FTTA – fiber to antenna
PDLC ODVA fiber patch line for FTTA:
Today’s mobile device users rely on wireless connections for voice, data and even video communications. Even homes and businesses may rely on wireless technology, especially those who are not in the city or suburbs of FTTH (Fiber to the Home) or FTTC (Fiber to the Road) services. Some of us now use the term FTTW as fiber-optic wireless, because no matter what type of wireless we use, wireless relies on fiber for communication backbones and is increasingly connected to wireless antennas.
Wireless is not completely wireless. The easiest way to learn about wireless is to think of it as a link to replace a cable that connects a cellular or wireless phone to a telephone system or a jumper that connects a computer or other portable Internet device to the network. In order to understand wireless, it is necessary to study several different and unique types of wireless systems, including cellular radiotelephones, wireless indoor wiring, municipal or private wireless links, and even short-range links for computer peripheral connections.
This FOA page focuses on fiber-to-the-array, with a focus on cellular towers and antennas mounted on rooftops, small cells, and distributed antenna systems (DAS). Due to its diversity, DAS will be presented in more detail on a separate page.
Why fiber to the antenna?
The reason that the fiber is used to connect the tower and then the tower is connected to the antenna is the consumer’s insatiable demand for bandwidth. In order to accommodate more bandwidth in cellular systems, new cellular protocols (4G, LTE, and anything else) are used, but more antennas are needed to support more frequencies. Therefore, a cellular tower that once had 3 antennas for coverage can have twenty-two antennas.
The increased demand for cellular bandwidth for the use of fast-growing data for smartphones and tablets requires upgrading towers – more bandwidth means more antennas. More antennas mean more cables on the tower. If these cables are coaxial, it means more weight and wind resistance, probably more than the tower design. Since the coaxial cable attenuates the signal at high frequencies, the RF (radio frequency) signal requires a large amount of power to transmit the tower.
Today’s cellular towers are undergoing retrofits to replace old copper coaxial cables with fiber optic cables to reduce weight and cost. As with other fiber optic applications, the small size and light weight allow one fiber optic cable (usually including power wires) to replace many coaxial cables. This figure shows the appearance of the current cell tower. The diagram is too complex for quick viewing, so we’ll focus on the various areas of the tower to show how the fiber is used, and then we’ll discuss installation and testing issues.
Mobile phone systems have grown into a dominant position in the telecommunications market. Countries with a century-old landline system now have more phones than land lines. Countries that have not developed a fixed-telephone-based telephone network have completely skipped them and entered the cellular wireless network directly, with a very high adoption rate.
Although cellular wireless was originally a voice network, text messaging became very popular and most users’ voices were eclipsed. Smartphones bring the Internet to mobile phones, and soon data becomes the largest traffic generator for cellular networks. In the first 3-1 / 2 years of the iPhone, AT&T claimed that their data traffic increased by 8000% – 80 times! Now, video will enter these same devices, creating faster growth for cellular network traffic.
To accommodate this level of traffic, wireless requires a new system with more RF spectrum. Current systems (CDMA for some systems, GSM for the US, GSM for the US and other parts of the world) are evolving into next-generation systems (4G, LTE) with more data bandwidth. Almost from the beginning, the cellular tower was connected to the telecommunications network via fiber optics, just like any other connection. The wireless tower has cabins on the base that connect to the fiber backbone and connect the tower to various telephone companies. As traffic increases, towers need more antennas. Instead of the 3-4 antennas on the tower, you can now see dozens of them, so the towers and buildings now look like this: or buildings.
All of these antennas on the tower or on the side of the building pose another problem. In the past, each antenna was connected by a large (~2 in., 50 mm) coaxial cable that provided both signal and power to the antenna. But for all of these antennas, the size, weight and uniform wind resistance of these cables has become a big problem, as is the cost. These towers, which have been upgraded to add many antennas, indicate problems with these large coaxial cable