Channel Status Based Transmission Performance Improvement Of Wireless Network

Unlike wireline based network,besides media access control,routing policy and congestion control,the key challenge to improve transmission performance of wire-less network is to deal with the time-variant wireless channel status,like fading and interference,across physical-layer included multiple layers.In this paper,we focus on promoting the transmission performance of single-hop wireless network consisting of one AP and multiple terminals based on channel status by minimizing the average delay of unicast and increasing the broadcast throughput.The main contribution of this paper includes the following two parts:For unicast,during the scenario where terminals can choose the channel with least fading and interference,we investigate the minimization problem of average delay of multi-antenna AP based SIMO(single-input and multiple-output)system by optimizing the antenna allocation.We first obtain the upper bound of transmission bandwidth by deriving the expected error probability of coherent detection for SIMO under Rayleigh fading,and then develop the expression of average delay of terminals sharing the same channel via contention by applying CTMC(continuous-time Markov chains).Upon above results,we formulate the optimization of antenna allocation as a non-linear in-teger programming problem and present a polynomial time algorithm based on integer partition and minimum matching to support optimized allocation.We prove the cor-rectness of our theoretical derived results by extensive simulations.The performance comparison results show that the proposed antenna allocation algorithm outperforms other heuristic based algorithms under different traffic models.For broadcast,towards the scenario where heterogeneous spatially separated inter-ference sources exist and available spectrum of terminals is fragmented,we propose a communication scheme that jointly exploits multiple narrow band communication,channel-hopping based narrow channel scheduling and Reed-Solomon erasure code to boost the throughput.This communication scheme is referred as Channel-Hopped Network-Coded Multiple Narrow Band Communication(CHNC-MNBC).We then de-rive the closed-form expression of the expected broadcast throughput of CHNC-MNBC and another two conventional communication schemes,i.e.,Network-Coded Multiple Narrow Band Communication(channel-hopping disabled,denoted as NC-MNBC)and Network-Coded Broad Band Communication(channel-partition disabled,denoted as NC-BBC)in general scenarios.We further show,by theoretical analysis,that the broad-cast throughtput gain of CHNC-MNBC and NC-BBC is at least[N/(N-n)]M-1 and an arbitrarily large number,respectively,when at each of M terminals,at least n of the total N narrow channels are obstructed by severe interference.Finally,via simula-tion experiment,we show the superiority of CHNC-MNBC and verify our theoretical calculation and analysis.