It started in Barcelona. Perhaps before, but Barcelona is where people starting taking it seriously. WiMAX and LTE, together as a happy family of technologies living together in harmony.
It won’t happen. The harmonization of WiMAX and LTE, that is. Talk about such a technology marriage was set off in earnest by a speech given by Vodafone CEO Arun Sarin at the Mobile World Congress in Barcelona last winter. The rumbling continued to echo in Las Vegas at the CTIA show when Sarin raised the topic again. Then, in June, the venerable media company BBC ran a story quoting Intel as saying the marriage “should” take place.
Like any urban legend, the supposition that WiMAX and LTE could somehow unite refuses to die despite all of the evidence to the contrary. That’s not to say that many in the industry wouldn’t like to see a universal radio access technology. But there are too many things going against it.
Blame part of it on the media, which loves a controversy. WiMAX and LTE usually are seen as competing technologies so any hint that they might come together gathers media attention. Sarin’s suggestion that WiMAX could become part of the LTE family gets turned into an advocacy. And the BBC may have been off-base when it quoted Sean Maloney, Intel’s sales and marketing chief, as saying the two technologies “should” be united.
“We are not supporting LTE today and we have no plans or efforts in progress on the harmonization (of LTE and WiMAX),” said Intel spokesperson Kari Aakre. She went on to say that Intel has always advocated one radio interface standard and conceptually believes a harmonization of WiMAX and LTE would be good. But the chip company is not doing anything in that regard.
Ron Resnick, the president and chairman of the WiMAX Forum, is even more firm. “They are not going to harmonize,” he said flatly. “If we had a United Nations (for technology) and we could have one technology, it would be wonderful. I think that’s what you’re hearing from Arun Sarin, from Intel, and from me. That’s Nirvana.”
|Norén: Too late to combine WiMAX and LTE.|
You get much the same picture from the LTE side. Thomas Norén, director of LTE products for Ericsson, said it is too late in the standardization process to bring about any harmony. He also noted that Sarin’s company, Vodafone, is one of the most aggressive on the rollout of LTE.
The only thing that lends credence to a harmonization theory is that WiMAX and LTE have a lot more in common, as technologies, than they have differences. Both are based on orthogonal frequency division multiplexing (OFDM) access schemes as well as multiple-input, multiple-output (MIMO) antenna configuration.
There are enough differences, though, that real work would need to be done to make them compatible. The main stumbling block is that LTE uses a pre-coded version of OFDM called Single Carrier Frequency Division Multiple Access (SC-FDMA) on the uplink. SC-FDMA is used to reduce power consumption on handsets. WiMAX uses Time Division Duplexing (TDD) exclusively, while LTE initially was going to use only Frequency Division Duplexing (FDD) but now plans to support TDD as well. WiMAX also is looking at FDD in the future.
The problem in bringing these together is that the mobile WiMAX standard has been completed, with the WiMAX Forum certifying equipment and networks rolling out. Meanwhile, the standard for the physical layer of LTE also has been completed, with the specification expected to be finally ratified by the end of the year.
It’s too late now to make substantive changes in the LTE standard, according to Ericsson’s Norén. The only way to do it would be to delay commercialization of LTE products, which is something no carrier advocates, including Vodafone, Norén said.
“It’s in no one’s interest to change the time plan except for WiMAX,” he said. He pointed out that Sarin’s Vodafone, Verizon Wireless, AT&T, Alltel, NTT DoCoMo, Telia Sonera and China Mobile all have announced plans to test LTE.
|McQueen: Motorola hopes to use the same equipment across technologies.|
The WiMAX industry has been bragging about its time-to-market advantage over LTE. Mobile WiMAX networks, led by Sprint Nextel, are rolling out this year. LTE networks aren’t expected to become commercial until 2010 or 2011.
LTE and WiMAX are often compared because of somewhat similar data rate promises, but Ericsson counters that the GSM community’s 3.5G technology, HSPA, is a better comparison. Norén said HSPA already is being widely deployed and in its latest version provides data rates of 42 Mbps down and 11.5 Mbps up. WiMAX ideally provides 40 Mbps down and 5 Mbps up with real-world rates of 1 Mbps to 5 Mbps, according to the WiMAX Forum.
Another impediment to a harmonization of the two air interfaces is that LTE is designed to be backward compatible with legacy networks using GSM/W-CDMA/HSPA and CDMA2000. WiMAX has no such plans on its roadmap, while LTE will bring about a marriage of two communities historically in conflict, the GSM and CDMA worlds. Even Qualcomm has broadened its chipset development to include LTE in its device and base station roadmaps. Qualcomm plans to sample its chips by mid-2009.
|Payne: Future versions of 802.16 may present a chance to harmonize.|
One of the main WiMAX vendors, Motorola, also is supporting LTE and envisions using the same basic equipment for either technology.
Darren McQueen, vice president for Motorola’s wireless broadband business, said the company has 19 WiMAX contracts and is deploying networks worldwide. On the network side, he said, Motorola can reuse the same hardware and its second generation WiMAX base station will become the basis for its first generation LTE product.
“We want to let the operators chose,” he said. “We see both (WiMAX and LTE) going forward.”
Bill Payne, vice president of advanced network technology for Motorola, said it is possible for LTE and WiMAX to harmonize. But he said the opportunity for that would come when WiMAX completes the next iteration of its technology, called 802.16m. He said WiMAX and LTE could converge at that point.
The 802.16m specifications are in the early stages of development, Payne said, with the expectation that it could go into draft stage in 2009.
|Tabassi: Harmonization will be achieved at the handset level.|
Ali Tabassi, vice president of technology development for Sprint Nextel, said the most likely harmonization of LTE and WiMAX will take place much the same way that 3G cellular technologies and Wi-Fi have come together on the handset – with multiple radios.
“Harmonization could be viewed from a hardware point of view with single or multiple chips in a device that handles different standards at different frequencies around the world,” Tabassi said.
The Sprint executive said the business model is just as important as the technology. That’s why Sprint went with WiMAX for its Xohm network, because equipment is available now with low IPR costs. He said WiMAX is being rolled out in more than 160 countries globally.
Wolfgang Mack, CMO for WiMAX vendor Telsima, said he believes the two technologies are competing now but he hoped they would be brought together when 802.16m is written.
“Harmonization can, should and needs to take place,” Mack said. Both would benefit by the larger ecosystem, driving prices down through greater economies of scale, he said. Even if harmonization isn’t done through standards, it can and should be accomplished through multimode devices, he added.
Still, the business model argument alluded to by Tabassi leads to a common assumption – that existing cellular operators (Sprint as a notable exception) are lining up with LTE in the future while greenfield operators, cable and Internet companies are backing WiMAX. The gulf between those is what prevents harmonization.