We propose a novel ultra wideband (UWB) wireless tag system capable of tracking shipping containers while being loaded, closely stacked above or below decks, or being moved within shipping terminals. Each container has one or more tags that use UWB wireless technology to form an ad-hoc mesh network with its neighboring containers. In addition, each tag can measure the distance to its neighboring tags. Therefore, the information from a container buried deep in a stack of containers can be relayed by intermediate tags and emerge at the "edges" of the container stack, which have clear visibility to the local transmitter/receiver net. As each tag has the capability of communicating with, and measuring its distance to, the local transceiver net, multiple "edge" tags provide redundancy in getting the information into and out of a stack of containers reliably. The identity and distance information from the container network is relayed by the local transceiver net, to a central network controller which solves the distance/ID constraint information to provide a unique x,y,z coordinate for each container. The central controller then allows for retransmission of this data via satellite to a remote Data Center
