SYSTEMATIC PROXIMITY-DETECTING CODES

This paper defines t-proximity-detecting (t-PD) codes that can detect when a received word is within distance t from the transmitted codewor d, when using a four-phase asynchronous communication protocol (or oth er similar protocols). Proximity-detecting codes can be used to improv e the performance of asynchronous buses. A nontrivial t-proximity-dete cting code must be unordered. However, not all unordered codes are t-p roximity-detecting. This paper characterizes t-PD codes, and presents some properties of such codes. Designs of systematic 1-PD codes, and t heir generalization to t-PD codes are presented, along with a bound on the number of checkbits.