Method and device for determining the carrier frequency of base stations in the mobile receiver of a cellular mobile radio system working with W-CDMA
View Patent ↗The method and device enable determining the carrier frequency of base stations in the mobile receiver of a cellular mobile radio system working with W-CDMA. The carrier frequency of the primary synchronization channel of the strongest received base station is first searched for by carrying out a non-coherent correlation of the received signal with the primary synchronization code over a very large number of code elements of the signal.
1. A method of determining a carrier frequency of base stations in a mobile receiver of a cellular mobile radio system working with W-CDMA, the method which comprises first searching for the carrier frequency of a primary synchronization channel and a time synchronization of the base stations by carrying out a non-coherent correlation of an in-phase component and quadrature component of a received signal with a primary synchronization code over a very large number of chips of the signal, searching for the primary synchronization channel in progressively less coarse frequency steps, by measuring an energy of the correlation result at intervals of a first frequency range in each case, then selecting a band having the highest energy and measuring at intervals of a second frequency range being smaller than the first frequency range in each case, then selecting a band having the highest energy and measuring at intervals of a third frequency range being smaller than the second frequency range in each case, and selecting a value having the highest energy as a hypothesis for the receiver carrier frequency.
2. The method according to claim 1 , which comprises obtaining a time synchronization of a strongest received base station modulo a slot length by determining a maximum value of peaks in the output signal of the correlation.
3. The method according to claim 1 , which comprises carrying out the correlation over 2560 chips of the signal.
4. The method according to claim 1 , which comprises, after the carrier frequency of the primary synchronization channel and the time synchronization of the strongest received base station have been determined, determining a frame synchronization and a code group of the base station by way of a secondary synchronization channel.
5. A device for determining the carrier frequency of base stations for the mobile receiver of the cellular mobile radio system working with W-CDMA according to the method of claim 1 , which comprises at least one search device having a device for demodulating a physical common primary control channel, a device for correlating various path delays, a device for identifying a scrambling code, a device for determining a time frame synchronization, and a device for estimating signal delay.
6. The device according to claim 5 , wherein said at least one search device is one of two search devices.
7. A device for determining the carrier frequency of base stations for the mobile receiver of the cellular mobile radio system working with W-CDMA according to the method of claim 1 , which comprises at least one search device having means for demodulating a physical common primary control channel, means for correlating various path delays, means for identifying a scrambling code, means for determining a time frame synchronization, and means for estimating the signal delay.
8. The method according to claim 1 , wherein the first frequency range is approximately 1 MHz, the second frequency range is approximately 100 kHz, and the third frequency range is approximately 10 kHz.