Mobile terminal and uplink channel local frequency regulation method

Abstract

A adjusting method for a local oscillating frequency of uplink path of a mobile terminal includes: after finishing adjusting the local oscillating frequency fr of downlink path, the mobile terminal sets the control parameters of the local oscillating frequency according to the requirement that ft is adjusted to 2f0-fr, when the mobile terminal adjusts the local oscillating frequency ft of uplink path. The control parameters of the local oscillating frequency include a control voltage of the frequency reference source of the local oscillating circuit and a frequency multiplying value of the local oscillating circuit, wherein f0 is the carrier frequency of the base station when the signal sending on current working channel has no frequency shift. A mobile terminal includes a local oscillating circuit and its frequency reference source, a storing module, a downlink adjusting module, a searching module and an uplink adjusting module. The method can respectively adjusts the carrier frequencies of the receiving and transmitting paths of the mobile terminal according to the mobile state so as to cancel the influence of the Doppler frequency shift and reduce the multiple access interference among the uplink users.

Description

technical field [0001] The invention relates to a mobile communication system terminal, namely a mobile terminal, in particular to a mobile terminal and a method for adjusting the local oscillator frequency of an uplink channel thereof. Background technique [0002] Existing mobile communication terminals, that is, mobile terminals, usually include a local oscillator circuit (local oscillator, LO for short), which is used to generate a local frequency reference signal, also called a local oscillator signal. The electromagnetic wave signal is received by the antenna from the air and sent to the low-noise amplifier, and then sent to the mixer together with the frequency reference signal generated by the local oscillator circuit. The mixer uses the local oscillator signal to down-convert the received RF signal. Then the down-converted signal is sent to a subsequent processing unit to complete receiving information. Sending information is processed in the same way as receiving ...

AI Technical Summary

Problems solved by technology

In the TD-LTE communication system, the uplink multiple access scheme adopts Orthogonal Frequency Division Multiple Access (OFDMA for short), and the interval between each subcarrier is generally 12Khz~15Khz. If 15Khz is used, Then the 0.8Khz Doppler frequency shift will cause serious inter-carrier interference for a single user, and will also cause multiple access interference for different users on the receiving side of the base station, reducing system capacity and increasing bit error rate.

In a special multiple access communication system such as OFDMA, the problems caused by Doppler frequency offset on the base station side cannot be handled by the base station, because the signals sent by many users that should be isolated on the frequency band are due to the Doppler frequency shift. And after moving and superimposing each other and arriving at the base station, the base station has no way to distinguish

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