Enhanced power control algorithms for fixed wireless access systems
AssigneeNortel Networks Limited
InventorNishith D. Tripathi
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Abstract
A method for efficient power control in a (CDMA based) fixed wireless system. The method comprises the steps of (1) monitoring a transmission link of the fixed wireless system for an occurrence of a fade, (2) recording a number of power increases to the transmission link due to said fade, and (3) reducing the power to an appropriate level when said fade is over. The adjusting step includes the steps of determining an appropriate power-down step size, which results in saving power, wherein the step size is influenced by a frame error rate (FER) and selected to maintain a desired FER, and dynamically decreasing the power by the appropriate power-down step size, thereby conserving power and increasing system capacity.
Claims19
A method for efficient power control in a wireless communications system, said method comprising the steps of:
- monitoring a transmission link of said wireless communications system for an occurrence of a fade, indicated by a received message;
- opening an observation window on receipt of said message, wherein said observation window is a period beginning when a fade is first indicated by receipt of said message and ending when the fade is no longer present as indicated by a receipt of consecutive good frames;
- recording time instances and a number of power increases to said transmission link due to said fade;
- closing said observation window when consecutive good frames are received;
- calculating an initial step down size Lo reduce the power level by an amount substantially equal to a combined amount of power increases during said fade utilizing the number of power increases following a recorded time instant within said observation period, wherein said combined amount of power increases is determined based on receipt of a first good frame of said consecutive good frames within a set number of frames following a time instance of a gain increase after the beginning of said fade;
- and
- reducing power to said transmission link by said calculated initial step down size when said fade ends.
A method for increasing capacity of a wireless communications system, said method comprising:
- monitoring a transmission link of said wireless communications system for a measurable condition that indicates an occurrence of a fade, said measurable condition from among (1) increase in a frame error rate (FER) and (2) receipt of a power measurement report message
- initiating a measurement period when an initial one of said measurable condition is detected following receipt of a sequence of good frames;
- terminating said measurement period when a first sequence of good frames is received following the initiating step;
- recording a number of power increases to said transmission link during said measurement period;
- determining which ones of said number of power increases were not required to maintain a FER of said transmission link before said fade;
- calculating an initial step down size to reduce the power level by an amount substantially equal to a combined amount of the number of power increases during said fade wherein said combined amount of power increases is determined based on receipt of a first good frame of said sequence of good frames within a set number of frames following a time instance of a gain increase after the beginning of said fade;
- and
- reducing said power to a level required to maintain said pre-fade FER by implementing an immediate power down step substantially equal to the initial step down size and then subsequently reducing said power by a step size that is a fractional part of one of said power increases during said fade, wherein said reducing of said power by said immediate power down step effectuates an increase in capacity of said fixed wireless system.
A system for implementing a feedback based power control algorithm in a wireless communications system, said system comprising:
- means for monitoring a transmission link of said wireless communications system for an occurrence of a fade, indicated by a received message;
- means for opening an observation window on receipt of said message, wherein said observation window is a period beginning when a fade is first indicated by receipt of said message and ending when the fade is no longer present as indicated by a receipt of consecutive good frames;
- means for recording time instances and a number of power increases to said transmission link due to said fade;
- means for closing said observation window when consecutive good frames are received;
- means for calculating an initial step down size to reduce the power level by an amount substantially equal to a combined amount of power increases during said fade utilizing the number of power increases following a recorded time instant within said observation period, wherein said combined amount of power increases is determined based on receipt of a fist good frame of said consecutive good frames within a set number of frames following a time instance of a gain increase after the beginning of said fade;
- and
- means for reducing power to said transmission link by said calculated initial step down size when said fade ends.
Dependencies are inferred from the claim text.