Design and Analysis of a Concatenated Code for Intersymbol Interference Wiretap Channels
This work addresses secure communication in specific wiretap channels with intersymbol interference, representing an incremental improvement in coding schemes for this domain.
The authors tackled reliable and secure communication over intersymbol interference wiretap channels by proposing a two-stage concatenated coding scheme that integrates LDPC and trellis codes, achieving tight lower bounds on secrecy capacity and optimizing degree distributions to drive information leakage to zero.
We propose a two-stage concatenated coding scheme for reliable and secure communication over intersymbol interference wiretap channels. We first establish the secrecy capacity. Then, motivated by the theoretical codes that achieve the secrecy capacity, our scheme integrates low-density parity-check (LDPC) codes in the outer stage, forming a nested structure of wiretap codes, with trellis codes in the inner stage to improve achievable secure rates. The trellis code is specifically designed to transform the uniformly distributed codewords produced by the LDPC code stage into a Markov process, achieving tight lower bounds on the secrecy capacity. We further estimate the information leakage rate of the proposed scheme using an upper bound. To meet the weak secrecy criterion, we optimize degree distributions of the irregular LDPC codes at the outer stage, essentially driving the estimated upper bound on the information leakage rate to zero.