1. In a mobile wireless communications system, which includes base stations of a first type operating according to a first air interface, and base stations of a second type operating according to a second air interface, a method for handing over a mobile station in the system from a first base station, which is of the first type, to a second base station, which is of the second type, wherein one of the first and second air interfaces comprises a TDMA interface, and the other of the interfaces comprises a CDMA interface, comprising:

establishing a communications link over the first air interface between the mobile station and the first base station;

receiving data from the mobile station responsive to a signal received by the mobile station over the second air interface from the second base station, substantially without breaking the communications link with the first base station;

wherein receiving the data comprises applying a weighting factor to the measurement of signal strength; and handing over the mobile station from the first to the second base station, which is of a second type, wherein one of the first and second air interfaces comprises a TDMA interface, and the other of the interfaces comprises a CDMA interface.

2. A method according to claim 1, wherein receiving the data comprises receiving a measurement of signal strength, and wherein handing over the mobile station comprises comparing measurements of signal strength from the first and second base stations and handing over the mobile station responsive to the comparison.

3. A method according to claim 2, wherein applying a weighting factor comprises varying the factor according to a network condition in the system and/or transmitting a weighting factor over the communications link to the mobile station, which applies the weighting factor to the measurement.

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4. A method according to any of the preceeding claims, wherein receiving the data comprises receiving an identification of the second base station based on decoding by the mobile station of the signal received over the second air interface.

5. A method according to claim 1, and comprising transmitting from the first base station to the mobile station a list of frequencies of base stations of the second type in the system, such that the mobile station seeks to receive the signal at a frequency in the list.

6. A method according to any of the preceeding claims, wherein handing over the mobile station comprises transmitting a handover command from the first base station.

7. A method according to any of the preceeding claims, wherein establishing the communications link and receiving the data responsive to the signal comprise establishing the link and receiving the signal at the mobile station using a single FR transceiver in the mobile station.

8. A method according to claim 1, wherein the TDMA interface comprises a GSM interface, and wherein the CDMA interface is configured to convey GSM network messages.

9. A method according to claim 1, wherein the CDMA interface is based on an IS-95 standard.

', "10. A method according to any of the preceeding claims, wherein establishing the communications link comprises using a single radio resource management protocol layer to manage the first air interface, and wherein handing over the mobile station comprises using the single radio resource management protocol layer to manage the second air interface.

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"11. A method according to any of the preceeding claims wherein receiving the data from the mobile station comprises defining an area of overlap between a first region served by the first air interface and a second region served by the second air interface, and triggering the mobile station to receive the data when the mobile station is in the area of overlap.

12. A method according to any of the preceeding claims, wherein the first air interface comprises a CDMA interface, and wherein the second air interface comprises a GSM/TDMA interface, and wherein receiving data from the mobile station comprises gating the mobile station to interrupt a CDMA communications link so as to receive and decode a GSM/TDMA signal.

13. A method according to claim 1, wherein gating the mobile station comprises interrupting CDMA communications for the duration of an IS-95 frame.

14. A method according to claim 1 & 13, wherein receiving the data comprises receiving an identification of the second base station based on decoding of GSM frequency correction and synchronization channels of the signal by the mobile station.

15. A method according to any of the preceeding claims, wherein the first air interface comprises a GSM/TDMA interface, and the second air interface comprises a CDMA interface, and wherein receiving the data from the mobile station comprises controlling the mobile station to interrupt the communications link so as to receive and decode a CDMA signal.

16. A method according to claim 15, wherein receiving the data comprises conveying time of day information through the GSM/TDMA interface.

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17. A method according to claim 16, wherein conveying the time of day information comprises broadcasting time of day information through the system using a GSM cell broadcast service.

18. A method according to claim 17, wherein broadcasting the time of day information comprises receiving a time of day and an associated GSM frame number from a transceiver in communication with a base station of the first type in the system.

19. A method according to claim 16, wherein the mobile station decodes a sync channel of the CDMA signal so as to derive the time of day.

20. A method according to the claim 15 or any claims 16-19 as dependent thereon, wherein receiving the data comprises conveying a GSM cell broadcast service message to the mobile station to initiate a search by the mobile station for a signal from a base station of the second type.

21. A method according to claim 20, wherein conveying the GSM cell broadcast service message to the mobile station comprises conveying the message so as to be received by the mobile station while the mobile station is operating in a dedicated mode.

22. A method according to claim 15 or any claims 16-21 as dependent thereon, wherein receiving the data from the mobile station comprises receiving an identification of a CDMA pilot beam decoded by the mobile station.

23. A method according to claim 16 or any claims 17-22 as dependent thereon, and comprising mapping the second base station as a GSM base station so as to control the handover.

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24. A method according to claim 16 or any claims 17-24 as dependent thereon, wherein controlling the mobile station comprises controlling the mobile station to receive the CDMA signal during a first TDMA time slot and to decode the signal during a subsequent TDMA time slot while communicating with the base station over the TDMA interface so as to generate the data to be received by the base station.

25. In a GSM mobile wireless telecommunications system, which includes a first base station subsystem and a second base station subsystem, at least one of which subsystems operates according to CDMA air interface, the other of which operating according to a TDMA air interface, a method for handing over a mobile station in the system from the first base station subsystem to the second base station subsystem, comprising:

mapping the at least one of the first and second subsystems that operates according to the CDMA air interface as a GSM/TDMA subsystem;

establishing a communications link between the mobile station and the first base station subsystem, so that the mobile station receives a first signal from the first base station subsystem;

receiving data from the mobile station responsive to a second signal received by the mobile station from the second base station subsystem , substantially without breaking the communications link with the first base station subsystem;

wherein receiving the data comprises applying a weighting factor to the measurement of signal strength;

comparing the strengths of the first and second signals, substantially as though both the first and second base station subsystems were GSM/TDMA subsystems; and handing over the mobile station from the first to the second base station subsystem responsive to comparison of the signal strengths.

26. A method according to claim 25, wherein mapping the at least one of the subsystems that operates according to the CDMA air interface comprises assigning to the subsystem a GSM frequency and location.

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27. A method according to claim 25 or 26, wherein establishing the communications link and handing over the mobile station comprise conveying messages between the first and second subsystems and a mobile switching center in the system via a GSM A-interface.

28. A method according to claim 27, wherein both the first and second base station subsystems operate according to the CDMA air interface.

29. A method according to claim 28, wherein handing over the mobile station comprises conveying a new IS-95 long code through the A-interface, substantially without violating A-interface protocols.

30. Wireless communications apparatus, for use in a mobile telecommunications system, comprising:

a base station of a first type which transmits and receives a first signal according to a first air interface;

a base station of a second type which transmits and receives a second signal according to a second air interface; and wherein one of the first and second air interfaces comprises a TDMA interface, and the other of the interfaces comprises a CDMA interface; and a mobile station, which receives the second signal over the second air interface from the base station of the second type while maintaining a communication link over the first air interface with the base station of the first type, and which transmits data to the base station of the first type responsive to the second signal so that the mobile station is handed over from the first to the second base station responsive to the transmitted data;

wherein transmitting the data comprises applying a weighting factor to the measurement of signal strength.

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31. Apparatus according to claim 30, wherein the data transmitted by the mobile station comprises a measurement of signal strength, such that the mobile station is handed over responsive to a comparison of signal strengths of the first and second signals.

32. Apparatus according to claim 31, wherein a weighting factor is applied to the measurement of signal strength.

33. Apparatus according to claim 32, wherein the weighting factor is varied according to a network condition in the system and/or transmitted over the communications link to the mobile station, which applies the weighting factor to the measurement.

34. Apparatus according to claim 30 or any of claims 31-33 as dependent thereon, wherein the mobile station is configured to decode the second signal to determine an identification of the base station of the second type.

35. Apparatus according to claim 30 or any of claims 31-34 as dependent thereon, wherein the base station of the first type transmits to the mobile station a list of frequencies of mobile stations of the second type in the system, such that the mobile station seeks to receive the second signal at a frequency in the list.

36. Apparatus according to claim 30 or any of claims 31-35 as dependent thereon, wherein the base station of the first type is configured to transmit a handover command to the mobile station, whereby the mobile station is handed over from the first to the second base station.

37. Apparatus according to claim 30 or any of claims 31-36 as dependent thereon, wherein the mobile station comprises a single RF transceiver which communicates with both the base stations of the first and semnri ttypes.

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38. Apparatus according to any of claims 30-37, wherein the TDMA interface comprises a GSM interface, and wherein the CDMA interface is configured to convey GSM network messages.

39. Apparatus according to claim 38, wherein the CDMA interface is based on an IS-95 standard.

40. Apparatus according to any one of claims 30-39 as dependent thereon, wherein the mobile station uses a single radio resource management protocol layer to manage both the first and second air interfaces.

41. Apparatus according to any one of claims 30-40 as dependent thereon, wherein either base station is configured to the mobile station to receive the second signal over the second air interface when the mobile station is in an area of overlap between a first region served by the first air interface and a second region served by the second air interface.

42. Apparatus according to any one of claims 30-41 as dependent thereon, wherein the first air interface comprises a CDMA interface, and wherein the second air interface comprises a GSM/TDMA interface, and wherein the base station of the first type gates the mobile station to interrupt the communications link so as to receive and decode a GSM signal.

43. Apparatus according to claim 42, wherein the mobile station is configured to interrupt the link for the duration of an IS-95 frame and/or process the second signal to decode GSM frequency correction and synchronization channels of the signal.

', "44. Apparatus according to any one of claims 30-43 as dependent thereon,

wherein the first air interface

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interface comprises a CDMA interface, and wherein the base station of the first type controls the mobile station to interrupt the communications link so as to receive and decode a CDMA signal.

", '45. Apparatus according to claim 44, wherein the base station of the first type conveys time of day information to the mobile station through the GSM/TDMA interface.

46. Apparatus according to claim 45, and comprising a GSM cell broadcast center, which conveys the time of day information through the system to the mobile station using a GSM cell broadcast service.

47. Apparatus according to claim 46, wherein the cell broadcast center receives the time of day information and an associated GSM frame number from a transceiver in communication with a base station of the first type in the system.

48. Apparatus according to claim 45 or any of claims 46-47 as dependent thereon, wherein the mobile station is configured to decode a synchronization channel of the CDMA signal so as to derive the time of day.

49. Apparatus according to claim 44 or any of claims 45-48 as dependent thereon, and comprising a GSM cell broadcast center, which conveys a cell broadcast service message to the mobile station to initiate a search by the mobile station for the second signal.

50. Apparatus according to claim 47, wherein the mobile station receives the cell broadcast service message while the mobile station is operating in a dedicated mode.

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51. Apparatus according to claim 44 or any of claims 45-50 as dependent thereon, wherein the mobile station processes the CDMA signal to identify a CDMA pilot beam.

52. Apparatus according to claim 44 or any of claims 45-51 as dependent thereon, wherein the mobile station receives the CDMA signal during a first TDMA time slot and processes the signal during a subsequent TDMA time slot while communicating with the base station over the TDMA interface so as to generate the data for transmission to the base station.

53. Apparatus for conveying time of day information to a mobile station in a GSM wireless telecommunications system, comprising a cell broadcast center, which broadcasts the information to the mobile station using a GSM cell broadcast system.

54. Apparatus according to claim 53, and comprising a transceiver in communication with system, which transmits a time of day and an associated GSM frame number to the cell broadcast center.

55. Apparatus according to claim 53, wherein the transceiver opens a data call through the system to the cell broadcast center so as to convey the time of day and associated frame number thereto.

56. Apparatus according to claim 53 or any of claims 54-55 as dependent thereon, wherein the mobile station is synchronized to a CDMA transmission signal using the time of day information.

57. Apparatus according to claim 53 or any of claims 54-56 as dependent thereon, wherein the mobile station receives the information from the cell broadcast system while operating in a dedicated mode.

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58. A mobile station for use in a wireless telecommunications system including CDMA and TDMA base stations, comprising:

a single mobile radio transceiver, which communicates with the CDMA and TDMA base stations;

a modern unit, which encodes signals for transmission by the mobile transceiver ands decodes signals received thereby, such that the signals are CDMA-encoded for communication with the CDMA base station; and terminal equipment, through which a user of the mobile station communicates with the modem unit;

wherein the mobile station is adapted to establish a communications link over the first air interface with the first base station, and to transmit data in response to a received signal over the second air interface to the second base station substantially without breaking a communications link with the first base station, said transmitted data being used to facilitate the handing over of the mobile station from the first to the second base station;

wherein transmitting the data comprises applying a weighting factor to the measurement of signal strength.

59. A mobile station according to claim 58, wherein the modem unit encodes the signals in accordance with GSM radio interface layer protocols.

60. In a mobile wireless telecommunications system, which includes base stations of a first type operating according to a first air interface, and base stations of a second type operating according to a second air interface, an apparatus for handing over a mobile station in the system from a first base station, which is of the first type, to a second base station, which is of the second type, wherein one of said first and second air interfaces comprises a TDMA interface, and the other of the interfaces comprises a CDMA interface, said system comprising:

means for establishing a communications link over the first air interface between the mobile station and the first base station;

means for receiving data from the mobile station responsive to a signal received by the mobile station over the second air interface from tho second base

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station, substantially without breaking the communications link with the first base station;

wherein receiving the data comprises applying a weighting factor to the measurement of signal strength; and means for handing over the mobile from the first to the second base station responsive to the data received therefrom.

61. An apparatus according to claim 60, wherein the means for receiving the data comprises means for receiving a measurement of signal strength, and wherein the means for handing over the mobile station comprises means for comparing measurements of signal strengths from the first and second base stations and handing over the mobile station responsive to the comparison.

62. An apparatus according to claim 61, wherein the means for receiving the data comprises means for applying a weighting factor to the measurement of signal strength.

63. An apparatus according to claim 62, wherein the means for applying the weighting factor comprises means for varying the factor according to a network condition in the system and/or means for transmitting a weighting factor over the communications link to the mobile station, which applies he weighting factor to the measurement.

64. A method for searching for a candidate for handover between a CDMA base station and a TDMA base station, said handover being completed according to the method of claims 1-25, said method of searching including the steps of:

a) receiving a candidate search request message including:

1) a value associated with a frame of information transmitted by a particular TDMA base station;

2) a value associ and

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3) a value indicating the time at which the frame and the portion of the frame were transmitted by the particular TDMA base station; and b) determining from the information included within the received candidate search request message when information will be transmitted in order to reduce the amount of time spent identifying potential candidates for handover.

65. An apparatus for searching for a candidate for handover between a CDMA base station and a TDMA base station, said handover being completed according to the method of claims 1-25, said apparatus including the steps of:

a) a means for receiving a candidate search request message including:

1) a value associated with a frame of information transmitted by a particular TDMA base station;

2) a value associated with a portion of the frame; and

3) a value indicating the time at which the frame and the portion of the frame were being transmitted by the particular TDMA base station; and b) means for determining from the information included within the received candidate search request message when information will be transmitted in order to reduce the amount of time spent identifying potential candidates for handover.

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