The benefit of license-free spectrum
One of the most significant costs is that of the network itself. This itself has a number of elements. The first of these is obtaining suitable spectrum. Conventionally, M2M solutions have been developed around legacy telephony based technologies – GPRS, 3G and LTE. Not only are these technologies not optimal for most IoT applications but spectrum licensing costs are significant – for example the cost of spectrum for a UK-wide cellular network would be $1-2billion. The high cost of access to the radio spectrum inevitably translates into a corresponding high cost of data transmission for the end user.
Weightless technology is frequency agnostic and can operate across different spectrums – importantly including licence exempt spectrum with zero access costs. Weightless-W is designed to operate in TV white space spectrum, Weightless-N is designed to operate in Industrial, Scientific and Medical (ISM) bands.
Longer range, fewer base stations
Range is another element with a strong influence on the cost of network deployment. Range translates proportionately to cell size and therefore the number of terminal devices that can be associated with one base station. The fewer the base stations needed in any given network, the lower the overall network cost.
Both Weightless-W and Weightless-N technologies are capable of range equivalent to and better than GPRS, 3G and LTE. Excellent signal propagation characteristics mean long range and excellent penetration of signal into buildings. Typically an urban range to terminals mounted internally is around 5km whilst a LoS rural implementation will typically achieve 20 – 30km.
Whether you are developing a network that you will operate or you are designing applications to connect to an existing network managed by another operator, low network installation costs lead to lower tariffs to each user of the network. The capital expenditure (CAPEX) for a network is considerably less than for an equivalent traditional cellular technology. BTS hardware typically costs less than USD$3000. Using the typical range figures that means that an 80 square km urban cell or a 2800 square km rural cell can be served from a single base station.
Weightless devices have been designed so that they do not send much data, and do not greatly load the network. Sensor-style devices may only wake up once every 15 minutes, or even less frequently. This will allow a tariff that charges only a small amount for when a device is communicating, and nothing at all when it is not, because the loading it places on the network is very small. This very low operational expenditure (OPEX) will make it possible to achieve the sub-USD$10/year subscription fees needed to meet M2M systems requirements.
Low cost hardware
The Weightless-N specification requires no exotic, high cost components to implement at either end of the link. Commodity transceiver and microcontroller devices together with a regulator, crystal, a small number of passives and a low cost antenna mean that modules can be produced for around USD$2.
The Weightless-W specification has been created in such a way that it can be implemented on a chip costing just USD$1-2 in volume.
Low cost deployment and maintenance
Fit and forget pricing of modules is complemented by the low power requirements for Weightless terminals making battery operation feasible. Battery powered devices avoid costly deployments requiring a connection to the grid whilst battery lives from 5 to 10 years mean less truck roll on scheduled maintenance.
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