Descending synchronous calibrating method and apparatus for TD-SCDMA system

Abstract

The invention provides a downlink synchronous calibration method and device in a TD-SCDMA system. The method comprises the steps of: receiving a downlink signal; searching for a downlink synchronization code (SYNC_DL) in the received downlink signal to control synchronization timing; using the midamble code of the received signal to calculate a channel impulse response to adjust the synchronization timing; Obtain the channel impulse response or channel complex correlation corresponding to the DwPTS channel; search for the third predetermined path with the strongest energy as the candidate position of the left boundary of the energy window; obtain the energy in the third predetermined path with the strongest energy greater than the specified The path of the predetermined threshold is a survival path, wherein the predetermined threshold is a function of the largest path among the third predetermined number of paths with the strongest energy; obtaining the position of the leftmost path in the survival path is the window Left boundary to obtain an adjustment amount for synchronization timing calibration; further adjust and / or calibrate the synchronization timing. The device includes: a receiving device; a searching device; a control computing device; an adjusting device. By using the invention, the performance of the system is effectively improved.

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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