The WiMedia Alliance has defined the interoperability standards for UWB communication. The work of the WiMedia Alliance, beginning over a decade after Wi-Fi was first standardized, focused its efforts on providing increased capability to enable new wireless applications.
The most demanding of these new applications is video. Uniquely, the availability of broad spectrum in UWB communication provides an unequalled advantage for high-performance, high-capacity video networks, including:
- High bandwidth.
- Greatly reduced probability of microscopic fading resulting in significantly improved link reliability and availability.
Building on the fundamental technology advantages of UWB, the WiMedia Alliance created product advantages by defining a high-performance solution (MAC and PHY layers) as a new standard, including:
- Quality of Service (QoS), including a bandwidth reservation scheme for guaranteed bandwidth.
- Increased data throughput as a result of more efficient channel use.
- Peer-to-peer communication (without an access point) for simplified networking of mobile devices.
One of the recent advances in UWB is the implementation of interference cancellation technologies that substantially improve performance in three key areas:
- Link reliabilitythe percentage of time the link is available for error-free transmission.
- Packet error ratethe number of video packets in error compared to the total number of video packets.
- Interference robustnessthe ability of the receiving device to avoid performance degradation (reduced video quality through increased packet errors) when exposed to other frequency signals. This interference robustness is necessary for protection against both in-band and out-of-band interferers.
The objective of these improvements is to improve the conditioning of wireless links to enable demanding, real-time applications to run on top of a robust connection. The technology draws on previous work in multiple antennas and MIMO, and results in a decrease in the fading margin required.
Below is summary of how these advances in UWB are enabling solutions that far surpass the performance of Wi-Fi networks, and meet and often exceed the requirements of CE manufacturers.
Click here for Table 1
Table 1: UWB vs. Wi-Fi.
Due to fading, wireless links are subject to unavoidable outages. The fade durations typically are between 0.1 to 3 seconds long, and occur in 10-20 MHz blocks. Coincidentally a Wi-Fi channel is 20 MHz wide (some newer systems use 40 MHz) which means that the fades take out entire Wi-Fi channels and render them unusable for communication.
For a best efforts data network (email or web browsing), losing all data carrying capacity in the network often goes unnoticed. By contrast, a network carrying video at a data rate of 30 or 60 frames per second will suffer serious image degradation (and possibly a complete lack of video) as the result of an outage due to fading.
Fading is an unavoidable phenomenon in Wi-Fi networks. Due to its narrowband nature, Wi-Fi solutions provide a link reliability of only 90 percent. To overcome this severe problem, some companies have tried buffering video data on the television. While this can help the on-going delivery of video to the screen, there are other implications of buffering video data, including:
- Memory costvideo is a high-bandwidth application where the video buffer for a 1080p, 12-bit color, 60 fps application requires approximately 560 MBs of buffer memory per second of video.
- Loss of lip sync.
- Increased latency and buffering result in poor remote control performance and poor joystick control in gaming applications.
New solutions provide link reliability and availability significantly above 99 percent, enabling real-time data transfer without buffering video data. Using them enables demanding applications such as video to be communicated flawlessly for hours without any degradation in link quality.