Wireless systems have been under an evolutionary process along the time, in order
to satisfy the demanding user needs of these types of systems. Those needs and inquiries
of wireless markets have grown considerably in a short time. This fast market growth
has pushed companies to employ state of the art technology in order to use and share
trustworthy databases in an instantaneous and imperceptible way for the *nal user.
Ad Hoc mobile networks are being developed and implemented in order to solve and
satisfy the needs and problems of mobile users. This technology can be an actual solution
in which users demands good quality of service (QoS) in their personal communications
and internet devises, according to the current and future market needs.
Code Division Multiple Access (CDMA) seems to be the future wireless interface and,
because of its characteristics, it could play an important role in future communications
systems. Operational characteristics allow CDMA to be considered an adequate access
method for conventional and Ad Hoc networking systems. As a mentioned above, this work
will base its access method on CDMA, where the main limiting factor is the interference,
so here we will characterize the interference and the outage probability for an ad hoc linear
network for di*erent scenarios and di*erent physical conditions.
Gaussian processes for regression (GPR) is proposed as a novel detector for multiuser detection in DS-CDMA systems. GPR provides an analytical nonlinear multiuser detection solution where the parameters describing the nonlinearities can be computed optimally using maximum likelihood, without needing cross-validation. GPR has fast and accurate learning properties. It can be interpreted as a regularized linear minimum mean squared error detector, where the regularization parameter is optimally set during training. Experimental results show GPR outperforms linear and nonlinear state-of-the-art solutions for multiuser detection in DS-CDMA systems.
This document discusses peak-to-average power ratio (PAPR) reduction techniques for multicarrier code division multiple access (MC-CDMA) systems. MC-CDMA combines orthogonal frequency division multiplexing (OFDM) and code division multiple access (CDMA), but inherits the high PAPR problem from OFDM. High PAPR decreases power amplifier efficiency and causes signal distortion. Three main categories of PAPR reduction techniques are discussed: signal distortion, coding methods, and symbol scrambling. Signal distortion techniques like clipping reduce peaks but cause interference. Symbol scrambling techniques like selected mapping and partial transmit sequence modify signals to reduce PAPR with increased complexity. The document analyzes different PAPR reduction
Advancements in Complementary Metal Oxide Semiconductor (CMOS) technology have enabled Wireless Sensor Networks (WSN) to gather, process and transport multimedia (MM) data as well and not just limited to handling ordinary scalar data anymore. This new generation of WSN type is called Wireless Multimedia Sensor Networks (WMSNs). Better and yet relatively cheaper sensors – sensors that are able to sense both scalar data and multimedia data with more advanced functionalities such as being able to handle rather intense computations easily - have sprung up. In this paper, the applications, architectures, challenges and issues faced in the design of WMSNs are explored. Security and privacy issues, over all requirements, proposed and implemented solutions so far, some of the successful achievements and other related works in the field are also highlighted. Open research areas are pointed out and a few solution suggestions to the still persistent problems are made, which, to the best of my knowledge, so far haven’t been explored yet.
Language Support For Fast And Reliable Message Based Communication In S...alanocu
1. The document describes a communication system for the Singularity OS that uses message passing over channels as the sole means of inter-process communication.
2. Channels are bidirectional and consist of two endpoints that are statically typed. Channel contracts specify valid message types and sequences.
3. Safety is ensured through the use of a type-safe language and static verification that guarantees each block of shared memory is owned by only one thread at a time.
ANALYSIS OF ROBUST MILTIUSER DETECTION TECHNIQUE FOR COMMUNICATION SYSTEMIJARIIE JOURNAL
This document summarizes a research paper that analyzes a robust multiuser detection technique called Group Based Successive Interference Cancellation (GSIC) for communication systems. GSIC is a nonlinear approach that applies successive interference cancellation processing to groups of signals based on their strength, rather than individual signals. This technique aims to improve the bit error rate compared to conventional successive interference cancellation schemes by reducing delay and increasing signal-to-noise ratio. The document provides background on multiuser detection and CDMA systems, describes the GSIC technique and methodology used to analyze it through MATLAB simulations, and reviews related work on successive interference cancellation approaches.
The document discusses media access control (MAC) strategies for shared transmission media. It begins by explaining the need for MAC in cases where multiple users share a common channel. It then discusses different MAC approaches such as scheduling versus random access, centralized versus distributed control, and examples including TDMA, slotted ALOHA, and CSMA/CD. Key MAC influences like distance between stations, throughput requirements, traffic patterns are also covered. Specific MAC protocols discussed include those used in ISDN, Ethernet, GSM, and wireless networks.
A Cooperative Approach to Extend Cellular Coverage via D2D Architecture based...IJCNCJournal
The access part of all cellular network’s generation suffers from common concerns related to dead spots (zones that are not covered by the network) and hot spots (zones where the number of users is higher compared to network resources). During the last decade, lots of research proposals have tried to overcome cellular problems through multi-hop D2D architecture, which is a new paradigm allowing the direct communication between devices in cellular network to enhance network performances and improve user QoS. In this paper, we propose a multi-hop D2D architecture based on the OLSR protocol to extend cellular coverage. Cell-OLSR, which is the proposed adaptation of OLSR for our architecture, allows the exchange of cellular parameters between nodes to choose the best proxy device to forward data to the cellular base station (BS).
Interference aware resource allocation model for D2D under cellular network IJECEIAES
Device-to-Device communication (D2D) has emerged as an efficient communication model in future generation cellular network for offloading cellular traffic and enhance overall network performance. D2D communication aid in attaining better spectrum utilization, lower delay, and less energy consumption, which can well adapt to meet demand of higher transmission rate, larger network capacity. Further, enhances spectral efficiency by reutilizing resource. However, it may result in severe cross-tier interference and co-tier interference. Therefore, efficient interference modelling design are required to address performance degradation caused by the interferences. The existing model has focused on addressing interference considering D2D association operating on same cell with the cellular association. As a result, it incurs interference to the cellular user located in the same cell. However, practically D2D association in overlapping area will reutilize spectrum of multiple neighboring cells. As a result, it incurs interference in multiple cells. For overcoming research challenges, this work presented Interference Aware Resource Allocation (IARA) model for D2D under cellular network as a game theory model. This work consider a resource allocation game where base station as a contender for catering D2D resource needs under different assumptions. Experiment are conducted to evaluate performance of IARA. The outcome shows IARA attained significant performance improvement over state-of-art models in terms of sum rate (utility), successful packet transmission, revenue, and delay.
Gaussian processes for regression (GPR) is proposed as a novel detector for multiuser detection in DS-CDMA systems. GPR provides an analytical nonlinear multiuser detection solution where the parameters describing the nonlinearities can be computed optimally using maximum likelihood, without needing cross-validation. GPR has fast and accurate learning properties. It can be interpreted as a regularized linear minimum mean squared error detector, where the regularization parameter is optimally set during training. Experimental results show GPR outperforms linear and nonlinear state-of-the-art solutions for multiuser detection in DS-CDMA systems.
This document discusses peak-to-average power ratio (PAPR) reduction techniques for multicarrier code division multiple access (MC-CDMA) systems. MC-CDMA combines orthogonal frequency division multiplexing (OFDM) and code division multiple access (CDMA), but inherits the high PAPR problem from OFDM. High PAPR decreases power amplifier efficiency and causes signal distortion. Three main categories of PAPR reduction techniques are discussed: signal distortion, coding methods, and symbol scrambling. Signal distortion techniques like clipping reduce peaks but cause interference. Symbol scrambling techniques like selected mapping and partial transmit sequence modify signals to reduce PAPR with increased complexity. The document analyzes different PAPR reduction
Advancements in Complementary Metal Oxide Semiconductor (CMOS) technology have enabled Wireless Sensor Networks (WSN) to gather, process and transport multimedia (MM) data as well and not just limited to handling ordinary scalar data anymore. This new generation of WSN type is called Wireless Multimedia Sensor Networks (WMSNs). Better and yet relatively cheaper sensors – sensors that are able to sense both scalar data and multimedia data with more advanced functionalities such as being able to handle rather intense computations easily - have sprung up. In this paper, the applications, architectures, challenges and issues faced in the design of WMSNs are explored. Security and privacy issues, over all requirements, proposed and implemented solutions so far, some of the successful achievements and other related works in the field are also highlighted. Open research areas are pointed out and a few solution suggestions to the still persistent problems are made, which, to the best of my knowledge, so far haven’t been explored yet.
Language Support For Fast And Reliable Message Based Communication In S...alanocu
1. The document describes a communication system for the Singularity OS that uses message passing over channels as the sole means of inter-process communication.
2. Channels are bidirectional and consist of two endpoints that are statically typed. Channel contracts specify valid message types and sequences.
3. Safety is ensured through the use of a type-safe language and static verification that guarantees each block of shared memory is owned by only one thread at a time.
ANALYSIS OF ROBUST MILTIUSER DETECTION TECHNIQUE FOR COMMUNICATION SYSTEMIJARIIE JOURNAL
This document summarizes a research paper that analyzes a robust multiuser detection technique called Group Based Successive Interference Cancellation (GSIC) for communication systems. GSIC is a nonlinear approach that applies successive interference cancellation processing to groups of signals based on their strength, rather than individual signals. This technique aims to improve the bit error rate compared to conventional successive interference cancellation schemes by reducing delay and increasing signal-to-noise ratio. The document provides background on multiuser detection and CDMA systems, describes the GSIC technique and methodology used to analyze it through MATLAB simulations, and reviews related work on successive interference cancellation approaches.
The document discusses media access control (MAC) strategies for shared transmission media. It begins by explaining the need for MAC in cases where multiple users share a common channel. It then discusses different MAC approaches such as scheduling versus random access, centralized versus distributed control, and examples including TDMA, slotted ALOHA, and CSMA/CD. Key MAC influences like distance between stations, throughput requirements, traffic patterns are also covered. Specific MAC protocols discussed include those used in ISDN, Ethernet, GSM, and wireless networks.
A Cooperative Approach to Extend Cellular Coverage via D2D Architecture based...IJCNCJournal
The access part of all cellular network’s generation suffers from common concerns related to dead spots (zones that are not covered by the network) and hot spots (zones where the number of users is higher compared to network resources). During the last decade, lots of research proposals have tried to overcome cellular problems through multi-hop D2D architecture, which is a new paradigm allowing the direct communication between devices in cellular network to enhance network performances and improve user QoS. In this paper, we propose a multi-hop D2D architecture based on the OLSR protocol to extend cellular coverage. Cell-OLSR, which is the proposed adaptation of OLSR for our architecture, allows the exchange of cellular parameters between nodes to choose the best proxy device to forward data to the cellular base station (BS).
Interference aware resource allocation model for D2D under cellular network IJECEIAES
Device-to-Device communication (D2D) has emerged as an efficient communication model in future generation cellular network for offloading cellular traffic and enhance overall network performance. D2D communication aid in attaining better spectrum utilization, lower delay, and less energy consumption, which can well adapt to meet demand of higher transmission rate, larger network capacity. Further, enhances spectral efficiency by reutilizing resource. However, it may result in severe cross-tier interference and co-tier interference. Therefore, efficient interference modelling design are required to address performance degradation caused by the interferences. The existing model has focused on addressing interference considering D2D association operating on same cell with the cellular association. As a result, it incurs interference to the cellular user located in the same cell. However, practically D2D association in overlapping area will reutilize spectrum of multiple neighboring cells. As a result, it incurs interference in multiple cells. For overcoming research challenges, this work presented Interference Aware Resource Allocation (IARA) model for D2D under cellular network as a game theory model. This work consider a resource allocation game where base station as a contender for catering D2D resource needs under different assumptions. Experiment are conducted to evaluate performance of IARA. The outcome shows IARA attained significant performance improvement over state-of-art models in terms of sum rate (utility), successful packet transmission, revenue, and delay.
High Performance Data Bus Encoding Technique in DSM TechnologyIDES Editor
To increase the performance and reliability of
highly integrated circuits like DSP processors,
Microprocessors and SoCs, transistors sizes are continues to
scale towards Deep Submicron and Very Deep Submicron
dimensions . As more and more transistors are packed on the
chip to increase the functionality more metal layers are being
added to the integrated chips. Hence the performance of the
chips depends more on the performance of global interconnect
and on-chip busses than gate performance. The performance
of the global interconnects and on-chip data busses is limited
by switching activity, energy dissipation and noise such as
crosstalk, leakage, supply noise and process variations etc.
which are the side effects of the technology scaling. To increase
the performance of overall system it is necessary to control
and reduce these technology scaling effects on on-chip data
buses. One of the favorable techniques to increase the
efficiency of the data buses is to encode the data on the onchip
bus. Data encoding technique is the promising method to
increase the performance of the data bus and hence overall
system performance. Hence high performance data bus
encoding technique is propose which reduces switching
activity, transition energy dissipation, crosstalk and crosstalk
delay. The proposed method reduces the switching activity by
around 23%, energy dissipation by 46%, 6C, 5C and 4C type
crosstalk by around 89%, 73% and 31% respectively and
crosstalk delay by around 44% to 50% compare to unencoded
data.
- The document discusses requirements for distributed multimedia systems, including supporting continuous media streams, quality of service management, synchronization, and multiparty communications.
- It introduces two framework models for meeting these requirements: 1) A middleware platform that uses "binding objects" to establish and control quality of service for streaming multimedia between applications. 2) A framework providing different services and satisfying application requirements through service selection and integration in an IPv6 differentiated services environment.
- The key requirements discussed are the need to support continuous media streaming over long periods, sophisticated static and dynamic quality of service management, synchronization of multiple media streams, and programming/system support for multiparty communications.
The document discusses design verification (DV) in the past, present, and future. In the past, DV techniques were basic like visual inspection and code coverage was in its infancy. Now, DV has evolved with more research, texts, and use of techniques like constrained random testing and static verification. The future of DV faces challenges of dealing with increasing capacity needs and being smarter about reaching verification goals. Formal verification and new algorithms are emerging to help address these challenges.
The research of cognitive communication networksWatcharanon Over
The document discusses research on cognitive communication networks. It defines cognitive communication networks as networks that can (1) sense changes in their internal and external environments, (2) analyze and learn from these changes, and (3) automatically adjust communication resources and capabilities according to user demands. The key aspects covered are: the environments cognitive networks can sense; the connotation of cognitive network technology; and the sensing, learning, decision-making, and action process of cognitive networks.
This document discusses techniques for improving multiuser detection in DS-CDMA systems using successive interference cancellation. It begins with an introduction to the multiple access interference problem in CDMA systems and how multiuser detection can help address this issue. It then provides the system model for a CDMA uplink and describes the matched filter receiver structure. Next, it discusses multiuser detection algorithms and focuses on successive interference cancellation as a suboptimal but lower complexity method. The document describes the successive interference cancellation algorithm and introduces the groupwise successive interference cancellation technique, which provides cancellation in groups to handle multirate users. It provides a block diagram of the groupwise successive interference cancellation receiver and discusses how it works to sequentially detect and cancel the strongest user signals
Distributed Localization for Wireless Distributed Networks in Indoor Environm...Hermie Mendoza
This document summarizes Hermie Mendoza's Masters thesis defense presentation on distributed localization for wireless distributed networks. The presentation covers preliminaries on position location and wireless distributed computing, fingerprint-based positioning techniques, and a WDC-based fingerprinting system. Mendoza proposes distributed algorithms to solve the localization problem in a parallelized manner using a wireless distributed computing network. The algorithms discussed include distributed Euclidean distance, Bayesian modeling, and neural networks approaches. Experimental results from a prototype system using USRP software-defined radios are also presented.
Multi User Detection in CDMA System Using Linear and Non Linear DetectorWaqas Tariq
DS-Code division multiple access is considered as the third generation of cellular mobile used in interim standard 95(IS-95) [1]and it is currently being standardized for universal mobile telecommunication systems (UMTS). CDMA offers attractive features, such as frequency reuse, soft handoff, increased capacity, and multipath combating. In a CDMA system, several users simultaneously transmit information over a common channel using pre-assigned codes. The conventional single user detector consists of a bank of filters matched to the spreading codes. This detector suffers from two problems. First, multiple access interference (MAI) produced by the other co-channel users is a significant limitation to the capacity of this detector. The second problem is the near-far effect which occurs when the relative received power of interfering signals becomes larger. A potential solution is multi-user detection which exploits the information of signals of interfering users. In the present study performance of various linear detectors like matched filter detector, MMSE detector, and adaptive LMS detector are studied. These are the linear detectors that operate linearly on the received signal statistics and are suboptimal detectors. The matched filter bank is the conventional detector and offers the simplest way of demodulating CDMA signals .The detector resulting from the MMSE (minimum mean square error) criterion shows better performance over the conventional one for low SNR value. Adaptive LMS is employed to enhance the BER performance in MUD application.Several factors motivated the research to apply neural network as multi-user detector. NN are nonlinear classifier in addition to being adaptive and computationally efficient. The performance of two layer perceptron neural network using BP learning rule is used for multi-user detection of CDMA signals in AWGN channels. The neural network detectors show improvement of BER in the comparative analysis done in the present work. and offers further research scope for solving multi-user detection problems in CDMA application.
Iaetsd comparative study mimo ofdm, cdma-sdmaIaetsd Iaetsd
This document compares and contrasts MIMO OFDM, CDMA-SDMA, and multi-user detection techniques for wireless communication systems. It discusses how MIMO OFDM can achieve high data rates with frequency and antenna diversity. Space division multiple access (SDMA) is introduced as an application of MIMO that improves spectral efficiency by multiplexing signals based on spatial signatures. The document also examines multi-user detection methods like linear detection, minimum mean square error, and successive interference cancellation that are needed for robust SDMA performance as the number of users increases.
This document provides information on a distributed systems course, including its objectives, learning outcomes, synopsis, content outline, assessment, and grading points. The course aims to provide understanding of distributed systems and emphasize problems, principles, techniques, infrastructure, and applications. Key topics covered include communication, distributed objects, web services, security, naming/trading, time/coordination, concurrency control, transactions, and fault tolerance. Students will be assessed through coursework, a midterm, project, and final exam.
This document provides an overview of the applications of error-control coding over the past 50 years. It begins by discussing early applications in deep space communications, where coding provided significant power savings. The first coding scheme used for deep space, known as the Mariner code, achieved a power gain of 3.2 dB over uncoded BPSK but required higher bandwidth. More advanced codes were later developed that achieved gains close to the theoretical limits. The document then discusses how coding has been widely used in other areas such as satellite communications, data transmission, data storage, mobile communications and more to improve performance.
Dear Students
Ingenious techno Solution offers an expertise guidance on you Final Year IEEE & Non- IEEE Projects on the following domain
JAVA
.NET
EMBEDDED SYSTEMS
ROBOTICS
MECHANICAL
MATLAB etc
For further details contact us:
enquiry@ingenioustech.in
044-42046028 or 8428302179.
Ingenious Techno Solution
#241/85, 4th floor
Rangarajapuram main road,
Kodambakkam (Power House)
http://www.ingenioustech.in/
Cassandra framework a service oriented distributed multimediaJoão Gabriel Lima
This document describes the CASSANDRA framework, a distributed multimedia content analysis system. It uses a service-oriented architecture that allows individual analysis components to be integrated and upgraded easily. The system is modular, self-organizing, and real-time. It can dynamically distribute workloads across available devices. The framework allows for flexible integration of new analysis algorithms and coordination of existing algorithms from different domains.
GAME THEORY BASED INTERFERENCE CONTROL AND POWER CONTROL FOR D2D COMMUNICATIO...IJCNCJournal
With the current development of mobile communication services, people need personal communication of
high speed, excellent service, high quality and low latency,however, limited spectrum resources become
the most important factor to hamper improvement of cellular systems. As big amount of data traffic will
cause greater local consumption of spectrum resources, future networks are required to have appropriate
techniques to better support such forms of communication. D2D (Device-to-device) communication
technology in a cellular network makes full use of spectrum resources underlaying, reduces the load of the
base station, minimizes transmit power of the terminals and the base stations, thereby enhances the overall
throughput of the networks. Due to the use of multiplexing D2D UE (User equipment) resources and
spectrum, and the interference caused by the sharing of resources between adjacent cells, it has become a
major factor affecting coexisting of cellular subscribers and D2D users. When D2D communication
multiplexes the uplink resources, the base-stations are easily to be disturbed; when the downlink resources
are multiplexed, the users of downlink are susceptible to interference. In order to build a high-efficient
mobile network, we can meet the QoS requirements by controlling the power to suppress the interference
between the base station and a terminal user.
Maximize resource utilization based channel access model with presence of re...IJECEIAES
Underwater sensor networks (UWSNs) are vulnerable to jamming attacks. Especially, reactive jamming which emerged as a greatest security threat to UWSNs. Reactive jammer are difficult to be removed, defended and identified. Since reactive jammer can control and regulate (i.e., the duration of the jam signal) the probability of jamming for maintaining high vulnerability with low detection probability. The existing model are generally designed considering terrestrial wireless sensor networks (TWSNs). Further, these models are limited in their ability to detect jamming correctly, distinguish between the corrupted and uncorrupted parts of a packet, and be adaptive with the dynamic environment. Cooperative jamming model has presented in recent times to utilize resource efficiently. However, very limited work is carried out using cooperative jamming detection. For overcoming research challenges, this work present Maximize Resource Utilization based Channel Access (MRUCA). The MRUCA uses cross layer design for mitigating reactive jammer (i.e., MRUCA jointly optimizes the cooperative hopping probabilities and channel accessibility probabilities of authenticated sensor device). Along with channel, load capacity of authenticated sensor device is estimated to utilize (maximize) resource efficiently. Experiment outcome shows the proposed MRUCA model attain superior performance than state-of-art model in terms of packet transmission, BER and Detection rate.
Contemporary Spread Spectrum Techniques: A Comparative StudyIJERD Editor
Anti-jamming is an important problem in broadcast communication. In this paper , we provide an
overview of recent contributions pertaining to the anti-jamming techniques. Specifically, the paper focuses on
comparative study of anti-jamming techniques‟ performance against jammers. Due to secret key sharing
between sender and receiver in classical Spread spectrum techniques, Anti-jamming Broadcast problem arises.
To have jamming resistant communication, Uncoordinated SS, Randomized differential-DSSS, Quorum
Rendezvous Channel Hopping are proposed and implemented in the respective domain of communication. From
the discussion provided in this paper, it is concluded that the brief review of anti-jamming techniques can help
the researchers to understand the functionality and practical applications of the techniques based on DSSS and
FHSS.
Qhuba is a network organization founded in 2007 that provides executives, IT project delivery, and consultancy services. It exists to successfully implement strategies through collaboration between competent and trustworthy individuals. Qhuba's business model involves providing interim staff to clients based on their needs and competencies within the network. The document outlines Qhuba's values, roles, strategy principles, and goals for building its network and knowledge sharing to generate over €7 million in revenue and €200 million in customer benefits by executing strategies.
The document repeatedly states "ilove to run" across multiple lines. It expresses an enjoyment of running through frequent short statements of "ilove to run".
Fall in love with beautiful Oriental cats.
Cats with attitude!
* need to download presentation to hear accompanying music that goes with the presentation.
Qhuba is a fast-growing strategy execution network of over 60 partners, staff, and associates with expertise in management, technology, HR, and finance. It was founded in 2007 to help companies adapt quickly to changing markets by assembling knowledge across disciplines and implementing strategies. Qhuba provides world-class consulting services through practices in interim management, recruitment, program management, transformation, and disciplines to make clients successful. It takes a SCOPE approach of strategy, context, organization, planning, and execution to bring business ideas to fruition.
High Performance Data Bus Encoding Technique in DSM TechnologyIDES Editor
To increase the performance and reliability of
highly integrated circuits like DSP processors,
Microprocessors and SoCs, transistors sizes are continues to
scale towards Deep Submicron and Very Deep Submicron
dimensions . As more and more transistors are packed on the
chip to increase the functionality more metal layers are being
added to the integrated chips. Hence the performance of the
chips depends more on the performance of global interconnect
and on-chip busses than gate performance. The performance
of the global interconnects and on-chip data busses is limited
by switching activity, energy dissipation and noise such as
crosstalk, leakage, supply noise and process variations etc.
which are the side effects of the technology scaling. To increase
the performance of overall system it is necessary to control
and reduce these technology scaling effects on on-chip data
buses. One of the favorable techniques to increase the
efficiency of the data buses is to encode the data on the onchip
bus. Data encoding technique is the promising method to
increase the performance of the data bus and hence overall
system performance. Hence high performance data bus
encoding technique is propose which reduces switching
activity, transition energy dissipation, crosstalk and crosstalk
delay. The proposed method reduces the switching activity by
around 23%, energy dissipation by 46%, 6C, 5C and 4C type
crosstalk by around 89%, 73% and 31% respectively and
crosstalk delay by around 44% to 50% compare to unencoded
data.
- The document discusses requirements for distributed multimedia systems, including supporting continuous media streams, quality of service management, synchronization, and multiparty communications.
- It introduces two framework models for meeting these requirements: 1) A middleware platform that uses "binding objects" to establish and control quality of service for streaming multimedia between applications. 2) A framework providing different services and satisfying application requirements through service selection and integration in an IPv6 differentiated services environment.
- The key requirements discussed are the need to support continuous media streaming over long periods, sophisticated static and dynamic quality of service management, synchronization of multiple media streams, and programming/system support for multiparty communications.
The document discusses design verification (DV) in the past, present, and future. In the past, DV techniques were basic like visual inspection and code coverage was in its infancy. Now, DV has evolved with more research, texts, and use of techniques like constrained random testing and static verification. The future of DV faces challenges of dealing with increasing capacity needs and being smarter about reaching verification goals. Formal verification and new algorithms are emerging to help address these challenges.
The research of cognitive communication networksWatcharanon Over
The document discusses research on cognitive communication networks. It defines cognitive communication networks as networks that can (1) sense changes in their internal and external environments, (2) analyze and learn from these changes, and (3) automatically adjust communication resources and capabilities according to user demands. The key aspects covered are: the environments cognitive networks can sense; the connotation of cognitive network technology; and the sensing, learning, decision-making, and action process of cognitive networks.
This document discusses techniques for improving multiuser detection in DS-CDMA systems using successive interference cancellation. It begins with an introduction to the multiple access interference problem in CDMA systems and how multiuser detection can help address this issue. It then provides the system model for a CDMA uplink and describes the matched filter receiver structure. Next, it discusses multiuser detection algorithms and focuses on successive interference cancellation as a suboptimal but lower complexity method. The document describes the successive interference cancellation algorithm and introduces the groupwise successive interference cancellation technique, which provides cancellation in groups to handle multirate users. It provides a block diagram of the groupwise successive interference cancellation receiver and discusses how it works to sequentially detect and cancel the strongest user signals
Distributed Localization for Wireless Distributed Networks in Indoor Environm...Hermie Mendoza
This document summarizes Hermie Mendoza's Masters thesis defense presentation on distributed localization for wireless distributed networks. The presentation covers preliminaries on position location and wireless distributed computing, fingerprint-based positioning techniques, and a WDC-based fingerprinting system. Mendoza proposes distributed algorithms to solve the localization problem in a parallelized manner using a wireless distributed computing network. The algorithms discussed include distributed Euclidean distance, Bayesian modeling, and neural networks approaches. Experimental results from a prototype system using USRP software-defined radios are also presented.
Multi User Detection in CDMA System Using Linear and Non Linear DetectorWaqas Tariq
DS-Code division multiple access is considered as the third generation of cellular mobile used in interim standard 95(IS-95) [1]and it is currently being standardized for universal mobile telecommunication systems (UMTS). CDMA offers attractive features, such as frequency reuse, soft handoff, increased capacity, and multipath combating. In a CDMA system, several users simultaneously transmit information over a common channel using pre-assigned codes. The conventional single user detector consists of a bank of filters matched to the spreading codes. This detector suffers from two problems. First, multiple access interference (MAI) produced by the other co-channel users is a significant limitation to the capacity of this detector. The second problem is the near-far effect which occurs when the relative received power of interfering signals becomes larger. A potential solution is multi-user detection which exploits the information of signals of interfering users. In the present study performance of various linear detectors like matched filter detector, MMSE detector, and adaptive LMS detector are studied. These are the linear detectors that operate linearly on the received signal statistics and are suboptimal detectors. The matched filter bank is the conventional detector and offers the simplest way of demodulating CDMA signals .The detector resulting from the MMSE (minimum mean square error) criterion shows better performance over the conventional one for low SNR value. Adaptive LMS is employed to enhance the BER performance in MUD application.Several factors motivated the research to apply neural network as multi-user detector. NN are nonlinear classifier in addition to being adaptive and computationally efficient. The performance of two layer perceptron neural network using BP learning rule is used for multi-user detection of CDMA signals in AWGN channels. The neural network detectors show improvement of BER in the comparative analysis done in the present work. and offers further research scope for solving multi-user detection problems in CDMA application.
Iaetsd comparative study mimo ofdm, cdma-sdmaIaetsd Iaetsd
This document compares and contrasts MIMO OFDM, CDMA-SDMA, and multi-user detection techniques for wireless communication systems. It discusses how MIMO OFDM can achieve high data rates with frequency and antenna diversity. Space division multiple access (SDMA) is introduced as an application of MIMO that improves spectral efficiency by multiplexing signals based on spatial signatures. The document also examines multi-user detection methods like linear detection, minimum mean square error, and successive interference cancellation that are needed for robust SDMA performance as the number of users increases.
This document provides information on a distributed systems course, including its objectives, learning outcomes, synopsis, content outline, assessment, and grading points. The course aims to provide understanding of distributed systems and emphasize problems, principles, techniques, infrastructure, and applications. Key topics covered include communication, distributed objects, web services, security, naming/trading, time/coordination, concurrency control, transactions, and fault tolerance. Students will be assessed through coursework, a midterm, project, and final exam.
This document provides an overview of the applications of error-control coding over the past 50 years. It begins by discussing early applications in deep space communications, where coding provided significant power savings. The first coding scheme used for deep space, known as the Mariner code, achieved a power gain of 3.2 dB over uncoded BPSK but required higher bandwidth. More advanced codes were later developed that achieved gains close to the theoretical limits. The document then discusses how coding has been widely used in other areas such as satellite communications, data transmission, data storage, mobile communications and more to improve performance.
Dear Students
Ingenious techno Solution offers an expertise guidance on you Final Year IEEE & Non- IEEE Projects on the following domain
JAVA
.NET
EMBEDDED SYSTEMS
ROBOTICS
MECHANICAL
MATLAB etc
For further details contact us:
enquiry@ingenioustech.in
044-42046028 or 8428302179.
Ingenious Techno Solution
#241/85, 4th floor
Rangarajapuram main road,
Kodambakkam (Power House)
http://www.ingenioustech.in/
Cassandra framework a service oriented distributed multimediaJoão Gabriel Lima
This document describes the CASSANDRA framework, a distributed multimedia content analysis system. It uses a service-oriented architecture that allows individual analysis components to be integrated and upgraded easily. The system is modular, self-organizing, and real-time. It can dynamically distribute workloads across available devices. The framework allows for flexible integration of new analysis algorithms and coordination of existing algorithms from different domains.
GAME THEORY BASED INTERFERENCE CONTROL AND POWER CONTROL FOR D2D COMMUNICATIO...IJCNCJournal
With the current development of mobile communication services, people need personal communication of
high speed, excellent service, high quality and low latency,however, limited spectrum resources become
the most important factor to hamper improvement of cellular systems. As big amount of data traffic will
cause greater local consumption of spectrum resources, future networks are required to have appropriate
techniques to better support such forms of communication. D2D (Device-to-device) communication
technology in a cellular network makes full use of spectrum resources underlaying, reduces the load of the
base station, minimizes transmit power of the terminals and the base stations, thereby enhances the overall
throughput of the networks. Due to the use of multiplexing D2D UE (User equipment) resources and
spectrum, and the interference caused by the sharing of resources between adjacent cells, it has become a
major factor affecting coexisting of cellular subscribers and D2D users. When D2D communication
multiplexes the uplink resources, the base-stations are easily to be disturbed; when the downlink resources
are multiplexed, the users of downlink are susceptible to interference. In order to build a high-efficient
mobile network, we can meet the QoS requirements by controlling the power to suppress the interference
between the base station and a terminal user.
Maximize resource utilization based channel access model with presence of re...IJECEIAES
Underwater sensor networks (UWSNs) are vulnerable to jamming attacks. Especially, reactive jamming which emerged as a greatest security threat to UWSNs. Reactive jammer are difficult to be removed, defended and identified. Since reactive jammer can control and regulate (i.e., the duration of the jam signal) the probability of jamming for maintaining high vulnerability with low detection probability. The existing model are generally designed considering terrestrial wireless sensor networks (TWSNs). Further, these models are limited in their ability to detect jamming correctly, distinguish between the corrupted and uncorrupted parts of a packet, and be adaptive with the dynamic environment. Cooperative jamming model has presented in recent times to utilize resource efficiently. However, very limited work is carried out using cooperative jamming detection. For overcoming research challenges, this work present Maximize Resource Utilization based Channel Access (MRUCA). The MRUCA uses cross layer design for mitigating reactive jammer (i.e., MRUCA jointly optimizes the cooperative hopping probabilities and channel accessibility probabilities of authenticated sensor device). Along with channel, load capacity of authenticated sensor device is estimated to utilize (maximize) resource efficiently. Experiment outcome shows the proposed MRUCA model attain superior performance than state-of-art model in terms of packet transmission, BER and Detection rate.
Contemporary Spread Spectrum Techniques: A Comparative StudyIJERD Editor
Anti-jamming is an important problem in broadcast communication. In this paper , we provide an
overview of recent contributions pertaining to the anti-jamming techniques. Specifically, the paper focuses on
comparative study of anti-jamming techniques‟ performance against jammers. Due to secret key sharing
between sender and receiver in classical Spread spectrum techniques, Anti-jamming Broadcast problem arises.
To have jamming resistant communication, Uncoordinated SS, Randomized differential-DSSS, Quorum
Rendezvous Channel Hopping are proposed and implemented in the respective domain of communication. From
the discussion provided in this paper, it is concluded that the brief review of anti-jamming techniques can help
the researchers to understand the functionality and practical applications of the techniques based on DSSS and
FHSS.
Qhuba is a network organization founded in 2007 that provides executives, IT project delivery, and consultancy services. It exists to successfully implement strategies through collaboration between competent and trustworthy individuals. Qhuba's business model involves providing interim staff to clients based on their needs and competencies within the network. The document outlines Qhuba's values, roles, strategy principles, and goals for building its network and knowledge sharing to generate over €7 million in revenue and €200 million in customer benefits by executing strategies.
The document repeatedly states "ilove to run" across multiple lines. It expresses an enjoyment of running through frequent short statements of "ilove to run".
Fall in love with beautiful Oriental cats.
Cats with attitude!
* need to download presentation to hear accompanying music that goes with the presentation.
Qhuba is a fast-growing strategy execution network of over 60 partners, staff, and associates with expertise in management, technology, HR, and finance. It was founded in 2007 to help companies adapt quickly to changing markets by assembling knowledge across disciplines and implementing strategies. Qhuba provides world-class consulting services through practices in interim management, recruitment, program management, transformation, and disciplines to make clients successful. It takes a SCOPE approach of strategy, context, organization, planning, and execution to bring business ideas to fruition.
- The surveys from Blackshear Elementary students, parents, and staff provided feedback on various aspects of the school. Students felt positively about their teachers and learning. Parents were generally satisfied with the school's academics and environment. Staff believed in high expectations for students and staff.
While it is commonly believed that digital natives require new teaching strategies, the author argues that this assumption lacks evidence. The author acknowledges that digital natives are immersed in technology but asserts that multitasking may hinder learning. Lectures and discussions, when implemented engagingly, can still effectively teach digital natives traditional content while allowing for different learning styles. More research is needed before concluding that new strategies are necessary for digital natives to learn.
1. O senador Jarbas Vasconcelos defendeu a necessidade de uma reforma política séria no Brasil para combater a degradação do sistema político e a corrupção.
2. Ele propôs que a reforma política inclua financiamento público de campanha, fidelidade partidária, fim das coligações em eleições proporcionais e a implantação da cláusula de desempenho.
3. O senador também anunciou que apresentará um projeto de lei proibindo indicações partidárias para diretorias financeiras de estatais
Web 2.0 permite la participación de los usuarios a través de servicios como Del.ici.us, Wikis, Blogs, Edublogs, Podcasts, Videocasts y licencias Creative Commons, así como software libre, donde los nativos e inmigrantes digitales pueden aprender e interactuar.
Este documento presenta una organización que ha estado creando productos personalizados durante más de dos décadas. Ofrece diseño de calzado a medida y servicios para crear artículos de moda personalizados según los deseos del cliente.
The 2nd Annual Doggie Fest is a fundraiser for H.O.P.E Safehouse, a nonprofit that helps abandoned animals, taking place on Saturday, July 18th 2009 from 9am to 2pm at Proper Paws University in Racine, WI. The event will include activities, snacks, and fun for dogs and their owners, with all proceeds benefiting H.O.P.E Safehouse.
This document contains information about recruitment and retention strategies for different generations in the workforce. It discusses engaging mature workers, recognizing the different imprints that shape how generations translate work values, and the importance of aligning an organization's interests with its people. The document advocates paying attention to the voices of candidates, adapting roles to individuals, and removing barriers to knowledge transfer between generations.
This document discusses sculpture and fabrication. Sculpture involves shaping or combining materials like clay, metal, or wood to form representational or abstract three-dimensional art. Fabrication is the process of manufacturing parts precisely and involves techniques like welding, molding, and computer numerical control to shape materials like metal into parts, components, or finished products. Both sculpture and fabrication involve manipulating and shaping materials into three-dimensional forms through various techniques.
This document provides information about conducting marketing research for entrepreneurs and small businesses. It discusses:
- The importance of understanding the competitive landscape and having good market intelligence to make better business decisions.
- How competitive intelligence can help businesses improve planning, develop strategies, avoid surprises, and increase sales.
- Common approaches small businesses take to competitive intelligence that are ineffective and don't provide a true return on investment.
- Key aspects of market research small businesses should consider like understanding customers, products/services, competition, and purpose of research.
- Types of marketing research, budget considerations, and resources available to small businesses for conducting research projects.
A princesa Briolanja estava triste por não ter um noivo e parte em busca de um príncipe. Após retornar sem sucesso, seus pais organizam um baile onde ela conhece o príncipe Filipe. No entanto, ele foge assustado e ela cai em um lago de sapos, sendo resgatada por Filipe. Os dois se apaixonam.
Pazarlama ve üst yönetim aynı lisanı nasıl konuşur?
Pazarlama iletişimi tek bir birim ile nasıl ölçülür?
İletişimin etkinliği ve verimliliği nasıl arttırılır?
A Survey of MAC Layer Issues and Application layer Protocols for Machine-to-M...IRJET Journal
This document discusses challenges at the MAC layer for machine-to-machine (M2M) communications. It first describes issues around efficient, scalable and fair channel access for large numbers of M2M devices. It then discusses application layer protocols used to connect devices and applications to the internet, including CoAP, MQTT, and WebSocket. Finally, it analyzes MAC layer issues for a smart home example using M2M for power management, security and assisted living for the elderly. Key challenges include supporting diverse quality of service needs, large numbers of devices sharing channels, energy efficiency needs, and low-cost hardware requirements.
The document discusses career opportunities in the field of wireless communication. It begins with an overview of wireless communication and how it allows transfer of information without wires. It then discusses the developments in the field and various career opportunities, including analog and digital communications engineers, coding and modulation engineers, mobile applications developers, software platform architects, and wireless medical technology developers. The document concludes by listing several major companies that offer job opportunities in the wireless communication field, such as AT&T, Vodafone, Cisco, IBM, and Amazon.
A wireless sensor network has important applications such as remote environmental monitoring and target tracking, particularly in recent years with the help of sensors that are smaller, cheaper, and intelligent. Sensors are equipped with wireless interfaces with which they can communicate with one another to form a network. A WSN consists of a number of sensor nodes (few tens to thousands) working together to monitor a region to obtain data about the environment. The design of a WSN depends significantly on the application, and it must consider factors such as the environment, the applications design objectives, cost, hardware, and system constraints.
Current Activities in WSN: Developing test bed for target tracking Using Passive Infrared and Ultrasonic Sensors Improving the delivery rate in low power wireless networks .Guided Navigation of Friendly Vehicle towards tracked Object. Design and development of smart mines and explosive ordinance for intelligent activation and deactivation and safe recovery based on secure WSN. Design of a data mule for data collection from remotely placed sensor nodes
The course gives the thorough concepts of the wireless sensor networks, applications examples. It also gives detailed study of sensor node architecture and various protocols used in wireless sensor networks. It also covers issues related to topology, clustering ,synchronization and operating execution environment used for wireless sensor networks.
Wideband Sensing for Cognitive Radio Systems in Heterogeneous Next Generation...CSCJournals
Mobile Next Generation Network (MNGN) is characterized as heterogeneous network where variety of access technologies are meant to coexist. Decisions on choosing an air interface that meets a particular need at a particular time will be shifted from the network’s side to (a more intelligent) user’s side. On top of that network operators and regularities have come to the realization that assigned spectrum bands are not utilized as they should be. Cognitive radio stands out as a candidate technology to address many emerging issues in MNGN such as capacity, quality of service and spectral efficiency. As a transmission strategy, cognitive radio systems depend greatly on sensing the radio environment. In this paper, we present a novel approach for interference characterization in cognitive radio networks based on wideband chirp signal. The results presented show that improved sensing accuracy is maintained at tolerable system complexity.
The document discusses optical OFDM for passive optical networks. It describes how PON uses either TDM or WDM to connect multiple ONUs to an OLT, with TDM requiring complex scheduling and WDM extending the reach of PON. PON provides a cost effective solution for optical access networks to meet increasing bandwidth demands through either point-to-point or point-to-multipoint topologies.
An efficient transport protocol for delivery of multimedia content in wireles...Alexander Decker
1. The document proposes an efficient transport protocol called the Multimedia Grid Protocol (MMGP) for delivering multimedia content over wireless grids.
2. MMGP aims to provide faster, reliable access and high quality of service when streaming multimedia over wireless grid networks, which face challenges like intermittent connectivity, device heterogeneity, weak security, and device mobility.
3. The protocol incorporates a new video compression algorithm called dWave to make streaming more efficient over bandwidth-constrained wireless networks.
Cognitive radio is an enhancement of software defined radio that allows radios to sense their environment and change operating parameters accordingly. It was first proposed in 1998 as a way to more efficiently utilize limited radio frequency spectrum. A cognitive radio can sense available portions of spectrum, then dynamically use those available channels while avoiding occupied ones. This allows for greater spectrum utilization and more flexible interoperability between different wireless technologies. However, cognitive radio also faces significant hardware and software challenges around dynamic reconfiguration, interference avoidance, and security that must be addressed for it to be fully realized.
Introduction to M2M
What is M2M?
The Business of M2M
Accelerating M2M Maturity
M2M Standards
The Business of M2M
The M2M Market
The M2M Market Adoption: Drivers and Barriers
The M2M Value Chain
Market Size Projections
Business Models
M2M Business Metrics
Market Evolution
Early M2M Deployments
M2M Requirements and High-Level Architectural Principles
Use-Case-Driven Approach to M2M Requirements
Smart Metering Approach in ETSI M2M
eHealth Approach in ETSI M2M
High-Level Architecture Principles for M2M Communication
ETSI M2M Services Architecture
High-Level System Architecture
ETSI TC M2M Service Capabilities Framework
ETSI TC M2M Release 1 Scenarios
ETSI M2M Service Capabilities
Introducing REST Architectural Style for M2M
ETSI TC M2M Resource-Based M2M Communication and Procedures
This document summarizes research on enhancing the DSR routing protocol to prevent distributed denial of service (DDoS) attacks in mobile ad hoc networks (MANETs). It discusses how DDoS attacks work, the challenges they present for MANETs due to their dynamic nature, and existing research on DDoS attack detection and prevention. The document reviews literature on analyzing DDoS attack behaviors and properties, characterizing attack traffic patterns, and using statistical analysis and neural networks to identify attacks. The goal of the research is to develop an enhanced DSR protocol that can detect and mitigate DDoS attacks in MANETs more effectively than previous approaches.
Acoustic event characterization for service robot using convolutional networksIJECEIAES
This paper presents and discusses the creation of a sound event classification model using deep learning. In the design of service robots, it is necessary to include routines that improve the response of both the robot and the human being throughout the interaction. These types of tasks are critical when the robot is taking care of children, the elderly, or people in vulnerable situations. Certain dangerous situations are difficult to identify and assess by an autonomous system, and yet, the life of the users may depend on these robots. Acoustic signals correspond to events that can be detected at a great distance, are usually present in risky situations, and can be continuously sensed without incurring privacy risks. For the creation of the model, a customized database is structured with seven categories that allow to categorize a problem, and eventually allow the robot to provide the necessary help. These audio signals are processed to produce graphical representations consistent with human acoustic identification. These images are then used to train three convolutional models identified as high-performing in this type of problem. The three models are evaluated with specific metrics to identify the best-performing model. Finally, the results of this evaluation are discussed and analyzed.
Taming limits with approximate networkingJunaid Qadir
Internet is the linchpin of modern society, which the various threads of modern life weave around. But being a part of the bigger energy- guzzling industrial economy, it is vulnerable to disruption. It is widely believed that our society is exhausting its vital resources to meet our energy requirements, and the cheap fossil fuel fiesta will soon abate as we cross the tipping point of global oil production. We will then enter the long arc of scarcity, constraints, and limits— a post-peak “long emergency” that may subsist for a long time. To avoid the collapse of the networking ecosystem in this long emer- gency, it is imperative that we start thinking about how network- ing should adapt to these adverse “undeveloping” societal condi- tions. We propose using the idea of “approximate networking”— which will provide good-enough networking services by employ- ing contextually-appropriate tradeoffs—to survive, or even thrive, in the conditions of scarcity and limits.
See the video at: https://www.youtube.com/watch?v=4hKvgIi-HZY
This document analyzes routing protocols in wireless mesh networks (WMNs) using certain parameters like delay, throughput, and network load. It discusses security challenges in WMNs and proposes a security model. It also describes WMN protocols and simulation parameters. The paper then simulates three routing protocols (AODV, DSR, OLSR) in OPNET Modeler and displays the results in graphs to analyze protocol performance based on the parameters.
Machine-Type-Communication in 5G Cellular System-Li_Yue_PhD_2018.pdfYAAKOVSOLOMON1
This document is a dissertation submitted by Yue Li for the degree of Doctor of Philosophy at the University of Victoria. The dissertation focuses on improving transmission efficiency for machine-type communication (MTC) devices in 5G cellular systems. Specifically, it proposes applying network coding and device-to-device communications to MTC devices to improve efficiency. It also proposes using floating relays deployed via unmanned aerial vehicles to proactively improve channel quality for MTC devices experiencing high shadowing. The dissertation provides theoretical analyses and performance evaluations of the proposed approaches.
Improvement of quality of service parameters using reinvented fsmac protocol ...eSAT Journals
This document discusses improving quality of service parameters in wireless sensor networks using a reinvented FSMAC protocol. The FSMAC protocol first uses fuzzy logic to detect intrusions based on two new parameters: the number of times a node senses a free channel and the variation in channel sense periods. If an intrusion is detected, appropriate countermeasures are taken to reduce the effects of attacks. Simulations with 20 nodes show that the reinvented FSMAC protocol increases successful data transmission rates and network throughput.
This document discusses improving quality of service parameters in wireless sensor networks using a reinvented fuzzy logic secure media access control (FSMAC) protocol. It proposes using two new intrusion detection parameters - the number of times a node senses a free channel and the variation in the channel sense period. The protocol uses fuzzy logic to detect intrusions based on these parameters. If an intrusion is detected, the defense module is triggered to switch nodes to a different radio frequency band or stop transmissions to avoid attacks. Simulations with 20 nodes show this approach can increase successful data transmission rates and network throughput.
This document outlines the course objectives, outcomes, and content for a Wireless Sensor Networks course. The course objectives are to determine network architecture, node discovery, deployment strategies, fault tolerance, network security, and challenges of wireless networking at various protocol layers. The course content includes an overview of wireless sensor networks, network architectures, single node architecture and components, energy consumption, operating systems, and gateway concepts. It provides modules on topics such as applications, enabling technologies, and optimization goals.
Research Challenges and Characteristic Features in Wireless Sensor NetworksEswar Publications
Wireless Sensor Networks have come to the forefront of the scientific community recently and it consists of small nodes with sensing, Communications and computing capabilities. The Wireless Sensor Network Systems can be applied to monitor different environments ranging from military to civil applications. It is observed that different protocols necessary for smooth functioning of the network system are highly application specific. Current WSNs typically communicate directly with a centralized controller or satellite. In this paper we survey the different research challenges in Wireless Sensor Networks and purpose of various research Challenges activities is the development of a framework, which is radically simplifies the development of software for sensor network applications and characteristic Features of Sensor Networks.
The document provides an introduction to the Global Internet of Things (IoT). It defines IoT as a system of interconnected computing devices, machines, objects, animals or people that can transfer data over a network without requiring human interaction. It discusses how IoT is the next phase of development after the Internet of computers and mobile phones. The document outlines several key technologies that enable IoT, including RFID, wireless networks, sensors, cloud computing and energy harvesting. It also discusses the architecture, applications, market and impact of digital transformation of IoT.
Cognitive radio technology aims to tackle frequency shortage and misuse by allowing radios to detect unused spectrum and adapt transmission parameters. It was introduced by Mitola in 1999 to define radios that can evaluate their environment, decide transmission parameters, and learn from experience. The technology faces challenges in reliably sensing primary users, distinguishing them from noise, and developing commercial applications. If these challenges can be addressed, cognitive radio networks may offer a robust wireless connection between many intelligent devices regardless of location.
Analysis and assessment software for multi-user collaborative cognitive radi...IJECEIAES
Computer simulations are without a doubt a useful methodology that allows to explore research queries and develop prototypes at lower costs and timeframes than those required in hardware processes. The simulation tools used in cognitive radio networks (CRN) are undergoing an active process. Currently, there is no stable simulator that enables to characterize every element of the cognitive cycle and the available tools are a framework for discrete-event software. This work presents the spectral mobility simulator in CRN called “App MultiColl-DCRN”, developed with MATLAB’s app designer. In contrast with other frameworks, the simulator uses real spectral occupancy data and simultaneously analyzes features regarding spectral mobility, decision-making, multi-user access, collaborative scenarios and decentralized architectures. Performance metrics include bandwidth, throughput level, number of failed handoffs, number of total handoffs, number of handoffs with interference, number of anticipated handoffs and number of perfect handoffs. The assessment of the simulator involves three scenarios: the first and second scenarios present a collaborative structure using the multi-criteria optimization and compromise solution (VIKOR) decision-making model and the naïve Bayes prediction technique respectively. The third scenario presents a multi-user structure and uses simple additive weighting (SAW) as a decision-making technique. The present development represents a contribution in the cognitive radio network field since there is currently no software with the same features.
Must Know Postgres Extension for DBA and Developer during MigrationMydbops
Mydbops Opensource Database Meetup 16
Topic: Must-Know PostgreSQL Extensions for Developers and DBAs During Migration
Speaker: Deepak Mahto, Founder of DataCloudGaze Consulting
Date & Time: 8th June | 10 AM - 1 PM IST
Venue: Bangalore International Centre, Bangalore
Abstract: Discover how PostgreSQL extensions can be your secret weapon! This talk explores how key extensions enhance database capabilities and streamline the migration process for users moving from other relational databases like Oracle.
Key Takeaways:
* Learn about crucial extensions like oracle_fdw, pgtt, and pg_audit that ease migration complexities.
* Gain valuable strategies for implementing these extensions in PostgreSQL to achieve license freedom.
* Discover how these key extensions can empower both developers and DBAs during the migration process.
* Don't miss this chance to gain practical knowledge from an industry expert and stay updated on the latest open-source database trends.
Mydbops Managed Services specializes in taking the pain out of database management while optimizing performance. Since 2015, we have been providing top-notch support and assistance for the top three open-source databases: MySQL, MongoDB, and PostgreSQL.
Our team offers a wide range of services, including assistance, support, consulting, 24/7 operations, and expertise in all relevant technologies. We help organizations improve their database's performance, scalability, efficiency, and availability.
Contact us: info@mydbops.com
Visit: https://www.mydbops.com/
Follow us on LinkedIn: https://in.linkedin.com/company/mydbops
For more details and updates, please follow up the below links.
Meetup Page : https://www.meetup.com/mydbops-databa...
Twitter: https://twitter.com/mydbopsofficial
Blogs: https://www.mydbops.com/blog/
Facebook(Meta): https://www.facebook.com/mydbops/
Essentials of Automations: Exploring Attributes & Automation ParametersSafe Software
Building automations in FME Flow can save time, money, and help businesses scale by eliminating data silos and providing data to stakeholders in real-time. One essential component to orchestrating complex automations is the use of attributes & automation parameters (both formerly known as “keys”). In fact, it’s unlikely you’ll ever build an Automation without using these components, but what exactly are they?
Attributes & automation parameters enable the automation author to pass data values from one automation component to the next. During this webinar, our FME Flow Specialists will cover leveraging the three types of these output attributes & parameters in FME Flow: Event, Custom, and Automation. As a bonus, they’ll also be making use of the Split-Merge Block functionality.
You’ll leave this webinar with a better understanding of how to maximize the potential of automations by making use of attributes & automation parameters, with the ultimate goal of setting your enterprise integration workflows up on autopilot.
What is an RPA CoE? Session 1 – CoE VisionDianaGray10
In the first session, we will review the organization's vision and how this has an impact on the COE Structure.
Topics covered:
• The role of a steering committee
• How do the organization’s priorities determine CoE Structure?
Speaker:
Chris Bolin, Senior Intelligent Automation Architect Anika Systems
"Frontline Battles with DDoS: Best practices and Lessons Learned", Igor IvaniukFwdays
At this talk we will discuss DDoS protection tools and best practices, discuss network architectures and what AWS has to offer. Also, we will look into one of the largest DDoS attacks on Ukrainian infrastructure that happened in February 2022. We'll see, what techniques helped to keep the web resources available for Ukrainians and how AWS improved DDoS protection for all customers based on Ukraine experience
5th LF Energy Power Grid Model Meet-up SlidesDanBrown980551
5th Power Grid Model Meet-up
It is with great pleasure that we extend to you an invitation to the 5th Power Grid Model Meet-up, scheduled for 6th June 2024. This event will adopt a hybrid format, allowing participants to join us either through an online Mircosoft Teams session or in person at TU/e located at Den Dolech 2, Eindhoven, Netherlands. The meet-up will be hosted by Eindhoven University of Technology (TU/e), a research university specializing in engineering science & technology.
Power Grid Model
The global energy transition is placing new and unprecedented demands on Distribution System Operators (DSOs). Alongside upgrades to grid capacity, processes such as digitization, capacity optimization, and congestion management are becoming vital for delivering reliable services.
Power Grid Model is an open source project from Linux Foundation Energy and provides a calculation engine that is increasingly essential for DSOs. It offers a standards-based foundation enabling real-time power systems analysis, simulations of electrical power grids, and sophisticated what-if analysis. In addition, it enables in-depth studies and analysis of the electrical power grid’s behavior and performance. This comprehensive model incorporates essential factors such as power generation capacity, electrical losses, voltage levels, power flows, and system stability.
Power Grid Model is currently being applied in a wide variety of use cases, including grid planning, expansion, reliability, and congestion studies. It can also help in analyzing the impact of renewable energy integration, assessing the effects of disturbances or faults, and developing strategies for grid control and optimization.
What to expect
For the upcoming meetup we are organizing, we have an exciting lineup of activities planned:
-Insightful presentations covering two practical applications of the Power Grid Model.
-An update on the latest advancements in Power Grid -Model technology during the first and second quarters of 2024.
-An interactive brainstorming session to discuss and propose new feature requests.
-An opportunity to connect with fellow Power Grid Model enthusiasts and users.
Taking AI to the Next Level in Manufacturing.pdfssuserfac0301
Read Taking AI to the Next Level in Manufacturing to gain insights on AI adoption in the manufacturing industry, such as:
1. How quickly AI is being implemented in manufacturing.
2. Which barriers stand in the way of AI adoption.
3. How data quality and governance form the backbone of AI.
4. Organizational processes and structures that may inhibit effective AI adoption.
6. Ideas and approaches to help build your organization's AI strategy.
Skybuffer SAM4U tool for SAP license adoptionTatiana Kojar
Manage and optimize your license adoption and consumption with SAM4U, an SAP free customer software asset management tool.
SAM4U, an SAP complimentary software asset management tool for customers, delivers a detailed and well-structured overview of license inventory and usage with a user-friendly interface. We offer a hosted, cost-effective, and performance-optimized SAM4U setup in the Skybuffer Cloud environment. You retain ownership of the system and data, while we manage the ABAP 7.58 infrastructure, ensuring fixed Total Cost of Ownership (TCO) and exceptional services through the SAP Fiori interface.
inQuba Webinar Mastering Customer Journey Management with Dr Graham HillLizaNolte
HERE IS YOUR WEBINAR CONTENT! 'Mastering Customer Journey Management with Dr. Graham Hill'. We hope you find the webinar recording both insightful and enjoyable.
In this webinar, we explored essential aspects of Customer Journey Management and personalization. Here’s a summary of the key insights and topics discussed:
Key Takeaways:
Understanding the Customer Journey: Dr. Hill emphasized the importance of mapping and understanding the complete customer journey to identify touchpoints and opportunities for improvement.
Personalization Strategies: We discussed how to leverage data and insights to create personalized experiences that resonate with customers.
Technology Integration: Insights were shared on how inQuba’s advanced technology can streamline customer interactions and drive operational efficiency.
Northern Engraving | Nameplate Manufacturing Process - 2024Northern Engraving
Manufacturing custom quality metal nameplates and badges involves several standard operations. Processes include sheet prep, lithography, screening, coating, punch press and inspection. All decoration is completed in the flat sheet with adhesive and tooling operations following. The possibilities for creating unique durable nameplates are endless. How will you create your brand identity? We can help!
Dandelion Hashtable: beyond billion requests per second on a commodity serverAntonios Katsarakis
This slide deck presents DLHT, a concurrent in-memory hashtable. Despite efforts to optimize hashtables, that go as far as sacrificing core functionality, state-of-the-art designs still incur multiple memory accesses per request and block request processing in three cases. First, most hashtables block while waiting for data to be retrieved from memory. Second, open-addressing designs, which represent the current state-of-the-art, either cannot free index slots on deletes or must block all requests to do so. Third, index resizes block every request until all objects are copied to the new index. Defying folklore wisdom, DLHT forgoes open-addressing and adopts a fully-featured and memory-aware closed-addressing design based on bounded cache-line-chaining. This design offers lock-free index operations and deletes that free slots instantly, (2) completes most requests with a single memory access, (3) utilizes software prefetching to hide memory latencies, and (4) employs a novel non-blocking and parallel resizing. In a commodity server and a memory-resident workload, DLHT surpasses 1.6B requests per second and provides 3.5x (12x) the throughput of the state-of-the-art closed-addressing (open-addressing) resizable hashtable on Gets (Deletes).
Main news related to the CCS TSI 2023 (2023/1695)Jakub Marek
An English 🇬🇧 translation of a presentation to the speech I gave about the main changes brought by CCS TSI 2023 at the biggest Czech conference on Communications and signalling systems on Railways, which was held in Clarion Hotel Olomouc from 7th to 9th November 2023 (konferenceszt.cz). Attended by around 500 participants and 200 on-line followers.
The original Czech 🇨🇿 version of the presentation can be found here: https://www.slideshare.net/slideshow/hlavni-novinky-souvisejici-s-ccs-tsi-2023-2023-1695/269688092 .
The videorecording (in Czech) from the presentation is available here: https://youtu.be/WzjJWm4IyPk?si=SImb06tuXGb30BEH .
[OReilly Superstream] Occupy the Space: A grassroots guide to engineering (an...Jason Yip
The typical problem in product engineering is not bad strategy, so much as “no strategy”. This leads to confusion, lack of motivation, and incoherent action. The next time you look for a strategy and find an empty space, instead of waiting for it to be filled, I will show you how to fill it in yourself. If you’re wrong, it forces a correction. If you’re right, it helps create focus. I’ll share how I’ve approached this in the past, both what works and lessons for what didn’t work so well.
Session 1 - Intro to Robotic Process Automation.pdfUiPathCommunity
👉 Check out our full 'Africa Series - Automation Student Developers (EN)' page to register for the full program:
https://bit.ly/Automation_Student_Kickstart
In this session, we shall introduce you to the world of automation, the UiPath Platform, and guide you on how to install and setup UiPath Studio on your Windows PC.
📕 Detailed agenda:
What is RPA? Benefits of RPA?
RPA Applications
The UiPath End-to-End Automation Platform
UiPath Studio CE Installation and Setup
💻 Extra training through UiPath Academy:
Introduction to Automation
UiPath Business Automation Platform
Explore automation development with UiPath Studio
👉 Register here for our upcoming Session 2 on June 20: Introduction to UiPath Studio Fundamentals: https://community.uipath.com/events/details/uipath-lagos-presents-session-2-introduction-to-uipath-studio-fundamentals/
Monitoring and Managing Anomaly Detection on OpenShift.pdfTosin Akinosho
Monitoring and Managing Anomaly Detection on OpenShift
Overview
Dive into the world of anomaly detection on edge devices with our comprehensive hands-on tutorial. This SlideShare presentation will guide you through the entire process, from data collection and model training to edge deployment and real-time monitoring. Perfect for those looking to implement robust anomaly detection systems on resource-constrained IoT/edge devices.
Key Topics Covered
1. Introduction to Anomaly Detection
- Understand the fundamentals of anomaly detection and its importance in identifying unusual behavior or failures in systems.
2. Understanding Edge (IoT)
- Learn about edge computing and IoT, and how they enable real-time data processing and decision-making at the source.
3. What is ArgoCD?
- Discover ArgoCD, a declarative, GitOps continuous delivery tool for Kubernetes, and its role in deploying applications on edge devices.
4. Deployment Using ArgoCD for Edge Devices
- Step-by-step guide on deploying anomaly detection models on edge devices using ArgoCD.
5. Introduction to Apache Kafka and S3
- Explore Apache Kafka for real-time data streaming and Amazon S3 for scalable storage solutions.
6. Viewing Kafka Messages in the Data Lake
- Learn how to view and analyze Kafka messages stored in a data lake for better insights.
7. What is Prometheus?
- Get to know Prometheus, an open-source monitoring and alerting toolkit, and its application in monitoring edge devices.
8. Monitoring Application Metrics with Prometheus
- Detailed instructions on setting up Prometheus to monitor the performance and health of your anomaly detection system.
9. What is Camel K?
- Introduction to Camel K, a lightweight integration framework built on Apache Camel, designed for Kubernetes.
10. Configuring Camel K Integrations for Data Pipelines
- Learn how to configure Camel K for seamless data pipeline integrations in your anomaly detection workflow.
11. What is a Jupyter Notebook?
- Overview of Jupyter Notebooks, an open-source web application for creating and sharing documents with live code, equations, visualizations, and narrative text.
12. Jupyter Notebooks with Code Examples
- Hands-on examples and code snippets in Jupyter Notebooks to help you implement and test anomaly detection models.
"Scaling RAG Applications to serve millions of users", Kevin GoedeckeFwdays
How we managed to grow and scale a RAG application from zero to thousands of users in 7 months. Lessons from technical challenges around managing high load for LLMs, RAGs and Vector databases.
Conversational agents, or chatbots, are increasingly used to access all sorts of services using natural language. While open-domain chatbots - like ChatGPT - can converse on any topic, task-oriented chatbots - the focus of this paper - are designed for specific tasks, like booking a flight, obtaining customer support, or setting an appointment. Like any other software, task-oriented chatbots need to be properly tested, usually by defining and executing test scenarios (i.e., sequences of user-chatbot interactions). However, there is currently a lack of methods to quantify the completeness and strength of such test scenarios, which can lead to low-quality tests, and hence to buggy chatbots.
To fill this gap, we propose adapting mutation testing (MuT) for task-oriented chatbots. To this end, we introduce a set of mutation operators that emulate faults in chatbot designs, an architecture that enables MuT on chatbots built using heterogeneous technologies, and a practical realisation as an Eclipse plugin. Moreover, we evaluate the applicability, effectiveness and efficiency of our approach on open-source chatbots, with promising results.
Connector Corner: Seamlessly power UiPath Apps, GenAI with prebuilt connectorsDianaGray10
Join us to learn how UiPath Apps can directly and easily interact with prebuilt connectors via Integration Service--including Salesforce, ServiceNow, Open GenAI, and more.
The best part is you can achieve this without building a custom workflow! Say goodbye to the hassle of using separate automations to call APIs. By seamlessly integrating within App Studio, you can now easily streamline your workflow, while gaining direct access to our Connector Catalog of popular applications.
We’ll discuss and demo the benefits of UiPath Apps and connectors including:
Creating a compelling user experience for any software, without the limitations of APIs.
Accelerating the app creation process, saving time and effort
Enjoying high-performance CRUD (create, read, update, delete) operations, for
seamless data management.
Speakers:
Russell Alfeche, Technology Leader, RPA at qBotic and UiPath MVP
Charlie Greenberg, host
Connector Corner: Seamlessly power UiPath Apps, GenAI with prebuilt connectors
MSc rjfg V1
1. Instituto Tecnol´gico y de Estudios Superiores de
o
Monterrey
Campus Monterrey
Divisi´n de Electr´nica, Computaci´n, Informaci´n, y
o o o o
Comunicaciones
Programa de Graduados
Interference and Capacity Analysis of CDMA multi-service
linear Ad Hoc Networks
THESIS
Presented as a partial fulfillment of the requeriments for the degree of
Master of Science in Electronic Engineering
Major in Telecommunications
Rodolfo Javier Fuentes Gonz´lez
a
Monterrey, N.L. October 2003
5. Instituto Tecnol´gico y de Estudios Superiores de
o
Monterrey
Campus Monterrey
Divisi´n de Electr´nica, Computaci´n, Informaci´n, y
o o o o
Comunicaciones
Programa de Graduados
The members of the thesis committee recommended the acceptance of the thesis of
Rodolfo Javier Fuentes Gonz´lez as a partial fulfillment of the requeriments for the degree
a
of Master of Science in:
Electronic Engineering
Major in Telecommunications
THESIS COMMITTEE
David Mu˜oz Rodr´
n ıguez, Ph.D.
Advisor
C´sar Vargas Rosales, Ph.D.
e Jos´ Ram´n Rodr´
e o ıguez Cruz, Ph.D.
Synodal Synodal
Approved
David Garza Salazar, Ph.D.
Director of the Graduate Program
October 2003
6.
7.
8.
9. Interference and Capacity Analysis of CDMA multi-service
linear Ad Hoc Networks
Rodolfo Javier Fuentes Gonz´lez, M.Sc.
a
Instituto Tecnol´gico y de Estudios Superiores de Monterrey, 2003
o
Abstract
Wireless systems have been under an evolutionary process along the time, in order
to satisfy the demanding user needs of these types of systems. Those needs and inquiries
of wireless markets have grown considerably in a short time. This fast market growth
has pushed companies to employ state of the art technology in order to use and share
trustworthy databases in an instantaneous and imperceptible way for the final user.
Ad Hoc mobile networks are being developed and implemented in order to solve and
satisfy the needs and problems of mobile users. This technology can be an actual solution
in which users demands good quality of service (QoS) in their personal communications
and internet devises, according to the current and future market needs.
Code Division Multiple Access (CDMA) seems to be the future wireless interface and,
because of its characteristics, it could play an important role in future communications
systems. Operational characteristics allow CDMA to be considered an adequate access
method for conventional and Ad Hoc networking systems. As a mentioned above, this work
will base its access method on CDMA, where the main limiting factor is the interference,
so here we will characterize the interference and the outage probability for an ad hoc linear
network for different scenarios and different physical conditions.
10.
11. Interference and Capacity Analysis of CDMA multi-service
linear Ad Hoc Networks
Rodolfo Javier Fuentes Gonz´lez, M.Sc.
a
Instituto Tecnol´gico y de Estudios Superiores de Monterrey, 2003
o
Resumen
Los sistemas de comunicaci´n inalambrica han venido evolucionando a lo largo del
o
tiempo para tratar de cubrir las demandantes necesidades de los usuarios de este tipo de
sistemas. Estas necesidades e inquietudes del mercado crecen rapidamente por lo que se
requiere contar con sistemas que sean el estado del arte en cuanto a tecnolog´ que cuenten
ıa,
y puedan accesar confiablemente a fuentes y bases de datos de manera instantanea y de
manera inperceptible para el usuario final.
Las redes m´viles Ad Hoc est´n siendo dise˜adas e implementadas para tratar de
o a n
resolver y satisfacer las necesidades y problemas de este tipo de usuarios, esta tecnolog´
ıa
pueden ser una soluci´n a acorde a la problem´tica actual, en donde se requiere contar con
o a
una buena disponibilidad de servcicios de comunicaci´n personal e internet acorde a las
o
demandas de los mercados actuales y de un futuro pr´ximo.
o
CDMA parece ser la interface inal´mbrica de sistemas futuros, debido a sus car-
a
acter´ısticas es que podr´ jugar un papel importante en los sistemas de comunicaciones
ıa
inal´mbricos que vienen. Las caracter´
a ısticas operacionales de CDMA le permiten ser
cosiderado como un modo de acceso adecuado a la redes convencioneles y del tipo Ad
Hoc. Por todo lo anterior es que este trabajo aborda, el problema de la caracterizaci´n de
o
la interferencia, limitante primordial de sistemas CDMA, as´ como una caracterizaci´n de
ı o
la capacidad y de la probabilidad de outage en un sistema ad hoc lineal, bajo diferentes
escenarios y con diferentes variantes f´
ısicas.
19. Chapter 1
Introduction
Advances in wireless technology and portable computing along with demands for greater
user mobility and bandwidth have provided a major impetus toward development of an
emerging class of self-organizing, rapidly deployable network architectures referred to as
ad-hoc wireless networks [18]. Ad-hoc wireless networks are systems of mobile nodes with-
out a fixed infrastructure. In such networks, users can communicate with each other by
using intermediate nodes as relays. Several advantages can be seen by using ad hoc wire-
less networks. Alternatively, an area can be served with fewer base stations, and faraway
terminals can connect via a neighboring node. Due to the benefits and the unique versatil-
ity that ad hoc networks provide in certain environments and applications is that ad hoc
networks will be implemented. Their properties are turning relay stations into an attrac-
tive feature for operators of conventional cellular networks. New services, such as email,
internet, ftp and video-service, are offered by companies, implying that the user bandwidth
requirement will grow considerably. The equipment supplier or network operator must be
able to guarantee a definite Quality of Service (QoS) to their customers at all time.
1.1 Objective
The objective of this thesis is to evaluate the performance of a network by simulating the
interference and its behavior when we work on funnel and single-network schemes, using
CDMA as a Medium Access Control (MAC) in a linear ad hoc network. This work also
analyzes the outage probability for both schemes when we have different physical conditions
such as user separation, path loss exponent (PLE) and size of the network. Finally, we will
present results for the case of multi-traffic schemes and for one branch and double branch
communications system networks.
1
20. 2 CHAPTER 1. INTRODUCTION
1.2 Justification
Due to rapid advances in technology along with the change of platform to wireless and de-
mands of new services and mobility, the installation of new infrastructure and renovation
could be unprofitable to the operator. For this reason, the development of self-organizing
network architectures that are capable of managing a nonhomogeneous collection of sub-
scribers is of great importance for the health of the market. On the other hand, the most
important aspect that all network operators must guarantee in order to be commercially
successful is the QoS. As result, an analysis that enables us to determine the way to ensure
a good QoS for these kinds of networks needs to be conducted.
1.3 Organization
This thesis is organized as follows: Chapter two gives a brief description of an ad-hoc wire-
less network. Chapter three presents thoroughly expounds on the problem characteristics
and describes the methodology used to obtain the interference and outage probabilities.
Chapter four presents the results obtained under different scenarios as well as in this work.
Finally, Chapter five presents both the conclusions of this analysis and the opportunities
for further research.
21. Chapter 2
Basic Concepts of Wireless Ad-hoc Networks
Today we see a great expansion in the production of technology to support mobile com-
puting. Not only are computers themselves becoming more and more capable, but many
applications are being developed in order to interact with other devices. The purpose of
this chapter is to present the fundamental aspects of multi-hop, ad-hoc wireless networks,
such as their main characteristics and configuration.
2.1 Ad-hoc Wireless Networks
An ad-hoc wireless network is a collection of two or more devices equipped with wireless
communications and networking capability. Such devices can communicate with another
node that is immediately within their radio range or one that is outside their radio range.
For the latter scenario, an intermediate node is used to relay or forward the packet from
the source toward its destination,[1].
An ad-hoc wireless network is self -organized and adaptive. This means that a formed
network can be de-formed on the fly without the need of any system administration. The
term “ad-hoc” implyes that it can take different forms, and it can be mobile, standalone,
or networked. Since ad-hoc wireless devices can take different forms (laptop, palmtop, in-
ternet mobile phone, etc.) the computation, storage, and communications capabilities of
such devices can vary tremendously. Ad-hoc devices should not only detect the presence of
connectivity with neighboring devices/nodes, but also identify what type the devices are
as well as their corresponding attributes.
In general, cellular networks consist of a number of centralized entities, such as BS
(Base Station), MSC (Mobile Switching Center), HLR (Home Location Registry), and so
on. These centralized entities perform the function of coordination. But an ad-hoc wireless
3
22. 4 CHAPTER 2. BASIC CONCEPTS OF WIRELESS AD-HOC NETWORKS
Figure 2.1: (a) heterogeneous ad-hoc devises (b) homogeneous ad-hoc networks
network is characterized by the lack of a wired backbone or centralized entities. However,
due to the presence of mobility, routing information will have to change to reflect changes
in link connectivity [1]. The diversity of ad-hoc mobile devices also implies that the battery
capacity of such devices will also vary. In Figure 2.1 we see two different networks: the first
is made by one type of device and the second network is made by different devices. Since
ad-hoc networks rely on forwarding data packets sent by other nodes, power consumption
becomes a critical issue.
In flat-routed networks, all nodes are “equal” and the packet routing is done based
on peer-to-peer connections, restricted only by the propagation conditions, and we sim-
ply note that flat-routed networks are more suitable for a highly versatile communications
environment, [11]. Figure 2.1(b) shows two different forms of ad hoc devices. There are
great differences among these devises, and this heterogeneity can affect communications
performance and the design of communications protocols. It is evident that each device
has different computational power, memory and battery capacity. The ability of an ad
hoc device to act as a server or service provider will depend on its computation, memory
storage and battery life capacity. The presence of heterogeneity implies that some devices
are more powerful than others. Some can also be servers while others can only be clients,
in addition relay communications from other users can result in a device expelling its own
energy [11].
2.1.1 Ad Hoc Characteristics
A few salient characteristics of the ad hoc networks are the following, [11]:
23. 5
2.1. AD-HOC WIRELESS NETWORKS
• Network size
Usually refers to the number of network nodes, but it can also refer to geographical
area covered by the network. Both are critical parameters coordinating network
actions with distributed control mechanisms. Taking together the number of nodes
over a given geographical space defines the network density.
• Connectivity
This refers to a number of neighbors to which each node can link directly. This
may or may not be directional links because of, for example, interference conditions.
Connectivity also refers to the link capacity between two nodes. Also related to
connectivity are specialized military operating modes, such as emission-controlled
operation. During this (EMCOM) nodes do not transmit to prevent detection by the
enemy, and they must be still able to receive critical messages.
• Network topology
User mobility can directly affect the speed of the node connectivity and, hence, the
network topology changes. Thus, it influences how and when the network protocol
must adapt to changes.
• User traffic
The characteristics and types of user generated traffic heavily influence the design of
an ad hoc network. How is the users traffic; Does it consist of short, busrty packets
that are without strict delay bound but intolerant of loss, does it consist of longer
packets that are generated periodically with strict delay bound but tolerant to loss?
Such knowledge is obviously important to the design of the medium access control
layer, because efficient access to the spectrum can be a bottleneck in a mobile ad hoc
network.
• Operational environment
Operational environment refers to the terrain (urban, rural, maritime, etc) that may
prevent line of sight (LOS) operation. It also refers to potential sources of interference
in the radio channel, which is especially relevant in the military environments where
the potential for intentional enemy interference necessitates that the design of the
physical MAC and network layers resist such attacks.
• Energy
Unlike a commercial cellular communications system. There are few or no fixed base
stations in a mobile ad hoc network (MANET). All nodes have roughly equal status,
so the energy burden cannot be transferred to energy advantaged nodes such as fixed
base stations, although nodes that are in Platt forms do have an energy advantage
24. 6 CHAPTER 2. BASIC CONCEPTS OF WIRELESS AD-HOC NETWORKS
over those that are battery operated. Specifically, battery-operated store-and-forward
nodes present a significant challenge in developing low-energy networking approaches.
Often overlooked in the design of MANET is the impact on energy consumption of
layers above the physical layer.
• Regulatory
A MANET must adhere to existing regulations for emitted power, for both legal and
public health reasons.
• Performance metrics
After determining the basic framework of a MANET, the designer must choose the
important performance metrics to satisfy user needs. Typically throughput and delay
along with their associated mean, variance, and distribution, are used as performance
metrics for user data.
• Cost
Ultimately cost-versus-performance trades must be made if the MANET design is
to be implemented. The designer must determine how cost affects the most critical
aspects of the design, specially the performance perceived by the users.
2.2 Link Establishment
Mobile users in ad hoc networks can communicate with their immediate peers, this is a peer-
to-peer single radio hop. Each individual has an influence area defined by its transmitting
power and its sensitivity threshold. Two individual are said to be adjacent if they are within
the intersection of their influence areas. Therefore, they can establish a direct connection
by a single link. Nonadjacent individuals are connected via a relaying individual lying in
the intersection of the influence areas of individuals A and B. Both sceneries are shown in
Figure 2.2.
2.3 Application Scenario
Since the ad hoc wireless networks have a network architecture that can be rapidly deployed,
without the pre-existence of almost any fixed infrastructure, they have a number of special
characteristics that are listed below, [11]:
• No central control and no hierarchical structure
25. 7
2.3. APPLICATION SCENARIO
Figure 2.2: (a) Link of adjacent individuals, and (b) link of no adjacent individuals
• Large network coverage; Large network radius
• Large number of network nodes
• Terminals are distributed stochastically
Examples of the scenarios where ad-hoc wireless networks are being used are described
below:
• Military communication
For fast establishment of communication infrastructure during deployment of forces
in hostile terrain.
• Rescue missions
For communication in areas without adequate wireless coverage.
• Security
For communication when the existing communication infrastructure is non-operational
due to a natural disaster.
• Commercial use
For setting up communications in exhibitions, conferences, or sales presentations.
• Education
For operation of virtual classrooms.
• Sensor networks
Mounted on mobile platforms.
Although all the applications mentioned represent the most efficient, secure and cheap-
est way to solve the specific problem. the application that is changing the way of concep-
tualizing future communications systems is the addition of ad-hoc wireless networks to the
26. 8 CHAPTER 2. BASIC CONCEPTS OF WIRELESS AD-HOC NETWORKS
existent cellular systems in order to get crowded heterogeneous networks with very high
data rates and bandwidth. This kind of networks will appear gradually in the next years
and are expected to be the network architecture of 4G. Its main advantages will be the
deployment of adaptive applications and partial coverage in places with a reduced density
of users. This will be possible because users will be those who deploy the network. Finally,
due to the multiple kinds of hosts, an analysis to determine the QoS in such networks is
an important research issue. A sketch of this scenery can be seen in Figure 2.3.
2.4 Multi-Hop Wireless Link Systems
The IMT-2000 mobile communications system, which supports global roaming services, is
to be introduced, as expected for broadband mobile multimedia services. Based on new
generation, mobile communications should offer at least 20 Mb/s data communications
channels. They also indicate that the network for these systems will utilize IP based tech-
nologies and transfer traffic 10 times bigger than current traffic, since broader bandwidth
mobile multimedia services will be offered so that not only people but also things will be
connected [1].
Because there will be the need to transport an enormous amount of traffic in a more
efficient manner by increasing the spectrum efficiency, the coverage of a base station will be
shorter than present systems. The radio frequency signal bandwidth will be broadened to
provide broadband communications, and because the propagation loss increases according
to the radio frequency increase, the cell radius is also supposed to be shorter. Therefore, a
new system will require more base stations to cover a wide area.
In order to utilize wireless links in future communications systems, these links must
have greater traffic capacity and economic performance. The radio frequency band of the
wireless link will become higher (such as the millimeter-wave band) to support a much
broader link bandwidth. Thus, the range of each radio link is assumed to be shorter
because of its broader link bandwidth and higher radio frequency band requirements. To
compensate for this problem, we could increase the output power and use high directivity
antennas. However, this is not desirable from the point of view of equipment cost.
To address the above mentioned problems, [3] proposes to apply a multi-hop wireless
link system. The multi-hop wireless link employs a set of short distance links instead of a
long-distance links. The required link bandwidth will increase since the links include not
only the traffic generated by the relevant user (native traffic) but also the traffic carried from
other users. In ad hoc multi-hop wireless networks, we can see two particular cases of these
networks. Single wireless networks and other network configuration that we have call funnel
wireless networks in the next sections, we will explain and see their main characteristics
27. 9
2.4. MULTI-HOP WIRELESS LINK SYSTEMS
Figure 2.3: Single Network
Figure 2.4: Funnel Network
and how do they work.
2.4.1 Single Networks
We have seen in the previous section that a multi-hop network can transport not only native
traffic but also other users traffic. This means that the radio link between mobile users
must be ready to handle highrate information. Figure 2.3 shows a multi-hop radio network
in which information departs from an access point and travels along the communication
path until it reaches its destination node.
In a single network scheme we see how information hops from user to user by using
one key per hop link. Every code key is orthogonal from each other. In later sections of
this work we will explain and define CDMA as the access method employed, which means
that the used key will be a CDMA code taken from the code pool of the system, [3].
2.4.2 Funnel Networks
On the other hand, we define a funnel network as a network array in which information
could appear to be in an imaginary funnel where the wider part is at the starting part
and as it goes ahead it becomes narrow as information is delivered to each element of the
network.
Considering this network configuration, we will refer to it as a funnel network which
28. 10 CHAPTER 2. BASIC CONCEPTS OF WIRELESS AD-HOC NETWORKS
Figure 2.5: Double Branch Funnel Network
works in the following way: each element of the network demands a certain fixed quantity
of information. This information must flow from an access point. We have to take into
account that each user demands a certain amount of information, a key multiple keys of
information that will be carried along the network. The main repercussion of this is that
the information will be carried in a cumulative way from its starting point, meaning that
the first link will carry all information belonging to the n elements of the network. Carried
information will be delivered user by user. Each user will take its information part and will
forward the rest of the information to the next user until information reaches the last user.
The main advantage of this type of ad hoc configuration is that the network can carry the
whole block of information and deliver to each user its requested information. Figure 2.4
shows an example of a funnel network.
2.4.3 Double Branch Funnel Networks
A double branch scheme could be possible when two communications branch are held by
the same access point. This is seen in Figure 2.5. This scenario is formed by two funnel
networks, one running in the opposite sense of the other. The double branch system will
work like the funnel network that we have described in previous part. Of course, we need
to analyze and see the repercussions that the use of this network configuration could have
for the system´s behavior and, in general, how the network performance is.
2.5 Propagation Model
The propagation model chosen for the system design is closely affected by the wavelengths
of the propagation frequencies and also by the distance between Tx and Rx. But when
29. 11
2.5. PROPAGATION MODEL
Figure 2.6: r(x) along x-axis in the space
designing a mobile radio system in certain environments several factors need to be account.
Such factors are listed as follows:
• Free Space Loss
• Antenna height of mobile units
• Multi-path fading
• Scattering
The field strength of a signal can be represented as a function of distance in the space
(space domain) or as a function of time (time domain). We can see that if a Tx antenna
is fixed, then the field strength varies, as is seen in Figure 2.6. The field strength at every
point is measured along the distance, and it is measured by the receptor. In Figure 2.6, we
see how a signal behaves along the distance.
The received field strength along the distance shows severe fluctuation when the mo-
bile is located far away from the base station. The average signal level of a fading signal
r(x ) o r(t) decreases as the mobile unit moves away from the transmitter unit which, for
example in a cellular environment, is the radio base station. This average signal level drop-
ping is the propagation path loss.
30. 12 CHAPTER 2. BASIC CONCEPTS OF WIRELESS AD-HOC NETWORKS
Figure 2.7: Description of a mobile radio environment
In the real environment instead of just having one direct signal from an antenna of
a mobile, we have another, or several other paths that are produced when the waves are
reflected in buildings or in the terrain. Figure 2.7 shows this effect [5].
In addition to the losses that the signal suffers when travels in space there are other
considerations such the condition of the terrain, which can be represented by a random
variable that follows a Log-Normal distribution this is called slow fading. Another type of
fading is caused by multipath when the signal is reflected by buildings or big objects, and
this effect is called fast fading.
Dispersion in a communication link is caused by the time in which different copies of
a signal arrive, and the frequency dispersion is called the Doppler effect, we can see this
effect in Figure 2.8.
Finally it is important to observe the next two points:
• Classical propagation models predict the mean signal strength over distances at many
hundreds of meters. It is important in predicting likely received power levels (cov-
erage and interference) in cells of mobile networks. Large-scale path losses may be
32. 14 CHAPTER 2. BASIC CONCEPTS OF WIRELESS AD-HOC NETWORKS
compensated by adaptive antennas and/or power control.
• Fading (small-scale) is a much more rapid fluctuation of received signals, caused by
constructive and destructive interference between two or more versions of the same
signal. This may be corrected by adaptive equalizers or by robust modulation and
error correction.
2.6 Medium Access
Unlike in cellular networks, there is a lack of centralized control and global synchronization
in ad hoc wireless networks. Hence, time division multiple access (TDMA) and frequency di-
vision multiple access (FDMA) schemes are not suitable. In addition many MAC protocols
do not deal with host mobility. As such, the scheduling of frames for timely transmission
to support QoS is difficult.
In ad hoc wireless networks, since the media are shared by multiple mobile ad hoc
nodes, access to the common channel must be made in a distributed fashion, through the
presence of a MAC protocol. Given the fact that there are no static nodes they cannot rely
on a centralized coordinator. The MAC protocol must contend for access to the channel
while at the same time avoiding possible collision with neighboring nodes.
2.6.1 Interference Factor
Interference is the main limiting factor in wireless communications. As a result of this, it is
vital to use the radio spectrum efficiently and to the limited resource among multiple users.
The channel assignment strategies minimize interference between users in different cells
in conventional cellular environments. Interference is caused by transmitted signals that
extend outside the intended coverage area into neighboring cells. The choice of multiple-
access technique directly affects subscriber capacity, which is a measure of the number of
users that can be supported in a predefined bandwidth at any time. Because of this is the
importance of characterize and study the interference.
2.6.2 CDMA Principles
CDMA is a multiple access concept based on the use of wideband spread-spectrum tech-
nique that enables the separation of signals that coincide in time and frequency, and all
signals share the same spectrum (signals are interferent each other). The energy of each
mobile station’s signal is spread over the entire bandwidth and coded to appear as broad-
band noise to every other mobile. Identification and demodulation of individual signals
33. 15
2.6. MEDIUM ACCESS
1 chip period
1 bit period
Data signal
PN Code
Coded Signal
Figure 2.9: CDMA Spreading Process
occur at the receiver by applying a replica of the sequence (code) used for spreading each
signal. This process enhances the interested signal while dismissing all others as broadband
interference.In Figure 2.9, we show how the expansion processes is done by a sequence which
is a unique code for each user. The period of the code is shorter than the information, so
the band width is bigger, because when signals are multiplied, the bandwidth is wider.
The CDMA concept can be contrasted with other multiple access techniques. In
(FMDA), each mobile station has full usage of the spectral allocation. In TDMA, breaks
down the allocation into a number of time slots. Each mobile cofinites its signal energy
within a time slot. In CDMA, the base station has full-time use of the entire spectral
allocation and spreads its signal energy over the entire bandwidth. Base stations and mobile
station use a unique code to sign each signal and to distinguish those signals coincident in
time and frequency.
There are two types of CDMA Direct Sequence (DS-CDMA) or Frequency Hop (FH-
CDMA). In the direct sequence all users share the same frequency at the same time with
a special and unique code. Before a signal transmission, user signals are multiplied by a
sequence which is different for each user [15].
Capacity considerations are fundamental to CDMA planning and operation, by ca-
pacity we mean simply the number of users that can be simultaneously supported by the
system. Power control minimizes the impact of interference by adjusting each signal level
to the minimum necessary to achieve desired call or service quality.
The relation between both bandwidths information and sequence, is known as the
Processing Gain and is defined by
Bss
PG = , (2.1)
B
where Bss is the bandwidth of the sequence used and B is the bandwidth of the information.
34. 16 CHAPTER 2. BASIC CONCEPTS OF WIRELESS AD-HOC NETWORKS
E
In digital communications there is an important metric denoted Nb , or bit energy to
0
noise power density ratio, this quantity can be related to the conventional signal-to-noise
ratio (SNR) by recognizing that energy per bit equates to the average modulation signal
power allocated to each bit duration, that is
Eb = ST, (2.2)
where S is the average modulating signal power and T is the time duration of each bit.
Notice that (2.2) is consistent with dimensional analysis, which states that energy is equiv-
alent to power multiplied by time. We can further manipulate (2.2), by substituting the
bit rate R, which is the inverse of the bit duration:
S
Eb = , (2.3)
R
Eb
is thus
N0
Eb S
= , (2.4)
N 0 RN0
We further substitute the noise power density N0 , which is the total noise power N
divided by the bandwidth W , which is,
N
N0 = , (2.5)
W
substituting (2.4) into (2.5) yields
Eb SW
= , (2.6)
N0 NR
E
which relates Nb to two factors: the S/N of the link, and the ratio of transmitted bandwidth
0
W to bit rate R. The ratio W/R is also known as the processing gain of the system, which
is the same as that in [15], and it handles and commands the performance of a CDMA
system.
Here we consider the reverse-link capacity since in CDMA this is often the limit-
ing link in terms of capacity. Assuming that the system possesses perfect power control,
which means that the transmitted power from all mobile users are equal. Based on this
assumption, the SN R of one user can be written as
S 1
= , (2.7)
N M −1
35. 17
2.7. OUTAGE PROBABILITY
where M is the total number of users present in the band. This is so because the total
interference power in the band is equal to the sum of the powers from individual users. We
proceed to substitute (2.7) into (2.6), and the result is
Eb 1W
= , (2.8)
N0 M −1 R
Solving for (M − 1) yields
W
R
M −1= , (2.9)
Eb
N0
Note that if M is large, then
W
R
M= . (2.10)
Eb
N0
2.7 Outage Probability
The Outage probability is defined as the probability that the output signal to interference
(SIR) falls below a prescribed level. This is given by:
γb
C0
P OU T = P ≤
I PG
C0
γb W
=P ,
≤
I R
where γb is the required SIR for the system in order to fill the BER requirements. W is the
system´s bandwidth and R is the rate of data transmission.
36. 18 CHAPTER 2. BASIC CONCEPTS OF WIRELESS AD-HOC NETWORKS
37. Chapter 3
Model Description
In order to analyze the network performance from the point of view of its capacity and
interference in this chapter we have made a simulation to model and analyze the behavior
of a wireless CDMA multi-service lineal ad hoc network. In the following sections we will
explain the characteristics considered to model and simulate a linear ad hoc network when
single and funnel schemes are used, both under one type of traffic and for the case of
multi-traffic scheme.
3.1 Linear Ad Hoc CDMA Modeling
For the analysis proposed in this work, we have considered the following points:
• In this work, we analyze an ad hoc network that uses CDMA as the access method,
which is deployed on a straight line, so the analysis will be considered in such scenario.
• We have chosen a point for the interference analysis. We will address this point as
the Analysis Point (AP) a point at which the interference conditions will have bigger
or crucial repercussions.
• Omnidirectional antennas are considered.
• The transmission power is considered in the sense that this power is the lowest possible
and is about -80dBm, which is the minimum receiver signal level [13].
• Power control is considered in order to reach the closest mobile, and the signal level
received is the minimum, and the same, for all users.
• User position follow a Poisson distribution, and mobiles are distributed independently
of each other.
19
38. 20 CHAPTER 3. MODEL DESCRIPTION
Figure 3.1: Planar to linear scenario
Figure 3.2: Linear generated scenario
• In this work all interference measures will be done before considering the cross-
correlation factor of each code.
• Mobiles use the closest neighbors to communicate.
• It is important to say that our system do not consider signal processing algorithms
such as, blind deconvolution and adaptive filter theory. Signal processing is proposed
as part of future work.
3.2 Proposed Model
The interference analysis made here was done by using simulations of a linear ad hoc net-
work. It is important to say that a planar model can be reduced to a linear scenario. In
Figure 3.1 we see a planar ad hoc network. Distance between points is represented by δi ,
and the distance which will be refereing as the linear distance is represented by Di . Every
Di , will be formed by the sum of the previous radio Di−1 , starting on the reference point.
For example D3 is formed by the sum of D2 and the projection of δ3 . Every time a node is
added the total distance DT otal also grows as it is seen in Figure 3.2.
39. 21
3.2. PROPOSED MODEL
Figure 3.3: Analized scenario
The simulated scenario is shown in Figure 3.3 and has the following configuration.
Our linear ad hoc network starts with an access point. The first element in the network is
placed at the first network’s position. After this point, we find user or node one, and then
successively the rest of the users; All network elements are generated with a Point Process
on the line. Based on this process we generate the mobile positions, which will compound
our complete scenario. Each event in the point process represents the mobile position along
the network.
3.2.1 Point Process
In order to model the mobile positions we use the Poisson Point Process on the line, with λ
as the parameter of occurrence, where λ is the average number of mobile stations per unit
length. The Poisson Point Process arises in many situations where the arrival or events
need to be counted and modelled. Our case events, produced by the point process are
considered as mobile positions on the working space that, for this work, will be on a line.
All our analysis will start here with the point process, so it is vital for the rest of the work to
have trustable point process. Figure 3.4 shows a point process in one and two dimensions.
Assuming that the points are distributed in a line according to a Poisson distribution
with intensity λ, the probability to have n points on the working space is given by
(λx)n e−λx
Pn = , n = 0, 1, 2...,
n!
where λ is the average number of event occurrences, and X is the random variable for
the number of mobiles n=0,1,2,... Our mobile scenario was based on a point process on a
40. 22 CHAPTER 3. MODEL DESCRIPTION
Figure 3.4: Point Process in one and two dimensions
limited line (working space WS), where the occurrence of an event represents a point which
is considered a mobile user in a particular scenario.
The exponential random variable arises in situations where the time of event occur-
rences and time modeling need to be modeled. In this work we use the exponential density
to generate the distances between the mobile positions, this density used is
f (x) = λe−λx , x ≥ 0, (3.1)
where the parameter λ is the rate at which events occur. So the probability of an event
occurring by the time x increases as the rate λ also increases.
3.3 Power Control
In CDMA, the system capacity is maximized if each mobile transmitter power level is
controlled so that the signal arrives at the mobile receptor with the minimum required
signal-to-interference ratio [17].
In order to have the minimum interference and to work with minimum interference
levels in the network, all signals must be transmitted at the minimum possible level, but
the minimum threshold level must be achieved at the receiver in order to fill the quality
requirement levels, most equipment suppliers have settle this level at -80dBm, [13] so for
this work our mobile receptors will be receiving that signal level.
Figure 3.3 shows the mobile positions and how the signals are transmitted to the next
consequent user. Mobile users know the position of the mobile to which they must trans-
mit, which is the next closest user. Also in Figure 3.3, we use In to refer to the interference
from the nth interferent (hitting our analysis point), while the line in the upper part of the
link in the picture represents a wireless link.
41. 23
3.4. PATH LOSS EXPONENT INFLUENCE
We have proposed an analysis point in which all interference has critical repercussions,
so the applied power for each link will depend on the distance between users. In this way
we come to the following. The power of the transmitted signal, [10] is given by
P Tx = P0 [1 + d]γ , (3.2)
where P Tx is the transmitted power, P0 is the threshold reception level, γ is the loss
exponent, and d is the distance between transmitter and receiver. The power at the receiver
is given by the following
P Rx = P Tx [1 + d]−γ (3.3)
= P0 [1 + d]γ [1 + D]−γ . (3.4)
3.4 Path Loss Exponent Influence
Path loss exponent is an important factor that must be consider when a communications
system is designed. Loss factor is related to the signal attenuation of the transmission
media. In free space, the causes of propagation path loss are merely frequency f and
distance d. In the next equation, we see how all of these this factors behave and we see, if
one changes how it affects the entire behavior of signal and interference
Por 1
= 2
Pt 4πdf
c
1
= 2, (3.5)
d
4π λ
where c is the speed of light, λ is the wavelength, PTx is the transmitting power, and PRx
is the received power in free space. The next equation defines the difference between two
received signals. The difference between two received signals in free space and the different
distances is given by
PR2
∆P = 10 log10
PR1
d1
= 20log10 (dB) , (3.6)
d2
and if d2 is twice distance d1 , then the difference in the two received powers is
42. 24 CHAPTER 3. MODEL DESCRIPTION
∆P =20log10 (.5) = −6dB,
so the free space propagation path loss is 6 dB/oct (octave), or 20 dB/dec (decade). And
an octave means doubling in distance, and a decade means a period of 10. Twenty dB/dec
means a propagation path loss of 20 dB and will be observed in distances between 3 to
3 km, in the case in which we would be working with signals in dB at the receiver we
must work also the path loss exponent (PLE) in dB units. A PLE changes depending on
the environment characteristics. In Table 3.1, we show different values of γ for different
environments [8].
Table 3.1: Path Loss Exponents
Environment Path Loss Exponent
Free space 2
Ideal specular relfection 4
Urban cells 2.7-3.5
Urban cells, shadowed 3-5
In building, line-of-sight 1.6-1.8
In building, obstructed path 4-6
In factory, obstructed path 2-3
3.5 Variable Activity Factors for Multi-Service CDMA
Wireless Systems
Voice activity factor (VAF) can enhance the network performance in a very convenient way
but also can be used to solve the management problem of multi-service in CDMA wireless
networks. For example in a conventional voice link, the user´s voice is active about half
the time, and if transmitters vary output power with voice activity, the total interference
power from a large number of users will be reduced about a factor of two. This reduction
in interference translates naturally into a direct increase in system capacity. The use of
voice activity is possible because all subscribers reuse the same channel [8].
If we are working with a channel which has a rate of R=14.4Kbps (as in today´s
conventional cellular systems) and if we consider a VAF of 0.4, we really would be trans-
mitting 5760 bps, because the transmitter would be transmitting 0.4 of a second. This way
43. 3.5. VARIABLE ACTIVITY FACTORS FOR MULTI-SERVICE CDMA WIRELESS SYSTEMS25
Figure 3.5: AF considerations on linear ad hoc networks
of thinking will allow us to work with channels of higher rates, for example 1Mbps with
the possibility of choosing different VAF’s and multiple parallel codes of this capacity, in
order to adapt our channel to the changing and demanding user information request we
see an example in Figure 3.5. we see that each link has its own VAF which depends on the
amount of information that is being carried.
Table 3.2 gives us the real rates that we could reach when three different transmission
capabilities are used, combined with different activity factors. If we have a channel of 1
Mbps and we need to transmit at 500Kbps, we employ a VAF of 0.5, which will allow us to
reach that transmission rate. In the case in which we need to transmit 1.5Mb, the system
would be using one full code. Another code would be used, at half of its capacity in order
to reach the required capacity.
Table 3.3 refers to the data rates that we are able to reach if we transmit parallel
codes with different data rates. In this scheme, the system splits into N parallel channels,
the entire block of information that we would need to transmit until the desired data rate
is reached with several parallel codes [7].
44. 26 CHAPTER 3. MODEL DESCRIPTION
Table 3.2: Different rates with different AF´s
Total Capacity
AF 512 Kbps 1 Mbps 2 Mbps
0.1 51.2 Kbps 100 Kbps 200 Kbps
0.2 102.4 Kbps 200 Kbps 400 Kbps
0.3 153.6 Kbps 300 Kbps 600 Kbps
0.4 204.8 Kbps 400 Kbps 800 Kbps
0.5 256 Kbps 500 Kbps 1.0 Mbps
0.6 307.2 Kbps 600 Kbps 1.2 Mbps
0.7 358.4 Kbps 700 Kbps 1.4 Mbps
0.8 409.6 Kbps 800 Kbps 1.6 Mbps
0.9 460.8 Kbps 900 Kbps 1.8 Mbps
1.0 512 Kbps 1000 Kbps 2.0 Mbps
Table 3.3: Reached capacity with parallel codes
Total Capacity
Parallel Codes 256 Kbps 512 Kbps 1 Mbps 2 Mbps
1 256 Kbps 512 Kbps 1 Mbps 2 Mbps
2 512 Kbps 1024 Kbps 2 Mbps 4 Mbps
3 768 Kbps 1536 Kbps 3 Mbps 6 Mbps
4 1024 Kbps 2048 Kbps 4 Mbps 8 Mbps
5 1280 Kbps 2560 Kbps 5 Mbps 10 Mbps
3.6 Working With Funnel Networks
As we saw in Section 2.4.2, funnel networks could be useful to transport information from an
access point to a desired user, when there is not deployed infrastructure. The versatility of
this networks consist in the fact that they are used as relay stations, carrying not only their
own traffic but also other users traffic. Every time a user is going to transmit, transmitter
must calculate an Activity Factor. Each transmitter-link has its own activity factor which
is useful in order to calculate the number of parallel or percentage of codes that it will use
to fulfil data transmission requirements.
45. 27
3.7. OUTAGE QUANTIFICATION
3.7 Outage Quantification
Outage probability is a very important parameter related to the QoS of a network. In
general outage values must be under 2-4%. Values beyond this threshold means poor´s
network Quality. Equipment suppliers must warranty this level. For this work Outage
statistics will be taken from the number of users that a network can accept successfully.
This means that all interference generated by the network in out reference point must be
less than a fixed value γtarget .
Finally in Figure 3.6 we see the employed algorithm for this work.
46. 28 CHAPTER 3. MODEL DESCRIPTION
Figure 3.6: Algorithm diagram of a CDMA linear ad hoc network
47. Chapter 4
Numerical Results
In this chapter, we present results obtained for those schemes proposed in chapter two.
The first scenario analyzed is single networks, in which users transmit one key per link
as current conventional cellular systems. On the other hand we have funnel networks,
which are formed when the user´s traffic is cumulative then is transmitted to relay nodes,
until information reaches its destiny. In both scenarios CDMA is used as the MAC. We
make a comparative analysis of the interference measures. We continue analyzing the
outage probability, where we can see the behavior of the capacity for different scenarios,
and changing different physical parameters, such as loss exponent, transmission rate, node
density, finally we make some appreciations.
4.1 Interference Analysis
In this part we will analyze the interference behavior for both scenarios carried out here
in Figure 4.1, we see the interference distribution comparison for a CDMA ad hoc network
carrying one type of service. Parameters used in this simulation are seen in Table 4.1.
Table 4.1: Characteristics of the simulated scenarios
Loss Exponent γ 2
Sensibility -80dBm
λ .01
1/λ 100 m
Working Space 10 Km
In Table 4.1, loss exponent is explained in Section 3.4, sensibility is refereed to the
minimum signal threshold needed to set a successful communication. λ is refereed to the
user occurrence, and 1/λ is refereed to the separation distance between users.
29
48. 30 CHAPTER 4. NUMERICAL RESULTS
0.2
Funnel Network
Single Network
0.18
0.16
0.14
0.12
0.1
0.08
0.06
0.04
0.02
0
−85 −80 −75 −70 −65 −60 −55
Interference (dBm)
Figure 4.1: Comparative interference density for 64 users
In Figure 4.2, we are comparing a single network vs a funnel network in their inter-
ference level using the same parameter values showed in table 4.1, because the nodes in a
funnel network work as relay stations, not only carrying their own traffic but also carrying
other user traffic. Funnel networks produce higher interference levels. On the other hand
we can see that single networks produce fewer interference levels because these networks
carry links of a single code, compared with the funnel networks which carries multiple codes
under the same physical conditions. Interference levels were reduced when the number of
users were also reduced, as we see in this case in which we have 32 users in the network
under the same physical conditions. Also in this scenario, the network which was carrying
funnel traffic was seen with the highest interference levels, but the highest interference
levels are seen for the 64-user scenario, as is shown in Figure 4.1.
In Figure 4.3, we are considering 8 users, also using the same parameters as shown
in table 4.1. We can see that interference levels are close similar in its level so there is a
tendency to reach the same level but, it will not be the same because of the funnel effect on
the traffic. The closest interference level between both schemes (single and funnel) would
be when we have two interfering users.
In Table 4.2, we see the main statistical parameters for a single network with three
different users number. For the case of funnel networks we have Table 4.3, for the same
users number. In the table std refers to the standar deviation, minimum refers to the lower
50. 32 CHAPTER 4. NUMERICAL RESULTS
level. The maximum refers to the highest interference level, and the mean which is the
expected value.
Table 4.2: Interference statistics single network: 64, 32, and 8 users.
Single network
Statistic values (dBm) 64 users 32 users 8 users
minimum -87.28 -89 -99.96
maximun -75.95 -75.84 -76.72
mean -79.57 -79.75 -81.69
std 3.3284 3.78 6.121
Table 4.3: Interference statistics funnel network: 64, 32, and 8 users.
Funnel network
Statistic values (dBm) 64 users 32 users 8 users
minimum -71.34 -73.75 -92.35
maximun -58.21 -62.07 -69.46
mean -62.13 -65.76 -74.41
std 3.773 3.415 6.041
Table 4.4: Characteristics of the simulated scenarios
Loss Exponent γ=2, γ=4
Sensibility -80dBm
Rate of user occurrence λ1 = .04, λ2 = .02, λ3 = .01
Working Space 3.5 Km
In Figure 4.4, we have a comparison of interference density using parameters from
table 4.4. We choose different user density. For the first λ1 , users would be separated
about 25m, In the second case λ2 , user´s separation would be about 50m. Finally in the
third case λ3 , distance would be around 100m. The highest interference levels are seen in
the case in which distance between users is bigger.
In the last scenario we considered a working space of 3.5Km, this means, that all of
users would be inside of this space. So depending on the distance between users is the
51. 33
4.1. INTERFERENCE ANALYSIS
f(I) Probability
0.5
λ=.04
λ=.02
0.45 λ=.01
0.4
0.35
0.3
0.25
0.2
0.15
0.1
0.05
0
−66 −65 −64 −63 −62 −61 −60 −59 −58 −57 −56 −55
Interference (w)
Figure 4.4: Comparative interference density for different λ and γ = 2
number of users that we will have in our proposed scenario. The same working space is
used in Figure 4.5, in which also we vary the occurrence rate of users. Table 4.4 show the
values used to simulate the scenario in which we have different values of node occurrence.
Figure 4.5 shows a comparison of interference distribution levels using a loss exponent
of γ = 4. When we use this value instead of using γ = 2, we have lower interference levels
because the attenuation is higher, producing lower interference levels for the rest of the
users, in this simulation we used values of Table 4.4.
4.1.1 Empirical CDF of Interference
In this part, we will analyze the empirical Cumulative Distribution Function (CDF) of
interference for the proposed scenarios in Figure 4.6, we show the empirical cumulative
distribution function of the interference. We see that for the same working space under
funnel scenario we have higher interference probabilities, when we have a bigger separation
between mobile users, meaning that if the distance between mobiles is lower nodes, would
need less power to communicate each other, and if distance between them is bigger, they
would need more power in order to reach the minimum receiver signal, in order to excite
the receptor but increasing the signal level that will produce higher interference levels for
the rest of the users in the network.
52. 34 CHAPTER 4. NUMERICAL RESULTS
0.25
λ=.04
λ=.02
λ=.01
0.2
0.15
f(I) Probability
0.1
0.05
0
−68 −66 −64 −62 −60 −58 −56
Interference (dBm)
Figure 4.5: Comparison of interference density for different λ and γ = 4
Empirical CDF graphs are generated from statistics that are taken in the reference
point. These statistics consists of multiple values of interference of our generated scenarios.
Once we have repeated the experiment a good number of times, we have a data collection
of interference. The whole block of statistics is ordered, starting from minimum values
to the maximum values. At this point we can get the data range which is the maximum
value less the minimum level. This data range we divide it into several intervals. Those
sub segments represent the data density (With this information it is possible to plot the
interference density). The empirical CDF is done adding each of the sub segment density
values, until the plot reach the maximum value of 1.
Finally Figure 4.7, shows the empirical CDF graphic for the same scenario, using a
loss exponent of γ = 4, also employing values of Table 4.4.
4.2 Capacity and Outage Probability
In this part of the chapter we will present obtained results for CDMA linear ah hoc net-
works that use the same parameters as current cellular systems, Table 4.5. We see the
network behavior in Figure 4.8, using γ = 4, as the loss exponent, and a working space of
18Km. Figure 4.9 we see the outage behavior for a funnel network using parameters as in
Table 4.5, but for this case we are using a loss exponent of γ = 2, we see that the outage
53. 36 CHAPTER 4. NUMERICAL RESULTS
0
10
Outage Probability
−1
10
λ=.003
λ=.002
λ=.001
−2
10
10 20 30 40 50 60 70
Interferents
Figure 4.8: Outage probability single network, γ = 4
behavior is also under 0.04 percent which guaranties good QoS.
Table 4.5: Parameters of current CDMA systems
Bandwidth 1.25MHz
Tx Rate 14.4Kbps
Eb/No 7 dB
VAF .4
Loss exponent γ = 2, γ = 4
In Figure 4.10, make a comparison of the outage probability between three loss ex-
ponents. In this case, we are working with a funnel network. We have use a occurrence
rate λ = .0111, which implies a user separation of about 90 meters. In this case the outage
probability is also under levels of 0.04 percent of outage which is also appropriate to guar-
anty good QoS.
Figure 4.11 shows the outage probability results for the case of a funnel network, using
the same parameters as current cellular systems, those parameters are listed in Table 4.5.
We can see that the number of users present in the funnel network is fewer that those levels
observed in the single network, for this case we are using a loss exponent of γ = 4. In
Figure 4.12 we see the behavior when we change the loss exponent to γ = 6. Here we see
54. 37
4.2. CAPACITY AND OUTAGE PROBABILITY
0
10
Outage Probability
−1
10
λ=.003
λ=.002
λ=.001
−2
10
10 20 30 40 50 60 70
Interferents
Figure 4.9: Outage probability single network, γ = 2
0
10
Outage Probability
−1
10
γ=2
γ=4
γ=6
5 10 15 20 25 30 35 40 45 50 55 60
Interferents
Figure 4.10: Outage probability of a funnel network with different PLE
55. 38 CHAPTER 4. NUMERICAL RESULTS
0
10
−1
10
Outage Probability
−2
10
λ=.003
λ=.002
λ=.001
−3
10
0 5 10 15 20 25 30 35 40 45 50
Interferents
Figure 4.11: Outage probability funnel network γ = 4
lower outage probability levels, because signals suffer high attenuation.
Finally before going to the multiservice section we will make an experiment in which we
propose to use different values of system´s characteristics. We will use a bigger bandwidth
and a bigger transmission rate. Table 4.6, show these experimental parameters.
Table 4.6: Experimental parameters in funnel CDMA systems
Bandwidth 30MHz
Tx Rate 128Kbps
Eb/No 7 dB
VAF .4
Loss exponent γ = 2, γ = 4
Employing a bandwidth of 30 MHz and a rate of R=128Kbps with a γ = 2, we see
the outage probability behavior in Figure 4.13. For the same scenario, but using now a loss
exponent of γ = 4, we see the outage probability behavior in Figure 4.14. Both simulations
are on a working space of 10Km.
In Figure 4.15, we see the capacity behavior. In this graph we have users number
versus user separation. We have set two outage values to analyze the capacity, the first is
57. 40 CHAPTER 4. NUMERICAL RESULTS
0
10
Outage Probability
−1
10
λ=.003
λ=.002
λ=.001
−2
10
10 20 30 40 50 60 70
Interferents
Figure 4.14: Outage probability funnel network γ = 4, BW 30MHz
0.04% and a second value for outage 0.08%. We can compare both schemes, single net-
works, and funnel networks. The figure shows bigger user capacity for the case of single
users. For the case of the fixed outage, if we decrease the outage requirement, the number
of users grow. Refer to Table 4.5, to see the utilized parameters to simulate both schemes
single and funnel CDMA networks.
4.3 Multiservice Traffic Results
In this section, we present results obtained when different transmission rates are used in the
ad hoc network. The procedure used here to use different activity factor (AF) is the same
as in section 3.6. For this work we consider that the network will be offering three types of
services with the same probability of occurrence in each node of the network. Parameters
used for the present scenarios are shown in Table 4.7.
Figure 4.16, shows the network behavior for a funnel network using a bandwidth of
20Mhz as well as the three proposed services with the same probability of the user demand.
In Figure 4.17, we see the network behavior with different values in lambda and the
same services, in this case we used λ1 = .001, λ2 = .002 and λ3 = .003. For this case, we
have a γ = 4.
58. 41
4.3. MULTISERVICE TRAFFIC RESULTS
70
Outage Single @ .04%
Outage Single @ .08%
Outage Funnel @ .04%
Outage Funnel @ .08%
60
50
Users Number
40
30
20
10
0
300 400 500 600 700 800 900 1000 1100
User separation 1/lambda (m)
Figure 4.15: Capacity comparison single VS funnel networks
0
10
Outage Probability
−1
10
Service types
S1= 64Kbps
S2=128Kbps
S =384Kbps
3
λ=.001
λ=.002
λ=.003
−2
10
5 10 15 20 25 30 35 40 45 50 55 60
Interferents
Figure 4.16: Outage probability funnel multiservice network, γ = 4
59. 42 CHAPTER 4. NUMERICAL RESULTS
Table 4.7: Multiservice parameters
Bandwidth 20MHz
Tx Rate 512Kbps
Eb/No 7 dB
VAF variable
Loss exponent γ = 2, γ = 4
0
10
Outage Probability
−1
10
Service types
S1= 64Kbps
S =128Kbps
2
S =384Kbps
3
λ=.001
λ=.002
λ=.003
−2
10
5 10 15 20 25 30 35 40 45 50 55 60
Interferents
Figure 4.17: Outage probability funnel multiservice network, γ = 2
We can see the same scenario, but now using a path loss exponent of γ = 2 and
offering the same services, in Figure 4.17. To see the effect that the loss exponent plays in
the network behavior, we have Figure 4.18. In this figure, we are using a γ = 6. Under
these physical conditions, in which we expected to observe the best results. Finally, Figure
4.19 directly compares three different values of γ1 = 2, γ2 = 4, γ3 = 6. Expecting to have
the best results when the path loss exponent is biggest.
From the capacity point of view we present Figure 4.20, in which we see the capacity
behavior for a network that works under multiservice scheme. Also for this scenario we
have taken into account two values of outage to see the capacity behavior. The first is
outage @ 0.04% and the other is @ 0.08%. In this case we see that the outage at 0.08%
accept more users than the other outage number 0.04%. On Table 4.7, we see the utilized
parameters to simulate these scenario.
60. 43
4.3. MULTISERVICE TRAFFIC RESULTS
0
10
−1
10
Outage Probability
Service type
S1= 64Kbps
−2
10
S =128Kbps
2
S =384Kbps
3
λ=.001
λ=.002
λ=.003
−3
10
5 10 15 20 25 30 35 40 45 50 55 60
Interferents
Figure 4.18: Outage probability funnel multiservice network, γ = 6
0
10
γ=2
γ=4
γ=6
Service types
S1= 64Kbps
S2=128Kbps
Outage Probability
S3=384Kbps
−1
10
−2
10
10 20 30 40 50 60 70
Interferents
Figure 4.19: Outage probability funnel multiservice network λ = .005