Ratan Kumar Mondal

Opportunistic channel reuse for a self-organized visible light communication personal area network

We investigate the adverse effect of interference in a visible light communication personal area network (VPAN) installed inside a museum. A VPAN should support diverse traffic in commercialized deployment. However, the state-of-the-art VPAN suffers from interference while supporting diverse and multidimensional traffic. The key challenge remains to satisfy and manage diverse quality of service (QoS) requirements of various applications while keeping the interference under the threshold level. Therefore we proposed interference bounded opportunistic channel allocation strategies for visible light communication personal area network (VPAN) in a cost effective manner which intends to maximize the sum rate capacity in the downlink channel and thereby allow maximum number of users within a target QoS. Performance analyses show improvement in terms of outage probability and throughput maximization.

Receiver performance improvement utilizing diversity in MIMO VLC

Visible light communication (VLC) using light emitting diodes (LEDs) has become a benchmark for high speed data communications, especially in indoor applications. In order to achieve high data rate for VLC system, multiple input multiple output (MIMO) is a feasible option. However, contemporary MIMO-VLC system lacks from diversity and experiences performance variation through different optical channels. In order to achieve receiver diversity and mitigate performance variation, we propose maximal ratio combining (MRC) method to improve VLC receiver performance. Simulation results demonstrate performance improvement in terms of received power and bit error rate.

Interference-aware optical resource allocation in visible light communication

As visible light communication (VLC) system continues to promising solution of spectrum shortage, resource allocation is becoming a concern in IEEE 802.15.7 wireless personal area network (WPAN) research. Due to the improper utilization of non-overlapping channels such networks suffer from the co-channel interference and hence system performance is degraded. In this paper, we propose a resource allocation scheme that selects non-overlapping channels having best signal-to-interference plus noise-ratio (SINR) and acting indirectly on the interference levels. Our proposed scheme assigns the visible light multicolor logical channels such that the co-channel interference is minimized. The numerical analysis shows that the interference aware channel assignment scheme can effectively reduce the dropping probability and increase the utilization of large visible light bandwidth.

Performance enhancement of MIMO based visible light communication

The camera based visible light communication (VLC) is the merger of VLC with vision technology in order to deploy VLC features in hand-held devices e.g., in Smartphone, employing light emitting diode (LED) transmitter to camera communication. However, the most advantageous features of VLC technology have not been achieved due to the low frame handling rate in camera module. In contrast, the spatially light source separation characteristic in camera module explores the scope to deploy multiple-input multiple-output (MIMO) concept for enhancing the overall system capacity and robust signal reception in camera based VLC system. In this paper, the performance of spatial multiplexing in MIMO based VLC system is evaluated.

Dynamic resource allocation for visible light based wireless sensor network

Optical signaling has added a new dimension to contemporary wireless sensor network (WSN) as a green and energy efficient technology. Optical wireless communication is considered to replace radio frequency in future sensor network. In fact, Optical wireless communication using visible light has become a benchmark technology in order to improve the speed and robustness of the communication link in indoor wireless sensor network and considered to be featured heavily in future sensor network. In this paper, we propose a novel resource allocation for visible light based WSN. We propose joint power allocation and bandwidth allocation for downlink transmission. Then we propose admission control to guarantee quality of service (QoS) in order to maintain service requirement. The simulation result shows satisfactory performance improvement.

Simple method for indoor localization in OCC using smart phone image sensor

Indoor localization technique is one of the key research issues due to highly demandable market value to provide Location Based Services (LBS) using smart phone. In optical camera communication (OCC) case one of the main advantages in indoor navigation system is LED itself can transmit location information along with unique feature of a camera to detect location using photogrammetry. This paper provides a simple approach to estimate user location in OCC.

SINR-Constrained Joint Scheduling and Optimal Resource Allocation in VLC Based WPAN System

A joint scheduling and optimal resource allocation scheme for wireless personal area network using visible light is proposed. In current IEEE 802.15.7 standard, multiple channel scheduling in medium access control (MAC) layer and variable data rate opportunity in physical layer (PHY) are performed separately. Therefore, the resources are not utilized effectively owing to the exclusion of channel variable characteristics during the scheduling. In this paper, the case for combining the PHY and MAC layer into a cross-layer platform is conducted for utilizing the resources efficiently. Generally in visible light communication (VLC) system, data rate of one link impacts on its neighbor link due to their high signal-to-noise ratio and this impact varies gradually according to some perspectives such as, field-of-view interaction and distance, hence allocated rate of both users could be dissipated. Moreover, the cell radius in VLC system is small compared with other small cell network and users from adjacent cells impact on transmission link which arises co-channel interference. To solve these problems, a novel joint scheduling and rate allocation (JSRA) algorithm associated with throughput maximization and channel-state has been proposed in VLC scenario. The objective of JSRA model is, each channel can determine the feasibility of its rate which always intends to increase, by exploiting the constraint value of signal-to-interference-plus-noise ratio (SINR) of that scheduled channel. The results show that the performance of joint control approach increases the total system average throughput and the spectral efficiency.

Mitigation of interference using OFDM in visible light communication

Visible light communication (VLC) enables high speed wireless communication along with fulfilling the illumination requirement in the indoor environment. In this paper, we investigate the performance of a VLC system under multiple reflection condition. We minimize the effect of intersymbol interference (ISI) by using orthogonal frequency division multiplexing (OFDM). Particularly the use of guard interval (GI) in OFDM is utilized to mitigate intersymbol interference. We performed simulation using MATLAB to demonstrate the performance of our proposed VLC system. Simulation results show that the use of guard interval significantly reduces the ISI and hence improves bit error rate (BER) performance.

The internet of LED: A LED-ID based interoperability and interconnectivity perspective.

The internet of LED (IoL) is a novel paradigm, proposed in this paper, where the main enabling technologies are the integration of LED identification (LED-ID) and internet technology. LED-ID is one of the promising technologies of visible light communication for identification, data transmission and illumination simultaneously. Due to the heterogeneity of two different domains, the requirements of interconnectivity between LED-ID system and the internet technologies are addressed here with varied performance expectations. The internet over VLC system is the new addition in internet of things arena for providing different kinds of smart services which are briefly introduced in this paper. We have also proposed modified MAC architecture, orthogonal latin square (OLS) based backoff scheduling, and scalable GTS allocation.

Balanced energy and coverage guaranteed protocol for wireless sensor networks

Wireless platforms are becoming less expensive and more powerful, enabling the promise of widespread use, everything from health monitoring to military sensing. In large scale applications like military surveillance, sensing coverage is essential for target detection and optimization of power consumption is important for lifetime extension of the network. Coverage and long lifetime network are two important factors and challenges for sensor networks. In this paper, we propose a new scheme, named as BECG, which remains the best coverage of the sensing area and energy balanced scheduling for all sensors. It allows nodes to determine when they can switch to sleep mode during operation. The energy efficiency of the proposed scheme is shown by intelligent decisions making. Each node in the network takes decision to turn on or turn off in a distributed manner that results a set of small number of active nodes throughout the lifetime of the network and covers sensing area of interest for target detection. It reduces redundancy, power consumption and increase the lifetime of a network. At first we applied our algorithm for a random topology and then we evaluate the performance of the network by simulation.