High Speed Wireless Communication Using Non-Directed Infrared Radiation

9408957卡恩非定向红外辐射是一种很有前途的大容量、短距离室内通信介质。与无线电相比，红外有几个优点，包括巨大的不受控制的带宽，以及红外辐射不能穿过墙壁的事实。因此，高速链路可以在大楼的每个房间内不受干扰地运行。现在市面上有几种基于红外的便携式计算机局域网，它们使用扩散传输，在长达15米的距离内，实现了每个房间高达4Mb/S的网络容量。目前红外使用的光学系统和调制技术可能会使网络容量增加到每个房间约10Mb/S。实现更高的比特率将需要新的解决方案来克服由强烈的环境红外辐射、多径传播引起的信号失真和来自其他用户的干扰所引起的噪声。该项目将研究提高非定向红外通信系统性能的组件和技术，该系统的比特率为10到100Mb/S，甚至更高。为了提供具体的指导，研究将解决无线多媒体计算中具有代表性的应用程序的全双工通信需求。这项应用涉及在一个房间内将多媒体从一个基站同时传输到多达50个便携终端，需要50到100Mb/S的总下行链路比特率。由于便携终端不会提供视频源，并且大多数计算将由主干网络上的服务器执行，因此上行链路要求不高，大约为每个房间10Mb/S。对于这种应用，希望将便携式红外收发机的复杂性和功耗最小化，可能的代价是增加基站的功耗和复杂性。这项研究将包括发射机和接收机的光学设计，单用户和多用户环境下调制和检测技术的理论性能研究，以及基站与便携式设备之间全双工通信的实验演示。头两年的活动将侧重于关键组件和通信技术的研究，第三年将致力于构建包含优化组件和技术的原型链路*

9408957 Kahn Non-directed infrared radiation is a promising medium for high-capacity, short-range indoor communications. Infrared possesses several advantages over radio, including an enormous unregulated bandwidth and the fact that infrared radiation cannot pass through walls. As a result, high-speed links can operate in each room of a building without interference. There are now available commercially several infrared-based local-area networks for portable computers, which use diffuse transmission to achieve network capacities as high as 4 Mb/s per room over a range as long as 15m. The optical systems and modulation techniques used in current infrared will probably permit network capacities to be increased to about 10 Mb/s per room. Achievement of higher bit rates will require new solutions to overcome the noise induced by intense ambient infrared radiation, signal distortion due to multipath propagation, and interference from other users. The project will investigate components and techniques to enhance the performance of non-directed infrared communication systems operating at bit rates for 10 to 100 Mb/s, or even higher. To provide concrete guidance, the research will address the full-duplex communication requirements of a representative application in wireless multimedia computing. This application involves simultaneous transmission of multimedia from a base station to as many as 50 portable terminals within a single room, requiring an aggregate downlink bit rate of 50 to 100 Mb/s. As the portable terminals will not source video and most computations will be performed by servers on a backbone network, uplink requirements are modest, of the order of 10 Mb/s per room. For this application, it is desirable minimize the complexity and power consumption of the portable infrared transceivers, at the possible expense of increased of increased base-station power consumption and complexity. The research will encompass transmitter and receiver optical design, theoretical performance s tudies of modulation and detection techniques in the single-and multi-user environment, and experimental demonstration of full-duplex communication between a base station and portables. The first two years of activity will focus on study of key components and communication techniques, and with the third year devoted to constructing a prototype link incorporating the optimized components and techniques ***