Tom Walingo

Energy analysis for the distributed receiver-based cooperative medium access control for wireless sensor networks

This paper presents the energy analysis of a new energy-efficient distributed receiver-based cooperative medium access control (MAC) scheme for wireless sensor networks. The cooperative MAC scheme developed herein incorporates cooperation, overhearing avoidance, receiver-based relay node selection and a Markov-based channel state estimation onto the standard IEEE 802.15.4 scheme. The solution is developed based on a receiver oriented approach when selecting cooperative relay nodes and using a store and forward scheme to relay the packets to the destination node. This works’ main focus is in combining the cooperative packet relaying with overhearing avoidance in order to reduce node energy consumption hence enhancing the network lifetime. As the performance criteria, the energy consumed per node is investigated against packet arrival rate and average signal-to-noise ratio. The percentage of energy consumed and packet throughput are also investigated as the proposed MAC scheme is compared against the standard IEEE 802.15.4 MAC over the estimated channel conditions. The results show that the proposed MAC scheme with cooperation and overhearing avoidance resulted in both improved performance and improved energy saving patterns.

Performance Analysis of Correlated Handover Service in LEO Mobile Satellite Systems

Analytical models for low earth orbit mobile satellite systems (LEO-MSSs) should consider service time correlation in adjacent satellite spot beams. This letter presents a simple analytical framework for the efficient performance evaluation of new and handover services in LEO-MSSs with correlated service times. When the fading channel is temporally correlated, channel characteristics in the preceding and succeeding spot beams do not change dramatically, especially for services with short transmission times. A closed-form solution of the correlated queue service time is derived using probability generating functions whose moments are used to derive the blocking probabilities of handover and new services. The system is then modeled as a queuing system with correlated service time and its performance investigated.

Performance Analysis of a Connection Admission Scheme for Future Networks

Future networks are to deliver any-traffic, anytime, anywhere with full quality of service (QoS) guarantees. They will evolve from typical heterogeneous networks (HetNets) into dense, organic, and irregular heterogeneous networks called DenseNets. They will be complex and face additional challenges of heterogeneity in many design dimensions like different radio access technologies (RATs) shrinking in structure. Radio Resource Management (RRM) is one of the key challenges in providing for QoS for these networks. Connection Admission Control (CAC) scheme and intelligent scheduling techniques are employed on the links for RRM. In this paper a CAC scheme is developed that features multiple traffic classes, multiple admission parameters at both packet and connection level. The CAC scheme uses both signal to interference ratio (SIR) and delay as admission parameters since the single parameter based CAC algorithm is not adequate for the emerging traffic classes. The performance analysis of the model features Batch Markovian Arrival Process (BMAP) traffic, a better representative of the future traffic characteristics than the traditional Poisson traffic. A simple approximate Markovian analytical model is developed and used to analyze the complex network. The developed model with more admission parameters outperforms those with less admission control parameters for future networks traffic.

Energy Efficient Distributed Receiver Based Cooperative MAC for wireless sensor networks

This article presents a new Energy Efficient Distributed Receiver Based Cooperative Medium Access Control protocol for wireless sensor networks (E2DRCMAC for WSNs). WSNs employ cooperative diversity techniques in order to improve network lifetime and overall network reliability. The proposed MAC scheme focuses on cooperation with overhearing avoidance and reducing transmissions in case of link failures in order to minimize energy consumption in the network to improve the network lifetime. This article also presents an analytical model for the packet delay to show the improved performance when cooperation is introduced as revealed by the simulation results. The findings presented in this article include percentage energy used in the network, throughput, packet delay, and packet delivery ratio.

Relay selection cooperative diversity in Land Mobile Satellite Systems

In recent times, the cooperative diversity concept has been a major research area as it promises improvement in communication with little complexity and resource demands. In this work, the cooperative diversity concept is investigated in Land Mobile Satellite Systems (LMSS). Using a two-state statistical LMSS satellite model, the algorithm seeks to choose a best relay with highest received signal strength to cooperate with the destination terminal. This receiver-based cooperation is also carried out incrementally, that is, only when the direct communication is insufficient to guarantee good communication is cooperation employed. This helps to save resources even more as less spectrum bandwidth and relay power would be utilized. The following performance criteria were considered; Average Output Signal to Noise Ratio (SNR), Outage Probability, Average Bit Error Rate and Average Channel Capacity for the cooperative Satellite system. The results show that for LMSS, cooperative communication performs better than direct communication alone, irrespective of the environment so considered.

Call Admission Control for Weather-Impacted Multimedia Satellite Networks

This paper proposes a call admission control (CAC) policy for multimedia satellite networks that are susceptible to service degradation due to rain attenuation. Based on noncooperative Game theory, the proposed CAC seeks to ensure quality of service (QoS) satisfaction for all real time (RT) and non-real time (NRT) connections that are accepted into the satellite network. In its decision, the CAC considers the effect of adaptive modulation and coding (AMC) employed to mitigate the effects of the rain attenuation experienced during a connections lifetime. A prediction scheme that predicts the rain attenuation on the link for successive intervals of time within the duration of a connection is also proposed. The performance of the CAC policy is investigated for different prediction intervals and the results show that the CAC policy is suitable to provide QoS satisfaction for traffic of multimedia connections in satellite networks.

Optimal fusion techniques for cooperative spectrum sensing in cognitive radio networks

Cooperative Spectrum Sensing (CSS) is a critical component in cognitive radio networks (CRN). It is a scheme used to opportunistically scan the spectrum by multiple CR devices to make collaborative decisions on the presence or absence of the Primary User (PU). It improves the performance on spectrum utilization by exploring the spatial diversity of the cognitive radio networks. Both the selection criterion of cooperating secondary users (SUs) and the fusion schemes used for CSS affect the detection probabilities of the PU. This paper investigates the performance of AND, majority and OR rule fusion techniques. The performance based on an optimal number of collaborating SUs in majority fusion rule is considered and comparison made against OR and AND rules. The optimal number of SUs collaborating in sensing is investigated using Newton Raphson Method. The performance results indicate that majority fusion rule has better detection capability, low total error probability as compared to the OR and AND rules at low SNR.

TCP over wireless with differentiated services

The focus of this paper is to analyze the throughput performance of TCP Tahoe and Reno on a differentiated services network with correlated wireless losses. An analytical model of TCP on a wireless link with differentiated services (DiffServ) based on the packet train model is developed. The network model is based on the state dependent arrival process. A major contribution of this paper is an analytical model combining the performance of TCP throughput and DiffServ leading to a model that represents an almost complete network scenario. It is shown that DiffServ in a wireless channel with correlated error losses is possible if the probability of the channel changing from a good state to a bad state is less than a particular value. It is also shown that TCP Reno has a higher sensitivity to DiffServ than Tahoe. Our analytical model is validated through a number of simulations.

Energy Efficient Medium Access Control and Routing Protocol For Multihop Wireless Sensor Networks

This work presents a combined energy-efficient medium access control (MAC) and routing protocol for large-scale wireless sensor networks that aims to minimise energy consumption and prolong the network lifetime. The proposed communication framework employs the following measures to enhance the network energy efficiency. Firstly, it provides an adaptive intra-cluster schedule to arbitrate media access of sensor nodes within a cluster, minimising idle listening on sensor nodes, leading to improved energy performance. Secondly, it proposes an on-demand source cross-layer routing protocol ensuring selection of best routes based on energy level and channel quality indicator for the multihop inter-cluster data transmission. Lastly, an unequal cluster size technique based on cluster head residual energy and distance away from the base station is utilised. This technique balances the energy among clusters and avoids early network partitioning. This work further presents the analytical performance model for energy consumption and delay of the proposed communication framework. The performance measures used for evaluation are energy consumption, delay, and network lifetime. The results indicate that combining routing and MAC schemes conserves energy better than utilising MAC scheme alone.

Energy Efficient Coverage Extension Relay Node Placement in LTE-A Networks

Deployed long term evolution-advanced (LTE-A) infrastructure may need coverage extension due to the exponential growth of mobile broadband data usages as well as poor network performance along the cell edges. A proper installation of relay nodes (RN) extends the network coverage in LTE-A networks. We propose an energy efficient and optimal RN placement (EEORNP) algorithm that maximizes the network coverage under the energy constraint, while maintaining the signal-to-interference ratio. The algorithm is based on an improved greedy algorithm, where an effective and optimal RN placement is guaranteed when the matroid rank function of the energy efficient coverage extension optimization is sub-modular and monotonic. The performance is investigated in terms of coverage percentage and number of RN needed to cover users. Results show that the proposed EEORNP outperforms both greedy and random placement algorithms.