Base station transmission power control system, mobile station and base station

• US 7,035,641 B2
• Filed: 08/06/2002
• Issued: 04/25/2006
• Est. Priority Date: 02/16/1998
• Status: Expired due to Term

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Hamabe, Kojiro, Furukawa, Hiroshi, Yoshida, Shousei
• Primary Examiner(s): Urban, Edward F.
• Assistant Examiner(s): Nguyen, Thuan T
• Application Number:
  US10/213,166
• Publication Number:
  US 20020193115A1
• Time in Patent Office: 1,358 Days
• Field of Search: 455/433, 455/456, 455/466, 455/442, 455/127.1, 455/524, 455/403, 455/436, 455/437, 455/438, 455/439, 455/522, 455/525, 455/63.1, 455/67.13, 455/67.14, 455/68
• US Class Current: 455/442
• CPC Class Codes: H04W 36/08 Reselecting an access point
• CPC Class Codes: H04W 36/18 for allowing seamless reselection, e.g. soft reselection
• CPC Class Codes: H04W 48/08 Access restriction or access information delivery, e.g. discovery data delivery signalling during connection H04W76/00
• CPC Class Codes: H04W 52/143 Downlink power control
• CPC Class Codes: H04W 52/245 taking into account received signal strength
• CPC Class Codes: H04W 52/248 where transmission power control commands are generated based on a path parameter
• CPC Class Codes: H04W 52/40 during macro-diversity or soft handoff
• CPC Class Codes: H04W 76/10 Connection setup

Abstract

In soft hand over in a code division multi access mobile radio communication system, interference in a down link caused by transmission from a plurality of base stations for one mobile station, can be restricted. Control of transmission power is performed according to command from the mobile station only in the base station serving as a primary base station which has minimum propagation loss with the mobile station during soft hand over, and the base stations other than the primary base station perform transmission with restricting output. In comparison with the transmission power control performed by the conventional plural base station transmission, interference for the peripheral mobile station can be reduced to achieve higher down link capacity. Also, upon restricting transmission power of the base station other than the base stations having small propagation loss with the mobile station among base station group in soft hand over, by moderately attenuating the transmission power instead of restricting abruptly, degradation of the reception quality can be prevented when error is caused in selection of the base station.

Claims

1. A base station transmission power control system in a code division multi access cellular mobile radio communication system comprising a plurality of base stations respectively announcing unique pilot signals and a mobile station which is capable of simultaneously establishing connection with a soft hand over base station group consisted of some of base stations out of said base stations in the system, wherein said soft hand over station group includes a primary base station having minimum propagation loss with said mobile station during soft hand over and remaining base stations being restricted outputs;

and

wherein said primary base station performs control of a transmission power according to a command from said mobile station.

2. A base station transmission power control system as set for in claim 1, wherein said mobile station takes one of base stations of said soft hand over base station group, in which a reception level of received pilot signal is maximum, as said primary base station, and controls the transmission power of said primary base station for achieving a desired communication reception quality.

3. A base station transmission power control system in a code division multi access cellular mobile radio communication system comprising a plurality of base stations respectively announcing unique pilot signals and a mobile station which is capable of simultaneously establishing connection with a soft hand over base station group consisted of some of base stations out of said base stations in the system, wherein

said mobile station detecting a communication reception quality and a primary base station among said base stations, reception level of pilot signal of which becomes maximum among pilot signals received from respective base stations in said soft hand over base stations group, notifying a base station number of said primary base station as a transmission power control signal for respective of said base stations in said soft hand over base station group when said communication reception quality is lower than a desired quality, and notifying a number other than the base station number of the base stations in said soft hand over base station group when said communication reception quality is in excess of said desired quality;

and

each base station in said soft hand over base station group receiving said transmission power control signal and being restricted a transmission power when a content of said transmission power control signal identifies number other than own base station number.

4. A base station transmission power control system in a code division multi access cellular mobile radio communication system comprising a plurality of base stations respectively announcing unique pilot signals and a mobile station which is capable of simultaneously establishing connection with a soft hand over base station group consisted of some of base stations out of said base station in the systems, wherein

said mobile station detecting a communication reception quality and a primary base station among said base stations, reception level of pilot signal of which becomes maximum among pilot signals received from respective base stations in said soft hand over base station group, increasing and decreasing the base station transmission power value managed by said mobile station so that said communication reception quality becomes a desired quality, and transmitting a transmission power control signal consisted of a base station number of said primary base station and said base station transmission power value to said soft hand over base station group, and

each base station of said soft hand over base station group receiving said transmission power control signal, setting said base station transmission power value managed by said mobile station and contained in said transmission power control signal to a transmission power value of own station when said base station number contained in said transmission power control signal is consistent with own base station number, and sets the transmission power value of own station at a restricted transmission power value when said base station number contained in said transmission power control signal is not consistent with own base station number.

5. A base station transmission power control system as set forth in claim 4, wherein said mobile station increases or decreases said base station transmission power in a magnitude corresponding to a difference between said communication reception quality and said desired quality.

6. A base station transmission power control system as set forth in claim 4, wherein said mobile station compares said communication reception quality and said desired quality for decreasing said base station transmission power value managed by said mobile station when said communication reception quality exceeds said desired quality and increasing said base station transmission power value managed by said mobile station when said communication reception quality does not exceed said desired quality.

7. A base station transmission power control system in a code division multi access cellular mobile radio communication system comprising a plurality of base stations respectively announcing unique pilot signals and a mobile station which is capable of simultaneously establishing connection with a soft hand over base station group including some of base stations out of said base stations in the system, wherein

said mobile station detects a communication reception quality and a primary base station among said base stations, reception level of pilot signal of which becomes maximum among pilot signals received from respective base stations in said soft hand over base station group, sets a power decreasing symbol in the transmission power control bit when said communication reception quality does not exceed a desired quality, sets a power decreasing symbol in the transmission power control bit when said communication reception quality exceeds said desired quality, transmits said transmission power control bit to said soft hand over base station group and intermittently transmitting said primary base station number, and

each base station of said soft hand over base station group receives said transmission power control signal which includes a primary base station number, and restricts a transmission power of own station when said primary base station number is not consistent with own base station number.

8. A base station transmission power control system as set forth in claim 7, wherein said mobile station transmits said transmission power control signal consisted of said primary base station number and said transmission power control bit to said soft hand over base station group only when variation is caused in said primary base station determined by said maximum pilot reception level, and transmits said transmission power control signal consisted of only transmission power control bit when variation of said primary base station is not caused.

9. A base station transmission power control system as set forth in claim 7, wherein said mobile station transmits the transmission power control signal consisted of only transmission power control bit to said soft hand over base station group and regularly transmits the transmission power control signal consisted of said primary base station number and said transmission power control bit to said soft hand over base station group.

10. A base station transmission power control system in a code division multiple access cellular mobile radio communication system comprising a plurality of base stations respectively announcing unique pilot signals and a mobile station which is capable of simultaneously establishing connection with a soft hand over base station group including some of base stations out of said base stations in the system, wherein

said mobile station detects a communication reception quality and a primary base station among said base stations, reception level of pilot signal of which becomes maximum among pilot signals received from respective base stations in said soft hand over base station group, sets a power increasing symbol in a transmission power control bit when said communication reception quality does not exceed a desired quality, sets a power decreasing symbol in the transmission power control bit when said communication reception quality exceeds said desired quality, transmits a transmission power control signal, including at least one of said transmission power control bit and said primary base station number, to said soft hand over base station group and;

each base station in said soft hand over base station group receives said transmission power control signal, and restricts a transmission power of own station when said primary base station number is not consistent with own base station number.

11. A base station in a code division multi access cellular mobile radio communication system announcing a unique pilot signal and its capable of simultaneously establishing connection with a mobile station together with other base stations in a soft hand over base station group consisted of some of base stations, comprising:

transmission power control signal detecting means for detecting a transmission power control signal from said mobile station; and

transmission power control means for restricting a transmission power when a primary base station information in said transmission power control signal does not identify own station.

12. A base station as set forth in claim 11, wherein said transmission power control signal detecting means comprises control signal detecting means for detecting said primary base station information or a base station transmission power decreasing information in said transmission power control signal, and said transmission power control means comprises means for restricting the transmission power when said primary base station information detected by said control signal detecting means does not identify own station.

13. A base station in a code division multi access cellular mobile radio communication system announcing a unique pilot signal and is capable of simultaneously establishing connection with a mobile station together with other base stations in a soft hand over base station group consisted of some of base stations, comprising:

control signal receiving means for receiving a transmission power control signal from said mobile station;

control signal separating means for separating a primary base station information and a base station transmission power value information from said transmission power control signal; and

transmission power control means for performing transmission with the base station transmission power indicated by said base station transmission power value information when said primary base station information separated by said control signal separating means indicates a base station information of own station, and performing transmission with a minimum transmission power when said primary base station information detected by said control signal separating means does not indicate the base station information of own station.

14. A base station in a code division multi access cellular mobile radio communication system announcing a unique pilot signal and is capable of simultaneously establishing connection with a mobile station together with other base stations in a soft hand over base station group consisted of some of base stations, comprising:

control signal receiving means for receiving a transmission power control signal from said mobile station;

primary base station information separating means for separating a primary base station information and a base station transmission power value information from said transmission power control signal, and

transmission power control means for increasing and decreasing a transmission power according to said transmission power control signal when said primary base station information is contained in said transmission power control signal and said primary base station information indicates the base station information of own station and setting the transmission power to a minimum transmission power when said primary base station information is contained in said transmission power control signal and said primary base station information does not indicate the base station information of own station.

15. A base station in a code division multi access cellular mobile radio communication system announcing a unique pilot signal and is capable of simultaneously establishing connection with a mobile station together with other base station in a soft hand over base station group consisted of some of base stations, comprising:

control signal receiving means for receiving a transmission power control signal from said mobile station; and

transmission power control means for increasing and decreasing a transmission power according to said transmission power control signal when a primary base station information is contained in said transmission power control signal and said primary base station information indicates the base station information of own station and setting the transmission power to a minimum transmission power when said primary base station information is contained in said transmission power control signal and said primary base station information does not indicate the base station information of own station.

16. A base station in a cellular mobile communication system temporarily assigned the base station number by a mobile station in soft hand over with said mobile station, comprising:

means for transmitting a pilot signal;

judgment means for receiving a transmission power control signal including a base station number selected as base station which transmits a pilot signal received by said mobile station at a maximum reception intensity among pilot signals transmitted from said base station in soft hand over and making judgment whether said base station number is consistent with a number assigned to own station or not; and

transmission power control means for performing sequential attenuation control of the transmission power with a given attenuation amount when said base station number and said number of own station are inconsistent with each other.

17. A base station as set forth in claim 16, wherein said transmission power control means controls the transmission power so that communication reception quality in said mobile station satisfies a predetermine quality when said judgment means makes judgment that said base station number is consistent with the number of own station.

18. A base station as set forth in claim 16, wherein said transmission power control means restricts transmission power when said base station number and the number of own station are inconsistent.

19. A base station transmission power control system in a code division multiple access cellular mobile radio communication system comprising a plurality of base stations respectively announcing unique pilot signals and a mobile station which is capable of simultaneously establishing connection with a group of base stations for performing soft hand over, said group comprising at least one of said plurality of base stations;

wherein said mobile station;

detects a primary base station among said base station group, said primary base station having a reception level of a pilot signal being a maximum among pilot signals received from respective base stations in said group of base stations performing soft hand over;

transmits said primary base station number to said soft hand over base station group; and

each base station in said group of base stations performing soft hand over;

receives said primary base station number; and

restricts transmission power of own station when said primary base station number is not consistent with own base station.

20. A base station in a code division multi access cellular mobile radio communication system, said base station announcing a unique pilot signal and being capable of simultaneously establishing connection with a mobile station together with other base stations in a soft hand over base station group comprising plural base stations, said base station comprising:

a transmission and reception means for transmitting a transmission signal to the mobile station;

a transmission power control means for controlling a transmission power of the transmission signal to the mobile station, said transmission and reception means receives a transmission power control signal from the mobile station, the transmission power control signal comprising a signal indicating to increase or decrease a transmission power of the transmission signal to the mobile station and a primary base station information, and

a transmission power control signal detecting means for detecting a transmission power control signal from the mobile station,

wherein said transmission power control means restricts a transmission power of the transmission signal to the mobile station in the event that the primary base station information in said transmission power control signal is not consistent with a base station information of said base station.

21. A base station according to claim 20, wherein said transmission and reception means transmits a pilot signal to the mobile station, and the primary base station is a base station which transmits a pilot signal of the maximum reception level at the mobile station among the plural base station performing a soft handover with said mobile station.

22. A base station according to claim 20 or 21, wherein the transmission power control means controls the transmission power of the transmission signal to the mobile station according to the signal indicating to increase or decrease the transmission power, which is in the transmission power control signal, in the event that the primary base station information in the transmission power control signal is consistent with the base station information of said base station.

23. A base station according to claim 22 wherein the restricted transmission power is a minimum transmission power.

24. A base station transmission power control system in a code division multi access cellular mobile radio communication system, comprising a plurality of base stations respectively announcing unique pilot signals and a mobile station which is capable of simultaneously establishing connection with a soft hand over base station group comprising some of base stations out of said plurality of base stations, wherein

said mobile station detects a communication reception quality and a primary base station among said base stations, a reception level of a pilot signal received from the primary base station is the maximum level among reception levels of pilot signals received from respective base stations in said soft hand over base station group, said mobile station sets one of a power increasing symbol and a power decreasing symbol in said transmission power control bit, and transmits said transmission power control bit and said primary base station number to said soft hand over base station group, and

each base station of said soft hand over base station group receives a transmission power control signal which includes said primary base station number, and restricts a transmission power of a transmission signal to the mobile station in the event that said primary base station number is not consistent with a base station number of said base station.

25. A base station transmission power control system according to claim 24, wherein said mobile station sets said power increasing symbol in said transmission power control bit in the event that said communication reception quality does not exceed a desired quality, and sets said power decreasing symbol in said transmission power control bit in the event that said communication reception quality exceeds said desired quality.

26. A base station transmission power control system according to claim 24 or 25, wherein said mobile station intermittently transmits said primary base station number to said soft hand over base station group.

27. A base station transmission power control system according to claim 26, wherein said base station controls the transmission power of the transmission signal to the mobile station according to one of said power increasing symbol and said power decreasing symbol in the event that said primary base station number in the transmission power control signal is consistent with the base station number of said base station.

28. A base station transmission power control system according to claim 27, wherein said restricted transmission power is a minimum transmission.

29. A communication control method in a code division multi access cellular mobile radio communication system, said communication system comprising a plurality of base stations respectively announcing unique pilot signals and a mobile station which is capable of simultaneously establishing connection with a soft hand over base station group comprising some of base stations out of said plurality of base stations said communication control method comprises:

a step of detecting a communication reception quality and a primary base station among said base stations, a reception level of a pilot signal received from the primary base station which is the maximum level among reception levels of pilot signals received from respective base stations in said soft hand over base station group;

a step of setting one of a power increasing symbol and a power decreasing symbol in a transmission power control bit; and

a step of transmitting said transmission power control bit and said primary base station number to said soft hand over base station group.

30. A communication control method according to claim 29, further comprising:

a step of receiving a transmission power control signal which includes said primary base station number, and restricting a transmission power of a transmission signal to the mobile station in the event that said primary base station number is not consistent with the base station number of said base station.

31. A communication method according to claim 29 or 30, wherein said power increasing symbol is set in said transmission power control bit in the event that said communication reception quality does not exceed a desired quality, and said power decreasing symbol is set in said transmission power control bit in the event that said communication reception quality exceeds said desired quality.

32. A communication control method according to claim 31, wherein in said primary base station number is intermittently transmitted to said soft hand over base station group.

33. A communication control method according to claim 32, further comprising a step of controlling said transmission power of the transmission signal to the mobile station according to one of said power increasing symbol and said power decreasing symbol in the event that said primary base station number in the transmission power control signal is consistent with the base station number of said base station.

34. A communication control method according to claim 33, wherein said restricted transmission power is a minimum transmission power.