Multi-carrier DAS
A multi-carrier DAS can process signals from multiple radios with multiple frequencies. So for example, if a multi-carrier DAS is built to work with AT&T, Sprint, T-Mobile and Verizon - it will work with phones from all of those operators.
But let me step back and start with radios.
Car radio
I am sure all of you have seen radios. Most of you have also tuned them to go to your favorite station. If you are ‘tuning’ into your favorite channel on a radio inside your car, you are essentially turning the knob to go to a certain frequency.
Specific type of radios are at the core of all signal sources. At a very basic level, radios used for wireless signal sources are similar to your car radio, except:
Radios for signal sources can both receive and transmit signals (but radios in our cars can only receive signals).
Radios we use in the wireless industry comes pre-tuned – which means they are ‘pre-tuned’ to only work for 700 band, or 1900 band; we just have to make sure that we are getting the right radios with the right band.
So what are the right bands for signal sources? Let me reframe that question by asking, “What are the common RF signal source frequency bands in the U.S.?”
The big operators in U.S. use 700, 800, 850, 1900, 2100, 2500 mega hertz. Here is a table that shows the major wireless service providers of U.S., and frequencies and technology they use.
One clarification here, as you can see in the table more than 1 carrier can use same band. For example, 1900 band is shared by all 4 carriers. This does not mean that all the carriers are using the same channels or frequencies within 1900 band. They all have distinct channels or frequencies within the 1900 band. If they are not distinct and separate from each other we would have interference problems – and that’s a bad thing.
As far as technologies, LTE, UMTS, CDMA – are all acronyms for wireless technologies used by the carriers. These technologies tell the engineers, basically, how the signals will be processed. LTE is common among all carriers. Although, most of the carriers are using LTE to transmit and receive data, all carriers have moved or moving to Voice over LTE or VOLTE and use LTE for carrying voice.
Now back to Multi-carrier DAS. As I mentioned in the beginning, a multi-carrier DAS can process signals from multiple radios with multiple frequencies.
For example, let’s look at a block diagram of a multi-carrier DAS below. We can share this DAS with AT&T, Sprint, T-Mobile, Verizon. That means operators can share the coaxial cable, fiber, couplers, antennas, etc. – basically the DAS infrastructure.
A multi-carrier DAS can process signals from multiple radios with multiple frequencies.
It’s common in the industry, to call a multi-carrier DAS - a neutral host DAS. That’s really a misnomer! Neutral Host means that DAS is ‘neutral’ to signal, and can take any signal – however, that’s not the case in majority of carrier grade DAS. So I like to call these multi-carrier DAS.
Some multi-carrier DAS can also carry public-safety signals (SOLiD DAS platform for example). We will have a separate post dedicated to public safety DAS, but just know that Public Safety is also often part of the multi-carrier DAS.
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