Wireless networks do not come with links. Rather, they just
consist of nodes radiating energy. Every receiver receives a noisy
complex
mixture of all the signals broadcast by all the other transmitters.
Nodes can cooperate in several complex ways.
The standard modes of broadcast, multiple-access, and relaying, only
scratch the surface and do not come close to exhausting the
possibilities
for cooperation among a plethora of nodes.
Two fundamental questions of interest are:
(i) How much information can wireless networks transport?
(ii) How should wireless networks be operated?
We present a new network information theory for wireless
communications that provides some answers to these questions. We obtain
scaling laws
for the transport capacity as the number of nodes increases. These
scaling laws depend on the attenuation in the medium,
and play the role of conservation laws for the entire wireless network.
When there is any absorption at all or there is large path loss, then
multi-hop operation is proved to be optimal. However, when there is no
absorption at all and the path loss is small, then a strategy
of coherent multi-stage relaying with interference cancellation is
optimal.
(Joint work with L-L. Xie)
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