System and method for call admission control

Abstract

A call admission control (CAC) method which operates in a network including at least one target cell and a plurality of neighboring cells under a variety of conditions. When only common measurements are available, the CAC function at a Controlling Remote Network Controller (CRNC) determines whether to accept or reject a request to setup or reconfigure a radio access bearer based on common measurements of the target cell and neighboring cells, estimated common measurements after admission, and load measurements of the target cell and the neighboring cells. When no measurements are available, the CAC function at the CRNC determines whether to accept or reject the request based on estimated load of the target cell and neighboring cells. The load is estimated based on the signal-to-interference ratio (SIR) of the requested radio access bearer, and the SIR of existing coded composite transport channels (CCTrCHs) in the target cell and neighboring cells.

1 . A method of performing call admission control (CAC) in a network including at least one target cell and a plurality of neighboring cells, the method comprising: 
 (a) receiving a request to setup or reconfigure a radio access bearer;    (b) measuring the signal-to-interference ratio (SIR) of the request;    (c) measuring the SIR of existing coded composite transport channels (CCTrCHs) in the target cell and the neighboring cells; and    (d) determining whether to accept or reject the request based upon the measurements performed in steps (b) and (c).    
   
   
       2 . The method of  claim 1  further comprising: 
 (e) determining the probability that the instantaneous load of a time slot used to fulfill the request will exceed a maximum allowed value; and    (f) further determining whether to accept or reject the request based upon the determination of step (e).    
   
   
       3 . A method of performing call admission control (CAC) in a network including at least one target cell and a plurality of neighboring cells, the method comprising: 
 (a) receiving a request to setup or reconfigure a radio access bearer;    (b) employing dedicated measurements to determine whether to accept or reject the request;    (c) if the dedicated measurements are not available, employing common measurements to determine whether to accept or reject the request;    (d) if both the dedicated and common measurements are not available, determining the probability that the instantaneous load of a time slot used to fulfill the request will exceed a maximum allowed value; and    (e) determining whether to accept or reject the request based upon the determination of step (d).    
   
   
       4 . The method of  claim 3  wherein the dedicated measurements are performed by a user equipment (UE).  
   
   
       5 . The method of  claim 3  wherein the common measurements include uplink time slot interference signal code power (ISCP).  
   
   
       6 . The method of  claim 3  wherein the common measurements include downlink carrier power.  
   
   
       7 . The method of  claim 3  wherein the common measurements are performed on at least one of the target cell and the neighboring cells.  
   
   
       8 . The method of  claim 3  wherein the determination of step (d) is based on a time variant signal-to-interference ratio (SIR).  
   
   
       9 . The method of  claim 8  wherein the time variant SIR comprises a required SIR and a SIR range of the radio access bearer.  
   
   
       10 . The method of  claim 8  wherein step (d) further comprises measuring the SIR of existing coded composite transport channels (CCTrCHs) in the target cell and the neighboring cells.  
   
   
       11 . In a network in which codes of existing coded composite transport channels (CCTrCHs) are assigned to different time slots, a method of performing call admission control (CAC) to optimize load or carrier power of a target cell and neighboring cells of the network, the method comprising: 
 (a) assigning a code of a CCTrCH to a particular time slot;    (b) determining the load of the target cell and the neighboring cells in the particular time slot;    (c) determining whether the load of the target cell and the neighboring cells is below at least one predetermined threshold;    (d) selecting the time slot that yields the lowest average load; and    (e) repeating steps (a)-(d) until all of the codes are assigned.    
   
   
       12 . In a network in which codes of existing coded composite transport channels (CCTrCHs) are assigned to different time slots, a method of performing call admission control (CAC) to optimize load or carrier power of a target cell and neighboring cells of the network, the method comprising: 
 (a) for each time slot in the target cell and the neighboring cells, determining the probability that the instantaneous load of the time slot will exceed a maximum allowed value;    (b) assigning a code of a CCTrCH to a particular one of the time slots having the lowest probability as determined in step (a);    (c) updating the instantaneous load probability of the particular time slot;    (d) repeating steps (a)-(c) until all of the codes are assigned; and    (e) determining whether or not to admit a new user to the network based on whether or not a total instantaneous load probability associated with the new user is less than a predetermined threshold.