Neighbor Discovery In Mobile Wireless Networks

In mobile wireless networks,the emerging proximity-based applications have led to the need for the capability of neighbor discovery on smart devices.Till now,most existing works focus on designing effective and energy-efficient neighbor discovery protocols.However,these works cannot realize the optimal worst-case latency in symmetric case,and their performance with asymmetric duty cycles can still be improved.More importantly,they have to rely on the simple beacon-decoding mechanism,which ignores the rich interference in mobile wireless communication media,and thus,only realizes the theoretical performance in the scenario without strong interference.In this work,we aim at both the efficiency and the robustness of neighbor discovery.We first investigate asynchronous neighbor discovery through a code-based approach,including the symmetric and asymmetric cases.We derive the tight worst-case latency bound in the case of symmetric duty cycle.We design a novel class of symmetric patterns called Diff-Codes,which is optimal when the Diff-Code can be extended from a perfect difference set.We also consider the asymmetric case,and design ADiffCodes.Furthermore,we exploit the cross-correlation property of pseudo-random sequences,and propose ReCorder to eliminate the necessity of beacon decoding in existing neighbor discovery protocols.In ReCorder,a neighbor discovery message can be detected through cross-correlation on an RCover preamble,and contains a ReCord identity signature,which is unique for each of the nodes.Algorithms for RCover detection and ReCord recognition are designed,as well.To evaluate(A)Diff-Codes and ReCorder,we conduct both simulations and testbed experiments.On one hand,both simulation and experiment results show that(A)Diff-Codes significantly outperform existing neighbor discovery protocols in both median case and worst-case.Specifically,in the symmetric case,the maximum worst-case improvement is up to 50%;in both symmetric and asymmetric cases,the median case gain is as high as 30%.On the other hand,ReCorder is proven to achieve robust neighbor discovery at an SINR lower than the existing beaconing and decoding based neighbor discovery protocols by almost 10 dB.Furthermore,ReCorder can avoid degrading the decoding of background IEEE 802.11a/g transmissions with BPSK modulation,which is important for its co-existence with concurrent wireless streams.