Power-Efficient System Design for Cellular-Based Machine-to-Machine Communications

TL;DR

This paper develops a systematic framework for power-efficient system design in cellular M2M communications, focusing on optimal transmission strategies, power control, and load support, considering the unique characteristics of M2M traffic and devices.

Contribution

It derives optimal power and load support results for various transmission strategies, providing practical design guidelines for energy-efficient M2M cellular networks.

Findings

FDMA is sum-power optimal at low spectral efficiency.

Uncoordinated CDMA performs nearly as well under light load.

Optimization within FDMA offers limited gains in the M2M regime.

Abstract

The growing popularity of Machine-to-Machine (M2M) communications in cellular networks is driving the need to optimize networks based on the characteristics of M2M, which are significantly different from the requirements that current networks are designed to meet. First, M2M requires large number of short sessions as opposed to small number of long lived sessions required by the human generated traffic. Second, M2M constitutes a number of battery operated devices that are static in locations such as basements and tunnels, and need to transmit at elevated powers compared to the traditional devices. Third, replacing or recharging batteries of such devices may not be feasible. All these differences highlight the importance of a systematic framework to study the power and energy optimal system design in the regime of interest for M2M, which is the main focus of this paper. For a variety of coordinated and uncoordinated transmission strategies, we derive results for the optimal transmit power, energy per bit, and the maximum load supported by the base station, leading to the following design guidelines: (i) frequency division multiple access (FDMA), including equal bandwidth allocation, is sum-power optimal in the asymptotically low spectral efficiency regime, (ii) while FDMA is the best practical strategy overall, uncoordinated code division multiple access (CDMA) is almost as good when the base station is lightly loaded, (iii) the value of optimization within FDMA is in general not significant in the regime of interest for M2M.