Image and video transmission is highly expected to proliferate with the wide spread of Wi-Fi devices and the introduction of multiple-input multiple-output (MIMO) systems. This paper proposes a novel precoder for vide...
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ISBN:
(纸本)9781509021758
Image and video transmission is highly expected to proliferate with the wide spread of Wi-Fi devices and the introduction of multiple-input multiple-output (MIMO) systems. This paper proposes a novel precoder for video transmission in overloaded MIMO systems, which is based on an eigen-beam space division multiplexing (E-SDM) technique. This paper also proposes a low complexity postcoder, which detects some of data symbols by a linear approach and the others by a prevoting vector cancellation (PVC) approach. It is shown from simulation results that the proposed precoder and postcoder achieve 40 dB in peak signal-to-noise ratio while reducing the computational complexity by over 61% compared to the conventional PVC-based detection when received signal-to-noise ratio is higher than 10 dB.
The secrecy performance of a source-channel model is studied in the context of lossy source compression over a noisy broadcast channel. The source is causally revealed to the eavesdropper during decoding. The fidelity...
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ISBN:
(纸本)9781467377041
The secrecy performance of a source-channel model is studied in the context of lossy source compression over a noisy broadcast channel. The source is causally revealed to the eavesdropper during decoding. The fidelity of the transmission to the legitimate receiver and the secrecy performance at the eavesdropper are both measured by a distortion metric. Two achievability schemes using the technique of hybrid coding are analyzed and compared with an operationally separate sourcechannelcoding scheme. A numerical example is provided and the comparison results show that the hybrid coding schemes outperform the operationally separate scheme.
We consider discrete-time all-analog-processing joint source-channel coding, using non-linear spiral-like curves. We assume a Rayleigh channel, where the receiver may employ or not multiple antennas. Maximum Likelihoo...
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ISBN:
(纸本)9781457705380
We consider discrete-time all-analog-processing joint source-channel coding, using non-linear spiral-like curves. We assume a Rayleigh channel, where the receiver may employ or not multiple antennas. Maximum Likelihood (ML) and Minimum Mean Square Error (MMSE) detection are considered. Our results show that MMSE performs much better than ML in high CSNR in single-antenna wireless systems, while diversity combining is able to significantly reduce such performance gap, therefore making the low complexity ML decoding very attractive in the case of multiple receive antennas.
Because of unavoidable wireless packet losses and inapplicability of retransmission-based schemes due to the well-known negative acknowledgment implosion problem, providing high quality video multicast over wireless w...
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Because of unavoidable wireless packet losses and inapplicability of retransmission-based schemes due to the well-known negative acknowledgment implosion problem, providing high quality video multicast over wireless wide area networks (WWAN) remains difficult. Traditional jointsource/channelcoding (JSCC) schemes for video multicast target a chosen nth-percentile WWAN user. Users with poorer reception than nthpercentile user (poor users) suffer substantial channel losses, while users with better reception (rich users) have more channelcoding than necessary, resulting in sub-optimal video quality. In this paper, we recast the WWAN JSCC problem in a new setting called cooperative peer-to-peer repair (CPR), where users have both WWAN and wireless local area network (WLAN) interfaces and use the latter to exchange received WWAN packets locally. Given CPR can mitigate some WWAN losses via cooperative peer exchanges, a CPR-aware JSCC scheme can now allocate more bits to sourcecoding to minimize source quantization noise without suffering more packet losses, leading to smaller overall visual distortion. Through CPR, this quality improvement is in fact reaped by all peers in the collective, not just a targeted nth-percentile user. To efficiently implement both WWAN forward error correction and WLAN CPR repairs, we propose to use network coding for this dual purpose to reduce decoding complexity and maximize packet recovery at the peers. We show that a CPR-aware JSCC scheme dramatically improves video quality: by up to 8.7 dB in peak signal-to-noise ratio for the entire peer group over JSCC scheme without CPR, and by up to 6.0 dB over a CPR-ignorant JSCC scheme with CPR.
Limitations on memory and resources of communications systems require powerful data compression methods. Decompression of compressed data stream is very sensitive to errors which arise during transmission over noisy c...
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Limitations on memory and resources of communications systems require powerful data compression methods. Decompression of compressed data stream is very sensitive to errors which arise during transmission over noisy channels, therefore error correction coding is also required. One of the solutions to this problem is the application of jointsource and channelcoding. This paper contains a description of methods of joint source-channel coding based on the popular data compression algorithms LZ' 77 and LZSS. These methods are capable of introducing some error resiliency into compressed stream of data without degradation of the compression ratio. We analyze jointsource and channelcoding algorithms based on these compression methods and present their novel extensions. We also present some simulation results showing usefulness and achievable quality of the analyzed algorithms.
Motivated by error correction coding in multimedia applications, we study the problem of broadcasting a single common source to multiple receivers over heterogeneous erasure channels. Each receiver is required to part...
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Motivated by error correction coding in multimedia applications, we study the problem of broadcasting a single common source to multiple receivers over heterogeneous erasure channels. Each receiver is required to partially reconstruct the source sequence by decoding a certain fraction of the source symbols. We propose a coding scheme that requires only off-the-shelf erasure codes and can be easily adapted as users join and leave the network. Our scheme involves splitting the source sequence into multiple segments and applying a systematic erasure code to each such segment. We formulate the problem of minimizing the transmission latency at the server as a linear programming problem and explicitly characterize an optimal choice for the code rates and segment sizes. Through numerical comparisons, we demonstrate that our proposed scheme outperforms both separation-based coding schemes and degree-optimized rateless codes and performs close to a natural outer (lower) bound in certain cases. We further study individual user decoding delays for various orderings of segments in our scheme. We provide closed-form expressions for each individual user's excess latency when parity checks are successively transmitted in both increasing order and decreasing order of their segment's coded rate and also qualitatively discuss the merits of each order.
This paper proposes a joint source-channel coding (JSCC) technique that well utilizes multi-dimensional (MD) source correlation using MD single parity check codes (MD-SPCCs). The source is assumed to be described by t...
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This paper proposes a joint source-channel coding (JSCC) technique that well utilizes multi-dimensional (MD) source correlation using MD single parity check codes (MD-SPCCs). The source is assumed to be described by the coupling of multiple first-order binary Markov processes. The knowledge about the source correlation is utilized in the channel decoding process where each component decoder utilizes a single dimension correlation of the MD source. To enhance performance and reduce the error floor, a rate-1 recursive systematic convolutional code is serially concatenated to the MD-SPCC via a random interleaver. Two decoding techniques are proposed for each component decoder, and the selection of the decoding technique depends on the strength of the source correlation, which may further enhance the performance of the proposed JSCC technique. Simulation results reveal that a significant performance gain can be achieved by exploiting the MD source correlation with the proposed JSCC technique compared with the case in which the source correlation is not utilized;more significant gains can be achieved with stronger source correlation, and with a larger dimensionality source correlation as well.
This paper extends the well-known sourcecoding problem of multiple descriptions, in its general and basic setting, to analog source-channelcoding scenarios. Encoding-decoding functions that optimally map between the...
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ISBN:
(纸本)9781479999880
This paper extends the well-known sourcecoding problem of multiple descriptions, in its general and basic setting, to analog source-channelcoding scenarios. Encoding-decoding functions that optimally map between the (possibly continuous valued) source and the channel spaces are numerically derived. The main technical tool is a non-convex optimization method, namely, deterministic annealing, which has recently been successfully used in other mapping optimization problems. The obtained functions exhibit several interesting structural properties, map multiple source intervals to the same interval in the channel space, and consistently outperform the known competing mapping techniques.
We study the transmission of a set of correlated sources (U1,...,UK) over a Gaussian multiple access relay channel with time asynchronism between the encoders. We assume that the maximum possible offset d(max)(n) betw...
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We study the transmission of a set of correlated sources (U1,...,UK) over a Gaussian multiple access relay channel with time asynchronism between the encoders. We assume that the maximum possible offset d(max)(n) between the transmitters grows without bound as the block length n ->infinity, while the relative ratio d(max)(n)/n of the maximum possible offset to the block length asymptotically vanishes. For such a joint source-channel coding problem and under specific gain conditions, we derive necessary and sufficient conditions for reliable communications and show that separate source and channelcoding achieves optimal performance. In particular, we first derive a general outer bound on the source entropy content for all channel gains as our main result. Then, using Slepian-Wolf sourcecoding combined with the channelcoding scheme on top of block Markov coding, we show that the thus achieved inner bound matches the outer bound. As a corollary, we also address the problem of sending a pair of correlated sources over a two-user interference channel in the same context.
A low-latency, parameter modulation-estimation feedback protocol for wide-band channels is introduced for both pure line-of-sight and more general fading channels with several degrees of freedom. One round of the prot...
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A low-latency, parameter modulation-estimation feedback protocol for wide-band channels is introduced for both pure line-of-sight and more general fading channels with several degrees of freedom. One round of the protocol consists of a data phase and a control phase and uses noncoherent detection. The asymptotic optimality in energy efficiency of the protocol is analyzed and an upper bound on the distortion level is derived for two rounds. The proposed scheme, as well as known one-way schemes, are compared with classical and very recent lower bounds. Both the lower bounds and performance evaluation of the feedback protocol are extended to a multichannel fading model. The improvement of the feedback protocol over one-shot transmission is shown to be very significant on both line-of-sight and fading channels.
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