The benefits of an increasingly mobile lifestyle introduced by wireless technologies in cell phones and home PCs have resulted in greater demand for the same benefits in other consumer devices. Consumers enjoy the increased convenience of wireless connectivity. They will soon demand it for their video recording and storage devices, for real-time audio and video (AV) streaming, interactive gaming, and AV conferencing services as the need for digital media becomes more predominate in the home.

Many technologies used in the digital home, such as digital video and audio streaming, require high-bandwidth connections to communicate. Considering the number of devices used throughout the digital home, the bandwidth demand for wireless connectivity among these devices becomes very large indeed. The wireless networking technologies developed for wirelessly connecting PCs, such as Wi-Fi* and Bluetooth* Technology, are not optimized for multiple high-bandwidth usage models of the digital home. Although data rates can reach 54 Mbps for Wi-Fi, for example, the technology has limitations in a consumer electronics environment, including power consumption and bandwidth. When it comes to connecting multiple consumer electronics (CE) devices in a short-range network, or WPAN, a wireless technology needs to support multiple high data rate streams, consume very little power, and maintain low cost, while sometimes fitting into a very small physical package, such as PDA or cell phone. The emerging UWB wireless technology and silicon developed for UWB applications offer a compelling solution.

The emerging digital home environment is made up of many different CE devices (e.g., digital video and audio players), mobile devices (e.g., cellular phones and PDAs), and personal computing devices (e.g., mobile notebook PCs) that will support a multitude of applications. These devices fall into three general overlapping
categories (Figure 1):

These devices have traditionally been kept in different rooms and used for different functions. Increasingly, however, owners expect them to interact.MP3 players exchanging files with PCs, digital video recorders communicating with STBs, etc. This convergence of device segments calls for a common wireless technology and radio that allows them to easily interoperate and delivers high throughput to accommodate multiple, high-speed applications. Currently, these segments utilize different interfaces and content formats.

The next generation of PC, consumer electronics, and mobile applications demand connectivity speeds beyond the 1 Mbps peak data rate of Bluetooth Technology, which is used by many devices to create WPANs today. But many CE devices cannot support the cost and power required by the higher speed 802.11a/g radios for Wi-Fi networking.

While Wi-Fi is much faster than Bluetooth Technology, it still does not deliver sufficient performance to effectively allow streaming of multiple simultaneous high-quality video streams. UWB technology provides the throughput required by the next generation of converged devices. Plus, the support of industry initiatives, such as the WiMedia* Alliance, will help ensure interoperability across multiple protocols, including IEEE 1394, USB, and Universal Plug and Play (UPnP*), making UWB a broad technology solution for creating high-speed, low-cost, and low-power WPANs.

UWB differs substantially from conventional narrowband radio frequency (RF) and spread spectrum technologies (SS), such as Bluetooth Technology and 802.11a/g. UWB uses an extremely wide band of RF spectrum to transmit data (Figure 2). In so doing, UWB is able to transmit more data in a given period of time than the more traditional technologies.

The potential data rate over a given RF link is proportional to the bandwidth of the channel and the logarithm of the signal-to-noise ratio (Shannon’s Law). RF design engineers typically have little control over the bandwidth parameter, because this is dictated by FCC regulations that stipulate the allowable bandwidth of the signal for a given radio type and application. Bluetooth Technology, 802.11a/g Wi-Fi, cordless phones, and numerous other devices are relegated to the unlicensed frequency bands that are provided at 900 MHz, 2.4 GHz, and 5.1 GHz. Each radio channel is constrained to occupy only a narrow band of frequencies, relative to what is allowed for UWB.

UWB is a unique and new usage of a recently legalized frequency spectrum. UWB radios can use frequencies from 3.1 GHz to 10.6 GHz.a band more than 7 GHz wide. Each radio channel can have a bandwidth of more than 500 MHz, depending on its center frequency. To allow for such a large signal bandwidth, the FCC put in place severe broadcast power restrictions. By doing so, UWB devices can make use of an extremely wide frequency band while not emitting enough energy to be noticed by narrower band devices nearby, such as 802.11a/g radios. This sharing of spectrum allows devices to obtain very high data throughput, but they must be within close proximity.

Strict power limits mean the radios themselves must be low-power consumers. Because of the low power requirements, it is feasible to develop cost-effective CMOS implementations of UWB radios. With the characteristics of low power, low cost, and very high data rates at limited range, UWB is positioned to address the market for a high-speed WPAN.

UWB technology also allows spectrum reuse. A cluster of devices in proximity (for example, an entertainment system in a living area) can communicate on the same channel as another cluster of devices in another room (for example, a gaming system in a bedroom). UWB-based WPANs have such a short range that nearby clusters can use the same channel without causing interference. An 802.11g WLAN solution, however, would quickly use up the available data bandwidth in a single device cluster, and that radio channel would be unavailable for reuse anywhere else in the home. Because of UWB technology’s limited range, 802.11 WLAN solutions are an excellent complement to a WPAN, serving as a backbone for data transmission between home clusters.