Receiver End Research Articles

Performance Improvement and Analysis of NOMA in densely populated networks

ABSTRACT Non Orthogonal Multiple Access technique (NOMA) is a potential and promising candidate for 5 G and beyond 5 G due to its better spectral efficiency and low latency. However, it faces implementation challenges in densely populated networks due to its computational complexity. In NOMA, for decoding user information at the receiver end, it needs to perform times perfect Successive Interference Cancellation (SIC) operation. Hence, in a dense network, where the number of users is high, the implementation of NOMA becomes tedious. In order to improve the performance of NOMA implementation, in this work, the concept of Cooperative Modulated-NOMA (CM-NOMA) is applied in the considered densely populated networks model. Performance analysis of the system in terms of outage probability, Symbol-to-Error Rate (SER) and achievable data rate in both one-to-one and cooperative communications scenarios are done. The analytical expressions are also validated using Monte Carlo simulation. The results show that the deployment of CM-NOMA in a densely populated network increases the performance of the system, and also reduces the computational complexity.

Semi-Blind watermarking using convolutional attention-based turtle shell matrix for tamper detection and recovery of medical images

“Telemedicine or e-medicine” refers to an electronic communication system that shares medical information from one location to another through the transmission channel. The increase in multimedia data sharing/transmission across the communication channel has raised to an uncontrollable stage. Thus, the transmission of medical reports across the network has increased higher, which has a chance of tampering either intentional or unintentional attacks. In the case of deliberate attacks, tamper detection and localization are the highly required criteria to verify the originality. In such cases, medical image authentication, security, and integrity verification are also essential criteria in telemedicine applications to verify whether the report belongs to the right person or not. To achieve these criteria and to satisfy these requirements Digital watermarking techniques are highly suggested. Much research has been carried out to address this issue, but some drawbacks and limitations still need to be addressed. The objective is to accomplish a Tamper detection, localization, and recovery (TDLR) system with minimal source information at the receiver end with a better payload or embedding capacity. This paper presents a novel Conventional Attention network (CoAtNet) based invariant watermark generation. A two-level embedding is proposed to enhance watermark security, where image tamper localization and recovery information is generated. The primary level of embedding is carried out by the Turtle Shell Data Hiding Algorithm (TSDH), and the secondary level of embedding is carried out by the DWT-SVD transform. The result shows that the proposed model achieves high imperceptibility and tamper detection accuracy of 60.24 and 99.51% respectively. Furthermore, the suggested system performed well in evaluations of tamper detection and image restoration for various malicious attacks against state-of-the-art systems.

Error performance analysis of forward error correction using convolutional encoding in the presence of (1/f) noise

Any communication scheme's principal goal is providing error-free data transmission. By increasing the rate at which data could be transmitted through a channel and maintaining a given error rate, this coding is advantageous. The message bits to be transmitted will gradually receive more bits thanks to the convolution (channel) encoder. At the receiver end of the channel, a Viterbi decoder is utilized in order to extract original message sequence from the received data. Widely utilized error correction approaches in communication systems for the enhancement of bit error rate (BER) performance are Viterbi decoding and convolutional encoding. The Viterbi decoder and convolution encoder rate for constraints with lengths of 2 and 6 and bit rates of 1⁄2 and 1⁄3 are shown in this study in the presence of (1/f) noise. The performance regarding the convolutional encoding/hard decision Viterbi decoding forward error correction (FEC) method affects the simulation outcomes. The findings demonstrate that the BER as function of signal to noise ratio (SNR) acquired for uncoded binary phase shift keying (BPSK) with the existence of additive white Gaussian noise (AWGN) is inferior to that acquired with the use of a hard decision Viterbi decoder.

Quadratic filtering for discrete time-varying non-Gaussian systems under binary encoding schemes

This paper is concerned with the recursive quadratic filtering problem for a class of linear discrete-time systems subject to non-Gaussian noises. Considering its robustness against channel noises, the binary encoding scheme is utilized in the process of data transmission from sensors to the filter. Under such a scheme, the original signal is first encoded into a bit string, and then transmitted via memoryless binary symmetric channels (with certain crossover probabilities). Subsequently, the received bit string is recovered by a decoder at the receiver end. The primary purpose of this paper is to design a recursive quadratic filter for the underlying non-Gaussian systems with a minimized upper bound on the filtering error covariance. For this purpose, an augmented system is first constructed by aggregating the original vectors and their second-order Kronecker powers. Accordingly, an upper bound on the filtering error covariance is obtained in the form of solutions to certain Riccati-like difference equations, and the obtained bound is then minimized by properly choosing the filter parameter. Moreover, sufficient conditions are established to guarantee the boundedness of filtering error covariance. Finally, a numerical example is provided to demonstrate the effectiveness of the proposed quadratic filtering algorithm.

Direct detection system for independent triplet-sideband signals based on a single photodiode.

This paper proposes a novel, to the best of our knowledge, independent triplet-single-sideband (triplet-SSB) transmission system scheme aimed at increasing channel capacity and improving spectrum efficiency. The conventional independent multiband transmission systems are limited by their complexity and high computational requirements, which hinder the improvement of spectrum efficiency and channel capacity. To address these challenges, this scheme uses three independent signals, modulated by an in-phase/quadrature (I/Q) modulator, and transmits them over a 5-km standard single-mode fiber (SSMF). At the receiver end, a single photodiode (PD) is used for signal reception, and the signals are separated using digital signal processing (DSP) algorithms. Through simulation and verification, the feasibility and reliability of the system are demonstrated, with the bit error rates (BERs) of all three signals below the hard decision forward error correction (HD-FEC) threshold value of 3.8 × 10-3. This independent triplet-SSB transmission system scheme effectively improves spectrum efficiency and channel capacity, providing a valuable solution for meeting the growing demands of data transmission.

KNN-Based ML Model for the Symbol Prediction in TCM Trellis Coded Modulation TCM Decoder

Machine Learning is a booming technology today. In a machine learning set of training, data is to be provided to the model for training and that model predicts the output. Machine Learning models are trained using a computer program known as ML algorithms.The new machine learning-based Transition Metric Unit (TMU) of 4D- 8PSK Trellis coded Modulation TCM Decoder is presented in this work. The classic Viterbi decoder's branch metric unit, or TMU, takes on a complex structure. Trellis coded Modulation (TCM) is a combination of 8 PSK modulations and Error Correcting Code (ECC). TMU is one of the complex units of the TCM decoder, which is essentially a Viterbi decoder. Similar to how the first Branch metric is determined in the straightforward Viterbi decoder, the TCM decoder performs this BM computation via the TMU unit. The TMU becomes challenging and uses more dynamic power as a result of the enormous constraint length and the vast number of encoder states.In the proposed algorithm innovative KNN (K nearest neighbours) based ML model is developed. It is a supervised learning model in which input and output both are provided to the model, training data also called the labels, when a new set of data will come the model will give output based on its previous set experience and data.Here we are using this ML model for the symbol prediction at the receiver end of the TCM decoder based on the previous learning. Using the proposed innovation, the paper perceives the optimization of the TCM Decoder which will further reduce the H/W requirements and low latency which results in less power consumption.

YOLO-based ROI selection for joint encryption and compression of medical images with reconstruction through super-resolution network

Medical images contain significant patient information, and this confidential data should not be accessed without proper authorisation. Concurrently, due to the high redundancy of image data, compression is necessary to minimise image size and efficiently utilise network resources. This paper presents an effective joint encryption and compression method for medical images that prevent critical data leakage while reducing redundancy. Initially, a powerful real-time object detection method, You Only Look Once v7, is employed to accurately and swiftly detect the region of interest (ROI) within the medical images. Subsequently, a joint three-dimensional chaotic map and Huffman encoding are applied to secure medical images without compromising the compression ratio or increasing the time cost. Lastly, a super-resolution network is established at the receiver end to better reconstruct the ROI image for precise diagnostic purposes. The comprehensive experimental analysis demonstrates that our method delivers high levels of security, compression, and visual quality performance on standard datasets used in smart healthcare applications, at a minimum. Furthermore, our approach outperforms other competitive state-of-the-art schemes when compared. We hope this study will inspire further research within the healthcare community.

IMPLEMENTATION OF VLC USING ERROR CORRECTING TURBO CODES

This work showcases the analysis of an efficient VLC applications using error correcting turbo codes. It demonstrates how device switching, audio signal transfer and light switching is done using VLC. Compared to the conventional radio signal transfer, it is quiet advantageous as visible light frequency doesn’t need to be licensed for certain frequency or bandwidth. Data transmission needs to be secured, while reducing the error rates. Here, for device switching and data transfer we use turbo codes to reduce the error rates in data transfer. The proposed sytem has transmitter and receiver. In transmitter the data is modulated onto visible light using intensity modulation techniques, at the receiver end, a photodiode captures modulated light and converts it back into electrical signal.

Design of Turbo Trellis Coding Modulation Scheme of Rate 4/9 for Rician Fading Channel

When the fading channels are encountered during data communication, errors are likely to occur at the receiving end due to multipath propagation. Researchers have been consistently striving to develop Error Correction Schemes that can effectively handle these errors and ensure error-free data reception at the receiver end. Of particular interest are the Forward Error Correction Schemes that can be implemented at the transmitter end itself. However, the implementation of error correction coding through these schemes incurs additional costs in terms of bandwidth expansion, as extra bits need to be added to facilitate error correction. Fortunately, there exists one coding scheme called Trellis Coded Modulation (TCM), which addresses this issue. TCM selects a modulation scheme based on the rate of the convolutional coding scheme. However, this coding technique has limitations in correcting the number of errors, leading to the development of Turbo Coding. This scheme utilizes two coders at the transmitter, arranged in either serial or parallel configuration, and a suitable decoder at the receiver. A design of Turbo Coding scheme has been presented in this paper, that employs convolutional coders having rate 2/3, in a serially concatenated configuration, providing an effective rate of 4/9. This turbo coding scheme is then applied to TCM scheme in order to preserve the bandwidth. Therefore, if using the convolutional coding scheme of rate 2/3, the modulation scheme is 8-QAM and in order to preserve bandwidth after coding, using the Turbo coding scheme of rate 4/9, then the modulation scheme will be 512-QAM. The simulations have been conducted in MATLAB and the error correcting capabilities of the designed scheme in comparison with convolutional coding scheme using the constituent convolutional encoder have also been compared. It has been observed that in the Rician fading channel conditions, the Turbo Trellis Coding Modulation Scheme provides approximately 5 dB gain compared to the convolutional coding scheme.

Outage Analysis of Sparse Vector Coding-Based Downlink Multicarrier NOMA for URLLC

Ultra-reliable and low latency communication (uRLLC) is a promising use case in the fifth generation and beyond systems for critical and delay-sensitive applications with aid of short packet transmission. Nevertheless, multi-carrier non-orthogonal multiple access (MCNOMA) is a promising technique to achieve spectral efficiency and massive connectivity, however, inter-carrier interference (ICI) stands out to be a major downside. Recently, sparse vector coding (SVC) is proposed to fulfill the trade-off between reliability and latency, thereby achieving the benchmarks of uRLLC. In this paper, SVC based downlink MCNOMA (SVC-MCNOMA) system is considered and first it is shown that SVC-MCNOMA is free from ICI due to the sparse nature of the information. Further, compressed sensing-based recovery at the receiver end helps in reducing the latency as well as enhances reliability. Moreover, to study the system performance, this paper derives the closed form outage expressions of the SVC-MCNOMA system over the Rician fading channel and through Monte-Carlo simulation, the analytical results are validated. The analyses demonstrate that SVC-MCNOMA outperforms conventional MCNOMA (C-MCNOMA), thereby achieving spectral efficacy, ultra-reliability with low latency and eradicates the effect of ICI.

Improving the Timeliness of Two-Source Status Update Systems in Internet of Vehicles With Source-Dedicated Buffer: Resource Allocation

Age of information (AoI) is a pertinent metric for characterizing the timeliness of status updates in Internet of Vehicles (IoV). Resources allocated to update transmission would significantly affect the timeliness of status update observed at the receiver end. This work investigates the sum average AoI of a two-source wireless updating system in IoV by modeling the system as a non-preemptive queue with a size-two source-dedicated buffer. Two bandwidth allocation schemes, i.e., an asynchronous time division multiplexing (ATDM) scheme and a dynamic bandwidth allocation (DBA) scheme, are proposed for the system. In the ATDM scheme, status updates are transmitted using all available bandwidth sequentially while in the DBA scheme, the server fractionally allocates the available bandwidth for transmitting the arrived update based on the buffer state. By analyzing the age evolution of each update stream based on stochastic hybrid systems, the closed-form per-source average AoI and the sum average AoI of the two proposed schemes are derived. In particular, the per-source average AoI when the system provides priority for serving one update stream is also given. It is demonstrated that by employing the ATDM scheme and the DBA scheme with optimized bandwidth allocation factor, the system can achieve a significant improvement in terms of sum average AoI, enhancing the update freshness.

Face recognition based physical layer security system for next-generation wireless communication

Security system in every sector all over the world is a most demandable and crucial issue to protect the fake user especially in wireless communication system. The most common feature in current wireless communication system is only transmitted users’ information; consequently, it is difficult to identify the actual sender to attain the desired security. Face recognition is one of the most popular security systems in biometric authentication, which can detect intruders to restricted or high-security areas in wireless communication sector, and help in minimizing the face user. In this paper, we proposed a system that is the senders will transmit message information with their image to confirm the original senders. A face-recognition algorithm will be implemented at the receiver end. When a senders’ transmitted information enters to the receiver section, the image of sender will be separated from original message signal and sent to the face-recognition algorithm to be analysed and compared with an existing database of trusted user. An alarm goes off if the user is not recognized.

Development of an Android Based Home Automation System

As automation technology keeps advancing, the future of modern homes is continually changing from manual system into automatic ones that include remote control process. A Conventional means of accessing home electronic appliances is rigid and demands user presence to attend to different locations of such appliances before they can be used, this can be stressful for the elderly, the cripples, and provides limited ease of operation for everyone. The need for wireless communication function of the home appliances becomes very important in order to increase the flexibility of accessing them remotely by a user. Accessing and control of electronic devices and appliances used at home through a remote process is the main purpose for the development of a portable home automation system using app that is based on an android phone. ESP8266 microcontroller was interfaced to a servo motor that controls door movement and also to an AC bulb through a relay at the signal receiver end of the system. An MIT application inventor platform was used to build a mobile app on an android phone at the signal transmitter end of the system; this enables the transmission of on and off signals to the receiver end through Wi-Fi connection to access the connected loads (door and lamp). The hardware and software architecture of the developed home automation system was described in this paper. Implementation of a prototype of the designed system was carried out after which the system was tested on hardware as it yields expected results.

Measurement incompatibility and quantum advantage in communication

Measurement incompatibility stipulates the existence of quantum measurements that cannot be carried out simultaneously on single systems. We show that the set of input-output probabilities obtained from d-dimensional classical systems assisted with shared randomness is the same as the set obtained from d-dimensional quantum strategies restricted to compatible measurements with shared randomness in any communication scenario. Thus, measurement incompatibility is necessary for quantum advantage in communication, and any quantum advantage (with or without shared randomness) in communication acts as a witness to the incompatibility of the measurements at the receiver's end in a semi-device-independent way. We introduce a class of communication tasks - a general version of random access codes - to witness incompatibility of an arbitrary number of quantum measurements with arbitrary outcomes acting on d-dimensional systems, and provide generic upper bounds on the success metric of these tasks for compatible measurements. We identify all sets of three incompatible rank-one projective qubit measurements that random access codes can witness. Finally, we present the generic relationship between different sets of probability distributions - classical, quantum with or without shared randomness, and quantum restricted to compatible measurements with or without shared randomness - produced in communication scenarios.

Joint WDM and OAM Mode Group Multiplexed Transmission Over Conventional Multimode Fiber

To exploit the advantages of multimode fiber (MMF)-based transmission and to improve the overall capacity, transmission of OAM modes over a single wavelength needs to be replaced by multichannel transmission with the proper experimental demonstration in terms of achievable bit error rates (BER), cross-talk(x-talk), etc. over the entire transmission band. In this paper, we have experimentally shown the successful transmission of two OAM mode groups multiplexed signals jointly with three channels using wavelength division multiplexing (WDM) over a 1 km conventional MMF, namely OM3. In this experimental study, each OAM mode over each WDM channel uses 10 Gbps of on-off keying (OOK) modulation format. At the receiver end, the achieved bit error rate (BER) is found well below the required pre-FEC BER of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$3.8\times 10^{-3}$</tex-math></inline-formula> without using any MIMO-DSP. To establish the efficacy of the signal transmission, the time evolutions of OAM mode x-talk and BER over wavelengths spanning the entire C-band have been experimentally measured. Under the influence of different x-talks, the BER performances of all three 50 GHz-spaced WDM channels for both OAM modes are measured. With proper adjustment of polarization at the receiver end, a BER value below the pre-FEC threshold is achieved over 900 seconds. The experimental results also revealed that the power penalty contribution of WDM x-talk is negligible compared to OAM mode x-talk.

A Modified Vigenère Cipher based on Time and Biometrics features

Biometrics is widely used with security systems nowadays; each biometric modality can be useful and has distinctive properties that provide uniqueness and ambiguity for security systems especially in communication and network technologies. This paper is about using biometric features of fingerprint, which is called (minutiae) to cipher a text message and ensure safe arrival of data at receiver end. The classical cryptosystems (Caesar, Vigenère, etc.) became obsolete methods for encryption because of the high-performance machines which focusing on repetition of the key in their attacks to break the cipher. Several Researchers of cryptography give efforts to modify and develop Vigenère cipher by enhancing its weaknesses. The proposed method uses local feature of fingerprint represented by minutiae positions to overcome the problem of repeated key to perform encryption and decryption of a text message, where, the message will be ciphered by a modified Vigenère method. Unlike the old usual method, the key constructed from fingerprint minutiae depend on instantaneous date and time of ciphertext generation. The Vigenère table consist of 95 elements: case sensitive letters, numbers, symbols and punctuation. The simulation results (with MATLAB 2021b) show that the original message cannot be reconstructed without the presence of the key which is a function of the date and time of generation. Where 720 different keys can be generated per day which mean 1440 distinct ciphertexts can be obtained for the same message daily.

Deep Q-Learning-Based Buffer-Aided Relay Selection for Reliable and Secure Communications in Two-Hop Wireless Relay Networks

This paper investigates the problem of buffer-aided relay selection to achieve reliable and secure communications in a two-hop amplify-and-forward (AF) network with an eavesdropper. Due to the fading of wireless signals and the broadcast nature of wireless channels, transmitted signals over the network may be undecodable at the receiver end or have been eavesdropped by eavesdroppers. Most available buffer-aided relay selection schemes consider either reliability or security issues in wireless communications; rarely is work conducted on both reliability and security issues. This paper proposes a buffer-aided relay selection scheme based on deep Q-learning (DQL) that considers both reliability and security. By conducting Monte Carlo simulations, we then verify the reliability and security performances of the proposed scheme in terms of the connection outage probability (COP) and secrecy outage probability (SOP), respectively. The simulation results show that two-hop wireless relay network can achieve reliable and secure communications by using our proposed scheme. We also performed comparison experiments between our proposed scheme and two benchmark schemes. The comparison results indicate that our proposed scheme outperforms the max-ratio scheme in terms of the SOP.

Ultrahigh Capacity MMWoF Link Using 2-λ VCSEL Front-Haul Transmitter Encoded With Broadband Generalized FDM Data Stream

By employing a dual-wavelength (2-λ) vertical cavity surface emitting laser (VCSEL) directly encoded by novel quadrature amplitude modulation generalized frequency division multiplexing (QAM-GFDM) modulation schemes with optimized data capacity, a 28-GHz millimeter-wave-over-fiber (MMWoF) link is created for fusing the long-reach single-mode-fiber wired network and the beyond fifth generation (B5G) mobile wireless network without using any localized synthesizer and mixer at the remote receiver end. Detuning the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</i> subcarrier to 2 optimizes the electrical-to-electrical 5-GHz 64-QAM-GFDM link with an error vector magnitude (EVM) of 3.04%, a signal-to-noise ratio (SNR) of 30.3 dB and a bit error ratio (BER) of 2.1×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-13</sup> . By using this condition to perform the long-reach 50-km optical transmission, the 5-GHz 64-QAM GFDM carried by the 2-λ VCSEL exhibits an SNR of 23.8 dB, an EVM of 6.47% and a BER of 2.2×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-4</sup> . By fixing the optimized <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</i> subcarriers, the maximal bandwidth and raw data rate of the 64-QAM-GFDM transmission can be achieved to 6.75 GHz and 40 Gbit/s, respectively. For the wireless transmission at the remote end, the photo-mixed MMW carrier at 28-GHz exhibits a peak power of -11.4 dBm and a carrier-to-noise ratio (CNR) of 45 dB. After performing the self-heterodyne down-conversion via power envelope detection, the receiving data amplitude is improved from 26.2 to 132 mV with adding a 3-dB attenuator for impedance matching. Under the 2-m wireless transmission via horn antenna pair, the maximal bandwidth and data rate of the received 4-QAM GFDM data respectively achieve 2 GHz and 4 Gbit/s.

Attenuation compensation techniques for ultra-reliable high throughput satellite integrated network

To support future development in satellite communication systems in the Ka-band and above, this paper studies the beacon attenuation measurements recorded at Chilbolton in Southern England to evaluate the performance of Time Diversity (TD) and Site Diversity (SD) techniques. TD performance is computed by comparing the measured rain attenuation time series with a delayed version of itself. Five (5) time delays were employed, namely 1, 5, 10, 30 and 60 seconds. SD performance is obtained by using the single-site rain attenuation data at Chilbolton and the ITU-R P.618-13 recommendation [1], with inter-site distances 1, 5, 10, and 20 km, and baseline angle fixed at 90°. Analytical results of the selection combining (SC)-based TD and SD performance are validated by MATLAB simulations. Results show that the TD and SD are significant techniques for handling the effect of rain attenuation. However,to be effective, TD requires long time delays, whereas SD requires large inter-site separation distances and additional terrestrial infrastructure. Significant improvement in TD performance is obtained by using maximal ratio combining (MRC), rather than selection, to produce the carrier signal input to the demodulator at the receiver end. This improvement is demonstrated in the simulation results presented in the paper.

Simulation analysis of underwater wireless optical communication based on Monte Carlo method and experimental research in complex hydrological environment

This paper aims to address the challenges of short optical communication distances and high Bit Error Rates (BERs) caused by seawater absorption, scattering, and underwater turbulence. This paper establishes an optical communication channel model based on the Monte Carlo method and simulates and analyzes the process of received optical power attenuation when light is transmitted underwater due to absorption and scattering. The simulation model focuses on the influence of seawater type, transmission distance, receiver position, and angle on the received optical power attenuation. The results of this simulation will provide theoretical support for the development of prototype underwater optical communication systems and experiments in complex environments. To solve the long-range weak signal reception and processing issues in underwater optical wireless communication systems, this paper proposes the design and implementation of an underwater optical wireless communication system using optimized on-off keying high-power light-emitting diode/laser diode modulation technology and avalanche photodiode (APD)/photomultiplier (PMT) receiver modules. In addition, this paper describes the design of the underwater optical communication host computer software, which provides functions such as mode selection, BER monitoring, and file transfer. To test the performance of the proposed system, this paper conducts experiments in a 35 m long pool, fixed platform, and underwater mobile platform, as well as cross-air-water interface optical communication performance test experiments in a complex hydrological environment. The results show that the system achieved a 35 m underwater medium communication distance, transmission rate of 5–20 Mbps, and cross-domain wireless optical communication function under the condition of a BER of less than 10−6. The experiments also revealed that the communication distance decreases as the turbidity of the water body increases and the PMT receiver module selected at the receiver end has a longer communication distance than the APD receiver module. Overall, this paper demonstrates the feasibility of the proposed technology for underwater optical communication systems in complex waters, providing theoretical and data support for the next engineering practice.