GPS SYNCHRONIZATION METHOD FOR WIRELESS CELLULAR NETWORKS

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

a Base Transceiver Station (a “sync-BTS”) coupled to a GPS receiver; and

at least one femtocell including a processor for performing time and frequency synchronization on said sync-BTS over an air interface.

2 . The system according to claim 1 ,

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 identify and correct timing and frequency offset in said femtocells.

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

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 , further comprising a plurality of femtocells coupled for communication to said sync-BTS, each femtocell including a processor for preamble synchronization with said sync-BTS for initial acquisition.

7 . The system according to claim 1 , 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 . The system according to claim 2 , wherein a transmission frame of said sync-BTS includes a dedicated zone consisting of two symbols on a single sub-channel slot for transmitting said pilot tones.

9 . The system according to claim 1 , wherein said sync-BTS includes said GPS receiver.

10 . A method for GPS synchronization of a femtocell in a wireless telecommunications network, the femtocell being coupled to a core network via wired backhaul, the method comprising:

transmitting synchronization signals from a Base Transceiver Station (a “sync-BTS”) coupled to a GPS receiver; and

performing synchronization on said sync-BTS over an air interface in at least one femtocell.

11 . The method according to claim 10 , wherein said step of transmitting includes transmitting a sync-BTS preamble, and said step of performing includes performing preamble synchronization with said sync-BTS for initial acquisition.

12 . The method according to claim 11 , 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.

13 . The method according to claim 11 ,

wherein said step of transmitting further includes transmitting pilot tones;

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

14 . The method according to claim 13 , wherein said step of tracking includes repeating said preamble synchronization, at given intervals.

15 . The method according to claim 13 , 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.

16 . The method according to claim 10 , wherein said step of transmitting includes transmitting over a femtocell network channel frequency.

17 . The method according to claim 10 , wherein said step of transmitting includes transmitting said pilot tones on a dedicated zone in a transmission frame consisting of two symbols on a single sub-channel slot.

18 . The method according to claim 17 , further comprising encoding management channel signals in said sub-channel together with said pilot tones.

19 . The method according to claim 18 , 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.