Effect Of Propagation Delay Research Articles

Excitable dynamics in the presence of time delay

The spiking properties of a subcritical Hopf oscillator with a time delayed nonlinear feedback is investigated. Finite time delay is found to significantly affect both the statistics and the fine structure of the spiking behavior. These dynamical changes are explained in terms of the fundamental modifications occurring in the bifurcation scenario of the system. Our mathematical model can find useful applications in understanding the dynamical behavior of various real life excitable systems where propagation delay effects are ubiquitous.

Effect of propagation delay and RTS packet recognition time on MACA

AbstractThe authors analytically derive the throughput performance of the media access control (MAC) protocol MACA, which has become the prototype of options used in IEEE802.11 for reducing the effects of hidden terminals. This derivation indicates that the MACA throughput performance basically is affected by the propagation delay and RTS recognition time. Also, by comparing MACA with CSMA, which is a typical contention mode MAC protocol, the authors show that (1) if the RTS recognition time is sufficiently small, MACA has better performance than CSMA even in a network in which no hidden terminal exists, and (2) when relatively large data packets are transmitted and received, MACA functions effectively. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 88(1): 21–31, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20147

Performance of Multimedia Rate Control Protocols in InterPlaNetary Internet

The communication requirements of the next generation space missions necessitate to address the challenges for the realization of the InterPlaNetary (IPN) Internet. The multimedia flows carrying audio and visual information, including planet images and scientific observations, will constitute significant portion of the traffic in the IPN Internet. In this letter, the effects of propagation delay, link errors, and blackouts on the throughput performance of multimedia rate control protocols are investigated in IPN Internet. The analytical observations and experimental results show that the existing multimedia rate control protocols are far from satisfying the IPN Internet communication requirements.

An efficient media access protocol for packet-switched wavelength-division multiplexed photonic networks

A reservation-based protocol based on a Pipelining Cyclic Scheduling Algorithm (PCSA) is proposed for packet-switched single-hop photonic networks. This protocol contains a mechanism to avoid contention at the receivers. Packets arrive in order and the transmission delay and its variations are optimized. The effects of propagation delay and processing time are almost compensated for by a pipelining technique. Analytical models and analysis are developed. The transmission delay is calculated as a function of the offered load, the number of nodes, propagation delay and processing time. Finally, the results of the analysis and simulations are compared.

Performance analysis of multicast flow control algorithms over combined wired/wireless networks

A multicast flow control framework for data traffic traversing both a wired and wireless network is proposed. Markov-modulated fluid (MMF) models are used for the receivers to capture the dynamics of the wireless links. Our study shows that the phase differences of the instantaneous throughput capabilities of the receivers are a distinctive feature of multicast connections. The objectives of the multicast flow control algorithms are to cope with the receiver phase differences (RPDs) cost effectively in addition to the general goals such as maximizing throughput and minimizing delay. Three ad hoc algorithms have been studied: listen to slowest request (LSQ), source estimation (SE), and open-loop control. A fluid-flow analysis technique is applied to study the effect of receiver phase differences assuming zero propagation delay. The effect of propagation delay in multicast connections is then discussed. Simulation results are presented to verify the analysis for the zero-delay case and to compare the performance of the algorithms under nonnegligible delays. It turns out that the zero-delay case reveals the characteristics of the multicast algorithms and provides good performance bounds for the cases with nonnegligible propagation delays.

Efficient window flow control for high speed data networks with small buffers

As the transmission speeds of emerging data networks scale up, the effects of propagation delays, which do not scale, become quite consequential for the design of sliding windows which are needed for congestion control. It was previously shown that optimal window lengths grow linearly with transmission speed λ, thus making the cost of memory for buffers a major factor. However, it was also shown that the moments of the number of packets in the buffers are onlyO(\(\sqrt {{\mathbf{ }}\lambda }\)), the remaining packets are in the course of being propagated. This fact underlies the proposal made here which requires smallO(\(\sqrt {{\mathbf{ }}\lambda {\mathbf{ }}ln{\mathbf{ }}\lambda }\)) buffers and yet guarantees that the ratio of the realized throughput to the ideal throughput approaches unity with increasing λ. That is, buffers when properly sized overflow so rarely that even with a rudimentary (conversely, easily implemented) protocol like go-back-n, the loss in throughput due to retransmissions is negligible. This result is arrived at by obtaining an explicit characterization for large λ of thetail of the distribution of buffer occupancy in the closed network with window sized buffers; in the case of a single-hop virtual circuit the characterization is by a Gaussian conditioned to be nonnegative. Numerical and simulation results are presented to corroborate the performance predictions of the theory for the case of 45 Mbits/sec transmission speed.

Throughput of inhibit sense multiple access with propagation delays

A large number of terminals transmitting data packets over a common radio channel to a central base station is studied. In inhibit sense multiple access (ISMA), the base station broadcasts a busy signal when an incoming packet is being received, to inhibit other terminals from colliding transmissions. This busy signal arrives at each terminal with a propagation delay, proportional to the distance between the base station and the terminal. This leads to unfairness in the probability of successfully transmitting a data packet, since nearby terminals have more up-to-date information on the actual channel status than remote terminals. This unfairness is additional to the advantage that nearby terminals have because of the capture effect, which is also considered. The paper applies nonstationary Poisson processes to describe the random arrivals of data packets at the central receiver. It is shown that the probability of a successful attempt to transmit a packet decreases, approximately linearly with the distance between the transmitter and the central receiver. The total throughput is also assessed, and it is found that the assumption of a fixed propagation delay adopted in CSMA studies by others gives too optimistic results for ISMA. Moreover, the analysis suggests a subtle change of the fixed delay approximation that enhances its accuracy, without adding complexity. The effect of propagation delays in random access radio networks are of increasing importance, since newly developed systems are designed to transmit with increasingly high bit rates.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Survey of traffic control schemes and protocols in ATM networks

The authors survey a number of important research topics in ATM (asynchronous transfer mode) networks. The topics covered include mathematical modeling of various types of traffic sources, congestion-control and error-control schemes for ATM networks, and priority schemes to support multiple classes of traffic. Standard activity for ATM networks and future research problems in ATM are also presented. It is shown that the cell-arrival process for data sources can be modeled by a simple Poisson process. However, voice sources or video sources require more complex processes because of the correlation among cell arrivals. Due to the effects of high-speed channels, preventive control is more effective in ATM networks than reactive control. Due to the use of optical fibers in ATM networks, the channel error rate is very small. The effects of propagation delay and processing time become significant in such high-speed networks. These fundamental changes trigger the necessity to reexamine the error-control schemes used in existing networks. Due to the diversity of service and performance requirements, the notion of multiple traffic classes is required, and separate control mechanisms should be used according to the traffic classes. The priority scheme is shown to be an effective method to support multiple classes of traffic.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

MPM?An atmospheric millimeter-wave propagation model

The neutral atmosphere is characterized for the frequency range from 1 to 300 GHz as a nonturbulent propagation medium. Attenuation and propagation delay effects are predicted from meteorological data sets: pressure, temperature, humidity, suspended particle concentration, and rain rate. The physical data base of the propagation model consists of four terms: (a) resonance information for 30 water vapor and 48 oxygen absorption lines in the form of intensity coefficients and center frequency for each line; (b) a composite (oxygen, water vapor, and nitrogen) continuum spectrum; (c) a hydrosol attenuation term for haze, fog, ,and cloud conditions; and (d) a rain attenuation model. Oxygen lines extend into the mesosphere, where they behave in a complicated manner due to the Zeeman effect. The geomagnetic field strength H is required as an additional input parameter. Each 02 line splits proportionally with H into numerous, sub-lines, which are juxtaposed to form a Zeeman pattern spread over a megahertz scale. Patterns for three main polarization cases are calculated. Detailed examples for model atmospheres provide basic millimeter wave propagation information over the height range 0 to 100 km of the neutral atmosphere.

Effect of propagation delays on ALOHA systems

Abstract Effect of propagation delays on the steady state behavior in ALOHA systems is investigated. The basic model of ALOHA systems with propagation delays is introduced and analyzed in line with the catastrophe theory. The bifurcation set, which shows the necessary and sufficient condition that the system is either monostable or bistable, is given explicitly in terms of a few system and user parameters including propagation delays. The global behavior of the system is determined by the cusp catastrophe. Analysis of bifurcation sets shows that propagation delays stabilize the system.