What is 4G LTE?

By Ashish Gulati

4G LTE (Long Term Evolution) builds on the success of the second and third generation cellular technologies used by mobile network operators. However, it is distinguished from those 2G and 3G networks by brand new network core and air interface technologies. It employs a simple, flat, all-IP architecture that is more efficient and flexible. LTE can accommodate up to 10 times more traffic and latency is 10 times lower. Network operators continue to promote high-speed, high-margin services that meets the performance requirements of phones and other consumer-oriented devices like tablets or PCs that require large bandwidth. Therefore, LTE is seen as a solution for a narrow list of M2M / IoT segments where high data speeds (routers) and long term network availability is required (metering). LTE’s intrinsic flexibility allows the technology to deliver different services. For example, the top end data rate is 450 Mbps, which is set to rise to 600 Mbps next year. The low-end data rate is currently 10Mbps and this is where LTE is being challenged. Many M2M/IoT applications only need a throughput of 100bps.

The IoT sector is also served by other wireless technologies such as WiFi, Bluetooth, Zigbee, Z-Wave as well as LPWA (low-power wide-area) options which all have their own challenges. Cellular is often the technology of choice when mobility, coverage, scalability, reliability or security is required, but the challenge is serious, particularly for the B2C sector, where lifecycles are much shorter than those of the Industrial IoT (IIoT). LTE employs UE (User Equipment) categories to define the performance specification. Category 1’s download data rate, 10Mbps, is the lowest, but it is a performance overkill. Cat-1 was specified back in 2008 but never introduced into the core network by the service providers because their focus was on consumer devices.

The response of the 3GPP (Third Generation Partnership Project) started with Cat-0 which focuses on the needs of the industry, the primary goal being reducing the size, power and cost of LTE technology. The 3GPP is the working group that defines new revisions of cellular technology standards. Cat-0 will be followed by Cat-M, which refers to LTE Machine-Type Communications, and at a later date by Narrow-Band IoT.

LTE-MTC is a convenient way of encapsulating the optimization of LTE Advanced for Machine-Type Communications. The key benefits of LTE-MTC include:

• Taking advantage of the reliability, pervasiveness, efficiency and longevity of 4G LTE
• The significant increase in battery life thanks to longer sleep cycles, while reducing cost/complexity and enhancing coverage in what have traditionally been difficult-to-reach locations.
• Facilitating new business model innovation
• The ability to play a key connectivity role in the various solutions that make up IoT solutions.

Recent 4G developments have focused on the needs of the IoT industry, the primary goal being reducing the size, power and cost of LTE technology, which in turn will allow cellular to take direct aim at other IoT wireless technologies like Wi-Fi, Bluetooth, ZigBee, Z-wave, and other LPWA (low-power wide-area) options.

As the underlying network technologies become more efficient and better targeted towards the specific IoT applications, differences in rate plans specific to those technologies will continue to evolve. We have seen this in a broad scale as generally data rates have decreased over time. The intersection of lower and lower data rates along with new network technologies has resulted in new and exciting business models across industries. We are seeing more and more high bandwidth applications and existing applications evolving into new higher bandwidth feature sets. The continued evolution of LTE and the associated lower data cost structures will accelerate this trend.

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 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.

In conclusion, 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.

(The author, Ashish Gulati, is Country Manager at Telit India)