In today's era of modernization, the concept of smart vehicles, smart cities and automated vehicles is trending day by day. VANET (Vehicular Adhoc Network) has also been emerging as a potential applicant to enable these smart applications. Though VANET is very much similar to MANET (Mobile Adhoc Network) but VANET has more severe challenges as compared to MANET due to hostile channel conditions and high degree of mobility. So lot of work related to MAC and Network Layer need attention from the network designers. In this paper MAC Layer has been optimised in terms of Queue Size by using QoS Parameters namely Packet Collision Rate, Packet Drop Rate, Throughput Rate and Broadcast Rate. In doing so, simulative investigations have been done to find out optimum queue size. For this purpose various routing protocols namely DSDV, AODV, ADV and GOD have been considered and optimum queue length for each of these have been obtained. Further the most efficient routing protocol has also been identified. Moreover this paper also compares the performance of most efficient Routing Protocols selected in terms of QoS parameters for different MAC Interfaces.

In this paper, 3:1 and 10:1 unequal Wilkinson power dividers are designed and investigated. Unequal power dividers are an integral part of the feeding network for antenna array where their performance affects a group of elements rather than an individual element. Thus, there is a need for an accurate design for such dividers. A coupled-line section with two grounding via has been used to attain the high characteristic impedance line. This is done in order to outplay the microstrip fabrication constraints of printing very thin/fine conductor lines. Further to reduce the size of the structure, meandering of the transmission line has been done which procreates three designs, namely: 00 Serpentine Flexure, 1800 Serpentine Flexure and Compact Meandered Flexure. Verification of the design methodology has been done by creating a 10:1 Unequal WPD. The structures are implemented on a high-resistive silicon substrate (HRS) for a centre frequency of 1.575 GHz. Further, their EM analysis is done in terms of S-parameters such as return loss and insertion loss using commercially available FEM solver. Satisfactory RF performance, with return loss better than -10 dB and required power split for all the structures, has been achieved. 

A statistical characterization of body surface to external communication of Body Area Network is investigated for movement of human body in different directions i.e. 00, 900, 1800 and 2700, with respect to the transmitting antenna. The NICT’s statistical model is used to carry out measurement in ultra-wideband (UWB) range. The important parameters that capture the variability of the delay profile over the channel e.g. mean delay spread and RMS delay spread of power delay profile (PDP) is presented. The probability density (PDF) and cumulative distribution (CDF) function of the output signal to noise ratio (SNR) have been computed. The performance of Selective Rake (S-Rake) and Partial rake (P-Rake) receiver structure that employs maximal-ratio combining (MRC) is investigated for varying number of fingers taps.

Vehicular Ad Hoc network is a versatile mobile wireless Ad-Hoc network targeted to support traffic monitoring, vehicular safety and many more applications. For the robust and reliable services in the VANET there is need to investigate the performance under frequent handovers in Mobile IP to prevent packet loss. Mobile IP is an interface that helps to track the mobile nodes and deliver messages even if vehicles are out of the coverage area of home node. In order to find the achievable performance bounds in terms of throughput, packet drop, collision rate and packet broadcast rate, extensive simulations have been done. A realistic city scenario has been proposed here by using the Rayleigh channel simulator, mobile IP enabled IEEE 802.11p OBUs and RSUs. The transmission powers of RSUs and threshold power levels have been varied to obtain the optimum performance through realistic conditions. Simulations are performed using NCTUns6.0 (National Chiao Tung University Network Simulator) in mobile IP interface.

Zigbee standard has been designed for low data rate, low cost and limited power applications for short-range wireless communication. The successful implementation of Zigbee based network depends on the suitable selection of physical (PHY) layer and medium access control (MAC) layer parameters. In this work the PHY layer parameters have been optimized for star, tree and mesh topologies. The performance investigations have been carried out for different frequency band and data rate and different bandwidth (BW) in each of standard topologies. Through extensive simulations, QoS parameters like throughput, network load and delay have been evaluated to achieve optimal performance of physical layer.

LTE Standard has been an inseparable part of 3GPP that was started with an objective to upgrade 3G based Mobile Systems to 4G.This standard has been developed to enhance the data rate, reliability and seamless connectivity to the users. There is a need to evaluate the achievable performance through this standard in terms of MAC parameters. Moreover, in order to optimize the resources like Power and Bandwidth, Extensive Simulations have been done here considering the Medium Access techniques like Channel estimation, Retransmission techniques and Scheduling techniques. Two Scenarios have been designed by considering diverse Conditions of Physical Layer Resources. Optimal Performance bounds have been obtained in terms of BLER and throughput for the proposed Scenarios.

VANET deployment in real world has become a living reality by the successful allotment of 5.9GHz to Dedicated Short Range Communication (DSRC) by WLAN technologies. Dynamically changing topology and establishment of reliable path between nodes with minimum bandwidth consumption and lesser routing overheads are the main aims of ad- hoc network routing. To exploit effective and reliable communication among vehicles routing is a major factor which needs to be investigated. This paper intends to evaluate the performance of AODV and GOD routing protocols in city scenario under different application types and different fading environment using IEEE 802.11b MAC standard. Simulations are performed using NCTUns 6.0 (National Chung Tung University Network Simulator) and found that AODV performance is better in fading channel even if we increase rician factor. Also the performance of GOD is better in ideal fading (AWGN) channel, although the performance of routing protocols vary from one scenario to other and application traffic.

Convergecast communication is used in many sensor applications .The flow of data in convergecast routing is from many to one i.e. many sensory nodes sense the data and send through parent child relation to the root node or sink node. Convergecast routing is always followed by broadcasting. In broadcast communication is from one to many and in convergecast it is from many to one. As sensor nodes have limited battery capacity main focus is to save energy. As compare to wired network wireless network is prone to attacks and it is less reliable than the wired network. This paper investigates the affect of header length of network layer on the BER, SNIR, backoff duration, SNR and latency of convergecast routing with the help of omnet++ simulator.

Mobile wireless system incorporates dual sphere in terms of mobility as well as computing. Such systems have revamped momentously resulting in expedient wireless devices. Current wireless communication requires enormous data rates, streaming audio/video, asymmetric access/multiple access, fully-integrated, low cost, reliable seamless systems with the capability of providing voice, high speed data, and video with minimum latency and long battery life to enhance error free communication. However, there are many obstacles and bottlenecks to achieving this in practice. These bottlenecks include limited spectrum, limited energy, multipath fading and propagation loss, cost, standardization processes. This paper focuses on coding and modulation techniques for wireless communications so as to reduce/overcome many of these obstacles. To put the discussion in perspective, a short background on the coding and modulation approaches of wireless communication systems is provided. The turbo coding is mainly chosen to facilitate the wireless communication. The paper enlightens the impetus behind using turbo codes for high data rate mobile wireless systems. Paper explains how better out-turns can be yielded when approaches like cyclic redundancy check and scrambling are embedded with coding. The BER performance and SNR ratio are observed for illustrating variance between convolution and turbo coding for different rates and modulations. Simulation results are plotted using Matlab software.