Systems and methods for adjusting transmit power in wireless local area networks
First Claim
1. A method comprising adjusting a communication station transmit power level for orthogonal frequency-division multiplexed signal transmissions to an access point based on an access point sensitivity, a path loss, and a link margin variation,wherein the access point sensitivity is calculated by subtracting the path loss and an access point link margin from the communication station transmit power level.
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Accused Products
Abstract
A communication station performs closed-loop transmit power control and adjusts its transmit power level based on an access point sensitivity, a path loss and/or a link margin variation. An average received power level of orthogonal frequency-division multiplexed (OFDM) subcarriers of an OFDM channel may be measured at the communication station, and the path loss may be estimated from an access point transmit power level and the measured power level. The communication station may request an access point'"'"'s transmit power level and link margin from the access point prior to estimating the path loss. The communication station may calculate the access point sensitivity by subtracting the path loss and the access point link margin from the communication station'"'"'s transmit power level. The link margin variation may be estimated from an access point transmit power variation, an indoor path loss variation, and/or a receiver power measurement error of the communication station.
83 Citations
24 Claims
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1. A method comprising adjusting a communication station transmit power level for orthogonal frequency-division multiplexed signal transmissions to an access point based on an access point sensitivity, a path loss, and a link margin variation,
wherein the access point sensitivity is calculated by subtracting the path loss and an access point link margin from the communication station transmit power level.
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13. A method comprising:
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adjusting a communication station transmit power level for orthogonal frequency-division multiplexed signal transmissions to an access point based on an access point sensitivity, a path loss, and a link margin variation; reporting a communication station link margin and the communication station transmit power level to the access point, wherein the access point is to determine whether to adjust an access point transmit power level based on the communication station link margin and transmit power level, wherein the method further comprises prior to the reporting; determining a data rate of an orthogonal frequency-division multiplexed symbol received by a communication station; determining a communication station sensitivity based on the data rate, the communication station sensitivity being either predetermined or precalibrated for various data rates; and calculating the communication station link margin from the data rate and the communication station sensitivity, wherein the determining the communication station sensitivity comprises looking up the communication station sensitivity in a table based on the data rate.
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14. A method comprising adjusting a communication station transmit power level for orthogonal frequency-division multiplexed signal transmissions to an access point based on an access point sensitivity, a path loss, and a link margin variation,
wherein the method comprises: -
measuring an average power level across orthogonal frequency-division multiplexed subcarriers of a subchannel received by a communication station; estimating the path loss from an access point transmit power level and the measured average power level; calculating the access point sensitivity by subtracting the path loss and an access point link margin from the communication station transmit power level; estimating the link margin variation from at least one of an access point transmit power variation, an indoor path loss variation, and a receiver power measurement error of the communication station; and requesting the access point transmit power level and the link margin from the access point prior to calculating the access point sensitivity, wherein the adjusting comprises setting the communication station transmit power level by an amount substantially comprising the sum of the access point sensitivity, the path loss and the link margin variation.
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15. A communication station comprising:
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a transmitter to transmit orthogonal frequency-division multiplexed signals to an access point; a controller to adjust a communication station transmit power level of the transmitter based on an access point sensitivity, a path loss, and a link margin variation; and a receiver to receive orthogonal frequency division multiplex communication signals, wherein the controller is to measure a received power level of the orthogonal frequency-division multiplexed signals and estimate the path loss from an access point transmit power level and the measured received power level, wherein the controller is to configure the transmitter to report a communication station link margin and the communication station transmit power level to the access point, wherein the access point is to responsively determine whether to adjust the access point transmit power level based on the reported communication station link margin and communication station transmit power level, wherein prior to configuring the transmitter to report, the controller is to; determine a data rate of an orthogonal frequency-division multiplexed symbol received by the receiver; determine a communication station sensitivity based on the data rate, the communication station sensitivity being either predetermined or precalibrated for various data rates; and calculate the communication station link margin from the data rate and the communication station sensitivity. - View Dependent Claims (16, 17)
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18. A communication station comprising:
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a transmitter to transmit orthogonal frequency-division multiplexed signals to an access point; a controller to adjust a communication station transmit power level of the transmitter based on an access point sensitivity, a path loss, and a link margin variation; and a receiver to receive orthogonal frequency division multiplex communication signals, and wherein the controller is to measure a received power level of the orthogonal frequency-division multiplexed signals and estimate the path loss from an access point transmit power level and the measured received power level, wherein the controller is to configure the transmitter to send a request message to the access point to request the access point transmit power level and an access point link margin prior to estimating the path loss, wherein the controller is to calculate the access point sensitivity by subtracting the path loss and the access point link margin from the communication station transmit power level, wherein the controller comprises a digital signal processor, and wherein the controller is to perform an open-loop transmit power control procedure when the access point transmit power level is not received from the access point, wherein as part of the open-loop transmit power control process, the controller is to; retrieve a communication station receiver sensitivity based on a data rate of an orthogonal frequency-division multiplexed symbol from a table; and reduce the communication station transmit power level by a first amount when the received power level exceeds the communication station receiver sensitivity by a second amount.
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19. A system comprising:
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a substantially omnidirectional antenna; a transmitter to transmit orthogonal frequency-division multiplexed signals to an access point via the antenna; and a controller to adjust a communication station transmit power level of the transmitter based on an access point sensitivity, a path loss, and a link margin variation, wherein the access point sensitivity is calculated by the controller by subtracting the path loss and an access point link margin from the communication station transmit power level. - View Dependent Claims (20, 21)
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22. A system comprising:
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a substantially omnidirectional antenna; a transmitter to transmit orthogonal frequency-division multiplexed signals to an access point via the antenna; and a controller to adjust a communication station transmit power level of the transmitter based on an access point sensitivity, a path loss, and a link margin variation, wherein the system comprises a communication station that is to operate as part of a wireless local area network communicating orthogonal division multiplexed signals with the access point, and wherein the orthogonal frequency-division multiplexed signals are within a subchannel comprising a plurality of orthogonal frequency-division multiplexed subcarriers, and wherein each subcarrier of the subchannel has a null at substantially a center frequency of other subcarriers of the subchannel, wherein the controller comprises a digital signal processor, wherein the controller is to perform an open-loop transmit power control procedure when the access point transmit power level is not received from the access point, and wherein as part of the open-loop transmit power control procedure, the controller is to; retrieve a communication station receiver sensitivity based on a data rate of an orthogonal frequency-division multiplexed symbol from a table; and reduce the communication station transmit power level by a first amount when the received power level exceeds the communication station receiver sensitivity by a second amount.
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23. A computer readable medium that stores instructions for execution by one or more processors, causing said processors to perform operations comprising adjusting a communication station transmit power level for orthogonal frequency-division multiplexed signal transmissions to an access point based on an access point sensitivity, a path loss, and a link margin variation,
wherein the operations further comprise: -
measuring a received power level of orthogonal frequency-division multiplexed signals at a communication station; estimating the path loss from an access point transmit power level and the measured received power level; and
calculating the access point sensitivity by subtracting the path loss and an access point link margin from the communication station transmit power level. - View Dependent Claims (24)
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Specification