iPhone’s data throughput – Just you wait!

7 06 2007

The iPhone uses EDGE for its cellular data transmission. What’s up with that? AT&T already has a faster method called HSDPA, and that deployed in many areas, so why in the world didn’t Apple use it? Here are some answers.

Apple says EDGE is a good method, and of course the iPhone includes WiFi connectivity that is very fast, and WiFi is available in many places and there are more hotspots all the time. In fact, a lot of people already have WiFi in their homes, their friends homes, and theor schools.

Something we haven’t heard as of this writing are the actual speeds we can expect from the iPhone using any of these connections. We may get some surprises.

WiFi comes in several flavors. “B” can theoretically go up to 11Mbps, “G” up to 54Mbps, and N up to 200Mbps or more. Those speeds are never actually reached, however, and throughput depends on things like distance and the type of antennas used. The point is, it’s much faster than any cellular data transmission method deployed in the USA today.

EDGE can be theoretically as fast as 470Kbps. In reality, EDGE under AT&T in the real world yields perhaps 40Kbps. This is on a par with dialup speed, and that’s not saying much.

However, AT&T is said to be enhancing its EDGE service in time for the iPhone launch. We may be seeing throughput of 80Kbps on the iPhone im most places. That’s getting better! The iPhone might not be quite a pokey as everyone expects.

But what about HSPDA? It’s already out there on AT&T’s air. I believe AT&T is running it at 1.8Mbps. Now we are getting somewhere! It’s ten times faster than EDGE, so why isn’t this technology in the iPhone?

I think there are two reasons. One is that current chips that implement this in mobile phones are relative power hogs. The iPhone is already sniffing for WiFi and Bluetooth signals in addition to running a hefty CPU, a big chunk of memory, and a large bright display. It’s battery must already be stressed.

Here’s the thing. The iPhone version 2 is going to be a killer! Much lower power chips for HSDPA are already in the works. And AT&T is said to be cranking up their deployment of HSDPA to the maximum specified throughput of 14.4Mbps. That’s Ethernet speed! Imagine this kind of Internet connectivity on a phone. It is going to blow the doors off other US carriers, for example Verizon’s EVDO runs at 2.4Mbps.

I think this is a major reason Apple went with AT&T. Looking ahead, they saw AT&T is going to deploy, and fairly quickly, a very fast 3G data service. They also knew appropriate chips will be available that will let a near-future version of iPhone take full advantage of this system without killing the batteries. Steve Jobs said in his January keynote that 3G would be coming, and I believe this is what is planned.

So. I think the first iPhone will run EDGE twice as fast as people are thinking. And when a 3G iPhone does come, the over the air data throughput is going to knock people’s socks off! Let’s see what happens!

(I hope I have all these numbers right, if not, please leave a comment.)




3 responses

7 06 2007

First , it’s HSDPA — High Speed Digital Packet Access. Not HSPDA.

Second, I’m a little lost when you say 1.8Mbps (1800Kbps) is 10 times faster than 473Kbps. I see it as being 3.8x faster. We could even round up to 4x. That’s still a far sight from 10x.

Finally, you point out that the actual speed is about 40Kbps (a little slower tha dial-up). If we take the same ratios 40/473Kbps, the actual speed of the 1.8Mbps will end up at 152Kbps. I’m not sure I’d want to download music at that speed…

But, I agree. 14.4Mbps definitely sounds promising! That’s one reason I’m not going out and buying an iPhone 1. I’ll wait for HSDPA, thanks…

7 06 2007
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25 06 2007

There is a large disparity between the rated capacity of a transmission technology and the actual throughput. Much of that disparity is legitimate overhead used to package the data and much of it is hype. Fist of all, transmission methods are rated in bits per second while files are usually listed in bytes. An actual throughout of 152Kbps is not all that bad and rivals most cable modems and DSL. (I am getting a pretty consistent 76Kbps on a DSL line.)

Here, I think is the real reason AT&T does not want the iPhone to start off with 3G+. They have spent millions getting their DSL infrastructure in place. If they introduce an easy to use phone with equal or better throughput, their DSL cash-cow is going to dry up pretty quickly.

It is rarely a question of technology, but rather a question of making the most money from the technology.

– j

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