Showing posts with label Sigfox. Show all posts
Showing posts with label Sigfox. Show all posts

Sunday, 7 May 2017

10 years battery life calculation for Cellular IoT

I made an attempt to place the different cellular and non-cellular LPWA technologies together in a picture in my last post here. Someone pointed out that these pictures above, from LoRa alliance whitepaper are even better and I agree.

Most IoT technologies lists their battery life as 10 years. There is an article in Medium rightly pointing out that in Verizon's LTE-M network, IoT devices battery may not last very long.

The problem is that 10 years battery life is headline figure and in real world its sometimes not that critical. It all depends on the application. For example this Iota Pet Tracker uses Bluetooth but only claims battery life of  "weeks". I guess ztrack based on LoRa would give similar results. I have to admit that non-cellular based technologies should have longer battery life but it all depends on applications and use cases. An IoT device in the car may not have to worry too much about power consumption. Similarly a fleet tracker that may have solar power or one that is expected to last more than the fleet duration, etc.

So coming back to the power consumption. Martin Sauter in his excellent Wireless Moves blog post, provided the calculation that I am copying below with some additions:

The calculation can be found in 3GPP TR 45.820, for NB-IoT in Chapter on ‘Energy consumption evaluation’.

The battery capacity used for the evaluation was 5 Wh. That’s about half or even only a third of the battery capacity that is in a smartphone today. So yes, that is quite a small battery indeed. The chapter also contains an assumption on how much power the device draws in different states. In the ‘idle’ state the device is in most often, power consumption is assumed to be 0.015 mW.

How long would the battery be able to power the device if it were always in the idle state? The calculation is easy and you end up with 38 years. That doesn’t include battery self-discharge and I wondered how much that would be over 10 years. According to the Varta handbook of primary lithium cells, self-discharge of a non-rechargable lithium battery is less than 1% per year. So subtract roughly 4 years from that number.

Obviously, the device is not always in idle and when transmitting the device is assumed to use 500 mW of power. Yes, with this power consumption, the battery would not last 34 years but less than 10 hours. But we are talking about NB-IoT so the device doesn’t transmit for most of the time. The study looked at different transmission patterns. If 200 bytes are sent once every 2 hours, the device would run on that 5 Wh battery for 1.7 years. If the device only transmits 50 bytes once a day the battery would last 18.1 years.

So yes, the 10 years are quite feasible for devices that collect very little data and only transmit them once or twice a day.

The conclusions from the report clearly state:

The achievable battery life for a MS using the NB-CIoT solution for Cellular IoT has been estimated as a function of reporting frequency and coupling loss. 

It is important to note that these battery life estimates are achieved with a system design that has been intentionally constrained in two key respects:

  • The NB-CIoT solution has a frequency re-use assumption that is compatible with a stand-alone deployment in a minimum system bandwidth for the entire IoT network of just 200 kHz (FDD), plus guard bands if needed.
  • The NB-CIoT solution uses a MS transmit power of only +23 dBm (200 mW), resulting in a peak current requirement that is compatible with a wider range of battery technologies, whilst still achieving the 20 dB coverage extension objective.  

The key conclusions are as follows:

  • For all coupling losses (so up to 20 dB coverage extension compared with legacy GPRS), a 10 year battery life is achievable with a reporting interval of one day for both 50 bytes and 200 bytes application payloads.
  • For a coupling loss of 144 dB (so equal to the MCL for legacy GPRS), a 10 year battery life is achievable with a two hour reporting interval for both 50 bytes and 200 bytes application payloads. 
  • For a coupling loss of 154 dB, a 10 year battery life is achievable with a 2 hour reporting interval for a 50 byte application payload. 
  • For a coupling loss of 154 dB with 200 byte application payload, or a coupling loss of 164 dB with 50 or 200 byte application payload, a 10 year battery life is not achievable for a 2 hour reporting interval. This is a consequence of the transmit energy per data bit (integrated over the number of repetitions) that is required to overcome the coupling loss and so provide an adequate SNR at the receiver. 
  • Use of an integrated PA only has a small negative impact on battery life, based on the assumption of a 5% reduction in PA efficiency compared with an external PA.

Further improvements in battery life, especially for the case of high coupling loss, could be obtained if the common assumption that the downlink PSD will not exceed that of legacy GPRS was either relaxed to allow PSD boosting, or defined more precisely to allow adaptive power allocation with frequency hopping.

I will look at the technology aspects in a future post how 3GPP made enhancements in Rel-13 to reduce power consumption in CIoT.

Also have a look this GSMA whitepaper on 3GPP LPWA lists the applications requirements that are quite handy.

Monday, 1 May 2017

Variety of 3GPP IoT technologies and Market Status - May 2017

I have seen many people wondering if so many different types of IoT technologies are needed, 3GPP or otherwise. The story behind that is that for many years 3GPP did not focus too much on creating an IoT variant of the standards. Their hope was that users will make use of LTE Cat 1 for IoT and then later on they created LTE Cat 0 (see here and here).

The problem with this approach was that the market was ripe for a solution to a different types of IoT technologies that 3GPP could not satisfy. The table below is just an indication of the different types of technologies, but there are many others not listed in here.

The most popular IoT (or M2M) technology to date is the humble 2G GSM/GPRS. Couple of weeks back Vodafone announced that it has reached a milestone of 50 million IoT connections worldwide. They are also adding roughly 1 million new connections every month. The majority of these are GSM/GPRS.

Different operators have been assessing their strategy for IoT devices. Some operators have either switched off or are planning to switch off they 2G networks. Others have a long term plan for 2G networks and would rather switch off their 3G networks to refarm the spectrum to more efficient 4G. A small chunk of 2G on the other hand would be a good option for voice & existing IoT devices with small amount of data transfer.

In fact this is one of the reasons that in Release-13 GSM is being enhanced for IoT. This new version is known as Extended Coverage – GSM – Internet of Things (EC-GSM-IoT ). According to GSMA, "It is based on eGPRS and designed as a high capacity, long range, low energy and low complexity cellular system for IoT communications. The optimisations made in EC-GSM-IoT that need to be made to existing GSM networks can be made as a software upgrade, ensuring coverage and accelerated time to-market. Battery life of up to 10 years can be supported for a wide range use cases."

The most popular of the non-3GPP IoT technologies are Sigfox and LoRa. Both these technologies have gained significant ground and many backers in the market. This, along with the gap in the market and the need for low power IoT technologies that transfer just a little amount of data and has a long battery life motivated 3GPP to create new IoT technologies that were standardised as part of Rel-13 and are being further enhanced in Rel-14. A summary of these technologies can be seen below

If you look at the first picture on the top (modified from Qualcomm's original here), you will see that these different IoT technologies, 3GPP or otherwise address different needs. No wonder many operators are using the unlicensed LPWA IoT technologies as a starting point, hoping to complement them by 3GPP technologies when ready.

Finally, looks like there is a difference in understanding of standards between Ericsson and Huawei and as a result their implementation is incompatible. Hopefully this will be sorted out soon.

Market Status:

Telefonica has publicly said that Sigfox is the best way forward for the time being. No news about any 3GPP IoT technologies.

Orange has rolled out LoRa network but has said that when NB-IoT is ready, they will switch the customers on to that.

KPN deployed LoRa throughout the Netherlands thereby making it the first country across the world with complete coverage. Haven't ruled out NB-IoT when available.

SK Telecom completed nationwide LoRa IoT network deployment in South Korea last year. It sees LTE-M and LoRa as Its 'Two Main IoT Pillars'.

Deutsche Telekom has rolled out NarrowBand-IoT (NB-IoT) Network across eight countries in Europe (Germany, the Netherlands, Greece, Poland, Hungary, Austria, Slovakia, Croatia)

Vodafone is fully committed to NB-IoT. Their network is already operational in Spain and will be launching in Ireland and Netherlands later on this year.

Telecom Italia is in process of launching NB-IoT. Water meters in Turin are already sending their readings using NB-IoT.

China Telecom, in conjunction with Shenzhen Water and Huawei launched 'World's First' Commercial NB-IoT-based Smart Water Project on World Water Day.

SoftBank is deploying LTE-M (Cat-M1) and NB-IoT networks nationwide, powered by Ericsson.

Orange Belgium plans to roll-out nationwide NB-IoT & LTE-M IoT Networks in 2017

China Mobile is committed to 3GPP based IoT technologies. It has conducted outdoor trials of NB-IoT with Huawei and ZTE and is also trialing LTE-M with Ericsson and Qualcomm.

Verizon has launched Industry’s first LTE-M Nationwide IoT Network.

AT&T will be launching LTE-M network later on this year in US as well as Mexico.

Sprint said it plans to deploy LTE Cat 1 technology in support of the Internet of Things (IoT) across its network by the end of July.

Further reading:

Saturday, 16 May 2015

Smart Homes of the Future and Technologies

Saw the above picture recently on Twitter. While its great to see how connected our future homes and even cities would be, it would be interesting to see what technologies are used for connecting these devices.

Cambridge Wireless had a smart homes event last month, there were some interesting presentations that I have detailed below.

The first of these technologies discussed is LoRa. As can be seen, its billed as ultimate long range (10 mile) and low power (10 year battery lifetime) technology. It uses spread-spectrum making it robust to channel noise. Here is the presentation:

The next technology is Zigbee 3.0. According to Zigbee Alliance:

The new standard unifies ZigBee standards found in tens of millions of devices delivering benefits to consumers today. The ZigBee 3.0 standard enables communication and interoperability among devices for home automation, connected lighting, energy efficiency and other markets so more diverse, fully interoperable solutions can be delivered by product developers and service providers. All device types, commands, and functionality defined in current ZigBee PRO-based standards are available to developers in the new standard.

ZigBee 3.0 defines the widest range of device types including home automation, lighting, energy management, smart appliance, security, sensors, and health care monitoring products. It supports both easy-to-use DIY installations as well as professionally installed systems. Based on IEEE 802.15.4, which operates at 2.4 GHz (a frequency available for use around the world), ZigBee 3.0 uses ZigBee PRO networking to enable reliable communication in the smallest, lowest-power devices. Current ZigBee Certified products based on ZigBee Home Automation and ZigBee Light Link are interoperable with ZigBee 3.0. A complete list of standards that have been merged to create ZigBee 3.0 can be seen on the website at

“The ZigBee Alliance has always believed that true interoperability comes from standardization at all levels of the network, especially the application level which most closely touches the user,” said Tobin J. M. Richardson, President and CEO of the ZigBee Alliance. “Lessons learned by Alliance members when taking products to market around the world have allowed us to unify our application standards into a single standard. ZigBee 3.0 will allow product developers to take advantage of ZigBee’s unique features such as mesh networking and Green Power to deliver highly reliable, secure, low-power, low-cost solutions to any market.”

Finally, we have Bluetooth Smart mesh.

CSRmesh enables Bluetooth® low energy devices not only to receive and act upon messages, but also to repeat those messages to surrounding devices thus extending the range of Bluetooth Smart and turning it into a mesh network for the Internet of Things.

While the CW event was not able to discuss all possible technologies (and believe me there are loads of them), there are other popular contenders. Cellular IoT (CIoT) is one if them. I have blogged about the LTE Cat-0 here and 5G here.

A new IEEE Wi-Fi standard 802.11ah using the 900MHz band has been in works and will solve the need of connectivity for a large number of things over long distances. A typical 802.11ah access point could associate more than 8,000 devices within a range of 1 km, making it ideal for areas with a high concentration of things. The Wi-Fi Alliance is committed to getting this standard ratified soon. With this, Wi-Fi has the potential to become a ubiquitous standard for IoT. See also this article by Frank Rayal on this topic.

Finally, there is SIGFOX. According to their website:

SIGFOX uses a UNB (Ultra Narrow Band) based radio technology to connect devices to its global network. The use of UNB is key to providing a scalable, high-capacity network, with very low energy consumption, while maintaining a simple and easy to rollout star-based cell infrastructure.

The network operates in the globally available ISM bands (license-free frequency bands) and co-exists in these frequencies with other radio technologies, but without any risk of collisions or capacity problems. SIGFOX currently uses the most popular European ISM band on 868MHz (as defined by ETSI and CEPT) as well as the 902MHz in the USA (as defined by the FCC), depending on specific regional regulations.

Communication on SIGFOX is secured in many ways, including anti-replay, message scrambling, sequencing, etc. The most important aspect of transmission security is however that only the device vendors understand the actual data exchanged between the device and the IT systems. SIGFOX only acts as a transport channel, pushing the data towards the customer's IT system.

An important advantage provided by the use of the narrow band technology is the flexibility it offers in terms of antenna design. On the network infrastructure end it allows the use of small and simple antennas, but more importantly, it allows devices to use inexpensive and easily customizable antennas.

Sigfox is also working on project Mustang, a three-year effort to build a hybrid satellite/terrestrial IoT (internet of things) network. According to Rethink Research:

The all-French group also contains aerospace firm Airbus, research institute CEA-Leti and engineering business Sysmeca. The idea is to use Sigfox as the terrestrial data link, with satellite backhaul and connections to planes and boats provided by a low-earth orbit (LEO) satellite constellation.
The satellite link could be added to either the end devices or the base station, so that if a device was unable to connect to the terrestrial Sigfox network, it could fall back to the satellite.

While the power requirements for this would be prohibitive for ultra-low power, battery-operated devices, for those with a wired power supply and critical availability requirements (such as smart meters, alarms, oil tankers and rigs) the redundancy would be an asset. These devices may transmit small amounts of data but when they do need to communicate, the signal must be assured.

The Sigfox base station could be fitted with a satellite uplink as a primary uplink as well as a redundancy measure in some scenarios where terrestrial network reach cannot be achieved. With a three-year lifecycle, Mustang’s participants are looking to create a seamless global network, and note that the planned dual-mode terrestrial/satellite terminal will enable switching between the two channels in response to resource availability.

The group says that the development of this terminal modem chipset is a priority, with later optimization of the communication protocols being the next step before an application demonstration using an airplane.

The project adds that the full potential of the IoT can only be achieved by offering affordable mobile communications at a global scale and reach. Key to this is adapting existing networks, according to the group, which explains why Sigfox has been chosen – given that the company stresses the affordability of its system.

Well, there are a lots of options available. We just have to wait and see which ones work in what scenarios.