แนวคิดหลัก
Spatially coupled LDPC codes can universally achieve the symmetric information rates of different intersymbol interference channels.
บทคัดย่อ
The paper investigates the performance of spatially coupled low-density parity-check (SC-LDPC) codes over intersymbol interference (ISI) channels with erasures and additive white Gaussian noise (AWGN).
Key highlights:
- The authors derive the exact input/output transfer functions of the optimal a-posteriori probability channel detector for general ISI channels with erasures.
- Using these transfer functions, they compute the belief propagation (BP) and maximum a-posteriori (MAP) thresholds for regular SC-LDPC codes with joint iterative detection and decoding.
- The results show an apparent inconsistency in the performance ranking of the ISI channels when comparing the thresholds for erasures and AWGN. This can be resolved by looking at the thresholds from an entropy perspective.
- The authors demonstrate that with spatial coupling, the BP thresholds approach the symmetric information rates (SIRs) of the corresponding ISI channels, supporting the conjecture that SC-LDPC codes can universally approach the SIR of ISI channels.
- This makes spatially coupled codes superior to uncoupled irregular codes that need to be optimized for a particular ISI channel, as they cannot guarantee robust performance if the channel is changed.
สถิติ
The channel impulse responses of the three considered ISI channels are given in Table I.
The transfer functions of the three ISI channels are provided in Table III.