4G LTE (long term evolution) is a mobile, typically data IP (internet protocol) only, network. It is incompatible with 2G and 3G networks and runs in separate wireless spectrum.
4G compatibility is a real issue due to the different LTE frequency bands in use around the world - and the absence to date of a true multi-band modem that can use more than about a dozen frequencies. To help alleviate this issue smartphones and tablets also have 3G (UMTS universal mobile telecommunications system) and 2G (GSM global system for mobile communications) modems for all voice and data fall back.
At present, there are more than 40 different 4G frequencies and the Wikipedia article, particularly the Deployment by region table, is most enlightening.
In Australia 4G frequencies include (Band/Frequency):
- 01 (2100, no deployments)
- 03 (1800, currently used for 2G by Telstra, Optus and Vodafone)
- 05 (850, no deployments)
- 07 (2600, Telstra, Optus and TPG - no deployments)
- 08 (900, Telstra)
- 26 (850, no deployments)
- 28 (700, Optus no deployments until analogue TV shut down)
- 33 (TDD 2100, no deployments)
- 40 (TDD 2300, NBN Co, Optus)
That is nine frequencies just to cover one country. The US has 21 frequencies, Latin America 16, Europe 14, Asia 19 (China has 5 of these) and Africa six.
To complicate this further LTE has eight UE (user equipment categories) ranging from 10.3 Mbit/s to 2,998.6Mbit/s theoretical download speed depending on the frequency, and aggregation of the spectrum to achieve that bandwidth. This is why you will see claimed speeds of one or more Gigabits per second.
To manage the LTE spectrum and stop issues like interference the world is divided into three ITU (international telecommunications union) regions:
- Region 1 comprises Europe, Africa, Middle East west of the Persian Gulf including Iraq, the former Soviet Union and Mongolia.
- Region 2 covers the Americas, Greenland and some of the eastern Pacific Islands.
- Region 3 contains most of non-former-Soviet-Union Asia, east of and including Iran, and most of Oceania.
Brief summary to date: 40+ different frequencies, three ITU regions, and at present no LTE modem chip can handle all.
But Apple 5S/5C claims it can manage “up to 13 LTE bands. That’s more than any other single model of smartphone. Which means even more iPhone users can experience fast download and upload speeds in more places around the world. So when you’re travelling, you can take advantage of ultrafast 4G LTE networks in more places.”
The model A1530 for carriers in Australia, Hong Kong, Korea, New Zealand, and Singapore (ITU region 3) covers 10 bands:
1 (2100 MHz)
2 (1900 MHz)
3 (1800 MHz)
5 (850 MHz)
7 (2600 MHz)
8 (900 MHz Telstra)
20 (DD 800)
38 (TD 2600)
39 (TD 1900)
40 (TD 2300 NBN, Optus)
To understand how the Apple 5S manages 13 LTE frequencies iFixit did a teardown:
- Qualcomm MDM9615M LTE (CAT3), DC-HSPA+, EV-DO Rev B, TD-SCMA (China Mobile), GSM, GPRS, EDGE, EGAL modem. This chip also provides the GPS/Glonass/Beidou, USB 2.0 and Wi-Fi hotspot capabilities.
- Qualcomm WTR1605L supports 5 x LTE (FDD and TDD), 5 x HSPA+, CDMA2K, WCDMA, TDSCDMA, 4 x EDGE/GPS/GSM transceiver (radio receiver and transmitter).
Samsung take a more conservative approach generally referring to up to six LTE Cat 3 bands for its new Galaxy Note 3 which we understand uses the same chipset as the Apple 5S above.
These are companion chips and are marketed by Qualcomm under the Gobi trademark. The chip is in common use in recent 4G smartphones and tablets made by LG, Samsung, ZTE, Huawei, Acer, HTC, Sony, BlackBerry and Nokia. Simply put, all devices using the same Qualcomm solution will have the same benefits and regional exclusions.
Summary to date: An impressive 2nd generation chip in use by many smartphone makers, but is not yet a World chip due to limitations of the number of ports (11 TX and 9 RX) it can utilise without firmware/antenna and other considerations. Apple could have used the third generation MDM9x25 chip for LTE Advanced Cat4 and even greater carrier coverage. There is an excellent, not too technical, slide series from Qualcomm here.
For those who have read to here you might ask why I researched this. In essence, a lot of smartphone companies are touting world phones and there is clearly no such thing. For Apple, perhaps the most aggressive world phone marketer, it has done an excellent job but even it requires five different models to cover the world. Note that the Qualcomm technical specs show the chip supports LTE Cat 3 only, not LTE Advanced which needs another chipset and antenna.
The article was also driven by reader comments on the new Samsung Galaxy Note 3 being region locked. The internet was full of a lot of poor journalism and obviously limited research. At the time of my reporting (27 September) I was the only Australian journalist to realise that it was the limitation of the Gobi chipset and why it affected 4G data access in different regions. It is purely a hardware limitation, not a Samsung ploy, and the reality is that the Gobi Chipset will work world-wide with many carriers, even if the maximum data speeds are only 2G or 3G.