Neighbor Selection For Handover in a Radio Access Network

• US 20140228031A1
• Filed: 09/26/2012
• Published: 08/14/2014
• Est. Priority Date: 09/30/2011
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Masini, Gino Luca, Centonza, Angelo
• Granted Patent: US 9,294,963 B2
• Time in Patent Office: Days
• US Class Current: 455/436
• CPC Class Codes: H04W 36/0005 Control or signalling for completing the hand-off
• CPC Class Codes: H04W 36/00835 Determination of neighbour cell lists
• CPC Class Codes: H04W 84/045 using private Base Stations, e.g. femto Base Stations, home Node B
• CPC Class Codes: H04W 92/20 between access points

Abstract

The following methods are disclosed: A method of initiating handover of a User Equipment, UE, in a cellular network comprising a plurality of enhanced Node Bs, eNBs, the method comprising: receiving at a source eNB, from the UE, a handover measurement report containing a Physical Cell Identifier, PCI, of a cell of a neighboring eNB; at the source eNB, performing a lookup of a Neighbor Relation Relation Table to identify a global cell identity and access mode associated with the PCI; and using the identified global cell identity and the access mode to determine an eNB identity for said neighboring eNB. A method of initiating handover of a User Equipment, UE, in a cellular net-work comprising a plurality of enhanced Node Bs, eNBs, the method comprising: receiving at a source eNB, from the UE, a handover measurement report containing a Physical Cell Identifier, PCI, of a cell of a neighboring eNB; at the source eNB, performing a lookup of a Neighbor Relation Table to identify a plurality of global cell identities associated with the PCI, the neighbor relation table also containing, for each such global cell identity, PCIs of neighboring cells; selecting the correct global cell identity from said plurality of global cell identities by comparing the PCIs of further neighboring eNBs cells reported by the UE with the neighboring PCIs of each of said plurality of global cell identities; and deriving from the selected correct global cell identity, an eNB identity of said neighboring eNB. A method of initiating handover of a subscriber from a cell of a source enhanced Node B, eNB, to a cell of a target enhanced Node B, eNB, via the X2 interface, the method comprising, at the source eNB, maintaining a Neighbor Relation Table (NRT) identifying the connectivity of the source eNB to cells of its neighboring eNBs, this information including for each eNB cell an indication that the eNB cell is an open, closed or hybrid eNB cell and, for each closed and hybrid eNB cell, a Closed Subscriber Group, CSG, identity; determining that a handover of the UE is required and using

Claims

1. A method of initiating handover of a User Equipment (UE) via an X2 interface in a cellular network comprising a plurality of enhanced Node Bs (eNBs), the method comprising:

receiving at a source eNB, from the UE, a handover measurement report containing a Physical Cell Identifier (PCI) of a cell of a neighboring eNB;

at the source eNB, performing a lookup of a Neighbor Relation Relation Table to identify a global cell identity and access mode associated with the PCI; and

using the identified global cell identity and the access mode to determine an eNB identity for said neighboring eNB.

2. The method according to claim 1, wherein, if said access mode identifies the neighboring eNB as a Home eNB, said eNB identity is constructed using the entire, 28 bit global cell identity, and if the access mode identifies the neighboring eNB as a macro eNB, said eNB identity is constructed using the first 20 bits of the 28 bit global cell identity.

6. The method according to claim 1, further comprising maintaining within said Neighbor Relation Table, for each neighboring cell, PCIs of one or more cells neighboring that neighboring cell.

7. The method according to claim 2, further comprising maintaining within said Neighbor Relation Table, for each neighboring cell, PCIs of one or more cells neighboring that neighboring cell.

3. A method of initiating handover of a User Equipment (UE) in a cellular network comprising a plurality of enhanced Node Bs (eNBs), the method comprising:

receiving at a source eNB, from the UE, a handover measurement report containing a Physical Cell Identifier (PCI) of a cell of a neighboring eNB;

at the source eNB, performing a lookup of a Neighbor Relation Table to identify a plurality of global cell identities associated with the PCI, the neighbor relation table also containing, for each such global cell identity, PCIs of neighboring cells; and

selecting the correct global cell identity from said plurality of global cell identities by comparing the PCIs of further neighboring eNBs cells reported by the UE with the neighboring PCIs of each of said plurality of global cell identities; and

deriving from the selected correct global cell identity, an eNB identity of said neighboring eNB.

4. A method of initiating handover of a User Equipment (UE), from a cell of a source enhanced Node B (eNB) to a cell of a target eNB via the X2 interface, the method comprising:

at the source eNB, maintaining a Neighbor Relation Table (NRT) identifying the connectivity of the source eNB to cells of its neighboring eNBs, this information including for each eNB cell an indication that the eNB cell is an open, closed or hybrid eNB cell and, for each closed and hybrid eNB cell, a Closed Subscriber Group, CSG, identity;

determining that a handover of the UE is required and using the information stored in the NRT to identify closed and hybrid eNBs cells to which the subscriber has access;

selecting a target eNB cell from the available open eNBs cells and the identified closed and hybrid eNBs cells; and

performing handover of the subscriber from the source to the target eNB cell including establishing an X2 interface between the source and the target eNBs where no such interface exists a priori.

5. The method according to claim 4, wherein said step of determining that a handover of the UE is required comprises receiving at the source eNB, from said UE, reports of neighboring eNB cells including, where available, the CSG identity and access mode of a neighboring eNB cell.

8. The method according to claim 4, further comprising maintaining within said Neighbor Relation Table, for each neighboring cell, PCIs of one or more cells neighboring that neighboring cell.

9. The method according to claim 5, further comprising maintaining within said Neighbor Relation Table, for each neighboring cell, PCIs of one or more cells neighboring that neighboring cell.