System and method for modeling simulcast delay spread and optimizing launch delays

• US 6,097,930 A
• Filed: 08/21/1998
• Issued: 08/01/2000
• Est. Priority Date: 08/21/1998
• Status: Expired due to Term

• Current Assignee: USA Mobility Wireless, Inc. (Spok Holdings, Inc.)
• Original Assignee: WebLink Wireless, Inc. (Spok Holdings, Inc.)
• Inventors: Chang, Chi-Ming, Hill, Selwyn E.
• Primary Examiner(s): CANGIALOSI, SALVATORE A
• Application Number:
  US09/138,438
• Time in Patent Office: 711 Days
• Field of Search: 455/31.1, 455/67.6, 370/342
• US Class Current: 340/7.26
• CPC Class Codes: H04H 20/67 Common-wave systems, i.e. using separate transmitters operating on substantially the same frequency
• CPC Class Codes: H04W 4/12 Messaging; Mailboxes; Announcements
• CPC Class Codes: H04W 72/30 Resource management for broadcast services
• CPC Class Codes: H04W 84/027 providing paging services

Abstract

There is disclosed a launch delay controller, for use in a wireless messaging system having a defined coverage area. The launch delay controller controls the transmission of paging messages from a plurality of transmitters in the wireless messaging system. The launch delay controller comprises: 1) a memory capable of storing a) a delay spread associated with a selected point in the coverage area between a first signal transmitted by a first of the plurality of transmitters and a second signal transmitted by a second of the plurality of transmitters, and b) distances between the selected point and the first and second transmitters; and 2) a processor capable of determining from the delay spread and the distances an offset delay, wherein the offset delay is used by the first transmitter to delay a transmission of the first signal with respect to a transmission of the second signal, the delayed transmission of the first signal thereby reducing the delay spread.

Claims

1. For use in a wireless messaging system capable of broadcasting over a selected coverage area, a launch delay controller for controlling a transmission of paging messages from a plurality of transmitters in said wireless messaging system, said launch delay controller comprising:

a memory capable of storing

     1) a delay spread associated with a selected point in said coverage area between a first signal transmitted by a first of said plurality of transmitters and a second signal transmitted by a second of said plurality of transmitters, and

     2) distances between said selected point and said first and second transmitters;

a processor capable of determining from said delay spread and said distances an offset delay, wherein said offset delay is used by said first transmitter to delay a transmission of said first signal with respect to a transmission of said second signal, said delayed transmission of said first signal thereby reducing said delay spread.

2. The launch delay controller as set forth in claim 1 wherein said delay spread is measured at said selected point.

3. The launch delay controller as set forth in claim 1 wherein said delay spread is a theoretical predicted value associated with said selected point.

4. The launch delay controller as set forth in claim 1 wherein said memory is capable of storing a plurality of delay spreads associated with a plurality of selected points in said coverage area, and a plurality of distances between each of said selected points and each of said plurality of transmitters.

5. The launch delay controller as set forth in claim 4 wherein said processor determines from said plurality of delay spreads and said plurality of distances a plurality of offset delays, wherein a first offset delay is used by said first transmitter to delay a transmission of said first signal with respect to a transmission of said second signal, and a second offset delay is used by said second transmitter to delay a transmission of said second signal with respect to a transmission of a third signal by a third of said plurality of transmitters, wherein said delayed transmissions of said first and second signals thereby reduce at least two of said delay spreads.

6. The launch delay controller as set forth in claim 5 wherein said launch delay controller determines a plurality of offset delays operable to optimize a plurality of delay spreads throughout said coverage area.

7. The launch delay controller as set forth in claim 5 wherein said launch delay controller assigns a weighting factor to at least one of said selected points and uses said weighting factor to modify at least one of said offset delays such that a first delay spread is more greatly reduced than a second delay spread.

8. A wireless messaging system capable of broadcasting over a selected coverage area comprising:

a plurality of transmitters capable of transmitting a plurality of paging message signals; and

a launch delay controller for controlling the transmission of paging message signals from said plurality of transmitters, said launch delay controller comprising;

a memory capable of storing

     1) a delay spread associated with a selected point in said coverage area between a first signal transmitted by a first of said plurality of transmitters and a second signal transmitted by a second of said plurality of transmitters, and

     2) distances between said selected point and said first and second transmitters;

a processor capable of determining from said delay spread and said distances an offset delay, wherein said offset delay is used by said first transmitter to delay a transmission of said first signal with respect to a transmission of said second signal, said delayed transmission of said first signal thereby reducing said delay spread.

9. The wireless messaging system set forth in claim 8 wherein said delay spread is measured at said selected point.

10. The wireless messaging system set forth in claim 8 wherein said delay spread is a theoretical predicted value associated with said selected point.

11. The wireless messaging system set forth in claim 8 wherein said memory is capable of storing a plurality of delay spreads associated with a plurality of selected points in said coverage area, and a plurality of distances between each of said selected points and each of said plurality of transmitters.

12. The wireless messaging system set forth in claim 11 wherein said processor determines from said plurality of delay spreads and said plurality of distances a plurality of offset delays, wherein a first offset delay is used by said first transmitter to delay a transmission of said first signal with respect to a transmission of said second signal, and a second offset delay is used by said second transmitter to delay a transmission of said second signal with respect to a transmission of a third signal by a third of said plurality of transmitters, wherein said delayed transmissions of said first and second signals thereby reduces at least two of said delay spreads.

13. The wireless messaging system set forth in claim 12 wherein said launch delay controller determines a plurality of offset delays operable to optimize a plurality of delay spreads throughout said coverage area.

14. The wireless messaging system set forth in claim 12 wherein said launch delay controller assigns a weighting factor to at least one of said selected points and uses said weighting factor to modify at least one of said offset delays such that a first delay spread is more greatly reduced than a second delay spread.

15. For use in a wireless messaging system capable of broadcasting over a selected coverage area, a method for controlling a transmission of paging messages from a plurality of transmitters in the wireless messaging system, the method comprising the steps of:

determining a delay spread associated with a selected point in the coverage area between a first signal transmitted by a first of the plurality of transmitters and a second signal transmitted by a second of the plurality of transmitters;

determining distances between the selected point and the first and second transmitters; and

determining from the delay spread and the distances an offset delay, wherein the offset delay is used by the first transmitter to delay a transmission of the first signal with respect to a transmission of the second signal, the delayed transmission of the first signal thereby reducing the delay spread.

16. The method as set forth in claim 15 wherein the delay spread is measured at the selected point.

17. The method as set forth in claim 15 wherein the delay spread is a theoretical predicted value associated with the selected point.

18. The method as set forth in claim 15 including the further steps of determining a plurality of delay spreads associated with a plurality of selected points in the coverage area, and determining a plurality of distances between each of the selected points and each of the plurality of transmitters.

19. The method as set forth in claim 18 including the further steps of determining from the plurality of delay spreads and the plurality of distances a plurality of offset delays, wherein a first offset delay is used by the first transmitter to delay a transmission of the first signal with respect to a transmission of the second signal, and a second offset delay is used by the second transmitter to delay a transmission of the second signal with respect to a transmission of a third signal by a third of the plurality of transmitters, wherein the delayed transmissions of the first and second signals thereby reduce at least two of the delay spreads.

20. The method set forth in claim 19 including the further steps of determining a weighting factor of at least one of the selected points and using the weighting factor to modify at least one of said offset delays such that a first delay spread is more greatly reduced than a second delay spread.