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Outdoor Mobility

Not for Amateurs


Point-to-multipoint

Wireless connections in outdoor areas differ in terms of technical implementation and legal compliance (LAN or WAN).

The most common case is that often referred to as the ‘last mile,’ that is, providing users with an Internet connection where a DSL connection is not possible or foreseeable. Outdoor Wi-Fi in point-to-multipoint operation often caters to the last mile access. Here, several customers are supplied via one single node.

Using the 802.11a standard in the ‘upper band’ delivers transmission power of one watt, which is enough to sufficiently supply medium-sized areas. The fact that the users share a theoretical maximum bandwidth of 54 Mbps (effectively approximately 22 Mbps), means that there are virtually no limitations or restrictions.

The new 802.11n standard offers even more development potential, not just because of MIMO technology and the increased bandwidth of up to 150 Mbps, but also thanks to mesh technology, which allows the user to centrally manage connections across multiple hops, and offers a considerably better redundancy concept if designed in the correct way.

However, the required line-of-sight connection complicates matters. Non-line-of-sight solutions also require careful location and capacity planning if the aim is to keep downtimes below one percent (this would mean an average of 3.5 days without a connection, based on a 365-day year).

It is also important to select the correct antennas and lightning and surge protection. In this case, ensuring compliance with the usual technical requirements requires specialists in the field. The same applies for installation planning, particularly outdoors, where temperature-resistant HF cables are necessary, or if the entire system has to be installed outdoors due to damping.

One key, yet frequently neglected factor, is the legal situation. Even if it’s a matter of license-free ISM solutions for 802.11 Wi-Fi, registration is still required for WWAN connections. Furthermore, operators who provide these services for others are subject to further legal obligations including data retention laws.

We have employed one person qualified in high-frequency engineering to oversee these applications. He is familiar with the basics of telecommunications and has many years of practical experience in the field. He has implemented systems for desert environments in Dubai as well as systems suitable for harsh winter conditions in Russia. If antenna diagrams mean nothing to you or you can’t remember the formula for the first and second Fresnel zones, get in touch with us. We know what we’re doing.

 
Fig.: Fresnel zone of radio links
 
 
Point-to-point
 
All of the above also applies to planning and implementing point-to-point connections. The most common case here is connecting one or several buildings using wireless technology.

From a legal point of view, it is necessary to differentiate between WAN and LAN. If the transmitter, receiver, and transmission path are located on the user’s property, only the basic LAN rules apply. If external or public areas are used, or if the building is rented, the WAN definition applies. Registration is required in both cases.

For technical implementation, the first requirement is the actual bandwidth required and the distance between transmitter and receiver(s) because both are indirectly proportional to one another. To this end, detailed planning is essential for installations of this kind, where a minimum of 99 percent stability is guaranteed, even in adverse weather conditions.

Taking the legally permitted transmission power into account, Wi-Fi systems can achieve distances up to 12 km, however, with a minimal bandwidth of 1 Mbps and in open areas. Yet even in the high-rise jungle of a city, we have managed to bridge distances of several kilometers. The maximum data throughput rates for shorter distances are approximately 20 Mbps using special outdoor router protocols.

An increase through the use of 802.11n systems can only achieve short distances of up to approximately one kilometer. However, it is possible to achieve effective bandwidth of up to 150 Mbps when using devices, for example, that support beamforming.

Systems that require a license (WiMax, private mobile radio, trunked radio etc.)

We also offer solutions even for systems requiring a license, which are usually operated by system providers and carriers. The difference in licensing costs depending on area is a disadvantage easily offset by the advantages of the dedicated frequency band. While Wi-Fi networks operating in the license-free ISM (industry, scientific, and medical) bands have to share bandwidth with other users, other systems, and high-priority radar without being able to exert an influence, a system requiring a license can work virtually uninterrupted.

Any enquiries on this matter require precise definition of the purpose of the application as well as the exact geographical location as these licenses are mainly issued on a local or regional basis.

Free Space Optics (FSO)

Wi-Fi has replaced FSO systems, which were once also installed for bandwidths under 50 Mbps, in high-load applications. Even 100-Mbps systems are hardly worth the effort as costs for lasers and precision optics are substantial. The only exceptions are if there are no channels available due to external influences.

If demand for bandwidth is in the gigabit range, FSO systems are still an attractive alternative to dedicated lines or fiber optic connections. Depending on requirements, we offer basic systems with or without Wi-Fi redundancy and multibeam systems with automatic beam tracking in order to compensate for outside influences such as wind and rain.

Given that, depending on transmission power, bandwidth, and distance, not only Class 1 and Class 1M lasers are employed, we recommend planning the installation, calculating performance, and making a TCO calculation as lasers above Class 2 require additional safety measures as well as a laser safety officer.

Fig.: LaserByte FSO system GigPronto

Our engineers are experts in high frequency engineering and have many years of professional experience. Whatever technology you opt for, they are on hand to help to help you find a solution for your problem.
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