The relay point model

Farpoint Group –

I recently had the pleasure of moderating a session on the Future of Wireless at the Communications Design Conference in San Francisco. The room was packed (as is always the case with sessions of this type), and the panel consisted of CEOs and senior technical folks from wireless companies both large and small. The conversation went everywhere - chips, systems, protocols, basic technologies, markets, applications, and products. One of the most interesting questions concerned wide-area broadband services, of the EDGE (for an example, see AT&T Wireless's implementation) and 1xEV-DO varieties, that are now becoming available.

While, as always, your mileage may vary, these systems offer downlink throughput of 200 to 300 Kbps, and sometimes faster. We can expect that we'll reach megabit speeds in wide-area wireless, although not for a few years yet. One of the panelists, though, mentioned that the utility of such systems may be limited by subscriber units. In less formal terms, why would anyone need a few hundred kilobits per second, and perhaps more, going into an end-user device like a cell phone? A number of speakers noted that, given the small screen and limited user-input facilities available, such throughput was either a marketing ploy, something better suited to notebook computers, or perhaps a waste of time altogether. Indeed, EDGE is largely marketed by AT&T Wireless as something best suited to a laptop equipped with a PC Card modem - a mobile DSL replacement, if you will. And, of course, at $80 a month, demand will be somewhat limited for now regardless.

This line of reasoning makes sense if we look at the handset as an end in itself. And, traditionally, it has been. Connectivity between handsets and other information appliances or computers has to date been quite limited. My Sidekick (which, as I've noted, I mostly like) has both a USB connector and an infrared port. Neither do anything at present; there's no software support. I can synchronize data stored on the Sidekick through a Web page, but this can be inconvenient. What I really want is a local broadband connection that would allow the handset to be a relay point between the Internet (via the wireless WAN) and other devices I might be carrying, including a notebook, PDA, digital camera, and on and on.

This sounds like a job for a wireless personal-area network, like Bluetooth. But with wireless LAN prices dropping so rapidly, why use Bluetooth when you can get Wi-Fi? And, indeed, Wi-Fi in cell phones is a major trend. So, if I add Wi-Fi to my mobile phone, all of my other Wi-Fi-equipped devices can now be on the Internet, too, using the cell phone as a relay point - or, more formally, a router.

Sound strange? It is, today. But this is likely to be the model for the future. We won't be putting wide-area radios in every device because of cost, and because each will need its own account on the wide-area service. That could really get expensive! But WLAN chips are cheap, and the service is free. We do, however, need to worry about power consumption in the cell phone. Batteries and power management remain the final frontier in mobility, and I'll have more to say on this topic later in the year. But for now, power conservation remains the gating item. We can, of course, just turn the power down in the Wi-Fi network, since we're not transmitting very far, and live with any interference from any nearby higher-power Wi-Fi nodes, which won't cause much interference in the typical case anyway.

But there is another option: ultrawideband (UWB) radio. I've mentioned this a couple of times in the past, and I'll cover it in more detail next week. UWB consumes very little power, and doesn't have much trouble with interference. This might be the ideal technology to work with the cell-phone relay point model. But, it's early, and UWB is not without its own controversies at present. Regardless, a battle between UWB and Wi-Fi could be shaping up.

In the meantime, I think the cell phone handset of the future will be a lot more than a mobile phone. It will also be a firewall, router, and gateway. It will provide the means for all of your other personal information devices to connect to the Net. This is one scenario Bluetooth got right - and one that both Wi-Fi and UWB have their sights set on.

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