Locality-Sensitive Hashing for Efficient Rendezvous Search: A New Approach

The multichannel rendezvous problem is a fundamental problem for neighbor discovery in many IoT applications. The existing works in the literature focus mostly on improving the worst-case performance, and the average-case performance is often not as good as that of the random algorithm. As IoT devices (users) are close to each other, their available channel sets, though they might be different, are similar. Using the locality-sensitive hashing (LSH) technique in data mining, we propose channel hopping algorithms that exploit the similarity between the two available channel sets to increase the rendezvous probability. For the synchronous setting, our algorithms have the expected time-to-rendezvous (ETTR) inversely proportional to a well-known similarity measure called the Jaccard index. For the asynchronous setting, we use dimensionality reduction to speed up the rendezvous process. Furthermore, we combine our LSH approach with the Asynchronous Channel Hopping sequence with Maximum rendezvous diversity (MACH) to ensure an upper bound of maximum time-to-rendezvous (MTTR). Our numerical results show that our algorithms can outperform the random algorithm in terms of ETTR.