Broadband Optical/RF Wireless Networks with Topology and Diversity Control

There is a growing need, especially in light of Homeland Security, for surveillance of our critical infrastructure, including road, water, electrical, and rail systems. There is an equally compelling concern for a high level of effectiveness among first responders to incidents that may be terrorist related, but could also be the result of weather events or hazardous spills. In both cases, there is an urgent need for high quality video-based surveillance, advanced specialized sensors and high bandwidth communications, which are portable, secure, reconfigurable and offer high availability. Such sensor-communication (SC) networks will be extensive, must be compatible with legacy communication infrastructure, and must be able to transport large quantities of data, which could involve Gb/s data flows from systems of high-resolution cameras. They must be rapidly deployable, and provide in essence an instant communications infrastructure. The use of free space laser communication links, here called optical wireless, is emerging as an important solution to this problem. It is our belief that autonomous optical wireless communication nodes (locations where data are generated or relayed) have the ability to meet the requirements of portability, security, reconfigurability and availability. They provide the data rates required, do not interfere with existing RF mobile communications, and provide a bridge from where data are generated to the nearest optical fiber connection.

In this proposal we describe research on optical wireless in conjunction with other technologies to provide a robust, advanced SC network. A key focus is the development of autonomous (solar-powered) optical wireless transceivers, which have the ability to point and track, can handle continuous or bursty data, and can function in a dynamic, self-configuring network environment (instantaneous infrastructure). The ability of optical wireless communications to provide bursty data communication allows downloading of buffered data from moving nodes, mounted for example on rail cars, police vehicles, trucks, or barges. This permits dynamic adjustment of traffic flow within the communication network by intelligent exchange of detailed situation data between fixed and mobile nodes.

We propose to

• develop the hardware and software for multiple-connected, reconfigurable, SC networks; and
• test key concepts, in real network demonstrations within a large existing development program, the Capital Area Wireless Integrated Network (CapWIN), using interoperable data communications systems now being implemented to support first responders in the 17 political jurisdictions surrounding the national capital.