• Title/Summary/Keyword: Random Channel

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Random Access Channel with Retransmission Gain

  • Shi, Junmin;Sun, Yi;Zhang, Xiaochen;Xiao, Jizhong
    • IEIE Transactions on Smart Processing and Computing
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    • v.2 no.3
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    • pp.148-159
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    • 2013
  • An analysis of the throughput and stability region of random access systems is currently of interest in research and industry. This study evaluated the performance of a multiuser random access channel with a retransmission gain. The channel was composed of a media access control (MAC) determined by the transmission probabilities and a multiuser communication channel characterized by the packet reception probabilities as functions of the number of packet transmissions and the collision status. The analysis began with an illustrative two-user channel, and was extended to a general multiuser channel. For the two-user channel, a sufficient condition was derived, under which the maximum throughput was achieved with a control-free MAC. For the channel with retransmission gain, the maximum steady throughput was obtained in a closed form. The condition under which the random access channel can acquire retransmission gain was also obtained. The stability region of the general random access channel was derived. These results include those of the well-known orthogonal channel, collision channel and slotted Aloha channel with packet reception as a special instance. The analytical and numerical results showed that exploiting the retransmission gain can increase the throughput significantly and expand the stability region of the random access channel. The analytical results predicted the performance in the simulations quite well.

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Applying the Nash Equilibrium to Constructing Covert Channel in IoT

  • Ho, Jun-Won
    • International Journal of Internet, Broadcasting and Communication
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    • v.13 no.1
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    • pp.243-248
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    • 2021
  • Although many different types of covert channels have been suggested in the literature, there are little work in directly applying game theory to building up covert channel. This is because researchers have mainly focused on tailoring game theory for covert channel analysis, identification, and covert channel problem solving. Unlike typical adaptation of game theory to covert channel, we show that game theory can be utilized to establish a new type of covert channel in IoT devices. More specifically, we propose a covert channel that can be constructed by utilizing the Nash Equilibrium with sensor data collected from IoT devices. For covert channel construction, we set random seed to the value of sensor data and make payoff from random number created by running pseudo random number generator with the configured random seed. We generate I × J (I ≥ 2, J ≥ 2) matrix game with these generated payoffs and attempt to obtain the Nash Equilibrium. Covert channel construction method is distinctly determined in accordance with whether or not to acquire the Nash Equilibrium.

Variable RCH Channel Assignment Scheme in HiperLAN/2 System (HiperLAN/2 시스템에서 가변적인 RCH 채널 할당방안)

  • Jang, soon-gun;Jang, jae-hwan;Lim, seog-ku
    • Proceedings of the Korea Contents Association Conference
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    • 2009.05a
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    • pp.83-87
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    • 2009
  • The MAC protocol of HiperLAN/2 is based on TDMA/TDD. Mobile terminal acquires a data transmission opportunity as successfulness in channel competition through RCH (Random CHannel) phase. Therefore, AP (Access Point) be able to dynamically assign optimum RCH at next frame according to the number of success and collision. In this paper, we suggest scheme that fluctuate RCH (Random CHannel) number as fixed value considering success and collision for improvement of performance in HiperLAN/2. To prove efficiency of proposed scheme, a lots of simulations are conducted and analyzed in view of throughput and access delay.

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Random Access Channel Allocation Scheme in Multihop Cellular Networks (멀티 홉 셀룰라 망에서의 랜덤 액세스 채널 할당 방안)

  • Cho, Sung-Hyun
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.32 no.4A
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    • pp.330-335
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    • 2007
  • This paper proposes a multichannel random access channel allocation scheme for multihop cellular networks to guarantee the stable throughput of a random access. The fundamental contribution is a mathematical formula for an optimal partition ratio of shared random access channels between a base station and a relay station. In addition, the proposed scheme controls the retransmission probability of random access packets under heavy load condition. Simulation results show that the proposed scheme can guarantee the required random access channel utilization and packet transmission delay even if the a random access packet arrival rate is higher than 0.1.

Distortion Analysis for two TDM Channel Expansion Methodsperiodic Sample Skipping and Sampling Frequency Reduction (주기적 Sample Skipping과 표준화주파수 축소에 의한 TDM 회선증가방식에서의 불특정 해석)

  • 안병성;이재균
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.12 no.3
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    • pp.30-36
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    • 1975
  • Distortions are analyzed and compared for two TDM channel expansion methods- periodic sample skipping and sampling frequency reduction. Signal is assumed to be stationary random signal with zero.mean. Channel noise and interference are not considered in the analysis. For speech signal, it is shown that the periodic sample skipping method could be a better choice under practical design constraints.

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An analysis of error probabilities for VSB signals in the presence of cochannel interference on the frequency selective fading channel (주파수 선택성 페이딩 채널에서 동일채널 간섭신호가 존재하는 경우 VSB 신호의 오율 분석)

  • 이종열;정영모;이상욱
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.21 no.9
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    • pp.2433-2443
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    • 1996
  • In this paper, a new technique is proposed for obtaining the error probabilities of the VSB(vestigial sideband modulation) signal in the presence of the cochannel interference and frequency-selective fading channel. For the receivers, a suboptimal matched filter receiver and the MLSE(maximum likelihood sequence estimation) receiver, which is known to be optimal on the fading channel, are considered. First, for the matched filter receiver, the distributions of the random variables, which determine the SER(symbol error rate) are obtained by decomposing the multi-path fading channel into Rayleigh distributed main path and Gaussian distributed remained path channels. the random variables mean the energy of the main path and subpath respecitively, and SER can be calculated from the distribution of them. Next, for the case of the MLSE receover, it is found that the random variables are expressed as a function of integrals. In order to obtain the distribution for the random variables, we expanded each element of integrals with the KL(Karhunen-Loeve) transformation. And it is derived that the distributions for the transformed random variables are given by a sum of chi-square distributions. Finally, we calculated the error rate derived formula on the two-ray fading channel, which is one of widely used models for the frequency-selective fading channel. From the numerical results, it is found that for the matched filer receiver, performance degradation is significant, while the performance degradation at the MLSE receiver is insignificant on the frequency-selective fading channel. However, in case of cochannel interference environment, the error rateis found to increase significantly both at the matched filter and at the MLSE receiver.

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Maximal overlap discrete wavelet transform-based power trace alignment algorithm against random delay countermeasure

  • Paramasivam, Saravanan;PL, Srividhyaa Alamelu;Sathyamoorthi, Prashanth
    • ETRI Journal
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    • v.44 no.3
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    • pp.512-523
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    • 2022
  • Random delay countermeasures introduce random delays into the execution flow to break the synchronization and increase the complexity of the side channel attack. A novel method for attacking devices with random delay countermeasures has been proposed by using a maximal overlap discrete wavelet transform (MODWT)-based power trace alignment algorithm. Firstly, the random delay in the power traces is sensitized using MODWT to the captured power traces. Secondly, it is detected using the proposed random delay detection algorithm. Thirdly, random delays are removed by circular shifting in the wavelet domain, and finally, the power analysis attack is successfully mounted in the wavelet domain. Experimental validation of the proposed method with the National Institute of Standards and Technology certified Advanced Encryption Standard-128 cryptographic algorithm and the SAKURA-G platform showed a 7.5× reduction in measurements to disclosure and a 3.14× improvement in maximum correlation value when compared with similar works in the literature.

The Gauss, Rayleigh and Nakagami Probability Density Distribution Based on the Decreased Exponential Probability Distribution (감쇄지수함수 확률분포에 의한 가우스, 레일레이, 나카가미 확률 밀도 분포)

  • Kim, Jeong-Su;Lee, Moon-Ho
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.17 no.6
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    • pp.59-68
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    • 2017
  • Random process plays a major role in wireless communication system to analytically derive the probability distribution function of the various statistical distribution. In this paper, we derive the decreasing function of the exponential distribution under the given condition which is expressed as wireless channel condition. The probability distribution function of Gaussian, Laplacian, Rayleigh and Nakagami distribution are also derived. Extensive simulation results of these statistical distributions are provided to prove that random process has a significant role in the wireless communications. In addition, the Rayleigh and Rician channels show specific examples of visible distance communication and invisible distance channel environment. This paper is motivated by that we assume a block fading channel model, where the channel is constant during a transmission block and changes independently between consecutive transmission block, can achieve a better performance in high SNR regime with i.i.d channel. This algorithm for realizing these transforms can be applied to the Kronecker MIMO channel.

Dynamic Random Channel Allocation Algorithm by Limiting the Number of Minimum RCH in HIPERLAN/2 (HIPERLAN/2에서 최소 RCH 수를 제한한 동적 랜덤채널 할당 기법)

  • Kang, Jae-Eun;Lee, Jong-Kyu
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.34 no.1A
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    • pp.58-64
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    • 2009
  • In this paper, we propose an dynamic random channel allocation scheme increasing probability of channel acquisition and reducing delay by limiting the number of minimum RCHs(Random CHannels) as an optimal factor $\beta$. The MAC protocol of HIPERLAN/2 is based on TDMA/TDD and MT(Mobile Terminal) can obtain chance of traffic transmission through channel competition in RCH period. And AP(Access Point) can dynamically schedule the number of RCHs based on the number of the collision in each RCH of the previous frame. Therefore, the proposed scheme increases a probability of channel acquisition and reduces delay by means of guaranteeing the number of minimum RCHs. With a practical Internet traffic, it is concluded that by the proposed scheme the delay reduction of the order of 19% and slightly better throughput are obtained compared to the conventional algorithm.

Processing Time and Traffic Capacity Analysis for RFID System Using LBT-Random Searching Scheme (LBT-Random Searching 방식을 채용한 RFID 시스템의 트래픽 처리 시간 및 용량 해석)

  • Hwang, In-Kwan;Lim, Yeon-Jun;Pyo, Cheol-Sig
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.30 no.9A
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    • pp.822-829
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    • 2005
  • In this paper, a processing time and trafnc capacity analysis algorithm for RFID system using LBT-Random Searching scheme is proposed. Service time, carrier sensing time, additional delay time required for contiguous frequency channel occupancy, and additional delay time required for the contiguous using the same frequency channel are considered and the processing delay and frequency channel capacity are analyzed for the steady state operation of the system. The simulation results showing maximum capacity of the system and explaining the accuracy of the algorithm are provided.