This article is part two of a six-part online series that culminates with a final analysis feature in Oct. 9 issue of Telephony. The other parts in this series can be found on our WiMAX World page.

Nortel Networks is aching for a rumble. Or, to use Nortel’s new WiMAX general manager Peter MacKinnon’s more domestic imagery, it’s ready to pit its WiMAX gear against any other vendors in a “competitive bake-off” to see whose is superior.

Whatever the metaphor, Nortel more than any other vendor is touting its research and development and all-around technical savvy in WiMAX above all else. MacKinnon said Nortel has seven years of solid research in orthogonal frequency division multiplexing (OFDM) and multiple input/multiple output (MIMO) smart antenna technology under its belt and the intellectual property and patents to back it up. But more than just ideas on paper, it has a commercial Mobile WiMAX kit that MacKinnon claims can achieve a cost-per-bit ratio three times better than any other vendor’s commercial WiMAX gear and a 10-times improvement over whatever 3G technologies can provide today.

“We’re coming out from day one with MIMO, while our competitors are doing adaptive array,” MacKinnon said. “We’re starting out with a second generation product so we won’t have the product maturity issues others will face.”

While the acronyms may be ungainly, the concept is simple. Nortel is eschewing the two-tiered technology path of most vendors, who are starting with adaptive antenna system (AAS) and beamforming technologies and later incorporating MIMO’s multi-signal path support, MacKinnon said. Instead Nortel is taking an all-MIMO-all-the-time approach to WiMAX, MacKinnon said, and believes that implementation will provide a simpler yet technically superior alternative for any operator.

Every vendor will make a different claim of what a particular technology is capable and which is superior, but on a basic level, both beamforming and MIMO are both multiple antenna technologies that differ mainly in how they use those antennas to create a connection to the end device. AAS and beamforming systems use multiple antennas to create a single beam aimed at particular WiMAX device. That single beam provides a stronger signal and a higher-capacity link to the individual user. MIMO, however, doesn’t use its multiple antennas to create a single focused beam, but rather multiple parallel beams, each of which finds its way to corresponding antennas on the device. Multiple signals hitting multiple antennas means more capacity, and signal processing software sorts out the individual transmissions, simulating a single high-capacity transmission back to the base station.

The typical knock on beamforming is that it doesn’t support true mobility. While the base station can easily steer the beam to follow individual users throughout the cell, it isn’t easily adaptable for high-mobility cases, particularly when a user is moving between base stations. And according to Nortel, the increased range and signal strength benefits of beamforming are negated in real-world deployment scenarios. Meanwhile, MIMO not only supports additional capacity, Nortel maintains, it’s optimal for the cluttered urban environments where WiMAX is expected to make its initial impact. MIMO can take advantage of multi-path effects as signals bounce off buildings on their way to the device.

While it’s true MIMO is optimized for dense urban environments with strong signals and beamforming ideal for more spread-out deployments with weaker signal strength, it doesn’t mean MIMO is the superior antenna architecture, said Lars Johnsson, vice president of business development for WiMAX CPE-maker Beceem and a co-founder of Flarion Technologies. They are merely suited for different applications of WiMAX, he said by no means are the mutually exclusive. Beceem and its infrastructure partners are developing devices that incorporate both beamforming and MIMO technologies. The devices simply switch between the two schemes as a user moves throughout the network, constantly optimizing the configuration of the device as signal conditions change, Johnsson said.

“MIMO is not the answer to everything, but neither is beam forming,” Johnsson said. “Vendors that focus on one at the exclusion of the other may be swimming upstream when it comes to optimal system performance.”

Nortel’s championing of MIMO may give it one advantage over the competition though. Choosing to focus solely on MIMO gives Nortel a clear technology path that it can point to while other vendors waver between different solutions or create multiple products, said Peter Jarich, broadband wireless analyst at Current Analysis.

“That’s the problem with any new technology,” Jarich said. “You get all of these little technical nips. The result is you get conflicting camps, all saying different things. After a while the customer just gives up.”

While Nortel is clearly in the MIMO camp, Jarich said, it is sticking by the technology exclusively and not hedging its bets with a separate or combined beamforming platform. It may be a risk, but there’s no doubt in anyone’s mind Nortel will change technology midstream, which many carriers may find refreshing, Jarich said.

If MIMO is Nortel’s ace in the hole, it has to play that card soon. Other vendors are by no means ignoring the technology. Motorola has been demonstrating its MIMO system, called Diversity, at trade shows. Alcatel said it will soon be shipping its software defined radio (SDR) base station, which will support MIMO with a software upgrade. Several other WiMAX vendors said they are targeting the WiMAX Forum second phase of certification—which will includes the MIMO profile—next summer for the release of their MIMO products.

But MacKinnon said he doesn’t feel pressed. Though Nortel feels it has the technical lead, it certainly hasn’t stopped innovating, MacKinnon said. He pointed to work Nortel’s labs have been doing on the algorithms that determine the fundamental orthogonal modulation schemes of OFDM, the heart of any WiMAX transmission. Through math alone, MacKinnon claimed, Nortel’s commercial WiMAX products have a 25% efficiency advantage over other vendors’ pre-commercial products. “And when they come out with MIMO, we will have moved on,” he MacKinnon said. “We’ll have full mobility. We’ll have even greater efficiencies.”

What Nortel needs now is to turn those purported efficiencies and technical innovations into a contract win. Nortel has conducted smaller Mobile WiMAX trials in Korea Taiwan and Germany, but it’s only commercial WiMAX win--for underserved areas in Alberta--was a Fixed WiMAX contract using the gear of its OEM partner Airspan. Nortel definitely competed for the Sprint contract, but failed to make the list of initial vendors—which MacKinnon said came as a surprise to the vendor. But Sprint is likely to name more infrastructure vendors in the future, possibly even a third primary vendor to split the national rollout with Sprint and Motorola. If Nortel can secure a place in that lucrative deal, it would definitely gain the same momentum of the former two vendors.

Sprint confirmed that it will require fully-supported MIMO deployment for its urban ‘4G’ footprint, which is clearly a checkmark in Nortel’s favor, but what may be Nortel’s biggest advantage in securing Sprint’s favor is its long-standing CDMA relationship with the carrier, Current Analysis’s Jarich said. Nortel is a known entity in Sprint’s many networks; the operator is clearly comfortable working with the manufacturer, Jarich said. But WiMAX is a completely new technology with no established incumbents--Samsung won a contract without any existing presence in Sprint’s network (though it is a major network provider). And any buddy-buddy relationship status Nortel has with Sprint may also be true for other vendors, Jarich said. Lucent Technologies may have no WiMAX product, but it certainly has a healthy relationship with Sprint as its primary CDMA provider. If the Lucent and Alcatel’s merger goes fluidly with no global integration problems, it might open the way for Alcatel’s own WiMAX platform, Jarich said.

“No one should be so naïve to think products alone make deals,” Jarich said. “Sales channels are very important in this industry.”

Related Articles

Motorola: The College Boy