Posts Tagged ‘HSDPA’

Understanding Data Coverage Notation

Thursday, December 23rd, 2010

Most of us with a smart phone are used to checking our data coverage by looking for “3G” at the top of our devices. Those without a smart phone might look for an E, if they are AT&T customers. I took a very long train ride over the last two days and managed to see a wide spectrum of data coverage. One I had to look up, so I thought it would be good to cover the spectrum. This is primarily a lesson on GSM devices, though there is some overlap.

Having finally debranded my AT&T phone, I now expect to see an “H” to tell me whether I have a data connection. The H is for HSDPA, which is generally understood as 3.5G. It is what AT&T has been working on in 2010, in preparation for LTE in 2011. When an LTE connection gets congested, the phone will fall back on HSDPA which will still be fast, thus making a more pleasant data experience. At least that’s the plan. So far I have noticed a lot of improvement in my connection speed. Part of it is finally having Eclair on my Xperia X10, but the HSDPA is certainly a factor.

Next is the more familiar 3G. This doesn’t require as much of an explanation. Prior to LTE, WiMax, and HSDPA, it was the fastest thing around. Most fast phones are currently 3G capable.

For AT&T customers, the next fastest connection is Edge. You’ll see this represented by an “E”. My Sony Ericsson Walkman phone was only capable of Edge, so that used to be a good thing for me to find on my phone. Now that H is my fastest connection, the E is dreaded. It is however better than the one I found today.

As my phone went in and out of AT&T’s coverage area, roaming here and there, I noticed a new symbol. I saw a “G” at the top of my phone. G is 2G, or really slow. It is short for GPRS. Considering the fact I spent most of the last two days on Edge, I assumed the G was bad, and I was right.

Here are the options for comparison:

Symbol Connection Speed
G GPRS 56 Kbits/second
E Edge 236 Kbits/second
3G UMTS 384 Kbits/second
H HSDPA 7.2 Mbits/second to 14.4 Mbits/second

So there you have it, in a very limited nutshell. You can see why I am happy seeing an H every day now. I don’t get anywhere near the 7 Mbits/second, but it is noticeably faster than 3G. I am assuming as the network matures it will reach its potential. Spending most of the last two days between no coverage or G and E, I have been largely disconnected. That’ll teach me to take a train through the middle of nowhere. It would be nice if AT&T really did cover 97% of Americans as it claims. I would have been far less frustrated.