Abstract: An apparatus is provided in a digital communications device for efficiently determining the Hamming distance for trellis based decoders, such as decoders for punctured convolutional codes. The Hamming distance is pre-determined for all codes and stored in program memory. In one version, the device comprises five components including a state sequencing circuit, a Hamming distance table generator, a Hamming distance table, a Hamming distance retrieval circuit, and an ACS circuit. The state sequencer groups all of the possible 2m possible states into groups of similar branch metrics. The Hamming distance table generator is responsive to the state sequencer and determines the Hamming distance for all combinations of puncture code, received symbol, and transition paths. This may be performed once and stored in permanent memory or performed each time the digital communications device is initialized and stored in a random access memory.

Abstract: A digital cellular telephone using a scalable channel coding scheme includes a memory arranged as a three-dimensional code book. The three-dimensional code book may receive the following three input variables: 1. The number of bit classes; 2. The number of bits per frame to be coded; and 3. The available size of the output codeword based on available channel capacity. For each of these input variables, the three-dimensional code book may output the following scalable coding parameters: 1. The number of bits per frame are partitioned into each of the coding classes; and 2. The puncture code per class. The invention provides the scalable coding parameters in real-time. It does this, however, without calculating the parameters in real-time. The memory may be arranged in the following manner. A number of information bits to be coded is determined by a mode of the transmission signal.