Secondary synchronization sequences for cell group detection in a cellular communications system

Abstract

Timing parameters and an identity of a particular one of a number of cell groups are indicated in a signal transmitted in a cellular communication system having a radio frame in a physical layer, the radio frame comprising a number of time slots. In a known one of the time slots, a synchronization signal, S 1 , is transmitted that comprises a pair of sequences, {tilde over (S)} i ,{tilde over (S)} j ({tilde over (S)} i ≠{tilde over (S)} j ) arranged in a first ordering. In another known one of the time slots, a synchronization signal, S 2 , is transmitted that comprises the pair of sequences, {tilde over (S)} i ,{tilde over (S)} j arranged in a second ordering. The selected pair of sequences is uniquely identified with the particular cell group, and the first ordering of the sequences is used only for transmission in the known one of the time slots, and the second ordering of the sequences is used only for transmission in said another known one of the time slots.

What is claimed is: 
     
         1 . A method of indicating timing parameters and an identity of a particular cell group from a number, M, of possible cell groups in a signal transmitted in a cellular communication system that employs a radio frame in a physical layer, the radio frame comprising a number of time slots, the method comprising:
 transmitting, in a known one of the time slots of the radio frame, a synchronization signal, S 1 , that comprises a pair of sequences, {tilde over (S)} i ,{tilde over (S)} j  arranged in a first ordering; and   transmitting, in another known one of the time slots of the radio frame, a synchronization signal, S 2 , that comprises the pair of sequences, {tilde over (S)} i ,{tilde over (S)} j  arranged in a second ordering,   wherein:   each member of the pair of sequences, {tilde over (S)} i ,{tilde over (S)} j , is selected from a group comprising N seq  different sequences, wherein N seq  is at least ceil   
       
         
           
             
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          different sequences; 
         the selected pair of sequences is uniquely identified with the particular cell group, wherein i, jε[1, . . . , N Seq ] and {tilde over (S)} i ≠{tilde over (S)} j ; and 
         the first ordering of the sequences is used only for transmission in the known one of the time slots of the radio frame, and the second ordering of the sequences is used only for transmission in said another known one of the time slots. 
       
     
     
         2 . The method of  claim 1 , wherein:
 the first ordering of the pair of sequences, {tilde over (S)} i ,{tilde over (S)} j  is effected by transmitting the sequence {tilde over (S)} i  before transmitting the sequence {tilde over (S)} j ; and   the second ordering of the pair of sequences, {tilde over (S)} i ,{tilde over (S)} j  is effected by transmitting the sequence {tilde over (S)} j  before transmitting the sequence {tilde over (S)} i .   
     
     
         3 . The method of  claim 2 , wherein S 1  and S 2  are each of length n, and each of the sequences {tilde over (S)} i ,{tilde over (S)} j  is of length n/2. 
     
     
         4 . The method of  claim 1 , wherein:
 the physical layer of the cellular communication system employs Orthogonal Frequency Division Multiplexing;   the first ordering of the pair of sequences, {tilde over (S)} i ,{tilde over (S)} j  is effected by transmitting the sequence {tilde over (S)} i  on a first set of one or more sub-carriers, and transmitting the sequence {tilde over (S)} j  on a second set of one or more sub-carriers; and   the second ordering of the pair of sequences, {tilde over (S)} i ,{tilde over (S)} j  is effected by transmitting the sequence {tilde over (S)} j  on the first set of one or more sub-carriers, and transmitting the sequence {tilde over (S)} i  on the second set of one or more sub-carriers.   
     
     
         5 . The method of  claim 1 , wherein:
 in the physical layer of the cellular communication system, symbols of the synchronization signal, S 1 , are separated in a frequency domain;   the first ordering of the pair of sequences, {tilde over (S)} i ,{tilde over (S)} j  is effected by transmitting the sequence {tilde over (S)} i  on a first set of frequencies, and transmitting the sequence {tilde over (S)} j  on a second set of frequencies; and   the second ordering of the pair of sequences, {tilde over (S)} i ,{tilde over (S)} j  is effected by transmitting the sequence {tilde over (S)} j  on the first set of frequencies, and transmitting the sequence {tilde over (S)} i  on the second set of frequencies.   
     
     
         6 . The method of  claim 1 , comprising:
 generating the synchronization signals S 1  and S 2  in accordance with:
     S   1   =α{tilde over (S)}   i   +β{tilde over (S)}   j ; and 
     S   2   =β{tilde over (S)}   i   +α{tilde over (S)}   j , 
   wherein:   α is a first multiplicand;   β is a second multiplicand, α≠β.   
     
     
         7 . The method of  claim 6 , wherein each of the multiplicands, α and β, is a scalar value and corresponds to an amount of signal amplitude. 
     
     
         8 . The method of  claim 6 , wherein each of the multiplicands, α and β, is a scalar value and corresponds to an amount of signal power. 
     
     
         9 . The method of  claim 6 , wherein the synchronization signals S 1  and S 2  and the sequences {tilde over (S)} i  and {tilde over (S)} j  are all of equal length. 
     
     
         10 . The method of  claim 6 , wherein:
 transmitting the synchronization signal S 1  comprises transmitting α{tilde over (S)} i  and β{tilde over (S)} j  simultaneously; and   transmitting the synchronization signal S 2  comprises transmitting β{tilde over (S)} i  and α{tilde over (S)} j  simultaneously.   
     
     
         11 . The method of  claim 1 , wherein the use of the first ordering of the sequences only for transmission in the known one of the time slots of the radio frame, and the use of the second ordering of the sequences only for transmission in said another known one of the time slots enables detection of radio frame timing using just one of the synchronization signals, S 1  and S 2 . 
     
     
         12 . A method of detecting timing parameters and an identity of a particular cell group from a number, M, of possible cell groups in a signal received in a cellular communication system that employs a radio frame in a physical layer, the radio frame comprising a number of time slots including two time slots associated with a synchronization channel, the method comprising:
 receiving, in one of the time slots associated with the synchronization channel, one of first and second synchronization signals, S 1  and S 2 , wherein the first synchronization signal S 1  comprises a pair of sequences, {tilde over (S)} i ,{tilde over (S)} j  arranged in a first ordering and the second synchronization signal S 2  comprises the pair of sequences, {tilde over (S)} i ,{tilde over (S)} j  arranged in a second ordering;   determining which of a number of predefined sequences best matches the received sequence {tilde over (S)} i , which of the number of predefined sequences best matches the received sequence {tilde over (S)} j , and whether the pair of received sequences {tilde over (S)} i ,{tilde over (S)} j  were arranged in the first ordering or the second ordering, wherein the number of predefined sequences is selected from a group comprising N seq  different sequences, wherein N seq  is at least ceil   
       
         
           
             
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          different sequences; 
         identifying the particular cell group by performing a cell group identification process that includes determining with which cell group the pair of received sequences, {tilde over (S)} i ,{tilde over (S)} j , is uniquely associated; and 
         determining in which one of the two time slots associated with the synchronization channel the one of first and second synchronization signals was received by using information that indicates whether the sequences {tilde over (S)} i ,{tilde over (S)} j  were received in the first ordering or the second ordering. 
       
     
     
         13 . The method of  claim 12 , wherein:
 the first ordering of the pair of sequences, {tilde over (S)} i ,{tilde over (S)} j  causes the sequence {tilde over (S)} i  to be received before receiving the sequence {tilde over (S)} j ; and   the second ordering of the pair of sequences, {tilde over (S)} i ,{tilde over (S)} j  causes the sequence {tilde over (S)} j  to be received before receiving the sequence {tilde over (S)} i .   
     
     
         14 . The method of  claim 13 , wherein S 1  and S 2  are each of length n, and each of sequences {tilde over (S)} i ,{tilde over (S)} j  is of length n/2. 
     
     
         15 . The method of  claim 12 , wherein:
 the physical layer of the cellular communication system employs Orthogonal Frequency Division Multiplexing;   the first ordering of the pair of sequences, {tilde over (S)} i ,{tilde over (S)} j  causes the sequence {tilde over (S)} i  to be received on a first set of one or more sub-carriers, and the sequence {tilde over (S)} j  to be received on a second set of one or more sub-carriers; and   the second ordering of the pair of sequences, {tilde over (S)} i ,{tilde over (S)} j  causes the sequence {tilde over (S)} j  to be received on the first set of one or more sub-carriers, and the sequence {tilde over (S)} i  to be received on the second set of one or more sub-carriers.   
     
     
         16 . The method of  claim 15 , wherein the first and second synchronization signals, S 1  and S 2 , and the sequences {tilde over (S)} i  and {tilde over (S)} j  are all of equal length. 
     
     
         17 . The method of  claim 12 , wherein:
 in the physical layer of the cellular communication system, symbols of the synchronization signal, S 1 , are separated in a frequency domain;   the first ordering of the pair of sequences, {tilde over (S)} i ,{tilde over (S)} j  causes the sequence {tilde over (S)} i  to be received on a first set of frequencies, and the sequence {tilde over (S)} j  to be received on a second set of frequencies; and   the second ordering of the pair of sequences, {tilde over (S)} i ,{tilde over (S)} j  causes the sequence {tilde over (S)} j  to be received on the first set of frequencies, and the sequence {tilde over (S)} i  to be received on the second set of frequencies.   
     
     
         18 . The method of  claim 12 , wherein determining whether the pair of received sequences {tilde over (S)} i ,{tilde over (S)} j  were arranged in the first ordering or the second ordering comprises:
 determining whether the received one of the first and second synchronization signals represents:
     S   1   =α{tilde over (S)}   i   +β{tilde over (S)}   j ; or 
     S   2   =β{tilde over (S)}   i   +α{tilde over (S)}   j , 
   wherein:   α is a first multiplicand;   β is a second multiplicand, α≠β.   
     
     
         19 . The method of  claim 18 , wherein each of the multiplicands, α and β, is a scalar value and corresponds to an amount of signal amplitude. 
     
     
         20 . The method of  claim 18 , wherein each of the multiplicands, α and β, is a scalar value and corresponds to an amount of signal power. 
     
     
         21 . The method of  claim 18 , wherein the first and second synchronization signals, S 1  and S 2 , and the sequences {tilde over (S)} i  and {tilde over (S)} j  are all of equal length. 
     
     
         22 . The method of  claim 12 , wherein receiving, in one of the time slots associated with the synchronization channel, one of the first and second synchronization signals S 1  and S 2  comprises:
 receiving the pair of sequences {tilde over (S)} i ,{tilde over (S)} j  simultaneously.   
     
     
         23 . The method of  claim 12 , comprising:
 detecting radio frame timing by using information that indicates in which one of the two time slots associated with the synchronization channel the one of the first and second synchronization signals was received.   
     
     
         24 . The method of  claim 12 , wherein identifying the particular cell group by determining with which cell group the pair of received sequences, {tilde over (S)} i ,{tilde over (S)} j , is uniquely associated comprises using the pair of received sequences {tilde over (S)} i ,{tilde over (S)} j  to locate an entry in a look-up table. 
     
     
         25 . The method of  claim 12 , wherein identifying the particular cell group by determining with which cell group the pair of received sequences, {tilde over (S)} i ,{tilde over (S)} j , is uniquely associated is performed by calculation circuitry. 
     
     
         26 . The method of  claim 12 , wherein using information about whether the sequences {tilde over (S)} i ,{tilde over (S)} j  were arranged in the first ordering or the second ordering to determine in which one of the two time slots associated with the synchronization channel the received one of the first and second synchronization signals was received comprises using the pair of received sequences {tilde over (S)} i ,{tilde over (S)} j  to locate an entry in a look-up table. 
     
     
         27 . The method of  claim 12 , wherein using information about whether the sequences {tilde over (S)} i ,{tilde over (S)} j  were arranged in the first ordering or the second ordering to determine in which one of the two time slots associated with the synchronization channel the received one of the first and second synchronization signals was received is performed by calculation circuitry. 
     
     
         28 . The method of  claim 12 , comprising:
 receiving, in an other one of the time slots associated with the synchronization channel, an other one of the first and second synchronization signals;   determining whether a type of cell search procedure to be performed is an inter-frequency cell search procedure;   determining whether the type of cell search procedure to be performed is an inter-radio access technology cell search procedure;   determining whether the type of cell search procedure to be performed is an intra-cell search procedure;   if the type of cell search procedure to be performed is none of the inter-frequency cell search procedure, the inter-radio access technology cell search procedure, or the intra-cell search procedure, then performing:
 determining which of the number of predefined sequences best matches the received sequence {tilde over (S)} i  of the other one of the first and second synchronization signals, which of the number of predefined sequences best matches the received sequence {tilde over (S)} j  of the other one of the first and second synchronization signals, and whether the pair of received sequences {tilde over (S)} i ,{tilde over (S)} j  of the other one of the first and second synchronization signals were arranged in the first ordering or the second ordering, 
   wherein the cell group identification process further includes determining with which cell group the pair of received sequences, {tilde over (S)} i ,{tilde over (S)} j , of the other one of the first and second synchronization signals is uniquely associated.   
     
     
         29 . An apparatus for indicating timing parameters and an identity of a particular cell group from a number, M, of possible cell groups in a signal transmitted in a cellular communication system that employs a radio frame in a physical layer, the radio frame comprising a number of time slots, the apparatus comprising:
 logic configured to transmit, in a known one of the time slots of the radio frame, a synchronization signal, S 1 , that comprises a pair of sequences, {tilde over (S)} i ,{tilde over (S)} j  arranged in a first ordering; and   logic configured to transmit, in another known one of the time slots of the radio frame, a synchronization signal, S 2 , that comprises the pair of sequences, {tilde over (S)} i ,{tilde over (S)} j  arranged in a second ordering,   wherein:   each member of the pair of sequences, {tilde over (S)} i ,{tilde over (S)} j , is selected from a group comprising N seq  different sequences, wherein N seq  is at least ceil   
       
         
           
             
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          different sequences; 
         the selected pair of sequences is uniquely identified with the particular cell group, wherein i, jε[1, . . . , N Seq ] and {tilde over (S)} i ≠{tilde over (S)} j ; and 
         the apparatus is configured to operate such that the first ordering of the sequences is used only for transmission in the known one of the time slots of the radio frame, and the second ordering of the sequences is used only for transmission in said another known one of the time slots. 
       
     
     
         30 . The apparatus of  claim 29 , wherein:
 the logic configured to transmit, in the known one of the time slots of the radio frame, the synchronization signal, S 1 , that comprises the pair of sequences, {tilde over (S)} i ,{tilde over (S)} j  arranged in the first ordering effects the first ordering of the pair of sequences, {tilde over (S)} i ,{tilde over (S)} j  by transmitting the sequence {tilde over (S)} i  before transmitting the sequence {tilde over (S)} j ; and   the logic configured to transmit, in said another known one of the time slots of the radio frame, the synchronization signal, S 2 , that comprises the pair of sequences, {tilde over (S)} i ,{tilde over (S)} j  arranged in the second ordering effects the second ordering of the pair of sequences, {tilde over (S)} i ,{tilde over (S)} j  by transmitting the sequence {tilde over (S)} j  before transmitting the sequence {tilde over (S)} i .   
     
     
         31 . The apparatus of  claim 30 , wherein S 1  and S 2  are each of length n, and each of the sequences {tilde over (S)} i ,{tilde over (S)} j  is of length n/2. 
     
     
         32 . The apparatus of  claim 29 , wherein:
 the physical layer of the cellular communication system employs Orthogonal Frequency Division Multiplexing;   the logic configured to transmit, in the known one of the time slots of the radio frame, the synchronization signal, S 1 , that comprises the pair of sequences, {tilde over (S)} i ,{tilde over (S)} j  arranged in the first ordering effects the first ordering of the pair of sequences, {tilde over (S)} i ,{tilde over (S)} j  by transmitting the sequence {tilde over (S)} i  on a first set of one or more sub-carriers, and transmitting the sequence {tilde over (S)} j  on a second set of one or more sub-carriers; and   the logic configured to transmit, in said another known one of the time slots of the radio frame, the synchronization signal, S 2 , that comprises the pair of sequences, {tilde over (S)} i ,{tilde over (S)} j  arranged in the second ordering effects the second ordering of the pair of sequences, {tilde over (S)} i ,{tilde over (S)} j  by transmitting the sequence {tilde over (S)} j  on the first set of one or more sub-carriers, and transmitting the sequence {tilde over (S)} i  on the second set of one or more sub-carriers.   
     
     
         33 . The apparatus of  claim 32 , wherein the first and second synchronization signals, S 1  and S 2 , and the sequences {tilde over (S)} i  and {tilde over (S)} j  are all of equal length. 
     
     
         34 . The apparatus of  claim 29 , wherein:
 in the physical layer of the cellular communication system, symbols of the synchronization signal, S 1 , are separated in a frequency domain;   the logic configured to transmit, in the known one of the time slots of the radio frame, the synchronization signal, S 1 , that comprises the pair of sequences, {tilde over (S)} i ,{tilde over (S)} j  arranged in the first ordering effects the first ordering of the pair of sequences, {tilde over (S)} i ,{tilde over (S)} j  by transmitting the sequence {tilde over (S)} i  on a first set of frequencies, and transmitting the sequence {tilde over (S)} j  on a second set of frequencies; and   the logic configured to transmit, in said another known one of the time slots of the radio frame, the synchronization signal, S 2 , that comprises the pair of sequences, {tilde over (S)} i ,{tilde over (S)} j  arranged in the second ordering effects the second ordering of the pair of sequences, {tilde over (S)} i ,{tilde over (S)} j  by transmitting the sequence {tilde over (S)} j  on the first set of frequencies, and transmitting the sequence {tilde over (S)} i  on the second set of frequencies.   
     
     
         35 . The apparatus of  claim 29 , comprising:
 logic configured to generate the synchronization signals S 1  and S 2  in accordance with:
     S   1   =α{tilde over (S)}   i   +β{tilde over (S)}   j ; and 
     S   2   =β{tilde over (S)}   i   +α{tilde over (S)}   j , 
   wherein:   α is a first multiplicand;   β is a second multiplicand, α≠β.   
     
     
         36 . The apparatus of  claim 35 , wherein each of the multiplicands, α and β, is a scalar value and corresponds to an amount of signal amplitude. 
     
     
         37 . The apparatus of  claim 35 , wherein each of the multiplicands, α and β, is a scalar value and corresponds to an amount of signal power. 
     
     
         38 . The apparatus of  claim 35 , wherein the synchronization signals S 1  and S 2  and the sequences {tilde over (S)} i  and {tilde over (S)} j  are all of equal length. 
     
     
         39 . The apparatus of  claim 35 , wherein:
 the logic configured to transmit the synchronization signal S 1  comprises logic configured to transmit α{tilde over (S)} i  and β{tilde over (S)} j  simultaneously; and   the logic configured to transmit the synchronization signal S 2  comprises transmitting β{tilde over (S)} i  and α{tilde over (S)} j  simultaneously.   
     
     
         40 . The apparatus of  claim 29 , wherein the use of the first ordering of the sequences only for transmission in the known one of the time slots of the radio frame, and the use of the second ordering of the sequences only for transmission in said another known one of the time slots enables detection of radio frame timing using just one of the synchronization signals, S 1  and S 2 . 
     
     
         41 . An apparatus for detecting timing parameters and an identity of a particular cell group from a number, M, of possible cell groups in a signal received in a cellular communication system that employs a radio frame in a physical layer, the radio frame comprising a number of time slots including two time slots associated with a synchronization channel, the apparatus comprising:
 logic configured to receive, in one of the time slots associated with the synchronization channel, one of first and second synchronization signals, S 1  and S 2 , wherein the first synchronization signal S 1  comprises a pair of sequences, {tilde over (S)} i ,{tilde over (S)} j  arranged in a first ordering and the second synchronization signal S 2  comprises the pair of sequences, {tilde over (S)} i ,{tilde over (S)} j  arranged in a second ordering;   logic configured to determine which of a number of predefined sequences best matches the received sequence {tilde over (S)} i , which of the number of predefined sequences best matches the received sequence {tilde over (S)} j , and whether the pair of received sequences {tilde over (S)} i ,{tilde over (S)} j  were arranged in the first ordering or the second ordering, wherein the number of predefined sequences is selected from a group comprising N seq  different sequences, wherein N seq  is at least ceil   
       
         
           
             
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          different sequences; 
         logic configured to identify the particular cell group by performing a cell group identification process that includes determining with which cell group the pair of received sequences, {tilde over (S)} i ,{tilde over (S)} j , is uniquely associated; and 
         logic configured to determine in which one of the two time slots associated with the synchronization channel the one of first and second synchronization signals was received by using information that indicates whether the sequences {tilde over (S)} i ,{tilde over (S)} j  were received in the first ordering or the second ordering. 
       
     
     
         42 . The apparatus of  claim 41 , wherein:
 the first ordering of the pair of sequences, {tilde over (S)} i ,{tilde over (S)} j  causes the sequence {tilde over (S)} i  to be received before receiving the sequence {tilde over (S)} j ; and   the second ordering of the pair of sequences, {tilde over (S)} i ,{tilde over (S)} j  causes the sequence {tilde over (S)} j  to be received before receiving the sequence {tilde over (S)} i .   
     
     
         43 . The apparatus of  claim 42 , wherein S 1  and S 2  are each of length n, and each of the sequences {tilde over (S)} i ,{tilde over (S)} j  is of length n/2. 
     
     
         44 . The apparatus of  claim 41 , wherein:
 the physical layer of the cellular communication system employs Orthogonal Frequency Division Multiplexing;   the first ordering of the pair of sequences, {tilde over (S)} i ,{tilde over (S)} j  causes the sequence {tilde over (S)} i  to be received on a first set of one or more sub-carriers, and the sequence {tilde over (S)} j  to be received on a second set of one or more sub-carriers; and   the second ordering of the pair of sequences, {tilde over (S)} i ,{tilde over (S)} j  causes the sequence {tilde over (S)} j  to be received on the first set of one or more sub-carriers, and the sequence {tilde over (S)} i  to be received on the second set of one or more sub-carriers.   
     
     
         45 . The apparatus of  claim 44 , wherein the first and second synchronization signals, S 1  and S 2 , and the sequences {tilde over (S)} i  and {tilde over (S)} j  are all of equal length. 
     
     
         46 . The apparatus of  claim 41 , wherein:
 in the physical layer of the cellular communication system, symbols of the synchronization signal, S 1 , are separated in a frequency domain;   the first ordering of the pair of sequences, {tilde over (S)} i ,{tilde over (S)} j  causes the sequence {tilde over (S)} i  to be received on a first set of frequencies, and the sequence {tilde over (S)} j  to be received on a second set of frequencies; and   the second ordering of the pair of sequences, {tilde over (S)} i ,{tilde over (S)} j  causes the sequence {tilde over (S)} j  to be received on the first set of frequencies, and the sequence {tilde over (S)} i  to be received on the second set of frequencies.   
     
     
         47 . The apparatus of  claim 41 , wherein the logic configured to determine whether the pair of received sequences {tilde over (S)} i ,{tilde over (S)} j  were arranged in the first ordering or the second ordering comprises:
 logic configured to determine whether the received one of the first and second synchronization signals represents:
     S   1   =α{tilde over (S)}   i   +β{tilde over (S)}   j ; or 
     S   2   =β{tilde over (S)}   i   +α{tilde over (S)}   j , 
   wherein:   α is a first multiplicand;   β is a second multiplicand, α≠β.   
     
     
         48 . The apparatus of  claim 47 , wherein each of the multiplicands, α and β, is a scalar value and corresponds to an amount of signal amplitude. 
     
     
         49 . The apparatus of  claim 47 , wherein each of the multiplicands, α and β, is a scalar value and corresponds to an amount of signal power. 
     
     
         50 . The apparatus of  claim 47 , wherein the first and second synchronization signals, S 1  and S 2 , and the sequences {tilde over (S)} i  and {tilde over (S)} j  are all of equal length. 
     
     
         51 . The apparatus of  claim 41 , wherein the logic configured to receive, in one of the time slots associated with the synchronization channel, one of the first and second synchronization signals S 1  and S 2  comprises:
 logic configured to receive the pair of sequences {tilde over (S)} i ,{tilde over (S)} j  simultaneously.   
     
     
         52 . The apparatus of  claim 41 , comprising:
 logic configured to detect radio frame timing by using information that indicates in which one of the two time slots associated with the synchronization channel the one of the first and second synchronization signals was received.   
     
     
         53 . The apparatus of  claim 41 , wherein the logic configured to identify the particular cell group by determining with which cell group the pair of received sequences, {tilde over (S)} i ,{tilde over (S)} j , is uniquely associated comprises logic configured to use the pair of received sequences {tilde over (S)} i ,{tilde over (S)} j  to locate an entry in a look-up table. 
     
     
         54 . The apparatus of  claim 41 , wherein the logic configured to identify the particular cell group by determining with which cell group the pair of received sequences, {tilde over (S)} i ,{tilde over (S)} j , is uniquely associated comprises calculation circuitry. 
     
     
         55 . The apparatus of  claim 41 , wherein the logic configured to determine in which one of the two time slots associated with the synchronization channel the one of first and second synchronization signals was received by using information that indicates whether the sequences {tilde over (S)} i ,{tilde over (S)} j  were received in the first ordering or the second ordering comprises:
 a look-up table; and   logic configured to use the pair of received sequences {tilde over (S)} i ,{tilde over (S)} j  to locate an entry in the look-up table.   
     
     
         56 . The apparatus of  claim 41 , wherein the logic configured to determine in which one of the two time slots associated with the synchronization channel the one of first and second synchronization signals was received by using information that indicates whether the sequences {tilde over (S)} i ,{tilde over (S)} j  were received in the first ordering or the second ordering comprises:
 calculation circuitry that takes as input the pair of received sequences {tilde over (S)} i ,{tilde over (S)} j .   
     
     
         57 . The apparatus of  claim 41 , comprising:
 logic configured to receive, in an other one of the time slots associated with the synchronization channel, an other one of the first and second synchronization signals;   logic configured to determine whether a type of cell search procedure to be performed is an inter-frequency cell search procedure;   logic configured to determine whether the type of cell search procedure to be performed is an inter-radio access technology cell search procedure;   logic configured to determine whether the type of cell search procedure to be performed is an intra-cell search procedure;   logic configured to respond to the type of cell search procedure to be performed being none of the inter-frequency cell search procedure, the inter-radio access technology cell search procedure, or the intra-cell search procedure, by performing:
 determining which of the number of predefined sequences best matches the received sequence {tilde over (S)} i  of the other one of the first and second synchronization signals, which of the number of predefined sequences best matches the received sequence {tilde over (S)} j  of the other one of the first and second synchronization signals, and whether the pair of received sequences {tilde over (S)} i ,{tilde over (S)} j  of the other one of the first and second synchronization signals were arranged in the first ordering or the second ordering, 
   wherein the cell group identification process further includes determining with which cell group the pair of received sequences, {tilde over (S)} i ,{tilde over (S)} j , of the other one of the first and second synchronization signals is uniquely associated.