Wireless options for the IoT: Page 2 of 5

January 08, 2019 //By Samir Hennaoui, Rui Ramalho, Murata Europe
Wireless options for the IoT
Wireless connectivity is the enabler for internet of things (IoT) applications. It provides the ability to place sensor nodes and actuators where they are needed and have them communicate with servers and other nearby devices as soon as they are in place. But wireless connectivity comes in many forms. The choice of network protocol can seem baffling at first but each of them has features that suit different markets and applications. Now that the market for IoT devices is beginning to mature, some of the protocols are also beginning to assume a leadership position, particularly for short-range wireless.

Bluetooth 5, launched in the summer of 2016, brought enhancements that include the ability to trade range against the maximum datarate. By using an adaptive protocol, the range can be extended to be around four times higher than that of Bluetooth 4.2 at a datarate of approximately 125 kb/s.

Assuming line-of-sight conditions outdoors, this range can approach 200m. Alternatively, for devices that are more closely spaced, the maximum datarate can reach as high as 2 Mb/s, although packet overhead typically reduces the peak achievable payload datarate to around 1.6 Mb/s.

For high-datarate IoT traffic, WiFi now offers a viable option. Transceiver costs have fallen dramatically and support for the protocol makes it possible to use conventional home routers for access to the internet instead of relying on specialised gateways.

WiFi, from the start, has been focused on delivering high-bandwidth communication to mobile devices. The availability of the 5 GHz band in addition to the 2.4 GHz industrial, scientific and medical (ISM) used by the original WiFi protocol, Bluetooth, 6LowPAN and Zigbee provides access to a less congested part of the RF spectrum. This is useful for applications that need continuous high-speed data transfer.

There are now multiple versions of WiFi available. Although many IoT applications, even those that need high bandwidth communication for real-time audio or video, can make use of the older variants of WiFi, it often makes sense to standardise today on the 802.11ac variant. This version caters for multiple antennas to boost aggregate datarates to at least 1 Gb/s on the 5 GHz band.

IoT devices that support 802.11ac will help maintain the maximum possible datarate by allowing the home or office router to make full use of antenna diversity. Falling back to a slower, older protocol can slow down the entire network when the IoT device is active.

Figure 2: BLE modules like the MBN52832 device can support the most demanding Bluetooth low energy IoT applications.

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