Method and apparatus for antenna steering for WLAN

Abstract

A Station Management Entity (SME) steers a directional antenna for a station to communicate with an Access Point (AP) in an 802.11 protocol system. The SME can steer the antenna before or after an 802.11 station has authenticated and associated with the Access Point. During a passive scan, the steering process cycles through the available antenna positions and monitors an AP beacon signal to determine a best position based on, for example, a Received Signal Strength Indication (RSSI). During an active scan where access probing is used, the steering process cycles through the antenna positions and monitors a probe response to determine the best antenna position. Additional scans may be performed based on a decision that the received signal level of the currently selected antenna position has dropped below a predetermined threshold.

1 . A method for operating a directional antenna in a wireless communication system comprising: 
 causing metrics for each of a plurality of antenna angles to be calculated in a medium access control (MAC) layer;    providing said metrics to a Station Management Entity (SME) separate from said MAC layer; and    directing the antenna to a best antenna angle based on input from said SME.    
   
   
       2 . The method of  claim 1 , further comprising receiving in the MAC layer an access point signal for each antenna angle; 
 said access point signal used to calculate each of said metrics.    
   
   
       3 . The method of  claim 2 , wherein each of said access point signals is received from a respective access point.  
   
   
       4 . The method of  claim 3 , further comprising accessing the access point associated with said best antenna angle in said MAC layer.  
   
   
       5 . The method of  claim 2 , wherein said access point signal is a beacon signal.  
   
   
       6 . The method of  claim 5 , further comprising measuring said beacon signal.  
   
   
       7 . The method of  claim 6 , wherein said best antenna angle is based on a signal quality measurement of said beacon signal.  
   
   
       8 . The method of  claim 7 , wherein the signal quality measurement includes at least one of the following: signal-to-noise ratio (SNR), energy-per-bit per total noise (Eb\No), received signal strength indicator (RSSI), and a carrier to interference ratio (C\I).  
   
   
       9 . The method of  claim 1 , wherein said MAC Layer determines the metrics as a function of received energy by the directional antenna in the antenna angles.  
   
   
       10 . A mobile station in a wireless communication system comprising: 
 a Station Management Entity (SME) for directing a directional antenna to a best antenna angle; said best antenna angle determined using metrics calculated in a Medium Access Control (MAC) layer, external to said SME, for each of a plurality of antenna angles.    
   
   
       11 . The mobile station of  claim 10 , further comprising an antenna control unit coupled to the directional antenna that receives input from said SME based on said metrics.  
   
   
       12 . The mobile station of  claim 11 , wherein an access point signal is received by the MAC layer for each of said antenna angles, said access point signal used by said MAC layer to calculate each of said metrics.  
   
   
       13 . The mobile station of  claim 11 , wherein the SME causes said MAC layer to calculate said metrics.  
   
   
       14 . The mobile station of  claim 13 , wherein the SME causes the MAC layer to determine the metrics, for each of the antenna angles, as a function of energy received by the directional antenna.  
   
   
       15 . The mobile station of  claim 13 , wherein the SME causes the MAC layer to transmit a signal to the access point and to measure a response from the access point.  
   
   
       16 . The mobile station of  claim 12 , wherein said access point signal is a beacon signal.  
   
   
       17 . The mobile station of  claim 16 , further comprising measuring said beacon signal.  
   
   
       18 . The mobile station of  claim 17 , wherein said best antenna angle is based on a signal quality measurement of said beacon signal.  
   
   
       19 . The mobile station of  claim 18 , wherein the signal quality measurement includes at least one of the following: signal-to-noise ratio (SNR), energy-per-bit per total noise (Eb\No), received signal strength indicator (RSSI), and a carrier to interference ratio (C\I).