Many short-range technologies including Wi-Fi, Bluetooth, ZigBee and others aspire to play a role in the IoT/M2M ecosystem. However, islands of coverage, such as Wi-Fi provides, are not an option. Short range technologies cannot provide the coverage needed for applications such as automotive, sensors, asset tracking, healthcare and many more. Instead, they are restricted to machines connected within the home or office environments.
Even in these environments there are many good reasons why a wide-area solution is preferable. For example, an electricity supply company is unlikely to accept that its meter is only connected via, e.g. Wi-Fi, into a home network, which in turn connects to the home broadband.
Long range, in-building penetration
Coverage is typically more important for M2M than data rate. Radio signals in the lower frequency bands go further. Weightless technology is frequency agnostic but is typically deployed in sub-1GHz spectrum. Weightless-N operates in ISM frequency bands – 868MHz in Europe, 900MHz in the US for example, and Weightless-W operates in TV white space, a perfect low frequency band. This low frequency spectrum enables excellent propagation, at low power, and without needing inconveniently large or expensive antennas in terminal devices.
Superior propagation to cellular networks is a good starting point, but IoT/M2M signals need to penetrate deep within homes and other buildings. Smart meters, for example, are often in basements. It is more critical that all smart meters can be read than what the data rate of transmission is. Most buildings have a penetration loss for signals entering them of around 15-20dB; techniques used in the Weightless system design provide indoor coverage to machines where only outdoor coverage previously existed.
Propagation characteristics make for the perfect M2M network solution
Range not only affects network performance, but overall costs, too. Weightless’ ubiquitous coverage and extended range directly impacts on the cost of establishing IoT/M2M networks. As a result of the need to deploy relatively few cells, set-up costs are minimised for network operators.
These design considerations make M2M networks radically different in many respects from traditional telephony based technologies. The Weightless-N standard for ISM and Weightless-W standard for TV white space spectrum meet all of the requirements for IoT/M2M communications, including range and in-building penetration.
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