5 years ago, when LTE was just about to hit the real world, I wrote a blog post about the LTE band challenge. Even at the time, 3GPP defined more bands for LTE use that one could count with two hands and even more have been added since. It was quite worrying 5 years ago when the state of the art in mobile devices was to support 4 GSM bands and 2 UMTS bands. Fortunately the situation has much improved since then.
Things already started to improve a year later in 2011 when I bought a mobile device that supported 5 UMTS bands and roaming to the US became a reality. At the time experts told me that we might see one additional band per year to be added to mobile devices as a result of improved front-end designs that counter the negative side effects of adding more frequencies to the RF part. According to this we should have devices today that support 10 bands.
Much to my surprise, some magic has happened as some very popular devices support 23 bands simultaneously today! Yes, you’ve read correctly, 23 simultaneous bands! Have a look at the web page linked here for the details. 23 bands and FDD and TD-LTE support means that such devices can be used around the globe in pretty much every country and I have done so in the past year on several occasions in Europe, the US and Asia, including China with their TD-LTE on bands 38 to 41.
O.k. so the experts have erred on the lower side of the equation. Which makes me really wonder how things will evolve in the next few years. It’s likely that it won’t stop here, with many more bands that will shortly be used that are not among the 23 that are supported by the leader of the pack today. In Europe, the 700 MHz range assigned to LTE as part of the Digital Dividend II spectrum auctions in several EU countries as well as band 32 for the 1400 MHz downlink-only band are likely to be used in the not too distant future. If one can jump from 5 to 23 bands in just 4 years it seems it shouldn’t be too much of a problem to aim for even more and do so in an economical way.
And for some more background reading here’s a post from last year on the RF parts that are in front of the baseband. Enjoy.