, Sweat-proof “smart skin” takes reliable vitals, even during workouts and spicy meals
, Sweat-proof “smart skin” takes reliable vitals, even during workouts and spicy meals

DK low energy IoT trends

Abstract
This article looks at developments in low power for the Internet of Things, particularly the Thread consortium low power extensions for IOT smart energy and other competing consortia.

Low Power IoT trends
Smart energy is becoming an increasingly important and competitive capability in the Internet of Things. The ability to run a sensor node for months or even years rather than weeks is driving chips and system developers to look at new ways of deploying vast networks of devices.
The latest innovation has emerged from a consortium of companies that calls itself the Thread Group and is looking to roll out Thread, a new IP-based wireless networking protocol designed for low-power connected products in the home. The Thread protocol was founded by 7 industry-leading companies, including Nest, a California startup that developed a smart thermostat and networked smoke detector. Nest is now owned by Google, and the Thread Group also includes processor core designer ARM, low power chip specialist Silicon Labs, Samsung Electronics, Freescale Semiconductor, Big Ass Fans and lock maker Yale Security. ARM dominates the space for wireless controllers from a wide range of chip suppliers, so is an important partner for Thread. Makers of air conditioning systems and locks are part of the consortium as these are the end products that will be controlled across the Internet.
Thread technology is based on 6LoWPAN, which uses the 802.15.4 2.4GHz wireless protocol that is also used by ZigBee, although the two are different. 6LoWPAN is specifically designed to support the larger IPv6 address space that is needed for IoT with a low power, low data rate network running at up to 250kbit/s.
The low energy comes partly from avoiding the ‘hub and spoke’ model where all the nodes have to connect to a hub. Being able to directly interact with devices – over 250 – and over the Internet can reduce the power requirements.
Thread offers a robust self-healing mesh networks that scale to hundreds of devices with no single point of failure. This reduces power as there is less need to retransmit packets. The Thread devices will also be simple to install with a smartphone, tablet or computer so that consumers can securely connect Thread devices in the home to each other and to the cloud for easy control and access from anywhere.

, Sweat-proof “smart skin” takes reliable vitals, even during workouts and spicy meals

Figure 1: The Thread protocol block diagram (Courtesy of the Thread Group)

Existing wireless networking approaches were introduced long before the Internet of Things gained ground, says Vint Cerf, vice president and chief Internet evangelist, Google, and advisor to the Thread Group, so the Thread protocol takes existing technologies and combines the best parts of each to provide a better way to connect products in the home.
Unlike many existing technologies or IoT approaches, Thread is not an application protocol or a connectivity platform for many types of disparate networks. This is an IPv6 networking protocol built on open standards and specifically optimized for low-power 802.15.4 mesh networks. As a result, existing popular application protocols and IoT platforms can run over Thread networks. This provides a significant advantage for the consortia members looking for Thread to be adopted by equipment makers. Millions of existing 802.15.4 wireless devices already on the market – mostly running ZigBee – can run Thread with just a software enhancement with no new hardware required. This will be a potential benefit to chip makers such as Atmel, Silicon Labs and Texas Instruments who already supply devices using the ZigBee protocol and have extensive experience with mesh network application software.

, Sweat-proof “smart skin” takes reliable vitals, even during workouts and spicy meals

Figure 2: Thread network architecture (Courtesy of the Thread Group)

However, there are several other technologies looking to be the platform for IoT applications.
ZigBee sees itself as a key IoT technology, with the mesh network that uses the same 2.4GHz radio front end. Unlike 6LoWPAN, ZigBee uses a hub to connect up the IoT sensors, although the latest version supports IPv6 and more direct connections as well as low power modes with higher data rates.
Thread will also be competing with other low power technologies that are emerging for the Internet of Things. The Bluetooth Special Interest Group (SIG) has approved two new low power versions of the point to point protocol, for Bluetooth Low Energy (now called Bluetooth Smart). BT Smart 4.0 and 4.1 add new low power modes to cut the power in connecting devices – 4.0 for personal devices such as fitness monitors and 4.1 for longer range IoT devices. Cambridge Silicon Radio also has a technology called CSRmesh that uses BT4.0 to provide a low power mesh network for IoT applications similar to ZigBee but without the hub. It is making this an open protocol and the Bluetooth SIG is working on a mesh version to standardize.
At the same time there is also a proposal from 6LoWPAN to include elements of this technology in Bluetooth Smart.
WiFi also has not stood still in looking at low power. The latest version of the 802.11 standard that is used to power wireless networks around the world moves to the sub Ghz band to save power and provide longer range, and many of the WiFi silicon suppliers are positioning for this new technology called 802.11ah. This is currently undergoing voting by the IEEE, also removes the need for regular polling that made WiFi a relatively power hungry technology. The combination of low power modes, much longer sleep modes and operation at around 900MHz will make WiFi a significant contender for low power IoT networks as nodes will be able to automatically join existing wireless networks.

, Sweat-proof “smart skin” takes reliable vitals, even during workouts and spicy meals

Figure 3: Enigma Whisper Bluetooth Smart and low power Wi-Fi (Courtesy of Imagination Technologies)

Imagination Technologies has developed a configurable radio processing unit (RPU) that can handle all the WiFi protocols including 802.11ah as well as Bluetooth 4.0 and 4.1 and, if necessary, ZigBee, with low power in mind. The Whisper architecture combines a configurable modem block with much of the MAC functions handled in a Warrior class MIPS processor. The RPU design will be available for licensing to chip makers towards the end of 2014 and allows the device makers to have a single underlying architecture and configure it for different products for different standards. For example, a dedicated 802.11ah implementation will be half the size and power consumption of a full 802.11n WiFi design, and can still be used alongside a Bluetooth block, for example. Taking this configurable route is the way to achieve lower power, says Imagination.
Higher up the application stack there are other consortia looking to build low power smart energy networks for IoT.
Weightless is an open standard that operates in a range of bands including the unlicensed sub GHz band to provide a low power implementation. With silicon designed by Neul (Acquired by Huawei) in Cambridge, Weightless is now testing out IoT applications in Milton Keynes.
The Open Interconnect Consortium is another competing group that is also aiming to provide a low power protocol for IoT starting with the home. This group includes Atmel, Cisco, Dell, Intel and its Wind River subsidiary, as well as Samsung who is also in the Thread Group.
The OIC is aiming to create a common communications framework based on industry standard technologies to connect and manage IoT devices. The open source layer is intended to be agnostic to the form factor, operating system or service provider.
The member companies are contributing software and engineering resources to the development of a protocol specification, open source implementation, and a certification program, all with a view of accelerating the development of the IoT.
What makes this slightly different is that it is intended to cover a range of existing and emerging wireless standards and be compatible with a variety of operating systems, rather than just being one radio technology.
The OIC is competing directly with the AllSeen Alliance that is backed by chip giant Qualcomm, Microsoft and also networking giant Cisco. This is built around the AllJoyn open source technology developed by Qualcomm and now has 50 companies signed up, including Sharp, D-link and Wilocity. The aim of AllJoyn is that the core building blocks and services for discovery of new devices, how they connect and security can be used across both wireless and wired networks for connecting up devices. The aim is to standardize the approach at a higher level to allow devices with different technologies to interact, so the focus is on service-level discovery, capabilities broadcasting, remote procedure calls, interface sharing and message handling, along with the ability to react to dynamic, ad-hoc network changes.
AllSeen is probably slightly ahead of other consortia such as OIC and the Thread Group with more members and a software development kit to allow applications developers and end customers to work with the technology. However the amount of software development needed to bring different technologies together with a low power implementation may be a challenge for many customers, along with the focus mostly on the US.

Conclusion
Low power is becoming a driving force behind the development of technology for the Internet of Things. Trading off data rate, packet complexity and wireless duty cycle to reduce the power requirements and extend battery life is leading to a split of protocols and standards, backed by a range of different consortia. It is now down to the different applications, particularly in the smart home, and the cooperation of different suppliers that will determine the protocols with the critical mass and so the cost effective solution.

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