Power controlling method during a soft handoff in a mobile communication system

• US 20030045321A1
• Filed: 08/26/2002
• Published: 03/06/2003
• Est. Priority Date: 08/30/2001
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Kim, Youn-Sun, Kwon, Hwan-Joon, Choi, Ho-Kyu, Jang, Jae-Sung
• Granted Patent: US 7,548,759 B2
• Time in Patent Office: Days
• US Class Current: 455/522
• CPC Class Codes: H04B 17/24 with feedback of measurements to the transmitter
• CPC Class Codes: H04B 17/318 Received signal strength
• CPC Class Codes: H04W 36/18 for allowing seamless reselection, e.g. soft reselection
• CPC Class Codes: H04W 52/08 Closed loop power control
• CPC Class Codes: H04W 52/146 Uplink power control
• CPC Class Codes: H04W 52/24 using SIR [Signal to Interference Ratio] or other wireless path parameters
• CPC Class Codes: H04W 52/32 TPC of broadcast or control channels
• CPC Class Codes: H04W 52/40 during macro-diversity or soft handoff
• CPC Class Codes: H04W 52/58 Format of the TPC bits

Abstract

A power control method during a soft handoff in a mobile communication system. A mobile station communicating with a plurality of base stations at a soft handoff measures the signal strengths of forward common pilot channels received from the base stations and transmit them to the base stations sequentially. Then the base stations control the transmission power of forward common power control channels according to the received signal strength measurements.

Claims

1. A method of transmitting signal strength measurements of forward channels received from a plurality of base stations communicating with a mobile station at a soft handoff to the base stations from the mobile station in a mobile communication system, comprising the steps of:

assigning time slots to the base stations; and

transmitting the signal strength measurements to the base stations in the respective assigned time slots.

2. The method of claim 1, wherein the signal strength measurements are carrier to interference ratios of forward common pilot channels.

3. The method of claim 1, wherein the time slots are assigned when one of the base stations is dropped or a new base station is added to the base stations.

4. The method of claim 3, wherein the one of the base stations is dropped or the new base station is added when one of the signal strength measurements of the forward channels received from adjacent base stations including the base stations communicating with the mobile station at the soft handoff is less than a second threshold continuously for a predetermined time period, or greater than a first threshold.

5. The method of claim 1, wherein the time slots are assigned according to the signal strength measurements.

6. The method of claim 1, wherein an indicator indicating a base station having a highest signal strength among the base stations is transmitted in the transmission step.

7. A method of transmitting signal strength measurements of forward channels received from a plurality of base stations communicating with a mobile station at a soft handoff to the base stations from the mobile station in a mobile communication system, comprising the steps of:

receiving information about time slots assigned to the base stations from a service base station among the base stations; and

transmitting the signal strength measurements to the base stations in the respective assigned time slots.

8. The method of claim 7, wherein the signal strength measurements are carrier to interference ratios of forward common pilot channels.

9. The method of claim 7, wherein an indicator indicating a base station having a highest signal strength among the base stations is transmitted in the transmission step.

10. A signal strength measurement transmitting method in a mobile station communicating with a plurality of base stations at a soft handoff in a mobile communication system, comprising the steps of:

measuring signal strengths of forward channels received from the base stations; and

transmitting the signal strength measurements to the base stations, sequentially.

11. A power control method in base stations communicating with a mobile station at a soft handoff in a mobile communication system, comprising the steps of:

receiving signal strength measurements of first forward channels from the mobile station in time slots assigned to the base stations; and

controlling transmission power of second forward channels according to the received signal strength measurements.

12. The method of claim 11, wherein the signal strength measurements of the first forward channels are carrier to interference ratios of forward common pilot channels.

13. The method of claim 11, wherein an indicator indicating a base station having a highest signal strength among the base stations is received in the reception step.

14. The method of claim 11, further comprising the steps of:

measuring signal strengths of a reverse channel received from the mobile station;

generating power control commands for the reverse channel according to the signal strength measurements of the reverse channel; and

transmitting power control commands to the mobile station.

15. A signal strength measurement receiving method for a forward power control in a service base station among a plurality of base stations communicating with a mobile station at a soft handoff in a mobile communication system, comprising the steps of:

assigning time slots to the base stations;

transmitting information about the time slot assignment to the other base stations; and

receiving a signal strength measurement of a first forward channel from the mobile station in time slots assigned to the service base station.

16. The method of claim 15, wherein the signal strength measurement of the first forward channel is a carrier to interference ratio of a forward common pilot channel.

17. The method of claim 15, wherein the time slots are assigned when one of the base stations is dropped or a new base station is added to the base stations.

18. The method of claim 15, wherein the time slots are assigned according to signal strength measurements of forward channels from the base stations.

19. The method of claim 15, wherein the time slot assignment information is transmitted to the mobile station in the transmission step.

20. The method of claim 15, wherein an indicator indicating a base station having a highest signal strength is received in the reception step.

21. The method of claim 15, further comprising the step of controlling a transmission power of a second forward channel according to the received signal strength measurement of the first forward channel.

22. The method of claim 15, further comprising the steps of:

measuring a signal strength of a reverse channel received from the mobile station;

generating a power control command for the reverse channel according to the signal strength measurement of the reverse channel; and

transmitting a power control command to the mobile station.

23. A power control method in a base station communicating with a mobile station that is also communicating with a plurality of other base stations adjacent to the base station due to a soft handoff in a mobile communication system, comprising the steps of:

generating a power control command for a reverse channel quality indicator channel received from the mobile station according to a signal strength measurement of the reverse channel quality indicator channel;

transmitting the power control command for the reverse channel quality indicator channel to the mobile station on a forward common power control channel in pre-assigned time slots;

generating a power control command for a reverse pilot channel received from the mobile station according to a signal strength measurement of the reverse pilot channel; and

transmitting the power control command for the reverse pilot channel to the mobile station on the forward common power control channel in remaining time slots.

24. The method of claim 23, wherein the signal strength measurements of the reverse channel quality indicator channel and the reverse pilot channel are carrier to interference ratios of the reverse channel quality indicator channel and the reverse pilot channel.

25. The method of claim 23, further comprising the steps of:

receiving a signal strength measurement of a first forward channel from the mobile station in the pre-assigned time slots; and

controlling a transmission power of a second forward channel according to the received signal strength measurement of the first forward channel.

26. The method of claim 25, wherein an indicator indicating a base station having a highest signal strength is received in the reception step.

27. A power control method in a mobile station communicating with a first base station and a plurality of other base stations adjacent to the first base station due to a soft handoff in a mobile communication system, comprising the steps of:

receiving a power control command for a reverse channel quality indicator channel each of the first base station and the adjacent base stations in pre-assigned time slots;

controlling a transmission power of the reverse channel quality indicator channel according to the received power control commands;

receiving a power control command for a reverse pilot channel in remaining time slots from each of the first base station and the adjacent base stations; and

controlling a transmission power of the reverse pilot channel according to the received power control commands.

28. The method of claim 27, further comprising the steps of:

measuring signal strengths of forward channels received from the base stations including the first base station; and

transmitting the signal strength measurements of the forward channels to the base stations including the first base station.

29. The method of claim 28, wherein the signal strengths of the forward channels are carrier to interference ratios of forward common pilot channels.

30. The method of claim 28, wherein an indicator indicating a base station having a highest signal strength is transmitted in the transmission step.