• Title/Summary/Keyword: frame delay

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(A Study on an Adaptive Multimedia Synchronization Scheme for Media Stream Transmission) (미디어 스트림 전송을 위한 적응형 멀티미디어 동기화 기법에 관한 연구)

  • 지정규
    • Journal of the Korea Computer Industry Society
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    • v.3 no.9
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    • pp.1251-1260
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    • 2002
  • Real-time application programs have synchronization constraints which need to be met between media-data. Synchronization method represents feedback method including virtual client-side buffer. This buffer is used in buffer level method. It is client-leading synchronization that is absorbing variable transmission delay time and that is synchronizing by feedback control. It is the important factor for playback rate and QoS if the buffer level is normal or not. To solve the problems, we can control the start of transmission in multimedia server by appling filtering, control and network evaluation function. Synchronization method is processing for smooth presentation without cut-off while media is playing out. When audio frame which is master media is in high threshold buffer level we decrease play out time gradually, otherwise we increase it slowly.

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Performance Improvement of Ethernet using Dynamic Mode Change (동적 모드 변환을 이용한 이더넷 성능 개선)

  • 황민태;윤일환;이재조
    • Journal of Korea Multimedia Society
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    • v.4 no.4
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    • pp.349-355
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    • 2001
  • In this paper, we newly propose a performance enhanced CSMA/CD MAC(Medium Access Control) protocol for the Ethernet which changes its operation mode dynamically according to the network status, not fixed it as one of p-persistent mode and non-persistent mode. Dynamic mode change occurs independently on each node, and uses the consecutive success count and the fail count of the frame transmission. The simulation result shows that the dynamic mode change maintains the enhanced network utilization and transmission delay characteristics. Also we show the implementation simplicity of our MAC protocol through its conceptual design using the Ethernet commercial chip as it stands.

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Performance Analysis of Binary Scheduling Wheel Structure based on Weighted Round Robin (가중치 원형 분배 기반 이진 스케쥴링 바퀴구조의 성능 분석)

  • Cho, Hae-Seong;Lee, Sang-Tae;Chon, Byoung-Sil
    • Journal of KIISE:Information Networking
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    • v.28 no.4
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    • pp.631-640
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    • 2001
  • Round robin scheduling discipline, which is a sort of frame-based scheduling, is quite simple and straightforward for handling multiple queues, and by putting a different weight on each queue, a network can offer differentiated services such as different bandwidth, or delay bound. The most typical algorithm among this disciplines is the weighted round robin(WRR). Also, WRR algorithm can be implemented efficiently by dynamic binary scheduling wheel(DBSW) architecture. This paper performs the analysis of the DBSW architecture and compares the results with simulation results. The analysis data and simulation data show that the DBSW structure decreases average buffer length because it is capable of maintaining the allocated weight of each VC correctly.

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FPGA-based Hardware Prediction Rendering for Low-Latency Touch Platform

  • Song, Seok Bin;Kim, Jin Heon
    • Journal of Multimedia Information System
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    • v.5 no.1
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    • pp.59-62
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    • 2018
  • The delay between input action and visual interface feedback ("Latency") in a touchscreen inking task reduces the user's performance. When the latency is less than 2.38ms, the user cannot perceive the latency in dragging task. This value is difficult to achieve on recent touchscreens and general purpose computers. So, methods of predicting touch points to reduce perceptible latency has been proposed. In general, touch points prediction is not perfect. When using point prediction, feedback of the predicted points is displayed on the screen, after a while, erased when the actual points are displayed. When this task is implemented by software, it causes additional latency to work to erase predicted points feedback. It therefore propose a platform for rendering point prediction feedback without additional latency by the FPGA. This platform transmits input points and HDMI signals rendering feedback of input points to the FPGA. The FPGA draws the feedback of points predicted based on the input points on the HDMI and displays the screen. Since hardware rendering changes the HDMI signal every frame, it does not require erasing work and rendering can be done within an early time regardless of the amount of rendering, so we will reduce the latency.

Variable RCH Channel Assignment Scheme in HiperLAN/2 System (HiperLAN/2 시스템에서 가변적인 RCH 채널 할당방안)

  • Jang, soon-gun;Jang, jae-hwan;Lim, seog-ku
    • Proceedings of the Korea Contents Association Conference
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    • 2009.05a
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    • pp.83-87
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    • 2009
  • The MAC protocol of HiperLAN/2 is based on TDMA/TDD. Mobile terminal acquires a data transmission opportunity as successfulness in channel competition through RCH (Random CHannel) phase. Therefore, AP (Access Point) be able to dynamically assign optimum RCH at next frame according to the number of success and collision. In this paper, we suggest scheme that fluctuate RCH (Random CHannel) number as fixed value considering success and collision for improvement of performance in HiperLAN/2. To prove efficiency of proposed scheme, a lots of simulations are conducted and analyzed in view of throughput and access delay.

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Joint Control of Duty Cycle and Beacon Tracking in IEEE 802.15.4 LR-WPAN (IEEE 802.15.4 저속 WPAN에서 듀티 사이클과 비콘 추적의 통합 제어)

  • Park, Sung-Woo
    • The Journal of the Korea institute of electronic communication sciences
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    • v.11 no.1
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    • pp.9-16
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    • 2016
  • Since most of devices in the IEEE 802.15.4 LR-WPAN are expected to operate on batteries, they must be designed to consume energy in a very conservative way. Two energy conservation algorithms are proposed for the LR-WPAN: DDC (Dynamic Duty Cycle) and DBT (Dynamic Beacon Tracking). The DDC algorithm adjusts duty cycle dynamically depending on channel conditions. The DBT algorithm switches beacon tracking mode on and off adaptively depending on traffic conditions. Combining the two algorithms reduces energy consumption more efficiently for a wide range of input loads, while maintaining frame delivery ratio and average delay at satisfactory levels.

A new MAC protocol to improve a performance in IEEE 802.11 wireless LANs (IEEE 802.11 무선 랜의 성능 향상을 위한 새로운 MAC프로토콜)

  • Hwang, Gyung-Ho
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.13 no.4
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    • pp.759-764
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    • 2009
  • A new backoff scheme for infrastructure mode in IEEE 802.11 wireless LANs is proposed to improve a performance. Each station generates a unique backoff number using total number of stations, fairness parameter included in beacon frame and an user's ID that is assigned by AP. The station sends a packet after its own backoff number of idle slots, which makes a collision free access among stations within AP's coverage. The proposed method shows better performance in the view of channel utilization and packet delay than an original IEEE 802.11 CSMA/CA backoff scheme.

Analysis of V2V Broadcast Performance Limit for WAVE Communication Systems Using Two-Ray Path Loss Model

  • Song, Yoo-Seung;Choi, Hyun-Kyun
    • ETRI Journal
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    • v.39 no.2
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    • pp.213-221
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    • 2017
  • The advent of wireless access in vehicular environments (WAVE) technology has improved the intelligence of transportation systems and enabled generic traffic problems to be solved automatically. Based on the IEEE 802.11p standard for vehicle-to-anything (V2X) communications, WAVE provides wireless links with latencies less than 100 ms to vehicles operating at speeds up to 200 km/h. To date, most research has been based on field test results. In contrast, this paper presents a numerical analysis of the V2X broadcast throughput limit using a path loss model. First, the maximum throughput and minimum delay limit were obtained from the MAC frame format of IEEE 802.11p. Second, the packet error probability was derived for additive white Gaussian noise and fading channel conditions. Finally, the maximum throughput limit of the system was derived from the packet error rate using a two-ray path loss model for a typical highway topology. The throughput was analyzed for each data rate, which allowed the performance at the different data rates to be compared. The analysis method can be easily applied to different topologies by substituting an appropriate target path loss model.

Comparison Study of Helper Node Selection Schemes of Cooperative Communications at Ad Hoc Networks (애드혹 네트워크에서 협력통신을 위한 도움노드 선정방법 비교연구)

  • Jang, Jae-Shin
    • Journal of the Korea Society for Simulation
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    • v.21 no.2
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    • pp.69-78
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    • 2012
  • In this paper, a study on finding an appropriate helper node that can help increase effective frame transmission rate for cooperative communications at ad hoc networks is carried out. Those researches from reference use the reactive helper node selection mechanism which starts its role after exchanging RTS and CTS frames between source and destination nodes, and are implemented into our simulator for performance comparison. System throughput and average channel access delay are used for performance measures and all communicating nodes are assumed to move independently within the communication range. It is anticipated that this research result can be used as basic information for designing a new efficient helper node selection scheme.

Scheduling Scheme and Performance Analysis of IEEE802.15.4e TSCH (IEEE802.15.4e TSCH의 스케줄링 방식 및 성능분석)

  • Park, Mi-Ryong;Kim, Dongwon
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.17 no.5
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    • pp.43-49
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    • 2017
  • In this paper, we propose the scheduling scheme of IEEE802.15.4e TSCH which is not specified in standard specification. The proposed scheme schedules the link by cooperating among the devices. A new device scans EBs(Enhanced Beacons) from network. An advertiser device broadcasts an enhanced beacon frame including links information on allocated channel offset and time-slots, and a new device can determine its own channel offset and time-slot. It's performance on maximum throughput and minimum delay is evaluated by comparing the proposed approach with a typical single channel IEEE802.15.4.