## 1 Introduction
The use of these color independent LEDs minimizes the interference by the filtering technique [22]. Further to improve the symbol error rate performance, a dynamic palette is generated based on the channel environment [23], and the circular Hough transform is used for the symbol decision. [24] The K-means clustering algorithm and regression analysis are proposed to minimize the variable effect of interference with respect to diverse light condition [25]. Further to improve the accuracy and symbol error rate (SER) performance, a boosting neural network (BNN) model has been proposed [26]. Another approach uses the Strokes transform in a uniform colored LEA to translate the Euclidean distributed LEDs to a 3-D stroke space. It enables LEDs to be placed across different layers of the stroke's dimensions, which minimizes the interference [27]. To facilitate real-time applications, a spatial clustering-based adaptive threshold technique has been proposed to minimize ambient and adjacent interference. As this MIMO communication uses a visible spectrum, it makes the masquerade aware of the transmission and vulnerable to attack. With a good quality camera, the masquerade may receive the transmitting signal and decode the secret information. Hence, security for the visual MIMO system has become a serious concern [28]. In literature, a secure visual MIMO system is developed by incorporating a key-based encryption and stenographic technique. A new modified version of the Rivets-Shamir-Adelman (RSA) technique [29] is used to encrypt the transmitted information using asymmetric keys. In a screen-camera based visual MIMO communication, a Laplacian pyramid and an IWT-based ARC-LSB embedding technique have been proposed to improve security [30; 31]. A key generation algorithm that generates a considerably large key provides better security. A random pixel value-based color image is used for key generation [32; 33; 34]. Bit sequences are generated from red, green, and blue planes of the color image. A single key is generated by concatenating these sequences of bits. Recent work involves the use of LSB of the adjacent pixels in the color image with an absolute difference of one to generate either keys or bit sequence [32]. Additionally, a histogram of the image is calculated, and its peak value is used to extract the key from the generated bit sequence [33]. Another approach uses the LSB to MSB to generate twenty-four sequences, and the randomness property is used to select the key [34]. A similar approach has been proposed in this work with higher computational complexity leading to more key strength. A customized LFSR based random key generation technique is developed, and the generated key is used to encrypt the incoming data using stream ciphers. A major contribution of this work includes, (i) design of QR inspired LEA, (ii) implementation of the particle filter for LEA tracking, (iii) customized LFSR based key generation using synthetic color image to provide security (iv) simulation studies in the presence of geometric distortions (v) spatial clustering-based adaptive threshold technique for minimizing interference (vi) real-time implementation and performance analysis of the proposed work. The rest of the paper is organized as follows; Section 2 presents the system model of the proposed MIMO communication with detailed insights on security and tracking algorithms. It also describes the formulation of the adaptive threshold technique. Section 3 discusses the performance analysis of key randomness. It also presents the simulation and real-time performance results of the tracking algorithm in the presence of geometric distortions. Section 4 concludes the paper with a discussion on future directions.