January 25, 2005 
Joint Meeting with ISA

Self Organizing Wireless Ad Hoc Networks for Instrumentation
Chien-Chung Shen, PhD
Assistant Professor
Computer and Information Science
University of Delaware

In last year's joint IEEE/ISA meeting, ISA arranged for Mark Fondl to speak on Industrial Communications Technologies. During the question period, Mark said that the next big event in this technology would be wireless.

Dr. Chen gave us an idea of the problems involved when wireless technology is introduced to enable many nodes to communicate with each other. This technology is currently built around the 802.1X, where we are familiar with the 802.11b (wifi) and 802.15.1 (Bluetooth), standard. The currently identified problems to overcome with wireless are:

  • Decreased signal strength with distance, and with increasing bandwidth
  • Interference with the many other devices operating in the so called "Industrial" frequency of 2.5 GHz. This "industrial" frequency is one which the FCC allows to operate without need for a license.
  • Multipath propagation due to reflections
  • Hidden terminal-all nodes cannot communicate with every other node on the network
  • Signal fading
  • Colliding communications-due to many attempts to talk at the same time.

We also heard about the ad hoc mode, where no base station is used and nodes can organize themselves into a network. In a mesh network, the nodes do not move. Microsoft, who wants to have many Microsoft mesh networks organized, is promoting this kind of network. In a mobile network the nodes can move around, and as the distances change, nodes can find signal strength to low, look for and join another one.

In the area of protocols, we heard that Proactive Protocol is when communication routes are computed prior to need, which could be seen as wasteful of energy. Mobile networks are likely running on battery power and are sensitive to any energy consuming activity. Reactive Protocol is used to compute a communications path only when the need arises. 

Dr. Chen said that the next big "killer app" after the internet will be the wireless network.