Wireless Relay Networks
Mathematics of Relaying and Cooperation in Communication Networks
April 11,2006 03:00 PM to 03:30 PM
Speakers:
Franceschetti, Massimo
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Abstract: |
It is well known that the throughput capacity of wireless networks scales poorly as the network size increases and all nodes wish to communicate simultaneously. In this talk we focus on the scenario when a constant density of nodes is randomly scattered in an increasing area and only two nodes wish to communicate at any given time, while all others can be used as possible relays. Using a percolation argument and a simple TDMA construction it is shown that in this case any pair, among an arbitrarily large fraction of the nodes, can maintain a constant bit-rate. On the other hand, an ergodic argument shows that this fraction can never be one, irrespective of the nodes cooperation strategies. Namely, there always exists a positive fraction of poorly connected nodes, among any two of which the rate must tend to zero as network size tends to infinity.
Stated informally, the conclusion is that in a wireless network it is not possible to have full-connectivity (i.e. a non-vanishing rate among any pair of nodes), but it is indeed possible to have almost-full connectivity (i.e. a non-vanishing rate among almost any pair of nodes). The constant rate in this latter case clearly depends on the fraction of connected nodes.
This is joint work with Olivier Dousse and Patrick Thiran. |
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