Browsing by Subject "Voice/data communication systems"

Now showing 1 - 5 of 5

Open Access
Markov modulated periodic arrival process offered to an ATM multiplexer
(IEEE, 1993-11-12) Akar, Nail; Arıkan, Erdal
When a superposition of on/off sources is offered to a deterministic server, a particular queueing system arises whose analysis has a significant role in ATM based networks. Periodic cell generation during active times is a major feature of these sources. In this paper a new analytical method is provided to solve for this queueing system via an approximation to the transient behavior of the nD/D/1 queue. The solution to the queue length distribution is given in terms of a solution to a linear differential equation with variable coefficients. The technique proposed here has close similarities with the fluid flow approximations and is amenable to extension for more complicated queueing systems with such correlated arrival processes. A numerical example for a packetized voice multiplexer is finally given to demonstrate our results.
Open Access
Markov modulated periodic arrival process offered to an ATM multiplexer
(Elsevier BV * North-Holland, 1995-04) Akar, N.; Arıkan, E.
When a superposition of on/off sources is offered to a deterministic server, we are faced with a particular queueing system, the analysis of which has a significant role in ATM networks. Periodic cell generation during active times is a major feature of these sources. We provide an analytical approach to solve for this queueing system via an approximation to the transient behavior of the nD/D/1 queue. The solution to the queue length distribution is given in terms of a solution to a linear differential equation with variable coefficients. The technique proposed here has close similarities with the fluid flow approximation and is amenable to extension for more complicated queueing systems with such correlated arrival processes. A numerical example for a packetized voice multiplexer is finally given to demonstrate our results.
Open Access
A simulation study of forward error correction for lost packet recovery in B-ISDN/ATM
(IEEE, 1993-05) Oğuz, Nihat Cem; Ayanoğlu, E.
We present the results of a simulation study for a virtual circuit connection over an ATM network where forward error correction is performed at both the ATM cell level and the packet data unit (PDU) level. A main conclusion of this study is that at low loads ATM cells from the same source dominate in the switch buffers, while at high loads there is a mixing of ATM cells from different sources. For the latter case. ATM cell level coding performs better, while for the former, PDU level coding performs better. The combination of the two techniques has the best overall performance.
Open Access
A simulation study of two-level forward error correction for lost packet recovery in B-ISDN/ATM
(IEEE, 1993) Oğuz, Nihat Cem; Ayanoğlu, E.
The major source of errors in B-ISDN/ATM systems is expected to be buffer overflow during congested conditions, resulting in lost packets. A single lost or errored ATM cell will cause retransmission of the entire packet data unit (PDU) that it belongs to. The performance of the end-to-end system can be made much less sensitive to cell loss by means of forward error correction. In this paper, we present the results of a simulation study for an ATM network where forward error correction is performed at both the cell level and the PDU level. The results indicate that (i) cell losses are highly correlated in time, and analytical models ignoring this fact will not yield accurate results, (ii) the correlation of cell losses is similar to burst errors in digital communication, and similar code interleaving techniques should be used, (iii) coding cells and PDUs separately provides this interleaving effect, and this joint code outperforms coding only at the cell level or only at the PDU level in almost all cases simulated.
Open Access
Wireless ATM: limits, challenges, and proposals
(Institute of Electrical and Electronics Engineers, 1996) Ayanoglu, E.; Eng, K. Y.; Karol, M. J.
Recently, there has been an increased interest in the topic of "wireless ATM." The subject matter raises interest due to the potential combination of two of the hottest topics in communications of the mid-'90s, but at the same time raises a natural question as to its viability, and sometimes even its desirability. In this article the authors survey potential applications of wireless ATM and describe what is usually meant by wireless ATM, why it may make sense, and some of the proposals to build systems based on it. The emphasis in this article is on the physical layer, the data link layer, and the access layer. The authors also present general observations on each of these layers, and some research solutions to these problems. Mobility issues and interoperability with the existing networks are addressed. Finally, the authors list some of the proposals to build wireless ATM systems from the literature.