My U770 reports my 3G technology as being HRPD, however when my tower went down or was having issues I noticed that I was picking up a faint signal and reporting the technology being eHRPD. So I did some researching and found a very informative post about eHRPD, on the S4GRU forums: Here is what user "S4GRU Administrator" has to say:
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In all seriousness, here is a comprehensive understanding of eHRPD:
For the most part, eHRPD is EVDO-A. Both are 3G CDMA technology. EVDO is a High Rate Packet Data technology, and eHRPD is Evolved High Rate Packet Data. It is essentially the same exact technology, except eHRPD data is routed through the LTE core instead of the MSC (switch) so it can maintain the same IP address as LTE. This allows for data hand offs between LTE and 3G. Only LTE devices are capable of eHRPD connections.
eHRPD and EVDO-A are broadcast from the same tower on the same channel using the same technology and the same backhaul. It is one signal, not two different signals. However, if your device is in CDMA only mode (or you have a non-LTE device), your data from your device goes from the site through backhaul to a Sprint MSC switching center is processed and dumped out onto the internet backbone.
If your device is in CDMA/LTE mode and your site has been upgraded to eHRPD, when your device data gets to the site, it goes through the backhaul to a 4G LTE core instead of the MSC. There it is processed and dumped out onto the internet backbone.
So, the only difference in performance between eHRPD and EVDO-A on the same site occurs at the MSC vs. the LTE core. Everything else is pretty much identical between the two. Each site in the Sprint network is tied to a very specific MSC for 1x voice and EVDO data. Sprint has dozens of MSC's scattered around the country. When that MSC experiences problems or has a logjam, it affects all the sites connected to it. And EVDO can slow down (although this is not the big culprit in Sprint 3G deterioration).
In contrast to how the MSC's handle 1x and 3G EVDO data, 3G eHRPD and 4G LTE data are processed through 4G cores. Unlike MSC, sites are not limited to only one core. Sprint is setting up their 4G LTE cores to be dynamic. So if one core is too busy, data can be routed to a different under burdened core.
Performance between EVDO-A and eHRPD should be very similar when on the same channel from the same exact site. The most common difference is that eHRPD will often have faster ping times. And a MSC is more likely to bottleneck than an LTE core, so at peak times EVDO may be slightly slower than eHRPD (when all things are the same).
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Source - »
s4gru.com/index.php?/top ··· s-ehrpd/For the basic run down, EVDO is run through a 4G Core with eHRPD, and this is a bit faster, and can decrease ping times. Also, this means 4G Cores have been added in my area, and must mean 4G is on its way.
