Thursday, June 10, 2010

Relationship between frequency & capacity, in-building penetration & cell size


Interesting picture from a presentation by Prof Ed Candy Hutchison Whampoa Europe & 3 Group Europe in the LTE World Summit.
Posted by Zahid Ghadialy at 7:28 AM
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10 comments:

Anonymous said...

I don't understand this, provided that you can have the same bandwidth, why should capacity change?

June 10, 2010 at 9:20 AM
Zahid Ghadialy said...

The higher the frequency, the lower the propagation of waves assuming constant power. This means smaller cell size.

See also: http://3g4g.blogspot.com/2009/07/800-or-2600mhz-frequency-impact-on.html

June 10, 2010 at 10:16 AM
Anonymous said...

Oh yes, the coverage part is clear, my comment was about capacity ;-)

June 10, 2010 at 10:24 AM
Zahid Ghadialy said...

Doh! Of course the capacity will remain the same. The capacity part is not correct on the picture.

June 10, 2010 at 10:34 AM
Anonymous said...

Actually, when cell radius decreases, there will be more sites in the network which means more capacity.

June 10, 2010 at 3:00 PM
Anonymous said...

Yes, that's true, but then the comparison is not quite fair, we need a third axis then with the variable $$$ :-)

Same bandwidth, Same money, Higher frecuency => less coverage, same capacity.

June 10, 2010 at 3:52 PM
Sathees said...

Hi, Thanks for the Picture !

If we have 10 MHz bandwidth in 900Mhz and 10MHz in 2.3GHz, then capacity of 900MHz and 2.3GHz are the same? Please clarify

June 11, 2010 at 6:09 AM
Zahid Ghadialy said...

Yes, the cell capacity should remain the same but as someone rightly pointed out above, the radius of the cell will decrease and hence you will need more cells for the same area of coverage. This would in turn increase the network capacity.

June 11, 2010 at 11:57 AM
Sathees said...

Hi, Thanks.
900 Mhz = 900000 cycles per second,
2300Mhz = 2300000 cycles per second

that means 2.3GHz can carry more data in given time than 900MHz. So according to this, 2.3GHz will get more data rate than lower band..isn't it?

June 14, 2010 at 9:23 AM
Zahid Ghadialy said...

Hi Sathees, The frequencies we are talking about is the Modulating frequency. The data remains the same regardless of the frequency. The modulation translates the data into the frequency to be transmitted and at the receiver side the demodulator receives the sata at the higher frequency and translates it back onto the lower frequency.

An RF engineer should be able to better explain what I have said.

June 14, 2010 at 11:08 AM

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