The topic was really usefull

"International standard of 3.5 GHz spectrum"? Not according to WRC07!!

That's the complete answer i was googling for.
Thanks.

good article ... any graph showing curve through spectrum vs bandwidth !?!

Graph is required ....

Dear All this is very good learning topics for all. I am googling for IPtv Frequency. Thanks

Thanks for publishing this article, it is very useful. However, there is a note that I don´t agree with.

"A 900 MHz license free radio will travel farther and penetrate ..... But it can carry much less bandwidth than a 2.4 GHz signal which cannot penetrate any tree cover whatsoever, but can deliver a lot more data"

Why 900 MHz spectrum carries much less bandwidth? In my opinion it can carry as much as any other band, such as 2.4GHz depending on the technology used. Each technology uses different bandwidths for its individual carriers. Now, in regards to data throughput (sometimes mixed with bandwidths), amount of bandwidths will depend on RF conditions which is independent from frequency band.

Please clarify, thanks.

Alberto

Remember the Nyquist Theory. Lower the frequency lower the bandwith. Using the same modulation schemes, the higher freq can carry more data than the lowest.
The higher frequency travels further and penetrates more obstacles than a higher frequency.
This is basic RF.

" The higher frequency travels further and penetrates more obstacles than a higher frequency.
This is basic RF."

where is the comparison? both are "higher frequency"

Wimax,
.
The original thought was meant to express --I will think-- that lower frequencies tend to pass through some objects better than will higher frequencies, and that is essentially a true statement.
.
The physical character of the object largely determines whether transmission through the object will take place.
.
Of course, there is ~also~ that matter of the actual 'power level' of the signal being expressed upon the surface of object.
.
Largely speaking though, the greater the ability of the intervening object to conduct an electrical charge --of any particular power-- along its SURFACE, the lesser will be the likelihood of a particular signal passing through it.
.
THINK: Waveguide surfaces.
.
If in the process of conducting an electrical charge (RF signal in this case), there exists ~other~ qualities besides the purely resistive, i.e., reactive (capacitive and/or inductive) such as to cancel (absorb) or reflect the impinging electrical charge, then that impedance serves to resist further transmissibility through the object.
.
In the main then --for conductive surfaces-- the impinging electrical charge is largely reflected and/or absorbed (converted into heat) relative to the power level of the impinging charge and the ability of the object to sustain the level of power exerted upon it.
.

The higher frequency travels further and penetrates more obstacles than a higher frequency.
this should be correctly stated as
"the lower frequency travels further and penetrates more obstacles than a higher frequency."

Alberto,
.
How a higher frequency may carry more information than a lower frequency signal is aptly illustrated by remembering this: A 10Hz signal may carry 10 times more information than would a 1Hz signal by dint of the fact that it is ten times faster.
.
If each cycle of a waveform is able to contain 1 bit of information, then 10 cycles will carry 10 times more information than would the 1 cycle waveform in that SAME SPAN of time.
.
Remember: You're looking at TIME and the amount of data transferred in that SPAN of time.
.
Ergo, a 2.4Gig signal will carry far more information than would 900Mhz signal, and that's working with just 1 bit per cycle.
.
If you go with frequency modulation, the quantity increases even further. Study up a little bit on information theory when you get a chance.

Thanks a lot for the quality of the input and for your time. I have three comments.
I agree with the explanation about the Nyquist theorem and the great example of the 10Hz signal carrying 10 times more info than a 1Hz signal. However in mobile communication systems, each technology may have a different “bandwidth“ for its carrier signal. For example, a TDMA is 30 KHz wide, a GSM carrier is 200KHz wide, a CDMA carrier is 1.25MHz wide, a WCDMA carrier is 5 MHz wide and a WiMax or LTE signals can be of variable bandwidth reaching up to 20MHz for each carrier. This is regardless of the frequency used to be transmitted (800MHz, 1800 MHz, 2.1GHz, 2.3 GHz, etc). Thus, I was having trouble reading the statement “A 900 MHz license free radio …….can carry much less bandwidth than a 2.4GHz signal…..” For example a CDMA carrier (1.25 MHZ of bandwidth) transmitted at 1900 MHz can carry much more bandwidth that a same CDMA carrier at 850 MHz?
Now, in regards to the penetration, I agree with the argument about the type of objects being more or less subject to penetration by a particular RF signal. However, and most importantly, in free space with no obstacles, an RF signal transmitted at higher frequencies will suffer stronger attenuation than those of lower frequency.
About the power levels, in mobile systems, remember that terminals are limited to power levels In lieu of health issues caused by over exposure to higher level of RF. Therefore higher frequency systems are more costly because more stations are needed to provide for the right coverage.

Thanks again.

Alberto

Alberto,
.
As likely you know, bandwidth is a technical specification more than it is a physical characteristic, i.e., the FCC determines the max bandwidth a carrier might produce in order to keep from interfering with other adjacent services.
.
Your question:
-----
For example a CDMA carrier (1.25 MHZ of bandwidth) transmitted at 1900 MHz can carry much more bandwidth that a same CDMA carrier at 850 MHz?
-----
.
Let's reframe you question with: Throughput. The American Heritage English Dictionary defines that term as: "Output or production, as of a computer program, over a period of time."
.
By dint of the higher frequency there is greater data throughput.
.
Some people rather erroneously speak of 'bandwidth' as being the same as throughput.
.
In the entirely esoteric sense of things, they have come to be mistakenly synonymous, and that's where you've taken the wrong fork in the road!
.
Even if both frequencies have the =same= bandwidth, the higher frequency will carry more information. Remember: You're working with time here, and not just physical bandwidth.
.
Ergo, what we are ~really~ discussing here is throughput: How much information is transmitted in a unit period of time.
.
Increased bandwidth merely allows for a greater amount of information to pass over what's possible with a fixed minimal bandwidth at any particular frequency.
.
When you're talking about just ONE frequency, then bandwidth becomes 'everything.'
.
But when you're talking about ~several~ frequencies, then the higher the frequency the greater the data throughput.
.
Now, your comment:
-----
However, and most importantly, in free space with no obstacles, an RF signal transmitted at higher frequencies will suffer stronger attenuation than those of lower frequency.
-----
That's not exactly true. When you say 'free space,' you --of necessity-- declare that there are =no= intervening objects with which a signal might interact.
.
If you take two signals of widely separated frequencies and of exactly the same power levels, and transmit them into space, they will travel for as long as they do not encounter an impeding object.
.
Now, if you mean to declare 'free space' to mean the atmosphere of Earth, then you'll have a point, inasmuch as the molecules of the constituent gasses will have an attenuating effect on those signals.
.
Finally, you remark:
-----
About the power levels, in mobile systems, remember that terminals are limited to power levels In lieu of health issues caused by over exposure to higher level of RF. Therefore higher frequency systems are more costly because more stations are needed to provide for the right coverage.
-----
I don't know that they would be more costly in the long term, because with increases in knowledge, and production capabilities, the initial costs are spread out over time and the size of a production run.
.
You really must keep in mind that thought about 'the economies of scale.'
.
The more you make of a thing, the less it will cost to produce, and the lower the price as a result.
.
THINK: If you have only an acre of land to farm, then it will cost 'X' to purchase the seeds, the fertilizer, the fuel needed to run the machinery for tilling, watering, etc.
.
'X' will be the investment cost.
.
At the end of the day, what you extract as a useful product will cost 'X' for your customers, PLUS what you will need to transport that to market AND support yourself for next year's planting.
.
Therefore, the SIZE of your production run determines what the price will be at the marketplace.
.
A small production run will cost lots more than a large production run simply for the fact that the 'X' costs are distributed across a LARGER production quantity instead of a SMALL production quantity.
.
Now then, higher frequency units require smaller parts, are more easily adapted to automated production lines, and actually result in a higher yield than would larger, more bulky units using larger parts.
.
What that translates to is just this: Because they will be inexpensive, small, and require less power, they will become ubiquitous -- they will essentially be everywhere.
.
THINK: The IBM 360 mainframe versus the Home PC of today.

I Tend to disagree with, the higher frequency, the greater troughput, compared to a lower frequency.

as you yourself stated "Increased bandwidth merely allows for a greater amount of information to pass over ".

1. If a 900 MHz carrier would have a bandwidth of say, 5 MHz. (hypothetical). compared with a 5 Ghz. carrier with a 5 MHz. bandwidth, both will have the same maximum troughput, considering that both are equal in all aspect.

thus carrier frequency has nothing to do with troughput, it is the bandwidth that determines the carrier troughput.

I am speaking when all other consideration like access, multiplexing, compression and others are all the same for both, with the same bandwidth the throughput is the same, irregardless of carrier frequency band.

one possible point of confussion to this line of understanding is that most higher frequencies carries a much larger bandwidth compared to their lower frequency counter part.

an example of this is that a 10% bandwidth in 900 Mhz is a lot smaller than a 10% bandwidth in say 5 GHz.

2. "FREE SPACE LOSS" is in my opinion Free space propagation on the surface of the earth, since wimax was not designed for space operation, I generaly assume it is on the surface of the earth.

3. Lower frequencies suffer less free space attenuation, compared with some higher frequencies, this constitutes to a larger coverage service area, for services using lower frequencies, however this has a reverse impact on troughput for each subscriber, Ie; The further a terminal from a base station the lesser data rate it would get, compared to a terminal that is closer to the base station, and the same is true to the higher number of subscribers the lesser datarate will be availabe for each.

As a bottom line it is always a balance of both.