Статті в журналах: "Time Division Multiplexing Access"

1

Ansari, Muhammad Adil, Umair Saeed Solnagi, Jinuk Kim, Ahsin Murtaza Bughio, and Sungju Park. "Time Division Multiplexing based Test Access for Stacked ICs." JOURNAL OF SEMICONDUCTOR TECHNOLOGY AND SCIENCE 19, no. 1 (February 28, 2019): 87–96. http://dx.doi.org/10.5573/jsts.2019.19.1.087.

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Li, Jun, Miaowen Wen, Xueqin Jiang, and Wei Duan. "Space-Time Multiple-Mode Orthogonal Frequency Division Multiplexing With Index Modulation." IEEE Access 5 (2017): 23212–22. http://dx.doi.org/10.1109/access.2017.2761845.

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3

Liu, Bo, Lijia Zhang, Xiangjun Xin, and Lei Liu. "40 Gb/s dynamic wavelength-division-multiplexing/time-division-multiplexing hybrid access network with energy and data stream synchronized transmission." Optics Letters 38, no. 18 (September 4, 2013): 3503. http://dx.doi.org/10.1364/ol.38.003503.

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4

Siddiqi, Umair F., Sadiq M. Sait, and Murat Uysal. "Deep Q-Learning Based Optimization of VLC Systems With Dynamic Time-Division Multiplexing." IEEE Access 8 (2020): 120375–87. http://dx.doi.org/10.1109/access.2020.3005885.

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5

Wang, Hui Qi, and Wangyong Lv. "FrFT Angle Division Multiple Access with Optimal Time-Frequency-Angle Resource Distribution." Applied Mechanics and Materials 519-520 (February 2014): 1012–15. http://dx.doi.org/10.4028/www.scientific.net/amm.519-520.1012.

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In this paper, optimal time-frequency-angle (TFA) resource distribution is proposed. It is achieved by fractional Fourier transform (FrFT) angle division multiple access (ADMA), and multiple data streams can be transmitted in the same frequency and time slot. Comparing with conventional time-frequency (TF) resource based orthogonal frequency division multiplexing (OFDM) system, the exponential base at each sub-channel is replaced by a set of chirp bases, which keep mutually approximately orthogonal. Each base station (BS) can support more move stations (MSs) or cell throughput. Simulations show the essential advantages in TFA resource distribution and system spectrum efficiency.

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6

Yonis, Aws Zuheer, and Khalid Khalil Mohammed. "Investigation of pattern division multiple access technique in wireless communication networks." Indonesian Journal of Electrical Engineering and Computer Science 26, no. 1 (April 1, 2022): 296. http://dx.doi.org/10.11591/ijeecs.v26.i1.pp296-303.

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Recently, pattern division multiple access (PDMA) is a non-orthogonal multiple access system that is now being developed in next-generation telecoms to address the requirement for mass connectivity. The core premise of non-orthogonal multiple access is to simultaneously serve multiple users with varying power levels across the same spectrum resources such as time, frequency, code, as well as space with minimal inter-user interference. A simulation analysis of significant technology enhancements focusing on PDMA aims to describe the benefits of the two plans now being examined by the third-generation partnership project for 5G technologies, namely filtered orthogonal frequency division multiplexing (F-OFDM) and windowed orthogonal frequency division multiplexing (W-OFDM), and to compare them to alternative modulation processes such as 16, 32, and 128 modulations. The research results explained the PDMA is less bit error rate used in multiple access technologies compare with W-OFDM and F-OFDM.

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7

Saeed, Iftikhar Ahmed, Shi Qinglan, Minjuan Wang, Salman Latif Butt, Lihua Zheng, Vu Ngoc Tuan, and Gao Wanlin. "Development of a Low-Cost Multi-Depth Real-Time Soil Moisture Sensor Using Time Division Multiplexing Approach." IEEE Access 7 (2019): 19688–97. http://dx.doi.org/10.1109/access.2019.2893680.

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8

Richard, E. Alwin. "Performance Analysis of OFDMA vs. NOMA in Cognitive Radio Network." International Journal for Research in Applied Science and Engineering Technology 9, no. VI (June 14, 2021): 2483–88. http://dx.doi.org/10.22214/ijraset.2021.34751.

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Recent advancements in communication systems have resulted in a new class of multiple access schemes known as non-orthogonal multiple access (NOMA), the primary goal of which is to increase spectrum efficiency by overlapping data from different users in a single time-frequency resource used by the physical layer. NOMA receivers can resolve interference between data symbols from various users, hence increasing throughput. Initially, the combination of SCMA and orthogonal frequency division multiplexing (OFDM) is addressed, establishing a baseline for the overall SER performance of the multiple access strategy. Furthermore, this work suggests the merging of SCMA with generalised frequency division multiplexing (GFDM).GFDM is an intriguing possibility for future wireless communication systems since it is a very flexible non-orthogonal waveform that can imitate various different waveforms as corner cases. This research suggests two methods for integrating SCMA with GFDM.

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Wu, Bin, Hongxi Yin, Jie Qin, Chang Liu, Anliang Liu, Qi Shao, and Xiaoguang Xu. "Design and implementation of flexible TWDM-PON with PtP WDM overlay based on WSS for next-generation optical access networks." Modern Physics Letters B 30, no. 25 (September 20, 2016): 1650324. http://dx.doi.org/10.1142/s0217984916503243.

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Aiming at the increasing demand of the diversification services and flexible bandwidth allocation of the future access networks, a flexible passive optical network (PON) scheme combining time and wavelength division multiplexing (TWDM) with point-to-point wavelength division multiplexing (PtP WDM) overlay is proposed for the next-generation optical access networks in this paper. A novel software-defined optical distribution network (ODN) structure is designed based on wavelength selective switches (WSS), which can implement wavelength and bandwidth dynamical allocations and suits for the bursty traffic. The experimental results reveal that the TWDM-PON can provide 40 Gb/s downstream and 10 Gb/s upstream data transmission, while the PtP WDM-PON can support 10 GHz point-to-point dedicated bandwidth as the overlay complement system. The wavelengths of the TWDM-PON and PtP WDM-PON are allocated dynamically based on WSS, which verifies the feasibility of the proposed structure.

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10

Liang, Siyuan. "The demonstration of 10 Gbit/s time division multiplexing and 2.5 Gchip/s quasi-synchronous electrical code division multiplexing access passive optical network prototype system." Optical Engineering 51, no. 4 (April 20, 2012): 040507. http://dx.doi.org/10.1117/1.oe.51.4.040507.

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11

Cai, Chun, Yongmei Sun, Jianing Niu, Peng Zhang, Yongrui Zhang, and Yuefeng Ji. "Multicore-fiber-based quantum-classical access network architecture with quantum signal wavelength-time division multiplexing." Journal of the Optical Society of America B 37, no. 4 (March 12, 2020): 1047. http://dx.doi.org/10.1364/josab.384344.

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12

Soomro, Iftikhar A., Mohammad Samie, and Ian K. Jennions. "Reduced Pin-Count Test Strategy for 3D Stacked ICs Using Simultaneous Bi-Directional Signaling Based Time Division Multiplexing." IEEE Access 9 (2021): 75892–904. http://dx.doi.org/10.1109/access.2021.3081359.

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13

Li, Shuang Zhi, Zhe Zhang, Xiao Min Mu, and Jian Kang Zhang. "Joint Multiple-Access Channel Effective Order and CIR Estimation Algorithm for Multi-User OFDM/SDMA System." Applied Mechanics and Materials 548-549 (April 2014): 1227–30. http://dx.doi.org/10.4028/www.scientific.net/amm.548-549.1227.

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In this paper, a novel joint estimation of channel effective order and channel impulse response (CIR) is presented for multiuser orthogonal frequency division multiplexing/space-division multiple-access (OFDM/SDMA) systems. By exploiting Akaike’s Information Criterion (AIC) as the fitness function to search the optimal order, the proposed scheme performs the channel effective order and CIR estimation in a parallel way based on differential evolution (DE) algorithm. Simulation results demonstrate that the proposed scheme is capable of attaining a better mean square error performance than the fixed channel order scheme, and improving the performance of time-domain maximum likelihood (ML) channel estimator.

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14

Shi, Yue Qi, Li Jia Zhang, Bo Liu, Qi Zhang, Yong Jun Wang, Qing Hua Tian, Xiao Li Yin, and Xiang Jun Xin. "Research of a Variable Rate Real-Time Optical OFDM-PON Access System Based on Oversampling." Applied Mechanics and Materials 687-691 (November 2014): 4033–36. http://dx.doi.org/10.4028/www.scientific.net/amm.687-691.4033.

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This paper studies a variable rate optical Orthogonal Frequency Division Multiplexing Passive Optical Network (OFDM-PON) real-time access system model, using the signal processing method of oversampling. The basic principle of the model is that the access system uses different oversampling rates according to the allocated bandwidth to different Optical Network Units (ONUs), ensuring that the entire system can utilize the existing hardware conditions to maximum effect. The proposed system uses Xilinx V5 FPGA to generate real-time OFDM signals. MATLAB software is used to recover the signals and calculate the bit error rate (BER). The simulation results are presented and analyzed to verify the performance of the system.

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15

Lu, Zhiyu, Jianhui Wang, Bin Ba, and Daming Wang. "A Novel Direct Position Determination Algorithm for Orthogonal Frequency Division Multiplexing Signals Based on the Time and Angle of Arrival." IEEE Access 5 (2017): 25312–21. http://dx.doi.org/10.1109/access.2017.2766632.

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16

Hatanaka, Masahide, Toru Homemoto, and Takao Onoye. "Architecture and Implementation of Fading Compensation for Dynamic Spectrum Access Wireless Communication Systems." VLSI Design 2013 (June 6, 2013): 1–9. http://dx.doi.org/10.1155/2013/967370.

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This paper proposes an efficient architecture and implementation of fading compensation dedicated to dynamic spectrum access (DSA) wireless communication. Since pilot subcarrier arrangements are adaptively determined in wireless communication systems with DSA, the proposed architecture employs piecewise linear interpolation to the channel response estimation for data subcarriers in order to increase the channel estimation accuracy. The fading compensation for an orthogonal frequency-division multiplexing (OFDM) symbol is performed within the time for one OFDM symbol to make increase of latency smaller. The proposed architecture guarantees real-time processing with 76 MHz or higher clock frequency. The FPGA implementation of the proposed architecture occupies 1,577 slices and works up to 121 MHz.

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17

Setiawan, Erwin, Trio Adiono, Rahmat Mulyawan, Nana Sutisna, Infall Syafalni, and Wasiu O. Popoola. "A Real-Time Baseband Processor for Li-Fi Internet Access." Wireless Communications and Mobile Computing 2022 (November 8, 2022): 1–15. http://dx.doi.org/10.1155/2022/6154495.

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In the past years, light fidelity (Li-Fi) has been gaining popularity in the research. However, many researches have done only offline transmission with laboratory instruments. As a result, it is not practical to be used in commercial product, due to its cost and size. Therefore, the objective of this paper is to address problems that arise from the real-time implementation of Li-Fi system using the commercial off-the-shelf components. The implementation was developed on a low-cost system-on-chip (SoC) field-programmable gate array (FPGA). The implementation supports orthogonal frequency division multiplexing (OFDM) modulation including time synchronization. In order to build a system that is more practical to be used in commercial product, the network stack that supports TCP and ICMP was also developed. As a result, the user client can easily access the Internet using the available web browsers. The results showed that the system is functionally verified enabling it for real-time transmission to be used to access the Internet. According to the result, our baseband processor can transfer data with a maximum throughput of 1 Mbps at 125 Mhz of FPGA.

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18

Taubin, F. A. "MULTIPLE ACCESS IN WIRELESS CHANNELS USING NONORTHOGONAL CODING AND FREQUENCY INTERLEAVING." System analysis and logistics 4, no. 34 (December 20, 2022): 73–82. http://dx.doi.org/10.31799/2077-5687-2022-4-73-82.

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Code division multiple access (CDMA) is currently considered as one of the promising technologies that can significantly improve the efficiency of modern and future communication networks. In code division multiple access systems, users can share a dedicated space-frequency-time resource to simultaneously transmit their own traffic. To ensure the separation of individual user streams on the receiving side, each user is provided with his own code sequence embedded in the broadband signal transmitted by this user, the spectrum of which, as a rule, occupies the entire allocated frequency band. When centimeter-and- millimeter wave wireless channels are used as the transmission medium, such factors as fading, multipath, and Doppler scatter can significantly degrade the performance of a code division multiple access system. The standard solution in this situation is to combine code division multiple access with OFDM (orthogonal frequency division multiplexing) technology, known as multicarrier CDMA (MC-CDMA). To ensure the acceptable level of performance of multiple access systems under oversaturated conditions, many novel approaches based on the use of non-orthogonal multiple access (NOMA) have been proposed. The paper considers a variant of multiple access with non-orthogonal coding that is close in approach to sparse coding multiple access (SCMA). The proposed access procedure is based on dividing the allocated time-frequency resource into relatively small clusters and sharing each cluster with its own group of users, equipped with a non-orthogonal cluster code with the ability to change the loading factor. For the proposed class of cluster codes, a general encoding and decoding scheme is presented. Examples of specific cluster code constructions and numerical results are given that allow one to get a number of the parameters for tradeoffs between an increase of the loading factor in the system and additional energy loss.

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Diki Andriasmika, I. Wayan, I. G. A. K. Diafari Djuni H, and N. M. A. E. Dewi Wirastuti. "ANALISIS INTERCARRIER INTERFERENCE (ICI) SISTEM OFDM-MIMO STBC PADA KANAL FREQUENCY SELECTIVE FADING." Jurnal SPEKTRUM 6, no. 1 (May 10, 2019): 90. http://dx.doi.org/10.24843/spektrum.2019.v06.i01.p13.

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Wireless telecommunications requires high-speed access. One technique used tooWireless telecommunications requires high-speed access. One technique used toovercome multipath fading is Ortoghonal Frequency Division Multiplexing (OFDM). Theweakness of OFDM occurs on the mobile channel due to time variations in the channel, givingrise to intercarrier interference (ICI). The aim of the study is to determine the effect ofnormalized carrier frequency offset on ICI and the effect of frequency selective fading tapchannel. The simulation results show the system performance in calculating the Eb / N0 5 dBvalue that the greater the normalized carrier frequency offset (?), the worse the signal. Thesimulation results show the OFDM-MIMO system performance in calculating the Eb / N0 5 dBvalue that the greater the tap on the channel the worse the signal.vercome multipath fading is Ortoghonal Frequency Division Multiplexing (OFDM). Theweakness of OFDM occurs on the mobile channel due to time variations in the channel, givingrise to intercarrier interference (ICI). The aim of the study is to determine the effect ofnormalized carrier frequency offset on ICI and the effect of frequency selective fading tapchannel. The simulation results show the system performance in calculating the Eb / N0 5 dBvalue that the greater the normalized carrier frequency offset (?), the worse the signal. Thesimulation results show the OFDM-MIMO system performance in calculating the Eb / N0 5 dBvalue that the greater the tap on the channel the worse the signal.

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Ahmed, N., S. A. Aljunid, Hilal A. Fadil, R. B. Ahmad, and M. A. Rashid. "Hybrid OCDMA over WDM System Using Modified Double Weight (MDW) Code for Optical Access Network." Advanced Materials Research 433-440 (January 2012): 3878–83. http://dx.doi.org/10.4028/www.scientific.net/amr.433-440.3878.

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In this paper a hybrid optical code division multiple access (OCDMA) over wavelength division multiplexing (WDM) network is proposed to support large number of subscribers. The system combines two different techniques, namely OCDMA and WDM for supporting many subscribers simultaneously. We used modified double weight (MDW) codes as a signature address in designing the system because this code can accommodate more number of simultaneous active users under considerable standard bit error rate (e.g. ≤ 10-9). The induced MDW code for hybrid system can eliminate multiuser interference fully and increase the bit-error-rate performance compared to other codes at the same time. We ascertained by simulation results that the proposed scheme provides very good performance and enhance the network capability. Therefore, this system can be considered as a promising solution for the next generation optical access network.

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21

Uthansakul, Peerapong, and Marek E. Bialkowski. "An Adaptive Power and Bit Allocation Algorithm for MIMO OFDM/SDMA System Employing Zero-Forcing Multi-user Detection." African Journal of Information & Communication Technology 2, no. 2 (July 12, 2006): 63. http://dx.doi.org/10.5130/ajict.v2i2.217.

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The paper describes an adaptive algorithm for power and bit allocations in a multiple user Multiple Input Multiple Output Orthogonal Frequency Division Multiplexing (MIMO OFDM) system with Space Division Multiple Access, which operates in a frequency selective fading channel. The zero forcing (ZF) technique is applied to accomplish multi user detection (MUD). A Lagrange multiplier method is applied to obtain a one-step solution for optimal power and bit allocations in this system. The resulting algorithm is advantageous over an alternative Greedy algorithm, because it does not require a time-consuming iterative procedure for its implementation. The algorithm assigns bits and power for all users according to the channel state information (CSI), which is assumed to be fully or partially available to the transmitter. The simulation results show the proposed algorithm operates successfully in multiple user access scenarios.

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22

Ghanim Wadday, Ahmed Ghanim Wadday, Faris Mohammed Ali, and Hayder Jawad Mohammed Albattat. "Design of high scalability multi-subcarrier rof hybrid system based on optical CDMA/TDM." Indonesian Journal of Electrical Engineering and Computer Science 21, no. 2 (February 1, 2021): 927. http://dx.doi.org/10.11591/ijeecs.v21.i2.pp927-937.

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The technology of radio over fiber (RoF) regard a crucial point to solve problems in wireless communication system. As well as, the growth of internet applications also reveals a tremendous increase in bandwidth for different applications. Therefore, the development of optical networks is very important that have maximum bandwidth by using different multiple access techniques. Optical code division multiple access (OCDMA) technique has considered as a good solution for high bandwidth network. Hybrid optical systems of OCDMA and time division multiplexing (OTDM) has been proposed in this paper to increase the number of simultaneous users. The results of hybrid OCDMA and OTDM system demonstrate that this system can make a considerable increase in the network scalability while ensuring sufficient data rate and an acceptable bit error rate. Where M-user OCDMA signals can be transmitted in different channels of an OTDM system. Due to its wide band facility compared with other access techniques, OCDMA used here. In addition to its high scalability for our radio network, the OTDM and SCM utilized. The combination of these efficient access technique and powerful time-sharing media are lead to increase the framework system scalability.

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23

Hou, Yinan, Shilin Xiao, Haifeng Zheng, and Weisheng Hu. "Multiple Access Scheme Based on Block Encoding Time Division Multiplexing in an Indoor Positioning System Using Visible Light." Journal of Optical Communications and Networking 7, no. 5 (April 29, 2015): 489. http://dx.doi.org/10.1364/jocn.7.000489.

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24

Koyama, Akio, and Masato Akiyama. "A Media Access Control Protocol for Broadcast Type Super High-Speed WDM Networks." Journal of Interconnection Networks 04, no. 02 (June 2003): 147–62. http://dx.doi.org/10.1142/s0219265903000799.

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In this paper, we propose a new media access protocol for single hop Wavelength Division Multiplexing (WDM) networks with a passive star topology. In the conventional protocols, when the control packets collided with other ones or the packets didn't get a data channel from the channel reservation mechanism, these packets should be retransmitted. But, when transmission distance becomes long, it takes a long time to transmit the control packets and the propogation dalay time will be long. We propose a new protocol that can allocate data channels without retransmitting control packets except the collided ones. By using the proposed protocol, it is possible to reduce the transmission delay time and to get high throughput because the number of retransmitted control packets is reduced. The simulation results show that the proposed protocol has good performance comparied with conventional protocols.

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25

Maruta, Kazuki. "Frequency Domain Backoff for Continuous Beamforming Space Division Multiple Access on Massive MIMO Wireless Backhaul Systems." Journal of communications software and systems 16, no. 1 (March 15, 2020): 1–10. http://dx.doi.org/10.24138/jcomss.v16i1.920.

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This paper newly proposes a frequency domain backoff scheme dedicated to continuous beamforming space division multiple access (CB-SDMA) on massive antenna systems for wireless entrance (MAS-WE). The entrance base station (EBS) has individual base band signal processing units for respective relay stations (RSs) to be accommodated. EBS then continuously applies beamforming weight to transmission/reception signals. CB-SDMA yields virtual point-to-point backhaul link where radio resource control messages and complicated multiuser scheduling are not required. This simplified structure allows RSs to work in a distributed manner. However, one issue remains to be resolved; overloaded multiple access resulting in collision due to its random access nature. The frequency domain backoff mechanism is introduced instead of the time domain one. It can flexibly avoid co-channel interference caused by excessive spatial multiplexing. Computer simulation verifies its superiority in terms of system throughput and packet delay.

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Subhashini, N., and A. Brintha Therese. "Performance Analysis of Different Electrical Filters in 10G Hybrid Passive Optical Network." International Journal of Engineering & Technology 7, no. 4 (July 4, 2018): 6652. http://dx.doi.org/10.14419/ijet.v7i4.15758.

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With growing number of applications and network traffic, optic fibers are extensively used in the access part of the network. Passive Optical Networks (PON) in particular, Ethernet PON (EPON) networks based on Time Division Multiple Access (TDMA) are more prominently used in many parts of the world. Though Wavelength Division Multiplexing (WDM) PON has its own advantages, considering the cost and utilisation of such networks in the access part makes it less useful. On the other hand, Hybrid PON network combines the advantages of both EPON and WDM PON Networks. The objective of this paper is to identify suitable electrical filters for a 16-channel Hybrid Passive Optical Network with a transmission rate of 10Gbps per channel, by analysing their performance in terms of Q factor and Bit Error Rate. Different filters like the Bessel filter, Gaussian filter, Raised Cosine Filter, Rectangular filter, Butterworth filter, Chebyshev Filter are compared and their performances are evaluated. DB Modulation format that provides a longer reach is used at the transmitter to evaluate the different scenarios and the simulation is carried out using Optisystem.

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Alansi, Mohammed, Ibrahim Elshafiey, Abdulhameed Al-Sanie, and Md Anowar Hossain. "Multi-User Detection for Radar and Communication Multifunction System." Journal of Circuits, Systems and Computers 24, no. 03 (February 10, 2015): 1550038. http://dx.doi.org/10.1142/s0218126615500383.

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A multifunctional system that performs synthetic aperture radar (SAR) and communication tasks is presented. The system depends on orthogonal frequency division multiplexing (OFDM) waveform shaping and multiple input multiple output (MIMO) configuration to achieve enhancement in the spectral efficiency of communication operation and provide interference rejection in SAR imaging. The SAR interval idle time is utilized to enhance the communication signal through diversity. Adaptive system features are introduced to achieve multi-user detection and improve the communication reliability, by means of space division multiple access (SDMA) and space–time block coding (STBC). Investigations of linear and nonlinear multi-user detection (MUD) techniques are provided. Moreover, a genetic algorithm-based system is developed to optimize the MUD problem and to provide near-optimal performance even for overloaded scenarios. A gain of more than 4 dB is achieved at bit error rate of 10-2.

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Ahmed, Mohamed H., Octavia A. Dobre, and Rabie K. Almatarneh. "Analytical Evaluation of the Performance of Proportional Fair Scheduling in OFDMA-Based Wireless Systems." Journal of Electrical and Computer Engineering 2012 (2012): 1–12. http://dx.doi.org/10.1155/2012/680318.

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This paper provides an analytical evaluation of the performance of proportional fair (PF) scheduling in Orthogonal Frequency-Division Multiple Access (OFDMA) wireless systems. OFDMA represents a promising multiple access scheme for transmission over wireless channels, as it combines the orthogonal frequency division multiplexing (OFDM) modulation and subcarrier allocation. On the other hand, the PF scheduling is an efficient resource allocation scheme with good fairness characteristics. Consequently, OFDMA with PF scheduling represents an attractive solution to deliver high data rate services to multiple users simultaneously with a high degree of fairness. We investigate a two-dimensional (time slot and frequency subcarrier) PF scheduling algorithm for OFDMA systems and evaluate its performance analytically and by simulations. We derive approximate closed-form expressions for the average throughput, throughput fairness index, and packet delay. Computer simulations are used for verification. The analytical results agree well with the results from simulations, which show the good accuracy of the analytical expressions.

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Ramadhan, Ali J. "Overview and Comparison of Candidate 5G Waveforms: FBMC, UFMC and F-OFDM." International Journal of Computer Network and Information Security 14, no. 2 (April 8, 2022): 27–38. http://dx.doi.org/10.5815/ijcnis.2022.02.03.

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The fifth generation (5G) technology standard, utilizing the Internet of Things, promises enhanced communication systems. However, the efficiency expected from such systems entails significant requirements, such as higher data rates and flexibility of the lowest 5G layer. Meeting these requirements in subsequent wireless communication systems is highly dependent on the use of waveforms capable of efficiently enabling multiple access. In other words, proper waveforms determine the effective handling of diverse traffic within a given band. In this study, four candidate multicarrier waveforms, namely filtered orthogonal frequency division multiplexing, filter bank multicarrier, universal filtered multicarrier, and orthogonal frequency division multiplexing, which is currently used in 4G systems, are compared based on multiple parameters. MATLAB simulation results indicate that the waveforms significantly improved spectrum localization and provided appropriate spectrum fragmentation. As these waveforms can mix diverse traffic specifications, they handle the problem of time-frequency synchronization effectively. Therefore, these new waveforms exhibit significant potential in terms of orthogonality and synchronicity and can support numerous users without dropping signals. In addition, they support all applications and scenarios related to multiple-input and multiple-output. The obtained simulation results confirm the suitability of such waveforms for 5G applications and systems.

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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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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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32

Palani, K., D. Jagadeesan, R. Jothikumar, and S. Susi. "An Enhanced Peak to Average Power Ratio Reduction Scheme for Interleaved and Sub-Band Orthogonal Frequency-Division Multiple Access Frameworks with Low Complexity." Journal of Computational and Theoretical Nanoscience 16, no. 2 (February 1, 2019): 754–58. http://dx.doi.org/10.1166/jctn.2019.7804.

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Orthogonal Frequency Division Multiplexing (OFDM) is a multicarrier transmission technique which has the major drawback namely Peak to Average Power Ratio (PAPR). The high PAPR influences the efficiency of the power amplifier. The Selected Level Mapping (SLM) gives reduced PAPR contrasted with different strategies but the complexity is high due to the necessity of various Inverse Fast Fourier Transform (IFFTs). With the end goal to reduce the complexity, the proposed design requires only one IFFT, the candidate signals are produced by cyclic shifting the original time domain signal then multiplying with the distinctive genuine positive numbers. At that point the candidate with most minimal PAPR is chosen for transmission.

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33

More, Sangram, and K. Krishna Naik. "Modelling and Simulation of IDMA-OFDM for Underwater Acoustic Communication." Defence Science Journal 65, no. 4 (July 20, 2015): 307. http://dx.doi.org/10.14429/dsj.65.8606.

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The Ocean exhibits phenomenon of changing acoustic signal transmission due to its non-stationary nature. Water columns in between transmitter and receiver are not fixed at any point of time. Thus, designing of a wireless communication systems for underwater applications becomes significantly challenging. The speed of sound in water is 1500 m/s which introduces large delay spread in acoustic signal due to multipath phenomenon. The large time delay causes Inter-symbol Interference; this ISI degrades the performance of many receivers. However orthogonal frequency division multiplexing is multi-tone modulation reduces long time delay spreads of acoustic channels. The interleave division multiple access distinguishes each user with the unique random interleaver code. The IDMA-OFDM is superior design for reducing error bursts in multi-access underwater applications. A Simulink based simulation modell of IDMA-OFDM system has been discussed in this paper. Satisfactory performance of the implementation was observed through analysis of BER with respect to SNR. The results have been concluded by comparing simulated data in BER tool of Simulink.Defence Science Journal, Vol. 65, No. 4, July 2015, pp. 307-311, DOI: http://dx.doi.org/10.14429/dsj.65.8606

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34

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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Pokamestov, Dmitriy, Yakov Kryukov, Eugeniy Rogozhnikov, Islam Kanatbekuli, and Edgar Dmitriyev. "SCMA-MIMO system with adaptation to the channel state." Journal of Physics: Conference Series 2134, no. 1 (December 1, 2021): 012025. http://dx.doi.org/10.1088/1742-6596/2134/1/012025.

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Abstract Sparse code multiple access (SCMA) is one of the promising implementations of non-orthogonal multiple access (NOMA) methods. SCMA provides high spectral efficiency and a large number of network resources. We describe a communication system with SCMA, space-time block coding (STBC), multiple input multiple output (MIMO) technology, and orthogonal frequency division multiplexing (OFDM). The architecture of such systems, including algorithms of formation and processing of signals is considered. A method for adapting signals to the state of the spatial channel transmission based on information about the matrix of channel coefficients is proposed. The application of such adaptation allows to compensate the influence of the channel and to reduce the probability of bit errors. We consider the bit error rate (BER) performance of the communication system in different channel models and show the effectiveness of the proposed methods.

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Manglayev, Talgat, Refik Kizilirmak, and Nor Hamid. "GPU Accelerated PIC and SIC for OFDM-NOMA." Electronics 8, no. 3 (February 26, 2019): 257. http://dx.doi.org/10.3390/electronics8030257.

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Non-orthogonal multiple access (NOMA) is a candidate multiple access scheme for the fifth-generation (5G) cellular networks. In NOMA systems, all users operate at the same frequency and time, which poses a challenge in the decoding process at the receiver side. In this work, the two most popular receiver structures, successive interference cancellation (SIC) and parallel interference cancellation (PIC) receivers, for NOMA reverse channel are implemented on a graphics processing unit (GPU) and compared. Orthogonal frequency division multiplexing (OFDM) is considered. The high computational complexity of interference cancellation receivers undermines the potential deployment of NOMA systems. GPU acceleration, however, challenges this weakness, and our numerical results show speedups of about from 75–220-times as compared to a multi-thread implementation on a central processing unit (CPU). SIC and PIC multi-thread execution time on different platforms reveals the potential of GPU in wireless communications. Furthermore, the successful decoding rates of the SIC and PIC are evaluated and compared in terms of bit error rate.

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Narasu, Krishnamoorthy Raghavan, Immanuel Rajkumar, Jerry Alexander, and Marshiana Devaerakkam. "Impact of Equalizer step size in Underwater Acoustic Communication Channel." International Journal of Computer Network and Information Security 13, no. 1 (February 8, 2021): 29–38. http://dx.doi.org/10.5815/ijcnis.2021.01.03.

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The Underwater Acoustic Channel (UAC) is a time variant channel and its multipath effects create ISI. This is one of the most important obstacles in the UAC channel which reduces the transmission rate. To remove this obstacle, a proper filter has to be designed in the receiver section. In this article, optimal step size for equalizer is computed and compared the results with the known techniques namely Decision Feedback Equalizer with interleave division multiple access (DFE IDMA) and Cyclic Prefix - Orthogonal Frequency Division Multiplexing (CP-OFDM) Equalizer. Channels are modeled using ray tracing methods. The various factors considered are ambient noise, attenuation loss, bottom and surface loss. The overall path loss for channels is computed by summing up the attenuation loss, surface and bottom loss. Simulation results evident that for short range UAC channel, the BER in the order of 10-2 is achieved using proposed methodology with least Eb/No compared to standard DFE method.

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Zhang, Zhen Yu, Feng Chun Tian, Fan Xin Zeng, Li Jia Ge, and Gui Xin Xuan. "Symbol Timing Sequence Structure for OFDM-CDMA Communication System under Low SNR." Applied Mechanics and Materials 713-715 (January 2015): 1188–92. http://dx.doi.org/10.4028/www.scientific.net/amm.713-715.1188.

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Symbol synchronization offset of orthogonal frequency division multiplexing (OFDM) communication system will cause the rotation of data constellation at receiver even if such offset falls in the range of the appended cyclic prefix. When OFDM modulation is combined with spread spectrum technique, e.g., OFDM code division multiple access (OFDM-CDMA), the problem becomes more serious since OFDM-CDMA communication system generally works under very low signal-to-noise ratio. This paper focuses on symbol timing synchronization of OFDM-CDMA communication system and proposes an effective sequence structure on the basis of circular conjugate-symmetric properties of discrete Fourier transform. The proposed frequency-domain sequence not only can generate real time-domain signal to reduce calculation complexity, but also can resist peak-to-average power ratio of OFDM modulation by exploiting suitable computer search algorithm. The simulation results show a sharp cross-correlation peak can be obtained, which is quite helpful for accurate symbol timing synchronization of OFDM-CDMA communication system.

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39

He, Chao, and Ruyan Wang. "A QoE-Aware Energy Supply Scheme over a FiWi Access Network in the 5G Era." Sensors 20, no. 13 (July 7, 2020): 3794. http://dx.doi.org/10.3390/s20133794.

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Integrated fiber-wireless (FiWi) should be regarded as a promising access network architecture in future 5G networks, and beyond; this due to its seamless combination of flexibility, ubiquity, mobility of the wireless mesh network (WMN) frontend with a large capacity, high bandwidth, strong robustness in time, and a wavelength-division multiplexed passive optical network (TWDM-PON) backhaul. However, the key issue in both traditional human-to-human (H2H) traffic and emerging Tactile Internet is the energy conservation network operation. Therefore, a power-saving method should be instrumental in the wireless retransmission-enabled architecture design. Toward this end, this paper firstly proposes a novel energy-supply paradigm of the FiWi converged network infrastructure, i.e., the emerging power over fiber (PoF) technology instead of an external power supply. Then, the existing time-division multiplexing access (TDMA) scheme and PoF technology are leveraged to carry out joint dynamic bandwidth allocation (DBA) and provide enough power for the sleep schedule in each integrated optical network unit mesh portal point (ONU-MPP) branch. Additionally, the correlation between the transmitted optical power of the optical line terminal (OLT) and the quality of experience (QoE) guarantee caused by multiple hops in the wireless frontend is taken into consideration in detail. The research results prove that the envisioned paradigm can significantly reduce the energy consumption of the whole FiWi system while satisfying the average delay constraints, thus providing enough survivability for multimode optical fiber.

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40

Wang, Haijun, Weihua Jiang, Qing Hu, Jianjun Zhang, and Yanqing Jia. "Differential Evolution Algorithm-Aided Time-Varying Carrier Frequency Offset Estimation for OFDM Underwater Acoustic Communication." Journal of Marine Science and Engineering 10, no. 12 (November 28, 2022): 1826. http://dx.doi.org/10.3390/jmse10121826.

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Orthogonal frequency division multiplexing (OFDM) is the preferred scheme for high-speed communication in the field of underwater acoustic communication. However, it is very sensitive to the carrier frequency offset (CFO). This study used a time-varying CFO estimation method aided by the differential evolution (DE) algorithm to accurately estimate the CFO of an OFDM system. This method was based on the principle that the received OFDM signal with inter-carrier interference could be considered by a Multi Carrier-code division multiple access (MC-CDMA) system on the receiver side because MC-CDMA is a technology that combines OFDM and code division multiple access (CMDA). Because it is suitable for solving problems where there are dependencies between adjacent variables, the DE algorithm was used to capture the varying CFO values on the adjacent blocks. The spreading code of the MC-CDMA was obtained based on the estimated CFO values, which were elements in the DE solutions. Then the received signal was reconstructed. The Root-Mean-Square Error between the reconstructed and actual received signals was used as the cost function, and the CFO was estimated using the DE algorithm because of its powerful parallel search capability. The simulation results showed that the proposed method had a high estimation accuracy. Compared with other intelligent optimization algorithms such as the genetic algorithm and simulated annealing mutated-genetic algorithm, the time-varying CFO estimation performance of the DE algorithm was better because of its unique ability to solve problems with dependencies between adjacent variables. Specifically, under the condition of a high signal-to-noise ratio, the improvement of estimation accuracy reaches 36.13%, and the Bit Error Rate of demodulation is thus reduced by 75%, compared with the reference algorithms. In addition, the proposed method also has good applicability to modulation methods. For phase-shift keying and quadrature amplitude modulation, in particular, the proposed method not only achieved high-precision time-varying CFO estimation values, but also reduced the demodulation deterioration caused by noise.

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41

Róka, Rastislav. "An Effective Evaluation of Wavelength Scheduling for Various WDM-PON Network Designs with Traffic Protection Provision." Symmetry 13, no. 8 (August 23, 2021): 1540. http://dx.doi.org/10.3390/sym13081540.

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Recently, metropolitan and access communication networks have markedly developed by utilizing a variety of technologies. Their bearer communication infrastructures will be mostly exploiting the optical transmission medium where wavelength division multiplexing techniques will play an important role. This contribution discusses the symmetric sharing of common optical network resources in wavelength and time domains. Wavelength-Division Multiplexed Passive Optical Networks (WDM-PON) attract considerable attention regarding the next generation of optical metropolitan and access networks. The main purpose of this contribution is presented by the analysis of possible scheduling of wavelengths for our novel hybrid network topologies considered for WDM-PON networks. This contribution briefly deploys adequate Dynamic Wavelength Allocation (DWA) algorithms for selected WDM-PON network designs with the provision of traffic protection when only passive optical components in remote nodes are utilized. The main part of this study is focused on the use of wavelength scheduling methods for selected WDM-PON network designs. For evaluation of offline and online wavelength scheduling for novel hybrid network topologies, a simulation model realized in the Matlab programming environment allows to analyze interactions between various metropolitan and access parts in the Optical Distribution Network (ODN) related to advanced WDM-PON network designs. Finally, wavelength scheduling methods are compared from a viewpoint of utilization in advanced WDM-PON networks designs.

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42

Dang, Khoa Le, Thanh Hai Ngo, and Nghia Thai Cong Nguyen. "Performance of non-orthogonal multiple access downlink system using the Log-Likelihood ratio." Science and Technology Development Journal - Natural Sciences 4, no. 3 (August 16, 2020): First. http://dx.doi.org/10.32508/stdjns.v4i3.662.

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Non-orthogonal multiple access (NOMA) is one of the potential technologies for fifth generation (5G) cellular networks. This technique can combine with other techniques such as Orthogonal Frequency Division Multiplexing (OFDM) and Multiple Input Multiple Output (MIMO). In NOMA downlink, signals from multiple users are superposed in time-frequency domain. Hence, NOMA systems have a larger throughput than orthogonal multiple access systems. There are several schemes for NOMA detection. The successive interference cancellation (SIC) is commonly used to decode desired signals at the receivers. Some NOMA schemes with SIC are ideal SIC, symbol-level SIC and codeword-level SIC. The previous studies showed that the log-likelihood ratio (LLR) has a performance as ideal SIC. In this paper, we derive the bit error rate for a NOMA downlink system with 2 users (UE) using LLR receiver. This study considers the system over a Rayleigh fading channel and the presence of Additive White Gaussian Noise. The closed-form equations have been proposed for each user with QPSK mapping. The simulation results show that the performance of the system is consistent with the proposed formula

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Yerrapragada, Anil Kumar, and Brian Kelley. "On the Application of K-User MIMO for 6G Enhanced Mobile Broadband." Sensors 20, no. 21 (November 2, 2020): 6252. http://dx.doi.org/10.3390/s20216252.

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This paper presents a high-throughput wireless access framework for future 6G networks. This framework, known as K-User MIMO, facilitates all-to-all communication between K access points and K mobile devices. For such a network, we illustrate the demodulation of K2 independent data streams through a new interference cancellation beamforming algorithm that improves spectral efficiency compared to massive MIMO. The paper derives a multi-user Shannon Capacity formula for K-User MIMO when K is greater than or equal to 3. We define an Orthogonal Frequency Division Multiplexing (OFDM) frame structure that demonstrates the allocation of time-frequency resources to pilot signals for channel estimation. The capacity formula is then refined to include realistic pilot overheads. We determine a practical upper-bound for MIMO array sizes that balances estimation overhead and throughput. Lastly, simulation results show the practical capacity in small cell geometries under Rayleigh Fading conditions, with both perfect and realistic channel estimation.

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44

Avendaño-Lopez, Carlos M., Rogelio Castro-Sanchez, Dora L. Almanza-Ojeda, Juan Gabriel Avina-Cervantes, Miguel A. Gomez-Martinez, and Mario A. Ibarra-Manzano. "Scalable Visible Light Indoor Positioning System Using RSS." Mathematics 10, no. 10 (May 19, 2022): 1738. http://dx.doi.org/10.3390/math10101738.

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This paper proposes a visible light positioning system that utilizes commercial Light-Emitting Diode (LED) lamps as transmitters and Silicon PIN photodiodes as receivers. The light signals are transmitted and received using Intensity Modulation and Direct Detection (IMDD). The lamps are modulated using On–Off Keying (OOK) with the Manchester code, and the medium access control is achieved by Time-Division Multiplexing (TDM). The position is estimated using trilateration based on the Received Signal Strength (RSS). The system’s scalability is accomplished by replicating primary localization cells composed of seven lamps and drawing on the neighborhood synchrony, exploiting the spatial multiplexing property of the light. A basic unit in the cell comprises three lamps forming a localization triangle; then, one primary localization cell shall consist of six triangles sharing lights among basic neighbor units. The cell prototype was implemented to prove the working principle of the system. Three estimation methods were used to compute the position: a deterministic approach based on least-squares regression, an Artificial Neural Network (ANN) per lamp, and an ANN for the complete system. The best per lamp estimator was the ANN, computing positions that reached an experimental accuracy of 2.5 cm under indoor conditions.

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45

Polyakov, Nikita, and Anna Platonova. "Assessing Latency of Packet Delivery in the 5G 3GPP Integrated Access and Backhaul Architecture with Half-Duplex Constraints." Future Internet 14, no. 11 (November 21, 2022): 345. http://dx.doi.org/10.3390/fi14110345.

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Integrated Access and Backhaul (IAB) is an enabling technology for efficient 5G millimeter wave (mmWave) New Radio (NR) deployment. The key feature of IAB is multi-hop wireless backhauling, allowing utilizing relaying IAB-nodes to provide cost-efficient access network densification and alleviate the problem of blockages. One of the critical performance measures in such systems is the latency of packet delivery over the multi-hop paths. The paper aims at assessing the impact of multi-hop transmission on the end-to-end delay in an IAB radio access network, taking into account the half-duplex constraint. We build a detailed queuing theory model for latency assessment in time-division-multiplexing (TDM)-based IAB deployments and evaluate the delay due to queuing in the network nodes for several cell topologies and under different time allocation strategies between access and backhaul. The paper considers a practical Manhattan-style urban deployment, which is characteristically impaired by the blockage of buildings. The numerical results show that balancing the access and backhaul micro phases is crucial for reducing the end-to-end packet delay, at least in the uplink, while increasing the number of network hops yields a linear increase in the total packet delay for both the uplink and downlink. The numerical results were obtained via simulation using the open-source software OMNeT++.

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46

MAKARISHKIN, DENYS, M. LYUBARSKY, and V. MISHAN. "MODERN RADIO TECHNOLOGIES FOR M2M COMMUNICATION." Herald of Khmelnytskyi National University 303, no. 6 (December 2021): 225–28. http://dx.doi.org/10.31891/2307-5732-2021-303-6-225-228.

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The aim of the study is to analyze the functioning of the PRACH system in overload conditions, when a large number of M2M devices with different priorities establish their connection to the access network. Fifth-generation (5G) systems provide increased data rates, use of low-latency over-the-counter (URLLC), have high spectral efficiencies, extensive connectivity, and increased energy efficiency. Multiplexing with orthogonal frequency division multiplexing and filter (F-OFDM) is a signal received at the output of the filter. F-OFDM compared to OFDM provides a reduction in out-of-band radiation, which improves system performance. The article is devoted to the comparison of CP-OFDM and F-OFDM signals. Connecting multiple M2M devices to the network in a short period of time can cause a surge in PRACH channel loading due to its limited capacity. It is also interesting to note that the PRACH preambles, randomly selected by M2M devices, can be considered as code "channels" that do not overlap. When two or more terminals choose an identical preamble (channel), a situation resembling a typical collision between data packets occurs. This interpretation allows us to study the process of competition between M2M devices, based on the known results obtained for multi-channel random access protocols. As a result, it is possible to obtain an exact approximation in a given range of parameters of the PRACH system, such as the number of available preambles (M) and competing terminals (U), the size of the delay window, etc.

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47

Ibarra-Delgado, Salvador, Remberto Sandoval-Arechiga, José Ricardo Gómez-Rodríguez, Manuel Ortíz-López, and María Brox. "A Bandwidth Control Arbitration for SoC Interconnections Performing Applications with Task Dependencies." Micromachines 11, no. 12 (November 30, 2020): 1063. http://dx.doi.org/10.3390/mi11121063.

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Current System-on-Chips (SoCs) execute applications with task dependency that compete for shared resources such as buses, memories, and accelerators. In such a structure, the arbitration policy becomes a critical part of the system to guarantee access and bandwidth suitable for the competing applications. Some strategies proposed in the literature to cope with these issues are Round-Robin, Weighted Round-Robin, Lottery, Time Division Access Multiplexing (TDMA), and combinations. However, a fine-grained bandwidth control arbitration policy is missing from the literature. We propose an innovative arbitration policy based on opportunistic access and a supervised utilization of the bus in terms of transmitted flits (transmission units) that settle the access and fine-grained control. In our proposal, every competing element has a budget. Opportunistic access grants the bus to request even if the component has spent all its flits. Supervised debt accounts a record for every transmitted flit when it has no flits to spend. Our proposal applies to interconnection systems such as buses, switches, and routers. The presented approach achieves deadlock-free behavior even with task dependency applications in the scenarios analyzed through cycle-accurate simulation models. The synergy between opportunistic and supervised debt techniques outperforms Lottery, TDMA, and Weighted Round-Robin in terms of bandwidth control in the experimental studies performed.

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48

Asif Khan, Muhammad Kamal, Farman Ali, Muhammad Irfan, Fazal Muhammad, Faisal Althobiani, Asar Ali, Suliman Khan, Saifur Rahman, Grzegorz Perun, and Adam Glowacz. "Mitigation of Phase Noise and Nonlinearities for High Capacity Radio-over-Fiber Links." Electronics 10, no. 3 (February 1, 2021): 345. http://dx.doi.org/10.3390/electronics10030345.

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Radio-over-fiber (RoF) links successfully provide high data rates and bandwidth capacity with a low complexity system architecture, as compared to its counterpart digital-RoF. In addition, the compound of quadrature amplitude modulation (QAM) and orthogonal frequency division multiplexed (OFDM) modulation schemes further enhance the process of these achievements. However, high data rates and bandwidth-capacity-supported RoF links face nonlinearities (NLs), linear distortions (LDs), and phase noise challenges that degrade the reliability of communication networks (CNs). Therefore, in this paper, to suppress NLs, LDs, and phase noise, next generation cloud radio access networks (CRANs) are investigated using RoF links and wavelength division multiplexing (WDM) methodology based on 16, 32, and 64 QAM-OFDM modulation schemes. The receiver of the proposed framework is designed, applying an improved digital signal processing (DSP) system that includes overlap frequency domain equalization (OFDE), a synchronization process, and time domain equalization (TDE). Theoretical and simulation models are organized for estimating the proposed RoF link with the aid of different values of transmission ranges, input power, output power, bit rate, bits per symbol, channel spacing, and the number of users. The fitness of the model matches that of existing approaches.

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49

Mestoui, Jamal. "A Novel PM-OFDM-CDMA System for 5G Wireless Communication with High Capacity and Low Energy Consumption." ASM Science Journal 16 (November 3, 2021): 1–8. http://dx.doi.org/10.32802/asmscj.2021.786.

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Phase Modulation Orthogonal Frequency Division Multiplexing (PM-OFDM) and Code Division Multiple Access (CDMA) have distinctive advantages. On one hand, PM-OFDM is an attractive technique to combat multipath fading and reduce high PAPR in conventional OFDM. On the other hand, CDMA has the ability to serve multiple users at the same time and/or frequency. In this article, a new PM-OFDM-CDMA system that combines PM-OFDM and CDMA is proposed. The idea behind the proposed technique is to combine the advantages of these techniques in order to enhance the performance of the 5G system by serving multiple users simultaneously. The performance of the proposed system is analysed in terms of BER under different channel conditions. A Minimum Mean Square Equaliser (MMSE) scheme is used in order to avoid the effect of multipath effect and noise simultaneously. From the simulation results, we conclude that the proposed system has good performance that can improve 5G wireless communication networks, especially for battery-powered mobile devices. This amounts to the constant envelope of the proposed waveform which generates constant instantaneous power and therefore reduced PAPR.

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50

Ibrahim, Sarmad Khaleel, Nooruldeen Q. Ismaeel, and Saif A. Abdulhussien. "Comparison study of channel coding on non-orthogonal multiple access techniques." Bulletin of Electrical Engineering and Informatics 11, no. 2 (April 1, 2022): 909–16. http://dx.doi.org/10.11591/eei.v11i2.3348.

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Some of the benefits of fifth-generation (5G) mobile communications include low latency, fast data rates, and increased amount of perceived service quality of users and base station capacity. The purpose of this paper is to solve some of the problems in the traditional mobile system by increasing the channel capacity, non-orthogonal multiple access (NOMA), has a chance of winning the race, power-domain NOMA (PD-NOMA) is widely used in but it requires a large power imbalance between the signals allocated to various users to work. This paper also proposes an improved mobile system model and compares it with a traditional mobile system, then evaluates the effect of channel coding types on the spectrum efficiency performance. A proposed mobile system relied on increasing the number of users as well as increasing the frequency spectrum and is also proposed to improve the error rate, which is incorporated into NOMA and orthogonal frequency division multiplexing (OFDM) schemes at the same time to provide great ﬂexibility and compatibility with other services, such as the 5G and sixth-generation (6G) systems. The mobile gully system (MGS) system is compared to a traditional system, the result is demonstrated that the proposed outperforms the orthogonal multiple access (OMA) system in terms of sum-rate capacity, and bit error rate (BER) performance.

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