Seen tonight in the West End, two Mobi bike-share stations with a “relay box” in place.
This box communicates to and from the bikes (via ZigBee), and from the box to the Mobi Mothership servers (via GPRS). The relay box is solar-powered, and the bikes’ electronics are powered from the front wheel hub dynamo (a.k.a. generator). Both communications protocols are oriented to short data bursts, and use little power, so are great choices for Mobi.
GPRS is a subset of the cellular networks. ZigBee is short-range point-to-point.