Real-world deployments of wireless HD video: Is 802.11 ready?

While streaming video has been around for some time, the market's attention must now focus on the immediate future and determine if the industry is prepared to meet the ever-increasing demand for wireless High Definition (HD) video transmissions. In addressing this issue, it will be important to research and identify what real world issues we must overcome in order to achieve HD video capability wirelessly. Current IEEE 802.11 WLANs operate with raw data rates up to 54M bit/sec with actual throughputs of no more than 20 to 30Mbit/sec (depending on the type of overhead).

Although fine for many applications in use today, future applications will demand an even higher throughput. These emerging wireless video applications such as HDTV (720p up to 1080i) video demand throughput rates of 100M bit/sec and higher.

It is important to have an understanding of the use of the ISM bands that the FCC has designated for unlicensed applications (i.e. Bluetooth, garage door openers, cordless phones, microwave ovens, baby monitors, video surveillance, etc.), and now WLAN (802.11) applications.

The FCC revolutionized the wireless industry by opening up unlicensed ISM bands. Today, spectrum is selling for millions of dollars and there are delays associated with obtaining an FCC license for a specific frequency band.

These unlicensed ISM bands reduce the barrier to entry allowing companies to introduce wireless products and services without the expense. The price paid for utilization of the ISM bands however, is interference.

Despite the fact that these bands have typically been sparsely occupied, the ever increasing adoption of Bluetooth and WLANs in this band will make the challenge of overcoming interference more prevalent. Over the past few years, the use of the ISM bands for data communications has grown dramatically and today three main applications of the ISM bands remain—Bluetooth devices, cordless phones and WLAN.

Interference and congestion affect Wi-Fi in the 2.4GHz and 5GHz ISM bands in unmanaged/uncontrolled environments such as homes, apartments, small offices, and 802.11 Wi-Fi Networks.

Some of the factors contributing to this problem include, but are not limited to, no control over interfering sources; higher data rates, which are more susceptible to the effects of interference; and growing portability and mobility of interference sources (i.e. Voice Over Wi-Fi handsets—VoIP).

A focused look at wireless video
RF environment. The most promising new applications to enter the market will be the use of Wi-Fi systems, 802.11n in particular, for streaming video, and HDTV distribution in the home.

In order to support these emerging technologies, new approaches to mitigating a dirty RF environment while still enabling even higher throughput wireless communications (100's of Mbps) must be developed. As already noted, higher throughput transmission schemes are typically more sensitive to interference, so this creates a particularly challenging task for the engineering team.

The migration to high-definition content along with the proliferation of digital source devices has intensified the consumer's desire to simply and flexibly connect to the highest quality, high-definition displays and consumer electronics systems—thus the drive to wireless connectivity.

Today, experience with devices attempting to use wireless local area network (WLAN) technology for video distribution have fallen well short of consumer expectations in picture quality and range (distance from router for effective transmissions). Their biggest deficiency has been the lack of adequate effective throughput.

While it's not the sole solution to all video-handling hurdles, higher throughput improves immunity to interference while delivering a means to handle degraded environmental (dirty RF) conditions.