Perhaps the most important research has been done Telecom R&D under the auspices of the EU IST-Magnet project examining personal area networks. France Telecom and its partners are examining how to implement UWB in 60GHz in order to benefit from the small wavelength and limited interference, hence permitting a higher radiated power level than classical UWB systems. Within the IEEE taskgroup, companies such as Philips - notably absent from the WiHD's founder members - driven by the need to boost data rates for media networks, are prominent. It is vital for the digital home industry that this overriding common interest - to accelerate functionality and time to market for high speed home media networks - takes precedence over political and commercial differences and that another damaging standards war is averted.
The chip challenges:
Although standards will be critical to achieve the cost efficiencies and economies of scale for the consumer electronics market - preferably just one unified standard - equally important will be the creation of chip technology that can be the basis of cost effective devices, the main obstacle that has limited usage of higher frequency spectrum, even when available, to date. As yet, emerging chips for 60GHz are unproven but increasing congestion in 2.4GHz and risk of the same in 5GHz is increasing interest in exploiting other sources of unlicensed spectrum are exploited, especially if these are available on an international basis, as 57-64GHz is in many countries. Such bands are also attractive since they tend to generous power allowances than others – the FCC’s limit in 60GHz is 40dBm, far higher than it permits for UWB in its current US-allocated spectrum range of 3.1GHz to 10GHz, where its power limits are one-10,000th those of a cellphone. However, creating cost effective chips - which usually means CMOS process - is very difficult at these high reaches of spectrum.
There are plenty of technical obstacles associated with implementing access applications in high spectrum. Peak data rates can only be sustained over short distances and with high power, compared to lower bands. This has limited the market in the past and kept equipment costs high, as have the complexities of making 60GHz radios. Traditionally, these have used expensive materials such as gallium arsenide, but now there are research projects examining the potential of the implementations in low cost silicon germanium and, eventually, CMOS, which would drive prices down for a volume market. For instance, IBM’s TJ Watson Research Center in New York state is working on such a project, as are Caltech and some advanced start-ups such SiBeam, along with Intel.
The main interest, from a chipmaker’s point of view, is that high frequencies support very small circuits and antennas. To some extent, these can be designed to compensate for the propagation problems. For instance, tiny antennas – in the more futuristic projects, small enough to be part of a ‘body area network’ – can still achieve high direction gain, or complex antenna arrays can be assembled to boost data rate and range even within the limitations of the frequency, using techniques such as beam forming or MIMO (Multiple In Multiple Out). The higher power limits allowed by the FCC also help make up for the inherent problems of 60GHz radios.
A project at Berkeley University in California is aiming to implement very small circuits in CMOS with a view to creating low cost, mass market miniature devices that will, in their first iteration, perform at 1Gbps over 10 meters – a target the team aims to hit by year end. IBM is looking to build its radio initially in silicon germanium, believing that CMOS will only be appropriate once the market is established and starting to achieve volume.
Clearly such projects will be of critical interest to Intel, whose ambitious designs on controlling the wireless chip market center on all-CMOS radios supporting one or multiple frequencies. It has several advanced projects in the area of CMOS radios for frequencies above 10GHz, and interestingly, seeks to establish the technology potential for the full 802.16 standard. While WiMAX has been focused on spectrum below 6GHz, the 802.16 standard can be applied to higher spectrum up to 60GHz. Intel will look to create an efficient CMOS radio for 60GHz, delivering advanced performance through MIMO and other techniques.
Copyright © 2006, Wireless Watch
Wireless Watch is published by Rethink Research, a London-based IT publishing and consulting firm. This weekly newsletter delivers in-depth analysis and market research of mobile and wireless for business. Subscription details are here.