DURING recent years, wireless has become the buzz word in the process industry.
It has been recognised that the worldwide market for wireless in manufacturing will grow at a compounded annual growth rate of 26 per cent over the next five years, and savings in installation costs will drive significant improvement in process automation, according to the ARC Advisory Group.
Wireless technology should not be adopted simply because it is the latest and greatest technology on the market. A wireless technology investment must be made for strategic and business reasons. This should not be done simply for a cost saving reason alone. In some cases, there are additional costs associated with planning and installation of antennas. However, the benefits of losing the wire can create significant opportunities, provided the design is sound.
Ultimately, wireless access to the wired world provides the avenue to an expanding array of enablers and solutions. The key factors in the design of an industrial wireless infrastructure are scalability, reliability and security.
SCALABILITY
Industrial wireless scalability is best addressed by an infrastructure approach. In the wireless world, we are now faced with radio frequency and bandwidth issues that are not factors in the wired world. Coexistence with existing wireless deployments and the ability to allow for new solutions need to be primary concerns.
To accomplish all of this, an architecture combining multiple frequencies, bandwidths and protocols is necessary. Infrastructure devices may include multiple radios and multiple access scenarios to provide for the greatest flexibility. A high-speed, high-bandwidth wireless backbone is essential.
The design should be an open system that allows connection to any plant system and inherently transports existing protocols. It must also be able to provide wireless remote access for a number of wireless and wired devices and their supporting applications. Therefore an infrastructure that combines sensor radios, wireless Ethernet, remote wired
Ethernet and Wi-Fi access should be part of any industrial wireless infrastructure design.
A robust wireless infrastructure must also provide bandwidth flexibility not only to conform to country restrictions but allow for the optimal utilisation of bandwidth. Infrastructure members that allow the use of multiple radios best accomplish this and allow for any future developments in radio technologies and standards.
RELIABILITY
Reliability is affected by many factors such as coexistence, redundancy and availability. What is becoming more and more common is legacy wireless in the infrastructure that needs to be addressed.
These outside sources may cause interference and or may need to coexist. An industrial wireless infrastructure must support coexistence and make the best use of a limited spectrum. This is often handled by assessing the site to determine what wireless spectrum is in use and what is available, and configuring the infrastructure hardware to assure reliability for site-wide use.
To assure reliability, an industrial wireless infrastructure must assure redundancy. It must be able to handle multiple hardware failures with no degradation in performance. This is best accomplished by ensuring redundant communication paths forming what is known as a mesh. This communications mesh assures that sensor and system communications have multiple paths to relay information to the wired world.
The most reliable designs assure the sensors are in parallel communications on at least two paths
A robust design also utilises a powered mesh infrastructure to assure availability with fast mesh reformation and no significant loss in performance as the wireless system expands. Power management on the sensor level is also extremely important. Deterministic power consumption and alerting of battery levels assures long life and planned availability of sensor data.
The design should also assure that sensor traffic is given dedicated bandwidth on the high-speed backbone to ensure no degradation and the infrastructure supports more and more applications.
SECURITY
Security is essential in the design of an industrial wireless infrastructure. Security begins with the integration of the gateway to the wired infrastructure through to the secure commissioning of sensors.
Any wireless infrastructure device should permit for all the latest implementations of network security allowing for replay protection, source authentication, and resistance to denial of service attacks, and security deployment and management. Robust security should extend to the sensor level by utilising advanced security deployment methodology.
Finally, the key to building an industrial wireless infrastructure is coordination and support. Beyond providing hardware that fits the industrial environment, it is important to have an industrial wireless partner that can comprehensively address all the issues from sensor network through wired interface and Wi-Fi solutions.
Preferred is a single source partner that is equipped to evaluate, design, implement, monitor and assist in expansion of the wireless infrastructure. The goal is a single open, standards-based, upgradeable industrial network that can reduce risk and associated support cost.
