METHOD AND SYSTEM OF THRESHOLD SELECTION FOR RELIABLE RELAY STATIONS GROUPING FOR DOWNLINK TRANSMISSION

• US 20090116419A1
• Filed: 10/23/2008
• Published: 05/07/2009
• Est. Priority Date: 11/05/2007
• Status: Abandoned Application

• Current Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Original Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Inventors: Chong, Chia-Chin, Inamura, Hiroshi, Watanabe, Fujio
• Application Number:
  US12/257,325
• Publication Number:
  US 20090116419A1
• Time in Patent Office: Days
• US Class Current: 370/312
• CPC Class Codes: H04B 7/024 Co-operative use of antennas of several sites, e.g. in co-ordinated multipoint or co-operative multiple-input multiple-output [MIMO] systems
• CPC Class Codes: H04B 7/15592 Adapting at the relay station communication parameters for supporting cooperative relaying, i.e. transmission of the same data via direct - and relayed path cooperative diversity H04B7/024
• CPC Class Codes: H04W 16/26 Cell enhancers or enhancement, e.g. for tunnels, building shadow

Abstract

A relaying selection and cooperative communications method provides a threshold selection criterion for forming a reliable group of relay stations (RSs) based on one or more design criteria. Possible design criteria include an outage probability constraint and a throughput constraint. The threshold value is selected according to, for example, transmission paths (e.g., line-of-sight, obstructed-light-of-sight, non-light-of-sight) or channel conditions (e.g., signal-to-noise-ratio) between the base station (BS) and the RSs (i.e., BS-RSs link) and between the RSs and the mobile station (MS) (i.e., RSs-MS link), respectively.

Claims

1. A method for selecting a threshold value for determining a reliable relay station group, under a cooperative multicast relay downlink transmission scheme, comprising:

evaluating a first signal condition between a transmitter and one or more relay stations; and

assigning a first value to the threshold value, when the first signal condition is stronger than a first predetermined value;

otherwise;

evaluating a second signal condition between the one or more relay stations and a destination, and

assigning a second value less than the first value to the threshold value, when the second signal condition is stronger than a second predetermined value, and assigning a third value greater than the second value to the threshold value, otherwise.

2. A method as in claim 1, wherein the first and second signal conditions are determined based on whether or not a line-of-sight condition, a non-line-of-sight condition or an obstructed-line-of-sight condition exists.

3. A method as in claim 1, wherein the first and second signal conditions are evaluated based on a signal-to-noise ratio.

4. A method as in claim 1, wherein the method reduces a probability of a lost packet.

5. A method for selecting a threshold value for determining a reliable relay station group, under a cooperative multicast relay downlink transmission scheme, comprising:

evaluating a first signal condition between a transmitter and one or more relay stations; and

assigning a first value to the threshold value, when the first signal condition is stronger than a first predetermined value;

otherwise;

evaluating a second signal condition between the one or more relay stations and a destination, and

assigning the first value to the threshold value, when the second signal condition is stronger than a second predetermined value, and assigning a second value to the threshold value, otherwise.

6. A method as in claim 5, wherein the first and second signal conditions are determined based on whether or not a line-of-sight condition, a non-line-of-sight condition or an obstructed-line-of-sight condition exists.

7. A method as in claim 5, wherein the first and second signal conditions are evaluated based on a signal-to-noise ratio.

8. A method as in claim 5, wherein the method results in increasing an average number of correctly received packets per transmission.

9. A two-part transmission system to a destination, comprising:

a transmitter; and

a plurality of relay stations, wherein the transmitter transmit a data packet to a subset of the relay stations, which forward the data packet to the destination and wherein the subset is determined according to a threshold value determined by a method that comprises;

evaluating a first signal condition between a transmitter and one or more relay stations; and

assigning a first value to the threshold value, when the first signal condition is stronger than a first predetermined value;

otherwise;

evaluating a second signal condition between the one or more relay stations and a destination, and

assigning a second value less than the first value to the threshold value, when the second signal condition is stronger than a second predetermined value, and assigning a third value greater than the second value to the threshold value, otherwise.

10. A two-part transmission system as in claim 9, wherein the first and second signal conditions are determined based on whether or not a line-of-sight condition, a non-line-of-sight condition or an obstructed-line-of-sight condition exists.

11. A two-part transmission system as in claim 9, wherein the first and second signal conditions are evaluated based on a signal-to-noise ratio.

12. A two-part transmission system as in claim 9, wherein the method reduces a probability of a lost packet.

13. A two-part transmission system to a destination, comprising:

a transmitter; and

a plurality of relay stations, wherein the transmitter transmit a data packet to a subset of the relay stations, which forward the data packet to the destination and wherein the subset is determined according to a threshold value determined by a method that comprises;

evaluating a first signal condition between a transmitter and one or more relay stations; and

assigning a first value to the threshold value, when the first signal condition is stronger than a first predetermined value;

otherwise;

evaluating a second signal condition between the one or more relay stations and a destination, and

assigning the first value to the threshold value, when the second signal condition is stronger than a second predetermined value, and assigning a second value to the threshold value, otherwise.

14. A two-part transmission system as in claim 13, wherein the first and second signal conditions are determined based on whether or not a line-of-sight condition, a non-line-of-sight condition or an obstructed-line-of-sight condition exists.

15. A two-part transmission system as in claim 13, wherein the first and second signal conditions are evaluated based on a signal-to-noise ratio.

16. A two-part transmission system as in claim 13, wherein the method results in increasing an average number of correctly received packets per transmission.