A distributed power control and mode selection algorithm for D2D communications

Norbert Reider,Gabor Fodor

doi:10.1186/1687-1499-2012-266

Abstract

Device-to-device (D2D) communications underlaying a cellular infrastructure has recently been proposed as a means of increasing the resource utilization, improving the user throughput and extending the battery lifetime of user equipments. In this article we propose a new distributed power control algorithm that iteratively determines the signal-to-noise-and-interference-ratio (SINR) targets in a mixed cellular and D2D environment and allocates transmit powers such that the overall power consumption is minimized subject to a sum-rate constraint. The performance of the distributed power control algorithm is benchmarked with respect to the optimal SINR target setting that we obtain using the Augmented Lagrangian Penalty Function method. The proposed scheme shows consistently near optimum performance both in a single-input-multiple-output and a multiple-input-multiple-output setting. We also propose a joint power control and mode selection algorithm that requires single cell information only and clearly outperforms the classical cellular mode operation.

Highlights

Device-to-device (D2D) communications in cellular spectrum supported by a cellular infrastructure holds the promise of three types of gains
As UE1 moves from its cell center position towards the cell edge, the average sum power required to reach their respective SINR targets gradually increases both when the D2D pair communicates in D2D mode and when they communicate in cellular mode
Recall that in cellular mode, we first assume that only UE1 transmits and only UE2 transmits to the AP

Summary

Introduction

Device-to-device (D2D) communications in cellular spectrum supported by a cellular infrastructure holds the promise of three types of gains. We would like to express the sum transmit power as a closed form function of the SINR targets To this end, the following result from [36] will be useful: by assuming equal power allocation for all streams s (i.e. no uplink beam forming, Tk = INt ∀k), the minimum stream SINR at Receiver-k (a cellular access point or a D2D receiver) is lower bounded as min s∈[1,Nt. Here, μmax(·) is the maximum eigenvalue operator for a Hermitian matrix, while k,j,1 and k,j,2 are defined as k,j,1 =. It should rely only on large scale fading information; It should allow for setting a minimum link quality (SINR target) value; It should reward the transmitters whose transmit power increase yields high capacity increase This requirement is justified by the intuition (confirmed and illustrated in the numerical section) that higher SINR targets should be granted to links with low pass

Objective function

Calculate current sum capacity as

Cellular mode

Conclusions