Mitigating initial access congestion for dense smart meters deployment in LTE network

Abstract

Smart meter applications have been gaining huge importance due to its use in many appliances of citizen requirements. Wireless standards have been proposing requirements and protocols to support such applications of smart meters connectivity to networks through MTC (Machine Type Communication). One of the main requirements of smart meter applications is to have periodic reporting of meter readings to server without any human intervention. LTE (Long Term Evolution) network being the latest cellular technology with extended coverage becomes a preferred choice for supporting connectivity between smart meter device and network. After each data transfer to server, connection between transmission-device in smart meter and LTE network is terminated to allow device to move to power saving mode and hence initial access through RACH (Random Access Channel) is required every time for establishing connection to network before transmitting data to server. When such large number of initial access is attempted at the same time, it would increase the probability of collision among smart meter devices. This would further delay access to network and in turns increases the battery consumption due to retransmissions till initial access is successful. To overcome the above challenge of initial access congestion, we proposed a novel algorithm called Time Distributed Initial Access (TDIA), which group the smart meters and available preambles to distribute the start time of RACH transmissions in each group based on their IMSI (International Mobile Subscriber Identity). The major advantage of our TDIA algorithm is that each smart meter device could calculate its start time on its own without much overhead in network. The analytical model supported simulation results shows that our TDIA algorithm of uniformly distributing the initial access attempts increases the probability of successful preamble transmission to around 98% compared to 70% in Poisson distributed arrival process and 25% in Beta distributed arrival process in legacy 3GPP initial access schemes while considering 3000 initial access attempts at an average load of 20.