Beam Adaptive Algorithms For Smart Antennas Computer Science Essay

Beam reconciling Algorithms For yen overtures Computer Science judgeSmart barbels employed in space division doubled access schemas commode cater the towering demand in terms of susceptibility in smooth applications with turn up further increase in piano tuner oftenness spectrum al locating. Further much, bruise advances provide better quality of service (QoS) and better coverage. Therefore, glisten adjustive algorithmic rules utilize in ingeniousness approach clays ar of great interests.1.2 Project AimsThe pop out aim is to study and make the adaptational algorithms for shot readying for Smart overture Systems and to develop look skills, by reading research papers and diary papers related to the topic. nonwithstanding, to produce the technical draft that contains the analysis, results and coverion of several adaptive algorithms employed in Smart Antenna Systems. The research work conducted and a simulation provide provide the better intellect of the subject and dissolve be a possible contribution to the existing work.1.3 Project ObjectivesThe project clinical is to attempt agreementatic comparison of the exercise of diametrical reconciling Algorithms for mailforming for Smart Antenna System. The algorithms that will be under investigation in this project will be training sequence algorithms like algorithmic least(prenominal) Squ ars (RLS) and to the lowest degree nasty Squares (LMS), and Constant Modulus Algorithm (CMA). Simulations will be done to bugger off out which algorithms are best for cockforming i.e. to form main lobes towards coveted drug drug drug delectationr and for point of intersection order. The comparison of algorithms will be made on the basis of formation of main lobe and the convergence rate. The effect of jammers in algorithms will too be studied.1.4 Project OutcomesThe outcome of the project is come up with simulation software that will count the parameters of Smart Antenna a nd tell us which algorithm performs better in a especial(a) situation. Moreover to prepare a research report that contains critical analysis different cock adaptive algorithms.1.5 building of the reportThe first chapter of the final report is the Introduction which describes the motivation for research, project aims and objectives. The second chapter is the writings review. The overview of late work conducted in this domain and the brief summary of several research papers studied for conducting this research has been presented. Reading list is appended in the references section. Third chapter is the introduction to approachs and languish forward passs. The fundamentals parameters of transmitting aerials and expert antennas are presently described. Fourth chapter is on lustrous antenna frame. Types of smart antennas and their comparison are done in detail. In fifth chapter description about the forecast affect algorithms is presented. Lastly confoundn are the results and conclusion.Chapter 2 Literature ReviewSmart antenna is the around efficient leading innovation for level best mental object and change quality and coverage 1. They bunghole adapt to varying traffic requirements dynamically. Smart antennas radiate narrow beam to serve different users and are normally employed at base localizes. The complex weight computations that are found on different criteria are incorporate in the note processor in the form of software algorithms 3. Due to the rapid growing demand in mobile applications not only for qualification but for high quality of service (QoS) and better coverage without increasing the radio frequency spectrum allocation the wireless organizations that uses indomitable antenna systems will no longer be in use 3 discuss the need for smart antennas in space division multiple access systems. The article foc employ on adaptive beam forming approach based on smart antennas the adaptive algorithms that are employed to envision t he complex weight are discussed and LMS and RLS in particular. The fact that error computed from the filter at time n is used to provide the filter coefficient at time n+1 provides a nontraditional modality to understand adaptive algorithms. 2 describe the approach of seeing classical adaptive algorithm like LMS, RLS, CMA, decision directed) as recursive structures. 4 Explain the normalized least mean square (NLMS) algorithm for smart antenna system. The algorithm was implemented on the StarCore SC3400 DSP core and the execution of instrument was evaluated on MSC8144 DSP and the antenna coverage pattern was obtained and analyzed to find towards the desired orient source. With adaptive beamforming algorithm to name LMS for smart antenna the down pop to buildher multiple-input multiple-output (MIMO) multi-carrier code division multiple access system is proposed 5. 1 Describes the sequential Studies of beamforming algorithms for smart antenna systems.2.1 Scope of Smart AntennasSma rt antennas assured to concede the significant increment in the capacity of system and its performance in the wireless conversation system 11. Which will eventually lead into increase profits for the tele conversations companies and also a decline in block up and dropped calls.Its been about 45 years Antenna was first used in applications related to radar communication in the form of fixed vagabond. In later years many an(prenominal) researches on antenna helped into smart antennas and tiled the way for their uses in commercial wireless systems 12. These are the main reasons smart antennas got so more than interest over the few years. At present the application of smart antennas are predominant at the mobile base stations due to compact commonwealth and processing condition requirements 13. Currently, a circulate of research is going on the mobile terminal based smart antennas. In the coming early we can expect smart antenna skills to be present at the base station and mob ile terminal too.Chapter 3 Introduction to Antennas and Smart Antenna3.1 AntennaAccording to IEEE Standard Definitions of Terms for Antenna, it is defined as a means for radiating or receiving radio waves.3.2 Fundamental parameters of AntennaThe fundamental parameters of Antenna are irradiation patternRadiation frenzyDirective bring in and directivity agent progress to and Radiation efficiencyFront to Back ratioAntenna beamwidthAntenna beam efficiency3.2.1Radiation radiation diagramRadiation pattern show the angular variation of field effect. They are bugger offn at just about distance r proportional to field intensity in the direction and .Normalized Field PatternIt is obtained by dividing the field component by its maximum value. It is dimensionless.E(,) = E(,) / E(,) maxPower Radiation PatternPower density Pd is defined as military group flow per unit theater of operations and is given byPd(,) =1/2*E (,) 2/0Pattern may also be expressed in terms of power per unit solid wobble .The normalized power pattern can also be expressed in terms of this parameter as the ratio of radiation intensity U(,) as function of angle to its max value.Pn(,) = Pd(,) / Pd max(,)The co-ordinates are and dB are used to draw the pattern and calculate by following relationdB= 10log10Pn(,)3.2.2 Radiation IntensityThe power radiated from an antenna per unit solid angle is called the radiation intensity U.3.2.3 Directive Gain and DirectivityFor omnidirectional antenna the power density at all the points on the surface of a sphere will be very(prenominal).Pavg = Prad/4r2The directive gain is defined as the ratio of the power density Pd(,) to the average power radiated. For isotropic antenna, the value of directive gain is unity. The directive gain can be defined as a measure of the concentration of the radiated power in a particular direction (,) . The ratio of the maximum power density to the average power radiated is called maximum directive gain or directivity of the ant enna.GDmax = Pdmax/Pavg3.2.4 Power Gain and Radiation efficiencyThe relation amid input power and power radiated is given asPrad=r Pinr=Prad/ PinPin=Prad +P injuryr=Prad/(Prad +Ploss)The power radiated and the ohmic power loss can be expressed in terms of r.m.s. current asr=Rrad/(Rrad +Rloss)The ratio of the power radiated in a particular direction (,) to the actual power input to the antenna is called power gain of antenna.3.2.5 Front to Back ratio (FBR)It is the ratio of the power radiated in the desired direction to the power radiated in the opposite direction.FBR = Power radiated in desired direction/Power radiated in opposite directionFBR depends on frequency of operation, spacing betwixt antenna elements (inversely proportional) and electrical length of the parasitic elements of the antenna. FBR is an important consideration specially in receiving antennas3.2.6 Antenna BeamwidthAntenna beamwidth is the measure of the directivity of the antenna. The antenna beamwidth is an a ngular width in degrees. It is measured on a radiation pattern on a major lobe.3.2.7 Beam efficiency replete(p) beam knowledge domain A consists of the main beam area M plus the minor lobe area m.A= M+ mSo Beam Efficiency is,M= M/ A cheat on FactorThe ratio of minor lobe m area to the total beam area A is called wander factor.Em= m/ AEM + Em= 13.3 Smart AntennaThe smart antenna is defined as an antenna array system that is supported by processing system that deals with the original and transmitted signal by the array development proper array algorithms to advance wireless system performance. 4Numbers of distributive antenna elements are combined to make arrays of antennas called smart antenna. The different signals collected by individual antenna are cipher in such a manner that increases the signal strength of desired signal and reduces impedence from new(prenominal) signals. 12A smart antenna can be observed as a combination of antennas, whose transmitted or received sign als are processed using smart algorithms. These smart algorithms make antenna work efficiently, and reli able in communication 13. Main purpose of smart antenna is that the signal comes from the source hit the target in that way if the target is moving the antenna is such a smart and intelligent that it would change its direction according to the target movement and the main lobe of the antenna moldiness be toward the target so that the maximum strength of the signal strikes the target. virtuallyly Smart antennas are being used in wireless communication systems to provide interference reduction and stir user capacity and the data rates 6.3.4 Uses of Smart AntennaSmart antennas are considered useful in the wireless communication systems. The area coverage and the capacity of a system are increased by Smart antennas. Maximum data rate is increased by using smart antennas in multipath and moderate fading due to the terminating the component of multipath. One of its most useful appli cations is direction finding with the applications including emergency go and traffic monitoring 11.In areas with less population, extended coverage is predominant in those areas than increased capacity. I such areas the gain provided by the antennas can extend the range covered by a carrel and hence more users can communicate with less system capacity than any other typical antenna.It is used for the interference reduction and rejection as well. Finding the location of user will be a useful application of smart antenna, geo-locations of user and to make downlink beam forming easy 14.Smart antennas are presently used in Radars, Radio astronomy and mostly used in cellular systems to keep the system speed equal with the number of increasing subscribers. It is also used in defense for safe communication purpose.3.5CHARACTERISTICS OF heady advanceThere are four main characteristics of smart antenna,DOA (direction of arrival) evaluationBeam forming,antenna diversitybeam-width3.5.1 DIRECTION OF ARRIVAL / ANGLE OF ARRIVALA measure of the direction of the propagation of electro magnetic radiation upon arrival at a receiver it is the angle between the plan of the level comportment and some plan of reference, usually the level, at the receiver antenna. 9Direction of arrival indicates the direction from which usually a signal arrives at a point 3. We can guess the direction of arrival of the signal by using different techniques like multiple signal classification. In this technique an algorithm is used to for frequency estimation and the location of emitter, matrix pencil method or their derivatives. 9UsageGeodesic location or Geo-location of the cell phones is the main application of direction of arrival nowadays 9.Multiple base stations calculate the angle of arrival of the cell phone signal and this randomness is combined to locate the cell phone anyplace on the earth.It is generally used to locate the pirate or military radio transmitting point. In subm arines acoustics, angle of arrival is the method to localize objects with active and passive ranging 9.3.5.2 BEAM-FORMINGBeam forming is a technique of digital signal processing and its is used for directional signal transmission or reception form the preferred signal direction as compared to some undesired direction 3. It mean that the techniques which we used reserve the dexterity to make the radiation pattern of the antenna by constructive and destructive interference for reception and transmission and to accept moving beams in the direction of preferred signal and put nulls in the direction of meddling signals. This mean due to this co- passage and interference reduce and antenna gain is increased in the direction of desired signal 13. exercise 3.1These rebounds from different surfaces can set up time delays, attenuations, phase shifts, and distortions that can interfere with each other at the receiver end of the antenna. It can be set by the digital signal processing techni ques used in smart antenna system 15.3.5.3 ANTENNA DIVERSITYAntenna diversity uses more then two antennas to develop the quality and dependableness of a wireless link 3. Specially in the areas where LOS is not clear between transmitter and receiver. Before reaching at the receiver end signal is reflected along several paths. This result in introducing phase shift, time delays, attenuation, and distortion which results in the interference between signal arriving before and after the particular signal 9.As two or more antennas receive several observations of the same signal they will calculate the most strengthen signal give the output.3.5.4 BEAM-WIDTHIt means the half(prenominal)-power beam-width 7. The maximum radiation strength is found, and then the points on both side of the maximum, represent half power of the maximum strength are located. The distance between the half power points is known as the beam-width 16.Half of the power expressed in decibels is -3dB, so half power be am-width is often referred to as the 3dB beam-width. We considered both horizontal and vertical beam-widths. 63.6 TYPES OF SMART ANTENNASThere are two major types of smart antenna transformationed beam smart antenna and adaptive array smart antenna.3.6.1 SWITCHED BEAM SMART ANTENNAThere are different permanent beam patterns presented in switched beam system. A decision is made as to which beam to be taken, at any given point in time, depend upon the necessities of the system 3.3.6.2 ADAPTIVE ARRAY SMART ANTENNAIt allows the antenna to focus the beam to any direction of direction of desired signal perpetually ignoring interfering signals. Beam direction can be estimated using the direction of arrival (DOA) estimation methods 3.3.7 ADVANTAGESFor the most part smart antennas are employed at the base station in the mobile net profit to improve system capacity. Capacity means the number of the users that can be handled in a system. use of Omni-directional antennas originate co-channe l interference when two users use the same band of frequency that finally limits the user capacity in the system 8. In case of smart antennas beams are focused towards the desired user slander interference to other users using the same frequency band.0 get wind 3.2It helps against multipath fading noise which improves dependability of received signal. Reduced power consumption for cell phones, low probability of interception and detection improve location estimation and meliorate range of reception 1.3.8 DISADVANTAGEMost major disadvantages of smart antenna is in their design and completion in hardware. Multi RF chains can boost the price and make the transceiver bulkier 4.Most of the devices in the making of a typical antenna used non-linear devices and using smart antenna also increases the components used. If not checked properly, this affects the performance of the antenna 15.As the data bandwidth necessary for the digital signal processing increases with the number of ante nna elements used. This can limit the data rate for different applicationsChapter 4 SMART ANTENNA SYSTEM4.1 INTRODUCTIONSmart Antenna System is combination of multiple antennas which Transmit or receive Signals using an Adaptation Algorithm 4. A smart antenna system is combination of many antennas elements with a signal receiving and transmitting ability to optimize its radiation and reception pattern robotically in reaction to the signal environment 10.4.2 TYPES OF SMART ANTENNA SYSTEMSThere are mainly two ways to implement antennas that dynamically change their antenna radiation pattern to minimize interference or multipath affects by increasing coverage area and range. Switched beam There are finite numbers of fixed patterns which are defined by the system (sectors) Adaptive arrays There are an infinite number of patterns (scenario-based) which are adjusted in original timeThe Switched beam approach is easy and simple then the adaptive approach. It increases the network capacit y as compared to the usual Omni-directional antenna systems. In this technique, an antenna array produces over lapping beams that cover the neighboring area as in the figure 17. When a signal is coming and detected, the base station determine the beam that is best associated in the signal-of-interest direction and then switch that beam toward the user for communication 6.0 Figure 4.1 17The Adaptive array system is efficient then the switched array technique 2. A mobile user is tracked by this system continually by routing the main beam towards the destination and at the same time sending no signal in the direction of interfering signals like switched beam.0 Figure 4.2 174.2.1 SWITCHED BEAM SYSTEMSSwitched beam antenna systems make many fixed beams with finely tuned sensitivity in particular directions 17. These antenna systems detect strength of signal, choose one from numerous already determined, fixed beams, and switch his beam from one beam to another as the user moves during th e sector 11. The output of many antennas combine by means of Switched beam systems in such a way that it form finely directional beams with more selectivity than can be achieve with usual, single-element antenna technique.4.2.1.1 WORKINGIn this type of adaptive approach in reality did not steer or scan the beam in the direction of the desired signal 17. Switched beam use an antenna array which radiates a number of overlapping permanent beams covering a elective angular area. The directional beam leads to increase the factor of a frequency reuse in channel by decreasing possible interference and it also increases the range 14. These antennas system not have a uniform gain in all directions but when they are compared to simple antenna system they have more gain or increased gain in the desired directions. The Switched beam antenna has a switching method that enables the system to select and then switch the desired beam which gives the best reception for a mobile user. The selectio n is generally based on maximum received power for user 9.0 Figure 4.3 3A usual switched beam system for a base station consists of many antennas with each array covering a certain sector in cell. Take an slip of switched beam-forming system below 7. It consists of a phase shifting network, which forms many beams look in certain directions. The RF switch targets the correct beam in the direction of interest. The measurement for selecting of the correct beam is done by the reckon logic unit. The control logic unit is controlled by an algorithm which scans all the beams and then selects that beam which is strongest signal based on a measurement calculated by the algorithm.0 Figure 4.4 17This technique is not good when interference is high this technique is simple in operation. Let us consider an example where User 1 is at the side-edge of the beam receiving low power which is entertained by this beam 6. If in that location is a second user were at the direction of the null then the re will be no interference but if the second user also moves into the direction where user 1 is located then there will be interference occur therefore the switched beam system is competent where there is no interference 174.2.2 ADAPTIVE ARRAY ANTENNASSwitched beam systems only give a control performance improvement when compared to common antenna systems in wireless communication 3. Greater improved performance can be achieved by using superior signal processing technique to practice the information achieved by the antenna arrays. The adaptive array system is Opposite to switched beam systems, they are smarter because they are able to react to the changing RF environment. They have a huge amount of radiation patterns as compared to fixed finite patterns in switched beam systems to adjust in the changing radio frequency environment 9. An Adaptive array is just like a switched beam system which use number of antennas but they are controlled by signal processing 17. This signal proc essing moves the radiation beam towards a desired user as he changes his direction and ii limit the interference happen from other users by ready nulls in their directions. This is shown in figure below 17.http//i.cmpnet.com/embedded/gifs/2005/0503/0503feat1fig2.jpg0 Figure 4.5 174.3 COMPARISONHere are the differences between switched bean array and adaptive beam array4.3.1 SWITCHED BEAM SYSTEMIt uses many planned directional beams with slim beam-widths.The necessary phase shifts be provide by normal preset phase shifting networks e.g. the butler matrix 11.They do not need tall(prenominal) algorithms, easy algorithms are used for selection of beamIt need only reasonable relations between mobile and base station as compared to adaptive array system 15.Because low technology is used it has minor price and complication. premix is easy and cheap into existing cellular system.It give important increase in coverage and capacity compare normal antenna based systems 6.Since many slim bea ms are used, normal intra-cell hand-offs occur between beam when a mobile moves from one beam to another 15.It does not make a characteristic between direct signal and interfering signal this leading to undesired improvement of the interfering signal more than the desired signal 6. Switched beam systems offers limited co-channel interference control as compared to the adaptive array system.4.3.2 ADAPTIVE ARRAY SYSTEMA whole adaptive system moves the beam towards desired signal and put nulls toward interfering signal directions 17.It is implemented on DSP technology 17.To steer the beam and the nulls complicated adaptive algorithm is required 6.Rejection capably of interference is much better then the switching beams system 15.It is difficult to impose on existing systems, i.e. up gradation is hard and costly.Since nonstop moving of the beam is required as the user moves, high contact between the mobile and base station is required 17.It provides improved coverage and improved capac ity because of improved interference elimination as compare to the Switched beam.It can each decline multipath components or add them by correcting the delays to improve the signal quality6.4.4 ANTENNAS SMARTNESSSmart antenna systems using these adaptive systems are quite smart in the true sense and that is why they are referred as smart antennas 17. The smartness of these systems is due to the intelligent processor using digital processing techniques which are integrated in these systems. These signal processing techniques use complex algorithms which are our main concern in our project 11.As modern world is using advanced technology in different fields, smart antenna also comes with such type of digital formation algorithms that operate the signals in accurate and flexible manner. On the way to the smart antenna, the signal is received, converted and modulated for transmission into digital signal and at the other end it is reconverted in analog information 5.4.4.1 BASIC MECHANISM There are a share of function a smart antenna can perform on the bases of techniques used for desired scenario. close to of them major functions smart antenna can perform are listed belowFirst Smart antenna can locate the direction as well as the angle of arrival of all the entry signals 16. Whether they are interfering in the signal of our interest or they are same signals arriving at the antenna from different directions after reflection from different surfaces. Their direction is estimated by the processing techniques used in smart antennas.Secondly The signal of our interest can separated from the cluster of all the incoming signals using smart antenna systems.Lastly a beam is moving in the direction of the desireed signal and the user is traced when he moves in the area and placing noting at interfering signal directions by continually updating the weights 17.It is comely obvious that the direction of radiation beam of the main lobe in an array depends upon the phase diffe rence between the elements of the array. Thus it is possible to constantly move the main beam in any direction by adjusting the phase difference between the elements. The same concept is used in adaptive array systems in which the phase is tuned to attain highest radiation in the most wanted direction.4.5 ADAPTIVE ALGORITHM CLASSIFICATIONSThe adaptive algorithms can be classify into category base on different approach given below day-and-night adaptation The algorithms based on this technique fine-tune the weights as the arriving data is sampled and continue updating it in such a way that it converges to an finest solution. This approach is suit able when the signal information is varying with time.Examples The least Mean Square (LMS) algorithm and the Recursive Least square (RLS) algorithm 17.Block adaptation The algorithms based on this technique calculate the weights depend on the approximation achieve from a temporary stumblebum of data 3. This method can be used in a non-stati onary situation provided the weights are calculated from time to time.Example The Sample Matrix Inversion (SMI) algorithm 17.Reference signal based algorithms These types of algorithms worked on the principal of minimization of the mean square error between the received signal and the original signal. thusly it is necessary that an original signal is available which has high relationship with the desired signal 17.Examples The Least Mean Square (LMS) algorithm, The Recursive Least square (RLS) algorithm 17.Blind adaptive algorithms These algorithms do not want any original signal information. They are generating the necessary ordinal signal from the received signal to get the desired signal.Examples The Constant Modulus Algorithm (CMA).CHAPTER 5ALGORITHMSIt is obvious that themselves antennas or not much intelligent to perform such.It is the wideness of antenna system which is such clever in aspect of advanced signal processing algorithms. In order to use the smart antenna to its f ull smart techniques superior and computationally smart algorithms must be used.There are number of algorithms which are optimized and specialized for different smart antenna system and for different scenarios. For this purpose here are the few algorithms we have studied till the day to get a brief idea about the smart antenna systems are given below.LMS (Least Mean Squares)RLS (Recursive Least Squares)CMA (Constant Modulus Algorithm)We will try to give a logical comparison on the performance of different Adaptive Algorithms for beam forming for our Smart Antenna. In this study we have exposed that these algorithms RLS and LMS are best for making beam forming like main lobe towards desired user but they have boundaries towards reject interference. In case of CMA has improved response towards beam forming and it gives improved results for interference rejection, but there is a problem the Bit mistake Rate (BER) is greatest and high in case of single antenna element in CMA. It is con firm that convergence rate of RLS is faster than LMS so RLS is proved the best choice for us. The effect of changing maltreat size for LMS algorithm has also been studied.5.1 CMA (CONSTANT MODULUS ALGORITHM)CMA is based on those methods which are old but many of them are modified or completely changed techniques. This is popular algorithm and we are using this algorithm for blind adaptive array processing for beam pattern. But there is a problem with this algorithm it has low convergence rate because it is a type of instant gradient searching method depend on performance surface. Later some enhanced algorithms such as orthogonal constant modulus (OCMA) and least square constant modulus algorithm (LSCMA) are proposed 4.OCMA use the Newton algorithm and LSCMA is a type of block-update interactive algorithm. Both use estimation of revision of covariance matrix. This means high calculation complexity and convergence rate is improved. But they will not converge when covariance matrix is positive and singular. Faster convergence rate, constant convergence steps, lower computational complexity and better numerical stability will be achieved with instant gradient searching and combine gradient algorithm 2.ConclusionA constant modulus algorithm based on modified conflate gradient for adaptive array processing. CMA algorithm has the similar performance as high convergence rate algorithm such as LSCMA there is an advantage that they do not need to perform matrix inversion and its performance is improved then other type of conjugate gradient algorithms5.2 LMS (Least Mean Squares) and RLS (Recursive Least Squares)An adaptive algorithm has a natural recursive formation even in the case of a limited impulse response modelization. As the error