Method and apparatus for selecting a base station

• US 6,760,599 B1
• Filed: 09/29/2000
• Issued: 07/06/2004
• Est. Priority Date: 09/29/2000
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: ArrayComm LLC (Ygomi LLC)
• Inventors: Uhlik, Christopher Richard
• Primary Examiner(s): Maung, Nay
• Assistant Examiner(s): SHARMA, SUJATHA R
• Application Number:
  US09/676,140
• Time in Patent Office: 1,376 Days
• Field of Search: 455/67.1, 455/442, 455/437, 455/434, 455/422, 455/450, 455/525, 455/524, 455/453, 455/436, 455/422.1
• US Class Current: 455/525
• CPC Class Codes: H04B 7/022 Site diversity; Macro-diversity using two or more spaced independent antennas H04B7/04
• CPC Class Codes: H04W 36/08 Reselecting an access point
• CPC Class Codes: H04W 36/36 by user or terminal equipment
• CPC Class Codes: H04W 48/10 using broadcasted information
• CPC Class Codes: H04W 48/20 Selecting an access point

Abstract

In one embodiment, the present invention comprises receiving a first broadcast burst from a first base station of a radio communications system, the first broadcast message including a first broadcast information sequence representing the power with which the first broadcast burst was transmitted, and measuring the received signal strength of the first broadcast burst. The invention further comprises receiving a second broadcast burst from a second base station of the radio communications system, the second broadcast burst including a second broadcast information sequence representing the power with which the second broadcast burst was transmitted, and measuring the received signal strength of the second broadcast burst. The invention further includes selecting a base station of the radio communications system for communication of data based on the first and second broadcast information sequence and the received signal strength of the first and second broadcast bursts.

Claims

1. A method comprising:

receiving a first broadcast burst from a first base station of a radio communications system at a user terminal, the first broadcast message including a first broadcast information sequence including an index of how much unused capacity is available at the first base station;

receiving a second broadcast burst from a second base station of the radio communications system at the user terminal, the second broadcast burst including a second broadcast information sequence including an index of how much unused capacity is available at the second base station; and

selecting a base station of the radio communications system at the user terminal for communication of data between the selected base station and the user terminal based on the first and second broadcast information sequences.

2. The method of claim 1 wherein receiving the first broadcast burst comprises receiving the first broadcast burst in a broadcast channel at a first specific time within a first assigned slot of a predetermined frame and wherein receiving a second broadcast burst comprises receiving the second broadcast burst in the broadcast channel at a second specific time within a second assigned slot of the predetermined frame from a second base station of the radio communications system.

3. The method of claim 2, further comprising receiving broadcast bursts in the broadcast channel at further specific times within further assigned slots of a predetermined frame from further base stations of the radio communications system, the further broadcast messages including a broadcast information sequence including an index of how much unused capacity is available at the respective base station and wherein selecting a base station further comprises selecting a base station based on the broadcast information sequences of the further base stations.

4. The method of claim 2 further comprising:

sending a system access request burst having a timing relationship with the predetermined frame, wherein the base station to which the burst is directed is based on the timing relationship.

5. The method of claim 1 wherein the sequence including an index of how much unused capacity is available at the respective base station, represents the transmit and receive bit rates of each modem of each respective base station over a period of a few minutes measured against maximum possible loading.

6. The method of claim 5, wherein the index of how much unused capacity is available at the respective base station takes into account the number of amplifiers and diversity antennas available at the base station.

7. The method of claim 1, wherein the broadcast information sequence includes a code to identify the base station.

8. The method of claim 7, wherein the code to identify the base station comprises a base station color code.

9. The method of claim 1, further comprising measuring the timing of receiving the first broadcast burst and measuring the timing of receiving the second broadcast burst and wherein selecting a base station further comprises selecting a base station based on the measured timing.

10. The method of claim 9, wherein the first and second broadcast bursts are synchronized to a common timing reference.

11. The method of claim 10 wherein the common timing reference is a satellite clock transmission received by a satellite receiver at each base station.

12. The method of claim 1, wherein the broadcast information sequence includes a power sequence that is related to the power with which the burst was transmitted from the respective base station and wherein selecting a base station further comprises selecting a base station based on the power sequence.

13. The method of claim 1 wherein selecting a base station comprises selecting a base station based on whether a communications session with a base station is in progress and the identity of the base station with which the communication session is in progress.

14. The method of claim 1 wherein selecting a base station further comprises:

building a map of base stations for which broadcast bursts have been received;

inserting data from the broadcast information sequences received from each base station into the map; and

scoring each base station based on the data inserted into the map.

15. The method of claim 14 wherein inserting data further comprises scaling the data using scaling values appropriate to each item of data that is inserted.

16. The method of claim 14 further comprising measuring attributes of each received broadcast burst and inserting the measurement into the map and wherein scoring each base station further comprises scoring each base station based on the data inserted into the map and based on the measurements inserted into the map.

17. The method of claim 16 wherein measuring attributes comprises measuring the signal strength at which each broadcast burst is received.

18. The method of claim 16 wherein measuring attributes comprises measuring the time delay with which each broadcast burst is received.

19. A machine-readable medium having stored thereon data representing sequences of instructions which, when executed by a machine, cause the machine to perform operations comprising:

receiving a first broadcast burst from a first base station of a radio communications system, the first broadcast message including a first broadcast information sequence including an index of how much unused capacity is available at the first base station;

receiving a second broadcast burst from a second base station of the radio communications system, the second broadcast burst including a second broadcast information sequence including an index of how much unused capacity is available at the second base station; and

selecting a base station of the radio communications system for communication of data based on the first and second broadcast information sequences.

20. The medium of claim 19 wherein the instructions for receiving the first broadcast burst comprise instructions causing the machine to perform operations comprising receiving the first broadcast burst in a broadcast channel at a first specific time within a first assigned slot of a predetermined frame and wherein the instructions for receiving a second broadcast burst comprise instructions causing the machine to perform operations comprising receiving the second broadcast burst in the broadcast channel at a second specific time within a second assigned slot of the predetermined frame from a second base station of the radio communications system.

21. The medium of claim 20, further comprising instructions causing the machine to perform operations comprising receiving broadcast bursts in the broadcast channel at further specific times within further assigned slots of a predetermined frame from further base stations of the radio communications system, the further broadcast messages including a broadcast information sequence including an index of how much unused capacity is available at the respective base station and wherein the instructions for selecting a base station further comprise instructions causing the machine to perform operations comprising selecting a base station based on the broadcast information sequences of the further base stations.

22. The medium of claim 19 wherein the sequence including an index of how much unused capacity is available at the second base station, represents the transmit and receive bit rates of each modem of each respective base station over a period of a few minutes measured against maximum possible loading.

23. The medium of claim 19, further comprising instructions causing the machine to perform operations comprising measuring the timing of receiving the first broadcast burst and measuring the timing of receiving the second broadcast burst and wherein the instructions for selecting a base station further comprise instructions causing the machine to perform operations comprising selecting a base station based on the measured timing.

24. The medium of claim 19, wherein the broadcast information sequence includes a power sequence that is related to the power with which the burst was transmitted from the respective base station and wherein the instructions for selecting a base station further comprise instructions causing the machine to perform operations comprising selecting a base station based on the power sequence.

25. The medium of claim 19 wherein the instructions for selecting a base station further comprise instructions causing the machine to perform operations comprising:

building a map of base stations for which broadcast bursts have been received;

inserting data from the broadcast information sequences received from each base station into the map; and

scoring each base station based on the data inserted into the map.

26. A user terminal comprising:

means for receiving a first broadcast burst from a first base station of a radio communications system, the first broadcast message including a first broadcast information sequence including an index of how much unused capacity is available at the first base station;

means for receiving a second broadcast burst from a second base station of the radio communications system, the second broadcast burst including a second broadcast information sequence including an index of how much unused capacity is available at the second base station; and

means for selecting a base station of the radio communications system for communication of data based on the first and second broadcast information sequences.

27. The terminal of claim 26, further comprising means for measuring the timing of receiving the first broadcast burst and means for measuring the timing of receiving the second broadcast burst and wherein the means for selecting a base station further comprises means for selecting a base station based on the measured timing.

28. The terminal of claim 26, wherein the broadcast information sequence includes a power sequence that is related to the power with which the burst was transmitted from the respective base station and wherein the means for selecting a base station further comprises means for selecting a base station based on the power sequence.

29. A method comprising:

transmitting a first broadcast burst from a first base station of a radio communications system, the first broadcast message including a first broadcast information sequence representing the power with which the first broadcast burst was transmitted and the traffic load carried by the first base station as indicated by an index of how much unused capacity is available at the first base station;

transmitting a second broadcast burst from a second base station of the radio communications system, the second broadcast burst including a second broadcast information sequence representing the power with which the second broadcast burst was transmitted and the traffic load carried by the second base station as indicated by an index of how much unused capacity is available at the second base station;

receiving a system access request burst from a remote terminal of the radio communications system indicating a base station selection for communication of data based on the first and second broadcast information sequences.

30. The method of claim 29 wherein transmitting the first broadcast burst comprises transmitting the first broadcast burst in a broadcast channel at a first specific time within a first assigned slot of a predetermined frame, wherein transmitting a second broadcast burst comprises transmitting the second broadcast burst in the broadcast channel at a second specific time within a second assigned slot of the predetermined frame from a second base station of the radio communications system and wherein the base station selection is further based on the timing of the first and second broadcast bursts.

31. The method of claim 30 wherein the system access request burst has a timing relationship with the predetermined frame, indicating the base station to which the burst is directed.

32. The method of claim 30, wherein the first and second broadcast bursts are synchronized to a common timing reference.

33. The method of claim 32 wherein the common timing reference is a satellite clock transmission received by a satellite receiver at each base station.

34. The method of claim 29 wherein the sequence representing the power represents the effective isotropic radiated power of the broadcast burst transmission.

35. The method of claim 34, wherein the effective isotropic radiated power indicates the power transmitted by the base station taking into account the number of amplifiers and diversity antennas available at the base station.

36. The method of claim 29, wherein the broadcast information sequence includes a code to identify the base station.

37. The method of claim 36, wherein the code to identify the base station comprises a base station color code.

38. A broadcast channel in a radio communications system, the channel comprising:

a repeating frame shared by a plurality of base stations, the frame having a plurality of slots, each base station being assigned to a slot;

a predetermined timing assigned to each slot, so that each slot of the frame is synchronized at all base stations; and

a broadcast burst for each base station, for transmission in the respective assigned slot, the burst having a broadcast information sequence, the broadcast information sequence representing the power with which the respective broadcast burst was transmitted and the traffic load carried by the respective base station as indicated an index of how much unused capacity is available at the respective base station.

39. The channel of claim 38, further comprising a plurality of uplink request slots to allow a user terminal to request a traffic channel, each slot of the uplink request slots having a timing relationship with the slots of the repeating frame so that the timing relationship indicates the base station to which the traffic channel request is directed.

40. The channel of claim 38, wherein the broadcast information sequence includes a code to identify the transmitting base station.

41. The channel of claim 38, wherein the predetermined timing is based on a common timing reference received by each base station.

42. A machine-readable medium having stored thereon data representing sequences of instructions which, when executed by a machine, cause the machine to perform operations comprising:

transmitting a first broadcast burst from a first base station of a radio communications system, the first broadcast message including a first broadcast information sequence representing the traffic load carried by the first base station as indicated an index of how much unused capacity is available at the first base station;

transmitting a second broadcast burst from a second base station of the radio communications system, the second broadcast burst including a second broadcast information sequence representing traffic load carried by the second base station as indicated by an index of how much unused capacity is available at the second base station;

receiving a system access request burst from a remote terminal of the radio communications system indicating a base station selection for communication of data based on the first and second broadcast information sequences.

43. The medium of claim 42 wherein transmitting the first broadcast burst comprises transmitting the first broadcast burst in a broadcast channel at a first specific time within a first assigned slot of a predetermined frame, wherein transmitting a second broadcast burst comprises transmitting the second broadcast burst in the broadcast channel at a second specific time within a second assigned slot of the predetermined frame from a second base station of the radio communications system and wherein the base station selection is further based on the timing of the first and second broadcast bursts.

44. The medium of claim 43 wherein the system access request burst has a timing relationship with the predetermined frame, indicating the base station to which the burst is directed.

45. The medium of claim 43 wherein the first and second broadcast bursts are synchronized to a common timing reference.

46. The medium of claim 45 wherein the common timing reference is a satellite clock transmission received by a satellite receiver at each base station.

47. The medium of claim 42 wherein the information sequence further comprises a sequence representing the effective isotropic radiated power of the broadcast burst transmission.

48. The medium of claim 47, wherein the effective isotropic radiated power indicates the power transmitted by the base station taking into account the number of amplifiers and diversity antennas available at the base station.

49. The medium of claim 42, wherein the broadcast information sequence includes a code to identify the base station.