The need for high-speed portable multimedia workstations is expected to accelerate the use of broadband wireless local access. Portable radio head devices require low power consumption, small size and weight. The demand for inexpensive, high-speed transmission links satisfying these requirements has motivated the research on indoor wireless access. Future portable multimedia workstations need wide bandwidth connections to cabled backbone LANs in order to transfer high data rates in the order of 150 Mb/s or more in multimedia communications. There are major technological challenges for broadband wireless local access and this is an important research area. Both IR and Radio Frequency (RF) technologies are being examined for this application. However, indoor wireless IR offers a great number of advantages over indoor RF as will be explained in the next section.
The proposed research is focused on a novel design of a jointly optimized transceiver optical antenna diversity system for broadband wireless ATM indoor IR local access. To achieve this, we plan to work on a spot-diffusing multiple lines-of-sight approach through:
1. Design and fabrication of a computer generated holographic beam-splitter, to be used at the transmitter for producing multiple diffusing spots;
2. Design and fabrication of a holographic mirror combining, concentrating and filtering functions, to be used at the narrow field-of-view branches of a composite angle diversity receiver;
3. Joint optimization of transmitter and receiver parameters;
4. Prototyped models will serve as broadband wireless access means, interfacing an ATM local area network of high-speed multimedia work stations. We will also investigate whether Quality-of-Service (QoS) of an end-to-end ATM virtual connection can be guaranteed through such a wireless physical medium.
In comparison with any currently available wireless IR optical transmission system, the effort should result in a higher transmission rate of about OC-12 and a larger range of coverage of about 100 meters diameter. The wireless configuration will be capable of handling many-to-one and one-to-many communications without direct line-of-sight requirements and will be tolerant to shadowing and blockage.
