Estimation and Adaptation for Bursty L T E Random Access
Abstract: With the potential to generate numerous connection requests, an explosive growth in the volume of data traffic and the number of mobile and machine-tomachine devices has drawn new attention to the radio access network. Surging random-access attempts cause not only severe preamble collisions but downlink resource shortage as well, thus degrading the performance of the random-access procedure. However, the effect of downlink resource shortage on system performance has yet to be comprehensively studied. In addition, most existing random-access contention resolution mechanisms sacrifice random-access channel (RACH) throughput for a high success probability, and thus, the price is that low-throughput mechanisms need a lot of time to deal with access attempts. In this paper, we evaluate the medium-access-control (MAC)-level performance for the four-step random-access procedure in Long-Term Evolution (LTE) systems, both with and without constrained downlink resources. Furthermore, we propose a novel RACH contention resolution scheme, i.e., the dynamic backoff (DB) scheme. DB can achieve high RACH throughput, yielding a high random-access success probability under various RACH overloaded scenarios.