Overcoming the Wireless Sensor Network Bandwidth Problem
One of the challenges identified in our last posting http://community.controlglobal.com/content/mobile-communications-gdp was the increasing demand on the 2.4 GHz bands to be all things to all people and that unfortunately, IEEE 802.15.4 is further hindered by the restrictions put on the radios. One possible solution is to migrate to a different unlicensed frequency band such as the 60 GHz frequency band, which has 5-mm wavelengths. Interestingly, wireless signals at 60 GHz frequencies have inherently high propagation losses and are targeted toward short-range, in-building, high-speed applications. This certainly sounds like the similar distances that are being called for with Industrial Wireless.
A recent article in the “Journal of Lightwave Technology” and summarised at http://www.physorg.com/print187346128.html states that, “Mm-wave frequency allocation around 57-66 GHz can deliver bandwidths in excess of 1 Gb/s compared to few Mb/s offered by current third generation mobile systems or 100 Mb/s offered by Wi-Fi systems” In addition, there are even higher mm-wave frequencies which have much larger bandwidths available. However, the technologies for these are not yet matured and over time, the mm-wave band could be exploited to give bandwidths in excess of 10 Gb/s over short-range wireless. Fiber-wireless could be commercially ready in 3-5 years so NOW is the time to investigate this technology for its applicability to the industrial environment and perhaps also influencing the direction of its development so that it is suitable for industrial use and NOT restricted as could potentially be happening in the EU so that the license free bandwidths are available for remote control “toys.”
If not, for direct connection to the sensors themselves, Fiber-wireless could perhaps be used as a way to take the load off the access points, or at least replace some of the mesh routers with these higher bandwidth devices through to a fibre based access point and overcome the potential restrictions on “real time” response rates in practically any environment or vertical industry including factory automation.