M2M has been a notable topic in IEEE Globecom 2012, ranging from tutorials, industry fora and a dedicated workshop, featuring technical papers and a panel. Perhaps the most interesting discussions were circling around the question which of the wide area wireless technologies will prevail and transform itself into a dominant M2M solution.
2G (GSM/GPRS) is a very mature technology, long abandoned by the cutting-edge research in wireless communications, but the one that has won the trust of the end users due to its ubiquity, reliability, energy efficiency and low cost. Our groups will soon publish a paper where we show that GSM/GPRS, using only rather minor software updates of the protocol stack, can be converted into M2M-dedicated system, in which a single cell can support 10000 simultaneous low-data rate connections (e. g. to smart meters). But, although technologically possible, 2Gmay not survive as a dedicated M2M solution on a long run due to other factors. First, in many countries 2G is scheduled to be closed down and release the frequency. the plan is to refarm the spectrum for LTE. Second, even if 2G can keep the operating frequency, the operators will not be willing to maintain multiple technologies in their network, and in that case LTE is a clear winner.
But, if 2G can technologically support various M2M applications, perhaps it can re-emerge in another form. For example, operate on a single frequency, keeping a narrow band and being owned by a M2M service provider i. e. not necessarily by a company that is also a mobile LTE-based provider. A more radical thought could be to put 2G in a certain license-exempt spectrum and large M2M users (e. g. utilities) may have their own 2G cells; the license-exempt operation could be created in a way to facilitate interference management among 2G cells that have different owners and are in proximity where they can cause interference. How about porting 2G into a “cognitive M2M radio”, by re-engineering it through protocol (software) updates?
Another thing is the role of 3G. The M2M discussion is very often between 2G and 4G; however, Qualcomm presented their solution in which CDMA-based protocols are re-engineered to support different M2M requirements (latency, reduced access overhead, etc.). Considering the impact of Qualcomm, it is clear that 3G should also be considered in the M2M discussion.
Finally, an emerging technology in the M2M arena is the sub-GHz WiFi specified as IEEE 802.11ah, dedicated to sensor networks and smart metering, and scheduled for finalization in May 2015.