• Journal of IKEEE
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• v.13 no.4
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• pp.29-36
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• 2009

The packet loss and the disconnection during handoff are the most critical problems which degrade the video quality in wireless video streaming. To cope with these problems, we propose an efficient video streaming method in this paper, which does not only dynamically adjust the video transmission rate based on the raptor forward error correction (FEC) level, but also minimize the error propagation during handoff. Firstly, the channel bandwidth of the wireless broadband internet, called WiBro, is estimated by analyzing channel parameters including the carrier to interference and noise ratio (CINR) and the handoff. Secondly, the streaming server adjusts the next transmission rate according to the estimated channel bandwidth and the raptor FEC level to avoid packet error. Also, the encoder performs the intra refresh method that inserts an intra frame (I-frame) right after handoff to reduce the error propagation effectively. Experimental results indicate that the proposed method can improve the performance of the video streaming over WiBro network.

• Journal of Advanced Navigation Technology
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• v.15 no.3
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• pp.386-391
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• 2011

CRU (contiguous resource unit) composed of adjacent OFDMA subcarriers is popularly adopted for recently developed cellular communication standards, e.g. IEEE 802.16e/m. If multiple CRUs having different SNR are assigned to a mobile station, and multiple packet streams are independently transmitted by using H-ARQ transmission, an achievable data rate can be varied according to the channel allocation method of re-transmission packets and new transmission packets. In this paper, the optimum channel allocation method for the above stated problem, and several sub-optimum channel allocation methods to reduce the computational complexity of the optimum allocation method are proposed. According to the simulation results, a sub-optimum allocation method assigning a CRU having good SNR to new transmission packet shows marginal performance loss compared with optimum method, however, the computational complexity can be significantly reduced.

• Journal of Advanced Navigation Technology
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• v.23 no.6
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• pp.548-553
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• 2019

Along with advanced vehicle to vehicle (V2V) communication technologies, platooning is regarded as one of the most promising form of autonomous driving solutions in order to increase road capacity. In this paper, we propose a novel V2V transmission scheme for safety message dissemination in platooning. The proposed scheme enhances the efficiency of channel access and multi-vehicle orthogonal frequency division multiple access (OFDMA) transmission by taking advantage of triggered uplink access technique and null data packet feedback report protocol introduced in the sixth generation WLAN standard, IEEE 802.11ax. The simulation results prove that the proposed scheme outperforms the conventional IEEE 802.11 transmission scheme throughout all measured vehicle density range.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.6C
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• pp.471-479
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• 2008

In this paper, we propose a novel algorithm to automatically generate an RTP timestamp value that is required for the RTP packetization in order to transmit SVC video over various If networks such as Internet. Unlike the conventional single layer coding algorithms such as H.263, MPEG-4 and H.264, SVC generates a multi-layered single bitstream which is composed of a base layer and one or more enhancement layers in order to simultaneously provide temporal, spatial, and SNR scalability. Especially, in order to provide temporal scalability based on hierarchical B-picture prediction structure, the encoding (or transmission) and display order of pictures in SVC coding is completely decoupled. Thus, the timestamp value to be specified at the header of each RTP packet in video transmission does not increase monotonically according to the display time instant of each picture. Until now, no method for automatically generating an RTP timestamp when SVC video is loaded in a RTP packet has teen introduced. In this paper, a novel automatic RTP timestamp generation method exploiting the TID (temporal ID) field of the SVC NAL unit header is proposed to accommodate the SVC video transmission.

• The KIPS Transactions:PartC
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• v.16C no.2
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• pp.237-244
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• 2009

The congestion in wireless sensor network increases the ratio of data loss and causes the delay of data. The existing congestion protocols for wireless sensor network reduces the amount of transmission by control the sampling frequency of the sensor nodes related to the congestion when the congestion has occurred and was detected. However, the control method of sampling frequency is not applicable on the situation which is sensitive to the temporal data loss. In the paper, we propose a new congestion control, ACT - Adaptive Congestion conTrol. The ACT monitors the network traffic with the queue usage and detects the congestion based on the multi level threshold of queue usage. Given network congestion, the ACT increases the efficiency of network by adaptive flow control method which adjusts the frequency of packet transmission and guarantees the fairness of packet transmission between nodes. Furthermore, ACT increases the quality of data by using the variable compression method. Through experiment, we show that ACT increases the network efficiency and guarantees the fairness to sensor nodes compared with existing method.

• The KIPS Transactions:PartC
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• v.9C no.6
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• pp.875-882
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• 2002

The active packets unlike traditional IP packets should be executed at each active node along their path. To execute the active program at each active node, the active packets for an active program should go through the same active nodes and all packets are delivered without any loss. This paper presents the new active engine for every active packet which execute an active program to be routed through the same intermediate active nodes and to be delivered reliably. Proposed active engine requires fewer changes to existing IP protocols and guarantees the reliable delivery of the active packets. Moreover, even if the sender does not have any information about the intermediate nodes every active packet is routed through the same intermediate active nodes. The simulation results show that proposed active engine achieves an efficient transmission with high data delivery and low communication overhead compared with the other existing transmission protocols.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.7
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• pp.1554-1560
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• 2015

802.11p WAVE is the next-generation wireless communication that can make Ad-hoc network communication possible for Vehicle-to-Vehicle. GBSR protocol, one of the 802.11p WAVE protocols, mainly focuses on improvements in networks that have a tendency to disconnect. However, it does not consider the transmission time and velocity of a packet thus, there is a disadvantage of there being a delay in the transmission velocity, in urgent situations like car accidents, emergency patients transportation and crimes. In this paper, we proposed A-GBSR protocol for transmission of a packet to mobile node which has a high speed through the improved beacon message and Adaptive Neighbor list Management that are considering of the GBSR protocol transmission velocity.

• Journal of Broadcast Engineering
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• v.12 no.2
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• pp.80-92
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• 2007

IPTV Services that is representative union service of broadcasting and telecommunication need guarantee of QoS, efficiency of multicasting, and hish bandwidth on the network. Because typical TDM based metro transport network was designed by transporting fixed voice traffic with stable and recovering method, it has a defect of bottleneck and a waste of bandwidth for acceptance of data traffic with burst feature and then all of data are treated equally at the transport network because it cannot classify between advanced high end service and best effort low end service. for completely resolving this kind of problem about increasing burst traffic and QoS issues, firstly we need to new design for transport network. This paper presents transformation method from TDM based metro transport network to packet based transport network and advantage and effectiveness of packet based transport network and also indicates technical factor and characters about method of packet transport system. As a result of research, the Packet Transport System, which is a transmission network for packet delivery, take in not only a specific character of legacy TDM but QoS, Multicast and high bandwidth, then, it is able to keep an effective bandwidth and a stabilized performance of packet transmissions. Additionally, if a fault be occurred on an optical link, the system is able to guarantee a differential QoS by an each service class using an algorithm to make certain of a traffic existence and contain a protective mechanism.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.12
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• pp.2857-2863
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• 2014

IR-UWB has been developed as a standard of indoor ranging technology, because it has robust and good transmission characteristics in indoor environments and it can be operated with low power. In this paper, a IR-UWB packet analyzer is designed and implemented based on IEEE 802.15.4a, which is useful in developing IR-UWB real time location system with resolution of a few ten centimeters. A sniffer device of the packet analyzer monitors IR-UWB wireless networks, captures MAC packet frames, and transmits packet frames to the packet analyzing computer. The packet analyzing program in a computer analyzes received MAC packet frames and displays parsed packet information for developing engineers. Developed packet analyzer is used to analyze IEEE 802.15.4a MAC protocol, and also it can be used in other IEEE 802 series MAC protocol by modifying some functions.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2006.07a
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• pp.489-489
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• 2006