• Title/Summary/Keyword: Gaussian interference channel

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Sum-Rate Optimal Power Policies for Energy Harvesting Transmitters in an Interference Channel

  • Tutuncuoglu, Kaya;Yener, Aylin
    • Journal of Communications and Networks
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    • v.14 no.2
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    • pp.151-161
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    • 2012
  • This paper considers a two-user Gaussian interference channel with energy harvesting transmitters. Different than conventional battery powered wireless nodes, energy harvesting transmitters have to adapt transmission to availability of energy at a particular instant. In this setting, the optimal power allocation problem to maximize the sum throughput with a given deadline is formulated. The convergence of the proposed iterative coordinate descent method for the problem is proved and the short-term throughput maximizing offline power allocation policy is found. Examples for interference regions with known sum capacities are given with directional water-filling interpretations. Next, stochastic data arrivals are addressed. Finally, online and/or distributed near-optimal policies are proposed. Performance of the proposed algorithms are demonstrated through simulations.

Exact Error Rate of Dual-Channel Receiver with Remote Antenna Unit Selection in Multicell Networks

  • Wang, Qing;Liu, Ju;Zheng, Lina;Xiong, Hailiang
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.10 no.8
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    • pp.3585-3601
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    • 2016
  • The error rate performance of circularly distributed antenna system is studied over Nakagami-m fading channels, where a dual-channel receiver is employed for the quadrature phase shift keying signals detection. To mitigate the Co-Channel Interference (CCI) caused by the adjacent cells and to save the transmit power, this work presents remote antenna unit selection transmission based on the best channel quality and the maximized path-loss, respectively. The commonly used Gaussian and Q-function approximation method in which the CCI and the noise are assumed to be Gaussian distributed fails to depict the precise system performance according to the central limit theory. To this end, this work treats the CCI as a random variable with random variance. Since the in-phase and the quadrature components of the CCI are correlated over Nakagami-m fading channels, the dependency between the in-phase and the quadrature components is also considered for the error rate analysis. For the special case of Rayleigh fading in which the dependency between the in-phase and the quadrature components can be ignored, the closed-form error rate expressions are derived. Numerical results validate the accuracy of the theoretical analysis, and a comparison among different transmission schemes is also performed.

Performance of 8SQAM Modem in a Nonlineraly Amplified Multi-Channel Interference Environment (비선형 증폭 다중채널 간섭환경에서의 8SQAM 모뎀 성능)

  • 성봉훈;서종수
    • Proceedings of the Korean Society of Broadcast Engineers Conference
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    • 2002.11a
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    • pp.3-8
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    • 2002
  • A new Modem technique - 8-state Superposed QAM(8SQAM) - for use in power and bandwidth limited digital communication system is proposed. The premodulation baseband signal of the 8SQAM system is a double-interval(2Ts) raised cosine pulse superposed with weighted single-interval(Ts) raised cosine pulse. The performance of the 8SQAM, in a nonlinearly amplified multi-channel environment with additive white Gaussian noise(AWGN), inter-symbol interference(ISI), inter-modulation(IM) and adjacent channel interference(ACI), is analyzed via computer simulation. The simulation result shows that the 8SQAM outperforms 8PSK by about 1.6㏈ at BER=$1\times10^{-4}$ when HPA IBO is 1㏈ and channel Spacing, ${\Delta}F$ is 0.417fb.

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A Study on Blind Adaptive Interference Suppression for DS-CDMA systems (DS-CDMA 시스템을 위한 블라인드 적응 간섭 억제에 관한 연구)

  • 우대호;윤태성;변윤식
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.24 no.10B
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    • pp.1995-2003
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    • 1999
  • Since the cross-correlation function which is due to communication channel distortion or interference is not orthogonal, near far problem and multi-user interference are generated in the DS-CDMA system. Those problems degrade performance of the system so that the efficient algorithm to suppress the interference in the DS-CDMA system is required. In this paper, a blind adaptive interference suppressor using constant modulus algorithm is proposed. Simulation results present that the gain of SIR for the blind adaptive receiver is about 7[dB] at steady state over Gaussian channel in forward channel. The gain of noise to interference ration is about 4[dB] over Rayleigh fading channel, is about 11[dB] over multipath channels. Thus the proposed receiver has higher performance than a conventional receiver in the DS-CDMA system.

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Blind Channel Estimator based on the RLS algorithm (RLS 알고리즘에 기반을 둔 블라인드 채널 추정)

  • 서우정;하판봉;윤태성
    • Proceedings of the IEEK Conference
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    • 1999.11a
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    • pp.655-658
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    • 1999
  • In this study, We derived Recursive Least Squares(RLS) algorithm with adaptive maximum -likelihood channel estimate for digital pulse amplitude modulated sequence in the presence of intersymbol interference and additive white Gaussian noise. RLS algorithms have better convergence characteristics than conventional algorithms, LMS Least Mean Squares) algorithms.

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Intersymbol Interferences Due to Mismatched Roll-off Factors and Sampling-Time Jitter in a Gaussian Noise Channel

  • Park, Seung Keun;Mok, Jin Dam;Na, Sang Sin
    • The Journal of the Acoustical Society of Korea
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    • v.16 no.2E
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    • pp.47-54
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    • 1997
  • This paper presents two results on intersymbol interferences in baseband digital communication over an additive white Gaussian noise channel-the interferences due to mismatched square-root raised-cosine filters, in which the filters have different roll-off factors, and / or due to sampling-time jitter. The result for the mismatched filters is that even the jitter-free sampling causes intersymbol interference and it is negligibly small for a wide range of signal-to-noise ratio up to 10dB, for the roll-off factor ranging from 0.2 to 0.5, the mismatch loss being within 0.1dB from the optimum at around 10-6 .For jitter interference an approximation formula for the bit error probability is derived in case of the matched filters, which shows how the roll-off factors and the amount of jitter affect the system performance. The formula is reasonably accurate.

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Capacity Bounds in Random Wireless Networks

  • Babaei, Alireza;Agrawal, Prathima;Jabbari, Bijan
    • Journal of Communications and Networks
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    • v.14 no.1
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    • pp.1-9
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    • 2012
  • We consider a receiving node, located at the origin, and a Poisson point process (PPP) that models the locations of the desired transmitter as well as the interferers. Interference is known to be non-Gaussian in this scenario. The capacity bounds for additive non-Gaussian channels depend not only on the power of interference (i.e., up to second order statistics) but also on its entropy power which is influenced by higher order statistics as well. Therefore, a complete statistical characterization of interference is required to obtain the capacity bounds. While the statistics of sum of signal and interference is known in closed form, the statistics of interference highly depends on the location of the desired transmitter. In this paper, we show that there is a tradeoff between entropy power of interference on the one hand and signal and interference power on the other hand which have conflicting effects on the channel capacity. We obtain closed form results for the cumulants of the interference, when the desired transmitter node is an arbitrary neighbor of the receiver. We show that to find the cumulants, joint statistics of distances in the PPP will be required which we obtain in closed form. Using the cumulants, we approximate the interference entropy power and obtain bounds on the capacity of the channel between an arbitrary transmitter and the receiver. Our results provide insight and shed light on the capacity of links in a Poisson network. In particular, we show that, in a Poisson network, the closest hop is not necessarily the highest capacity link.

A Comparison of the Error Rate Performances of Various Digitally Modulated Signals in the Environment of Tone/Multiple Interferer (톤간섭 및 다중간섭하에서 제반 디지탈 변조신호의 오율특성 비교)

  • 공병옥;조성준
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.15 no.10
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    • pp.797-810
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    • 1990
  • The error rate equations of digitally modulated signals transmitted through the Gaussian noise and tone multiple interference channel have been derived. Using the derived equations of error probabilities in the environments of Gaussian noise tone interferer and Gaussian noise multiple interferer, the error rate performances of various digitally modulated signals have been evaluated, and compared in graphs as a function of average carrier to tone interferer power ratio(CIR), average carrier to multiple interferer power ratio(CIT) and the average carrer-to-Gaussian noise powr ratio(CIR). In this paper, the modulation schemes such as amplitude shift keying (ASK), phase shift keying(PSK), frequency shift keying(FSK), minimum shift keying(MSK), quadrature amplitud modulation(QAM) and amplitude phase shift keying(APK) have been selected for the study of performance comparison. The results of comparison show us that, in low bits/sec/Hz, PSK is superior to the other schemes, but in high bits/sec/Hz, mixed multi ary type is better than single multi ary type. And in strong noise evironment, the multiple interferer has much influence than tone interferer, however, in low noise environment. the mojor error factor is tone interferer. But tone interference effect nearly disappears over specified CIR level about 20[dB]. And the modulation schemes using amplitude are heavily influenced by multiple interference.

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Lattice Code of Interference Alignment for Interference Channel with 3 Users in CoMP (세 명의 사용자의 간섭 채널을 위한 협력 다중점 송수신(CoMP)에서의 격자(Lattice) 부호 간섭 정렬)

  • Lee, Moon-Ho;Peng, Bu Shi
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.49 no.6
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    • pp.27-38
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    • 2012
  • In this paper, we introduce CoMP in 3GPP LTE-Advanced Release 11 to take care of shadowing effects appearing in cell-edge areas to meet rapidly increasing demand for high speed transmission and multi-media data. In order to mitigate interference, orthogonalizing is ideal but it is slightly difficult to be applied to real systems. Therefore, interference alignment and avoidance are used in practical applications. Interference alignment is a scheme enabling us to consider interference our friend not enemy. We show lattice codes in Gaussian channel achieve Shannon capacity where strong interference exists. In addition, we show the relationship between channel parameter a and DoF(Degree of Freedom) applying lattice codes to interference alignment for interference channel with three users.

Performance of M-ary PPM UWB Radio in Fading Channels

  • Mohammed, Abdel-Hafez;Alagoz, Fatih;Hamalainen, Matti
    • Journal of Communications and Networks
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    • v.5 no.4
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    • pp.365-373
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    • 2003
  • This paper investigates the performance of M-ary pulse position modulation (PPM) multiuser ultra-wideband (UWB) communication systems in terms of symbol error rate (SER) over fading and additive white Gaussian noise (AWGN) channel. Based on Gaussian approximation for the multiple access interference, an expression for the signal-to-noise ratio (SNR) is derived for the UWB system. This expression is used to derive exact SER expressions for coherent UWB receivers. The effect of pulse selection on the SER of multiuser UWB system is studied. In addition to rectangular pulse, the 2nd derivative Gaussian waveform and Rayleigh pulses were considered. We show that the system capacity and/or SER performance can be significantly increased by using the monocycle pulse in fading channels.