[Show abstract][Hide abstract] ABSTRACT: In cognitive radio networks (CRNs), TCP goodput is one of the key issues to measure it's performance. However, most existing research efforts on TCP performance improvement have two weaknesses as follows: first of all, most of them only consider the underlying parameters to optimize the physical performance, the TCP performance have been neglected; Second, they are largely formulated as a Markov Decision Process (MDP), which requires a complete knowledge of network and cannot be directly applied to distributed CRNs. To solve the above problems, a Q-BMDP algorithm is proposed in this paper: Each user in CRN autonomously decides modulation type and transmitting power in PHY, channels to access in MAC to find the best TCP goodput. Due to the existence of perception error of environment, this issue is formulated as a Partial Observable Markov Decision Process (POMDP) which is then converted to belief state MDP, with Q-value iteration to find the optimal strategy. Simulation results show that the network can learn optimal strategy to effectively improve TCP goodput in dynamic wireless network.
Engineering and Technology (S-CET), 2012 Spring Congress on; 05/2012
[Show abstract][Hide abstract] ABSTRACT: Scarcity problem of radio spectrum resource stimulates the research on cognitive radio technology, in which dynamic spectrum allocation attracts lots of attention. For higher access efficiency in cognitive radio context, we suggest a fully dynamic access scheme for primary and secondary users, which is modeled by a master-slave stochastic knapsack process. Equilibrium behavior of this knapsack model is analyzed: expressions of blocking probability of both master and slave classes are derived as performance criterion, as well as forced termination probability for the slave class. All the theoretic results are verified by numeric simulations. Compared to traditional opportunistic spectrum access (OSA), which can be regarded as half dynamic due to primary users’ rough preemption, our scheme leads to less termination events for the secondary users while keeping the same performance for the primary class, thus promotes the system access performance. Nonideal spectrum sensing algorithm with detection error is also taken into consideration to evaluate its impact on system access performance, which is a practical issue for implementation.
Mobile Networks and Applications 17(6). · 1.11 Impact Factor
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