• Journal of KIISE:Computing Practices and Letters
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• v.10 no.6
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• pp.460-471
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• 2004

Since the RTP is suitable for real-time data transmission in multimedia services like VoD, AoD, and VoIP, it has been adopted as a real-time transport protocol by RTSP, H.323, and SIP. Even though the RTP protocol stack for embedded systems has been in great need for efficient support of multimedia services, such a stack has not been developed yet. In this paper, we explain embeddedRTP which supports the RTP protocol stack at the kernel level so that it is suitable for embedded systems. Since embeddedRTP is designed to reside in the UBP module, existing applications which rely ell TCP/IP services can proceed the same as before, while applications which rely on the RTP protocol stack can request HTP services through embeddedRTp API. EmbeddedRTP stores transmitted RTP packets into per session packet buffer, using the packet's port number and multimedia session information. Communications between applications and embeddedRTP is performed through system calls and signal mechanisms. Additionally, embeddedRTP API makes it possible to develop applications more conveniently. Our performance test shows that packet-processing speed of embeddedRTP is about 7.5 times faster than that oi VCL RTP for multimedia streaming services on PDA in spite that its object code size is reduced about by 58% with respect to UCL RTP's.

• The Journal of the Convergence on Culture Technology
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• v.6 no.1
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• pp.495-500
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• 2020

VANET (Vehicular Ad Hoc Network), an example of an ad hoc vehicular networks, becomes one of the popular research areas together with the self-driving cars and the connected cars. In terms of the VANET implementation, the traditional TCP/IP protocol stack could be applied to VANET. Recently, CCN (Content Centric Networking) shows better possibility to apply to VANET, called VCCN (VANET over CCN). CCN maintains several data tables including CS (Content Store) which keeps track of the currently requested content segments. When the CS becomes full and new content should be stored in CS, a replacement algorithm is needed. This paper compares and contrasts four replacement algorithms. In addition, it analyzes the transmission characteristics in diverse network conditions. According to the simulation results, LRU replacement algorithm shows better performances than the remaining three algorithms. In addition, even the size of CS is small, the network maintains a reasonable transmission performance. As the CS size becomes larger, the transmission rate increases proportionally. The transmission performance decreases when the network is crowded as well as the number of transmission hops becomes large.

• The Journal of the Convergence on Culture Technology
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• v.5 no.1
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• pp.429-434
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• 2019

There are several high technologies applied to the driving cars such as self-driving car and connected car for safe and convenient driving. VANET provides useful information such as route selection and gas price by communicating nearby cars and RSUs. VANET prefers CCN rather than traditional TCP/IP stack because CCN offers inherent multicast communication for sharing traffic information as well as traditional unicast. When all participating node rebroadcasts the Interest packets in a Vehicular CCN, the network may suffer from Broadcast Storm Problem. In order to mitigate the effect of the problem and to improve the Data packet transmission, not all but some selected nodes have to rebroadcast the packet. This paper simulates car movements using SUMO and evaluates data transmission performance using ns-3. According to the simulation results, when some selected nodes rebroadcast the Interest packets, the transmission performance improves 10% to 25% depending on the number of requesting nodes.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.1
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• pp.125-132
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• 2010

IEC61162-3 known as NMEA2000 protocol is approved as a standard network of SOLAS ship by ISO and used for the instrument network which exchanges data in real-time. For easy the development of ship network equipments, this study is focused on the development of SoC which can convert to NMEA2000 protocol from various kind of protocols such as TCP/IP, NMEA0183, RS422 and others using FPGA and u-Blaze. In this paper, we composed NMEA2000 protocol stack on FPGA and verified NMEA2000 network communication of FPGA system by connecting with commercialized devices through PC Hyper-terminal and network monitoring program.

• Proceedings of the KIEE Conference
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• 1998.07g
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• pp.2373-2376
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• 1998

This paper describes the development of the SCADA(Supervisory Control and Data Acquisition) system which can be controlled via the Internet. In this paper, the SCADA system is composed of a number of microprocessor-based RTU(Remote Terminal Unit)s, a MMI(Man Machine Interface) host, a SCADA server, and SCADA clients. There are two protocols used in the system. Each RTU and the MMI host are connected by a RS-485 line and CSMA/CD(Carrier Sense Multiple Access / Collision Detection) protocol is used to communicate with each other. TCP/IP(Transmission Control Protocol/Internet Protocol) is used among the MMI host, the SCADA server, and SCADA clients. The equipments installed in the field are controlled by a number of RTUs. The function of the MMI host is to acquire real-time data from RTUs and control them. The SCADA server supports data transfer between the networked MMI host and the SCADA client on the web-server through TCP/lP. Data transfer is possible regardless of the type of network only if there are TCP/lP Winsock-compatible stack driver. The SCADA client is implemented as the shape of web-page by means of JAVA language. Therefore, it runs on a web-browser such as Netscape and Explorer, and allows a number of users to access this SCADA system.

• 한국HCI학회:학술대회논문집
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• 2006.02a
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• pp.406-412
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• 2006

정보통신 기술의 발달로 근래에는 인터넷 방송 서비스가 활성화되었으며 누구든 자유롭게 방송을 제작하거나 청취할 수 있다. 이러한 인터넷 방송을 이용하기 위해서는 PC 를 이용하는 방법이 일반적이지만 오디오 서비스만을 이용할 경우 불편하다. 본 논문에서는 낮은 사양의 시스템에서 인터넷 방송을 청취하기 위한 하드웨어와 소프트웨어 설계 기법 그리고 효율적인 버퍼링 방법을 제안하였다. 제안된 시스템은 8 비트 마이크로 컨트롤러, 32KB 의 메모리, Hardwired TCP/IP Stack 그리고 Hardwired MP3 디코더를 이용하여 설계하였으며 각 작업간의 스케쥴링을 위하여 타이머 인터럽트를 이용하였다. 16KB의 메모리로 몇 가지 버퍼링 기법을 제안했다. 폴링 방식은 가장 보편적인 방법으로 데이터를 전송받는 작업과 음악을 재생하는 작업이 순차적으로 이루어진다. 이 방법은 데이터 전송과 음악 재생을 동시에 할 수 없기 때문에 타이머 인터럽트를 이용한 버퍼링 모델이 사용된다. 두 번째로 메모리를 두개의 블록으로 나누어 한 블록에는 데이터를 저장하고 다른 한 블록에는 데이터를 내보내는 '더블 버퍼링'을 제안했다. 세 번째는 메모리 블록을 여러 단계로 나눈'n-Queue 버퍼링' 기법을 제안했다. 마지막으로 네트워크 상황에 따라서 블록의 개수를 유동적으로 조절하는 '가변 길이 n-Queue 버퍼링' 기법을 제안했다. 이 방법은 네트워크 상황에 따라 메모리의 크기를 유동적으로 할당하기 때문에 메모리 사용률이 높아지는 장점이 있다. 본 논문에서 제안하는 시스템은 운영체제를 사용하지 않았기 때문에 TV 나 오디오 등 다른 시스템에 이식이 용이하므로 다양한 기기에 적용이 가능하다.

• ETRI Journal
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• v.35 no.1
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• pp.7-17
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• 2013

The ongoing proliferation of new services, applications, and contents is leading the Internet to an architectural crisis owing to its inability to provide efficient solutions to new requirements. Clean-slate architectures for the future Internet offer a new approach to tackle current and future challenges. This proposal introduces a novel clean-slate architecture in which the TCP/IP protocol stack is decoupled in basic functionalities, that is, atomic services (ASs). A negotiation protocol, which enables context-aware service discovery for providing adapted communications, is also specified. Then, we present how ASs can be discovered and composed according to requesters' requirements. In addition, a media service provisioning use case shows the benefits of our framework. Finally, a proof-of-concept implementation of the framework is described and analyzed. This paper describes the first clean-slate architecture aligned with the work done within the ISO/IEC Future Network working group.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.05a
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• pp.927-930
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• 2007

As RFID systems are applied to various fields and applications such as supply chain management, asset management, location based applications etc. the requirements becomes diverse. For example, Much higher performance, TCP/IP protocol stack are required in some applications. However, low end processors based systems such as 8051 processor can not meet such requirements due to their low processing capacity and limited size of memory. In this paper a UHF band RFID system which meets the ISO 18000-6 TYPE C specification with ARM920T-based processor is implemented and tested.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.12
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• pp.1792-1798
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• 2017

Event Data Recorder(Car Black-Box) with WiFi dongle have been released, and the platform of the majority is the Linux platform. This is because the platform development is possible in little investment cost by reducing the source licensing costs by taking advantage of the open source. But utilizing Linux platform has the limitations of boot-up time and consuming processing power due to the limitation of battery capacity, to be cost-competitive to minimize the use of memory. In this paper, the real-time operating system(RTOS) is utilized to optimize these portions. MP4 encoder and Muxer are developed to be about ten seconds boot up and minimized memory. It has the advantages of operating at lower power consumption than the Linux utilizing WiFi dongle. Utilizing a WiFi dongle is to provide a progressive download feature on smart phones to lower product prices. But RTOS has the weakness in WiFi. Porting TCP /IP, Web and DHCP server and combination with the USB OTG Host interface by implementing the protocol stack are developed for WiFi. And also SPI NOR flash memory is utilized for faster boot time and cost reductions, low processing power to be consume. As the results, the developed proved the 10 seconds booting time, 24 frame rate/sec. and 10% lower power consumption.

• The KIPS Transactions:PartC
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• v.14C no.4
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• pp.371-382
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• 2007

In this paper, we propose a real-time sensor node platform that efficiently manages periodic and aperiodic tasks. Since existing sensor node platforms available in literature focus on minimizing the usage of memory and power consumptions, they are not capable of supporting the management of tasks that need their real-time execution and fast average response time. We first analyze how to structure periodic or aperiodic task decomposition in the TinyOS-based sensor node platform as regard to guaranteeing the deadlines of ail the periodic tasks and aiming to providing aperiodic tasks with average good response time. Then we present the application and efficiency of the proposed real-time sensor node platform in the sensor node equipped with a low-power 8-bit microcontroller, an IEEE802.15.4 compliant 2.4GHz RF transceiver, and several sensors. Extensive experiments show that our sensor node platform yields efficient performance in terms of three significant, objective goals: deadline miss ratio of periodic tasks, average response time of aperiodic tasks, and processor utilization of periodic and aperiodic tasks.