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101.
下一代播出系统的主要模式将是把多套视音频节目、综合服务数据、多媒体信息复用成码流输出,实现网络化的硬盘播出。概述五莲县电视台制播设备数字化改造要求及播出系统现状,介绍硬盘自动播出系统改造方案。 相似文献
102.
Nuno Souto Rui Dinis Francisco Cercas João Carlos Silva Américo Correia 《Wireless Personal Communications》2008,45(1):45-65
In this paper we consider the use of hierarchical Quadrature Amplitude Modulation (QAM) constellations for Multimedia Broadcast/Multicast
Service (MBMS) within Wideband Code Division Multiple Access (WCDMA) based systems. These constellations are employed so as
to increase the transmission efficiency, since they are able to provide unequal error protection to different information
bit streams. With this strategy, the most important information can be received by all users while the less relevant information
will only be extracted by users with good propagation conditions. However, these constellations are very sensitive to inter-symbolic
interference introduced by multipath propagation, especially for large constellations. Moreover, large hierarchical constellations
have also high channel estimation requirements. For these reasons, we propose an iterative receiver for joint detection and
channel estimation. The proposed receiver takes advantage of the turbo-code present in the transmission system and uses feedback
information from the turbo-decoder to estimate and suppress the interference, as well as to provide enhanced channel estimates. 相似文献
103.
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105.
Here we proposed a novel architecture of wavelength division multiplexed-passive optical network (WDM-PON) in which the downlink unicast data, broadcast data and uplink unicast data transmission is possible with the symmetric data rate of 10 Gbps. At remote node (RN) cyclic wavelength routing property of array waveguide grating (AWG) and power splitting capacity of power splitter is used in the architecture so that broadcast channel can be overlaid on downlink unicast channels. At ONU carriers sent from central office (CO) is reused for upstream data transmission with the help of integration of a reflective semiconductor amplifier (RSOA) and an electro-absorption modulator (EAM) so there is no need of extra laser sources at ONUs which makes them colorless. EAM can be operated at very high speed; a modulation bandwidth of tens of GHz can be achieved. Broadcast channel causes a limited interference with downlink and uplink unicast channels so it does not affect the system performance. Since each channel has different wavelength so NRZ data is used which eliminates expensive DPSK receivers and detection becomes very easy. Simulation is performed with all channels having data rate of 10 Gbps having acceptable performance. 相似文献
106.
广东电视台国际频道高清系统是在原有的临时高清系统的基础上建设的、具备3个高清频道播出规模的正式的、独立的高清系统.详细介绍了这套正式高清播出系统整体设计方案,并着重对新技术的应用和临时高清系统的改造完善进行分析. 相似文献
107.
Smart antennas have the advantage over traditional omnidirectional antennas of being able to orientate radio signals into the concerned directions in either transmission mode or in reception mode. Since the omnidirectional antenna use in broadcasting over the whole network is the source of an excessive redundancy of broadcast packet receptions within each node, we suggest using smart antennas to improve the medium usage in the case of broadcasting. We propose to adapt a current broadcast protocol to smart antenna applications and present two smart antenna broadcast approaches. We also present a comparative performance study between omnidirectional and smart antennas when broadcasting. We show that we can improve battery power utilisation and bandwidth usage with smart antennas. 相似文献
108.
本文通过对超高清(UHD)节目生产制作流程的实践与探索,发现问题,总结经验,为下一步在更多领域开展超高清电视节目生产奠定了基础。 相似文献
109.
《AEUE-International Journal of Electronics and Communications》2014,68(6):489-495
Disasters can be natural and human-initiated events that interrupt the usual functioning of people on a large scale. Region where disasters have occurred causes hazards to the public of that area and to the rescue teams. Disaster causes the damage to the communication network infrastructure also. Once the communication infrastructure is damaged, it is very difficult to the rescue teams to actively involve in relief operation. To handle these hazards, different wireless technologies can be initiated in the area of disaster. This paper discusses the innovative wireless technology for disaster management. Specifically, issues related to the broadcast scheduling problem in wireless mesh network is deployed efficiently during disaster relief are discussed. A domain specific memetic algorithm is proposed for solving the optimum time division multiple access broadcast scheduling problem in wireless mesh networks. The aim is to increase the total number of transmissions in optimized time slot with high channel utilization in a less computation time. Simulation results showed that our memetic algorithm approach to this problem achieves 100% convergence to solutions within reduced computation time while compared to recent efficient algorithms. The results were compared with several heuristic and non-heuristic algorithms for broadcast scheduling problem. 相似文献
110.
Transmission-scheduling protocols can support contention-free link-level broadcast transmissions and delay sensitive traffic in mobile, multiple-hop packet radio networks. Use of transmission-scheduling protocols, however, can be very inefficient in mobile environments due to the difficulty in adapting transmission schedules. The paper defines a new adaptive and distributed protocol that permits a terminal to adapt transmission assignments to changes in topology using information it collects from its local neighborhood only. Because global coordination among all the terminals is not required and changes to transmission assignments are distributed to nearby terminals only, the protocol can adapt quickly to changes in the network connectivity. The two key parameters that affect the ability of the protocol to adapt to changes in connectivity are the rate of connectivity changes and the number of terminals near the connectivity changes. Using simulation, we determine the ranges for these parameters for which our adaptive protocol can maintain collision-free schedules with an acceptable level of overhead. The stability of the protocol is also characterized by showing that the protocol can quickly return to a collision-free transmission schedule after a period of very rapid changes in connectivity. Our channel-access protocol does not require a contention-based random-access phase to adapt the transmission schedules, and thus its ability to adapt quickly does not deteriorate with an increase in the traffic load. 相似文献