Coverage Enhancement by CDMA Code Sectoring in Hybrid Terrestrial/Satellite Point-to-Multipoint Networks

Interference reduction techniques in wireless point-to-multipoint (PIMP) networks are considered in this paper, utilizing code-division multiple access (CDMA) and hybrid terrestrial/satellite access. Downlink code sectoring approaches are introduced combined with multiuser detection. Full network coverage is achieved by assigning satellite access to critical interference zones. The aim of our proposed network architecture is providing the largest possible terrestrial coverage so that satellite access can be focused only on the most critical zones. Interference zone analyses are obtained by bit error rate (BER) simulations

I Introduction

The widespreadof wireless alternatives of broadband wired access services is foreseen in the upcoming years. Wireless alternatives of copper and fibre based transmission must meet tough quality of service (QoS) requirements besides providing flexible and cost-effective installation. Broadband wireless access point-to-multipoint (PMP) networks are represented by standards such as WiMax, BFWA and LMDS [1]. Microwave terrestrial PMP networks may suffer from insufficient capacity due to poor radio transmission environment or increased interference level. Our former investigations aim at reducing interference in terrestrial PMP radio networks. The application of CDMA with sophisticated receiver algorithms, i.e. multiuser detection is investigated on uplink and downlink in [2] and [3], respectively; combined code sectoring and antenna-sectoring improvement strategies are discussed in [4] and [5].