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Wireless home multimedia networks require multiple design strategies

Posted: 16 May 2003 ?? ?Print Version ?Bookmark and Share

Keywords:multimedia network? wireless network? wap? web browser? bluetooth?

Implementing bandwidth-hungry and processing-intensive applications in a wireless network presents numerous challenges to design engineers. Until recently, real-time media and networking performance was achieved by using multi-chip solutions, with discrete processors to handle such things as MPEG-2 decode or the Docsis cable modem. But today, to meet the requirement of newer standards such as MPEG-4, WMV, and JVT (H26L), and maintain consumer level manufacturing costs, vendors are looking to ever larger-scale SoCs that contain several processors.

There are four technologies that when used together will optimize an SoC for maximum performance, power economy and low cost in a wireless home multimedia network. These are the single-instruction, multiple-data (SIMD) processing; an efficient and fast on chip interconnect bus, such as the AMBA standard; effective use of symmetric multiprocessing (SMP); and reliance on vectored interrupt controller (VIC) mechanisms to ensure real time deterministic response in a networked multimedia environment.

Presently, wireless device makers, service providers and software developers use a variety of operating systems and applications based on disparate standards that can make it hard for devices and networks to interact.

There are a plethora of media standards: MPEG-2, MP3, and MPEG-4; advanced audio coding (AAC); Bluetooth; H.263+; and the upcoming JVT for high-rate, high-resolution video; to name just a few, many of which have multiple profiles within their standard.

In addition, a new standards group, the Open Mobile Alliance, has replaced the WAP Forum, whose WAP is the most widely used platform for Web browsers on cellphones. It is too early to know what the new group will come up with in the line of new versions of WAP (the latest version is WAP 2.0, launched in January of this year). At the same time, however, Apple Computer, Ericsson and Sun Microsystems are working on what they call the Ericsson content-delivery solution for multimedia, based on 3G Partnership Project (3GPP) standards.

What all this means to the wireless network system developer is that any multimedia codec that is hardwired into the system is likely to be superceded by improved standards in the near future, meaning early product obsolescence. For this reason, hardwiring these codecs does not make any sense in today's market.

SIMD is a method of processing data in which a single instruction is applied to multiple pieces of data simultaneously rather than to each piece of data individually. Repetitive tasks are effectively consolidated into one, reducing the code size and greatly increasing the speed of data processing. Instructions of this nature are often associated with graphics and video.

SIMD instructions are especially helpful when processing streaming video, which lends itself well to parallel processing. For example, if you are processing RGB components in video, whatever you do to one color you also do to the two others. With SIMD you can do the procedure with one instruction for all three operations. This dramatically reduces the performance load on the codec processor. The use of SIMD in wireless multimedia environments is even more important than its use in desktop multimedia for it ensures efficient, fast processing with a minimum of compute and power resources.

- Noel Hurley

Multimedia MArket Manager


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