Channel resource allocation in a cloud radio access network

Abstract

A communication system for performing DRX-aware channel resource allocation is described. The communication system includes a plurality of radio points (RPs), each configured to exchange radio frequency (RF) signals with a plurality of user equipment (UEs) at a site. The communication system also includes a baseband controller communicatively coupled to the plurality of radio points. The baseband controller is configured to reallocate a second UE's channel resource in a first UE's DRX subcycle, for RPs in a first UE's combining zone vector (CZV), from a second UE to a first UE, wherein the first UE's CZV matches the second UE's CZV.

1 . A communication system for performing DRX-aware channel resource allocation, comprising:
 a plurality of radio points (RPs), each configured to exchange radio frequency (RF) signals with a plurality of user equipment (UEs); and   a baseband controller communicatively coupled to the plurality of radio points, wherein the baseband controller is configured to:
 reallocate a second UE's channel resource in a first UE's DRX subcycle, for RPs in a first UE's combining zone vector (CZV), from a second UE to a first UE, wherein the first UE's CZV matches the second UE's CZV. 
   
     
     
         2 . The communication system of  claim 1 , wherein the first UE is assigned to a first DRX subcycle, wherein the second UE is assigned to a second DRX subcycle. 
     
     
         3 . The communication system of  claim 2 , wherein the reallocating comprises:
 determining that the second UE's channel resource is reserved, for the RPs in the first UE's CZV, in all the DRX subcycles;   releasing the second UE's channel resource, for the RPs in the first UE's CZV, in all DRX subcycles except the second UE's DRX subcycle; and   allocating the second UE's channel resource in the first UE's DRX subcycle, for the RPs in the first UE's CZV, to the first UE.   
     
     
         4 . The communication system of  claim 1 , wherein the baseband controller is further configured to trigger the DRX-aware channel resource allocation for the first UE. 
     
     
         5 . The communication system of  claim 4 , wherein the DRX-aware channel resource allocation is triggered in response to at least one of:
 an RP in the communication system reaching or exceeding a threshold number of UEs it can serve;   a group of RPs in the communication system reaching or exceeding a second threshold number of UEs the group can serve; and   a DRX-enabled UE attaching to the communication system or moving within a coverage site of the communication system to which it has previously attached.   
     
     
         6 . The communication system of  claim 1 , wherein the baseband controller is configured to determine which RPs are in the first UE's CZV based on whether each RP receives a transmission from the first UE with a signal metric that exceeds a threshold or drops below the threshold. 
     
     
         7 . The communication system of  claim 1 , wherein the baseband controller is further configured to:
 search for a channel resource that is available on all the DRX subcycles for the RPs in a first UE's combining zone vector (CZV); and   when the search for the channel resource is unsuccessful:
 reallocate the second UE's channel resource in the first UE's DRX subcycle to the first UE; and 
 release the second UE's channel resource in at least one additional DRX subcycle that is different than the first UE's DRX subcycle and the second UE's DRX subcycle. 
   
     
     
         8 . The communication system of  claim 7 , wherein the baseband controller is further configured to, when the search for the channel resource is successful, assign the channel resource to the first UE on all the DRX subcycles for the RPs in the first UE's CZV. 
     
     
         9 . The communication system of  claim 8 , wherein each PUCCH resource is defined by:
 a particular subframe within a system frame;   a physical resource block (PRB) within the particular subframe; and   a cyclic shift.   
     
     
         10 . The communication system of  claim 9 , wherein each PUCCH resource is further defined by an orthogonal sequence used in the PRB. 
     
     
         11 . A method for DRX-aware channel resource allocation in a communication system, the communication system comprising a baseband controller and a plurality of radio points (RPs), wherein each radio point is configured to exchange radio frequency (RF) signals with a plurality of user equipment (UEs), the method comprising:
 reallocating a second UE's channel resource in a first UE's DRX subcycle, for RPs in a first UE's combining zone vector (CZV), from a second UE to the first UE, wherein the first UE's CZV matches the second UE's CZV.   
     
     
         12 . The method of  claim 11 , wherein the first UE is assigned to a first DRX subcycle, wherein the second UE is assigned to a second DRX subcycle. 
     
     
         13 . The method of  claim 12 , wherein the reallocating comprises:
 determining that the second UE's channel resource is reserved, for the RPs in the first UE's CZV, in all the DRX subcycles;   releasing the second UE's channel resource, for the RPs in the first UE's CZV, in all DRX subcycles except the second UE's DRX subcycle; and   allocating the second UE's channel resource in the first UE's DRX subcycle, for the RPs in the first UE's CZV, to the first UE.   
     
     
         14 . The method of  claim 11 , further comprising triggering the DRX-aware channel resource allocation for the first UE. 
     
     
         15 . The method of  claim 14 , further comprising triggering the DRX-aware channel resource allocation in response to at least one of:
 an RP in the communication system reaching or exceeding a threshold number of UEs it can serve;   a group of RPs in the communication system reaching or exceeding a second threshold number of UEs the group can serve; and   a DRX-enabled UE attaching to the communication system or moving within a coverage site of the communication system to which it has previously attached.   
     
     
         16 . The method of  claim 11 , further comprising determining which RPs are in the first UE's CZV based on whether each RP receives a transmission from the first UE with a signal metric that exceeds a threshold or drops below the threshold. 
     
     
         17 . The method of  claim 11 , further comprising:
 searching for a channel resource that is available on all the DRX subcycles for the RPs in a first UE's combining zone vector (CZV); and   when the search for the channel resource is unsuccessful:
 reallocate the second UE's channel resource in the first UE's DRX subcycle to the first UE; and 
 release the second UE's channel resource in at least one DRX subcycle that is different than the first UE's DRX subcycle and the second UE's DRX subCycle. 
   
     
     
         18 . The method of  claim 17 , further comprising, when the search for the channel resource is successful, assigning the channel resource to the first UE on all the DRX subcycles for the RPs in the first UE's CZV. 
     
     
         19 . The method of  claim 18 , wherein each PUCCH resource is defined by:
 a particular subframe within a system frame;   a physical resource block (PRB) within the particular subframe; and   a cyclic shift.   
     
     
         20 . The method of  claim 19 , wherein each PUCCH resource is further defined by an orthogonal sequence used in the PRB.