Multiplexing Algorithm Research Articles

Design of Intelligent City Communication Network Based on Internet of Things

Abstract In response to the advancements in Internet of Things (IoT) technology and the growing demands for data transmission, there is a crucial need for further integration of communication network technology with IoT to enhance efficiency. This paper presents the design of a multi-node communication network model utilizing the Orthogonal Frequency-Division Multiplexing (OFDM) algorithm. In the realm of physical layer parameter design, uplink, and downlink carriers are allocated based on OFDM symbols, employing the Zadoff-Chu (ZC) sequence as the pilot frequency sequence. Additionally, the Cyclic Redundancy Check (CRC) error-checking code is implemented to ensure the accuracy of network transmissions. The model proposed in this study is applied to the operational dynamics of traffic systems within a smart city, focusing on the security and operational efficiency of the traffic communication network. Empirical testing and analysis demonstrate that the communication network, as designed, is susceptible to malware attacks by 25.68%, representing the least vulnerability among the three algorithms assessed. Moreover, in examining the bus trip time distribution with the implementation of this model, the average running time is predominantly around 11.76 minutes, which is a reduction of 0.74 minutes compared to previous configurations, thereby indicating an improvement in operational efficiency.

Wide field of view chiral imaging with a liquid crystal planar lens enabled by digitalized nanogratings.

To compensate for the inability for polarization imaging by conventional methods, metasurface optics with compactness and multi-function emerge as an approach to provide images with different linear and circular polarizations. Here, we propose a liquid crystal (LC) geometric phase-based chiral imaging lens (CIL) that simultaneously forms images of objects with opposite helicity. The CIL (Diameter 2.3 cm) was optimized by a spatial multiplexing algorithm and realized using the digital holography technique, where the LC domains were regulated by pixelated nanogratings with varied orientation. We investigated the potential of the patterning technique toward high order LC alignment by balancing the periodicity and depth of the nanogratings. The CIL exhibited a wide field of view of ±20°, which is attributed to the self- assembling effects of LC molecules. The compactness, lightness, and ability to produce chiral images of the LC CIL even at large angles have significant potential for practical polarization imaging.

URLLC Shadowing Estimation in eMBB-uRLLC Multiplexing for Geospatially Correlated PPP Channel

This letter investigates eMBB-uRLLC multiplexing in which the eMBB users’ channel feedback is exploited for the uRLLC channel condition estimation. This approach allows instant and reliable transmission without acquiring the user’s CSI, which is especially advantageous in intermittent uRLLC traffic transmissions. This letter introduces two channel estimators for a geospatially-correlated channel and derives their estimation errors. Then, we propose an eMBB-uRLLC multiplexing algorithm based on the estimates and provide transmission reliability and spectral efficiency measures under adaptive modulation and coding. Simulation results confirm the effectiveness of the proposed approach in different propagation environments.

Design Method of an Ocean Induction Coupling Chain Communication System that Resists the Multipath Effect of a Seawater Channel

In this study, a mathematical model of multipath channels is established, and the delay parameters of 10-path models are calculated at 300 m. A multipath-channel hardware simulator based on a field programmable gate array (FPGA) is designed and verified at 100 kHz, 200 kHz, 500 kHz, 1 MHz, and 24 MHz transmission frequencies. According to the characteristics of the ocean induction coupling chain channel, the orthogonal frequency-division multiplexing (OFDM) algorithm parameters are designed by referring to the wireless communication protocol. The appropriate length cyclic prefix (CP) is added in the OFDM symbol to resist the multipath effect of the seawater channel, and the FPGA hardware transceiver based on the OFDM algorithm is realized. The hardware platform of the ocean induction coupling chain communication system is developed to resist the multipath effect of the seawater channel and tested at 24 MHz. The experimental results show that 800 ns is the best CP length for the developed system, which can effectively resist the multipath effect, with a signal-to-noise ratio above 24 dB and a bit error rate below 1%. This study provides a hardware simulation test platform and an effective method to resist the multipath effect of a seawater channel and improve the transmission performance of the seawater channel.

Dynamic Sidelobe Multiplexing in Beamspace MIMO Systems

Recent studies on multiplexing concept over beamspace multiple-input-multiple-output (MIMO) can reduce the need for using phase shifters while keeping the directivity performance at similar levels. Thus, beamspace MIMO provides cost-effective and simple hardware designs for millimeter-wave (mmWave) systems. However, the number of users/streams that can be supported at the same time-frequency resource is limited to the number of radio-frequency (RF) chains. In this letter, to overcome this restriction, dynamic sidelobe multiplexing (DSM) algorithm is proposed. The proposed multiplexing technique precodes the transmitted data over transmitter beams in order to open up a new path to the receiver. Therefore, the proposed method provides an opportunity to exceed the limits of conventional hardware usage in beamspace MIMO. The numerical results show that the proposed approach enhance the system performance for more than 50% compared to conventional beamspace MIMO techniques.

Non-Redundant OFDM Receiver Windowing for 5G Frames and Beyond

Contemporary receiver windowed orthogonal frequency division multiplexing (RW-OFDM) algorithms have limited adjacent channel interference (ACI) rejection capability under high delay spread and small Fast Fourier Transform (FFT) sizes. Cyclic prefix (CP) is designed to be longer than the maximum excess delay (MED) of the channel to accommodate such algorithms in current standards. The robustness of these algorithms can only be improved against these conditions by adopting additional extensions in a new backward incompatible standard. Such extensions would deteriorate the performance of high mobility vehicular communication systems in particular. In this paper, we present a low-complexity Hann RW-OFDM scheme that provides resistance against ACI without requiring any intersymbol interference (ISI)-free redundancies. While this scheme is backward compatible with current and legacy standards and requires no changes to the conventionally transmitted signals, it also paves the way towards future spectrotemporally localized and efficient schemes suitable for higher mobility vehicular communications. A Hann window effectively rejects unstructured ACI at the expense of structured and limited intercarrier interference (ICI) across data carriers. A simple maximum ratio combining successive interference cancellation (MRC-SIC) receiver is therefore proposed to resolve this induced ICI and receive symbols transmitted by standard transmitters currently in use. The computational complexity of the proposed scheme is comparable to that of contemporary RW-OFDM algorithms, while ACI rejection and bit-error rate performance is superior in both long and short delay spreads. Channel estimation using Hann RW-OFDM symbols is also discussed.

Code Division Multiplexing and Machine Learning Based Reversible Data Hiding Scheme for Medical Image

In this paper, a new reversible data hiding (RDH) scheme based on Code Division Multiplexing (CDM) and machine learning algorithms for medical image is proposed. The original medical image is firstly converted into frequency domain with integer-to-integer wavelet transform (IWT) algorithm, and then the secret data are embedded into the medium frequency subbands of medical image robustly with CDM and machine learning algorithms. According to the orthogonality of different spreading sequences employed in CDM algorithm, the secret data are embedded repeatedly, most of the elements of spreading sequences are mutually canceled, and the proposed method obtained high data embedding capacity at low image distortion. Simultaneously, the to-be-embedded secret data are represented by different spreading sequences, and only the receiver who has the spreading sequences the same as the sender can extract the secret data and original image completely, by which the security of the RDH is improved effectively. Experimental results show the feasibility of the proposed scheme for data embedding in medical image comparing with other state-of-the-art methods.

Resourceful Residual Energy Consumption in TDMA Scheduling for IoT-based Wireless Sensor Network

Recently, wireless sensor network (WSN) gets more concern due to the robustness in the latest communication technology iteration such as big data, IoT and 5G. Such daily usage of these technologies includes smart home, smart farming, smart traffic control etc. Moreover, WSN becomes the best preference for mobile objects in data accumulating in a wild range area. Routing distance, signal interference and routing computational cost give a significant impact to the WSN nodes lifetime. Unsynchronized node time allocation slot and neighbor discovery are the main factors in the energy consumption issue faced by the WSN. Higher energy consumption reduces the network lifetime and WSN nodes performance. This paper discusses the optimization of energy-topology (E-T) factors for distributed time division multiplexing algorithm (TDMA) slot scheduling for high-speed data link capacity. The E-T factor is based on the influence of residual energy and topology on the time slot allocation. Both node residual energy and topology information have shown a respectable impact on the TDMA node slot allocation. Moreover, the numbers of neighbors and the network residual energy have been proved both nodes execution time and energy utilization can be reduced in the algorithm. The algorithm performance has been evaluated based on the previous experiment parameters with new high-speed data link. The experimental results have shown a significant improvement in residual energy consumption for the proposed optimized TDMA slot allocation.

A time division multiplexing algorithm based on FPGA buffer shift to realize high speed image processing

With the development of medical image technology, two-dimensional imaging technology bottlenecks highlighted, three-dimensional imaging technology needs more and more urgent. Cone beam projection computer reorganization tomography equipment principle, which is also called “CBCT”, is the X-ray generator with a lower ray around the projection body to do a circular DR digital projection. Then the data obtained in the “intersection” after projection of the projection body has reconstructed in the computer to obtain the three-dimensional image. Image processing has still faced with image processing problems, such as processing speed and stability. In this paper, the key technology of high-speed image processing system based on FPGA is studied, and a high-speed and high-definition cone-shaped beam projection computerized tomo-graphic image processing platform based on FPGA is realized. The design of this paper is based on the image processing algorithm module of the pipeline. According to the structural characteristics of FPGA, a time division-multiplexing algorithm based on buffer shift is proposed to solve the problem of time division multiplexing for shared resources in image processing process, which facilitates the allocation of buffer memory resources. In this paper, the parallel CORDIC algorithm has introduced to solve the problem of the transcendental function in the image algorithm. The iterative speed advantage is obvious, which provides a powerful guarantee for the later image registration.

Novel Distributed Scheduling Algorithms for mmWave Mesh Networks

This paper addresses throughput improvement in millimeter-wave (mmWave) mesh networks via two novel distributed scheduling algorithms. The first one uses packet aggregation and block acknowledgment (ACK) that were introduced in the IEEE Std 802.11e-2005 for WiFi. Specifically, a distributed time-division multiplexing scheduling algorithm, which targets increasing the network capacity via reserving as many contiguous slots as possible for each node, is proposed thus enabling packet aggregation. This algorithm achieves its goal when the operating signal-to-noise ratio (SNR) is significantly high. If that is not the case, the second proposed algorithm can be used. It is a distributed one that starts initially with a random feasible schedule determined cooperatively between nodes. The algorithm then tries to reach better feasible schedules via parallel and successive local searches without violating feasibility constraints. Extensive simulations show that the first algorithm improves the network throughput by almost [Formula: see text] compared to the well-known memory-guided directional medium access control (MDMAC) due to reducing the transmission overhead. The second proposed algorithm is shown to increase the number of reserved slots by about [Formula: see text] over MDMAC. Both algorithms are shown to either increase or almost maintain the same degree of fairness among the nodes as quantified by Jain’s fairness index.

Research on Virtual Channel Multiplexing Algorithm Based on Advanced Orbiting Systems

To address multiple data types and high speeds in a business satellite network based on the virtual channel multiplexing technology of advanced orbiting systems (AOSs), an AOS virtual channel multiplexing system model is established. AOS queue management problems and the constraint problems in virtual channel scheduling are analyzed. On this basis, a priority adaptive random early detection and vaccine updating immune genetic algorithm is proposed. In queue management, based on the scheme of a multi-queue sharing cache with a minimum allocation, the algorithm adaptively adjusts packet dropping probability according to the packet priority. Based on an immune genetic algorithm, virtual channel scheduling automatically updates the vaccine database according to the matching degree of the vaccines and population. Meanwhile, the algorithm efficiently combines queue management and virtual channel scheduling. Experimental results show that the algorithm has excellent evolution performance and can maintain smaller queue lengths, smaller packet loss rates, less delay for high-priority virtual channels, and also has preferable fairness.

Transmitter Design and Hardware Considerations for Different Space Modulation Techniques

Space modulation techniques (SMTs), in which some or all of the data bits modulate a block of spatial constellation symbol, are promising candidates for future 5G wireless systems. They promise data rate enhancements while maintaining low energy consumption, hardware cost, and computational complexity. As such, they attracted significant research interest in the past few years. One of the major assets of SMTs is the assumption that they can operate with a single RF chain at the transmitter even though multiple antennas might be activated at one time instant. Thus far, this claim is anticipated in several research articles but the transmitter designs of the different SMTs with a single RF chain are not addressed yet in the literature. SMTs include different system configurations, such as spatial modulation, space shift keying, quadrature spatial modulation, and quadrature space shift keying. The required hardware components to implement a transmitter for each of these systems with the minimum number of RF-chains are discussed in this paper. In addition, hardware limitations and the impact of different hardware blocks on the overall system performance are discussed. Besides, a comparison among different schemes along with conventional spatial multiplexing algorithm in terms of power consumption, hardware cost, probability of error, and receiver computational complexity is presented. It is shown that some of these techniques can operate without any RF-chain while a single-RF chain is sufficient for other systems. Moreover, these schemes can be traded off in terms of energy savings, complexity, performance, and cost.

Efficient Upstream Bandwidth Multiplexing for Cloud Video Recording Services

The upsurge of cloud video recording (CVR) has gained increasing attention from the general public and entrepreneurs. With live video records archived in the cloud, the CVR paradigm enables various smart services by keeping track of activities in the monitored region from anywhere at any time. However, the limited upstream bandwidth affects the quality of surveillance when multiple distributed cameras share the same upstream link. To solve the problem, this paper proposes an efficient upstream bandwidth multiplexing algorithm to intelligently allocate upstream bandwidth for each live video stream while maximizing the overall utility from the perspective of a CVR user. Specifically, we formulate the upstream bandwidth multiplexing problem as a constrained stochastic optimization problem, and apply the technique of hierarchical approximation to solve it efficiently. Our algorithm can be extended to take the priority of video streams into account and allocate more upstream bandwidth to video streams with higher priorities. We explicitly prove the approximation ratio of the proposed algorithm. In addition, we also conduct extensive trace-driven simulations to verify the effectiveness of our algorithm. The simulation results show that our algorithm improves the overall CVR user utility by over 20% compared with other alternatives, and the average utility per bandwidth unit is guaranteed to be stable even when the number of video streams increases.

SP-CNN: A Scalable and Programmable CNN-Based Accelerator

Specialized accelerators have become prevalent in many mobile computing platforms for their ability to perform certain tasks, such as image processing, at a lower power cost than a generalized CPU or GPU. In this article, the authors focus on using cellular neural networks (CNNs) as a specialized accelerator. CNN is a neural computing paradigm that is well suited for image processing applications. However, hardware implementations were originally developed to handle only relatively small image sizes. The authors propose SP-CNN, an architecture and a multiplexing algorithm that provides scalability to CNN applications. The authors demonstrate the proposed multiplexing algorithms over a set of six image processing benchmarks and present a performance analysis of SP-CNN.

Upscaled sub‐pixel multiplexing of multi‐view images based on weighted view overlay

A sub-pixel multiplexing algorithm for generating multi-view images on an autostereoscopic three-dimensional (3D) display at high speed is proposed. Generally, sub-pixel multiplexing in an autostereoscopic 3DTV system is to assign R, G, B colour sub-pixels of multiple view images at the proper position on the display such that a proper view image can be seen in accordance with the viewer's position. The upscaled sub-pixel multiplexing algorithm proposed is composed of bilinear upscaling and a weighted view overlay. Even though upscaling multiple view images requires too much resources and increases system complexity, the proposed algorithm can significantly reduce complexity from an implementation point of view while providing high-quality 3D views. Specifically, the advantage of the proposed weighted view-overlay technique is that several overlaid view images decide the colour value of the sub-pixel, which results in increasing the subjective quality of view images. Through an experiment, it is confirmed that the image quality of generated multi-views with the proposed algorithms is notably better than the existing simple techniques.

SP-CNN: A Scalable and Programmable CNN-based Accelerator

Specialized accelerators have become prevalent in many mobile computing platforms for their ability to perform certain tasks, such as image processing, at a lower power cost than a generalized CPU or GPU. In this article, the authors focus on using cellular neural networks (CNNs) as a specialized accelerator. CNN is a neural computing paradigm that is well suited for image processing applications. However, hardware implementations were originally developed to handle only relatively small image sizes. The authors propose SP-CNN, an architecture and a multiplexing algorithm that provides scalability to CNN applications. The authors demonstrate the proposed multiplexing algorithms over a set of six image processing benchmarks and present a performance analysis of SP-CNN.

Fast reconstruction of off-axis digital holograms based on digital spatial multiplexing.

A method for fast reconstruction of off-axis digital holograms based on digital multiplexing algorithm is proposed. Instead of the existed angular multiplexing (AM), the new method utilizes a spatial multiplexing (SM) algorithm, in which four off-axis holograms recorded in sequence are synthesized into one SM function through multiplying each hologram with a tilted plane wave and then adding them up. In comparison with the conventional methods, the SM algorithm simplifies two-dimensional (2-D) Fourier transforms (FTs) of four N*N arrays into a 1.25-D FTs of one N*N arrays. Experimental results demonstrate that, using the SM algorithm, the computational efficiency can be improved and the reconstructed wavefronts keep the same quality as those retrieved based on the existed AM method. This algorithm may be useful in design of a fast preview system of dynamic wavefront imaging in digital holography.

Joint Spatial Division and Multiplexing for mm-Wave Channels

Massive MIMO systems are well-suited for mm-Wave communications, as large arrays can be built with reasonable form factors, and the high array gains enable reasonable coverage even for outdoor communications. One of the main obstacles for using such systems in frequency-division duplex mode, namely, the high overhead for the feedback of channel state information (CSI) to the transmitter, can be mitigated by the recently proposed joint spatial division and multiplexing (JSDM) algorithm. In this paper, we analyze the performance of this algorithm in some <bold xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>realistic</i></b> propagation channels that take into account the partial overlap of the angular spectra from different users, as well as the sparsity of mm-Wave channels. We formulate the problem of user grouping for two different objectives, namely, maximizing spatial multiplexing and maximizing total received power in a graph-theoretic framework. As the resulting problems are numerically difficult, we proposed (sub optimum) greedy algorithms as efficient solution methods. Numerical examples show that the different algorithms may be superior in different settings. We furthermore develop a new, “degenerate” version of JSDM that only requires average CSI at the transmitter and thus greatly reduces the computational burden. Evaluations in propagation channels obtained from ray tracing results, as well as in <bold xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>measured</i></b> outdoor channels, show that this low-complexity version performs surprisingly well in mm-Wave channels.

A Novel Packet Channel Multiplexing Control Algorithms of AOS

The tradition packet channel multiplexing control algorithm of Advanced Orbiting Systems has the obvious disadvantages such as high time delay, high packet loss probability and low system throughput. Those depress the capability of the space communications badly. Based on the packet parameters, a new packet channel multiplexing control algorithm is proposed to optimize the tradition fixed multiplexing time. Under the prerequisite to ensure the maximal multiplexing efficiency, the processing time of packet channel multiplexing is limited, the packet loss probability is depressed, and the multiplexing throughput is advanced effectively.

Multiplexing the Elementary Streams of H.264 Video and MPEG4 HE AAC v2 Audio, De-multiplexing and Achieving Lip Synchronization

Television broadcasting applications such as ATSC-M/H, DVB[16] require that the encoded audio and video streams to be transmitted across a network in a single transport stream containing fixed sized data packets that can be easily recognized and decoded at the receiver. MPEG2 part1 specifies two layers of packetization to achieve a transport stream suitable for digital transmission. In a broadcasting system, multiplexing is a process in which two or more elementary streams are converted into a single transport stream ensuring synchronous playback of the elementary streams and proper buffer behavior at the decoder. This paper presents a scheme to multiplex the elementary streams of H.264 video and HE AAC v2 audio using the MPEG2 systems specifications[4], then de-multiplex the transport stream and playback the decoded elementary streams with lip synchronization or audio-video synchronization. This paper briefly introduces the MPEG2 systems, two layers of packetization namely program elementary stream (PES) and transport stream (TS). It also introduces the concept of timestamps. The proposed multiplexing and de-multiplexing algorithms followed to achieve synchronization are explained. It is shown that during decoding the audio-video synchronization is achieved with a maximum skew of 13ms.