The rapid progress in semiconductor technology and chip mounting technology has made it possible to produce portable computes with high performance, such as notebook computers and PDAs. Portable computes can be used anytime and anywhere. By using the features of mobility, some cooperative works anywhere with multiple portable computers have been realized. However, present networks such as a wireless LAN or a public wireless network are too limited to permit portable computers to cooperate with each other. As the result, a new networking technology for portable computers has been highly requested. In this paper, we propose a novel network technology suitable for face-to-face communication, which we call "Wireless DAN" (Desk Area Network). Here, face-to-face communication is a communication between people who can directly see faces and hear voices with each other. In Wireless DAN, computers independently recognize the network configuration around them. Although present computer networks assume permanence and all computers must be registered before the system can be used, Wireless DAN enables a computer to communicate with computers nearby at any place the user goes without any complicated procedures or dedicated network equipment such as a base station. We also present a new support system for face-to-face cooperative work, which makes it possible to join or leave a meeting while it is in progress. We have developed an experimental system of Wireless DAN and the support system, which is comprised of notebook personal computers with an existing peer-to-peer infrared LAN card. The support system has been implemented using the functions provided by Wireless DAN and thus the system has been simplified. With the experimental system, we confirmed that Wireless DAN operates effectively for face-to-face communication.

The use of high-performance portable computers has become widespread. It is expected that many people will carry large amounts of multimedia information in these portable computers. In face-to-face communication, however, few systems are capable of exchanging multimedia information. Previously, we developed the Nomadic Collaboration Support System, which supports face-to-face communication through conversation and the distribution of documents. The system makes it possible for each participant in face-to-face communication to distribute electronic documents to other participants and edit them synchronously. However, it is often impossible for participants to obtain suitable amounts of information during face-to-face communication because of the difficulty in tailoring the documents for each participant. In this paper, we propose a technique to exchange hypertext documents on the Nomadic Collaboration Support System, which will allow each participant to obtain the most suitable amount of information possible from the distributor without his tailoring documents for each participant.