GPS synchronization method for mobile wireless networks

1. A system for GPS (Geographical Positioning System) synchronization of a femtocell, as defined in the application, in a wireless telecommunications network, the system comprising:

a dedicated Base Transceiver Station (a “sync-BTS”) for transmitting synchronization signals;

a GPS receiver coupled to said sync-BTS;

at least one femtocell; and

a processor in each said femtocell for performing time and frequency synchronization on said sync-BTS over an air interface;

wherein said sync-BTS further includes a transmitter for transmitting pilot tones for tracking synchronization; and

each said femtocell includes a decoder for decoding said pilot tones to correct timing and frequency offset in said femtocells.

2. The system according to claim 1 , wherein said sync-BTS is integrated in a macro-base station.

3. The system according to claim 2 , further comprising utilizing Space Time Coding (STC) in a transmitter of the sync-BTS and implementing an MRC (Maximum Ratio Combining) technique in said femtocell receiver.

4. The system according to claim 1 , wherein said sync-BTS transmits on a same frequency as a collocated macro-base station.

5. The system according to claim 1 , wherein said sync-BTS transmits on a different frequency from a collocated macro-base station.

6. The system according to claim 1 , wherein a transmission frame of said sync-BTS includes a dedicated time zone and sub-channel slot for transmitting said pilot tones.

7. A system for GPS (Geographical Positioning System) synchronization of a femtocell, as defined in the application, in a wireless telecommunications network, the system comprising:

a dedicated Base Transceiver Station (a “sync-BTS”) for transmitting synchronization signals;

a GPS receiver coupled to said sync-BTS;

at least one femtocell;

a processor in each said femtocell for performing time and frequency synchronization on said sync-BTS over an air interface;

further comprising utilizing Space Time Coding (STC) in a transmitter of the sync-BTS and implementing an MRC (Maximum Ratio Combining) technique in said femtocell receiver.

8. A method for GPS synchronization of a femtocell, as defined in the application, in a wireless telecommunications network, the method comprising:

coupling a module for GPS synchronization to a dedicated Base Transceiver Station (a “sync-BTS”) arranged for transmitting synchronization signals;

transmitting synchronization signals from said sync-BTS including transmitting a sync-BTS preamble;

performing synchronization on said sync-BTS over an air interface by at least one femtocell, including performing preamble synchronization with said sync-BTS for initial acquisition; and

wherein said preamble synchronization includes:

Time Domain (TD) Preamble Detection, estimating a preamble time of arrival and a fractional Carrier Frequency Offset (CFO) between the femtocell and said sync-BTS;

fractionally correcting CFO and correcting symbol timing; and

Frequency Domain (FD) Preamble Detection, implemented after Fast Fourier Transform processing, performing a Cell Search, Integer CFO and AP Power estimation.

9. The method according to claim 8 ,

wherein said step of transmitting further includes transmitting pilot tones;

and further comprising tracking of frequency, timing and start of frame of said sync-BTS, by said femtocell, by means of said pilot tones.

10. The method according to claim 9 , wherein said step of tracking includes:

allocating a slot in a sync zone of a femtocell transmission frame for clock time information, based on said pilot tones transmitted by said sync-BTS; and

causing said femtocell to track the pilot tones and correct the femtocell's internal clock.

11. The method according to claim 9 , wherein said step of tracking includes repeating said preamble synchronization, at given intervals.

12. The method according to claim 8 , wherein said step of transmitting includes transmitting over a femtocell network channel frequency.

13. The method according to claim 8 , wherein said step of transmitting includes transmitting said pilot tones on a dedicated time zone and sub-channel slot in a transmission frame.

14. The method according to claim 13 , further comprising encoding management channel signals in said sub-channel together with said pilot tones.

15. The method according to claim 14 , further comprising:

utilizing STC (Space Time Coding) when transmitting by said sync-BTS; and

implementing a MRC (Maximum Ratio Combining) technique in said femtocell when receiving.