Assessment of LTE Wireless Access for Monitoring of Energy Distribution in the Smart Grid

TL;DR

This paper evaluates LTE's suitability for smart grid monitoring, revealing that signaling constraints limit capacity and proposing a lightweight access method and an analytical model to improve M2M communication efficiency.

Contribution

It provides a detailed simulation of LTE access limitations for M2M traffic and introduces an analytical model to predict outage, highlighting the need for reduced signaling in standardization.

Findings

Increasing random access opportunities can worsen performance.

Signaling overhead significantly reduces device capacity.

A lightweight access method could enhance LTE for M2M applications.

Abstract

While LTE is becoming widely rolled out for human-type services, it is also a promising solution for cost-efficient connectivity of the smart grid monitoring equipment. This is a type of machine-to-machine (M2M) traffic that consists mainly of sporadic uplink transmissions. In such a setting, the amount of traffic that can be served in a cell is not constrained by the data capacity, but rather by the signaling constraints in the random access channel and control channel. In this paper we explore these limitations using a detailed simulation of the LTE access reservation protocol (ARP). We find that 1) assigning more random access opportunities may actually worsen performance; and 2) the additional signaling that follows the ARP has very large impact on the capacity in terms of the number of supported devices; we observed a reduction in the capacity by almost a factor of 3. This suggests that a lightweight access method, with a reduced number of signaling messages, needs to be considered in standardization for M2M applications. Additionally we propose a tractable analytical model to calculate the outage that can be rapidly implemented and evaluated. The model accounts for the features of the random access, control channel and uplink and downlink data channels, as well as retransmissions.