Developers and designers are responding to industry needs for innovative, multi-mode LTE devices. The requirement for multimode LTE devices is not just that they can handoff between LTE, HSPA and 3G coverage, but also that they will be able to operate within different LTE spectrum bands.
This may aid roaming, of course, but more importantly will enable use across spectrum bands within a network where operators are using lower frequencies for coverage, and higher frequencies for urban capacity. It may also mean being able to operate in both TDD and FDD spectrum.
One company, IP Wireless, is using Altair's Software Defined Radio (SDR) baseband processors to build LTE devices that can operate at specific frequencies. IPWireless' LTE device will incorporate Altair's FourGee-3100 baseband and FourGee-6200 RFIC chipsets. The FourGee-3100 is a 3GPP LTE baseband processor that supports LTE category 3 (CAT-3) throughputs (100Mbps/50Mbps DL/UL respectively). The chip implements a 20MHz MIMO receiver and is based on a proprietary SDR processor which offers increased performance but reduced power over traditional DSP cores. The chipset supports FDD as well as TDD versions of the LTE standard and has undergone interoperability testing with OEMs.
John Hanvidge, of IP Wireless, said that the first product has been designed with a specific operator in mind. It will operate at 800MHz, 1800MHz and 2.6GHz. It will be available in the final quarter of this year, he said. Later devices would cover the US 700MHz bands, he said. Hanvidge cited Vodafone Germany as one operator that is looking at such a deployment of LTE across different spectrum bands.
With experts now expecting there to be up to 15 LTE radio bands, the key for device OEMs will be to have platforms that enable them to select radios accordingly. Software Defined Radio and modems lend themselves to this. They also reduce power consumption - a critical factor as the industry looks to move from dongles to actual LTE handsets.
Icera Wireless is one company that has demonstrated multimode soft modems, showing LTE/HSPA interworking on its commercial HSPA sticks at Mobile World Congress this year using its Adaptive Wireless feature set and Livanto soft baseband. The company recently took $45 million financing to accelerate its product development.
An Icera spokesperson said that its next product would be out before the end of the year, and would enable LTE and HSPA.
Another company targeting the soft modem space is UK start up Cognovo - a company formed initially founded by TTPCom executives, before later incorporating ARM's Ardbeg Vector Signal Processor activity.
Cognovo's CEO Gordon Aspin said that the ARM VSP enables the company to design a Software Defined Modem platform that is dimensioned for handsets and portable devices capable of LTE Category 4 (150Mbps) but also scales to support multi-mode operation with other standards.
This puts it ahead of Icera, he said, describing Icera as a 1.5G version of the SDM.
Aspin also added that another advantage of the SDM is that its performance can be upgraded even once the device has been shipped. He said you could even see "white label" modems developed that have software downloaded onto them later. That raises the question, then, of who pays the IPR if software is being downloaded later than the manufacturing stage?
"It's potentially a very disruptive technology. You could create devices that have the world's best wireless processor but independent of any particular air interface."