Coding Scheme For Transmission Research Articles

Wireless Deep Video Semantic Transmission

In this paper, we design a new class of high-efficiency deep joint source-channel coding methods to achieve end-to-end video transmission over wireless channels. The proposed methods exploit nonlinear transform and conditional coding architecture to adaptively extract semantic features across video frames, and transmit semantic feature domain representations over wireless channels via deep joint source-channel coding. Our framework is collected under the name deep video semantic transmission (DVST). In particular, benefiting from the strong temporal prior provided by the feature domain context, the learned nonlinear transform function becomes temporally adaptive, resulting in a richer and more accurate entropy model guiding the transmission of current frame. Accordingly, a novel rate adaptive transmission mechanism is developed to customize deep joint source-channel coding for video sources. It learns to allocate the limited channel bandwidth within and among video frames to maximize the overall transmission performance. The whole DVST design is formulated as an optimization problem whose goal is to minimize the end-to-end transmission rate-distortion performance under perceptual quality metrics or machine vision task performance metrics. Across standard video source test sequences and various communication scenarios, experiments show that our DVST can generally surpass traditional wireless video coded transmission schemes. The proposed DVST framework can well support future semantic communications due to its video content-aware and machine vision task integration abilities.

Wireless Communication Network Security System Based on Big Data Information Transmission Technology

This paper establishes a unified perception information transmission model for the difference in the number of cognitive radio users in wireless communication network systems. The model can effectively improve the utilization of spectrum resources. At the same time, this paper introduces a cyclic delay full diversity sensing information coding transmission scheme for the security risks of wireless communication networks. We established a system simulation model to compare performance under different correlation coefficients. The study found that the total interference intensity in the cyclic delay diversity system is lower than that of the frequency division duplex and time division duplex. Its antijamming attack capability also becomes stronger accordingly.

RaptorQ codes aided secure data delivery strategy for vehicular networks

Abstract This paper deals with security issues in the presence of an eavesdropper for a vehicular scenario. The proposed secure data delivery scheme implements Fountain Codes, namely RaptorQ (RQ) codes, at the application layer (AL) to increase communication security against eavesdroppers’ attacks. For RQ coded transmission scheme, the receiver has to collect a sufficient number of coded packets to reconstruct the original source data. Secure delivery can be achieved if the legitimate user obtains enough RQ coded packets before the eavesdropper does. To satisfy this condition, it is proposed to use a road side unit (RSU) cooperation method when the eavesdropper has better channel conditions than the legitimate user to scatter the coded packets from multiple RSUs. The aim is to reduce the probability that the eavesdropper receives the sufficient number of coded packets and recover the source data before the legitimate user. An optimisation framework which jointly selects the RQ code rate at the AL and Modulation and Coding Scheme (MCS) at the physical (PHY) layer to ensure the secure data transmission by allowing the user to decode the file with a certain probability of decoding success while minimising the intercept probability at the eavesdropper is presented. To evaluate the proposed system, a realistic end-to-end system level simulator is developed. Simulation results show that the proposed scheme can provide secure and efficient data transmission over vehicular networks by significantly reducing the intercept probability at the eavesdropper.

Physical layer security over fading wiretap channels through classic coded transmissions with finite block length and discrete modulation

The chance to use existing coded transmission schemes for achieving some security at the physical layer besides reliability is of interest for many applications. In this paper, we assess the levels of physical layer security achievable by classic coding schemes over fading wiretap channels, taking into account the effects of finite block lengths and discrete modulations. In order to take these practical constraints into account, some previous works use the error rates experienced by legitimate receivers and eavesdroppers as reliability and security metrics, respectively. However, having a high error rate at the eavesdropper is a necessary but not a sufficient condition for security, thus we resort to more robust information theoretic security metrics for such a purpose. By focusing on mutual information security, we estimate the average number of attempts required by an attacker to recover the whole message in practical conditions and under outage constraints. Based on this metric, higher layer cryptographic protocols can be designed to achieve robust security built upon the physical layer. We obtain lower bounds on the wiretapper equivocation about the secret message, subject to some outage probability, and assess their tightness. We provide some examples considering classic coding and modulation techniques like extended Bose–Chaudhuri–Hocquenghem codes and convolutional codes with binary signaling.

Quasi-Cyclic Spatially Coupled LDPC Code for Broadcasting

Flexible and robust transmission schemes are required to support different coded modulation modes, receiver types and channel conditions in future broadcasting systems. However, conventional low-density parity-check (LDPC) coded schemes are usually optimized towards particular scenario, and may face the problem of performance degradation in other different scenarios. In this paper, a type of quasi-cyclic spatially coupled LDPC (QC-SC-LDPC) codes, which have been recently proven to be able to universally achieve capacity over different channels under conventional belief propagation decoding, are proposed as the forward error correcting codes for broadcasting applications. Then a QC-SC-LDPC coded transmission scheme is proposed, which is capable of showing good performance in various scenarios under practical constraints of finite coupling length, smoothing parameter, uncoupled code length and number of decoding iterations. To maintain the universal property under the above constraints, a typical construction method is developed, based on which a QC-SC-LDPC code is constructed as an example. Finally, the performance and robustness of the proposed QC-SC-LDPC coded transmission scheme are demonstrated via simulations under different yet typical coded modulation modes and channel conditions.

Rateless Coded Uplink Transmission Design for Multi-User C-RAN.

Cloud radio access network (C-RAN) is a promising technology for the Internet of Things (IoT). In C-RAN, the remote radio head (RRH) and baseband unit (BBU) in the conventional base station are separated, and each BBU is backward centralized into a virtual BBU pool. In this paper, we consider the uplink transmission for the two-user C-RAN with two RRHs under a block fading channel. A novel rateless coded transmission scheme is designed. During each transmission round, each user keeps transmitting to the RRHs using Raptor code until the BBU pool feeds back an acknowledgement (ACK). With the proposed scheme, each user does not require the instant channel state information, which greatly reduces the system overhead. We also design the quantizer at the RRHs and the iterative multi-user detector and decoder at the BBU pool, based on the belief propagation (BP) algorithm. For the Raptor code applied at each user, we optimize the corresponding output node degree profile, based on extrinsic information transfer (EXIT) analysis for the decoding process at the BBU pool. The resulted degree profiles are optimal in an average sense under all possible channel states. The simulation results show that the rateless coded transmission scheme with the optimized degree profiles outperforms the benchmark degree profile in both bit error rate and average system throughput. Moreover, the achieved performance is close to the theoretical limit.

Adaptive Rate-Compatible Non-Binary LDPC Coding Scheme for the B5G Mobile System.

This paper studies an adaptive coding scheme for B5G (beyond 5th generation) mobile system-enhanced transmission technology. Different from the existing works, the authors develop a class of rate-compatible, non-binary, low-density parity check (RC-NB-LDPC) codes, which expresses the strong connection between the algebra-based and graph-theoretic-based constructions. The constructed codes can not only express rate-compatible (RC) features, but also possess a quasi-cyclic (QC) structure that facilitates the encoding implementation. Further, in order to achieve the code rate-adaptive allocation scheme, the authors propose using the K-means++ clustering algorithm to cluster different channel environments, considering various factors that affect channel characteristics. Finally, in order to present the advantages of the adaptive coding scheme, the authors construct a coding scheme for image transmission. The numerical results demonstrate that the developed code can obtain better waterfall performance in a larger code rate range, which is more suitable for data transmission; the adaptive coding transmission scheme can obtain higher reconstructed image quality compared to the fixed code rate-coding scheme. Moreover, when considering unequal error protection (UEP), the proposed scheme can further improve the reconstructed image quality.

Joint Coding and Adaptive Image Transmission Scheme Based on DP-LDPC Codes for IoT Scenarios

For wireless image communication in the Internet of Things (IoT) scenarios, fast and low error coding and transmission mechanisms are imperative. The joint source-channel coding scheme based on the double protograph low-density parity-check (DP-LDPC) codes would be a potential candidate due to the low complexity and good error performance. However, the error floor performance of DP-LDPC codes may deteriorate for source sequences with higher source probabilities or shorter block lengths. This paper aims to improve the traditional DP-LDPC image transmission system for the IoT scenarios from the following aspects. First, a joint optimization method of finite-length DP-LDPC codes is proposed to reduce the error floor while keeping satisfactory waterfall region performance. Second, an improved rate allocation strategy based on the fuzzy logic control is adopted to further improve the transmission reliability of the proposed short block length DP-LDPC codes. This scheme may offer some new solutions for the IoT image communication. The simulation results indicate the effectiveness of the proposed methods.

Rateless Coded Multi-User Downlink Transmission in Cloud Radio Access Network

In this paper, we propose a rateless coded transmission scheme for the multi-user downlink of Cloud Radio Access Network (C-RAN). In the network, multiple users are served by a cluster of remote radio heads (RRH), which are connected to the building baseband units (BBU) pool through the fronthaul links with limited capacity. In the proposed transmission scheme, the precoder and compressor at the BBU pool, and the decoding algorithm at the users are designed. To further improve the performance of the proposed transmission scheme, we investigate the joint optimization of the precoder and the degree profiles of the rateless codes implemented at the BBU pool to maximize the sum throughput of the network. Explicitly, the optimization problem is formulated according to the extrinsic information transfer (EXIT) function analysis on the decoding process at the users. We give simulation results on the BER and throughput performance achieved by the proposed rateless coded transmission scheme, which verify the effectiveness of the joint optimization on the degree profiles and the precoder.

New beamforming and space‐time coding for two‐path successive decode and forward relaying

Successive relaying is a bandwidth-efficient scheme in cooperative networks. In this study, a novel distributed space-time coding (DSTC) transmission scheme for a two-path successive relay network is proposed that enjoys threshold-based selection relaying protocol. A new beamforming method is also employed alongside the proposed DSTC transmission scheme. Three scenarios are considered in this study. In the first scenario, single-input–single-output (SISO) relays are considered. In the second and third scenarios, multiple-input–multiple-output (MIMO) relays are used, but in the second case a transmission scheme named as quasi-DSTC scheme alongside employing space-time coding at each relay is proposed. A closed-form expression for the end-to-end bit error rate (BER) of the system is derived and it is shown that regardless of the fading in inter-relay channel, the proposed scheme achieves full diversity order even when there are decoding errors at the relay nodes. Simulation results show a significant saving in power of about 2.5, 3, and 4 dB at BER ( 10 − 4 ) compared with other conventional methods in the case of using SISO relays, MIMO relays in the second and third scenarios, respectively.

A Low-Complexity Coded Transmission Scheme Over Finite-Buffer Relay Links

Relay transmissions play an important role in many types of communication systems. In this paper, we consider packet-level coded transmissions over lossy relay links with the finite-buffer and coding coefficients delivery cost constraints. We propose a low-complexity coding scheme where packets are encoded from sequentially formed random subsets of source packets called batches . The relay recodes only from the buffered packets belonging to the same batch to maintain the code sparsity, lowering the packet header overhead and the decoding complexity compared to the random linear network coding (RLNC). To analyze the performance, we first propose an absorbing Markov chain model to analyze the RLNC transmission over finite-buffer relay links. The finite-length analysis not only provides a lower bound on the completion time using any sparser random codes but also characterizes each individual batch’s transmission of the proposed code. Based on the analysis, another Markov chain is proposed to determine the decoding failure probability and the expected completion time of the batch coding scheme. As shown through analysis and simulations, the proposed scheme achieves higher effective end-to-end rates than RLNC when the coding coefficients delivery cost is considered and is also with much lowered decoding complexity thanks to its sparseness.

ARMA-Based Adaptive Coding Transmission Over Millimeter-Wave Channel for Integrated Satellite-Terrestrial Networks

The integrated satellite-terrestrial network can provide broadband wireless access in a wide coverage, efficient, and cost-effective manner, and is regarded as one of the most promising infrastructures for future heterogeneous network toward fifth generation. With the development of next generation of high throughput satellites (HTS), the application of the millimeter-wave (mmWave) band HTS is viewed as a vital role in the future integrated satellite-terrestrial network. Considering the rain attenuation is the dominant fading factor of the mmWave channel, we first propose a practical time-varying rain attenuation prediction model based on the autoregressive-moving-average (ARMA) model. Then, we develop an adaptive coding transmission (ACT) scheme based on the analog fountain codes combine the ARMA mmWave channel prediction model. The key parameters are selected based on a tradeoff between the decoding failure probability, block length, and overhead for our ARMA-based ACT scheme. Simulation results show that our proposed ACT scheme can effectively improve the throughput.

Physical-Layer Network Coding Based Multi-User Cooperative Relay Transmission With Multi-Antennas in Cognitive Wireless Networks

A promising way to improve the performance and guarantee the quality of service (QoS) of cognitive wireless cooperative relay networks is to jointly employ physical-layer network coding (PNC) and multi-antenna space–time block coding. This paper proposes a new multi-user transmission coding scheme, cooperative quadrature PNC (CQPNC), for cognitive wireless networks. In CQPNC scheme, two source nodes (users) first use quadrature carriers to transmit signals simultaneously, which are received and processed by a cooperative relay node using the PNC method. The processed signal is then transmitted to the destination node, which makes a combination of the signals from the direct path and relay path to obtain the information transmitted by the source node. Simulation results in difference cases of cognitive wireless networks show that the CQPNC scheme outperforms the traditional cooperation and cooperative network coding transmission schemes on the performance of anti-noise and throughput.

Interleaved coding and sequential transmission scheme for packet‐level forward error correction over burst loss channels

SummaryBurst packet loss is a common problem over wired and wireless networks and leads to a significant reduction in the performance of packet‐level forward error correction (FEC) schemes used to recover packet losses during transmission. Traditional FEC interleaving methods adopt the sequential coding‐interleaved transmission (SCIT) process to encode the FEC packets sequentially and reorder the packet transmission sequence. Consequently, the burst loss effect can be mitigated at the expense of an increased end‐to‐end delay. Alternatively, the reversed interleaving scheme, namely, interleaved coding‐sequential transmission (ICST), performs FEC coding in an interleaved manner and transmits the packets sequentially based on their generation order in the application. In this study, the analytical FEC model is constructed to evaluate the performance of the SCIT and ICST schemes. From the analysis results, it can be observed that the interleaving delay of ICST FEC is reduced by transmitting the source packets immediately as they arrive from the application. Accordingly, an Enhanced ICST scheme is further proposed to trade the saved interleaving time for a greater interleaving capacity, and the corresponding packet loss rate can be minimized under a given delay constraint. The simulation results show that the Enhanced ICST scheme achieves a lower packet loss rate and a higher peak signal‐to‐noise‐ratio than the traditional SCIT and ICST schemes for video streaming applications.

Security gap analysis of some LDPC coded transmission schemes over the flat and fast fading Gaussian wire-tap channels

It is known that the error rate can be used as a measure of reliability and security over the wire-tap channel when practical, finite length codes are used for transmission, and the security gap is an error rate based metric able to jointly treat these two aspects. In this paper, we consider several low-density parity-check (LDPC) coded transmissions, which represent the state of the art for transmissions over the wire-tap channel and we assess and compare their security gap performance. We consider two kinds of wire-tap channels: the flat and the fast fading wire-tap channels with additive white Gaussian noise. As a reference, we use the progressive edge growth (PEG) algorithm for the design of unstructured LDPC codes and compare its performance with that of four approaches for designing structured LDPC codes. We analyze both systematic and non-systematic transmissions and show that some structured code design techniques are able to achieve comparable or even better performance than the PEG algorithm over the considered channels, while taking advantage of their simpler encoding and decoding procedures.

Denoise-and-Forward Network Coding for Two-Way Relay MIMO Systems

In this paper, we propose a denoise-and-forward network coding (DNF-NC) transmission scheme for its applications in two-way relay multiple-input and multiple-output (MIMO) systems. We first consider a scenario with a single pair of source nodes, and minimum mean square error (MMSE) receiver is applied at each node. The global optimal precoding design based on the mean square error (MSE) criterion can be achieved by solving two independent convex optimization problems. To achieve a better tradeoff between performance and complexity, an alternative power optimization approach is proposed using a channel diagonalization technique. Then, we proceed to considering a more challenging bidirectional communication scenario with multiple pairs of source nodes. With intrapair coordination at the sources, we modify DNF-NC by employing a signal alignment technique to combat interpair interference. The numerical results demonstrate that the proposed DNF-NC schemes can significantly improve bit error rate (BER) performance in both two scenarios, and such performance gains can be achieved with relatively low computational complexity.

Algebraic Number Precoded OFDM Transmission for Asynchronous Cooperative Multirelay Networks

This paper proposes a space-time block coding (STBC) transmission scheme for asynchronous cooperative systems. By combination of rotated complex constellations and Hadamard transform, these constructed codes are capable of achieving full cooperative diversity with the analysis of the pairwise error probability (PEP). Due to the asynchronous characteristic of cooperative systems, orthogonal frequency division multiplexing (OFDM) technique with cyclic prefix (CP) is adopted for combating timing delays from relay nodes. The total transmit power across the entire network is fixed and appropriate power allocation can be implemented to optimize the network performance. The relay nodes do not require decoding and demodulation operation, resulting in a low complexity. Besides, there is no delay for forwarding the OFDM symbols to the destination node. At the destination node the received signals have the corresponding STBC structure on each subcarrier. In order to reduce the decoding complexity, the sphere decoder is implemented for fast data decoding. Bit error rate (BER) performance demonstrates the effectiveness of the proposed scheme.

Distributed MAC Protocol Supporting Physical-Layer Network Coding

Physical-layer network coding (PNC) is a promising approach for wireless networks. It allows nodes to transmit simultaneously. Due to the difficulties of scheduling simultaneous transmissions, existing works on PNC are based on simplified medium access control (MAC) protocols, which are not applicable to general multihop wireless networks, to the best of our knowledge. In this paper, we propose a distributed MAC protocol that supports PNC in multihop wireless networks. The proposed MAC protocol is based on the carrier sense multiple access (CSMA) strategy and can be regarded as an extension to the IEEE 802.11 MAC protocol. In the proposed protocol, each node collects information on the queue status of its neighboring nodes. When a node finds that there is an opportunity for some of its neighbors to perform PNC, it notifies its corresponding neighboring nodes and initiates the process of packet exchange using PNC, with the node itself as a relay. During the packet exchange process, the relay also works as a coordinator which coordinates the transmission of source nodes. Meanwhile, the proposed protocol is compatible with conventional network coding and conventional transmission schemes. Simulation results show that the proposed protocol is advantageous in various scenarios of wireless applications.

Noncoherent Amplitude/Phase Modulated Transmission Schemes for Rayleigh Block Fading Channels

In this paper, we investigate noncoherent transmission schemes using amplitude/phase modulation. For uncoded transmission schemes, we derive the pairwise error probability (PEP) and its high-SNR approximation for signal vectors with unequal power values using a noncoherent maximum-likelihood detector under Rayleigh block fading channels. For coded transmission schemes, we consider differential amplitude/phase modulated signals and introduce a codeword-interleaving strategy to improve the error performance. The design criteria for the signal labelling and bit interleaving are also derived via the high-SNR approximation of the PEP. At the receiver, we devise an iterative channel amplitude estimator to enhance the detection reliability. With the help of a specially-designed iterative receiving algorithm, the designed noncoherent coded scheme can provide a significant improvement, either in the error-floor or the waterfall region.

Progressive Differences Convolutional Low-Density Parity-Check Codes

We present a new family of low-density parity-check (LDPC) convolutional codes that can be designed using ordered sets of progressive differences. We study their properties and define a subset of codes in this class that have some desirable features, such as fixed minimum distance and Tanner graphs without short cycles. The design approach we propose ensures that these properties are guaranteed independently of the code rate. This makes these codes of interest in many practical applications, particularly when high rate codes are needed for saving bandwidth. We provide some examples of coded transmission schemes exploiting this new class of codes.