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CDMA system access channel frequency deviation estimating method

A technology of access channel and code division multiple access, which is applied in the direction of code division multiplexing system, transmission system, multiplexing communication, etc. Effect of incoming message demodulation performance loss on

Inactive Publication Date: 2010-02-10
ZTE CORP
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Problems solved by technology

[0004] The technical problem to be solved by the present invention is: the problem of rough frequency offset compensation accuracy in the access message demodulation process

Method used

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  • CDMA system access channel frequency deviation estimating method
  • CDMA system access channel frequency deviation estimating method
  • CDMA system access channel frequency deviation estimating method

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Embodiment Construction

[0021] The first step: Carry out theoretical analysis to obtain the functional relationship DeltaF(Arate, FStep) between the leading amplitude (or energy) ratio Arate and "dF1-signal real frequency offset Foffset" of two different preset frequency offsets dF1 and dF2 , where FStep=dF2-dF1, which satisfies

[0022] Foffset=dF1-DeltaF(Arate, dF2-dF1);

[0023] If multiple preset frequency offsets are required and the same FStep is used in the calculation, DeltaF(Arate, FStep) can be transformed into a one-dimensional function DeltaF(Arate). For example, four frequency offsets are set at equal intervals, and the demodulation amplitude ratios obtained from adjacent frequency offsets are used for calculation.

[0024] This step can be done during system design.

[0025] Step 2: During the access process, preset n (n is greater than or equal to 2) different frequency offset compensation values ​​dF1, dF2, ..., dFn-1, dFn for preamble demodulation, and obtain the preamble amplitude...

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Abstract

The invention discloses a method for evaluating frequency deviation when code division multiple access systems switch in communication channels. The inventive method comprises the steps of: (1) duringthe process of switching in, using preset different frequency deviation compensation values dF1, dF2,..., dFn-1, dFn to leading modulation and getting different leading amplitude A(dF1), A(dF2),...,and A(dFn-1), A(dFn)during compensating, wherein n>=2; (2) calculating the ratio of the amplitude values get from step (1) Aratei=A(dFi) / A(dFi+1), wherein i=1...n-1; (3) according to the ratio of leading modulation amplitude and the differential value of preset frequency deviation FStepi function DeltaF and the ith frequency deviation compensation value dFi, getting the (n-1)th frequency deviation; (4) getting the evaluating frequency deviation value by averaging; (5) making frequency deviation compensation to switched-in messages.

Description

technical field [0001] The invention relates to the technical field of communication, in particular to the estimation of the frequency offset of an access channel in a code division multiple access wireless communication system. Background technique [0002] In the code division multiple access wireless communication system, due to the difference in the accuracy of the radio frequency local oscillator and the influence of the Doppler effect when moving, there is a certain deviation between the carrier center frequency of the signal received by the base station and the frequency of the radio frequency local oscillator of the base station. This frequency deviation sometimes amounts to more than 1000 hertz (Hz), and is usually in the range of plus or minus 1500 Hz. If this frequency deviation (referred to as frequency deviation) is not compensated, the demodulation performance will be greatly degraded. For this reason, we need to estimate how much this frequency offset is, and...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04J13/00H04B1/12H04L25/02H04L25/03
Inventor 丁杰伟
Owner ZTE CORP
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