Wangrok Oh

Joint decoding and carrier phase recovery algorithm for turbo codes

In this letter, we investigate the sensitivity of the iterative maximum a posteriori probability (MAP) decoder to carrier phase offsets and propose simple carrier phase recovery algorithms operating within the iterative MAP decoding iterations. The algorithms exploit the information contained in the extrinsic values generated within the iterative MAP decoder to perform carrier recovery, thus requiring low hardware complexity.

Iterative decoding and channel parameter estimation algorithms for repeat-accumulate codes

The sensitivity of the iterative decoder for repeat-accumulate (RA) codes to carrier phase and channel signal-to-noise ratio estimation errors is investigated, and efficient algorithms to estimate and correct these errors are developed. The behavior of RA codes with imperfect channel estimation is different from that of turbo codes, and correction algorithms specific to RA codes must be formulated. The proposed algorithms use the soft information generated within the iterative decoder, and thus, are not only hardware-efficient, but also offer excellent performance.

Improving the performance of turbo codes with a simple protection scheme for error-prone bit positions

It is well known that turbo codes provide highly unequal error protection within a transmitted frame. Previous attempts to exploit this fact focused mainly on adding additional redundancy to provide extra protection for the error-prone bit positions. Here, instead, we use the error-detection capability of the cyclic redundancy check (CRC), which is almost always employed in practical systems. Once a frame is declared uncorrectable by the CRC, a process termed the error-prone bit processing procedure is activated in an attempt to correct the probable error patterns which are a priori identified as being error-prone.

Modified RA codes suitable for BPSK modulated systems with non-data-aided carrier recovery

A 180deg carrier phase ambiguity is inevitable in digital communication systems employing binary phase-shift keying modulation and non-data-aided carrier phase recovery. Here, we propose a simple modification to standard regular RA codes by exploiting differential encoding inherent to inner encoder of RA codes resulting in a 180deg rotationally invariant RA code