SCHEDULING AND PROTECTION OF QUIET PERIODS IN A QUIET ZONE FOR INCUMBENT SIGNAL DETECTION

• US 20110299509A1
• Filed: 02/02/2010
• Published: 12/08/2011
• Est. Priority Date: 02/27/2009
• Status: Active Grant

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Wang, Jianfeng, Gaddam, Vasanth
• Granted Patent: US 8,787,324 B2
• Time in Patent Office: Days
• US Class Current: 370/336
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks
• CPC Class Codes: H04W 72/23 in the downlink direction of a wireless link, i.e. towards a terminal

Abstract

A method and system for scheduling and protecting quiet periods (QP) in a quiet zone (105) for incumbent signal (121) detection in a wireless communications system. The communication system includes a plurality of wireless networks (103, 104), each of the plurality of wireless networks contains at least a master device (101, 401) and a client device (111, 411). In each of the plurality of wireless networks, the master device (101, 401) transmits a beacon (402) that contains a QP schedule (500) and a reservation of a time slot (405) for the client device (411). The client device (111, 411) transmits a request-to-quiet (RTQ) message (412) during the time slot, wherein the RTQ message (412) includes the client device'"'"'s QP schedule information. The master and client devices within the quiet zone (105) keep quiet during scheduled quiet periods according to the QP schedule information contained in the received beacons and RTQ messages.

Claims

1. A method for scheduling and protecting quiet periods (QP) in a quiet zone (105) in order to detect an incumbent signal (121) in a wireless communications system that includes a plurality of wireless networks (103, 104), each of the plurality of wireless networks containing at least a master device (101, 401) and a client device (111, 411), the method comprising:

transmitting a beacon (402) by the master device (101, 401), wherein the beacon (402) contains a first QP schedule (500) and a reservation of a time slot (405) for the client device (111, 411);

transmitting a request-to-quiet (RTQ) message (412) by the client device (111, 411) during the time slot, wherein the RTQ message (412) includes a second QP schedule (706); and

keeping quiet by the master device and the client device within the quiet zone (105) during quiet periods according to information in the first and second QP schedules.

2. The method of claim 1, further comprising adjusting the first or second QP schedule according to a targeted beacon transmission time (TBTT) of another one of the plurality of wireless networks in order to avoid a collision between the quiet periods and beacon transmissions by the another one of the plurality of wireless networks.

3. The method of claim 2, further comprising reporting and updating the TBTT by listening to beacon transmissions from the another one of the plurality of wireless networks.

4. The method of claim 1, further comprising:

transmitting a decline-to-quiet (DTQ) message (922) by a master device (902) in another one of the plurality of wireless networks if there is a collision between the quiet periods and beacon transmissions by the another one of the plurality of wireless networks;

responding to the DTQ message (922) with a respond-to-decline message (923);

adjusting the first or second QP schedule to avoid the collision; and

issuing a new QP schedule in the beacon or the RTQ message (924).

5. The method of claim 1, wherein the reserved time slot (405) is a time slot in a neighborhood quiet request period (NQRP) (403) immediately following the beacon (402), and the master device (401) includes a NQRP information element (600) in the beacon (402) for time slot reservations for the client device (411), wherein the NQRP information element (600) comprises an address list (604) specifying a group of devices chosen for participating in a quiet zone to transmit the RTQ message within the neighborhood quiet request period.

6. The method of claim 1, further comprising:

detecting an incumbent signal (121) by making a plurality of measurements (1101, 1102, 1103, 1104) during the quiet periods; and

discarding a measurement (1102) of the plurality of measurements if another signal (1002) is detected during the measurement.

7. A system for detecting an incumbent signal (121) of a wireless communications medium, the system including a plurality of wireless networks (103, 104), the system comprising:

a master device (101, 401) configured to transmit a beacon (402), the beacon (402) containing a first quiet period (QP) schedule (500) and a reservation of a time slot for a client device (111, 411), the client device (402) being configured to transmit a request-to-quiet (RTQ) message (412) during the time slot, wherein the RTQ message (412) includes a second QP schedule (706), and wherein the master and client devices within a quiet zone (105) are configured to keep quiet during quiet periods according to information in the first and second QP schedule.

8. The system of claim 7, wherein the master device (101) is further configured to adjust the first or second QP schedule according to a targeted beacon transmission time (TBTT) of another one of the plurality of wireless networks in order to avoid a collision between the quiet periods and beacon transmissions by the another one of the plurality of wireless networks.

9. The system of claim 8, wherein the master and client devices are further configured to report and update the TBTT by listening to beacon transmissions from the another one of the plurality of wireless networks.

10. The system of claim 7, wherein the master device (902) is further configured to:

transmit a decline-to-quiet (DTQ) message (922) to a device (901, 911) of another one of the plurality of wireless networks that transmits the beacon or the RTQ message (921) if there is a collision between the quiet periods and the beacon of the master device; and

the device (901, 911) that transmits the beacon or the RTQ message is further configured to;

respond to the DTQ message (922) with a respond-to-decline message (923);

adjust the first or second QP schedule to avoid the collision; and

issue a new QP schedule in the beacon or the RTQ message (924).

11. The system of claim 7, wherein the reserved time slot (405) is a time slot in a neighborhood quiet request period (NQRP) (403) immediately following the beacon (402), and the master device (101, 401) is further configured to include a NQRP information element (600) in the beacon (402) for time slot reservations for the client device (111, 411), and wherein the NQRP information element (600) comprises an address list (604) specifying a group of devices chosen for participating in the quiet zone to transmit the RTQ message within the neighborhood quiet request period.

12. The system of claim 7, wherein each of the master and client devices further comprises:

a spectrum manager (204) for selecting or deselecting an operating frequency channel;

a primary signal sensing module (202) for detecting an incumbent signal;

a secondary signal transceiver (201) for receiving signals from the plurality of wireless networks; and

a sensing scheduler and analyzer (203) for scheduling a plurality of signal measurements (1101, 1102, 1103, 1104) during the quiet periods and

discarding a measurement (1102) of the plurality of measurements if another signal (1002) is detected during the measurement (1102).

13. The system of claim 12, wherein the master device (301) further comprises a means for accessing a spectrum database (341) over the Internet (331).

14. The system of claim 13, wherein the spectrum manager (204) selects or deselects an operating frequency channel based on consolidated signal measurements from devices of the plurality of wireless networks and the spectrum database (341).

15. A computer readable storage medium having stored thereon computer executable code, when executed, causing a processor in a master device (101, 401) and a client device (111, 411) to perform a process of scheduling and protecting quiet periods (QP) in a quiet zone (105) in order to detect an incumbent signal (121) in a wireless communications system, the process comprising:

transmitting a beacon (402) by the master device (101, 401), wherein the beacon (402) contains a first QP schedule (500) and a reservation of a time slot (405) for the client device (111, 411);

transmitting a request-to-quiet (RTQ) message (412) by the client device (411) during the time slot, wherein the RTQ message (412) comprises a second QP schedule (706); and

keeping quiet by the master and client devices within the quiet zone (105) during quiet periods according to information in the first and second QP schedule.

16. The computer readable storage medium of claim 15, wherein the process further comprises adjusting the first or second QP schedule according to a targeted beacon transmission time (TBTT) of another one of the plurality of wireless networks in order to avoid a collision between the quiet periods and beacon transmissions by the another one of the plurality of wireless networks.

17. The computer readable storage medium of claim 16, wherein the process further comprises reporting and updating the TBTT by listening to beacon transmissions from the another one of the plurality of wireless networks.

18. The computer readable storage medium of claim 15, wherein the process further comprises:

transmitting a decline-to-quiet (DTQ) message (922) by a master device (902) in another one of the plurality of wireless networks if there is a collision between the quiet periods and beacon transmissions by the one of the plurality of wireless networks;

responding to the DTQ message (922) with a respond-to-decline message (923);

adjusting the first or second QP schedule to avoid the collision; and

issuing a new QP schedule in the beacon or the RTQ message (924).

19. The computer readable storage medium of claim 15, wherein the reserved time slot (405) is a time slot in a neighborhood quiet request period (NQRP) (403) immediately following the beacon (402), and the master device (401) includes a NQRP information element (600) in the beacon (402) for time slot reservations for the client device (411), wherein the NQRP information element (600) comprises an address list (604) specifying a group of devices chosen for participating in a quiet zone to transmit the RTQ message within the neighborhood quiet request period.

20. The computer readable storage medium of claim 15, wherein the process further comprises detecting an incumbent signal (121) by making a plurality of measurements (1101, 1102, 1103, 1104) during the quiet periods, and discarding a measurement (1102) of the plurality of measurements if another signal (1002) is detected during the measurement.