Descending synchronous calibrating method and apparatus for TD-SCDMA system

Abstract

This invention provides a down stream synchronous calibration method in TD-SCDMA system and its device. It includes following steps: receiving down stream signal. Looking up the down stream SYNC_DL to control the synchronous timing; using the midamble code of the above received signal to calculate the channel impulse response to regulate the synchronous timing; getting the channel impulse response and multiple correlation corresponding to DwPTS channel; getting the left edge of the channel impulse response to get the amount for regulating the synchronous timing calibration; further regulating and calibrating the synchronous timing. The device comprises: receiving device ; looking up device; control and calculation device; regulating device.

Description

technical field [0001] The invention relates to mobile communication, in particular to a downlink synchronization calibration method and device in a TD-SCDMA system. Background technique [0002] In spread spectrum communication, before the receiver starts to demodulate the received signal, it first needs to ensure that the locally generated pseudo-random code (PN) sequence is completely synchronized with the PN sequence of the received signal. Usually, the synchronized PN is obtained through two stages of acquisition and tracking. sequence. In the acquisition phase, the rough synchronization of the PN code sequence is obtained, so that the phase difference of the PN sequence between the transceivers is less than a certain threshold, which is determined by the acquisition band of the timing tracking unit, which is usually half a chip wide in the actual system time. [0003] The initial synchronization of the CDMA communication system receiver includes PN code synchronizati...

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Problems solved by technology

[0011] The existing synchronization adjustment scheme of the TD-SCDMA system, through the two steps of coarse synchronization adjustment and fine synchronization adjustment, can indeed obtain good synchronization performance under certain circumstances, but it is limited by the characteristics of midamble codes, as mentioned above , in the case of other than the Common allocation method of midamble codes, the channel impulse response calculated by midamble codes actually includes the channel impulse responses of multiple channels and multiple users. When we cannot compare these different channels or different users When strictly distinguishing the channel impulse response of , the synchronization performance of this method will be affected to a certain extent, so in order to overcome this problem, we must find a way to solve the problem outside the Midamble code

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