Method of Allocating Walsh Codes and Quasi-Orthogonal Functional Codes in a CDMA Network

A method of allocating Walsh codes and Quasi-orthogonal Functional, QoF, codes to mobile terminals in a Code Division Multiple Access, CDMA, system in which a finite number of Walsh codes are defined, and some mobile terminals operating in the CDMA system are capable of supporting Advance Quasi-Linear Interference Cancellation, AQLIC, and some mobile terminals operating in the CDMA system are non-AQLIC-capable, the method comprising the steps of:

• determining a threshold number of Walsh codes to reserve for non-AQLIC-capable mobile terminals;
• determining whether a current Walsh code usage level is greater than the threshold;
• when the current Walsh code usage level is not greater than the threshold, allocating Walsh codes to both the AQLIC-capable mobile terminals and the non-AQLIC-capable mobile terminals;
• and
• when the current Walsh code usage level is greater than the threshold:
• allocating QoF codes only to AQLIC-capable mobile terminals;
• and
• allocating Walsh codes to non-AQLIC-capable mobile terminals.

A code allocation unit for allocating Walsh codes and Quasi-orthogonal Functional, QoF, codes to mobile terminals in a Code Division Multiple Access, CDMA, system in which a finite number of Walsh codes are defined, and some mobile terminals operating in the CDMA system are capable of supporting Advance Quasi-Linear Interference Cancellation, AQLIC, and some mobile terminals operating in the CDMA system are non-AQLIC-capable, the code allocation unit comprising:

• a program memory for storing computer program instructions;
• and
• a code allocation processor for executing the computer program instructions, wherein execution of the computer program instructions causes the processor to:
• utilize a current Walsh code usage level and a penetration level for non-AQLIC-capable mobile terminals as inputs to determine a threshold number of Walsh codes to reserve for the non-AQLIC-capable mobile terminals;
• determine whether the current Walsh code usage level is greater than the threshold;
• allocate Walsh codes to both the AQLIC-capable mobile terminals and the non-AQLIC-capable mobile terminals when the current Walsh code usage level is not greater than the threshold;
• and
• allocate QoF codes only to AQLIC-capable mobile terminals while allocating Walsh codes to non-AQLIC-capable mobile terminals when the current Walsh code usage level is greater than the threshold.