Method and system for performing call admission control in the uplink for third generation wireless communication systems

Abstract

A method and system for performing call admission control in wireless communication systems is disclosed. Resource units required by a new user are assigned based on an outage probability of each uplink timeslot. The outage probability of each timeslot is updated as the resource units are assigned so that each resource unit assignment results in the lowest possible contribution to total outage probability. Once all of the resource units are assigned, the total outage probability is computed based on the resource allocation. If the total outage probability is below a predetermined value, the new user is admitted. If the total outage probability is above the predetermined value, the new user is rejected.

1 . A method for performing call admission control in a time-slotted wireless communication system, the method comprising: 
 (a) calculating an individual outage probability of each of a plurality of time slots, the individual outage probability being a probability that a signal-to-interference ratio (SIR) in a time slot falls below a predetermined SIR value; and    (b) allocating for a user one or more radio resource units to one or more time slots such that a total outage probability becomes the lowest, the total outage probability being a probability that an SIR in any allocated time slot falls below the predetermined SIR value.    
   
   
       2 . The method of  claim 1  further comprising: 
 determining whether the total outage probability is below a predetermined threshold; and    admitting the user when the determination is positive and rejecting the user when the determination is negative.    
   
   
       3 . The method of  claim 1  wherein step (b) comprises: 
 selecting a time slot having the lowest individual outage probability;    allocating the time slot one of a plurality of radio resource units; and    allocating subsequent radio resource units in a time slot in which a contribution to the total outage probability of each subsequent radio resource unit is lowest.    
   
   
       4 . An apparatus for performing call admission control in a time-slotted wireless communication system, the apparatus comprising: 
 an outage probability calculator for calculating an individual outage probability of each of a plurality of time slots, the individual outage probability being a probability that a signal-to-interference ratio (SIR) in a time slot falls below a predetermined SIR value; and    a radio resource unit allocator for allocating for a user one or more radio resource units to one or more time slots such that a total outage probability becomes the lowest, the total outage probability being a probability that an SIR in any allocated time slot falls below the predetermined SIR value.    
   
   
       5 . The apparatus of  claim 4  further comprising: 
 a controller for determining whether the total outage probability is below a predetermined threshold, whereby admitting the user when the determination is positive and rejecting the user when the determination is negative.    
   
   
       6 . The apparatus of  claim 4  wherein the radio resource unit allocator allocates one of a plurality of radio resource units to a time slot having the lowest individual outage probability, and subsequent radio resource units in a time slot where a contribution to the total outage probability of each subsequent radio resource unit is lowest.