Communication system

• US 20070066241A1
• Filed: 06/16/2006
• Published: 03/22/2007
• Est. Priority Date: 06/17/2005
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Hart, Michael
• Granted Patent: US 8,571,468 B2
• Time in Patent Office: Days
• US Class Current: 455/69
• CPC Class Codes: H04B 7/2606 Arrangements for base station coverage control, e.g. by using relays in tunnels
• CPC Class Codes: H04W 52/34 TPC management, i.e. sharing limited amount of power among users or channels or data types, e.g. cell loading
• CPC Class Codes: H04W 52/38 TPC being performed in particular situations
• CPC Class Codes: H04W 52/46 in multi hop networks, e.g. wireless relay networks

Abstract

The present application relates to a wireless communication system and related methods and apparatuses for transmitting a signal from a source apparatus to a destination apparatus, via at least one intermediate apparatus. In particular, the present invention relates to techniques which seek to improve the throughput of data in multi-hop communication systems.

Claims

1. A communication system comprising a source apparatus, an intermediate apparatus and a base station, the source apparatus being operable to transmit a communication signal, via the or each intermediate apparatus, to the base station, the base station comprising an indicator derivator operable to derive one or more indicators of the quality of a communication signal received at the base station, and wherein the communication system further comprises:

i) a controller provided in the base station;

ii) an indicator deviator detector operable to detect a change in one said indicator derived by the base station from a desired value;

iii) a determination unit operable, following the detection of such a change, to determine a required change in the transmit power of the intermediate apparatus that will tend to bring said indicator to said desired value, wherein said determination unit further comprises a request transmitter operable to transmit a request for a change in the transmit power of the intermediate apparatus to the controller.

2. A communication system as claimed in claim 1, wherein one said indicator derived by said destination apparatus comprises a measure of the strength of a communication signal received at the base station.

3. A communication system as claimed in claim 1, wherein one said indicator derived by said destination apparatus comprises a measure of the signal-to-interference plus noise ratio (SINR) of a communication signal received at the base station.

4. A communication system as claimed in claim 1, wherein one said indicator derived by said base station comprises a measure of the variation of the quality of a communication signal received at the destination apparatus from a target received signal quality.

5. A communication system as claimed in claim 1, wherein if the required change in transmit power of the intermediate apparatus comprises a decrease in transmit power, said controller is operable, following receipt of a request for a change in the transmit power of the intermediate apparatus, to issue a command to said intermediate apparatus, commanding a change in transmit power of the intermediate apparatus.

6. A communication system as claimed in claim 1, wherein the controller further comprises an input signal receiver, operable to receive an input signal which allows the controller to determine if an increase in transmit power of the intermediate apparatus is prohibited.

7. A communication system as claimed in claim 6, wherein if the required change in transmit power of the intermediate apparatus comprises an increase in transmit power, and following a determination by the controller that an increase in transmit power of the intermediate apparatus is prohibited, the controller is operable to ignore said request.

8. A communication system as claimed in claim 6, wherein if the required change in transmit power of the intermediate apparatus comprises an increase in transmit power, and following a determination by the controller that an increase in transmit power of the intermediate apparatus is not prohibited, the controller is operable issue a command to said intermediate apparatus, commanding a change in transmit power of the intermediate apparatus.

9. A communication system as claimed in claim 5, wherein said intermediate apparatus is operable to receive such a command from said controller of the base station.

10. A communication system as claimed in claim 9, wherein said intermediate apparatus is operable to determine, based on a maximum transmit power of the intermediate apparatus, if said intermediate apparatus can carry out the change in transmit power according to said command.

11. A communication system as claimed in claim 10, wherein if said intermediate apparatus determines that it cannot carry out the change in transmit power according to said command, said intermediate apparatus is operable to determine a revised change in transmit power of the intermediate apparatus which can be carried out by said intermediate apparatus.

12. A communication system as claimed claim 9, wherein said intermediate apparatus is operable to cause the transmit power of the intermediate apparatus to change in accordance with said request, or said revised request, as the case may be.

13. A communication system as claimed in claim 1, wherein said intermediate apparatus comprises an indicator derivator operable to derive an indicator of the quality of a communication signal received at the intermediate apparatus and wherein said intermediate apparatus is further operable to transmit said indicator to an indicator receiver of said base station, wherein said base station further comprises an imbalance detector operable to detect an imbalance between an indicator derived by the base station and an indicator derived by the intermediate apparatus, and wherein said determination unit is further operable, following detection of such an imbalance by said imbalance detector, to determine a required change in the transmit power of the source apparatus that will tend to reduce such an imbalance, wherein said controller is further operable, following determination of said change, to issue a command to said source apparatus commanding a change in the transmit power of the source apparatus in accordance said required change.

14. A communication system as claimed in claim 13, wherein said source apparatus is operable, following receipt of a command, and wherein said command is for an increase in transmit power, to determine if it can carry out the command based on the maximum transmit power of the source apparatus.

15. A communication system as claimed in claim 14, wherein if said source apparatus determines that it cannot carry out the said request, the source apparatus is operable to determine a revised change in transmit power that will tend to reduce the said imbalance, and to carry out said revised change.

16. A communication system as claimed in claim 13, wherein said controller is operable, following issuance of a command to said source apparatus and wherein said instruction was for an increase in transmit power, to monitor said indicator derived by the intermediate apparatus in order to determine if said transmit power of said source apparatus has been changed in accordance with said command.

17. A communication system as claimed in claim 16, wherein if it is determined that a change in transmit power of the source apparatus has not been carried out in accordance with said command, said controller is operable to prohibit any subsequent increases in transmit power of said intermediate apparatus.

18. A communication system, as claimed in claim 17, wherein if an increase in transmit power of said intermediate apparatus is prohibited, and if no subsequent imbalance is detected by said imbalance detector, said controller is operable to allow a subsequent increase in transmit power of said intermediate apparatus.

19. A communication system, as claimed in claim 17, wherein if an increase in transmit power of said intermediate apparatus is prohibited, and if a subsequent imbalance is detected by said imbalance detector such that said controller of said base station is caused to issue a command to said source apparatus and wherein said command is for a decrease in transmit power, said controller is operable to allow a subsequent increase in transmit power of said intermediate apparatus.

20. A communication system, as claimed in claim 17, wherein if an increase in transmit power of said intermediate apparatus is prohibited, and if a subsequent imbalance is detected by said imbalance detector such that said controller of the base station is caused to issue a command request to said source apparatus wherein said command is for an increase in transmit power which can be carried out by said source apparatus, said controller is operable to allow a subsequent increase in transmit power of said intermediate apparatus.

32. A communication system as claimed in claim 1 or 13, wherein said intermediate apparatus comprises a regenerative relay node.

41. A computer program which, when loaded into a computer, causes the computer to become the base station of the communication system as claimed in claim 1.

21. A communication system comprising a source apparatus, an intermediate apparatus and a base station, the source apparatus being operable to transmit a communication signal, via the or each intermediate apparatus, to the base station, the wherein each of the base station and the intermediate apparatus comprise:

an indicator derivator operable to derive one or more indicators of the quality of a communication signal received at the base station or the intermediate apparatus respectively, the communication system further comprising;

i) an imbalance detector operable to detect an imbalance between one said indicator derived by the base station and one said indicator derived intermediate apparatus; and

ii) a determination unit operable, following detection of such an imbalance by said imbalance detector, to determine a required change in the transmit power of the source apparatus that will tend to reduce such an imbalance; and

iii) a controller provided in said base station and operable, following determination of said change, to issue a command to said source apparatus commanding a change in the transmit power of the source apparatus.

22. A communication system as claimed in claim 21, wherein one said indicator derived by each of the intermediate apparatus and the base station comprises a measure of the strength of a communication signal respectively received at the intermediate apparatus or the base station, as the case may be.

23. A communication system as claimed in claim 21, wherein one said indicator derived by each of said intermediate apparatus and said base station comprises a measure of the signal-to-interference plus noise ratio (SINR) of a communication signal respectively received at the intermediate apparatus or the base station, as the case may be.

24. A communication system as claimed in claim 21, wherein said intermediate apparatus is operable to transmit said indicator to said imbalance detector.

25. A communication system as claimed in claim 21, wherein said source apparatus is operable, following receipt of a command, and wherein said command is for an increase in transmit power, to determine if it can carry out the command based on the maximum transmit power of the source apparatus.

26. A communication system as claimed in claim 25, wherein if said source apparatus determines that it cannot carry out the said command, the source apparatus is operable to determine a revised change in transmit power that will tend to reduce the said imbalance, and to carry out said revised change.

27. A communication system as claimed in claim 24, wherein said controller is operable, following issuance of a command to said source apparatus and wherein said command was for an increase in transmit power, to monitor said indicator derived by the intermediate apparatus in order to determine if said transmit power of said source apparatus has been changed in accordance with said command.

28. A communication system as claimed in claim 27, wherein if it is determined that a change in transmit power of the source apparatus has not been carried out in accordance with said request, said controller is operable to prohibit any subsequent increases in transmit power of said intermediate apparatus.

29. A communication system, as claimed in claim 28, wherein if an increase in transmit power of said intermediate apparatus is prohibited, and if no subsequent imbalance is detected by said imbalance detector, said controller is operable to allow a subsequent increase in transmit power of said intermediate apparatus.

30. A communication system, as claimed in claim 28, wherein if an increase in transmit power of said intermediate apparatus is prohibited, and if a subsequent imbalance is detected by said imbalance detector such that said controller of said base station is caused to issue a command to said source apparatus and wherein said command is for a decrease in transmit power, said controller is operable to allow a subsequent increase in transmit power of said intermediate apparatus.

31. A communication system, as claimed in claim 28, wherein if an increase in transmit power of said intermediate apparatus is prohibited, and if a subsequent imbalance is detected by said imbalance detector such that said controller of said base station is caused to issue a command to said source apparatus and wherein said instruction is for an increase in transmit power which can be carried out by said source apparatus, said controller is operable to allow a subsequent increase in transmit power of said intermediate apparatus.

33. A method of controlling the transmit power of an intermediate apparatus in a multi-hop communication system, the communication system comprising a source apparatus, a base station and at least one intermediate apparatus, the source apparatus being operable to transmit a communication signal, via the or each intermediate apparatus, to the base station, the method comprising the steps of:

i) deriving, at the base station, one or more indicators of a quality of a communication signal received at the base station;

ii) detecting a deviation in the, or one of the, indicators derived by the base station from a desired value; and

iii) determining a required change in the transmit power of the intermediate apparatus that will tend to bring said indicator to said desired value.

34. A method of controlling the transmit power of a source apparatus in a multi-hop communication system, the multi-hop communication system comprising a source apparatus, a base station and at least one intermediate apparatus, the source apparatus being operable to transmit a communication signal, via the or each intermediate apparatus, to the base station, the method comprising the steps of:

i) deriving, at each of the base station and the intermediate apparatus, one or more indicator(s) of a quality of a communication signal received at the base station, or at the intermediate apparatus, respectively;

ii) detecting an imbalance between one said indicator derived by the base station and one said indicator derived by the intermediate apparatus;

iii) determining a required change in the transmit power of the source apparatus that will tend to reduce such an imbalance; and

iv) issuing a command to said source apparatus commanding a change in the transmit power of said source apparatus.

35. A base station operable to receive, via one or more intermediate apparatus a communication signal from a source apparatus, the base station comprising:

i) an indicator derivator operable to derive one or more indicators of a quality of a communication signal received at the base station;

ii) an indicator deviation detector, operable to detect a deviation in the, or one of the, indicators derived by the indicator derivator;

from a desired value;

iii) a determination unit operable, following detection of such a change by said indicator deviation detector, to determine a required change in the transmit power of the intermediate apparatus that will tend to bring the said indicator towards said desired value, said determination unit being operable to transmit a request for a change in the transmit power of the intermediate apparatus to said controller;

iv) a controller, operable to receive such a request from said determination unit.

36. A base station as claimed in claim 35, wherein the controller further comprises input signal receiver, operable to receive an input signal which allows the controller to determine if an increase in transmit power of the intermediate apparatus is prohibited.

37. A base station as claimed in claim 35 or 36, further comprising:

i) a receiver, operable to receive an indicator derived by said intermediate apparatus, which indicator is indicative of a quality of a communication signal received at the intermediate apparatus;

ii) an imbalance detector operable to detect an imbalance between an indicator derived by the base station and an indicator received from the intermediate apparatus;

wherein said determination unit is operable, following detection of such an imbalance by said imbalance detector, to determine a required change in the transmit power of the source apparatus that will tend to reduce such an imbalance, said controller being further operable, following determination of said required change, to issue a command to said source apparatus commanding a change in the transmit power of said source apparatus.

38. A base station operable to receive, via one or more intermediate apparatus, a communication signal from a source apparatus, the base station comprising:

i) an indicator derivator operable to derive one or more indicator of the quality of a communication signal received at the base station;

ii) an indicator receiver operable to receive one or more indicator from the intermediate apparatus, wherein the or each indicator is indicative of the quality of a communication signal received at the intermediate apparatus;

iii) an imbalance detector operable to detect an imbalance between an indicator derived by the base station and an indicator received from the intermediate apparatus; and

iv) a determination unit operable, following detection of such an imbalance by said imbalance detector, to determine a required change in the transmit power of the source apparatus that will tend to reduce such an imbalance; and

v) a controller operable, following determination of said change, to issue a command to said source apparatus commanding a change in the transmit power of said source apparatus.

39. A base station as claimed in claim 38, wherein said controller is operable, following issuance of a command to said source apparatus and wherein said instruction was for an increase in transmit power, to monitor said signal strength indicator derived by the intermediate apparatus in order to determine if said transmit power of said source apparatus has been changed in accordance with said command.

40. A base station as claimed in claim 39, wherein if it is determined that a change in transmit power of the source apparatus has not been carried out in accordance with said command, said controller is operable to prohibit any subsequent increases in transmit power of said intermediate apparatus.