Optimized Code-Expanded Random Access Procedure for Massive Internet of Things

Optimal code-expanded random access (OptCeRA) is a promising random access (RA) technique for supporting massive Internet of Things (MIoT) in mobile networks. It allows devices to employ, as contention resources, codewords formed by the transmission of preambles in consecutive RA slots and selected from a maximum average distance code. This paper introduces the adaptive version of the OptCeRA scheme to cope with substantial random access channel (RACH) demands, which is particularly relevant for supporting MIoT scenarios in such networks. A practical algorithm to dynamically adjust the OptCeRA scheme parameters to the RA channel load based on optimizing the RA success probability is proposed. Numerical results show that the proposal significantly increases the capacity of the networks in terms of the number of simultaneous random access attempts compared to the state-of-the-art RA schemes.