Energy efficient path selection scheme for OFDMA-based two-hop cellular systems

Abstract

In this paper, we proposed new path selection for two-hop cellular systems called energy efficient path selection (EEPS) scheme to enhance downlink system throughput and reduce transmission energy consumption. In the EEPS scheme, a base station determines either a single-hop or two-hop path that uses less energy consumption. The simulation results show that the EEPS scheme outperforms a conventional path selection scheme which uses high signal to interference and noise ratio (SINR) strength based path selection in terms of system throughput and energy consumption. Also, we suggest the appropriate relay station position and optimal resource allocation for access and relay communications.

Introduction

Cellular multihop networks have been proposed as an attractive solution for next generation wireless communication since they enhance throughput and/or extend cell coverage using multihop relay stations (RSs) [1], [2], [3], [4], [5], [6], [7]. In cellular multihop networks, however, the resource management and path selection schemes are considerably more complex than those of conventional cellular systems because a base station (BS) shares its wireless resource with RSs and determines the optimal path for connecting with mobile stations (MSs). In [8], an optimal path selection scheme between single-hop and two-hop services was proposed in a cellular multihop network for highway deployment, where the BS and RSs were deployed along the road as roadside units. The proposed scheme in [8] outperformed other schemes in terms of system throughput but the proposed scheme can be used only for the highway environment. In [9], a path selection scheme for cellular multihop networks was introduced using a cost metric that indicated the effectiveness of the radio resource of a link for data transmission and a non-transparent frame structure that is described in [6]. In the simulation, a BS and several RSs were randomly deployed in a cell, and the BS chose paths to MSs through single- or multi-hop using the cost metric. However, the authors assumed the BS knows all link qualities of multi-hop paths to MSs and ignored interference and frequency reuse.

In this paper, we propose a new path selection for two-hop cellular systems called energy efficient path selection (EEPS) scheme to enhance downlink (DL) system throughput and reduce transmission energy consumption in two-hop cellular networks with two-dimensional topology based on orthogonal frequency division multiple access (OFDMA) and time division duplex (TDD). The key idea of the EEPS scheme is that the BS chooses the paths to MSs using the energy efficiency between single-hop and two-hop paths using channel quality information (CQI) and the modulation and coding scheme (MCS) option in a transparent environment. The simulation results show that the EEPS scheme outperforms a conventional path selection scheme which uses stronger signal to interference and noise ratio (SINR) for path selection in terms of system throughput and energy consumption. Also, we suggest the appropriate RS position and optimal resource allocation for access and relay communications.

Section 2 in describes the system topology and frame structure, SINR model in cellular multihop networks, Resource allocation and system capacity and Energy consumption for data transmission. Energy efficient path selection scheme will be explained in Section 3, and then Section 4 shows the performance evaluation and Section 5 summarizes conclusion.