In the developed mobile world, new technologies like WiMAX and LTE will have to live alongside several other systems, and consumers will increasingly want to be able to roam seamlessly across different networks according to cost and availability ‘ especially if open access models start to take off in earnest. This will place new momentum behind the bid to make multimode devices more complex, and yet cheaper and less power hungry.
Packing more and more radios on to a single chip is one approach, as pursued by Qualcomm (though no support for WiMAX yet). A stage beyond that comes the software programmable processor, which can be tweaked in software, by the handset maker or operator, to support a flexible combination of network connections. Sandbridge Technologies this week announced its contribution to this nascent market, with its SB3500, a 65nm reprogrammable software-based baseband processor, which can be adapted to LTE, HSPA, WiMAX, W-CDMA, Wi-Fi, GPS and the mobile TV standard DVB-H.
The Sandbridge processor is entirely software-based, and points to the vision of a fully cognitive radio in future ‘ a single radio that can move intelligently between different networks, according to parameters such as cost or signal strength. Indeed, a workshop hosted by Intel last week demonstrated how much progress has already been made towards that dream.
Because the Sandbridge platform is programmable, cellphone makers can use a single architecture to support phones with different combinations of radios, reducing their costs. Sandbridge’s technology will also reduce the number of chips needed in a phone, which should cut cost, time to market and complexity. The company claims the cost savings can amount to 15% across design and production, and the figure could grow as consumers look for more and more functions to be packed into one low power unit.
Another advantage that Sandbridge claims for its technology is that handset makers can respond more quickly to standards changes ‘ such as the next wave of 802.16e, or even the shift to 802.16m – testing and adding new functions rapidly in software rather than waiting for the chipmaker to deliver upgraded hardware. Changes in standards can also be easily accommodated, so operators could move to new networks even before standards are finalized, with reduced risk.
The software-based processor is likely to catch the attention of larger handset chip players, especially those, like Qualcomm, that have been in the forefront of squeezing multiple radios into a single chip in hardware. As for competition, there are other start-ups, such as Sweden’s Coresonic, in this field, and ST-NXP Wireless has some advanced software defined technology, from the NXP side of the group, but most of the majors are nowhere near to market readiness with programmable basebands yet.
Although Sandbridge claims ST-NXP’s offering has far higher power consumption than its own processor, the joint venture has been making quite a stir with its multimode, programmable LTE modem, which will be the basis of a software defined radio system from the company. The modem, built round NXP’s Embedded Vector Processor (EVP), will have theoretical data rates of 150Mbps on the downlink and 50Mbps on the uplink. It complies with the 3GPP R8 radio specification for LTE and also supports UMTS and EDGE/GPRS/GSM. NXP is targeting the modem at the handsets market but also plans to optimize the design for next generation laptops, internet tablets and ultra-mobile PCs.
Looking ahead to full cognitive radios – which actually sense wireless traffic to make intelligent decisions about using spectrum ‘ Intel hosted a workshop last week in conjunction with European research institute IMEC. Among companies represented at the event were Alcatel-Lucent, Alvarion, Marvell, Motorola, Nokia and Qualcomm and IMEC aims to build prototype hardware soon, geared to next generation WiMAX and LTE networks in licensed bands, as well as to various technologies for license-exempt white spaces.
Cognitive radios would “have more direct pay-off to the incumbent operators and some form of this probably will begin to appear in next generation broadband standards such as WiMAX 2 [802.16m] and LTE,” said Kevin Kahn, director of Intel’s communications technology lab. He also believes the white spaces within the US broadcast spectrum will be a good area to test the new technology at relatively low cost and risk. The chip giant believes the FCC’s recent decision to open up these white spaces for unlicensed wireless use ‘ provided interference avoidance techniques are supported – will light a new fire under cognitive radio work and offer WiMAX a new opportunity.
Some early work on interference avoidance in the spaces was undertaken by 802.16 study groups and the IEEE 802.22 (or Wi-TV) standard is an important element of many prototype devices. These were produced to make the case to the FCC that wireless devices in the white spaces will not interfere with TV broadcasts or wireless microphones. Microsoft, Google, Motorola and Philips were among the leaders of the effort, and at the heart of their developments was cognitive radio. 802.22 aims to create a standard for fixed wireless (up to 1W power) and nomadic embedded systems (up to 100mW), and potentially for mobility in future, using cognitive radio techniques to switch automatically to a clear area of the band, and to avoid interfering with other occupying devices. The WiMAX community has been particularly keen to claim TV bands for its own, and in March 2004 when the 802.22 group was set up, the 802.16 faction was angered when its proposal that the cognitive radio work should be under its auspices, rather than in a separate group, was defeated. However, this has not halted its supporters, led by Intel, in their quest to turn the 802.22 efforts to their advantage.
Separately, IMEC is making progress on developing software defined radios that use common hardware blocks to handle work on up to six wireless networks. “We think the first market for SDR will be in enabling programmable baseband processors for handsets in 2009,” said the institute at Intel’s workshop. “Long term we may see common analog-digital converters and antennas, but that’s very long term and impossible in today’s technology.” IMEC has demonstrated a baseband and front end radio chipset flexibly handling traffic for two wireless nets at data rates up to 100Mbps, according to EETimes, and claims this is the highest performance SDR to see the light of day, and has low power levels.
Intel, which has often talked of its Adaptive Radio project, a flagship R&D activity for five years, said its labs have now built a baseband processing chip that can be programmed with several radio standards; and have also done work on reconfigurable antennas. Such research is now being transferred to various product groups for inclusion in future chips. “For our purposes, limited programmability is a win. For these reasons I have tended to talk about softer radios rather than software radios,” Kahn said.