How to transfer data to 54 kilometers, if there is no 220V in the cabinet?

    Information transfer via an autonomous wireless channel: the practice of building a long-distance WiFi network in sparsely populated areas of Kamchatka.

    In our practice, we often come across the opinion that WI-FI networks are used only for organizing wireless access over a small area or for links between networks over relatively short distances of about 5-10 km.
    In this review, we present an example of the implementation of a wireless network on the Kamchatka Peninsula with distances between radio channels of up to 54 kilometers in extreme weather conditions with autonomous power supply to remote points.

    The WIFI network of the Kamchatka branch of the Geophysical Service of the Russian Academy of Sciences is part of the organization’s corporate network and has several segments located in different areas of Kamchatka. The network provides round-the-clock transmission of seismic data in real time. Certain points of this network are equipped with hardware systems that provide transmission of not only seismic, but also various geophysical information and are additionally equipped with video cameras for observing volcanoes.

    One of the main segments of the wireless network is located in the areas of the city of Petropavlovsk-Kamchatsky and Avachinsky Bay, remote points of the network are located in the area of ​​the pass between Avachinsky and Koryaksky volcanoes, as well as on the coast of the Pacific Ocean - points Nalychevo and Russkaya Bay. All remote locations operate in standalone power mode through the use of solar panels in tandem with batteries.

    An example of a video image transmitted by the equipment of the complex. Volcano "Nameless".

    Dumb information about the climatic conditions of this region: the absolute maximum temperature reaches + 34 ° C, the absolute minimum from minus 24-26 ° C on the islands to minus 49-60 ° C in the north and in Central Kamchatka.
    The climate is markedly complemented by winds. In winter, they sweep over Kamchatka from the north, in the summer change to the south, so the average annual wind speed is quite moderate: from 1.3 to 8.8 m / s. In the winter season, in the south of Kamchatka and on the Commander Islands, the wind speed reaches 40 m / s. The amount of precipitation depends on the cyclones, the maximum precipitation is 1100-2600 mm per year.

    When implementing a wireless network project, the following technical requirements were presented to the equipment:
    • the minimum operating temperature of the device is -55 ° C
    • wind resistance up to 200km / h
    • tightness of the case of the radio router is not worse than IP67
    • resistance of the device casing, CPU and AFT to salt fog
    • high output power of the radio transmitter and high sensitivity of the receiver
    • high antenna gain and low feeder path loss
    • mechanical resistance of housing elements to damage (birds, animals, insects)
    • lightning protection device
    • radio operation of equipment actively used by other radio equipment
    • stable operation of the equipment for a long time due to the inaccessibility of client points

    The following diagram shows the general topology of a wireless network:


    The diagram includes several extended sections using Rapier radio equipment:
    • Lighthouse Peter and Paul - Nalychevo (51km)
    • Peter and Paul Lighthouse - Russian Bay (54km)
    • IPC Tsunami - Lighthouse “Peter and Paul” (21km)
    • IPC Tsunami - Avachinsky volcano (24km ")

    The table shows the main parameters of the links:

    Two routes pass over the city (21km, 24km) and two over water (54km, 51km).

    The Rapira radio routers were selected as the basis for building the network, both in the form of separate RS3-AP1-F5060-PTP blocks , and in the form of radio routers combined with the RS3-AP1-F5060-PTP-TH antenna (monoblocks) , providing all the technical requirements presented .
    In the described topology, all radio links are configured in the "router" mode.
    Each remote point has a separate IP subnet with 8 addresses for connecting scientific equipment.

    Consider the option of organizing wireless communications using the example of the link Peter and Paul Lighthouse - Russkaya Bay (54km).

    The base station is installed on a stationary mast near the lighthouse "Peter and Paul".

    Installation of a client data transmission unit on a support structure of pipes of various diameters, the coast of the Russkaya Bay.

    Winter view of the same station from a different angle, a little way off you can see the shelter for the block of scientific equipment.

    Mars Antennas MA-WA55-30 planar antennas were selected as antennas . Given the climatic conditions / wind loads, the antenna design had to be slightly modified, strengthening the planar blade along the perimeter with additional hardware.

    The structure of the network node:

    For the continuous functioning of the system, it was necessary to ensure:

    • mechanical resistance of knot elements to wind loads
    • guaranteed autonomous power supply of the unit

    The first problem was solved with the help of a standard set of fasteners for radio equipment, the canvas of the planar antenna housings was additionally reinforced with hardware.

    The task of ensuring guaranteed power supply was solved according to the following scheme:

    The structure of the autonomous point included:

    • block of 3 solar panels, with an output voltage of 24V and a maximum output power of 600W (model KGM195M-72)
    • radio unit based on Rapier radio routers with an external antenna
    • 350V AGM 24V battery pack based on 12 cans of 2Vh350Ah each
    • block of scientific instruments
    • battery control unit (manufactured by MorningStar)
    • battery discharge control unit (manufactured by MorningStar)
    • converter block (DC / DC24-24 and DC / DC 24-12)

    Solar panels provide recharging of the battery pack, the operation of which is controlled by the battery charge control unit.
    Stabilization and power supply of radio equipment and devices is provided by converter units.

    The use of solar panels and high capacity batteries allows you to charge the batteries during the day and provide power to the equipment in the dark. For a guaranteed battery charge, 3 solar panels are used throughout the year.

    The battery pack is based on batteries with absorbed electrolyte and has the following characteristics:

    • the battery is virtually maintenance free
    • The battery design is sealed and valve-controlled to prevent acid leakage and corrosion of the marks
    • subject to battery charging rules, gas generation and explosion hazard are excluded
    • works at low temperatures
    • vibration resistant design

    As radio equipment, the Rapier RS3-AP1-F5060-PTP radio router unit is installed with an output of 600mW in tandem with an external antenna MA-WA55-30.

    The block of scientific equipment includes seismic recorders (accelerometer and cycle meter).

    Despite limited availability, the network has been operating successfully for several years, starting in 2009. It should be noted that most of the remote points are difficult to access, some of the points can be reached only in summer or winter; The point located in the Russkaya Bay is mainly accessible in summer and only by helicopter.

    We express our gratitude to the IT department of the CF of the GS RAS, in particular to the senior engineer of the department Artyom Sumakov for help in preparing the material.

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