共查询到20条相似文献,搜索用时 15 毫秒
1.
2.
本文讨论了格形码距离谱的计算问题,定义了度量空间意义下的广义准正则格形码,对具有Imai与Hirakawa[2]和Ungerboeck[3]定义的典型的时不变网格结构的广义准正则格形码,证明了其距离谱可用全零信息序列对应的码字进行计算。在理论上推广了M.Rouance与D.J.Costelo的结果,解决了非平方欧几里德度量意义下一类TCM信号序列的距离谱计算问题 相似文献
3.
In this paper, we present a novel concatenated trellis coded modulation (CTCM) scheme for limited diversity order fading channels. Examples for such channels include those encountered in indoor wireless networks like IEEE 802.11. It is first shown that when the diversity order afforded by the channel is fixed, bit interleaved coded modulation (BICM) is no longer the best way to encode. We then develop CTCM, which is superior to both BICM and conventional TCM of similar complexities. Unlike conventional TCM where convolutional codes are designed over modulated signal sets, CTCM has TCM concatenated to short length inner codes. Each trellis branch in the TCM now corresponds to a short block-code. We discuss design of good inner codes that allow for simple decoders. CTCM design incorporates useful features of both BICM and conventional TCM. Code design is explained with examples. Simulation results and information theoretic supporting the arguments are shown. 相似文献
4.
Lv Shujuan Wei Guo Zhu Jinkang 《电子科学学刊(英文版)》2006,23(3):355-360
In this paper, a novel multiple trellis coded orthogonal transmit scheme is proposed to exploit transmit diversity in fading channels. In this scheme, a unique vector from a set of orthogonal vectors is assigned to each transmit antenna. Each of the output symbols from the multiple trellis encoder is multiplied with one of these orthogonal vectors and transmitted from corresponding transmit antennas. By correlating with corresponding orthogonal vectors, the receiver separates symbols transmitted from different transmit antennas. This scheme can be adopted in coherent/differential systems with any number of transmit antennas. It is shown that the proposed scheme encompasses the conventional trellis coded unitary space-time modulation based on the optimal cyclic group codes as a special case. We also propose two better designs over the conventional trellis coded unitary space-time modulation. The first design uses 8 Phase Shift Keying (8-PSK) constellations instead of 16 Phase Shift Keying (16-PSK) constellations in the conventional trellis coded unitary space-time modulation. As a result, the product distance of this new design is much larger than that of the conventional trellis coded unitary space-time modulation. The second design introduces constellations with multiple levels of amplitudes into the design of the multiple trellis coded orthogonal transmit scheme. For both designs, simulations show that multiple trellis coded orthogonal transmit schemes can achieve better performance than the conventional trellis coded unitarv space-time schemes. 相似文献
5.
本文提出了一种通过调整非编码信息量,并与信号映射相结合来改变编码、调制模式的自适应Turbo TCM编码调制方案,称之为基于非编码信息匹配的自适应Turbo TCM编码调制方案.由于将Turbo码和TCM编码调制技术相结合得到的Turbo TCM编码调制方案的带宽效率高,所以,在慢时变无线衰落信道中,自适应Turbo TCM编码调制的平均频谱效率也将很高.给出了该方案的工作原理、设计方法,并通过蒙特卡洛(Monte Carlo)仿真研究了该方案的性能.与现有编码调制方案相比,该方案具有频谱效率高、易于设计和实现的优点. 相似文献
6.
本文分析室内无线多径衰落信道中网络编码调制的直扩多址通信系统的性能,系统采用网络编码多相调制技术以改善系统性能,本文讨论了网格编码技术与系统性能之间的关系及载波恢复相位误差对系统性能的影响,本文给出了误码率的理论分析结果和计算机模拟结果,并与常规的未编码直扩系统性能对比。 相似文献
7.
为了克服多天线信道相关性的影响,提出一种新的自适应发送方案。应用空时分组码特征波束成型技术和格形编码调制(TCM)来获得分集增益和编码增益。针对采用和不采用交织器两种情况,基于成对差错概率(PEP)准则。分析了系统的统计性能,分别得到了使系统编码增益和分集增益最大化的TCM设计准则。根据注水法则和Lagrange乘子法求得波束间功率分配算法最优解。此外,码距作为优化功率加载算法中的权重因子,有效降低了获取波束成形分集的信噪比门限。分析和实验结果表明此方案复杂度低。能有效克服相关衰落。 相似文献
8.
空间调制系统作为多输入多输出技术(Multi-input Multi-output,MIMO)的一种,优点是在减少多天线方案的复杂度和成本的同时,始终能够保证较高的数据传输速率。在每个信道使用间隙下,仅使用一根选定的天线(称为活动天线)发送数据信号,并且活动天线空间位置作为数据传输的附加维度。然而,空间调制技术的分析和设计依然面临许多挑战,编码空间调制方案就是其中一种。针对编码空间调制方案,重点论述了Trellis码、BMST码、LDPC码以及多元LDPC码等信道编码空间调制方案,并且分析了这几种方案的特点以及它们在MIMO中的应用。 相似文献
9.
Vishnu Vardhan Gudla Vinoth Babu Kumaravelu 《International Journal of Communication Systems》2020,33(6)
Spatial modulation techniques (SMTs) have emerged as promising multiple‐input and multiple‐output (MIMO) technology for fifth generation (5G) networks, which can achieve an appealing trade‐off between conflicting design objectives such as reliability, hardware cost, complexity, spectral efficiency, and energy efficiency. Most of the SMTs suffer from significant performance deterioration under correlated fading channels. In this paper, a novel spectral efficient SMT referred as enhanced redesigned spatial modulation (EReSM) is proposed, which is robust against adverse channel correlation effects. At any time instant, EReSM activates either one or two transmit antennas and employs a robust bits to antenna index mapping that ensures the selection of antenna subsets with maximum spatial separation to mitigate the effect of spatial correlation. EReSM also exploits phase rotation of transmitted symbols as an additional dimension to convey an extra information bit. The rotation angles used for bit mapping are optimized for various modulation schemes to maximize the minimum euclidean distance between the symbols. To analyze the performance, analytical upper bound expression for average bit error probability (ABEP) is derived for both uncorrelated and spatially correlated channel conditions. Monte Carlo simulation results substantiate the accuracy of the analytical results and also demonstrate that the proposed EReSM outperform conventional redesigned spatial modulation (ReSM) by at least 4 dB. 相似文献
10.
In this paper, error performance bounds are derived for 8-PSK trellis coded modulation (TCM) over Gaussian and fading channels in the presence of phase noise. Coherent demodulation combined with both phase-locked loop (PLL) and transparent tone in band technique (TTIB) for phase recovery is assumed. The analysis is then applied to a number of Ungerboeck 8-PSK trellis codes and the results for the bit error rate (BER) performance, obtained both analytically and by Monte Carlo simulation, are presented. The derived bounds can be directly extended to any M-PSK trellis code 相似文献
11.
12.
Combining PSA fading estimation techniques for TCM and diversity reception in Rician fading channels
M. H. Ng S. W. Cheung 《International Journal of Satellite Communications and Networking》2002,20(1):63-78
In this paper, a novel pilot‐symbol‐aided (PSA) technique is proposed for fading estimation in the land mobile satellite fading channels. The proposed technique combines the fading estimates obtained from a bandwidth‐efficient technique and a conventional technique according to the signal‐to‐noise ratios (SNRs) of the fading estimates. To enhance the transmission quality, trellis‐coded modulation (TCM) and diversity reception are employed in the system, and the combined estimates are subsequently used to correct the channel fading effects, to weight the signals from different diversity branches, and to provide channel state information to the Viterbi decoder. Monte Carlo computer simulation has been used to study the bit‐error‐rate (BER) performance of the proposed technique on trellis‐coded 16‐ary quadrature amplitude modulation in the frequency non‐selective Rician fading channels. Results have shown that the proposed PSA technique requires a very low bandwidth redundancy to provide satisfactory BER performance at low SNRs, and thus is suitable for use with TCM and diversity reception to achieve both bandwidth and power‐efficient transmission. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
13.
A systematic way of designing efficient trellis coded modulation (TCM) is presented. Design is based on the concept of trellis partitioning and newly defined branch distances. A lower bound on free Euclidean distance is given.<> 相似文献
14.
15.
Zhenyu Sun Tjeng Thiang Tjhung 《Wireless Communications, IEEE Transactions on》2007,6(7):2374-2378
Proper partitioning of a unitary space-time (UST) signal set is essential for the optimal design of trellis coded unitary space-time modulation (TC-USTM). The unique properties of these UST signals have necessitated a different partitioning methodology from that of the conventional two dimensional constellations. In this letter, we propose a systematic set partitioning through a novel subset-pairing strategy, for an arbitrary UST signal set. This approach leads to a geometrically congruent partitioning, i.e., subsets of the same size (order) have identical intra-distance profiles. Based on this partitioning, the resulting TC-USTM can achieve a minimum bit error probability. 相似文献
16.
Segun Oladoyinbo Narushan Pillay Hongjun Xu 《International Journal of Communication Systems》2019,32(6)
Single‐symbol generalized spatial modulation (GSM) improves upon the limitation of spatial modulation (SM) by reducing the number of required transmit antennas to achieve high data rates. In this paper, we investigate the application of media‐based modulation (MBM) based on radio frequency mirrors to single‐symbol GSM, with the aim of improving error performance. The theoretical average bit error probability of the proposed scheme is derived, employing a lower bound approach and used to validate the Monte Carlo simulation results. Finally, the effect of optimal and suboptimal mirror activation pattern selection employing Euclidean distance and channel amplitude coupled with antenna correlation is investigated for the proposed media‐based single‐symbol GSM system. The Monte Carlo simulation results obtained demonstrate a significant improvement over the conventional SM, GSM, and media‐based SM (MB‐SM) schemes in terms of error performance and spectral efficiency. 相似文献
17.
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. 相似文献
18.
Duckdong Hwang Ashish Pandharipande Hyeongwoon Park 《Communications Letters, IEEE》2006,10(6):447-449
Single carrier (SC) block transmission with frequency domain equalization (FDE) in multi-path fading channels is considered. It is shown that uncoded SC-FDE is resistant to fading even though the multi-path diversity cannot be harnessed. We propose simple schemes based on concatenations of trellis coded modulation (TCM) and interleaving for single and multiple transmit antennas to improve the coding gain, which also exploit spatial diversity in the multi antenna case. 相似文献
19.
Coded modulation has had a very significant impact on the communications scene in the decade or so since its introduction, finding practical applications from voice-band modems for telephone lines to deep-space communications. The paper introduces the principles of coded modulation and describes the two main schemes: block coded modulation (BCM) and trellis coded modulation (TCM). In particular it considers the argument between the proponents of BCM and TCM, and points out some pitfalls in the use of performance measures such as asymptotic coding gain for these schemes. It concludes that in terms of performance versus decoder complexity the schemes seem to be quite close, and the choice of the system designer may be determined by other factors 相似文献
20.
G. Ungerboeck's (1982) design rules for a class of bandlimited codes called trellis codes are reviewed. His design of the trellis is based on a set partitioning of the signal constellation, and he realized these trellis codes by a convolutional encoder followed by a mapping rule from the coder output to modulation symbols. R. Calderbank and J.E. Mazo (1984) showed how to realize trellis codes for one-dimensional signal sets in a single-step, easily derived, nonlinear transformation with memory on a sliding block of source symbols. The design rules that give a signal (state) specification in a trellis that yields the Calderbank-Mazo transformation with the smallest number of terms are presented. This gives a minimal transmitter complexity design. It is shown how to realize the Ungerboeck from the Calderbank-Mazo form, and as a result a step-by-step, search-free design procedure for trellis codes is presented. Two additional design rules are presented and applied to two examples by analytically designing two trellis codes. A simple procedure for converting an analytic code expression to a convolutional encoder realization is discussed. The analytic designs of a 4-D code and a 2-D code are presented 相似文献