IoT Connectivity Technologies - Part II
From the set of solutions we have introduced in part I, we will only consider Wi-Fi 6/6E, Sigfox and LoRa as the most relevant worldwide for unlicensed spectrum and LTE-M, NB-IoT and 5G for the licensed spectrum.
What is Wi-Fi 6/6E
According to the Wi-Fi Alliance Wi-Fi 6/6E operates in the unlicensed sub-1 GHz frequency spectrum band and offers data-rates varying from hundreds of kbits/s to tens of Mbits/s and across distances of tens of meters to over a kilometre. It occupies a space between ultra-low-power, ultra-low-throughput and lower energy-efficient LoRa and Sigfox Wide Area Networks (WAN), the lower-throughput, shorter-range Personal Area Networks (PAN) such as Bluetooth/BT5, and the more power-hungry LTE Cat-M / Narrowband-IoT cellular networks that come along with data plans.
System integrators can leverage the same hardware and software assets already developed for traditional Wi-Fi radios, enjoy multi-vendor product offering and benefit from the Wi-Fi Alliance interoperability testing and certification programs. However, you only get the benefits of Wi-Fi 6 (also sometimes referred to as 802.11ax) if you have a Wi-Fi 6-enabled device connecting to a Wi-Fi 6-certified router. Security is part of the IEEE 802.11 enterprise-grade security standards: Wi-Fi 6 embraces the latest WPA3 security protocol along with encrypted messages and unique ID technology for secure boot implementation. High data-rates allow secure over-the-air firmware upgrades, and support UDP and TCP/IP protocols. Native IP support means that no bridges or gateways are required.
- backward compatibility
- Faster than older Wi-Fi versions using OFDMA
- Longer battery life through TWA (target wake time)
- Enhanced security protocol WPA 3
- Smaller range compared to 5GHz networks
- OFDMA (orthogonal frequency-division multiple access) requires the use of new generation access points and end-user devices replacing existing equipment
What is SigFox
The Sigfox technology was developed in 2010 by the start-up Sigfox (in Toulouse, France), which is both a company and an LPWAN network operator. Sigfox operates and commercializes its own IoT solution meanwhile in 31 countries and is still under rollout worldwide owing to the partnership with various network operators. Sigfox uses unlicensed ISM bands and offers an end-to-end IoT connectivity solution based on its patented technologies. Sigfox deploys its proprietary base stations equipped with cognitive software-defined radios and connect them to the back-end servers using an IP-based network. By employing the ultra-narrow band, Sigfox uses the frequency bandwidth efficiently and experiences very low noise levels, leading to very low power consumption, high receiver sensitivity, and low-cost antenna design at the expense of maximum throughput of only 100 bps. Sigfox initially supported only uplink communication, but later evolved to bidirectional technology with a significant link asymmetry. The downlink communication, i.e., data from the base stations to the end devices can only occur following an uplink communication. The number of messages over the uplink is limited to 140 messages per day.
- In deployment with a lot of traction
- Great relationship with vendors (TI, Silicon Labs, Axom)
- Power-efficient: no RX circuitry so sensors consume less energy
- Great for simple monitoring & metering applications
- Not an open protocol, limited to SigFox networks
- Minimal Built-in Security: 16-bit encryption
- Limited use cases: not appropriate for use cases where downlink communication is important
- FCC regulation: SigFox transmission is too long for the limit set by the FCC under Part 15. So, the architecture in the US is significantly different than the existing, tested ones in Europe.
- Potentially high levels of RF interference
What is LoRa
Optimized for equipment with limited resources that do not require high speed and require a battery life of several years, LoRa is used to control sensors and meters in many activity sectors. LoRa is a physical layer technology that modulates the signals in sub-GHZ ISM (Industrial, Scientific, and Medical) band using a proprietary spread spectrum technique. A LoRa-based communication protocol called LoRaWAN was standardized by LoRa-Alliance (first version in 2015). Using LoRaWAN, each message transmitted by an end device is received by all the base stations in the range. By exploiting this redundant reception, LoRaWAN improves the successfully received messages ratio. However, achieving this feature requires multiple base stations in the neighborhood, which may increase the network deployment cost. The resulting duplicate receptions are filtered in the backend system (network server) that also has the required intelligence for checking security, sending acknowledgments to the end device, and sending the message to the corresponding application server. Further, multiple receptions of the same message by different base stations are exploited by LoRaWAN for localizing end devices. For this purpose, the time difference of arrival (TDOA)-based localization technique supported by very accurate time synchronization between multiple base stations is used. Moreover, multiple receptions of the same message at different base stations avoid the handover in LoRaWAN network (i.e., if a node is mobile or moving, handover is not needed between the base stations).
- Large, influential members including Cisco, IBM, Kerlink, Actility, and SK Telecom
- Better security: AES CCM (128-bit) encryption and authentication,
- Flexible packet size defined by the user
- In deployment, most popular along with SigFox (over 100 commercial operators)
- Not ideal for private/customer-deployed networks
- Downlink capability is still limited
- Limited to Semtech-approved vendors
What is LTE-M
Long-term evolution machine (LTE-M) is derived from the 3rd generation partnership project (3GPP) 4G LTE standard in the licensed spectrum. It leverages the extensive LTE advantages in terms of efficient flat Internet protocol architecture, mobility, priority handling mechanisms, security, and a globally established base. It has strong ties with legacy 3GPP 2G and 3G networks, as well as a comparatively seamless migration to the upcoming powerful 5G solution. LTE-M can be efficiently utilized for a wide range of applications with varying range of bandwidths and latencies. It has considerable similarity to narrowband-Internet of things but has advantages in the terms of range of bandwidth, latency, and mobility. Its disadvantages include some complexity and cost for the end devices. For IoT applications requiring higher data rates, low latency, full mobility, and voice in typical coverage situations, LTE-M is the best low-power wide-area network (LPWAN) technology choice. And for IoT applications requiring deep coverage where latency, mobility, and data speed requirements are less stringent, LTE-M is a strong LPWAN contender as well. Overall, this versatility allows LTE-M to support an extremely wide array of IoT applications, which helps to increase volume and drive economies of scale.
- SIM/eSIM security
- Costs of end devices
- Data plan (subscription) in the licensed spectrum
- Operator based
What is NB-IoT
NB-IoT is a Narrow Band IoT low-power wide-area network (LPWAN) radio technology standard specified in Release 13 of the 3GPP in June 2016. NB-IoT can coexist with GSM (global system for mobile communications) and LTE (long-term evolution) under licensed frequency bands (e.g., 700 MHz, 800 MHz, and 900 MHz). NB-IoT occupies a frequency band width of 200 KHz, which corresponds to one resource block in GSM and LTE transmission. NB-IoT focuses specifically on indoor coverage, low cost, long battery life, and high connection density. It uses OFDM modulation for downlink communication and SC-FDMA for uplink communications. IoT applications which require more frequent communications will be better served by NB-IoT, which has no duty cycle limitations operating on the licensed spectrum.
The 3GPP recommends the integration of NB-IoT in conjunction with the LTE cellular networks. NB-IoT can be supported with only a software upgrade in addition to the existing LTE infrastructure. The NB-IoT communication protocol is based on the LTE protocol. In fact, NB-IoT reduces LTE protocol functionalities to the minimum and enhances them as required for IoT applications. For example, the LTE backend system is used to broadcast information that is valid for all end devices within a cell. As the broadcasting back-end system obtains resources and consumes battery power from each end device, it is kept to a minimum, in size as well as in its occurrence. It was optimized to small and infrequent data messages and avoids the features not required for the IoT purpose, e.g., measurements to monitor the channel quality, carrier aggregation, and dual connectivity. Therefore, the end devices require only a small amount of battery, thus making it cost-efficient. NB-IoT technology can achieve 10 years of battery lifetime when transmitting 200 bytes per day on average.
- SIM/eSIM security
- indoor coverage
- long battery life
- high connection density
- operator based
- It offers lower data rate (about 250Kbps download and 20Kbps upload) compared to LTE-M
- costs for operating in the licensed spectrum
What is 5G
The upcoming 5G technology is a fundamental paradigm shift from previous generations. In addition to handling human-oriented voice, data, and video-based applications at significantly higher performance and functionality, 5G is being defined to address M2M applications in the IoT space.
5G has little to do with classic mobile communications as we have known it up to now. 5G cellular network has been designed for the three different types of applications already mentioned above.
The International Telecommunication Union (ITU-R) has defined three application groups for 5G.
eMBB - Enhanced Mobile Broadband
Mobile broadband access with high data rates and low signal propagation times (4 ms user plane latencies). Essentially, Enhanced Mobile Broadband places the following requirements on the mobile network:
- high data transmission rates up into the double-digit gigabit range per user
- high transmission capacity per unit area both inside and outside buildings suitable for high device densities at mass events
- high mobility and no restrictions on the user experience when used in moving vehicles such as trains, cars, or buses
These requirements apply for services where particularly high data transfer rates are essential, such as video streaming. Especially when several customers in one cell request ultra-high-resolution videos, high capacities are needed. The same applies to augmented reality or virtual reality applications. This group is subsumed by the ITU as "Enhanced Mobile Broadband".
mMTC - Massive Machine Type Communication
Applications with sporadic and low data volumes, 10 sec latency. Simple and inexpensive to manufacture devices with low power consumption. Typically, networked sensors and remotely readable meters. Essentially, Massive Machine Type Communications places the following requirements on the cellular network:
- Support of a high device density per unit area
- low energy consumption of the terminals - i.e., long usage times in battery or rechargeable battery mode
- Low-cost production of terminal equipment
- Reliable mobile radio coverage even in unfavorable locations
- Fully autonomous operation of the devices
These requirements apply for much stronger networking in the industrial sector, the keywords here being "Industry 4.0" and "Internet of Things" (IoT). But smart devices with sensors are becoming more prevalent in the end customer sector. For example, the transmission of data from various home sensors - electricity, water, smoke detectors, monitoring, temperature, etc. - will also become more common. Although only small amounts of data are generated, the networking of thousands to millions of devices in one cell or access point places new demands on energy efficiency and reliability. The class for this is summarized by the ITU as "Massive Machine Type Communication" (mMTC).
URLLC - Ultra Reliable and Low Latency Communication
Applications with high data volumes that require availability, reliability, and very low signal propagation times (0.5ms user plane latencies). Essentially, Ultra Reliable and Low Latency Communications places the following requirements on the cellular network:
- Latency in the range of one millisecond or less
- Low error and packet loss rates
- High availability of the network technology
- Low failure probability of the communication link
These requirements apply essentially for remote control of machinery and equipment, real-time control of critical operations in manufacturing, energy networks, autonomous driving vehicles, and critical applications such as surgical procedures with augmented reality. The class for this is summarized by the ITU as Ultra Reliable and Low Latency Communication (URLLC).
The first one is the enhanced mobile broadband (eMBB). The second one is massive machine type communications (mMTC). This category is designed specifically for IoT applications. The last one is ultra-reliable and low latency communications (URLLC) which is made and tailored especially to be suitable for real time and safety applications.
However, there is no single 5G network. The requirements placed on the network by Internet of Things applications are too varied. For example, the requirements of the automotive industry, sensor network operators or smart city architects differ completely. Rather, a whole family of radio technologies exists for different requirements and different access options. A variety of new business models as described above are expected in vertical industries. Hence, 5G is to be understood as an umbrella term that encompasses various networks, technologies, and applications.
- SIM/eSIM security
- network slicing
- private and operator based
- High complexity
- Costs of licensed spectrum