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Kumar, R.
- An Improved Spectrum Sensing for Cognitive Radio Networks with Rayleigh Fading Channel
Authors
1 SRM University, Chennai, IN
Source
Wireless Communication, Vol 3, No 9 (2011), Pagination: 630-634Abstract
Cognitive radio devices will be able to sense and dynamically use frequency bands for network access. This will be done by autonomous detection of unoccupied bands in the radio spectrum. Several factors like fading and shadowing affects the ability of the cognitive radio to detect the primary user. The current research shows that cooperation among the cognitive users can increase the detection probability for a given probability of false alarm. Previous research work shows that, the probability of detection is achieved maximum of 0.9 in AWGN channel. In this paper, we propose a new method for capacity maximization by minimizing probability of signal outage. And also increases the probability of detection by increasing sensing time for Rayleigh fading channel. Simulation results show promising performance results of the proposed technique are increased probability of detection and considerably maximizing the channel capacity.Keywords
Cooperative, Energy Detection, Outage Probability and Rayleigh Fading.
- Improvement of TCP Throughput in Wireless Networks with High Delay Round-Trip Time
Authors
1 Department of IT, Sri Ramkrishna Institute of Technology, Coimbatore 10, Tamilnadu, IN
2 Department of MCA, Sri Ramkrishna Institute of Technology, Coimbatore - 10. Tamilnadu, IN
Source
Wireless Communication, Vol 2, No 3 (2010), Pagination: 61-65Abstract
Highly variable round-trip times (RTTs) in wireless networks can induce spurious timeouts, thus unnecessarily degrading throughput for the Transmission Control Protocol (TCP). In this paper, we propose and study two effective ways to improve TCP throughput in wireless networks. The first technique is to select a retransmission timeout (RTO) threshold higher than that in the de facto standard. Simulation reveals that the proposed method reduces timeouts and provides a relative throughput gain up to 13.7% based on RTT measurements in a commercial 3G network and in a simulated network environment. The second technique is an appropriate use of selective repeat (SR) and go-back-N (GBN) as retransmission policies upon packet timeout. We find that when RTTs have reasonable temporal correlation and packets can arrive out-of-order at the receiver, GBN can improve throughput over the SR policy. Specifically, based on the RTT measurements in the 3G network, our results show that GBN provides a 12% throughput gain over the SR policy.
Keywords
End-To-End Performance, Split TCP, TCP, Timeout, Throughput, Wireless Networks.- Capacity Comparison of WCDMA Network for Different Coding Scheme
Authors
1 ECE department of Rajiv Gandhi College of Engineering and Technology, Pondicherry, IN
2 Department of Electronics and Communication Engineering, SRM University, Chennai, IN
Source
Wireless Communication, Vol 2, No 2 (2010), Pagination: 41-46Abstract
The wide-band code division multiple access (WCDMA) based 3G and beyond cellular mobile wireless networks are expected to provide a diverse range of multimedia services to mobile users with guaranteed quality of service (QoS). To serve diverse quality of service requirements of these networks it necessitates new radio resource management strategies for effective utilization of network resources with coding schemes. Call admission control (CAC) is a significant component in wireless networks to guarantee quality of service requirements and also to enhance the network resilience. In this paper capacity enhancement for WCDMA network with convolution coding scheme is discussed and compared with Block code and without coding scheme to achieve a better balance between resource utilization and quality of service provisioning. The model of this network is valid for the real-time (RT) and non-real-time (NRT) calls having different data rate. Simulation results demonstrate the effectiveness of the network using convolutional code in terms of capacity enhancement and QoS of the voice and data services.