Relay Enhanced Cellular Telecommunication Network

Abstract

Systems and techniques for avoiding inefficiencies resulting from failed handover attempts. A base station selects one or more mobility management entity (MME) pools for assignment to a relay nod; with the selection being performed so as to minimize or eliminate handover attempts requiring that a target device support a particular MME pool when the MME pool is not supported by the MME. A base station selects, when communicating with a relay node, a subset of the MME pools that it supports and assigns the subset to the base station. UEs served by the relay node are assigned the MME pool or MME pools assigned to the relay node. The relay node is informed of the MME pools supported by one or more neighbor nodes and, when attempting a handover to a neighbor node, attempts an X2 handover only to neighbor nodes supporting an MME pool assigned to the relay node.

We claim: 
     
         1 . A method comprising:
 selecting a single mobility management entity pool for all user equipments connected to a specified relay node associated with a donor base station; and   communicating the identity of the selected mobility management entity pool to the specified relay node.   
     
     
         2 . The method of  claim 1 , wherein communicating the identity of the selected mobility management entity pool to the specified relay node is performed using one or more of X2 setup and update procedures. 
     
     
         3 . A method comprising:
 identifying a mobility management entity pool serving a user equipment associated with a relay node operating in a wireless network;   receiving information identifying one or more mobility management entity pools supported by a handover target;   comparing the one or more mobility management entity pools supported by the handover target to the mobility management entity pool serving the user equipment;   if the handover target supports the mobility management entity pool serving the user equipment, initiating an X2 handover to handover the mobility management entity to the target; and   if the handover target does not support the mobility management entity pool serving the user equipment, initiating an S1 handover to handover the user equipment to the target.   
     
     
         4 . The method of  claim 3 , wherein the information identifying the one or more mobility management entity pools supported by the handover target is received from a donor base station in a configuration update. 
     
     
         5 . The method of  claim 3 , wherein the information identifying the one or more mobility management entity pools supported by the handover target is sent by the donor base station in response to a change in the one or more mobility management entity pools supported by a neighbor node. 
     
     
         6 . The method of  claim 3 , wherein the relay node sends information to the donor base station specifying mobility management entity pools supported by neighbors of the relay node, and wherein the information is sent to the donor base station during either an X2 or an X2 setup response procedure. 
     
     
         7 . The method of  claim 3 , wherein the relay node receives from the donor base station information identifying all mobility management entity pools meeting the condition that the mobility management entity pool is supported by all neighbors of the relay node. 
     
     
         8 . A non-transitory computer readable medium storing a program of instructions, execution of which by a processor causes an apparatus to at least:
 identify a mobility management entity pool serving a user equipment associated with a relay node operating in a wireless network;   receive information identifying one or more mobility management entity pools supported by a handover target;   compare the one or more mobility management entity pools supported by the handover target to the mobility management entity pool serving the user equipment;   if the handover target supports the mobility management entity pool serving the user equipment, initiate an X2 handover to handover the user equipment to the target; and   if the handover target does not support the mobility management entity pool serving the user equipment, initiate an S1 handover to handover the user equipment to the target.   
     
     
         9 . An apparatus comprising:
 at least one processor;   memory storing computer program code;   wherein the memory storing the computer program code is configured, with the processor, to cause the apparatus to at least:   identify a mobility management entity pool serving a user equipment associated with a relay node operating in a wireless network;   receive information identifying one or more mobility management entity pools supported by a handover target;   compare the one or more mobility management entity pools supported by the handover target to the mobility management entity pool serving the user equipment;   if the handover target supports the mobility management entity pool serving the user equipment, initiate an X2 handover to handover the user equipment to the target; and   if the handover target does not support the mobility management entity pool serving the user equipment, initiate an S1 handover to handover the user equipment to the target.   
     
     
         10 . The apparatus of  claim 9 , wherein the information identifying the one or more mobility management entity pools supported by the handover target is received from a donor base station in a configuration update. 
     
     
         11 . The apparatus of  claim 9 , wherein the information identifying the one or more mobility management entity pools supported by the handover target is sent by a donor base station in response to a change in the one or more mobility management entity pools supported by a neighbor node. 
     
     
         12 . The apparatus of  claim 9 , wherein the relay node sends information to the donor base station specifying mobility management entity pools supported by neighbors of the relay node, and wherein the information is sent to the donor base station during either an X2 or an X2 setup response procedure. 
     
     
         13 . The apparatus of  claim 9 , wherein the relay node receives from the donor base station information identifying all mobility management entity pools meeting the condition that the mobility management entity pool is supported by all neighbors of the relay node. 
     
     
         14 . An apparatus comprising:
 at least one processor;   memory storing computer program code;   wherein the memory storing the computer program code is configured, with the processor, to cause the apparatus to at least:   select a single mobility management entity pool for all user equipments connected to a specified relay node associated with a donor base station; and   communicate the identity of the selected mobility management entity pool to the specified relay node.   
     
     
         15 . The apparatus of  claim 14 , wherein communicating the identity of the selected mobility management entity pool to the specified relay node is performed using one or more of X2 setup and update procedures. 
     
     
         16 . A non-transitory computer-readable medium storing a program of instructions, execution of which by a processor configures an apparatus to at least:
 select a single mobility management entity pool for all user equipments connected to a specified relay node associated with a donor base station; and   communicate the identity of the selected mobility management entity pool to the specified relay node.   
     
     
         17 . The computer-readable medium of  claim 16 , wherein communicating the identity of the selected mobility management entity pool to the specified relay node is performed using one or more of X2 setup and update procedures.