• KIPS Transactions on Computer and Communication Systems
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• v.10 no.2
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• pp.29-38
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• 2021

The Internet including mobile networks is developing to overcoming the limitation of physical distance and providing or acquiring information from remote locations. However, the systems that use video as primary information require higher bandwidth for recognizing the situation in remote places more accurately through high-quality video as well as lower latency for faster interaction between devices and users. The emergence of the 5th generation mobile network provides features such as high bandwidth and precise location recognition that were not experienced in previous-generation technologies. In addition, the Mobile Edge Computing that minimizes network latency in the mobile network requires a change in the traditional system architecture that was composed of the existing smart device and high availability server system. However, even with 5G and MEC, since there is a limit to overcome the mobile network state fluctuations only by enhancing the network infrastructure, this study proposes a high-definition video streaming system in ultra-low latency based on the SRT protocol that provides Forward Error Correction and Fast Retransmission. The proposed system shows how to deploy software components that are developed in consideration of the nature of 5G and MEC to achieve sub-1 second latency for 4K real-time video streaming. In the last of this paper, we analyze the most significant factor in the entire video transmission process to achieve the lowest possible latency.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.5
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• pp.105-111
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• 2008

Mobility support for mobile networks will be important to minimize the packet overhead, to optimize routing, to reduce handoff latency, and to reduce the volume of handoff signals. Mobile IPv6 (MIPv6) and Hierarchical MIPv6 (HMIPv6) are one of mobility management protocols (MMPs) that provides network layer mobility over all access technologies. However, the communication quality of these candidates is severely degraded during handoffs. As another way to improve the handoff performance of a mobile network by conventional MMPs such as MIPv6 and HMIPv6, we propose a Low Latency Handoff Scheme (LLHS) combining Fast MIPv6 (FMIPv6) with HMIPv6 extension with buffering function, in which Mobility Anchor Points (MAPs) buffer packets destined to the Mobile Routers (MRs) or MNs within a mobile network during handoffs. The simulation results show that the proposed scheme reduces transmission delay and packet loss in UDP communication.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.12C
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• pp.1207-1214
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• 2002

A scheduling scheme for high speed networks requires a low time complexity to schedule packets in a packet transmission time. High speed networks support a number of connections, different rates for each connection and variable packet length. Conventional round robin algorithms have a time complexity of O(1), but their short time fairness, latency and burstiness depend on the quantum of a connection due to serving several packets for a backlogged connection once a round. To improve these properties, we propose in this paper an efficient packet scheduling scheme which is based on the credits of a connection and has a time complexity of O(1). We also analyzed its performance in terms of short time fairness, latency and burstiness. The analysis results show that the proposed scheme can improve the performance compared with traditional round robin schemes. The proposed scheme can be easily utilized in high speed packet networks.

• PNF and Movement
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• v.19 no.2
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• pp.195-203
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• 2021

Purpose: Neurodynamic tests are used to examine neural tissue in patients with neuro-musculoskeletal disorders, although this has not yet been established in the intensity of nerve tension application. This study aimed to investigate the acute effects of neural stretching intensity on nerve excitability using the latency and amplitude of nerve conduction velocity test (NCV) analysis. Methods: Thirty young, healthy male and female subjects (mean age = 21.30 years) voluntarily participated in this study. Nerve excitability was assessed using the median sensory NCV test. The latency and amplitude of the NCV test were measured under four different conditions: reference phase (supra-maximal stimulus, without neural stretching), baseline phase (2/3 of the supra-maximal stimulus, without neural stretching), weak stretch phase (2/3 of the supra-maximal stimulus, with weak neural stretching), and strong stretch phase (2/3 of the supra-maximal stimulus, with strong neural stretching). Results: The NCV latency was significantly delayed after one minute of neural stretching at the baseline, weak phase, and strong phase in comparison with the reference phase. The NCV latency was significantly delayed by increasing the strength of neural stretching. Furthermore, the NCV amplitude was significantly increased at the weak and strong phases, which were under neural stretching, in comparison with the baseline phase. The NCV amplitude was significantly increased by increasing the strength of the neural stretching. Conclusion: Transient neural stretching as a neurodynamic test can increase the sensitivity of the nerve without negatively affecting the nervous system. However, based on the results of this study, strong neural stretching in the neurodynamic test may delay the transmission of nerve impulses and hypersensitivity.

• Journal of KIISE:Information Networking
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• v.31 no.5
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• pp.532-543
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• 2004

Mobile Ad hoc NETworks (MANET) consist of mobile nodes which are usually powered by battery Approaches for minimizing power consumption have been proposed for all network layers and devices. IEEE 802.11 DCF (Distributed Coordination Function), a well-known medium access control protocol for MANETS, also defines a power save mode operation. The nodes in power save mode periodically repeat the awake state and the doze state in synchronized fashion. When all nodes are in the awake state, the exchange the announcements for the subsequent message transmission with neighbors. The nodes that send or receive the announcements stay awake for data transmission, and others go into the dole state. The previous works for enhancing the power save mode operation have focused on shortening the duration of the awake state. We observed that the longer sleeping period results in seriously long delivery latency and the consequent unnecessary power consumption as well, because the packets can move forward only one hop for a fixed interval. In this paper, we propose an improved protocol for the power save mode of IEEE 802.11 DCF, which allows the flooding packets to be forwarded several hops in a transmission period. Our approach does not reduce the duration of compulsory awake period, but maximizes its utilization. Each node propagates the announcements for next flooding to nodes of several hops away, thus the packets can travel multiple hops during one interval. Simulation results of comparison between our scheme and the standard show a reduction in flooding delay maximum 80%, and the unicasting latency with accompanying flooding flows near 50%, with slight increase of energy consumption.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.4
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• pp.581-587
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• 2021

Real-time video streaming scheme for multimedia content delivery and remote conference services is one of technologies that are significantly sensitive to data transmission delay. Recently, because of COVID-19, real-time video streaming contents for the services are significantly increased such as personal broadcasting and remote school class. In order to support the services, there is a growing emphasis on low transmission delay and secure content delivery, respectively. Therefore, our research proposed a packet aggregation algorithm to reduce the transmission delay of selectively encrypted video transmission for real-time video streaming services. Through the application of the proposed algorithm, the selectively encrypted video framework can control the amount of MPEG-2 TS packets for low latency transmission with a consideration of packet priorities. Evaluation results on testbed show that the application of the proposed algorithm to the video framework can reduce approximately 11% of the transmission delay for high and low resolution video.

• Journal of KIISE:Information Networking
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• v.35 no.1
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• pp.56-66
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• 2008

Contention-based forwarding in wireless ad-hoc networks reduces transmission failure rate by selecting one receiver with good channel among multiple receivers. However, contention-based forwarding may increase transmission latency due to the collision problem caused by the simultaneous transmission among multiple receivers. In this paper, we present an analytic model that reflects the delay and collision rate of contention-based forwarding in lossy wireless links. Through the analytic model, we calculate the expected delay and progress in one-hop transmission under given wireless link model and delay model. Based on the analytic results, we observe that delay model should be adapted to wireless link model for optimal performance in contention-based forwarding.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.8
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• pp.3399-3419
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• 2020

In the Vehicular Ad-hoc Network (VANET), the data transmission of time-sensitive applications requires low latency, such as accident warnings, driving guidance, etc. However, frequent changes of topology in VANET will result in data transmission failures. In order to improve the efficiency of VANETs data transmission and increase the timeliness of data, this paper proposes a relay scheme based on Recurrent Neural Network (RNN) trajectory prediction, which can be used to select the optimal relay vehicle to transmit data. The proposed scheme learns vehicle trajectory in a distributed manner and calculates the predicted trajectory, and then the optimal vehicle can be selected to complete the data transmission, which ensures the timeliness of the data. Finally, we carry out a set of simulations to demonstrate the performance of the algorithm. Simulation results show that the proposed scheme enhances the timeliness of the data and the accuracy of the predicted driving trajectory.

• Smart Media Journal
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• v.4 no.1
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• pp.25-32
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• 2015

Powering wireless sensors with energy harvested from the environment is coming of age due to the increasing power densities of both storage and harvesting devices and the electronics performing energy efficient energy conversion. In order to maximize the functionality of the wireless sensor network, minimize missing packets, minimize latency and prevent the waste of energy, problems like congestion and inefficient energy usage must be addressed. Many sleep-awake protocols and efficient message priority techniques have been developed to properly manage the energy of the nodes and to minimize congestion. For a WSN that is operating in a strictly energy constrained environment, an energy-efficient transmission strategy is necessary. In this paper, we present a novel transmission priority decision scheme for a heterogeneous body sensor network composed of normal nodes and an energy harvesting node that acts as a cluster head. The energy harvesting node's decision whether or not to clear a normal node for sending is based on a set of metrics which includes the energy harvesting node's remaining energy, the total harvested energy, the type of message in a normal node's queue and finally, the implementation context of the wireless sensor network.

• Journal of Broadcast Engineering
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• v.21 no.6
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• pp.986-994
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• 2016

In this paper, a digital closed-circuit television (CCTV) transmission system called the extended reach high definition serial digital interface (ER-SDI) is proposed to increase the transmission distance while preserving the quality using digital modulation. The current standard of HD-serial digital interface (HD-SDI) has the maximum transmission distance of 200 m. Recently, one system which transforms the digital signal to an analog signal and modulates color signal to extend the transmission distance is proposed. Another system which uses IP network is also proposed. However, the former system has a disadvantage of video quality and the latter system has high latency. The proposed ER-SDI is designed to extend the transmission distance of 518 m by adopting multilevel constellations and a channel code for a data rate of 1.485 Gbps. The maximum transmission distance of the proposed system is calculated using the specification of HD-SDI and the experiment result under coaxial cable environment.