Preamble Reuse for Massive Machine-Type Communications in LTE Networks

Massive Machine-Type Communications using LTE networks is the focus of this work aimed at realization of future Internet of Things (IoT) paradigm. Random Access Channel is the bottleneck in random access procedure which is designed for low-rate HTC connections. In MTC, when there are a large number of devices, congestion occurs in Random Access Channel. Access Class Barring (ACB) and preamble slicing are two main approaches proposed to control RACH congestion. These schemes have limited improvements over the base approach. In this paper, we propose a complementary approach that can be used in conjunction with these methods. Our approach is based on the concept of local relays and spatial preamble reuse. Assuming random selection of preambles by the devices, we developed a heuristic to select a set of local relays to act as an aggregator node for random access requests of the devices in its vicinity. The relays perform random access procedure on behalf of their members to eNodeB. The simulations show that using RACH relays reduces preamble collisions and hence is a promising technique to scale and move up the random access success rate.