On asymptotically optimum rate 1/n convolutional codes for a given constraint length

The criterion used to find good convolutional codes has traditionally been the maximization of the free distance for a given constraint length and code rate. In this letter we approach convolutional code design from a different perspective. We assume no constraints in the rate of the code, and the only restriction is in the constraint length. That is, we assume we can utilize as much bandwidth as necessary but we are complexity-limited by the constraint length we can afford. The results are optimum codes for a given constraint length, which can find application, for example, in CDMA systems.