Scheduling and protection of quiet periods in a quiet zone for incumbent signal detection

• US 8,787,324 B2
• Filed: 02/02/2010
• Issued: 07/22/2014
• Est. Priority Date: 02/27/2009
• Status: Active Grant

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips N.V.
• Inventors: Wang, Jianfeng, Gaddam, Vasanth
• Primary Examiner(s): Rinehart, Mark
• Assistant Examiner(s): SOLINSKY, PETER G
• Application Number:
  US13/201,654
• Publication Number:
  US 20110299509A1
• Time in Patent Office: 1,631 Days
• Field of Search: 370/328, 370/329, 370/336, 370/345, 370/498, 370/348, 370/351, 370/254, 370/431
• 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 in order to detect an incumbent signal in a wireless communications system that includes a plurality of wireless networks, each of the plurality of wireless networks containing at least a master device and a client device, the method comprising:

transmitting a beacon by a master device of one of the plurality of wireless networks, wherein the beacon contains a first QP schedule and a reservation of a time slot for a client device of the one of the plurality of wireless networks;

transmitting a request-to-quiet (RTQ) message by the client device of the one of the plurality of wireless networks during the time slot, wherein the RTQ message includes a second QP schedule; and

keeping quiet by the master device and the client device of each of the plurality of wireless networks within the quiet zone during quiet periods according to information in the first and second QP schedules;

wherein the incumbent signal is transmitted by a primary user device; and

wherein the master and client devices are secondary user devices.

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 other 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 other one of the plurality of wireless networks.

4. The method of claim 1, further comprising

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

responding to the DTQ message with a respond-to-decline message;

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

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

5. The method of claim 1, wherein the reserved time slot is a time slot in a neighborhood quiet request period (NQRP) immediately following the beacon, and the master device of the one of the plurality of wireless networks includes a NQRP information element in the beacon for time slot reservations for the client device of the one of the plurality of wireless networks, wherein the NQRP information element comprises an address list 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 by making a plurality of measurements during the quiet periods; and

discarding a measurement of the plurality of measurements if another signal is detected during the measurement.

7. A system for detecting an incumbent signal of a wireless communications medium, the system including a plurality of wireless networks, each of the plurality of wireless networks containing at least a master device and a client device, the system comprising:

a master device of one of the plurality of wireless networks configured to transmit a beacon, the beacon containing a first quiet period (QP) schedule and a reservation of a time slot for a client device of the one of the plurality of wireless networks, the client device of the one of the plurality of wireless networks being configured to transmit a request-to-quiet (RTQ) message during the time slot, wherein the RTQ message includes a second QP schedule, and wherein master and client devices of each of the plurality of wireless networks within a quiet zone are configured to keep quiet during quiet periods according to information in the first and second QP schedule;

wherein the incumbent signal is transmitted by a primary user device; and

wherein the master and client devices are secondary user devices.

8. The system of claim 7, wherein the master device of the one of the plurality of wireless networks 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 other one of the plurality of wireless networks.

9. The system of claim 8, wherein the master and client devices of the one of the plurality of wireless networks are further configured to:

report and update the TBTT by listening to beacon transmissions from the other one of the plurality of wireless networks.

10. The system of claim 7, wherein a master device of another one of the plurality of wireless networks is further configured to:

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

the device that transmits the beacon or the RTQ message is further configured to;

respond to the DTQ message with a respond-to-decline message;

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

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

11. The system of claim 7, wherein the reserved time slot is a time slot in a neighborhood quiet request period (NQRP) immediately following the beacon, and the master device of the one of the plurality of wireless networks is further configured to include a NQRP information element in the beacon for time slot reservations for the client device of the one of the plurality of wireless networks, and wherein the NQRP information element comprises:

an address list 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 for selecting or deselecting an operating frequency channel;

a primary signal sensing module for detecting an incumbent signal;

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

a sensing scheduler and analyzer for scheduling a plurality of signal measurements during the quiet periods and

discarding a measurement of the plurality of measurements if another signal is detected during the measurement.

13. The system of claim 12, wherein each master device of the plurality of wireless networks further comprises a means for accessing a spectrum database over the Internet.

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

15. A non-transitory computer readable storage medium having stored thereon computer executable code, that when executed, causing a processor to perform a process of scheduling and protecting quiet periods (QP) in a quiet zone in order to detect an incumbent signal in a wireless communications system that includes a plurality of wireless networks, each of the plurality of wireless networks containing at least a master device and a client device, the process comprising:

transmitting a beacon by a master device of one of the plurality of wireless networks, wherein the beacon contains a first QP schedule and a reservation of a time slot for a client device of the one of the plurality of wireless networks;

transmitting a request-to-quiet (RTQ) message by the client device of the one of the plurality of wireless networks during the time slot, wherein the RTQ message comprises a second QP schedule; and

keeping quiet by master and client devices of each of the plurality of wireless networks within the quiet zone during quiet periods according to information in the first and second QP schedule;

wherein the incumbent signal is transmitted by a primary user device; and

wherein the master and client devices are secondary user devices.

16. The non-transitory 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 other one of the plurality of wireless networks.

17. The non-transitory computer readable storage medium of claim 16, wherein the process further comprises:

reporting and updating the TBTT by listening to beacon transmissions from the other one of the plurality of wireless networks.

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

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

responding to the DTQ message with a respond-to-decline message;

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

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

19. The non-transitory computer readable storage medium of claim 15, wherein the reserved time slot is a time slot in a neighborhood quiet request period (NQRP) immediately following the beacon, and the master device of the one of the plurality of wireless networks includes a NQRP information element in the beacon for time slot reservations for the client device of the one of the plurality of wireless networks, wherein the NQRP information element comprises:

an address list 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 non-transitory computer readable storage medium of claim 15, wherein the process further comprises:

detecting an incumbent signal by making a plurality of measurements during the scheduled quiet periods; and

discarding a measurement of the plurality of measurements if another signal is detected during the measurement.