Mobile backhaul and other network operators turn to microwave for quicker and less expensive, high-capacity networking. There are essentially three deployment configurations for microwave deployments: all-indoor, split-mount and all-outdoor.
Microwave systems include four major components: (1) a radio for signal transmission and reception, (2) interfaces that connect the radio link to one or more information pipes (sources and destinations for the information being sent/received), (3) a modem for modulating and demodulating the radio signal so that it can carry information, and (4) an antenna that shapes and directs the radio signal to another such microwave link.
Each deployment configuration— all-indoor, split-mount, all-outdoor—includes all four of the components, but in a different configuration. Each has its advantages and disadvantages. Let’s compare them.
An all-indoor microwave configuration means that the radio, the interfaces and the modem are contained in a rack-mountable enclosure typically installed inside an environmentally controlled hut or equipment shelter. The antenna is mounted outdoors often on a tower or rooftop. A waveguide connects the indoor radio to the outdoor antenna. Because signal strength is weakened as a function of the length of the waveguide, close proximity between the antenna and the radio is advisable.
All-indoor configurations offer convenient access to all parts of the deployment except for the antenna. The enclosure is often housed in a computer room with other equipment so it can enjoy a common electric supply and cooling.
Since it is far less expensive to maintain ground-based personnel than tower climbing technicians, the all-indoor configuration is usually cheaper to maintain than the other two. Repairs, replacements and upgrades are handled indoors in familiar and easy-to-access racks. With the electronics indoors, weather has no effect on accessibility to any of the parts except the antenna.
So why doesn’t everybody just deploy all-indoor configurations? There are some drawbacks. For one, all-indoor configurations require careful installation of the waveguide and its accoutrements (e.g., dehydrator) in order to minimize signal loss. Because of that signal loss, all-indoor deployments require transmission at frequencies lower than 12 GHz. Another drawback is that all-indoor systems generally require installation in an environmentally controlled building where rack space may be at a premium.
All-indoor deployments are used extensively by large carriers, tower companies and right-of-way companies because it is less expensive to pay for ground-based personnel than the specialized personnel who climb towers while working on active electronics.
The main benefit of the split-mount microwave configuration is that it eliminates the expensive waveguide while still providing the convenient access of the all-indoor configuration. In the split-mount design, the modem and interfaces are mounted indoors while the radio is moved outdoors to reside with the antenna. The indoor unit (IDU) is connected to the outdoor unit (ODU) via a relatively inexpensive coax cable. And since the radio sits outdoors right by the antenna, there is no need for a lengthy, expensive and signal-attenuating waveguide. The idea is to get most of the benefits of the all-indoor configuration—easy access, controlled environment—with the added advantages of lower cost and better signal strength.
Like its all-indoor cousin, the split-mount configuration requires rack space and environmental control for the IDU albeit significantly less. It also adds a tower climb for access to the ODU.
Split-mount deployments are especially popular outside of North America among telcos and enterprises.
As you might have guessed, an all-outdoor configuration puts the radio, interfaces and modem alongside the antenna usually mounted on a rooftop or tower. Because all-outdoor equipment lives outside, it is usually packed into a hardened, sealed enclosure.
All-outdoor configurations are perfect for deployment scenarios where indoor space is not available. Furthermore, all-outdoor microwave solutions require no special cooling so they tend to be more energy-efficient than the other configurations. They can often be powered via solar energy so they are perfect for remote deployments like rural areas.
All-outdoor deployments tend to be stellar performers as they take advantage of certain efficiencies possible in a fully integrated system. They also minimize and virtually eliminate the RF loss between the radio and the antenna.
The drawback to the all-outdoor configuration is, of course, that it is all-outdoors! It has to be mounted on a tower or rooftop where technicians access it with all the associated repercussions described earlier. Exposed to the elements, weather can affect performance and longevity. As a result, all-outdoor solutions must be made highly reliable and able to withstand extreme variations in temperature and harsh weather environments.
All-outdoor deployments are popular with enterprises because they tend to own the real estate where the radio system resides; they typically have no problem gaining access to rooftops or towers in order to perform radio maintenance or configuration.
Over time, all-outdoor solutions will grow in number in order to promote greener designs, reduce expenses and place equipment closer to the point of use. Space is becoming more expensive and operators can cut costs by reducing real estate, power and cooling costs—strengths of all-outdoor solutions.
Microwave transmission systems can be deployed in all-indoor, split-mount, all-outdoor configurations. Each configuration has advantages and disadvantages relative to the others. Mobile network and other operators deploy these configurations to suit given their space, signal, weather, staff, distance, power and other considerations.
Yoav Mor has been a Product Marketing Manager at Ceragon Networks for the past two years, bringing with him seven years of experience in optical and wireless network engineering for the defense industry. He holds a B.Sc. in Electrical Engineering and an M.B.A., both from Tel-Aviv University. Yoav can be contacted directly at [email protected] and his past Backhaul Forum posts can be viewed here.