Most M2M applications today do not need the higher bandwidth of LTE and 3G as data rate of a few hundreds kbps could meet their needs. The LTE-M extension aims to fulfill the specific energy, spectrum, cost, efficiency constraints of M2M communications, whilst not hindering current LTE devices to operate normally on the LTE network.
LTE-M is expected to be released by 2017 achieving the following
- low power consumption and autonomy (i.e. up to five years for a device running on AA batteries),
- easy deployment
- low overall cost,
- excellent coverage.
LTE-M is likely to evolve further with discussion on including local mesh networking, very low cost modules (under $5), very long battery life ( even up to 10 years due to long sleep cycles) and low data rates with two-way (including full-duplex) communication.
LTE-M should co-exist with other proprietary networks supporting backwards compatibility to the previous LTE standards in the same spectrum. Today, for example the LTE EPC will require scaling and densification to support a huge number of additional LTE-M devices similar to the requirement of an increased subscriber number as LTE rollout progresses.
Thus, two different worlds need to coexist and share the same resources: first, the LTE core network with LTE users directly connected to the base station (eNodeB) through a LTE interface; second, the capillary (and heterogeneous) network with LTE-M or non LTE-M devices connected to a M2M Gateway via any air interface (LTE-M or not), while the M2M Gateway is interconnected to the LTE base station via a LTE-M interface. It might be also possible for LTE-M standalone devices (i.e., LTE-M devices which do not belong to any capillary network) to directly access the base station via a LTE-M connection. Some main features and research has been conducted in the EXALTED (EXpAnding LTE for Devices), an Integrating Project (IP) of the European Union’s Seventh Framework Programme (FP7) in the Information and Communication Technologies (ICT) by 2013.
However detailed security features and protocols need further research if need to be implemented. The security protocols should be applied at the application and data layer without compromising the energy efficiency of the device, inducing the minimal extra electrical consumption. Security should also be implemented at the SIM (embedded in the device) level, based on the SIM’s hardware and operating system, components that are progressing, enabling high security for a minimal economical cost and a minimal energy consumption.
Today LTE Category 4-6 supports broadband M2M services at speeds of 300 kbps, expecting LTE Category 0, by 2017 to reach data speeds at up to 1Mbps. LTE Category 0, Cat-0, has been already incorporated into the 3GPP standards, thus the possibility of using LTE as a main bearer for M2M communications has come a step nearer. Most 4G LTE mobile phones being used today are either category 3 or 4, and new developments are taking place for categories 6 or even 7.
Category 0 can perform really well under certain configuration and conditions. It is expected to reduce the complexity of an LTE modem relative to a single band Category 1 LTE module due to a modem’s simplicity. Today, Cat-0 operates with only one transmit / receive antenna; has a single RF chain; the peak data rate is 1Mbps in downlink and uplink. That can be achieved by using reduced transport block sizes; among the limitations is the fact that it supports only half duplex capability.
In addition, an M2M unit does not usually require a display or UI, thus the processing power is now compared to a typical smartphone. Low cost modems could be used that could be really cheap in a large scale, where each could cost like a GSM modem (~$10).
Today some interesting M2M applications among others include Energy Smart Metering and E-Health considered basic parts of tomorrow’s networked society. Many startup companies heavily involved into IoT and M2M, should be able to provide efficiency and innovation into a variety of low cost solutions.