Simulation of a SAC-OCDMA 15 User System Using Hadamard Code

Author(s):  
Ahmed Abdul kadhim Jaber ◽  
Samir Jasim Mohammed ◽  
Ibrahim A. Murdas
Keyword(s):  
Author(s):  
Farzaneh Farhang Baftani ◽  
Hamid Reza Maimani

The support of an $(n, M, d)$ binary code  $C$ over the set $\mathbf{A}=\{0,1\}$ is the set of all coordinate positions $i$, such  that  at  least two codewords  have distinct entry  in  coordinate $i$.  The  $r$th  generalized  Hamming  weight  $d_r(C)$,  $1\leq r\leq 1+log_2n+1$,  of  $C$  is  defined  as  the minimum  of  the  cardinalities  of  the  supports  of  all subset  of  $C$ of cardinality $2^{r-1}+1$.  The  sequence $(d_1(C), d_2(C), \ldots, d_k(C))$ is called the Hamming weight hierarchy (HWH) of $C$. In this paper we obtain HWH for $(2^k-1, 2^k, 2^{k-1}$ binary Hadamard code corresponding to Sylvester Hadamard matrix $H_{2^k}$ and we show that    $$d_r=2^{k-r} (2^r -1).$$ Also we compute the HWH of all $(4n-1, 4n, 2n)$ Hadamard code for $2\leq n\leq 8$.


Author(s):  
Sandip Mandal ◽  
Supriti Samanta ◽  
Goutam Kumar Maity ◽  
Subhadipta Mukhopadhyay

2021 ◽  
Vol 20 (2) ◽  
pp. 67-82
Author(s):  
Eddy Wijanto

In this study, the performance of bipolar optical code division multiple access (OCDMA) with dual electro-optical modulator (EOM) scheme for multi-user scenario was tested and analyzed with OptiSystem version 10. The performance measurement was implemented for free-space optical (FSO) communication and includes the common noises in optical communication. Two different channels were used in the measurement, i.e., additive white Gaussian noise (AWGN) and fading channel. Two extreme weather conditions, strong rain and storm, were considered in the simulation. The performance between three spectral amplitude coding (SAC) codes, i.e., Modified M-Sequence code, Walsh-Hadamard code, and random diagonal (RD) code were measured and compared. The simulation results indicate that Modified M-Sequence code had the highest BER while RD code achieved the lowest BER in the short-range and Walsh-Hadamard code got the lowest BER for the medium-range of FSO, both for AWGN only and AWGN with fading channel. In strong turbulence condition, the performance of all codes become comparable after 500 m of FSO range. Modified M-Sequence suffered the lowest performance degradation while RD code endured the highest performance deterioration in all-weather condition. The results show that Modified M-Sequence can be applied for medium to long-range FSO.


2020 ◽  
pp. 2130001
Author(s):  
Agha Yasir Ali ◽  
Samiya Asghar ◽  
Rumaisa Iftikhar ◽  
Wang Shujun

This paper investigates the error probability of our proposed modulation technique which is produced by combining the existing pulse position modulation (PPM) technique with Hadamard code (HC). Moreover, the HC is also combined with differential PPM (DPPM). The error performances of existing technique and the proposed technique are compared at high-order modulation (HOM) and low-order modulation. The results show that the error performance of the proposed technique outperforms at HOM at the cost of higher bandwidth. This error performance is improved due to the bipolar nature of HC and it reduces the power requirements of the system.


Author(s):  
Supriti Samanta ◽  
Goutam Kumar Maity ◽  
Subhadipta Mukhopadhyay

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