Optimal precoder designs for sum rate maximization in MIMO multiuser multicells

Kha Hoang Ha,Long Dinh Nguyen,Tuan Hong Do

doi:10.32508/stdj.v18i3.890

Abstract

This paper is concerned with the joint linear precoder design problem for the multiuser multiple-input multiple-output (MIMO) heterogeneous networks (HetNets) in which multiple femto base stations (FBSs) coexist with a macro base station (MBS). To tackle the inter-user interference in the macrocell, we exploit the blockdiagonalization scheme and then use the convex optimization to maximize the sum rate of the macrocell. The FBS transmission strategy is to maximize the sum-rate of femtocells subject to the transmitted power constraints per FBS and restrictions on the cross-tier interference to macro-users (MUs). Such a design problem is typically nonconvex, and, thus, challenging to find the FBS precoders. We reformulate the design problem of the FBS precoders as a d.c. (difference of convex functions) programming, and develop an efficient iterative algorithm to obtain the optimal precoders. Numerical simulation results show that the proposed algorithm outperforms the other methods in terms of the total sum-rate of the HetNet.

Highlights

Heterogeneous networks (HetNets) have recently become a major research topic in wireless communications due to its great potential to improve the coverage and capacity of wireless networks [1], [2]
Due to the scarce frequency resource, the femto base stations (FBSs) share the same frequency spectrum with the macro base station (MBS), the cochannel cells result in crosstier interference from the marocell to femtocells and from femtocells to macrocell [2], [6]
Each MBS or FBS is equipped with Mk =

Summary

Introduction

Heterogeneous networks (HetNets) have recently become a major research topic in wireless communications due to its great potential to improve the coverage and capacity of wireless networks [1], [2]. In Long Term Evolution (LTE) Advanced HetNets, micro, pico, and femto cells with low power base stations and short range of coverage can be placed in different locations to improve the spectral efficiency since these cells operate in the licensed spectrum of the macrocell and provide the high quality of service (QoS) for nearby users [1], [3]–[5]. Due to the scarce frequency resource, the femto base stations (FBSs) share the same frequency spectrum with the macro base station (MBS), the cochannel cells result in crosstier interference from the marocell to femtocells and from femtocells to macrocell [2], [6]. A key challenge for successful deployment of HetNets is how efficiently to handle intra-tier and cross-tier interference

Objectives

Methods

Results

Conclusion