Did anyone else notice that during the recent WiMAX World trade show, every vendor launching WiMAX gear touted Multiple Input, Multiple Output technology as part of its solution?
Indeed, Aclatel Inc., Fujitsu Network Communications, Motorola Inc., Nortel Networks Ltd., Samsung Electronics Co. Ltd., and even ZTE Corp. said their WiMAX gear employs MIMO technology.
So what exactly is MIMO, and how is it that the technology aids both Wi-Fi and WiMAX networks? MIMO refers to transceivers and receivers. Instead of Single-Input, Single-Output antenna architecture, which seeks to eliminate multipath propagation, MIMO takes advantage of multi-path propagation, which results in increased data throughput and range due to reduced bit error rates. And, MIMO achieves this using no additional bandwidth or power. Overall, MIMO is said to increase the spectral efficiency of wireless networks.
So it makes sense that the IEEE working groups for both the 802.11n standard for higher Wi-Fi throughput standard and the 802.16-2005 mobile WiMAX standard are aching to include MIMO technology in their final standards. In fact, MIMO technology developed by Airgo Networks Inc. is the foundation of 802.11n.
Airgo’s TrueMIMO technology was showcased in two recent wireless-in-the-home product launches, and although 802.11n technology will not be certified by the Wi-Fi Alliance until sometime next year, Airgo is shipping products built according to the IEEE’s draft 2 specifications that is said to deliver Wi-Fi at speeds up to 540 megabits per second.
The best thing about MIMO? “MIMO can be applied to any wireless communications system,” noted Dave Borison, director of product management at Airgo.
He also pointed out that MIMO technology can increase the reliability of a network by collecting multiple signals, including echoes, and then rebuilding the signals into a stronger signal.
Over the last few years, Airgo has sold about 3 million in-home MIMO-powered products under the Linksys and Netgear brands. Borison said he believes the next wave of products to be shipped with MIMO are laptops, with other mobile consumer electronics devices set to roll after that.
“For now, the Wi-Fi market is a huge market for us,” Borison explained. “In 2007, the market will transition to our playing field. We see the MIMO-enabled Wi-Fi market as a $3 billion market.”
Nonetheless, Jeff Orr, director of marketing at the WiMAX Forum, said in an e-mail that MIMO is an optional testing module within Release 1.0, Wave 2 of 802.16-2005, which is estimated to be approved by the third quarter of 2007.
Furthermore, Orr said the WiMAX Forum believes there are sufficient products under development today to begin certification testing in that timeframe and stressed that “products can be submitted with MIMO, but it is not a required element for certification.”
However, Juan Santiago, director of WiMAX Infrastructure Product Management at Motorola, told RCR Wireless News, “MIMO has been in the WiMAX standard for a long time, and it will be one of the things that all of the vendors have to have.”
Santiago defined Motorola’s WiMAX offerings as two distinct architectures-a dual transmit and receive WiMAX application and a “smart antenna” product loaded with 4 transmitters and 8 receivers along with beamforming technology.
“We are driving MIMO into the standard. It’s a matter of finalizing when it’s going to be required,” Santiago said.
Interestingly, Santiago also mentioned that Motorola is still in the process of switching from a SISO-enabled product to MIMO-laden equipment, but added, “When it’s mandatory, we’ll be marching fully ahead.”
Nonetheless, even if MIMO isn’t part of the WiMAX standard, carriers may demand that the technology be included in the equipment they deploy into their networks. Jim Parker, senior manager of Wireless Terminals at Samsung noted, “Sprint [Nextel Corp.] has announced that they will deploy only Wave 2 devices and infrastructure into the network-all Wave 2 devices and infrastructure will support MIMO.”
And apparently it won’t be hard to find WiMAX equipment laced with MIMO technology.
“Nokia firmly believes in MIMO as a technology and is actively implementing MIMO into its WiMAX product offering,” stated Nokia in an e-mail.
Alcatel is also bullish on MIMO, according to Sudeep Gupta, director of the company’s North American Broadband Wireless Access business development.
“Alcatel is using MIMO technology, as well as Adaptive Antenna System, for our support of smart antennas. Both AAS, which supports beam forming, and MIMO are going to be important for WiMAX deployments,” Gupta said. “AAS provides a way to increase the reach of a cell, and for coverage-limited environments, can reduce the number of required sites by up to 50 percent. Since wireless networks usually start out as coverage limited, having support for AAS is important when the system is first deployed.”
Gupta did add that “MIMO isn’t used to increase coverage, but for increasing capacity and it can almost double the capacity in urban environments. MIMO therefore offers the most benefits in urban areas when the network is capacity-limited. Operators will see the most benefits from deploying AAS initially and then following up with MIMO as the network becomes capacity-limited. Therefore, Alcatel’s WiMAX base station supports AAS in the initial release, and it is software-upgradeable to MIMO to align with the timing for certification.”
And in case carriers aren’t interested in WiMAX or Wi-Fi networks, rest assured, efforts are under way to standardize a MIMO specification for use in 3G standards.
