ADAPTIVE SMART ANTENNA Prepared By: Shivangi Jhavar Guided By: Mr.Bharat Patil

CONTENTS Antenna Types of Antenna Smart Antennas Types of Smart Antennas Switch Beam Antenna Adaptive Antenna Functioning Adaptive array configuration Adaptive beam forming Adaptive algorithms LMS Applications Pros and Cons of Adaptive Antenna Conclusion

ANTENNA An “Antenna” is transducer that transmits or receives electromagnetic waves. In other words, it is a transitional structure between free space and guiding structure. Heinrich Hertz invented the antenna in the era Antennas are used in radio and television broadcasting, wireless LAN, spacecraft communication, RADAR and cellular communication.

Various Looks of Antennas DEEP SPACE NETWORK ANTENNA GPS NETWORK ANTENNA

TYPES OF ANTENNA OMNIDIRECTIONALDIRECTIONAL LINEAR WIRE PATCHLOOPPARABOLI C ARRAY SMART ANTENNA

Various Antennas

SMART ANTENNAS They are antenna arrays with smart signal processing algorithms used to identify spatial signal signature such as the direction of arrival of the signal, and use it to calculate beam forming vectors, to track and locate the antenna beam on the target. Their applications are in the fields of radio astronomy, cellular networks. Smart antenna used in digital T.V.

SWITCH BEAM ANTENNA This system consists of fixed numbers of predefined configurations that can be accessed. It detects the signal strength, switch from one beam to another. Combine the outputs of multiple antennas in such a way as to form finely directional with more selectivity. Switch beam antenna used in military applications.

ADAPTIVE SMART ANTENNAS This array antennas are the most advanced smart antennas. This system uses new variety of multiple antennas and algorithms in order to maximize the strength of the signal being send and received by reducing the effect of interference or noise. They can effectively locate, track, identify, minimize the interfering signals and increase the signal reception. This point makes them more versatile and better than switch beam antennas. Adaptive antennas used in cellular technology

FUNCTIONING

The system converts the received signal into baseband signal. The Direction of Arrival algorithm tracks the required and null signals. This tracking is implemented by changing the weights i.e. amplitude and phase of signal. After the tracking the adaptive algorithm computes the weights which results in radiation pattern. This is implemented due to phenomenon of beam forming.

ADAPTIVE ARRAY CHOICE Phased Array Controlling the phase difference between the elements the maximum radiation can be directed along any direction. It consists of power dividers, switch, phase shifters. Parasitic Array It is formed using one active and several monopoles on the ground plane. changing the reactance alters the radiation of each element. lower power consumption.

ADAPTIVE BEAM FORMING Adaptive beam forming is a powerful technique of enhancing a signal of interest while suppressing the interference signal and the noise at the output of an array of sensors. Accomplished by phasing the feed to each element of an array so that signals received or transmitted from all elements will be in phase in a particular direction. Main beam point towards the user. Side lobes are reduced

How beam forming takes place ? Signal x(n) gets multiplied with weight vector coefficient w. Weighted vector gets summed to form y(n) i.e. output. Adaptive algorithm reduced error between y(n) and signal d(n) Weights are slowly varied to steer the beam to get maximum signal. Weight Wk is combination of phase and amplitude.

ADAPTIVE ALGORITHMS Adaptive Beam Forming Algorithms Blind adaptive algorithm Non blind adaptive algorithm Do not need any training signal.  They use some of the known properties of the desired signal.  The goal is to retrieve the input signal using output signal.  Used a training signal d(n) to update its complex weight vector.  In receiver beam former uses this information to compute new complex weight. Ex: Constant Modulus Algorithm(CMA) EX: Least mean square (LMS), Recursive mean square (RLS)

LMS ALGORITHM Least mean squares algorithms are a class of adaptive filter used to mimic a desired filter by finding the filter coefficients that relate to producing the least mean squares of the error signal. It requires no direct matrix inversion and memory. It uses steepest descent method and updates the weight vector. Calculations are easy to compute and its applicable to real time applications.

…N=1 LMS algorithm.

LMS ALGORITHM For order p, n=0,1,2…..

APPLICATIONS Cellular Communication Radio Communication WiMaX RADAR Military Satellite communication

Adaptive antennas are used in wireless mobile communication. They reduce interference, hence making the communication more powerful, faster and increase the rate of data bytes, also signal reception.

SATELLITE USING ADAPTIVE ANTENNA ARRAY

ADVANTAGES Increased range and coverage Increased capacity Lower power requirements and cost reduction Improve link quality and reliability Security Reduction in handoff Spatial information Increased spectral efficiency

DISADVANTAGES Transceiver Complexity Resource management Physical size

CONCLUSION Adaptive antenna has immensely increased the spectral efficiency thereby, making the wireless communication faster and easier. Thus, we can term adaptive antennas as the future of wireless communication.

REFERENCES [1] W.F.Gabriel,”Adaptive nProcessing Array Systems,” Proc.IEEE, vol.80,no.1.pp, , January 1992 [2] J.D.Kraus, Antennas, Mcgraw-hill, New york, 1988 [3] R.C.Hansen,”Array pattern control and synthesis”, Proc. IEEE,vol. 80,No 1,pp , January [4].Sheikh's.; Gesbert D; Gore.D; Paulraj.A “Smart antennas for broadband wirelessacess networks” “IEEEcommunications Magazine” volume 37,issue 11,nov Page [5] T.S.Rappaport, Smart Antennas: Adaptive array, Algorithms, IEEE,NJ,1998.

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