Mobile industry prepares LTE for Internet of Things

Tuesday 15 September 2015 | 17:15 CET | Background

LTE has been under development since 2008, and with each new version, the focus on more speed and more capacity increases, in order to support services providing a return on investment. As a result complexity also increases steadily. The industry has now started work on making LTE networks suitable for the Internet of Things (IoT), and for this the network technology cannot be simple enough. Alongside the digital superhighway, a more pedestrian path is also being built. 

The reason is the rise of the IoT and the billions of devices in need of their own internet connection to communicate. Indoors, the focus is on radio standards with limited reach, such as Wi-Fi, Bluetooth Low Energy and ZigBee. Outdoors there is a role for mobile networks, with their much further reach to play. These can reach up to 15km with Low Power Wide Area (LPWA) networks. According to estimates from Machina Research, around 30 billion devices will be connected to the Internet of Things within ten years. Around 7 billion of those will form part of an outdoor network, and this segment will grow by 35 percent per year, Nokia predicts in a recent white paper over LTE-M.

The 3GPP organisation is responsible for developing the LTE standards roadmap. With each new version of 4G, faster speeds and additional features, such as VoLTE, are added. The most recent Release 12, finalised at the end of 2014, and the upcoming Release 13, expected in Q1 2016, are taking a somewhat different route. The increasing complexity of LTE chipsets and radios will be reversed, focusing instead on limited bandwidth, low power, simple antennas and as much integration as possible of components on a single chip.

Now that 4G network roll-outs are largely completed in many countries, the infrastructure can start to serve M2M applications. The aim is to develop M2M units that cost just a couple dollars and last for many years. Devices will be equipped with a Power Save Mode under which they remained registered on the network but can go days if not months without making a connection. At the same time they can last up to ten years on the equivalent of two AA batteries, Nokia expects, based on data usage of around 200 bytes per day.

Nokia notes that demand for mobile internet only takes up a fraction of the capacity of the (radio) network, while part of M2M communication can also easily be conducted at night.

The 3GPP standards count the support of the major vendors of network equipment, such as Nokia, Ericsson and Huawei, and the chipmakers, including Intel, Qualcomm, Sequans and Altair. Nokia also recently announced a cooperation with Intel and Ericsson to develop Narrow Band LTE (NB LTE), a variation specially developed for machine-to-machine communications. Meanwhile, the major mobile operators and the GSM Association have started their own ‘Mobile IoT Initiative’.

Chipsets for Cat-1 and Cat-0

As the standardisation process gathers pace, the first commercial products are starting to emerge. Release 12 prepared the way for LTE Cat 1 and Cat 0; Cat 1 supports 10/5 Mbps, while Cat 0 is designed for 1/1 Mbps.

Chipsets for Cat 1 are already available, such as the Calliope platform from Sequans. This is used in the Cinterion M2M units from Gemalto and is being tested by Verizon Wireless (together with Ericsson) and T-Mobile US.

A Cat 1 radio may be more speed than is needed for some applications, but Cat 0 is still under development. Some of the latter's features, such as the Power Sleep Mode, can be deployed through a software upgrade on the network, Nokia said. This means they will also benefit Cat 1 devices.

Release 13 will set the parameters for LTE-M or Cat M for applications that require even less bandwidth and with an even longer battery life. The services use limited spectrum, as little as 1.4 MHz for LTE-M or 200 kHz for Narrow-Band LTE-M. The ‘Clean Slate IoT’ project is also looking at a standard with still less bandwidth than NB LTE-M, of around 50 kbps.

Another candidate is EC-GSM, an evolutionary path for current M2M applications on 2G networks. The specifications are comparable to Narrow-Band LTE-M, but use carriers of 200 kHz on refarmed GSM spectrum.

Licence-free spectrum

In addition to the above 3GPP standards, a number of companies are developing LPWA networks on licence-free spectrum, using proprietary technology. Examples include Ingenu, Sigfox and the LoRa Alliance; the latter has attracted operators such as KPN, Proximus and Bouygues Telecom.

Again the target market is services requiring very low bandwidth. SigFox is designed for connected devices sending up to 140 messages per day of around 12 bytes per message as well as receiving four messages of 8 bytes each per day. LoRa also is focusing on services using only very limited data. 

Spectrum not requiring a licence is available below 1 GHz, including the 868 MHz band in Europe and 902 MHz in the US. Network roll-outs can start already at low costs using these frequencies.

The backers of the 3GPP standards suggest that proprietary technology can at best serve niche markets. The technology being introduced under Releases 12, 13 and 14 will also form the basis for ‘pre-5G’ or ‘4.5G’, supporting the transition of IoT services to 5G networks. Nevertheless, licence-free spectrum still carries a number of advantages and is expected to remain in use alongside licensed frequencies. 

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