Method and system for station location based neighbor determination and handover probability estimation

Abstract

The present invention is a method and system for station location based neighbor determination and handover probability estimation. A serving access point determines the location and movement measurements of a station (STA). Neighboring access points report coordinates of cell fringes of the neighboring access points. The STA sends a request for system information to the current access point along with current location of the STA. The current access point provides the system information, and the STA utilizes the system information to determine best handover candidate from among neighboring access points and an estimate of the time for handover.

1 . A method for dynamic estimation of probability and initiation time for handover of a station (STA) in a wireless communication system having a serving access point (AP) and a plurality of neighboring APs, the method comprising: 
 determining the location of the STA and speed and direction of movement;    reporting coordinates of cell boundaries of neighboring APs;    the STA sending a request for system information to the serving AP;    the serving AP providing the system information; and    determining probability of handover to each neighboring AP and an estimate of the initiation time for handover based on the STA location and speed and direction of movement and the cell boundary coordinates.    
   
   
       2 . The method of  claim 1 , wherein the neighboring APs are associated with heterogeneous networks.  
   
   
       3 . The method of  claim 1  wherein the request also provides measurements on other APs and base stations.  
   
   
       4 . The method of  claim 3 , further comprising: 
 associating weighting factors to each neighboring AP according to metrics related to the probability of handover of the STA from the serving AP, whereby the serving AP determines a neighboring AP with highest probability for handover.    
   
   
       5 . The method of  claim 6  wherein the weighting factor is based on received signal quality taken from neighboring APs as reported by the STA.  
   
   
       6 . The method of  claim 1 , wherein the serving AP provides network topology information and the STA uses the information to estimate distance to the cell boundary.  
   
   
       7 . The method of  claim 1  wherein the system information is requested at system access by the STA.  
   
   
       8 . The method of  claim 1  wherein the STA requests update of the system information based on the speed and direction of the STA's movement.  
   
   
       9 . The method of  claim 8  wherein the update is triggered when a signal quality becomes below a predetermined threshold.  
   
   
       10 . The method of  claim 1  wherein the measurements on APs and base stations other than the serving AP and base station are performed by other STAs within the network.  
   
   
       11 . A method for dynamic estimation of probability and initiation time for handover of a station (STA) in a wireless communication network having an access controller (AC), a serving access point (AP) and a plurality of neighboring APs, the method comprising: 
 determining the location and direction of movement of the STA by the AC;    reporting coordinates of cell boundaries of neighboring APs;    the STA sending a request for system information to the AC;    the serving AC providing the system information; and    the STA utilizing the system information to determine probability of handover to each neighboring AP and an estimate of the initiation time for handover.    
   
   
       12 . The method of  claim 11 , wherein the request is made at system access or as required by the STA.  
   
   
       13 . The method of  claim 11 , further comprising the STA providing its current location coordinates based on GPS or a network map provided by the network, or both.  
   
   
       14 . In a wireless network having a plurality of access points, a mobile wireless transmit/receive unit (WTRU), comprising: 
 a processor configured to determine geographical coordinates of the WTRU, determine signal strengths of signals received from neighboring access points, and calculate a probability of handover for at least one neighboring access point.    
   
   
       15 . The WTRU of  claim 14 , wherein the processor is further configured to calculate a time until an expected handover for at least one neighboring access point.  
   
   
       16 . The WTRU of  claim 14 , wherein the processor is further configured to receive measurements of the WTRU's movement determined by a serving access point according to the geographical coordinates of the WTRU.  
   
   
       17 . The WTRU of  claim 14 , wherein the processor performs multiple determinations of geographical position of the WTRU.  
   
   
       18 . The WTRU of  claim 14 , wherein the processor is further configured to receive network topology that includes cell boundary definitions of at least one neighboring access point.  
   
   
       19 . The WTRU of  claim 14 , wherein multiple handover probabilities are determined and ranked by the processor to permit selection of a best handover candidate from among the neighboring access points.  
   
   
       20 . A wireless network having a plurality of access points (AP), comprising: 
 a mobile station (STA) configured to determine its geographical coordinates and its speed and direction of movement;    an access controller configured to report network topology information to the STA including cell boundaries of the APs; and    a serving access point (AP) configured to handover the STA to the target AP according to an estimated handover initiation time;    wherein the STA estimates the handover initiation time based on the network topology information and the determination of speed and direction of movement.