Method for assigning a unique word in a communication system

• US 20070110013A1
• Filed: 11/15/2005
• Published: 05/17/2007
• Est. Priority Date: 11/15/2005
• Status: Active Grant

• Current Assignee: Kyocera Corporation
• Original Assignee: Kyocera Corporation
• Inventors: Sano, Masato
• Granted Patent: US 7,697,494 B2
• Time in Patent Office: Days
• US Class Current: 370/338
• CPC Class Codes: H04W 72/20 Control channels or signalling for resource management
• CPC Class Codes: H04W 72/51 based on terminal or device properties
• CPC Class Codes: H04W 72/541 using the level of interference
• CPC Class Codes: H04W 72/56 based on priority criteria

Abstract

A method and system for assigning unique words in an SDMA (spatial division multiple access) communication system is disclosed. A base station has a set of available unique words from which to select and assign unique words. The base station prioritizes the set of unique words by determining which unique words are likely to interfere with adjacent base stations, and setting those words to a low priority. In this way, over time, the base station assigns unique words that have a lower level of correlation to allow for better signal differentiation and improved communication sensitivity. When a mobile device enters a base station'"'"'s geographic area, it generates an establish request message that indicates what unique word it is using in the adjacent cell. The base station extracts this unique word, and sets it to a low priority in its set of unique words. The base station is therefore able to assign unique words that facilitate improved communications.

Claims

1. A method for assigning a unique word to a personal station in an SDMA (Spatial division Multiple Access) communication system, the SDMA communication system having a set of available unique words comprising:

receiving a request message;

extracting information from the request message that is indicative of a first unique word;

determining if the request message is from a personal station that is being handed off from another cell;

comparing, if the personal station is being handed off, the first unique word to the set of unique words; and

adjusting priority of the unique words based on the comparing step.

2. The method according to claim 1, wherein the comparing step includes determining a level of cross correlation between the first unique word and each of the unique words in the set of available unique words.

3. The method according to claim 2, wherein the adjusting step includes setting unique words with lower cross correlation effects to a higher priority.

4. The method according to claim 1, further comprising the steps of:

selecting a high priority unique word from the set of unique words; and

generating an assignment message including the high priority unique word.

5. The method according to claim 1, further comprising the steps of:

receiving an establish request from a second personal station;

selecting a high priority unique word from the set of unique words; and

generating an assignment message to assign the selected unique word to the second personal station.

6. The method according to claim 1, wherein the request message is received as an establish request message.

7. The method according to claim 1, wherein the personal station is operating as a PHS personal station communicating with a PHS cell station.

8. The method according to claim 1, further comprising:

maintaining, if the personal station is not being handed off, the current priority in the set of unique words.

9. The method according to claim 1, further comprising:

determining if the personal station is requesting to make a new call;

selecting a high priority unique word from the set of unique words; and

generating an assignment message to assign the selected unique word to the personal station.

10. The method according to claim 9, wherein the determining step comprises evaluating the extracted message to determine if a valid unique word is indicated.

11. A method for generating a request message from a personal station, comprising:

determining that an establish request should be made;

generating an establish request message, the message comprising a unique word field and an identifier field; and

transmitting the establish request message.

12. The method according to claim 11, wherein the identifier field comprises a personal station identification value.

13. The method according to claim 11, wherein the identifier field comprises a cell station identification value.

14. The method according to claim 11, wherein the determining step comprises receiving a new call instruction.

15. The method according to claim 11, wherein the determining step is part of a call handoff process.

16. A method for assigning unique words from a cell station to a set of personal stations, comprising:

storing a set of unique words for the cell station;

receiving an establish request from an arriving personal station, the arriving personal station also communicating with another cell station;

extracting information from the establish request to determine an adjacent unique word used by an arriving personal station;

prioritizing the set of unique words according to correlation with the adjacent unique word; and

assigning unique words from the set of unique words so that higher priority words are assigned before lower priority unique words are assigned.

17. The method according to claim 16, wherein the prioritizing step includes identifying a unique word in the set of unique words that has a low cross correlation effect with the adjacent unique word, and setting that identified unique word to have a high priority.

18. The method according to claim 16, wherein the prioritizing step includes identifying a unique word in the set of unique words that has a high cross correlation effect with the adjacent unique word, and setting that unique word to have a low priority.

19. The method according to claim 16, wherein the number of unique words in the set of unique words is more than the number of unique words that are permitted to be assigned.

20. The method according to claim 19, wherein the number of unique words in the set of unique words is about 10 and the number of unique words that are permitted to be assigned is about 3.

21. The method according to claim 16, wherein the set of unique words is organized according to time slot number.

22. The method according to claim 21, wherein unique word priority is set independently for each time slot number.

23. The method according to claim 16, wherein the arriving personal station is operating as a PHS personal station and the cell station is operating as a PHS cell station.

24. A method for prioritizing the assignment of unique words from a base station, comprising:

storing a set of unique words that are useful in implementing an SDMA (Spatial division Multiple Access) communication process;

receiving a request message that is indicative of a first unique word;

determining that the first unique word is in use at an adjacent base station;

comparing the first unique word to at least some of the unique words in the set of available unique words; and

adjusting priority of the unique words in the set of unique words according to the comparison.

25. The method according to claim 24, further including a set of assignable unique words, the assignable unique words being a subset of the set of unique words.

26. The method according to claim 25, wherein the adjusting step includes replacing one of the unique words in the set of assignable unique words, and placing the replaced unique word at a lower priority in the set of unique words.

27. The method according to claim 24, wherein the request message is generated by a mobile device, and the mobile device is operating as a PHS personal station and the base station is operating as a PHS cell station.

28. The method according to claim 24, wherein the request message is received as a PHS establish request message.

29. The method according to claim 24, wherein the comparing step comprises comparing the cross correlation between the first unique word and at least some of the unique words in the set of available unique words.