1. Antenna II LN08_Smart Antennas zakeri@nit.ac.ir 1 /09 Smart Antennas

2. Antenna II LN08_Smart Antennas zakeri@nit.ac.ir 2 /09 Smart Antennas  Over the last decade, wireless technology has grown at a formidable rate.  Most practical solution to this problem is to use spatial processing.  Spatial processing is central idea of smart-antenna systems.  Smart Antennas are known as:  Adaptive array antennas.  Multiple antennas and recently multiple input multiple output (MIMO).  This idea backs to World War II with conventional Bartlett beam former (BBF) used in Radar systems.  a great deal of research is being done on adaptive and direction-of-arrival (DOA) algorithms.  Its name in military is direction finders (DF).  These topics are followed by:  Antenna array theory.  Time of arrival.  Adaptive digital processing algorithms.  Mutual coupling.  Mobile Ad-Hoc networks.  Network capacity/throughput.  Bit-error-rate (BER).

3. Antenna II LN08_Smart Antennas zakeri@nit.ac.ir 3 /09  Smart Antenna Analogy:  To give an insight into how a smart-antenna system works, let us imagine two persons as:  Voice of speaker arrives at each acoustic sensor (ear) at a different time.  Human signal processor (brain) computes direction of speaker from time differences.  brain adds strength of signals from each ear so as to focus on sound of computed direction.  Furthermore, if additional speakers join in conversation, brain can tune out unwanted interferers and concentrate on one conversation at a time.  The equivalent system is: Smart Antennas

4. Antenna II LN08_Smart Antennas zakeri@nit.ac.ir 4 /09  Cellular Radio Systems Evolution:  Maintaining capacity has always been a challenge as number of services and subscribers increased.  To achieve capacity demand required by the growing number of subscribers, cellular radio systems had to evolve throughout the years.  To justify need for smart-antenna systems in current cellular system structure, a brief history on evolution of cellular radio systems is presented. For more in-depth details refer to [23]–[25].  Omnidirectional Systems:  Since system designers knew that capacity was going to be a problem, especially when number of channels or frequencies allotted by Federal Communications Commission (FCC) was limited.  Therefore, to achieve capacity required for thousands of subscribers, a suitable cellular structure had to be designed; Smart Antennas

5. Antenna II LN08_Smart Antennas zakeri@nit.ac.ir 5 /09  Smart-Antenna Systems:  Despite its benefits, cell sectoring did not provide the solution needed for the capacity problem.  Therefore, the system designers began to look into a system that could dynamically sectorize a cell.  Hence, they began to examine smart antennas. Smart Antennas

6. Antenna II LN08_Smart Antennas zakeri@nit.ac.ir 6 /09  Switched-Beam Systems: Smart Antennas

7. Antenna II LN08_Smart Antennas zakeri@nit.ac.ir 7 /09  Switched-Beam Systems: Smart Antennas Relative coverage area comparison among sectorized systems, switched-beam systems, and adaptive array systems

8. Antenna II LN08_Smart Antennas zakeri@nit.ac.ir 8 /09 Smart Antennas Functional block diagram of an adaptive array system

9. Antenna II LN08_Smart Antennas zakeri@nit.ac.ir 9 /09 Smart Antennas  Multipath Environment