This paper addresses Dynamic Spectrum Sharing (DSS) between two wireless operators. The Universal Mobile Telecommunication System (UMTS) network is used as a case study. The proposed protocol is evaluated under the uniform and non-uniform traffic conditions. The underlying principles of the algorithm can be deployed in the UMTS extension Band (2500MHz-2690MHz) which is yet to be allocated or the re-farmed GSM spectrum (900MHz/1800MHz). The simulation results for the proposed protocol shows that significant spectrum sharing gains can be obtained. However such spectrum efficiency gain need to be carefully balanced with the complexity in terms of latency (delays) and additional overhead it brings to the network. The results show that significant spectrum sharing gain of 4.0 % and 2.0 % can be obtained under uniform and non-uniform traffic conditions
we find out various power aware and data packet rate control with-collision-avoidance (CSMA/CA)-based ad hoc wireless network communication. And identifies that CSMA
Investigation of Clock Synchronization Techniques and its Performance Impact ...ijctet
This document summarizes research on clock synchronization techniques in mobile ad hoc networks (MANETs). It begins by defining MANETs and explaining why time synchronization is important. It then discusses challenges in time synchronization due to clock imperfections and variable network delays. The document reviews existing clock synchronization methods like burst transmission and clock sampling. It also covers characteristics of MANETs like dynamic topology. Finally, it surveys previous research on time synchronization algorithms for MANETs, including a decentralized algorithm that achieves fast convergence times and high accuracy.
DESIGN OF A COMPACT CIRCULAR MICROSTRIP PATCH ANTENNA FOR WLAN APPLICATIONS pijans
This paper presents the design of a compact circular microstrip patch antenna for WLAN applications which covers the band 5.15 to 5.825 GHz. The antenna is designed using 1.4mm thick FR-4 (lossy)substrate with relative permittivity 4.4 and a microstrip line feed is used. The radius of the circular patch is chosen as 7.62mm. To reduce the size and enhance the performance of the proposed antenna, a circular slot is loaded on circular patch and a square slot is etched on the ground plane of dimension 30mm×30mm. Design of the antenna is carried out using CST Microsoft Studio Sonimulation Software. The proposed antenna resonates at 5.5 GHz with a wider bandwidth of 702 MHz and it provides low return loss of -31.58 dB, good gain of 3.23 dB and directivity of 4.28 dBi and high efficiency of around 79% against the resonance frequency. The geometry of the proposed circular antenna with reduced size and its various performance parameters such as return loss, bandwidth, VSWR, gain, directivity, efficiency and radiation pattern plots are presented and discussed.
COMPARATIVE PERFORMANCE ASSESSMENT OF VBLAST ENCODED 8×8 MIMO MC-CDMA WIRELES...pijans
The bit error rate performance of a V-Blast encoded 8x8 MIMO MC-CDMA wireless communication system
for different signal detection (MMSE and ZF) and digital modulation (BPSK, QPSK, DPSK, and 4QAM)
schemes for grayscale image transmission has been investigated in this paper. The proposed wireless system
employ ½-rated Convolution and cyclic redundancy check (CRC) channel encoding over the AWGN channel
and Walsh Hadamard code as an orthogonal spread code. The present Matlab based simulation study
demonstrates that the V-Blast encoded 8×8 MIMO MC-CDMA wireless system with the employment of 1⁄2-
rated convolution and cyclic redundancy check (CRC) channel encoding strategies shows good performance
utilizing BPSK digital modulation and ZF signal detection scheme in grayscale image transmission
Comparative Performance Assessment of V-Blast Encoded 8×8 MIMO MC-CDMA Wirele...pijans
The bit error rate performance of a V-Blast encoded 8x8 MIMO MC-CDMA wireless communication system
for different signal detection (MMSE and ZF) and digital modulation (BPSK, QPSK, DPSK, and 4QAM)
schemes for grayscale image transmission has been investigated in this paper. The proposed wireless system
employ ½-rated Convolution and cyclic redundancy check (CRC) channel encoding over the AWGN
channel and Walsh Hadamard code as an orthogonal spread code. The present Matlab based simulation study
demonstrates that the V-Blast encoded 8×8 MIMO MC-CDMA wireless system with the employment of 1⁄2-
rated convolution and cyclic redundancy check (CRC) channel encoding strategies shows good performance
utilizing BPSK digital modulation and ZF signal detection scheme in grayscale image transmission
Resource Dependent Radio Allocation For Battlefield Communications - A Data M...IJERA Editor
Network Enabled Capability (NEC) and the Land Open Systems Architecture (LOSA) are novel approaches to enable interoperability between a heterogeneous collection of assets in the battlefield. These paradigms utilise an underlying network for cooperation between deployed battlefield equipment. NEC and LOSA have great potential to transform military communications and enhance integrated survivability as well as situational awareness, but the Achilles’ heel of NEC and LOSA is the wireless spectrum over which they must communicate. A noisy and dynamic battlefield wireless spectrum as well as an array of heterogeneous wireless communications equipment handling multiple types of data with different Quality of Service (QoS) requirements requires a system which manages and allocates these communication resources effectively. This paper presents the High Availability Wireless Communications (HAWC) system, a hardware agnostic communications controller middleware to manage any combination of existing and future multiband wireless resources. The system utilises a vehicle’s data model to gather information about available radio resources and enable LOSA by meeting communications data requirements and delivering appropriate QoS to the appropriate traffic in a fleet of vehicles. The functionality of the system is verified by using behavioural simulation on a virtual battlefield.
The advent of spectrally flexible (a.k.a. elas-
tic) optical networking is widely identified as the
next generation optical network solution that
permits varying bandwidth demands to be
dynamically assigned over flexible spectral con-
tainers, targeting optimum use of the available
network resources. Additionally, the adoption of
the space dimension is identified as a promising
solution for the capacity expansion of future net-
works, while novel spatial-spectral switching
solutions show that the flexible networking con-
cept can be further expanded over both the spa-
tial and spectral dimensions. This article provides
an overview of the latest developments and pos-
sible approaches with respect to flexible optical
networking and the emerging benefits that spa-
tially flexible networking approaches can offer.
The focus is on the network planning and
resource optimization functions, the main net-
work operations related to fragmentation and
IP/optical layer integration, and the control
plane solutions.
A CELLULAR BONDING AND ADAPTIVE LOAD BALANCING BASED MULTI-SIM GATEWAY FOR MO...pijans
As it is well known, the QoS(quality of service) provided by mobile Internet access point devices is far from
the QoS level offered by the common ADSL modem-router due to several reasons: in fact, mobile Internet
access networks are not designed to support real-time data traffic because of several drawbacks
concerning the wireless medium such as resource sharing, traffic congestion, radio link coverage etc.,
which impact directly such parameters as delay, jitter, and packet loss rate that are strictly connected to
the quality of user experience. The main scope of the present paper is to introduce a dual USIM HSPA
gateway for ad hoc and sensors networks thanks to which it will be possible to guarantee a QoS suitable
for a series of network-centric application such as real-time communications and monitoring, video
surveillance, real-time sensor networks, telemedicine, vehicular and mobile sensor networks and so on. The
main idea is to exploit multiple radio access networks in order to enhance the available end-to-end
bandwidth and the perceived quality of experience. The scope has been reached by combining multiple
radio access with dynamic load balancing and the VPN (virtual private network) bond technique.
we find out various power aware and data packet rate control with-collision-avoidance (CSMA/CA)-based ad hoc wireless network communication. And identifies that CSMA
Investigation of Clock Synchronization Techniques and its Performance Impact ...ijctet
This document summarizes research on clock synchronization techniques in mobile ad hoc networks (MANETs). It begins by defining MANETs and explaining why time synchronization is important. It then discusses challenges in time synchronization due to clock imperfections and variable network delays. The document reviews existing clock synchronization methods like burst transmission and clock sampling. It also covers characteristics of MANETs like dynamic topology. Finally, it surveys previous research on time synchronization algorithms for MANETs, including a decentralized algorithm that achieves fast convergence times and high accuracy.
DESIGN OF A COMPACT CIRCULAR MICROSTRIP PATCH ANTENNA FOR WLAN APPLICATIONS pijans
This paper presents the design of a compact circular microstrip patch antenna for WLAN applications which covers the band 5.15 to 5.825 GHz. The antenna is designed using 1.4mm thick FR-4 (lossy)substrate with relative permittivity 4.4 and a microstrip line feed is used. The radius of the circular patch is chosen as 7.62mm. To reduce the size and enhance the performance of the proposed antenna, a circular slot is loaded on circular patch and a square slot is etched on the ground plane of dimension 30mm×30mm. Design of the antenna is carried out using CST Microsoft Studio Sonimulation Software. The proposed antenna resonates at 5.5 GHz with a wider bandwidth of 702 MHz and it provides low return loss of -31.58 dB, good gain of 3.23 dB and directivity of 4.28 dBi and high efficiency of around 79% against the resonance frequency. The geometry of the proposed circular antenna with reduced size and its various performance parameters such as return loss, bandwidth, VSWR, gain, directivity, efficiency and radiation pattern plots are presented and discussed.
COMPARATIVE PERFORMANCE ASSESSMENT OF VBLAST ENCODED 8×8 MIMO MC-CDMA WIRELES...pijans
The bit error rate performance of a V-Blast encoded 8x8 MIMO MC-CDMA wireless communication system
for different signal detection (MMSE and ZF) and digital modulation (BPSK, QPSK, DPSK, and 4QAM)
schemes for grayscale image transmission has been investigated in this paper. The proposed wireless system
employ ½-rated Convolution and cyclic redundancy check (CRC) channel encoding over the AWGN channel
and Walsh Hadamard code as an orthogonal spread code. The present Matlab based simulation study
demonstrates that the V-Blast encoded 8×8 MIMO MC-CDMA wireless system with the employment of 1⁄2-
rated convolution and cyclic redundancy check (CRC) channel encoding strategies shows good performance
utilizing BPSK digital modulation and ZF signal detection scheme in grayscale image transmission
Comparative Performance Assessment of V-Blast Encoded 8×8 MIMO MC-CDMA Wirele...pijans
The bit error rate performance of a V-Blast encoded 8x8 MIMO MC-CDMA wireless communication system
for different signal detection (MMSE and ZF) and digital modulation (BPSK, QPSK, DPSK, and 4QAM)
schemes for grayscale image transmission has been investigated in this paper. The proposed wireless system
employ ½-rated Convolution and cyclic redundancy check (CRC) channel encoding over the AWGN
channel and Walsh Hadamard code as an orthogonal spread code. The present Matlab based simulation study
demonstrates that the V-Blast encoded 8×8 MIMO MC-CDMA wireless system with the employment of 1⁄2-
rated convolution and cyclic redundancy check (CRC) channel encoding strategies shows good performance
utilizing BPSK digital modulation and ZF signal detection scheme in grayscale image transmission
Resource Dependent Radio Allocation For Battlefield Communications - A Data M...IJERA Editor
Network Enabled Capability (NEC) and the Land Open Systems Architecture (LOSA) are novel approaches to enable interoperability between a heterogeneous collection of assets in the battlefield. These paradigms utilise an underlying network for cooperation between deployed battlefield equipment. NEC and LOSA have great potential to transform military communications and enhance integrated survivability as well as situational awareness, but the Achilles’ heel of NEC and LOSA is the wireless spectrum over which they must communicate. A noisy and dynamic battlefield wireless spectrum as well as an array of heterogeneous wireless communications equipment handling multiple types of data with different Quality of Service (QoS) requirements requires a system which manages and allocates these communication resources effectively. This paper presents the High Availability Wireless Communications (HAWC) system, a hardware agnostic communications controller middleware to manage any combination of existing and future multiband wireless resources. The system utilises a vehicle’s data model to gather information about available radio resources and enable LOSA by meeting communications data requirements and delivering appropriate QoS to the appropriate traffic in a fleet of vehicles. The functionality of the system is verified by using behavioural simulation on a virtual battlefield.
The advent of spectrally flexible (a.k.a. elas-
tic) optical networking is widely identified as the
next generation optical network solution that
permits varying bandwidth demands to be
dynamically assigned over flexible spectral con-
tainers, targeting optimum use of the available
network resources. Additionally, the adoption of
the space dimension is identified as a promising
solution for the capacity expansion of future net-
works, while novel spatial-spectral switching
solutions show that the flexible networking con-
cept can be further expanded over both the spa-
tial and spectral dimensions. This article provides
an overview of the latest developments and pos-
sible approaches with respect to flexible optical
networking and the emerging benefits that spa-
tially flexible networking approaches can offer.
The focus is on the network planning and
resource optimization functions, the main net-
work operations related to fragmentation and
IP/optical layer integration, and the control
plane solutions.
A CELLULAR BONDING AND ADAPTIVE LOAD BALANCING BASED MULTI-SIM GATEWAY FOR MO...pijans
As it is well known, the QoS(quality of service) provided by mobile Internet access point devices is far from
the QoS level offered by the common ADSL modem-router due to several reasons: in fact, mobile Internet
access networks are not designed to support real-time data traffic because of several drawbacks
concerning the wireless medium such as resource sharing, traffic congestion, radio link coverage etc.,
which impact directly such parameters as delay, jitter, and packet loss rate that are strictly connected to
the quality of user experience. The main scope of the present paper is to introduce a dual USIM HSPA
gateway for ad hoc and sensors networks thanks to which it will be possible to guarantee a QoS suitable
for a series of network-centric application such as real-time communications and monitoring, video
surveillance, real-time sensor networks, telemedicine, vehicular and mobile sensor networks and so on. The
main idea is to exploit multiple radio access networks in order to enhance the available end-to-end
bandwidth and the perceived quality of experience. The scope has been reached by combining multiple
radio access with dynamic load balancing and the VPN (virtual private network) bond technique.
Dear Student,
DREAMWEB TECHNO SOLUTIONS is one of the Hardware Training and Software Development centre available in
Trichy. Pioneer in corporate training, DREAMWEB TECHNO SOLUTIONS provides training in all software
development and IT-related courses, such as Embedded Systems, VLSI, MATLAB, JAVA, J2EE, CIVIL,
Power Electronics, and Power Systems. It’s certified and experienced faculty members have the
competence to train students, provide consultancy to organizations, and develop strategic
solutions for clients by integrating existing and emerging technologies.
ADD: No:73/5, 3rd Floor, Sri Kamatchi Complex, Opp City Hospital, Salai Road, Trichy-18
Contact @ 7200021403/04
phone: 0431-4050403
ADAPTIVE RANDOM SPATIAL BASED CHANNEL ESTIMATION (ARSCE) FOR MILLIMETER WAVE ...IJCNCJournal
Millimeter-wave and mMIMO communications are the most essential success systems for next-generation wireless sensor networks to have enormous amounts of accessible throughput and spectrum. Through installing huge antenna arrays at the base station and performing coherent transceiver processing, mMIMO is a potential technology for enhancing the bandwidth efficiency of wireless sensor networks. The use of mmWave frequencies for mMIMO systems solves the problem of high path-loss through offering greater antenna gains. In this work, we provide a design with a random spatial sample structure that incorporates a totally random step before the analogue is received. It contains a totally random step before the analogue received signals are sent into the digital component of the HBF receiver. Adaptive random spatial based channel estimation (ARSCE) is proposed for channel session measurement collection, and an analogue combiner with valves has been used to estimate the signals at each receiving antenna. The proposed optimization problem formulation attempts to discover the orientations and gains of wideband channel routes. In addition, our proposed model has compared to various state-of-art techniques while considering error minimization.
Improving the network lifetime of mane ts through cooperative mac protocol de...Pvrtechnologies Nellore
The document proposes a novel cooperative MAC (CMAC) protocol called DEL-CMAC for improving the network lifetime of mobile ad hoc networks (MANETs). DEL-CMAC incorporates a distributed utility-based best relay selection strategy based on location information and residual energy. It also includes a cross-layer optimal transmitting power allocation scheme to conserve energy while maintaining throughput. Additionally, it provides an innovative network allocation vector setting to deal with interference from varying transmitting powers during cooperation. Simulation results show DEL-CMAC significantly prolongs network lifetime under different scenarios compared to the IEEE 802.11 standard and other throughput-focused CMAC protocols.
The document reviews different routing protocols for mobile ad hoc networks (MANETs). It begins with an introduction to MANETs and discusses some of their key characteristics including decentralized operation and dynamic topology. It then reviews several popular routing protocol categories for MANETs - flat, hierarchical, and location-based. Flat protocols like distance vector and link state are discussed as well as their limitations in dynamic MANET environments. The review covers over a dozen different specific routing protocols that have been proposed.
Modelling and QoS-Achieving Solution in full-duplex Cellular SystemsIJCNCJournal
The global bandwidth scarcity and the ever-growing demand for fast wireless services have motivated the quest for new techniques that enhance the spectral efficiency (SE) of wireless systems. Most conventional SE increasing methods (e.g., adaptive modulation and coding) have already been exhausted. Single-channel full-duplex (SCFD) communication is a new attractive approach in which each node may simultaneously receive and transmit over the same frequency channel, and thus, it has the potential to double the current SE figures. In this paper, we derive a model for the signal-to-interference-plus-noise ratio (SINR) in a SCFD-based cellular system with imperfect self-interference cancellation. Furthermore, given a set of uplink and downlink quality of service requirements, we answer the following two fundamental questions. First, is this set achievable in the SCFD-based cellular system? Second, if the given set is achievable, what is the optimal achieving policy? To that end, we provide a unified model for the SCFD-based cellular system, and give insights in the matrix of interference channel gains. Simulation results suggest that depending on the locations of the users, a combination of full-duplex and half-duplex modes over the whole network is more favourable policy
EFFICIENCY ENHANCEMENT BASED ON ALLOCATING BIZARRE PEAKSijwmn
A new work has been proposed in this paper in order to overcome one of the main drawbacks that found in
the Orthogonal Frequency Division Multiplex (OFDM) systems, namely Peak to Average Power Ratio
(PAPR). Furthermore, this work will be compared with a previously published work that uses the neural
network (NN) as a solution to remedy this deficiency.
The proposed work could be considered as a special averaging technique (SAT), which consists of wavelet
transformation in its first stage, a globally statistical adaptive detecting algorithm as a second stage; and
in the third stage it replaces the affected peaks by making use of moving average filter process. In the NN
work, the learning process makes use of a previously published work that is based on three linear coding
techniques.
In order to check the proposed work validity, a MATLAB simulation has been run and has two main
variables to compare with; namely BER and CCDF curves. This is true under the same bandwidth
occupancy and channel characteristics. Two types of tested data have been used; randomly generated data
and a practical data that have been extracted from a funded project entitled by ECEM. From the achieved
simulation results, the work that is based on SAT shows promising results in reducing the PAPR effect
reached up to 80% over the work in the literature and our previously published work. This means that this
work gives an extra reduction up to 15% of our previously published work. However, this achievement will
be under the cost of complexity. This penalty could be optimized by imposing the NN to the SAT work in
order to enhance the wireless systems performance.
International Journal of Computer Networks & Communications (IJCNC)IJCNCJournal
Beamforming for millimetre-wave (mmWave) frequencies has been studied for many years. It is considered as an important enabling technology for communications in these high-frequency ranges and it received a lot of attention in the research community. The special characteristics of the mmWave band made the beamforming problem a challenging one because it depends on many environmental and operational factors. These challenges made any model-based architecture fit only special applications, working scenarios, and specific environment geometry. All these reasons increased the need for more general machine learning based beamforming systems that can work in different environments and conditions. This increased the need for an extended adjustable dataset that can serve as a tool for any machine learning technique to build an efficient beamforming architecture. Deep MIMO dataset has been used in many architectures and designs and has proved its benefits and flexibility to fit in many cases. In this paper, we study the extension of collaborative beamforming that includes many cooperating base stations by studying the impact of User Equipment (UE) speed ranges on the beamforming performance, optimizing the parameters of the neural network architecture of the beamforming design, and suggesting the optimal design that gives the best performance for as a small dataset as possible. Suggested architecture can achieve the same performance achieved before with up to 33% reduction in the dataset size used to train the system which provides a huge reduction in the data collection and processing time.
DYNAMIC HYBRID CHANNEL (WMN) FOR BANDWIDTH GUARANTEES IN AD_HOC NETWORKSpharmaindexing
This document discusses bandwidth guarantees in wireless mesh networks. It proposes a new routing technique called dynamic hybrid channel, which uses both proactive and reactive routing protocols based on AOMDV. The goal is to provide bandwidth guarantees by selecting multiple paths and using the path with the highest available bandwidth for transmission. The performance of this approach is evaluated using the NS-2 network simulator. Several challenges of wireless mesh networks are also discussed, such as interference reduction and improving throughput across multiple hops.
CL-SA-OFDM: cross-layer and smart antenna based OFDM system performance enha...IJECEIAES
The growing usage of wireless services is lacking in providing high-speed data communication in recent times. Hence, many of the modulation techniques are evolved to attain these communication needs. The recent researches have widely considered OFDM technology as the prominent modulation mechanism to fulfill the futuristic needs of wireless communication. The OFDM can bring effective usage of resources, bandwidth, and system performance enhancement in collaboration with the smart antenna and resource allocation mechanism (adaptive). However, the usage of adaptive beamforming with the OFDM leads to complication in the design of medium access layer and which causes a problem in adaptive resource allocation mechanism (ARAM). Hence, the proposed manuscript intends to design an OFDM system by considering different switched beam smart antenna (SBSA) along with the cross-layer adaptive resource allocation (CLARA) and hybrid adaptive array (HAA). In this, various smart antenna mechanism are considered to analyze the quality of service (QoS) and complexity reduction in the OFDM system. In this paper, various SA schemes are used as per the quality of service (QoS) requirement of the different users. The performance analysis is conducted by considering data traffic reduction, bit-rate reduction, and average delay.
ADAPTIVE SENSOR SENSING RANGE TO MAXIMISE LIFETIME OF WIRELESS SENSOR NETWORK IJCNCJournal
Wireless Sensor Network (WSN) is commonly used to collect information from a remote area and one of the most important challenges associated with WSN is to monitor all targets in a given area while maximizing network lifetime. In wireless communication, energy consumption is proportional to the breadth of sensing range and path loss exponent. Hence, the energy consumption of communication can be minimized by varying the sensing range and decreasing the number of messages being sent. Sensing energy can be optimized by reducing the repeated coverage target. In this paper, an Adaptive Sensor Sensing Range (ASSR) technique is proposed to maximize the WSN Lifetime. This work considers a sensor network with an adaptive sensing range that are randomly deployed in the monitoring area. The sensor is adaptive in nature and can be modified in order to save power while achieving maximum time of monitoring to increase the lifetime of WSN network. The objective of ASSR is to find the best sensing range for each sensor to cover all targets in the network, which yields maximize the time of monitoring of all targets and eliminating double sensing for the same target. Experiments were conducted using an NS3 simulator to verify our proposed technique. Results show that ASSR is capable to improve the network lifetime by 20% as compared to other recent techniques in the case of a small network while achieving an 8% improvement for the case of a large networks.
Performance Analysis of Energy Optimized LTE-V2X Networks for Delay Sensitive...IJCNCJournal
This document analyzes the performance of three uplink transmission modes - single-hop direct, multi-hop cellular V2X, and store-carry-forward (SCF) - for delay sensitive real-time services in LTE-V2X networks. It presents a highway system model and compares the total energy consumption and transmission delay of the three modes using numerical simulations validated with ns-3. The results show that SCF mode consumes the least energy due to its carry phase, but incurs high delays unacceptable for real-time applications. Single-hop direct has the reverse performance. Multi-hop cellular V2X outperforms in terms of balancing low latency and moderate energy consumption beyond a cell radius of 600
This document presents a novel Cross-layer Mesh Router Placement (CMRP) scheme for wireless mesh networks. CMRP aims to minimize network deployment cost while meeting user demands. It considers various factors such as antenna types, wireless link characteristics, MAC scheduling, routing, and equipment costs. CMRP encapsulates these cross-layer factors into three attributes - Local Coverage, Backbone Residual Capacity, and Deployment Cost. It uses these attributes to select mesh router locations that maximize coverage and backbone capacity while minimizing costs. Simulations show CMRP outperforms existing schemes in cost performance ratio and feasibility for planning wireless mesh networks.
A NURBS-optimized dRRM solution in a mono-channel condition for IEEE 802.11 e...IJECEIAES
This document describes a NURBS-optimized dynamic radio resource management (dRRM) solution for IEEE 802.11 enterprise WLAN networks called N-WLCx. The authors present their original dRRM solution called WLCx, which uses a novel per-beam coverage representation approach. To reduce the high processing time of WLCx, they developed an optimization based on NURBS (Non-Uniform Rational B-Spline) surfaces. Simulation results show N-WLCx achieves a 92.58% reduction in processing time compared to the basic WLCx solution. The authors conclude N-WLCx optimization could be extended to enhance other vendors' and researchers' RRM solutions for improved efficiency
Teletraffic Analysis of Overflowed Traffic with Voice only in Multilayer 3G W...IRJET Journal
This document presents a study analyzing the traffic overflow performance of a three-layered wireless mobile network with microcells, macrocells and satellite cells handling voice-only traffic. The three-layered hierarchical network structure is described, with microcells overlaid by macrocells and macrocells overlaid by satellite cells. An existing call admission control scheme is evaluated that prioritizes voice calls, including handling call blocking probabilities, channel utilization, and call dropping probabilities across the different cell layers under varying traffic parameters. Analytical models are developed and numerical calculations are performed to analyze the performance of the call admission control scheme in the three-layered network handling overflowed voice traffic.
COMPARING VARIOUS CHANNEL ESTIMATION TECHNIQUES FOR OFDM SYSTEMS USING MATLABijwmn
This document compares the performance of five channel estimation techniques for OFDM systems over quasi-static channels using MATLAB simulations. The techniques evaluated are: decision directed (DD), linear interpolation, second-order interpolation, discrete Fourier transform (DFT) interpolation, and minimum mean square error (MMSE) interpolation. Simulation results show that DD channel estimation provides the lowest bit-error rate and mean square error, but has extra processing delay and is sensitive to channel variations. MMSE interpolation outperforms the other interpolation techniques.
An investigation-on-efficient-spreading-codes-for-transmitter-based-technique...Cemal Ardil
This document summarizes research on efficient spreading codes for transmitter-based techniques to mitigate interference in time division duplex code division multiple access (TDD/CDMA) downlink systems. It investigates bitwise and blockwise multiuser transmission schemes that transfer complexity to the transmitter. Different spreading codes are evaluated based on correlation properties to determine suitability for techniques like precoding, pre-rake, and rake diversity. Performance is measured by bit error rate with varying numbers of users to identify the most efficient codes for interference mitigation.
A Novel Routing Strategy Towards Achieving Ultra-Low End-to-End Latency in 6G...IJCNCJournal
Compared to 5G, 6G networks will demand even more ambitious reduction in endto-end latency for packet communication. Recent attempts at breaking the barrier of end-to-end millisecond latencies have focused on re-engineering networks using a hybrid approach consisting of an optical-fiber based backbone network architecture coupled with high-speed wireless networks to connect end-devices to the backbone network. In our approach, a wide area network (WAN) is considered with a high-speed optical fiber grid network as its backbone. After messages from a source node enter the backbone network through a local wireless network, these are delivered very fast to an access point in the backbone network closest to the destination node, followed by its transfer to the local wireless network for delivery to the destination node. We propose a novel routing strategy which is based on distributing the messages in the network in such a way that the average queuing delay of the messages through the backbone network is minimized, and also the route discovery time at each router in the backbone network is drastically reduced. Also, multiple messages destined towards a particular destination router in the backbone network are packed together to form a mailbag, allowing further reductions in processing overheads at intermediate routers and pipelining of mailbag formation and route discovery operations in each router. The performance of the proposed approach green based on these ideas has been theoretically analyzed and then simulated using the ns-3 simulator. Our results show that the average end-to-end latency is less than 380 µs (with only 46-79 µs within the backbone network under varying traffic conditions) for a 1 KB packet size, when using a 500 Gbps optical fiber based backbone network laid over a 15 Km × 15 Km area, a 50 Mbps uplink channel from the source to the backbone network, and a 1 Gbps downlink channel from the backbone network to the destination. The significant reduction in end-to-end latency as compared to existing routing solutions clearly demonstrates the potential of our proposed routing strategy for meeting the ultra-low latency requirements of current 5G and future 6G networks, particularly for mobile edge computing (MEC) application scenarios.
A novel optimal small cells deployment for next-generation cellular networks IJECEIAES
This document presents a novel approach to optimally deploy small cells in next-generation cellular networks. The approach aims to minimize total network installation costs, balance resource allocation among small cells, and provide optimal coverage with minimal interference between stations. An accurate formula is derived to determine the optimum number of small cell deployments. Mathematical expressions are also presented to calculate the critical handoff point between neighboring wireless stations. Simulation results demonstrate that the proposed approach can effectively alleviate interference and enhance coverage area compared to non-optimized small cell deployment strategies.
Matthew Weston is an experienced electrical fitter/mechanic with over 15 years of experience working in heavy industrial, mining, and LNG plant construction. He has extensive technical skills including installing, terminating, and inspecting industrial electrical equipment. He also has a strong safety record and various licenses and qualifications.
Patrik Glavica received the Oracle Certified Professional, Java SE 6 Programmer certification on February 25, 2015. The certification number associated with this achievement is 237196805OCPJSE6P.
Aliviar el estrés gracias a la risoterapiaPhilip2112
El documento describe los conceptos de estrés y sus causas. El estrés surge de una falta de correspondencia entre las necesidades percibidas y los mecanismos disponibles para hacerles frente. Esto puede deberse a requisitos excesivos o autoimpuestos, o a percibir amenazas donde no las hay. Para reducir el estrés, hay que reevaluar los requisitos y mejorar los mecanismos de afrontamiento como la comunicación y el control de impulsos. El estrés puede manifestarse física y emocionalmente, con síntomas que van desde dolores de cabeza
Dear Student,
DREAMWEB TECHNO SOLUTIONS is one of the Hardware Training and Software Development centre available in
Trichy. Pioneer in corporate training, DREAMWEB TECHNO SOLUTIONS provides training in all software
development and IT-related courses, such as Embedded Systems, VLSI, MATLAB, JAVA, J2EE, CIVIL,
Power Electronics, and Power Systems. It’s certified and experienced faculty members have the
competence to train students, provide consultancy to organizations, and develop strategic
solutions for clients by integrating existing and emerging technologies.
ADD: No:73/5, 3rd Floor, Sri Kamatchi Complex, Opp City Hospital, Salai Road, Trichy-18
Contact @ 7200021403/04
phone: 0431-4050403
ADAPTIVE RANDOM SPATIAL BASED CHANNEL ESTIMATION (ARSCE) FOR MILLIMETER WAVE ...IJCNCJournal
Millimeter-wave and mMIMO communications are the most essential success systems for next-generation wireless sensor networks to have enormous amounts of accessible throughput and spectrum. Through installing huge antenna arrays at the base station and performing coherent transceiver processing, mMIMO is a potential technology for enhancing the bandwidth efficiency of wireless sensor networks. The use of mmWave frequencies for mMIMO systems solves the problem of high path-loss through offering greater antenna gains. In this work, we provide a design with a random spatial sample structure that incorporates a totally random step before the analogue is received. It contains a totally random step before the analogue received signals are sent into the digital component of the HBF receiver. Adaptive random spatial based channel estimation (ARSCE) is proposed for channel session measurement collection, and an analogue combiner with valves has been used to estimate the signals at each receiving antenna. The proposed optimization problem formulation attempts to discover the orientations and gains of wideband channel routes. In addition, our proposed model has compared to various state-of-art techniques while considering error minimization.
Improving the network lifetime of mane ts through cooperative mac protocol de...Pvrtechnologies Nellore
The document proposes a novel cooperative MAC (CMAC) protocol called DEL-CMAC for improving the network lifetime of mobile ad hoc networks (MANETs). DEL-CMAC incorporates a distributed utility-based best relay selection strategy based on location information and residual energy. It also includes a cross-layer optimal transmitting power allocation scheme to conserve energy while maintaining throughput. Additionally, it provides an innovative network allocation vector setting to deal with interference from varying transmitting powers during cooperation. Simulation results show DEL-CMAC significantly prolongs network lifetime under different scenarios compared to the IEEE 802.11 standard and other throughput-focused CMAC protocols.
The document reviews different routing protocols for mobile ad hoc networks (MANETs). It begins with an introduction to MANETs and discusses some of their key characteristics including decentralized operation and dynamic topology. It then reviews several popular routing protocol categories for MANETs - flat, hierarchical, and location-based. Flat protocols like distance vector and link state are discussed as well as their limitations in dynamic MANET environments. The review covers over a dozen different specific routing protocols that have been proposed.
Modelling and QoS-Achieving Solution in full-duplex Cellular SystemsIJCNCJournal
The global bandwidth scarcity and the ever-growing demand for fast wireless services have motivated the quest for new techniques that enhance the spectral efficiency (SE) of wireless systems. Most conventional SE increasing methods (e.g., adaptive modulation and coding) have already been exhausted. Single-channel full-duplex (SCFD) communication is a new attractive approach in which each node may simultaneously receive and transmit over the same frequency channel, and thus, it has the potential to double the current SE figures. In this paper, we derive a model for the signal-to-interference-plus-noise ratio (SINR) in a SCFD-based cellular system with imperfect self-interference cancellation. Furthermore, given a set of uplink and downlink quality of service requirements, we answer the following two fundamental questions. First, is this set achievable in the SCFD-based cellular system? Second, if the given set is achievable, what is the optimal achieving policy? To that end, we provide a unified model for the SCFD-based cellular system, and give insights in the matrix of interference channel gains. Simulation results suggest that depending on the locations of the users, a combination of full-duplex and half-duplex modes over the whole network is more favourable policy
EFFICIENCY ENHANCEMENT BASED ON ALLOCATING BIZARRE PEAKSijwmn
A new work has been proposed in this paper in order to overcome one of the main drawbacks that found in
the Orthogonal Frequency Division Multiplex (OFDM) systems, namely Peak to Average Power Ratio
(PAPR). Furthermore, this work will be compared with a previously published work that uses the neural
network (NN) as a solution to remedy this deficiency.
The proposed work could be considered as a special averaging technique (SAT), which consists of wavelet
transformation in its first stage, a globally statistical adaptive detecting algorithm as a second stage; and
in the third stage it replaces the affected peaks by making use of moving average filter process. In the NN
work, the learning process makes use of a previously published work that is based on three linear coding
techniques.
In order to check the proposed work validity, a MATLAB simulation has been run and has two main
variables to compare with; namely BER and CCDF curves. This is true under the same bandwidth
occupancy and channel characteristics. Two types of tested data have been used; randomly generated data
and a practical data that have been extracted from a funded project entitled by ECEM. From the achieved
simulation results, the work that is based on SAT shows promising results in reducing the PAPR effect
reached up to 80% over the work in the literature and our previously published work. This means that this
work gives an extra reduction up to 15% of our previously published work. However, this achievement will
be under the cost of complexity. This penalty could be optimized by imposing the NN to the SAT work in
order to enhance the wireless systems performance.
International Journal of Computer Networks & Communications (IJCNC)IJCNCJournal
Beamforming for millimetre-wave (mmWave) frequencies has been studied for many years. It is considered as an important enabling technology for communications in these high-frequency ranges and it received a lot of attention in the research community. The special characteristics of the mmWave band made the beamforming problem a challenging one because it depends on many environmental and operational factors. These challenges made any model-based architecture fit only special applications, working scenarios, and specific environment geometry. All these reasons increased the need for more general machine learning based beamforming systems that can work in different environments and conditions. This increased the need for an extended adjustable dataset that can serve as a tool for any machine learning technique to build an efficient beamforming architecture. Deep MIMO dataset has been used in many architectures and designs and has proved its benefits and flexibility to fit in many cases. In this paper, we study the extension of collaborative beamforming that includes many cooperating base stations by studying the impact of User Equipment (UE) speed ranges on the beamforming performance, optimizing the parameters of the neural network architecture of the beamforming design, and suggesting the optimal design that gives the best performance for as a small dataset as possible. Suggested architecture can achieve the same performance achieved before with up to 33% reduction in the dataset size used to train the system which provides a huge reduction in the data collection and processing time.
DYNAMIC HYBRID CHANNEL (WMN) FOR BANDWIDTH GUARANTEES IN AD_HOC NETWORKSpharmaindexing
This document discusses bandwidth guarantees in wireless mesh networks. It proposes a new routing technique called dynamic hybrid channel, which uses both proactive and reactive routing protocols based on AOMDV. The goal is to provide bandwidth guarantees by selecting multiple paths and using the path with the highest available bandwidth for transmission. The performance of this approach is evaluated using the NS-2 network simulator. Several challenges of wireless mesh networks are also discussed, such as interference reduction and improving throughput across multiple hops.
CL-SA-OFDM: cross-layer and smart antenna based OFDM system performance enha...IJECEIAES
The growing usage of wireless services is lacking in providing high-speed data communication in recent times. Hence, many of the modulation techniques are evolved to attain these communication needs. The recent researches have widely considered OFDM technology as the prominent modulation mechanism to fulfill the futuristic needs of wireless communication. The OFDM can bring effective usage of resources, bandwidth, and system performance enhancement in collaboration with the smart antenna and resource allocation mechanism (adaptive). However, the usage of adaptive beamforming with the OFDM leads to complication in the design of medium access layer and which causes a problem in adaptive resource allocation mechanism (ARAM). Hence, the proposed manuscript intends to design an OFDM system by considering different switched beam smart antenna (SBSA) along with the cross-layer adaptive resource allocation (CLARA) and hybrid adaptive array (HAA). In this, various smart antenna mechanism are considered to analyze the quality of service (QoS) and complexity reduction in the OFDM system. In this paper, various SA schemes are used as per the quality of service (QoS) requirement of the different users. The performance analysis is conducted by considering data traffic reduction, bit-rate reduction, and average delay.
ADAPTIVE SENSOR SENSING RANGE TO MAXIMISE LIFETIME OF WIRELESS SENSOR NETWORK IJCNCJournal
Wireless Sensor Network (WSN) is commonly used to collect information from a remote area and one of the most important challenges associated with WSN is to monitor all targets in a given area while maximizing network lifetime. In wireless communication, energy consumption is proportional to the breadth of sensing range and path loss exponent. Hence, the energy consumption of communication can be minimized by varying the sensing range and decreasing the number of messages being sent. Sensing energy can be optimized by reducing the repeated coverage target. In this paper, an Adaptive Sensor Sensing Range (ASSR) technique is proposed to maximize the WSN Lifetime. This work considers a sensor network with an adaptive sensing range that are randomly deployed in the monitoring area. The sensor is adaptive in nature and can be modified in order to save power while achieving maximum time of monitoring to increase the lifetime of WSN network. The objective of ASSR is to find the best sensing range for each sensor to cover all targets in the network, which yields maximize the time of monitoring of all targets and eliminating double sensing for the same target. Experiments were conducted using an NS3 simulator to verify our proposed technique. Results show that ASSR is capable to improve the network lifetime by 20% as compared to other recent techniques in the case of a small network while achieving an 8% improvement for the case of a large networks.
Performance Analysis of Energy Optimized LTE-V2X Networks for Delay Sensitive...IJCNCJournal
This document analyzes the performance of three uplink transmission modes - single-hop direct, multi-hop cellular V2X, and store-carry-forward (SCF) - for delay sensitive real-time services in LTE-V2X networks. It presents a highway system model and compares the total energy consumption and transmission delay of the three modes using numerical simulations validated with ns-3. The results show that SCF mode consumes the least energy due to its carry phase, but incurs high delays unacceptable for real-time applications. Single-hop direct has the reverse performance. Multi-hop cellular V2X outperforms in terms of balancing low latency and moderate energy consumption beyond a cell radius of 600
This document presents a novel Cross-layer Mesh Router Placement (CMRP) scheme for wireless mesh networks. CMRP aims to minimize network deployment cost while meeting user demands. It considers various factors such as antenna types, wireless link characteristics, MAC scheduling, routing, and equipment costs. CMRP encapsulates these cross-layer factors into three attributes - Local Coverage, Backbone Residual Capacity, and Deployment Cost. It uses these attributes to select mesh router locations that maximize coverage and backbone capacity while minimizing costs. Simulations show CMRP outperforms existing schemes in cost performance ratio and feasibility for planning wireless mesh networks.
A NURBS-optimized dRRM solution in a mono-channel condition for IEEE 802.11 e...IJECEIAES
This document describes a NURBS-optimized dynamic radio resource management (dRRM) solution for IEEE 802.11 enterprise WLAN networks called N-WLCx. The authors present their original dRRM solution called WLCx, which uses a novel per-beam coverage representation approach. To reduce the high processing time of WLCx, they developed an optimization based on NURBS (Non-Uniform Rational B-Spline) surfaces. Simulation results show N-WLCx achieves a 92.58% reduction in processing time compared to the basic WLCx solution. The authors conclude N-WLCx optimization could be extended to enhance other vendors' and researchers' RRM solutions for improved efficiency
Teletraffic Analysis of Overflowed Traffic with Voice only in Multilayer 3G W...IRJET Journal
This document presents a study analyzing the traffic overflow performance of a three-layered wireless mobile network with microcells, macrocells and satellite cells handling voice-only traffic. The three-layered hierarchical network structure is described, with microcells overlaid by macrocells and macrocells overlaid by satellite cells. An existing call admission control scheme is evaluated that prioritizes voice calls, including handling call blocking probabilities, channel utilization, and call dropping probabilities across the different cell layers under varying traffic parameters. Analytical models are developed and numerical calculations are performed to analyze the performance of the call admission control scheme in the three-layered network handling overflowed voice traffic.
COMPARING VARIOUS CHANNEL ESTIMATION TECHNIQUES FOR OFDM SYSTEMS USING MATLABijwmn
This document compares the performance of five channel estimation techniques for OFDM systems over quasi-static channels using MATLAB simulations. The techniques evaluated are: decision directed (DD), linear interpolation, second-order interpolation, discrete Fourier transform (DFT) interpolation, and minimum mean square error (MMSE) interpolation. Simulation results show that DD channel estimation provides the lowest bit-error rate and mean square error, but has extra processing delay and is sensitive to channel variations. MMSE interpolation outperforms the other interpolation techniques.
An investigation-on-efficient-spreading-codes-for-transmitter-based-technique...Cemal Ardil
This document summarizes research on efficient spreading codes for transmitter-based techniques to mitigate interference in time division duplex code division multiple access (TDD/CDMA) downlink systems. It investigates bitwise and blockwise multiuser transmission schemes that transfer complexity to the transmitter. Different spreading codes are evaluated based on correlation properties to determine suitability for techniques like precoding, pre-rake, and rake diversity. Performance is measured by bit error rate with varying numbers of users to identify the most efficient codes for interference mitigation.
A Novel Routing Strategy Towards Achieving Ultra-Low End-to-End Latency in 6G...IJCNCJournal
Compared to 5G, 6G networks will demand even more ambitious reduction in endto-end latency for packet communication. Recent attempts at breaking the barrier of end-to-end millisecond latencies have focused on re-engineering networks using a hybrid approach consisting of an optical-fiber based backbone network architecture coupled with high-speed wireless networks to connect end-devices to the backbone network. In our approach, a wide area network (WAN) is considered with a high-speed optical fiber grid network as its backbone. After messages from a source node enter the backbone network through a local wireless network, these are delivered very fast to an access point in the backbone network closest to the destination node, followed by its transfer to the local wireless network for delivery to the destination node. We propose a novel routing strategy which is based on distributing the messages in the network in such a way that the average queuing delay of the messages through the backbone network is minimized, and also the route discovery time at each router in the backbone network is drastically reduced. Also, multiple messages destined towards a particular destination router in the backbone network are packed together to form a mailbag, allowing further reductions in processing overheads at intermediate routers and pipelining of mailbag formation and route discovery operations in each router. The performance of the proposed approach green based on these ideas has been theoretically analyzed and then simulated using the ns-3 simulator. Our results show that the average end-to-end latency is less than 380 µs (with only 46-79 µs within the backbone network under varying traffic conditions) for a 1 KB packet size, when using a 500 Gbps optical fiber based backbone network laid over a 15 Km × 15 Km area, a 50 Mbps uplink channel from the source to the backbone network, and a 1 Gbps downlink channel from the backbone network to the destination. The significant reduction in end-to-end latency as compared to existing routing solutions clearly demonstrates the potential of our proposed routing strategy for meeting the ultra-low latency requirements of current 5G and future 6G networks, particularly for mobile edge computing (MEC) application scenarios.
A novel optimal small cells deployment for next-generation cellular networks IJECEIAES
This document presents a novel approach to optimally deploy small cells in next-generation cellular networks. The approach aims to minimize total network installation costs, balance resource allocation among small cells, and provide optimal coverage with minimal interference between stations. An accurate formula is derived to determine the optimum number of small cell deployments. Mathematical expressions are also presented to calculate the critical handoff point between neighboring wireless stations. Simulation results demonstrate that the proposed approach can effectively alleviate interference and enhance coverage area compared to non-optimized small cell deployment strategies.
Matthew Weston is an experienced electrical fitter/mechanic with over 15 years of experience working in heavy industrial, mining, and LNG plant construction. He has extensive technical skills including installing, terminating, and inspecting industrial electrical equipment. He also has a strong safety record and various licenses and qualifications.
Patrik Glavica received the Oracle Certified Professional, Java SE 6 Programmer certification on February 25, 2015. The certification number associated with this achievement is 237196805OCPJSE6P.
Aliviar el estrés gracias a la risoterapiaPhilip2112
El documento describe los conceptos de estrés y sus causas. El estrés surge de una falta de correspondencia entre las necesidades percibidas y los mecanismos disponibles para hacerles frente. Esto puede deberse a requisitos excesivos o autoimpuestos, o a percibir amenazas donde no las hay. Para reducir el estrés, hay que reevaluar los requisitos y mejorar los mecanismos de afrontamiento como la comunicación y el control de impulsos. El estrés puede manifestarse física y emocionalmente, con síntomas que van desde dolores de cabeza
ITM BUILDING GUIDE: SUSTAINABLE BUILDING
Produced in association with BRANZ to provide builders and homeowners with practical, common sense information on energy and water efficiency, air quality and selecting more sustainable building materials.
El documento presenta 5 tendencias educativas clave para el 2016: 1) El proceso de enseñanza-aprendizaje se personalizará, 2) Los profesores apostarán por nuevas metodologías como flipped classroom y aprendizaje por proyectos, 3) Los alumnos aprenderán de forma activa, 4) Las aulas serán más flexibles y 5) Las TIC como ordenadores y libros digitales serán esenciales permitiendo estudiar en cualquier momento y lugar.
Pratiques sociales en formation à distance : entre solitude et abandonClément Dussarps
Présentation effectuée lors du colloque M@RSOUIN en 2014 sur mes travaux de thèse. Il s'agit de comprendre comment la solitude participe à l'abandon en formation ouverte et à distance.
Benchmarking Informatico de sistemas de gestión de video open sourceVale Perez Cepeda
Este documento presenta el trabajo de graduación de Valeria Pérez titulado "Benchmarking informático para la implementación de una plataforma Open Source de seguimiento por video streaming en la empresa INEDYC de la ciudad de Ambato". El trabajo realiza una investigación y evaluación comparativa de sistemas de video vigilancia abiertos para seleccionar la mejor opción para la empresa INEDYC. Se utiliza la técnica de medición o monitoreo para ejecutar pruebas de benchmarking a los sistemas Zoneminder y Motion, midiendo parámetros como tiempo de respuesta,
Word es un procesador de texto que permite crear y editar documentos. Forma parte de Microsoft Office y permite realizar tareas de oficina como redactar textos con diferentes fuentes, tamaños y colores de letra, e incluye herramientas como un corrector ortográfico. Word es un software propietario cuya licencia debe ser adquirida para su uso.
method for enhancement of coexistence between e gsm and cdma systems in borde...INFOGAIN PUBLICATION
This paper presents a possible method for enhancement of co-existence of an E-GSM system based network with a CDMA sustem based network, in border area between two countries. Since the frequency bands allocated for the deployment of previous mentioned networks can partially overlap and due to the fact that the downlink frequency band of CDMA system is in the same frequrency band as the uplink of E-GSM system, the co-existence of the systems represents a challenge for the spectrum enineering process. In this paper a method for sharing the frequency band between the two countries under discussion is presented, in order to offer an equitable access to limited spectrum resources. Under this approach, there are settled common technical principles of a coordination procedure between country A and country B.
Spectrum sharing in cognitive radio networks IJECEIAES
Cognitive radio networks are the next step to tackle scarcity in wireless networks given the increasing demand of radioelectric spectrum where the proposed solution is to share said resource to improve this situation. In the present article, a review of the current state of spectrum sharing in cognitive radio networks. To achieve this purpose, the articles published over the last 4 years on the matter were reviewed including topics such as mobile networks and TV. Some studies and simulations proposed to share the spectrum is shown. The current state of the studies reveals that there has been significant progress in this research area yet it is necessary to continue similar studies and set in motion different schemes.
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.
PERFORMANCE ANALYSIS OF THE LINK-ADAPTIVE COOPERATIVE AMPLIFY-AND-FORWARD REL...IJCNCJournal
This paper analyzes the performance of cooperative amplify-and-forward (CAF) relay networks that
employ adaptive M-ary quadrature amplitude modulation (M-QAM)/M-ary phase shift keying (M-PSK)
digital modulation techniques in Nakagami-m fading channel. In particular, we present and compared the
analysis of CAF relay networks with different cooperative diversity and opportunistic routing strategies
such as regular Maximal Ratio Combining (MRC), Selection Diversity Combining (SDC), Opportunistic
Relay Selection with Maximal Ratio Combining (ORS-MRC) and Opportunistic Relay Selection with
Selection Diversity Combining (ORS-SDC). We advocate a simple yet unified numerical approach based on
the marginal moment generating function (MGF) of the total received SNR to compute the average symbol
error rate (ASER), mean achievable spectral efficiency, and outage probability performance metrics.
The document is the International Journal of Electronics and Communication Engineering & Technology (IJECET) from January 2014. It discusses a hybrid optimization method for multi-user detection in SDMA-OFDM systems that combines genetic algorithms and particle swarm optimization. This approach aims to overcome limitations of existing detection methods. The hybrid method is shown to provide better performance than minimum mean square error and maximum likelihood detection, especially when the number of users is high relative to base station antennas. The document provides details on the proposed hybrid method and compares its performance to other approaches through simulation.
Optical network is an emerging technology for data communication
inworldwide. The information is transmitted from the source to destination
through the fiber optics. All optical network (AON) provides good
transmission transparency, good expandability, large bandwidth, lower bit
error rate (BER), and high processing speed. Link failure and node failure
haveconsistently occurred in the traditional methods. In order to overcome
the above mentioned issues, this paper proposes a robust software defined
switching enabled fault localization framework (SDSFLF) to monitor the
node and link failure in an AON. In this work, a novel faulty node
localization (FNL) algorithm is exploited to locate the faulty node. Then, the
software defined faulty link detection (SDFLD) algorithm that addresses the
problem of link failure. The failures are localized in multi traffic stream
(MTS) and multi agent system (MAS). Thus, the throughput is improved in
SDSFLF compared than other existing methods like traditional routing and
wavelength assignment (RWA), simulated annealing (SA) algorithm, attackaware RWA (A-RWA) convex, longest path first (LPF) ordering, and
biggest source-destination node degree (BND) ordering. The performance of
the proposed algorithm is evaluated in terms of network load, wavelength
utilization, packet loss rate, and burst loss rate. Hence, proposed SDSFLF
assures that high performance is achieved than other traditional techniques.
Adaptive Multi-state Millimeter Wave Cell Selection Scheme for 5G communicati...IJECEIAES
Millimeter wave bands have been introduced as one of the most promising solutions to alleviate the spectrum secrecy in the upcoming future cellular technology (5G) due the enormous amount of raw bandwidth available in these bands. However, the inherent propagation characteristics of mmWave frequencies could impose new challenges i.e. higher path loss, atmospheric absorption, and rain attenuation which in turn increase the outage probability and hence, degrading the overall system performance. Therefore, in this paper, a novel flexible scheme is proposed namely Adaptive Multi-State MmWave Cell Selection (AMSMCS) through adopting three classes of mmWave base stations, able to operate at various mmWave carrier frequencies (73, 38 and 28 GHz). Two mmWave cellular Grid-Based cell deployment scenarios have been implemented with two inter-site-distances 200 m and 300 m, corresponding to target area of (2.1 km2) and (2.2 km2). The maximum SINR value at the user equipment (UE) is taken in to consideration to enrich the mobile user experience. Numerical results show an improvement of overall system performance, where the outage probability reduced significantly to zero while maintaining an acceptable performance of the 5G systems with approximately more than 50% of the mobile stations with more than 1Gbps data rate.
IRJET- Review Paper on Call Admission Control with Bandwidth Reservation Sche...IRJET Journal
This document reviews call admission control schemes with bandwidth reservation in wireless communication systems. It begins with an abstract that discusses energy savings opportunities in heterogeneous networks, including issues like sleep/wake cycles and interference management. It then reviews the literature on call admission control, discussing types like deterministic vs stochastic, uplink vs downlink-focused, and those using cell occupancy, mobility, or individual user information. The document presents a system model of a wireless network with call and handoff connections between cells. It discusses heterogeneous network deployment with single-RAT and multi-RAT configurations. It analyzes the energy efficiency of an LTE-WiFi heterogeneous network using simulation, comparing a WLAN-first selection scheme with and without call admission control.
This document reviews the Security and QoS Aware Dynamic Clustering (SQADC) Routing protocol for cognitive radio networks (CRNs). It first discusses existing routing protocols for CRNs and identifies gaps, including that most focus on improving quality of service but few address security issues. It then outlines the objectives of designing a new routing protocol to achieve a tradeoff between QoS performance and security performance for CRNs. The proposed SQADC protocol will use dynamic clustering based on ant colony optimization for cluster head selection and re-clustering to optimize spectrum allocation and quality of service while introducing a lightweight trust-based mechanism for detecting malicious nodes.
The document summarizes a proposed scheduling technique called Real Time Conflict-free Query Scheduling (RTCQS) for wireless sensor networks. RTCQS aims to increase throughput for high data rate sensor applications while supporting real-time queries. It uses a query planner to construct transmission plans for queries as sequential conflict-free steps. A query scheduler then schedules the query instances, using preemption for higher priority queries or concurrent execution when no conflicts exist. The goal is high throughput, low latency, and adaptability to varying workloads.
The document summarizes a proposed scheduling technique called Real Time Conflict-free Query Scheduling (RTCQS) for wireless sensor networks. RTCQS aims to increase throughput for high data rate sensor applications while supporting real-time queries. It uses a query planner to construct transmission plans for queries as sequential conflict-free steps. A query scheduler then schedules the query instances, using preemption for higher priority queries or concurrent execution when no conflicts exist. The goal is high throughput, low latency, and adaptability to varying workloads.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
The impact of channel model on the performance of distance-based schemes in v...IJECEIAES
This document discusses three distance-based schemes - RNDN, EVNDN, and OIFP - for data dissemination in vehicular named data networks (VNDNs). It evaluates the impact of different propagation models (Friis, Nakagami, random) on the performance of these schemes. Simulation results show that the Nakagami model significantly degrades network performance and increases retransmissions for RNDN. EVNDN sees more retransmissions under Friis and random models. OIFP exhibits higher interest satisfaction ratios and lower delays compared to the other schemes under all models. The document concludes that propagation models have a noticeable effect on distance-based scheme performance in VNDNs.
The improvement of end to end delays in network management system using netwo...IJCNCJournal
The document summarizes research on improving end-to-end delays in a network management system using network coding. Specifically, it applies network coding to manage radio and television broadcast stations in a wireless network. The study shows that a proposed "Fast Forwarding Strategy" using network coding outperforms a classical routing strategy in reducing end-to-end delays from source to destination. It analyzes end-to-end delays theoretically using network calculus and conducts a practical study on a network of broadcast stations, finding the proposed strategy reduces delays compared to the classical strategy.
Spectrum Sharing between Cellular and Wi-Fi Networks based on Deep Reinforcem...IJCNCJournal
Recently, mobile traf ic is growing rapidly and spectrum resources are becoming scarce in wireless
networks. Due to this, the wireless network capacity will not meet the traf ic demand. To address this
problem, using cellular systems in an unlicensed spectrum emerged as an ef ective solution. In this case,
cellular systems need to coexist with Wi-Fi and other systems. For that, we propose an ef icient channel
assignment method for Wi-Fi AP and cellular NB, based on the DRL method. To train the DDQN model,
we implement an emulator as an environment for spectrum sharing in densely deployed NB and APs in
wireless heterogeneous networks. Our proposed DDQN algorithm improves the average throughput from
25.5% to 48.7% in dif erent user arrival rates compared to the conventional method. We evaluated the
generalization performance of the trained agent, to confirm channel allocation ef iciency in terms of
average throughput under the dif erent user arrival rates
Spectrum Sharing between Cellular and Wi-Fi Networks based on Deep Reinforcem...IJCNCJournal
Recently, mobile traffic is growing rapidly and spectrum resources are becoming scarce in wireless networks. Due to this, the wireless network capacity will not meet the traffic demand. To address this problem, using cellular systems in an unlicensed spectrum emerged as an effective solution. In this case, cellular systems need to coexist with Wi-Fi and other systems. For that, we propose an efficient channel assignment method for Wi-Fi AP and cellular NB, based on the DRL method. To train the DDQN model, we implement an emulator as an environment for spectrum sharing in densely deployed NB and APs in wireless heterogeneous networks. Our proposed DDQN algorithm improves the average throughput from 25.5% to 48.7% in different user arrival rates compared to the conventional method. We evaluated the generalization performance of the trained agent, to confirm channel allocation efficiency in terms of average throughput under the different user arrival rates.
Congestion control, routing, and scheduling 2015parry prabhu
This document summarizes a research paper about congestion control, routing, and scheduling in wireless networks with interference cancellation capabilities. It discusses using successive interference cancellation (SIC) to allow multiple concurrent transmissions and increase network capacity. The paper formulates the joint congestion control, routing, and scheduling problem and solves it in a distributed manner using dual decomposition. It develops a decentralized algorithm for link scheduling under the physical SINR interference model that coordinates local transmissions and achieves similar results to centralized greedy maximal scheduling. The paper evaluates the performance gains from SIC and shows that network flows can achieve up to twice their rates compared to networks without interference cancellation.
IRJET- MIMO-Energy Efficient and Spectrum Analysis using Congnitive Radio Tec...IRJET Journal
This document summarizes research on improving energy efficiency and spectrum utilization in wireless networks using MIMO and cognitive radio technologies. It proposes using a parametric method for cognitive radio networks, where priority is given to unused channels to allow secondary users to opportunistically access the spectrum without interfering with primary transmissions. Matlab simulations demonstrate how this approach allows a secondary user to identify and use an unused channel based on the occupancy status of channels used by five primary users. The parametric method and priority checking enable more efficient spectrum sharing while avoiding interference.
ABSTRACT : Performance enhancement of smart antennas versus their complexity for commercial wireless
applications. The goal of the study presented in this paper is to investigate the performance improvement
attainable using relatively simple smart antenna techniques when applied to the third-generation W-CDMA air
interface. Methods to achieve this goal include fixed multi beam architectures with different beam selection
algorithms (maximum power criterion, combined beams) or adaptive solutions driven by relatively simple direction
finding algorithms. After comparing these methods against each other for several representative scenarios, some
issues related to the sensitivity of these methods are also studied, (e.g., robustness to environment, mismatches
originating from implementation limitations, etc.). Results indicate that overall, conventional beam forming
seems to be the best choice in terms of balancing the performance and complexity requirements, in particular
when the problem with interfering high-bit-rate W-CDMA 3g users is considered.
A Broadband Wireless Access technology known as
Worldwide Interoperability for Microwave Access (WiMAX) is
based on IEEE 802.16 standards. It uses orthogonal frequency
division multiple accesses (OFDMA) as one of its multiple access
technique. Major design factors of OFDMA resource allocation are
scheduling and burst allocation. To calculate the appropriate
dimensions and location of each user’s data so as to construct the
bursts in the downlink subframe, is the responsibility of burst
allocation algorithm. Bursts are calculated in terms of number of
slots for each user. Burst Allocation Algorithm is used to overcome
the resource wastage in the form of unused and unallocated slots per
frame. It affects the Base station performance in mobile WiMAX
systems. In this Paper, HOCSA (Hybrid One Column Striping with
Non Increasing Area) algorithm is proposed to overcome frame
wastage. HOCSA is implemented by improving eOCSA algorithm
and is evaluated using MATLAB. HOCSA achieves significant
reduction of resource wastage per frame, leading to more
exploitation of the WiMAX frame.
Similar to Interoperator Dynamic Spectrum Sharing (Analysis, Costs and Implications) (20)
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Interoperator Dynamic Spectrum Sharing (Analysis, Costs and Implications)
1. G Salami, R.Tafazolli
International Journal of Computer Networks, Volume (2): Issue (1) 47
Inter-operator Dynamic Spectrum Sharing (Analysis, Cost and
Implications)
Gbenga Salami g.salami@surrey.ac.uk
Center for Communication Systems Research
University of Surrey,
Guildford, GU2 7XH, United Kingdom
Rahim Tafazolli r.tafazolli@surrey.ac.uk
Center for Communication Systems Research
University of Surrey,
Guildford, GU2 7XH, United Kingdom
Abstract
This paper addresses Dynamic Spectrum Sharing (DSS) between two wireless
operators. The Universal Mobile Telecommunication System (UMTS) network is
used as a case study. The proposed protocol is evaluated under the uniform and
non-uniform traffic conditions. The underlying principles of the algorithm can be
deployed in the UMTS extension Band (2500MHz-2690MHz) which is yet to be
allocated or the re-farmed GSM spectrum (900MHz/1800MHz). The simulation
results for the proposed protocol shows that significant spectrum sharing gains
can be obtained. However such spectrum efficiency gain need to be carefully
balanced with the complexity in terms of latency (delays) and additional overhead
it brings to the network. The results show that significant spectrum sharing gain
of 4.0 % and 2.0 % can be obtained under uniform and non-uniform traffic
conditions.
Keywords: Dynamic spectrum sharing, fixed spectrum allocation, call setup, queuing.
1. INTRODUCTION
Several measurement studies have indicated that the finite spectrum resource is not efficiently
utilized [1] [2]. When the scarce spectrum resource is viewed dynamically as a function of time
(temporal variations) and space (spatial variation) or a combination of both, there exists
“spectrum opportunities or holes” that require more efficient techniques in order to be exploited.
The traditional spectrum management method is known as Fixed Spectrum Allocation (FSA).
FSA is simple and effectively controls interference through the use of a guard band. However, it
has three main deficiencies; it is static, inefficient and it limits innovation or rapid deployment of
new technologies [3]. This is because spectrum licenses and hence chunks of spectrum blocks
are issued in an exclusive manner to the network provider/operator. Therefore a new network
provider/operator is not allowed to use this spectrum during the idle or less busy periods.
The future/next generation wireless network will consist of a plethora of heterogeneous networks.
In order to satisfy the service demands of these complex networks, Dynamic Spectrum Access
(DSA) provides a very promising solution to address the problem of spectrum underutilization [4]
[5]. The DSA solutions can be centralized [6] [7], distributed [8] or a combination of both. A
2. G Salami, R.Tafazolli
International Journal of Computer Networks, Volume (2): Issue (1) 48
classification of these solutions according to the intelligent decision maker together with the
advantages and disadvantages of each approach is presented in [9].
The successful realization of DSA schemes will depend on the elimination of a number of
technical, economic and regulatory barriers. These barriers are highlighted in [5]. A detailed
survey on the challenges to be addressed within the context of opportunistic spectrum access is
presented in [4] [5] [10]. These papers have outlined the key requirements involved in the design
of DSA schemes for next generation wireless systems. The requirements include: architectural
design requirements, techniques to effectively identify reuse opportunities (spectrum sensing),
efficient exploitation of detected opportunities through adaptive transmission and modulation
waveforms, reconfigurability, the release of the resource once communication has ended
(spectrum mobility) and interference mitigation mechanisms [10]. A framework for hierarchical
spectrum management in a heterogeneous network is presented in [11]. The successful
management of DSA networks involves specialized “protocols” and “policies”. An example of
such a policy is discussed in [12]. The goals of these spectrum sharing protocols are usually
multi-objective in nature. The protocols should ensure efficient and fair use of the spectrum in a
stable manner by allowing secondary users into the white spaces, while at the same time
minimizing harmful interference to the licensed primary users of the spectrum.
The main contributions of this paper are as follows; the paper describes a spectrum access
framework for the evaluation of spectrum sharing algorithms. The proposed protocol takes into
account the fact that although the peak period may coincide, the differential loading during the
peak hour between two operator’s traffic pattern provides sufficient gain which can be exploited to
improve system capacity and hence spectrum efficiency gain. The characterization depicted here
represents the lower bound conditions (worst case scenario). It has been shown in [22] that the
spectrum efficiency gain increases significantly in un-correlated traffic situations. The simulated
performance takes into account soft handover and Inter-operator interference in the form of
Adjacent Channel Interference (ACI). The impact of ACI is particularly important if the operator
base stations are non-co-located and displaced by distance (d). This effect serves to reduce the
achievable capacity gain for DSS, since in the real world base stations belonging to different
operators are more likely to be displaced.
Secondly, the paper has evaluated the call setup latency associated with the proposed algorithm,
since longer call setup times will be expected if the User Equipment (UE) is unable to seek
connection on its initial network. Furthermore the overhead cost in the form of call setup
messages is also presented. The overall aim is to provide a guideline for wireless operators in the
selection of an appropriate scheme, taking into account the spectrum efficiency gains and the
associated penalty or complexity resulting from the use of such DSS schemes.
Similarly, the algorithm takes into account uniform and non-uniform traffic cases. In the non-
uniform traffic case, hotspots cell areas have been included in the model. Hotspots are areas of
temporarily high call volume occurring statically or dynamically, due to specific events such as
campaign rallies, sporting events, airports etc.
The work presented in this paper addresses a case study involving two UMTS operators sharing
spectrum and may be deployed in any band as stated earlier. Furthermore, this paper proposes
the architecture for enabling co-operative spectrum sharing between two UMTS operators. A
major component of any DSA scheme is the signaling cost and control information overhead
associated with it. Therefore central to the implementation of any spectrum sharing algorithm is
the determination of the cross-over point at which spectrum sharing may be detrimental to the
network. This paper gives an insight into the signaling overhead (call setup delays) involved in the
proposed schemes.
The remainder of this paper is structured as follows. Section II introduces the spectrum access
framework and the cases investigated. Section III and Section IV gives the details of the system
model and algorithm description respectively. Section V analyses the call setup delays. The
simulation metrics and DSA performance results are presented in Section VI. This section also
gives a discussion of the results. The conclusions and future work plans are outlined in Section
VII.
3. G Salami, R.Tafazolli
International Journal of Computer Networks, Volume (2): Issue (1) 49
2. RELATED WORK
DARPA Next Generation (XG) [13] has initially investigated dynamic spectrum access with the
aim of developing new technologies and system concepts (including new waveforms) to
intelligently redistribute the spectrum through opportunistic access. Since the early 1990s, DSA
has been formerly studied under the heading of Dynamic Channel Allocation (DCA) [14]. In 2000,
the European projects such as the DRIVE [15] and its successor OVERDRIVE [16] have
proposed network centric algorithms such as contiguous and fragmented schemes for addressing
dynamic spectrum access. This investigation quantifies the spectrum efficiency gain in UMTS-
DVB-T sharing scenario to be about twenty nine percent. More recently in 2008, the work in [17]
under the E
2
R II (End to End Reconfigurability) project applies genetic algorithm to solve the
optimization problem involved in cell-by-cell DSA. This work reported a spectrum efficiency gain
of 38 % and 41 % respectively under uniform and non-uniform traffic conditions. Reconfigurability
is an important practical enabler of DSA systems. The European project E
2
R project, and its
follow up E
2
RII [18], have focused on different aspects of radio reconfigurability, spectrum
sharing, and CR implementation in a test-bed. In [18], the factors for achieving this are captured
in three-dimensional spaces: technical, economic and regulatory. The technical requirements
(radio segment and network segment) can further be broken into a multi-dimensional space
composed of service (s), time (t), space (sp) (i.e. location), frequency (f), and RAT dimensions. In
2009, the End to End Efficiency (E
3
) project [19] funded by the European Union aims to address
the integration of Cognitive Wireless networks into beyond 3G network. A further manifestation of
the intense interest within the research community in this area is demonstrated by the numerous
publications in the IEEE conferences DySPAN [20], CROWNCOM [21].
2.1 Spectrum Access Framework
In order to adequately develop a Spectrum Access Framework, it is important to understand the
variety of spectrum sharing models available in literature. The authors in [4] [23] have provided a
detailed classification of the different types of sharing options. This paper focuses on a
centralized mechanism for spectrum sharing between two operators using the same technology.
The traffic demand of Network Operator A is given by (D1A, D2A, D3A, ........,DNA) at time intervals
(t1, t2, t3, t4........., tn), similarly for Network Operator B, the traffic demand is given by (D1B, D2B,
D3B,......,DNB) at time intervals (t1, t2, t3, t4,........, tn). It can be seen that although the operator may
have the same peak hour periods, this does not necessarily mean that the two operators have
exactly the same peak load.
The traffic profile for the two operators is exactly the same. The peaks coincide as shown in Fig.1.
A realistic traffic model inspired by [1] [24] is used in this paper. Fig. 1 shows the normalized
traffic profile of the two operators (initially measured in calls/cell/hour), with similar peak periods
occurring at 8-10 am (morning) and 4-6 pm (evening).
FIGURE 1: Showing normalized traffic profile for two networks
4. G Salami, R.Tafazolli
International Journal of Computer Networks, Volume (2): Issue (1) 50
A closer look at the Fig. 1 indicate that although the peaks coincide there are instantaneous
opportunities that could be exploited during the peak hour due to statistical multiplexing of call
arrivals. This represents the worst case scenario and it gives the lower bound on the spectrum
efficiency gain. These instantaneous fluctuations are captured in Fig. 2.
.
In order to properly address spectrum sharing, the papers in [8], [17] have proposed a
hierarchical solution. Fig. 3 presents an architectural enabler to facilitate spectrum sharing
between two operators. The Spectrum Management Entity (SME) controls all spectrum related
activity such as user migration between networks, carrier allocation and release. The architecture
allows resource optimization to occur at different levels from intra-network to inter-network.
.
FIGURE 2: Instantaneous variation in peak hour load for two
networks with similar traffic profile.
RAN 1
Meta-operator with
global spectrum
view
SME1: Spectrum
Management entity
SME2: Spectrum
management entity
Operator A
Operator B
RAN 3RAN 2
Inter-operator Inter RAT
(High level Spectrum Management)
(HLSM)
Intra operator-Intra RAT
(Low level spectrum management)
(LLSM)
RNC
RNC
RNC
Intra-operator-Inter RAT
(Medium level Spectrum Management)
(MLSM)
RAN 1
FIGURE 3: Architectural enabler for UMTS spectrum sharing showing interfaces and network
elements.
5. G Salami, R.Tafazolli
International Journal of Computer Networks, Volume (2): Issue (1) 51
This paper presents an algorithm description of the component required at the different levels of
the spectrum access framework. It is important to note that at each level, resource optimization is
required using a combination of legacy and new techniques (power control, call admission
control, load balancing and inter-operator resource scheduling etc) in order to achieve the desired
overall spectrum efficiency gain.
Based on Fig. 4, a resource allocation request in the network triggers the low level spectrum
management functionality (LLSM). The specific techniques at this level will encompass intra-
operator intra-RAT resource management strategies. The time scale for this operation is also
considered to be of the order of milliseconds. If the resource optimization criteria can be met at
this level no further interaction with the MLSM entity is necessary and the resource is granted to
the user. The inability of the system to satisfy the UE at the lower level triggers the Medium Level
Spectrum Management (MLSM) subsystem. This subsystem includes a number of intra-operator
inter-RAT resource management techniques. The time scale for the MLSM operation is longer
compared to the LLSM but shorter compared to the HLSM. This will be of the order of few
minutes. The failure of MLSM to address the spectrum needs of the user triggers the HLSM
functionality.
(resource allocation request)
Can target be met by
management functionality
(LLSM)
Triggers Low level spectrum
management functionality
(Intra-operator intra-RAT
RRM)
Trigger Medium level
spectrum management
functionality (Intra-operator
inter-RAT RRM)
Can target be met by
management functionality
(MLSM)
Trigger High level spectrum
management functionality
(Inter operator inter-RAT
RRM)
EXIT
START
Execute resource
allocation
Execute resource
allocation
Can target be met by
management functionality
(HLSM)
Abort radio resource allocation
request
Execute resource
allocation
Yes
Yes
Yes
No
No
No
FIGURE 4: Flowchart description of the UMTS spectrum management
framework
6. G Salami, R.Tafazolli
International Journal of Computer Networks, Volume (2): Issue (1) 52
2.2 System Model
Consider the following model, in which two operators share the spectrum. The traffic profile of the
two networks (Ta and Tb) is as described in Fig. 2. Two cases have been identified. In the first
case, whole carriers may be exchanged by the operator depending on their traffic and hence
carrier requirement. In the second case, the users from one operator may be migrated to another
operator’s network based on pre-establishment agreement between the two operators. The
second is more likely in the case of Wideband Code Division Multiple Access (WCDMA) system
where the release of whole carrier is highly unlikely due to the wideband nature of CDMA.
In the model, the operators are assumed to have the cell grid deployment shown in Fig. 5 with
wraparound mobility to maintain constant user density. It is an important assumption that both
operators cover the same geographical area and the cell radius is 1km. The displaced cell model
means the impact of ACI needs to be taken into account. ACI primarily due to imperfection in
transmit and receive filter characteristics, is modeled as a reduction in the network capacity [25].
Soft handover gain is modeled according to [26] [27]. Perfect power control is also assumed.
Two traffic models are used in the simulation. The first is the uniform traffic case in which the
average cell load in all the different cells is approximately the same. In the non-uniform traffic
case, three hotspots cells with 10% higher call volume are included. According to [28], the same
cell interference (Isc) is given in (1) for mobiles in the same cell as;
rsc S)1M(I α (1)
Where S is the power of each mobile at the receiver, αr is the average reverse link voice activity
factor. The other cell interference (Ioc) is given in (2) as
ξα )SM(I roc (2)
Where ζ is the reuse fraction given by;
FIGURE 5: Cell deployment for two operators covering same
geographic area with displaced BS
7. G Salami, R.Tafazolli
International Journal of Computer Networks, Volume (2): Issue (1) 53
fractionreuse
powerreceivedcellsametotal
powerreceivedcellothertotal
ξ
The UMTS capacity equation used in the simulation is given in [29-30] by (3)
i1
1
E
N
R
B1
1M
b
o
b
w
r
α
(3)
Where “i” is the ratio of other cell to own cell interference.
2.3 Algorithm Description
In the algorithm description, there is a primary and secondary operator. The primary operator
(PO) is defined as the operator which has instantaneous spare capacity to support the secondary
operator (SO) during a capacity crisis. The secondary operator suffers capacity problems and
requires additional resources from another network for a given period of time. It is important to
note that the process is dynamic in time (i.e op A and op B may interchangeably be PO or SO)
based on traffic demand. In FSA, the operators maintain their carrier allocations and no spectrum
sharing takes place. In Fig. 6, no further effort is made to admit dropped calls and the right hand
side of the flow chart is ignored.
In DSA, the operators are able to support their user requests on another network. Furthermore,
queuing is introduced to minimize inter-network signaling. The priority is to support the
connection request of the users on its own network initially. If the users are unable to find a free
channel, then the calls are queued for a short period of time (2 - 3 seconds) respectively. The
connection request times due to queuing introduces increased spectrum efficiency gain at the
expense of delays. This process termed “DSA with queuing” helps to minimize the inter-network
signaling overhead involved in the process. This is because the user is initially queued on its
home network before inter-network signaling occurs. A flow chart of the DSA algorithm is shown
in Fig. 6.
Can call be
successfully admitted
on own network
New call arrival
Call admission on
own network
Queue uncompleted
calls on own network
(mean waiting time=2,
3s)
Can call be
successfully admitted
on own network
Home network transfer
users to new network
Call supported on own
network
Can call be
successfully admitted
on new network
Call supported on new
network
Call supported on own
network
Call blocked on new
network
Yes
No No
Yes Yes
No
DSA with queuing
scheme
DSA without queuing
scheme
FIGURE 6: Flowchart of the FSA and DSA spectrum admission procedure
8. G Salami, R.Tafazolli
International Journal of Computer Networks, Volume (2): Issue (1) 54
3. Call Setup Analysis
The process of establishing a call involves a number of procedures before the resource is
assigned to the user equipment (UE). In this section the call setup involved in FSA and DSA is
analyzed. Three cases have been identified.
3.1 FSA or Non-shared mode
This refers to the mode when no spectrum sharing occurs. Hence, users are only admitted in their
home networks. In the FSA mode, the call setup phase includes the Radio Resource Connection
(RRC) establishment, security handshake, radio bearer setup, alerting, connect acknowledge,
etc. The recommended one way end to end delay for conversational voice service according to
[33] is less than 150ms and the limit should be no more than 400ms. All call requests are
assumed to be originated from the UE [31].
Neglecting practical constraints such as the actual radio channel condition, the estimate shown in
[31] assumes the best case scenario. However, it has been shown in [25] that the typical delay
budget is usually between 6-8 seconds under practical conditions. In [31], the UE is assumed to
be in the idle mode initially. The reason for the different UE states (idle and connected) as defined
in [25] is for terminal power efficiency and network resource maximization. The main components
introducing delays in the FSA call setup is the RRC connection establishment and the radio
bearer setup.
3.2 DSA Mode with shared RNC
In the shared Radio Network Controller (RNC) mode, the operators share the same RNC. An
agent in the RNC proactively monitors the base station loading of the two operators. In this case,
the delay budget will be similar to that described for FSA in [31]. Since the information is
contained in the network, capacity can be served directly to the users without additional delays.
3.3 DSA Mode without shared RNC
In the non-shared RNC mode, additional delay is incurred in granting resources on the foreign
network. It is an assumption that the Common Pilot Channel (CPICH) of both operators can be
decoded by the terminal. The paper [34] has presented the call flow procedure for FSA and DSA.
We further analyze the impact of queuing and call setup latency on the spectrum sharing gain in
this work.
In addition to the modes mentioned above based on the infrastructure, the connection requests
can be queued on the home network. This measure aims to reduce the connection signaling
overhead associated with inter-network transfers. For the FSA mode, two main methods are
identified. These are; the FSA with queuing, and FSA without queuing modes. In FSA with
queuing the calls are queued but not transferred to the foreign network. In the FSA without
queuing, calls are either blocked or dropped and no queuing is implemented.
Similarly for the DSA schemes, two modes are identified. These are; the DSA with queuing and
the DSA without queuing modes. In the DSA with queuing, the calls are queued for 2-3 seconds
respectively as shown in Fig. 7. After this period, the calls are transferred to the foreign network.
In the DSA without queuing scheme, the connection requests that cannot be completed on the
home network are transferred to the new operator without further queuing on the home network.
The main focus of this work is on the DSA schemes and hence simulation results presented in
section VI focus on the latter scenarios.
9. G Salami, R.Tafazolli
International Journal of Computer Networks, Volume (2): Issue (1) 55
4 Simulation Results
A simulation tool described in [32] has been developed to evaluate the performance of the DSA
algorithms. The main simulation parameters used in this work is shown in Table I. The call
arrivals are modeled using the Poisson distribution, while the call holding times are exponentially
distributed with a mean of 120 seconds.
Parameters Values
Service type Speech traffic
Data rate 12.2 Kbps
Call Duration Mean = 120 seconds ( Exponential )
Eb/No 7 dB
Adjacent Channel Interference 2 %
Soft handover Gain 3 dB
Cell radius 1 Km
Voice Activity Factor 0.67
UMTS carrier bandwidth 5 MHz
Chip rate 3.84 MCps
Simulation borders Wraparound mobility of MS at
simulation borders
Propagation Model Path loss model with 4th
order power
exponent
User distribution Uniform and Non-Uniform
(3 Hotspots )
Frequency re-use factor 1
Handover Based on geometric cell boundaries
Total Number of cells 12 ( with interference modeling )
Carrier distribution Primary ( 3 carriers ), secondary ( 3
carrier)
Cell layout Hexagonal with omni-directional antenna
Deployment
Connection queuing times 1 second, 2 seconds
Table I: Simulation Parameters
To evaluate the spectrum efficiency gain, the FSA scenario when no spectrum sharing takes
place is compared with the DSA scenario with and without queuing. The gain is measured in
terms of the capacity improvement at 98 % Satisfaction Ratio (SR). The SR is defined in (4). This
value is considered sufficient to give the desired level of Quality of Service (QoS) in an operator’s
network.
))P10(P(1SR DB (4)
PB is the call blocking probability and PD is the call dropping probability. The dropped calls are
given a higher weighting since there are less tolerable than blocked calls. The spectrum efficiency
gain (Δη) is defined in (5) as
%98FSA,
%FSA,98%DSA,98
Load
LoadLoad
Δ
η (5)
LoadDSA,98% is the Users/Cell/Hour for DSA at 98% Satisfaction ratio, LoadFSA,98% is the
Users/Cell/Hour for FSA at 98% Satisfaction ratio.
10. G Salami, R.Tafazolli
International Journal of Computer Networks, Volume (2): Issue (1) 56
4.1 Dynamic spectrum sharing system level protocol performance and analysis
The simulation results are presented in this section. Fig. 7 and Fig. 8 show the FSA and DSA
performance curves for network 1 and 2 respectively for the uniform traffic case. According to the
figure, the satisfaction ratio decreases as the traffic offered (Mobile Subscribers/Cell/Hour)
increases. Similarly, the results show that the DSA without queuing provides a least spectrum
efficiency gain compared to the other two techniques. This is due to the fact that in the DSA
scheme without queuing, no further measures are taken to account the call if the operator is
unable to accommodate the call it is either blocked or dropped.
Similarly, the results show that queuing improves the gain at low and medium load (offered
traffic). It also shows that queuing is not effective at high load. This is because the probability of
both operators being able to accommodate more users on their network during heavy traffic
period is very low. Furthermore, the performance of DSA with 3 seconds queuing is slightly better
than DSA with 2 seconds because further delays on home network results increases the
probability of a service connection at low to medium load. In all the cases investigated, the call
setup delay is transparent to the end user. The gain for the three schemes is 4.6 %, 4.3 % and
4.2 % respectively at 98 % satisfaction ratio on network 1. Similarly, the spectrum efficiency gain
on network 2 is 4.1 %, 4.0 %, 3.9 %. These figures are obtained by substituting the values on the
horizontal axis of Fig. 7 and Fig. 8 into (9).
FIGURE 7: Performance comparison between FSA and DSA with
and without queuing for network operator 1 (Uniform traffic).
11. G Salami, R.Tafazolli
International Journal of Computer Networks, Volume (2): Issue (1) 57
Fig. 9 and Fig. 10 show the performance for FSA and DSA with and without queuing for the three
schemes investigated in the non-uniform traffic case. Three (3) hotspots which represent areas of
temporarily high traffic have been included in the simulation area. The trend in performance for
the three schemes is similar to that discussed previously. However, the main difference is that the
carriers in the non-uniform traffic case approaches saturation faster due to higher call volumes. It
is important to note that the spectrum efficiency gain for all the three schemes is similar at 98%
satisfaction ratio regardless of queuing. This fact is more visible at high load due to congestion. It
is also observed that the performance of the DSA algorithm approaches that of FSA at high load
due to the inclusion of the hotspot.
FIGURE 8: Performance comparison between FSA and DSA with
and without queuing for network operator 2 (Uniform traffic)
FIGURE 9: Performance comparison between FSA and DSA with and
without queuing for network operator 1 (Non-Uniform traffic)
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International Journal of Computer Networks, Volume (2): Issue (1) 58
Based on the graphs plotted above for both scenarios, the spectrum efficiency gain for the non-
uniform traffic scenario for the three DSA schemes for network 1 and 2 is 2.2 % and 2.0 %
indicating a reduction in gain compared to first scenario. There is also no significant benefit due to
queuing at 98 % SR.
4.2 Call setup messages and latency
The detailed description of the call setup sequence is presented in [34]. Here we provide the
simulation results in terms of total call setup messages for the two operators at a particular
satisfaction ratio. According to Fig. 11 and Fig. 12, the total setup message for the non-uniform
traffic (Fig. 12) case is generally higher than Uniform case (Fig. 11). A high number of subscribers
results in a higher number of signaling messages. Similarly, it is shown that DSA results in a
higher number of signaling messages compared to FSA for all the 3 schemes considered.
It is observed that DSA without queuing has the higher signaling messages since users are
directly migrated to the foreign network without any attempt to support them on their home
network. The other two schemes minimize the inter-network signaling by trying to support the
calls on their home network. DSA with 2 seconds queuing performs better than DSA with 3
seconds queuing since it accommodates less subscribers compared to the latter.
Figure 10: Performance comparison between FSA and DSA with
and without queuing for network operator 2 (Non- Uniform traffic).
13. G Salami, R.Tafazolli
International Journal of Computer Networks, Volume (2): Issue (1) 59
Fig. 11a. Total call setup messages versus SR
for the DSA schemes (uniform traffic) network 1.
Fig. 11b. Total call setup messages versus SR
for the DSA schemes (uniform traffic) network 2.
Fig. 12a. Total call setup messages versus SR
for the DSA schemes (non-uniform traffic)
network 1.
Fig. 12b. Total call setup messages versus SR
for the DSA schemes (non-uniform traffic)
network 2.
To adequately serve users, it is necessary to avoid long call setup delays [25]. Connection
request delays should be transparent and imperceptible to the end user. The mean queuing times
of 2-3 seconds chosen in the work is considered adequate to reflect these issues. The main
implications are that operators will need to carefully weigh the trade-offs between not
accommodating a subscriber and hence loss of revenue, to queuing of subscriber for short
periods after which they can be served as soon as capacity becomes available. It is also
important to note that additional latency is introduced due to spectrum sharing, so that the
maximum tolerable delay need to be matched with the service requirements.
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International Journal of Computer Networks, Volume (2): Issue (1) 60
5 Conclusions and Future Work
This paper has presented a spectrum access framework for dynamic spectrum sharing between
operators using the UMTS network as a case study. Three schemes to address UMTS spectrum
sharing have been presented. The simulation results show that significant spectrum efficiency
gain can be obtained in the low and medium traffic regions for the uniform and non-uniform
cases. For the scenarios considered spectrum sharing gain above 4.0 % and 2.0 % was obtained
for the uniform and non-uniform traffic at 98 % satisfaction ratio. The DSS gains are primarily due
to the statistical multiplexing of call arrivals. The decrease in the gain in the latter scenario was
due to the significantly higher call volumes associated with hotspots. The results also show that
queuing does not significant improve the spectrum sharing gain under heavy traffic conditions.
The paper has also investigated the trade-off associated with spectrum sharing taking into
account the call setup signaling and delay. It is important to note that DSA with queuing schemes
provide a more practical approach to increase the gain while minimizing the inter-network
signaling overhead. Furthermore, it was shown that the non-uniform traffic scenario presents
challenges in terms of signaling for network operators in all the DSS cases. Future work will
address operator networks with heterogeneous services and packet level simulations to
determine if further gains are possible due to statistical multiplexing of packet transmission.
ACKNOWLEDGEMENT
This work has been supported, in part, by the European ICT Project QoSMOS.
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