Dynamic spectrum access through Cognitive Radio Networks (CRNs) and exploiting multiple radios on a single node are two different well accepted techniques for enhancing network performance. Simultaneous usage of both the techniques, i.e., augmenting dynamic spectrum access with multiple radios can improve delay, however, makes throughput worse. Therefore, in this study, we propose a novel approach to improve network throughput for multi-radio cognitive radio networks. Through ns-3 simulation, we show that our approach can boost throughput without degrading the delay.
Poster: Overcoming Throughput Degradation in Multi-Radio Cognitive Radio Networks
by Tanvir Ahmed Khan and A. B. M. Alim Al Islam
In Proceedings of MobiSys Companion, Singapore, 2016.
In this study, we consider coexisting primary and secondary users cooperate with each other to improve their performance. In our system model, primary users' performance is defined regarding throughput and end to end delay while secondary users' objected is described concerning transmission opportunities and enery consumption. Based on these goals, we propose a multi-hop distributed routing protocol for primary and secondary users. In the proposed routing protocol, secondary users relay primary user packets in exchange of accessing primary user channels. We implemented the routing protocol in ns-3 and analyzed the performance regarding network throughput, end-to-end delay, and packet drop ratio.
A Multi-hop Cooperation based Routing Protocol in Cognitive Radio Networks
by Chowdhury Sayeed Hyder, Tanvir Ahmed Khan and Li Xiao
under review for possible publication in IEEE Transactions on Cognitive Communications and Networking (TCCN), 2016. [TCCN-TPS-16-0068.R1]
In this study, our objective was to reduce the delay CR users experience due to channel sensing, reporting, and negotiation. The main problem of reducing the delay is that we can not reduce any one of these individual components. Therefore, to reduce the delay we had to look at the bigger picture. Our ns-2 simulation results showed us that even though CR users experience these three delays, their delay performance mainly gets degraded due to sudden unavailability of their currently used communication medium. What happens is that when they lost their currently used channel, they have to start the whole process of channel reservation. And this results in longer delay. Therefore, to reduce the delay, we needed to decrease this overhead due to channel switching. We tried to mitigate this overhead by exploiting multiple radios for each user. Our basic intuition was that if we can supply the user with an already negotiated channel when it needs one after losing the previous one, we will be able to reduce the delay. Consequently, we mathematically modeled this multi-radio, multi-channel system with an M/G/k queue and simulated it in ns-2.
Towards exploiting a synergy between cognitive and multi-radio networking
by Tanvir Ahmed Khan, Chowdhury Sayeed Hyder, and A. B. M. Alim Al Islam
In Proceedings of WiMob, Abu Dhabi, UAE, 2015.