Hyeong-Gun Joo

New Construction of Rate-Compatible Block-Type Low-Density Parity-Check Codes Using Splitting

In this paper, we construct rate-compatible block-type low-density parity-check (B-LDPC) codes using splitting that cover a wide range of code rates from 1/3 to 4/5. They outperform other rate-compatible B-LDPC codes for all rates and can be decoded conveniently and efficiently. A strong motivation for proposing splitting scheme comes from the observation that the quality of the initial transmission is the most important factor to achieve high throughput of type-II HARQ. Proposed scheme builds low-rate codes from high-rate codes by splitting rows of the given LDPC parity-check matrix. Thus, rate-compatible LDPC codes obtained by splitting have good FER (frame error rate) performance in the first transmission. Contrary to other rate-control methods such as puncturing, shortening, and extending, the splitting algorithm not only needs smaller number of operations but also shows faster decoding convergence speed since more efficient Tanner graph is used for the decoding

Optimal Puncturing of Block-Type LDPC Codes and Their Fast Convergence Decoding

In this paper, we study and propose a puncturing algorithm of block-type low-density parity-check (B-LDPC) codes. This optimal puncturing algorithm is derived from the fact that puncturing of parity bits is equivalent to merging the check nodes. Furthermore, we propose a new decoding algorithm suitable for the punctured B-LDPC codes. This decoding algorithm needs not only smaller number of operations at each iteration, but also shows faster decoding convergence speed than the conventional erasure decoding algorithm. If the optimally punctured B-LDPC code is decoded by the new decoding algorithm, it results in the same performance as the unpunctured B-LDPC code of the same code rate

Construction and analysis of rate-compatible punctured concatenated zigzag codes

In this paper, new rate-compatible punctured concatenated zigzag (RCPCZ) codes are proposed and analyzed by using the density evolution technique. This analysis gives the design criteria for the rate-compatible puncturing patterns and accordingly good puncturing patterns for constructing RCPCZ codes are obtained. Since RCPCZ codes are linear-time encodable and show capacity-approaching performance, they can be a good candidate technology for the next-generation communication systems. As their applications, Type-II hybrid automatic repeat request (HARQ) using RCPCZ code is constructed, which gives higher throughput than Type-II HARQ using RCMCZ code

Adaptive Bit-Reliability Mapping for LDPCCoded High-Order Modulation Systems

In this paper, an adaptive bit-reliability mapping is proposed for the bit-level Chase combining in LDPC-coded high-order modulation systems. Contrary to the previously known bit-reliability mapping that assigns the information (or parity) bits to more (or less) reliable bit positions, the proposed mapping flexibly assigns codeword bits to the bit positions of various reliabilities by considering the characteristics of code and protection levels. Compared with the symbol-level Chase combining and the constellation rearrangement bit mapping, the proposed mapping gives 0.7 - 1.3 dB and 0.1 - 1.0 dB performance gain at FER = 10-3 with no additional complexity, respectively. The adaptive bit-reliability mappings are derived for various environments and the validity of them is confirmed through simulation.

Parameter optimization of decode-and-partial-forward scheme

In this paper, a decode-and-partial-forward (DPF) scheme for the half-duplex relay system is proposed, which transmits only a part of codewords by considering code and channel characteristics at the relay. Furthermore, optimization of the time-division parameter in DPF scheme is performed to obtain performance improvement.

Optimal Rate-Compatible Irregular Concatenated Zigzag Codes Using Puncturing and Pruning

In this paper, we show that irregular concatenated zigzag (ICZZ) codes are suitable as mother codes to support a wide range of code rates. We introduce the degree distribution matching method to derive the optimal puncturing and pruning patterns in order to achieve the rate-compatible target code rates of ICZZ code. By combining ICZZ code with the optimal puncturing and pruning patterns, new rate-compatible ICZZ (RC-ICZZ) codes are constructed. In an example, n RC-ICZZ code to achieve the code rates 1/3, 1/2, 2/3, 4/5, and 8/9 is constructed and shown to outperform RCTC adopted in 3GPP. Therefore, RC-ICZZ codes are suitable for hybrid automatic repeat request to increase the system throughput.

Bit-mapping Schemes of LDPC Codes for Partial Chase Combining

In this paper, a bit-mapping scheme is proposed for partial Chase combining in LDPC-coded systems. Contrary to the previously known bit mapping that assigns the information bits to more reliable channels, the proposed mapping assigns the codeword bits of irregular LDPC codes to distinct Gaussian channels by considering the characteristics of LDPC codes and channels. The recursion equation for partial Chase combining is derived by using the density evolution technique, based on it, the best bit mapping among the various bit-mapping schemes is derived, and the validity of them is confirmed through simulation.

Construction of Rate-Compatible Block-Type LDPC Codes using Extending and Puncturing

In this paper, we propose a construction method of rate-compatible block-type low-density parity-check (RC B-LDPC) codes using extending and puncturing, which works well over a wide range of code rates by decreasing the amount of puncturing nodes to mitigate the performance degradation at high rate range. RC B-LDPC code constructed by the proposed scheme to achieve the target code rates from 1/3 to 4/5 results in good frame error rate (FER) performance, even better than the well- designed rate-1/3 code in the small number of iterations (say, < 20).