TRANSMISSIONS TO MULTIPLE STATIONS IN WIRELESS COMMUNICATION SYSTEMS

• US 20080112351A1
• Filed: 11/13/2007
• Published: 05/15/2008
• Est. Priority Date: 11/15/2006
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Nanda, Sanjiv, Surineni, Shravan K.
• Granted Patent: US 8,305,948 B2
• Time in Patent Office: Days
• US Class Current: 370/312
• CPC Class Codes: H04W 74/0816 with collision avoidance

Abstract

Systems and methodologies are described that facilitate coordinating and conducting transmissions to multiple stations in a wireless communication system during a single transmission opportunity. A holder of a transmission opportunity can communicate a request-to-send message or a self-addressed clear-to-send message to one or more stations to establish the transmission opportunity. Subsequently, data transmissions with respective stations can be initiated by transmitting request-to-send messages to the respective stations. At each receiving station, the source address of a received request-to-send message is compared to the address of the holder of the transmission opportunity. If the addresses match for a given request-to-send message, the receiving station transmits a clear-to-send message to the holder of the transmission opportunity in response to the request-to-send message.

Claims

1. A method for coordinating and conducting transmissions to a plurality of users during a transmission opportunity, comprising:

transmitting a frame to one or more users selected from the group consisting of a clear-to-send frame and a request-to-send frame, the frame establishes a transmitter as a holder of a transmission opportunity and comprises an address of the transmitter and a transmission interval;

transmitting a request-to-send frame to a first user during the transmission interval, the request-to-send frame indicates the address of the transmitter and an address of the first user;

receiving a clear-to-send frame from the first user responsive to the request-to-send frame;

transmitting data to the first user;

transmitting a request-to-send frame to a second user during the transmission interval, the request-to-send frame indicates the address of the transmitter and an address of the second user;

receiving a clear-to-send frame from the second user responsive to the request-to-send frame; and

transmitting data to the second user.

2. The method of claim 1, wherein the transmitting a frame to one or more users comprises transmitting a clear-to-send frame to the one or more users that includes the address of the transmitter as a source and receiver of the clear-to-send frame.

3. The method of claim 1, wherein the transmitting a frame to one or more users comprises:

transmitting a request-to-send frame to a user in the one or more users that includes the address of the transmitter as a source of the request-to-send frame and an address of the user as a receiver of the request-to-send frame; and

receiving a clear-to-send frame from the user responsive to the request-to-send frame.

4. The method of claim 3, wherein the request-to-send frame transmitted to the user includes a request for a transmission interval and the clear-to-send frame received from the user in response to the request-to-send frame indicates a transmission interval.

5. The method of claim 1, further comprising determining the transmission interval by determining a length of time required for transmission of the data to the first user and the second user.

6. The method of claim 1, further comprising determining the transmission interval by determining an allowable transmission interval length for one or more transmission classes to be used for transmitting the data to the first user and the second user.

7. The method of claim 1, wherein the respective request-to-send frames transmitted to the first user and the second user include respective requests for feedback from the first user and the second user.

8. The method of claim 7, wherein the respective clear-to-send frames received from the first user and the second user responsive to the respective request-to-send frames include feedback indicated by the respective requests for feedback.

9. The method of claim 8, wherein the data is respectively transmitted to the first user and the second user using the feedback included in the clear-to-send frames respectively received by the first user and the second user.

10. The method of claim 8, further comprising:

applying beamforming to the data to be transmitted to the first user based at least in part on feedback included in the clear-to-send frame received from the first user; and

applying beamforming to the data to be transmitted to the second user based at least in part on feedback included in the clear-to-send frame received from the second user.

11. A wireless communications apparatus, comprising:

a memory that stores data relating to an address of the wireless communications apparatus and a transmission opportunity (TXOP) duration; and

a processor configured to transmit at least one of a clear-to-send message or a request-to-send message to one or more stations, the at least one message comprises the address of the wireless communications apparatus;

transmit respective request-to-send messages indicating the address of the wireless communication apparatus to respective stations;

receive respective clear-to-send messages from the respective stations; and

transmit data to the respective stations.

12. The wireless communications apparatus of claim 11, wherein the processor is configured to transmit a clear-to-send-to-self message that comprises the address of the wireless communications apparatus and the TXOP duration.

13. The wireless communications apparatus of claim 11, wherein the processor is configured to transmit a request-to-send message that comprises the address of the wireless communications apparatus and the TXOP duration to a first station and to receive a clear-to-send message from the first station responsive to the request-to-send message.

14. The wireless communications apparatus of claim 11, wherein the processor is configured to transmit a request-to-send message that comprises the address of the wireless communications apparatus to a first station and to receive a clear-to-send message that comprises the TXOP duration from the first station responsive to the request-to-send message.

15. The wireless communications apparatus of claim 11, wherein the processor is further configured to determine the TXOP duration as a length of time required for transmission of data to the respective stations.

16. The wireless communications apparatus of claim 11, wherein the processor is further configured to determine the TXOP duration as an allowable transmission interval length for one or more transmission classes to be used for transmitting data to the respective stations.

17. The wireless communications apparatus of claim 11, wherein the processor is further configured to embed respective requests for feedback into the request-to-send messages to be transmitted to the respective stations for which data is to be transmitted.

18. The wireless communications apparatus of claim 17, wherein the processor is further configured to identify feedback in the respective received clear-to-send messages received from the respective stations in response to the requests for feedback embedded in the respective request-to-send messages.

19. The wireless communications apparatus of claim 18, wherein the processor is further configured to transmit data to the respective stations using the feedback identified in the respective clear-to-send messages.

20. The wireless communications apparatus of claim 18, wherein the processor is further configured to transmit data to the respective stations by beamforming signals containing the data based at least in part on the feedback included in the respective clear-to-send messages.

21. The wireless communications apparatus of claim 11, wherein the stations to which data is to be transmitted comprise a wireless access point.

22. The wireless communications apparatus of claim 11, wherein the stations to which data is to be transmitted comprise at least one wireless terminal and the processor is configured to transmit data to the terminal using direct link setup (DLS).

23. An apparatus that facilitates assigning a plurality of users for communication during a transmission interval, comprising:

means for transmitting one or more of a clear-to-send message and a request-to-send message to one or more stations that includes a transmitter address, a receiver address, and a length of the transmission interval;

means for transmitting request-to-send messages to respective stations for which data is to be transmitted; and

means for receiving clear-to-send messages from the respective stations in response to the request-to-send messages.

24. A computer-readable medium, comprising:

code for causing a computer to identify a communication interval;

code for causing a computer to transmit a message to one or more users in a plurality of users to establish a transmission opportunity for communication with the plurality of users during the communication interval;

code for causing a computer to communicate a request message to a first user in the plurality of users during the communication interval;

code for causing a computer to receive a response message from the first user;

code for causing a computer to communicate a request message to a second user in the plurality of users during the communication interval; and

code for causing a computer to receive a response message from the second user.

25. An integrated circuit that executes computer-executable instructions for transmitting to multiple stations during a transmission period, the instructions comprising:

establishing a transmission opportunity at least in part by transmitting a message to one or more stations in the plurality of stations that specifies a transmitter address and a length of the transmission period;

transmitting request-to-send messages to respective stations in the plurality of stations;

receiving clear-to-send messages from the respective stations in response to the request-to-send messages; and

communicating data to the respective stations.

26. A method for initiating and conducting communication in a wireless communication system, comprising:

detecting one or more clear-to-send frames or request-to-send frames, the one or more frames indicate an address of an entity that holds a transmission opportunity and a duration of the transmission opportunity;

setting a network allocation vector (NAV) based on the duration of the transmission opportunity;

receiving a request-to-send frame that indicates an address of an entity that transmitted the request-to-send frame;

determining if the address of the entity that transmitted the request-to-send frame is the same as the address of the entity that holds the transmission opportunity; and

if the addresses are the same, transmitting a clear-to-send frame to the entity that transmitted the request-to-send frame.

27. The method of claim 26, wherein the detecting one or more clear-to-send frames or request-to-send frames comprises detecting a clear-to-send frame that indicates the address of the entity that holds the transmission opportunity as an addressee of the clear-to-send frame.

28. The method of claim 26, wherein the detecting one or more clear-to-send frames or request-to-send frames comprises:

detecting a request-to-send frame that indicates the address of the entity that holds the transmission opportunity as a transmitter of the request-to-send frame; and

transmitting a clear-to-send frame to the entity that holds the transmission opportunity in response to the request-to-send frame.

29. The method of claim 26, wherein the detecting one or more clear-to-send frames or request-to-send frames comprises detecting one or more of a request-to-send frame transmitted from the entity that holds the transmission opportunity to a target station and a clear-to-send frame transmitted from the target station to the entity that holds the transmission opportunity.

30. The method of claim 26, further comprising preventing updating the NAV if the address of the entity that transmitted the request-to-send frame is the same as the address of the entity that holds the transmission opportunity.

31. The method of claim 26, wherein the transmitting a clear-to-send frame comprises transmitting the clear-to-send frame approximately after a short interframe spacing (SIFS) period.

32. The method of claim 26, wherein the receiving a request-to-send frame comprises receiving a request for feedback embedded in the received request-to-send frame.

33. The method of claim 32, wherein the transmitting a clear-to-send frame comprises:

embedding feedback requested in the request-to-send frame into a clear-to-send frame; and

if the address of the entity that transmitted the request-to-send frame is the same as the address of the entity that holds the transmission opportunity, transmitting the clear-to-send frame.

34. The method of claim 26, further comprising receiving data from the entity that holds the transmission opportunity.

35. The method of claim 26, wherein the receiving a request-to-send frame comprises:

determining whether the NAV has been reset or has expired; and

if the NAV has been reset or has expired, discarding the request-to-send frame.

36. A wireless communications apparatus, comprising:

a memory that stores data relating to a NAV and an address of a transmitter; and

a processor configured to detect one or more initial messages that indicate the address of the transmitter, one or more transmission classes to be utilized by the transmitter, and transmission intervals respectively corresponding to the transmission classes;

set the NAV based on the transmission intervals;

receive a subsequent request-to-send message;

compare a source address of the subsequent request-to-send message with the address of the transmitter; and

transmit a clear-to-send message to the transmitter upon determining that the source address of the subsequent request-to-send message is the same as the address of the transmitter.

37. The wireless communications apparatus of claim 36, wherein the processor is further configured to detect one or more initial messages that comprise a clear-to-send message that indicates the address of the transmitter as an addressee of the clear-to-send message.

38. The wireless communications apparatus of claim 36, wherein the memory further stores data relating to an address of the wireless communications apparatus, and the processor is further configured to detect one or more initial messages that comprise a request-to-send frame that indicates the address of the transmitter as a source of the request-to-send message and the address of the wireless communications apparatus as the addressee of the request-to-send message.

39. The wireless communications apparatus of claim 38, wherein the processor is further configured to transmit a clear-to-send message to the transmitter in response to the request-to-send message.

40. The wireless communications apparatus of claim 39, wherein the memory further stores data relating to one or more transmission intervals and the processor is further configured to communicate the transmission intervals to the transmitter in the clear-to-send message.

41. The wireless communications apparatus of claim 36, wherein the processor is further configured to detect one or more initial messages that comprise at least one of a request-to-send message transmitted from the transmitter to an entity other than the wireless communications apparatus or a clear-to-send message transmitted from the entity other than the wireless communications apparatus to the transmitter.

42. The wireless communications apparatus of claim 36, wherein the processor is further configured to abstain from updating the NAV upon receiving a subsequent request-to-send message from the transmitter.

43. The wireless communications apparatus of claim 36, wherein the processor is further configured to transmit the clear-to-send message approximately after a short interframe spacing (SIFS) period upon receiving the subsequent request-to-send message.

44. The wireless communications apparatus of claim 36, wherein the processor is further configured to receive a request for feedback embedded in the subsequent request-to-send message.

45. The wireless communications apparatus of claim 44, wherein the processor is further configured to provide requested feedback requested in a clear-to-send message transmitted in response to a subsequent request-to-send message.

46. The wireless communications apparatus of claim 36, wherein the processor is further configured to receive data from the transmitter upon transmitting the clear-to-send message to the transmitter.

47. The wireless communications apparatus of claim 36, wherein the processor is further configured to determine whether the NAV has been reset or has expired and to discard a subsequent request-to-send message upon a positive determination.

48. An apparatus that facilitates determining intervals for communication in a wireless communication system, comprising:

means for detecting one or more of a clear-to-send frame and a request-to-send frame, the one or more frames indicate a transmitter address and one or more transmission interval durations;

means for receiving a request-to-send frame subsequent to the detecting one or more of a clear-to-send frame and a request-to-send frame;

means for comparing an address of a station that transmitted the request-to-send frame with the transmitter address; and

means for transmitting a clear-to-send frame to the station that transmitted the request-to-send frame if the address of the station that transmitted the request-to-send frame is the same as the transmitter address.

49. A computer-readable medium, comprising:

code for causing a computer to detect a message that establishes a transmission opportunity;

code for causing a computer to receive a request message upon establishment of the transmission opportunity;

code for causing a computer to determine whether the request message was transmitted by a holder of the transmission opportunity; and

code for causing a computer to transmit a response message if the request message was transmitted by the holder of the transmission opportunity.

50. An integrated circuit that executes computer-executable instructions for communicating in a wireless communication system during a transmission opportunity, the instructions comprising:

detecting a message transmitted to one or more stations that specifies a transmitter address and a length of a transmission period;

receiving a request-to-send message during the transmission period;

if an address of a station that transmitted the request to-send-message is the same as the transmitter address;

transmitting a clear-to-send message in response to the request-to-send message; and

receiving data from the transmitter upon transmitting the clear-to-send message.