I'll Take Your 300Mbps, and Raise You A Gig
By Carlo Longino, Tue Dec 07 19:15:00 GMT 2004
Forget HSDPA, and DoCoMo's 300Mbps 4G system -- a Siemens lab has hit 1Gbps, a new record for wireless transmissions.
Cue pipe dreams of what to do with all that bandwidth, and operators' dreams of how much they can charge for it. Siemens' lab used MIMO (multiple input multiple output) smart antenna technology alongside an OFDM network to break the wireless speed record, operating in the 5 GHz band. The company isn't getting too carried away, though, with no estimate of just when we'll all be enjoying this, but does say it will show it off at the 3GSM World Congress in February. It does say that by the time 4G debuts in 2015 -- a surprisingly conservative estimate for the mobile industry -- bandwidth demands for voice, data and multimedia will have grown tenfold.
There's a lot that has to happen before all this bandwidth is coming into phones, though. Multiple-antenna systems transmit different flows of data over the same channels in the same frequency band, so the information that's simultaneously transmitted by different antennas is received over multiple antennas on the receiving end. The streams then have to be reconstructed in real time by the receiving device, a task requiring significant computing power, more than that of chips generally used in today's mobile devices. Siemens overcame this by developing new signal-processing algorithms, which it says can run effienciently on today's hardware.
Siemens does, however, talk up OFDM technology, saying it's "highly promising" and already in use in WLANs and digital TV and radio broadcasts. Siemens also recently signed a deal with Flarion to partner on products using its proprietary Flash OFDM technology to create equipment for 450 Mhz networks. Flarion's technology, which supports download speeds up to 1.5Mbps, with 300-500Kbps on the upload, is being tested and deployed by several carriers around the world, including Nextel in the US.