Two Spoke Forums banner
1 - 7 of 7 Posts

·
Premium Member
Joined
·
9,948 Posts
Discussion Starter · #1 ·
Do those Cell boosters work? We are installing what's called small cell technology in our systems.( https://www.ctia.org/news/what-is-a-small-cell)
They’re placing small cells in this area as well. All sounds great until two or three years from now when 6G is the latest and greatest. I love technology and worked in it for many years, but I often wonder just how much are we really ready to spend on something whose initial intent is to make a phone call?
 

·
Two skinny J's
Joined
·
21,751 Posts
They’re placing small cells in this area as well. All sounds great until two or three years from now when 6G is the latest and greatest. I love technology and worked in it for many years, but I often wonder just how much are we really ready to spend on something whose initial intent is to make a phone call?
5G is much like our download speeds. Same bandwidth just taking it from other traditional video bandwidth. Overall bandwidth the FCC allocates is pretty limited really for both cell operators and ISP's so everyone is compressing and using some REALLY dense QAM carriers. I've been around long enough now to see the changes from ASK, QPSK, and QAM. Starting with 16 QAM and we are now up to 256 QAM and looking qt 4096 QAM.

( Since QAM is usually square, some of these are rare—the most common forms are 16-QAM, 64-QAM and 256-QAM. By moving to a higher-order constellation, it is possible to transmit more bits per symbol. However, if the mean energy of the constellation is to remain the same (by way of making a fair comparison), the points must be closer together and are thus more susceptible to noise and other corruption; this results in a higher bit error rate and so higher-order QAM can deliver more data less reliably than lower-order QAM, for constant mean constellation energy. Using higher-order QAM without increasing the bit error rate requires a higher signal-to-noise ratio (SNR) by increasing signal energy, reducing noise, or both.)

That SNR is what I spend 95% of my time working one :(

The backhaul ( fiber backbone ) seems harder to keep up with really than deploying things like small cell...

Sorry for such a huge thread derailment :D
 

·
Two skinny J's
Joined
·
21,751 Posts
Interesting to me, looking at at the 5G architecture, they use OFDM ( Orthogonal frequency-division multiplexing (OFDM) is a method of digital signal modulation in which a single data stream is split across several separate narrowband channels at different frequencies to reduce interference and crosstalk.) which I did not realize.

We also use an OFDM carrier which goes back to what I was saying about taking traditional bandwidth from other things like video. In my world an old analog channel you saw on TV was 6Mhz wide with three components to each carrier.

Then came digital where we took one 6 MHz wide channel and shoved as many as 14 digital channels in that same bandwidth. So there are , in our system 158 EIA channels( or 1 gig bandwidth) - what you used to see as display channels on your TV so 158X14=2,212 possible digital channels. With HD it can not be compressed that much so there are roughy 4 HD channels per 6 MHz bandwidth. Then comes data and we currently have 32 bonded channels giving us the ability to give 1 gig download speeds over coax.

Now back to that OFDM carrier. They take 92 ( in our case ) Mhz worth of bandwidth to make one 'lane of data traffic" that just like the interstate has MANY different lanes with different speeds of traffic if you will. So if there's an "accident", traffic can still move and get around. It's REALLY cool stuff! It's really crazy to look at on a spectrum analyzer after years of looking at traditional bandwidth

What is OFDM?
OFDM is a form of multicarrier modulation. An OFDM signal consists of a number of closely spaced modulated carriers. When modulation of any form - voice, data, etc. is applied to a carrier, then sidebands spread out either side. It is necessary for a receiver to be able to receive the whole signal to be able to successfully demodulate the data. As a result when signals are transmitted close to one another they must be spaced so that the receiver can separate them using a filter and there must be a guard band between them. This is not the case with OFDM. Although the sidebands from each carrier overlap, they can still be received without the interference that might be expected because they are orthogonal to each another. This is achieved by having the carrier spacing equal to the reciprocal of the symbol period.
https://www.electronics-notes.com/a...sion-multiplexing-what-is-tutorial-basics.php

That's the engineer side of OFDM but you get the idea
 

·
Spin Spin Spin
Joined
·
4,194 Posts
I'm bucking the trend.......except to post this :(
 
1 - 7 of 7 Posts
Top