Duplex Communication Research Articles

Self-Interference Cancellation in Full Duplex Communication using Steepest Descent Method

The present-day communication system uses Frequency Division Duplex (FDD) to emulate the benefits of Full Duplex Communication. But it requires more bandwidth as the cost of the spectrum is very high it becomes a major limitation. To overcome this problem implementation of Full Duplex Communication is the best solution. Implementation of full duplex communication is difficult because of a significant problem called self-interference. while transmitting and receiving signals on the same frequency band, receiving signal is interfered with the transmitted signal this phenomenon is called self-interference. The objective of this project is to minimize that self-interference signal from the received signal by using signal processing technique, LMS echo cancellation. Least Mean Square (LMS) echo canceller whose coefficients are updated iteratively is used to cancel the self-interference. An algorithm based on steepest descent method is used to obtain coefficients that change iteratively with varying step size to solve Weiner-Hopfs equation.

Miniaturized microstrip patch antenna with high inter‐port isolation for full duplex communication system

In this paper, an antenna is presented for in-band full duplex technology. This antenna includes a microstrip patch and a new 180° hybrid coupler. The designed 180° hybrid coupler has new structure that miniaturizes the entire system and also eliminates the self-interference signal that leaks from transmitter to receiver. In this antenna, at 2.4 GHz, an isolation between transmit and receive ports is more than 79 dB. Additionally, in this antenna, the measured inter-port isolation is better than 68, 72, and 74 dB for 80, 50, and 20 MHz bandwidths respectively in 10 dB return loss impedance. The dimensions of the designed antenna are 68 mm × 60 mm, and in compare with similar designed antenna is considerably smaller (more than 60%) with acceptable isolation.

Unsupervised Deep Learning for Massive MIMO Hybrid Beamforming

Hybrid beamforming is a promising technique to reduce the complexity and cost of massive multiple-input multiple-output (MIMO) systems while providing high data rate. However, the hybrid precoder design is a challenging task requiring channel state information (CSI) feedback and solving a complex optimization problem. This paper proposes a novel RSSI-based unsupervised deep learning method to design the hybrid beamforming in massive MIMO systems. Furthermore, we propose i) a method to design the synchronization signal (SS) in initial access (IA); and ii) a method to design the codebook for the analog precoder. We also evaluate the system performance through a realistic channel model in various scenarios. We show that the proposed method not only greatly increases the spectral efficiency especially in frequency-division duplex (FDD) communication by using partial CSI feedback, but also has near-optimal sum-rate and outperforms other state-of-the-art full-CSI solutions.

FARMART: COMPLETE SOLUTION OF SMART FARMING

With the increase in technology related to IoT, the concepts are being readily applied to Smart Agriculture that can help in providing data about the land as per the provided input. The farmart is a complete solution of smart farming. Which is developed for the farmers to optimize use of water for agricultural crop. As water supply is becoming a scare in today’s life it is important to adopt the smart solution in farming also. The project describes how irrigation can be handle smartly using IOT. This project can help farmers to save their time and give complete information about the soil and climate by which farmers can decide when crop needs water and as it’s a smart farming it can be done automatically by the farmart. The primary aim of the project is used for detecting soil moisture and climate condition and depending on the condition it sprinkle the water in field. And this entire information is sent to user’s mobile phone through SMS. This system involves using a WSN with different sensor which help farmart to take action. And this whole system is programmed into a microcontroller which control the irrigation system and quantity of water being used. And then send this information to user with the help of duplex communication channel working on an interface of cellular-internet which allow user to get every information on his phone through an app and a webpage.

A tuneable rat-race coupler for full duplex communications

AbstractFull duplex (FD) could potentially double wireless communications capacity by allowing simultaneous transmission and reception on the same frequency channel. A single antenna architecture is proposed here based on a modified rat-race coupler to couple the transmit and receive paths to the antenna while providing a degree of isolation. To allow the self-interference cancellation (SiC) to be maximized, the rat-race coupler was made tuneable. This compensated for both the limited isolation of the rat race and self-interference caused by antenna mismatch. Tuneable operation was achieved by removing the fourth port of the rat race and inserting a variable attenuator and variable phase shifter into the loop. In simulation with a 50 Ω load on the antenna port, better than −65 dB narrowband SiC was achieved over the whole 2.45 GHz industrial, scientific and medical (ISM) band. Inserting the S-parameters of a commercially available sleeve dipole antenna into the simulation, better than −57 dB narrowband SiC could be tuned over the whole band. Practically, better than −58 dB narrowband tuneable SiC was achieved with a practical antenna. When excited with a 20 MHz Wi-Fi signal, −42 dB average SiC could be achieved with the antenna.

MODERN APPROACHES TO THE ORGANIZATION OF A RELIABLE JAM–RESISTANT AND SECURED SATELLITE COMMUNICATION CHANNEL WITH UNMANNED AERIAL VEHICLES

At the present stage of development of unmanned aircraft systems work continues at a rapid pace to further improve their capabilities in the direction of more effective combat and special tasks.
 This is especially noticeable in two key areas: increasing the range and flight duration; reducing the physical size of the unmanned aerial vehicles.
 The combination of increasing flight duration and decreasing design characteristics significantly affects the requirements for unmanned aircraft system communication equipment and the development of a beyond line of sight satellite communication channel, which is currently considered as the main channel for transmitting intelligence, telemetry information in real time. Under existent warfighting conditions, the development of communication lines on the principle of a beyond line of sight with the use of ground or airborne relay stations, or through the introduction of additional ground control stations is virtually unjustified, due to the high dynamics of operational conditions and time constraints for decision making.
 In this context, the unmanned aerial vehicles' satellite communication channels are subject to strict requirements to ensure the combat missions are carried out successfully and safely.
 The article examines current approaches to the implementation of satellite communication channels with unmanned aerial vehicles in the context of the requirements for both on–board equipment and directly to the development of a satellite communication channel. Recommendations are given for the basic requirements for the organization of satellite duplex communication beyond line–of–sight with unmanned aerial vehicles based on geostationary (medium-altitude) high throughput satellites in the Ka frequency range.

All-Digital, Radio-Over-Fiber, Communication Link Architecture for Time-Division Duplex Distributed Antenna Systems

Radio-over-fiber is a popular technique to establish communication links between a central location and many remote antenna units. Many different architectures are available for the downlink, i.e., for the communication link from the central unit to the remote antennas. On the contrary, the low-cost and low-complexity requirement of the remote units makes it difficult to devise architectures suitable for the uplink, i.e., for the communication link from the remote antennas to the central unit. In this article, we address this and propose a low-complexity, all-digital, time-division-duplex communication architecture. For the downlink, a band-pass sigma-delta-over-fiber is employed. In the receive mode, the uplink includes an all-digital pulse-width-modulation technique. The received radio frequency (RF) signal is quantized into a binary stream through comparison with a tailored reference signal provided by the central unit. The direct quantization of the RF signal eliminates any need for local-oscillator and mixer stages at the remote units. The performance of the proposed architecture is investigated through extensive simulations and measurements. For instance, the all-digital, time-division duplex communication link provides -30.0 dB and -25.5 dB normalized mean square error signal quality through downlink and uplink communication with 20-MHz, 64-quadrature amplitude modulation signals centered at 2.365-GHz, respectively.

ALMS Loop Analyses With Higher-Order Statistics and Strategies for Joint Analog and Digital Self-Interference Cancellation

Joint analog and digital self-interference cancellation (SIC) is essential for enabling in-band full duplex (IBFD) communications. Analog least mean square (ALMS) loop is a promising low-complexity high-performance analog SIC technique with multi-tap adaptive filtering capability, but its properties on the tap coefficient variation have not been fully understood. In this paper, analysis based on higher-order statistics of the transmitted signal is performed to solve the problem of evaluating the variance of the ALMS loop’s weighting coefficient error, which reveals two additional types of irreducible residual self-interference (SI) produced by an ALMS loop if it runs freely. The residual SI channel impulse response in digital baseband is also analysed and its unique properties are investigated. By introducing a simple track and hold control to the ALMS loop’s tap coefficients, a joint analog and digital SIC scheme is proposed to stop the tap coefficient variation and achieve very low residual SI close to the IBFD receiver’s noise floor. In a coordinated application scenario, the noise figure of the digital SIC algorithm is proved to be only 1.76 dB at most. Simulation results are provided to verify the theoretical analyses.

Throughput maximization for UAV-assisted wireless powered D2D communication networks with a hybrid time division duplex/frequency division duplex scheme

In this paper, we investigate a low-altitude unmanned aerial vehicle (UAV)-assisted wireless power- ed device-to-device (D2D) network with the “harvest-transmit-store” model, where a UAV broadcasts energy to all D2D transmitters and the transmitters then store or use the energy for transmission information. In the proposed model, the UAV does not transmit energy in the transmission information time, resulting in a limited charging time. In addition, the interference may be caused by communicating information of an arbitrary number of D2D pairs simultaneously. In this paper, we propose a hybrid time division duplex/frequency division duplex communication scheme, which performs the power transfer and information transmission simultaneously in the transmission information time. The scheme cancels the cochannel interference by using the time division duplex scheme and guarantees the charging time by using the frequency division duplex. We consider optimizing the throughput based on the scheme via joint power control, spectrum allocation, and scheduling time. We propose a two-step algorithm to solve the formulated nonconvex problem. The simulation results show that the proposed algorithm improves the average throughput compared to the other schemes.

Integrated Linear and Nonlinear Digital Cancellation for Full Duplex Communication

Full duplex (FD) communication has the potential to double the throughput of wireless links while occupying the same bandwidth of half duplex communication. To enable FD communication, the self-interference (S1) signal is to be suppressed down to the noise floor. S1 cancellation can be achieved via antenna suppression, active analog cancellation, and digital cancellation. At high transmit power levels, the nonlinear behavior of the transceiver hardware degrades linear S1 channel estimation; hence, S1 cancellation results in reduced total suppression. In this article, we review nonlinear DSIC solutions in the literature, and we present a comprehensive integrated linear and nonlinear digital S1 cancellation framework with nested and residual approaches, where nonlinear algorithms, memory polynomial, support vector regression, and orthonormalized least mean squares algorithms are implemented together with linear cancellation. The performance of the proposed integrated framework is evaluated in comparison with well-known nonlinear digital cancellation techniques by implementing all techniques on the same software defined FD radio setup, consisting only of a single antenna and a WARP v3 board. It is shown that the integrated residual approach can enhance the total S1 suppression performance significantly by up to 7 dB as compared to linear-only digital S1 cancellation and by up to 4 dB with respect to existing nonlinear-only techniques observed at moderate power levels, and the integrated nested approach can provide an improvement of up to 6 dB over linear-only and 3 dB over nonlinear-on-ly digital S1 cancellation for high power settings. All schemes are also evaluated in terms of training overhead and computational complexity, providing insights about the trade-off between cost and performance at different power levels.

Guest Editorial: Full Duplex Communications Theory, Standardization, and Practice

Mobile data traffic grew by more than 50 percent between the first quarters of 2019 and 2020 and is projected to grow by close to a factor of 5 to reach 164 exabytes per month by 2025. This insatiable demand for mobile broadband communication services, including video, social networking, web browsing, audio, software updates, and peer-to-peer file sharing, has been driven by both the rising number of smartphone subscriptions and the increasing average data volume per subscription [1].

Sum-rate optimization for NOMA based two-tier hetnets with massive MIMO enabled wireless backhauling

In this paper, massive MIMO and NOMA techniques are jointly considered in a two tier heterogeneous network for accommodating huge traffic. In addition, full duplex communication is used at SBS to enhance system performance. First, SINR and rate equations are modeled while considering imperfect channel state information and zero-forcing beamforming. In the proposed framework, both macro base station and small cell base station can serve multiple users by using NOMA. Since, existing literature mainly focuses on orthogonal multiple access (OMA) based UA schemes, it is necessary to re-design user association (UA) schemes for NOMA. Hence, based on the proposed framework, a joint UA and power allocation (PA) optimization problem is designed with the perspective of optimizing the sum-rate of the system while accounting for quality of service and backhaul constraints. Since, the initially formulated problem is non-convex, a distributive algorithm is propounded where a joint problem is separated into two convex subproblems (viz., UA and PA). Furthermore, the complexity of the proposed algorithm is examined and Jain’s fairness index is measured. Simulation results demonstrate the effectiveness of the proposed algorithm by comparing with optimal solution and other base-line algorithms.

MODELING A NETWORK OF UNMANNED AERIAL VEHICLES

The research concerns the methods of UAV group control in networks with duplex communication between nodes built on the "client-server" architecture. Such systems belong to self-organized networks with variable topology. It is important to study the allowable parameters of deviation from the task in the management of a group of UAVs and analysis of the network topology for the group flighting. The network was optimized according to the Ant Colony algorithm ACO. The application of different types of algorithms prevents routing problems in networks, such as ANTMANET, AntNet, ACODV and others. Methods of coordination of group joint actions are considered. A method is proposed by which the optimal number of UAVs operated by one operator can be determined and the traffic intensity of the communication channel is calculated, as well as the bandwidth and packet transmission delay are estimated.

Operation and Control of Microgrids Using IoT (Internet of Things)

The current microgrid power management system is undergoing a significant and drastic overhaul. The integration of existing electrical infrastructure with an information and communication network is an inherent and significant need for microgrid classification and operation in this case. Microgrid technology’s most important features: 1) Full duplex communication; 2) Advanced metering infrastructure; 3) Renewable and energy resource integration; 4) Distribution automation and complete monitoring, as well as overall power system control. A microgrid’s communication infrastructure is made up of several hierarchical communication networks. Microgrid applications can frequently be found in numerous aspects of energy consumption. Because it provides a spontaneous communicational network, the Internet of Things plays a fundamental and crucial role in Microgrid infrastructure. This paper covers the deployment of a comprehensive energy management system for microgrid communication infrastructure based on the Internet of Things (IoT). This paper discusses microgrid operations and controls using the Internet of Things (IoT) architecture. Microgrids make use of IoT-enabled technologies, in conjunction with power grid equipment, which are enabling local networks to provide additional services on top of the essential supply of electricity to local networks that operate in parallel with or independently of the regional grid. Local balancing, internal blockage management, and request for support marketplace or grid operator activities are examples of auxiliary services provided by the microgrid that can add value to each end-user and other true stakeholders. Different technologies, architectures, and applications that use IoT as a key element with the main purpose of preserving and regulating innovative smart microgrids in accordance with modern optimization features and regulations are designed to update and improve efficiency, resiliency, and economics.

P2P (Bilateral) Communication Between Nodemcu Esp8266 Boards Using Arduino Ide

"Bilateral communication between the boards NodeMcu ESP826 is achieved using the WI FI capabilities of these devices and particularly code based on Arduino IDE. The system is used to control servos, DC motors or led. The duplex communication allows feedback action between sender and receiver. Real time feedback is obtained by particularly connection of the servo to the board. Keywords: Bilateral communication, NodeMcu ESP8266, Arduino. "

On-chip broadband nonreciprocal light storage

AbstractBreaking the symmetry between forward- and backward-propagating optical modes is of fundamental scientific interest and enables crucial functionalities, such as isolators, circulators, and duplex communication systems. Although there has been progress in achieving optical isolation on-chip, integrated broadband nonreciprocal signal processing functionalities that enable transmitting and receiving via the same low-loss planar waveguide, without altering the frequency or mode of the signal, remain elusive. Here, we demonstrate a nonreciprocal delay scheme based on the unidirectional transfer of optical data pulses to acoustic waves in a chip-based integration platform. We experimentally demonstrate that this scheme is not impacted by simultaneously counterpropagating optical signals. Furthermore, we achieve a bandwidth more than an order of magnitude broader than the intrinsic optoacoustic linewidth, linear operation for a wide range of signal powers, and importantly, show that this scheme is wavelength preserving and avoids complicated multimode structures.

Design and research of computer room communication system based on electronic information technology

No new building can be built without the computer room. The computer room is just like the soul of the information system. The construction of any large-scale information system is inseparable from the support of network, host and other communication equipment. This paper studies the optimization of the whole communication system. From the five aspects of practicality and advanced nature, safety and reliability, standardization, flexibility and extensibility, and manageability, the paper introduces the principles of building the communication system of electronic information room, and forms a complete set of communication system design for electronic information room. At present, serial communication is commonly used in electronic information communication system. The communication mode is half duplex communication of fd-mac layer protocol to improve the communication throughput. It is suitable for communication in electronic information room because of its fast transmission speed and space saving.

A low‐complexity pilot contamination elimination method for channel estimation in massive MIMO systems

SummaryPilot contamination is a major limitation in estimating the uplink channel state in massive MIMO systems using time division duplex communication method. This limitation has a huge impediment to harnessing the main advantages of massive MIMO systems such as spectral and energy efficiencies. In this article, a new low‐complexity subspace‐based method is proposed for eliminating pilot contamination and channel estimation, which exploits virtual channel modeling combined with a new problem formulation technique. On the contrary to most of the existing approaches in which the availability of correlation matrices of users and intercell data exchanges are needed, the proposed method eliminates the pilot contamination without need these confining assumptions. By employing the virtual beam searching technique and projection onto the component subspaces of virtual beams and pilot sequences, the proposed method estimates channel vectors of different cell users with very low computational complexity. Simulation results show that the proposed method achieves good performance with very low normalized mean square error and high achievable rates in the presence of severe pilot contamination and under different cell conditions.

Interrupt Enabled Priority Based Master Slave Communication using SPI Protocol

Serial Peripheral Interface or SPI is a synchronous serial communication protocol that provides full – duplex communication at very high speeds. It is a master – slave type protocol that provides a simple and low-cost interface between a microcontroller and its peripherals. This paper proposes the design of a priority-based master slave communication system using SPI Protocol that enables the system to operate using interrupts. The design mainly emphasizes on priority-based communication where the slaves will generate an interrupt over a newly defined interrupt pin when some data transfer needs to happen. When the master receives an interrupt from the slave it establishes communication with one slave at a time based on the priority and the priority to each slave is assigned by the arbiter or priority control block. The highest priority slave is served first. Shift register is used to store and transfer the data bit by bit and it resets every time a data transfer is complete. The design proposed here can be implemented in different applications which involve the peripherals that can support SPI protocol for communication such as LCDs, Analog to Digital Converter, Digital to Analog Converter, Memory Cards, Temperature Sensor, Pressure Sensor. In this work, a single master multi slave architecture is considered. The design given in this paper can be scaled up to support more than four slaves.

The Influence of Corporate Social Responsibility (CSR) and Social Media on the Strategy Formulation Process

The current theory on strategy formulation is based significantly on environmental analysis and leveraging strategic capability. There is limited understanding of how corporate social responsibility (CSR) and social media strategies could develop the strategy formulation to improve strategic outcomes. The input into the strategic formulation process does not tend to take account of customers’ inclination for CSR practices and policies. This is particularly important for consumers who can spurn organisations that do not incorporate ethical practices in their core values. The paper aims to show that social media is an inclusive tool, because of the duplex communication techniques that enhance it, and CSR is complementary to building a robust strategic planning process. The methodology is a qualitative case study using a reflective perspective based on a complete participant role. The results demonstrate that there are challenges in operating a strategic planning process that is situated in an uncertain, volatile and dynamic business environment; it requires an integrated partnership between the inter-organisational actors and other stakeholders. Social media is the integrator of resources and CSR helps to build relationships, acting as a reinforcer of trust.