Method and apparatus for inter-system handover

Abstract

An inter-system handover system for a wireless communication system supports hand-down and hand-up of user equipment (UE) to different radio access technologies, including synchronous and asynchronous systems. Latency and handover connection failures are reduced by an access node (nodeB) broadcasting information about neighboring systems (targets) when the UE reception (RX) capability is both inside or outside the reception range of the target. A single RX chain is sufficient, although transitioning between a wireless wide area network (WWAN) to a wireless local area network may (WLAN) may advantageously benefit from simultaneous operation on two Rx chains. Optimized list of neighboring RAT systems (targets) are broadcast from the network, including measurement parameters and reporting instructions. Thereby, UE-driven reporting minimizes latencies. UE reports other-system searches to network only if needed for a handover. In addition, handover requests can be bundled with other-system measurement information, if necessary, for additional efficiencies.

1 . A method for inter-system handovers in a wireless communication system, comprising:
 transmitting a neighbor list from a source node containing at least one parameter for connecting to a target node proximal to a source node;   transmitting a criterion for a user equipment (UE) to determine when to pursue a handover to the target node; and   handing over the UE to the target node.   
     
     
         2 . The method of  claim 1 , further comprising:
 transmitting the neighbor list and criterion to the UE in idle mode; and   removing paging scheduled to the UE subsequent to a location update acceptance by the target node.   
     
     
         3 . The method of  claim 1 , further comprising transmitting the neighbor list that identifies a subset of neighboring nodes for the UE to search. 
     
     
         4 . The method of  claim 1 , further comprising performing a handover from a dual reception (Rx) chain UE utilizing a single Rx chain. 
     
     
         5 . The method of  claim 1 , wherein transmitting the criterion for the UE to determine when to pursue the handover to the target node further comprises transmitting information prompting the UE to search for the target node. 
     
     
         6 . The method of  claim 5 , further comprising transmitting information comprising at least one target node in the neighbor list to prompt a search. 
     
     
         7 . The method of  claim 6 , further comprising transmitting information that prompts the UE to search in response to a determination that measured signal strength from the source node has trended below a predetermined threshold. 
     
     
         8 . The method of  claim 1 , further comprising transmitting the criterion for requesting the handover by specifying measured power parameter for the target system trending more than a predetermined difference above a measured power parameter for the source node. 
     
     
         9 . The method of  claim 8 , further comprising specifying a requirement that the measured power parameter for the source node is determined to be below a specified threshold as prerequisite for the UE to report satisfaction of the criterion for handover. 
     
     
         10 . The method of  claim 1 , further comprising performing a load based handover determination as a requirement for directing a handover request determination. 
     
     
         11 . The method of  claim 1 , further comprising performing generating a flow composition based discontinuous reception (DRX) pattern. 
     
     
         12 . The method of  claim 1 , further comprising transmitting the neighbor list containing information that facilitates the handover comprising a type identifier for a radio access technology, a center frequency, and a system bandwidth. 
     
     
         13 . The method of  claim 1 , further comprising transmitting the neighbor list containing information comprising a reference time difference between the source node and the target node. 
     
     
         14 . The method of  claim 1 , further comprising transmitting the neighbor list containing information comprising information specific for a type of radio access technology. 
     
     
         15 . At least one processor for inter-system handovers in a wireless communication system, comprising:
 a first module for transmitting a neighbor list from a source node containing at least one parameter for connecting to a target node proximal to a source node;   a second module for transmitting a criterion for a user equipment (UE) to determine when to pursue a handover to the target node; and   a third module for handing over the UE to the target node.   
     
     
         16 . A computer program product for inter-system handovers in a wireless communication system, comprising:
 a computer-readable medium, comprising:
 a first set of codes for causing a computer to transmit a neighbor list from a source node containing at least one parameter for connecting to a target node proximal to a source node; 
 a second set of codes for causing the computer to transmit a criterion for a user equipment (UE) to determine when to pursue a handover to the target node; and 
 a third set of codes for causing the computer to hand over the UE to the target node. 
   
     
     
         17 . An apparatus for inter-system handovers in a wireless communication system, comprising:
 means for transmitting a neighbor list from a source node containing at least one parameter for connecting to a target node proximal to a source node;   means for transmitting a criterion for a user equipment (UE) to determine when to pursue a handover to the target node; and   means for handing over the UE to the target node.   
     
     
         18 . An apparatus for inter-system handovers in a wireless communication system, comprising:
 a computer-readable medium containing a data structure comprising a neighbor list from a source node containing at least one parameter for connecting to a target node proximal to a source node and containing a criterion for a user equipment (UE) to determine when to pursue a handover to the target node;   a transmitter for transmitting the neighbor list and criterion; and   a communication channel to the target node for facilitating handover of the UE to the target node.   
     
     
         19 . The apparatus of  claim 18 , further comprising the transmitter transmitting the neighbor list and criterion to the UE in idle mode, and the communication channel facilitating handover by removing paging scheduled to the UE subsequent to a location update acceptance by the target node. 
     
     
         20 . The apparatus of  claim 18 , further comprising the data structure identifying a subset of neighboring nodes for the UE to search. 
     
     
         21 . The apparatus of  claim 18 , further comprising the transmitter facilitating a handover from a dual reception (Rx) chain UE utilizing a single Rx chain. 
     
     
         22 . The apparatus of  claim 18 , wherein the criterion for the UE to determine when to pursue the handover to the target node further comprises information prompting the UE to search for the target node. 
     
     
         23 . The apparatus of  claim 22 , wherein the information prompting the search comprises at least one target node in the neighbor list to prompt a search. 
     
     
         24 . The apparatus of  claim 23 , wherein the information that prompts the UE to search comprises a requirement that measured signal strength from the source node has trended below a predetermined threshold. 
     
     
         25 . The apparatus of  claim 18 , wherein the criterion for requesting the handover specifies a measured power parameter for the target system trending more than a predetermined difference above a measured power parameter for the source node. 
     
     
         26 . The apparatus of  claim 25 , further comprising the transmitter transmitting a requirement that the measured power parameter from the source node falls is determined to be below a specified threshold as prerequisite for the UE to report satisfaction of the criterion for handover. 
     
     
         27 . The apparatus of  claim 18 , further comprising a processor performing a load based handover determination as a requirement for directing a handover request determination to be transmitted. 
     
     
         28 . The apparatus of  claim 18 , further comprising a processor generating preparing a flow composition based discontinuous reception (DRX) pattern. 
     
     
         29 . The apparatus of  claim 18 , wherein the neighbor list contains information that facilitates the handover comprising a type identifier for a radio access technology, a center frequency, and a system bandwidth. 
     
     
         30 . The apparatus of  claim 18 , wherein the neighbor list contains information comprising a reference time difference between the source node and the target node. 
     
     
         31 . The apparatus of  claim 18 , wherein the neighbor list contains information comprising information specific for a type of radio access technology. 
     
     
         32 . A method for inter-system handovers in a wireless communication system, comprising:
 receiving a neighbor list from a source node containing at least one parameter for connecting to a target node proximal to a source node;   receiving a criterion for a user equipment (UE) to determine when to pursue a handover to the target node; and   requesting handing over to the target node.   
     
     
         33 . The method of  claim 32 , further comprising:
 receiving the neighbor list and criterion while in idle mode; and   requesting a location update request from the target node prompting a location update acceptance by the target node.   
     
     
         34 . The method of  claim 32 , further comprising receiving the neighbor list that identifies a subset of neighboring nodes to search. 
     
     
         35 . The method of  claim 32 , further comprising searching for the target node for a handover utilizing a single Rx chain of a dual reception (Rx) chain. 
     
     
         36 . The method of  claim 32 , wherein receiving the criterion to determine when to pursue a handover to the target node further comprises receiving information prompting the UE to search for the target node. 
     
     
         37 . The method of  claim 36 , further comprising receiving information comprising at least one target node in the neighbor list to prompt a search. 
     
     
         38 . The method of  claim 37 , further comprising receiving information that prompts the UE to search by making a determination that measured signal strength from the source node has trended below a predetermined threshold. 
     
     
         39 . The method of  claim 32 , further comprising receiving the criterion for requesting a handover that specifies measured power parameter for the target system trending more than a predetermined difference above a measured power parameter for the source node. 
     
     
         40 . The method of  claim 39 , further comprising reporting satisfaction of the criterion for handover in response to a power parameter measured for the source node falls that is determined to be below a specified threshold. 
     
     
         41 . The method of  claim 32 , further comprising making a handover request determination in response to a load based handover determination by the source node. 
     
     
         42 . The method of  claim 32 , further comprising requesting generation a flow composition based discontinuous reception (DRX) pattern. 
     
     
         43 . The method of  claim 32 , further comprising receiving the neighbor list containing information that facilitates a handover comprising a type identifier for a radio access technology, a center frequency, and a system bandwidth. 
     
     
         44 . The method of  claim 32 , further comprising receiving the neighbor list containing information comprising a reference time difference between the source node and the target node. 
     
     
         45 . The method of  claim 32 , further comprising receiving the neighbor list containing information comprising information specific for a type of radio access technology. 
     
     
         46 . At least one processor for inter-system handovers in a wireless communication system, comprising:
 a first module for receiving a neighbor list from a source node containing at least one parameter for connecting to a target node proximal to a source node;   a second module for receiving a criterion for a user equipment (UE) to determine when to pursue a handover to the target node; and   a third module for requesting handing over to the target node.   
     
     
         47 . A computer program product for inter-system handovers in a wireless communication system, comprising:
 a computer-readable medium, comprising:
 a first set of codes for causing a computer to receive a neighbor list from a source node containing at least one parameter for connecting to a target node proximal to a source node; 
 a second set of codes for causing the computer to receive a criterion for a user equipment (UE) to determine when to pursue a handover to the target node; and 
 a third set of codes for causing the computer to request handing over to the target node. 
   
     
     
         48 . An apparatus for inter-system handovers in a wireless communication system, comprising:
 means for receiving a neighbor list from a source node containing at least one parameter for connecting to a target node proximal to a source node;   means for receiving a criterion for a user equipment (UE) to determine when to pursue a handover to the target node; and   means for requesting handing over to the target node.   
     
     
         49 . An apparatus for inter-system handovers in a wireless communication system, comprising:
 a computer-readable medium for receiving a data structure comprising a neighbor list from a source node containing at least one parameter for connecting to a target node proximal to a source node and containing a criterion for a user equipment (UE) to determine when to pursue a handover to the target node;   a receiver for receiving the neighbor list and criterion; and   a transmitter for requesting handover to the target node.   
     
     
         50 . The apparatus of  claim 49 , further comprising the receiver receiving the neighbor list and criterion while in idle mode, and the transmitter requesting a location update request to the target node that results in a location update acceptance by the target node. 
     
     
         51 . The apparatus of  claim 49 , further comprising the data structure identifying a subset of neighboring nodes for the UE to search. 
     
     
         52 . The apparatus of  claim 49 , further comprising the receiver and transmitter facilitating a handover by utilizing a single Rx chain of a dual Rx chain. 
     
     
         53 . The apparatus of  claim 49 , wherein the criterion for the UE to determine when to pursue the handover to the target node further comprises information prompting the UE to search for the target node. 
     
     
         54 . The apparatus of  claim 53 , wherein the information prompting the search comprises at least one target node in the neighbor list to prompt a search. 
     
     
         55 . The apparatus of  claim 54 , wherein the information that prompts the UE to search comprises a requirement that measured signal strength from the source node has trended below a predetermined threshold. 
     
     
         56 . The apparatus of  claim 49 , wherein the criterion for requesting the handover specifies a measured power parameter for the target system trending more than a predetermined difference above a measured power parameter for the source node. 
     
     
         57 . The apparatus of  claim 56 , further comprising the receiver measuring a power parameter from the source node falls that is determined to be below a specified threshold as prerequisite for the UE to report satisfaction of the criterion for the handover. 
     
     
         58 . The apparatus of  claim 49 , further comprising a processor performing the handover request determination in response to receiving load based handover determination. 
     
     
         59 . The apparatus of  claim 49 , further comprising a processor requesting generation of a flow composition based discontinuous reception (DRX) pattern. 
     
     
         60 . The apparatus of  claim 49 , wherein the neighbor list contains information that facilitates the handover comprising a type identifier for a radio access technology, a center frequency, and a system bandwidth. 
     
     
         61 . The apparatus of  claim 49 , wherein the neighbor list contains information comprising a reference time difference between the source node and the target node. 
     
     
         62 . The apparatus of  claim 49 , wherein the neighbor list contains information comprising information specific for a type of radio access technology.