Sudarshan Tiwari

Performance analysis of high speed hybrid CMOS full adder circuits for low voltage VLSI design

This paper presents a comparative study of high-speed and low-voltage full adder circuits. Our approach is based on hybrid design full adder circuits combined in a single unit. A high performance adder cell using an XOR-XNOR (3T) design style is discussed. This paper also discusses a high-speed conventional full adder design combined with MOSCAP Majority function circuit in one unit to implement a hybrid full adder circuit. Moreover, it presents low-power Majority-function-based 1-bit full addersthat use MOS capacitors (MOSCAP) in its structure. This technique helps in reducing power consumption, propagation delay, and area of digital circuits while maintaining low complexity of logic design. Simulation results illustrate the superiority of the designed adder circuits over the conventional CMOS, TG, and hybrid adder circuits in terms of power, delay, power delay product (PDP), and energy delay product (EDP). Postlayout simulation results illustrate the superiority of the newly designed majority adder circuits against the reported conventional adder circuits. The design is implemented on UMC0.18 µm process models in Cadence Virtuoso Schematic Composer at 1.8 V single-ended supply voltage, and simulations are carried out on Spectre S.

Routing in IPv6 over Low-Power Wireless Personal Area Networks (6LoWPAN): A Survey

6LoWPANs (IPv6-based Low-Power Personal Area Networks) are formulated by devices that are compatible with the IEEE 802.15.4 standard. To moderate the effects of network mobility, the Internet Protocol (IP) does not calculate routes; it is left to a routing protocol, which maintains routing tables in the routers. 6LowPAN uses an adaptation layer between the network (IPv6) and data link layer (IEEE802.15.4 MAC) to fragment and reassemble IPv6 packets. The routing in 6LoWPAN is primarily divided on the basis of routing decision taken on adaptation or network layer. The objective of this paper is to present a state-of-the-art survey of existing routing protocols: LOAD, M-LOAD, DYMO-Low, Hi-Low, Extended Hi-Low, and S-AODV. These routing protocols have compared on the basis of different metric like energy consumption, memory uses, mobility, scalability, routing delay, an RERR message, a Hello message, and local repair. We have also presented the taxonomy of routing requirement; parameter for evaluating routing algorithm, and it was found that the routing protocol has its own advantages depending upon the application where it is used.

Optimal number of clusters in wireless sensor networks: a FCM approach

Wireless Sensor Networks (WSN) are resource constrained systems that needs efficient utilization of all resources. Clustering is well known technique for achieving high scalability and efficient resource allocation in WSN. One of the fundamental issues in cluster based networks is to determine the optimal number of clusters with the objective of minimizing the energy consumption. Considering its importance, a Fuzzy c-Means (FCM) clustering approach is proposed to determine the optimal number of clusters in WSN. The study considers the deployment of 100 nodes in 100×100 m2 area for random uniform distribution. The optimal number of clusters determined by FCM has been compared with those obtained by analytical method. Study on lifetime of wireless sensor networks is also presented with optimal clusters in network.

Performance of Routing Protocols for Beacon-Enabled IEEE 802.15.4 WSNs with Different Duty Cycle

Routing in WSNs (Wireless Sensor Networks) is very challenging due to some special characteristics that differentiate these networks from other wireless networks like cellular networks, mobile ad-hoc network etc. The difference is due to scalability, careful resource management etc. Sensor nodes are generally battery powered, are expected to be remotely deployed, and operated autonomously in unattended environments. ZigBee, a communication standard for LR-WPAN (Low Rate -Personal Area Networks), has low power consumption, complexity and cost. ZigBee uses the IEEE 802.15.4 standard as its communication protocol for Medium Access Control (MAC) layer and physical (PHY) layer. The IEEE 802.15.4 MAC standard achieves duty cycle operation by setting two system parameters, macBeaconOrder (BO) and macSuperframeOrder (SO), to achieve low power consumption for different value of duty cycle. In this Paper we have analyzed cross layer (MAC/PHY) approach for wireless sensor network scenario with different routing protocols: AODV, DYMO and XMESH under different percentage of duty cycle (DC). We have analyzed that what routing protocols with what percentage of Duty Cycle provide improvement over other routing protocols in WSNs. We have found value of attributes like energy consumption in transmit mode, energy consumption in received mode, energy consumption in idle mode, percentage of time in transmit mode (nodes comparison), percentage of time in received mode (nodes comparison) and total power consumption.

Performance Evaluation and Comparison of AODV and DSR Under Adversarial Environment

A mobile ad-hoc network (MANET) can be described as a mobile wireless network, consisting of a collection of communication nodes, which have to interact among themselves without the use of any centralized authority or fixed infrastructure. There are several technical challenges regarding deployment of a MANET, such as network scalability, communication stability, energy consumption, security and quality of services (QoS). Due to vulnerability of wireless links, nodes unstable infrastructure support and highly dynamic network states, MANET security becomes an essential design dimension. initially while designing MANET routing protocols security aspects were not considered, so routing protocols are vulnerable to various types of security attacks such as rushing attack, black hole attack, replay attack, jellyfish attack, wormhole attack, spoofing attack etc. In this paper we have discussed wormhole attack. In this paper, through simulation the effects of wormhole attack on Ad-hoc On Demand Distance Vector Routing (AODV) and Dynamic Source Routing (DSR) protocols have been analyzed and compared.

Cluster size optimisation with Tunable Elfes sensing model for single and multi-hop wireless sensor networks

ABSTRACT Minimising energy dissipation and maximising network coverage are the crucial aspects of wireless sensor networks (WSNs). The nodes of a sensor network are grouped into several non-overlapping subset to facilitate the network scalability and design of energy efficient system. Selecting optimal clusters provide significant gain in terms of network lifetime, system scalability, collision avoidance and end-to-end delay. Network coverage is another critical issue which depends on sensing model like deterministic sensing model and probabilistic sensing model. In this paper, we have proposed Tunable Elfes Sensing Model. This model is preferable in case of remote area application in WSNs, where nodes in the core of network closer to base station (BS) are modelled deterministically, whereas peripheral nodes are modelled probabilistically. Thus, we can model energy efficient system with large coverage area. In this paper, we have provided expression for optimal cluster using Tunable Elfes sensing model of BS for square and circular sensing field using single-hop communication between cluster heads (CHs) and BS with consideration of boundary effect. We have also analysed the optimal clusters for square and circular type of sensing field using Tunable sensing model for BS multi-hop communication between CHs and BS.

Ultra low voltage high speed 1-bit CMOS adder

In this paper, we present a novel design for realize full adder circuit. Our approach based on XOR-XNOR design full adder circuits in a single unit. Objective of this work is to investigate the power, delay and power delay product of low voltage full adder cells in different CMOS logic styles. Simulation results illustrate the superiority of the proposed adder circuit against the conventional CMOS, Hybrid, Bridge, Xor-Xnor adder circuits in terms of power, delay, PDP. The bridge design style enjoys a high degree of regularity, higher density than conventional CMOS design style as well as lower power consumption, by using some transistors, named bridge transistors. The performance of the full adder circuits is based on GPDK 90nm CMOS process models at all range of the supply voltage starting from 0.65V to 1.5V evaluated by the comparison of the simulation results obtained from Cadence. Simulation results reveal that the proposed circuit exhibits lower PDP and is faster when compared with available 1-bit full adder circuits. To summarize, some performance criteria are considered in the design and evaluation of adder cells, of which some are at ease of design, robustness, silicon area, delay, and power consumption. The design is implemented on GDPK 90 nm process models in Cadence Virtuoso Schematic Composer at 1.5V single ended supply voltage and simulations are carried out on Spectre S.

A Comparative Study of Reactive Routing Protocols for Industrial Wireless Sensor Networks

There have been a continuously growing demand for the efficient and infrastructure less Industrial Automation Systems (IAS), to fulfill the rapid changes in real world requirements. During the past decade, wireless sensor networks have been evolved as a powerful tool for the industrial process monitoring and distributed control. In the Industrial wireless control system, sensor nodes are deployed over an area, to monitor physical and or environmental conditions such as temperature, pressure, vibration, motion, sound, humidity etc. For the reliable control function, measured parameters should be delivered to the actuators in real time and reliable manner. Thus, considering the energy constraints of sensor nodes various reactive routing protocols are being used for the real time and reliable message delivery. The aim of this paper is to present a comparative study of existing reactive routing protocols in Industrial Wireless Sensor Networks (IWSNs).

Channel Estimation for Wavelet Based OFDM System

Orthogonal frequency division multiplexing (OFDM) is multi carrier modulation scheme. The channel estimation is a process of characterizing the effect of the transmission channel on the input signal. In this paper we compare the performance of Least Square (LS) and Linear Minimum Mean Square Error (LMMSE) channel estimation technique for Wavelet based OFDM system. The channel estimation based on block type pilot arrangement is performed by sending pilots at every sub-channel and using this estimation for a specific number of following symbols. In this paper we used wavelet transform instead of fast Fourier transform (FFT), which have more bandwidth efficiency, less prone to Doppler shift and also complexity of order O(N) as opposed to the FFTs O(Nlog2N).

DYMO as routing protocol for IEEE-802.15.4 enabled Wireless Sensor Networks

Wireless Sensor Networks (WSNs) is an emerging field of engineering with various applications. They have emerged as a new class of large scale networks of embedded systems with limited communication, computation and energy resources. Recently adopted IEEE 802.15.4 standards for Low-rate Wireless Personal Area Network (LR-WPAN) are most extensively used communication platform for WSNs. Conventional routing in IEEE 802.15.4 networks is based on Ad hoc On-demand Distance Vector (AODV) which facilitates the building of mesh networks for data dissemination. The Dynamic MANET On-demand (DYMO) routing protocol is a simple and fast routing protocol which is still in its internet draft and is in its 21st version. It is designed basically for multi-hop ad-hoc networks. In this paper we present a performance evaluation of DYMO routing protocols for IEEE-802.15.4 enabled WSNs. The performance of routing protocols is carried out base upon average energy consumption, average throughput, average end to end delay and average battery consumption and is compared with presently used AODV.