Bell Labs' Blue Cell dropped the signal processor so a cell site ran on solar

Ars Technica reported in April 2015 on Bell Labs' research effort Blue Cell, which aimed to simplify cellular access points by removing the wires. More cells mean fewer devices per tower, but each access point needs power and a network connection, and large towers bring siting permits and contracts.

Engineers found the biggest energy draw in existing hardware was the digital signal processor, which converts the cellular signal into something sendable over network cables. They removed it, dropping consumption from 100W at full use to 10W (500mW idle). Blue Cell shifts signals into a different frequency with more bandwidth and forwards them to an existing access point that handles the network backhaul.

Solar panel prices had plunged, so removing the power cord was feasible if energy needs fell.

A big solar panel would face the same siting trouble as a tower, so the load had to shrink.

Relaying to an existing access point avoids running new network cabling.

Find the component that eats most of the power budget and ask whether the job needs it at all.

The unit could run from a solar panel about twice the size of an adult hand, with a small battery holding three days of backup power. It was still preliminary research hardware: it needed line of sight to the tower, and the tower hosting the backhaul still needed significant reworking. Ars noted it might help where power is erratic; no deployment was reported.