RELAY STATION AND METHOD OF OPERATING RELAY STATION IN MULTI-HOP COMMUNICATION SYSTEM

• US 20090252078A1
• Filed: 11/04/2008
• Published: 10/08/2009
• Est. Priority Date: 04/03/2008
• Status: Active Grant

• Current Assignee: Industry Academic Cooperation Foundation, Samsung Electronics Co. Ltd.
• Original Assignee: Industry Academic Cooperation Foundation, Samsung Electronics Co. Ltd.
• Inventors: LIM, Sung Gook, LEE, Jai Yong, SO, Jung Min, DO, Mi Sun
• Granted Patent: US 8,472,401 B2
• Time in Patent Office: Days
• US Class Current: 370/315
• CPC Class Codes: H04B 7/15 Active relay systems
• CPC Class Codes: H04B 7/155 Ground-based stations H04B7/204 takes precedence

Abstract

A replay station and a method of operating the relay station in a multi-hop communication system are provided. A method of operating a relay station of a multi-hop communication system includes monitoring a delay of the relay station, determining whether the monitored delay exceeds a predetermined threshold, and controlling the relay station to be handed over to another upper relay station that is different from a connecting upper relay station.

Claims

1. A relay station comprising:

an information receiver to receive, from at least one upper relay station performing multi-hop communication with a base station, end-to-end delay information and hop-count information between the base station and the at least one upper relay station;

a selector to select a connection target relay station from the at least one upper relay station based on the hop-count information and the end-to-end delay information; and

a connection controller to control the relay station to connect with the connection target relay station.

2. The relay station as claimed in claim 1, wherein where the relay station is within the coverage of the base station, the selector selects the base station as the connection target relay station.

3. The relay station as claimed in claim 1, wherein the selector selects, as the connection target relay station, an upper relay station with minimum hop counts to the base station, from the at least one upper relay station, and

where at least two upper relay stations with the minimum hop counts exist, the selector selects, from the at least two upper relay stations with the minimum hop counts, an upper relay station with minimum end-to-end delay to the base station as the connection target relay station.

4. The relay station as claimed in claim 1, further comprising:

an information generator to generate end-to-end delay information and hop-count information to the base station; and

a broadcasting unit to broadcast a broadcast message including the generated hop-count information and end-to-end delay information.

5. A relay station of a multi-hop communication system, comprising:

a delay monitoring unit to monitor a delay of the relay station;

a decision unit to determine whether the monitored delay exceeds a predetermined threshold; and

a handover controller to control one of the relay station or at least one lower relay station connecting with the relay station to be handed over to a connection target relay station where the monitored delay exceeds the threshold.

6. The relay station as claimed in claim 5, wherein the delay is an average queuing delay of the relay station.

7. The relay station as claimed in claim 5, wherein where the at least one lower relay station is connected with the relay station, the handover controller controls the at least one lower relay station to be handed over to the connection target relay station, and

where the at least one lower relay station is not connected with the relay station, the handover controller controls the relay station to be handed over to the connection target relay station.

8. The relay station as claimed in claim 5, wherein the handover controller further comprises:

a relative delay calculator to calculate a relative delay that each of the at least one lower relay station affects the relay station; and

a selector to select, from the at least one lower relay station, a lower relay station to be handed over to the connection target relay station based on the calculated relative delay.

9. The relay station as claimed in claim 8, wherein the relative delay calculator calculates the relative delay based on a bandwidth allocation ratio of each of the at least one lower relay station.

10. The relay station as claimed in claim 8, wherein the selector selects, from the at least one lower relay station, at least one lower relay station with the relative delay greater than the difference between the monitored delay and the threshold, and

the selector selects, from the selected at least one lower relay station, a lower relay station with the smallest relative delay as the lower relay station to be handed over to the connection target relay station.

11. The relay station as claimed in claim 5, wherein the handover controller, while maintaining a connection state of at least one sub-lower relay station connecting in a lower layer of the at least one lower relay station, controls the at least one lower relay station to be handed over to the connection target relay station.

12. A relay station of a multi-hop communication system, comprising a state machine, wherein the state machine switches between:

a waiting state of receiving a signal from the multi-hop communication system for connection to the multi-hop communication system;

a normal state of connecting with the multi-hop communication system to perform communication and monitor a delay of the relay station; and

a control state of controlling the relay station to connect with the multi-hop communication system and controlling either the relay station or any one of at least one lower relay station connecting with the relay station to be handed over to a connection target relay station where the monitored delay exceeds a predetermined threshold.

13. A method of operating a relay station of a multi-hop communication system, the method comprising:

monitoring a delay of the relay station;

determining whether the monitored delay exceeds a predetermined threshold; and

in response to the monitored delay exceeding the threshold, controlling the relay station to be handed over to another upper relay station that is different from a connecting upper relay station.

14. The method as claimed in claim 13, wherein the delay is an average queuing delay of the relay station.

15. A method of operating a relay station of a multi-hop communication system, the method comprising:

monitoring a delay of the relay station;

determining whether the monitored delay exceeds a predetermined threshold; and

in response to the monitored delay exceeding the threshold, controlling at least one lower relay station connecting with the relay station to be handed over to another relay station.

16. The method as claimed in claim 15, wherein the delay is an average queuing delay of the relay station.

17. The method as claimed in claim 15, wherein the controlling of the at least one lower relay station comprises:

calculating a relative delay that each of the at least one lower relay station affects the relay station; and

selecting a target relay station to be handed over to the other relay station based on the relative delay.

18. The method as claimed in claim 17, wherein the calculating of the relative delay comprises calculating the relative delay based on a bandwidth allocation ratio of each of the at least one lower relay station.

19. The method as claimed in claim 17, wherein the selecting of the target relay station comprises selecting, from the at least one lower relay station, at least one lower relay station with the relative delay greater than the difference between the monitored delay and the threshold, and selecting, from the selected at least one lower relay station, a lower relay station with the smallest relative delay as the target relay station.

20. The method as claimed in claim 15, wherein the controlling of the at least one lower relay station comprises, while maintaining a connection state of at least one sub-lower relay station connecting in a lower layer of the at least one lower relay station, controlling the at least one lower relay station to be handed over to the another relay station.

21. A computer-readable storage medium storing a program to operate a relay station of a multi-hop communication system, comprising instructions to cause a computer to:

monitor a delay of the relay station;

determine whether the monitored delay exceeds a predetermined threshold; and

control the relay station to be handed over to another upper relay station that is different from a connecting upper relay station in response to the monitored delay exceeding the threshold.

22. A computer-readable storage medium storing a program to operate a relay station of a multi-hop communication system, comprising instructions to cause a computer to:

monitor a delay of the relay station;

determine whether the monitored delay exceeds a predetermined threshold; and

control at least one lower relay station connecting with the relay station to be handed over to another relay station in response to the monitored delay exceeding the threshold.