Tracking Technology Overview

There are three way of determining location for tracking devices.

Either you can use a reference, such as GPS whereby listening to the GPS satellites the position on the earth’s surface can be determined. The issue here is that the device has to be able to hear the GPS satellites (at least three) and then be able to transmit that information. The GPS signal itself is very weak and easily jammed.

The second method of determining location is by sending a transmission that contains information about the different radios that can be heard. This is like taking a bearing on notable points in the landscape. If you know where the radio is that you can hear, then by the angle of arrival and the strength of transmission you can gauge the direction and range. Again by taking three points this can provide a pretty accurate location.This is why sometimes in a city your smartphone will tell you that by turning on WiFi, locations will be more accurate. What is saying is that the GPS satellite signal may be obscured by high buildings or bouncing around, whereas by comparing the WiFi signals it can hear to the online database of where those routers are, it can narrow down you position.

The final method of determining location is by using a beacon. This has a number of advantages in that beacons are hard to jam and are very simple devices. However, the device cannot use a beacon to find out where it is – it relies on someone coming to find that device with a directional scanner. The beauty of this solution is that it does not require any interaction with the cloud. The beacon device transmits, the directional scanner receives it and the person closes in on the beacon. Whether you are trying to find a stolen car or a person in a burning building, this is simple and reliable technology that work best over a few hundred metres. Therefore beacons are usually used in combination with GPS or radio triangulation to get the recovery team into the area, before narrowing down the search with the beacon.

Networks are designed to do different things. Orion is designed for the real time tracking and monitoring of people and assets. Clients today include a large number of blue chips, charities and some government organisations. The Orion network does not use a control channel and therefore is not liable to timing issues and battery issues caused by interference.

Uniquely, Orion also has an analogue mode for recovery by direction finding equipment. Since the infrastructure, devices and software all come from a single supplier, projects can be priced to suit the customer’s needs. There is an ever increasing customer list. Specifically, clients are adopting the technology for the real time audit of assets and people, with the added re-assurance that a recovery can take place if something is stolen.

All the hype around the Internet of Things (IoT) has led to speculation that there will be billions of devices added to networks over the coming years. Fundamentally, it seems that little attention has been paid to the overall radio environment when making these predictions. Governments licence the spectrum to make money but fundamentally, to help prevent interference. Whatever the protocol, as the airwaves become more crowded, the affect is to shorten the effective range of the communications. This is why licencing of the radio waves is about both the maximum power of transmission and also the duty cycle, how many times can you transmit in a given period.

The vast majority of the communications networks today are focusing on the higher ends of the spectrum because they need increased bandwidth for richer formats of communication that use higher data rates. Then there are a group of networks around the 868-900Mhz range which are generally focused on sending smaller packets, less often. These networks generally limit both the size of the communications and the number of communications in any given period. The design compromise is that this means they are only really suitable for fixed assets and sending tiny amounts of data.

There is a very important point about network congestion that is often missed. If the network generates a control channel, then the difference in power consumption for a device looking for a control channel in an area of high interference as opposed to clear air is around 300% in terms of power usage. You could equally say this means it takes three times as long, as radios generally use the same amount of power to listen as to transmit and therefore power and time are interchangeable to a degree. The effect that is perhaps more subtle and often overlooked is the time impact on the network overall. Everything is taking longer. In highly congested areas, the communications therefore run slower or to put it another way, the communications are limited to the loudest devices, or in other words, the closest devices.

When you consider that that the maximum power on the 868MHz in Europe in the licence free ISM bands is 500mW, or half a watt, think about the impact this has on other users trying to do low power 868MHz solutions. There is a real danger of being drowned out.

Bluetooth is good at one to one connections over short ranges. It is in the 2.4GH range and therefore subject to high power consumption and really only line of sight connections. If you have a set of Bluetooth speakers and have been playing music from your iPhone over them, you will be fully aware of the limitations in both range and line of sight communications.

Some notable solutions like Aeroscout exist but fundamentally limited by the frequency range. At 2.4GHz it does not travel far or penetrate well. Also, tends to be power hungry. Ultimately, it is the same frequency range give or take as Bluetooth.

After all the hype a serious flaw was found in its mesh networking protocol. The concept is good, a low power WiFi communications solution for devices that can ‘mesh’ together. ‘Meshing’ in this case is the ability to forward messages between the nodes. This is an adaption to the limitation of low power WiFi communications where typical ranges are only 10-100m.

2G might be continued for as much as ten years in the UK but already service levels are dropping. 2G is a TDMA based architecture, which stands for Time Division Multiple Access. Although both TDMA and CDMA can work perfectly well without control channels, in all the commercial applications discussed in this document, they are all implemented with control channels.

2G has been the standard for M2M or machine to machine SIMs for many years. Extensive experience has shown how good and reliable this network has been, particularly across Europe. The real issue today is that the business case for the networks is based around the £15 monthly subscription for the smart phone user and this is driving 4G at the cost of 2G. There are some two million 2G devices in the UK that are now suffering from the re-mapping of the networks. Many users are also aware of the gaps in the network that have appeared. The problem for the corporate user is how to swap out the 2G solutions for something else. Typically, if you have tens of thousands of devices any swap out takes years. Add to this a few years of testing and development up front and the 2G demise in 2020 to 2025 seems like tomorrow.

This is the ugly child of the radio world – likely to be turned off with or even before 2G, in Europe. This is CDMA, which stands for Code Division Multiple Access. America will probably hang onto 3G for some time given that they have pretty much already turned off 2G and a 4G roll out will be a massive investment, on top of the fact they have really only just finished the 3G roll out.

Really good but mostly wants to be on 2100MHz so won’t generally work well for asset tracking and security as 2100MHz does not penetrate reinforced concrete structures well. It is a better use of the radio spectrum than 3G but until recently it could not do voice. It now has a voice over IP solution so 3G can be turned off, as its only reason d’etre was to provide voice once 2G went. 4G is LTE. LTE means Long Term Evolution and is based on OFDM or Orthogonal Frequency Division Multiple Access. (curiously someone was granted a trade mark on OFDMA, so it is just OFDM).

Sigfox has taken 134 million euros in investment and is currently out looking for a further 200-300 million euros. They typically charge 5-20 euros a year for network access. Sigfox is aimed at mostly infrastructure and monitoring as opposed to asset tracking and security. There is a maximum of 140 messages a day. (Most asset recovery operations need hundreds of messages in a few hours to bring them to a successful conclusion).

Sigfox is aimed therefore at providing connectivity to masses of fixed devices that only need to send small amounts of data back to base. An important feature of the network is the low power element that means the end user device can be small and low cost. The design compromise here is that the basestation needs to be a bigger, more sophisticated piece of equipment to compensate for this.

Another important element is their move to 868MHz, which brings with it less penetration and reflection than is found on 433Mhz.

LoRa is aimed at providing low power, wide area network solutions. It is as the name suggests an alliance of different companies creating a standard. Reading between the lines it is an improvement on many of the concepts and ideas first proposed in Zigbee. The issue with this technology as proposed is that there is not much to sell today or for potential customers to get their hands on. Talking to major corporate clients, LoRa really hasn’t emerged yet as a technology to adopt, it is still in its infancy.

Mostly 900Mhz to make use of the old 2G spectrum. It will not launch until 2018, only at the early design stages. A little like Sigfox in that it is built for sending very small data packets. Vodafone will probably be the first provider in the UK. Expect normal 2G costs but no voice and very limited packet size. This is a TDMA based solution.