As a result of the recent ruling by the European Commission, ultrawideband wireless communications can now pervade small confined environments such as cars or trains. This paper studies frequency selective fading experienced by ultrawideband wireless channels in these confined environments. It focuses on the relationship between the severity of fading and the environment * + * +

A novel concept of the use of an ultra-wide bandwidth (UWB) ultrasmall-scale wireless interconnect scheme inside an electrically small enclosure is proposed. The concept is presented using a PC tower case as a model environment in which a channel measurement campaign has been made with two different types of antennas. Ricean K factor analysis was conducted for different positions of the antennas to identify the multipath behaviour of the channel, as well as channel capacity. An average maximum channel capacity of almost 6 Gbit/s is achieved using the whole UWB band for one of the antennas, assuming a signal-to-noise ratio of 25 dB. This work supports the proposal that a high-capacity UWB wireless interconnect scheme for communicating different devices within a PC case scenario may be used to replace wired interconnections, providing a wireless backplane system.Introduction: Look inside a conventional PC enclosure and one sees a big range of cables and line buses connecting different components. Part of these cables connects the main board (MB) to devices such as CD-ROM or floppy disk. These wired buses have a maximum data rate of no more than 3 Gbit/s using the serial advanced technology attachment (SATA II) with future improvements [1]. If we look closer we can find another type of thin cable integrated in different boards, such as the MB or peripheral cards (PCBs), interconnecting different microchips of their own substrate, where the standard data rate for a 32-bit communication will not exceed 1 Gbit/s [2]. All these interconnections require a huge amount of space, where further improvements of data rate would be limited by this fixed architecture. Replacing part of these wired cables inside small cavities has become an important future technology receiving increasing research interest [3]. We propose in this study to substitute the wired bus connections by small antennas, in order to enable a wireless interconnect between components. This study is based in the ultra-wide band (UWB, 3 -11 GHz) [4]. However we ignore FCC power regulations owing to the considerable effort expended in the electromagnetic compatibility field in ensuring that equipment enclosures do not permit radiation to leak out. The use of the UWB band is vital to achieve the highest data rates possible to match SATA II or PCI bus technologies.

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This paper explores the performance of a commercial WiMedia Multi-Band OFDM Ultrawideband development kit in a confined environment. It confirms previous predictions that the forward error correction schemes of WiMedia systems might not be sufficient for confined environments with a high number of multipaths. A carefully designed environment is shown to be able to alleviate the issue and improve the performance by reducing the packet-error rates. Analysis of packet-error-rates obtained for various antenna orientations and polarisations enables us to propose design rules to assist deployment of WiMedia MultiBand OFDM Ultrawideband wireless systems in confined environments.