Frequency correcting method and device

Abstract

The present invention provides frequency correction method and device. It contains Utilizing receiving all cell signal frequency offset estimation, uniform proceeding calibration to received carrier frequency, independent estimating each cell signal residual frequency offset, through feed forward frequency correction ensuring each cell signal demodulation and detection performance; also through coherence length shorter cell searching, fast selecting demodulation cell participate carrier frequency calibrating signal generation and residual frequency offset forward correcting, quick adjusting carrier frequency in switching or cell updating, to make it more approaching most strong service cell transmission frequency, ensuring metric switching or cell updating accuracy, reducing up-down going transmitted signal power, system interference; cell searching to obtain higher SNR cell, measuring CPICH signal intensity.

Description

technical field [0001] The invention relates to the field of wireless communication, in particular to a method and a device for correcting frequency offset by a mobile terminal in a communication network. Background technique [0002] In a wireless communication system, in order to ensure continuous coverage and reception of wireless propagation signals, a user terminal (UE) will communicate with different base stations at the same time, or select the best serving cell for communication through measurement and handover. [0003] For example, in a WCDMA system, if the UE maintains communication with the network while moving and is in the overlapping area covered by the signals of two base stations, the system will arrange for the UE to perform soft handover. The UE communicates with the two base stations simultaneously through two air interface channels, and the downlink signal Using different pseudo-random bit scrambling, the UE receives the two signals through RAKE processi...

AI Technical Summary

Problems solved by technology

[0015] 1. When only the radio frequency AFC comprehensively locks and receives all base stations to receive downlink signals, take the signal strength of the two base stations as an example. figure 1 The receiving carrier frequency f locked by the UE in 0 ' should be close to f 0 , for the received signals of base station 1 and base station 2 in the baseband data, there are f d The fixed frequency offset, the performance of coherent demodulation in the following link is degraded

[0016] 2. If the UE moves from receiving the signal of base station 1 to the handover area covered by the signals of two base stations, the radio frequency channel of the UE in technical solution 1 first locks the downlink frequency f of base station 1 0 -f d , the received signal of base station 2 in the baseband data has 2×f d The frequency offset of 303 link CPICH measurement performance declines, 305 link and 309 will not soon join the signal of base station 2 for demodulation and frequency calibration, only when the received signal power of base station 2 is stronger, it is possible to join the base station through 305 link 2 information, through the closed-loop adjustment of links 309, 310 and 301, the frequency is gradually locked to f 0 Left and right, due to the increase in power requirements and the delay in measurement, resulting in delays in handover and best cell update, the increase in uplink and downlink signal transmission power also leads to a decrease in system capacity

If the signal coverage strength is average, it may also cause the UE to handover unsuccessfully and cause the call to be dropped.

[0017] 3. Coherent demodulation can improve the detection performance. In the existing method, the 303 link performs CPICH measurement. Considering that the UE adapts to different wireless environments, the baseband data in the high-speed mobile environment may have a large frequency offset, which limits the choice of coherent length during measurement. Decreases measurement performance for applications in non-high-speed environments

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