Method and apparatus of physical cell identifier allocation

Abstract

A method and apparatus of allocating a Physical Cell Identifier (PCI) is disclosed in an embodiment of the present invention allowing different cells to operate on different frequencies while eliminating or reducing risk of PCI conflicts. Thereby PCI allocation is provided that is effective also in a multi-frequency environment.

1 . A method of physical cell identifier allocation in a wireless cellular communications system, comprising:
 communication of at least one signaling message comprising neighboring cell information of at least one cell neighboring a first cell in addition to information on the first cell, said neighboring cell information comprising a physical cell identifier, and   transfer of the at least one signaling message from a first eNB serving the first cell to a second eNB.   
   
   
       2 . The method according to  claim 1 , comprising
 communication of operating frequency information of the at least one cell which is neighboring said first cell.   
   
   
       3 . The method according to  claim 2 , wherein the neighboring cell operating frequency information is frequency channel number. 
   
   
       4 . The method according to  claim 2 , wherein the neighboring cell operating frequency information is uplink frequency information. 
   
   
       5 . The method according to  claim 2 , wherein the neighboring cell operating frequency information is downlink frequency information. 
   
   
       6 . The method according to  claim 1 , wherein the neighboring cell information comprises neighboring cell physical cell identifier irrespective of neighboring cell operating frequency. 
   
   
       7 . The method according to  claim 1 , wherein the first eNB serves cells of disjoint frequencies. 
   
   
       8 . The method according to  claim 1 , wherein the eNB serves cells operating on disjoint frequencies. 
   
   
       9 . The method according to  claim 8 , wherein the cells operating on disjoint frequencies are of different size in terms of geographical coverage. 
   
   
       10 . The method according to  claim 1 , wherein the first eNB serves at least one cell operating on a frequency disjoint from a frequency on which a cell served by the second eNB is operating. 
   
   
       11 . The method according to  claim 1 , wherein the signaling message is an X2 Setup message. 
   
   
       12 . The method according to  claim 11 , wherein the signaling message is an X2 Setup Request message. 
   
   
       13 . The method according to  claim 11 , wherein the signaling message is an X2 Setup Response message. 
   
   
       14 . The method according to  claim 11 , wherein the signaling message is an eNB Configuration Update message. 
   
   
       15 . The method according to  claim 1 , comprising
 detecting on basis of said neighboring cell information, a, at least potentially, conflicting physical cell identifier allocation in said first cell.   
   
   
       16 . A method of physical cell identifier allocation in a wireless cellular communications system, comprising:
 communication of at least one signaling message comprising neighboring cell information of at least one cell neighboring a first cell, said neighboring cell information comprising a physical cell identifier irrespective of operating frequency of the at least one cell, which is neighboring said first cell, and its at least one neighboring cell; and   determination of neighboring cell operating frequency on the basis of said neighboring cell information in response to the communicated information.   
   
   
       17 . A method of physical cell identifier allocation, comprising:
 obtaining neighboring cell information from at least one cell neighboring a first cell, said neighboring cell information comprising physical cell identifier information of at least one cell, which is neighboring said at least one cell neighboring the first cell, wherein the neighboring cell information comprises operation frequency information corresponding to the physical cell identifier information.   
   
   
       18 . The method according to  claim 17 , wherein at least one of said cells neighboring said first cell comprises is a cell operating on a frequency different from a frequency of said first cell; and
 allocating, according to said neighboring cell information, a physical cell identifier to said first cell.   
   
   
       19 . The method according to  claim 17 , wherein said neighboring cell information comprises neighboring cell information of at least one indirect neighboring cell of said first cell, said direct neighboring cell of said first cell being a cell adjacent to or overlapping with said first cell, and said indirect neighboring cell of said first cell being a cell adjacent to or overlapping with said direct neighboring cell. 
   
   
       20 . The method according to  claim 19 , wherein obtaining neighboring cell information of at least one cell neighboring said first cell comprises:
 obtaining a first neighboring cell information of said first cell, said first neighboring cell information comprising physical cell identifier information of one or more direct neighboring cells of said first cell;   obtaining a second neighboring cell information of said at least one direct neighboring cell according to said first neighboring cell information of said first cell, said second neighboring cell information comprising physical cell identifier information of at least one indirect neighboring cell of said first cell;   wherein said neighboring cell information of at least one cell neighboring said first cell comprises said first neighboring cell information and said second neighboring cell information.   
   
   
       21 . The method according to  claim 20 , wherein obtaining a second neighboring cell information of said at least one direct neighboring cell comprises:
 obtaining neighboring cell information from each one of said at least one direct neighboring cell, said second neighboring cell information comprising a neighboring cell information from each one of said at least one direct neighboring cell, wherein said neighboring cell information of each one of said at least one direct neighboring cell comprises at least one of:
 physical cell identifier information of one or more cells which are indirect neighboring cells of said first cell and which operate on said frequency of said first cell; 
 physical cell identifier information and cell global ID information of one or more cells which are indirect neighboring cells of said first cell; and 
 physical cell identifier information, cell global ID information and frequency information of one or more cells which are indirect neighboring cells of said first cell. 
   
   
   
       22 . The method according to  claim 21 , comprising:
 obtaining according to cell global ID information of said at least one cell, which is indirect neighboring cell of said first cell, frequency information of said one or more cells, wherein said neighboring cell information of cells neighboring to said first cell comprises said frequency information of said at lest one cell.   
   
   
       23 . The method of  claim 20 , wherein said at least one direct neighboring cell of said first cell is a cell operating on said frequency of said first cell and said second neighboring cell information further comprises cell global ID information of said at least one indirect neighboring cell of said first cell. 
   
   
       24 . The method of  claim 23 , wherein conditionally upon said neighboring cell information of each one of said one or more cells operating on a frequency different from said frequency of said first cell comprises:
 obtaining, according to cell global ID information of direct neighboring cells of each one of said at least one cell operating on a frequency different from said frequency of said first cell, frequency information of direct neighboring cells of each one of said at least one cell operating on a frequency different from said frequency of said first cell, wherein said neighboring cell information of cells neighboring said first cell further comprises said frequency information of direct neighboring cells of each one of said at least one cell operating on a frequency different from said frequency of said first cell.   
   
   
       25 . The method of  claim 21 , comprising:
 obtaining, from at least one eNB of a direct neighboring cell of said first cell or from an operation administration maintenance system, said frequency information of said one or more cells or said frequency information of said direct neighboring cells of each one of said one or more cells working under a frequency different to said frequency of said first cell.   
   
   
       26 . An apparatus of physical cell identifier allocation, said apparatus comprising:
 an information obtaining module configured to obtain neighboring cell information of at least one cell neighboring a cell served by the apparatus, said neighboring cell information comprising physical cell identifier information of at least one cell which is neighboring said at least one cell neighboring said cell served by the apparatus.   
   
   
       27 . The apparatus according to  claim 26  wherein the information obtaining module is configured to retrieve neighboring cell information comprising operation frequency information corresponding to a physical cell identifier of the neighboring cell information. 
   
   
       28 . An apparatus of physical cell identifier allocation, said apparatus comprising:
 processing circuitry arranged to compile a signaling message comprising neighboring cell information, wherein the neighboring cell information comprises an element of physical cell identifier of at least one cell neighboring a first cell served by the apparatus; and   a transmitter arranged to transmit the signaling message as controlled by the processing circuitry.   
   
   
       29 . The apparatus according to  claim 28 , wherein the transmitter is controlled to transmit the signaling message conditionally upon request from an apparatus serving a second cell. 
   
   
       30 . The apparatus according to  claim 28 , wherein the processing circuitry is adapted to compile the signaling message comprising neighboring cell information, wherein the neighboring cell information comprises an element of operating frequency corresponding to the physical cell identifier. 
   
   
       31 . A wireless cellular communication system comprising an apparatus in  claim 26  and an apparatus in  28 , wherein the apparatuses are interconnected for exchange of a signaling message comprising physical cell identifier and operating frequency elements. 
   
   
       32 . The system according to  claim 31 , wherein the interconnection is an interconnection over an X2 interface.