Current visions for the IoT space have taken on a broader perspective, with more emphasis on post-processing of accumulated data. This has led to the need to connect individual applications to cloud storage and enable remote control via the internet.
The scale of the required network is potentially mind-boggling – and making this scenario a reality depends on absolutely reliable connectivity, designed in from the start and well tested all along the product lifecycle.
If recent trends continue, only some devices will use wired connections – USB, Ethernet, fibre – and a majority of IoT things will rely on wireless technology. This will range from near-field communication (NFC) for mobile payments, to geosynchronous satellites for unattended remote weather stations, and everything in between: Bluetooth, wireless LAN (WLAN), ZigBee, point-to-point radio, cellular, and more. The network will need to cope with all kinds of unique devices with different communication requirements. At one end will be simple wireless devices such as battery-powered sensors and actuators that will transmit very little data while operating unattended for several years. At the other end of the spectrum – literally and figuratively – will be high-bandwidth, mission-critical services and devices such as autonomous cars that require constant, reliable and super-secure connections. Key to uniquely identifying each device is a vast IP address space. Because the IPv4 addressing space is too limited, currently requiring the use of concentrators (e.g., routers and gateways), the end-to-end use of IPv6 addressing is a key enabler for IoT devices. With its virtually unlimited address space, IPv6 allows unique addressing of billions of devices.
Accessing gateways to the cloud
Server/cloud-based big-data analytics and machine learning are central to the majority of IoT business models. IoT uses M2M communication to harvest data and route control messages between widely distributed things (e.g., sensors or actuators) and cloud-based intelligence. Many topologies include gateway nodes as aggregation points between thing and cloud (Fig. 1).
Gateways vary in complexity. For example, a WiFi access point includes an IP router and may also include translation from Ethernet and WiFi to ADSL or another fixed-line protocol. More complex gateways can include significant computing resources programmed with “edge” or “fog” applications capable of local decision making. Where communication costs are low and latency can be tolerated, IoT implementations tend to use simple gateways and then route most of the data to the cloud for analysis and decision making. In situations that have either high communication costs are demanding latency requirements, complex gateway nodes are often specified. These gateways can be remotely maintained and configured, and they will monitor and control a local constellation of things. Traffic routed to the cloud may include infrequent status updates or alerts when locally monitored thresholds are crossed (e.g., a temperature exceeding a maximum level or an intruder tripping an alarm).
Many wearable applications and some home-automation applications make use of smartphones to provide a user interface or act as a gateway node. The almost ubiquitous availability of WiFi makes it the first choice for many IoT applications. Where fixed-line or WiFi links are unavailable, cellular protocols are frequently used. In wearable applications and for home automation around the smartphone, Bluetooth is often used. NFC is the natural choice when security is aided by proximity. ZigBee, Z-Wave and Thread offer robust, low-power mesh networks for home automation and smart energy devices. ISA100.11a and WirelessHART include frequency hopping for improved resilience in safety critical industrial applications. Emerging low-power wide area (LPWA) technologies such as LoRa and SIGFOX combine the cost, low complexity and low power benefits of technologies such as ZigBee, but with much longer range enabled by narrowband, low data rate protocols.
Mapping technologies versus operating range
Fig. 2 shows an example of IoT technologies grouped by operating range. Terms such as proximity, WPAN, WHAN, WFAN, WLAN, WNAN, LPWA and WWAN are used within the radio-standards community to provide general indications of range. Many formats are available for short-range connections between devices and gateways. To facilitate future development, standards are quickly forming and evolving as new devices become connected. Currently, there are more than 60 legacy and new RF formats in use for M2M and IoT–related applications. Some, such as Bluetooth, WLAN and cellular, are already widely used. Others, such as ZigBee and Thread, are emerging in specific market niches.
To accelerate their products to market, some companies developed proprietary solutions that were relatively easy to create because they had low data rates, low-power transmissions and minimal interoperability requirements. This approach is likely to fall out of favor because the globalization of markets is driving device communication away from proprietary designs and towards standardised solutions.
Scanning the most promising technologies
Fig. 2 spans several technologies: proximity, WPAN, WHAN, WFAN, WLAN, WNAN and WWAN. Each includes one or more noteworthy connectivity standards. Where available, each overview includes a link to deeper information. Proximity: Near-field communication (NFC), which is a very short-range system based on ISO 14443 at 13.56 MHz, is used for ticketing, access control, passports and, increasingly, for mobile payment systems. Payment applications are regulated by EMVCo while many other applications are regulated by the NFC Forum. NFC devices can behave as terminals, also called proximity-coupling devices (PCD) or readers.
They may also behave as cards, also known as proximity inductive-coupling card (PICC) or tags; cards are often powered by the RF field generated by the terminal. The NFC Forum has added logical link control protocol (LLCP), simple data-exchange format (NDEF) and simple data-exchange protocol (SNEP) to enable peer-to-peer communication (e.g., between two mobile phones). To learn more, please visit www.emvco.org and www.nfcforum.org.
WPAN: In the IoT space, Bluetooth low energy (BLE) is of greatest interest. Designed for lower data throughput, it significantly reduces the power consumption of Bluetooth devices and enables years of operation using coin-cell batteries. Simplified models for device discovery, service discovery and data exchange result in a radio that needs very little airtime, greatly reducing power consumption. This enables use of BLE in small devices such as watches, health monitors and battery-powered appliances. For more information about BLE, please see the Bluetooth Special Interest Group (SIG) website at www.bluetooth.org.
WHAN: To simplify development, a number of short-range wireless technologies use IEEE 802.15.4 as the physical (PHY) and media access control (MAC) layers. For the variants shown in Fig. 3, the developer of the higher layers specifies the higher-level protocol that is appropriate for the target application.
This low-rate WPAN (LR-WPAN) supports rates that range from 20 to 250 kbps. It is designed for home networking, industrial control and building automation, all of which need low data rates, low complexity and, in many cases, long battery life. To learn more, see www.standards.ieee.org/about/get/802/802.15.html.
ZigBee: Established in 2002, ZigBee is widely used in commercial applications. These devices are able to connect, exchange information and disconnect quickly before returning to sleep mode. One key attribute is the use of a mesh network topology that can include thousands of nodes.
Radios operate with very low duty cycles, enabling sensing and monitoring applications to run for years on inexpensive batteries. Target applications include smart energy, home automation, healthcare, retail, and lighting control, each of which has a specific ZigBee profile and certification. Its transmitter and receiver specifications appear in section 10.3 of the IEEE 802.15.4 specification. More information is available at www.zigbee.org.
Thread: The Thread Group was launched in July 2014 and is growing quickly. This technology is similar to ZigBee in that it is based on the IEEE 802.15.4 PHY and MAC; however, it uses the IPv6 over low-power WPAN (6LoWPAN) protocol. It’s a robust, encrypted mesh network designed to connect – securely and reliably – up to hundreds of home-automation products and devices.
The network is self-healing and is configured such that there is no single point of failure. Its short messaging conserves bandwidth and power, while a streamlined routing protocol reduces network overhead and latency. To get the details, see www.threadgroup.org.
WLAN: WiFi is the most widely used wireless internet connectivity technology, with 802.11a/b/g/n being most common today. Fig. 4 shows the main amendments to the PHY layer in each version. Two recent amendments address the need for very high throughput data rates: 802.11ac, which operates below 6GHz and is becoming the standard in mobile phones, tablets and PCs; and 802.11ad, which operates in the 60 GHz band.
802.11ah: The upcoming introduction of 802.11ah is intended to support low energy for IoT applications. It uses low power and low data rates, and because it operates in the sub-gigahertz band, it has a range of up to 1 km.
802.11p: Also called wireless access in vehicular environments (WAVE), 802.11p has been created specifically for wireless access to vehicles. In a connected car, it opens the door to applications such as telematics, roadside assistance, fleet management, and young-driver insurance validation.
In the future, 802.11p will also enable V2V and V2I connectivity for enhanced vehicle safety, traffic management and toll collection.
More information about all 802.11 variants is available online at www.ieee802.org/11.
For the full article see link: www.ee.co.za/wp-content/uploads/2017/03/IoT-enabling-solns-for-design-and-test-5992-1175EN.pdf
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