A joint source-channel coding problem that combines the efficient compression of discrete memoryless sources with their reliable communication over memoryless channels via binary prefix-free variable-length error-corr...
详细信息
A joint source-channel coding problem that combines the efficient compression of discrete memoryless sources with their reliable communication over memoryless channels via binary prefix-free variable-length error-correcting codes (VLECs) is considered. Under a fixed free distance constraint, a priority-first search algorithm is devised for finding an optimal VLEC with minimal average codeword length. Two variations of the priority-first-search-based code construction algorithm are also provided. The first one improves the resilience of the developed codes against channel noise by additionally considering a performance parameter B-dfree without sacrificing optimality in average codeword length. In the second variation, to accommodate a large free distance constraint as well as a large source alphabet such as the 26-symbol English data source, the VLEC construction algorithm is modified with the objective of significantly reducing its search complexity while still yielding near-optimal codes. A low-complexity sequence maximum a posteriori (MAP) decoder for all VLECs (including our constructed optimal code) is then proposed under the premise that the receiver knows the number of codewords being transmitted. Simulations show that the realized optimal and suboptimal VLECs compare favorably with existing codes in the literature in terms of coding efficiency, search complexity and error rate performance.
Reliable transmission of a discrete memoryless source to multiple destinations over a relay network is considered. Motivated by sensor network applications, it is assumed that the relays and the destinations all have ...
详细信息
Reliable transmission of a discrete memoryless source to multiple destinations over a relay network is considered. Motivated by sensor network applications, it is assumed that the relays and the destinations all have access to side information correlated with the underlying source signal. jointsource-channel cooperative transmission is studied in which the terminals in the network help the transmission of the source signal to the destinations by using their overheard signals, as in the classical channel cooperation scenario, as well as the available correlated side information. Decode-and-forward-based cooperative transmission is studied in a network of multiple relay terminals and two different achievability schemes are proposed: 1) a regular encoding and sliding-window decoding scheme without explicit source binning at the encoder;and 2) a semiregular encoding and backward decoding scheme with binning based on the side information statistics. It is shown that both of these schemes lead to the same source-channel code rate, which is shown to be the source-channel capacity in the case of 1) a physically degraded relay network with a single destination in which the side information signals are degraded in the same order as the channel;and 2) a relay network with multiple destinations, in which all the terminals want to reconstruct the source reliably, while at most one of them can act as a relay.
The multiuser communication channel, in which multiple users exchange information with the help of a relay terminal, termed the multiway relay channel (mRC), is introduced. In this model, multiple interfering clusters...
详细信息
The multiuser communication channel, in which multiple users exchange information with the help of a relay terminal, termed the multiway relay channel (mRC), is introduced. In this model, multiple interfering clusters of users communicate simultaneously, such that the users within the same cluster wish to exchange messages among themselves, i.e., each user multicasts its message to all the other users in its own cluster. It is assumed that the users cannot receive each other's signals directly. Hence, the relay terminal in this model is the enabler of communication. In particular, restricted encoders are considered, such that the encoding function of each user depends only on its own message and the received signal is used only for decoding the messages of the other users in the cluster. Achievable rate regions and an outer bound are characterized for the Gaussian mRC, and their comparison is presented in terms of the exchange rate, the symmetric rate point in the capacity region in a symmetric Gaussian mRC scenario. It is shown that the compress-and-forward (CF) protocol achieves exchange rates within a constant bit offset of the optimal exchange rate, independent of the power constraints of the terminals in the network. A finite bit gap between the exchange rates achieved by the CF and the amplify-and-forward protocols is also shown. The two special cases of the mRC, the full data exchange model, in which every user wants to receive messages of all other users, and the pairwise data exchange model which consists of multiple two-way relay channels, are investigated in detail. In particular for the pairwise data exchange model, in addition to the proposed random coding-based achievable schemes, a nested lattice coding-based scheme is also presented and is shown to achieve exchange rates within a constant bit gap of the exchange capacity.
In this paper we investigate an optimal solution for adaptive H.264/SVC video transmission over Multiple-Input Multiple-Output (MIMO) channels. We first write the end-to-end distortion of the H.264/SVC video transmiss...
详细信息
In this paper we investigate an optimal solution for adaptive H.264/SVC video transmission over Multiple-Input Multiple-Output (MIMO) channels. We first write the end-to-end distortion of the H.264/SVC video transmission over a diagonal MIMO channel. The total distortion is expressed following three physical layer parameters: power allocation, modulation spectral efficiency and Error Code Correction (ECC) code rate. Minimizing the total distortion is considered as an optimization problem containing both discrete and continuous variables. We use the Lagrangian method associated with Karush-Kuhn and Tucker conditions to find out the optimal continuous physical layer parameters. Concerting the discrete modulation spectral efficiency and ECC code rate, we exploit information of the MIMO system to remove all suboptimal configurations. Therefore, the optimal power allocation is computed only for a reduced number of discrete configurations. The performance of the proposed solution is evaluated over both statistical and realistic MIMO channels. Results show that the proposed solution performs an optimal resource allocation to achieve the best QoS regardless the channel conditions. (c) 2013 Elsevier Inc. All rights reserved.
Reliable transmission of a pair of arbitrarily correlated sources over a discrete memoryless cognitive radio channel is studied. We derive a sufficient condition for lossless transmission of such communication scenari...
详细信息
Reliable transmission of a pair of arbitrarily correlated sources over a discrete memoryless cognitive radio channel is studied. We derive a sufficient condition for lossless transmission of such communication scenario using superposition coding, correlation preserving technique, random source partition, a binning scheme and joint typicality decoding. This sufficient condition reduces to the known rate regions for interference channels with independent, specially correlated and arbitrarily correlated sources.
This paper shows the strong converse and the dispersion of memoryless channels with cost constraints. The analysis is based on a new non-asymptotic converse bound expressed in terms of the distribution of a random var...
详细信息
ISBN:
(纸本)9781479904464
This paper shows the strong converse and the dispersion of memoryless channels with cost constraints. The analysis is based on a new non-asymptotic converse bound expressed in terms of the distribution of a random variable termed the b-tilted information density, which plays a role similar to that of the information density in channelcoding without cost constraints. We also analyze the fundamental limits of lossy joint-source-channelcoding over channels with cost constraints.
This paper proposes a novel joint source-channel coding (JSCC) methodology which minimizes the end-to-end distortion for the transmission over packet loss channels of scalable video encoded using SVC, the scalable ext...
详细信息
This paper proposes a novel joint source-channel coding (JSCC) methodology which minimizes the end-to-end distortion for the transmission over packet loss channels of scalable video encoded using SVC, the scalable extension of H.264/AVC. The proposed JSCC approach performs channel protection using low-density parity-check codes and relies on Lagrangian-based optimization techniques to derive the appropriate protection levels for each layer produced by the scalable source codec. Our JSCC approach for SVC can support spatial, temporal and quality scalability and can provide an optimized channel protection in any scalable setting. Experiments show that our JSCC methodology yields competitive results against state-of-the-art Lagrangian-based JSCC algorithms. Compared to the state-of-the-art, our approach significantly reduces the number of computations needed to derive the rate-distortion hulls. Moreover, the proposed approach constructs convex rate-distortion hulls for each frame, irrespective of the target rate. This allows the pre-computation of the convex rate-distortion hulls for typical packet loss channels, such that the extraction of a near-optimal JSCC allocation can be achieved on-the-fly for any target rate or packet-loss rate. We conclude that the proposed JSCC methodology provides optimized resilience against transmission errors in scalable video streaming over variable-bandwidth error-prone channels.
We investigate fundamental limits of lossy communication in a bi-directional (two-way), half-duplex relay channel, where users wish to exchange correlated Gaussian sources and do so by sending their data according to ...
详细信息
ISBN:
(纸本)9781467331227
We investigate fundamental limits of lossy communication in a bi-directional (two-way), half-duplex relay channel, where users wish to exchange correlated Gaussian sources and do so by sending their data according to a two-phase transmission protocol. We first establish a general distortion inner bound using the data processing inequality. Based on uncoded transmission schemes, separate source and channelcoding schemes, and a lattice coding scheme, we then develop several cooperative joint source-channel coding (JSCC) approaches. Furthermore, we compare the corresponding achievable distortion performances in terms of the correlation coefficient between Gaussian sources. This comparison particularly shows that separate source and channelcoding in combination with decode-and-forward relaying achieves the best distortion values of any joint source-channel coding scheme in this paper.
We study the transmission of a pair of correlated sources over a Gaussian multiple access channel with weak time asynchronism between the encoders. In particular, we assume that the maximum possible offset d(max)(n) b...
详细信息
ISBN:
(纸本)9781479904464
We study the transmission of a pair of correlated sources over a Gaussian multiple access channel with weak time asynchronism between the encoders. In particular, we assume that the maximum possible offset d(max)(n) between the transmitters grows without bound as the block length n -> infinity while the ratio d(max)(n)/n of the maximum possible offset t. o t8 he block length asymptotically vanishes. For such a joint source-channel coding problem, we derive the capacity region and also show that separate source and channelcoding achieves optimal performance. Specifically, we first derive an outer bound on the source entropy content as our main result. Then, using Slepian-Wolf sourcecoding combined with the channelcoding introduced in [1], we show that the thus achieved inner bound matches the outer bound.
This paper proposes a hybrid sender/receiver-driven error protection scheme to transmit scalable video packets over packet-lossy peer-to-peer networks. In our scheme, given an estimated system uplink capacity, a joint...
详细信息
ISBN:
(纸本)9781479923410
This paper proposes a hybrid sender/receiver-driven error protection scheme to transmit scalable video packets over packet-lossy peer-to-peer networks. In our scheme, given an estimated system uplink capacity, a joint source-channel coding (JSCC) mechanism based on receiver-driven subscriptions is proposed to minimize the visual distortion received by child-peers by subscribing to appropriate amounts of source and channelcoding packets. Because the bandwidth for inter-peer transmissions may fluctuate largely due to peer dynamics, in our method peers estimate the available system uplink capacity based on consensus propagation to avoid the fluctuating allocations of JSCC. To efficiently utilize the uplink bandwidth of peers, parent-peers use sender-driven contribution-guided peer selection to reject the low-contribution subscriptions requested from candidate child-peers. Simulation results demonstrate that our method significantly improves visual quality, compared to other state-of-the-art schemes.
暂无评论