In the next generation wireless networks, the growing demand for new wireless applications is accompanied with high expectations for better quality of service (QoS) fulfillment especially for multimedia applications. Furthermore, the coexistence of future unlicensed users with existing licensed users is becoming a challenging task in the next generation communication systems to overcome the underutilization of the spectrum. A QoS and interference aware resource allocation is thus of special interest in order to respond to the heterogeneous constraints of the next generation networks. In this work, we address the issue of resource allocation under heterogeneous constraints for unlicensed multiband ultra-wideband (UWB) systems in the context of Future Home Networks, i.e. the wireless personal area network (WPAN). The problem is first studied analytically using a heterogeneous constrained optimization problem formulation. After studying the characteristics of the optimal solution, we propose a low-complexity suboptimal algorithm based on a cross-layer approach that combines information provided by the PHY and MAC layers. While the PHY layer is responsible for providing the channel quality of the unlicensed UWB users as well as their interference power that they cause on licensed users, the MAC layer is responsible for classifying the unlicensed users using a two-class based approach that guarantees for multimedia services a high-priority level compared to other services. Combined in an efficient and simple way, the PHY and MAC information present the key elements of the aimed resource allocation. Simulation results demonstrate that the proposed scheme provides a good tradeoff between the QoS satisfaction of the unlicensed applications with hard QoS requirements and the limitation of the interference affecting the licensed users.
MULTI-CRITERIA HANDOVER DECISION FOR HETEROGENEOUS NETWORKS: CARRIER AGGREGAT...IJCNCJournal
Carrier aggregation and integration of heterogeneous networks allow the mobile user equipment to benefit from wider bandwidth and radio coverage of different access technologies. However, these technologies have increased handoff scenario probability through user equipment’s mobility, leading to high outage probability and low throughput. Handover is an important aspect of mobility management which allows users to migrate from one cell to another without losing connections. But no lone access technology meets the requirements of providing seamless communication without loss and delay. Therefore, high-quality service continuity and reliable user equipment access to network anywhere and at any time require the
design of an appropriate handover decision algorithm. In this paper, a multi-criteria based handover decision-making algorithm is proposed to evade loss of communication and provide better performance to the system. It adaptively makes handover decisions based on different decision criteria (load, availability of resources, and the handover scenario type) in addition to signal interference to noise ratio. The multicriteria handover decision making algorithm-based method chooses among the cells that satisfy the requirements for the handover. As compared to some existing handover decision algorithms, simulation result shows that this algorithm improves system performance in terms of handover failure by 93%, 72%,
and 58%; radio link failure reduction by 77%, 43%, and 22%; and handover ping–pong by 81%, 59%, and 36% over the conventional received signal strength, received wireless transmission line, and multiinfluence factor hand over decisions respectively.
Reducing handoff delay by adaptive thresholdijistjournal
In wireless networks data are sent and received with impressive speed and ease. Mobile WiMAX is a
broadband wireless solution that enables coverage of mobile and fixed broadband networks with flexible
network architecture. Devised as a truly broadband access solution, the WiMAX technology offers
promising features in terms of high bandwidth, extended coverage area and low cost. Despite having
many advantages, WiMAX faces major research issues like QoS based bandwidth allocation, Roaming,
Internetworking with other technologies, security and handoff. Handoff occurs when a mobile user goes
from one cell to another without interruption of ongoing session. Many approaches have been proposed
for reducing handoff delay. In this paper, we propose a new approach by which a critical area, an area
far away from serving base station but still inside the coverage of serving base station, is found. And then
overlapping area between serving base stations and neighboring base station are found and tabulated.
According to the size of overlapping area, different weights are assigned where handoff threshold is
changed adaptively to reduce handoff delay.
MULTI-HOP BANDWIDTH MANAGEMENT PROTOCOL FOR MOBILE AD HOC NETWORKSIJMIT JOURNAL
An admission control scheme should play the role of a coordinator for flows in a data communication network, to provide the guarantees as the medium is shared. The nodes of a wired network can monitor the medium to know the available bandwidth at any point of time. But, in wireless ad hoc networks, a node must consume the bandwidth of neighboring nodes, during a communication. Hence, the consumption of bandwidth by a flow and the availability of resources to any wireless node strictly depend upon the neighboring nodes within its transmission range. We present a scalable and efficient admission control scheme, Multi-hop Bandwidth Management Protocol (MBMP), to support the QoS requirements
in multi-hop ad hoc networks. We simulate several options to design MBMP and compare the performances of these options through mathematical analysis and simulation results, and compare its effectiveness with the existing admission control schemes through extensive simulations.
Downlink beamforming and admissin control for spectrum sharing cognitive radi...acijjournal
n this paper, to detect the moving objects between frames in compressed video and to obtain the bes
t
compression video
and the noiseless video. We describe a video in which frames by classifying
macroblocks (MB), and describe motion estimation (ME), motion vector field (MV) and motion
compensation (MC). we propose to classify Macroblocks of each video frame into different
classes and use
this class information to describe the frame content based on the motion vector. MB class informatio
n
video applications such as shot change detection, motion discontinuity detection, Outlier rejection
for
global motion estimation. To reduc
e the noise and to improve the clarity of the compressed video by using
contrast limited adaptive histogram equalization (CLAHE) Algorithm
Quality of Service in bandwidth adapted hybrid UMTS/WLAN interworking networkTELKOMNIKA JOURNAL
Integration of Universal Mobile Telecommunications System (UMTS) and Wireless Local Area Network (WLAN) result in ubiquitous connection for end users. In the integrated network, ensuring the quality of service to users and enhancing capacity of network are prominent issues. Bandwidth adaptation technique is one of the solutions to overcome these issues. Bandwidth adaptation based on per flow and per class schemes were proposed for loosely coupled interworking network. In this paper, hybrid coupled UMTS and WLAN interworking network is analyzed with bandwidth adaptation based on per flow and per class schemes and the performances have been compared. Simulation result shows that the proposed hybrid coupled interworking network with bandwidth adaptation based on per class scheme performs better with enhanced quality of service and network capacity.
Markovian Queueing Model for Throughput Maximization in D2D-Enabled Cellular ...IJECEIAES
Device-to-Device (D2D) communication has been considered a key enabling technol- ogy that can facilitate spectrum sharing in 4G and 5G cellular networks. In order to meet the high data rate demands of these new generation cellular networks, this paper considers the optimization of available spectrum resource through dynamic spectrum access. The utilization of continuous-time Markov chain (CTMC) model for efficient spectrum access in D2D-enabled cellular networks is investigated for the purpose of determining the impact of this model on the capacity improvement of cellular networks. The paper considers the use of CTMC model with both queueing and non-queueing cases called 13-Q CTMC and 6-NQ CTMC respectively with the aim of improving the overall capacity of the cellular network under a fairness constraint among all users. The proposed strategy consequently ensures that spectrum access for cellular and D2D users is optimally coordinated by designing optimal spectrum access probabilities. Numerical simulations are performed to observe the impact of the proposed Markovian queueing model on spectrum access and consequently on the capacity of D2D-enabled cellular networks. Results showed that the proposed 13-Q CTMC provide a more spectrumefficient sharing scheme, thereby enabling better network performances and larger capabilities to accommodate more users.
MULTI-CRITERIA HANDOVER DECISION FOR HETEROGENEOUS NETWORKS: CARRIER AGGREGAT...IJCNCJournal
Carrier aggregation and integration of heterogeneous networks allow the mobile user equipment to benefit from wider bandwidth and radio coverage of different access technologies. However, these technologies have increased handoff scenario probability through user equipment’s mobility, leading to high outage probability and low throughput. Handover is an important aspect of mobility management which allows users to migrate from one cell to another without losing connections. But no lone access technology meets the requirements of providing seamless communication without loss and delay. Therefore, high-quality service continuity and reliable user equipment access to network anywhere and at any time require the
design of an appropriate handover decision algorithm. In this paper, a multi-criteria based handover decision-making algorithm is proposed to evade loss of communication and provide better performance to the system. It adaptively makes handover decisions based on different decision criteria (load, availability of resources, and the handover scenario type) in addition to signal interference to noise ratio. The multicriteria handover decision making algorithm-based method chooses among the cells that satisfy the requirements for the handover. As compared to some existing handover decision algorithms, simulation result shows that this algorithm improves system performance in terms of handover failure by 93%, 72%,
and 58%; radio link failure reduction by 77%, 43%, and 22%; and handover ping–pong by 81%, 59%, and 36% over the conventional received signal strength, received wireless transmission line, and multiinfluence factor hand over decisions respectively.
Reducing handoff delay by adaptive thresholdijistjournal
In wireless networks data are sent and received with impressive speed and ease. Mobile WiMAX is a
broadband wireless solution that enables coverage of mobile and fixed broadband networks with flexible
network architecture. Devised as a truly broadband access solution, the WiMAX technology offers
promising features in terms of high bandwidth, extended coverage area and low cost. Despite having
many advantages, WiMAX faces major research issues like QoS based bandwidth allocation, Roaming,
Internetworking with other technologies, security and handoff. Handoff occurs when a mobile user goes
from one cell to another without interruption of ongoing session. Many approaches have been proposed
for reducing handoff delay. In this paper, we propose a new approach by which a critical area, an area
far away from serving base station but still inside the coverage of serving base station, is found. And then
overlapping area between serving base stations and neighboring base station are found and tabulated.
According to the size of overlapping area, different weights are assigned where handoff threshold is
changed adaptively to reduce handoff delay.
MULTI-HOP BANDWIDTH MANAGEMENT PROTOCOL FOR MOBILE AD HOC NETWORKSIJMIT JOURNAL
An admission control scheme should play the role of a coordinator for flows in a data communication network, to provide the guarantees as the medium is shared. The nodes of a wired network can monitor the medium to know the available bandwidth at any point of time. But, in wireless ad hoc networks, a node must consume the bandwidth of neighboring nodes, during a communication. Hence, the consumption of bandwidth by a flow and the availability of resources to any wireless node strictly depend upon the neighboring nodes within its transmission range. We present a scalable and efficient admission control scheme, Multi-hop Bandwidth Management Protocol (MBMP), to support the QoS requirements
in multi-hop ad hoc networks. We simulate several options to design MBMP and compare the performances of these options through mathematical analysis and simulation results, and compare its effectiveness with the existing admission control schemes through extensive simulations.
Downlink beamforming and admissin control for spectrum sharing cognitive radi...acijjournal
n this paper, to detect the moving objects between frames in compressed video and to obtain the bes
t
compression video
and the noiseless video. We describe a video in which frames by classifying
macroblocks (MB), and describe motion estimation (ME), motion vector field (MV) and motion
compensation (MC). we propose to classify Macroblocks of each video frame into different
classes and use
this class information to describe the frame content based on the motion vector. MB class informatio
n
video applications such as shot change detection, motion discontinuity detection, Outlier rejection
for
global motion estimation. To reduc
e the noise and to improve the clarity of the compressed video by using
contrast limited adaptive histogram equalization (CLAHE) Algorithm
Quality of Service in bandwidth adapted hybrid UMTS/WLAN interworking networkTELKOMNIKA JOURNAL
Integration of Universal Mobile Telecommunications System (UMTS) and Wireless Local Area Network (WLAN) result in ubiquitous connection for end users. In the integrated network, ensuring the quality of service to users and enhancing capacity of network are prominent issues. Bandwidth adaptation technique is one of the solutions to overcome these issues. Bandwidth adaptation based on per flow and per class schemes were proposed for loosely coupled interworking network. In this paper, hybrid coupled UMTS and WLAN interworking network is analyzed with bandwidth adaptation based on per flow and per class schemes and the performances have been compared. Simulation result shows that the proposed hybrid coupled interworking network with bandwidth adaptation based on per class scheme performs better with enhanced quality of service and network capacity.
Markovian Queueing Model for Throughput Maximization in D2D-Enabled Cellular ...IJECEIAES
Device-to-Device (D2D) communication has been considered a key enabling technol- ogy that can facilitate spectrum sharing in 4G and 5G cellular networks. In order to meet the high data rate demands of these new generation cellular networks, this paper considers the optimization of available spectrum resource through dynamic spectrum access. The utilization of continuous-time Markov chain (CTMC) model for efficient spectrum access in D2D-enabled cellular networks is investigated for the purpose of determining the impact of this model on the capacity improvement of cellular networks. The paper considers the use of CTMC model with both queueing and non-queueing cases called 13-Q CTMC and 6-NQ CTMC respectively with the aim of improving the overall capacity of the cellular network under a fairness constraint among all users. The proposed strategy consequently ensures that spectrum access for cellular and D2D users is optimally coordinated by designing optimal spectrum access probabilities. Numerical simulations are performed to observe the impact of the proposed Markovian queueing model on spectrum access and consequently on the capacity of D2D-enabled cellular networks. Results showed that the proposed 13-Q CTMC provide a more spectrumefficient sharing scheme, thereby enabling better network performances and larger capabilities to accommodate more users.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
Design and implementation of new routingIJCNCJournal
Energy consumption is a key element in the Wireless Sensor Networks (WSNs) design. Indeed, sensor nodes are really constrained by energy supply. Hence, how to improve the network lifetime is a crucial and challenging task. Several techniques are available at different levels of the OSI model to maximize the WSN lifetime and especially at the network layer which uses routing strategies to maintain the routes in the network and guarantee reliable communication. In this paper we intend to propose a new protocol called
Combined Energy and Distance Metrics Dynamic Routing Protocol (CEDM-DR). Our new approach considers not only the distance between wireless sensors but also the energy of node acting as a router in order to find the optimal path and achieve a dynamic and adaptive routing.
The performance metrics exploited for the evaluation of our protocol are average energy consumed, network lifetime and packets lost. By comparing our proposed routing strategy to protocol widely used in WSN namely Ad hoc On demand Distance Vector(AODV), simulation results show that CEDM-DR strategy might effectively balance the sensor power consumption and permits accordingly to enhance the network
lifetime. As well, this new protocol yields a noticeable energy saving compared to its counterpart.
Performance Analysis of Energy Optimized LTE-V2X Networks for Delay Sensitive...IJCNCJournal
Energy-efficient relaying technology in multi-hop data transmission can help the challenges faced in cellular Vehicle-to-Everything (cellular-V2X) communication. However, due to high demand of emergency service requirements of the systems such as Public Protection and Disaster Relief (PPDR), National Security and Public Safety (NSPS), Intelligent Transport System (ITS) etc., least energy consumed user equipment (UEs)/Vehicular-UEs are required which can either run real-time applications or relay the application data. To support these scenarios, we present a high way based system model in rural area and enhance its scope for applying single-hop direct, relay assisted multi-hop cellular-V2X and Store-CarryForward (SCF) modes of uplink data transmission. We compare the performance of three modes of transmissions in terms of overall energy consumption and overall transmission delay with specific delay constraints of VoIP and video applications. With the varying cell radius and irrespective type of applications, our numerical results, validated with ns-3 show that, least energy is always consumed in SCF mode due to its inherent property but applications suffer a lot due to high delay incurred whereas singlehop direct mode shows the reverse. When compared with cellular-V2X mode, overall transmission delay for single-hop direct mode is acceptable within cell radius 600m but beyond that, relay assisted multi-hop cellular-V2X mode always outperforms (with low latency and moderate energy consumption).
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.
Mimo noma design for small packet transmission in the internet of thingsredpel dot com
Mimo noma design for small packet transmission in the internet of things
for more ieee paper / full abstract / implementation , just visit www.redpel.com
An optimum dynamic priority-based call admission control scheme for universal...TELKOMNIKA JOURNAL
The dynamism associated with quality of service (QoS) requirement for traffic emanating from smarter end users devices founded on the internet of things (IoTs) drive, places a huge demand on modern telecommunication infrastructure. Most telecom networks, currently utilize robust call admission control (CAC) policies to ameliorate this challenge. However, the need for smarter CAC has becomes imperative owing to the sensitivity of traffic currently being supported. In this work, we developed a prioritized CAC algorithm for third Generation (3G) wireless cellular network. Based on the dynamic priority CAC (DP-CAC) model, we proposed an optimal dynamic priority CAC (ODP-CAC) scheme for Universal Mobile Telecommunication System (UMTS). We then carried out simulation under heavy traffic load while also exploiting renegotiation among different call traffic classes. Also, we introduced queuing techniques to enhance the new calls success probability while still maintaining a good handoff failure across the network. Results show that ODP-CAC provides an improved performance with regards to the probability of call drop for new calls, network load utilization and grade of service with average percentage value of 15.7%, 5.4% and 0.35% respectively.
A Cooperative Approach to Extend Cellular Coverage via D2D Architecture based...IJCNCJournal
The access part of all cellular network’s generation suffers from common concerns related to dead spots (zones that are not covered by the network) and hot spots (zones where the number of users is higher compared to network resources). During the last decade, lots of research proposals have tried to overcome cellular problems through multi-hop D2D architecture, which is a new paradigm allowing the direct communication between devices in cellular network to enhance network performances and improve user QoS. In this paper, we propose a multi-hop D2D architecture based on the OLSR protocol to extend cellular coverage. Cell-OLSR, which is the proposed adaptation of OLSR for our architecture, allows the exchange of cellular parameters between nodes to choose the best proxy device to forward data to the cellular base station (BS).
Performance Analysis of Wireless Networks With MDQOSIJERA Editor
In Wireless/Mobile networks various kinds of encoding schemes were used for transmission of data over a bandwidth. The desired quality and generated traffic varies with the requirement with this bandwidth. A generic video telephony may require more than 40 kbps whereas a low motion video telephony may require about 25 kbps for data transmission. From the designing point of view these requirements demands for an alternative resource planning, especially for bandwidth allocation in wireless networks. In wireless network where bandwidth is a scare resource, the system may need to block incoming user if all of the bandwidth has been used to provide highest quality of service to existing users. However this bandwidth resource planning may be unacceptable for larger application. A degradable approach to multiple users can be made on bandwidth allocation to reduce the blocking probability without degrading the quality of service to existing users.
This work aims towards a realization of a wireless/mobile network using W-CDMA multi access technique supporting multilevel quality of services. The bandwidth allocation to multiple users is adjusted dynamically according to the required network condition so as to increase bandwidth utilization. The work analyze the performance deriving the degradation period ratio, mean degradation time and degradation state for the implemented wireless network.The proposed work is aim to implement on Matlab tool for its functional verification considering various mobility patterns
Wimax technology has reshaped the framework of broadband wireless internet
service. It provides the internet service to unconnected or detached areas such as east South
Africa, rural areas of America and Asia region. Full duplex helpers employed with one of
the relay stations selection and indexing method that is Randomized Distributed Space Time
are used to expand the coverage area of primary Wimax station. The basic problem was
identified at cell edge due to weather conditions (rain, fog), insertion of destruction because
of multiple paths in the same communication channel and due to interference created by
other users in that communication. It is impractical task for the receiver station to decode
the transmitted signal successfully at the cell edges, which increases the high packet loss and
retransmissions. But Wimax is a outstanding technology which is used for improving the
quality of internet service and also it offers various services like Voice over Internet
Protocol, Video conferencing and Multimedia broadcast etc where a little delay in packet
transmission can cause a big loss in the communication. Even setup and initialization of
another Wimax station nearer to each other is not a good alternate, where any mobile
station can easily handover to another base station if it gets a strong signal from other one.
But in rural areas, for few numbers of customers, installation of base station nearer to each
other is costlier task. In this review article, we present a scheme using R-DSTC technique to
choose and select helpers (relay nodes) randomly to expand the coverage area and help to
mobile station as a helper to provide secure communication with base station. In this work,
we use full duplex helpers for better utilization of bandwidth.
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 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
LINK-LEVEL PERFORMANCE EVALUATION OF RELAY-BASED WIMAX NETWORKijwmn
Relay technology promises appreciable network throughput and coverage enhancement which is required
for high speed wireless cellular systems to function to their optimum. This paper is focused on analysing
the link performance of a relay-based WiMAX network under varying conditions. Comparison is made
between relay and direct link communication in terms of BER (Bit Error Rate), spectral efficiency and
capacity. Effect of multipath fading and user speed on performance are investigated as well. The entire
study involves a hypothetical view as well as MATLAB simulations to predict the benefit of relay
deployment. This is aimed at solving pertinent issues such as coverage holes and cell edge problems which
are associated with traditional non-relay based cellular networks.
A STUDY ON QUANTITATIVE PARAMETERS OF SPECTRUM HANDOFF IN COGNITIVE RADIO NET...ijwmn
The innovation of wireless technologies requires dynamic allocation of spectrum band in an efficient
manner. This has been achieved by Cognitive Radio (CR) networks which allow unlicensed users to make
use of free licensed spectrum, when the licensed users are kept away from that spectrum. The cognitive
radio makes decision, switching from primary user to secondary user and vice-versa, based on its built-in
interference engine. It allows secondary users to makes use of a channel based on its availability i.e. on the
absence of the primary user and they should vacate the channel once the primary user re-enters and
continue their communication on another available channel and this process in the cognitive radio is
known as spectrum mobility. The main objective of spectrum mobility is that, there is no interruption
caused due to the channel occupied by secondary users and maintains a good quality of service. In order to
achieve better spectrum mobility, it is mandatory to choose an effective spectrum handoff strategy with the
capability of predicting spectrum mobility. The handoff strategy with its parameters and its impact is an
important concept in spectrum mobility but fairly explored. In this paper an empirical study on quantitative
parameters involved in spectrum mobility prediction are discussed in detail. These parameters are studied
extensively because they play a vital role in the spectrum handoff process moreover the impact of these
parameters in various handoff methods can be used to predict the effectiveness of the system.
A small vessel detection using a co-located multi-frequency FMCW MIMO radar IJECEIAES
Small vessels detection is a known issue due to its low radar cross section (RCS). An existing shore-based vessel tracking radar is for long-distance commercial vessels detection. Meanwhile, a vessel-mounted radar system known for its reliability has a limitation due to its single radar coverage. The paper presented a co-located frequency modulated continuous waveform (FMCW) maritime radar for small vessel detection utilising a multiple-input multiple-output (MIMO) configuration. The radar behaviour is numerically simulated for detecting a Swerling 1 target which resembles small maritime’s vessels. The simulated MIMO configuration comprised two transmitting and receiving nodes. The proposal is to utilize a multi-frequency FMCW MIMO configuration in a maritime environment by applying the spectrum averaging (SA) to fuse MIMO received signals for range and velocity estimation. The analysis was summarised and displayed in terms of estimation error performance, probability of error and average error. The simulation outcomes an improvement of 2.2 dB for a static target, and 0.1 dB for a moving target, in resulting the 20% probability of range error with the MIMO setup. A moving vessel's effect was observed to degrade the range error estimation performance between 0.6 to 2.7 dB. Meanwhile, the proposed method was proven to improve the 20% probability of velocity error by 1.75 dB. The impact of multi-frequency MIMO was also observed to produce better average error performance.
Downlink beamforming and admissin control for spectrum sharing cognitive radi...acijjournal
We investigate the
problem of multiuser downlink beam
-
forming and admission control considering a
scenario where licensed, or primary, users and cognitive radios, or secondary users, are transmittin
g
concurrently over the same band. The primary users share a common receiver
and the interference on this
receiver from secondary users should be strictly limited to a certain level. Each secondary link is
assumed
to have a minimum quality of service (QoS) requirement that should be satisfied together with the
interference limit co
nstraint, otherwise the secondary link is not admitted. Under those constraints,
downlink beam
-
forming and admission control for secondary users are investigated for two main
optimization objectives. First, we maximize the number of admitted secondary link
s. Second, we maximize
the sum throughput of the admitted secondary links. our main design objective is to minimize the tra
nsmit
power of the SU
-
transmitter while simultaneously targeting a lower
-
bound on the received signal
-
to
-
interference
-
plus
-
noise
-
rati
o(SINR) for the SU’s and imposing on upper limit on the interference power(IP)
at the PUs.
Adaptive Bandwidth Management Model for Wireless Mobile Ad-hoc NetworkIJCNCJournal
The quality of service (QoS) component in a mobile ad-hoc network has an active role in the current network scenario. In a dynamic mobile ad hoc network, ensuring optimum QoS with a scarce network resource is a significant challenge. To achieve QoS, it is essential to adopt some effective and efficient mechanisms. We have proposed an adaptive bandwidth manager model (ABMM) which uses a bandwidthsharing concept along with the flexible bandwidth reservation algorithm (FBRA) for an effective, quick and authentic data transfer. During real-time data transfer, to make communication effective, we make use of bandwidth-sharing network design problems and the concept of reserving bandwidth in high-performance networks. In our proposed model we are concentrating on the maximum utilization of resources, and using the scheduling concept to provide the minimum required bandwidth guarantee to QoS flows. Our goal is to reduce the delay in data transfer and enhance the throughput while properly utilizing the system resources. Our simulation result also shows that our model improves the network performance.
ADAPTIVE BANDWIDTH MANAGEMENT MODEL FOR WIRELESS MOBILE AD-HOC NETWORKIJCNCJournal
The quality of service (QoS) component in a mobile ad-hoc network has an active role in the current
network scenario. In a dynamic mobile ad hoc network, ensuring optimum QoS with a scarce network
resource is a significant challenge. To achieve QoS, it is essential to adopt some effective and efficient
mechanisms. We have proposed an adaptive bandwidth manager model (ABMM) which uses a bandwidthsharing concept along with the flexible bandwidth reservation algorithm (FBRA) for an effective, quick and
authentic data transfer. During real-time data transfer, to make communication effective, we make use of
bandwidth-sharing network design problems and the concept of reserving bandwidth in high-performance
networks. In our proposed model we are concentrating on the maximum utilization of resources, and using
the scheduling concept to provide the minimum required bandwidth guarantee to QoS flows. Our goal is to
reduce the delay in data transfer and enhance the throughput while properly utilizing the system resources.
Our simulation result also shows that our model improves the network performance.
Dynamic resource allocation for opportunistic software-defined IoT networks: s...IJECEIAES
Several wireless technologies have recently emerged to enable efficient and scalable Internet-of-Things (IoT) networking. Cognitive radio (CR) technology, enabled by software-defined radios, is considered one of the main IoT-enabling technologies that can provide opportunistic wireless access to a large number of connected IoT devices. An important challenge in this domain is how to dynamically enable IoT transmissions while achieving efficient spectrum usage with a minimum total power consumption under interference and traffic demand uncertainty. Toward this end, we propose a dynamic bandwidth/channel/power allocation algorithm that aims at maximizing the overall network’s throughput while selecting the set of power resulting in the minimum total transmission power. This problem can be formulated as a two-stage binary linear stochastic programming. Because the interference over different channels is a continuous random variable and noting that the interference statistics are highly correlated, a suboptimal sampling solution is proposed. Our proposed algorithm is an adaptive algorithm that is to be periodically conducted over time to consider the changes of the channel and interference conditions. Numerical results indicate that our proposed algorithm significantly increases the number of simultaneous IoT transmissions compared to a typical algorithm, and hence, the achieved throughput is improved.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
Design and implementation of new routingIJCNCJournal
Energy consumption is a key element in the Wireless Sensor Networks (WSNs) design. Indeed, sensor nodes are really constrained by energy supply. Hence, how to improve the network lifetime is a crucial and challenging task. Several techniques are available at different levels of the OSI model to maximize the WSN lifetime and especially at the network layer which uses routing strategies to maintain the routes in the network and guarantee reliable communication. In this paper we intend to propose a new protocol called
Combined Energy and Distance Metrics Dynamic Routing Protocol (CEDM-DR). Our new approach considers not only the distance between wireless sensors but also the energy of node acting as a router in order to find the optimal path and achieve a dynamic and adaptive routing.
The performance metrics exploited for the evaluation of our protocol are average energy consumed, network lifetime and packets lost. By comparing our proposed routing strategy to protocol widely used in WSN namely Ad hoc On demand Distance Vector(AODV), simulation results show that CEDM-DR strategy might effectively balance the sensor power consumption and permits accordingly to enhance the network
lifetime. As well, this new protocol yields a noticeable energy saving compared to its counterpart.
Performance Analysis of Energy Optimized LTE-V2X Networks for Delay Sensitive...IJCNCJournal
Energy-efficient relaying technology in multi-hop data transmission can help the challenges faced in cellular Vehicle-to-Everything (cellular-V2X) communication. However, due to high demand of emergency service requirements of the systems such as Public Protection and Disaster Relief (PPDR), National Security and Public Safety (NSPS), Intelligent Transport System (ITS) etc., least energy consumed user equipment (UEs)/Vehicular-UEs are required which can either run real-time applications or relay the application data. To support these scenarios, we present a high way based system model in rural area and enhance its scope for applying single-hop direct, relay assisted multi-hop cellular-V2X and Store-CarryForward (SCF) modes of uplink data transmission. We compare the performance of three modes of transmissions in terms of overall energy consumption and overall transmission delay with specific delay constraints of VoIP and video applications. With the varying cell radius and irrespective type of applications, our numerical results, validated with ns-3 show that, least energy is always consumed in SCF mode due to its inherent property but applications suffer a lot due to high delay incurred whereas singlehop direct mode shows the reverse. When compared with cellular-V2X mode, overall transmission delay for single-hop direct mode is acceptable within cell radius 600m but beyond that, relay assisted multi-hop cellular-V2X mode always outperforms (with low latency and moderate energy consumption).
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.
Mimo noma design for small packet transmission in the internet of thingsredpel dot com
Mimo noma design for small packet transmission in the internet of things
for more ieee paper / full abstract / implementation , just visit www.redpel.com
An optimum dynamic priority-based call admission control scheme for universal...TELKOMNIKA JOURNAL
The dynamism associated with quality of service (QoS) requirement for traffic emanating from smarter end users devices founded on the internet of things (IoTs) drive, places a huge demand on modern telecommunication infrastructure. Most telecom networks, currently utilize robust call admission control (CAC) policies to ameliorate this challenge. However, the need for smarter CAC has becomes imperative owing to the sensitivity of traffic currently being supported. In this work, we developed a prioritized CAC algorithm for third Generation (3G) wireless cellular network. Based on the dynamic priority CAC (DP-CAC) model, we proposed an optimal dynamic priority CAC (ODP-CAC) scheme for Universal Mobile Telecommunication System (UMTS). We then carried out simulation under heavy traffic load while also exploiting renegotiation among different call traffic classes. Also, we introduced queuing techniques to enhance the new calls success probability while still maintaining a good handoff failure across the network. Results show that ODP-CAC provides an improved performance with regards to the probability of call drop for new calls, network load utilization and grade of service with average percentage value of 15.7%, 5.4% and 0.35% respectively.
A Cooperative Approach to Extend Cellular Coverage via D2D Architecture based...IJCNCJournal
The access part of all cellular network’s generation suffers from common concerns related to dead spots (zones that are not covered by the network) and hot spots (zones where the number of users is higher compared to network resources). During the last decade, lots of research proposals have tried to overcome cellular problems through multi-hop D2D architecture, which is a new paradigm allowing the direct communication between devices in cellular network to enhance network performances and improve user QoS. In this paper, we propose a multi-hop D2D architecture based on the OLSR protocol to extend cellular coverage. Cell-OLSR, which is the proposed adaptation of OLSR for our architecture, allows the exchange of cellular parameters between nodes to choose the best proxy device to forward data to the cellular base station (BS).
Performance Analysis of Wireless Networks With MDQOSIJERA Editor
In Wireless/Mobile networks various kinds of encoding schemes were used for transmission of data over a bandwidth. The desired quality and generated traffic varies with the requirement with this bandwidth. A generic video telephony may require more than 40 kbps whereas a low motion video telephony may require about 25 kbps for data transmission. From the designing point of view these requirements demands for an alternative resource planning, especially for bandwidth allocation in wireless networks. In wireless network where bandwidth is a scare resource, the system may need to block incoming user if all of the bandwidth has been used to provide highest quality of service to existing users. However this bandwidth resource planning may be unacceptable for larger application. A degradable approach to multiple users can be made on bandwidth allocation to reduce the blocking probability without degrading the quality of service to existing users.
This work aims towards a realization of a wireless/mobile network using W-CDMA multi access technique supporting multilevel quality of services. The bandwidth allocation to multiple users is adjusted dynamically according to the required network condition so as to increase bandwidth utilization. The work analyze the performance deriving the degradation period ratio, mean degradation time and degradation state for the implemented wireless network.The proposed work is aim to implement on Matlab tool for its functional verification considering various mobility patterns
Wimax technology has reshaped the framework of broadband wireless internet
service. It provides the internet service to unconnected or detached areas such as east South
Africa, rural areas of America and Asia region. Full duplex helpers employed with one of
the relay stations selection and indexing method that is Randomized Distributed Space Time
are used to expand the coverage area of primary Wimax station. The basic problem was
identified at cell edge due to weather conditions (rain, fog), insertion of destruction because
of multiple paths in the same communication channel and due to interference created by
other users in that communication. It is impractical task for the receiver station to decode
the transmitted signal successfully at the cell edges, which increases the high packet loss and
retransmissions. But Wimax is a outstanding technology which is used for improving the
quality of internet service and also it offers various services like Voice over Internet
Protocol, Video conferencing and Multimedia broadcast etc where a little delay in packet
transmission can cause a big loss in the communication. Even setup and initialization of
another Wimax station nearer to each other is not a good alternate, where any mobile
station can easily handover to another base station if it gets a strong signal from other one.
But in rural areas, for few numbers of customers, installation of base station nearer to each
other is costlier task. In this review article, we present a scheme using R-DSTC technique to
choose and select helpers (relay nodes) randomly to expand the coverage area and help to
mobile station as a helper to provide secure communication with base station. In this work,
we use full duplex helpers for better utilization of bandwidth.
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 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
LINK-LEVEL PERFORMANCE EVALUATION OF RELAY-BASED WIMAX NETWORKijwmn
Relay technology promises appreciable network throughput and coverage enhancement which is required
for high speed wireless cellular systems to function to their optimum. This paper is focused on analysing
the link performance of a relay-based WiMAX network under varying conditions. Comparison is made
between relay and direct link communication in terms of BER (Bit Error Rate), spectral efficiency and
capacity. Effect of multipath fading and user speed on performance are investigated as well. The entire
study involves a hypothetical view as well as MATLAB simulations to predict the benefit of relay
deployment. This is aimed at solving pertinent issues such as coverage holes and cell edge problems which
are associated with traditional non-relay based cellular networks.
A STUDY ON QUANTITATIVE PARAMETERS OF SPECTRUM HANDOFF IN COGNITIVE RADIO NET...ijwmn
The innovation of wireless technologies requires dynamic allocation of spectrum band in an efficient
manner. This has been achieved by Cognitive Radio (CR) networks which allow unlicensed users to make
use of free licensed spectrum, when the licensed users are kept away from that spectrum. The cognitive
radio makes decision, switching from primary user to secondary user and vice-versa, based on its built-in
interference engine. It allows secondary users to makes use of a channel based on its availability i.e. on the
absence of the primary user and they should vacate the channel once the primary user re-enters and
continue their communication on another available channel and this process in the cognitive radio is
known as spectrum mobility. The main objective of spectrum mobility is that, there is no interruption
caused due to the channel occupied by secondary users and maintains a good quality of service. In order to
achieve better spectrum mobility, it is mandatory to choose an effective spectrum handoff strategy with the
capability of predicting spectrum mobility. The handoff strategy with its parameters and its impact is an
important concept in spectrum mobility but fairly explored. In this paper an empirical study on quantitative
parameters involved in spectrum mobility prediction are discussed in detail. These parameters are studied
extensively because they play a vital role in the spectrum handoff process moreover the impact of these
parameters in various handoff methods can be used to predict the effectiveness of the system.
A small vessel detection using a co-located multi-frequency FMCW MIMO radar IJECEIAES
Small vessels detection is a known issue due to its low radar cross section (RCS). An existing shore-based vessel tracking radar is for long-distance commercial vessels detection. Meanwhile, a vessel-mounted radar system known for its reliability has a limitation due to its single radar coverage. The paper presented a co-located frequency modulated continuous waveform (FMCW) maritime radar for small vessel detection utilising a multiple-input multiple-output (MIMO) configuration. The radar behaviour is numerically simulated for detecting a Swerling 1 target which resembles small maritime’s vessels. The simulated MIMO configuration comprised two transmitting and receiving nodes. The proposal is to utilize a multi-frequency FMCW MIMO configuration in a maritime environment by applying the spectrum averaging (SA) to fuse MIMO received signals for range and velocity estimation. The analysis was summarised and displayed in terms of estimation error performance, probability of error and average error. The simulation outcomes an improvement of 2.2 dB for a static target, and 0.1 dB for a moving target, in resulting the 20% probability of range error with the MIMO setup. A moving vessel's effect was observed to degrade the range error estimation performance between 0.6 to 2.7 dB. Meanwhile, the proposed method was proven to improve the 20% probability of velocity error by 1.75 dB. The impact of multi-frequency MIMO was also observed to produce better average error performance.
Downlink beamforming and admissin control for spectrum sharing cognitive radi...acijjournal
We investigate the
problem of multiuser downlink beam
-
forming and admission control considering a
scenario where licensed, or primary, users and cognitive radios, or secondary users, are transmittin
g
concurrently over the same band. The primary users share a common receiver
and the interference on this
receiver from secondary users should be strictly limited to a certain level. Each secondary link is
assumed
to have a minimum quality of service (QoS) requirement that should be satisfied together with the
interference limit co
nstraint, otherwise the secondary link is not admitted. Under those constraints,
downlink beam
-
forming and admission control for secondary users are investigated for two main
optimization objectives. First, we maximize the number of admitted secondary link
s. Second, we maximize
the sum throughput of the admitted secondary links. our main design objective is to minimize the tra
nsmit
power of the SU
-
transmitter while simultaneously targeting a lower
-
bound on the received signal
-
to
-
interference
-
plus
-
noise
-
rati
o(SINR) for the SU’s and imposing on upper limit on the interference power(IP)
at the PUs.
Adaptive Bandwidth Management Model for Wireless Mobile Ad-hoc NetworkIJCNCJournal
The quality of service (QoS) component in a mobile ad-hoc network has an active role in the current network scenario. In a dynamic mobile ad hoc network, ensuring optimum QoS with a scarce network resource is a significant challenge. To achieve QoS, it is essential to adopt some effective and efficient mechanisms. We have proposed an adaptive bandwidth manager model (ABMM) which uses a bandwidthsharing concept along with the flexible bandwidth reservation algorithm (FBRA) for an effective, quick and authentic data transfer. During real-time data transfer, to make communication effective, we make use of bandwidth-sharing network design problems and the concept of reserving bandwidth in high-performance networks. In our proposed model we are concentrating on the maximum utilization of resources, and using the scheduling concept to provide the minimum required bandwidth guarantee to QoS flows. Our goal is to reduce the delay in data transfer and enhance the throughput while properly utilizing the system resources. Our simulation result also shows that our model improves the network performance.
ADAPTIVE BANDWIDTH MANAGEMENT MODEL FOR WIRELESS MOBILE AD-HOC NETWORKIJCNCJournal
The quality of service (QoS) component in a mobile ad-hoc network has an active role in the current
network scenario. In a dynamic mobile ad hoc network, ensuring optimum QoS with a scarce network
resource is a significant challenge. To achieve QoS, it is essential to adopt some effective and efficient
mechanisms. We have proposed an adaptive bandwidth manager model (ABMM) which uses a bandwidthsharing concept along with the flexible bandwidth reservation algorithm (FBRA) for an effective, quick and
authentic data transfer. During real-time data transfer, to make communication effective, we make use of
bandwidth-sharing network design problems and the concept of reserving bandwidth in high-performance
networks. In our proposed model we are concentrating on the maximum utilization of resources, and using
the scheduling concept to provide the minimum required bandwidth guarantee to QoS flows. Our goal is to
reduce the delay in data transfer and enhance the throughput while properly utilizing the system resources.
Our simulation result also shows that our model improves the network performance.
Dynamic resource allocation for opportunistic software-defined IoT networks: s...IJECEIAES
Several wireless technologies have recently emerged to enable efficient and scalable Internet-of-Things (IoT) networking. Cognitive radio (CR) technology, enabled by software-defined radios, is considered one of the main IoT-enabling technologies that can provide opportunistic wireless access to a large number of connected IoT devices. An important challenge in this domain is how to dynamically enable IoT transmissions while achieving efficient spectrum usage with a minimum total power consumption under interference and traffic demand uncertainty. Toward this end, we propose a dynamic bandwidth/channel/power allocation algorithm that aims at maximizing the overall network’s throughput while selecting the set of power resulting in the minimum total transmission power. This problem can be formulated as a two-stage binary linear stochastic programming. Because the interference over different channels is a continuous random variable and noting that the interference statistics are highly correlated, a suboptimal sampling solution is proposed. Our proposed algorithm is an adaptive algorithm that is to be periodically conducted over time to consider the changes of the channel and interference conditions. Numerical results indicate that our proposed algorithm significantly increases the number of simultaneous IoT transmissions compared to a typical algorithm, and hence, the achieved throughput is improved.
Improved Algorithm for Throughput Maximization in MC-CDMAVLSICS Design
The Multi-Carrier Code Division Multiple Access (MC-CDMA) is becoming a very significant downlink multiple access technique for high-rate data transmission in the fourth generation wireless communication systems. By means of efficient resource allocation higher data rate i.e. throughput can be achieved. This paper evaluates the performance of group (subchannel) allocation criteria employed in downlink transmission, which results in throughput maximization. Proposed algorithm gives the modified technique of sub channel allocation in the downlink transmission of MC-CDMA systems. Simulation are carried out for all the three combining schemes, results shows that for the given power and BER proposed algorithm comparatively gives far better results .
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.
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
LTE QOS DYNAMIC RESOURCE BLOCK ALLOCATION WITH POWER SOURCE LIMITATION AND QU...IJCNCJournal
3GPP has defined the long term evolution (LTE) for 3G radio access in order to maintain the future
competitiveness for 3G technology, the system provides the capability of supporting a mixture of services
with different quality of service (QoS) requirements. This paper proposes a new cross-layer scheduling
algorithm to satisfy better QoS parameters for real time applications. The proposed algorithm takes care of
allocating resource blocks (RBs) with different modulation and coding schemes (MCS) according to target
bit error rate (BER), user equipment supportable MCS, queue stability constraints and available transmit
power constraints. The proposed algorithm has been valued, compared with an earlier allocation algorithm
in terms of service rate and packet delay and showed better performance regards the real time
applications.
In this project, we proposed a framework to support heterogenous traffic with different QoS demand in
WiMAX. This framework dynamically changes the bandwidth allocation (BA) for ongoing and new arrival
connections based on network condition and service demand. The objective is to efficiently use the
available bandwidth and provide QoS support in a fair manner. Dynamic allocation of spectrum prior to
transmission can mitigate the starvation problem of Non Real time application. The WFQ based dynamic
bandwidth allocation framework uses architecture that has packet scheduler scheme (PS), call admission
policy and a dynamic bandwidth allocation mechanism. By the simulation result we have showed that this
architecture could provide QoS support by being fair to all classes of services.
PERFORMANCE ANALYSIS OF WIRELESS MESH NETWORK USING ADAPTIVE INFORMANT FACTOR...IJCSES Journal
Wireless mesh network (WMN) has become an important leading technology which provides several types of useful applications such as community network, broadband home network and internet access, etc. The rise in the size of users in WMN has created a degradation of efficiency in a network especially in dense areas due to the clumsy channel allocation and hence creating many challenges for enhancing the users experience, network quality and throughput. Therefore in this paper, we proposed OCA based AIF model that can access the channel information and then it process to improve the RF channel association. The proposed OCA-AIF will function for each period when some interference is detected via AIF and we further extend this analysis by taking in to consideration the influence of interference to provide a high quality indicator in network. The analysis of result shows the optimization by our proposed approach which increases as per the increment of relay nodes (RNs).
Constellation Shared Multiple Access - A Noma Scheme for Increased User Capac...IJCNCJournal
While the legacy cyclic prefix orthogonal frequency division multiple access is retained as the preferred multiple access scheme for 5G enhanced mobile broadband the research is now focussed on the multiple access schemes for massive machine type communication (mMTC) and ultra-reliable low latency communication .Though orthogonal multiple access schemes provide simple reception, they limit number of simultaneous user equipment as against the primary requirement of mMTC. On the other hand, the various non-orthogonal multiple access schemes which have been proposed so far as the likely solution, need complex successive interference cancellation receivers. So a simplified scheme named constellation shared multiple access is proposed here which substantially increases the number of simultaneous users to be served within a single resource block (RB) in LTE or 5G New Radio, thus aiding the massive connectivity requirement of mMTC. This is achieved by differentiating among the users in constellation domain. Moreover, the simple architecture compatible with 5G eMBB makes it a strong contender multiple access contender for 5G mMTC.
CONSTELLATION SHARED MULTIPLE ACCESS - A NOMA SCHEME FOR INCREASED USER CAPAC...IJCNCJournal
While the legacy cyclic prefix orthogonal frequency division multiple access is retained as the preferred
multiple access scheme for 5G enhanced mobile broadband the research is now focussed on the multiple
access schemes for massive machine type communication (mMTC) and ultra-reliable low latency
communication .Though orthogonal multiple access schemes provide simple reception, they limit number
of simultaneous user equipment as against the primary requirement of mMTC. On the other hand, the
various non-orthogonal multiple access schemes which have been proposed so far as the likely solution,
need complex successive interference cancellation receivers. So a simplified scheme named constellation
shared multiple access is proposed here which substantially increases the number of simultaneous users to
be served within a single resource block (RB) in LTE or 5G New Radio, thus aiding the massive
connectivity requirement of mMTC. This is achieved by differentiating among the users in constellation
domain. Moreover, the simple architecture compatible with 5G eMBB makes it a strong contender multiple
access contender for 5G mMTC.
Channel feedback scheduling for wireless communicationseSAT Journals
Abstract Opportunistic scheduling can significantly improve wireless network performance by exploiting the underlying channel condition. There has been a lot of work on opportunistic scheduling, but the problem of finding the right feedback mechanism to convey channel information has largely been untouched. In emerging multichannel systems, the per-channel feedback induces a substantial amount of feedback overhead and requires high computational complexity. To reduce the feedback overhead, we consider an opportunistic feedback strategy that activates the channel feedback opportunistically according to the channel condition. Then, we combine the opportunistic feedback with the best-n channel feedback scheme where a mobile user chooses the best n channels and transfers this information to the base station. We analyze the throughput and the amount of channel feedback information for proportionally fair opportunistic scheduling under Rayleigh fading i.i.d. channels. The numerical results confirm that our partial feedback schemes achieve a remarkable reduction in the amount of feedback information without significant throughput degradation, thereby saving the scarce wireless bandwidth and limited battery power.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
Performance analysis for Adaptive Subcarriers Allocation in Coherent Optical ...iosrjce
The constraint to satisfy the need of increased bandwidth requirement for high speed applications
with higher performance has been a motivation to work on Optical Orthogonal Frequency division multiplexing
(OOFDM) technique with coherent detection. We implement the coherent optical OFDM (CO-OOFDM)
technique and investigate the effect of the number of sub-carriers on performance over single mode fiber (SMF)
links. To explore improvement in performance adaptive subcarriers has been selected by assigning subcarriers
to user according to the conditions of channel. An adaptive subcarrier allocation has been investigated and
performance comparison for proportional and equal allocation has been carried over.
DYNAMIC CURATIVE MECHANISM FOR GEOGRAPHIC ROUTING IN WIRELESS MULTIMEDIA SENS...csandit
Maintaining network stability and extending network lifetime to cope with breaking links and topology changes remain nowadays a unsolved issues in Wireless Multimedia Sensor Networks (WMSNs), which aim to ensure flow delivery while guaranteeing QoS requirements, particularly, during data transmission phase. Therefore, in this paper, we jointly consider multipath transmission, load balancing and fault tolerance, to enhance the reliability of transmitted data. We propose a Dynamic Curative Mechanism for Geographic Routing in WMSNs. Theoricals results and those obtained from simulation study demonstrate the validity and efficiency of our proposed mechanism, and indicate that it is highly advised for multimedia transmission and network stability
RESOURCE ALLOCATION ALGORITHMS FOR QOS OPTIMIZATION IN MOBILE WIMAX NETWORKSijwmn
WiMAX is based on the standard IEEE 802.16e-2009 for wireless access in Metropolitan Area Networks. It
is one of the solutions for 4G IP based wireless technology. WiMAX utilizes Orthogonal Frequency
Division Multiple Access which also supports Multicast and Broadcast Service with appropriate
Modulation and Coding Scheme. Presently, Scheduling and Resource allocation algorithm in Opportunistic
Layered Multicasting provides multicasting of layered video over mobile WiMAX to ensure better QoS.
Initially, the knowledge based allocation of subcarriers is used for scheduling. In addition, to reduce the
burst overhead, delay and jitter, SWIM (Swapping Min-Max) algorithm is utilized. Another promising
technology that can greatly improve the system performance by exploring the broadcasting nature of
wireless channels and the cooperation among multiple users is the Cooperative Multicast Scheduling
(CMS) technique. The simulation results show, Swapping Min-Max performs better with lesser number of
bursts, Zero jitter and with optimal throughput. The results with Cooperative Multicast Scheduling show
the enhanced throughput for each member in the Multicasting Scenario.
General Model for Single and Multiple Channels WLANs with Quality of Service...ijwmn
In this paper we develop an intergraded model for request mechanism and data transmission in the uplink
phase in the presence of channel noise. This model supports quality of service. The wireless channel is prone
to many impairments. Thus, certain techniques have to be developed to deliver data to the receiver. We
calculated the performance parameters for single and multichannel wireless networks, like the requests
throughput, data throughput and the requests acceptance probability and data acceptance probability. The
proposed model is general model since it can be applied to different wireless networks such as IEEE802.11a,
IEEE802.16e, CDMA operated networks and Hiperlan\2.
General Model for Single and Multiple Channels WLANs with Quality of Service ...ijwmn
In this paper we develop an intergraded model for request mechanism and data transmission in the uplink phase in the presence of channel noise. This model supports quality of service. The wireless channel is prone to many impairments. Thus, certain techniques have to be developed to deliver data to the receiver. We calculated the performance parameters for single and multichannel wireless networks, like the requests throughput, data throughput and the requests acceptance probability and data acceptance probability. The proposed model is general model since it can be applied to different wireless networks such as IEEE802.11a, IEEE802.16e, CDMA operated networks and Hiperlan\2.
Similar to CROSS-LAYER RESOURCE ALLOCATION SCHEME UNDER HETEROGENEOUS CONSTRAINTS FOR NEXT GENERATION HIGH RATE WPAN (20)
Industrial Training at Shahjalal Fertilizer Company Limited (SFCL)MdTanvirMahtab2
This presentation is about the working procedure of Shahjalal Fertilizer Company Limited (SFCL). A Govt. owned Company of Bangladesh Chemical Industries Corporation under Ministry of Industries.
Explore the innovative world of trenchless pipe repair with our comprehensive guide, "The Benefits and Techniques of Trenchless Pipe Repair." This document delves into the modern methods of repairing underground pipes without the need for extensive excavation, highlighting the numerous advantages and the latest techniques used in the industry.
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About
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
Technical Specifications
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
Key Features
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface
• Compatible with MAFI CCR system
• Copatiable with IDM8000 CCR
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
Application
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
Cosmetic shop management system project report.pdfKamal Acharya
Buying new cosmetic products is difficult. It can even be scary for those who have sensitive skin and are prone to skin trouble. The information needed to alleviate this problem is on the back of each product, but it's thought to interpret those ingredient lists unless you have a background in chemistry.
Instead of buying and hoping for the best, we can use data science to help us predict which products may be good fits for us. It includes various function programs to do the above mentioned tasks.
Data file handling has been effectively used in the program.
The automated cosmetic shop management system should deal with the automation of general workflow and administration process of the shop. The main processes of the system focus on customer's request where the system is able to search the most appropriate products and deliver it to the customers. It should help the employees to quickly identify the list of cosmetic product that have reached the minimum quantity and also keep a track of expired date for each cosmetic product. It should help the employees to find the rack number in which the product is placed.It is also Faster and more efficient way.
CROSS-LAYER RESOURCE ALLOCATION SCHEME UNDER HETEROGENEOUS CONSTRAINTS FOR NEXT GENERATION HIGH RATE WPAN
1. International Journal of Network Security & Its Applications (IJNSA), Vol.2, No.3, July 2010
DOI : 10.5121/ijnsa.2010.2302 18
CROSS-LAYER RESOURCE ALLOCATION SCHEME
UNDER HETEROGENEOUS CONSTRAINTS FOR
NEXT GENERATION HIGH RATE WPAN
Ayman Khalil, Matthieu Crussière and Jean-François Hélard
INSA, 20 avenue des Buttes de Coësmes, 35708 Rennes, France
Institute of Electronics and Telecommunications of Rennes (IETR)
ayman.khalil@insa-rennes.fr
ABSTRACT
In the next generation wireless networks, the growing demand for new wireless applications is
accompanied with high expectations for better quality of service (QoS) fulfillment especially for
multimedia applications. Furthermore, the coexistence of future unlicensed users with existing licensed
users is becoming a challenging task in the next generation communication systems to overcome the
underutilization of the spectrum. A QoS and interference aware resource allocation is thus of special
interest in order to respond to the heterogeneous constraints of the next generation networks. In this
work, we address the issue of resource allocation under heterogeneous constraints for unlicensed multi-
band ultra-wideband (UWB) systems in the context of Future Home Networks, i.e. the wireless personal
area network (WPAN). The problem is first studied analytically using a heterogeneous constrained
optimization problem formulation. After studying the characteristics of the optimal solution, we propose a
low-complexity suboptimal algorithm based on a cross-layer approach that combines information
provided by the PHY and MAC layers. While the PHY layer is responsible for providing the channel
quality of the unlicensed UWB users as well as their interference power that they cause on licensed users,
the MAC layer is responsible for classifying the unlicensed users using a two-class based approach that
guarantees for multimedia services a high-priority level compared to other services. Combined in an
efficient and simple way, the PHY and MAC information present the key elements of the aimed resource
allocation. Simulation results demonstrate that the proposed scheme provides a good tradeoff between
the QoS satisfaction of the unlicensed applications with hard QoS requirements and the limitation of the
interference affecting the licensed users.
KEYWORDS
Interference limitation, MB-OFDM, QoS, service differentiation.
1. INTRODUCTION
While the next generation wireless networks are being driven by a large set of new application
requirements, they are promising to provide higher data rates and better quality of service (QoS)
achievement especially for multimedia applications. Thereby, as the number of wireless
applications is increasing, the coexistence of various types of wireless devices is one of the
major challenging issues.
On the other hand, while spectrum resource has become increasingly scarce, spectrum
occupancy measurements have shown that most of the assigned radio spectrum is still
significantly underutilized. In that context, cognitive radio (CR) and ultra-wideband (UWB) are
two recent and exciting technologies that offer new solutions for the spectrum scarcity and
spectrum underutilization. CR is based on the spectrum sensing and dynamic spectrum access
(DSA) techniques to find available spectrum which can be used by a CR user without causing
any harmful interference to licensed users [1]. The UWB approach is however based on an
underlay usage of the spectrum obtained under tough power spectral density (PSD) limitations.
With this latter solution, even if the transmission mask should protect existing systems, there is
2. International Journal of Network Security & Its Applications (IJNSA), Vol.2, No.3, July 2010
19
interest in finding a flexible method for managing the spectrum access of the secondary users in
order to satisfy high-priority multimedia services while reducing the interference they cause on
the licensed users.
So far, UWB has been attracting great interest as an appropriate technology for unlicensed next
generation short range communications. In 2002, the Federal Communications Commission
(FCC) regulated UWB systems by allocating them the 3.1 to 10.6 GHz spectrum for unlicensed
use [2], with a power spectral density level restricted to a maximum of -41.3 dBm/MHz. This
stringent power limitation should ensure an underlay usage of the spectrum with little effects on
other licensed services. One of the techniques proposed for high-rate UWB by the
IEEE802.15.3a workgroup is based on orthogonal frequency division multiplexing (OFDM)
referred to as MB-OFDM [3]. Since 2005, this MB-OFDM approach has been supported by the
WiMedia Alliance that promoted it to the ECMA International standardization body. As a
result, on December 2005, ECMA International eventually approved two standards for UWB
technology [4] based on the MB-OFDM WiMedia solution: ECMA-368 for high-rate UWB
PHY and MAC Standard and ECMA-369 for MAC-PHY Interface for ECMA-368. However,
these standardized UWB systems do not integrate any efficient adaptive mechanisms for
dynamic spectrum usage and interference mitigation.
In the literature, the resource allocation problem in OFDM systems is addressed in general as an
optimization problem where optimal and suboptimal subcarrier and power allocation are
proposed using one of the two well-known optimization classes: margin adaptive and rate
adaptive [5, 6]. Besides, some studies have been devoted to the resource allocation problem
under interference constraints. In [7] for instance, the authors define an optimization allocation
problem that maximizes the system throughput (i.e. the sum of the rates of all users) while
limiting the interference caused by each unlicensed user. Comparatively, in [8], a suboptimal
resource allocation algorithm that minimizes the total interference caused by unlicensed users as
well as their transmitted power is presented. In [9], the authors introduce optimal and
suboptimal power loading algorithms for an OFDM-based CR system under interference
limitations.
In MB-OFDM UWB, few related studies are proposed for spectrum sharing and resource
allocation. The authors in [10] focus on the adaptive subcarrier selection and power allocation in
OFDM-based UWB systems in a single-user scheme. A multiuser optimal and suboptimal sub-
band and power allocation scheme for the multiband UWB systems is also proposed in [11]
under limited power constraint.
None of the above mentioned studies takes into consideration the service differentiation and the
QoS support for multimedia and real-time applications with the interference constraint. In the
perspective of a diversification of the application requirements, this feature has however to be
considered in the design of allocation algorithms.
The objective of this paper is to study a novel heterogeneous resource allocation optimization
scheme for the MB-OFDM UWB systems under interference and QoS constraints so that we
can make a proper tradeoff between the QoS support and the interference level in order to
satisfy both the unlicensed multimedia users and the primary users. Eventually, we aim at
defining a new allocation scheme for the unlicensed UWB users that takes into account the
following three major criteria: (i) the service differentiation issue through the classification of
the UWB users in two classes: Hard-QoS (or HQoS) class for multimedia applications, and
Soft-QoS (or SQoS) class for data applications; (ii) the channel state information (CSI) through
the use of the effective SINR method; and (iii) the limitation of the interference introduced by
the unlicensed UWB users on the existing licensed users.
The paper is organized as follows. In section 2, the MB-OFDM UWB system model is
introduced. Then, an analytical study is defined in section 3. The appropriate allocation criteria,
i.e. the service differentiation, the CSI and the interference power are presented in order to serve
3. International Journal of Network Security & Its Applications (IJNSA), Vol.2, No.3, July 2010
20
the optimization problem. Based on the aspects presented in section 3, the constrained
optimization problem is derived in section 4. We propose in section 5 two algorithms for the
addressed problem; one optimal algorithm based on an iterative procedure to obtain the optimal
sub-band and power allocation, and one low-complexity suboptimal algorithm based on a
simple cross-layer approach. Section 6 gives simulation results for the proposed algorithms and
provides analysis and comparisons between the performance of the optimal and suboptimal
solutions. Besides, we present some analysis on the interference impact on licensed users as
well as the performance of the UWB users in terms of power and rate satisfaction in order to
check the QoS support of users having strict QoS requirements.
2. SYSTEM MODEL: MB-OFDM SOLUTION
The MB-OFDM UWB approach (or equivalently the WiMedia solution) consists in combining
OFDM with a multi-banding technique that divides the available band into 14 sub-bands of 528
MHz each, as illustrated in Fig. 1. Five band groups or channels are defined, each consisting of
three consecutive sub-bands, except for the fifth one which includes only the last two sub-
bands. A WiMedia compatible device should actually make use of only one out of these five
defined channels. As mentioned in the introduction, note that the PSD level is set to -41.3
dBm/MHz for UWB systems.
In this system, the MB-OFDM scheme is applied with a total of 128 subcarriers per band, 100
data carriers, 10 guard carriers, 12 pilot and 6 null tones. The OFDM signal can be transmitted
on each sub-band using a 128-point inverse fast Fourier transform (IFFT). The pilot tones are
used in order to achieve the coherent detection. The constellation applied to the different
subcarriers is either a quadrature phase-shift keying (QPSK) for the low data rates or a dual
carrier modulation (DCM) for the high data rates. Different data rates from 53.3 to 480 Mbps
are obtained with the combined use of forward error correction (FEC), frequency-domain
spreading (FDS) and time-domain spreading (TDS), as presented in Table 1. This enables
optimum performance under a variety of channel conditions varying the information data rate of
the system. The FEC used is a convolutional code with coding rates of 1/3, 1/2, 5/8 and 3/4.
Note that in Table 1, a new parameter λ is introduced. This parameter will be defined in section
3and used for the exploitation of the CSI at the physical level.
1 2 3 4 8765 109
U-NII
GSM
GPS
WiMAX
ISM
UWB
-41.3 dBm/MHz
Emitted
Signal
Power
Frequency (GHz)
Band
1
Band
2
Band
3
Band
4
Band
5
Band
6
Band
7
Band
8
Band
9
Band
10
Band
11
Band
12
Band
13
Band
14
Channel 1 Channel 2 Channel 3 Channel 4 Channel 5
3432 3960 4488 5016 5544 6072 6600 7128 7656 8184 8712 9240 9768 10296
f
(MHz
Fig. 1. UWB spectrum and sub-band distribution for WiMedia solution.
4. International Journal of Network Security & Its Applications (IJNSA), Vol.2, No.3, July 2010
21
Table 1. WiMedia data rates and the associated parameter λ.
Data Rate
(Mbps)
Modulation Coding
Rate
(r)
Frequency
Domain
Spreading
Time
Spreading
Factor
Code bits
per OFDM symbol
λ
53.3 QPSK 1/3 Yes 2 100 1.49
80 QPSK 1/2 Yes 2 100 1.57
110 QPSK 11/32 No 2 200 1.42
160 QPSK 1/2 No 2 200 1.57
200 QPSK 5/8 No 2 200 1.82
320 DCM 1/2 No 1 200 1.85
400 DCM 5/8 No 1 200 1.82
480 DCM 3/4 No 1 200 1.80
The coded data is spread by using a time-frequency code (TFC). In all, there are two types of
TFCs. The first one is a time-frequency interleaving (TFI), where the coded information is
interleaved over three bands and the second one is a fixed frequency interleaving (FFI), where
the coded information is transmitted on a single band. TFC allows each user to benefit from
frequency diversity over a bandwidth equivalent to the two or three sub-bands of one channel.
In addition, to prevent interference between consecutive symbols, a zero padding (ZP) guard
interval is added instead of the traditional cyclic prefix (CP) used in the classical OFDM
systems. The ZP simply consists in trailing zeros and requires a specific processing at the
receiver side to compensate for the lack of cyclic structure in the received signal and hereby
make possible a simple OFDM demodulation through FFT computation [12].
From the physical layer point of view, the WiMedia solution offers potential advantages for
high-rate UWB applications, such as the signal robustness against channel selectivity and the
efficient exploitation of the energy of every signal received within the prefix margin.
Concerning the MAC layer and the medium access, a combination of carrier sense multiple
access (CSMA) and time division multiple access (TDMA) is adopted to ensure prioritized
schemes for isochronous and asynchronous traffics. To reserve any TDMA access for
isochronous and other data transfer, a distributed reservation protocol (DRP) is used. For
network scalability, meaning possible less use of extra resources when the number of devices
increases, prioritized contention access (PCA) is provided using a CSMA scheme [4].
Channel time is divided into superframes. A superframe is the basic timing structure for frame
exchange and it is composed of two major parts, the beacon period (BP) and the data transfer
period (DTP). The duration of the superframe is specified as 65536 µs, and the superframe
consists of 256 medium access slots (MASs), which are all of equal length, 256 µs.
3. CROSS-LAYER INFORMATION
The proposed allocation scheme counts on the collection of information located at two different
levels, more precisely the PHY and the MAC levels. In this section, we present the new
functionalities of these two layers that should contribute to the optimization problem
formulation.
3.1. MAC layer Information
3.1.1. Service classification
Since multimedia applications services are key applications in next generation wireless
networks, especially in high-rate UWB networks, it is desirable to assign them a high level of
priority in any radio access mechanism. A two-level service classification model is proposed in
5. International Journal of Network Security & Its Applications (IJNSA), Vol.2, No.3, July 2010
22
this paper to ensure the prioritization principle and to respond to next generation systems QoS
requirements. Consequently, we classify the UWB service types into two classes:
1. Hard-QoS class (HQoS): This class is defined for applications or services that
require strong QoS support, more precisely multimedia applications. Voice and
video services for instance are non delay-tolerant applications, they have thus strict
QoS requirements and they definitely belong to this class.
2. Soft-QoS class (SQoS): This class is dedicated to applications that don’t have strict
QoS requirements, more precisely non real-time or data applications. Best effort
(BE) and file transfer services for instance are delay-tolerant applications, they
belong thus to this class.
3.1.2. Weight assignment
The defined service classification scheme offers a two-level priority-based model which affects
the scheduling decision. Effectively, we assign a class weight to the different users or
applications belonging to the two defined classes. A higher weight is thus to be assigned to the
service type with strict QoS requirements.
Our weight assignment model is divided into two parts: fixed class weight assignment and
dynamic service weight assignment:
• Fixed class weight
A constant weight is assigned to the users aiming at accessing the network based on the class to
which they belong. This approach is proposed in [16] for IEEE 802.16 where the four defined
classes are assigned four weights according to the class priority. Similarly, according to our
two-level service classification model, weight 2 is attributed to HQoS class and weight 1 to
SQoS class.
• Dynamic service weight
Since different services belonging to the same class may have different QoS requirements, we
define a dynamic service weight that ensures an additional level of differentiation between users
according to their requested data rates. Consequently, a user k is assigned a service weight sk
defined as
min
max min
1 k
k
R R
s
R R
−
= +
−
(1)
where Rk is the user k requested data rate, Rmin and Rmax are respectively the lowest and the
highest data rates taken from the WiMedia data rate modes as presented in Table 1. Evidently,
this service weight gives advantage to users having high data rate requirements.
Note that if two or more users require the same data rate which results in assigning them the
same weight, an additional differentiation level is demanded which is the delay tolerance. For
instance, two users belonging to the same class and having the same rate requirements have to
be differentiated according to their target delay requirement, so that the user with a lower delay
tolerance is considered as a higher priority user.
• Absolute user weight
Provided by the MAC layer, the fixed and the dynamic weight definitions ensure an adaptive
rate differentiation for the end-users according to their requirements and to the system
constraints. Accordingly, the absolute user weight W is the combination of the class weight with
the service weight defined as
6. International Journal of Network Security & Its Applications (IJNSA), Vol.2, No.3, July 2010
23
k k kW q s= × (2)
where qk is the user k class weight and sk is its service weight.
3.2. PHY layer Information
3.2.1. Channel State Information (CSI)
Since the unlicensed UWB users have to learn about the channel conditions to adjust their
transmission parameters, useful channel information can be provided to each user by exploiting
the CSI. Assuming that the instantaneous SINR for each subcarrier is known by each user, it is
possible to evaluate the system level performance in terms of BER by using the effective SINR
approach. The basic idea of the effective SINR method is to find a compression function that
maps the sequence of varying SINRs to a single value that is correlated with the BER. This new
channel approach used in the 3GPP standardization as an effective link to system mapping
method [13,14] is useful in representing the quality of a sub-band by a scalar value stated as
1
1
1
( )
N
eff i
i
SINR I I SINR
N
−
=
=
∑ (3)
where I(x) is called the information measure function, N the number of subcarriers in a sub-band
and iSINR the ratio of signal to interference and noise for the ith subcarrier. Referring to the
Exponential Effective SINR Mapping (EESM), we use the following expression for I(x)
( ) exp( )
x
I x
λ
= − (4)
where λ is a scaling factor that depends on the selected modulation and coding scheme (MCS).
In our system, λ is computed and evaluated for the eight WiMedia data rate modes as presented
in Table 1.
Eventually, the effective SINR writes
1
1
ln exp( )
N
i
eff
i
SINR
SINR
N
λ
λ=
= − −
∑ (5)
In practice, based on the CSI knowledge, each user is capable to compute the effective SINR
value in each sub-band by using (5). For instance, in the case of one channel divided into 3B =
sub-bands and with 3K = users, the physical layer information is reduced to the knowledge of
only 9B K× = effective SINR values.
3.2.2. Interference Power
With the limited power imposed by the FCC to the unlicensed UWB users, we have to be aware
in any power allocation scheme to limit the interference that could be caused by the UWB users
to the primary users sharing the same spectrum. More precisely, since we are dealing with
heterogeneous environment due to different service classes or traffic types, this will absolutely
lead to different power level assignments. Our objective is thus to control the power assignment
of the different UWB users in order to limit or reduce the interference caused by these users on
the primary users.
According to [15], in OFDM systems the interference power caused by a secondary user k
assigned a subcarrier i and affecting a primary user u is defined as
, ,
u
k i k i iI P I= (6)
7. International Journal of Network Security & Its Applications (IJNSA), Vol.2, No.3, July 2010
24
1
( )
2
1
( )
2
where ( )
u
i
u
i
n f
i i
n f
I f df
+ ∆
− ∆
= Φ∫ (7)
where Pk,i is the power allocated to user k in subcarrier i, u
in the spectral distance between
subcarrier i and the center of primary user u band, f∆ the bandwidth of primary user u band and
( )i fΦ the spectral pulse shape of subcarrier i.
We extend these formulas to the MB-OFDM systems to obtain
, ,
u
k b k b bI P I= (8)
1
( )
2
1 1
( )
2
where ( )
u
i
u
i
n f
N
b i
i
n f
I f df
+ ∆
=
− ∆
= Φ∑ ∫ (9)
where Pk,b is the power allocated to user k in sub-band b and N the number of subcarriers in one
sub-band.
4. PROBLEM FORMULATION
In order to address the resource allocation matter in a heterogeneous context under QoS and
interference requirements, we first study it analytically by deriving a constrained optimization
problem. We consider a system consisting of U primary users and K UWB users where the first
Kh users are HQoS users and the remaining K-Kh are SQoS users. The rate of a user k in sub-
band b is defined as
, 2 , ,log (1 )k b k b k br P E= + (10)
where Ek,b is the effective SINR of user k in sub-band b. The objective is to find a joint sub-band
and power allocation scheme for the UWB users in a fair way that maximizes the total data rate
of the K-Kh SQoS users while respecting the following conditions:
- maintaining a certain level of transmission rate for the Kh HQoS users,
- limiting or reducing the interference power caused by the UWB users on the primary users,
- and respecting the total transmission power PT constraint of the UWB systems.
The problem can be formulated as
,
,
1
,
,
1 1
,
1 1
max
, 1,...,
, 1,...,
k k
h k
k
K
k b
S P
k K b S
k b k h
b S
K B
u th
k b u
k b
K B
k b T
k b
r
subject to r R k K
I I u U
P P
= + ∈
∈
= =
= =
≥ =
≤ =
≤
∑ ∑
∑
∑∑
∑∑
(11)
where B is the total number of sub-bands, Rk the HQoS user k required data rate, th
uI the power
interference threshold defined by the primary user u, Sk the set of sub-bands assigned to user k.
In our case, S1, S2,.., Sk are disjoint and each user is assigned one sub-band during one time
interval. This problem is a mixed integer linear programming problem since Sk are integer
variables [17]. Consequently, the problem is classified as NP-hard. A method that makes the
problem solvable is to relax the constraint that each sub-band is assigned to one user only. The
8. International Journal of Network Security & Its Applications (IJNSA), Vol.2, No.3, July 2010
25
idea is to allow the users to time-share each sub-band by defining a new parameter ρk,b, which
represents the time-sharing factor for user k of sub-band b. The optimization problem can be
reformulated as
, ,
, ,
, 2
,
1 1 ,
, ,
, 2
1 ,
, ,
1
max log (1 )
log (1 ) , 1,.....
1, 0 1 ,
k b k b
h
K B
k b k b
k b
P
k K b k b
B
k b k b
k b k h
b k b
K
k b k b
k
P E
P E
subject to R k K
b k b
ρ
ρ
ρ
ρ
ρ
ρ ρ
= + =
=
=
+
+ ≥ =
= ∀ ≤ ≤ ∀
∑ ∑
∑
∑
,
1 1
,
1 1
, 1,...,
K B
u th
k b u
k b
K B
k b T
k b
I I u U
P P
= =
= =
≤ =
≤
∑∑
∑∑
(12)
The problem in (12) is a convex maximization problem. Using standard optimization
techniques, we obtain the Lagrangian
, , , ,
, 2 , 2
1 1 1 1, ,
, , ,
1 1 1 1 1 1
log (1 ) ( log (1 ) )
(1 ) ( - )+ ( )
h
h
KK B B
k b k b k b k b
k b k k b k
k K b k bk b k b
B K K B K B
th u
b k b u k b T k b
b k k b k b
P E P E
L R
I I P P
ρ α ρ
ρ ρ
β ρ γ θ
= + = = =
= = = = = =
= + + + − +
− + −
∑ ∑ ∑ ∑
∑ ∑ ∑∑ ∑∑
(13)
Sub-band Allocation
Let *
,k bρ be the optimal solution. After differentiating (13) with respect to ,k bρ by KKT
optimality condition [18], we obtain
,
2
,
,
2
,
1 ln2
log ( ) (1 ) 0, for 1,..,
ln2 ln2
1 ln 2
log ( ) (1 ) 0, for 1,..,
ln2 ln 2
k k b
k b h
k k b
k b
b h
k b
E
k K
E
E
k K K
E
α γ
α β
γ α
γ
β
γ
− − − = =
− − − = = +
(14)
Since *
,k bρ should satisfy the following KKT condition
*
,
*
,*
, *
,
>0, 1
= 0, 0 < < 1
0, 0
k b
k b
k b
k b
L
ρ
ρ
ρ
ρ
=
∂
=
∂
< =
(15)
Substituting (14) into (15), we get
,*
,
,
1,
0,
k b b
k b
k b b
H
H
β
ρ
β
>
=
<
(16)
where Hk,b is defined as
9. International Journal of Network Security & Its Applications (IJNSA), Vol.2, No.3, July 2010
26
,
, 2
,
,
, 2
,
1 ln 2
log ( ) (1 ) , for 1,..,
ln2 ln 2
1 ln2
log ( ) (1 ), for 1,..,
ln 2 ln 2
k k b
k b k h
k k b
k b
k b h
k b
E
H k K
E
E
H k K K
E
α γ
α
γ α
γ
γ
= − − =
= − − = +
(17)
We conclude that, for a chosen sub-band b, the user with the largest Hk,b can use the sub-band.
In other words, for a sub-band b, if Hk,b are different for all k, then
* *
, ,1, 0 for allk b k b k kρ ρ′
′= = ≠ (18)
where ,arg max k b
k
k H′ = (19)
Power Allocation
Let *
,k bP be the optimal solution. After differentiating (13) with respect to ,k bP by KKT
optimality condition [18], we obtain
*
, ,
,
*
, ,
,
1
( ), for 1,..,
ln 2
1 1
( ), for 1,..,
ln 2
k
k b k b h
k b
k b k b h
k b
P k K
E
P k K K
E
α
ρ
γ
ρ
γ
= − =
= − = +
(20)
As a result, in order to achieve the sub-band and power allocation, we have to compute Hk,b and
Pk,b for all the existing UWB users. We thus need to find the set of αk such that the HQoS users
rate and the total power constraints are satisfied. This can be stated as
,
, 2
1
,
1 1
log ( ) , for 1,...,
ln 2
B
k k b
k k b k h
b
K B
k b T
k b
E
R R k K
P P
α
ρ
γ=
= =
′ = ≥ =
≤
∑
∑∑
(21)
Interference Power Control
After allocating the sub-bands and the power to the different UWB users, we eventually need to
satisfy the interference constraint. Since the interference power of a user k in a sub-band b
depends on its allocated power in this sub-band as given by (8), we control the interference that
may be caused by the UWB users to the primary users occupying the same spectrum after the
power allocation. The control consists in reducing the power level of the users causing an
interference level that exceeds the primary users interference threshold.
In order to be consistent with the HQoS users constraint, we have to make a certain tradeoff
between the interference reduction and the QoS satisfaction. Let ,k bP% be the power that should
be allocated to the part of the sub-band b causing interference. Thereby, we define a power
reduction parameter ,
red
k bP for the different UWB users as the power that should be reduced from
the allocated power in the band or the set of subcarriers that are causing interference to the
primary users. In the following we define the power reduction value in the case of SQoS and
HQoS users respectively.
- For SQoS users:
For SQoS users, the allocated power is annulled in the band or the set of subcarriers occupied
by a primary user. This is stated as
10. International Journal of Network Security & Its Applications (IJNSA), Vol.2, No.3, July 2010
27
, , ,0, and consequently red
k b k b k bP P P= =% (22)
This gives a protection to the primary user while reducing the performance of the SQoS UWB
users. The performance degradation of the SQoS users should be tolerable since these users do
not have strict QoS requirements.
- For HQoS users:
In the case of HQoS users, the interference reduction should take into consideration the rate
requirements of these users. In other terms, the power is reduced to a level that can satisfy the
HQoS constraints.
By taking the HQoS rate constraint given by (11), we can write
2 , , 2 , ,
1
log (1 ) log (1 )
up
ud
nB
k b k b k b k b k
b b n
P E P E R
= =
+ − + ≥∑ ∑ % (23)
where nup-nud is the bandwidth occupied by a primary user. Solving (23) we obtain
( )
,
,
2 1
up ud
k k
n n
r R
N
red
k b
k b
P
E
−
−
−
≤ (24)
This limitation in the interference reduction guarantees the QoS support of the HQoS users so
that any power reduction does not affect their rate requirements.
As a conclusion, adapting the interference power reduction value to the users QoS level gives a
kind of tradeoff between the need to protect the primary users and guarantee the QoS support of
the HQoS UWB users.
5. OPTIMAL AND SUBOPTIMAL ALLOCATION ALGORITHMS
5.1. Mathematical characteristics of the optimal solution
To solve the formulated optimization problem, we first study the characteristics of the sub-band
and power allocation functions given by (17) and (20) respectively. These two functions have
the following properties:
• First, they are monotonically increasing with respect to Ek,b. This means that, for a
selected sub-band, the user having better channel conditions has more chance to be
assigned this sub-band with a good power level.
• Second, the two allocation functions are monotonically increasing with respect to αk.
This can be viewed as a result of the service differentiation principle. In other terms, the
functions depend on the user priority and thus, the stricter the user requirements, the
higher the value of αk and consequently the higher the value of these functions.
• Third, we conclude from the HQoS users constraint given by (21) that αk is
monotonically increasing with respect to Rk.
As a result, the power and the sub-band allocation functions depend on the rate constraints of
the users, more precisely the HQoS users that have strict data rate requirements.
5.2. Optimal Algorithm
Based on the above observations, we propose an iterative algorithm detailed in Algorithm 1 for
the search of the optimal sub-band and power allocation. Thereby, since the interference power
control is a step that follows the power allocation step, the algorithm is divided into two parts:
the joint sub-band and power allocation part, and the interference control part. In the first part,
11. International Journal of Network Security & Its Applications (IJNSA), Vol.2, No.3, July 2010
28
the process consists in incrementing αk iteratively by a small value δ until reaching the HQoS
users data rate request while respecting the power constraint. Then, using the so-obtained αk, the
allocated power is refined in order to reduce the interference power to primary users as
described in the previous section.
Algorithm 1: Optimal Solution
Part 1: joint sub-band and power allocation
1- Initialization
alpha = 1
kα = alpha+δ, for k = 1,..,kh
2- Sub-band allocation
a. for sub-band b = 1,..,B
compute Hk,b using (17) for all k
obtain ,ρk b and ′k using (18) and (19)
b. for k = 1,..,kh
compute kR′ using (21)
c. for k = 1,..,kh
find %k with and′ ′ ′< − ≤ −% % % % k kk k k k
R R R R R R
d. while ′ <% %k k
R R
k k
α α δ= +% %
repeat a.,b. and c.
3- Power allocation
a. compute Pk,b using (20) for all k
b. compute ,
1 1= =
′ = ∑∑
K B
T k b
k b
P P
c. if ′ <T TP P
kα = kα + δ/2
else
kα = kα - δ/2
repeat 2. and 3. until ′ =T TP P
Part 2: Interference power control
1- for k = 1,..,K
compute ,
u
k bI using (8) for the allocated sub-band b
2- compute ,
1 1= =
′ = ∑∑
K B
u
u k b
k b
I I
3- if ′ > th
u uI I
a. find ˆk and the corresponding allocated sub-band ˆb with ˆ 0b
I ≠
b. if { }ˆ 1,..,hk k K∈ +
reduce the power in the subcarriers causing interference using (22)
else
reduce the power in the subcarriers causing interference using (24)
12. International Journal of Network Security & Its Applications (IJNSA), Vol.2, No.3, July 2010
29
5.3. Suboptimal Algorithm
In order to reduce the high computation cost of the optimal algorithm due to the iterative
process, we define a suboptimal allocation algorithm. This suboptimal algorithm is based on a
cross-layer approach in the way of collecting the corresponding information from the PHY and
MAC layers. The idea is first to replace αk by a static parameter that can be defined once for all
the users. We propose thus to use the weight parameter Wk defined in section 3.1. This can be
justified by the fact that the weight parameter has the same characteristics as αk; both parameters
depend on the service data requirements or the QoS level. Second, in the suboptimal solution,
the power is equally distributed among the different users and it is refined individually
according to each user conditions.
The new suboptimal sub-band allocation function that will replace the optimal sub-band
function given by (17) is defined as follows
, ,k b k k bH W E′ = (25)
Algorithm 2: Suboptimal Solution
1- Initialization
0=red
TP
2- Power distribution
, , for 1,..,T
k b
P
P k K
B
= =
3- Sub-band allocation
for sub-band b = 1,..,B
compute ,
′k bH using (25) for all k
,arg max′ ′= k bk H
4- Interference control
a. for k = 1,..,K
compute ,
u
k bI using (8) for the allocated sub-band b
b. compute ,
1 1= =
′ = ∑∑
K B
u
u k b
k b
I I
c. if ′ > th
u uI I
find ˆk and the corresponding allocated sub-band ˆb with ˆ 0b
I ≠
if { }ˆ 1,..,hk k K∈ +
reduce the power in the subcarriers causing interference using (22)
else
reduce the power in the subcarriers causing interference using (24)
ˆ ˆ, ,
ˆ,
′ = −
= +
red
T k b k b
red red red
T T k b
P P P
P P P
5- QoS control - power refinement
if 0red
TP ≠
a. for k = 1,..,kh
compute kR′ using (10)
b. for k = 1,..,kh
find ( )′ ′ ≠ %k k k with and′ ′ ′ ′′ ′ ′< − ≤ −k k k k k kR R R R R R
, ,′ ′= + red
k b k b TP P P
13. International Journal of Network Security & Its Applications (IJNSA), Vol.2, No.3, July 2010
30
The allocation function given by (25) can be viewed as a cross-layer function since it combines
the user weight as defined in (2), information provided by the MAC layer, and the user effective
SINR in a sub-band as defined in (5), information provided by the PHY layer.
Algorithm 2 presents the suboptimal solution. In this algorithm, the power is first distributed
equally among the existing users. Then, we proceed with the sub-band allocation using the
suboptimal allocation function given by (25). The interference control is done here before the
QoS satisfaction control. Thus, after the power reduction resulting from the interference power
control step, the power is refined in order to ensure the unsatisfied HQoS users having no
interference problem with primary users. To do so, we increase the allocated power of these
unsatisfied HQoS users by the amount of the power reduced from users having interference
problem with primary users.
6. SYSTEM PERFORMANCE
6.1. Channel model
The channel used in this study is the one adopted by the IEEE 802.15.3a committee for the
evaluation of UWB proposals [19]. This model is a modified version of Saleh-Valenzuela
model for indoor channels [20], fitting the properties of UWB channels. A log-normal
distribution is used for the multipath gain magnitude. In addition, independent fading is
assumed for each cluster and each ray within the cluster. The impulse response of the multipath
model is given by
0 0
( ) ( , ) ( ( ) ( , ))
i iZ P
i i i i i
z p
h t G z p t T z z pα δ τ
= =
= − −∑∑ (26)
where Gi is the log-normal shadowing of the ith channel realization, Ti(z) the delay of cluster z,
and ( , ) and ( , )i iz p z pα τ represent the gain and the delay of multipath p within cluster z,
respectively.
Four different channel models (CM1 to CM4) are defined for the UWB system modelling, each
with arrival rates and decay factors chosen to match different usage scenarios and to fit line-of-
sight (LOS) and non-line-of-sight (NLOS) cases.
6.2. Simulation results
In this section, we present the simulation results for the proposed allocation scheme and we
compare the performance of the optimal and the suboptimal solutions. For the simulation
scenarios, we use the proposed WiMedia data rates (see Table 1) and we consider the first
WiMedia channel (3.1-4.7 GHz) for CM1 channel model. Consequently, three unlicensed UWB
users are considered to send simultaneously by sharing the three sub-bands of the first WiMedia
channel. Moreover, we consider a licensed user occupying a bandwidth that varies from 1 to 50
MHz in the first WiMedia channel.
Since we aim at guaranteeing the QoS support of multimedia applications, we present in Fig. 2
the power satisfaction of the HQoS users causing interference on the licensed user. Two
scenarios are studied: scenario 1 consists of one unlicensed HQoS UWB transmitting at a data
rate of 320 Mbps and two SQoS users transmitting at 53.3 Mbps; and scenario 2 consisting of
one unlicensed HQoS UWB transmitting at a data rate of 160 Mbps and two SQoS users
transmitting at 53.3 Mbps. As explained before, contrarily to the SQoS users that annul their
power in the primary user band, the HQoS user reduces its transmission power to a certain limit
that respects its rate requirement. Accordingly, the power reduction depends on the rate
requirement Rk of the HQoS user and the bandwidth of the primary user occupying the same
UWB user band. As shown in the figure, if the data rate requirement level of the HQoS user is
high (Rk = 320 Mbps), the reduction is not considerable and the user satisfaction is good.
14. International Journal of Network Security & Its Applications (IJNSA), Vol.2, No.3, July 2010
31
0 5 10 15 20 25 30 35 40 45 50
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Primary user bandwidth (MHz)
PowerSatisfactionLevel
HQoS 320 Mbps optimal
HQoS 320 Mbps suboptimal
HQoS 160 Mbps optimal
HQoS 160 Mbps suboptimal
Fig. 2. Power satisfaction level of unlicensed HQoS users causing interference to a licensed
user.
However, in the case where Rk = 160 Mbps, we observe a substantial reduction level especially
if the bandwidth occupied by the primary user is large. This proves that users with high data rate
are more protected, which guarantees a good level of QoS support for multimedia applications
having high rate requirements. Besides, we notice that the optimal solution outperforms the
suboptimal solution with an average of 10% in both scenarios.
In Fig. 3, we present the interference reduction ratio in the cross-layer (suboptimal) solution for
the HQoS and the SQoS users in different conditions. We mean by interference reduction ratio
the ratio of the whole reduced interference level resulting from the power refinement of the
users causing interference to primary users, to the original interference level obtained before
applying the new allocation scheme. We present results according to three values of Ith as shown
in the figure. We consider a scenario which consists of one unlicensed HQoS UWB transmitting
at a data rate of 320 Mbps and two SQoS users transmitting at 53.3 Mbps. As we can observe,
increasing the value of Ith decreases the interference reduction level, which is normal since it is a
constraint imposed by the primary user to the UWB users. Besides, note that the interference
reduction in the case of SQoS users is more important. This is resulted from the fact that the
interference depends on the power which is annulled in the part of the band causing interference
by SQoS users on a primary user whereas it is reduced in the case of HQoS users.
0 5 10 15 20 25 30 35 40 45 50
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
Primary user bandwidth (MHz)
InterferencereductionRatio
SQoS - Ith = - 5 dB
SQoS - Ith = -10 dB
SQoS - Ith = -15 dB
HQoS - Ith = - 5 dB
HQoS - Ith = -10 dB
HQoS - Ith = -15 dB
Fig. 3. Interference reduction ratio for the different users in different conditions
15. International Journal of Network Security & Its Applications (IJNSA), Vol.2, No.3, July 2010
32
.
0 5 10 15 20 25 30 35 40 45 50
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Primary user bandwidth (MHz)
RateSatisfaction
HQoS - Optimal
HQoS - Suboptimal
SQoS - Optimal
SQoS - suboptimal
Fig. 4. Rate Satisfaction of HQos and SQoS users in the proposed scheme.
In Fig. 4, we present the average rate satisfaction level of all the users in the optimal and
suboptimal solutions. We consider the same scenarios defined for Fig. 2. As shown in the
figure, HQoS users rate satisfaction level is much more better than that of SQoS users. This
proves that the QoS support of the HQoS users is guaranteed in terms of rate satisfaction in both
optimal and suboptimal solutions. For instance, in the case where an HQoS user is causing
interference to a primary user occupying a bandwidth of 50 MHz, the rate satisfaction level is
almost 80%. On the other hand, since the SQoS users have less QoS requirements, their rate
satisfaction level decreases to 40% when they cause interference to a primary user occupying a
bandwidth of 50 MHz in the suboptimal solution. Besides, we note that the optimal and
suboptimal solutions perform very close in both HQoS and SQoS cases. This can be justified by
the fact that, in both solutions, the sub-band allocation is the same, so the channel quality is the
same and what differs is the assigned power level.
7. CONCLUSION
In this paper, we have studied the resource allocation problem for the unlicensed high-rate
UWB systems which use an underlay approach for the coexistence with already existing
licensed systems. This study gives an answer to the spectrum sharing problem for the secondary
users having heterogeneous conditions and aiming at coexisting with the primary users.
The problem has been first studied analytically by deriving a constrained optimization problem.
This study has lead to an optimal solution while considering three main constraints: the QoS
requirements, the channel quality, and the interference level caused by the UWB users on the
primary users. A suboptimal solution is also proposed to reduce the complexity of the optimal
solution. It is based on a cross-layer approach in the way it jointly considers information
provided by the PHY and MAC layers.
Finally, we have shown through simulations the efficiency of the proposed allocation scheme
that guarantees a good QoS support for users with strict requirements. Besides, the slight
performance degradation of the unlicensed users that do not have QoS requirements is viewed
as a sacrifice to ensure an efficient use of the spectrum that limits the interference affecting the
primary users. We have shown also that the optimal and suboptimal solutions perform close,
which means that the new simplified cross-layer approach is advantageous and can be an
efficient solution for the QoS support and spectrum sharing matters in the next generation UWB
systems.
16. International Journal of Network Security & Its Applications (IJNSA), Vol.2, No.3, July 2010
33
ACKNOWLEDGEMENTS
The research leading to these results has received funding from the European Community's
Seventh Framework Programme FP7/2007-2013 under grant agreement n° 213311 also referred
as OMEGA.
REFERENCES
[1] J. Mitola and G. Maguire, “Cognitive Radio: Making software radio more personal,” IEEE
Journal on Personal Communications, vol. 6, no. 4, pp. 13-18, Aug. 1999.
[2] “First report and order, revision of part 15 of the commission’s rules regarding ultra-wideband
transmission systems,” FCC, ET Docket 98-153, Feb. 14, 2002.
[3] WiMedia Alliance, Inc., “Multi-band OFDM physical layer specification,” Release 1.1, July
2005.
[4] Standard ECMA-368, High rate ultra wideband PHY and MAC standard, 2nd
edition, Sept. 2007.
[5] C.Y. Wong, R.S. Cheng, K.B. Lataief and R.D. Murch, “Multiuser OFDM with adaptive
subcarrier, bit and power allocation,” IEEE Journal on Selected Areas in Communications,
vol. 17, no. 10, pp. 1747-1758, Aug. 2002..
[6] I. Kim, I. Park and Y.H. Lee, “On the use of linear programming for dynamic subcarrier and bit
allocation in multiuser OFDM,” IEEE Trans. on Vehicular Technology, vol. 55, pp. 1195-1207,
July 2006.
[7] A. Attar, O. Holland, M.R. Nakhai and A.H. Aghvami, “Interference-limited resource allocation
for cognitive radio in orthogonal frequency-division multiplexing networks,” IET
Communications, vol. 2, no. 6, pp. 815-816, July 2008.
[8] T. Qin and C. Leung, “A cost minimization algorithm for a multiuser OFDM cognitive radio
system,” IEEE Pacific Rim Conference on Communications, Computers and Signal
(PacRim’07), pp. 518-521, Aug. 2007.
[9] G. Bansal, J. Hossain and V.K. Bhargava, “Optimal and suboptimal power allocation schemes
for OFDM-based cognitive radio systems,” IEEE Trans. on Wireless Communications, vol. 7,
no. 11, pp. 4710-4718, Nov. 2008.
[10] Z. Chen, D. Wang and G. Ding, “An OFDM-UWB scheme with adaptive carrier selection and
power allocation,” IEEE Intern. Conference on Wireless Communications, Networking and
Mobile Computing (WiCOM’06), pp.1-4, China, Sept. 2006.
[11] W.P. Siriwongpairat, Z. Han and K.J. Ray Liu, “Power controlled channel allocation for multi-
user multiband UWB systems,” IEEE Trans. on Wireless Communications, vol. 6, no. 2, pp.
583–592, Feb. 2007.
[12] B. Muquet, Z. Wang, G.B. Giannakis, M. de Courville and P. Duhamel, “Cylic pefix or zero
padding for wireless multicarrier transmission,” IEEE Trans. on Communications, vol. 50, pp.
2136-2148, Dec. 2002.
[13] 3GPP TSG-RAN-1, “R1-030999: considerations on the system performance evaluation of
HSDP using OFDM modulations”; RAN WG1 #34.
[14] 3GPP TSG-RAN-1, “R1-040090: system level performance evaluation for OFDM and WCDMA
in UTRAN,” Finland, Jan. 2004.
[15] T. Weiss, J. Hillenbrand, A. Krohn and F.K. Jondral, “Mutual interference in OFDM-based
spectrum pooling systems,” IEEE Vehicular Technology Conference (VTC’04-spring), pp.
1873-1877, May 2004.
[16] S. Maheshwari, “An Efficient QoS scheduling architecture for IEEE 802.16 wireless MANs,”
Indian Institute of Technology, India, 2005.
[17] S. Boyd and L. Vandenberghe, Convex Optimization. Cambridge University Press, 2004.
17. International Journal of Network Security & Its Applications (IJNSA), Vol.2, No.3, July 2010
34
[18] D.P. Bertsekas, Nonlinear Programming 2nd
Edition. Athena Scientific, 1999.
[19] J. Foester, “Channel Modeling sub-committee report (final),” IEEE P802.15.-02/490rl-SG3a,
2003.
[20] A. Saleh and R. Valenzuela, “A statistical model for indoor multipath propagation,” IEEE
Journal on Selected Areas in Communications, vol. 5, no. 2, pp. 128–137, Feb. 1987.
Authors
Ayman Khalil received the M.Sc in Networking and Telecommunications from the Lebanese
University/Saint Joseph University, Beirut, Lebanon in 2007. Actually, he is working on a Ph.D.
study in the Institute of Electronics and Telecommunications of Rennes (IETR), Rennes, France.
His research interests lie in wireless communication systems, and particularly focus on topics
related to all aspects of PHY layer, MAC layer and cross-layer designs. He is involved in the
European OMGA project and his main contribution focuses on studies and proposals holding
solutions for the cross-layer resource allocation and spectrum sharing matters for the next
generation home networks.
Matthieu Crussiere received the M.Sc. and Ph.D. degrees in electrical engineering from the National
Institute of Applied Sciences (INSA), France, in 2002 and 2005, respectively. During its Ph.D.
he was with the Electronics and Telecommunications Institute of Rennes (IETR), where he
worked on the optimization of high-bit rate powerline communications. Since 2005, he has been
an Associate Professor in the Department of Telecommunications and Electronic Engineering at
INSA and currently leads its research activities at IETR. His main research interests lie in digital
communications and signal processing techniques, and particularly focus on multi-carrier
spread-spectrum systems, synchronization, channel estimation, and adaptive resource allocation.
He has been involved in several European and national research projects including powerline
communications, broadcasting systems, ultra wideband and mobile radio communications.
Professor Jean-François Hélard received his Dipl.-Ing. and his Ph.D in electronics and signal
processing from the National Institute of Applied Sciences (INSA) in Rennes, France, in 1981
and 1992, respectively. From 1982 to 1997, he was research engineer and then head of channel
coding for the digital broadcasting research group at CCETT (France Telecom Research Center)
in Rennes. In 1997, he joined INSA, where he is currently Professor and Deputy Director of the
Rennes Institute for Electronics and Telecommunications (IETR), created in 2002 in association
with the CNRS. His research interests lie in signal processing techniques for digital
communications, such as space-time and channel coding, multi-carrier modulation, as well as
spread-spectrum and multiuser communications. He is involved in several European and national
research projects in the fields of digital video terrestrial broadcasting, mobile radio
communications and cellular networks, power-line and ultra-wide-band communications. Prof.
J-F. Hélard is a senior member of IEEE, author and co-author of more than 130 technical papers
in international scientific journals and conferences, and holds 13 European patents.