# US RE45,019 E1 · Noise margin information for power control and link adaptation in IEEE 802.11h WLAN

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- Number: US RE45,019 E1
- Document ID: USRE45019E1
- Status: Granted
- Kind: E1
- Application number: 13/623,989
- Filed: 2012-09-21
- Granted: 2014-07-15
- Earliest claimed: 2001-06-29
- Assignees: Koninklijke Philips N.V.
- Applicants: Amjad Ali Soomro; Sunghyun Choi
- Inventors: Amjad Ali Soomro; Sunghyun Choi
- Web page: https://patentgrep.com/patent/USRE45019E1

## Abstract

A method and apparatus for adjusting the transmission power level or transmission data rate between a plurality of stations located within the coverage area of a basic service set (BSS) or in an independent basic service set (IBSS) in a wireless local area network (WLAN). The receiving station extracts a transmission data rate from an incoming signal, determines a signal-to-noise ratio (SNR) for the incoming signal, and then calculates noise margin information based on a difference between the SNR of the incoming signal and a minimum SNRMIN for the extracted data rate. The noise margin is then transmitted back to the original transmitting station and using the noise margin information, the transmit power level and/or the transmission rate of this station may be adjusted accordingly.

## Claims

### Claim 1

A method for transmitting data among stations in a wireless local area network (WLAN), comprising:
determining, at a receiving station, a measure of received signal power of a signal received from a transmitting station;
calculating by the receiving station a noise margin based on a difference between the measure of received signal power and a power measure required for reliable communication at a predetermined data rate of the signal; and
transmitting the noise margin from the receiving station to the transmitting station.

### Claim 2 (depends on 1)

The method of claim 1, further including:
receiving the noise margin at the transmitting station, and
adjusting at least one of a transmit power level and a transmission rate of the transmitting station based on the noise margin.

### Claim 3 (depends on 1)

The method of claim 1, wherein:
determining the measure of received signal power includes determining a signal-to-noise ratio (SNR) of the received framesignal; and
calculating the noise margin includes determining a difference between the SNR and a minimum acceptable signal-to-noise ratio (SNRMIN).

### Claim 4 (depends on 1)

The method of claim 1, further comprising storing said noise margin in a memory medium at the receiver.

### Claim 5 (depends on 1)

The method of claim 1, wherein the transmitting station is located within a basic service set (BSS) or an independent basic service set (IBSS).

### Claim 6 (depends on 1)

The method of claim 1, wherein the receiving station is a mobile unit located within a basic service set (BSS) or an independent basic service set (IBSS).

### Claim 7

A method for transmitting data among a plurality of stations located within the coverage area of a basic service set (BSS) in a wireless local area network (WLAN) comprising:
transmitting a first frame from a transmitting station;
receiving the first frame at the receiving station;
determining, at the receiving station, a transmission data rate of the first frame;
calculating, by the receiving station, a signal-to-noise ratio (SNR) of the first frame;
calculating, by the receiving station, a noise margin based on a difference between the SNR and a minimum acceptable signal-to-noise ratio (SNRMIN) for the data rate;
transmitting the noise margin from the receiving station;
receiving the noise margin at the transmitting station;
calculating, by the transmitting station, at least one of a new transmit power level and new transmission data rate based on the noise margin; and,
adjusting, at the transmitting station, at least one of a transmit power level and the transmission data rate to the at least one of a new transmit power level and a new transmission data rate.

### Claim 8 (depends on 7)

The method of claim 7, further comprising:
transmitting, by the receiving station, a second noise margin to a second station and
adjusting at least one of a transmission power level and a transmission rate of the second station based on the second noise margin.

### Claim 9 (depends on 7)

The method of claim 7, wherein the receiving station or the transmitting station are mobile units.

### Claim 10

An apparatus for determining the transmission power level between a plurality of non access point stations located within the coverage area of a basic service set (BSS) in a wireless local area network (WLAN), comprising:
means for receiving an incoming signal from a first station;
means for demodulating said incoming signal;
means for determining a transmission data rate and a measure of received signal power of the incoming signal;
means for calculating a noise margin based on a difference between the measure of received signal power and a power measure required for a predetermined threshold of communication for the transmission data rate;
means for transmitting said noise margin to the said first station, and,
means for storing said noise margin for a subsequent retrieval.

### Claim 11 (depends on 10)

The apparatus of claim 10, further comprising means for adjusting at least one of a transmit power level and a transmission rate of the apparatus, in response to said noise margin.

### Claim 12 (depends on 10)

The apparatus of claim 10, further comprising means for modulating signals indicative of said noise margin.

### Claim 13 (depends on 10)

The apparatus of claim 10, wherein the noise margin is stored for a predetermined time period.

### Claim 14 (depends on 10)

The apparatus of claim 10, wherein said signal is transmitted by a transmitting station located within a basic service set (BSS) or an independent basic service set (IBSS).

### Claim 15 (depends on 1)

The method of claim 1, wherein the transmitting station is an access point (AP) located with a basic service set (BSS).

### Claim 16 (depends on 1)

The method of claim 1, wherein the receiving station is an access point (AP) located with a basic service set (BSS).

### Claim 17 (depends on 10)

The apparatus of claim 10, wherein the first station is an access point (AP) located with a basic service set (BSS).

### Claim 18

An apparatus comprising:
a transmitter that is configured to transmit a signal at a transmit power level and a transmit data rate,
a receiver that is configured to receive a noise margin corresponding to receipt of the signal at a receiving station, wherein the noise margin is based on a difference between a measure of received signal power and a power measure required for reliable communication at a predetermined data rate of the signal, and
a processor that is configured to calculate an adjustment to at least one of the transmit power level and transmit data rate based on the noise margin, and to correspondingly adjust the at least one transmit power level and transmit data rate.

### Claim 19 (depends on 18)

The apparatus of claim 18, wherein the apparatus is a mobile station.

### Claim 20 (depends on 18)

The apparatus of claim 18, wherein the apparatus is an access point (AP) located with a basic service set (BSS).

### Claim 21

A method for transmitting data among stations in a wireless local area network (WLAN), the method comprising acts of: determining, at a receiving station, a transmission data rate and a measure of received signal power of a signal received from a transmitting station; calculating by the receiving station a noise margin based on a difference between the measure of received signal power and a power measure required for a predetermined threshold of communication for the transmission data rate; and transmitting the noise margin from the receiving station to the transmitting station.

### Claim 22 (depends on 21)

The method of claim 21, further comprising acts of: receiving the noise margin at the transmitting station; and adjusting at least one of a transmit power level and a transmission rate of the transmitting station based on the noise margin.

### Claim 23 (depends on 21)

The method of claim 21, wherein determining the measure of received signal power comprises acts of: determining a signal-to-noise ratio (SNR) of the received signal; and calculating the noise margin includes determining a difference between the SNR and a minimum acceptable signal-to-noise ratio.

### Claim 24 (depends on 21)

The method of claim 21, further comprising an act of storing the noise margin in a memory at the receiver.

### Claim 25 (depends on 21)

The method of claim 21, further comprising an act of storing the measure of received signal power in a memory at the receiver.

### Claim 26 (depends on 21)

The method of claim 21, wherein the transmitting station is located within a basic service set (BSS) which is one of an infrastructural BSS and an independent basic service set (IBSS).

### Claim 27 (depends on 21)

The method of claim 21, wherein the receiving station is a mobile unit located within a basic service set (BSS) which is one of an infrastructural BSS and an independent basic service set (IBSS).

### Claim 28

A receiver for receiving data transmitted from a transmitting station in a wireless local area network, the receiver comprising: a processor configured to: determine at the receiver, a transmission data rate and a measure of received signal power of a signal received from the transmitting station; calculate by the receiving station a noise margin based on a difference between the measure of received signal power and a power measure required for a predetermined threshold of communication for the transmission data rate; and transmit the noise margin from the receiving station to the transmitting station.

### Claim 29 (depends on 28)

The receiver of claim 28, further comprising: a signal to noise measurement circuit configured to determine the measure of received signal power by determining a signal-to-noise ratio (SNR) of the received signal; and the processor is configured to calculate the noise margin by determining a difference between the SNR and a minimum acceptable signal-to-noise ratio.

### Claim 30 (depends on 28)

The receiver of claim 28, further comprising a memory and the processor is configured to store the noise margin in the memory.

### Claim 31 (depends on 28)

The receiver of claim 28, further comprising a memory and the processor is configured to store the measure of received signal power in the memory.

### Claim 32 (depends on 28)

The receiver of claim 28, wherein the receiver is a mobile unit located within a basic service set (BSS) which is one of an infrastructural BSS and an independent basic service set (IBSS)).

### Claim 33

An apparatus for determining the transmission power level between a plurality of wireless stations in a wireless local area network (WLAN), the apparatus comprising:
a receiver configured to receive an incoming signal from a first station; a demodulator configured to demodulate the incoming signal; and a processor configured to determine a transmission data rate and a measure of received signal power of the incoming signal, calculate a noise margin based on a difference between the measure of received signal power and a power measure required for a predetermined threshold of communication for the transmission data rate, and transmit the noise margin to the first station.

### Claim 34 (depends on 33)

The apparatus of claim 33, further comprising a memory wherein the processor is configured to store the noise margin in the memory.

### Claim 35 (depends on 33)

The apparatus of claim 33, further comprising a memory wherein the processor is configured to store the measure of received signal power in the memory.

### Claim 36 (depends on 33)

The apparatus of claim 33, wherein the processor is configured to adjust at least one of a transmit power level and a transmission rate of the apparatus, in response to the noise margin.

### Claim 37 (depends on 33)

The apparatus of claim 33, further comprising a modulator configured to modulate signals indicative of the noise margin.

### Claim 38 (depends on 33)

The apparatus of claim 33, wherein the noise margin is stored for a predetermined time period.

### Claim 39 (depends on 33)

The apparatus of claim 33, wherein the signal is transmitted by a transmitting station located within a basic service set (BSS) which is one of an infrastructural BSS and an independent basic service set (IBSS).

### Claim 40 (depends on 33)

The apparatus of claim 33, wherein the first station is an access point (AP) located with a basic service set (BSS).

### Claim 41

A method for transmitting data among stations in a wireless local area network (WLAN), the method comprising acts of: determining, at a receiving station, a measure of received signal power of a signal received from a transmitting station; calculating by the receiving station a noise margin based on a difference between the measure of received signal power and a minimum power measure for a transmission data rate; and transmitting the noise margin from the receiving station to the transmitting station.

### Claim 42 (depends on 41)

The method of claim 41, further comprising acts of: receiving the noise margin at the transmitting station; and adjusting at least one of a transmit power level and a transmission rate of the transmitting station based on the noise margin.

### Claim 43 (depends on 41)

The method of claim 41, wherein determining the measure of received signal power comprises acts of: determining a signal-to-noise ratio (SNR) of the received signal; and calculating the noise margin includes determining a difference between the SNR and a minimum acceptable signal-to-noise ratio.

### Claim 44 (depends on 41)

The method of claim 41, further comprising an act of storing the noise margin in a memory at the receiver.

### Claim 45 (depends on 41)

The method of claim 41, further comprising an act of storing the measure of received signal power in a memory at the receiver.

### Claim 46 (depends on 41)

The method of claim 41, wherein the transmitting and receiving stations are located within a basic service set (BSS) which is one of an infrastructural BSS and an independent basic service set (IBSS).

### Claim 47

An apparatus comprising: a transmitter that is configured to transmit a signal at a transmit power level and a transmit data rate to a receiving station; a receiver that is configured to receive a noise margin corresponding to receipt of the signal at the receiving station, wherein the noise margin is based on a difference between a measure of received signal power and a minimum power measure for a transmission data rate; and a processor that is configured to calculate an adjustment to at least one of the transmit power level and transmit data rate based on the noise margin, and to correspondingly adjust the at least one transmit power level and transmit data rate.

### Claim 48 (depends on 47)

The apparatus of claim 47, wherein the apparatus is a mobile station.

### Claim 49 (depends on 47)

The apparatus of claim 47, wherein the apparatus is an access point (AP) located with a basic service set (BSS).

### Claim 50

A station in a wireless local area network (WLAN), the station comprising:
a processor configured to determine a measure of received signal power of a signal received from a transmitting station; calculate a noise margin based on a difference between the measure of received signal power and a minimum power measure for a transmission data rate; and transmit the noise margin to the transmitting station.

### Claim 51 (depends on 50)

The station of claim 50, further comprising a receiver configured to receive the noise margin, wherein the processor is configured to adjust at least one of a transmit power level and a transmission rate based on the noise margin.

### Claim 52 (depends on 50)

The station of claim 50, comprising a signal-to-noise measurement circuit configured to determine a signal-to-noise ratio (SNR) of the received signal, wherein the processor is configured to determine a difference between the SNR and a minimum acceptable signal-to-noise ratio.

### Claim 53 (depends on 50)

The station of claim 50, further comprising a memory, wherein the processor is configured to store the noise margin in the memory.

### Claim 54 (depends on 50)

The station of claim 50, further comprising a memory, wherein the processor is configured to store the measure of received signal power in the memory.

### Claim 55 (depends on 50)

The station of claim 50, wherein the station is located within a basic service set (BSS) which is one of an infrastructural BSS and an independent basic service set (IBSS).