1. SMART ANTENNA SYSTEMS IN BWA Submitted by M. Venkateswararao

2. Abstract One of the most rapidly developing areas of communications is “Smart Antenna” systems. The elegance of their applications in various fields such a 4G telephony system, best suitability of multi carrier modulations such as OFDMA etc.., The signal that is been transmitted by a smart antenna cannot tracked or received any other antenna thus ensuring a very high security of the data transmitted. This paper also deals the required algorithms that are need for the beam forming in the antenna patters.

3. INTRODUCTION The rapid growth of the Internet user base and of bandwidth-hungry applications in recent years has created a need for ‘last mile’ broadband access We define “broadband” access as one that provides at least 5 Mbps peak (burst) rate per user in the downlink direction and 500 Kbps peak (burst) rate in the uplink. These include rapid deployment, high data (Mbps/sq.mile) scalability, low maintenance.

4. BLOCK DIAGRAM

5. Smart Antenna Array: Antenna array with a digital signal processing capability to transmit and receive in an adaptive and spatially sensitive manner. “Smart” >> digital signal processing facility

6. USAGE Applications to: cellular and wireless networks radar electronic warfare (EWF) as a countermeasure to electronic jamming satellite systems

7. WHY SMART ANTENNA ARRAYS?  Higher Capacity  Higher Coverage  Higher bit rate  Improved link quality  Spectral efficiency  Mobility

8. Elements of a Smart Antenna Number of radiating elements A combining/dividing network Control unit

9. Aim : To maximize the antenna gain in the desired direction To minimize the gain in directions of interferers

10. Smart Antennas for Base Stations The idea of smart antennas is to use base station antenna patterns that are not fixed, but adapt to the current radio conditions Can be visualized as the antenna directing a beam toward the communication partner only

11. Types of Smart Antennas Switched lobe (SL): ( also called “switched beam” ) simplest technique comprises only a basic switching function between separate directive antennas or predefined beams of an array

12. Types of Smart Antennas - cont’d Dynamically phased array (PA): continuous tracking can be achieved by including a direction of arrival (DoA) algorithm for the signal received from the user can be viewed as a generalization of the switched lobe concept

13. BWA ARCHITECTURES SINGLE (MEGA) CELL In mega cell architecture, a large service area with a radius of up to 30 miles is covered by one or two cells. The base station antenna is typically located on a very high tower or hill top (height of 500 to 1200 ft) to provide line of sight (LOS) paths to subscribers. A high gain CPE rooftop mounted antenna pointing towards the base station is used. Frequency reuse in angle (and polarization) may be possible with sectorization [Fig. 1(a)], particularly on the uplink.

14. Macro Cell Macro cellular systems use spatial frequency reuse to cover the service area. The BTS heights are similar to cellular infrastructure. LOS propagation is usually not possible, and cell ranges are therefore much smaller (1 – 4 miles) due to higher path loss.

15. SMDA (Space Division Multiple Access) More than one user can be allocated to the same physical communications channel simultaneously in the same cell Separated by angle only In a TDMA system, two users will be allocated to the same time slot and carrier frequency at the same time and in the same cell

16. SDMA (Space Division Multiple Access)

17. SMART ANTENNA ADVANTAGES Array Gain: Multiple antennas coherently combine the signal energy improving the carrier-to-noise ratio (C/N). Available both on transmit and receive. Diversity Gain: Spatial diversity obtained from multiple antennas helps combat channel fading. Available on transmit and receive. Spatial Multiplexing: Spatial multiplexing uses multiple antennas at both ends to create multiple channels and improves spectrum efficiency (bps/Hz).

18. Conclusion A large market opportunity is opening up for providing broadband wireless access to residential, SOHO and business markets. Successful BWA systems need to be scalable, should have high spectrum efficiency, should offer high bit rates and should be easy to deploy at the infrastructure and subscriber end. Use of multiple antennas at both ends of the wireless link along with efficient modulation, radio resource management, coding and diversity can increase spectrum efficiency

19. REFERENCES 1.“Smart Antenna Systems Tutorial”, The International Engineering Consortium, http://www.iec.org/online/tutorials/smart_ant/ 2.Lehne, P.H. and Pettersen M., “An Overview of Smart Antenna Technology for Mobile Communications Systems”, IEE Communications Surveys, Fourth Quarter 1999, vol. 2, no.4, http://www.comsoc.org/livepubs/surveys/public/4q99issue/pdf/Lehne.pdf 3.Schüttengruber, W., Molisch A.F. and Bonek E., “Smart Antennas for Mobile Communications Tutorial”, http://www.nt.tuwien.ac.at/mobile/research/smart_antennas_tutorial/inde x.en.html