Dynamic Power Control Based on FFR for D2D
Communication Underlaying Cellular Networks
Fan Jiang
†,‡
, Xian-chao Wang
†
, Chen-bi Li
†
, Bin-yan Shen
†
†
School of Communications and Information Engineering,
Xian University of Posts and Telecommunications, Xi’an, 710121, P.R.China
‡
Department of Computer Science and Engineering, University of South Florida, Tampa, FL, USA
Abstract—By reuse the resource of existing cellular users, D2D
(Device-to-Device) communication underlaying cellular network
can improve the spectrum utilization rate and reduce the power
consumption of mobile terminals. However, it will also bring
interference to the existing cellular network. How to effectively
restrain the interference caused by resource reuse has become the
most important factor that affects the performance of multi-cell
networks. In order to ensure the quality of service of D2D users
and cellular users, this paper studies the power control and
resource allocation scheme for D2D communication underlaying
cellular communications. Specifically, based on multi-cell cellular
network architecture, fractional frequency reuse is introduced to
achieve resource partitioning and resource reuse between cellular
users and D2D users. Based on the principle of maximizing the
throughput of the whole system, the optimization objective is then
established. Combined with the fractional power control and with
the introduction of interference limits, we use the Lagrangian
dual decomposition to solve the optimization objectives, and
propose a dynamic power control strategy. Simulation results
show that compared with the existing algorithms, the proposed
scheme improves the performance of the overall system.
Keywords—Device-to-Device communication; Interference
coordination; Fractional frequency reuse; Fractional power
control
I. INTRODUCTION
In recent years, with the popularity of high-performance
intelligent terminals and the emergence of new mobile
multimedia services, the contradiction between the growing
service demands of users and the limited network bandwidth
capacity has become increasingly prominent. It is difficult to
provide high-quality and large-capacity multimedia services
through the existing cellular systems [1-2]. By allowing
mobile devices to transmit data with local peer-to-peer links,
such device-to-device (D2D) communications [3-4] can offer a
variety of advantages over the traditional cellular
communications in terms of higher throughput, improved
spectrum efficiency, and extended network coverage. However,
due to resource sharing, the interference between the cellular
network and D2D layer brings great challenges to the wireless
resource management.
In order to mitigate the co-channel interference caused by
D2D frequency reuse, there have been a lot of researches and
the investigations about resource allocation methods and
power control strategies. Among these studies, [5] proposes
an individual optimization (IO) resource allocation scheme,
which focuses on minimizing the interference of individuals,
but ignores the overall interference. [6] presents an overall
optimization (OO) resource allocation scheme based on the
Hungarian Method, which minimizes the overall interference
caused by the D2D user equipments (DUEs) underlaying with
the cellular user equipments (CUEs). However, one of the
limitations of the above schemes is that it cannot be easily
extended to the multi-cell environment. In order to reduce the
inter-cell interference in a multi-cell environment, [7] extends
the work of [6], which applies both Fractional Frequency
Reuse (FFR) and Fractional Power Control (FPC) for D2D
communication underlying cellular networks. The proposed
scheme can effectively reduce the interference between
different cells, but the transmit power of CUEs are fixed
which lacks flexibility. A joint admission control, mode
selection and power allocation in D2D communication
systems is proposed in [8]. Instead of conventional exhaustive
searching, the authors proposed an approximation approach to
obtain the suboptimal result.
Based on the existing contributions, this paper first
concentrates on resource partition and resource allocation
method with the introduction of FFR. Then, by incorporating
FPC into DUEs and CUEs, we propose a dynamic power
control (DPC) strategy, which aims at minimizing the
interference caused by D2D underlaying. By transforming the
non-convex object function into a convex function, we then
use the Lagrange dual decomposition method [9] to solve the
optimal power allocation problem.
The remainder of this article is organized as follows: In
Section II we present the system model. In Section III a
dynamic power control strategy is proposed. Section IV
presents the numerical results and analysis. The conclusion is
drawn in section V.
II. SYSTEM MODEL AND PROBLEM FORMULATION
A. System Model
The paper considers a multi-cell model which contains
seven hexagon cells. We assume that CUEs and DUEs are
randomly distributed in each cell. Orthogonal frequency
division multiple (ODFM) is applied so that there is no intra-
cell interference among CUEs. DUEs are assumed to adopt
underlying mode which means DUEs reuse uplink cellular
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