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ANT+ and Bluetooth Low Energy in Phones and Sensors

On March 11, 2011, in Interesting Reads, by Brandon Keller

Digifit No Longer Supports ANT+. Switch to BLE today!

Here at Digifit, we like to stay on the cutting edge of ultra-low power wireless technology.  Digifit currently uses the fitness industries leading open standard for ULP digital wireless called ANT+ and we are a proud member of the thriving ANT+ Alliance. However, a new contender will soon step into the ring with the debut of Bluetooth Low Energy in 2011. 

The first devices with Bluetooth Low Energy are expected to be released soon and are expected to reach high volumes of use in applications where it is technically capable. Digifit will support BLE as it emerges. This is the first in a series of blog posts looking at these two technologies in progressively more detail.

What is ANT?
ANT is an ultra-low power (ULP) wireless protocol.  ANT is built into leading edge 2.4 GHz radio chips from suppliers such as Nordic Semiconductor and Texas Instruments. By itself, it does not provide for interoperability among various manufacturers devices.

What is ANT+?
ANT+ is an open standard, which enables interoperability among devices by defining the network parameters and data formats used by that device type (e.g. a heart rate monitor). These parameters and formats are defined in ANT+ Device Profiles. ANT+ always runs on top of ANT so I will refer to the pair as ANT+. There are approximately 14 million ANT+ device in the market to date (Mar 2011).

What is Bluetooth Low Energy?
Bluetooth Low Energy (BLE) is an ultra low power wireless protocol that comes loaded into BLE radio chips.  BLE interoperability will be achieved by device profiles, which will come from the Bluetooth Special Interest Group (SIG) committee.

What is Similar Between ANT+ and BLE?
Both ANT+ and BLE use 2.4 GHz radio hardware, providing for small size and low cost hardware radio (chip and antenna) implementations.  Each of these technologies can also be used in “stand alone” mode where only the ULP radio is implemented into a chip for use in sensors and built into multi mode communication chips (MMCCs) which also contain WiFi and Bluetooth. This is essential to their adoption in cell phones and other mobile devices which will not tolerate adding yet another radio chip and antenna. 

What are a few key differences between ANT+ and BLE?

ANT+

BLE

Provides for complex network topologies making it more flexible and applicable in more advanced use cases.

Supports simple star network topology only

Small software stack (16KB memory size). Memory costs money and time spent in the stack costs power.

Larger (128-256 KB) software stack. Memory costs money and time spent in the stack costs power.

Low protocol overhead = high data to overhead ratio which means less radio on time for a given amount of data which saves power on both sides of the link.

Much higher messaging overhead without additional functionality which consumes more power per data byte transmitted and received.

Highly defined and optimized search mechanisms

No defined search process leaving it up to individual chip vendors to define and ensure interoperability with the other chip vendors.

Built in file transfer protocol developed for open use

Relies on Bluetooth technology for file transfers, which cannot operate on coin cell batteries

Availability and Capability of ANT+ and BLE
ANT has 17 proven fitness and health Devices, the ANT+ Alliance has almost 400 members, and ANT has a large market share in the current generation of smart phones.  BLE is still in the developmental stage, so it remains to be seen when and how it will compete with ANT+

Status and Advantages of BLE
The BLE base protocol is defined in the recently released Bluetooth V4.0 specification and most of the leading multi mode communication chip vendors (MMCCs are used in mobile devices to provide WiFi, BT, etc connectivity) will include hardware support for BLE in their next generation chips. BLE will benefit from the strong brand and marketing associated with Bluetooth so it will eventually see wide spread adoption in uses cases where it is technically capable.

For more information, check out the Bluetooth webpage on Bluetooth Low Energy



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