• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.7
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• pp.1313-1319
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• 2017

In this paper, we evaluate the performance of multi-hop transmissions in IEEE 802.15.6 ultra wide band (UWB) wireless body area network (WBAN). The packet structure in the physical layer, and encoding and decoding are considered for multi-hop transmissions in IEEE 802.15.6 UWB WBAN. We analyze the data success rate and energy efficiency of multi-hop transmissions with considering the length of data payload, transmission power, and distances between the nodes in IEEE 802.15.6 UWB WBAN. Through simulations, we evaluate the data success rate and energy efficiency of multi-hop transmissions with varying the length of data payload, transmission power, and distances between the nodes in IEEE 802.15.6 UWB WBAN. Finally, we can select an energy-efficient multi-hop transmission in IEEE 802.15.6 UWB WBAN depending on the length of data payload, transmission power, and distances between the nodes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.4B
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• pp.303-310
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• 2006

In sensor network environments, a sensor node has a limited power because of their resource constraints. Therefore it is important to efficiently use its power in sensor networks. Power consumption of sensor node is closely related to its amount of transmission data. So, we need to reduce the transmission data in order to minimize the power consumption. And sensor networks are inherently unreliable because radio transmission can fail, node can move, and so on. In this paper, we propose the reliable data aggregation protocol in order to these problems. This protocol performs the routing and the query inserting process at the same time to minimize the packet loss caused by network changes. And, this protocol removes the unnecessary routing caused by the periodic routing without query. Additionally, we suggest the countermeasure algorithm against the frequent errors in sensor networks.

• Journal of the Korean Society for Railway
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• v.12 no.6
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• pp.902-908
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• 2009

TETRA is the standard of Digital Trunked Radio System developed by the ETSI (European Telecommunications Standards Institute). It is currently adopted as Electric Power IT Wireless Backbone Network in Korea, and a national enterprise is going on for versatile utilization of TETRA. To use TETRA wireless network, TETRA modem is very necessary such that performance measurements are very crucial for each TETRA modem by various manufacturers. In this paper, PED (Protocol Evaluation Data) is suggested for PD performance measurement in D-TRS wireless network environment. The performance measurements for different data lengths and transmission intervals are done using TG (Traffic Generator) on Test Bed. The data size is increased by 10 bytes from 10-byte to 400-byte, and it is measured 1,000 times for each transmission interval of 0.5, 1.0, and 1.5 seconds. Based on the transmission time measured, average transmission speed and MER (Message Error Rate) are derived for TETRA Modem performance measurement. Two TMR880i's of EADS are used for TETRA modem, and SwMI (Switching and Management Infrastructure) of EADS is used for switching system in this paper.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.2
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• pp.40-49
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• 2015

PicoCast is a recently proposed short-range wireless communications technology that supports both low rate sensor/control data and high speed data such as voice and video traffic in the personal space, defined by the user-centric space of radius tens of meters, with one unified protocol. When the users are in the same area, personal spaces defined by each user may overlap. Since these PicoCast piconets may simultaneously operate, mutual interference is unavoidable. It is necessary to investigate the effect of mutual interference on data transmission and to conduct research on minimizing the interference among PicoCast devices. In this paper we analyze the effect of mutual interference between PicoCast piconets based on data throughput using OPNET network simulator. We have implemented the PicoCast protocol and measured the average throughput and packet loss rate.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.4
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• pp.855-860
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• 2017

One of the most important issues in Wireless Sensor Networks is to save energy of the sensor node. But transmission latency is also the problem to solve for some applications such as military surveillance, object tracking. In these applications sensor node needs to send lots of data in limited time when an even such as object appearance occurs. So a delay efficient data transmission method is required. In this paper we propose a MAC protocol adequate for those applications. This paper proposed a low delay data transmission mechanism for military surveillance in wireless sensor networks. In the MAC protocol, a receiver node sends another beacon frame to sender node after receiving data packet. Using this second beacon frame, fast hop-to-hop transmission can be performed. Results have shown that the proposed MAC control mechanism outperformed RI-MAC protocol in the terms of latency.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.48 no.6
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• pp.140-148
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• 2011

Multimedia streaming service is susceptible to loss and delay of data as it requires high bandwidth and real time processing. Therefore QoS cannot be guaranteed due to data loss caused by heavy network traffic. To deal with these problems, a study on algorithm that can provide high quality multimedia service by considering both network congestion and characteristics of multimedia data is required. In this paper, we propose APQM algorithm which probabilistically removes packet by the congestion level of the queue in wireless station. The comparison with other existing scheduling algorithms shows tht congestion in the network is reduced and multimedia service quality of the proposed algorithm is improved.

• The Transactions of the Korea Information Processing Society
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• v.7 no.2S
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• pp.721-732
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• 2000

Multimedia communication systems require not only high-performance computer hardwares and high-speed networks, but also a buffer management mechanism to process many data efficiently. Two buffer handling methods, Push and Pull, are commonly used. In the Push method, a server controls the flow of dat to a client, while in the Pull method, a client controls the flow of data from a server. Those buffering schemes can be applied to the data transfer between the packet receiving buffer, which receives media data from a network server, and media playout devices, which play the recived media data. However, the buffer management mechanism in client-sides mainly support either one of the Push or the Pull method. Consequently, they have some limitations to support various media playout devices. Futhermore, even though some of them support both methods, it is difficult to use since they can't provide a unified structure. To resolved these problems, in this paper, we propose an efficient and flexible Push/Pull buffer management mechanism at client-side. The proposed buffer management scheme supports both Push and Pull method to provide various media playout devices and to support buffering function to absorb network jitter. The proposed scheme can support the various media playback devices using a single buffer space which in consequence, saves memory space compared to the case that a client keeps tow types of buffers. Moreover, it facilitates the single buffer as a mechanism for the absorbing network jitter effectively and efficiently. The proposed scheme has been implemented in an existing multimedia communication system, so called ISSA (Integrated Streaming Service Architecture), and it shows a good performance result compared to the conventional buffering methods in multimedia communication environments.

• Journal of Communications and Networks
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• v.14 no.6
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• pp.640-652
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• 2012

Many studies have investigated the smart grid architecture and communication models in the past few years. However, the communication model and architecture for a smart grid still remain unclear. Today's electric power distribution is very complex and maladapted because of the lack of efficient and cost-effective energy generation, distribution, and consumption management systems. A wireless smart grid communication system can play an important role in achieving these goals. In this paper, we describe a smart grid communication architecture in which we merge customers and distributors into a single domain. In the proposed architecture, all the home area networks, neighborhood area networks, and local electrical equipment form a local wireless mesh network (LWMN). Each device or meter can act as a source, router, or relay. The data generated in any node (device/meter) reaches the data collector via other nodes. The data collector transmits this data via the access point of a wide area network (WAN). Finally, data is transferred to the service provider or to the control center of the smart grid. We propose a wireless cooperative communication model for the LWMN.We deploy a limited number of smart relays to improve the performance of the network. A novel relay selection mechanism is also proposed to reduce the relay selection overhead. Simulation results show that our cooperative smart grid (coopSG) communication model improves the end-to-end packet delivery latency, throughput, and energy efficiency over both the Wang et al. and Niyato et al. models.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.12
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• pp.63-72
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• 2007

This paper addresses the system development that can transfer data and TDM signals simultaneously by adding TDM pseudowires functions to E-PON system. E-PON technology is one of many technologies which can realize FTTH, has raised as next generation access network solution having both low-cost Ethernet technology and optical infrastructure. TDM pseudowires service is the new voice/data conversion technology which can transfer the existing TDM circuit switched voice and data over packet switching network. In this paper, this system can provide both data and TDM service without deteriorating QoS by adding TDM pseudowires service module to E-PON, and then implementing QoS control function. Therefore, the competitive system which can transfer both data and TDM signal, can be installed.

• Journal of KIISE:Computing Practices and Letters
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• v.8 no.3
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• pp.328-335
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• 2002

When we want to transfer video streaming data through computer networks, we will have to be allocated a larger bandwidth compared to a general application. In general, it causes a serious network overload inevitably due to the limited bandwidth. In this paper, in order to resolve the problem, we haute taken a method for transmitting video streaming data using RTP and RTCP. With RR(Receiver Report) packet in RTCP we will test it to check whether the traffic in a network has occurred or not. If it happened, we haute tried to reduce the overall network traffic by dynamically changing the quantization factor of the Motion JPEG that is one of the encoding styles in JMF. When the ratio of the average of transmission for each session to the average of overall transmission is greater than 7%, we should adjust the amount of data to be transmitted for each session to reach the session mean values. The experimental results show that the proposed method taken here reduces the overload effectively and therefore improves the efficiency for transmitting video streaming data.