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Introduction
Scaling and increasing the performance of wireless communication systems in the 5 GHz frequency range required an increase in the allowed frequency channels number by using channels for military and meteorological radars data transmission. To reduce the impact of wireless broadband systems on radars, the data exchange protocol included requirements for detecting radar and immediately leaving the frequency it operates.
The radar detection mechanisms implementation was connected with the air scanning methods and transition between frequency channels. These methods were included in the requirements for wireless systems and were called dynamic frequency selection (DFS).
Dynamic
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Frequency Selection and radar detection
It is necessary to separate the mechanisms of dynamic frequency selection and radar detection:
- The dynamic frequency selection implementation require the available frequency channels scanning and the selection of the least noisy channel. Thus, the wireless data transmission systems distribution over the frequency spectrum is performed.
- A radar detection mechanism is necessary to a ban the use of frequency channels that radars operate on. Thus, the DFS technology retains the possibility of using such channels by broadband systems, in case they are immediately released when radar operation is detected.
Regulatory requirements
Regulatory requirements for wireless communication systems vary by country. The most common requirements for the implementation of dynamic frequency selection and radar detection in devices, were formed by the Federal Communications Commission (FCC) and the European Telecommunications Standards Institute (ETSI).
The limitations in InfiNet devices can be performed by the license which includes the set of frequencies used in the configuration and the presence of the radar detection option. A license may be issued in accordance with the regulations for a particular territory.
DFS operation principles
The dynamic frequency selection algorithm consists of the following steps:
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Video 1 - Dynamic frequency selection algorithm |
The radar detection principle
The radar detection algorithm operation can be described by the following steps:
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Video 2 - Radar detection algorithm |
Instant DFS
The DFS mechanism disadvantage is the inability to quickly assess the radio and timely change the operating frequency in accordance to the situation on the air.First solution is to make scanning the air more frequent, however, it should be understood that the time spent on updating information about the radio parameters is not used to transmit data, i.e. communication system performance decreases.
InfiNet devices use proprietary technology called Instant DFS, which allows to obtain current information about the radio state, without breaking the connection.
Instant DFS operating principles
Instant DFS operation principle is similar to the described DFS algorithm, but it has the following differences:
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Video 3 - Proprietary Instant DFS algorithm |
Instant DFS application patterns
Devices with Instant DFS support can be used in point-to-point and point-to-multipoint topologies. Note, the scan results are valid only for the received signal, therefore:
- In point-to-point topologies, it is recommended to use both devices with Instant DFS technology. During operation, the devices will exchange scan results and the decision about frequency selection will be made taking into account the interference situation on two sites.
- If in the point-to-point topology it is not possible to use both devices with Instant DFS support, then the device with Instant DFS needs to be installed on site with the most hard interference conditions.
- In point-to-multipoint topologies, if it is not possible to use all devices with Instant DFS support, the best option would be to install an Instant DFS device as a base station sector.
Instant DFS implementation in the InfiNet devices
Instant DFS proprietary technology support is implemented in devices of the InfiLINK 2x2 and InfiMAN 2x2 families operating in the 5 GHz frequency band through the additional radio module installation. Lowercase letter "s" in the device part number indicates the presence of the second radio module, for example R5000-Mmxbs/5.300.2x500.2x16.
All InfiLINK XG family devices operating in the 5 GHz frequency band support Instant DFS technology.
Additional information
- DFS configuration process for InfiLINK 2x2 and InfiMAN 2x2 family devices (web / CLI)
- Online course "InfiLINK 2x2 / InfiMAN 2x2: Initial Link Configuration and Installation"
- DFS configuration process for InfiLINK XG family devices (web / CLI)
- Online course "InfiLINK XG Family Product"
- Units Numbering Convention