VERY-LOW VARIABLE-RATE CONVOLUTIONAL-CODES FOR UNEQUAL ERROR PROTECTION IN DS-CDMA SYSTEMS

Convolutional codes based on Hadamard sequences can achieve both ortho gonality and variable rate, In contrast with other convolutional codin g techniques, these codes incur no processing gain penalty in direct-s equence code-division multiple-access (DS-CDMA) systems, We describe h ere class of such codes called ''telescopic protection codes.'' These codes enable variable-rate error protection in the manner of rate-comp atible punctured-convolutional (RCPC) codes, but preserve the Hadamard orthogonality properties necessary to maintain processing gain that R CPC codes lack.