Monthly Archives: January 2011

http://www.pcworld.com/article/216669/iphone_vs_iphone_which_network_can_satisfy_your_need_for_speed.html

The results seem to indicate that AT&T is the faster network but that Verizon is more reliable. There were also some other interesting points brought up both in the article and in the comments posted by readers.

Alan Spicer liked one comment and added his own comments to that.

Posted Today, 03:29 PM
hazydave, on 14 January 2011 – 05:34 PM, said:

WHEN you can get a good 3G connection, AT&T has an inherently faster protocol. HSPA can run up to double the speed of EvDO, and minimally, the peaks are set for 3.6Mb/s down, versus 3.1Mb/s down on Verizon.

On the other hand, while AT&T has good 3G support in urban areas, less than 25% of AT&T’s cells (as of some report last year) are 3G at all. Every Verizon cell is 3G. So once you leave the big city, there’s another story entirely. A big part of this is the CDMA2000 technology… neither Verizon nor Sprint needed either all-new equipment or new spectrum to support EvDO 3G. AT&T and T-Mobile needed twice the usual spectrum (better still 4x) to support HSPA. T-Mobile didn’t even have this spectrum until 2006 (they bought newly opened spectrum at 1700MHz and 2100MHz).

Another non-city issue is frequency. Higher frequencies drop off faster in free air, and faster still through buildings and foliage. One reason Verizon and AT&T have better coverage in rural areas is this: they each have one of the two available slots at 850MHz, the old AMPS frequencies. Nearly everyone else, along with Verizon and AT&T, run at 1900MHz (this is in the USA, but it’s similar in Europe). But AT&T needs both 850MHz and 1900MHz at the same time for 3G, so they have 3G range problems compared to Verizon, once you’re out of the city.

This is somewhat fixed for 4G (real 4G, LTE in particular… HSPA+ is still a 3G technology, on the same frequencies as HSPA). Verizon and AT&T both have a good deal of spectrum in the 700MHz band, so they’ll outperform the others, once they get the suburbs and rural areas wired (the both claim “end of 2013″). Sprint has even more spectrum, but it’s at 2500MHz, which has serious problems though foliage. They’ll need more towers than AT&T or Verizon. T-Mobile has some LTE aspirations, but has not fully announced these yet, particularly, who’s spectrum they’re going to use.

Alan Spicer said:

@hazydave – That was the best post I have seen on this article and on many article comment posts. Instead of posting a he-said she-said finger-pointing barrage … you posted technical facts backing things up. In ham radio frequencies are often described by what wavelength “meters” band they are.

Examples 160 meters = 1.8 Mhz, 80 meters = 3.5 Mhz, 40 meters = 7 Mhz, all the way down to many of you have heard of 2 meters = 144 Mhz (we’re now in Very High or VHF), but not many have heard of 70 centimeters (Now in Ultra High or UHF). 33 Centimeters Amateur Radio Band is about half of that and now on the playing field for cellular communications ranges. It’s 902 Mhz.

I know from ham radio use that VHF went a lot further outdoors but didn’t penetrate buildings very well. UHF seemed to penetrate buildings better but didn’t have as much range as VHF. And it gets worse the higher you go up in frequencies. Hand cellular devices seem to have some of the same problems that hand held amateur radio transceivers have … because of being small devices with small antennas and having no guaranteed line-of-sight to the “tower”.

In amateur radio – “repeaters” are used to retransmit the signal to increase coverage. They also often use linking systems with multiple towers and base stations … almost “cellular” like in concept and purpose. But not as many towers as most cellular systems have.

1900 Mhz – (300 / F Mhz = ~ meters) = 0.1578947368421053 Meters. Or 15.7894 Centimeters. 15.7894 centimeters multiplied by 0.3937008 = 6.2 inches. Two interesting things about that. #1 to be a full wave antenna at 1900 Mhz your antenna has to be about 1/2 foot tall. It is NOT. #2 You see the size ~ 6.2 inches and can imagine the obstacles near that size that can absorb that radio wave. Things in your car, things in your house, things in your office. Those frequencies are not SUPPOSED to go that far. (Why WiFi is in 2.4Ghz? They don’t want it to go too far.) In fact the cellular provider likely has a down tilt on the antennas to keep them from interfering with the adjacent towers, etc.

This was just mean to show some information about radio waves and relate it to cellular frequencies. It was not meant to make a definitive answer as to any cellular carriers range or speed. Just some food for thought. Your hand, your arm, your body, could very easily block a cellular band signal.

73 de KA4UDX,

Alan Spicer

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Alan Spicer Marine Telecom