Subject: The capacity of wireless networks

From: "P. R. Kumar" <[email-masked]>
Date: Thu, 19 Nov 1998 17:01:25 -0600 (CST)

Dear Colleagues,

Attached below is the Abstract of the paper
``The Capacity of Wireless Networks.''

The full paper can be downloaded as a postscript file from
http://black.csl.uiuc.edu/~prkumar/capacity.ps

Sincerely,
P. R. Kumar

-------------------------------------
The Capacity of Wireless Networks
P. Gupta and P. R. Kumar

It is shown that when $n$ identical randomly located nodes
form a wireless network, the throughput obtained by each node
is only $\Theta ( {1 \over \sqrt{n \log n}} )$.
This result is true whether the nodes are independently and uniformly
distributed on the surface $S^2$ of a sphere,
or on a disk in the plane.
It is the need for every node all over the domain
to share the channel with nodes in its local neighborhood
that is the fundamental reason for the constriction in capacity,
and not the possible formation of routing hot spots at the center
of a domain.

Some implications may be worth considering by designers.
Since the throughput furnished to each user
diminishes to zero as the number of users is increased,
perhaps networks connecting smaller numbers of users may
be more likely to be find acceptance.
Also, since the utilization of each node's transmitter
is $\Theta ( {1 \over \log n } )$, and the
range of transmissions
is only of the order $O( \sqrt{\log n \over n} )$,
nodes asymptotically use little power for transmissions. \\

Keywords: Wireless networks, ad hoc networks, multi-hop radio networks,
capacity, throughout, spatial concurrency.

--------------
P. R. Kumar
Professor, Dept. of Electrical and Computer Engineering, and
Research Professor, Coordinated Science Lab

Univ. of Illinois                       Off: 217-333-7476
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1308 West Main St                       Fax: 217-244-1653
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