METHOD OP RELAYED WIRELESS TRANSMISSION

• US 20090028086A1
• Filed: 02/28/2007
• Published: 01/29/2009
• 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: Feng, Xie, Tay, Hui MJ, Bappu, Benjamin
• Granted Patent: US 8,687,539 B2
• Time in Patent Office: Days
• 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 for selecting the most-likely “best” relay station for data transmission from a given source station S to an access point AP uses the Initial Receive Signal Strength (IRSS) to infer the future data transmission rate. In the initialisation 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 candidates 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 (5, AP) via one of a plurality of relay stations (R), comprising

(a) sending at least one transmission (FRR) to the relay stations;

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

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

characterised in that each relay station (R) selects, based on its measurement, a time to transmit its report, such that the more favourable reports are transmitted more expeditiously than less favourable reports.

2. A method according to claim 1 in which transmission (a) is sent by the first station (S) to the relay stations (R);

the reports by the relay stations (R) are sent to the second station (AP);

the second station (AP) measures the signals received from the relay stations (R); and

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

3. A method according to claim 1 in which:

the second station (AP) sends a transmission (SRR) to the relay stations;

each relay station (R) measures the signals (SRR) received from the second station (AP);

at each relay station (R), the time selected to transmit its report is based not only on its measurements of the signal (FRR) from the first station but also on its measurement of the signal sent from the second station (AP).

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

the transmission (SRR) from the second station (AP) to the relay stations (R) is triggered by the reception at the second station (AP) of the transmission (ERR) from the first station; and

the transmissions from the relay stations (R) are triggered by reception at the relay station of the transmission (SRR) from the second station.

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

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

7. A method according to claim 6 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.

8. A method according to claim 5, when dependent on claim 3, in which each relay station translates its measurements into said index using translation data (ISSRC) sent to it with said transmission (SRR) from the second station.

9. A method according to claim 1,

in which, at each relay station (R), 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).

10. A method of choosing a station from a plurality of candidate stations for participation in a wireless link, comprising

(a) sending at least one transmission (FRR) to the candidate stations (R);

(b) at each candidate station, measuring the received signal (FRA) and transmitting a report (ROR) of this measurement;

(c) upon receipt of the reports (RCR), choosing a candidate station to be used, based on said measurements;

characterised in that each candidate station (R) selects, based on its measurement, a time to transmit its report, such that the more favourable reports are transmitted more expeditiously than at least the majority of the less favourable reports.