Hafiz M. Asif

Power consumption optimization and delay minimization in MANET

The performance of wireless networks under video traffic is subjected to two-fold constraints. Both power minimization and other QoS requirements such delay, delay jitter etc. need to be taken care of properly. Mobile Ad Hoc Networks (MANETs) are more sensitive to these issues where each mobile device acts like a router and thus, routing delay adds significantly to overall end-to-end delay. In this paper, we analyze the performance of the Warning Energy Aware Clusterhead/Virtual Base Station-On demand (WEAC/VBS-O) protocol, proposed earlier by one of the authors [1], in terms of average delay, multihop communication and power minimization aspects subject to video traffic. The H.263 standard is utilized to model video traffic in our simulation design. Primarily, we establish a single hop communication between nodes. It is then extended to multihop communication. However, we found that the protocol can support up to two hops for an acceptable network performance provided there is a significant number of nodes in the network. Hence, we modelled the same network with H.264 and showed that the hop count increases from two to five with better performance. We also took power minimization issue into consideration and minimize power consumption by making use of HCB model by applying it within the neighborhood of the node. Simulation results showed that this strategy does minimize power consumption and it did not degrade multihop communication improvement. With the idea that maximum power saving is achieved if the relaying node lies in the middle of source and destination node for HCB model [2]. Furthermore, we saw the effect of sudden demise of cluster heads in the Warning Energy Aware Cluster head (WEAC) protocol based on our previous work [3]. Subsequently, we compared the results when some clusterheads (CHs) have sudden death to the results when there is no switching of CH based on selected performance metrics. We found that there is little power loss if the relaying node is not in the middle of source and destination node. However, performance is seriously degraded on the introduction of sudden demise of CH during simulation as far as average end-to-end delay is concerned.

OCDMA and OSTBC based VLC transceiver design using NI cDAQ

Visible light communication (VLC) is a novel technology especially for short-range data communication. IEEE has standardized VLC for 5G systems as a means to short-range wireless communication. In this paper, a complete state-of-the-art VLC software-defined radio is designed using NI cDAQ components tools developed in LabVIEW/MATLAB. The main objectives in designing a VLC transceiver are the suitable envelope for driving LEDs (transmitters) and a high data rate. The current work makes use of optical code division multiple access mainly to achieve the said objectives. It is shown through comparison with existing system that the proposed system is computationally less expensive and provides improved data rate. Finally, simulation programs are also developed and the proposed system is compared with the existing system in terms of bit error rate.

ESIM-OFDM-based transceiver design of a visible light communication system

Summary Visible light communication (VLC) system has been becoming a potential technology for short-range data communication over wireless optical channel. In this paper, a real-time state-of-the-art VLC system prototype is implemented mainly based on enhanced subcarrier index modulation orthogonal frequency division multiplexing (ESIM-OFDM) modulation scheme. The prototype has been designed using NI cDAQ hardware equipment programmed in matlab/labview. In other words, the developed VLC transceiver labview model is loaded into cDAQ to perform real-time transmission of text data. The design mainly comprises VLC transmitter, VLC receiver, interfacing NI cDAQ with labview, and implementation of ESIM-OFDM. It should be noted that the direct output of ESIM-OFDM is not suitable to drive VLC transmitter circuit; therefore, the key contribution lies in making use of sigma–delta modulator to modify ESIM-OFDM output to produce constant current signal which in turn could drive VLC transmitter. The second main contribution of the work targets the luminous properties of the designed transmitter that have experimentally been characterized using a LUX meter. Finally, the last contribution of the work is the simulation carried out to analyze the performance of the proposed system with other existing VLC modulation schemes. Copyright

Multiple-input multiple-output ultra-wide band channel modelling method based on ray tracing

In this work, the authors have developed a deterministic Ultra Wide Band (UWB) channel model for indoor environment using both ray-tracing technique and the art of computer game technology in 3D Game Studio (game development tool). In the developed model, the characteristics of indoor environment such as texture, transparency etc. can be taken into consideration while indoor parameters such as room size, objects position etc. can be interactively changed. Each time, indoor environment is changed, the program is compiled and hence, the underlying ray-tracing captures the updated indoor environment. It is the key novelty of the authors’ developed model and it has been so incorporated to make the authors’ model independent of any fixed (pre-defined) indoor environment. The developed model is compared against the standard statistical UWB channel model based on certain parameters such as delay spread etc. to address its validity and accuracy. The model is then enhanced to use multiple antennas on both sides of the system and capture the channel response accordingly. Finally, the developed model has been tested over a range of frequencies to see frequency effect on the channel impulse response. The simulation results have been presented and discussed in the simulation section.

Gaussian integers and interleaved rank codes for space–time block codes

This paper presents the design of space–time block codes (STBCs) over maximum rank distance (MRD) codes, energy-efficient STBCs, STBCs using interleaved-MRD codes, the use of Gaussian integers for STBCs modulation, and Gabidulins decoding algorithm for decoding STBCs. The design fundamentals of STBCs using MRD codes are firstly put forward for different number of transmit antennas. Extension finite fields (Galois fields) are used to design these linear block codes. Afterward, a comparative study of MRD-based STBCs with corresponding orthogonal and quasi-orthogonal codes is also included in the paper. The simulation results show that rank codes, for any number of transmit antennas, exhibit diversity gain at full rate contrary to orthogonal codes, which give diversity gain at full rate only for two transmit antennas case. Secondly, an energy-efficient MRD-STBC is proposed, which outperforms orthogonal STBC at least for 2 × 1 antenna system. Thirdly, interleaved-MRD codes are used to construct higher-order transmit antenna systems. Using interleaved-MRD codes further reduces the complexity (compared with normal MRD codes) of the decoding algorithm. Fourthly, the use of Gaussian integers is utilized in mapping MRD-based STBCs to complex constellations. Furthermore, it is described how an efficient and computationally less complex Gabidulins decoding algorithm can be exploited for decoding complex MRD-STBCs. The decoding results have been compared against hard-decision maximum likelihood decoding. Under this decoding scheme, MRD-STBCs have been shown to be potential candidate for higher transmit antenna systems as the decoding complexity of Gabidulins algorithm is far less, and its performance for decoding MRD-STBCs is somewhat reasonable.

Customizable Transceiver Design of a Visible Light Communication System

Visible Light Communication (VLC) is an optical wireless communication technology that can be used for data communication over optical wireless link. In this paper, a complete state-of-the-art Visible Light Communication (VLC) transceiver prototype has been physically designed. The developed VLC transceiver prototype can serve the purpose of both illumination and data communication simultaneously. The novelty of the design lies in the fact that it uses STM32F4Discovery board which is customizable over the Universal Synchronous/Asynchronous Receiver/Transmitter (USART) TX and RX protocols. The work covers complete hardware design of the transceiver including LED driving circuit, and full configuration of the STM32F4Discovery board. Furthermore, the proposed VLC design can also be used for audio communication.

Frequency and MIMO impact on ray tracing based UWB channel modelling

It is a challenging task to handle dense multipath environment in a wireless communication channel. Various techniques were suggested to handle this issue such as power control, antenna, time and frequency diversity etc. However, antenna diversity is considered to be the most practical way to handle multipath fading. In this paper, a deterministic UWB channel model was developed based on ray-tracing technique using the art of 3D computer game technology. Reflection, refraction and scattering phenomena were successfully implemented. The model was then enhanced to use multiple antennas on both sides of the system. Simulation results show great improvement in channel impulse response (CIR) in case of multiple antennas. Moreover, the frequency effect on channel impulse response was analyzed for 500 MHz–4 GHz range. Our results indicate that the change in frequency does not affect the channel behaviour a lot but changes the pattern of received rays.

Design of NS3 VLC module and performance analysis of ad hoc network under VLC and Wi-Fi layers

Int J Commun Syst. 2018;e3764. https://doi.org/10.1002/dac.3764 Summary Visible light communication (VLC) is the branch of optical wireless communications that uses light‐emitting diodes for the dual purpose of illumination and very‐high‐speed data communication. The main motivation behind the current work is finding alternatives to the saturated radio frequency spectrum, radio frequency security issue, and vulnerability to interferences. The current work is aimed at developing a module for the physical layer of a VLC‐based ad hoc network in network simulation 3. The VLC physical layer module is developed by using the optical signal modules available in the network simulator. The work also includes modelling of VLC‐based transmitter, wireless optical channel, and the optical receiver. Furthermore, the implementation and evaluation of the VLC‐based physical layer is carried out over a typical ad hoc network under different performance metrics. The designed ad hoc network is also tested under Wi‐Fi module followed by its comparison with corresponding ad hoc network under VLC module. The comparison is based on bit error rate curves, system throughput, and gain in received signal‐to‐noise ratio mainly. Finally, the suitability of different modulation schemes is also investigated in the current work for both Wi‐Fi– and VLC‐based ad hoc networks.

Autonomous data driven surveillance and rectification system using in-vehicle sensors for intelligent transportation systems (ITS)

Abstract Road safety through vehicular control is the prime interest of research in Vehicular Ad hoc Networks (VANETs). Diagnostic analysis of In-vehicle sensors is one of the core concerns for vehicular safety. There is a number of safety applications promising the features needed in vehicular safety. Therefore, this paper designed, developed, and implemented a solution for diagnostic analysis of In-vehicle sensors with autonomous recovery procedure. An artificial intelligence-based technique is used for monitoring, reporting and autonomous recovering of vehicle sensors. The algorithm used for diagnostic analysis of sensors not only determines the operational state of the sensors but also executes procedure for sensors autonomous recovery. A graphical display depicts the operational state of sensors for driver’s information. Hexadecimal message format is implemented for transmission and reception of sensors data to the central administration unit using Internet Protocol (IP). The simulation results confirm the effectiveness of proposed solution in term of recovery time of faulty sensor.

Semantic Based Cluster Content Discovery in Description First Clustering Algorithm

In the field of data analytics grouping of like documents in textual data is a serious problem. A lot of work has been done in this field and many algorithms have purposed. One of them is a category of algorithms which firstly group the documents on the basis of similarity and then assign the meaningful labels to those groups. Description first clustering algorithm belong to the category in which the meaningful description is deduced first and then relevant documents are assigned to that description. LINGO (Label Induction Grouping Algorithm) is the algorithm of description first clustering category which is used for the automatic grouping of documents obtained from search results. It uses LSI (Latent Semantic Indexing); an IR (Information Retrieval) technique for induction of meaningful labels for clusters and VSM (Vector Space Model) for cluster content discovery. In this paper we present the LINGO while it is using LSI during cluster label induction and cluster content discovery phase. Finally, we compare results obtained from the said algorithm while it uses VSM and Latent semantic analysis during cluster content discovery phase.