Recent research reveals that information security and information-hiding capabilities can be enhanced by proper exploitation of space-time techniques. Meanwhile, intrinsic properties of ultra-wideband (UWB) signals make it an outstanding candidate for secure applications. In this paper, we propose a space-time coding scheme for impulse radio UWB systems. A novel real orthogonal group code is de...

Cognitive radio (CR) improves spectrum efficiency to satisfy increasing demands on wireless transmission by dynamic spectrum access without interfering with legacy networks. In 2004, IEEE 802.22 Working Group was formed to develop a standard for wireless regional area networks (WRANs) based on CR technology (Hu et al et al., 2007). It is expected to obtain a broadband access to data networks on...

Ultra-Wideband (UWB) technology has been gaining increasing interest from the industry due to its recent application in communications. The technology itself has been well known for decades and its use was mostly reduced to radars in industrial applications. During the standardization process which is not over yet, two realizations were proposed – Impulse Radio (IR), which has been known for ye...

The paper presents results of a co-existence measurement study between multiple ultra wideband (UWB) transmitters and a Universal Mobile Telecommunications System (UMTS) mobile phone. Two environments were explored: an anechoic chamber with one operating UMTS link and a true operational UMTS network. A large number of FCC compatible UWB transmitters were used to generate interference for an act...

Ultra-wideband (UWB) impulse radio (IR) systems are well known for low transmission power, low probability of detection, and overlaying with narrowband (NB) systems. These merits in fact make UWB signal detection challenging, since several high-power wireless communication systems coexist with UWB signals. In the literature, cyclic features are exploited for signal detection. However, the high ...

Wireless personal area networks (WPANs) will play an important role in next-generation communication networks. Currently, two technologies are being considered for the physical layer of WPANs, based on the two ultra wideband (UWB) standards, namely, multiband orthogonal frequency division multiplexing (MB-OFDM) UWB and direct-sequence (DS) UWB. The coexistence issue of these two types of WPANs ...

Abstract—Recently, the shortage of assignable radio frequency spectrum became a serious issue because of the coexistence of many licensed wireless communications systems. Therefore, cognitive radio technology has gained much attention around the world, which may be aware of its environment and makes occupancy of radio spectrum more efficient. This paper examines numerical results of active inte...