In anticipation of WiMAX operators fleeing to LTE for 4G mobile broadband, Continuous Computing has added time division duplex (TDD) support to its Trillium LTE software for gearmakers. TDD support also opens up the addressable markets available to OEMs and by extension, operators.
“For WiMAX operators, many have TDD spectrum, so the TDD variance makes it much easier and faster for those players to expand their product line and expand into LTE world,” said Brian Wood, vice president of marketing at Continuous Computing, which specifically focuses on the telecom sector, selling underlying solutions to network equipment manufacturers for LTE, DPI and femtocells.
He said Continuous Computing works with several strong vendor players in the WiMAX space and they are clearly looking for such solutions to evolve to LTE. “Then there’s another group who are not yet our customers and they need somewhere to go, because staying with WiMAX is not an option,” Wood said. “The LTE market is the path for growth, because of the sheer projected size: Nine out of 10 major operators have publically committed to LTE. WiMAX in relative terms is limited.
“LTE is going to be an order of magnitude bigger than the WiMAX market,” he told xchange. “So this allows them to easily evolve using our TDD variation. The hardware is very similar – it’s the software that’s the main difference.”
The TDD variance also allows gearmakers to approach operators in new markets. Most markets in the world have frequency division duplex (FDD) paired spectrum in use for 3G: One is used for uplink and the other for downlink. An exception is China – the regulations there specified going with a TDD approach, creating a market difference that would give the home vendors have a home field advantage for the TDD version of CDMA.
“But TDD is not just for China anymore as 4G rolls out,” said Wood. “That used to be the case and no longer the case.”
He added that a minority of markets – 40 percent – less than half of the operators have FDD ready spectrum for 4G. A little more than half however have the TDD spectrum.
“Paired FDD is ideal when an operator has a large unencumbered block of spectrum,” said Wood. “But having a big chunk that’s all for them and they can subdivide it as they choose is fairly rare for 4G because there are legacy services using existing spectrum for public safety, TV, 3G, supporting older equipment. Not every operator in every country has that luxury.”
Where there is fragmented spectrum, operators need to work with what they have. The flavor of LTE that allows them to do that is TDD, which uses shared or unpaired spectrum for more flexibility, albeit in trade for a slight performance penalty.
Continuous Computing has also announced its Advanced LTE MAC Schedulers, in an attempt to standardize MAC schedulers in general. This software physically assigns air interface resources to the various processes in the base station, across all the uplinks and downlinks.
“Previously gearmakers had developed their own MAC schedulers, and considered it their own secret sauce, proprietary,” Wood explains. “Every one was different from the other so there’s not a lot of portability. So we narrowed down six proven popular implementations and developed a suite of six pre-programmed MAC schedulers.”
Vendors can use them out of the box, or customize the software.
The LTE TDD and MAC scheduler offerings are available today; Wood said they’ve been battle-hardened in field and lab trials, including one with a large Japanese carrier and one with a large U.S. carrier.
