08 February 2011
The battle for the ultra low power wireless network market
Traditionally, embedded applications requiring low data rates and power consumption have relied on ZigBee and Bluetooth. However, an independent study claims that ANT powered network nodes use four times less power than a ZigBee node, while providing a simpler sensor and network development environment. So could ANT be the great white hope?
Dynastream Innovations, the company behind ANT, certainly believes so and has 'open book' disclosure of its battery life performance – claiming nodes can operate for years on coin cells, compared to days or months with Bluetooth and ZigBee.
As with other 2.4GHz technologies – Bluetooth Low Energy or RF for Consumer Electronics (rf4ce), for instance – ANT doesn't need line of sight to perform an operation. So, unlike long established infrared technology, an ANT+ remote control can control a device from any room in the house. The technology also allows more functions and information to be sent over the wireless link, such as displaying the name of a song on the remote control.
Because 2.4GHz is an unlicensed band, providing a robust service against common sources of interference required the use of a very short duty cycle. Volker Prueller, Texas Instruments' worldwide marketing manager for low power rf products, noted: "Adaptive frequency agility is available to provide an even more robust link, if desired by the application. ANT also has a patented time based mechanism for preventing cross interference between devices, allowing hundreds of nodes to coexist in the same rf space."
As an ultra low power wireless network solution, inevitable comparisons are going to be made with ZigBee, although ANT's wireless sales manager, Mike Paradis, believes there is no contest. "If ZigBee means the full stack, and not just the IEEE802.15.4 radio layers," he asserted, "then ZigBee is cumbersome, high power, fragmented – years of versions without compatibility – not dominant in its core market and the SIG based approach disallows free application development."
ANT already plays a major part in the digital sensing market for sports and fitness, with applications ranging from bike power sensors – 'ANT virtually owns that space', according to Paradis – to fitness equipment using proximity pairing.
Prueller concurred: "Over the last few years, ANT has become popular in the health and fitness space, especially since the introduction of the ANT+ interoperable networking technology." The standard has created an open platform of 18 device profile specifications that companies can design to gain access to the growing interoperable market. According to Paradis, it's built around the theory that the more vendors there are in a popular market, the larger that market grows. "More than 350 members of the ANT+ alliance can't all be wrong," he claimed.
While ANT is targeted primarily at the health and fitness market, it is not limited to that sector. "Typical use cases see a handful of connected devices per network," Prueller said. "ZigBee is really designed for larger mesh networks capable of scaling and supporting thousands of nodes with a corresponding group application layer profiles for smart energy, medical, building automation, Telecom Services and rf4ce."
While ZigBee focuses on ranges of up to 100m, ANT focuses on up to 30m and it's unlikely this range will be extended for the foreseeable future. "Body Area Networks do not make sense over that distance," Paradis asserted. "The cost of distance is power consumption and stack complexity, both of which affect BoM cost and user satisfaction."
That being said, ANT developers can add amplification and repeaters to extend distance, but no viable commercial use cases have appeared yet. "Multiprotocol solutions using bridge technologies best optimise the uses of any protocol," continued Paradis. "Texas Instrument's recent offering has a 4dB output and we expect 100m out of a good antenna design."
TI has a strong presence in short range wireless communications, with its low power rf products focusing on proprietary systems in markets with standalone rf transceiver products, as well as with single chip solutions integrating rf and mcus.
"ANT+ represents a significant installed base of low power wireless enabled sensors and will certainly continue to grow, so it made sense for TI to develop products for that market," explained Prueller. Indeed, during CES 2011, TI announced an ANT development kit for its CC2570 and CC2571 products, as well as the CC2567 – a dual mode solution offering a bridge between Bluetooth and ANT.
As part of an ANT+ Bluetooth Health and Fitness Aggregator Kit, the CC2567 is the first wireless single chip solution designed to enable direct short communication between ultra low power ANT+ enabled devices and commonly used mobile devices supporting Bluetooth.
The dual mode device requires 80% less board area than a design with two single mode solutions – for example, one ANT+ and one Bluetooth. And it has been designed to enable simultaneous operation over a shared antenna with built in coexistence, while increasing the wireless transmission range up to twice the distance of a single mode ANT+ solution.
So what exactly is ANT's place in the market? Paradis believes the industry has always settled into camps around IEEE standards for security of supply, vertical market focus or raw specs. "ANT has gained a lot of acceptance in vertical markets, based upon performance set by our early consumer product solutions and raw product performance," he observed. "Once we found second sources of silicon were possible due to our success, we were able to expand our 'fan club'. We explicitly calculate complete rf budgets, including cpu overhead for channel control and serial data handling overheads."
In such a competitive sector, it's no surprise there have been a number of hurdles to cross when trying to persuade new users to adopt ANT protocols. According to Paradis, the biggest barriers have been existing biases and beliefs. ANT has addressed these biases through demonstrations and anecdotal evidence.
"Data sheets and power estimators have extensive real world defined power consumption data," asserted Paradis. "Many competitors state power numbers on sensors, only using average currents and battery life claims derived from duty cycles of hours between messages, while neglecting the power budget of an always on receiver," he contended. "Coin cell battery to coin cell battery protocol design is not easy, but many inexperienced ODM design houses have claimed the ability to do this, but revert to ANT when they fail."
As the ultra low power wireless market continues to grow, Paradis is confident that ANT's technology and ANT+ interoperability function are having a major impact.
"We have already impacted the market," he concluded. "Bluetooth has had to envelop WiBree to try to compete in our space. It is basically mimicking how we have structured our protocol to attain the targeted ultra low power performance in Bluetooth Low Energy. Other 'standards' have reduced system overhead in their offerings to better compete. We have the majority of low power radio vendors soliciting us to license our technology."