Wireless HD video: Raising the UWB throughput bar (again)

After a period of relative quiet in the UWB arena, new products are emerging to raise the throughput bar. Recent independent tests put Radiospire in the lead.

Testing by octoScope verified that Radiospire's AirHook technology achieved throughput of 1.6 Gbps—fast enough for uncompressed HD video distribution over distances of 15 feet. Radiospire sponsored the test.

This article will first review the promise and technical challenges facing UWB, report on the most recent test results, and analyze Radiospire's approach to UWB. We will also discuss the throughput and encryption considerations for HD video distribution.

Leapfrogging technologies
It was less than a year ago that the industry eagerly anticipated the arrival of Certified Wireless USB (CW-USB) and wondered how close real-world systems would come to the advertised 480 Mbps PHY rate quoted by the technology's trade association, the WiMedia Alliance. Some WiMedia companies were promoting their technologies for video distribution—with the help of data compression.

In independent testing conducted by octoScope and published by EE Times and Wirelessnetdesignline, however, performance of CW-USB chips and systems proved to be disappointing. But the same testbed confirmed that Pulse-Link's CWave technology achieved a 675 Mbps PHY rate and 500 Mbps of application layer throughput.

Now Radiospire has taken the lead. It remains to be seen how WiMedia and Pulse-Link will respond, not to mention the UWB technology community, which has already taken initial steps toward standardizing a 60 GHz technology.

UWB video challenges
UWB operates in the noise floor of traditional wireless applications and is able to share the already allocated spectrum with other services while only negligibly raising their noise floor.

The low transmit power limit of -41.3 dBm/MHz EIRP (Effective Isotropic Radiated Power) curtails the range of UWB to about 10 meters, but the wide available spectrum of 3.1 to 10.6 GHz, enables high throughput applications, making UWB technology well suited for short range High Definition (HD) video transport, connecting devices such as the DVD players, set-top boxes and displays.

After the FCC approved the UWB spectrum allocation in February of 2002, the IEEE 802.15 committee attempted to standardize the MAC and PHY layers to operate in the UWB band, but abandoned this effort in January of 2006 for lack of consensus. Many of the companies originally working on the IEEE 802.15 standard joined the WiMedia Alliance and focused on the CW-UWB technology that was evaluated in octoScope's recent EE Times test.

In that test the WiMedia-based products exhibited an order of magnitude lower throughout than Pulse-LINK (675 Mbps), the only non-WiMedia product tested. Now Radiospire, another player outside the WiMedia camp, has set a new record of 1.6 Gbps.

Although WiMedia is regarded as the UWB standard, companies such as Pulse-LINK and Radiospire point out that other MAC and transport standards, such as the IEEE 802.15.3b, TCP/IP and HDMI (High Definition Multimedia Interface) can also bridge the gap between UWB PHY technologies.

The original goal of UWB was short range HD video distribution. HDMI, in particular, is an uncompressed video interface, requiring more throughput (Table 1) than was achievable in the UWB band until Radiospire came along.

Click here for Table 1.
Table 1: Uncompressed video throughput requirements.