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Yan, Zhongjiang, Qianqian Li, Bo Li, and Mao Yang. "A Link Distance Division Based Time Division Multiple Access Protocol for Directional Aeronautical Relay Networks." Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University 38, no. 1 (February 2020): 147–54. http://dx.doi.org/10.1051/jnwpu/20203810147.
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In directional aeronautical relay networks, the airplane relay explores the advantages of the directional antenna, in terms of long transmission distance, low transmission power, small interference range and so on, to help the ground nodes transmitting data. However, data transmission delay extension problem occurs when the distance of the transmission link extends, where the wireless signal transmission time approximates the data transmission time such that the wireless signal transmission time cannot be omitted. To address the data transmission delay extension problem, a link distance division based time division multiple access protocol, LDD-TDMA, is proposed in this paper. Different from the traditional TDMA protocol, where the time slots are equal and are determined by the longest transmission link, the length of the time slots are different and are determined by different transmission links. Furthermore, the concept of communication coverage ring is proposed where the nodes located in the same ring communicate with the relay utilizing the same time slot length. The relationships between the number of rings, the ring radius and the transmission range of the LDD-TDMA are modelled and derived as a closed formula, where the ring radius are optimized such that the gain is maximized. Simulation results show that LDD-TDMA outperforms TDMA by 13.37% when the transmission range is 200 km and the ring number is 4.
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Rom, Raphael, and Moshe Sidi. "Message Delay Distribution in Generalized Time Division Multiple Access (TDMA)." Probability in the Engineering and Informational Sciences 4, no. 2 (April 1990): 187–202. http://dx.doi.org/10.1017/s0269964800001546.
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In the classical TDMA, which has been the subject of extensive research in the past, a single slot is allocated to each and every user within every frame. In many situations this leads to an inefficient utilization of the channel calling for a nonhomogeneous allocation of slots. This paper focuses on a generalized TDMA scheme in which users are allocated more than a single slot per frame, not necessarily contiguous. We derive the delay distribution and buffer occupancy for such a scheme as well as the expected values of these quantities.
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Gupta, Ashi. "Faster and Efficient Time Division Multiple Access (TDMA) System." International Journal of Advanced Research in Computer Science and Software Engineering 8, no. 3 (March 30, 2018): 11. http://dx.doi.org/10.23956/ijarcsse.v8i3.586.
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In this paper the author has developed a new design to implement the TDMA(Time division multiple access) system. It is a verilog code that is simulated on the “Mentor graphics MODEL SIM- ALTERA 10.1d(QUARTUS II 13.0) “ software. It allows several users to share the same frequency channel by dividing the signal into different time slots. It takes requests from the users, processes them and provide grants to the users one by one according to the priority set, in one clock cycle per grant better than the previous design which takes more than 2 cycles to process 1 request.
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Elmissaoui, Taoufik. "Time Division Multiple Access for Remote Lab (TDMA-RL)." International Journal of Online and Biomedical Engineering (iJOE) 18, no. 07 (June 14, 2022): 4–13. http://dx.doi.org/10.3991/ijoe.v18i07.29773.
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The new technologies development has enabled us to build a remote lab system for multiple disciplines. The remote lab system becomes an essential for eLearning system. Multiple solution has been provided in the literature for building remote laboratory. All existing and commercialized system do not provide the multiusers process at the same time. In fact, each student must make a reservation before using the remote lab. In this paper, we have proposed and tested a new method that enable multi student to have the benefits of the remote laboratory at the same time. Our solution is based on the Time Division Multiple Access for Remote Lab (TDMA-RL). Each student can use the laboratory equipment at a fixed slot time. Our application can manage the frame send for each learner. The remotely learner can not feel the existing of the other persons due to the equipment speed and the good management time of application. The number of users varies the equipment lab characteristics.
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Akizuki, Osamu, Shingo Suzuki, Shinjirou Ooshita, and Kouichi Mutsuura. "Time division multiple access with parallel transmission: TDMA/PT." Electronics and Communications in Japan (Part I: Communications) 80, no. 5 (May 1997): 1–10. http://dx.doi.org/10.1002/(sici)1520-6424(199705)80:5<1::aid-ecja1>3.0.co;2-p.
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Miriampally, Venkata Raghavendra, G. Subba Rao, and V. Sudheer Raja. "Determination of Number of Channels in Multiple Access Techniques for Wireless Communications." International Journal of Informatics and Communication Technology (IJ-ICT) 4, no. 1 (April 1, 2015): 1. http://dx.doi.org/10.11591/ijict.v4i1.pp1-6.
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<p>In wireless communications system, it is desirable to allow the subscriber to send simultaneously information to the base station while receiving information from base station. Multiple access techniques are used to allow many mobile users to share simultaneously a finite amount of radio spectrum. Frequency division multiple access (FDMA), time division multiple access(TDMA), and code division multiple access (CDMA) are the three major access techniques used to share the available bandwidth in a wireless communication system. In this paper we calculated the number of channels required for FDMA & TDMA techniques depending on various factors such as spectrum, channel band width etc.</p>
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Yun, Changho, and Yong-Kon Lim. "GSR-TDMA: A Geometric Spatial Reuse-Time Division Multiple Access MAC Protocol for Multihop Underwater Acoustic Sensor Networks." Journal of Sensors 2016 (2016): 1–14. http://dx.doi.org/10.1155/2016/6024610.
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The nonnegligible propagation delay of acoustic signals causes spatiotemporal uncertainty that occasionally enables simultaneous, collision-free packet transmission among underwater nodes (UNs). These transmissions can be handled by efficiently managing the channel access of the UNs in the data-link layer. To this end, Geometric Spatial Reuse-TDMA (GSR-TDMA), a new TDMA-based MAC protocol, is designed for use in centralized, multihop underwater acoustic sensor networks (UASNs), and in this case all UNs are periodically scheduled after determining a geometric map according to the information on their location. The scheduling strategy increases the number of UNs that send packets coincidentally via two subscheduling configurations (i.e., interhop and intrahop scheduling). Extensive simulations are used to investigate the reception success rate (RSR) and the multihop delay (MHD) of GSR-TDMA, and the results are compared to those of previous approaches, including C-MAC and HSR-TDMA. GSR-TDMA outperforms C-MAC; the RSR of GSR-TDMA is 15% higher than that of C-MAC, and the MHD of GSR-TDMA is 30% lower than that of C-MAC at the most. In addition, GSR-TDMA provides even better performance improvements over HSR-TDMA; the RSR of GSR-TDMA is 50% higher than that of HSR-TDMA, and the MHD of GSR-TDMA is an order of102lower than that of HSR-TDMA at the most.
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Li, Fuyou, Feng He, Zhen Dong, Manqing Wu, and Yongsheng Zhang. "General Signal Model for Multiple-Input Multiple-Output GMTI Radar." Sensors 18, no. 8 (August 6, 2018): 2576. http://dx.doi.org/10.3390/s18082576.
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Multiple-input multiple-output (MIMO) ground moving target indication (GMTI) radar has been studied recently because of its excellent performance. In this paper, a general signal model is established for the MIMO GMTI radar with both fast-time and slow-time waveforms. The general signal model can be used to evaluate the performance of the MIMO GMTI radar with arbitrary waveforms such as the ideal orthogonal, code division multiple access (CDMA), frequency-division multiple access (FDMA), time division multiple access (TDMA), and Doppler division multiple access (DDMA) waveforms. We proposed a range-compensation method to eliminate the range-dependence of the FDMA waveforms. The simulation results indicate that the improved performance of FDMA waveforms is achieved utilizing the range-compensation method.
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Saravanan, M., Rajeev Sukumaran, M. R. Christhuraj, and T. T. Manikandan. "Stochastic Network Calculus Model for Delay Distribution of Time Division Multiple Access and Carrier Sense Multiple Access in Underwater Acoustic Wireless Communication." Revista Gestão Inovação e Tecnologias 11, no. 4 (July 22, 2021): 2885–901. http://dx.doi.org/10.47059/revistageintec.v11i4.2325.
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Underwater Acoustic wireless communication becomes a popular research area for transmitting and receiving data between the communicators in the ocean environment. High accuracy in data communication can be succeeded by proficient modeling of carrier sense multiple access and time division access. For such innovations, the system has to proceed with an appropriate framework to make constant data traffic and limitations on start to finish data traffic delays. There are two major wireless communication multiple access methods that can be utilized in real-time underwater networks. One of the multiple access schemes is TDMA and another one is CSMA/CA. This paper concentrated on the modeling of TDMA and CSMA/CA also proposes the comparison of delay (end-end) of both multiple access protocols. The results using SNC to obtain delay bounds and are associated with simulation. The results show TDMA has a lesser efficiency than CSMA/CA in the acoustic environment.
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Nguyen, VanDung, Tran Anh Khoa, Thant Zin Oo, Nguyen H. Tran, Choong Seon Hong, and Eui-Nam Huh. "Time Slot Utilization for Efficient Multi-Channel MAC Protocol in VANETs." Sensors 18, no. 9 (September 10, 2018): 3028. http://dx.doi.org/10.3390/s18093028.
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In vehicular ad hoc networks (VANETs), many schemes for a multi-channel media access control (MAC) protocol have been proposed to adapt to dynamically changing vehicle traffic conditions and deliver both safety and non-safety packets. One such scheme is to employ both time-division multiple access (TDMA) and carrier-sense multiple access (CSMA) schemes (called a hybrid TDMA/CSMA scheme) in the control channel (CCH) interval. The scheme can adjust the length of the TDMA period depending on traffic conditions. In this paper, we propose a modified packet transmitted in the TDMA period to reduce transmission overhead under a hybrid TDMA/CSMA multi-channel MAC protocol. Simulation results show that a MAC protocol with a modified packet supports an efficient packet delivery ratio of control packets in the CCH. In addition, we analyze the hybrid TDMA/CSMA multi-channel MAC protocol with the modified packet under saturated throughput conditions on the service channels (SCHs). The analysis results show that the number of neighbors has little effect on the establishment of the number of time slots in TDMA periods and on SCHs under saturated throughput conditions.
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LIM, ALVIN, and KUI MOK. "PERFORMANCE EVALUATION OF ADAPTIVE MEDIA ACCESS CONTROL PROTOCOLS FOR PERVASIVE WIRELESS NETWORKS." Journal of Interconnection Networks 03, no. 03n04 (September 2002): 253–72. http://dx.doi.org/10.1142/s0219265902000665.
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As pervasive and high-density wireless networks become increasingly common, it is critical to address the problems of intermittent disconnection, high error rate and collision that cause degradation in the performance of wireless media access control protocols, such as slotted ALOHA Time Division Multiple Access (slotted ALOHA/TDMA) and Direct Sequence Code Division Multiple Access (DS/CDMA). We propose adaptive techniques for improving performance of media access protocols through awareness of the mobile communication environment. These techniques involve detection of intermittent disconnection, high error rates, and collisions. Upon detection and notification of these conditions by snooping devices, the media access control layer adapts its operation and synchronization accordingly to reduce delay and loss of bandwidth. Results from our simulation studies show that adaptive TDMA improves performance by as much as 12 times over basic TDMA and adaptive CDMA improves by as much as 4 times over basic CDMA in wireless network with high density cells. Overall, adaptive CDMA still performs better than adaptive TDMA by about 4 times.
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Mengesha, Befekadu, Pablo Torres-Ferrera, and Roberto Gaudino. "Analysis of 5G New Radio Uplink Signals on an Analogue-RoF System Based on DSP-Assisted Channel Aggregation." Applied Sciences 9, no. 1 (December 24, 2018): 47. http://dx.doi.org/10.3390/app9010047.
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The 3rd Generation Partnership Project (3GPP) is in the process of developing 5th generation (5G) radio access technology, the so-called new radio (NR). The aim is to achieve the performance requirements forIMT-2020 radio interface technology. In this paper, we focus on the analysis of the transmission of 5G NR uplink physical channels, such as physical uplink shared channel (PUSCH) and physical uplink control channel (PUCCH), dedicated for data and control channels, respectively, as specified in the 3GPP standard, using digital signal processing (DSP)-assisted frequency division multiple access (FDMA) and time division multiple access (TDMA) channel aggregation techniques on an analogue radio-over-fiber (A-RoF) architecture. We verified that there is ~34% spectral efficiency gain and lower error vector magnitude (EVM) achieved using the TDMA technique.
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RANALKAR, MR, MK GUPTA, RP MISHRA, ANJIT ANJAN, and S. KRISHNAIAH. "Network of Automatic weather stations : Time division multiple access type." MAUSAM 65, no. 3 (July 1, 2014): 393–406. http://dx.doi.org/10.54302/mausam.v65i3.1048.
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A network of 550 Automatic Weather Stations (AWS) has been established across India during April 2009 to February 2012 to bridge observational gaps in data sparse regions and augment manned surface observational network. All AWS are equipped with sensors for parameters air temperature, relative humidity, atmospheric pressure, rainfall, wind and global solar radiation. Additional sensors for soil temperature, soil moisture, leaf temperature and leaf wetness have been provided at 127 AWS. The data loggers are programmed for hourly measurement schedule. The satellite telemetry technique called Time Division Multiple Access (TDMA) has been employed for data transmission through Data Relay Transponder (DRT) aboard geo-stationary satellite INSAT – 3A located at 93.5º E to ensure effective channel utilization. The data are received and archived in the central data receiving Earth Station established at Pune. The mean sea level pressure, dew point temperature, pressure tendency, daily maximum and minimum temperature are derived at Earth Station. The data are made available in near real time to end users in WMO code form via WMO Information System (WIS) and at www.imdaws.com.This paper presents technical details of AWS, network plan, features of telemetry system, capabilities of data receiving Earth Station and preliminary results of the performance of network.
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Abbosh, A. M., and M. A. Shehathah. "Theoretical Investigation into Spectral Coexistence of CDMA and TDMA Systems." Journal of Engineering Research [TJER] 5, no. 1 (December 1, 2008): 1. http://dx.doi.org/10.24200/tjer.vol5iss1pp1-6.
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The scarcity of available radio spectrum presently limits the extension of modern multimedia systems. This paper presents a theoretical investigation into the possibility of using a frequency overlay of a narrowband Code Division Multiple Access (CDMA) System and a Time Division Multiple Access (TDMA) System to provide a greater spectral efficiency. This paper shows that under certain conditions the two systems can operate in the same frequency band and in the same area with a considerable improvement in the overall capacity of the whole system.
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CHATTERJEE, MAINAK, and SAJAL K. DAS. "PERFORMANCE EVALUATION OF A REQUEST-TDMA/CDMA PROTOCOL FOR WIRELESS NETWORKS." Journal of Interconnection Networks 02, no. 01 (March 2001): 49–67. http://dx.doi.org/10.1142/s0219265901000257.
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This paper proposes a new medium access control (MAC) protocol, called Request-TDMA/CDMA, for supporting multimedia traffic in wireless networks. In this hybrid protocol, CDMA (code division multiple access) is laid over TDMA (time division multiple access), where a time frame has two kinds of slots, namely data slots and control slots. The data slots are used to the user to transmit their data while the control slot holds the information for the next frame's slot allocation. Each data slot in a frame can be simultaneously used by multiple users with the help of uniquely assigned codes. Whenever a user needs to transmit a message, he first sends a request message to the central controller and enters the contention process. The controller takes into consideration the time of generation of a call, the bit rate requirement and the message length while reserving slots for the entire length of the message generated. The user then goes into the transmission phase if he is successful in the contention process, and continues to transmit his data till the entire message is sent. Three scheduling algorithms for the allocation of data slots are proposed and their performance are studied for four classes of traffic. We also analyze our protocol using a two-dimensional Markov chain model, and compute the state transition probabilities and derive the average waiting time for a given system load. By simulation experiments we show that our request-TDMA/CDMA protocol is able to effectively combine the orthogonality of both time and code division multiplexing. Further enhancements are also proposed to decrease the waiting time and increase the average channel utilization.
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Jia, Gu, Yu Wen Wang, Fan Ji Meng, Guo Hua Ye, and Guo Lin Wang. "An Adaptive TDMA Slot Assignment Algorithm for Scalable Wireless Mesh Networks." Applied Mechanics and Materials 392 (September 2013): 872–75. http://dx.doi.org/10.4028/www.scientific.net/amm.392.872.
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The media access control (MAC) protocol based on fixed slot allocation has low throughput and high delay in high load wireless mesh network. In order to improve the performance of wireless mesh network, we propose a scalable adaptive time division multiple access (TDMA) slot allocation algorithm based on the existing fixed TDMA. The algorithm uses the network structure of clustering and builds a more optimized frame structure, cluster head dynamically allocates time slot according to the packet number of the cluster member sent and the priority level, at the same time taking into account the situation of nodes joining and leaving to improve the scalability of the network The simulation results on OPNET network simulation platform show that the algorithm is superior to fixed TDMA algorithm in both throughput and delay.
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Chen, Xiang, Yuheng Chen, Shuai Cao, Lei Zhang, Xu Zhang, and Xun Chen. "Acoustic Indoor Localization System Integrating TDMA+FDMA Transmission Scheme and Positioning Correction Technique." Sensors 19, no. 10 (May 22, 2019): 2353. http://dx.doi.org/10.3390/s19102353.
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This paper presents a novel audio indoor localization system. In the proposed system, four speakers placed at known positions transmit chirp signals according to the time-division multiple access (TDMA) plus frequency-division multiple access (FDMA) transmission scheme. A smartphone receives the signal via a built-in microphone and calculates the time differences of arrival (TDOAs). Using TDOA measurements, the position is estimated by the shrinking-circle method. In particular, to reduce the positioning error in moving conditions, a TDOA correction method based on Doppler shifts is proposed. The performance of the proposed system was evaluated in real-world experiments using a 10.971 m × 5.684 m positioning area. The results of the static-target positioning experiment showed that the TDMA+FDMA transmission scheme has more advantages in improving the update rate of the positioning system than the TDMA-only transmission scheme. The results of the moving-target positioning experiment under three different speeds demonstrated that the positioning errors were reduced by about 10 cm when the Doppler-shift-based TDOA correction method was adopted. This research provides a possible framework for the realization of a TDOA-chirp-based acoustic indoor positioning system with high positioning accuracy and update rate.
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Yang, Xin, Ling Wang, Jian Xie, and Zhaolin Zhang. "Energy Efficiency TDMA/CSMA Hybrid Protocol with Power Control for WSN." Wireless Communications and Mobile Computing 2018 (2018): 1–7. http://dx.doi.org/10.1155/2018/4168354.
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Wireless sensors network (WSN) is widely used in the Internet of Things at present. However, limited energy source is a critical problem in the improvement and practical applications of WSN, so it is necessary to improve the energy efficiency. As another important evaluation criterion of transmission performance, throughput should be improved too. To mitigate both of the problems at the same time, by taking the advantages of Time Division Multiple Access (TDMA) and Carrier Sense Multiple Access (CSMA) at the medium access control (MAC) layer of WSN, we propose a hybrid TDMA/CSMA MAC layer protocol. Meanwhile, we design a novel power control scheme to further reduce the energy consumption and optimize the transmission slots. The simulation results demonstrate that the proposed protocol significantly improves the throughput and energy efficiency.
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Vakulya, Gergely, Zsolt Tuza, and Gyula Simon. "Optimal Multi-TDMA Scheduling in Ring Topology Networks." Mathematical Problems in Engineering 2015 (2015): 1–14. http://dx.doi.org/10.1155/2015/837074.
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A scheduling algorithm will be proposed for wireless ring topology networks, utilizing time division multiple access (TDMA) with possible simultaneous operation of nodes. The proposed algorithm finds the optimal schedule to minimize the turnaround time for messages in the network. The properties of the algorithm are mathematically analyzed and proven, and practical test results are also provided.
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BORST, S. C., E. G. COFFMAN, E. N. GILBERT, P. A. WHITING, and P. M. WINKLER. "OPTIMAL CARRIER SHARING IN WIRELESS TDMA." Journal of Interconnection Networks 02, no. 02 (June 2001): 189–211. http://dx.doi.org/10.1142/s0219265901000324.
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To improve efficiency, we allow a carrier in a TDMA (Time Division Multiple Access) network to be shared by adjacent cells. This sharing of time slots is seriously hampered by the lack of synchronization in distinct cells. We study packing algorithms that overcome this obstacle by clustering calls. The results suggest that even simple greedy algorithms are nearly optimal, and that little extra performance can be gained either by allowing the rejection of calls or by repacking.
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Dobslaw, Felix, Tingting Zhang, and Mikael Gidlund. "Latency Improvement Strategies for Reliability-Aware Scheduling in Industrial Wireless Sensor Networks." International Journal of Distributed Sensor Networks 2015 (2015): 1–10. http://dx.doi.org/10.1155/2015/178368.
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We propose novel strategies for end-to-end reliability-aware scheduling in Industrial Wireless Sensor Networks (IWSNs). Because of stringent reliability requirements in industrial applications where missed packets may have disastrous or lethal consequences, all IWSN communication standards are based on Time Division Multiple Access (TDMA), allowing for deterministic channel access on the MAC layer. We therefore extend an existing generic and scalable reliability-aware scheduling approach by the name of SchedEx. SchedEx has proven to quickly produce TDMA schedules that guarantee a user-defined end-to-end reliability levelρ_for all multihop communication in a WSN. Moreover, SchedEx executes orders of magnitude faster than recent algorithms in the literature while producing schedules with competitive latencies. We generalize the original problem formulation from single-channel to multichannel scheduling and propose a scalable integration into the existing SchedEx approach. We further introduce a novel optimal bound that produces TDMA schedules with latencies around 20% shorter than the original SchedEx algorithm. Combining the novel strategies with multiple sinks, multiple channels, and the introduced optimal bound, we could through simulations verify latency improvements by almost an order of magnitude, reducing the TDMA superframe execution times from tens of seconds to seconds only, which allows for a utilization of SchedEx for many time-critical control applications.
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Ilcev, Stojce Dimov. "Analyses of Time Division Multiple Access (TDMA) Schemes for Global Mobile Satellite Communications (GMSC)." TransNav, the International Journal on Marine Navigation and Safety of Sea Transportation 14, no. 4 (2020): 831–37. http://dx.doi.org/10.12716/1001.14.04.06.
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Harkins, Judy. "Practical Information for Audiologists on Access to Wireless Telephones." Journal of the American Academy of Audiology 12, no. 06 (June 2001): 290–95. http://dx.doi.org/10.1055/s-0042-1745610.
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AbstractAnalog cellular telephone service is being phased out in favor of digital wireless services, which are less accessible to people with hearing loss. As a result, audiologists can expect to receive an increasing number of inquiries from clients about using wireless telephones with hearing aids and other assistive technologies. In this article, the underlying transmission technology, telephone handset, roaming, and current solutions to accessibility problems are described. Public policy affecting the accessibility of wireless telephones to people with hearing loss is explained. Alternatives to wireless voice services are explored, and resources for information in a quickly changing industry are provided. Abbreviations: CDMA = code division multiple access, FCC = Federal Communications Commission, GSM = Global System Mobile Communications, HAC = hearing aid compatible, TDMA = time division multiple access, TTY = text telephone
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Zhang, Pengju, Wenping Ge, Yongxing Zhang, Mengyao Gao, and Gecheng Zhang. "Energy Efficiency and User Capacity Optimization of Cognitive MIMO Systems Via the SCMA-Based Nonorthogonal Time Slot Allocation." Symmetry 12, no. 7 (July 7, 2020): 1136. http://dx.doi.org/10.3390/sym12071136.
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This paper investigates the energy-efficient communications and user capacity in the cognitive multiple input multiple output (MIMO) symmetric system of underlay mode. The advantage of the improved energy efficiency provided by the orthogonal slot allocation for time division multiple access (TDMA) has a side effect of restricting the number of users accessing the system. To tackle the above problem, this paper proposes a nonorthogonal time resource allocation method with sparse code multiple access (SCMA), which allows one to convert the orthogonal slot units of TDMA into non-orthogonal shared slot units for multiple secondary users (SUs). The method of adding virtual users is adopted, wherein each SU is treated as multiple SUs who occupy a shared unit, to facilitate the packet access. Finally, the greedy algorithm is applied to optimize the time slot allocation of unoccupied shared slot units. The simulation results show that SCMA-based nonorthogonal slot allocation can reduce not only the energy consumption by nearly 40%, but also the average power interference from SUs to primary users by nearly 2 dB if their number is relatively high. Moreover, in the case of satisfying the rate requirement of the users, the system user capacity increased by more than 50%.
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HE, ZHENYA, KE LI, LUXI YANG, and YUHUI SHI. "TDMA SECURE COMMUNICATION SCHEME BASED ON SYNCHRONIZATION OF CHUA'S CIRCUITS." Journal of Circuits, Systems and Computers 10, no. 03n04 (June 2000): 147–58. http://dx.doi.org/10.1142/s0218126600000111.
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A novel Time Division Multiple Access (TDMA) secure communication scheme is proposed based on sporadic coupling chaos synchronization. Compared with conventional chaos masking method, it has higher noise-resistibility, better security and frequency efficiency, etc. Simulation results illustrate the effectiveness and efficiency of this method. Finally, we analyze factors which affect system ability and give some conclusions.
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Aslam, Aqsa, Pedro M. Santos, Frederico Santos, and Luís Almeida. "Empirical Performance Models of MAC Protocols for Cooperative Platooning Applications." Electronics 8, no. 11 (November 12, 2019): 1334. http://dx.doi.org/10.3390/electronics8111334.
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Vehicular ad-hoc networks (VANET) enable vehicles to exchange information on traffic conditions, dynamic status and localization, to enhance road safety and transportation efficiency. A typical VANET application is platooning, which can take advantage of exchanging information on speed, heading and position to allow shorter inter-vehicle distances without compromising safety. However, the platooning performance depends drastically on the quality of the communication channel, which in turn is highly influenced by the medium access control protocol (MAC). Currently, VANETs use the IEEE 802.11p MAC, which follows a carrier sense multiple access with collision avoidance (CSMA/CA) policy that is prone to collisions and degrades significantly with network load. This has led to recent proposals for a time-division multiple access (TDMA)-based MAC that synchronize vehicles’ beacons to prevent or reduce collisions. In this paper, we take CSMA/CA and two TDMA-based overlay protocols, i.e., deployed over CSMA/CA, namely PLEXE-slotted and RA-TDMAp, and carry out extensive simulations with varying platoon sizes, number of occupied lanes and transmit power to deduce empirical models that provide estimates of average number of collisions per second and average busy time ratio. In particular, we show that these estimates can be obtained from observing the number of radio-frequency (RF) neighbours, i.e., number of distinct sources of the packets received by each vehicle per time unit. These estimates can enhance the online adaptation of distributed applications, particularly platooning control, to varying conditions of the communication channel.
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Manzano, Mario, Felipe Espinosa, Ángel M. Bravo-Santos, and Alfredo Gardel-Vicente. "Cognitive Self-Scheduled Mechanism for Access Control in Noisy Vehicular Ad Hoc Networks." Mathematical Problems in Engineering 2015 (2015): 1–12. http://dx.doi.org/10.1155/2015/354292.
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Within the challenging environment of intelligent transportation systems (ITS), networked control systems such as platooning guidance of autonomous vehicles require innovative mechanisms to provide real-time communications. Although several proposals are currently under discussion, the design of a rapid, efficient, flexible, and reliable medium access control mechanism which meets the specific constraints of such real-time communications applications remains unsolved in this highly dynamic environment. However, cognitive radio (CR) combines the capacity to sense the radio spectrum with the flexibility to adapt to transmission parameters in order to maximize system performance and has thus become an effective approach for the design of dynamic spectrum access (DSA) mechanisms. This paper presents the enhanced noncooperative cognitive division multiple access (ENCCMA) proposal combining time division multiple access (TDMA) and frequency division multiple access (FDMA) schemes with CR techniques to obtain a mechanism fulfilling the requirements of real-time communications. The analysis presented here considers the IEEE WAVE and 802.11p as reference standards; however, the proposed medium access control (MAC) mechanism can be adapted to operate on the physical layer of different standards. The mechanism also offers the advantage of avoiding signaling, thus enhancing system autonomy as well as behavior in adverse scenarios.
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Sivakumar, V., and D. Rekha. "Underwater Acoustic Sensor Node Scheduling using an Evolutionary Memetic Algorithm." Journal of Telecommunications and Information Technology 1 (March 28, 2018): 88–94. http://dx.doi.org/10.26636/jtit.2018.116217.
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Underwater Acoustic Sensor Networks (UWASNs) play an important role in monitoring the aqueous environment which has created a lot of interest for researchers and scientists. Utilization of underwater acoustic sensor node (UASN) scheduling for transmission remains, due to the limited acoustic bandwidth available, a challenge in such an environment. One of the methods to overcome this problem is to efficiently schedule UASN data using time division multiple access (TDMA) protocols the parallel transmissions, simultaneously avoiding interference. The paper shows how to optimize the utilization of acoustic sensor node bandwidth by maximizing the possible node transmissions in the TDMA frame and also by minimizing the node's turnaround wait time for its subsequent transmissions by using an evolutionary memetic algorithm (MA). The simulation of MA-TDMA proves that as the size of the network increases, every node in UWASN transmits with an average minimal turnaround transmission time. It also proves that as the TDMA cycle repeats, the overall network throughput gets maximized by increasing the possible node transmissions in the MA-TDMA frame.
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Tientadakul, Romprakhun, Hiroaki Nakanishi, Tomoo Shiigi, Zichen Huang, Lok Wai Jacky Tsay, and Naoshi Kondo. "Spread Spectrum Sound with TDMA and INS Hybrid Navigation System for Indoor Environment." Journal of Robotics and Mechatronics 33, no. 6 (December 20, 2021): 1315–25. http://dx.doi.org/10.20965/jrm.2021.p1315.
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Indoor navigation plays an essential role in agricultural robots that operate in greenhouses. One of the most effective methods for indoor navigation is the spread spectrum sound (SS-sound) system. In this system, the time of arrival (ToA) of the spread spectrum modulated sound is used for localization. However, there is a near-far problem. Transmitting the SS-sound from multiple anchors using time division multiple access (TDMA) is adequate to solve the near-far problem. However, localization is impossible because the ToA from multiple anchors cannot be simultaneously acquired. To solve this problem, a method for combining the SS-sound system with TDMA and an inertial navigation system is proposed in this study. The effectiveness of the proposed method was demonstrated through numerical simulations of a ground robot and experimentally using a crawler robot.
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Nosheen, Irum, Shoab A. Khan, and Umar Ali. "A Cross-Layer Design for a Multihop, Self-Healing, and Self-Forming Tactical Network." Wireless Communications and Mobile Computing 2019 (April 9, 2019): 1–16. http://dx.doi.org/10.1155/2019/1523906.
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In mission and time critical applications, bandwidth and delay optimizations are the key goals of communication systems. This paper presents a cross-layer framework design that reduces the call setup time, provides collision-free communication, and reuses the empty slots of Time Division Multiple Access (TDMA) protocol which otherwise causes low throughput and large delay. As number of communicating nodes in tactical networks is small as compared to commercial mobile ad hoc networks (MANETs), classical TDMA will yield huge number of empty slots and any Carrier Sense Multiple Access/Collision Detection (CSMA/CD) technique may cause more delay in some critical scenarios. Proposed methodology gives a Cross-Layer Architecture for Network (NET) Layer and Medium Access Control (MAC) Layer. Our design provides bandwidth efficient, collision-free communication to Software-Defined Radios (SDRs) in self-forming and self-healing tactical networks with low call setup time and multihop routing. For this purpose TDMA as MAC layer protocol and Ad Hoc On Demand Distance Vector (AODV) as Network Layer Routing Protocol are used. Our slot allocation (SA) algorithm, Cross-Layer TDMA (CL-TDMA), consists of control phase where AODV control packets are exchanged and data transfer phase where transmission of data and voice occurs. All active radios in vicinity gather information about communicating nodes based on the exchange of control packets by SDRs. Our algorithm then uses this information to help all active SDRs find slot(s) that will be used for collision-free transmission. A number of experiments are performed to establish improved performance of the proposed technique compared to other established techniques and protocols.
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Giustiniano, Domenico, Eduard Goma, Alberto Lopez Toledo, and George Athanasiou. "Optimizing TCP Performance in Multi-AP Residential Broadband Connections via Minislot Access." Journal of Computer Networks and Communications 2013 (2013): 1–12. http://dx.doi.org/10.1155/2013/752363.
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The high bandwidth demand of Internet applications has recently driven the need of increasing the residential download speed. A practical solution to the problem is to aggregate the bandwidth of 802.11 access points (APs) backhauls in range. Since 802.11 devices are usually single radio, the communication to APs on different radio channels requires a time-division multiple access (TDMA) policy at the client station. With an in-depth experimental analysis and a customized 802.11 driver, in this paper, we show that the usage of multi-AP TDMA policy may cause degradation of the TCP throughput and an underutilization of the AP backhauls. We then introduce a simple analytical model that accurately predicts the TCP round-trip time (RTT) with a multi-AP TDMA policy and propose a resource allocation algorithm to reduce the observed TCP RTT with a very low computational cost. Our proposed scheme runs locally at the client station and improves the aggregate throughput up to 1.5 times compared to state-of-the-art allocations. We finally show that the throughput achieved by our algorithm is very close to the theoretical upper bound in key simulation scenarios.
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Ross, Mark. "Wireless Telephones and Hearing Aids: An Overview." Journal of the American Academy of Audiology 12, no. 06 (June 2001): 286–89. http://dx.doi.org/10.1055/s-0042-1745609.
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AbstractWireless telephones are becoming increasingly common and will be more so in the future. Unfortunately, many are unusable with hearing aids and may actively interfere with the normal use of hearing aids because of the electromagnetic interference (EMI) generated by wireless telephones. The EMI generated by digital wireless telephones is much greater than that of analog wireless telephones. More research and design work needs to be done before wireless telephones can be considered accessible to people who use hearing aids. Abbreviations: CDMA = code division multiple access, EMI = electromagnetic interference, FCC = Federal Communications Commission, GSM = Global System for Mobile Communications, PCS = personal communication service, SHHH = Self Help for Hard of Hearing People, TDMA = time division multiple access
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Xu, Juan, Jiali Kan, and Yan Zhang. "Centralized Energy Harvesting-Based TDMA Protocol for Terahertz NanoSensor Networks." Sensors 19, no. 20 (October 17, 2019): 4508. http://dx.doi.org/10.3390/s19204508.
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Terahertz wireless nano-sensor networks (WNSNs) are novel networks interconnecting multiple nano-devices by means of wireless communication. In this paper, a centralized energy harvesting-based time division multiple access (TDMA) protocol, called CEH-TDMA is proposed. This protocol examines the data transmission process from a global perspective, where the nano-controller regulates the channel access and allocates time slots for all nano-nodes. First, each nano-node sends the remaining energy and the number of packets in its data buffer to the nano-controller, and then, the nano-controller constructs a Markov decision process (MDP) model according to the state information of all nano-nodes, where the energy consumption and the number of transmitted packets in the entire network are considered as impact factors in designing the award function in the MDP model. Finally, a globally optimal slot allocation strategy is obtained, which maximizes the amount of packet transmission in the perpetual WNSNs.
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Liu, Yao, Hongjing Zhou, and Jiawei Huang. "OCA-MAC: A Cooperative TDMA-Based MAC Protocol for Vehicular Ad Hoc Networks." Sensors 19, no. 12 (June 14, 2019): 2691. http://dx.doi.org/10.3390/s19122691.
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Cooperative communication is an effective method of improving the transmission performance for vehicular ad hoc networks. However, the rapid movement of vehicles leads to frequent changes in network topology and reduces the probability of successful data transmission on the medium access control (MAC) layer. In this paper, we propose an Optimal Cooperative Ad hoc MAC protocol (OCA-MAC) based on time division multiple access (TDMA). OCA-MAC utilizes multiple cooperative nodes to forward data, so as to improve the probability of successful data transmission. It chooses cooperative nodes according to direct successful transmission probability, communication range between potential helper node and destination node, and available time slot. Meanwhile, in order to avoid excessive transmission redundancy caused by multiple cooperative forwarding, the optimal number of cooperative forwarding nodes is obtained through analysis of a probabilistic model. Simulation results show that OCA-MAC improves the successful data transmission rate and reduces the number of transmission times and transmission delay compared to the multichannel TDMA MAC protocol (VeMAC) and the cooperative ad hoc MAC protocol (CAH-MAC).
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Gong, Shuping, and Husheng Li. "Wireless Multiple Access and Analog Oscillation Analysis in Microgrids: A Prony Approach." International Journal of Distributed Sensor Networks 8, no. 10 (October 1, 2012): 932683. http://dx.doi.org/10.1155/2012/932683.
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A key challenge in smart grid is to monitor the system modal characteristics of disturbance over a microgrid for system stability and diagnosis. The measurements at different phasor measurement units (PMUs) need to be reported to a processing center. Therefore, a multiple access scheme for wireless transmission is necessary to collect the measurements from PMUs. An analog oscillation analysis is carried out without demodulating the received signal. Both schemes of time-division multiple access (TDMA) and code-division multiple access (CDMA) are discussed. In both schemes, the Prony-based algorithms using the received signal to estimate the system modal characteristics, including the eigenvalues of the linear system and the amplitudes of different response modes, are proposed and analyzed. Two countermeasures, max-min ratio measure (MMRM) and variance measure (VM), are also proposed to prevent possible attacks of false reports. Numerical simulation results demonstrate the effectiveness of Prony-based algorithms and the two countermeasures.
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Ullah, Sana, Riazul Islam, Ahasanun Nessa, Yingji Zhong, and Kyung Sup Kwak. "Performance Analysis of Preamble-Based TDMA Protocol for Wireless Body Area Network." Journal of Communications Software and Systems 4, no. 3 (September 22, 2008): 222. http://dx.doi.org/10.24138/jcomss.v4i3.221.
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A wireless body area network (WBAN) allows the integration of low power, invasive or non-invasive miniaturized sensors around a human body. Each intelligent sensor has enough capability to analyze and process the physiological parameters and to forward all the information to a central intelligent node for disease management, diagnosis and prescription. The data transmission rate of various biosensors is heterogeneous. Furthermore, the limited energy resources and computational power of these sensors have urged the development of low power energy efficient medium access control (MAC) protocol. This paper studies the performance of Preamble-Based time division multiple access (PB-TDMA) protocol for a heterogeneous non-invasive WBAN. Simulation results show that the performance of PB-TDMA protocol outperforms S-MAC and IEEE 802.11 DCF in terms of throughput and power consumption.
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Shenoy, Meetha V., and K. R. Anupama. "DTTA - Distributed, Time-division Multiple Access based Task Allocation Framework for Swarm Robots." Defence Science Journal 67, no. 3 (April 25, 2017): 316. http://dx.doi.org/10.14429/dsj.67.10955.
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Swarm robotic systems, unlike traditional multi-robotic systems, deploy number of cost effective robots which can co-operate, aggregate to form patterns/formations and accomplish missions beyond the capabilities of individual robot. In the event of fire, mine collapse or disasters like earthquake, swarm of robots can enter the area, conduct rescue operations, collect images and convey locations of interest to the rescue team and enable them to plan their approach in advance. Task allocation among members of the swarm is a critical and challenging problem to be addressed. DTTA- a distributed, Time-division multiple access (TDMA) based task allocation framework is proposed for swarm of robots which can be utilised to solve any of the 8 different types of task allocation problem identified by Gerkey and Mataric´. DTTA is reactive and supports task migration via extended task assignments to complete the mission in case of failure of the assigned robot to complete the task. DTTA can be utilised for any kind of robot in land or for co-operative systems comprising of land robots and air-borne drones. Dependencies with other layers of the protocol stack were identified and a quantitative analysis of communication and computational complexity is provided. To our knowledge this is the first work to be reported on task allocation for clustered scalable networks suitable for handling all 8 types of multi-robot task allocation problem. Effectiveness and feasibility of deploying DTTA in real world scenarios is demonstrated by testing the framework for two diverse application scenarios.
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Wang, Zhen-Yu, Hong-Yi Yu, and Da-Ming Wang. "Energy Efficient Transceiver Design for NOMA VLC Downlinks with Finite-Alphabet Inputs." Applied Sciences 8, no. 10 (October 4, 2018): 1823. http://dx.doi.org/10.3390/app8101823.
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Non-orthogonal multiple access (NOMA) is considered as a promising technique in visible light communication (VLC) systems for performance enhancement. In order to improve the system’s energy efficiency, we carry out transceiver design for an NOMA VLC system. We develop an optimal power allocation scheme for the system based on finite-alphabet inputs, and we propose a joint detection and decoding (JDD) algorithm for signal detection. Comprehensive simulation results demonstrate that our proposed NOMA strategy can achieve significant performance gains over the time division multiple access (TDMA) scheme, and our designed JDD algorithm outperforms the conventional successive interference cancellation (SIC) algorithm for NOMA.
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Manzano, Mario, Felipe Espinosa, Ángel M. Bravo-Santos, Enrique Santiso, Ignacio Bravo, and David Garcia. "Dynamic Cognitive Self-Organized TDMA for Medium Access Control in Real-Time Vehicle to Vehicle Communications." Mathematical Problems in Engineering 2013 (2013): 1–13. http://dx.doi.org/10.1155/2013/574528.
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The emergence of intelligent transport systems has brought out a new set of requirements on wireless communication. To cope with these requirements, several proposals are currently under discussion. In this highly mobile environment, the design of a prompt, efficient, flexible, and reliable medium access control, able to cover the specific constraints of the named real-time communications applications, is still unsolved. This paper presents the original proposal integrating Non-Cooperative Cognitive Time Division Multiple Access (NCC-TDMA) based on Cognitive Radio (CR) techniques to obtain a mechanism which complies with the requirements of real-time communications. Though the proposed MAC uses a slotted channel, it can be adapted to operate on the physical layer of different standards. The authors’ analysis considers the IEEE WAVE and 802.11p as the standards of reference. The mechanism also offers other advantages, such as avoiding signalling and the adaptation capacity to channel conditions and interferences. The solution is applied to the problem of units merging a convoy. Comparison results between NCC-TDMA and Slotted-Aloha are included.
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Latif, Muhammad Bilal, Feng Liu, and Kai Liu. "A TDMA-Based MAC Protocol for Mitigating Mobility-Caused Packet Collisions in Vehicular Ad Hoc Networks." Sensors 22, no. 2 (January 14, 2022): 643. http://dx.doi.org/10.3390/s22020643.
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An autonomous driving environment poses a very stringent requirement for the timely delivery of safety messages in vehicular ad hoc networks (VANETs). Time division multiple access (TDMA)-based medium access control (MAC) protocols are considered a promising solution because of their time-bound message delivery. However, in the event of mobility-caused packet collisions, they may experience an unpredicted and extended delay in delivering messages, which can cause catastrophic accidents. To solve this problem, a distributed TDMA-based MAC protocol with mobility-caused collision mitigation (MCCM-MAC) is presented in this paper. The protocol uses a novel mechanism to detect merging collisions and mitigates them by avoiding subsequent access collisions. One vehicle in the merging collisions retains the time slot, and the others release the slot. The common neighboring vehicles can timely suggest a suitable new time slot for the vacating vehicles, which can avoid access collisions between their packet transmissions. A tie-breakup mechanism is employed to avoid further access collisions. Simulation results show that the proposed protocol reduces packet loss more than the existing methods. Consequently, the average delay between the successfully delivered periodic messages is also reduced.
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Arokiaraj Jovith, A., S. V. Kasmir Raja, and A. Razia Sulthana. "Interference mitigation in point to point wireless sensor networks using LSP protocol and time division multiplexing approach." Journal of Intelligent & Fuzzy Systems 39, no. 4 (October 21, 2020): 5449–58. http://dx.doi.org/10.3233/jifs-189028.
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Interference in Wireless Sensor Network (WSN) predominantly affects the performance of the WSN. Energy consumption in WSN is one of the greatest concerns in the current generation. This work presents an approach for interference measurement and interference mitigation in point to point network. The nodes are distributed in the network and interference is measured by grouping the nodes in the region of a specific diameter. Hence this approach is scalable and isextended to large scale WSN. Interference is measured in two stages. In the first stage, interference is overcome by allocating time slots to the node stations in Time Division Multiple Access (TDMA) fashion. The node area is split into larger regions and smaller regions. The time slots are allocated to smaller regions in TDMA fashion. A TDMA based time slot allocation algorithm is proposed in this paper to enable reuse of timeslots with minimal interference between smaller regions. In the second stage, the network density and control parameter is introduced to reduce interference in a minor level within smaller node regions. The algorithm issimulated and the system is tested with varying control parameter. The node-level interference and the energy dissipation at nodes are captured by varying the node density of the network. The results indicate that the proposed approach measures the interference and mitigates with minimal energy consumption at nodes and with less overhead transmission.
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Xu, Shi Jun, Yong Hong Hu, and Wei Wan. "The Design and Application of UAV’s Digital Steering Gear." Advanced Materials Research 181-182 (January 2011): 998–1005. http://dx.doi.org/10.4028/www.scientific.net/amr.181-182.998.
Full textAbstract:
For a special electromagnetic environment and the installation of environmental requirements of UAV (unmanned aerial vehicle) airborne, a design of digital anti-jamming steering gear is given. The composition, functions and working principle of the steering gear are described in details. The key circuits of functional modules are given, introduce a CDMA (code division multiple access) communication protocol of Digital Servo instruction and TDMA (time division multiple access) state data frame format. Take a UAV as an example, discusses the multi-steering application in airborne systems workflow. The application results showed that: this design not only improves the steering anti-jamming capability, ensures that the steering gear in the normal operation of complex electromagnetic environment, but also greatly reduces the UAV onboard computer control interfaces, improves flexibility and reliability.
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Levitt, Harry, Judy Harkins, Beth Singer, and Eddy Yeung. "Field Measurements of Electromagnetic Interference in Hearing Aids." Journal of the American Academy of Audiology 12, no. 06 (June 2001): 275–80. http://dx.doi.org/10.1055/s-0042-1745607.
Full textAbstract:
AbstractThis investigation was a preliminary field study to determine the acoustic and perceptual characteristics of hearing aid distortion generated by digital wireless telephones, the usability of the telephones under field conditions, and the extent of bystander interference under field conditions. A two-channel analog-to-digital converter was used to monitor voltages generated by an acoustic (real-ear) and electromagnetic probe. Digital recordings of interference and speech plus interference were made on a laptop computer. Fifty-three hearing aid wearers listened to interference and speech plus interference through personal communication service 1900 and time division multiple access digital wireless telephones and rated them in terms of annoyance experienced and usability of the wireless telephone. Ratings of annoyance were also done for the bystander condition. Approximately 80 percent of the sample rated the telephones as unusable; on the other hand, 70 to 90 percent experienced no annoying interference from telephones being used by another person seated nearby (bystander condition). Abbreviations: BTE = behind the ear, CDMA = code division multiple access, EM = electromagnetic, PBX = private branch exchange, PCS = personal communication service, RF = radio frequency, TDMA = time division multiple access
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HOSSAIN, EKRAM, and VIJAY K. BHARGAVA. "LINK-STATE AWARE DYNAMIC TRAFFIC SCHEDULING FOR PROVIDING PREDICTIVE QoS IN WIRELESS MOBILE MULTIMEDIA NETWORKS." Journal of Interconnection Networks 01, no. 03 (September 2000): 221–45. http://dx.doi.org/10.1142/s0219265900000147.
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The performance of a centralized traffic priority based dynamic burst-level cell scheduling scheme is investigated in a correlated fading channel. The scheduling scheme is designed for the transmission of multiservice traffic over TDMA (Time Division Multiple Access)/TDD (Time Division Duplex) channels in a WATM (Wireless ATM) network. In this scheme, the number of slots allocated to a VC (Virtual Circuit) during a frame-time is changed dynamically depending on the traffic type, system traffic load, TOE (Time of Expiry) value of the data burst and data burst length. While allocating bandwidth, the channel error status is also taken into consideration. SR-ARQ (Selective Repeat - Automatic Repeat Request)-based link-level error control is assumed for all the traffic types in a multiservice traffic environment. The performance of the proposed scheme under correlated Rayleigh fading is evaluated using computer simulation for realistic voice, video and data traffic models and the QoS (Quality of Service) requirements of different traffic classes in a wireless mobile network. Simulation results show that the proposed scheduling framework can provide reasonably high channel utilization with predictive QoS guarantee in a multiservice traffic environment. The channel utilization and the perceived QoS for different services is highly affected by the traffic burstiness of the corresponding traffic type. Such a scheme can result in an energy efficient TDMA/TDD medium access control protocol for broadband wireless access.
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Al-Absi, Ahmed Abdulhakim, Mohammed Abdulhakim Al-Absi, Mangal Sain, and Hoon Jae Lee. "Channel Allocation for Connected Vehicles in Internet of Things Services." Sensors 21, no. 11 (May 24, 2021): 3646. http://dx.doi.org/10.3390/s21113646.
Full textAbstract:
Based on the existing Internet of Vehicles communication protocol and multi-channel allocation strategy, this paper studies the key issues with vehicle communication. First, the traffic volume is relatively large which depends on the environment (city, highway, and rural). When many vehicles need to communicate, the communication is prone to collision. Secondly, because the traditional multi-channel allocation method divides the time into control time slots and transmission time slots when there are few vehicles, it will cause waste of channels, also when there are more vehicles, the channels will not be enough for more vehicles. However, to maximize the system throughput, the existing model Enhanced Non-Cooperative Cognitive division Multiple Access (ENCCMA) performs amazingly well by connected the Cognitive Radio with Frequency Division Multiple Access (FDMA) and Time Division Multiple Access (TDMA) for a multi-channel vehicular network.However, this model induces Medium Access Control (MAC) overhead and does not consider the performance evaluation in various environmental conditions.Therefore, this paper proposes a Distributed Medium Channel Allocation (DMCA) strategy, by dividing the control time slot into an appointmentand a safety period in the shared channel network. SIMITS simulator was used for experiment evaluation in terms of throughput, collision, and successful packet transmission. However, the outcome shows that our method significantly improved the channel utilizationand reduced the occurrence of communication overhead.
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Giriraja, C. V., V. Chirag, C. Sudheendra, Samarth S. Bellur, T. K. Ramesh, and K. N. Meera. "Priority Based Time-Division Multiple Access Algorithm for Medium Range Data Communication in Very High Frequency Radios." Journal of Computational and Theoretical Nanoscience 17, no. 1 (January 1, 2020): 290–96. http://dx.doi.org/10.1166/jctn.2020.8664.
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In this paper, A novel and efficient time division multiple access (TDMA) algorithm for military last-mile data communication is designed. A dynamic slot assignment method coupled with an out-of-band control mechanism is used for the proposed design. In out-of-band, there is a well-defined control segment along with the data segment. So, if a new node specifically a high priority node arrives at the network, it can signal its arrival by a response in the designated mini-slots and can also check the slot in the network, if no idle slots are available. Assigning priority to the nodes would also ensure the delivery of the important messages first. Query messages are broadcasted by the Central node in order to detect new nodes. This reduces nodes working time and also ensures that the nodes don’t interrupt any existing communication. Furthermore, we describe the feasibility and the reliability of this algorithm for military’s last-mile (end user) data communication.
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Zhang, Litianyi, Yifan Gu, Rui Wang, Kan Yu, Zhibo Pang, Yonghui Li, and Branka Vucetic. "Enabling Real-Time Quality-of-Service and Fine-Grained Aggregation for Wireless TSN." Sensors 22, no. 10 (May 20, 2022): 3901. http://dx.doi.org/10.3390/s22103901.
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Wireless Time-Sensitive Networking (WTSN) has emerged as a promising technology for Industrial Internet of Things (IIoT) applications. To meet the latency requirements of WTSN, wireless local area network (WLAN) such as IEEE 802.11 protocol with the time division multiple access (TDMA) mechanism is shown to be a practical solution. In this paper, we propose the RT-WiFiQA protocol with two novel schemes to improve the latency and reliability performance: real-time quality of service (RT-QoS) and fine-grained aggregation (FGA) for TDMA-based 802.11 systems. The RT-QoS is designed to guarantee the quality-of-service requirements of different traffic and to support the FGA mechanism. The FGA mechanism aggregates frames for different stations to reduce the physical layer transmission overhead. The trade-off between the reliability and FGA packet size is analyzed with numerical results. Specifically, we derive a critical threshold such that the FGA can achieve higher reliability when the aggregated packet size is smaller than the critical threshold. Otherwise, the non-aggregation scheme outperforms the FGA scheme. Extensive experiments are conducted on the commercial off-the-shelf 802.11 interface. The experiment results show that compared with the existing TDMA-based 802.11 system, the developed RT-WiFiQA protocol can achieve deterministic bounded real-time latency and greatly improves the reliability performance.
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Prapas, Antonios, Konstantinos F. Kantelis, Petros Nicopolitidis, and Georgios I. Papadimitriou. "An On-Demand TDMA Approach Optimized for Low-Latency IoT Applications." Sensors 22, no. 17 (August 27, 2022): 6461. http://dx.doi.org/10.3390/s22176461.
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The never-ending evolution of the Internet of Things ecosystem is reshaping the arena of wireless communications and competing against conventional networking solutions in fields such as battery life, device and deployment cost, coverage, and support for an immense number of devices. Inspired by this phenomenon, this paper presents a novel Medium Access Control protocol utilizing long-range technology, based on a Time Division Multiple Access communication protocol variant, adjusted to make better use of each device’s hardware. Focusing on Low Power Wide Area Network applications, this implementation improves data latency and offers amplified performance due to better network awareness and dynamic time slot rescheduling. Various simulation scenarios were contrived to evaluate the protocol’s performance. The results instate the proposed algorithm as a promising access scheme for the IoT field.
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Sugihara, Makoto. "Dynamic Slot Multiplexing Under Operating Modes for TDMA-Based Real-Time Networking Systems." Electronics 9, no. 2 (January 29, 2020): 224. http://dx.doi.org/10.3390/electronics9020224.
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The Time Division Multiple Access (TDMA) scheme has been proposed as the one which assures real-time messaging in a networking system. In the TDMA scheme, a networking system operates based on time slots which are defined as discrete time units. Some messages are periodically and exclusively assigned to their own time slots and are assured to be sent between network nodes by their own deadline. In this paper, we note that an operating situation of a system determines what functions of the system run. More concretely, an operating situation determines what data the system requires and how frequently it requires them. We propose to introduce operating modes, each of which reflects its own operating situation, to the TDMA scheme. An operating mode is specified by a set of communication signals which are active under the operating mode. We propose a dynamic slot multiplexing (DSM) technique which switches operating modes and assignments of communication signals to time slots adaptively with operating situations. System designers are to schedule all messages of communication signals for every operating mode so that the messages are sent by their own deadline. Compared with a single-mode TDMA system, in which a single message schedule is determined for all communication signals, our approach optimally determines a message schedule for each operating mode so that it can avoid wasting networking resources. Our experiment shows that DSM technique achieves about 21%-37% lower operating frequency than static slot multiplexing one.
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Son, Woong, Jungwook Choi, Soobum Park, Howon Lee, and Bang Chul Jung. "A Time Synchronization Protocol for Barrage Relay Networks." Sensors 23, no. 5 (February 22, 2023): 2447. http://dx.doi.org/10.3390/s23052447.
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Time-division multiple access (TDMA)-based medium access control (MAC) protocol has been widely used for avoiding access conflicts in wireless multi-hop ad hoc networks, where the time synchronization among wireless nodes is essential. In this paper, we propose a novel time synchronization protocol for TDMA-based cooperative multi-hop wireless ad hoc networks, which are also called barrage relay networks (BRNs). The proposed time synchronization protocol is based on cooperative relay transmissions to send time synchronization messages. We also propose a network time reference (NTR) selection technique for improving the convergence time and average time error. In the proposed NTR selection technique, each node overhears the user identifier (UID) of other nodes, hop count (HC) from them to itself, and network degree, which denotes the number of 1-hop neighbor nodes. Then, the node with the minimum HC from all other nodes is selected as the NTR node. If there are multiple nodes with the minimum HC, the node with the larger degree is selected as the NTR node. To the best of our knowledge, the proposed time synchronization protocol with the NTR selection is introduced for the first time for cooperative (barrage) relay networks in this paper. Through computer simulations, we validate the proposed time synchronization protocol in terms of the average time error under various practical network scenarios. Furthermore, we also compare the performance of the proposed protocol with the conventional time synchronization methods. It is shown that the proposed protocol significantly outperforms the conventional methods in terms of the average time error and convergence time. The proposed protocol is shown to be more robust against packet loss as well.