M2M Migration from 2G to 3G
Published 03 September 2014 by Trevor O'Grady
We’ve been helping quite a few customers recently with migration from 2G (mostly GPRS) to 3G/4G or at least have a option for supporting 3G/4G at some point. For the purposes of this article I’ll just simply refer to 3G here and not all the various flavours of UMTS, HSPA, CDMA200 and LTE etc. so you might have to forgive me for being over simple.
The reasons our customers have for change are many but the primary driver we see is the ability to support regions where 2G is, or soon will be, a non option. The extra speed is almost never the reason, most of the M2M systems we develop are all about small amounts of data, so there is no real performance advantage for our customers when moving from GPRS to 3G.
GPRS is already ‘challenging’ in Australia
If you’re a player in M2M then unless you’ve been living under a rock for the last few years you have probably heard about AT&T planning to turn off their 2G network soon. Australia is another example, the major player there is Telstra and it will close its 2G network in 2016 and will reuse the spectrum for 4G. Telstra’s 3G network, called NextG, is what they are pushing customers to. GPRS is already ‘challenging’ in Australia. Any M2M product wanting to make progress there needs to be 3G or above. There are other similar examples elsewhere. The reasons for networks to abandon 2G and GPRS is fairly obvious in that, compared to handset sales, M2M is still small fry - even if it is showing encouraging signs of growth; When was the last time you saw a GPRS only phone handset? The networks’ trend is towards 3G and 4G and so it is easier if the spectrum and other resources can be reused. Having said that here in the UK there hasn’t been much scaremongering about GPRS disappearing in the short to medium term.
This all reminds me of maybe 8 - 10 years ago when there was an increasing need to migrate from GSM to GPRS. That was maybe a more disruptive migration as usually this meant customers getting their heads round using the Internet to transfer data for the first time as GPRS is IP (Internet Protocol) based and most GSM telemetry back then was plain old GSM dial up (CSD). This was actually a good opportunity for the company I worked for at the time as we provided systems that used the Internet so potential customers that previously told us to “go away with your fancy Internet stuff” were now asking us to “please provide a solution for sending my data via GPRS” to which the answer was to send the data over IP to a server on the Internet – conveniently for us but there are of course other good reasons to use an IP network like the the Internet over point to point that I won’t go into here. The migration from 2G to 3G is less troublesome in the sense that an IP based system will work much the same on 3G. But what is often different of course is the modem. Changing modem from 2G to 3G/4G brings some challenges. The cost of a 3G modem is often 150% more than for the GPRS equivalent! No I didn’t mistakenly add a zero. I keep hearing that the costs will go down once the volume comes (which is true) but that does not lessen the pain for people that need to supply product now. This is a major issue which is delaying many making the change.
Another issue is that the power consumption on 3G is substantially more than 2G. Most of our projects are battery powered so power is a big issue. Having said that because the data loads are so low we are typically not on the network very long so the power used elsewhere often swamps the power used by the modem. However the increased current required by a 3G modem, especially during transmission, means that it is often necessary to modify or redesign the modem power supply and this is not an area to take chances with, I’ve seen far too many inadequate modem power supply designs in my time. So with a change in modem footprint and redesign of the power supply this is not a small tweak by any means. Most use this opportunity to change other things e.g. add features, redesign for cost reduction, revamp etc.
Many of the modem manufactures provide a 3G option in the same footprint as their existing 2G offerings but as most modems these days are soldered directly onto the PCB this means committing to the appropriate modem option at build time rather than being able to fit a region specific modem option nearer to dispatch time. There is of course the option of using a modem with a connector interface but I’m not a fan of modems fitted to PCBs with high density connectors, I’ve seen issues with this in terms of mechanical strength and vibration weaknesses as well as being a more expensive option (more expensive modem, extra connectors required, longer build time). Choosing a modem might be a good topic for another blog.
Everyone would like the network connection method they choose to be future proof and never have to change to the next thing but this is never going to be possible while we are using a cellular/mobile network, especially when it is not primarily dedicated to M2M. All you can do is try and ensure the modem you choose will be around for a reasonable time period and has a reasonable upgrade road map, ideally on a standardised footprint. After that you just have to factor into the business model that change will be a necessary part of the product lifecycle. There are other non-cellular approaches but that’s maybe for another blog.