Arbitration method for high power transmissions in a code division multiple access system

• US 6,456,835 B1
• Filed: 01/13/2000
• Issued: 09/24/2002
• Est. Priority Date: 01/19/1999
• Status: Expired due to Term

• Current Assignee: IPR Licensing Incorporated (InterDigital, Inc.)
• Original Assignee: Tantivy Communications Incorporated (InterDigital, Inc.)
• Inventors: Proctor, James A. Jr.
• Primary Examiner(s): Maung, Nay
• Assistant Examiner(s): Vuong, Quochien B.
• Application Number:
  US09/482,241
• Time in Patent Office: 985 Days
• Field of Search: 455/421, 455/422, 455/423, 455/425, 455/427, 455/12.1, 455/296, 455/67.1, 455/67.3, 455/67.7, 455/88, 455/128, 455/226.1, 455/226.2, 455/226.3, 455/226.4, 455/436, 370/320, 370/331, 370/332, 370/335, 370/342, 370/441, 370/908
• US Class Current: 455/296
• CPC Class Codes: H04W 52/283 Power depending on the position of the mobile
• CPC Class Codes: H04W 52/50 at the moment of starting communication in a multiple access environment
• CPC Class Codes: H04W 72/541 using the level of interference

Abstract

In an interference mitigation method, subscribers that will receive a high power transmission generate an alert message to surrounding base stations. A surrounding base station, before it generates new transmissions, determines the distance between it and a second subscriber that will receive the new transmission. If the distance is greater than an interference threshold, the base station delays the new transmission until the first high-power transmission concludes. The method prevents two high-power transmissions from occurring simultaneously.

Claims

1. An interference mitigation method for a CDMA system comprising, at a base station:

receiving an alert message;

engaging a delay timer;

during the duration of the delay timer, when a new message is received;

determining a distance from the base station to a subscriber addressed by the new message; and

if the distance is greater than an interference threshold, delaying transmission of the message until the delay timer expires, and thereafter, transmitting the message to the subscriber.

2. The method of claim 1, wherein the determining step includes determining a level of transmitted messages from the subscriber to the base station.

3. The method of claim 1, wherein the delay timer counts out a length of time corresponding to a maximum length of messages transmitted by the CDMA system.

4. The method of claim 1, wherein the CDMA system is a cellular system.

5. The method of claim 1, wherein the CDMA system is a wireless LAN system.

6. The method of claim 1, wherein the CDMA system is a satellite system.

7. The method of claim 1, wherein the base station operates in a plurality of cell sectors and performs the method independently for each sector.

8. An interference mitigation method for a CDMA system including a plurality of base stations and a plurality of subscribers, comprising:

at a first subscriber;

receiving a transmission from an originating base station containing a logical channel assignment;

determining the first subscriber'"'"'s distance to the originating base station;

if the first subscriber'"'"'s distance to the originating base station exceeds a predetermined threshold, transmitting an alert message;

at each base station that receives the alert message;

engaging a delay timer, if, during the duration of the delay timer, a new message is received addressed to a second subscriber;

determining a distance from the base station to the second subscriber, if the distance from the base station to the second subscriber exceeds an interference threshold; and

delaying transmission of the new message to the second subscriber until the delay timer expires, and thereafter, transmitting the new message to the second subscriber.

9. An interference mitigation method for a CDMA system populated by base stations providing sectored cells, comprising:

responsive to an alert message received on at least one sector, engaging a delay timer for the sectors on which the alert message was received;

when a new message is received addressed to a subscriber;

determining the one sector in which the subscriber is located;

determining whether the delay timer is engaged for the one sector, and if the delay timer is engaged for the one sector,

determining a distance from the base station to the subscriber;

if the distance from the base station to the subscriber exceeds an interference threshold, delaying transmission of the new message until the delay timer expires; and

transmitting the new message in the one sector.

10. The method of claim 9, wherein the delay timer counts out a length of time corresponding to a maximum length of non real time messages transmitted by the CDMA system.

11. The method of claim 9, wherein the CDMA system is a cellular system.

12. The method of claim 9, wherein the CDMA system is a wireless LAN system.

13. The method of claim 9, wherein the CDMA system is a satellite system.

14. An apparatus for interference mitigation in the CDMA system comprising:

a receiver, located at a base station for receiving an alert message;

a delay timer, being engaged upon receipt of the alert message;

distance determining means, connected to a base station message receiver, for determining a distance from the base station to a subscriber unit addressed by a new message received during duration of the delay timer, and if that distance is greater than an interference threshold, delaying transmission of the message until the delay timer expires; and

a transmitter for transmitting the message to the subscriber upon expiration of the delay timer.

15. An apparatus as in claim 14 wherein the means for determining a distance includes determining a level of transmitted messages from a subscriber unit to the base station.

16. An apparatus as in claim 14 wherein the delay timer additionally counts out a length of delay a length of time corresponding to a maximum length of messages transmitted by the CDMA system.

17. An apparatus as in claim 14 wherein the CDMA system is a cellular system.

18. An apparatus as in claim 14 wherein the CDMA system is a wireless LAN system.

19. An apparatus as in claim 14 wherein the CDMA system is a satellite system.

20. An apparatus as in claim 14 wherein the base station operates in a plurality of cell sectors.