Parallel operation of wireless solutions

Parallel operation of wireless solutions

Reliable communication

Problem-free coexistence between wireless solutions in industrial environments.

The biggest advantage of wireless communication lies in the use of free space as an open, public transmission medium. In contrast to a wired installation, this does not result in additional costs or installation effort. The free space can be used to move freely and the transmission medium is not subject to wear.

This transmission medium is, however, a limited resource. It is not made available exclusively to a specific application but is used by all applications that generate electromagnetic waves. Since an increasing number of applications are using wireless communication in industrial systems, the use of this resource needs to be coordinated.

Mutual interference between wireless applications

Mutual interference between wireless applications  

Mutual interference between wireless applications

The shared use of this transmission medium can sometimes result in conflicts and mutual interference. This only happens, however, when the wireless signals of two or more wireless systems interfere with one another in the same place, at the same frequency, and at the same time.

The effects of this in practice depend on the application in question and the immunity of the wireless technologies used. In addition to the wireless technology, wireless planning determines spatial and frequency overlapping while the application determines temporal overlapping.

Effects

Example time response with and without wireless interference  

Example time response with and without wireless interference

Mutual interference between wireless applications does not necessarily result in a communication failure. The main effect is an extended transmission time (latency) and increased jitter. The delay and the degree of fluctuation (jitter) depend on the immunity of the wireless technology and wireless system used.

In order to ensure a high degree of reliability in spite of this, all wireless technologies use robust modulation processes as well as internal mechanisms for error correction and the resending of telegrams. As a result, central coordination and wireless planning is essential, particularly for time-critical applications, in order to eliminate mutual interference from the outset.

Coexistence management

Professional planning and design of wireless applications and manual frequency and wireless channel planning guarantees the reliable parallel operation of several wireless applications in a single location.

Trusted Wireless 2.0 and the industrial Bluetooth solutions from Phoenix Contact provide additional support during manual frequency planning with special functions. The individual steps involved in coexistence management are described in more detail in VDI directive 2185 and IEC EN 62657-2. These steps, particularly those designed to minimize wireless interference, should always be supervised or implemented by an expert.

Coexistence is possible by means of isolation in at least one area (location, frequency or time):

Physical isolation

  • Adjustment of the transmission power
  • Selection of antennas
  • Placement/alignment of antennas

Isolation within the frequency range

  • Channel selection
  • Blacklisting of frequency ranges or channels

Minimization of simultaneous frequency occupation

  • The average utilization of all individual systems should be kept to a minimum

Other sources of electromagnetic interference in industry

Implementing wireless communication reliably in industry means safely excluding electromagnetic interference. There are many sources of electromagnetic interference, for example welding processes, switching operations or frequency inverters. The electromagnetic fields they emit only reach low frequencies in the kilohertz or lower megahertz range, however.

Data transmission, however, only generally takes place at 868/900 MHz or above 2.4 GHz, and is therefore far higher than the frequencies occupied by common industrial interferences. This therefore eliminates adverse effects from electromagnetic sources of interference commonly found in industry.

Interference spectrums from other typical industrial applications

Interference spectrums from other typical industrial applications

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