自适应格状编码调制

介绍了多维格状编码调制（MTCM）及其自适应格状编码调制的设计方法,并模拟了固定码率TCM与自适应TCM在衰落信道中的误码性能。     

一种格状编码调制结合交织技术性能研究

将格状编码 调制（TCM）技术与数据交织技术相结合,研究在数字传输系统中的传输性能,给出了数据交织与非交织条件下该编码调制技术的计算机模拟结果。模拟结果表明：采用格状编码与交织技术可 使信道传输的误码率降低,编码增益提高。     

格状编码技术在超短波战术数据链中的性能研究

介绍一种将格状编码（TCM）技术与RS编、译码相结合，对它在超短波战术数据链传输中的应用进行了分析。仿真结果表明：采用格状编码与RS技术可使信道传输的误码率大大降低，对提高数据传输效率和信道的利用率具有优越的性能，能更好地满足战术数据传输要求。     

移动衰落信道下的格状编码MPSK调制

衰落信道下的格状编码调制(TCM)与加性高斯白噪声(AWGN)信道下的TCM在设计方法上有所不同。已经知道,在AWGN信道下格状码设计的性能标准是最大的自由欧氏距离(MFED)。在本文中,我们将给出在高信噪比Rician衰落信道下应用交错/解交错时,最佳格状码设计的另外两个性能标准:最短错误路径长度和沿该路径的分支距离乘积。基于这一点,多维TCM由于其在最短错误路径长度上的更大自由度,因而更适合于移动信道。最后,本文根据以上两个标准推导了衰落信道下多维MPSK信号的集合分块方法,结果表明,衰落信道下的最佳集合分块不一定对应一树状结构。     

级联码结合交织技术的纠错性能研究

本文将格状编码调制(TCM)技术与RS纠错码相结合,研究在数字传输系统中的纠错性能与抗干扰能力,给出了数据交织与非交织条件下差错控制系统的计算机模拟结果。模拟结果表明：采用级联码与交织技术可使信道传输的误码率从10^-3降至10^-7,编码增益提高35dB。     

激光水下通信TURBO码应用研究

由于水下通信信道对光信号的衰减极大,实际通信系统的编码应具有极强纠随机差错和纠突发差错的能力.针对激光水下通信信道的特殊性,对信道模型进行分析,结合当前优异的编码技术--turbo码对信道进行编码,并通过与未编码系统的性能进行比较,从而得出了turbo码实现低误码率的水下信息传输的优越性.     

运用格状图支路转移规则和Viterbi算法实现数字信号盲估计

该文提出了一种新的离散数字信道盲估计算法,运用格状图中的一步支路转移规则,大大削减了最佳估计所要求的计算量。文中首先介绍了符合最大似然序列估计(MLSE)准则的信道最佳盲估计算法,然后阐述了运用格状图中的一步支路转移规则对格状图进行筛选的基本思想,接着详细介绍了本算法,最后通过数值仿真研究了本算法的性能。     

多载波格状编码调制的实现和性能分析

本文综合考虑复杂度、时延和实时性等因素,讨论了格状编码应用在多载波调制系统中的具体实现方案,并在ADSL DMT环境下对其性能进行了模拟分析。结果显示,格状编码用于多载波调制系统时仍然能够获得大部分理论编码增益。     

脉冲重双叠PPM直接检测光信道上的TCM设计

本文研究了脉冲笪叠脉位调制直接检测光信道上的格状编码调制设计的性能准则和设计方法。根据所采用的调制格式和光信号检测方式的特点，本文导出了码字路径间的一种距离量度，并以之作为ＴＣＭ设计的基础，给出了相应的设计方法及实例。     

MSK上的格状编码调制

Ungerboeck提出的格状编码调制技术,将编码和Modem信号星座视为一体进行设计,性能优越,具有很高的实用价值。本文提出了MSK上的格状编码方法,和文献[5]中的相比,避免了不必要的计算机搜索找码的过程,而且编码性能也较之优越。     

Joint source-coding, channel-coding and modulation schemes for AWGN and Rayleigh fading channels

Joint source-coding, channel-coding and modulation schemes based on variable length codes, inphase-quadrature phase interleaved trellis coded modulation (TCM) and turbo TCM (TTCM) schemes are proposed. A significant coding gain and a lower error floor are achieved without bandwidth expansion.     

Turbo码和高频谱利用率调制技术

本文论述了Ｔｕｒｂｏ码的基本原理和译码器结构。介绍一种联合Ｔｕｒｂｏ码调制方案，并将之与格状编码调制方案进行比较。     

A Simplified Decoding Algorithm Using Symbol Transformation for Turbo Pragmatic Trellis‐Coded Modulation

This paper presents the application of a turbo coding technique combined with a bandwidth efficient method known as trellis‐coded modulation. A transformation applied to the incoming I‐channel and Q‐channel symbols allows the use of an off‐the‐shelf binary/quadrature phase shift keying (B/QPSK) turbo decoder without any modifications. A conventional turbo decoder then operates on transformed symbols to estimate the coded bits. The uncoded bits are decoded based on the estimated coded bits and locations of the received symbols.     

Turbo coded multiple-antenna systems for near-capacity performance

For a turbo coded BLAST (Bell LAbs Space-Time architecture) system with N_t transmit antennas and N_r receive antennas, there is a significant gap between its detection threshold and the capacity in case N_t > N_r. In this paper, we show that by introducing a convolutional interleaver with block delay between the BLAST mapper and the turbo encoder, the threshold can be improved. Near-capacity thresholds can be achieved for some cases. To take advantage of the low detector complexity in Alamouti STBC (space-time block code), we also investigate a STBC system, which is the concatenation of the Alamouti STBC with a turbo trellis coded modulation. By using a proper labelling and adding a convolutional interleaver with block delay to such a STBC system, we achieve both lower error floors and lower thresholds.     

Joint MAP equalization and channel estimation forfrequency-selective and frequency-flat fast-fading channels

This paper presents a new fractionally-spaced maximum a posteriori (MAP) equalizer for data transmission over frequency-selective fading channels. The technique is applicable to any standard modulation technique. The MAP equalizer uses an expanded hypothesis trellis for the purpose of joint channel estimation and equalization. The fading channel is estimated by coupling minimum mean square error techniques with the (fixed size) expanded trellis. The new MAP equalizer is also presented in an iterative (turbo) receiver structure. Both uncoded and conventionally coded systems (including iterative processing) are studied. Even on frequency-flat fading channels, the proposed receiver outperforms conventional techniques. Simulations demonstrate the performance of the proposed equalizer     

Sliding window and interleaver design

Terminating the trellis was considered essential to lower the bit error probability in a turbo coded system. When a sliding window algorithm is used, this issue becomes even more important. It is shown that trellis termination can be completely ignored by using an interleaver that takes into account the particular window size of the sliding window algorithm     

无线信道中网格编码调制技术研究

网格编码调制技术（TCM）是一种将编码与调制有机结合起来的技术,可使系统的频带利用率和功率资源同时得到有效利用。在对TCM原理和结构分析的基础上,研究了网格编码调制技术中的几个关键技术,主要包括集分割原理和无线信道下TCM误码率的分析,最后对无编码的QPSK与8PSK—TCM进行了仿真比较。仿真结果表明,在无线信道相同的误码率下,采用网格编码调制技术比未编码QPSK获得2dB的编码增益。     

The performance of type-I trellis coded hybrid-ARQ protocols overAWGN and slowly fading channels

A method is described for modifying trellis coded modulation systems for use in type-1 hybrid-ARQ protocols. The difference between the partial path metric of the survivor and that of the best nonsurvivor at each node in the trellis is used to determine the desirability of a retransmission request for a given received packet. Bounds on the reliability and throughput performance of the resulting error control scheme are derived for AWGN channels and slowly fading Rician channels. Examples are included to illustrate the achievable gain of the proposed system relative to ordinary forward-error-correcting trellis coded systems. Hybrid-ARQ protocols based on ordinary trellis coded modulation and multiple trellis coded modulation are also compared over slowly fading Rician channels. The dependence of performance on packet length is examined and illustrated by examples. All analytical results are supported by data from a series of simulations     

Iterative Equalization and TCM Decoding with Refined Channel Value

In this correspondence, we present a new method for the iterative equalization and decoding of multilevel trellis coded modulation (TCM) signals over frequency selective channels. Results show that the proposed algorithm achieves better performance compared to the previous work on the MMSE filter- based turbo equalization for a non-binary coded modulation scheme. The performance gain is accomplished by utilizing the combined modulation and coding nature of TCM and passing the refined signal obtained from different paths to the TCM decoder as the channel value in addition to the a priori probabilities.     

一种短延时Turbo编码调制系统的设计

本文设计了一种比传统体制减少了一半延时的Turbo编码调制系统,介绍了交织器的相关限制.提出了一种在译码过程中对信道值的估计方法,使得外信息的计算更加趋于精确,从而提高了译码性能.这种迭代译码算法是标准格码调制译码算法的一种自然推广,同时也类似于二元Turbo码在BPSK调制下的逐比特译码算法.采用吞吐率为2bits/s/Hz的8PSK调制,比特错误率为10^-5所需的信噪比与Shannon限相距不到0.4dB.