International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 08 Issue: 06 | June 2021 www.irjet.net p-ISSN: 2395-0072 © 2021, IRJET | Impact Factor value: 7.529 | ISO 9001:2008 Certified Journal | Page 918 Performance Analysis of Multi-Identity High Power Codes (MIHP) Over Free Space Optical Communication System Lalit Kumar 1 , Shailesh Kumar Singh 2 1 Student M.Sc(Physics), Monad University, Hapur 2 Associate professor, Department of Physics, HimalayanGarhwal University Uttarakhand ---------------------------------------------------------------------***---------------------------------------------------------------------- Abstract -Optical code division multiplexing and free space optical communication integration provides an ultimate solution to provide enhanced reach and enhanced data rates. In this research work, a high speed data streams are supported over multi-identity high power codes (MIHP) over FSO. Simultaneous 10 users are catered 5 Gbps over diverse link lengths (2 km-10 km) and different beam divergences are also investigated. Moreover, diverse weather instabilities such as clear weather, light haze, heavy haze, rains are studied over FSO link and results are observed in case Q factor and BER. Comparison of double diagonal weight and multi-identity high power codes has been accomplished. It is perceived that MIHP codes performs superior than DDW codes due to high SNR because the potential of MIHP codes is high to carry high power levels. Key Words: Free space optics (FSO), Multi-identity high power codes (MIHP), optical code division multiplexing (OCDMA), Weather instability, Data rate 1.INTRODUCTION With the advent of technology, optical fiber communication emerges as a promising method to transfer information from one location to other. However, fiber optical is suffering from some limitations such as high installation costs, licenses requirement, trenching and bending losses etc. [1] [2] [3]. Free space optical technology is an ultimate candidate to provide solutions to issues which emerges in optical fiber communication. Laser source carriers are transmitted through air and save the cost of installation by trenching [4] [5]. It is the most excellent substitute for wireless communication systems to cater high data rate. Furthermore it offers operations without any license. But, despite many benefits of the FSO, it suffers from some limitations such as weather instabilities [6] [7] [8]. Atmospheric turbulences degrade the system performance because it affects the line of sight of the signal also decrease the visibility such as in case of rain, fog, haze etc. Some other factors are geometric losses, beam divergence, scattering of light etc. Scattering is also prominent issues of signal degradation because it disperses the light signals. Raindrops and snow are outcome the Geometrical scattering because the molecules of raindrops and snow are large and similar to Rayleigh scattering. In free space optical system, analysis of diverse weather condition is an important requirement [9].For the capacity enhancement, optical code division multiple access is ubiquitously operational in optical communication system. However OCDMA system suffer from different noises such as short noise, thermal noise, phase intensity induced noise (PIIN), multiple access interference (MAI). Multiple access interference is emerged in the OCDMA systems with cross correlation codes and MAI is performance degrading factor [10]. Spectral amplitude coding is a superior way out to decrease the effect of multiple access interference by using codes with zero cross correlation [11]. Some of the mostly used spectral amplitude codes are enhanced double weight (EDW), multi-diagonal (MD) codes, diagonal double weight (DDW), etc [4] [11] [12] [13] [14] [15] [16] [17].In this paper performance of multi-identity high power code is analyzed due to fixed cross correlation, less complexity and ability to cater high power under different weather conditions in free space medium. 2. CONSTRUCTION OF MULTI-IDENTITY HIGH POWER CODES (MIHP) First and foremost define an identity matrix of IN size, N represents the total users for which code will be constructed. In MHIP codes, two diverse matrices used and for first multi-identity matrices, cross correlation is zero. Basic significance of the multi-identity codes is that it can decrease the PIIN noise in spectral coding. (MI) represents multi-identity matrix and size of the matrix is given as N x N. Here, M is the total users. Let total users for example are 4 then and value of diagonal is i=4 Matrix becomes MI=[I4,1]= [I4,1, I4,2, I4,3 , I4,4] Formation of All One matrix In order to increase the weight of the multi-identity value equals to the code weight, a matrix having ‘1’s is created. In this matrix, there are N number rows which are same as users and for the total columns, w-i is used where i are diagonals and w is code weight. Consider an example of 4 users and set the value of diagonals equal to 2. Therefore ‘1’ matrix having two columns ad matrix is given as: