Protocol Boosters in the Virtual World

Virtual environment (VE) designs have evolved from text-based systems to graphical ones. The next logical step of this evolution is to have a fully immersive environment in which thousands of widely distributed users will be able to move around and interact. Current VE architectures are unable to fully meet these requirements and a new network/protocol architecture is needed.

The VENUS (A Virtual Environment Network Using Satellites) approach addresses these problems by creating a network architecture which is scalable and flexible. We define a new architecture consisting of a transmit-only satellite/server and bi-directional links (as shown in the diagram below) which will be capable of sustaining a wide-area virtual environment. VENUS enables users equipped with the appropriate devices (video goggles, gloves etc.) to move around and interact with other users in a 3-D virtual world.

Venus Overview

Boosters in VENUS

Protocol Boosters play a key role in several parts of VENUS. For the broadcast by the satellite it is not possible to rebroadcast any portion of the frame that has been lost/corrupted during transmission since the broadcast is being sent to several thousand users. Instead, we will use Boosters to include error correction information with some of the essential packets so that receivers will be able to recover data from corrupted transmissions.

On the terrestrial links, a user transmitting from a high speed wired link will have very different charactersitics than one transmitting over a slower (and noisy) cellular link. A point-to-point link may be more secure, and thus require less encryption than a shared link. Boosters are needed to transparently adapt data according to the type of data, link quality and also available bandwidth.

Project Status

We have set up a network of computers to emulate the satellite/server, as shown in the figure below. The first ethernet network (Eth0) is used to emulate the bidirectional links, and the second one (Eth1) is a broadcast-only network for the server. The setup is fully functional and we are currently conducting experiments to evaluate the effects of packet size, number of objects and link latency on the overall system. We will later also measure the effects of Boosters on the system. The preliminary results are available upon request

Venus Experimental Setup


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