Traffic channel assignment in a cellular telephone system using an uplink interference driven frequency packing method

• US 5,963,865 A
• Filed: 11/24/1997
• Issued: 10/05/1999
• Est. Priority Date: 11/24/1997
• Status: Expired due to Term

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Nagle, Mairead, Simonsson, Arne, Karlsson, Patrik, Desgagne, Michel
• Primary Examiner(s): TO, DORIS HA
• Application Number:
  US08/977,083
• Time in Patent Office: 680 Days
• Field of Search: 455/422, 455/450-453, 455/455, 455/507, 455/509, 455/512, 455/513-514, 455/516-517, 455/524-525, 455/62, 455/161.1-161.3 , 455/166.1-166.2, 370/322, 370/329, 370/330, 370/337, 370/347, 370/442
• US Class Current: 455/450
• CPC Class Codes: H04W 36/302 due to low signal strength
• CPC Class Codes: H04W 72/02 Selection of wireless resources by user or terminal
• CPC Class Codes: H04W 72/0446 Resources in time domain, e.g. slots or frames
• CPC Class Codes: H04W 72/541 using the level of interference

Abstract

Each base station in a cellular telephone system includes a signal strength measurement device operable to tune to and make signal strength measurements on not only the frequencies allocated to other cells, but also on its own allocated frequencies. Measurements are made by the device on those of its own frequencies having idle traffic channels to obtain an indication of injected uplink interference. An interference penalty is then assessed against the measured uplink interference for those frequencies having more than a threshold number of idle traffic channels. The adjusted measurements for the frequencies allocated to the cell are then sorted in relative order of idle traffic channel (adjusted) measured uplink interference from a least (adjusted) interfered frequency to a most (adjusted) interfered frequency. An idle traffic channel is then selected for assignment at either call set-up or hand-off from the least (adjusted) interfered frequency.

Claims

1. A cellular telephone system, comprising:

a base station allocated use of a plurality of frequencies, each frequency including a plurality of time slot traffic channels, comprising;

a signal strength measuring device selectively tunable to make signal strength measurements on the frequencies allocated to the base station having idle time slot traffic channels and obtain uplink interference measurements on those measured frequencies; and

processing means connected to receive the uplink interference measurements, the processing means operating to;

apply an interference penalty against the received uplink interference measurements if the measured frequency includes more than a threshold number of idle time slot traffic channels;

sort the measured frequencies by their uplink interference measurements adjusted by any applied interference penalties from a least uplink interfered frequency to a most uplink interfered frequency; and

select for assignment by the base station at call set-up or hand-off one of the idle time slot traffic channels included within the least uplink interfered frequency.

2. The system as in claim 1 wherein the signal strength measuring device comprises a base station locating verification module.

3. The system as in claim 1 wherein the signal strength measuring device comprises a base station idle channel supervision functionality provided by a base station transceiver.

4. The system as in claim 1 wherein the signal strength measuring device makes signal strength measurements for each idle time slot.

5. The system as in claim 1 wherein the processing means sorting operation sorts the measured frequencies by their uplink interference measurements adjusted by any applied interference penalties into plural lists, each list ordered from a least uplink interfered frequency to a most uplink interfered frequency.

6. The system as in claim 5 wherein the processing means selecting operation selects from a certain one or ones of the plural lists for assignment at call set-up or hand-off one of the idle time slot traffic channels included within the least uplink interfered frequency contained on that certain list.

7. The system as in claim 1 wherein the processing means applying operation applies an increasing interference penalty against the received uplink interference measurements corresponding to when an increasing number of idle time slot traffic channels are included within the frequency.

8. The system as in claim 1 wherein the processing means comprises a mobile switching center connected to the base station.

9. A method for use in a cellular telephone system for assigning traffic channels, comprising the steps of:

making signal strength measurements on frequencies allocated to a base station, wherein each frequency includes a plurality of time slot traffic channels, the measurement made on those frequencies having idle time slot traffic channels to obtain uplink interference measurements;

applying an interference penalty against the made uplink interference measurements if the measured frequency includes more than a threshold number of idle time slot traffic channels;

sorting the measured frequencies by their uplink interference measurements adjusted by any applied interference penalties from a least uplink interfered frequency to a most uplink interfered frequency; and

selecting for assignment by the base station at call set-up or hand-off one of the idle time slot traffic channels included within the least uplink interfered frequency.

10. The method as in claim 9 wherein the step of making signal strength measurements comprises the step of making signal strength measurements for each idle time slot.

11. The method as in claim 9 wherein the step of sorting comprises the step of sorting the measured frequencies by their uplink interference measurements adjusted by any applied interference penalties into plural lists, each list ordered from a least uplink interfered frequency to a most uplink interfered frequency.

12. The method as in claim 11 wherein the step of selecting comprises the step of selecting from a certain one or ones of the plural lists for assignment at call set-up or hand-off one of the idle time slot traffic channels included within the least uplink interfered frequency contained on that certain list.

13. The method as in claim 9 wherein step of applying comprises the step of applying an increasing interference penalty against the received uplink interference measurements corresponding to when an increasing number of idle time slot traffic channels are included within the frequency.

14. The method as in claim 9 wherein the step of selecting comprises the step of randomly selecting an idle time slot traffic channel included within the least uplink interfered frequency.

15. The method as in claim 9 wherein the step of selecting comprises the step of selecting an idle time slot traffic channel having a lowest interference included within the least uplink interfered frequency.

16. A cellular telephone system having a plurality of frequencies available for carrying cellular communications, each frequency including a plurality of time slot traffic channels, comprising:

a plurality of base stations distributed across a service area, each base station being allocated to use a subset of the plurality of frequencies wherein each base station includes;

a signal strength measuring device selectively tunable for making signal strength measurements on any of the plurality of frequencies in the system; and

processing means;

connected to receive a report from a given base station of measurements made by the signal strength measuring device on selected ones of the subset of frequencies allocated to that given base station which include idle traffic channels, the measured signal strengths indicative of uplink interference; and

operating to process uplink interference signal strength measurements for the selected frequencies and select for assignment by the given base station an idle time slot traffic channel on as little an interfered one of selected frequencies as possible while simultaneously using as few of the frequencies allocated to that given base station as possible by giving selection preference to an idle time slot traffic channel on the as little interfered one of the selected frequencies which currently has the fewest number of idle time slots.

17. The system of claim 16 wherein the signal strength measuring device comprises a locating verification module.

18. The system of claim 16 wherein the signal strength measuring device comprises an idle channel supervision functionality provided by a base station transceiver.

19. The system as in claim 16 wherein the signal strength measuring device makes signal strength measurements for each idle time slot.

20. The system as in claim 16 wherein the processing means operates to process and select by:

applying an interference penalty against the received uplink interference measurements if the measured frequency includes more than a threshold number of idle time slot traffic channels;

sorting the measured frequencies by their uplink interference measurements adjusted by any applied interference penalties from a least uplink interfered frequency to a most uplink interfered frequency; and

selecting for assignment by the base station at call set-up or hand-off one of the idle time slot traffic channels included within the least uplink interfered frequency.

21. The system as in claim 20 wherein the processing means performs the sorting operation to sort the measured frequencies by their uplink interference measurements adjusted by any applied interference penalties into plural lists, each list ordered from a least uplink interfered frequency to a most uplink interfered frequency.

22. The system as in claim 21 wherein processing means performs the selecting operation to select from a certain one or ones of the plural lists for assignment at call set-up or hand-off one of the idle time slot traffic channels included within the least uplink interfered frequency contained on that certain list.

23. The system as in claim 20 wherein the processing means performs the applying operation to apply an increasing interference penalty against the received uplink interference measurements corresponding to when an increasing number of idle time slot traffic channels are included within the frequency.

24. The system as in claim 16 wherein processing means comprises a mobile switching center.

25. A method for use in a cellular telephone system for assigning traffic channels, comprising the steps of:

making signal strength measurements on frequencies allocated to a base station, wherein each frequency includes a plurality of time slot traffic channels, the measurement made on those frequencies having idle time slot traffic channels to obtain uplink interference measurements;

making a report by a given base station of measurements made on selected ones of the plurality of frequencies allocated to that given base station which include idle traffic channels, the measured signal strengths indicative of uplink interference; and

processing the reported uplink interference signal strength measurements for the selected frequencies to select for assignment by the given base station an idle time slot traffic channel on as little an interfered one of selected frequencies as possible while simultaneously using as few of the frequencies allocated to that given base station as possible by giving selection preference to an idle time slot traffic channel on the as little interfered on to the selected frequencies which currently has the fewest number of idle time slots.

26. The method as in claim 25 wherein the step of making signal strength measurements comprises the step of making signal strength measurements for each idle time slot.

27. The method as in claim 25 wherein the step of processing comprises the steps of:

applying an interference penalty against the received uplink interference measurements if the measured frequency includes more than a threshold number of idle time slot traffic channels;

sorting the measured frequencies by their uplink interference measurements adjusted by any applied interference penalties from a least uplink interfered frequency to a most uplink interfered frequency; and

selecting for assignment by the base station at call set-up or hand-off one of the idle time slot traffic channels included within the least uplink interfered frequency.

28. The method as in claim 27 wherein the step of sorting comprises the step of sorting the measured frequencies by their uplink interference measurements adjusted by any applied interference penalties into plural lists, each list ordered from a least uplink interfered frequency to a most uplink interfered frequency.

29. The method as in claim 28 wherein the step of selecting comprises the step of selecting from a certain one or ones of the plural lists for assignment at call set-up or hand-off one of the idle time slot traffic channels included within the least uplink interfered frequency contained on that certain list.

30. The method as in claim 27 wherein step of applying comprises the step of applying an increasing interference penalty against the received uplink interference measurements corresponding to when an increasing number of idle time slot traffic channels are included within the frequency.

31. The method as in claim 27 wherein the step of selecting comprises the step of randomly selecting an idle time slot traffic channel included within the least uplink interfered frequency.

32. The method as in claim 27 wherein the step of selecting comprises the step of selecting an idle time slot traffic channel having a lowest interference included within the least uplink interfered frequency.