An adaptive control for video transmission over bluetooth

This paper is concerned with transmission of a moving picture expert group (MPEG) video stream over a Bluetooth channel, using an adaptive neuro-fuzzy technique. MPEG variable bit rate (VBR) video sources over a network generally experience long delay and unacceptable data loss, due to high variations in bit rate. Furthermore, transmission rate could be unpredictable in a Bluetooth network due to interferences by other wireless devices or general Bluetooth channel noises. Subsequently, it is almost impossible to transmit VBR data sources over Bluetooth without excessive delay or data loss. In this work, an adaptive scheme is introduced so that the controller may adjust itself to the current state of the system under control. This paper utilizes a traffic-shaping buffer to prevent excessive back-to-back transmissions of MPEG VBR data sources. A novel adaptive neuro-fuzzy scheme regulates the output rate of the buffer to ensure that the video stream from the host conforms to the traffic conditions of the Bluetooth channel during the transmission period. The computer simulation results show that the use of the neuro-fuzzy controller reduces excessive delay and data loss at the host-controller-interface, as compared with a conventional VBR video transmission and a rule-based fuzzy controller (RBF1) in Bluetooth.     

A fuzzy control scheme for video transmission in Bluetooth wireless

This paper is concerned with transmission of Moving Picture Expert Group (MPEG) video over a Bluetooth wireless network using a fuzzy approach. MPEG Variable Bit Rate (VBR) video sources suffer from long delay and excessive loss due to the sudden bursts in bit rate. Constant Bit Rate (CBR) encoding scheme may work well for a network with a guaranteed bandwidth. However, a Bluetooth channel is subject to wireless interference and can never guarantee a constant bandwidth. Subsequently, it is impossible to transmit a CBR video over Bluetooth wireless without data loss or image quality degradation. To resolve this problem, a fuzzy control system is introduced at the Host Controller Interface (HCI). The system consists of a traffic-shaping buffer whose role is to prevent excessive back-to-back cells being generated during the peak transmissions of MPEG video sources. The output bit rate of the traffic-shaping buffer is controlled by a fuzzy controller to ensure that the video stream from the host conforms to the traffic condition of the Bluetooth channel. Another fuzzy controller regulates the average arrival bit rate to the traffic-shaper to guarantee that the buffer is neither full nor empty. Computer simulation results demonstrate that the use of the fuzzy controllers reduces excessive data loss at the HCI as compared with an open loop VBR/CBR video transmission in Bluetooth.     

Wireless multimedia delivery over 802.11e with cross-layer optimization techniques

The use of wireless networks has spread further than simple data transfer to delay sensitive and loss tolerant multimedia applications. Over the past few years, wireless multimedia transmission across Wireless Local area Networks (WLANs) has gained a lot of attention because of the introduction of technologies such as Bluetooth, IEEE 802.11, 3G, and WiMAX. The IEEE 802.11 WLAN has become a dominating technology due to its low cost and ease of implementation. But, transmitting video over WLANs in real time remains a challenge because it imposes strong demands on video codec, the underlying network, and the Media Access Control (MAC) layer. This paper presents a cross-layer mapping algorithm to improve the quality of transmission of H.264 (a recently-developed video coding standard of the ITU-T Video Coding Experts Group) video stream over IEEE 802.11e-based wireless networks. The major goals of H.264 standard were on improving the rate distortion and the enhanced compression performance. Our proposed cross-layer design involves the mapping of H.264 video slices (packets) to appropriate access categories of IEEE 802.11e according to their information significance. We evaluate the performance of our proposed cross-layer design and the results obtained demonstrate its effectiveness in exploiting characteristics of the MAC and application layers to improve the video transmission quality.     

Two neuro-fuzzy control schemes for a traffic-regulating buffer in wireless technology

Bluetooth wireless operates in 2.4-GHz Industrial Scientific and Medicine (ISM) frequency, which may interfere with other devices functioning within the same frequency band, such as WiFi. Furthermore, Moving Picture Expert Group (MPEG) variable bit rate (VBR) video demands larger and more stable bandwidth and may cause data loss and time delay as a result of the high variation in bit rate in Bluetooth channels with limited bandwidth. To address these issues, two new neuro-fuzzy schemes are developed to control the input and output of a buffer referred to here as the traffic-regulating buffer. Regarding the input of this buffer, a rule-based fuzzy scheme is introduced and supervised by a neural network technique as a master controller to monitor the arrival rate to the buffer. The output of the traffic-regulating buffer is observed by another rule-based fuzzy scheme and is supervised by a second neural network to monitor the departure rate. Computer simulation results demonstrate that the two proposed neuro-fuzzy models reduce standard deviation and excessive data loss, and they also show an improved picture quality as compared with conventional MPEG VBR video over a Bluetooth channel.     

A cross-layer solution for enabling real-time video transmission over IEEE 802.15.4 networks

Over the last few years, the research community has devoted great attention to video transmission on wireless sensor networks, and in particular to their recent evolution, the one based on IEEE 802.15.4 standard. This cost-efficient wireless technology is aimed at transmitting information at low rates and short distances. Extending the use of this technology for intensive bandwidth applications is a challenge that offers the opportunity to support value-added services. This paper deals with this issue and evaluates, by analysis and computer simulation as well as by developing a first prototype, the feasibility of transmitting MPEG-4 video information over an IEEE 802.15.4 network. The study of power-consumption is also considered and so are the Quality of Service parameters together with the human quality perception of the received video streaming. A detailed cross-layer solution is offered, and the results obtained are presented and discussed.     

基于MPEG-4关键技术的视频医疗系统

通过对MPEG-4视频编码关键技术及原理的分析,利用MPEG-4视频技术实时、高效无线视频传输的特性,开发、设计并实现了基于JMF技术、应用于智能化社区的视频医疗系统。在视频医疗系统中,由JMF提供一个统一的架构和通信协议来管理基于时间媒体的获取、处理和传输。采用实时传输协议/实时传输控制协议(RTP/RTCP)很好的保证了视频传输过程中的实时性,并在JMF中引入了MPEG-4压缩算法插件进行视频压缩。MPEG-4压缩算法压缩比高,并且具有良好的网络适应性。     

多通道数字视频远程网络监控系统及其数据缓存技术

针对MPEG_1标准压缩率低，不适合远程网络传输的问题，提出远程网络传输视频压缩采用MPEG_4标准，从而在现有MPEG_1平台上实现多通道数字视频远程网络监控。首先，系统从MPEG_l压缩卡获取数据实现本地硬盘录像；然后用软件实现MPEG_l解码、MPEG_4编码和网络传输。采用面向对象和多线程技术，为每个通道准备五个数据缓存区，解决了多制式视频信号存储与实时传输中容易出现数据丢失和图像产生马赛克的难题，实现了16路以上视频信号录像、监控和多至其中任意4路可切换MPEG_4远传的大型数字网络监控系统。文章重点讨论了该系统多制式数字视频信号存储与传输中数据缓存的关键技术。     

Web-based delivery of medical multimedia contents using an MPEG-4 system

Moving picture expert group compression standard version 4 (MPEG-4) is a standard for video coding aimed at multimedia applications. MPEG-4 was developed to enable high compression rate in a low bitrate transmission via the Internet or mobile telecommunications. Although these characteristics of MPEG-4 are suitable for telemedicine, little is known about the possibility of using this technology in the field of telemedicine. We evaluated the quality of MPEG-4-encoded medical video streams and compared them with original analogue videos and audio-video-interleave (AVI) files. Although MPEG-4 video streams have the advantage of small file size, they were found to be inferior to original videos and AVI files in terms of smoothness of motion pictures, sharpness of images and clearness of sound. Illegibility of characters was a major problem in MPEG-4 files. The score for total impression of MPEG-4 files was significantly lower than those for AVI files. The results of this study suggest that the quality of MPEG-4-encoded video streams is not adequate for telemedicine.     

Adaptive unequal protection for wireless video transmission over IEEE 802.11e networks

Packet loss of video streams cannot be avoided at wireless links for limited wireless bandwidth and frequently changed environments. To provide differentiated Quality of Service (QoS) guarantees between multimedia and data services, IEEE 802.11e was proposed. However, its performance and flexibility need to be further improved. In this paper, after a survey on various modifications of IEEE 802.11e, we formulate the problem of video transmission over IEEE 802.11e networks to help scheme design and performance analysis. Then accompanied with in-depth analysis, an adaptive unequal protection schema is proposed, which is composed of three mechanisms: (1) Insert each video packet into the access category (AC) with the minimum relative queuing delay; (2) Assign each packet dynamically to a proper AC based on several parameters to guarantee the transmission of high priority frames; (3) Apply fuzzy logic controllers to adjust parameters so as to reply quickly to the variation of video data rate, coding structure and network load. Finally, regarding MPEG-4 codec as the example, we perform extensive evaluations and validate the effectiveness and flexibility of proposed scheme. Simulations are divided into WLAN and multihop parts, involving different video sequences and various traffic modes of data streams. Beside performance comparison between proposed scheme and other ones, influence of parameter setting and combination with routing algorithms are also evaluated.     

基于TD-SCDMA无线视频监控编码研究

该文在基于MPEG-4的FGS的基础之上,对其编码算法进行优化,提出适于TD-SCDMA无线网络的无线视频监控编码方案,仿真的结果表明基于MPEG-4的FGS具有较高的信噪比及视觉质量,能够较好的满足无线视频监控的需要。     

基于蓝牙的连续媒体实时传输技术的研究

由于蓝牙无线信道带宽较窄且动态变化，在其上实时传输连续媒体数据是一个巨大挑战．本文研究了其中若干关键技术．包括蓝牙通信技术、视频／音频压缩技术和自适应服务质量控制技术等．文中提出了一种基于简单网络管理协议(SNMP)的自适应服务质量控制方案．设计了蓝牙多媒体传输管理信息库(简称BMT—MIB)，通过动态监测当前蓝牙无线信道和终端系统状态，有效利用带宽等资源．文中还给出了基于蓝牙的远程监控系统原型的设计和实现。     

基于3G的无线实时视频监控系统设计

设计并实现了一种基于3GWCDMA无线网络的远程视频实时监控系统,该系统以Cypress公司的CY8C52芯片、TI公司的TMS320DM642芯片以及华为公司的EM770W通信模块为核心,融合了嵌入式、视频压缩、无线通信等技术,实现了视频的采集、压缩、传输、解码、显示等功能。该系统还对压缩模块中DSP编码选项和MPEG-4算法进行了优化,减少了运算量,提高了编码效率,使系统的信号处理能力得到了很大改善。     

MPEG- 4码率控制及其改进策略

在对现有MPEG- 4的码率控制算法分析研究的基础上,应用一些改进策略,包括基于权重的P帧目标比特分配法和联合缓存器控制算法,使码率控制算法具有更高的效率,在低码率下可以提供更好的图像质量,降低传输延迟,明显减少帧跳跃的数量,提高峰值信噪比.     

基于MPEG-2的图像压缩系统设计

针对未压缩的视频图像信号的高传输码率,占用存储空间大进行了研究,提出了一种基于MPEG—2的图像压缩编码系统,实现数字图像的无线传输,并输出传输流。通过视频解码芯片SAA7114H和编码芯片SAA6752H构成压缩模块,分析原始视频图像,经D1格式采集压缩后,分别以不同的速率传输时,视频图像质量变化,表明压缩倍数越高,图像质量越差;由SAA6752芯片引脚采集数据,将采集到的视频流数据转换为十六进制,分析数据结构及排列规律符合传输流特性。该设计方法不仅能保证良好的图像质量,提高视频图像压缩率,且能正确提取传输流。     

A systematic rate controller for MPEG-4 FGS video streaming

This paper proposes a systematic rate controller (SRC) for content-aware streaming of MPEG-4 FGS video over the Internet. An active layer dropping technique is proposed to provide both coarse-grain and fine-granularity scalability of smooth quality adaptation to bandwidth fluctuations and bit-rate variations of streamed video over a general time-scale. The smooth quality adaptation is realized through the mode and state transition of a state machine that implements the SRC. The SRC effectively uses available bandwidth and client buffer by forward-shifting the FGS video stream. It provides protection to video segments with important content by introducing a content-aware priority-based layer model for the MPEG-4 FGS video stream. RID="*" ID="*" The work reported in this paper was performed when this author was working at Microsoft Research Asia as a research intern.     

基于ARM11的无线彩色LED显示屏的控制系统设计

针对彩色LED显示屏的实际应用需求,结合嵌入式技术、视频压缩技术、无线传输技术;设计了一种可靠性高、成本低的嵌入式无线的彩色LED显示屏的控制系统;系统选用S3C6410微处理器作为主控制器,利用无线Wi-Fi接收上位机经过H.264压缩的视频信息,并进行解码,最后送入基于FPGA的彩色LED显示屏扫描系统显示;测试结果表明,系统设计合理,无线传输信号较强、支持IEEE 802.11b/g从1Mbps到最高54Mbps所有的通信速率,运行稳定,能进行较短距离的无线视频数据传输。     

Adaptive frequency hopping and power control based on spectrum characteristic of error sources in Bluetooth systems

In this paper, we propose a new adaptive frequency hopping (AFH) and power control (PC) scheme to mitigate co-channel interferences and channel noise in the Bluetooth systems. We consider a two-step interference mitigation scheme exploiting the spectrum characteristic of the interference source and channel noise. Good channels without IEEE 802.11x based wireless local area networks (WLAN) interference are first estimated by considering wideband characteristic of WLAN. Then, channel noise and interference from other Bluetooth devices in good channels are, respectively, mitigated by PC and AFH based on narrowband characteristic of Bluetooth. The performance of the proposed scheme is verified by computer simulation. Simulation results show that the proposed mitigation scheme significantly outperforms conventional schemes.     

基于相对排队延时的无线视频传输研究

无线接入和视频应用的日益普及使无线视频传输成为新的研究热点。随着研究的深入,跨层优化和不平等保护的思想逐渐为大多数研究所采纳。基于IEEE 802.11e协议研究无线视频传输质量的改善方法,提出一种综合考虑视频帧优先级和相对排队延时、适用于优先级数目有限的任何编码算法的视频帧调度算法。仿真实验结果表明,提出的算法具有远高于标准EDCA及其已有改进方案的平均峰值信噪比。     

Low-delay video control in a personal area network for augmented reality

A personal area network (PAN) is a feature of an augmented reality system, transmitting modified video for real-time display. Low-delay communication of encoded video over a Bluetooth wireless PAN is achieved in favourable channel conditions by a combination of dynamic packetisation of video slices together with centralised and predictive rate control. The result is minimised packet delay (below 0.05 s) and high-quality 40 dB video, with packet loss limited to 4 from radio frequency noise. Where channel conditions result in error bursts, dynamic rate change is introduced to reduce the need for packet retransmission and improve power efficiency.     

矿井下基于蓝牙技术的语音通讯控制器设计

提出一种基于蓝牙技术的矿井下无线语音通讯控制器设计方案,解决了蓝牙语音传输在特殊环境下容易受到外界干扰的问题;在语音通讯控制器系统结构中,采用ROK101 007蓝牙芯片做为无线通信模块,使用MSM7570芯片完成语音编解码;详细介绍了软、硬件的设计,使该语音通讯控制器达到本安型标准,从而适合在矿井下的特殊场合使用,经试用后,该语音通讯控制器传输话音清晰稳定。