Conventional space-time trellis code cannot be directly applied to the intensity modulation/direct detection atmospheric optical transmission systems due to the complex and negative signal problem. An asymmetrically c...
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ISBN:
(数字)9781510627710
ISBN:
(纸本)9781510627710
Conventional space-time trellis code cannot be directly applied to the intensity modulation/direct detection atmospheric optical transmission systems due to the complex and negative signal problem. An asymmetrically clipped space-time trellis code scheme is proposed, which combines the Hermitian symmetry of the inverse fast Fourier transform and the N/4 points to N points signal mapping to make the processed bipolar signal sequence satisfies the odd harmonic symmetry. The conversion of complex signal to positive real signal can then be achieved by clipping the bipolar signal sequence. Monte Carlo method is utilized to verify the feasibility of the proposed scheme. The results show that the proposed method can effectively resist the atmosphere scintillation.
In this paper we present a new visualisation approach in the effort of improving the evaluation strategy of space-time trellis code (STTC) generator matrix G. To our knowledge, although visualisation is widely used to...
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ISBN:
(纸本)9780769544762
In this paper we present a new visualisation approach in the effort of improving the evaluation strategy of space-time trellis code (STTC) generator matrix G. To our knowledge, although visualisation is widely used to handle a variety of problems, it has never been employed specifically to solve complexity problems that are related to generator matrix G evaluation. Most approaches are either mathematically or algorithmically inclined. As such, they tend to offer a series of refinement that enhances the current available method, but do not provide fresh insight on the problem at hand. By comparing it with the enhancement strategy that was discovered via the normal approach (i.e., by analysing algorithm) it was discovered that visualisation had inspired an entirely different pruning technique that outperformed the common approach by 20%.
In this paper, the authors propose a system where a number of cooperating mobile nodes transmit information to a common destination node. Each cooperating node has a set of decoders to detect the information of other ...
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In this paper, the authors propose a system where a number of cooperating mobile nodes transmit information to a common destination node. Each cooperating node has a set of decoders to detect the information of other nodes and a set of encoders to further encode the decoded information as well as its own information using multilevel space-timetrellis coding (MLSTTC) scheme. The coded information is mapped using multi-resolution modulation partitioning to M-ary quadrature amplitude modulation constellation. The mapped symbols are weighted based on the availale channel state information at transmitting nodes. The weighting of transmitting symbols provides beamforming resulting in receive signal-to-noise ratio gain. The weighted symbols are sent to destination node through two transmit antennas. If the information of other nodes has been correctly decoded at the cooperating node, then the destination node receives the information of each node as many times as there are number of transmitting nodes, thus achieving full diversity order. A multistage Viterbi decoder is used at the destination node to extract information of each mobile node. The results indicate that the performance of proposed cooperative MLSTTC system is superior to non-cooperative MLSTTC system. Copyright (C) 2016 John Wiley & Sons, Ltd.
Several multilevel space-timetrellis coding (MLSTTC) techniques have been investigated in the past few years to attain the benefits of spectral efficiency, coding gain and diversity gain. However, these techniques re...
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Several multilevel space-timetrellis coding (MLSTTC) techniques have been investigated in the past few years to attain the benefits of spectral efficiency, coding gain and diversity gain. However, these techniques require multiple transmit antennas for their operation and cannot be used for mobile nodes with size, cost or hardware constraint. This study proposes a cooperative transmission technique for single-antenna mobile nodes using novel multilevel pseudo space-timetrellis coding (MLPSTTC). Each mobile node behave as a cooperating node and decodes the information transmitted by other mobile nodes to the common destination node. The self-information of a cooperating node and decoded information of other nodes is further encoded using multilevel coding scheme with pseudo space-time trellis codes as component codes. The resultant MLPSTTC symbols generated at each cooperating node are transmitted to the common destination node through independent fading channels. Thus, the destination node receives multiple copies of information of each mobile node. The received coded signal at the destination node is passed through a multistage Viterbi decoder to detect the information of each mobile node. The performance of proposed cooperative multilevel pseudo space-timetrellis coding technique is superior to most of the existing MLSTTC techniques.
It has been shown that multilevel space-time trellis codes (MLSTTCs) designed by combining multilevel coding (MLC) with space-time trellis codes (STTCs) can provide improvement in diversity gain and coding gain of the...
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It has been shown that multilevel space-time trellis codes (MLSTTCs) designed by combining multilevel coding (MLC) with space-time trellis codes (STTCs) can provide improvement in diversity gain and coding gain of the STTCs. MLSTTCs assume perfect channel state information (CSI) at receiver and no knowledge of CSI at transmitter. Weighted multilevel space-time trellis codes (WMLSTTCs), designed by combining MLSTTCs and perfect CSI at transmitter are capable of providing improvement in coding gain of MLSTTCs. In this paper, we present improvement in performance of MLSTTCs by using channel feedback information from the receiver for adaptive selection of generator sequences. The selected generator sequences are used for encoding the component STTCs. The receiver compares current channel profile at receiver with a set of predetermined channel profiles, and sends an index of a predefined channel profile closest to the current channel profile to the transmitter. The transmitter selects a code set that matches best with the current channel profile at receiver using the index. The selected code set having different sets of generator sequences is used by STTC encoders to generate dynamic space-time trellis codes (DSTTCs). The DSTTCs act as component codes in multilevel coding for generating new codes henceforth referred to as multilevel dynamic space-time trellis codes (MLDSTTCs). Analysis and simulation results show that MLDSTTCs provide improvement in performance over MLSTTCs.
Multiple antenna transmission methods are currently being developed all around the world for evolving 3G wireless standards. space-time trellis code (STTC) has been proven to use transmit diversity efficiently. It eff...
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Multiple antenna transmission methods are currently being developed all around the world for evolving 3G wireless standards. space-time trellis code (STTC) has been proven to use transmit diversity efficiently. It effectively exploits the effects of multipath fading to increase the information capacity of the multiple antenna transmission systems. STTC is a channel coding technique that maximises the 'distance' between different symbol matrices such that the probability of transmission errors are decreased when transmitting redundant symbol or in other words, to maximise the minimum determinant. Maximising the minimum determinant is equivalent to obtaining optimal generator matrix G. Instead of using state diagrams, optimal generator matrix G discussed in this paper is obtained using an improved algorithm which is based on Lisya tree structure. Optimal generator matrix G in this paper has a minimum determinant of 48 which is the highest coding gain obtained so far. (C) 2011 Elsevier Masson SAS. All rights reserved.
space-time trellis code (STTC) has been widely applied to coded multiple-input multiple-output (MIMO) systems because of its gains in coding and diversity;however, its great decoding complexity makes it less promising...
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space-time trellis code (STTC) has been widely applied to coded multiple-input multiple-output (MIMO) systems because of its gains in coding and diversity;however, its great decoding complexity makes it less promising in chip realization compared to the space-time block code (STBC). The complexity of STTC decoding lies in the branch metric calculation in the Viterbi algorithm and increases significantly along with the number of antennas and the modulation order. Consequently, a low-complexity algorithm to mitigate the computational burden is proposed. The results show that more than 70%, 78%, and 83% of the computational complexity is reduced for 2 x 2, 3 x 3, and 4 x 4 MIMO configurations, respectively. Based on the proposed algorithm, a reconfigurable MISO STTC Viterbi decoder is designed and implemented using 0.18 mu m 1P6M CMOS technology. The decoder achieves 11.14 Mbps, 8.36 Mbps, and 5.75 Mbps for 4-PSK, 8-PSK, and 16-QAM modulations, respectively.
Using several high rate recursive convolutional codes as the basic element and the trace criteria as the designing principle, a new kind of recursive space-time trellis code with more flexible and higher data rate is ...
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Using several high rate recursive convolutional codes as the basic element and the trace criteria as the designing principle, a new kind of recursive space-time trellis code with more flexible and higher data rate is presented for the serially concatenated space-timecode. When 2(b)-ary modulation and N transmit antennas are used, the data rate of the new code can be arranged from b bps/Hz to Nb-1bps/Hz by modifying the number of recursive convolutional codes and the data rate of each code.
In multiple input and multiple output (MIMO) system, the channel code is very important and complex compare single antenna system. space-timecodes (STC) were proposed to solve the problem. In space-timecodes family ...
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ISBN:
(纸本)9780769539010
In multiple input and multiple output (MIMO) system, the channel code is very important and complex compare single antenna system. space-timecodes (STC) were proposed to solve the problem. In space-timecodes family the space-time block code and space-time trellis code are applied in many cases. In this paper we proposed the maximum likelihood detector used in space-time trellis codes system, and compare the difference between these two kinds of codes under maximum likelihood sequence estimator, get which situation is better to these two kinds of STC.
This paper proposes improved space-time multiple TCM (ST-MTCM) codes via a systematic expansion of space-time block code (STBC) for two transmit antennas. Starting from the orthogonal STBC, the STBC set is expanded in...
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This paper proposes improved space-time multiple TCM (ST-MTCM) codes via a systematic expansion of space-time block code (STBC) for two transmit antennas. Starting from the orthogonal STBC, the STBC set is expanded into super-orthogonal STBC, and further expanded up to spatial multiplexing in the case of BPSK and QPSK constellations. Exploiting the expanded set of STBCs as the number of states increase, improved full diversity ST-MTCM codes can be designed by increasing the coding gain and Euclidean distance of the pairwise errors.
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