Collision Resolution With FM0 Signal Separation for Short-Range Random Multi-Access Wireless Network

In internet of things, a central node to multiple sensor nodes is usually a short-range communication network, which generally uses random multiple access to resolve collision at a media access control (MAC) layer. In this case, the communication efficiency is not optimal. On the other hand, its efficiency can be improved in separated collision resolution, where collision signals can be separated and then decoded. For the resolution, good coding techniques can improve the performance of collision resolution. However, the conventional coding techniques usually need the signal fading coefficient estimated or be known in advance. The condition is not always satisfied in the short-range network. This paper proposes a finite-symbol separation Viterbi decoder (FSVD) which does not need to know the fading coefficient. Through the estimation of a dictionary matrix, the uncertainty of signal separation can be eliminated, and thus obtain more accurate likelihood distances and improve the decoding accuracy. In experiments, we establish two ultra-high frequency (UHF) short-range wireless networks based on an FM0 code, using a simulation and a software radio platform, respectively. The experimental results show that the throughput of FSVD reaches about 0.61, which is about 0.25 higher than that of a traditional ALOHA network.