Connecting the wireless dots

Connecting the wireless dots
By Patrick Mannion, EE Times
November 8, 2002 (12:24 p.m. EST)
URL: http://www.eetimes.com/story/OEG20021107S0017

Two years ago, skeptism reigned when the concept that the next step for wireless was to connect the dots — not just between isolated WLAN islands but also between WLANs and wide-area cellular networks. Arguments against an all-in-one solution included WLAN radios power consumption, the potential for 2.5/3G to obviate the need for widespread use of WLANs, network roaming with its IP mobility and authentication problems and the reluctance of carriers to even acknowledge the WLANs, much less make them an integral part of their value-add.

At a panel I chaired at the following Spring Comdex in 2001, I asked panelists from both Ericsson and Nokia if they were working on a cohesive WLAN/WAN solution. Both said point blank that it was not feasible - for many of the same reasons, adding the cost factor of WLAN radios.

My how the landscape has changed. Nokia has announced a combined 802.11b/GPRS radio for laptops (albeit exploratory), as h as Gtran; VoiceStream snatched up the assets of defunct hot-spot provider MobileStar; Ericsson has partnered with Agere and Proxim to provide seamless connectivity between WLANs and WANs with SIM cards providing the authentication and Ericsson's network providing the one-stop billing and IP roaming. And the list goes on. From chip and software announcements to network/system alliances it's clear that operators, from Telenor in Norway (which still leads the way) to VoiceStream in the U.S., are recognizing that it's time to take off the 3G blinkers and recognize the complementary assets at their fingertips.

So what does this mean for hotspots? For one thing, the notion that hotspots operators can exist as standalone, self-sustaining entities is ludicrous. It's like having a car that you can only refill at Amoco. Users need to be able to migrate from network to network - ideally without dropping a session, but at least without having to ante up with more money and entering a new password. This is happen ing, thanks to the awakening of the operators. In the meantime, as Navin Sabharwal, of Allied Business Intelligence (Oyster Bay, NY) points out, designers will strive toward the goal of a single-chip radio for both networks, but in reality, this is still a number of years off - don't count on seeing such a device until 2004. Plug-in add-ons will be the norm.

"The power consumption of WLAN radios is still more than the cellular operators' handheld power budget will allow," he said. "But add-on WLAN cards are feasible in the meantime." As we migrate toward a single-chip solution, however, it appears that integration will first occur in the baseband/MAC, thereby leaving the radio options open.

In the meantime, of more interest to some (namely Parthus (Dublin, Ireland), said Sabharwal, is the integration of Bluetooth and GPS radios, citing the similar power and size parameters of each and their non-conflicting bands of operation.

While this melding of the two networks occurs, from the bottom up by WLANs and from the top down by operators, a number of interesting things are happening in between. Space-time coding, smart antennas and antenna diversity are being employed to extend the range of WLANs up to several kilometers and to improve capacity and overall reception (Zyray Wireless, Bermai). The same for WANs, with Innovics recently adding its name to smart-antenna proponents for cellular that includes Arraycomm, Nortel and IPWireless. This is blurring the data-rate and distance distinctions between cellular, WLAN and fixed wireless access technologies. This blurring has only been accentuated by the announcement recently by Monet Mobile Networks (Kirkland, Wash.) that it was offering cdma2000 1xEV-DO service to homes (typically the domain of fixed wireless) at rates of up to 2.4 Mbits/s to compete with dial up service.

As wireless LAN (WLAN) chip sets become commoditized and the long-awaited shakeout in that arena continues, smart (aka diversity, beam-forming) antennas are becomi ng the next differentiating factor. Long shunned for its intensive processing requirements, the technology is now being embraced, thanks to refined algorithms and "cheap" processing power.

As a result, this week's In-Focus takes a look at the key enabling technology that will form the next plateau in WLAN and cellular performance. We have several antenna design articles: Engineers from Bell Labs discuss how multiple-input, multiple-output technologies can boost data rates significantly and Zyray Wireless founder Pieter VanRooyen makes a case for space-time processing, and one by an Ethertronics design team discussing antenna diversity in handhelds.

As WLANs proliferate and Bluetooth commences its long-awaited emergence, the coexistence of co-located WLAN and Bluetooth radios continues to be an issue. For example, Mobilian Corp. just announced its breakthrough TrueRadio chip set, which allows simultaneous operation through advanced techniques such as active cancellation and deferred transmis sion. To get an idea of some of the issues that Mobilian claims to have overcome, read thearticle by Silicon Wave's Terry Bourk, who is a member of the Bluetooth Review Board.

Other contributions include a discussion by engineers at Xtreme Spectrum on what is needed to get ultrawideband up and running and, online, a piece on the ever-popular task of allocating FPGAs, DSPs and ASICs for 3G basestations, by Altera DSP manager Paul Ekas. Also, there is a discussion of low-power front-end WLAN design by Raviv Melamed, chief RF engineer at Envar Inc., and an update on advanced processes for wireless from RF engineer Etienne Delhaye at Philips Semiconductors.

The point of all these is to create a snapshot of real-world design techniques and technologies that can push forward the current slew of established WLAN and cellular networks, while giving a glimpse of what's up and coming. For the next wireless In-Focus section, scheduled for the Feb. 17th. 2003 issue, we'll go beyond improving the here a nd now to examine 10 of the most cutting-edge wireless technologies that will shape the wireless arena 10 years from now.