Improving of data secondary frequency synchronous in cellular mobile equipment
A mobile station and reference frequency technology, which is applied in the direction of synchronization devices, digital transmission systems, electrical components, etc., can solve problems such as difficulty in complying with the lower bound of 0.1ppm and slow convergence
Inactive Publication Date: 2003-10-01
SIEMENS INFORMATION & COMM NEWTWORKS INC
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It can be concluded that in the new UMTS environment, under the realistic assumptions adopted in the simulation, the studied methods of the prior art hardly obey the lower bound of 0.1ppm, and in any case, the convergence is too slow
A reasonable approach for improving asymptotic accuracy might be to reduce the correction step of the frequency offset estimate, which is especially useful in noisy environments, but doing so still requires many iterations to achieve the desired accuracy
As far as the TD-SCDMA system is concerned, the noted deficiencies of the known methods have a rather general character and have also been demonstrated for other standards
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[0050] refer to Image 6 , reproduces a functional block diagram of a UE receiver suitable for performing the frequency synchronization method of the present invention. Although reference to the described architecture of TD-SCDMA is common, reference may also be made to a GSM type UE receiver except for some details (ie: SPRq, SYNC). For completeness, in Image 6 The channel is also simulated in , as seen at the receive antenna. In the channel model of interest, s(t) represents the transmitted signal, c(t) is the channel fading process (ie: Rayleigh fading), and n(t) is used to model thermal noise and multi-user interference (cell within and between communities). At the input of the UE receiver, the received signal r(t) is visible, which reaches the front-end FR-END block comprising a bandpass RF filter and a low noise receive amplifier (both invisible). At the output of the front end, the RF signal is down-converted to baseband frequency by the DOWNCONV box, which include...
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Some improvements to the traditional algorithms used for digital assisted frequency correction in cellular systems are introduced into various standards, namely: 3GPP CDMA-TDMA, 3.84Mcps FDD mode, 3.84Mcps TDD mode, 1.28Mcps TDD mode, CWTS TD-CDMA, GSM / DCS / GPRS, in the new method implemented by the user equipment. The method starts by obtaining the suboptimal frequency error Δ⌋i using a known formula that calculates the arguments of the autocorrelation function for a subset of baseband samples of the detected training sequence. This error Δi is stored into an L-bit long shift register and averaged to obtain an estimated frequency error Δi for recursively correcting the reference frequency of the local oscillator as i-1=i-1 +k△i, where K(0 K 1) is the weighting factor. Contrary to the simple average error of the prior art, only the terms with the most frequently occurring algebraic sign within the stored terms Δ∆i are averaged by using a sign criterion.
Description
technical field [0001] The present invention relates to the field of frequency synchronization, and in particular to some improvements to data-assisted frequency synchronization in cellular mobile equipment. Background technique [0002] Precise frequency synchronization is an essential process performed by mobile stations in order to meet stringent specification requirements, eg 0.1ppm. Calibration of the local oscillator is allowed immediately after the initial cell search which occurs at power-on. The initial cell search is a procedure which depends to some extent on the characteristics of the PLMN (Public Land Mobile Network) involved, but in any case the initial cell search consists of a frequency scan of the allocated bandwidth and in order to detect The synchronization sequence detection is performed on the target cell, and the synchronization sequence is allocated on a cell-by-cell basis. At the end of the initial cell search, the target cell's carrier frequency is...
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IPC IPC(8): H04L27/00H04L27/233
CPCH04L27/0014H04L27/233H04L2027/0028H04L2027/0057H04L2027/0095
Inventor 亚历山德罗·文图拉
Owner SIEMENS INFORMATION & COMM NEWTWORKS INC