Rateless codes such as lt codes have become more and more popular due to their abilities to handle varying channel conditions without much feedback. However, rateless codes have the drawback of unable to provide inter...
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ISBN:
(纸本)9781424456383
Rateless codes such as lt codes have become more and more popular due to their abilities to handle varying channel conditions without much feedback. However, rateless codes have the drawback of unable to provide intermediate outputs when delivering layer-coded media content. Although some methods have been proposed to produce intermediate outputs based on adjusting the distribution of lt codes, they are typically content-dependent and unable to guarantee that a more important layer can always be decoded before the decoding of a less important layer. In this paper, we propose a simple joint unequal loss protection (ULP) and lt coding (ULP-lt) scheme for layered media delivery, where different numbers of FEC are allocated to different layers to guarantee the priority and lt codes are used to deal with varying channel conditions. Simulation results show that with a small amount of overhead allocated to ULP, the ULP-lt scheme can produce good intermediate performance while still enjoying the nice features provided by lt codes.
In this paper, we propose a distributed rateless coding (DRC) scheme for a two-user cooperative system. In DRC, the overall transmission is divided into two phases, a broadcast phase and a cooperation phase. In the br...
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ISBN:
(纸本)9781467325790
In this paper, we propose a distributed rateless coding (DRC) scheme for a two-user cooperative system. In DRC, the overall transmission is divided into two phases, a broadcast phase and a cooperation phase. In the broadcast phase, each user keeps transmitting its rateless coded symbols to the other user and the destination until its message has been successfully decoded by the destination or the other user. In the cooperation phase, each user encodes both users' messages by using a rateless code and transmits them to the destination. A linear programming optimization problem is then formulated to find the optimal degree distribution for the proposed distributed rateless code. The performance of the proposed code is analyzed and validated by simulations.
In view of characteristics of channel parameters changing with time and space of underwater acoustic channel, a rateless transmission scheme for adaptive transmission over underwater acoustic channels is studied in th...
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ISBN:
(纸本)9789811365041;9789811365034
In view of characteristics of channel parameters changing with time and space of underwater acoustic channel, a rateless transmission scheme for adaptive transmission over underwater acoustic channels is studied in this paper. The scheme utilizes the characteristics of lt coding without fixed coding rate, and the communication efficiency is further improved through single-carrier frequency-domain equalization. Simulation results show that the scheme we proposed can effectively reduce the computational complexity compared to the rateless coding system under classical time-domain equalization. With achieving the same reliable information transmission in the same underwater acoustic channel, the redundancy required by the proposed scheme is about 1/3 of the classical retransmission method, which improves the efficiency of information transmission.
To increase bandwidth efficiency and adapt to the bandwidths of different underwater acoustic channels (UAC), a joint blind frequency-domain equalization (BFE) and rateless decoding approach for underwater acoustic co...
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To increase bandwidth efficiency and adapt to the bandwidths of different underwater acoustic channels (UAC), a joint blind frequency-domain equalization (BFE) and rateless decoding approach for underwater acoustic communication is proposed. Considering the complexity and improving the equalization perfor-mance, a variable frequency-domain tap-length linear BFE (VFTL-LBFE) is firstly proposed. In contrast to the existing approaches, the VFTL-LBFE can dynamically adjust the frequency-domain tap-length accord-ing to the specific UAC. Then, to increase the bandwidth efficiency and better utilize the different band-widths, a joint VFTL-BFE and rateless decoding (JVFTL-BFE-RD) approach is proposed. To process the feedback soft information from the rateless decoder, the LBFE is revised to decision feedback structure. In the process of obtaining feedback soft information from rateless decoding, unlike the existing approaches, the proposed approach does not need to know the noise variance. Therefore, an iterative loop is formed, through exchanging log-likelihood information between the BFE and the rateless decoder, the detection performance can be significantly improved by the iterative process, as a result, the communi-cation efficiency can be further improved. The simulation results verify the practicability and show that the proposed method has superiorities over the existing approaches. (c) 2021 Elsevier ltd. All rights reserved.
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