In order to obtain coding gain along with diversity gain,rotation code was applied to cooperative diversity employing decoded-and-forward cooperative *** from the same two symbols transmitted in conventional repetitio...
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In order to obtain coding gain along with diversity gain,rotation code was applied to cooperative diversity employing decoded-and-forward cooperative *** from the same two symbols transmitted in conventional repetition-coded scheme,two different symbols were transmitted separately in two successive timeslots in the proposed rotation-coded cooperative *** this way,constellation spread in the available two-dimensional signal space rather than on a single-dimensional line in repetition-coded scheme,which was supposed to be responsible for the additional coding *** the proposed cooperative transmission model,upper bounds for the symbol-error-rate(SER)of cooperative diversity based on repetition code and rotation code were derived *** analytical and simulated results show that cooperative diversity based on rotation code can obtain an improved coding gain(by about 2 dB)than repetition-coded scheme without the expense of power or bandwidth.
In this paper, a code-domain non-orthogonal multiple access (NOMA) scheme called "Subcarrier and Permutation Index Modulation Multiple Access" (SPIMMA) scheme is proposed over the Orthogonal Frequency Divisi...
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ISBN:
(纸本)9781665413688
In this paper, a code-domain non-orthogonal multiple access (NOMA) scheme called "Subcarrier and Permutation Index Modulation Multiple Access" (SPIMMA) scheme is proposed over the Orthogonal Frequency Division Multiplexing-Subcarrier and Permutation Index Modulation (OFDM-SPIM) architecture. The Index Modulation Multiple Access (IMMA) which applies index modulation (IM) technique is a codebook-based NOMA scheme. It uses the active subcarriers to make index indices which can carry additional bits besides the modulation bits. The proposed scheme uses the concept of IMMA and improves it by transmitting additional bits through different modes. Index bits which deliver additional information are not only produced from the active and inactive subcarriers but also from the different modes permutation. Therefore, he performance of energy efficiency (EE) and spectral efficiency (SE) are improved. The rotation code is proposed in the SPIMMA to solve the problem of inter-user interference (IUI) in contention based multiple access. Due to the diversity gain from the rotation code, the simulation results show that the bit error rate (BER) of SPIMMA is improved with rotation code. In brief, we have designed a code-domain NOMA scheme that facilitates grant free random multiple access, which also shows better SE, EE than IMMA, OFDMA, and SCMA.
This paper studies the mutual information improvement attained by rotated multidimensional (multi-D) constellations via a unitary precoder G in Rayleigh fading. At first, based on the symmetric cut-off rate of the N-D...
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This paper studies the mutual information improvement attained by rotated multidimensional (multi-D) constellations via a unitary precoder G in Rayleigh fading. At first, based on the symmetric cut-off rate of the N-D signal space, we develop a design criterion with regard to the precoder G. It is then demonstrated that the use of rotated constellations in only a reasonably low dimensional signal space can significantly increase the mutual information in high-rate regimes. Based on parameterizations of unitary matrices, we then construct good unitary precoder G in 4-D signal space using a simple optimization problem, which involves only four real variables and it is applicable to any modulation scheme. To further illustrate the potential of multi-D constellation and to show the practical use of mutual information improvement, we propose a simple yet powerful bit-interleaved coded modulation (BICM) scheme in which a (multi-D) mapping technique employed in a multi-D rotated constellation is concatenated with a short-memory high-rate convolutional code. By using extrinsic information transfer (EXIT) charts, it is shown that the proposed technique provides an exceptionally good error performance. In particular, both EXIT chart analysis and simulation results indicate that a turbo pinch-off and a bit error rate around 10(-6) happen at a signal-to-noise ratio that is well below the coded modulation and BICM capacities using traditional signal sets. For example, with code rates ranging from 2/3 to 7/8, the proposed system can operate 0.82 dB-2.93 dB lower than the BICM capacity with QPSK and Gray labeling. The mutual information gain offered by rotated constellations can be therefore utilized to design simple yet near Shannon limit systems in the high-rate regions.
The data volume of global information has grown exponentially in recent years, but the development of silicon-based memory has entered a bottleneck period. Deoxyribonucleic acid (DNA) storage is drawing attention owin...
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The data volume of global information has grown exponentially in recent years, but the development of silicon-based memory has entered a bottleneck period. Deoxyribonucleic acid (DNA) storage is drawing attention owing to its advantages of high storage density, long storage time, and easy maintenance. However, the base utilization and information density of existing DNA storage methods are insufficient. Therefore, this study proposes a rotational coding based on blocking strategy (RBS) for encoding digital information such as text and images in DNA data storage. This strategy satisfies multiple constraints and produces low error rates in synthesis and sequencing. To illustrate the superiority of the proposed strategy, it was compared and analyzed with existing strategies in terms of entropy value change, free energy size, and Hamming distance. The experimental results show that the proposed strategy has higher information storage density and better coding quality in DNA storage, so it will improve the efficiency, practicality, and stability of DNA storage.
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