One of the biggest limitations of Web tablets is that few are truly wireless-enabled. Those that are more often than not are tied to restrictive protocols and servers that strip the rich multimedia content before delivering information from the Web. The primary reason for this is that the common wireless technologies for embedded platforms, such as Cellular Digital Packet Data and General Packet Radio Service, support a maximum data rate of 19.2 kbits/second and 150 kbits/s, respectively.
So protocols such as Wireless Application Protocol are traditionally employed to strip the rich media content from the target Web site to alleviate painfully extended wait times. The result is a less than fulfilling Web experience.
Working together, Wi-LAN and Applied Data Systems have developed a new product that will offer a thousandfold speed increase for wireless data transmission and will improve speeds from the current levels of 19 kbits/s and 27 kbits/s to 20 Mbits/s. Wireless is now faster than both DSL and a cable modem.
We have developed a wireless Web pad equipped with Intel's SA-1110 microprocessor and SA-1111 companion chip, the MQ200 graphics accelerator, Windows Media 6.4, a 13.5-inch XGA TFT display and that 20-Mbit/s unprecedented access data rate. Two factors enabled us to do this: broadband communication data rates and multimedia processing.
Last year, Wi-LAN developed the world's first Orthogonal Frequency Division Multiplexing (OFDM) ASIC for use in our WAN product line. Wideband OFDM (W-OFDM), a multicarrier transmission scheme, offers two inherent advantages over other wireless techniques: the technology highly resists the effects of multipath delay spread and it boasts outstanding spectral efficiencies. So we expect the next generation of portable devices to leverage the benefits of W-OFDM to accommodate seamless and cost-effective high-speed wireless deployments.
One of our primary goals was to develop a design that would sustain high-resolution, media-rich applications to differentiate our access technology from the existing technologies that support only limited bandwidth applications such as e-mail.
In the middle of 2000, Wi-LAN's team began focusing on a proof-of-concept design that would showcase the portability of the W-OFDM technology. The immediate challenge was to identify and select an embedded architecture-operating system combination that was powerful enough to fully demonstrate the capabilities of W-OFDM. To do that, we defined an extensive list of selection criteria about the performance of existing embedded processors and operating systems. One of our primary yardsticks was the support that was readily available from the worldwide design community. In other words, we wanted to choose an operating system and embedded CPU that boasted the largest number of supported applications, development tools and experienced developers.
Moreover, we sought an embedded processor that offered the greatest flexibility, an excellent cost-performance ratio and a clear road map. Additional selection criteria included power requirements; availability of design tools; vendor support; general component availability; number of previous design wins; support by credible design houses; the highest cost-performance ratio for intensive high-resolution multimedia consumer-based applications; capabilities of supporting dominant operating systems-such as Windows CE and Windows Media-and support of leading graphics accelerators such as MediaQ's MQ200 as the preferred graphics accelerator. That was due to the device's power efficiency, impressive functionality and low cost, and MediaQ's concentrated focus on the consumer electronics appliance market.
Then we began searching for a partner with a solid track record developing embedded platforms for portable and mobile applications. We quickly realized that competition within the embedded design industry was extremely tight and aggressive. Ultimately, we identified and evaluated five processors, three potential operating systems and a number of competent vendors; we then assessed the existing platform offerings of each of the vendors. Since none of the off-the-shelf platforms was ideally suited for our application, the willingness of the vendor to modify the existing designs to better satisfy our requirements and the cost became important factors. After four months of investigation, we brought in Applied Data Systems (ADS) as our partner.
Integration goal
Basically, ADS supplied the multimedia processing capabilities by integrating our technology with one of the only commercial off-the-shelf component technologies that could keep up with such a broad data pipe and still run on batteries. ADS adapted its StrongARM-powered Tandem product with the powerful Media-Q MQ-200 graphics processor. With 32-bit processing power for Windows CE 3.0 and its media player, the tablet can provide full-motion video on a 24-bit, 13.5-inch, XGA full-screen display.
We built an onboard power supply as part of the Tandem package to help speed the project's development. Finally, we had to add a slot to hold the PCI implementation of the Wi-LAN OFDM communication system.
Most important for our Web tablet application is that the Tandem system uses its RISC environment and streamlined engineering platform to produce minimal heat output and have a power requirement of only several watts. ADS included an on-board power supply so that battery operation would be possible. Finally, ADS had to add a PCI Bus and connector to facilitate connection to the OFDM module.
The Wi-LAN-ADS teams selected the Windows CE platform, as it represents one of the most dominant, best-known operating systems in the embedded market today. Supporting documentation and software is pervasive; besides, our design engineers have a natural inclination toward Windows CE as they migrate from 95 to NT to CE. ADS has produced a comprehensive low-level software set supporting the CE 3.0 platform that includes drivers for all devices on board.
Simplified design
To simplify the tablet, we selected a two-board solution for the prototype-Wi-LAN's W-OFDM PCI module and a modified ADS Tandem system. The module design provides a PCI 2.1-compliant 32-bit, 33-MHz interface into the OFDM engine that can provide up to 30 Mbits/s of raw data. The wireless interface has a bandwidth of 10 MHz with a carrier frequency within the ISM band. The PCI interface was strategically chosen to provide a processor-independent interface to permit the W-OFDM PCI module to be incorporated within a number of other PCI-equipped devices.
In the Web tablet design, one of the problems our two teams faced was how to blend design elements of hardware, software and FPGA code while maintaining the portability of the existing software in the design. We wanted as few changes as possible to the PCI FPGA design, since modification of a design that complex would certainly not be trivial.
Significant glue logic was required to hardware remap elements in the ADS legacy design into address "holes" within the PCI interface and vice versa.
Despite the design obstacles encountered during the development of the Web tablet, the project was completed in early January. And, in an achievement as unique as the tablet itself, we were able to move from an informal agreement at the Embedded Systems Conference in September to having the first units operational in January.
