ANT (network)

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ANT
Developed by Dynastream Innovations Inc.
Industry Sports, health, home automation, industrial

ANT is a proprietary open access multicast wireless sensor network technology featuring a wireless communications protocol stack that enables semiconductor radios operating in the 2.4 GHz industrial, scientific, and medical allocation of the RF spectrum ("ISM band") to communicate by establishing standard rules for co-existence, data representation, signalling, authentication, and error detection.

The ANT protocol is designed and marketed by ANT Wireless, a division of Dynastream Innovations Inc. (a Cochrane, Canada-based company), which is subsequently a subsidiary of GPS equipment manufacturer Garmin.

The ANT protocol is available on low-power RF transceiver chips from manufacturers such as Nordic Semiconductor (since 2005)[1] and Texas Instruments (since 2010),[2] as well as combination connectivity transceiver chips from manufacturers such as Broadcom, MediaTek or Qualcomm used in cellphones, tablets, etc. Currently a typical ANT protocol transceiver is a black box that comes pre-loaded with the protocol software and must be controlled by an external application processor via a UART, SPI, or USB interface. New ANT transceivers are also available in a SoC where an external application processor is not required.

ANT is characterized by low computational overhead and low to medium efficiency,[citation needed] resulting in low power consumption by the radios supporting the protocol and enabling low power wireless embedded devices that can operate on a single coin-cell battery from months to years.

Overview[edit]

The applications for which ANT is targeted are characterized by periodic transfer of small amounts of sensor information between several, scores, or hundreds of interconnected devices in point-to-point, star, tree, or mesh network topologies. These applications are often constrained by strict power, footprint, and cost requirements. Typical applications measure parameters that don't change rapidly (for example, temperature or humidity), so updates every few seconds are satisfactory.

Commercial wireless sensor networks must be reliable, feature low power consumption (to extend battery life and minimize maintenance), and be low cost to purchase, install, and maintain.[3] In addition, transceivers in close proximity need to coexist in harmony by being able to transmit and receive without interference from their neighbors and other wireless devices operating in the 2.4 GHz band.

ANT-powered nodes are claimed to be capable of acting as slaves or masters within a wireless sensor network concurrently. This means the nodes can act as transmitters, receivers, or transceivers to route traffic to other nodes. In addition, every node is capable of determining when to transmit based on the activity of its neighbors.

Typical applications[edit]

ANT has been primarily targeted at the sports sector, particularly fitness and cycling performance monitoring. The transceivers are embedded in equipment such as heart rate belts, watches, cycle power, and cadence meters, and distance and speed monitors to form wireless Personal Area Networks (PANs) monitoring a user's performance.

Manufacturers such as Adidas, Garmin,[4] Geonaute,[5] Nike, Suunto, Fitbit[6] and Tacx[7] have used ANT technology in their performance monitoring products.

Recently, ANT (the company) has attempted to diversify, claiming ANT wireless sensor networking technology's low overhead, low power, interference-free characteristics, and operation in the 2.4 GHz ISM band suit applications in the health, home automation, and industrial sectors.

Technical information[edit]

The ANT protocol has an efficiency (determined by the ratio of overhead to data) of 47 percent.[citation needed] ANT can be configured to spend long periods in a low-power “sleep” mode (consuming of the order of microamps of current), wake up briefly to communicate (when consumption rises to a peak of 22mA (at -5dB) during reception and 13.5mA (at -5dB) during transmission)[8] and return to sleep mode. Average current consumption for low message rates is less than 60 microamps on some devices.[8]

Each ANT channel consists of one or more transmitting nodes and one or more receiving nodes, depending on the network topology. Any node can transmit or receive, so the channels are bi-directional.

ANT accommodates three types of messaging: broadcast, acknowledged, and burst. Broadcast is a one-way communication from one node to another (or many). The receiving node(s) transmit no acknowledgment, but the receiving node may still send messages back to the transmitting node. This technique is suited to sensor applications and is the most economical method of operation.

Acknowledged messaging confirms receipt of data packets. The transmitter is informed of success or failure, although there are no retransmissions. This technique is suited to control applications.

ANT can also be used for burst messaging; this is a multi-message transmission technique using the full data bandwidth and running to completion. The receiving node acknowledges receipt and informs of corrupted packets that the transmitter then re-sends. The packets are sequence numbered for traceability. This technique is suited to data block transfer where the integrity of the data is paramount.

Comparison with Bluetooth, Bluetooth Low Energy, and ZigBee[edit]

Versions of the Bluetooth prior to v4.0 were designed for music (the SCO and eSCO synchronous transports), rapid file transfer (ACL, asynchronous transport) between devices in a PAN such as a PDA, cell-phone, and portable computer that focused on applications with lower bandwidth requirements than that offered by WiFi. Previous and current versions of Bluetooth are not designed for large wireless sensor networks but were and still are capable of forming star networks of up to eight devices (one master and seven slaves).[9] In comparison ANT was designed for low bit rate, large scale sensor network topologies that require very low, coin cell class power consumption at every node.

Bluetooth 3.0 introduced the AMP controller which means that Bluetooth can use WiFi for quick and efficient transport when both technologies are collocated in one device. This is labelled as 3.0+HS. A Bluetooth 4.0+HS device can depending on selection of transports efficiently transport data using Low Energy, Standard Bluetooth or WiFi. Apple has recently qualified devices as 4.0+HS. Similar functionality on ANT can be implemented at the application level for any devices incorporating both ANT and WiFi (or any high data rate transfer technology). As well, ANT-FS or ANT File Share is a technical specification allowing larger file transfers to be performed in an interoperable fashion at up to 60 kbit/s over the ANT protocol.

Bluetooth SMART is a wireless specification including radio, link layer protocols, transport protocols and ways to describe data released for low power wireless embedded devices that can operate on a single coin-cell battery from months to years, such as Wireless Sensor Network, watches, and sports equipment similar to ANT. Currently, Bluetooth SMART supports a scatternets and broadcasting between devices. A mesh can easily be implemented on top of the scatternet. A single hop typically has communication range between 50 m to 100 m (330 ft). SMART is the hallmark feature of Bluetooth 4.0. Dual-mode core chip supporting Bluetooth and SMART will give SMART a quick start in the mass market of smartphones, laptops, tablets etc. This advantage of integration will also allow SMART to compete against other short range technologies, but in addition ANT has also benefited from this scale as ANT and SMART share similar RF characteristics, allowing manufacturers such as Qualcomm to include ANT as well in their connectivity devices for smartphones, tablets, etc. While SMART cannot currently compete with 6LowPAN, Zigbee, or WirelessHART (ANT can support mesh, but while most applications in sports are currently single hop, some devices are demonstrating usage of multi-hop such as bicycle pedal power meters, which connect pedal-to-pedal-to-cyclocomputer) in applications requiring a large multi-hop coverage area, SMART can compete in short-range single-hop applications. SMART has debuted in devices on the market late 2011 with notable support in the iPhone with Android support coming. Microsoft has also publicly stated their support for Bluetooth SMART and their first API's are in Windows 8. Bluetooth SMART chips are already in the mass market and provided by companies such as Nordic Semiconductor, Texas Instruments, CSR, Taiyo Yuden, Epson, Quintic, Broadcom, Qualcomm, EM microelectronics, ST and many more.[citation needed] In comparison, ANT debuted onto the smartphone market in late 2010 with Sony Ericsson entering the ANT+ Alliance, and is currently supported by a unified ANT Radio Service which provides a common interface for developers to create apps across Android versions and ANT hardware such as USB sticks connected through USB OTG. Samsung has also declared their support with the launch of the Galaxy Note 3 and joined the ANT+ Alliance in 2013.

A more direct comparison can be drawn with ZigBee. ZigBee is based on the IEEE 802.15.4 standard PHY and Media Access Control (MAC) layers, and supports the ZigBee Alliance's own Network (NWK) and Application (APL) layers (refer to the OSI model). ZigBee's IEEE 802.15.4 PHY for the 2.4 GHz frequency band has an on-the-air data rate of 250 kbit/s,[10] compared to ANT's 1 Mbit/s,[8] requiring ZigBee to stay on air longer than ANT to transmit a given volume of data.

Interference immunity[edit]

ANT, ZigBee, Bluetooth, Wi-Fi, and some cordless phones all use the 2.4 GHz band (as well as 868- and 915 MHz for regional variants in the latter's case), along with proprietary forms of wireless Ethernet and wireless USB.

Wi-Fi/ZigBee and Bluetooth employ Direct Sequence Spread Spectrum (DSSS) and Frequency-Hopping Spread Spectrum (FHSS) schemes respectively to maintain the integrity of the wireless link.

ANT uses an adaptive isochronous network technology to ensure coexistence with other ANT devices. This scheme provides the ability for each transmission to occur in an interference free time slot within the defined frequency band. The radio transmits for less than 150 µs per message, allowing a single channel to be divided into hundreds of time slots. The ANT messaging period (the time between each node transmitting its data) determines how many time slots are available.

ANT's adaptive isochronous scheme doesn't require a master clock. Transmitters start broadcasting at regular intervals but then modify the transmission timing if interference from a neighbor is detected on a particular time slot. This flexibility allows ANT to adapt to hostile conditions but ensures there is no overhead when interference is not present.

If the radio environment is very crowded, ANT can use frequency agility to allow an application microcontroller-controlled "hop" to an alternative 1 MHz channel in the 2.4 GHz band which can then be subdivided into timeslots.

ANT+[edit]

Main article: ANT+

ANT+ is an interoperability function that can be added to the base ANT protocol. This standardization allows for the networking of nearby ANT+ devices to facilitate the open collection and interpretation of sensor data. For example, ANT+ enabled fitness monitoring devices such as heart rate monitors, pedometers, speed monitors, and weight scales can all work together to assemble and track performance metrics. This data could grant a user a more holistic view of their fitness progress.

References[edit]

  1. ^ "Single chip ANT ultra low power wireless solutions". Nordic Semiconductor. 27 Oct 2010. 
  2. ^ "ANT - Ultra-low power wireless connectivity". Texas Instruments. 27 Oct 2010. 
  3. ^ "The Economist Special Report "A world of connections"". The Economist. 26 Apr 2007. Retrieved 11 Dec 2007. 
  4. ^ "Garmin Forerunner 50 press release". Garmin. 16 Mar 2007. Archived from the original on 26 December 2007. Retrieved 11 Dec 2007. 
  5. ^ "Geonaute, Experience Improved". Geonaute. 17 Dec 2011. 
  6. ^ "Fitbit Product Specifications". Fitbit. 27 Jan 2012. 
  7. ^ "How does wireless Bushido work". Tacx. 10 Oct 2009. 
  8. ^ a b c "Nordic Semiconductor figures for nRF24AP1". Nordic Semiconductor. Archived from the original on 29 October 2007. Retrieved 11 Dec 2007. 
  9. ^ "How Bluetooth Technology Works". bluetooth.com. Archived from the original on 20 February 2008. Retrieved 8 Feb 2008. 
  10. ^ "Ember figures for e250". Ember. Archived from the original on 15 December 2007. Retrieved 11 Dec 2007. 

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