National Conference on Innovative Paradigms in Engineering & Technology (NCIPET-2012) Proceedings published by International Journal of Computer Applications® (IJCA) 31 Performance improvement in beamforming of Smart Antenna by using LMS algorithm B. G. Hogade Jyoti Chougale-Patil Shrikant K.Bodhe Research scholar, Student, ME(ELX), Principal, SVKM’S NMIMS,. Terna Engineering College, Pandharpur, COE Vile Parle ,Mumbai Nerul, Navi Mumbai. Pandharpur, Dist. Solapur. ABSTRACT The smart antenna adaptive algorithms achieve the best weight vector for beam forming by iterative means. Whether the algorithm is good depends on the convergence rate and steady state error. Beam forming is directly determined by the two factors. The performance of the traditional LMS algorithm is analyzed in this paper. Then a new variable step size algorithm is proposed and is applied to beam forming with the software Matlab. The simulation result indicates that the algorithm improved could achieve faster convergence and lower steady state error. Keywords Smart antenna, adaptive algorithm, LMS, beamforming, antenna arrays. . 1.INTRODUCTION A smart antenna is a digital wireless communications antenna system that takes advantage of diversity effect at the source (transmitter), the destination (receiver), or both. Diversity effect involves the transmission and/or reception of multiple RF-waves to increase data speed and reduce the error rate. In conventional wireless communications, a single antenna is used at the source, and another single antenna is used at the destination. Such systems are vulnerable to problems caused by multipath effects. When an electromagnetic field (EM field) is met with obstructions such as buildings the wavefronts are scattered, and thus they take many paths to reach the destination. The late arrival of scattered portions of the signal causes problems such as fading. In a digital communications system it can cause a reduction in data speed and an increase in the number of errors. Multi-path fading and delay spread lead to inter- symbol interference (ISI) and co-channel interference. The use of smart antennas can reduce or eliminate these problems resulting in wider coverage and greater capacity. Fig. 1. A functional block diagram of a smart antenna system. A smart antenna system at the base station of a cellular mobile system is depicted in Fig. 1. It consists of a uniform linear antenna array for which the current amplitudes are adjusted by a set of complex weights using an adaptive beamforming algorithm. The adaptive beamforming algorithm optimizes the array output beam pattern such that maximum radiated power is produced in the directions of desired