Mao-Chao Lin

A coded modulation scheme with interblock memory

Proposes a coded modulation scheme with interblock memory. The proposed scheme has a multi-stage coding structure. However, at some coding stage, the coding designs for every two adjacent blocks are related. Compared to coded modulation schemes for which each block is independent of the others, the introduction of interblock coding provides additional flexibility in the design. In this way, for the proposed scheme, one can achieve a large minimum Euclidean distance while the number of nearest neighbors is not too large. The authors also design a multi-stage decoding algorithm, which is optimum in each stage and has low decoding complexity. Three specific examples are provided to demonstrate the advantages of the proposed scheme. >

Differential phase detection using recursively generated phase references

We show that decision-feedback differential phase detection (DFDPD) is equivalent to a technique which generates a phase reference by averaging several primitive phase references. We then modify the DFDPD into a differential phase detection (DPD) technique which generates the phase reference using a simple recursive form. The proposed technique can be easily implemented and has satisfactory error performance.

On constructing trellis codes with large free distances and low decoding complexities

We propose a trellis-coding scheme for which large free distances and low decoding complexities can be easily achieved. The proposed trellis-coding scheme is a generalization of the trellis-coding scheme proposed by Hellstern (1993). With the proposed trellis-coding scheme, we have the flexibility of controlling the decoding delay.

Adaptive quantization for low-density-parity-check decoders

For the implementation of low-density parity-check (LDPC) decoders, the associated error performance and the complexity are significantly affected by the number of quantization bits used. In this paper, we propose an adaptive quantization scheme, which uses different quantization schemes at different iteration numbers based on a fixed number of quantization bits. Simulation results show that the proposed adaptive quantization can reduce the number of quantization bits without error performance degradation.

A Construction of Physical-Layer Systematic Raptor Codes Based on Protographs

A construction of physical-layer Raptor (PLR) codes based on protographs is proposed. We first set up a sequence of signal-to-noise ratios (SNRs). For each SNR, we employ a modified protograph EXIT analysis to find the extra check nodes in addition to the existing check nodes so as to meet the threshold required by the outer low-density parity check code. PLR codes which are capacity-approaching for a wide SNR range can be obtained using the proposed construction.

The performance analysis of a concatenated ARQ scheme using parity retransmissions

The authors analyze an ARQ (automatic repeat request) scheme using parity retransmissions. By dividing each transmission block into subblocks, the combination of a transmission block and its retransmission block has the structure of a concatenated code. They derive formulae for calculating an upper bound on the probability of undetected errors and a lower bound on the throughput for such an ARQ scheme. Numerical results show that even with extremely simple code design, such an ARQ scheme has satisfactory performance. >

On block-coded modulation with interblock memory

Block-coded modulation with interblock memory (BCMIM) is a variation of block-coded modulation (BCM) which is designed for multilevel coding. By providing interblock memory between adjacent blocks, the coding rate of a BCMIM scheme can be increased without decreasing the minimum squared Euclidean distance (MSED) as compared to the original BCM. In an early version of BCMIM, interblock coding is provided only between the first two coding levels of adjacent blocks. In this paper, we design BCMIM with a more general form for which interblock coding can be introduced among many coding levels. In this way, we can further increase the coding rate of BCMIM without decreasing the MSED. We provide many examples to show the advantages of BCMIM with the general form. Most of the examples are designed based on multidimensional signal sets, since a multidimensional signal set can provide more coding levels than a two-dimensional (2-D) signal set.

A trellis coded modulation scheme constructed from block coded modulation with interblock memory

Proposes a new trellis coded modulation scheme which is constructed by combining a convolutional code and a variation of block coded modulation called block coded modulation with interblock memory. In the proposed scheme, each coded multidimensional signal point has a kind of two-fold dependency on other coded multidimensional signal points. In addition to the dependency on other coded multidimensional signal points described by the trellis of a convolutional code, each coded multidimensional signal point has another form of dependency on one previously coded multidimensional signal point. The additional dependency comes from the design of block coded modulation with interblock memory. >

A trellis coded modulation scheme with a convolutional processor

We propose a new trellis coded modulation (TCM) scheme. The proposed TCM is encoded by employing the encoder of a convolutional code C, which is followed by a convolutional processor and a signal mapper. Large free distances can be easily achieved for the proposed TCM. The decoding can be implemented by using the trellis for the convolutional code C with some feedback information.

Further Exploration of Convolutional Encoders for Unequal Error Protection and New UEP Convolutional Codes

In this paper, the unequal error protection (UEP) capability of convolutional encoders, in terms of the separation vector, is studied from an algebraic viewpoint. A simple procedure is presented for constructing a generator matrix, which is basic and has the largest separation vector for every convolutional code. Such a generator matrix would be desirable, since the corresponding encoder not only achieves UEP optimality, but also avoids undesired catastrophic error propagation. In addition, canonical generator matrices, which are both basic and reduced, are even more preferable for encoding, since they attain the lowest complexity for Viterbi decoding. However, the direct transformation from a UEP-optimal generator matrix to a canonical generator matrix may come with an unexpected loss of the separation vector. We also propose a specific type of transformation matrix that reduces the external degrees of the generator matrices, from which canonical generator matrices can be constructed that include the mitigated degradation of the separation vector. Finally, beneficial UEP convolutional codes that achieve the maximum free distances for the given code parameters are provided.