Study on Generalized Buffer-State-Based Relay Selection in Cooperative Cognitive Radio Networks

学位の種別: 修士University of Tokyo(東京大学

Buffer-aided relay selection with reduced packet delay in cooperative networks

Applying data buffers at relay nodes significantly improves the outage performance in relay networks, but the performance gain is often at the price of long packet delays. In this paper, a novel relay selection scheme with significantly reduced packet delay is proposed. The outage probability and average packet delay of the proposed scheme under different channel scenarios are analyzed. Simulation results are also given to verify the analysis. The analytical and simulation results show that, compared with non-buffer-aided relay selection schemes, the proposed scheme has not only significant gain in outage performance but also similar average packet delay when the channel signal-to-noise ratio (SNR) is high enough, making it an attractive scheme in practice

Buffer-aided 5G cooperative networks: Considering the source delay

© 2019 Association for Computing Machinery. Applying relays employed with data buffers drastically enhance the performance of cooperative networks. However, lengthening the packet delay is still a serious challenge for cooperative networks. This paper thoroughly studies a new factor affecting the packet delay which is the source delay. This factor plays a key role in calculating the total delay that messages encounter before reaching their destination. This delay is crucial especially in applications that require their messages to get transmitted as fast as possible. Markov chain is employed to model the system and analyze the source delay. Numerical simulations verify the analytical model, the results show that buffer-aided relays can beat non-buffer relays in terms of average packet delay, especially at low signal to noise ratio (SNR) range. This makes adding buffers to relays an attractive solution for the packet delay in 5G applications

Max-gain relay selection scheme for wireless networks

© 2020 Karabuk University Next generation wireless systems are supposed to handle high amount of data with broader coverage and high quality of service (QoS). When a signal travels from a source to destination, the signal quality may suffer from the fading, which makes it difficult to receive correct messages. To handle the impact of fading, various diversity techniques are performed with Multiple Input Multiple Output (MIMO). Considering cooperative wireless networks, virtual MIMOs are being used, which also called cooperative diversity. In this paper, we propose a max-gain relay selection scheme (MGRS) for buffer-aided wireless cooperative networks. This scheme determines the best link using the maximum gain based on quality of link and available buffer size. The time slot is divided into two parts, one is used to choose the best link from the source to relay transmission (odd slot) and another time slot (even) is used based on the selection of the best link from the relay to destination. Markov chain model is use to measure buffer status and QoS parameters to evaluate the performance. The proposed scheme provides better QoS (12%) compared to the existing relay selection schemes with respect to throughput, end-to-end delay and outage probability