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V2X (Vehicle-to-everything) communication relies on short messages for short-range transmissions over a fading wireless channel, yet requires high reliability and low latency. Hard-decision decoding sacrifices the preservation of diversity order, leading to pronounced performance degradation in fading channels. By contrast, soft-decision decoding retains diversity order, albeit at the cost of increased computational complexity. We introduce a novel enhanced hard-decision decoder termed as the Diversity Flip decoder (DFD) designed for preserving the diversity order. Moreover, it exhibits ‘universal’ applicability to all linear block codes. For a $\mathscr {C}(n,k)$ code having a minimum distance ${d_{\min }}$, the proposed decoder incurs a worst-case complexity order of $2^{({d_{\min }}-1)}-1$. Notably, for codes having low ${d_{\min }}$, this complexity represents a significant reduction compared to the popular soft and hard decision decoding algorithms. Due to its capability of maintaining diversity at a low complexity, it is eminently suitable for applications such as V2X (Vehicle-to-everything), IoT (Internet of Things), mMTC (Massive Machine type Communications), URLLC (Ultra-Reliable Low Latency Communications) and WBAN (Wireless Body Area Networks) for efficient decoding with favorable performance characteristics. The simulation results provided for various known codes and decoding algorithms validate the performance versus complexity benefits of the proposed decoder.

Abstract This letter considers the problem of estimating the state of a scalar dynamical system over a wireless channel that is lossy, capacity, and power limited. The limited power assumption, which is valid for most real problems, links the number of quantisation bits and packet error rate. As the number of quantisation bits increases, the quantisation noise decreases but the packet loss rate increases. It is shown that the estimation error variance (EEV) is minimised for a range of quantisation bits. Further, it is shown that operating beyond the optimal range sharply increases the EEV. Simulation results corroborating the analytical results are also presented.

In a recent paper, Mazucheli et al. (2019) introduced the unit-Gompertz (UG) distribution and studied some of its properties. It is a continuous distribution with bounded support, and hence may be useful for modelling life-time phenomena. We present counter-examples to point out some subtle errors in their work, and subsequently correct them. We also look at some other interesting properties of this new distribution. Further, we also study some important reliability measures and consider some stochastic orderings associated with this new distribution.

A piece of user equipment (UE), typically, has access to multiple radio access technologies (RATS). Moreover, apart from the standard primary cellular network, the secondary cellular networks can assist the primary network in downlink UE communications. In this way, the data can reach the UE through multiple entities. This paper exploits the multiple entities’ idea by proposing a cross-layer scheme that combines data to improve the block error rate (BLER) and the throughput. For this, we define a new entity, called the super-MAC, just above the Medium Access Control (MAC) layer. More specifically, we propose data duplication (at the transmitter) and combining (at UE) at the super-MAC, where the super-MAC gets the Radio Link Layer protocol data unit (RLC-PDU) and sends multiple-copies across various interfaces to different MAC-entities. In doing so, the super-MAC attaches a unique sequence number to a group of RLC-PDUs together. At the UE, the data from different MAC entities are combined at super-MAC to clear any block error. The super-MAC operates in between the Cyclic Redundancy Check and Forward Error Correction stages of the HARQ process. The additional complexity introduced by the scheme is negligible in front of the existing operations. Moreover, the average latency improves due to the significant improvement in the Block Error rate (BLER) that the combining scheme offers over the BLER of the conventional standalone system. Also, since the errors significantly reduce, the throughput shows significant improvement. Finally, the proposed scheme is an advancement in HARQ to reduce retransmissions, and hence it is suitable for the next-generation networks like B5G or 6G to adopt the super-MAC.

This work adopts the artificial neural network (ANN) for predicting the efficiency of a double-pipe heat exchanger which employs T-W tape inserts with different wing-width ratios (w/W) of 0.31, 0.47, and 0.63. The effects of friction factor (f), Nusselt number (Nu), and thermal performance (η) are predicted using the established multi-layer ANN. Different scenarios are examined using two parameters as inputs to the ANN: Reynolds number (Re) and w/W. The results prove that the developed ANN model is able to accurately predict the experimental data. The obtained mean square error has a value of less than 0.7 as compared to the experimental values. Furthermore, the proposed ANN-based approach is also effective to predict the thermal parameters, with the least variance and high precision. In addition, a multiple linear regression is employed to check the efficiency of the proposed model from which it is demonstrated that the suggested neural network method provides useful guidance for accurately predicting the thermal parameters with the least variance. The configuration of 2–10-1 is found to be the best for the current model, with a mean absolute error of 0.546896.

Cognitive radio (CR) systems are potentially capable of mitigating the spectrum shortage of contemporary wireless systems. In this paper, we provide a brief overview of CR systems and the important research milestones of their evolution, along with their standardization activities, as a result of their research. This is followed by the detailed analysis of the interweave policy-based CR network (CRN) and by a detailed comparison with the family of underlay-based CRNs. In the interweave-based CRN, sensing of the primary user's (PU) spectrum by the secondary user's (SU) has remained a challenge, because the sensing errors prevent us from fulfilling the significant throughput gains that the concept of CR promises. Since missed detection and false alarm errors in real-time spectrum sensing cannot be avoided, based on a new approach, we quantify the achievable rates of the interweave CR by explicitly incorporating the effect of sensing errors. The link between the PU transmitter and the SU transmitter is assumed to be fast fading. Explicitly, the achievable rate degradation imposed by the sensing errors is analyzed for two spectrum sensing techniques, namely, for energy detection and for magnitude squared coherence-based detection. It is demonstrated that when the channel is sparsely occupied by the PU, the reusing techniques that are capable of simultaneously providing low missed detection and false alarm probabilities cause only a minor degradation to the achievable rates. Furthermore, based on the achievable rates derived for underlay CRNs, we compare the interweave CR and the underlay CR paradigms from the perspective of their resilience against spectrum sensing errors. Interestingly, in many practical regimes, the interweave CR paradigm outperforms the underlay CR paradigm in the presence of sensing errors, especially when the SNR at the SU is below 10 dB and when the SNR at the PU is in the range of 10-40 dB. Furthermore, we also provide rules of thumb that identify regimes, where the interweave CR outperforms the underlay CR.

Objectives: This cross-sectional study investigated the association of lipoprotein(a) [Lp(a)] levels as an atherosclerosis predictor and their relationship to the severity of coronary artery disease (CAD). Methods: 360 consecutive patients at Sanjay Gandhi Postgraduate Institute of Medical Sciences and King George’s Medical University hospitals, Lucknow, North India, with chest pains, CAD symptoms and on lipid-lowering therapy were enrolled between June 2009 and October 2011. Before coronary artery angiography (CAG), a fasting blood sample was assessed for lipid and Lp(a) levels. The synergy between percutaneous coronary intervention with taxus and cardiac surgery (SYNTAX) score was calculated according to the CAG results. Patients were divided into 3 groups based on CAD severity and SYNTAX scores. Results: Angiography revealed CAD in 270 patients. Lp(a) levels were higher in CAD compared to non-CAD patients (48.7 ± 23.8 mg/dl versus 18.9 ± 11.1 mg/dl [P 30 (88.0±24.0 mg/dl). Lp(a) levels correlated significantly with SYNTAX scores (r = 0.70, P

In this paper we present alternate form of Radix-4/8 and split radix FFT’s based on DIF (decimation in frequency) version and discuss their implementation issues that further reduces the arithmetic complexity of power-of-two discrete Fourier Transform. This is achieved with circular shift operation on a subset of the output samples resulting from the decomposition in these FFT algorithms and a proposed dynamic scaling. These modifications not only provide saving in the calculation of twiddle factor, but also reduce the total flop count to ˜4Nlog2N almost 6% fewer than the standard Radix-4 FFT algorithm 2113log12NN? , 5% fewer than the standard Radix-8 FFT, and 273log9NN? , 5.5% fewer than the standard split radix FFT. Keywords: DFT (Discrete Fourier Transform), FFT (Fast Fourier Transform), Radix-4(R4), Radix-8(R8) and Split Radix (SR) FFT and Flop Count

Short block length "block" codes are typically not used in wireless standards as soft decision decoding is computationally intensive and hard decision decoding results in performance loss. However, short block lengths are of interest to massive machine-type communications (mMTC) and ultra-reliable low-latency communications (URLLC). In this paper, we propose a diversity preserving enhanced hard-decision decoding scheme for parity check codes (PCC) over Rayleigh fading channels. The proposed flip decoding scheme has linear complexity in the block length. Theoretical analysis and simulation results verify the correctness of the proposed detection scheme. [ABSTRACT FROM AUTHOR]