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Wireless specs vie to replace IR remotes

Posted: 04 May 2009 ?? ?Print Version ?Bookmark and Share

Keywords:wireless specification? IR remote control? Bluetooth 3.0?

The recently ratified Bluetooth 3.0 specification not only pushed the wireless interface's speed to 25Mbit/s but also defined a new function called Unicast Connectionless Data (UCD), putting it in direct competition with RF4CE, the wireless remote control specification that merged with the Zigbee Alliance efforts to replace IR remote controls.

While the rival interfaces were originally designed for different applications, TV makers will have to choose between them.

Bluetooth was considered too power hungry and its latency too high for remote controls, burning through a set of batteries in three months and delaying a second or more before registering a button push. However, the new UCD functionality in the 3.0 spec extends battery life to about four years and lowers Bluetooth's latency to milliseconds.

UCD "allows you to keep Bluetooth in sleep mode most of the time, to conserve battery life. Then when a key is pressed on the remote, rather than set up a formal Bluetooth connection with all the handshaking associated with establishing a connection, it just sends the data about the key over to the host and goes back to sleepwhich is why its called connectionless," said Steve McIntyre, senior product line manager for wireless personal area networking products at Broadcom.

Using Bluetooth 3.0 also enables additional capabilities for high-end TVs not possible with RF4CE such as hi-fi audio transmissions, network access to download TV schedules for display on the remote, push-picture for automatically uploading digital camera pictures to a TV and integration with Wi-Fi for transmitting high-bandwidth audio and video using a peer-to-peer connection controlled by Bluetooth commands, proponents claimed.

Bluetooth 3.0 also allows cellphones with music players to be virtually docked to TVs so that media played on a handheld device streams to TV speakers.

The best example of successfully using Bluetooth for handheld wireless controllers is the Wii game controller, according to Broadcom, which crafted a customized UDC version for Wii maker Nintendo, allowing Wii to tune Bluetooth for very low latency and long battery life. Those special modifications have been included in the latest Bluetooth 3.0 spec.

RF4CE cost advantage
RF4CE chipmakers like Freescale Semiconductor claim that Bluetooth is overkill for command-and-control applications traditionally handled by IR remotes. RF4CE was specifically designed to replace IR remote functions, solve lingering problems while increasing remote control range to over 1,000 feet compared to about 50 feet for IR and Bluetooth.

"RF4CE was designed to replace current IR remotes with increased functionality and to solve problems with IR reliability caused by [interference from LCD] back lighting, line-of-sight restrictions and only having to press a key once to get it to work," said Brett Black, commercial wireless manager for Freescale. "For that application, the ship has already left the dockvendors are already rolling out their first remotes for consumer products using RF4CE."

Freescale and its RF4CE rival, Texas Instruments, are working with major consumer electronic OEMs, Black said, not just on TV remote controls but also for set-top boxes and other devices that use IR remotes. Freescale does not make Bluetooth chips, but is pricing its forthcoming RF4CE chips below $2, with estimates that prices will dip below $1 within four years.

"You can build an IR remote control for less than a dollar, so I'm not sure that those same buyers will be willing to pay several dollars to use Bluetooth in that application," said Black. "RF4CE is not intended to run the high data rates of, which Bluetooth is capable, although you could do voice-level audio if you wanted to, but RF4CE was designed from the ground up for building inexpensive RF command-and-control devices."

The rivalry between RF4CE and Bluetooth is a chimera, according to In-Stat analyst Brian O'Rourke. He claimed that while Bluetooth 3.0 can be used for remote control applications, RF4CE leads in moving to consumer applications.

"This is very much an apples and oranges comparison: RF4CE is a low power, low data-rate replacement for today's IR remote controls, whereas Bluetooth 3.0 is optimized for the high-bandwidth wireless transmission of large amounts of data. They are about as far apart as you can get," said O'Rourke.

"Bluetooth 3.0 is an effort to increase its bandwidth, whereas RF4CE is a wireless master remote architecture for controlling not just your TV but your stereo system and elements of your PC cluster. I have not seen much interest in using Bluetooth for that application," O'Rourke added.

- R. Colin Johnson
EE Times

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