Interference control via selective blanking/attenuation of interfering transmissions

• US 8,085,831 B2
• Filed: 05/17/2004
• Issued: 12/27/2011
• Est. Priority Date: 05/17/2004
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Teague, Edward Harrison
• Primary Examiner(s): LAM, KENNETH T
• Application Number:
  US10/848,023
• Publication Number:
  US 20050254555A1
• Time in Patent Office: 2,780 Days
• Field of Search: 375/136, 375/132, 375/130, 375/133, 375/135, 375/259
• US Class Current: 375/132
• CPC Class Codes: H04B 1/715 Interference-related aspects
• CPC Class Codes: H04B 2001/7154 with means for preventing interference
• CPC Class Codes: H04W 52/243 taking into account interferences
• CPC Class Codes: H04W 52/38 TPC being performed in particular situations
• CPC Class Codes: H04W 52/44 in connection with interruption of transmission

Abstract

Inter-sector interference for a target user in a sector may be controlled by selectively blanking or attenuating transmit powers for interfering users in neighboring sectors whenever their transmissions collide. The sector provides the frequency hopping (FH) sequence or subband usage for the target user to the neighboring sectors. Each neighboring sector uses the target user'"'"'s FH sequence to form a blanking pattern. Each neighboring sector then either blanks or reduces transmit power for each subband in its blanking pattern. Each user in each neighboring sector receives either (1) punctured symbols for subbands in the blanking pattern, if blanking is performed, or (2) lower energy symbols for these subbands, if attenuation is performed. In any case, the target user and each neighboring user may process their received symbols in the normal manner and do not need to be informed of the blanking/attenuation.

Claims

1. A method of controlling interference caused by a transmitting entity in a wireless communication system, comprising:

receiving, at the transmitting entity from at least one base station other than the transmitting entity, at least one frequency hopping (FH) sequence assigned to at least one terminal for which reduced interference is sought;

determining a blanking pattern indicative of transmission spans for which the reduced interference from the transmitting entity is sought based on the received FH sequence; and

turning off or reducing transmit power for transmissions sent on the transmission spans in the blanking pattern.

2. The method of claim 1, wherein the wireless communication system utilizes orthogonal frequency division multiplexing (OFDM), and wherein each transmission span in the system corresponds to a specific set of one or more subbands in a specific time interval.

3. The method of claim 2, wherein the blanking pattern includes different sets of subbands in different time intervals.

4. The method of claim 1, wherein the blanking pattern includes a subset of all transmission spans usable for data transmission in the system.

5. The method of claim 1, wherein the transmitting entity is a current base station having at least one neighboring base station.

6. The method of claim 5, wherein the blanking pattern includes transmission spans assigned to the at least one terminal in communication with the at least one neighboring base station and for which the current base station is deemed to be an interfering base station.

7. The method of claim 6, wherein the current base station is deemed to be an interfering base station to a terminal in communication with a neighboring base station if received pilot power for the current base station, as measured at the terminal, exceeds a predetermined threshold.

8. The method of claim 6, wherein each terminal in communication with a neighboring base station maintains an active set of one or more base stations with which the terminal may communicate, and wherein the current base station is deemed to be an interfering base station if the current base station appears in the active set for the terminal.

9. The method of claim 5, wherein the blanking pattern excludes transmission spans with blanked or reduced transmission by the at least one neighboring base station.

10. The method of claim 5, further comprising:

identifying terminals in communication with the current base station and for which reduced interference is sought;

identifying neighboring base stations causing interference to each identified terminal; and

determining, for each neighboring base station, transmission spans on which reduced interference from the neighboring base station is sought for the identified terminals.

11. The method of claim 10, wherein a neighboring base station is deemed to be an interfering base station to a terminal in communication with the current base station if received pilot power for the neighboring base station, as measured at the terminal, exceeds a predetermined threshold.

12. The method of claim 10, wherein each terminal in communication with the current base station maintains an active set of one or more base stations with which the terminal may communicate, and wherein a neighboring base station is deemed to be an interfering base station if the neighboring base station appears in the active set for the terminal.

13. The method of claim 1, wherein the transmitting entity is a terminal.

14. The method of claim 13, wherein the FH sequence is received from a base station with which the terminal is in communication.

15. The method of claim 1, wherein the transmit power for transmissions sent on the transmission spans in the blanking pattern is reduced by a predetermined amount.

16. The method of claim 1, wherein the transmit power for transmissions sent on the transmission spans in the blanking pattern is limited to be within a predetermined power level.

17. The method of claim 1, wherein the transmit power is turned off when deemed more likely to cause high interference and reduced when deemed less likely to cause high interference.

18. An apparatus operable to control interference in a wireless communication system, comprising:

a controller operative to receive, at a transmitting entity from at least one base station other than the transmitting entity, at least one frequency hopping (FH) sequence assigned to at least one terminal for which reduced interference is sought, and to determine a blanking pattern indicative of transmission spans for which the reduced interference from the transmitting entity is sought based on the received FH sequence; and

a unit operative to turn off or reduce transmit power for transmissions sent on the transmission spans in the blanking pattern.

19. The apparatus of claim 18, wherein the transmitting entity is a current base station having at least one neighboring base station.

20. The apparatus of claim 19, wherein the blanking pattern includes transmission spans assigned to the at least one terminal in communication with the at least one neighboring base station and for which the current base station is deemed to be an interfering base station.

21. The apparatus of claim 19, wherein the controller is further operative to identify terminals in communication with the current base station and for which reduced interference is sought,

identify neighboring base stations causing interference to each identified terminal, and

determine, for each neighboring base station, transmission spans on which reduced interference from the neighboring base station is sought for the identified terminals.

22. The apparatus of claim 18, wherein the wireless communication system is an orthogonal frequency division multiple access (OFDMA) system.

23. An apparatus operable to control interference in a wireless communication system, comprising:

means for receiving, at a transmitting entity from at least one base station other than the transmitting entity, at least one frequency hopping (FH) sequence assigned to at least one terminal for which reduced interference is sought, and to determine a blanking pattern indicative of transmission spans for which the reduced interference from the transmitting entity is sought based on the received FH sequence; and

means for turning off or reducing transmit power for transmissions sent on the transmission spans in the blanking pattern.

24. The apparatus of claim 23, wherein the transmitting entity is a current base station having at least one neighboring base station.

25. The apparatus of claim 24, wherein the blanking pattern includes transmission spans assigned to the at least one terminal in communication with the at least one neighboring base station and for which the current base station is deemed to be an interfering base station.

26. The apparatus of claim 24, further comprising:

means for identifying terminals in communication with the current base station and for which reduced interference is sought;

means for identifying neighboring base stations causing interference to each identified terminal; and

means for determining, for each neighboring base station, transmission spans on which reduced interference from the neighboring base station is sought for the identified terminals.

27. A method comprising:

obtaining received symbols for transmission spans assigned to a terminal;

receiving at a base station, from at least one neighboring base station, at least one frequency hopping (FH) sequence assigned to at least one terminal for which reduced interference is sought, and determining a blanking pattern that indicates transmission spans for which the reduced interference from the base station is sought based on the received FH sequence, wherein a subset of the transmission spans assigned to the terminal is included in the received blanking pattern, and wherein transmit power for the base station is turned off or reduced for symbols sent on the transmission spans in the blanking pattern; and

processing the received symbols to obtain decoded data for the terminal.

28. The method of claim 27, wherein the wireless communication system utilizes orthogonal frequency division multiplexing (OFDM), and wherein each transmission span in the system corresponds to a specific set of one or more subbands in a specific time interval.

29. A method comprising:

obtaining received symbols for transmission spans assigned to a terminal of a wireless communication system at a base station, wherein the wireless communication system utilizes orthogonal frequency division multiplexing, and wherein each transmission span in the wireless communication system corresponds to a specific set of one or more subbands in a specific time interval;

receiving at the base station, from at least one neighboring base station, a blanking pattern that indicates transmission spans for which reduced interference from the base station is sought, wherein a subset of the transmission spans assigned to the terminal is included in the received blanking pattern, and wherein transmit power for the base station is turned off or reduced for symbols sent on the transmission spans in the blanking pattern;

setting the received symbols for transmission spans in the blanking pattern and assigned to the terminal to erasures at the base station; and

processing the received symbols to obtain decoded data for the terminal at the base station.

30. An apparatus operable to receive a data transmission sent by a base station to a terminal in a wireless communication system, comprising:

a demapping unit operative to obtain received symbols for transmission spans assigned to the terminal, operative to receive at the base station, from at least one neighboring base station, at least one frequency hopping (FH) sequence assigned to at least one terminal for which reduced interference is sought, and operative to determine a blanking pattern that indicates transmission spans for which the reduced interference from the base station is sought based on the received FH sequence, wherein a subset of the transmission spans assigned to the terminal is included in the blanking pattern, and wherein transmit power for the base station is turned off or reduced for symbols sent on the transmission spans in the blanking pattern; and

a decoder operative to process the received symbols to obtain decoded data for the terminal.

31. An apparatus comprising:

means for obtaining received symbols for transmission spans assigned to a terminal at a base station;

means for receiving at the base station, from at least one neighboring base station, at least one frequency hopping (FH) sequence assigned to at least one terminal for which reduced interference is sought, and determining a blanking pattern that indicates transmission spans for which the reduced interference from the base station is sought based on the received FH sequence, wherein a subset of the transmission spans assigned to the terminal is included in the blanking pattern, and wherein transmit power for the base station is turned off or reduced for symbols sent on the transmission spans in the blanking pattern; and

means for processing the received symbols to obtain decoded data for the terminal.

32. A method comprising:

obtaining received symbols for transmission spans assigned to a terminal at a base station of a wireless communication system;

receiving at the base station, from at least one neighboring base station, at least one frequency hopping (FH) sequence assigned to at least one terminal for which reduced interference is sought, and determining a blanking pattern that indicates transmission spans for which the reduced interference from the terminal is sought based on the received FH sequence, wherein a subset of the transmission spans assigned to the terminal is included in the blanking pattern, and wherein transmit power for the terminal is turned off or reduced for symbols sent on the transmission spans in the blanking pattern; and

processing the received symbols to obtain decoded data for the terminal.

33. The method of claim 32, wherein the wireless communication system utilizes orthogonal frequency division multiplexing (OFDM), and wherein each transmission span in the system corresponds to a specific set of one or more subbands in a specific time interval.

34. A method of receiving a data transmission sent by a terminal to a base station in a wireless communication system utilizes orthogonal frequency division multiplexing (OFDM), comprising:

obtaining received symbols for transmission spans assigned to the terminal, wherein each transmission span in the system corresponds to a specific set of one or more subbands in a specific time interval;

receiving at the base station, from at least one neighboring base station, a blanking pattern that indicates transmission spans for which reduced interference from the terminal is sought, wherein a subset of the transmission spans assigned to the terminal is included in the blanking pattern, and wherein transmit power for the terminal is turned off or reduced for symbols sent on the transmission spans in the blanking pattern;

setting the received symbols for the transmission spans in the blanking pattern to erasures; and

processing the received symbols to obtain decoded data for the terminal.

35. A non-transient machine-readable medium comprising code, which, when executed by a machine, cause the machine to perform operations, for controlling interference caused by a transmitting entity in a wireless communication system, the code comprising instructions to:

receive at the transmitting entity from at least one base station other than the transmitting entity, at least one frequency hopping (FH) sequence assigned to at least one terminal for which reduced interference is sought;

determine a blanking pattern indicative of transmission spans for which the reduced interference from the transmitting entity is sought based on the received FH sequence;

and turn off or reduce transmit power for transmissions sent on the transmission spans in the blanking pattern.