Problem Of Propagation Delays Research Articles

Modified Mackenzie Equation and CVOA Algorithm Reduces Delay in UASN

In Underwater Acoustic Sensor Network (UASN), routing and propagation delay is affected in each node by various water column environmental factors such as temperature, salinity, depth, gases, divergent and rotational wind. High sound velocity increases the transmission rate of the packets and the high dissolved gases in the water increases the sound velocity. High dissolved gases and sound velocity environment in the water column provides high transmission rates among UASN nodes. In this paper, the Modified Mackenzie Sound equation calculates the sound velocity in each node for energy-efficient routing. Golden Ratio Optimization Method (GROM) and Gaussian Process Regression (GPR) predicts propagation delay of each node in UASN using temperature, salinity, depth, dissolved gases dataset. Dissolved gases, rotational and divergent winds, and stress plays a major problem in UASN, which increases propagation delay and energy consumption. Predicted values from GPR and GROM leads to node selection and Corona Virus Optimization Algorithm (CVOA) routing is performed on the selected nodes. The proposed GPR-CVOA and GROM-CVOA algorithm solves the problem of propagation delay and consumes less energy in nodes, based on appropriate tolerant delays in transmitting packets among nodes during high rotational and divergent winds. From simulation results, CVOA Algorithm performs better than traditional DF and LION algorithms.

Security and performance evaluation of master node protocol based reputation blockchain in the bitcoin network

Bitcoin is a digital currency based on a peer-to-peer network to propagate and verify transactions. Bitcoin is gaining wider adoption than any previous crypto-currency. However, the mechanism of peers randomly choosing logical neighbours without any knowledge about the underlying physical topology can cause a delay overhead in information propagation which makes the system vulnerable to double spend attacks. Aiming at alleviating the propagation delay problem, this paper introduces a proximity-aware extension to the current Bitcoin protocol, named Master Node Based Clustering (MNBC). The ultimate purpose of the proposed protocol, which is based on how clusters are formulated and how nodes can define their membership, is to improve the information propagation delay in the Bitcoin network. In the MNBC protocol, physical internet connectivity increases as well as the number of hops between nodes decreases through assigning nodes to be responsible for maintaining clusters based on physical Internet proximity. Furthermore, a reputation-based blockchain protocol is integrated with MNBC protocol in order to securely assign a master node for every cluster. We validate our proposed methods through a set of simulation experiments and the findings show how the proposed methods run and their impact in optimising the transaction propagation delay.

Relay Selection for Capacity Increase in Underwater Acoustic Sensor Network.

In long distance sensor nodes, propagation delay is the most crucial factor for the successful transmission of data packets in underwater acoustic sensors networks (UWAs). Therefore, to cope with the problem of propagation delay, we propose examining and selecting the best relay node (EBRN) technique based on checking the eligibility and compatibility of RN and selecting the best RN for UWAs. In the EBRN technique, the source node (S) creates a list of the best RNs, based on the minimum propagation delay to the midpoint of a direct link between S and the destination node (D). After that, the S attaches the list of selected RNs and transmit to the D along with data packets. Finally, from the list of selected RNs, the process of retransmission is performed. To avoid collision among control packets, we use a backoff timer that is calculated from the received signal strength indicator (RSSI), propagation delay and transmission time, whereas the collision among data packets is avoided by involving single RN in a particular time. The performance of the proposed EBRN technique is analyzed and evaluated based on throughput, packet loss rate (LR), packet delivery ratio (PDR), energy efficiency, and latency. The simulation results validate the effectiveness of the proposed EBRN technique. Compared with the existing schemes such as underwater cooperative medium access control (UCMAC) and shortest path first (SPF), the proposed EBRN technique performs remarkably well by increasing the throughput, PDR, and energy efficiency while decreasing the latency and LR in UWAs.

Development of adamantane-containing polybenzoxazines for dielectric interlayers applications

Low dielectric constant materials are appropriate solutions to address the propagation delay problem in ultra-large scale integrated circuits. Herein, adamantane is applied to improve the dielectric properties of polybenzoxazines. Monomers synthesized from bisphenol-A, 4,4'-diphenol and 1-amino adamantane are developed for understanding the properties of polybenzoxazines at molecular level. We found that incorporating adamantane results in much lower dielectric constant and loss factor without sacrificing the glass transition temperature and thermal stability, which are potential alternates as new dielectric interlayer materials.

VERIFICATION OF CARRY LOOK AHEAD ADDER USING CONSTRAINED RANDOMIZED LAYERED TEST BENCH

In processors and in digital circuit designs, adder is an important component. As a result, adder is the main area of research in VLSI system design for improving the performance of a digital system. The performance depends on power consumption and delay. Adders are not only used for arithmetic operations, but also for calculating addresses and indices. In digital design we have half adder and full adder, by using these adders we can implement ripple carry adder (RCA). RCA is used to perform any number of additions. In this RCA is serial adder and it has propagation delay problem. With increase in hard & fast circuits, delay also increases simultaneously. That’s the reason these Carry look ahead adders (CLA) are used. The carry look ahead adder speeds up the addition by reducing the amount of time required to determine carry bits. It uses two blocks, carry generator (Gi) and carry propagator (Pi) which finds the carry bit in advance for each bit position from the nearest LSB, if the carry is 1 then that position is going to propagate a carry to next adder.

Receiver-Initiated Handshaking MAC Based on Traffic Estimation for Underwater Sensor Networks ‡.

In underwater sensor networks (UWSNs), the unique characteristics of acoustic channels have posed great challenges for the design of medium access control (MAC) protocols. The long propagation delay problem has been widely explored in recent literature. However, the long preamble problem with acoustic modems revealed in real experiments brings new challenges to underwater MAC design. The overhead of control messages in handshaking-based protocols becomes significant due to the long preamble in underwater acoustic modems. To address this problem, we advocate the receiver-initiated handshaking method with parallel reservation to improve the handshaking efficiency. Despite some existing works along this direction, the data polling problem is still an open issue. Without knowing the status of senders, the receiver faces two challenges for efficient data polling: when to poll data from the sender and how much data to request. In this paper, we propose a traffic estimation-based receiver-initiated MAC (TERI-MAC) to solve this problem with an adaptive approach. Data polling in TERI-MAC depends on an online approximation of traffic distribution. It estimates the energy efficiency and network latency and starts the data request only when the preferred performance can be achieved. TERI-MAC can achieve a stable energy efficiency with arbitrary network traffic patterns. For traffic estimation, we employ a resampling technique to keep a small computation and memory overhead. The performance of TERI-MAC in terms of energy efficiency, channel utilization, and communication latency is verified in simulations. Our results show that, compared with existing receiver-initiated-based underwater MAC protocols, TERI-MAC can achieve higher energy efficiency at the price of a delay penalty. This confirms the strength of TERI-MAC for delay-tolerant applications.

A Review and Classification of Energy Efficient MAC Protocols for Underwater Wireless Sensor Network

Underwater wireless sensor network is an emerging wireless networking technology (UWSN). UWSN has various applications for example it can be used for monitoring seismic activities, underwater animal, pipeline etc. UWSN face challenges in their MAC later operations. Different energy efficient MAC protocols have been proposed for underwater wireless sensor networks (UWSN) to overcome the problem of propagation delays which is inherent in underwater acoustic networks. In this paper, we study the energy efficient MAC protocols including EE-MACU, R-MAC and T-Lohi. We classify UWSN MAC protocols into two broad categories contention free and contention based and we further categorize contention based protocol. We analyze and compare key UWSN MAC protocols based on certain parameters and suggest their suitability in various scenarios.

A high performance long-reach passive optical network with a novel excess bandwidth distribution scheme

Long-reach passive optical networks (LR-PONs) have been considered to be promising solutions for future access networks. In this paper, we propose a distributed medium access control (MAC) scheme over an advantageous LR-PON network architecture that reroutes the control information from and back to all ONUs through an (N+1)×(N+1) star coupler (SC) deployed near the ONUs, thereby overwhelming the extremely long propagation delay problem in LR-PONs. In the network, the control slot is designed to contain all bandwidth requirements of all ONUs and is in-band time-division-multiplexed with a number of data slots within a cycle. In the proposed MAC scheme, a novel profit-weight-based dynamic bandwidth allocation (P-DBA) scheme is presented. The algorithm is designed to efficiently and fairly distribute the amount of excess bandwidth based on a profit value derived from the excess bandwidth usage of each ONU, which resolves the problems of previously reported DBA schemes that are either unfair or inefficient. The simulation results show that the proposed decentralized algorithms exhibit a nearly three-order-of-magnitude improvement in delay performance compared to the centralized algorithms over LR-PONs. Moreover, the newly proposed P-DBA scheme guarantees low delay performance and fairness even when under attack by the malevolent ONU irrespective of traffic loads and burstiness.

An improved Elmore delay model for VLSI interconnects

Elmore delay metric is a widely used model to compute signal delays for both analog and digital circuit interconnects. Although it provides a limited accuracy and its applicability is limited to the step function type input signals, this model is extremely popular with simple analytical functions that can be easily incorporated into design and automation software. In this work, a new boundary limiting the Elmore delay is introduced. A general form of traditional Elmore delay is defined and solved by utilizing this boundary. The new solution of the propagation delay problem called the improved Elmore delay model is derived according to the compound interest problem of Jacob Bernoulli. The improved Elmore delay formulation and the traditional Elmore delay model are compared according to SPICE simulation environment performances which verifies the superior accuracy of the novel delay formulation. The test results proved that better accuracy is achieved with the improved Elmore delay model than the traditional Elmore delay model with the same computation speed.

Proactive cooperative scheduling and buffer management for multimedia networks

Is it possible, and to what extent feasible, for link schedulers and buffer managers in multimedia networks with propagation delays to relieve effectively congestion by means of feedback signaling? We show that a proactive cooperative control algorithm for distributed resource scheduling and buffer management obviates the problem of propagation delays. The algorithm is based on traffic predictions of correlated input traffic streams into network nodes. Nodes projecting to be under stress signal their neighboring upstream nodes for the latter to readjust their flow rates, whileguaranteeing quality of service as negotiated at call setup. Detailed implementations of the adaptive, feedback control mechanisms of distributed asynchronous algorithms that project future overload conditions are presented. The design allows the underlying single-node link scheduling and buffer management algorithm to be run in either a cooperative or a noncooperative mode of operation.

Twelve Advantages of Stationary Satellite Systems for Point-to-Point Communication

With the exception of those systems which are intended to satisfy special military requirements, passive satellite communication systems will not be economically competitive with high-capacity, active satellite systems because of greater terminal costs. There are twelve reasons why stationary orbit systems should become the backbone of future global communications, and these are discussed in detail. Seven of these are based on economic and system advantages, while the remaining five arise from interference coordination advantages in frequency sharing among satellite systems and with surface services. Stationary satellites present space technology and propagation delay problems, but these are rapidly being overcome. It is therefore recommended that more planning and regulatory emphasis be focused on stationary satellite communication systems, since nonstationary, nonmilitary systems will only be interim or supplementary systems.