Enhanced forward link power control during soft hand-off

• US 20040106423A1
• Filed: 12/02/2002
• Published: 06/03/2004
• Est. Priority Date: 12/02/2002
• Status: Active Grant

• Current Assignee: Ericsson AB (Telefonaktiebolaget LM Ericsson)
• Original Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Inventors: Chheda, Ashvin, Ren, Hong, McGowan, Neil N.
• Granted Patent: US 7,127,267 B2
• Time in Patent Office: Days
• US Class Current: 455/522
• CPC Class Codes: H04L 1/004 by using forward error control H04L1/0618 takes precedence; coding, decoding or code conversion, for error detection or correction H03M13/00
• CPC Class Codes: H04L 1/203 Details of error rate determination, e.g. BER, FER or WER
• 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 52/12 Outer and inner loops
• CPC Class Codes: H04W 52/40 during macro-diversity or soft handoff
• CPC Class Codes: H04W 88/08 Access point devices

Abstract

A plurality of base station transceiver subsystems determine whether to scale the forward link transmission power level and, if so, by what amount to control forward link transmission power level mismatch. The plurality of base stations transmit reverse link signal-to-noise ratio information and forward link transmission power levels for a specified transmission to the base station controller. The base station controller compares the reverse link signal-to-noise ratio readings received from each of the plurality of base stations to determine and select a dominant base station. The base station controller then transmits the dominant base station'"'"'s forward link transmission power level for the specified transmission to each of the plurality of base stations that is communicating with the mobile station that is in hand-off. Each base station, accordingly, determines whether to scale its forward link transmission power level.

Claims

1. A method, in a base station transceiver subsystem, for adjusting a forward link transmission power level, comprising:

determining and transmitting a frame error rate target to a mobile station;

receiving power control commands from the mobile station over a reverse link control channel;

adjusting the power according to the received power control commands;

transmitting reverse link information to a base station controller for the mobile station;

transmitting the forward link transmission power level to the base station controller for a previous transmission to the mobile station;

receiving a base station transceiver subsystem forward link transmission power level for a corresponding transmission from the base station controller wherein the forward link transmission power level reflects a forward link transmission power level of a dominant base station transceiver subsystem; and

responsive to the receiving step, scaling and adjusting the forward link transmission power level.

2. The method of claim 1 further comprising the step of comparing the dominant base station transceiver subsystem forward link transmission power level to the transmitted power level wherein the transmitted power level is for a corresponding transmission to the mobile station by the base station transceiver subsystem.

3. The method of claim 2 including the step of determining that the dominant base station transceiver subsystem forward link transmission power level is equal to the corresponding transmission to the mobile station by the base station transceiver set and determining that the dominant base station transceiver set is the base station transceiver subsystem.

4. The method of claim 3 wherein the base station transceiver subsystem does not adjust its forward link transmission power level to the mobile station in response to receiving the dominant base station transceiver subsystem forward link transmission power level.

5. The method of claim 4 including determining that the dominant base station transceiver subsystem forward link transmission power level is not equal to the corresponding transmission to the mobile station by the base station transceiver subsystem.

6. The method of claim 5 wherein the step of transmitting reverse link information includes transmitting a reverse link signal quality indication to the base station controller to enable the base station controller to estimate which base station transceiver subsystem communicating to the mobile station in hand-off is most proximate to the mobile station.

7. The method of claim 6 wherein the base station transceiver subsystem adjusts its forward link transmission power level as a function of the forward link transmission power level of the dominant base station transceiver subsystem.

8. The method of claim 7 wherein the base station transceiver subsystem adjusts its forward link transmission power level according to a sum of an adjustment factor and to a mathematical function that includes a ratio of forward link transmission power levels of the base station transceiver subsystem and the dominant base station transceiver subsystem.

9. A method in a first base station transceiver subsystem for adjusting a forward link transmission power level to a mobile station in hand-off between the base station transceiver subsystem and a dominant base station transceiver subsystem in a code division multiple access network, comprising:

receiving a forward link transmission power level of the dominant base station transceiver subsystem to the mobile station in hand-off; and

adjusting the forward link transmission power level to the mobile station in hand-off responsive to the forward link transmission power level of the dominant base station transceiver subsystem.

10. The method of claim 9 wherein a sum of an adjustment factor and a mathematical function that includes a ratio of forward link transmission power levels of the base station transceiver subsystem and the dominant base station transceiver subsystem is calculated as a part of the adjusting step.

11. The method of claim 9 wherein the adjusting step includes retrieving a user specified adjustment factor and a user specified slope for use in determining the sum.

12. The method of claim 11 wherein the mathematical function is equal to:

{Adjustment factor+(specified slope factor)*10*(Log[(BTS power level)/(dominant BTS power level)]}/delay

13. The method of claim 12 wherein the adjustment factor is equal to a value in the range of zero to one.

14. The method of claim 12 wherein the specified slope factor is equal to a value in the range of zero to one.

15. A base station transceiver subsystem, comprising:

a bus;

a processor coupled to communicate over the bus;

a network port for coupling the base station transceiver subsystem to a wireless communication network to enable the base station transceiver subsystem to communicate with a base station controller; and

a memory coupled to the bus, the memory including computer instructions that define logic for;

receiving a forward link transmission power level indication by way of the network port from the base station controller;

determining whether the received forward link transmission power level indication matches a forward link transmission power level for a corresponding forward link transmission power level to a mobile station in hand-off; and

if the forward link transmission power levels do not approximately match, adjusting the forward link transmission power level.

16. The base station transceiver subsystem of claim 15 wherein the computer instructions further define logic for determining a sum of an adjustment factor and a mathematical function that includes a ratio of forward link transmission power levels of the base station transceiver subsystem and of a dominant base station transceiver.

17. The base station transceiver subsystem of claim 15 wherein the computer instructions further define logic for retrieving a user specified adjustment factor and a user specified slope, both of which are stored in memory, for use in determining the sum.

18. The base station transceiver subsystem of claim 15 wherein the computer instructions further define logic for adjusting the forward link transmission power level function is equal to:

Adjustment factor+10*(specified slope factor)*(Log[(first BTS power level)/(dominant BTS power level)]

19. The base station transceiver subsystem of claim 15 wherein the computer instructions further define logic for prompting the base station transceiver subsystem to transmit its forward link transmission power level to a base station controller for the mobile station that is in hand-off.

20. The base station transceiver subsystem of claim 15 wherein the computer instructions define logic for adjusting the forward link transmission power level to be a scaled value relative to a forward link transmission power level of a dominant base station transceiver subsystem.