Philips seeks to provide HAVi-based multimedia home networks through both wired and wireless implementations of 1394 but has "always believed the wireless solution is the Holy Grail," said Cees Jan Koomen, digital video group president at Philips Consumer Electronics.

Wi-LAN's technology contribution to the partnership helped achieve the data rates necessary for in-home multimedia networking. Philips Semiconductors, meanwhile, "brought to the table our 1394 technology and set-top expertise," said Benno Ritter, product-marketing manager for wireless connectivity products at Philips Semiconductors (Sunnyvale, Calif.).

Philips engineers modified the Ethernet interface of the Wi-LAN-developed W-OFDM device to yield a 1394 interface. Because it employs the 1394 packet size and time stamp, the proposed wireless scheme can seamlessly maintain 1394-based connectivity by wired or wireless means, Ritter said.

The demonstration system shown here features an MPEG-2 data stream generator that feeds a multiple transport stream into a Philips set-top box. The set-top converts the signal to an IEEE 1394 data stream and applies it to the Wi-LAN W-OFDM radio system. The Wi-LAN transmitter then sends the data stream over the air to the corresponding W-OFDM receiver.

On the receiver side, the IEEE 1394 data signal is demodulated and sent to two set-top boxes, which display the content of the different MPEG-2 data streams on two separate TV monitors.

The significance of the proposed wireless 1394 scheme is that it is potentially capable of offering a 46-Mbit/second raw data rate--and thus handling multiple MPEG-2 streams--at a distance far exceeding 10 meters. A/V clusters installed in different rooms could connect wirelessly through walls, Ritter said.

None of the currently available wireless home networking technologies fully fits the bill for such home entertainment applications as transmitting "continuous, guaranteed video streams," said Geert Christiaansen, program manager of the Philips Home Networking Group (Eindhoven, Netherlands).

Though the raw data rate of the Philips and Wi-LAN scheme is 46-Mbit/s , the net rate is 24 Mbits/s, after subtracting out the bit rates necessary for the W-OFDM headers and error correction (16 Mbits/s) and for the 1394 headers and error correction (6 Mbits). "We have not measured the actual distances that wireless 1394 can cover," said Ritter, "but considering the nature of W-OFDM originally developed for outdoor wireless applications covering up to 5 miles, we don't see any problems in covering a multiroom environment."

The demonstration by Philips and Wi-LAN comes as such industry consortia as Bluetooth, HomeRF and IEEE 802.11 are developing and promoting a host of RF-based wireless networking schemes. Based on divergent radio and modulation techniques, the approaches target a range of applications.

The IEEE 802.11 wireless Ethernet standard is designed for wireless transmission of data only; isochronous information is excluded. The approach uses the 2.4-GHz band and offers a raw data rate of up to 11 Mbits/s.

The Bluetooth scheme, meanwhile, targets short-distance links between cell phones and laptops with a 1-Mbit/s network that connects devices up to 10 meters apart. The frequency-hopping technology operates in the 2.54-GHz ISM band.

HomeRF also employs a frequency-hopping technology. It transmits data at 1.6 Mbit/s between home PCs and peripherals and supports up to four separate voice channels.

Philips is a member of both the Bluetooth and HomeRF groups. "We believe other RF solutions will coexist in the same home environment, because they are designed for different applications," Koomen said.

But developers of the various RF technologies are aware that such coexistence may be anything put peaceful at the outset, as issues of signal interference and network robustness arise once the technologies are deployed in homes. "When products sharing the same frequency band are used together, there will be definitely a resolution issue that we need to [address]," said Ritter. "The indoor environment is particularly susceptible to influences from other devices. We would probably need to go a step further [to ensure signal integrity] by adding more forward error correction and interleaving some data."

Philips hopes to realize a wireless 1394 solution by the end of next year. Ritter would not be specific about his company's chip-development plans for the scheme or comment on when or how the development arrangement between Philips and Wi-LAN might evolve into a broader business partnership. But he did say Philips would like to present its scheme "as a suggestion" at an upcoming HomeRF Group meeting.