Chapter 17: Microwave− and Radio−Based Systems

   

       The technology used for microwave communication was developed in the early 1940's by Western Union. The first microwave message was sent in 1945 from towers located in New York and Philadelphia. Following this successful attempt, microwave communication became the most commonly used data transmission method for telecommunications service providers.

          With the development of satellite and cellular technologies, microwave has become less widely used in the telecommunications industry. Fiber-optic communication is now the dominant data transmission method. However, microwave communication equipment is still in use at many remote sites where fiber-optic cabling cannot be economically installed.      

           In terms of business industry, the technology of microwaves have been taken for granted for years. It is quietly grown into a $4.6 billion global business annually with the expectation that will reach up to $10 billion by 2006. Microwaves also becomes a vital link in the overall backbone networks over the years. Achieving the new acclaim in the wireless revolution, microwaves are now relaying thousands of telephone conversations from place to place, bypassing the local landlines. Microwaves are between 1 mm and 30 cm long, and operate in a frequency range from 300 MHz to 300 GHz.

Possible market share for microwave products

          Today's microwave radios can be installed quickly and relocated easily.Several installations have taken over a year to be approved, only to have the radio system installed and running within a day or two. Compared to landlines which are vulnerable to everything including flooding, rodent damage, backhoe cuts, and vandalism, microwave systems provide more reliable service. Using a radio system, a developing country without a wired communications infrastructure can install a leading−edge telecommunications system within a matter of months. For these reasons, regions with rugged terrain or without any copper landline backbone in place find it easier to leap into the wireless age and provide the infrastructure at a fraction of the cost of installing wires.

         The cellular and Personal Communications Service (PCS) industries invested heavily in microwave radios to interconnect the components of their networks.In addition, a new use of microwave radio, called micro/millimeter wave radio, is bringing transmission directly into buildings through a new generation of tiny receiver dishes.Tens of thousands of new cell sites and PCS sites have been constructed and will continue to be constructed over the next few years, further expanding the use of microwave radio systems in each of these sites. As third−generation, handheld devices make their way into the industry, more wireless inter-connectivity will be used.

         Microwave also played a very crucial part of the PCS industry as the PCS systems use the 1.9 to

2.3 GHz frequency band.One study indicated that the PCS industry would spend over $3 billion in microwave equipment and services by 2005.

    The newer micro/millimeter−wave radios, which are smaller and usually less expensive than other microwaves, are also popular with these CAPs and PCS suppliers. They are used in urban areas to extend the fiber networks. These radio units use the high−frequency and width that hadn't been used before.An advantage of these systems is the small antennas that can be hidden on rooftops without interfering with zoning ordinances or creating aesthetic controversy.

Advantage and Disadvantage of Microwave

Advantage:                                                        
            1. No cables needed                                        
            2. Multiple channels available
            3.Wide bandwidth
 Disadvantage:
            1. Line-of-sight will be disrupted if any obstacle, such as new buildings, are in the way

       2.Signal absorption by the atmosphere. Microwaves suffer from attenuation due to atmospheric conditions.

            3.Towers are expensive to build

Analog microwave into Digital microwave

         Analog microwave communication may be most economical for use at your tower sites simply because it is already paid for and in service. If you are already operating microwave equipment, it is most likely analog. To avoid having to retrain your operators, you may want to stick with the analog microwave communication equipment you already have. Because you've already gotten comfortable with this equipment, you've probably also learned its capabilities, so you're unlikely to overburden your transport system with new digital equipment.

        Digital microwave communication utilizes more advanced, more reliable technology. It is much easier to find equipment to support this transmission method because it is the newer form of microwave communication. Because it has a higher bandwidth, it also allows you to transmit more data using more verbose protocols. The increased speeds will also decrease the time it takes to poll your microwave site equipment. This more reliable format provides for more reliable reporting with advanced communication equipment, while also allowing you to bring in your LAN connection when it becomes available at the site.

For more information about microwaves,kindly watch this video:

SOURCE: 
http://www.dpstele.com/dpsnews/techinfo/microwave_knowledge_base/microwave_communication.php
http://www.sqa.org.uk/e-learning/NetTechDC01CCD/page_44.htm
Broadband Telecommunications Handbook (VPN 3GW GPRS MPLS VoIP SIP).pdf