TDMA System Research Articles

RIS-Assisted Cooperative Time-Division Multiple Access.

Reconfigurable intelligent surface-aided communication systems have been intensively investigated to improve capacity, coverage, and energy efficiency via optimal controlling of phase shifts for passive reflecting elements. However, there are few studies on cooperative transmission incorporating RIS in TDMA systems, because RIS reflects all the incident signals, and it inadvertently leads to a boost in interference signals. In this paper, we propose RIS-assisted cooperative time-division multiple access, in which the required SINR of all users is guaranteed as much as possible by opportunistic use of RIS for cooperative transmission. The proposed scheme's primary function is that some time slots, i.e., cooperative time slots, serve a pair of users, i.e., a strong- and a weak-channel-conditioned user, using RIS. To support this functionality, we propose scheduling for non-cooperative and cooperative time slots, user pairing for scheduled cooperative time slots, and transmit beamforming vector design for the pair of UEs in each cooperative time slot. The simulation and numerical results demonstrate that the proposed scheme guarantees QoS for all UE as much as possible and minimizes the remaining required capacity indicating the amount of capacity that was not achieved compared with the required capacity.

Smart Antenna Systems

Abstract: Smart antennas have received increasing interest for improving the performance of wireless radio systems. These systems of antennas include a large number of techniques that attempt to enhance the received signal, suppress all interfering signals, and increase capacity, in general. The main purpose of this article is to provide an overview of the current state of research in the area of smart antennas, and to describe how they can be used in wireless systems. A smart antenna takes advantage of diversity effect at the source (transmitter), the destination (receiver), or both. Diversity effect involves the transmission and/or reception of multiple radio frequency (RF) waves to increase data speed and reduce the error rate. Thus, this article provides a basic model for determining the angle of arrival for incoming signals, the appropriate antenna beamforming, and the adaptive algorithms that are currently used for array processing. Moreover, it is shown how smart antennas, with spatial processing, can provide substantial additional improvement when used with TDMA and CDMA digitalcommunication systems.

Flexible TDMA System for the Efficient Microwave Power Transmission to Multiple Power Receiver

Flexible TDMA System for the Efficient Microwave Power Transmission to Multiple Power Receiver

Research on a novel maritime emergency search system

With the continuous development of the marine economy and the inland river transport, traditional vessels supervision methods have the shortcomings of short supervision range, small supervision scope, and high cost, which make it difficult to meet the requirements of modern maritime supervision. This paper proposes a novel maritime emergency search system based on unmanned aerial vehicle (UAV) and its landing platform. The system takes the base station with the cruise UAV, as the base point. Subsequently, TDMA system networking technology and wireless bridge communication technology are used to set up a local area network. Then, the improved three-dimensional raster processing is used to search the target waters. After that, several algorithms such as area optimization based on image filtering are applied to classify, integrate, and fit the waters. In addition, the base station distribution scheme and the emergency equipment intelligent management system software are designed to achieve more efficient and convenient management of the system. The system realizes unmanned, visualized, and normalized monitoring and management of the target waters through the coupling of UAV, aerial protection base stations and control terminals, and provides more detailed and accurate information for the development of search and rescue work.

Inter-satellite time synchronization and ranging link assignment for autonomous navigation satellite constellations

The BeiDou Navigation Satellite System (BDS) has equipped its new-generation satellites with inter-satellite link (ISL) payloads for the autonomous operation. In the autonomous operation mode, the navigation constellation realizes the time unification and orbit determination through inter-satellite time synchronization and ranging, so as to self-maintain the time-space reference. For solving the problem of inter-satellite time synchronization and ranging link assignment for autonomous navigation constellations, assignment algorithms of time synchronization links based on satellite layers, as well as ranging links combining satellite selection and weighting, were proposed. The ISL assignment simulation of the BeiDou-3 global constellation was implemented using our algorithms, and the assignment was completed almost within 5 cycles. According to the statistical results, using 56.6% of ISL timeslots, the constellation had achieved the optimal mode of inter-satellite time synchronization with the least skips; the number of inter-satellite ranging links established per minute of each satellite was not less than 10, which met the constraint of the minimum links; the average PDOP of ranging links of the MEO, GEO and IGSO satellite was about 1, 1.6 and 1.5 respectively, close to the lower reference limit. It was demonstrated that the ISLs were reasonably assigned for the demand of inter-satellite time synchronization and ranging with constraints of the TDMA system, narrow beams, the quantity of payloads and inter-satellite visibility.

Extended analysis of Age of Information threshold violations

We study a scenario where a monitor is interested in the freshest possible update from a remote sensor. The monitor also seeks to minimize the number of updates that exceed a certain freshness threshold, beyond which, the information is deemed to be too old. Previous work has presented results for First Come First Served (FCFS) systems. However, it has been shown that Last Come First Served (LCFS) with preemption is more effective in terms of average Age of Information (AoI); we therefore study an M/G/1 LCFS system with preemption. The generality of the busy time distribution gives the advantage of applicability on any distribution inside the model. For example, one can use a deterministic distribution to study a TDMA system, a gamma distribution to model a routing network, or a more complicated distribution to study a CSMA access scheme. We find a general procedure to derive the exact expression of the outage update probability — i.e. the portion of time updates have information older than a certain threshold. We compare different busy time distributions to the ones already present in literature for equivalent FCFS systems, showing the benefit of using the former discipline. We further study how the variance of the busy time distribution affects the update outage probability. We find two instances of the busy time distribution, where at low thresholds and low loads, higher variance gives an advantage in terms of update outage probability. First, we compare the M/D/1 LCFS with preemption against the M/Γ/1 LCFS with preemption and let the variance of the busy time of the latter vary, while maintaining the same average busy time for both systems. We further compare various M/H2/1 LCFS with preemption with different coefficient of variation and same expected value, thus covering a wider spectrum of variation of the busy time.

NOMA-Based 802.11n for Industrial Automation

Industry 4.0 and Industrial Internet refer to the expected revolution in production, utility management and, in general, fully automated, interconnected and digitally managed industrial ecosystems. One of the key enablers for Industry 4.0 lies on reliable and timely exchange of information and large scale deployment of wireless communications in industry facilities. Wireless will bring solutions to overcome the main drawbacks of the current wired systems: lack of mobility, deployment costs, cable damage dependency and scalability. However, the strict requirements in reliability and latency of use cases such as Factory Automation (FA) and Process Automation (PA) are still a major challenge and a barrier for massive deployment of currently available wireless standards. This paper proposes a PHY/MAC wireless communication solution for FA and PA based on Non-Orthogonal Multiple Access (NOMA) in combination with the 802.11n standard. The communication system proposed aims at delivering two different sets of services. The first service class is composed of Critical Services (CS) with strict restrictions in reliability and latency. The same communication system should convey also a second group of services, referred as Best Effort (BE) with more relaxed boundary conditions. The proposal theoretical background, a detailed transmission-reception architecture, the physical layer performance and the MAC level system reliability are presented in this paper. The solution provides significantly better reliability and higher flexibility than TDMA systems, jointly with a predictable control-cycle latency.

Evaluating the interference from fixed wireless access TDMA systems into HAPS systems: a probabilistic approach

This study presents a probabilistic model to assess the co-channel interference produced by multiple transmitters of a fixed wireless access network into a high altitude platform stations (HAPS) victim receiver. The authors propose an alternative probabilistic approach that avoids the worst case assumptions usually considered in traditional interference calculation methods, by considering the random modelling of some of the technical parameters involved. More specifically, the geographic positions of fixed wireless access system transmitters are modelled by a two-dimensional point process and their antenna gains in the sidelobe region are modelled as gamma distributed random variables. The proposed method is validated by comparing the minimal operating distance resulting from the traditional deterministic interference calculation methods and that obtained with th proposed approach. Results corresponding to the four possible interfering scenarios indicate that the proposed probabilistic approach leads to a reduction in coordination distances.

Design of Location Algorithm for Marine Drone Aircraft Maintenance Base Station

In recent years, unmanned aerial vehicle Cruise search and Rescue is a research hotspot at home and abroad. Water traffic accidents in recent years have been increasing, the traditional maritime patrol is usually based on boat cruise, this mode of maritime patrol not only means heavy task, and with poor inspection effect. So UAV-based maritime cruise and emergency search and rescue system is the subject of this research. The system based on the navigation and search and rescue of two unmanned aerial protection base station, using TDMA system network technology and Wireless bridge communication technology to set up a local area network, and target water site to establish a multi-objective model, optimize the design of supporting base station location algorithm,the system realizes the unmanned, visualized and normalized monitoring and management of target waters by means of coupling the UAV, Air-base station and control terminal, and provides more detailed and accurate information for the development of cruise search and rescue work.

A Novel Uplink Multiple Access Technique Based on Index-Modulation Concept

Index Modulation (IM) concept is exploited to propose a novel uplink multiple access technique called, IM-multiple access (IMMA). In IMMA, part of the transmitted block for each user is used to modulate a complex symbol that is transmitted on a specific time slot determined by the remaining bits in that block. Concurrent transmissions from different users are probable in IMMA since the operating time slot for each user is individually selected and the scheme can be considered as a non-orthogonal multiple access (NOMA) technique. Yet, it is revealed that the error rate at the centralized receiver is better than other orthogonal multiple access schemes. Adopting a maximum likelihood detector to jointly decode all the transmitted blocks from various users is shown to be computationally complex. Hence, a reduced-complexity detection scheme is proposed where a substantial reduction in computational complexity of more than 50% is attained with a marginal performance penalty. Besides, an analytical upper bound of the average bit error rate (BER) and the probability of collision are derived in a closed form expression. It is also disclosed through simulation results that a significant enhancement in the BER is achieved for the proposed IMMA scheme as compared with the conventional TDMA system and to sparse code multiple access NOMA scheme.

Study on the Optimization and Performance of TDMA Allocation Algorithm in Ships’ Ad Hoc Networks

Abstract This paper analyzes the requirements of the information transmission network of ship integrated condition monitoring system, and proposes a design scheme of ship condition monitoring system based on wireless ad hoc network. The wireless ad hoc network protocol was designed, its networking process was analyzed in detail, and the network transmission performance of the monitoring system was tested. The results proved the feasibility of the system. The above solution can be used for the transmission of ship state information that satisfies the requirements of wireless transmission, and has important theoretical and practical significance. The slot allocation algorithm has been receiving extensive attention as an important part of the TDMA system research. This paper analyzes the summarization and summarization of TDMA time slot assignment algorithms from several aspects such as slot synchronization, existing slot allocation algorithm, and slot assignment model, laying an important foundation for researchers to do further research. In the TDMA system, time is divided into non-overlapping time frames, and the time frames are divided into non-overlapping time slots. Each node in the network performs corresponding operations in each time slot.

Phase State and Saturation Vapor Pressure of Submicron Particles of meso-Erythritol at Ambient Conditions.

meso-Erythritol is a sugar alcohol identified in atmospheric aerosol particles. In this work, evaporation of submicron-sized particles of meso-erythritol was studied in a TDMA system including a laminar flow tube under dry conditions at five temperatures (278-308 K) and ambient pressure. A complex behavior was observed and attributed to the formation of particles of three different phase states: (1) crystalline, (2) subcooled liquid or amorphous, and (3) mixed. With respect to saturation vapor pressure, the subcooled liquid and amorphous states are treated to be the same. The particle phase state was linked to initial particle size and flow tube temperature. Saturation vapor pressures of two phase states attributed to the crystalline and subcooled liquid state respectively are reported. Our results suggest a mass accommodation coefficient close to one for both states.

A Dynamic Time-slot Assignment for Ground Wireless Sensor Network

This paper is on the background of the applied communications of automated vehicle in the multi-hop environment. The paper provides a dynamic time-slot assignment protocol for the ground wireless sensor network (WSN), based on TDMA. By interacting of the two-hop neighboring nodes information, the protocol finishes the dynamic time-slot assignment, realizes the efficient and fair sharing of channel, reduces the transfer delay of the end-to-end burst data, meets the communication demand of assignment on-demand in WSN, and prolongs the life-time of the network with the virtual backbone mechanism. The theoretical analysis and simulation results showed that the protocol provided has better adaptability for the burst network services and topological variation, comparing to the traditional static mac layer protocol in the TDMA system. multiple address (TDMA), automated vehicle 1. Background WSN has widely used in various fields, especially in the military field. It is well suited to use in the wretched battlefield environment, including monitoring our forces, materials and equipment, keeping watch over the conflict zones, detecting the topography and defensive of the enemy, aiming the targets, assessing the damage, detecting the nuclear, biological and chemical attacks. WSN on the ground is disposed into three parts: the lowest part is the smallest and lowest power consumption attended sensor, the second part is the directional sensor which could assess the azimuth and the third part is the confirmed sensor which has a imaging ability. The first two parts only need slow communications (kbps) between each other and the communication distance is 100-400 meters. The confirmed sensor in the third part need two-speed or two transceivers (Mbps), the one is responsible for the communication with the lower node and the other one is responsible for the communication with the directorial node in a distance which could not exceed 10km. Based on the communication of the ground sensor by using unmanned vehicle in mobile multi-hop, a MAC protocols for the ground wireless network is designed, a TDMA-based dynamic TSA protocol is proposed, this protocol can complete the TSA process by the communication between two neighboring nodes, which can realize the sharing of the high-quality and fair-minded signal path, fulfilling the demand to distribute the communication according to need for the ground wireless network at the same time. This review is followed by an introduction. A brief summary of some of the relevant concepts is presented in Section 2.Section 3 demonstrates the protocol design. Section 4 is the theoretical performance study of the protocol. In Section 5, we discuss the preliminary results of a simulation study. Finally, conclusions and future work are summarized.

Estimation of quality of service parameters for OFDM–TDMA networks using Markov chains and service curve

SummaryThis paper presents a model based on Queueing Theory for Orthogonal Frequency‐Division Multiplexing–Time‐Division Multiple Access (OFDM–TDMA) networks. This network model requires a Markovian model to the traffic processes. Thus, we present a Markov Modulated Fluid Model (MMFM) with autocorrelation function fitting for the network traffic, in order to evaluate the performance of the transmission link in OFDM–TDMA systems. That is, we deduce equations for estimating QoS parameters of OFDM–TDMA systems. The obtained results confirm that the proposed network model is efficient in describing the OFDM based link performance. A novel equation is also introduced for estimating the buffer overflow probability in OFDM–TDMA systems using a proposed network service curve. The computational effort is reduced compared to the Queueing Theory based method of overflow probability estimation. Besides, the results show that the estimates are very close to those obtained by simulations.

ECCT: An Efficient-Cooperative ADHOC MAC for Cluster-Based TDMA System in VANETs

In VANETs, a clustering algorithm can be used to partition the network into smaller segments. Therefore, the clustering algorithms provide not only limited channel contention but also fair channel access within the cluster. In addition, they also increase spatial reuse in VANETs and efficient control for the network topology. The main concern in the clustering algorithm is the cluster stability. The major challenge is to elect a cluster head and to maintain the membership of member nodes in a highly dynamic and a fast-changing topology. Therefore, the major criterion for cluster formation is to form a stable cluster. In this paper, a clustering algorithm to affect organization and cooperative ADHOC MAC for cluster-based TDMA system in VANETs (ECCT) is proposed. The cooperation is used to help a cluster head update each neighbor cluster's information which helps each cluster head to avoid collision when two clusters move into each other's cluster's transmission range. This efficiently utilizes a time slot. We use the lowest-ID algorithm to achieve organization. The analytical and simulated results show that not only the average number of time slots for electing a cluster head but also total number of time slots before data can be successfully transmitted is less than the existing cluster-based TDMA system and IEEE 802.11p.

Estimation of Backlog and Delay in OFDM/ TDMA Systems with Traffic Policing Through Network Calculus

In this paper, we firstly propose a policing algorithm based on multifractal traffic modeling, evaluating its performance in comparison to other algorithms. Further, we present an approach based on Network Calculus for estimating quality of service parameters, such as mean queue length (backlog) and delay. We analyze these two parameters for an OFDM/TDMA based simplified Wimax system with and without the application of traffic modeling based policing algorithms. We also evaluate the performance of the proposed algorithm in policing the traffic in an OFDM / TDMA system.

Minimization of the Fabrication Cost for a Bridged-Bus-Based TDMA System under Hard Real-Time Constraints

Minimization of the Fabrication Cost for a Bridged-Bus-Based TDMA System under Hard Real-Time Constraints

Novel Real-Time Closed-Loop Device Linearization via Predictive Pre-Distortion

In this paper, a novel real-time closed-loop device linearization technique has presented. In this paper the focus application is on AM/AM and AM/PM linearization of power amplifiers (PA) and/or radio transmitters. In such an application, the novel approach performs on-the-fly measurement-and-prediction of the nonlinear characteristics of the PA, stores such non-linear characteristics and calculates their inverse functions in order to pre-distort the base-band amplitude and phase signals modulating the PA such that the combination, or the resultant, of the pre-distorter and the PA leads to a linear behavior at the output of the PA. The predictive nature of the presented approach overcomes the inevitable delay between the time a measurement is collected through the feedback loop and the time it has taken place at the output of the forward loop, which is a must-have delay encountered in any natural causal system. Such a delay results in imperfect on-the-fly pre-distortion of the output signal due to the mismatch between the applied pre-distortion, which has been based on a past measurement, and the actual effect of the non-linearity at the time the signal is produced [5]. In addition, this novel approach promises the advantage of operating a highly non-linear (compressed) PA - hence, highly efficient - with minimal factory pre-calibration. We present a model of our predictor based approach and evaluate its performance for a GSM/EDGE/UMTS a cellular transmitter scenario, where the performance requirements on the transmitted signal are stringent and distortion due to non-linearity must be minimized. The key performance metrics we evaluate have mostly been based on the GSM/EDGE/UMTS requirements, such as the Error Vector Magnitude (EVM), Switching Transients (ST), and Adjacent Channel Power Ratio (ACPR), transmit time mask, modulation spectrum and power-added efficiency (PAE). Although the focus of the numerical results in this paper is on the GSM/EDGE/UMTS application, the novel approach discussed is applicable to any TDMA or TDD system where switching transients and spectral performance is tightly controlled.

한국형 전술데이터링크 시스템 구현을 위한 무선모뎀 시스템 설계

Next Generation Weapon system from the center of the platform to share information in real-time Network Centric Warfare(NCW: Network Centric Warfare) has been changed. Data link system is defined as a network. That is, all in real-time battlefield information is to enable sharing. Data link system is classified as a precision strike, Monitoring/control, control of a Patriot missile battery systems. These systems are most effective in a Joint warfare and precision strike. Data Link Systems(Data Communications) implementation is accomplished by using the KDLM(Korean Data Link Modem) and Radio Transceiver. KDLM is operated in conjunction with the legacy Radios(re-using fielded HF/VHF/UHF radio systems). In this paper, we describe in terms of KDLM system design. In this paper, the proposed design structure is how to effectively interact with legacy various radio. First, The results provide an analysis of that Dynamic TDMA system and apply modem structure. Radio characteristics data are necessary for an effective TDMA system design. This article analyzes the test results and describes the structure to improve the receive performance.

A Simulation Research of Binary Anti-Collision Algorithms in RFID System

An Anti - collision Algorithms technique would be required in RFID system to reduce conflicts and identify several tabs very quickly and accurately.Binary Search algorithm in a TDMA system is the most usual type of Anti - collision Algorithms in RFID System. This paper puts forward programming and simulating by using MATLAB based on EPCs Binary Search algorithm .Finally the results are compared and analyzed at the end of the paper and the author gives some pieces of advice.