• Journal of KIISE:Information Networking
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• v.29 no.5
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• pp.501-509
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• 2002

When using TCP over a mobile network, TCP responds to a handoff by invoking a congestion control algorithm, thereby resulting in a degraded end-to-end performance in a mobile network. In this paper, two schemes are proposed, TCP-MD and TCP-R. TCP-MD can detect the movement of s mobile host early on, whereas TCP-R can force the source to freeze data transmission during registration. The proposed schemes maintain end-to-end TCP semantics, making it possible to fully interoperate with the existing infrastructure. Only a small change is required in the mobile host, plus the implementation is simple because some Mobile IP messages are used to notify the handoff, eliminating the need for any additional messages. Simulations confirmed that the proposed schemes give an excellent performance under various environments.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.4
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• pp.885-892
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• 2013

In the model Utilizing the TCP / IP socket communication to transmit and receive data, if the size of data is small and if data-transmission aren't frequently requested, the importance of communication speed between a server and a client isn't emphasized. But nowadays, it has emerged for large amounts of data transfer requests and frequent data transfer request. This paper propose the TCP/IP communication model that can be improved the data transfer rate in multi-core environment by changing the receiving structure of the client to receive large amounts of data and the transmission structure of the server to send large amounts of data.

• Journal of KIISE:Computing Practices and Letters
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• v.10 no.3
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• pp.231-242
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• 2004

Remote control and monitoring of information appliances require RTOS and TCP/IP network module to communicate each other. Traditional TCP/IP protocol stacks, however, require relatively large resources to be useful in small 8 or 16-bit systems both in terms of code size and memory usage. It motivates design and implementation of micro TCP/IP that is lightweight for embedded systems. Micro embedded web server is also required to control and monitor information appliances through the Web. In this paper, we design and implement micro TCP/IP and Web server for information appliances. For this goal, we investigate requirements for the interoperability of embedded systems with the Internet and the Web-based control of embedded systems. Next, we compare our micro TCP/IP protocol stack with that of RTIP and QPlus in terms of object code size and performance. The size of micro TCP/IP protocol stack can be reduced by 3/2 and 1/4, respectively, comparing with that of RTIP and QPlus. We also show that the performance of our micro TCP/IP is similar to that of RTIP and QPlus since it handles 2.9Mbps when delayed ACK is not adapted.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.370-372
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• 2005

In this paper, the microcontroller TCP/IP NIE(Network Interface Equipment) which is exclusive of an operating system is implemented and the applied example to a step motor motion controller is then explained. The microcontroller TCP/IP NIE supplies a DHCP(Dynamic Host Configuration Protocol) as well as basic TCP/IP network protocols. So, the automatic setting up of the Dynamic If(Internet Protocol) is possible. To implement a control of a system with an internet, the microcontroller TCP/IP NIE is applied to a step motor motion controller and a step motor is then controlled with a Microsoft Windows-based Telnet application program.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.5
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• pp.434-437
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• 2002

A small size and light-weight DSP board is newly designed for a real time multi-distributed control system that overcomes constraints on time and space. There are a variety of protocols for a real-time distributed control system. In this research, we selected CAN for the multi distributed control, which was developed by the BOSCH in the early 1980's. If CAN and Internet are connected together, the system attains the characteristics of a distributed control system and a remote control system simultaneously. To build such a system. The TCP/IP-CAN Gateway which converts a CAN protocol to TCP/IP protocol and vice verse, was designed. Moreover, the system is required to be small and light-weighted for the high mobility and cost effectiveness. The equipment in remote place has a TCP/IP-CAN Gateway on itself to be able to communicate with another systems. The received commands in the remote site are converted from TCP/IP protocol to CAN protocol by the TCP/IP-CAN Gateway in real time. A simulation system consists of a TCP/IP-CAN Gateway in remote place and a command PC to be connected to Ethernet.

• International Journal of Internet, Broadcasting and Communication
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• v.16 no.1
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• pp.29-35
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• 2024

TCP is considered as one of the major candidate transport protocols even for constrained IoT networks..In our previous work, we investigated the congestion control mechanism of the uIP TCP. Since the uIP TCP sets the window size to one segment by default, managing the retransmission timer is the primary approach to congestion control. However, the original uIP TCP sets the retransmission timer based on the fixed RTO, it performs poorly when a radio duty cycling mechanism is enabled and the hidden terminal problem is severe. In our previous work, we proposed a TCP retransmission timer adjustment scheme for uIP TCP which adopts the notion of weak RTT estimation of CoCoA, exponential backoffs with variable limits, and dithering. Although our previous work showed that the proposed retransmission timer adjustment scheme can improve performance, we observe that the scheme often causes a node to set the retransmission timer for an excessively too long time period. In this work, we show that slightly modifying the dithering mechanism of the previous scheme is effective for improving TCP fairness.

• Journal of the Institute of Convergence Signal Processing
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• v.13 no.4
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• pp.211-219
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• 2012

In this paper, we described the software development for verifying the integrity of output data of TCP/IP for VLBI Correlation Subsystem (VCS) correlation block and proposed the performance improvement method in order to prevent the data loss of correlation output. The VCS correlation results are saved at the Data Archive system through TCP/IP packet transmission. In this paper, the integrity verification software is developed so as to confirm the integrity of correlation result saved at the data archive system using TCP/IP packet information of VCS. The 3-step integrity verification process is proposed by using the developed software, its effectiveness was confirmed in consequence of correlation experiments. In addition, TCP/IP packet transmission must be completed within minimum integration period. However, there is not only TCP/IP packet loss occurred but also the problem of correlation result integrity affected in account of a large quantity of packets and data during short integration time. In this paper, the reason of TCP/IP packet loss is analyzed and the modified methods for FPGA(Field Programmable Gate Array) of VCS are proposed, the integrity problem of correlation results will be solved.

• The Transactions of the Korea Information Processing Society
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• v.7 no.8S
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• pp.2679-2687
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• 2000

위성 ATM 망에서 TCP/IP 기반의 응용 서비스를 제공하기 위해서는 위성의 긴 전송지연과 이성 채널의 버스트 오류 특성에 따른 정확한 전송 성능의 영향과 분석이 요구되며, 아울러 성능 목표치가 제시되어야 한다. 본 논문은 2Mbps급 KOREASAT위성을 이용한 위성망과 지상망이 상호 연동된 실제 위성/지상 ATM LANE(LAN Emulation)을 구현하고, 위성 채널의 Eb/No와 TCP 소켓 버퍼 크기, 그리고 전송 메시지 크기를 바꾸어 가면서 그때의 TCP/IP 트래픽과 FTP의 전송성능을 비교 분석하였다. 아울러 IPoA(IP over ATM)기반의 영상회의 서비스에 대한 전송 품질 및 메시지 전달 특성 등을 분석하였다. 연구결과 TCP 소켓 버퍼 크기가 증가할 때 TCP의 전체 성능이 증가함을 알 수 있으나 제한된 최대 윈도우 크기 64kbytes와 위성채널의 오류 특성으로 인해 실제 최대 전송속도는 이론상의 목표치를 달성하지 못함을 보여 주었다. 또한 2Mbps 위성링크에서 Eb/No가 6dB 이하에서는 실제적으로 제공할 수 있는 최대 전송성능의 50%이하로 떨어져 TCP/IP over ATM 서비스가 거의 불가능함을 보여주었다. FTP의 경우, 파일 크기가 작으면 최대 전송속도에 도달하기 전에 파일 전송이 완료되어 대역폭 이용의 효율성 측면에서 TCP/IP의 slow start 메케니즘이 적절하지 않음을 보여주었다. 이울러 IPoA영상회의 서비스에서도 Eb/No가 약 6.5dB 이하에서는 영상이 거의 정지되고, 메시지 전달시간도 ITU에서 권고하는 목표치를 훨씬 상회하여 서비스가 거의 불가능함을 보였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.1
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• pp.24-51
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• 2011

When supporting both voice and TCP in a wireless multihop network, there are two conflicting goals: to protect the VoIP traffic, and to completely utilize the remaining capacity for TCP. We investigate the interaction between these two popular categories of traffic and find that conventional solution approaches, such as enhanced TCP variants, priority queues, bandwidth limitation, and traffic shaping do not always achieve the goals. TCP and VoIP traffic do not easily coexist because of TCP aggressiveness and data burstiness, and the (self-) interference nature of multihop traffic. We found that enhanced TCP variants fail to coexist with VoIP in the wireless multihop scenarios. Surprisingly, even priority schemes, including those built into the MAC such as RTS/CTS or 802.11e generally cannot protect voice, as they do not account for the interference outside communication range. We present VAGP (Voice Adaptive Gateway Pacer) - an adaptive bandwidth control algorithm at the access gateway that dynamically paces wired-to-wireless TCP data flows based on VoIP traffic status. VAGP continuously monitors the quality of VoIP flows at the gateway and controls the bandwidth used by TCP flows before entering the wireless multihop. To also maintain utilization and TCP performance, VAGP employs TCP specific mechanisms that suppress certain retransmissions across the wireless multihop. Compared to previous proposals for improving TCP over wireless multihop, we show that VAGP retains the end-to-end semantics of TCP, does not require modifications of endpoints, and works in a variety of conditions: different TCP variants, multiple flows, and internet delays, different patterns of interference, different multihop topologies, and different traffic patterns.

• The Transactions of the Korea Information Processing Society
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• v.6 no.11S
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• pp.3199-3208
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• 1999

Recently the number of Internet users have been drastically increased with the introduction of WWW browsers, which requires accommodation study of TCP/IP on ATM networks. There are a number of problems in operating IP-over-ATM efficiently because of limited functions and overhead of IP. According to recent research, the alternatives to TCP/IP efficiently because of limited functions and overhead of IP. According to recent research, the alternatives to TCP/IP over ABR or UBR have been suggested, and the required capacity of switch buffer and problems in TCP/IP over ABR have been researched. In this paper, we address problems caused by the features of HTTP traffic and suggest a solution for TCP over ABR. The performance of the methods suggested in this paper is verified through simulation under limited conditions.