Advanced Imaging


Advanced Imaging Magazine

Updated: July 8th, 2008 05:26 PM CDT

On-the-Go Imaging: Wireless Comes of Age



On-the-Go Imaging

A Real-Time Processing Challenge

By Paul Struhsaker

April 2003

Advanced Imaging's 2003 April Cover ImageBy codifying Quality-of-Service (QoS) requirements, the latest Wireless LAN standards pave the way for high-quality video and still-image transfer in the home, office and public "hot spots"...

Reliable and inexpensive transmission of high-bandwidth images around the home and in public venues without wires has been a long time in coming. But starting in 2004, a wave of products and applications will hit the market with the same mission: breaking the copper tethers in the home and public places-without sacrificing image quality.

Table 1. Peak performance data rates for various modulation and data-transport schemes.In the home, MPEG video will be transferred between DVD players and a variety of video sources. In public places, communication "hot spots" such as coffee shops and libraries equipped with high-bandwidth wireless LAN (WLAN) technology will provide access points where high-resolution still images can be transferred from cell phone to network in a few seconds instead of a few minutes. In the government sector, low-speed, low-cost video cameras for traffic control and security will become pervasive. These are but a few of many imaging applications enabled by wireless connectivity.

Why has it taken so long?

Transferring high-bandwidth wireless data locally has been a reality for years. But when wireless LANs made their first appearance in the mid-1990s, the focus was primarily on PCs and data. First-generation WLANs based on the IEEE 802.11 standard utilized the basic Ethernet error-correction protocol of identifying bad data packets and resending them. While a good solution for transferring data between PCs, this error-correction technique is deadly for imaging generally-and for video, in particular. Imaging needs reliable, predictable data streams to avoid image-deterioration artifacts such as frozen frames and pixilation.

As a result, WLANs were-for the most part-limited to computer data communication, which kept them in the office and industrial environments. A combination of modulation schemes and media access controller (MAC) protocols now provides a viable solution for high-bandwidth imaging applications. But the market also requires the right price points, and these have been achieved as well-not just in the semiconductors that implement the standard-but also in system components such as camera-imaging elements.

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