Suresh Kumar Jindal Int. Journal of Engineering Research and Applications www.ijera.com ISSN : 2248-9622, Vol. 5, Issue 4, ( Part -6) April 2015, pp.01-09 www.ijera.com 1 | Page Closed-Form Performance Analysis of Dual Polarization Based MIMO System in Shadowed-Rician Fading LMS Channels Suresh Kumar Jindal Suresh Kumar Jindal is with Defence Research and Development Organization, New Delhi, India Abstract In this paper, the problem of dual polarization based MIMO Processing in Shadowed-Rician (SR) fading land mobile satellite (LMS) channels is studied. It is shown in literature that polarization is used as a interference rejection method; and, most of the existing analytical results are not in closed-form. In this paper, we derive the closed-form expressions of the moment generating (MGF) function of the received signal-to-noise ratio of the MRC based receiver in SR fading LMS channels. Then we provide closed-form expressions of the symbol error rate (SER) by using MGF approach. The analytical diversity order and capacity of the considered scheme is also derived. It is shown by by derived closed-form capacity expression that the capacity of the considered dual polarization based scheme is improved; and it is found very useful in practical satellite communication systems. Index Terms: Land mobile satellite (LMS) channel, M-ary phase shift keying (M -PSK), Polarization, M -ary quadrature amplitude modulation (M -QAM), Shadowed-Rician fading. I. INTRODUCTION Satellite systems are very useful in broadcasting, disaster relief, and navigation. These systems are also beneficial in under-populated areas [1]. Multiple antenna b ased techniques are useful for improving the performance of the satellite based communication system [2]. By using multiple antennas at the earth station and using maximal ratio combining (MRC) the quality of signal reception can be improved. But it is difficult to install multiple antennas at the satellite due to involvement of high cost in designing the satellite system, in practice. Therefore, dual polarization based approach makes this system more useful in terms of available bandwidth. Two independent signals can be transmitted on the same frequency band by means of two orthogonal polarizations. Hence, we can say that the two orthogonal polarizations can be viewed as two data streams transmitting simultaneously and allowing to double the available spectrum. In [3], the Shadowed-Rician (SR) channel model is proposed which describes very accurately the land mobile satellite (LMS) channel and yields significantly less computational burden as compared to other LMS channel models. The MRC scheme for SR fading based LMS channels has been analyzed in [4]– [7]; nevertheless, most of the analytical results are provided in the form of infinite power series, which are not in closed-form. Whereas, closed-form analytical expressions are more suitable for understanding the characteristics and practical implementation of a communication system. Recently, hybrid satellite-terrestial communication system is discussed in [8]–[13], [21]. Another useful model for the LMS channel is recently discussed in [7] by using the κ − µ shadowed random variables. This model is more accurate for modelling the satellite links than S-R fading but has a complicated form. Because multiple antenna based terrestrial communication systems are widely utilized [25]-[30], therefore it is useful to study the satellite communication system with multiple antennas. In this paper, we provide closed-form expressions of the moment generating function (MGF) of the received signal-to-noise ratio (SNR) of the MRC scheme based satellite communication system, over SR fading LMS channels. By using these expressions, we get the bit error rate (SER), diversity order, and capacity of the scheme. II. SYSTEM MODEL We consider a satellite, with a single antenna, transmitting signals to an earth station containing  receive antennas. The data stream at the satellite is transmitted in two parts; one part uses left-hand circular polarization and other part uses right-hand circular polarization. The signals received at the receiving-end can be written as   =     +   , (1) and   =     +   , (2) where  ∈ℂ ×1 and   ∈ℂ ×1 contain the channel gains between left-hand and right-hand feed of the transmit antenna and receive antennas, respectively;   and   , with   average power, are the signals transmitted by the satellite; and   ∈ℂ ×1 and   ∈ℂ ×1 denotes the complex-valued additive white Gaussian noise with zero-mean and  2 variance. The channel vectors   and   with independent and identically distributed (i.i.d.) SR fading entries can be modeled as   =   +   , RESEARCH ARTICLE OPEN ACCESS