What Is A Cellular Distributed Antenna System?

The fact remains true that cellular network connectivity is of prime importance today as we are heavily dependent on our smartphones for absolutely everything. Be it the need to access the internet, reach out to someone through messages or voice calls.

Inadequate cellular coverage can result in calls not getting through on time or not connecting; messages fail to get delivered. You fail to access the internet to get your hands on the requisite information. Also, the internet speeds are hampered as well. 

All this results in poor living standards and can also be a great source of agony, especially when a person is in a tight situation. However, this problem can be addressed with the installation of DAS. 

So, what exactly is DAS?

DAS is short for Distributed Antenna Systems. The name says it out loud and clear. These Cellular Distributed Antenna Systems are a series of antenna receivers set up to enhance network coverage and distribute it uniformly over a specific region. This infrastructure has been installed to address one of the most common and yet widely prevalent problems of a patchy network. 

Think of places such as business complexes, college campuses, movie theatres, and the likes, where the population can get high in density per area. Heavy traffic can congest the network operator's line, which can result in poor signal strength. To avoid such a scenario, these places generally resort to Distributed Antenna Systems to ensure a stable network coverage to a large number of visitors and residents there. 

While we mention some commercial places above, Distributed Antenna Systems are not only meant and employed by businesses only. Many individuals have installed these systems in their residential properties to enjoy seamless, uninterrupted network coverage across the place. 

After all, stable network coverage isn't just a requirement for professional purposes solely. We all know the dead zone in our houses where the network signal is non-existent, much like unicorns. 

In addition to heavy traffic, connectivity issues can arise due to resistance caused by the building materials in an establishment, too. Which makes this problem far more common than one may expect.

So, this is the time we learn about how the DAS functions. 

communication antena with an array of dishesHow Does a Cellular Distributed Antenna System Work?

Understanding the working mechanism behind DAS is no rocket science. There are two components at work here, the Signal source and Signal Distribution system

The process involves the Signal source catching network signals from a mobile carrier and then distributing the signal through a distribution system. The signal strength is amplified during the process, thus ensuring stable coverage throughout the premises of a building. 

The overall efficiency depends on the type of technology used. Also, the kind of DAS to be installed at a place depends on the location and type of building.

Types of Signal Sources

Like we mentioned earlier in the article, the DAS "distributes" already existing network signals to a series of antennas located at a distance from one another, which results in maximum area coverage. 

This means that the signal source determines the network coverage area and capacity. So, in other words, the efficiency of a DAS is more prominently decided by the quality of the signal source.

In all, there are three types of signal sources - 

  1. Off-Air Antennas

    Also known as Repeaters, the Off-Air Antennas are employed in outdoor settings. Most of the time, DAS uses rooftop antennas to receive signals from a cellular carrier.

  2. Base Transceiver Station (BTS)

    BTS is an expensive technology wherein the signal is generated by connecting to the network carrier through fiber optics. This type of signal source is suited for theaters, shopping malls, etc., where the network caters to vast numbers of users.

  3. Small Cells

    These were initially introduced as an alternative to distributed antenna systems. However, when employed as a signal source in DAS, these can also enhance the coverage area of a DAS. 

    Back view of a skilled businessman is having serious mobile phone conversation with investor about help in financing his company, while is standing near office window with view of tall skyscrapersTypes of Cellular DAS Signal Distribution Systems

    Moving ahead from the signal sources, we shift our attention to learning about the various signal distribution systems. There are four types of signal distribution systems: active, passive, hybrid, and digital DAS.

    1. Passive Distributed Antenna System

      Under this system, the signal coverage is enhanced inside a building by installing radio frequency components such as coaxial cable, splitters, taps, and couplers. In addition to being the easiest to maintain, the overall installation costs of Passive DAS are much less in comparison to active DAS and Hybrid DAS. However, on the downside of things, there are also losses in network coverage. These losses are proportional to the distance between the antenna and the source signal. The more the distance, the more are the losses.

    2. Active Distributed Antenna System

      Here in the Active DAS system, a signal is generated using the appropriate infrastructure. The analog radio frequency received from the signal source is converted to a digital signal further distributed through fiber-optic or Ethernet cables. A central unit stands responsible for converting the analog frequencies to digital signals. These digital signals are further fed into remote radio units (RRU's) through optical fiber.

    3. Das And Fiber Optics

      Since coaxial cables are replaced with ethernet cables or fiber-optic lines, this allows the DAS suited for more significant buildings. However, this is way more expensive than any other DAS system out there.

    4. Hybrid DAS

      basically borrows aspects from both active and passive DAS systems. Here, both coaxial cables and fiber-optic can be employed since antennas are separated from remote radio units (RRU's). These RRU's generate signals using fiber-optic but transmit the signal through coaxial cables. In most cases, Hybrid DAS is a cheaper option than active DAS.

    5. Digital Distributed Antenna System

      This is the latest type of DAS. The Digital Distributed Antenna system uses a baseband unit (BBU) which does not require any analog to digital frequency conversions. Digital DAS being a new development, it hasn't been adopted much widely yet. However, there is a contention that the installation might be cheaper and more straightforward than past technologies.