As a quick recap, Part 1 of this thread covered the differences between traditional cellular handset needs compared to M2M needs:
- M2M Devices Are Different.
- M2M Applications Are Different.
- Network Coverage Needs Are Not The Same.
- Device Longevity.
Part 2 began the simplified history of cellular technologies:
- Early M2M Data Transmission Experiences.
- Introduction of Digital TDMA and CDMA.
- Digital Service Expanded And Changed.
- The AMPS Sunset Requirement.
Part 3 continued the simplified history:
- New Digital Data Transmission Methods.
- Higher Speed IP Data.
- Another Fundamental Technology Change ...
- Spectrum Needs Increased.
- GSM Radio Prices Drop.
Part 4 continued the simplified history:
- 3G Data Speeds Increase.
- 4G Cellular Introduced.
- Multiple Mode 3G/4G Radios.
- Higher Radio Costs.
- The Grand Unification(?)
This week, I will cover the main issue of 2G cellular longevity and why this has an impact on current and future M2M deployments.
2G Cellular Longevity
So, why is 2G Cellular longevity an issue? Particularly for M2M Applications?
Basically, it is an issue of spectrum efficiency.
These older 2G protocols are not as spectrum efficient as the newer 2.5G, 3G and 4G technologies. Simplifying a bit: for the same amount of bandwidth in a wireless spectrum, they do not transmit as much bits of data, or support as many simultaneous phone calls, or allow as much device management communication, etc. as newer technologies.
Thus, even though the large majority of M2M Devices can use 2G data technologies effectively (since they are much lower-usage in terms of bytes used for the applications), these technologies are not as useful or profitable for the cellular carriers and their ever-increasing requirement to support more data and more voice users simultaneously.
To support the explosive growth of wireless cellular, the cellular carriers must:
- Acquire more wireless spectrum.
- Convert their existing spectrum to more efficient protocols.
Since they are a scarce resource, the auction and sale of spectrum by the Federal Communications Commission (FCC) in the USA, has become a necessary means of regulating access in the various frequency bands that are available for use with cellular technologies.
And, wireless spectrum is extremely expensive to acquire! Multiple billions of dollarsparticularly if the spectrum is to have significant coverage everywhere in the country.
Yes, Carriers can and have acquired this expensive spectrum for their initial 3G and 4G services, and will continue to do so. However, it is easier, and equally important, for them to use their existing older spectrum more efficiently. Once the 3G and 4G services are deployed in the new spectrum and heavily used, they will convert the older 2G spectrum over timethe only question is When?
GSM and CDMA Protocols
In particular, 2G GSM data technologiesi.e., GPRS and EDGEuse the Time Domain Multiple Access (TDMA) protocols that are not as spectrum efficient as needed. In fact, these TDMA technologies are not as spectrum-efficient as the CDMA technologies that were deployed at around the same time.
Furthermore, since the new 3G/4G technologies for Carriers who provide 2G GSM service are entirely different protocols, that spectrum cannot be shared. Yes, these W-CDMA and UMTS handsets can operate in 2G mode in markets where only 2G GSM is available, but the converse is not trueGPRS Devices cannot operate in 3G or 4G mode in spectrum used for those new technologies.
On the other hand, there is less pressure to convert CDMA Devicesi.e., 1xRTT and EV-DOsince they are more spectrum efficient than GPRS and EDGE to begin with. The Carriers who deployed 1XRTT also deployed EV-DO (and later enhancements such as EV-DO Rev A.) everywhere in their footprint in the same spectrum and the ANSI-2000 CDMA Devices can co-exist more readily.
Business and Economic Pressure
In wireless spectrum where 2G GSM is deployed, there is economic and business pressure to convert that 2G usage to 3G, and 4G, technologies. We have seen this kind of pressure in the past, when 1G (Analog AMPS) service was converted to 2G Digital cellular service (CDMA, ANSI-136 TDMA and GSM).
As mentioned before though, in the AMPS to Digital transition, there was an AMPS Sunset period of 5 years (that ended in Feb 2008) enforced by the FCC.
However, a long sunset is unlikely to occur with 2G migrations to 3G and 4G, since consumers have become used to frequent handset changesenticed by newer features and capabilities in Smartphones!
In other words, the can only make a phone call capability of AMPS handsets, that allowed users not to change handsets unless they broke, is not much of a factor anymore.
Impact on M2M
The impact on M2M Devices using 2G GSM technologies is quite significant. Although the data performance today is sufficient for most of these applications, it is likely that 2G GSM service will be impacted within a few years as spectrum is converted to 3G and 4G technologies, particular in the dense urban areas where the business need for 3G/4G service is greatest.
Thus, the 2G GSM service quality and availability is likely to drop over the next few years and it is likely that GPRS service will no longer be available in most major cities by 2014 or 2015 and in the entire North American network by 2016, as the Carriers convert the existing 2G GSM spectrum to 3G and 4G services.
Carriers will also stop certifying and allowing any new M2M applications that use GPRS-only radio Modules (if they have not already done so!) in an effort to avoid more Devices on the network that require replacement when the 2G GSM technologies are removed.
The 2G/3G CDMA services are likely to continue for longer, since the CDMA Carriers are not under as much spectrum pressure as the GSM Carriers. However, in some CDMA Carriers, these 2G/3G spectrum deployments are also likely to be replaced with 4G services as consumer handsets are replaced (although Carriers who have enough spectrum for their 3G and 4G services are unlikely to do this rapidly).
Thus, it is likely that 1X and EV-DO service will be available through 2016 or 2017 (from Carriers such as Verizon, who need the spectrum for 4G LTE) and 2020 or longer (such as Sprint, who have sufficient spectrum to sustain support for ANSI-2000 CDMA while also deploying 4G LTE).
To Be Continued ...
Next time, I will wrap up this long series of posts with a review of how to make the right choice for M2M Applications.