Adaptive Cell ID Detection in a Cellular Communications System

A method of detecting a cell identifier in a received signal that was transmitted in a cellular communication system, wherein the signal includes a plurality, N, of reference symbols that together represent one of M orthogonal codes, wherein each of the codes has a length N of code symbols, the method comprising:

• determining whether a cell search procedure to be performed is of a first type;
• if the cell search procedure to be performed is of the first type, then generating a constructed code from a first number of the reference symbols, wherein the constructed code generated from the first number of the reference symbols represents one of M orthogonal codes;
• if the cell search procedure to be performed is not of the first type, then generating the constructed code from a second number of the reference symbols, wherein the constructed code generated from the second number of the reference symbols represents one of M orthogonal codes;
• and
• correlating the constructed code against a plurality of known codes to detect the cell identifier,
• wherein:
• at least one of the first number of the reference symbols and the second number of the reference symbols is a subgroup of length L of the reference symbols, wherein L<N;
• and
• the M codes are orthogonal with one another over their length, N, of code symbols, are orthogonal with one another over the first number of code symbols, and also are orthogonal over one another over the second number of code symbols.

An apparatus for indicating a cell identifier in a signal to be transmitted in a cellular communication system, the apparatus comprising:

• logic configured to select one of a plurality, M, of codes, wherein each of the codes has a length N of code symbols, and wherein the selected code is associated with the cell identifier;
• and
• logic configured to transmit the selected code as a plurality, N, of reference symbols,
• wherein the M codes are orthogonal with one another over their length, N, of the code symbols and also over at least one subgroup of length L of the code symbols, wherein L<N.

An apparatus for detecting a cell identifier in a received signal that was transmitted in a cellular communication system, wherein the signal includes a plurality, N, of reference symbols that together represent one of M orthogonal codes, wherein each of the codes has a length N of code symbols, the apparatus comprising:

• logic configured to determine whether a cell search procedure to be performed is of a first type;
• logic configured respond to the cell search procedure to be performed being of the first type by generating a constructed code from a first number of the reference symbols, wherein the constructed code generated from the first number of the reference symbols represents one of M orthogonal codes;
• logic configured to respond to the cell search procedure to be performed not being of the first type by generating a constructed code from a second number of the reference symbols, wherein the constructed code generated from the second number of the reference symbols represents one of M orthogonal codes;
• and
• logic configured to correlate the constructed code against a plurality of known codes to detect the cell identifier,
• wherein:
• at least one of the first number of the reference symbols and the second number of the reference symbols is a subgroup of length L of the reference symbols, wherein L<N;
• and
• the M codes are orthogonal with one another over their length, N, of code symbols, are orthogonal with one another over the first number of code symbols, and also are orthogonal over one another over the second number of code symbols.