Communication Networks ResearchLaxmi Subedi, Mohamadreza Najiminaini, and Ljiljana Trajković, {lsa38, mna28, ljilja}@cs.sfu.caCommunication Networks Laboratory, School of Engineering Science, Simon Fraser University

Communication Networks Laboratoryhttp://www.ensc.sfu.ca/research/cnl

Packet loss is an indicator of congestion and it causes TCP to reduce its congestion window size and throughput.TCP is designed for wired networks, where packet loss is mainly due to congestion.In wireless networks, TCP packet loss is often caused by transmission errors and handoffs. Hence, there is no need to reduce the TCP congestion window size.

Improving TCP over wireless links

ACK(n-1) ACK(n)

Mobile host (receiver)

Fixed host (sender)M-TCPSH-TCP

TCP M-TCP

Super host (router)

M-TCP network architecture.

Modeling traffic from a public safety wide area network

Repeaters

Consoles Dispatch

NetworkGateway

Air Interface

Data

PSTN

Data PortManagement

Other EDACS Systems

T1

M-RK

M-RK

M-RK NETWORKSWITCH

Data Gateway

PBX Gateway

T1

T1

Other EDACS Systems

T1

E-Comm network architecture.

Statistical analysis of collected data reveals that:call inter-arrival times are long-range dependentcall holding times follow lognormal distribution and are uncorrelated.

Clustering analysis is used to model user behavior.Traffic is predicted using Seasonal Autoregressive Integrated Moving Average(SARIMA) models.

E-Comm network coverage.

Analyzing packet loss in IP networks

A signal is decomposed into a hierarchical set of approximations and details using wavelet analysis. The detail part provides information in the time and frequency domains. It serves as a mathematical microscope for investigating complex traffic and loss pattern.

Loss pattern analysis: details on various time scales.

Characterize, model, and analyze collected traffic data.Apply statistical analysis and search for traffic invariants: self-similarity and long–range dependence.Understand underlying dynamical behavior of complex systems representing packet networks.

BCNET Technology ConferenceApril 22 - 23, 2008

References:• W. G. Zeng and Lj. Trajkovic, “TCP packet control for wireless networks,” Proc. IEEE Int. Conf. on Wireless and Mobile Computing, Networking and Communications (WiMob 2005), Montreal, Canada, Aug. 2005, vol. 2, pp. 196–203.• F. Xue, V. Markovski, and Lj. Trajkovic, “Wavelet analysis of packet loss in video transfers over UDP,” Proc. Internet Computing 2000, Las Vegas, NV, June 2000, pp. 427–433.• D. Sharp, N. Cackov, N. Laskovic, Q. Shao, and Lj. Trajkovic, “Analysis of public safety traffic on trunked land mobile radio systems,” IEEE J. Select. Areas Commun., vol. 22, no. 7, pp. 1197–1205, Sept. 2004.• H. Zhang, M. Liu, V. Vukadinovic, and Lj. Trajkovic, “Modeling TCP/RED: a dynamical approach,” in Complex Dynamics in Communication Networks, Lj. Kocarev and G. Vattay, Eds., Berlin: Springer, Series: Understanding Complex Systems, 2005, pp. 251–278.

Measuring traffic from BC.NET

10000

Capture system

10/100/1000/10000

Ethernet switch 1

10/100/1000

Capture system

10/100/1000

Ethernet switch 2

Supplier 1 Supplier 2Supplier 3

Proposed additions10 GigE link1 GigE link

BC.NET router

BC.NET client diagram.