Method and device for synchronizing mobile radio receivers in a mobile radio system
First Claim
1. A method of synchronizing mobile CDMA radio receivers in a cellular CDMA mobile radio system, wherein a first synchronization channel with a first frequency is provided for transmitting a synchronization signal with a code that is known to the mobile radio receivers and to base stations of the mobile radio system, and wherein a transmission from a base station to a mobile radio receiver delays the synchronization signal by an unknown time period and the first frequency is shifted by the transmission to a second frequency, the method which comprises the following steps:
- splitting the received synchronization signal into a real part signal and an imaginary part signal;
sampling the real part signal and the imaginary part signal to form sampled signals;
digitally filtering each sampled signal to correlate the sampled signal to the known code and to form filtered signals;
squaring each filtered signal to form squared signals;
determining a maximum signal level from the squared signals;
estimating the unknown time period with the maximum signal level determined in the determining step;
despreading the received synchronization signal with the known code and taking into account the time period estimated in the estimating step;
determining a frequency deviation between the first frequency and the second frequency based on the despread received synchronization signal; and
fine-tuning the second frequency to the first frequency based in part on the despread received synchronization signal.
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Accused Products
Abstract
Mobile radio receivers in a mobile radio system are synchronized. A first synchronization channel is provided, which has a first frequency and via which a code which is known to all the mobile radio receivers and to all the base stations of the mobile radio system is transmitted with a signal. The transmission from a base station to a mobile radio receiver delays the signal by an unknown time period and the first frequency is displaced by the transmission to a second frequency. The method includes a correlation and sampling of the received signal, digital filtering of the correlated and sampled signal, squaring of the filtered signal, determination of the maximum signal level of the squared signal, estimation of the unknown time period with the maximum signal level, despreading of the received signal with the known code, taking into account the just-estimated time period, and fine-tuning of the second frequency to the first frequency.
25 Citations
12 Claims
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1. A method of synchronizing mobile CDMA radio receivers in a cellular CDMA mobile radio system, wherein a first synchronization channel with a first frequency is provided for transmitting a synchronization signal with a code that is known to the mobile radio receivers and to base stations of the mobile radio system, and wherein a transmission from a base station to a mobile radio receiver delays the synchronization signal by an unknown time period and the first frequency is shifted by the transmission to a second frequency, the method which comprises the following steps:
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splitting the received synchronization signal into a real part signal and an imaginary part signal;
sampling the real part signal and the imaginary part signal to form sampled signals;
digitally filtering each sampled signal to correlate the sampled signal to the known code and to form filtered signals;
squaring each filtered signal to form squared signals;
determining a maximum signal level from the squared signals;
estimating the unknown time period with the maximum signal level determined in the determining step;
despreading the received synchronization signal with the known code and taking into account the time period estimated in the estimating step;
determining a frequency deviation between the first frequency and the second frequency based on the despread received synchronization signal; and
fine-tuning the second frequency to the first frequency based in part on the despread received synchronization signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification