Research On Imitial Ranging Detection Algorithm For WiMAX

With the rapid development of mobile communication, high-speedis one of the objectives that the people pursued.Now,2G and 3G mobile communication systems can provide users with data transmission services, but its capacity is limited, still not satisfied static user with the real-time high-speed data transmission applications. Based on IEEE 802.16 protocol standard Working Group has made a global Interoperability for Microwave Access (WiMAX). "Initial Ranging Process" is one of the important proceses in the uplink WiMAX OFDMA physical layer. The process achieves adjusting power, estimating time and synchronization between all subscriber stations and base stations in a cell initially, which performance determines whether user can quickly access systems and synchronously communicate or no.Therefore, the research of initial ranging process has a very important practical significance.This paper firstly from the WiMAX technical background, briefly introduces the basic theory of ranging process, such as the ranging code ceneration and classification, ranging symbolic structure, ranging access processes. Secondly, the existing research of initial Ranging detection algorithm results on their main properties are summarized and compared.This paper focuses on these two aspects of detection algorithm and super long coverage in the multi-antenna system. First of all, a method for improving initial Ranging detection algorithm is proposed from the traditional algorithm in multi-antenna systems. Without increasing the calculation this algorithm uses to detect the value of user timeoffset, indirect judges the antennas communication situation, and then uses the corresponding methods to detect. Theoretical analysis and simulation result indicate that this algorithm has a better detection performance in the AWGN and ITUPB3 channel. The algorithm maximizes the use of multi-antenna diversity gain, simultaneously improves efficiency and detection performance, and effectively inhibits the multi-path fading.Secondly, for the time-frequency domain detection algorithm in the super long coverage can not eliminate the phase ambiguity, it proposes a time-frequency domain detection algorithm-the initial ranging ultra-long coverage detection algorithm in multi-antenna systems. The algorithm not only effectively reduces the calculation, but also resolved to the phase ambiguity problem caused by super long coverage, the realization of the super much. Theoretical analysis and simulation results show that in AWGN channel, regardless of the single-user respectively access or multiple users simultaneously access, the algorithm has the benefits as low complexity, high detection rate, and can accurately estimate the time value.