Noise margin information for power control and link adaptation in IEEE 802.11h WLAN

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.

What is claimed is: 
     
       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.   
     
     
       2. 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.   
     
     
       3. The method of  claim 1 , wherein:
 determining the measure of received signal power includes determining a signal-to-noise ratio (SNR) of the received frame; and   calculating the noise margin includes determining a difference between the SNR and a minimum acceptable signal-to-noise ratio (SNR MIN ).   
     
     
       4. The method of  claim 1 , further comprising storing said noise margin in a memory medium at the receiver. 
     
     
       5. The method of  claim 1 , wherein the transmitting station is located within a basic service set (BSS) or an independent basic service set (IBSS). 
     
     
       6. 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). 
     
     
       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 (SNR MIN ) 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.   
     
     
       8. 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.   
     
     
       9. The method of  claim 7 , wherein the receiving station or the transmitting station are mobile units. 
     
     
       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.   
     
     
       11. 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. 
     
     
       12. The apparatus of  claim 10 , further comprising means for modulating signals indicative of said noise margin. 
     
     
       13. The apparatus of  claim 10 , wherein the noise margin is stored for a predetermined time period. 
     
     
       14. 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). 
     
     
       15. The method of  claim 1 , wherein the transmitting station is an access point (AP) located with a basic service set (BSS). 
     
     
       16. The method of  claim 1 , wherein the receiving station is an access point (AP) located with a basic service set (BSS). 
     
     
       17. The apparatus of  claim 10 , wherein the first station is an access point (AP) located with a basic service set (BSS). 
     
     
       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.   
     
     
       19. The apparatus of  claim 18 , wherein the apparatus is a mobile station. 
     
     
       20. The apparatus of  claim 18 , wherein the apparatus is an access point (AP) located with a basic service set (BSS). 
     
     
       21. A system for transmitting data among wireless stations in a wireless local area network (WLAN), the system comprising:
 a wireless transmitting station and a wireless receiving station, the wireless transmitting station comprising:
 a transmitter that is configured to transmit a signal at a transmit power level and a transmit data rate to the wireless receiving station; 
 a receiver that is configured to receive a noise margin corresponding to receipt of the signal at the receiving station; 
 the wireless receiving station comprising a receiving processor configured to calculate the noise margin based on a difference between a measure of a received signal power of the transmitted signal received by the wireless receiving station from the wireless transmitting station and a power measure required for a predetermined threshold of communication that corresponds to the transmitted data rate, the receiving processor being further configured to forward the noise margin to the wireless transmitting station, 
   the wireless transmitting station further comprising a memory and a transmitting processor coupled to and configured by the memory to calculate an adjustment to at least one of the transmit power level and transmit data rate based on the received noise margin, and to correspondingly adjust the at least one transmit power level and transmit data rate for a subsequent transmission to the wireless receiving station.   
     
     
       22. The system of claim 21, wherein the transmitter, receiver, memory and processor are contained within a mobile station. 
     
     
       23. The system of claim 21, wherein the wireless transmitting and receiving stations are configured to operate within a basic service set (BSS). 
     
     
       24. A method for transmitting data among stations in a wireless local area network (WLAN), the method comprising acts of:
 transmitting from a wireless transmitting station a signal at a transmit power level and a transmit data rate to a wireless receiving station;   receiving from the wireless receiving station a noise margin corresponding to receipt of the signal at the wireless receiving station;   wherein the noise margin is calculated by the wireless receiving station based on a difference between a measure of received signal power and a power measure required for a predetermined threshold of communication that corresponds to the transmitted data rate;   calculating by the wireless transmitting station an adjustment to at least one of the transmit power level and transmit data rate based on the received noise margin; and   adjusting the at least one transmit power level and transmit data rate for a subsequent transmission to the receiving station based on the calculated adjustment.   
     
     
       25. A method for transmitting data among stations in a wireless local area network (WLAN), the method comprising acts of:
 a wireless receiving station determining a measure of received signal power of a signal having a transmit data rate received from a wireless transmitting station;   a processor of the wireless receiving station extracting the transmit data rate from the signal and calculating a noise margin based on a ratio of the received signal power to a minimum power measure that corresponds to the transmit data rate;   a transmitter of the wireless receiving station transmitting the calculated noise margin to the wireless transmitting station;   the processor of the wireless receiving station receiving a transmitting station noise margin; and   adjusting at least one of a transmit power level and a transmission rate of the wireless receiving station based on the received transmitting station noise margin.   
     
     
       26. The method of claim 25, further comprising acts of:
 receiving the calculated noise margin at the wireless transmitting station; and   adjusting at least one of a transmit power level and a transmission rate of the wireless transmitting station based on the received noise margin.   
     
     
       27. The method of claim 25, 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 including determining a difference between the SNR and a minimum acceptable signal-to-noise ratio that corresponds to the transmit data rate.   
     
     
       28. The method of claim 25, further comprising an act of storing the received transmitting station noise margin in a memory at the wireless receiving station. 
     
     
       29. The method of claim 25, further comprising an act of storing the measure of received signal power in a memory at the wireless receiving station. 
     
     
       30. The method of claim 25, 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). 
     
     
       31. The method of claim 25, wherein the wireless 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). 
     
     
       32. A wireless apparatus for transmitting data among wireless stations in a wireless local area network (WLAN), the wireless apparatus comprising:
 a transmitter that is configured to transmit a signal at a transmit power level and a transmit data rate to a wireless receiving station;   a receiver that is configured to receive a noise margin from the wireless receiving station corresponding to the signal received at the wireless receiving station; and   a memory and a processor coupled to and configured by the memory to calculate a noise margin from a received signal having a transmission data rate based on a ratio of a received signal power to a minimum power measure that corresponds to the transmission data rate, the processor being further configured to calculate an adjustment to at least one of the transmit power level and transmit data rate based on the received noise margin, and to correspondingly adjust the at least one transmit power level and transmit data rate for a subsequent transmission to the wireless receiving station.   
     
     
       33. The wireless apparatus of claim 32, wherein the transmitter, receiver, memory and processor are contained within a mobile station. 
     
     
       34. The wireless apparatus of claim 32, wherein the apparatus is configured to operate within a basic service set (BSS). 
     
     
       35. A wireless station in a wireless local area network (WLAN), the wireless station comprising:
 a transmitter;   a receiver;   a memory; and   a processor coupled to the memory, transmitter and the receiver, the processor being configured by the memory to
 determine a measure of received signal power of a signal having a transmission data rate that is received by the receiver from a wireless transmitting station; 
 calculate a noise margin based on a ratio of the received signal power to a minimum power measure that corresponds to the transmission data rate; and 
 control the transmitter to transmit the noise margin to the wireless transmitting station. 
   
     
     
       36. The wireless station of claim 35, wherein the noise margin is a first noise margin, wherein the receiver is configured to receive a second noise margin from a wireless receiving station, and wherein the processor is configured to adjust at least one of a transmit power level and a transmission rate for a subsequent transmission to the wireless receiving station based on the received second noise margin. 
     
     
       37. The wireless station of claim 35, further 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 that corresponds to the transmission data rate. 
     
     
       38. The wireless station of claim 35, wherein the processor is configured to store the noise margin in the memory. 
     
     
       39. The wireless station of claim 35, wherein the processor is configured to store the measure of received signal power in the memory. 
     
     
       40. The wireless station of claim 35, wherein the wireless station is configured to operate within a basic service set (BSS) which is one of an infrastructural BSS and an independent basic service set (IBSS).