Method of relayed wireless transmission

• US 8,687,539 B2
• Filed: 02/28/2007
• Issued: 04/01/2014
• Est. Priority Date: 03/16/2006
• Status: Active Grant

• Current Assignee: British Telecommunications PLC (BT Group PLC)
• Original Assignee: British Telecommunications PLC (BT Group PLC)
• Inventors: Bappu, Benjamin, Feng, Xie, Tay, Hui M J
• Primary Examiner(s): SMARTH, GERALD A
• Application Number:
  US12/281,392
• Publication Number:
  US 20090028086A1
• Time in Patent Office: 2,589 Days
• Field of Search: 370/315
• US Class Current: 370/315
• CPC Class Codes: H04W 40/12 based on transmission quality or channel quality
• CPC Class Codes: H04W 40/22 using selective relaying for reaching a BTS [Base Transceiver Station] or an access point
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A light-weight relay selection mechanism selects the most likely “best” relay station for data transmission from a given source station S to an access point AP using the Initial Receive Signal Strength (IRSS) to infer the future data transmission rate. In the initialization stage, the access point AP constructs a table mapping the IRSSs of receivers to eight levels of transmission rate. In the relay selection stage, relay candidates R measure the IRSSs for the source station S and access point AP and report their IRSS levels to the AP. A contention-based mechanism is dedicated to enabling the candidate with higher IRSS levels to report earlier. With this mechanism, the access point AP is able to select the station with the highest estimated data transmission rate.

Claims

1. A method of transmission between a first station and a second station via one of a plurality of relay stations, said method comprising:

(a) transmitting at least one signal to a plurality of candidate relay stations for communicating between a first station and a second station;

(b) at each relay station, measuring a received signal resulting from said transmitted signal and transmitting a report of this measurement to one of the first and second stations;

(c) upon receipt of the reports, choosing a relay station to be used, based on said measurement;

(d) the second station transmitting a signal to the relay station;

(e) each relay station measuring the signal received from the second station; and

(f) each relay station selecting a time to transmit its report, such that more favorable reports are transmitted more expeditiously than less favorable reports,

wherein, for each relay station, the time selected to transmit its report is based not only on its measurement of the first received signal, but also on its measurement of the signal transmitted by the second station.

2. A method according to claim 1, in which:

in (a), the first station transmits the first signal to the relay stations;

in (b), each of the relay stations transmit the report to the second station; and

the second station measures the signals received from the relay stations; and

the second station chooses a relay station to be used, based both on the measurements contained in the reports and on the measurements made at the second station.

3. A method according to claim 1, in which:

the transmission of the signal by the second station to the relay stations is triggered by the reception at the second station of the signal transmitted by the first station; and

the transmissions from the relay stations are triggered by reception at the relay station of the signal transmitted by the second station.

4. A method according to claim 1, in which the measurements are of received signal strength.

5. A method according to claim 4, in which each report contains an index indicating within which of a plurality of ranges the received signal strength falls.

6. A method according to claim 5, in which said ranges are adaptively varied in accordance with actual measurements of the correlation between received signal strengths and data rates, such that each range corresponds to a range of signal strengths associated with a respective one or more of discrete data rates.

7. A method according to claim 5, in which each relay station translates its measurements into said index using translation data sent to it with said transmission from the second station.

8. A method according to claim 1, in which, at each relay station, the time selected to transmit its report is chosen in a random or pseudo random manner within a range defined by upper and lower bounds chosen as a function of said measurement(s).

9. A method of transmission between a first station and a second station via one of a plurality of candidate relay stations, said method comprising:

(a) transmitting at least one signal from at least one of a first station and a second station to each of plural candidate relay stations for relaying of future signals between said first and second stations;

(b) at each of said plural candidate relay stations, measuring an initial receive signal strength for said signals transmitted from said at least one of first and second stations;

(c) at each of at least some of said plural candidate relay stations, transmitting a received signal quality report to at least one of said first and second stations based on an initial receive signal quality measured for said signals transmitted from said at least one first and second stations at respectively corresponding different locally selected times such that more favorable reports are transmitted sooner than less favorable reports,

wherein, for each candidate relay station, the time selected to transmit its report is based on signals received from said at least one first and second stations; and

(d) selecting one of said candidate relay stations for future signals between said first and second stations at one of said first and second stations based at least in part on a signal quality report received from the selected candidate relay station.

10. The method according to claim 9, wherein:

the first station transmits a first signal to the relay stations and each of the relay stations transmits its report to the second station; and

the second station measures the signals received from the relay stations; and

the second station chooses a relay station to be used, based both on the measurements contained in the reports and on the measurements made locally at the second station.

11. The method according to claim 9, wherein:

the transmission of the signal by the second station to the relay stations is triggered by the reception at the second station of the signal transmitted by the first station; and

the transmissions from each relay station are triggered by reception at that relay station of the signal transmitted by the second station.

12. The method according to claim 9, wherein the measurements of quality include measurement of received signal strength.

13. The method according to claim 12, in which each transmitted quality report contains an index indicating within which of a plurality of ranges the received signal strength falls.

14. The method according to claim 13, in which said ranges are adaptively varied in accordance with actual measurements of correlation between received signal strengths and data rates, such that each range corresponds to a range of signal strengths associated with a respective one or more of discrete data rates.

15. The method according to claim 13, in which each relay station translates its measurements into said index using translation data sent to it with said transmission from the second station.

16. The method according to claim 9, in which, at each relay station, the time selected to transmit its report is chosen in a random or pseudo random manner within a range defined by upper and lower bounds chosen as a function of said measurement(s).