OUTLINE Introduction Antenna and its Parameters Smart antenna and its evolution Adaptation algorithms Applications Future Scope Conclusion
INTRODUCTIONPerformance and capacity are the two majorimpairments in Wireless Communication.Can be achieved by overcoming Multipath andInterference.Smart antenna is a promising technology that ensureshigher capacity in wireless networks.Employs SDMA (Space Division Multiple Access).
ANTENNA AND ITSPARAMETERSprovides a means for radiating or Antenna is a device that receiving radio waves. o Transmitting Antenna o Receiving Antenna o Radiation pattern o Isotropic antenna
Omni-directional pattern: f (θ, φ) = f (θ)o Pattern lobeso Side lobe levelo Beam width- HPBW and FNBW
SMART ANTENNA & ITS EVOLUTION Omni-directional antenna: radiates and receives well in all directions. Top View Antenna
Directional antenna: has certain fixed preferentialtransmission and reception directions. Top View Antenna Array
TYPE Omnidirectional DirectionalLIMITATION Element element Gain LOW HIGH Frequency reuse NONEInterference Rejection
Antenna diversity: uses two or more antennas toimprove the quality and reliability of a wireless link.Multiple versions of the same signal may be transmittedand/or received and combined in the receiver.o Spatial diversityo Polarization diversityo Pattern diversity
TYPE DIVERSITY COMBINING SYSTEMLIMITATION Gain VERY GOOD Capacity HIGHInterference LOW Rejection
Smart AntennaAn intelligent antenna system which is an antenna arraythat integrates the simultaneous operation of diversityschemes along with a digital signal processing capability totransmit and receive data.“Smart” >> digital signal processing facility
Smart antenna functionso Direction of arrival estimationo Beam steering
Benefits of Smart antennao Capacity enhancemento Coverage extensiono Increase in transmission efficiencyo Reduction of Co-channel interference (CCI) andMultipath fadingo Reduction of Bit Error Rate (BER)o Reduction in Handoff
Smart Antenna types Switched beam array: consists of either a number offixed beams with one beam turned on towards thedesired signal or a single beam that is steered towardsthe desired signal. Active Beam Antenna Array Coverage pattern
Adaptive antenna array: consists of an array of multipleantenna elements with the received signals weighted andcombined to maximize the SINR. Desired User Interfering User Antenna Array Coverage pattern
Comparison b/n Switched beam and Adaptive array systemsCRITERIA SWITCHED BEAM ADAPTIVE ARRAYSINTEGERATION • Easy to implement • Transceiver complexity • Low cost • High cost • Less hardware redundancyRANGE/COVERAGE • More coverage • More coverage compared to compared to switched conventional systems beam system • Less coverage compared to adaptive arrayINTERFERENCE • Difficulty in • Focusing is narrowerREJECTION distinguishing between • Capable of nulling desired signal and interfering signals interferer • Does not react to the movement of interferers.
ADAPTATION ALGORITHMSContinuous Adaptation: Automatically adjust weightsas the incoming data is sampled and updates it such thatit converges to an optimal solution, uses a referencesignal.E.g. The Least Mean Square algorithm (LMS), TheRecursive Least Square algorithm (RLS).Blind Adaptive algorithm: Adjustment of weightswithout the benefit of reference signal information.E.g. The Constant modulus algorithm (CMA).
o LMS algorithm generates better main lobes in desired userdirection but do not nullify co channel interference.o Interference rejection is better in CMA because nulls areproduced towards interfering signals. Hence nullifies cochannel interference but bears maximum errors.o RLS algorithm has better response towards co channelinterference, generates better main lobe in desired directionand has faster convergence rate than LMS, hence the best ofall.
APPLICATIONSMILITARY APPLICATIONo Makes the battlefield communication easier.o Power consumption is reduced on high speed multimediabattle field networks due to reduction in battery drain.o Spoofing is avoided.o Light weight video displays with in-built smart antenna usedin warfare to exchange real time maps and pictures.
SATELLITE COMMUNICATIONo SATCOM employs Space Division Multiple Access (SDMA).o more perspective for satcom systems for low (1500km)and middle (till 10000km) orbits.o Base stations are employed with smart antennatechnology.
MOBILE COMMUNICATIONo Economical to use adaptive antenna in base stationrather than at each mobile station.o Capacity problem is overcome by using multiple adaptiveantennas on mobile handsets.o Improves call reliability.o Suppress the interference signals.o mitigation against dead zonesE.g. Quadrifilar helix antenna (QHA) produced by SurreyUniversity and small solid state antenna as manufacturedby Antenova
WIRELESS SENSOR NETWORKSo Increased gain result from smart antenna which preserveconnectivity in sensor network and better usage of nodesenergy source.o Increase in Network life cycle due to improvements in SNRand BER.o Avoid sensor network resource depletion by usage ofswitched beam array antennas.
TERRESTRIAL TELEVISION RECEPTIONo Increase in BER would compromise with video or audio orsometimes result in no reception.o By employing automatic mechanism can adjust antenna gainand direction without user intervention.o Here smart antenna functions by changing relative gain andphase of internal elements.o Offers high degree of optimization for both signal capture andinterference rejection.
FUTURE SCOPEo MIMO systems employing smart antennas that fulfill IMT-advanced requirements is the core of 4G systems with1Gbit/s data rate and freq 20-100MHz.o MIMO systems fulfilling beyond IMT-advanced standardforms the 5G systems with more than 10 Gbit/s data rateand with a frequency of 200MHz.o Use of multiple smart antennas in mobile handsets toachieve much better performance.o Smart antenna based on UWB technology to detectmalignant tumors.
CONCLUSION Smart antennas are the intelligent antenna systems thatvastly improve the efficiency of wireless transmission. For applications including MIMO, Software Defined Radio- SDR, and Cognitive Radio - CR requiring antennasystems to be more adaptive and provide greater levels ofadaptivity Smart antenna technology is of wide use. Promising technology to resolve the traffic capacitybottlenecks in future high-speed broadband wirelessaccess networks and reduce RF pollution. Efficient utilization of the scarcest resource of today’swireless communication, the RF spectrum.
REFERENCESJensen M and J. W. Wallance, “A review of antennas and propagation for MIMO wirelesssystems”, IEEE Transaction of Antennas and propagation, vol. 52, pp. 2810-2824, 2004.R. H. Roy, “An overview of smart antenna technology and its application on wirelesscommunication systems,” Proc. IEEE Conf. Personal Wireless Comm., 2007, pp.234-238Chryssomallis, M., 2008. Smart antennas, IEEE Antennas and PropagationMagazine, 42(3): 129- 136.Sultan Budhwani, Mahasweta Sarkar and Santosh Nagaraj “A MAC Layer Protocol forSensor Networks using Smart Antennas”, IEEE International Conference on SensorNetworks, Ubiquitous, and Trustworthy Computing, 2010, pp 261-267.Luca Bencini, Giovanni Collodi, Divide Di Palma, Gianfranco Manes, Antonio Manes,” AnEnergy Efficient Cross Layer Solution based on Smart Antennas for Wireless SensorNetwork Applications” ,IEEE, COMPUTER SOCIETY, SENSOR COM, Fourth InternationalConference on Sensor Technologies and Applications. 2010, pp 232- 237.S.F. Shaukat, Mukhtar ul Hassan, R. Farooq, H.U. Saeed and Z.Saleem, "SequentialStudies of Beam forming Algorithms for Smart Antenna Systems", World AppliedSciences Journal, Vol. 6, no. 6, pp 754-758, 2009.