Enabling Cellular Networks for IoT

Feb 13, 2017 | By Navnit Goel

Cellular operators are at cross roads today as uptake of IoT is set to take-off. Analysts predict that there will be around 28 billion connected devices by 2021, of which more than 15 billion will be connected M2M and consumer-electronics devices. [1]. IoT Market size is likely to reach about 661 billion USD by 2021.

Cellular operators have a unique opportunity to monetize their existing networks and earn extra revenue by supporting new IoT applications by upgrading their networks and provide affordable connectivity on a global scale. Single network supporting all applications – from mobile broadband services, VoIP and all kinds of low – to high-end IoT use cases is a very strong value proposition.

The size of this share of market for these operators, will depend on the role, they adopt in the value chain. This could range from being a connectivity provider to all the way to being an end-to-end solution provider of turnkey solutions to vertical markets [4].

Cellular networks have following advantages over alternative WAN technologies such as unlicensed LPWA technologies like Wi-Fi, Bluetooth and Zigbee:

  • Global reach
  • QoS
  • Ecosystem
  • Security
  • Lesser Total Cost of Ownership (TCO)
  • Faster roll out enabled by software up-gradation of existing networks

1. Wide Range of IoT Applications

IoT applications can be put widely in two categories – Massive IoT applications and Critical IoT applications


Table-1

 


Table-2

2. Wide Range of IoT Requirements

IoT applications have a variety of requirements regarding device cost, battery life, coverage, performance (throughput and capacity), security and reliability depending upon application. Very less throughput is needed for applications like temperature status update, whereas high throughput is needed in case of video streaming for remote repair. Applications for monitoring and control of systems like heating and control plants need communication in uplink as well as in downlink whereas some applications like fire detectors need only uplink communication with low latency. For tracking applications, location information is essential. High security is needed for sensitive data transmission.

If, a system can be designed using a set of underlying technologies with a common network architecture with operational and fault management capability, it will result into a cost effective solution with optimum utilization of system resources.

a) Main requirements for massive IoT

  • Low cost – for high volume mass-market applications
  • High Battery life – cost of replacing battery in field is prohibitive.
  • Coverage – National/global with deep indoor connectivity for applications like transport.
  • Scalability –From initially supporting few devices to thousands or millions of devices.

b) Main requirements for Critical IoT

  • High reliability
  • High availability
  • High throughput
  • Low latency

3. Alternatives for IoT Connectivity

Type of access required will depend on the nature of the application.

a) Home or indoor environment ( PAN or LAN)

This will mostly be served by radio technologies that operate on unlicensed spectrum and that are designed for short-range connectivity with limited QoS and security requirements. The main technologies in this category are Wi-Fi, Bluetooth, and ZigBee.

b) Wide area coverage ( WAN)

There are two alternatives

  • Cellular technologies – 3GPP technologies like GSM, WCDMA, LTE and 5G technology. These WANs operate on licensed spectrum and they have historically been targeted to provide high-quality mobile voice and data services. Now, in order to meet emerging requirements of IoT with low power wide area (LPWA) applications, they are being enhanced by technologies like narrow band IoT (NB-IoT).

  • Unlicensed LPWA: new proprietary radio technologies, for example, SIGFOX and LoRa. These have been developed and designed solely for machine-type communication (MTC) applications addressing the ultra-low-end sensor segment, with very limited demands on throughput, reliability or QoS.

4. Mobility Support

The coverage needs of a particular use case may be stationary device, on in other cases global service coverage may be required for applications such as container tracking. 3GPP technologies already dominate use cases with large geographic coverage needs and medium- to high-performance requirements. With LPWA technologies requirements of low-cost, low-performance applications can also be met.

5. Networks combining Cellular and Unlicensed Strengths

Even when end-to-end cellular connectivity is not feasible, cellular technology can still be used as a bridging option, i.e. as an aggregation and routing solution. This capillary network approach allows end devices to utilize varying access solutions from either the short range or unlicensed LPWA domain and access the cellular networks via a gateway device. Capillary networks enable the reuse of cellular functions and assets such as security, device management, billing and QoS without requiring each end device to be cellular-enabled.

6. Cellular LPWA solutions

No single technology is suited to all the different potential Massive IoT applications, market situations and spectrum availability. As a result, the mobile industry is standardizing several LPWA technologies, including Extended Coverage GSM (EC-GSM), LTE-M and NB-IoT.

As a family of solutions, these can complement each other based on technology availability, use case requirements and deployment scenarios. NB-IoT covers ultra-low- end IoT applications with a cost and coverage advantage over LTE-M; and EC-GSM serves IoT services for all GSM markets. Asset-tracking applications that can support a relatively high number of messages triggered by certain events may employ LTE-M.

a) Extended Coverage GSM (EC-GSM)

Legacy GSM is most widely deployed mobile technology in several geographies across the world. Vast majority of cellular M2M applications use legacy GSM/GPRS/EDGE networks.

In order to serve the new IoT requirements, where legacy GSM networks continue to be in use, 3GPP has introduced improvements in release 13 with EC-GSM functionality. EC-GSM functionality enables coverage improvements of up to 20dB. EC-GSM is achieved by defining new control and data channels lover legacy GSM. Software up-gradation over the existing GSM network is sufficient. It supports up to 50,000 devices per cell. Another 3GPP feature eDRX improves the idle mode behavior, thus improving power efficiency and increasing battery life. A smart city application such as waste management may use EC-GSM technology to provide LPWA connectivity in markets where it can be deployed on existing 2G networks.

b) LTE-M – For Massive IoT Use cases

3GPP has introduced new functionalities in LTE with introduction of LTE-M to support IoT. LTE-M brings new power-saving and eDRX functionalities, reduction in complexities to reduce device cost. Cat 1, Cat 0 and Cat M devices support a wide range of IoT applications, including those that are content-rich.

c) NB-IoT – for Ultra-low-end MASS IoT Applications

  • Being standardized in 3GPP release 13
  • Self contained 200KHz carrier
  • NB-IoT carrier can be deployed in guard-band or as a standalone carrier
  • each 200 KHz carrier can support up to 200,000 devices
  • Can be scaled up by adding multiple carriers
  • Can be enabled with SW upgrade only
  • Extended coverage of up to 20dB
  • Battery saving, Power Saving Mode and eDRX features
  • Reduces device complexity below that of LTE-M
  • Suitable for supporting ultra-low end applications

For example, NB-IoT technology may be used for water-metering applications, which have deep coverage requirements in underground locations.

7. Advantages of cellular technologies

Each of the technologies available for IoT connectivity has its own advantages and disadvantages. However cellular technologies can provide both technical and commercial benefits across a wide variety of applications.

In terms of global reach, cellular networks already cover 90 percent of the world’s population. WCDMA and LTE are catching up, but GSM will offer superior coverage in many markets for years to come. Cellular networks have been developed and deployed for over three decades, and they will be around for the foreseeable future.

The cellular mobile industry represents a huge and mature ecosystem governed by 3GPP standardization forum, incorporating chipset, device and network equipment vendors, operators, application providers and many others.

Cellular networks are built to handle massive volumes of mobile broadband traffic; the traffic from most IoT applications will be relatively small and easily absorbed. Operators are able to offer connectivity for IoT applications from the start-up phase and grow this business with only incremental investment and effort. Operation in licensed spectrum provides predictable and controlled interference.

Cellular connectivity offers the diversity to serve a wide range of applications with varying requirements within one network. While competing unlicensed LPWA technologies are designed solely for very low-end MTC applications, cellular networks can address everything from Massive to Critical IoT use cases.

QoS mechanisms will be essential for many IoT applications. Cellular systems have mature QoS functionality, and this enables critical MTC applications to be handled together with traffic from sensors, voice and mobile-broadband traffic on the same carrier.

Traditionally, the security mechanisms of cellular networks have been based on a hardware SIM card attached to the device. The SIM will also be essential in future IoT applications, with hardware SIM card or as a soft-SIM solution running in a trusted run-time environment of the module.

With a straightforward rollout of new software, cellular networks will be able to support the full breadth of applications, ranging from low-end use cases in the LPWA segment, to the high-end segments of in-car entertainment and video surveillance

8. Evolution of 3GPP standards to Support LTE

3GPP has taken evolutionary steps on both the network side and the device side to meet requirements of the massive IoT segment. The key improvement areas addressed in 3GPP up to Release 13 are:

  • Lower device cost – by reducing peak rate, memory and device complexity

  • LTE for machine-type communication (LTE-M) Cat 1 devices with reduced peak rate of 100 Mbps introduced in Release 8

  • Further reduction in device cost in Releases 12 and 13 with reduced device complexity for lower performance and using less bandwidth.

  • Improved battery life – more than 10 years of battery life by introducing Power Saving Mode and/or extended discontinuous reception (eDRX) functionality.

  • Improved coverage – an improvement of 15dB in LTE-M and of 20dB in NB-IoT and GSM, which improves outdoor coverage area and indoor signal penetration significantly. This can support many IoT devices like smart meters, placed in a basement.

  • Support for massive numbers of IoT connections – one LTE cell site can support millions of IoT devices, depending on the use case.

  • Core network enhancements – Service differentiation handling, signaling optimization and support for more than 30 million devices per node.

9. References

[1] Ericsson, Mobility Report: http://www.ericsson.com/res/docs/2015/mobility-report/ericsson-mobility-report-nov-2015.pdf
[2] Gartner, IoT Installed Base Will Grow to 26 Billion Units By 2020: http://www.gartner.com/newsroom/id/2636073
[3] Ericsson, White Paper: https://www.ericsson.com/res/docs/whitepapers/wp_iot.pdf
[4]Ericsson, White Paper: http://www.ericsson.com/res/docs/whitepapers/wp-m2m.pdf

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