Quadriphase spreading codes in code division multiple access communications

In a code division multiple access (CDMA) communications system in which a plurality of communications devices communicate using allocated communications channels, each channel corresponding to one of a set of CDMA spreading codes, a method comprising:

• generating a family of original codes, each original code having a predetermined length, and
• extending the length of original codes from the family of spreading codes by a code symbol to generate a family of CDMA spreading codes by detecting the end of one of the original codes, and adding the code symbol to the end of one of the original codes.

In a code division multiple access (CDMA) communications system in which a plurality of communications devices communicate using allocated communications channels, each channel corresponding to one of a set of CDMA spreading codes, a method comprising:

• generating a family of original codes, each original code having a predetermined length, and
• extending the length of original codes from the family of spreading codes by a code symbol to generate a family of CDMA spreading codes by detecting the end of one of the original codes, and adding the code symbol to the end of one of the original codes,
• wherein the family of original codes has a length of L=2m−1, where m is an integer, and a single code symbol is added to the end of the original code periodically.

In a code division multiple access (CDMA) communications system in which a plurality of communications devices communicate using allocated communications channels, each channel corresponding to one of a set of CDMA spreading codes, a method comprising:

• generating a family of original codes, each original code having a predetermined length, and
• extending the length of original codes from the family of spreading codes by a code symbol to generate a family of CDMA spreading codes by detecting the end of one of the original codes, and adding the code symbol to the end of one of the original codes,
• wherein the family of original codes are an S(2) family of codes and the code symbol is selected to minimize cross-correlation between CDMA spreading codes.

A CDMA code generator providing CDMA spreading codes, comprising:

• one or more feedback shift registers having m stages, where m is an integer, where an output of a last stage is fed back to an input of a first stage, the output of the one or more feedback shift registers corresponding to one of a family of codes, and
• electronic circuitry for adding an additional code symbol to the one code to provide an extended code corresponding to one of the CDMA spreading codes.

In a mobile communications system including plural base stations for communicating with mobile stations and employing spreading codes from a particular spreading code family for radio communications between the mobile stations and the base stations, a method comprising:

• allocating a first subset of the particular spreading code family to a first base station, and
• allocating a second subset of the particular spreading code family to a second base station,
• wherein the spreading codes in the first and second subsets have lower cross-correlation than spreading codes in the particular spreading code family.

In a mobile communications system including base station having plural sectors for communicating with mobile stations and employing spreading codes from a particular spreading code family for radio communications between the mobile stations and the base station, a method comprising:

• allocating a first subset of the particular spreading code family to a first base station sector, and
• allocating a second subset of the particular spreading code family to a second base station sector,
• wherein the spreading codes in the first and second subsets have lower cross-correlation than spreading codes in the particular spreading code family.

In a code division multiple access (CDMA) communications system in which a plurality of communications devices communicate using allocated communications channels, each channel corresponding to one of a set of CDMA spreading codes, a method comprising:

• generating a family of original S(2) quaternary spreading codes, each original code having a predetermined length, and
• extending the length of original codes from the family of original S(2) quaternary spreading codes by a code symbol to generate a family of CDMA spreading codes without having to increase the number of the original codes from the family.

A CDMA code generator providing CDMA spreading codes, comprising:

• one or more feedback shift registers having m stages, where m is an integer, where an output of a last stage is fed back to an input of a first stage, the output of the one or more feedback shift registers corresponding to one of a family of S(2) quaternary spreading codes of length L=2m−1, and
• electronic circuitry for adding an additional code symbol to the one S(2) quaternary spreading code to provide an extended S(2) quaternary spreading code corresponding to one of the CDMA spreading codes.