Methods for analysing and improving the fault resilience of delay-insensitive codes

Delay-insensitive (DI) codes are usually prone to transient faults occurring during an ongoing transmission. For most DI codewords even a single transient can turn an incomplete transmission into a complete codeword, which is different from the originally sent codeword. Unless further redundant information is provided, the receiver has no means to detect such a transmission fault. In this paper we therefore propose two methods to systematically increase redundancy, either by i) building resilient subcodes, or by ii) using a two-step data encoding where error detecting codes are appropriately combined with delay-insensitive codes. In contrast to existing approaches we carefully avoid the introduction of timing assumptions to mask faults. Both methods are generic and can be used for any 4-phase DI code. In this paper we apply them to m-of-n codes, Berger and Zero-Sum codes and thoroughly analyse the efficiency of the resulting coding schemes.