• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.12
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• pp.1359-1364
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• 2014

IEEE 802.11p is a representative PHY/MAC layer standard in vehicular communications. The performance of IEEE 802.11p based communication systems has been measured in various criterions such as link setup time, error rate, and throughput for the case of one-to-one. In this paper, we measure the performance of IEEE 802.11p based communication systems in large capacity transmission. The performance of large capacity transmission is measured by considering the maximum 32 simultaneous transmission including one-to-one transmission. We consider two transmission schemes, i.e., broadcasting and unicasting, and the performance is represented as the receiving rate and throughput.

• Journal of Communications and Networks
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• v.15 no.5
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• pp.457-463
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• 2013

In recent days, cooperative diversity and communication security become important research issues for wireless communications. In this paper, to achieve low probability of interception (LPI) and high throughput in the cooperative single-carrier frequency division multiple access (SC-FDMA) system, a new physical layer transmission scheme is proposed, where a new encryption algorithm is applied and adaptive modulation is further considered based on channel state information (CSI). By doing so, neither relay node nor eavesdropper can intercept the information signals transmitted from user terminal (UT). Simulation results show above new physical layer transmission scheme brings in high transmission safety and secrecy rate. Furthermore, by applying adaptive modulation and coding (AMC) technique according to CSI, transmission throughput can be increased significantly. Additionally, low peak-to-average power ratio (PAPR) characteristic can still be remained due to the uniform distribution of random coefficients used for encryption algorithm.

• Journal of Advanced Navigation Technology
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• v.9 no.2
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• pp.156-163
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• 2005

In this paper, we analyzed the performance of VDL mode 3 system model whose specification is defined by ICAO(International Civil Aviation Organization). For performance evaluation, we obtained BER(Bit Error Rate), transmission delay time, burst retransmission rate and throughput. From the analysis result, we could explicitly define relationships among BER, transmission delay time, throughput and burst restransmission rate. In addition, it became known that V/D retransmission rate and throughput are closely related in down link channel.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1474-1479
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• 2003

This paper proposes a transmission interval which includes collisions and retransmissions in the IEEE 802.11 DCF. The transmission probability is used for the calculation of collisions and retransmissions in the DCF. Since the noises are considered to analyze the transmission interval, retransmissions by the noises are included in the proposed transmission interval. The proposed transmission interval takes account of the retransmissions by packet errors, and makes it possible to analyze the maximum throughput of the DCF.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.5
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• pp.21-26
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• 2012

Intra-session network coding has been proposed to improve throughput by simplifying scheduling of multi-hop wireless network and efficiency of packet transmission. Multi-rate transmission has been used in multihop wireless networks. An opportunistic routing with multirate shows throughput improvement compared with single rate. In this paper, we propose a method of throughput improvement in multi-hop wireless network by using multi-rate and intra-session network coding. We suggest a method to select an local optimal transmission rate at each node. The maximum throughput is evaluated by using linear programming (LP). To solve the LP, we use MATLAB and lp_solve IDE program. The performance evaluation results show that end-to-end throughput is improved by using multirate and intra-session network coding can achieve better throughput than opportunistic routing.

• Journal of Communications and Networks
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• v.11 no.5
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• pp.464-472
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• 2009

In this paper, we propose a packet scheduling algorithm for cellular relay networks by considering relay selection, variation of channel quality, and packet delay. In the networks, mobile users are equipped with not only cellular but also user relaying radio interfaces, where base station exploits adaptive high speed downlink channel. Our proposed algorithm selects a user with good cellular channel condition as a relay station for other users with bad cellular channel condition but can get access to relay link with good quality. This can achieve flexible packet scheduling by adjusting transmission rates of cellular link. Packets are scheduled for transmission depending on scheduling indexes which are calculated based on user's achieved transmission rate, packet utility, and proportional fairness of their throughput. The performance results obtained by using computer simulation show that the proposed scheduling algorithm is able to achieve high network capacity, low packet loss, and good fairness in terms of received throughput of mobile users.

• The KIPS Transactions:PartC
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• v.13C no.2 s.105
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• pp.235-240
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• 2006

Stream Control Transmission Protocol (SCTP) provides the multi-homing feature, which allows each SCTP endpoint to use two or more IP addresses for data transmission. In this paper, the SCTP multi-homing feature is experimented and analyzed in terms of throughput over Linux platforms based on the NISTNET network emulator. We perform the experimental analysis of SCTP throughputs by SCTP multi-homing for the various network conditions: different packet loss rates, network bandwidths, and transmission delays. From the experimental results, it is shown that the SCTP multi-homing gives much better throughout gun over the SCTP single-homing case in the networks with a high packet loss rate. In the meantime, the other factors including network bandwidth and transmission delay do not seem to give a significant impact on the performance of the SCTP multi-homing.

• Journal of Communications and Networks
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• v.5 no.1
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• pp.25-32
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• 2003

4G mobile communication system requires the throughput of 10-100Mbps. Adaptive modulated OFDM system is promising technique for increasing the throughput. In the pilot symbol assisted high-speed packet transmission system, the data symbol duration is generally considered to be small compared to the coherence time. However, OFDM symbol duration is longer than the symbol duration of a single carrier system, so that the packet duration of the pilot symbol assisted high speed packet transmission system is long. In this case, the change of channel conditions is too fast to be accurately estimated by channel estimator at the receiver in high Doppler frequency, so that many errors occur during demodulation, especially with the data symbols at the end of each packet. In this paper, we consider the BER at various instantaneous $E_b/N_o$ that includes the demodulation errors in high Doppler frequency. When the coherence time is ten times longer than the duration of a single packet, the channel can be closely approximated as an AWGN channel. Otherwise, the approximation breaks down and the above-mentioned errors that occur during demodulation must be taken into consideration. In this paper, we propose the pilot symbol assisted high speed packet transmission system based on adaptive OFDM using a novel lookup table to consider the demodulated errors and evaluate the throughput performance.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1982.10a
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• pp.37-39
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• 1982

In this paper, we deal with theoretical tools to improve the throughput efficiency of the conventional Go-Back-N ARQ system by performing block retransmission efficiently under high error rate, and two variations of the system is proposed.

• Journal of Communications and Networks
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• v.16 no.3
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• pp.293-300
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• 2014

As energy harvesting communication systems emerge, there is a need for transmission schemes that dynamically adapt to the energy harvesting process. In this paper, after exhibiting a finite-horizon online throughput-maximizing scheduling problem formulation and the structure of its optimal solution within a dynamic programming formulation, a low complexity online scheduling policy is proposed. The policy exploits the existence of thresholds for choosing rate and power levels as a function of stored energy, harvest state and time until the end of the horizon. The policy, which is based on computing an expected threshold, performs close to optimal on a wide range of example energy harvest patterns. Moreover, it achieves higher throughput values for a given delay, than throughput-optimal online policies developed based on infinite-horizon formulations in recent literature. The solution is extended to include ergodic time-varying (fading) channels, and a corresponding low complexity policy is proposed and evaluated for this case as well.