Towards Green Wireless Networking: Fading-Resistant Time Constraint Broadcasts Using Cooperative Communication

Cooperative broadcast, in which receivers are allowed to combine received packets from different senders to combat transmission errors, has gained increasing attention. Previous studies showed that broadcast optimization solutions are sufficient in non-fading environments but may suffer a low delivery ratio under wireless channel fading. Although some previous works analyze the tradeoff between energy and delay in cooperative broadcast, no work has investigated the tradeoff in a fading environment. Thus, in this paper, we study this tradeoff with the consideration of different fading models (i.e., Rayleigh fading, Rician fading, and Weibull fading models). We formulate this problem as a Fading-resistant Delay-constrained Minimum Energy Cooperative Broadcast (FDMECB) problem and prove the problem to be NP-hard under the Rayleigh fading, Rician fading, and Weibull fading models. We then identify an approximation algorithm for theoretical interests and propose a time efficient heuristic algorithm for practical use. Furthermore, we propose a dynamic programming (DP) based algorithm, which can achieve global optimization of FDMECB given the ordering of nodes to be informed. Our experimental results show that both FREEB and DP algorithms outperform a previous non-fading resistant algorithm, and also, DP nearly achieves the optimal.