MIMO Boosts WiMAX Bandwidth
Nortel Uses Multiple Antennas in Fourth Generation Mobile Trial
by Jim Barthold
Wed, October 25. 2006
Charting a course towards fourth generation (4G) mobile wireless services using WiMAX, Nortel has conducted a wireless transmission that used Uplink Collaborative MIMO to double the number of mobile broadband subscribers a cell site can support.
The demonstration is part of the vendor's overall policy to promote WiMAX as a viable 4G mobile technology and to begin to move toward the second wave of WiMAX Forum specifications that include MIMO in both transmission and reception devices.
“Under Wave 2 MIMO is an optional portion to the standard and we’re implementing it according to the standard,” said Bruce Gustafson, director of WiMAX marketing at Nortel. “The only difference in Nortel’s approach versus some of the other vendors is instead of launching a Wave 1 product which is a subset of the whole WiMAX standard, we’re launching a Wave 2 product right from the start.”
That product, he said, uses the multiple input-multiple output antenna scheme to double the bandwidth and make mobile broadband a more satisfying and realistic experience. This, in turn, could lead non-mobile operators to find a spot in the emerging 4G wireless space. On the other hand, since all fourth generation mobile technologies will use some fashion of MIMO and OFDM, it also gives Nortel a migration path for more conventional mobile technologies like UMTS and CDMA.
Possibly most importantly – aside from delivering more bandwidth in the WiMAX cell – it also creates a synergistic connection with MIMO-based Wi-Fi to enhance the fixed- mobile convergence (FMC) possibility for both wireless and wireline providers.
“Our definition of 4G is less based on technology (and) more based on a view of the world where there is no difference between the connection you can get on the desktop versus the connection you can get when you’re out in the wide world,” Gustafson said. “If all those devices are connected, if people don’t need to change their behavior to go back and search out a connection to complete a task, that’s what drives a significant change in consumer behavior,” he said.
4G devices, he emphasized, will be equipped with multiple antennas to receive multiple wireless signals. The Nortel demonstration of collaborative MIMO did not use those types of devices but rather used multiple antennas on the cell transmission site to drive up the bandwidth.
“Once Wave 2 devices appear … I can do full MIMO to drive up the bandwidth of any particular device,” he said. “It’s a WiMAX chipset, a few tenths of dollars, it’s multiple antennas in the device.”
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