Enhanced forward link power control during soft hand-off
View Patent ↗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.
1. A method in a 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, wherein adjusting the forward link transmission power level includes:
retrieving a user specified adjustment factor and a user specified slope factor; and
calculating a sum of the user specified adjustment factor and a mathematical function that includes a ratio of forward link transmission power levels of the base station transceiver subsystem (BTS) and the dominant BTS, the mathematical function including the user specified slope factor.
2. The method of claim 1 wherein the mathematical function is equal to:
{user specified adjustment factor+(user specified factor) *10*(log[(BTS forward link transmission power level)/(dominant BTS forward link transmission power level)])}/delay.
3. The method of claim 2 wherein the user specified adjustment factor is equal to a value in the range of zero to one.
4. The method of claim 2 wherein the user specified slope factor is equal to a value in the range of zero to one.
5. 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 by:
retrieving a user specified adjustment factor and a user specified slope factor, both of which are stored in the memory; and
calculating a sum of the user specified adjustment factor and a mathematical function that includes a ratio of forward link transmission power levels of the base station transceiver system (BTS) and a dominant BTS, the mathematical function including the user specified slope factor.
6. The base station transceiver subsystem of claim 5 wherein the computer instructions further define logic for adjusting the forward link transmission power level function is equal to:
user specified adjustment factor+(user specified slope factor)*10*(log[(BTS forward link transmission power level)/(dominant BTS forward link transmission power level)[).
7. The base station transceiver subsystem of claim 5 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.