Souped-Up Mesh Networks

In an effort to make a better wireless network, the Cambridge MA-based company BBN Technologies announced last week that it has built a mesh network that uses significantly less power than traditional wireless networks, such as cellular and Wi-Fi, while achieving comparable data-transfer rates.

The technology, which is being funded by the Defense Advanced Research Projects Agency (DARPA), was developed to create ad hoc communication and surveillance networks on battlefields. But aspects of it are applicable to emergency or remote cell-phone networks, and could potentially even help to extend the battery life of consumer wireless devices, says Jason Redi, a scientist at BBN.

Mesh networks -- collections of wireless transmitters and receivers that send data hopping from one node to another, without the need of a centralized base station or tower -- are most often found in research applications, in which scientists deploy hordes of sensors to monitor environments from volcanoes to rainforests. In this setting, mesh networks are ideal because they can be deployed without a large infrastructure. Because they lack the need for costly infrastructure, mesh networks can also be used for bringing communication to remote areas where there isn't a reliable form of electricity. In addition, they can be established quickly, which is useful for building networks of phones or radios during a public emergency.

While mesh networks have quite a bit of flexibility in where they can be deployed and how quickly, so far they've been less than ideal for a number of applications due to their power requirements and relatively slow data-transfer rates. All radios in a mesh network need to carry an onboard battery, and in order to conserve battery power, most low-power mesh networks send and receive data slowly -- at about tens of kilobits per second. 'You get the low power,' says Redi, 'but you also get poor performance.'

Especially in military surveillance, the data rates need to be much faster. If a soldier has set up a network of cameras, for example, he or she needs to react to the video as quickly as possible. So, to keep the power consumption to a minimum and increase data-transfer rates, the BBN team modified both the hardware and software of their prototype network. The result is a mesh network that can send megabits of data per second across a network (typical rates for Wi-Fi networks, and good enough to stream video), using one-hundredth the power of traditional networks.