Weightless (wireless communications)
Weightless was a set of low-power wide-area network (LPWAN) wireless technology specifications for exchanging data between a base station and thousands of machines around it.

History 
An event was held at the Moller Centre in Cambridge, UK by Cambridge Wireless on September 30, 2011.
Presentations were given by Neul, Landis+Gyr, Cable & Wireless, and ARM Holdings.
The technology was promoted by the Weightless Special Interest Group (SIG), announced December 7, 2012. The group was led by William Webb, a professor at Cambridge and a founder of the company Neul.
Another event was held in September, 2013, about when a version 1.0 was published.

The name Weightless was chosen to reflect the low overhead per transmission for devices that need to communicate just a few bytes of data.
The Weightless logo appears as uppercase letters with the 'W' appearing in the top-right corner of a light blue box that has a solid blue line above it.

In September, 2014, Cambridge-based Neul was acquired by Huawei, for an estimated $25 million.
By  2015, the company Nwave Technologies announced deployments in Copenhagen, Denmark and Esbjerg, Denmark. However, observers noted no products on the market.
A company called Ubiik, based in Taiwan, announced pre-orders in 2017.

Implementation 

Weightless-N is designed around a differential binary phase shift keying (DBPSK) digital modulation scheme to transmit within narrow frequency bands using a frequency hopping algorithm for interference mitigation and enhanced security. It provides for encryption and implicit authentication using a shared secret key regime to encode transmitted information via a 128 bit AES algorithm. The technology supports mobility with the network automatically routing terminal messages to the correct destination. Multiple networks, typically operated by different companies, are enabled and can be co-located. Each base station queries a central database to determine which network the terminal is registered to in order to decode and route data accordingly.

Weightless-W uses time-division duplex operation with frequency hopping and variable spreading factors in an attempt to increase range and accommodate low power devices in frequency bands, or channels, within the terrestrial television broadcast band. Channels that are in use by a nearby television transmitter are identified and left unaffected while channels not being used for broadcasting television can be allocated for use by Weightless devices.

A network of base stations communicate with the Internet, or a private network, in order to pass information from devices to a computer system; and to pass information back to the devices. The downlink to devices uses time slots (TDMA) and the uplink to the base station is divided into sub-channels so that several devices can communicate to the base station.

Originally, there were three published Weightless connectivity standards Weightless-P, Weightless-N and Weightless-W. Weightless-N was an uplink only LPWAN technology. Weightless W was designed to operate in the TV whitespace. Weightless-P, with bi-directional, narrowband technology designed to be operated in licensed and unlicensed ISM frequencies, was then just called "Weightless".

Communication and connection 

A base station transmits a Weightless frame which is received by a few thousand devices. The devices are allocated a specific time and frequency to transmit their data back to the base station. The base station is connected to the Internet or a private network. The base station accesses a database to identify the frequencies, or channels, that it can use without interfering with terrestrial television broadcasts in its local area.

Weightless is a wireless communications protocol designed for what is called machine to machine (M2M) communications known as the Internet of things – over distances ranging from a few metres to about 10 km.

Related technologies 
Other technologies which use the channels not used for terrestrial television broadcast in a particular area are also being developed. One is Wi-Fi under the standard IEEE 802.11af.
The IEEE 802.22 standard defines a MAC and PHY layer for TV white spaces that complies with the FCC and international standards for broadcasting in this spectrum. It also defines general protocol model for negotiating and selecting shared spectrum band for device operation. A Weightless Radio implementation would comply with this standard to cooperatively share the available spectrum.

Another technology is developed by the company Sigfox.

Specifications and features 
The original Weightless specification was developed for machine-to-machine, low-cost, low-power communication system for use in the white space between TV channels in 2011 by engineers working at Neul in Cambridge, UK. The Weightless-W specification is based on time-division duplex technology with spread spectrum frequency hopping in an attempt to minimise the impact of interference and with variable spreading factors in an attempt to increase range (at the expense of lower data rate) and to accommodate low power devices with low data rates.

Weightless v1.0
The formal Weightless-W Standard was published in February 2013. The Weightless-N Standard was published in May 2015. 
In networks using Weightless-W technology a base station queries a database which identifies the channels that are being used for terrestrial television broadcast in its local area. The channels not in use – the so-called white space – can be used by the base station to communicate with terminals using the Weightless-W protocol.
Terminal endpoints were designed to be low-cost devices using minimal power so that they could work autonomously for up to several years.

Air interface 
The Weightless-W protocol operates in the TV channels band. The Weightless-W protocol divides the band into channels. A database is queried by a base station to determine which channels are in use by terrestrial television broadcast stations in the area, and which ones are free for use by white space devices (such as those using Weightless). A range of modulation and encoding techniques are used to permit each base station to communicate at a variety of speeds with terminals, some of which may be nearby and others several km away. Data rates may vary depending on the distance and the presence of radio interference – the typical range is alleged to be between about 0.1Mbit/s and 16Mbit/s. The design of the air interface and protocol minimises the costs of the equipment and its power consumption. A broadband downlink from a base station to a terminal uses single carrier in an unused 6 MHz (for USA) or 8 MHz (for UK) TV channel.

See also 
Wimax
Telemetry
DASH7

References

External links 
 
 White Space Networks and Machine-to-Machine (M2M) Services  at Oxford University

Mobile computers
Networking standards
Wireless