Wireless communication method and apparatus for dynamically adapting packet transmission rates

• US 20060187885A1
• Filed: 09/30/2005
• Published: 08/24/2006
• Est. Priority Date: 02/23/2005
• Status: Active Grant

• Current Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: Roy, Vincent, Cave, Christopher
• Granted Patent: US 8,085,733 B2
• Time in Patent Office: Days
• US Class Current: 370/332
• CPC Class Codes: H04L 1/0002 by adapting the transmission rate
• CPC Class Codes: H04L 1/0015 characterised by the adaptation strategy
• CPC Class Codes: H04L 1/1867 Arrangements specially adapted for the transmitter end
• CPC Class Codes: H04L 1/203 Details of error rate determination, e.g. BER, FER or WER
• CPC Class Codes: H04W 28/18 Negotiating wireless communication parameters

Abstract

A method and apparatus for use by a first transceiver, (e.g., wireless transmit/receive unit (WTRU), access point (AP), node) for adjusting the transmission rate of packets transmitted to a second transceiver based on signals the first transceiver receives from the second transceiver. In one embodiment, a transmission packet error rate (Tx PER) process is used to adjust the packet transmission rate. In another embodiment, a relative signal strength indicator (RSSI)-based process is used to determine the RSSI of packets received at the first transceiver from the second transceiver for adjusting the packet transmission rate. In another embodiment, transmission quality indicators are measured at the second transceiver and are sent to the first transceiver, which derives a new packet transmission rate therefrom. The Tx PER and RSSI-based processes may be used individually, in combination, or in conjunction with other processes.

Claims

1. In a wireless communication system including a plurality of wireless transmit/receive units (WTRUs), a method for adjusting a packet transmission rate of a WTRU, the method comprising:

(a) a first one of the WTRUs determining a packet transmission rate for transmitting an available packet;

(b) the first WTRU transmitting the packet to a second one of the WTRUs at the transmission rate selected in step (a); and

(c) the first WTRU invoking a relative signal strength indicator (RSSI) training process based on the transmitted packet.

2. The method of claim 1 further comprising:

(d) the first WTRU determining whether or not there is at least one valid RSSI measurement available for at least one packet that was received from the second WTRU within a predetermined time period.

3. The method of claim 2 wherein if the determination of step (d) is positive, the method further comprising:

(e) the first WTRU determining the RSSI level of the at least one available RSSI measurement; and

(f) the first WTRU determining whether the RSSI level determined in step (e) was previously used by the RSSI training process within the predetermined time period.

4. The method of claim 3 wherein if the determination of step (f) is positive, the method further comprising:

(g) the first WTRU setting the packet transmission rate to a preferred packet transmission rate established for the RSSI level, as determined by the RSSI training process.

5. The method of claim 2 wherein if the determination of step (d) is negative, the method further comprising:

(e) the first WTRU invoking a transmission packet error rate (PER)-based process to determine the packet transmission rate.

6. The method of claim 3 wherein if the determination of step (f) is negative, the method further comprising:

(g) the first WTRU invoking a transmission packet error rate (PER)-based process to determine the packet transmission rate.

7. The method of claim 1 wherein the RSSI training process comprises:

(i) if the second WTRU sent an acknowledgement (ACK) message to the first WTRU in response to receiving the packet transmitted by the first WTRU, the first WTRU determining the RSSI level of an RSSI measurement of the ACK message and incrementing a count of total packet transmissions for the RSSI level; and

(ii) the first WTRU updating a preferred packet transmission rate for the RSSI level.

8. In a wireless communication system including at least one access point (AP) and at least one wireless transmit/receive unit (WTRU), a method for adjusting a packet transmission rate of the AP, the method comprising:

(a) the AP determining a packet transmission rate for transmitting an available packet;

(b) the AP transmitting the packet to the WTRU at the transmission rate selected in step (a); and

(c) the AP invoking a relative signal strength indicator (RSSI) training process based on the transmitted packet.

9. The method of claim 8 further comprising:

(d) the AP determining whether or not there is at least one valid RSSI measurement available for at least one packet that was received from the WTRU within a predetermined time period.

10. The method of claim 9 wherein if the determination of step (d) is positive, the method further comprising:

(e) the AP determining the RSSI level of the at least one valid RSSI measurement; and

(f) the AP determining whether the RSSI level determined in step (e) was previously used by the RSSI training process within the predetermined time period.

11. The method of claim 10 wherein if the determination of step (f) is positive, the method further comprising:

(g) the AP setting the packet transmission rate to a preferred packet transmission rate established for the RSSI level, as determined by the RSSI training process.

12. The method of claim 9 wherein if the determination of step (d) is negative, the method further comprising:

(e) the AP invoking a transmission packet error rate (PER)-based process to determine the packet transmission rate.

13. The method of claim 10 wherein if the determination of step (f) is negative, the method further comprising:

(g) the AP invoking a transmission packet error rate (PER)-based process to determine the packet transmission rate.

14. The method of claim 8 wherein the RSSI training process comprises:

(i) if the WTRU sent an acknowledgement (ACK) message to the AP in response to receiving the packet transmitted by the AP, the AP determining the RSSI level of an RSSI measurement of the ACK message and incrementing a count of total packet transmissions for the RSSI level; and

(ii) the AP updating a preferred packet transmission rate for the RSSI level.

15. An access point (AP) for adjusting a packet transmission rate, the AP comprising:

(a) a processor for determining the packet transmission rate of the AP; and

(b) a transmitter for transmitting a packet to a wireless transmit/receive unit (WTRU) at the rate determined by the processor, wherein the processor invokes a relative signal strength indicator (RSSI) training process on the packet and determines whether there is at least one RSSI measurement available for at least one packet that was received from the WTRU within a predetermined time period.

16. The AP of claim 15 wherein if there is at least one RSSI measurement available for at least one packet that was received from the WTRU within a predetermined time period, the processor determines the RSSI level of the at least one valid RSSI measurement and determines whether the RSSI level was previously used by the RSSI training process within the predetermined time period.

17. The AP of claim 15 wherein if there is not at least one RSSI measurement available for at least one packet that was received from the other WTRU within a predetermined time period, the processor invokes a transmission packet error rate (PER)-based process to determine the packet transmission rate.

18. The AP of claim 17 wherein if the RSSI level was not previously used by the RSSI training process within the predetermined time period, the processor invoking a transmission packet error rate (PER)-based process to determine the packet transmission rate.

19. The AP of claim 17 wherein if the RSSI level was previously used by the RSSI training process within the predetermined time period, the processor sets the packet transmission rate to a preferred level established for the RSSI level, as determined by the RSSI training process.

20. The AP of claim 15 wherein if the WTRU sent an acknowledgement (ACK) message in response to receiving the packet transmitted by the AP, the processor determines the RSSI level of an RSSI measurement of the ACK message, increments a count of transmissions for the RSSI level, and updates a preferred packet transmission rate for the RSSI level.

21. The AP of claim 15 wherein if an acknowledgement (ACK) message to the packet is not received by the AP in response to transmitting the packet, the processor determines whether there are any RSSI measurements available for any packets received from the second WTRU within the predetermined time period, and if so determines an RSSI level of said packets, and increments a count of total transmissions and a count of errors for the RSSI level, and updates a preferred packet transmission rate for the RSSI level.

22. An integrated circuit (IC) incorporated in a transceiver for adjusting the transceiver'"'"'s packet transmission rate, the IC comprising:

(a) a processor for determining the packet transmission rate of the transceiver;

(b) a transmitter for transmitting a packet to another transceiver at the rate determined by the processor, wherein the processor invokes a relative signal strength indicator (RSSI) training process on the packet and determines whether there is at least one RSSI measurement available for at least one packet that was received from the other transceiver within a predetermined time period.

23. The IC of claim 22 wherein if there is at least one valid RSSI measurement available for at least one packet that was received from the other transceiver within a predetermined time period, the processor determines the RSSI level of the at least one valid RSSI measurement and determines whether the RSSI level was previously used by the RSSI training process within the predetermined time period.

24. The IC of claim 22 wherein if there is not at least one RSSI measurement available for at least one packet that was received from the other transceiver within a predetermined time period, the processor invokes a transmission packet error rate (PER)-based process to determine the packet transmission rate.

25. The IC of claim 24 wherein if the RSSI level was not previously used by the RSSI training process within the predetermined time period, the processor invokes a transmission packet error rate (PER)-based process to determine the packet transmission rate.

26. The IC of claim 24 wherein if the RSSI level was previously used by the RSSI training process within the predetermined time period, the processor sets the packet transmission rate to a preferred level established for the RSSI level, as determined by the RSSI training process.

27. The IC of claim 22 wherein if the other transceiver sent an acknowledgement (ACK) message in response to receiving the packet, the processor determines the RSSI level of an RSSI measurement of the ACK message, increments a count of transmissions for the RSSI level, and updates a preferred packet transmission rate for the RSSI level.

28. The IC of claim 22 wherein if an acknowledgement (ACK) message to the packet is not received by the transceiver in response to transmitting the packet, the processor determines the RSSI level of an RSSI measurement of the ACK message, and updates a preferred packet transmission rate for the RSSI level.

29. A wireless transmit/receive unit (WTRU) for adjusting a packet transmission rate of packets the WTRU transmits via an antenna, the WTRU comprising:

(a) a transmitter for transmitting to a node at least one packet at a particular packet transmission rate;

(b) a receiver for receiving an acknowledgement (ACK) signal from the node that receives and acknowledges receipt of the at least one packet;

(c) a processor in communication with the transmitter and the receiver;

(d) a memory in communication with the processor;

(e) a transmission rates database in communication with the processor; and

(f) a plurality of packet transmission counters in communication with the processor.

30. The WTRU of claim 29 wherein the particular packet transmission rate is initially set to a default rate.

31. The WTRU of claim 29 wherein the packet transmission counters include a total successful packet transmission counter and an individual packet transmission error counter.

32. The WTRU of claim 31 wherein the total successful packet transmission counter is incremented when the receiver receives an ACK from the node.

33. The WTRU of claim 32 wherein the individual packet transmission error counter is reset to zero when the receiver receives an ACK from the node.

34. The WTRU of claim 33 wherein the packet transmission counters further include a total unsuccessful packet transmission counter, and the processor determines whether to adjust the particular packet transmission rate based on the sum of a first count value of the total successful packet transmission counter and a second count value of the total unsuccessful packet transmission counter.

35. The WTRU of claim 34 wherein the particular packet transmission rate is increased if the sum is greater than equal to a predetermined number of packets need for a packet transmission rate increase.

36. The WTRU of claim 35 wherein the particular packet transmission rate is increased if the ratio of the second count value over the first count value is less than a predetermined packet transmission rate increase ratio.

37. The WTRU of claim 29 wherein the packet transmission counters include a total unsuccessful packet transmission counter and an individual packet transmission error counter.

38. The WTRU of claim 37 wherein the total unsuccessful packet transmission counter and the individual packet transmission error counter are incremented when the receiver does not receive an ACK from the node after transmitting the at least one packet to the node.

39. The WTRU of claim 38 wherein the particular packet transmission rate is reduced by one or more supported rate steps designated in the transmission rates database based on a count value of the individual packet transmission error counter.

40. The WTRU of claim 29 wherein the packet transmission counters include a received signal strength indicator (RSSI) level total packet transmission counter.

41. The WTRU of claim 40 wherein an RSSI measurement of an ACK received from the node after transmitting the at least one packet to the node is retrieved from the memory if an RSSI training process was not previously used to determine the particular packet transmission rate, the RSSI measurement is determined by the processor and the RSSI level total packet transmission counter for the RSSI level is incremented.

42. The WTRU of claim 41 wherein a packet error rate (PER) for the RSSI level is updated in the memory and, if the PER is stable, a preferred packet transmission rate for the RSSI level is also updated in the memory.

43. The WTRU of claim 40 wherein an RSSI measurement of an ACK received from the node after transmitting the at least one packet to the node is retrieved from the memory if an RSSI training process was previously used to determine the particular packet transmission rate, the RSSI measurement is determined by the processor and the RSSI level total packet transmission counter for the RSSI level is incremented.

44. The WTRU of claim 43 wherein a packet error rate (PER) for the RSSI level is updated in the memory and, if the PER is stable, a preferred packet transmission rate for the RSSI level is also updated in the memory.

45. The WTRU of claim 40 wherein the RSSI level total packet transmission counter for the RSSI level is incremented if an RSSI training process was previously used to determine the particular packet transmission rate, and after transmitting the at least one packet to the node without receiving an ACK from the node.

46. The WTRU of claim 45 wherein a packet error rate (PER) for the RSSI level is updated in the memory and, if the PER is stable, a preferred packet transmission rate for the RSSI level is also updated in the memory.

47. The WTRU of claim 29 wherein the packet transmission counters include a received signal strength indicator (RSSI) level total packet transmission counter and an RSSI level packet transmission error counter.

48. The WTRU of claim 47 wherein an RSSI measurement of an ACK received from the node after transmitting the at least one packet to the node is retrieved from the memory, and the RSSI level total packet transmission counter for the RSSI level is incremented for the RSSI level of the ACK.

49. The WTRU of claim 47 wherein if the at least one packet is transmitted to the node without receiving an ACK from the node, a determination is made as to whether there are any RSSI measurements available for any packets received from the node within a last maximum duration time period, and if so, the RSSI level of the measurements is determined and the RSSI level total packet transmission counter and the RSSI level packet transmission error counter are incremented.

50. The WTRU of claim 49 wherein a packet error rate (PER) for the RSSI level is updated in the memory and, if the PER is stable, a preferred packet transmission rate for the RSSI level is also updated in the memory.

51. The WTRU of claim 29 wherein the WTRU sets the particular packet transmission rate based on a rate command received from the node, and transmits packets based on the received rate command.

52. An integrated circuit (IC) incorporated in a wireless transmit/receive unit (WTRU), the IC for adjusting a packet transmission rate of packets the WTRU transmits via an antenna, the IC comprising:

(a) a transmitter for transmitting to a node at least one packet at a particular packet transmission rate;

(b) a receiver for receiving an acknowledgement (ACK) signal from the node that receives and acknowledges receipt of the at least one packet;

(c) a processor in communication with the transmitter and the receiver;

(d) a memory in communication with the processor;

(e) a transmission rates database in communication with the processor; and

(f) a plurality of packet transmission counters in communication with the processor.

53. The IC of claim 52 wherein the particular packet transmission rate is initially set to a default rate.

54. The IC of claim 52 wherein the packet transmission counters include a total successful packet transmission counter and an individual packet transmission error counter.

55. The IC of claim 54 wherein the total successful packet transmission counter is incremented when the receiver receives an ACK from the node.

56. The IC of claim 55 wherein the individual packet transmission error counter is reset to zero when the receiver receives an ACK from the node.

57. The IC of claim 56 wherein the packet transmission counters further include a total unsuccessful packet transmission counter, and the processor determines whether to adjust the particular packet transmission rate based on the sum of a first count value of the total successful packet transmission counter and a second count value of the total unsuccessful packet transmission counter.

58. The IC of claim 57 wherein the particular packet transmission rate is increased if the sum is greater than equal to a predetermined number of packets need for a packet transmission rate increase.

59. The IC of claim 58 wherein the particular packet transmission rate is increased if the ratio of the second count value over the first count value is less than a predetermined packet transmission rate increase ratio.

60. The IC of claim 52 wherein the packet transmission counters include a total unsuccessful packet transmission counter and an individual packet transmission error counter.

61. The IC of claim 60 wherein the total unsuccessful packet transmission counter and the individual packet transmission error counter are incremented when the receiver does not receive an ACK from the node after transmitting the at least one packet to the node.

62. The IC of claim 61 wherein the particular packet transmission rate is reduced by one or more supported rate steps designated in the transmission rates database based on a count value of the individual packet transmission error counter.

63. The IC of claim 52 wherein the packet transmission counters include a received signal strength indicator (RSSI) level total packet transmission counter.

64. The IC of claim 63 wherein an RSSI measurement of an ACK received from the node after transmitting the at least one packet to the node is retrieved from the memory if an RSSI training process was not previously used to determine the particular packet transmission rate, the RSSI measurement is determined by the processor and the RSSI level total packet transmission counter for the RSSI level is incremented.

65. The IC of claim 64 wherein a packet error rate (PER) for the RSSI level is updated in the memory and, if the PER is stable, a preferred packet transmission rate for the RSSI level is also updated in the memory.

66. The IC of claim 63 wherein an RSSI measurement of an ACK received from the node after transmitting the at least one packet to the node is retrieved from the memory if an RSSI training process was previously used to determine the particular packet transmission rate, the RSSI measurement is determined by the processor and the RSSI level total packet transmission counter for the RSSI level is incremented.

67. The IC of claim 66 wherein a packet error rate (PER) for the RSSI level is updated in the memory and, if the PER is stable, a preferred packet transmission rate for the RSSI level is also updated in the memory.

68. The IC of claim 63 wherein the RSSI level total packet transmission counter for the RSSI level is incremented if an RSSI training process was previously used to determine the particular packet transmission rate, and after transmitting the at least one packet to the node without receiving an ACK from the node.

69. The IC of claim 68 wherein a packet error rate (PER) for the RSSI level is updated in the memory and, if the PER is stable, a preferred packet transmission rate for the RSSI level is also updated in the memory.

70. The IC of claim 52 wherein the packet transmission counters include a received signal strength indicator (RSSI) level total packet transmission counter and an RSSI level packet transmission error counter.

71. The IC of claim 70 wherein an RSSI measurement of an ACK received from the node after transmitting the at least one packet to the node is retrieved from the memory, and the RSSI level total packet transmission counter for the RSSI level is incremented for the RSSI level of the ACK.

72. The IC of claim 70 wherein if the at least one packet is transmitted to the node without receiving an ACK from the node, a determination is made as to whether there are any RSSI measurements available for any packets received from the node within a last maximum duration time period, and if so, the RSSI level of the measurements is determined and the RSSI level total packet transmission counter and the RSSI level packet transmission error counter are incremented.

73. The IC of claim 72 wherein a packet error rate (PER) for the RSSI level is updated in the memory and, if the PER is stable, a preferred packet transmission rate for the RSSI level is also updated in the memory.

74. The IC of claim 52 wherein the IC sets the particular packet transmission rate based on a rate command received from the node, and transmits packets based on the received rate command.