• Title/Summary/Keyword: Signal-to-Interference and Noise Ratio

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Performance Analysis of Large CDMA Random Access Systems with Retransmission Diversity over Fading Channels

  • Yu, Kai;Sun, Yi;Fan, Pingzhi;Lei, Xianfu;Shu, Lei
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.4 no.4
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    • pp.509-528
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    • 2010
  • The random access systems, with retransmission diversity (RD) employment, over large random spreading code division multiple access (CDMA) channel subject to fading is investigated, under the assumption of infinite number of users and infinite spreading gain with their ratio converging to a constant. The low bound of the signal to interference and noise ratio (SINR) is shown to converge almost surely to a constant. The throughput, spectrum efficiency and energy efficiency in the dominating systems are obtained. The analytical results are confirmed by simulations. We find that in high traffic loads the throughput with fading is higher than that without. When the energy efficiency increases, the spectrum efficiency tends to two contrary values due to SNR increases or decreases. For the ordinary stable systems, the stability region is shown to shrink as the traffic increases and enlarge with RD employment.

A Performance Improvement of FC-MMA Blind Equalization Algorithm based on Varying Step Size (가변 스텝 크기를 적용한 FC-MMA 블라인드 등화 알고리즘의 성능 개선)

  • Lim, Seung-Gag
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.19 no.5
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    • pp.101-106
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    • 2019
  • This paper propose the VSS-FC-MMA algorithm that is possible to improve the equalization performance based on varying step size to the FC-MMA adaptive equalization algorithm in order to reducing the intersymbol interference effect occurred in the nonconstant modulus signal transmission, and improved performance were confirmed. The FC-MMA is possible to improve the convergence speed, and degrades the steady state performance based on the fixed step size and modified dispersion constant considering the level number of signal symbol for obtain the error signal in adaptive equalization compared to MMA. The proposed VSS-FC-MMA uses varying step size and current FC-MMA possible to improve the steady state equalization performance, it was confirmed by computer simulation. For this, the signal recovery capabilities and residual isi, MSE, SER were applied for performance comparison index in the same channel and signal to noise ratio. As a result of computer simulation, the proposed VSS-FC-MMA improve the risidual value in steady state and SER performance than the FC-MMA, but has 1.7 times slow convergence time by using varying step size.

On the block error rate performance of cooperative non-orthogonal multiple access short-packet communications with full-duplex relay and partial relay selection

  • Ha Duy Hung;Hoang Van Toan;Tran Trung Duy;Le The Dung;Quang Sy Vu
    • ETRI Journal
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    • v.46 no.3
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    • pp.446-460
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    • 2024
  • In this paper, we mathematically investigate a downlink non-orthogonal multiple access (NOMA) system for short-packet communications (SPC) in which the near users are used as full-duplex (FD) relays to forward intended signals from the source to a far user. In addition, partial relay selection is employed to enhance the performance of the FD relays under the impact of imperfect interference cancellation. At the far user, selection combining (SC) or maximal ratio combining (MRC) is employed to combine the signals received from the source and the selected FD relay. The analytical expressions for the average block error rate (BLER) of two users over flat Rayleigh fading channels are derived. Furthermore, closed-form asymptotic expressions of the average BLERs at the near and far users in high signal-to-noise ratio (SNR) regimes are obtained. The numerical results show that the analytical BLERs of the near user and far user closely match the simulation results.

SINR-Based Multipath Routing for Wireless Ad Hoc Networks

  • Park, Ji-Won;Moh, Sang-Man;Chung, Il-Yong
    • Journal of Korea Multimedia Society
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    • v.13 no.6
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    • pp.849-864
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    • 2010
  • This paper proposes a multipath routing protocol called cross-layer multipath AODV (CM-AODV) for wireless ad hoc networks, which selects multiple routes on demand based on the signal-to-interference plus noise ratio (SINR) measured at the physical layer. Note that AODV (Ad hoc On-demand Distance Vector) is one of the most popular routing protocols for mobile ad hoc networks. Each time a route request (RREQ) message is forwarded hop by hop, each forwarding node updates the route quality which is defined as the minimum SINR of serialized links in a route and is contained in the RREQ header. While achieving robust packet delivery, the proposed CM-AODV is amenable to immediate implementation using existing technology by neither defining additional packet types nor increasing packet length. Compared to the conventional multipath version of AODV (which is called AOMDV), CM-AODV assigns the construction of multiple paths to the destination node and makes it algorithmically simple, resulting in the improved performance of packet delivery and the less overhead incurred at intermediate nodes. Our performance study shows that CM-AODV significantly outperforms AOMDV in terms of packet delivery ratio and average end-to-end delay, and results in less routing overhead.

Equalizer Mode Selection Method for Improving Bit Error Performance of Underwater Acoustic Communication Systems (수중음향통신 시스템의 비트 오류 성능 향상을 위한 등화 모드 선택 방법)

  • Kim, Hyeon-Su;Seo, Jong-Pil;Kim, Jae-Young;Kim, Seong-Il;Chung, Jae-Hak
    • The Journal of the Acoustical Society of Korea
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    • v.31 no.1
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    • pp.1-10
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    • 2012
  • The linear and decision-feedback equalization can mitigate time-varying intersymbol interference (ISI) caused by time-varying multipath propagation for underwater acoustic channels. The perfect elimination of interference components, however, is difficult using the linear equalization and the decision feedback equalizer has an error propagation problem. To overcome these shortcomings, this paper proposes an equalizer mode selection method using training sequences. The proposed method selects an equalization mode corresponding to the signal-to-noise ratio (SNR). If the SNR is low, the proposed system operates the linear equalizer for preventing the error propagation and if the SNR is high, the decision feedback equalizer for eliminating the residual ISI. Therefore, the proposed method can improve the error performance compared to the conventional equalizers. The computer simulation shows the proposed method improves the bit error performance using practical underwater channels responses acquired from the sea experiment.

Performance Analysis on Digital Phase Difference Measurement Techniques for Interferometer Direction Finder (인터페로미터 방향 탐지기의 디지털 위상차 측정 기법 성능 분석)

  • Kang, Jong-jin;Park, Sung-kyun;Roh, Ji-hyun
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.22 no.8
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    • pp.1076-1082
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    • 2018
  • This paper describes interferometer direction finder which measures the angle of arrival based on calculation of the phase difference of received radio signal from different antennas. Modern Electronic Warfare direction finder uses digital phase difference measuring techniques which have less effect on temperature variation and better performance under low Signal to Noise Ratio environment. In this paper, we analyze acceptable phase difference error for requirement of system's direction finding accuracy and introduce digital phase difference calculation techniques. We have investigated quantitative analysis on phase difference calculation according to sample number, SNR, interference injection. Through the simulation, frequency domain measurement technique is better performance than the time domain one at the environment of low SNR and interference injection. Proposed method can be used to determine the performance of interferometer direction finder.

A Triple-Band Transceiver Module for 2.3/2.5/3.5 GHz Mobile WiMAX Applications

  • Jang, Yeon-Su;Kang, Sung-Chan;Kim, Young-Eil;Lee, Jong-Ryul;Yi, Jae-Hoon;Chun, Kuk-Jin
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.11 no.4
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    • pp.295-301
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    • 2011
  • A triple-band transceiver module for 2.3/2.5/3.5 GHz mobile WiMAX, IEEE 802.16e, applications is introduced. The suggested transceiver module consists of RFIC, reconfigurable/multi-resonance MIMO antenna, embedded PCB, mobile WiMAX base band, memory and channel selection front-end module. The RFIC is fabricated in $0.13{\mu}m$ RF CMOS process and has 3.5 dB noise figure(NF) of receiver and 1 dBm maximum power of transmitter with 68-pin QFN package, $8{\times}8\;mm^2$ area. The area reduction of transceiver module is achieved by using embedded PCB which decreases area by 9% of the area of transceiver module with normal PCB. The developed triple-band mobile WiMAX transceiver module is tested by performing radio conformance test(RCT) and measuring carrier to interference plus noise ratio (CINR) and received signal strength indication (RSSI) in each 2.3/2.5/3.5 GHz frequency.

Probabilistic Constrained Approach for Distributed Robust Beamforming Design in Cognitive Two-way Relay Networks

  • Chen, Xueyan;Guo, Li;Dong, Chao;Lin, Jiaru;Li, Xingwang;Cavalcante, Charles Casimiro
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.12 no.1
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    • pp.21-40
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    • 2018
  • In this paper, we propose the distributed robust beamforming design scheme in cognitive two-way amplify-and-forward (AF) relay networks with imperfect channel state information (CSI). Assuming the CSI errors follow a complex Gaussian distribution, the objective of this paper is to design the robust beamformer which minimizes the total transmit power of the collaborative relays. This design will guarantee the outage probability of signal-to-interference-plus-noise ratio (SINR) beyond a target level at each secondary user (SU), and satisfies the outage probability of interference generated on the primary user (PU) above the predetermined maximum tolerable interference power. Due to the multiple CSI uncertainties in the two-way transmission, the probabilistic constrained optimization problem is intractable and difficult to obtain a closed-form solution. To deal with this, we reformulate the problem to the standard form through a series of matrix transformations. We then accomplish the problem by using the probabilistic approach based on two sorts of Bernstein-type inequalities and the worst-case approach based on S-Procedure. The simulation results indicate that the robust beamforming designs based on the probabilistic method and the worst-case method are both robust to the CSI errors. Meanwhile, the probabilistic method can provide higher feasibility rate and consumes less power.

A Performance Comparison of DSE-MMA and DQE-MMA Adaptive Equalization Algorithm using Dither Signal (Dither 신호를 이용한 DSE-MMA와 DQE-MMA 적응 등화 알고리즘의 성능 비교)

  • Lim, Seung-Gag;You, Jeong-Bong;Kang, Dae-Soo
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.22 no.1
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    • pp.45-50
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    • 2022
  • This paper compares the equalization performance of the DSE-MMA (Dithered Signed Error-MMA) and DQE-MMA (Dithered Quantized Error-MMA) adaptive equalization algorithm based on the dither signal in order to reduce the intersymbol interference occurs at communication channel. These algorithm was emerged in ordr to reduction of arithmetic operation than current MMA, it makes the independent and identical distribute the quantized error component by performing the 1 or N bit quautizer after adding the dither singal in obtaining the error signal for adapting process. It is possible to improve the robustness performance of adaptive algorithm, but degrade the MSE performance in steady state by dither signal. The paper directly compare the DSE-MMA and DQE-MMA adaptive equalization performance of the same concept of dithering in the same communication channel and signal to noise ratio by computer simulation. As a result of simulation, the DQE-MMA has more better in the every performance index, equalizer output constellation, residual isi, MSE and SER performance, but not in convergence speed.

Partial CSI-Based Cooperative Power Allocation in Multi-Cell Dual-Hop MISO Relay Systems (다중-셀 이중-홉 MISO 릴레이 시스템에서 부분 채널 정보를 이용한 협력 전력 할당 기법)

  • Cho, Hee-Nam;Kim, Ah-Young;Lee, Jin-Woo;Lee, Young-Hwan
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.34 no.9C
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    • pp.887-895
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    • 2009
  • This paper proposes a cooperative power allocation with the use of partial channel information (e.g., the average signal-to-noise ratio (SNR) and transmit correlation) in multi-cell dual-hop multi-input single-output (MISO) relay systems. In a dual-hop MISO relay channel, it is desirable to allocate the transmit power between dual-hop links to maximize the end-to-end capacity. We consider the maximization of the end-to-end capacity of a dual-hop MISO relay channel under sum-power constraint. The proposed scheme adaptively allocates the transmit power considering the average channel gain of the target relay and the transmit correlation of the desired and inter-relay interference channel from adjacent relays. It is shown by means of upper-bound analysis that the end-to-end capacity can be maximized by making the angle difference of the principal eigenvectors of the desired and inter-relay interference channel orthogonal in highly-correlated channel environments. Finally, the performance of the proposed scheme is verified by computer simulation.