In a hyper connected world, the IoT market covers a wide range of application areas with hundreds of forecasted potential applications. This wide range of applications areas can be grouped into larger IoT domains such as Agriculture, Transportation & Logistics, Environment and Energy, Industry, Security etc …). Each of these smart domains implying wireless M2M applications may include distinct technical or operational features that have particular implications for radio spectrum. One attempt in this serie is to elaborate key parameters essential for this consistent and comprehensive grouping of applications that could have similar characteristics in terms of potential impact on future demand for radio spectrum.
The term M2M essentially refers to the automated transmission of data between electronic devices, however the precise scope of the term can vary considerably depending on the assumed degree of human interaction with the devices.
Figure 1: M2M and Human interactions
Starting with primary application characteristics that are likely to have a particular impact on spectrum requirements, in terms of the transmission range, bandwidth and quality of service required helps a lot to apprehend the structuration of this intended grouping. We have identified a further set of secondary additional characteristics which have a less direct impact on spectrum use but may nevertheless impact on the user’s choice of technology or frequency band. These primary and secondary characteristics are described below.
- Applications Characteristics relating to transmission range
These characteristics are those that we consider primarily influence whether an application favours a short range or wide area technology. The primary characteristics falling into this category are:
- Location: g. indoor, deep indoor, outdoor, in-vehicle
- Geographic Coverage: local, national or international
- Geographic Distribution:g. highly concentrated at particular locations or widely dispersed
- Range: personal body area, local area, metropolitan area or wide area connectivity
- Degree of Mobility: static, nomadic or continuously moving
Figure 2: main deployment location of M2M applications
- Applications Characteristics relating to bandwidth
These characteristics are those that we consider primarily influence whether an application favours a narrow band or wide band technology. The primary characteristics falling into this category are:
- Peak Bit Rate / Throughput: For our analysis we have placed each application into one of four categories, namely: <16 kbps, up to 144 kbps, up to 2 Mbps and >2 Mbps
- Data volumes: Uplink and Downlink traffic size per year, per connection in MB
- Duty Cycle: The percentage of time that a device is transmitting and/or receiving data during an established event transmission
- Software and Firmware Update requirements: whether over-the-air updating of software or firmware is required.
M2M applications are predominantly narrow band, with only a small minority exceeding the peak bit rate of 144 kbps. Many applications have a bit rate of 16 kbps or less and are hence able to utilise narrow band technologies such as Sigfox. The amount of traffic per event is generally low (below 100 kB), although a small minority of applications convey very large volumes (10 MB or more). In most cases less than 100 events per day are generated and most traffic is either generated in response to specific events or on a regular, repetitive basis. The transmission duty cycle during an event is less than 1% for the majority of applications.
Unlike most wireless data applications, M2M applications tend to be uplink biased. This is illustrated in the following chart which categorises applications in terms of the percentage of total traffic generated being in the uplink direction. It can be seen that a large majority of applications are uplink dominated and in many cases significantly so, with 90% or more of the traffic flowing in the uplink direction. This is in direct contrast to most cellular network data traffic, which is typically 90% downlink traffic.
Figure 3: percentage of total traffic carried in the uplink for M2M applications
- Applications Characteristics relating to Quality of Service
These QoS characteristics are those that we consider primarily influence whether an application is likely to require priority access to connectivity (e.g. through network service agreements or reserved spectrum):
- Security: Does the data sent to or from the application need to be subject to security measures, e.g. authentication, authorisation and encryption?
- Criticality: How important is it that the data sent to or from the application is received?
- Sensitivity to Delay: How will the application be affected by a delay in receiving or transmitting data?
- Sensitivity to Error: How will the application be affected by communication errors, leading to partial or full loss of data sent to or from the application?
Of the + hundreds of applications analysed, a clear majority have either high or very high security requirements and approximately half fall into the high or very high criticality categories, suggesting an enhanced network quality of service would be required. By contrast only a minority (about a third) of applications have high or very high sensitivity to delay or error.
- Other characteristics that may affect spectrum use
A number of other characteristics have been identified that may also have an influence on the way in which spectrum is used by an M2M application, e.g. in terms of the preferred frequency band or technology. These are summarised below:
- Extent of deployment: Is the application developed and used in specific markets – national, regional (e.g. EU), or global?
- Application Lifecycle: What is the intended lifecycle of the application (i.e. before being superseded by new applications or by the device having to be replaced)?
- Power requirements: Whether the application is predominantly designed for battery, permanent or potentially harvested energy (self-sufficient).
- Accessibility: Will the device be easily accessible to allow for servicing and maintenance of the device as well as manual firmware/software updates?
- Size and cost may also influence the choice of technology and/or frequency band.