WIRELESS DEVICE AND METHODS FOR OPPORTUNISTIC SCHEDULING IN A CONTENTION-BASED WIRELESS NETWORK

• US 20100329131A1
• Filed: 06/25/2009
• Published: 12/30/2010
• Est. Priority Date: 06/25/2009
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Lin, Xintian E., Li, Qinghua, Oyman, Ozgur
• Granted Patent: US 8,472,467 B2
• Time in Patent Office: Days
• US Class Current: 370/252
• CPC Class Codes: H04W 74/085 collision avoidance

Abstract

Embodiments of a wireless device and method for channel access are generally described herein. In some embodiments, the wireless device is configured to measure channel quality and set a backoff delay for channel access based on the channel quality. Shorter backoff delays are set for better channel quality and longer backoff delays are set for poorer channel quality.

Claims

1. A wireless device configured to operate in a network that implements a random channel-access protocol, wherein the wireless device is configured to:

measure channel quality; and

set a backoff delay for channel access based on the channel quality, wherein shorter backoff delays are set for better channel quality and longer backoff delays are set for poorer channel quality.

2. The wireless device of claim 1 wherein the wireless device is configured to measure the channel quality of a random-access channel between the wireless device and an access point based on a request-to-send (RTS) packet, and

wherein the wireless device is configured to send a clear-to-send (CTS) packet on the random-access channel in response to the RTS packet at a time after the backoff delay is set.

3. The wireless device of claim 2 wherein the wireless device is configured to set the backoff delay based on a channel quality relative to channel qualities of the random-access channel associated with other wireless devices in the network.

4. The wireless device of claim 3 further comprising rate-adaptation circuitry to adapt a data rate based on the channel quality, wherein higher data rates are used for better channel quality and lower data rates are used for poorer channel quality, and

wherein throughput of the network is increased by limiting channel access to wireless devices with poorer channel quality that would transmit at a lower data rate.

5. The wireless device of claim 3 wherein the wireless device is configured to:

receive channel quality information from one or more of the other wireless devices over a low-latency radio link established directly with one or more of the other wireless devices; and

determine the channel quality relative to the channel qualities of the random-access channel associated with the other wireless devices.

6. The wireless device of claim 5 wherein the low-latency radio link utilizes a different frequency channel than a channel used for the random-access channel, and

wherein information about the channel quality is received from the one or more of the other wireless devices over the low-latency radio link during a contention phase of the random channel-access protocol.

7. The wireless device of claim 6 further comprising:

a first transceiver for communicating with the access point over the random-access channel using a first frequency channel; and

a second transceiver for communicating directly with one or more of the other wireless devices over the low-latency radio link using a second frequency channel.

8. The wireless device of claim 3 wherein the access point is configured to provide channel quality related to other wireless devices to the wireless device for use by the wireless device in determining the relative channel quality.

9. The wireless device of claim 3 wherein wireless devices of the network having the better relative channel quality utilize shorter backoff delays and the wireless devices of the network having poorer relative channel quality utilize longer back off delays for channel access, allowing wireless devices with the better relative channel quality to gain access to the channel more quickly and communicate data packets at higher data rates than wireless devices with the poorer relative channel quality.

10. The wireless device of claim 9 wherein the wireless device is further configured to further adjust the backoff delay based on a random exponential backoff time to help prevent collisions between wireless devices having similar channel qualities.

11. The wireless device of claim 9 wherein the backoff delay is further adjusted to implement a proportional fairness access technique to help ensure fair access opportunities for wireless devices having consistently poorer channel quality.

12. The wireless device of claim 3 wherein the network is a multichannel network,

wherein the access point is configured to broadcast the RTS packet on a plurality of random-access channels, each channel utilizing a different frequency channel;

and

wherein wireless devices are configured to;

measure a channel quality for two or more of the random-access channels based on receipt of the RTS packet;

select one of the random-access channels based on the measured channel quality;

set the backoff delay based on a relative channel quality of the selected channel; and

send a CTS packet on the selected channel at a time after the backoff delay.

13. The wireless device of claim 1 wherein the wireless network is a contention-based network and the random-access protocol comprises a Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA) protocol operating in accordance with one of IEEE 802.11 standards.

14. A method for channel access in a network that implements a random channel-access protocol, the method comprising:

measuring channel quality based on a broadcasted request-to-send (RTS) packet;

determining a relative channel quality from the measured channel quality and a channel quality of one or more other wireless devices; and

setting a backoff delay for channel access based on the relative channel quality, wherein shorter backoff delays are set for better channel quality and longer backoff delays are set for poorer channel quality.

15. The method of claim 14 further comprising:

receiving the channel quality of one or more other wireless devices from an access point in a clear-to-send (CTS) packet.

16. The method of claim 14 further comprising:

receiving the channel quality of one or more other wireless devices over a low-latency radio link established directly with one or more of the other wireless devices.

17. The method of claim 16 further comprising:

adjusting the backoff delay based on a random exponential backoff time to help prevent collisions between wireless devices having similar relative channel qualities; and

further adjusting the backoff delay to implement a proportional fairness access technique to help ensure fair access opportunities for wireless devices having consistently poorer channel quality.

18. A central scheduler for scheduling channel access in a contention-based network, the central scheduler configured to:

broadcast a request-to-send (RTS) packet on one or more random-access channels, each channel utilizing a different frequency channel; and

receive clear-to-send (CTS) packets from wireless devices at times after a backoff delay is set,

wherein wireless devices are configured to set the backoff delay based on a relative channel quality of one of the random access channels.

19. The central scheduler of claim 18 wherein the wireless devices are configured to:

measure a channel quality for two or more of the random-access channels based on receipt of the RTS packet;

select one of the random-access channels based on the measured channel quality;

set the backoff delay based on a relative channel quality of the selected channel; and

send the CTS packet on the selected channel at a time after the backoff delay is set,

wherein shorter backoff delays are set for better channel quality and longer backoff delays are set for poorer channel quality.

20. The central scheduler of claim 18 wherein the central scheduler is configured to grant channel access more quickly to wireless devices having better relative channel quality and to grant channel access less quickly to wireless devices having poorer relative channel quality.