OFDM-Based Broadband Wireless Networks: Design and Optimization

Chapter 7

Multi-Cell Frequency Planning

7.1 Introduction

The techniques described in previous chapters focus on a single-cell scenario with the assumption that the base station transmits/receives on one set of frequency bands. From a system level perspective, the same set of frequency bands can be reused by multiple base stations, as long as they are physically separated far enough to tolerate the mutual interference. The base stations that use the same frequency band give rise to co-channel interference. An important design factor for a cellular system is to coordinate the co-channel interference and make intelligent radio resource allocation over all base stations. The allocation of frequencies to the cellular system is termed frequency reuse or frequency planning which has a profound impact on system performance [1].

Generally speaking, existing frequency planning schemes can be classified into three categories: static/fixed frequency channel allocation (FCA), adaptive/dynamic channel allocation (DCA) and hybrid channel allocation (HCA). The hybrid channel allocation can be regarded as the combination of FCA and DCA, where some of the channels are fixed for each cell and others are dynamically assigned to cells/users [2] [3].

This chapter first provides an overview of the frequency planning schemes for cellular networks. As will be explained shortly, challenges remain when applying the existing schemes to OFDM systems. A frequency planning scheme based on dynamic channel allocation ...