updated 06:50 pm EDT, Mon October 24, 2011
Offers lower power usage, latency, more
Bluetooth 4.0, introduced in the latest models of MacBook Air, Mac mini and the iPhone 4S among other devices, is getting a re-branding courtesy of the working group that controls the technology. The 4.0 spec will now be referred to as "Bluetooth Smart Ready" for devices that use a dual-mode radio that can handle both the new spec and the "classic" Bluetooth abilities, while the tag "Bluetooth Smart" will refer to dramatically lower-power devices that use a single mode 4.0 radio only.
Bluetooth Smart devices would typically be things like pedometers or heart-rate monitors that run on button-cell batteries or were designed primarily to collect very specific bits of information. The low-power radio users less than half the energy of classic Bluetooth overall and can get down to as little as one one-hundredth the power requirement when idle. In standby mode, a low-power Bluetooth Smart device could run off the coin-sized battery found in a "feature" cell phone for over a year.
Bluetooth Smart Ready devices would be more capable, and are the type used in new Macs, some HDTVs and other complex devices that need to handle a variety of tasks. Both the low-power and more complex devices gain benefits from the Bluetooth 4.0 specification, including tougher encryption and dramatically lower latency -- down to six milliseconds from the present 100ms -- making future Bluetooth multimedia devices more responsive as well as more secure, all while still using much less power than before.
The Bluetooth SIG expects Bluetooth device shipments to rise to over two billion over the next two years, fueled mainly by single-purpose, low-power devices that are market-specific (from exercise sensors to proximity alarms) as much as by the more popular consumer electronics like iPhones and iPads. The secret behind the new specification's power savings is a new, low "pulsing" method of communication that keeps devices aware of each other without continuous information.
The low-power devices that use a single-mode radio make some compromises compared to classic Bluetooth to keep costs low -- including a shorter working range (to 160 ft from 330 feet in classic Bluetooth 2.1+EDR) and a slower data transmission speed (one megabit per second steady rather than the 1-3Mb per second of classic) and lower application throughput, but for the devices that opt for the single-mode radio these limitations are not an issue.
The designations of "Smart Ready" and "Smart" are also intended to inform consumers of a given device's capabilities, and make it easier for them to manage devices. Bluetooth Smart Ready devices are fully backward-compatible with older Bluetooth devices as well as other "Smart Ready" devices, while Bluetooth Smart devices can only connect to Bluetooth Smart Ready devices (see chart, below).
The new branding will be rolled out in concert with new devices that take advantage of Bluetooth 4.0 specifications.