What's beyond Wi-Fi?
In an evening session SiBeam and WiGig executives argued the relative merits of their competing technologies. Both aim to pave a path from today's Wi-Fi to a multi-gigabit future based on 60 GHz signaling.
Jeff Gilbert, CTO of SiBeam, argued that Wi-Fi is running out of gas while 60 GHz is inherently more energy efficient. While conceding the WiGig approach is a viable Gbit version of Wi-Fi, he said WirelessHD is as good or superior in all other user scenarios.
He also took on criticisms the WirelessHD approach could not reduce power enough for use in handheld devices. He said WirelessHD products could be made today using just four antennas to deliver a single Gbit/s of data about three meters with line-of-sight while consuming about 250 milliwatts.
Ali Sadri, president of the 50-member WiGig Alliance, said the group's 60 GHz technology is superior on several fronts.
Unlike WirelessHD and even Wi-Fi, WiGig aims to charge no royalties. It will have a Wi-Fi fallback mechanism and protocol abstraction layers supporting HDMI, DisplayPort and other interfaces.
A third option is in the works at the IEEE 802.11ac group. It is developing a 5 GHz spec using 80 and 160 MHz channels, up to 8x8 MIMO, 256 QAM and other techniques to deliver 867 Mbits/s to up to an aggregate of 6.9 Gbits/s across several devices depending on the implementation, said Rolf De Vegt, a Qualcomm engineer involved in the effort.
The .11ac technology could extend the familiar Wi-Fi experience far into the future, said De Vegt. It will leverage consumer hotspots and support software as well as the understanding of 5 GHz networking among Wi-Fi chip and system makers, he said.
The .11ac group is expected to finish its spec by the end of the year. The first compliant chips and an interoperability certification process could be in place at about the same time.
SiBeam's Gilbert suggested .11ac would be power hungry and its use of 80 and 160 MHz channels could be problematic. De Vegt himself admitted China currently has no 80 MHz channels available at 5 GHz, making the technology a non-starter there.
Jri Lee, an electronic engineering professor at National Taiwan University, called for simpler, lower cost options based on proprietary line of sight techniques aiming at distances of less than two meters.
He pointed to academic papers, some at ISSCC, describing such 60 GHz systems using relatively simple antenna designs and modulation schemes such as OOK, FSK and BPSK. Such designs could deliver 2-3 Gbits/s at less than 200 milliwatts, he said.