Monte Carlo Aproach for Internet Broadcasting Systems
by
Emanouil Atanassov
Central Laboratory for Parallel Processing, Bulgarian Academy of Sciences, Acad. G. Bonchev Bl. 25A, 1113 Sofia, Bulgaria
Coauthors: Todor Gurov (Bulgarian Academy of Sciences and Brooklyn College - CUNY)

The expansion of the Internet and especially of the Web led to the introduction of web proxies or caches as an intermediary between the end user and the web or ftp server. These proxy servers keep local copies of the "most wanted" documents, saving bandwidth and decreasing the response time.

Since installing and servicing such caches is relatively simple and economically beneficial in most cases, they are widespread at all levels of the Internet hierarchy.

When an Internet Service Provider (ISP) is using a satellite connection at least for one-directional communication with the bigger ISP and the Internet, there are some peculiarities which lead to the idea of broadcasting some of the "most wanted" content from the big ISP to the smaller ISP. Indeed, when satellite communications are used, the price of broadcasting the same content to all ISPs is almost the same as the price of sending the content to one ISP only. In practice one satellite channel is divided between many ISP and the respective content is encoded.

These considerations suggest that it would be beneficial for all the participants in such a scheme to have a broadcasting channel wider that the usual channels, dedicated to sending the most popular content to all of the ISP.

In such a setting there are different problems which require investigation. Since there are practical limitations to the size of the ISP caches, the simplistic solution of sending all the cacheable content to all ISP is infeasible. The second problem is the pricing of such a service, since the effective bandwidth of the broadcast channel for the smaller ISP is much smaller than the nominal.

Our approach is to simulate the function of such a broadcasting system using Monte Carlo method. We analyze statistically the logs of some ISP caches in order to obtain information about the distribution of requests by their frequency and size.

We investigate different algorithms for selection of the content for the broadcast channel under our model and obtain qualitative and quantitative results, which allow for the assessment and optimization of the input and output parameters of the scheme, for instance the optimal cache size for the ISP under the new conditions and the utilization of the broadcast channel depending on it's bandwidth. In general, we use Poisson processes and continuous time for our simulation.

http://copern.bas.bg/~emanouil

Date received: March 5, 2000

Copyright © 2000 by the author(s). The author(s) of this document and the organizers of the conference have granted their consent to include this abstract in Atlas Conferences Inc. Document # caen-45.