Lead code sending method and cell searching method for OFDM system

Abstract

The present invention provides a method for transmitting lead code of an orthogonal frequency division multiplexing system and a corresponding cell searching method, wherein the transmitting method comprises the following procedures: transmitting lead code comprising system synchronizing information to a terminal, the lead code comprises main front lead code and auxiliary lead code; modulating the main front lead code on useful subcarrier with fixed bandwidth which is a least bandwidth in the bandwidths used by each coexisting system; transmitting corresponding type of auxiliary lead code by the base station according to the system used in the base station; putting the main lead code in a first orthogonal frequency division multiplexing symbol of each sub-frame and putting the auxiliary lead code in a second orthogonal frequency division multiplexing symbol of each sub-frame by the base station; wherein the main lead code carries the information indicating the style of auxiliary lead code. The method according to the invention causes that the systems with different bandwidths are compatible and that the 802.16m system and 802.16e system are compatible. The terminals with different bandwidths can work to the system with different bandwidth and the access speed of terminal can be increased.

Description

technical field [0001] The invention relates to the field of digital communication, in particular to a preamble sending method and a cell search method of an orthogonal frequency division multiplexing system. Background technique [0002] As a multi-carrier transmission mode, OFDM (Orthogonal Frequency Division Multiplex) converts a high-speed transmission data stream into a set of low-speed parallel transmission data streams, making the system frequency-selective to multipath fading channels The sensitivity of OFDM is greatly reduced, and the introduction of cyclic prefix further enhances the ability of the system to resist Inter-symbol Interference (ISI). In addition, the high bandwidth utilization rate and simple implementation make OFDM in wireless communication Watersheds are widely used, for example, WLAN systems, IEEE 802.16e systems based on OFDM multiple access (802.16e for short), and IEEE 802.16m systems (fourth generation communication systems) that are the next ...

AI Technical Summary

Problems solved by technology

[0005] According to the 802.16e standard: the preamble is sent on the entire bandwidth of the first symbol of the downlink. At the same time, 802.16e systems with different bandwidths (such as 5MHz, 10MHz, and 20MHz) use different preambles. In order to access the system, the terminal needs very A large amount of calculation, and it is difficult for terminals with different bandwidths to work under systems with different bandwidths, so the existing technology brings problems of complex implementation and long access time

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