Enhanced Random Access: Initial Access Load Balance in Highly Dense LTE-A Networks for Multiservice Traffic

The Random Access (RA) procedure in cellular networks is not capable of functioning properly during high access load conditions. For this purpose, overload control mechanisms are needed. Most proposed mechanisms in the literature offer a tradeoff between the allowed access rate and experienced delay. However, when the maximal tolerated delay and the energy spent on retransmissions are tightly bounded, the very high access rate targeted for 5G systems cannot be achieved. For these situations, we propose the Delay Estimation based RA (DERA)-scheme that has the potential to meet very stringent reliability requirements, even in high access load conditions. The present work shows that this can be achieved with only limited additional complexity. Furthermore, we also study at which access-rate to move from a low-load to a high-load regime. This tool can also be used along with other proposed RA overload control schemes, e.g. when to invoke access class barring. The performance evaluation results show that the novel DERA scheme can significantly improve the control channels' resource utilization along with the success rate in dense deployment scenarios.