The importance of LTE (Long Term Evolution) is not widely understood and this is particularly true for M2M communications. For example, LTE (aka 4G) has been marketed by mobile network operators (MNOs) as a high-speed / low-latency service, which it is, but the network has far more bandwidth than most machine-to-machine (M2M) applications need. However, these new networks deploy OFDM (orthogonal frequency-division multiplexing), a method of digital modulation in which a signal is split into several narrow band channels having different frequencies. This allows bandwidth to be assigned in a very flexible way, and in turn, that allows operators to offer cost-effective, low-bit rate services for use in M2M solutions.
In addition, LTE networks are significantly more efficient than those of earlier generations. They are based on a simplified, flat, all-IP architecture having open interfaces and an evolved packet core. This will result in a global infrastructure that can accommodate up to 10 times more traffic and that will facilitate the deployment of tens of billions of smart devices that are predicted for the connected world.
In a nutshell, LTE is distinguished from earlier networks by a groundbreaking combination of efficiency and flexibility. This article will examine the ground that is being broken and the benefits that result, but first we need to define the network terminology.
LTE is marketed as 4G: marketed that way because technically it’s 3.9G. LTE-Advanced (LTE-A) is the real 4G because it meets the ITU’s requirements for fourth-generation wireless systems. These requirements are known as IMT-Advanced and the performance targets they set include a peak download traffic data rate of 1 Gbps and an uplink rate of 500 Mbps. LTE Release 8 already supports rates of up to 300 Mbps in the downlink and 75 Mbps in the uplink.
Machina Research indicates that over 99% of the wireless M2M connections in 2013 employed 2G and 3G networks, the split was 60% / 40% but this figure is set to change dramatically. By 2018 2G will fall to 20%, 3G to 50% and 4G comes in at 30%. By 2022 it will rise to almost 70%, the majority of the traffic coming from cost-effective low-bit rate services that will serve the Connected World
In addition, a key feature of LTE technology is the efficient use of spectrum, a precious commodity, and in time this will translate into lower operating costs for MNOs. That will result in lower tariffs for users because of operators will need to monetize their investment, Traffic levels will soar as we enter the IoT era.
When market pull coincides with technology push the result is an inflection point — a turning point in the economy after which significant changes take place. Andy Grove, Intel’s co-founder, described a strategic inflection point as “an event that changes the way we think and act.”
LTE is the first network technology that can comfortably accommodate demanding applications like real-time video surveillance and at the same time provide cost-effective connectivity for low-speed applications. Therefore although these apps have widely different performance requirements, the market will be able to build a wide-ranging ecosystem on a single, wide area communication technology. Moreover, LTE has or will have everything going for it: superior performance; ubiquitous connectivity; scalability (enabled by support for IPv6); low cost per bit, delivery of whatever QoS customers require, and longevity (MNOs are or will be retiring older network types). The only significant issue is the operating band, which varies from country to country. However, 1800 MHz is the best-supported frequency, with more terminals able to operate in this band than in any other.
An overlooked feature is the fact that LTE networks will fallback to an earlier generation network if the attached device cannot detect a 4G signal. This will ensure that the automotive on-board platforms that deliver a simultaneous array of entertainment, traffic, navigation, maintenance and safety features will continue to provide services when there is no LTE coverage.
Companies that recognize that LTE technology will be the global standard cannot rely on the longevity of earlier networks. We know that 2G is being decommissioned in the U.S. and other countries will follow. Moreover companies whose solutions have long life times, ten years or more in key segments like automotive, cannot rely on 3G since it too might reach decommissioning status within this timeframe. In India operatiors are already setting infrastructure to roll out 4G network. Infact one can say that countries like India would leap frog to 4G virtually bypassing 3G. The same would be true for many developing and emerging economies.
Mitigating the risk of betting on an established cellular technology makes sense, but LTE modules cost more than 2G and 3G modules. That’s inevitable as LTE is a relatively new development and the technology is more complex, e.g. support is needed for the different channel bandwidths. In addition, manufacturing volumes are low at this early stage.
Companies will therefore need to balance an initial higher bill of materials cost against potentially lower operating costs and also factor in the lifetime of the solution in order to determine the total cost of ownership (TCO). When decisions are made based solely on purchase price, then there may be a need to reinvest in application development and support services in order to upgrade devices in order to match sales growth.
LTE employs large bandwidths in order to deliver high-speed, low-latency traffic. That was the primary objective and at the design stage the network equipment providers would not have foreseen the potential of relatively low speed M2M communications on an LTE network. This means that high-speed performance was optimized; low speed was not. There are no intrinsic issues; OFDM has the requisite functionality. The air interface can be split into several narrow band channels having different frequencies. Release 8 permits channel bandwidths of 1.4, 3, 5, 10, 15, and 20 MHz with no fundamental change on the radio architecture. Allowing bandwidth to be assigned in a very flexible way makes it ideal for M2M and IoT applications.
However, while the process works, performance is not optimized. Various standards bodies are working on improving the LTE protocol as well as providing support for next-generation low-cost devices that are less complex. Congestion at cell sites is another issue that standards bodies are addressing as well as mobility management functions like longer sleep cycles.
LTE-Advanced (LTE-A) is the real 4G because it meets the ITU’s requirements for fourth-generation wireless systems, i.e. a peak download traffic data rate of 1 Gbps and an uplink rate of 500 Mbps. However, LTE-A is evolving and expanding and the new upcoming functionality underlines the fact that 4G technology is becoming the standard for high-speed wide area mobile communications.
Carrier aggregation is one of the evolving developments. Spectrum is a precious commodity and for historic reasons radio spectrum for use in cellular networks was licensed in different bands. Aggregating the spectrum assets of multiple carriers results in a much fatter bit pipe that delivers higher data rates and lower latencies for all users, as well as more capacity for “bursty” traffic peaks.
LTE did take a long time to evolve, which is not surprising given the high performance and functionality bar that was set by 3GPP, but network deployments are proceeding at a much faster rate than originally predicted, as is the availability of LTE-compliant devices.
LTE is distinguished from earlier networks by a groundbreaking combination of efficiency and flexibility. The efficient use of spectrum will lead to lower costs and the ability to combine high-speed, low-latency transmission with a range of cost-effective low bit rate services. Multi-regional coverage is the only significant issue: the air interface is complex and different countries are using more than 40 different frequency bands. But in the meantime the rollout of networks, devices and services proceeds, as does the new functionally that’s enabled by LTE-A.
