The dramatic growth of the wireless communication industry is creating a huge market opportunity. Wireless operators are
currently searching for new technologies that can be implemented in the existing wireless communication infrastructure
to provide broader bandwidth per user channel, better quality, and new value-added services. Employing smart antennas
presents an elegant and relatively economical way to improve the performance of wireless transmission (Winters, 1998;
Soni, 2002; Bellofiore, 2002a; Bellofiore, 2002b; Diggavi, 2004).
Deployed at base stations in the existing wireless infrastructure, smart antennas bring outstanding improvement in
capacity to radio communication systems, which have severely limited frequency resources, by employing an efficient
beamforming scheme (Tsoulos, 1997). New value-added services, such as position location (PL) services for emergency
calls, fraud detection, and intelligent transportation systems are also being implemented in real-world applications thanks
to the direction-finding ability of smart antennas (Tsoulos, 1999).
Smart antennas can also be efficiently used at mobile terminals. Employed at mobile terminals (e.g., notebook PCs,
PDAs) in ad hoc networks or wireless local-area networks (WLAN), the direction-finding ability permits the design of
packet routing protocols that can determine the optimal manner of packet relaying (Nasipuri, 2000). The beamforming or
interference-suppression ability makes it possible to increase throughput at network nodes where it is limited by interference
from neighboring nodes (Winters, 2006).