Subscribe to the Free Print Edition!
Celebrating 25 Years

GCN Home > 03/22/04 issue

NASA tests WiFi mesh networks

By Joab Jackson, GCN Staff

Mars has no data networks yet, so NASA engineers are investigating IEEE 802.11b wireless fidelity as a low-cost alternative.

But before they can equip future Mars rovers with WiFi cards, engineers at the space agency must devise a way to make the short-range cards communicate with base stations miles away.

To do that, NASA recently tested a mesh networking architecture for wireless communications at a remote Arizona site, said Marc Seibert, senior research engineer for the NASA Glenn Research Center in Cleveland.

Although the testing is not for any specific mission, the agency foresees future missions by astronauts or multiple data collection devices such as roaming rovers or stationary sensors.

Today, NASA transmitters largely use protocols designed by the Consultative Committee for Space Data Systems, a coalition of international space agencies and industry. The protocols were developed for high-latency space communications, where hops between nodes can span millions of miles. There is little commercial use for such protocols, so space communications equipment must be custom-built, which is costly.

For the past five years, Glenn and NASA’s Ames Research Center in Moffett Field, Calif., have been testing WiFi to relay data and voice over short distances. Researchers have tested commercial products from vendors such as Cisco Systems Inc. and NetGear Inc. of Santa Clara, Calif.

One difficulty with WiFi is that the end clients need access points to route data back to base stations. The access points are potential points of failure, especially in inhospitable climates and rocky terrains.

A mesh topology does not rely on a single gateway to direct traffic. Instead, each access point, or node, can forward packets from clients or from other nodes.

By having each access point automatically discover its neighbors and potentially act as a relay, the traffic can be dynamically rerouted around equipment failures.

“In a diverse terrain, the ability to take out a node and have the nodes figure out how to get data back to the base station is very appealing,” Seibert said.