Information Block Length Research Articles

Multiple CUAV-Enabled mMTC and URLLC Services: Review of Energy Efficiency and Latency Performance

Cognitive unmanned aerial vehicles (CUAVs) play a vital role in next-generation wireless networks as they assist in massive machine-type communication (mMTC) and ultra-reliable low-latency communication (URLLC) services. This study focuses on multiple CUAV-enabled networks wherein CUAVs are paired with each other. We analyze the data rate, energy efficiency, and latency of such networks by applying the finite information block length theory, wherein mMTC and URLLC information use a non-orthogonal multiple access technique. Furthermore, we formulate an optimization problem to maximize the energy efficiency of paired CUAV devices by jointly optimizing the transmission power of the mMTC and URLLC information to satisfy the latency requirement. The numerical results indicate that our proposed multiple-CUAV-enabled scheme enhances the network performance of CUAV devices in terms of energy efficiency and latency better than the existing scheme.

Data Transmission Enhancement Using Optimal Coding Technique Over In Vivo Channel for Interbody Communication.

Wireless in vivo actuators and sensors are examples of sophisticated technologies. Another breakthrough is the use of in vivo wireless medical devices, which provide scalable and cost-effective solutions for wearable device integration. In vivo wireless body area networks devices reduce surgery invasiveness and provide continuous health monitoring. Also, patient data may be collected over a long period of time. Given the large fading in in vivo channels due to the signal path going through flesh, bones, skins, and blood, channel coding is considered a solution for increasing the efficiency and overcoming inter-symbol interference in wireless communications. Simulations are performed by using 50 MHz bandwidth at Ultra-Wideband frequencies (3.10-10.60 GHz). Optimal channel coding (Turbo codes, Convolutional codes, with the help of polar codes) improves data transmission performance over the in vivo channel in this research. Moreover, the results reveal that turbo codes outperform polar and convolutional codes in terms of bit error rate. Other approaches perform similarly when the information block length is increased. The simulation in this work indicates that the in vivo channel shows less performance than the Rayleigh channel due to the dense structure of the human body (flesh, skins, blood, bones, muscles, and fat).

Analysis and Design of Analog Fountain Codes for Short Packet Communications

In this paper, we focus on the design and analysis of the Analog Fountain Code (AFC) for short packet communications. We first propose a density evolution (DE) based framework, which tracks the evolution of the probability density function of the messages exchanged between variable and check nodes of AFC in the belief propagation decoder. Using the proposed DE framework, we formulate an optimisation problem to find the optimal AFC code parameters, including the weight-set, which minimises the bit error rate at a given signal-to-noise ratio (SNR). Our results show the superiority of our AFC code design compared to existing designs of AFC in the literature and thus the validity of the proposed DE framework in the asymptotically long block length regime. We then focus on selecting the precoder to improve the performance of AFC at short block lengths. Simulation results show that lower precode rates obtain better realised rates over a wide SNR range for short information block lengths. We also discuss the complexity of the AFC decoder and propose a threshold-based decoder to reduce the complexity.

Performance comparison of channel coding schemes for 5G massive machine type communications

<p><span>Channel coding for the fifth generation (5G) mobile communication is currently facing new challenges as it needs to uphold diverse emerging applications and scenarios. Massive machine-type communication (mMTC) constitute one of the main usage scenarios in 5G systems, which promise to provide low data rate services to a large number of low power and low complexity devices. Research on efficient coding schemes for such use case is still ongoing and no decision has been made yet. Therefore, This paper compares the performance of different coding schemes, namely: tail-biting convolutional code (TBCC), low density parity check codes (LDPC), Turbo code and Polar codes, in order to select the appropriate channel coding technique for 5G-mMTC scenario. The considered codes are evaluated in terms of bit error rate (BER) and block error rate (BLER) for short information block lengths (K ≤ 256). We further investigate their Algorithmic complexity in terms of the number of basic operations. The Simulation results indicate that polar code with CRC-aided successive cancelation list decoder has better performance compared with other coding schemes for 5G-mMTC scenario.</span></p>

Rate Control for Wireless-Powered Communication Network With Reliability and Delay Constraints

We consider a two-phase Wireless-Powered Communication Network under Nakagami-m fading, where a wireless energy transfer process first powers a sensor node that then uses such energy to transmit its data in the wireless information transmission phase. We explore a fixed transmit rate scheme designed to cope with the reliability and delay constraints of the system while attaining closed-form approximations for the optimum wireless energy transfer and wireless information transmission blocklength. Then, a more-elaborate rate control strategy exploiting the readily available battery charge information is proposed and the results evidence its outstanding performance when compared with the fixed transmit rate, for which no battery charge information is available. It even reaches an average rate performance close to that of an ideal scheme requiring full Channel State Information at transmitter side. Numerical results show the positive impact of a greater number of antennas at the destination, and evidence that the greater the reliability constraints, the smaller the message sizes on average, and the smaller the optimum information blocklengths. Finally, we corroborate the appropriateness of using the asymptotic blocklength formulation as an approximation of the non-asymptotic finite blocklength results.

Forward Error Correction Using Turbo Codes for Multimedia Data

The swift growth in multimedia technology of wireless network has made it mandatory for the efficient transmission across erratic channel. The transmission of encoded video using error control techniques is grabbing a great attention, since it works over the recovery of the lost data and errors in the bit frames which occur as a result of congestion and physical channel fading. Turbo codes are attracting researchers because of their efficient performance. The Turbo code is made up of analogous concatenation of two Recursive Systematic Convolutional (RSC) coders parted by a non-uniform interleaver. For different code rate and information block lengths greater than 104, these codes are capable of achieving low Bit-error rates (BERs) at SNRs within 1dB of Shannon’s limit. Turbo codes will assist to employ Viterbi decoders. More the number of iterations, higher is the error correction capacity and hence Turbo codes act as an elucidation for obtaining large coding gains.

A Near BER-Optimal Decoding Algorithm for Convolutionally Coded Relay Channels With the Decode-and-Forward Protocol

Relay-assisted communication has been shown to be an effective technique to improve the reliability and throughput of real-world wireless communication networks. It enables single-antenna users to form a virtual antenna array without installing multiple antennas at the transmitter or the receiver. This paper re-examines the decoding problem in the convolutionally coded relay channel with the classical decode-and-forward protocol. By tackling the challenge of modeling the error propagation effect at the relay, a near BER-optimal decoding (NBOD) algorithm at the destination is derived, assuming the availability of perfect receiver channel state information. Its decoding complexity is linear in the information block length, while the exact BER-optimal decoding algorithm with a sub-exponential complexity is still unknown. The major approximation involved in the derivation of the NBOD algorithm is the pairwise error probability approximation that causes a practically insignificant degradation from the optimal BER performance. Our simulation result confirms that the proposed NBOD algorithm can perform close to the maximum likelihood performance bound on BER in the three-node one-way relay channel scenario. In addition, we have further extended the proposed algorithm for more general single-source single-destination decode-and-forward-based relay networks. Simulation results further verify that the proposed NBOD algorithm can outperform existing decoding algorithms based on maximal-ratio combining and selective decode-and-forward in various relay channel scenarios at the cost of higher complexity.

Buffer-Based Distributed LT Codes

We focus on the design of distributed Luby transform (DLT) codes for erasure networks with multiple sources and multiple relays, communicating to a single destination. The erasure-floor performance of DLT codes improves with the maximum degree of the relay-degree distribution. However, for conventional DLT codes, the maximum degree is upper-bounded by the number of sources. An additional constraint is that the sources are required to have the same information block length. We introduce a $D$-bit buffer for each source-relay link, which allows the relay to select multiple encoded bits from the same source for the relay-encoding process; thus, the number of sources no longer limits the maximum degree at the relay. Furthermore, the introduction of buffers facilitates the use of different information block sizes across sources. Based on density evolution we develop an asymptotic analytical framework for optimization of the relay-degree distribution. We further integrate techniques for unequal erasure protection into the optimization framework. The proposed codes are considered for both lossless and lossy source-relay links. Numerical examples show that there is no loss in erasure performance for transmission over lossy source-relay links as compared to lossless links. Additional delays, however, may occur. The design framework and our contributions are demonstrated by a number of illustrative examples, showing the improvements obtained by the proposed buffer-based DLT codes.

A Hybrid ARQ Scheme Based on Polar Codes

A hybrid automatic repeat request (HARQ) scheme based on a novel class of rate-compatible polar (\mbox{RCP}) codes are proposed. The RCP codes are constructed by performing punctures and repetitions on the conventional polar codes. Simulation results over binary-input additive white Gaussian noise channels (BAWGNCs) show that, using a low-complexity successive cancellation (SC) decoder, the proposed HARQ scheme performs as well as the existing schemes based on turbo codes and low-density parity-check (LDPC) codes. The proposed transmission scheme is only about 1.0-1.5dB away from the channel capacity with the information block length of 1024 bits.

Rate-Compatible Short-Length Protograph LDPC Codes

This paper produces a rate-compatible protograph LDPC code at 1k information blocklength with superior performance in both waterfall and error floor regions. The design of such codes has proved difficult in the past because the constraints imposed by structured design (protographs), rate-compatibility, as well as small block length, are not easily satisfied together. For example, as the block length decreases, the predominance of decoding threshold as the main parameter in coding design is reduced, thus complicating the search for good codes. Our rate-compatible protograph codes have rates ranging from 1/3 to 4/5 and show no error floor down to 10-6 FER.

Design of Efficiently Encodable Rate-Compatible LDPC Codes Using Vandermonde Extension Matrices

A low-complexity algorithm for the design of efficiently-encodable rate-compatible (RC) low-density parity-check (LDPC) codes by deterministically extending an irregular repeat-accumulate (IRA) is introduced. The extending structure is based on circulants shifted according a truncated Vandermonde matrix (VM) and therefore termed as "extended VM" (eVM). The novel extending algorithm is significantly less computationally complex than other known similar methods since it does not require any optimization of the extending profile or any post-construction girth conditioning. To improve the codes' properties and correcting capabilities in low code rate applications, the optimal proportions of degree-1 and degree-2 parity bits for the extended nodes are investigated and, in contrast to existing deterministic extending approaches for RC-IRA codes, an extending increment step equal to half the information block length is chosen. Various bit error rate (BER) and frame error rate (FER) have been obtained for different code rates, R, and information block length k 0 = 512 and 1024 bits considering an additive white Gaussian noise (AWGN) channel. The results have demonstrated that the proposed eVM RC-LDPC codes, despite their very simple structure and very low computational complexity, exhibit excellent performance only slightly inferior to both dedicated IRA and previously known RC-IRA codes for different data block sizes.

Rate-compatible IRA codes using quadratic congruential extension sequences and puncturing

A novel algorithm for the design of rate-compatible (RC) irregular repeat-accumulate (IRA) codes through deterministic extending based on quadratic congruential extension sequences is introduced. To maintain low-complexity, algebraic operations are used without any post-construction girth conditioning. The proposed extending algorithm is general and can be applied to any IRA mother code of information block length, k <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> , producing different sequences of code rates, R. Furthermore, a hybrid class of Deterministically Designed RC-IRA (D <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> RC-IRA) codes is obtained by combining the proposed extending algorithm with puncturing. Simulation results have shown that for k <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> = 1024 and R = 8/24, 8/23, . . . , 8/9, the proposed codes outperform equivalent deterministic coding schemes in both error rate and throughput by up to 0.62 dB and 0.6 dB, respectively.

Scaling Law of Turbo Codes over the Binary Erasure Channel

In this paper, it is shown that the bit erasure probability of turbo codes with iterative decoding in the waterfall region is nonlinearly scaled by the information blocklength. This result can be used to predict efficiently the bit erasure probability of the finite-length turbo codes over the binary erasure channel.

On the performance of turbo codes over the binary erasure channel

In this letter, we propose an estimate for the block erasure probability of turbo codes with an iterative decoding in a waterfall region, which is nonlinearly scaled by the information blocklength. This estimate can be used to predict efficiently the block erasure probability of the finite-length turbo codes over a binary erasure channel

Interleaver Design for Serially Concatenated Convolutional Codes: Theory and Application

This paper addresses the problem of interleaver design for serially concatenated convolutional codes (SCCCs) tailored to the constituent codes of the SCCC configuration. We present a theoretical framework for interleaver optimization based on a cost function closely tied to the asymptotic bit-error rate (BER) of the block code C/sub s/ resulting from proper termination of the constituent codes in the SCCC code. We define a canonical form of the interleaving engine denoted as the finite state permuter (FSP) and using its structural property, develop a systematic iterative technique for construction of interleavers. The core theoretical results focus on the asymptotic behavior of a class of cost functions and their martingale property, which is then used to develop an order recursive interleaver optimization algorithm. We address the issue of the complexity of the interleaver growth algorithm presented in the paper and demonstrate that it has polynomial complexity. Subsequently, we provide details about the application of the proposed technique and present a modification of the algorithm that employs error pattern feedback for improved performance at a reduced complexity. Sample experimental results are provided for an SCCC code of rate 1/3 and information block length 320 that achieves a minimum distance of d/sub min/=44.

On Construction of Rate-Compatible Low-Density Parity-Check Codes

In this letter, we present a framework for constructing rate-compatible low-density parity-check (LDPC) codes. The codes are linear-time encodable and are constructed from a mother code using puncturing and extending. Application of the proposed construction to a type-II hybrid automatic repeat request (ARQ) scheme with information block length k=1024 and code rates 8/19 to 8/10, using an optimized irregular mother code of rate 8/13, results in a throughput which is only about 0.7 dB away from Shannon limit. This outperforms existing similar schemes based on turbo codes and LDPC codes by up to 0.5 dB.

Bounds for finite block-length codes

A tight bound for finite block-length codes is required when developing bandwidth efficient systems, and the paper describes an information-theoretic approach for determining the bound for binary codes. It is derived on the assumption that when the entropy loss in a binary symmetric channel equates to that in a soft-decision channel, the corresponding hard and soft-decision decoders must generate the same error probability. The bound agrees well with the Gallager bound at large block lengths, and is compared to the performance of iteratively decoded product codes. The paper also describes a recursive breakdown of Shannon&apos;s sphere packing bound that permits exact numerical evaluation for information block lengths up to 103 bits. The difference between the exact solution and Shannon&apos;s approximation is given up to this block length.

Error performance for D-MAC data services

Options for error protection within the D-MAC packet format are discussed. It is proposed that the packet-type byte be encoded using frame error correction (FEC), thereby increasing the robustness of the packet. Once FEC for the packet-type byte has been allocated, the choice of FEC for data broadcasting is limited to block codes whose lengths are integer multiples of the information block length. Three different codes have been found to be suitable and (along with the case of no FEC) this gives four options for encoding data within the D-MAC packet. These are related to the carrier-to-noise ratio, and the calculation is made on the assumption that FM duobinary can be treated as three-state frequency shift keying and that the noise is additive white Gaussian noise.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Performance of Error-Correcting Codes

Binary decoding of relatively short codes corrupted by Gaussian noise or pulse interference has been considered in applications for which the minimum useful information block length is unity, equal to the information bit capacity of a code, or equal to an integral multiple of the information capacity of a code. The following results pertain to applications which are further characterized by the performance criterion of minimizing error rate and transmitter power, with only minor restrictions on transmission bandwidth and none on channel efficiency (no credit given for error detection): [1] The word error probability for any group error-correcting code is never exceeded by its corresponding bit error probability (for either Gaussian noise or pulse interference). [2] Relatively short codes (10 to 50 information bits) of moderate redundancy (40 to 50 per cent) are available which can reduce bit error rates by factors of 10 to 400, or equivalently, permit 1 to 3 db reductions in transmitter power, when the coded system bit error rate is 10-6(Gaussian noise). [3] These same codes can alternatively reduce word error rates by factors of 10 to 104, or equivalently, permit reductions of 1.5 to 3.7 db in transmitter power, for average word error rates corresponding to values of the quantity E/N_{o} (signal energy per information bit/Gaussian noise power density) in the neighborhood of 8 db for the coded systems. [4] Under worst-case pulse interference, these codes permit 4 to 7 db reductions in transmitter power for average word error rates less than 20 per cent. (Considerably greater improvements result for the pulse interference expected.) [5] All of these codes are easily encoded and decoded.