A Study on Cell Search Algorithms for IEEE 802.16e OFDMA Systems

In this paper, the problem of cell search for IEEE 802.16e OFDMA systems is addressed, which includes two steps: frame detection and cell ID identification. We propose two novel frame detection algorithms: one is based on the pseudo-periodicity property of the preamble signal in time-domain (TD algorithm), and the other one is based on the Euclidean distance in frequency-domain (FD algorithm). In comparison with the FD algorithm, the TD algorithm is more robust to fading and interference, at the cost of a higher implementation complexity. Therefore, we should choose the suitable one based on different system reliability and complexity requirements. As for the cell ID identification procedure, an adaptive correlation length algorithm (ACL algorithm) is proposed, in which the necessary correlation length can be chosen without prior channel knowledge, and thereby greatly reduces the cell search time. The system simulation results show that the proposed frame detection and cell ID identification algorithms are robust and efficient for OFDMA cellular systems, especially for IEEE 802.16e OFDMA systems.

I. Introduction

The IEEE 802.16 WirelessMAN standard [1] provides MAC and PHY specifications for open air interface for fixed and portable broadband wireless access systems, which has now been updated and extended to the IEEE 802.16e [2] standard for mobile access below 6 GHz. The IEEE 802.16e standard defines three PHYs that can be used in conjunction with the MAC layer to provide a reliable end-to-end link. The three physical modes include WirelessMAN-SCa, WirelessMAN-OFDM and WirelessMAN-OFDMA. Among them, wirelessMAN-OFDMA is supposed to be the most promising one for its high spectral efficiency and capability of flexible resource allocation.