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Presentation Transcript

Summary of recent results

Work in progress: Active techniques to characterise delays and losses in forward and reverse links and paths. Development of Arrowsmith tool for Local Internet characterisation.

Recent Research and ProjectsInternet Pricing and Queue Control Wireless Networks Internet Measurement and Analysis Voice over IP Technologies Optical Networks Packet Switch Architectures

Indian Institute of Technology Bombay

Academia Industry Meet 2002, Electrical Engineering Department

Internet Pricing and Queue Control

Join Minimum Cost Queue

- Parallel queues with single server providing round robin service
- Each queue has a join price and congestion is posted
- Arrivals use a disutility f(price,queue) that is increasing in price and queue and joins the queue for which the disutility is minimum
- Motivation from Tirupati queues

Indian Institute of Technology Bombay

Academia Industry Meet 2002, Electrical Engineering Department

Results:

We show that for single class with linear cost

function, the system is nearly socially optimal

Use truncation models and reduce the

problem to Quasi Birth Death Models for

analysis in the presence of multiclass customers

Use a dynamic price adaptation scheme to

maintain the queue lengths at prescribed levels

and analyse using o.d.e. approach to

stochastic approximation

Indian Institute of Technology Bombay

Academia Industry Meet 2002, Electrical Engineering Department

Wireless Networks

- Power control and its analysis using stochastic
Approximation techniques.

- Simplified derivation for the critical transmission
range using results from geometric random graphs

- Exact connectivity expression for finite networks
- Scheduling in Ad Hoc Networks for special purpose
communication like gossiping: motivation from

distributed control using ad hoc networks

Indian Institute of Technology Bombay

Academia Industry Meet 2002, Electrical Engineering Department

Internet Measurement and Analysis

- Construct user based models: How does a end-user use the Internet?
- Develop passive and active algorithms to measure the “Local Internet”

- Entropy of the destination set from a LAN is very
- low -- 3-5 bits!
- Hoggers are hoggers over long and short time scales
- Sampling can be used to know the “destination”
- profile from a sink

Continued

Indian Institute of Technology Bombay

Academia Industry Meet 2002, Electrical Engineering Department

Internet Measurement and Analysis

- Local Topology does not change frequently
- Loss is infrequent but delay variation is
- significant

Indian Institute of Technology Bombay

Academia Industry Meet 2002, Electrical Engineering Department

Optical Networks

- Efficient virtual topology sequence for
- multiperiod design.
- Apply “simple” well known algorithms to resource
- allocation problems in Optical Networks –
- Edge Disjoint Path and its applicability to Routing
and Wavelength Assignment;

- Vehicle Routing Problems to Grooming;
- Time dependent solutions of queues to capacity
allocation and expansion

- Edge Disjoint Path and its applicability to Routing

Indian Institute of Technology Bombay

Academia Industry Meet 2002, Electrical Engineering Department

Packet Switching Architectures

- Extensive analysis of copy networks and
- multicast switches
- Extensive continuous time analysis of input
- queued packet switches to deal with variable
- length packets and interarrival times
- drawn from continuous distributions.

Indian Institute of Technology Bombay

Academia Industry Meet 2002, Electrical Engineering Department

In the not too distant past

- Queueing Theory and Stochastic Processes
- A bivariate exponential distribution using linear
- structures and using it to model queues with
- correlations in the arrival and service times.
- Queue Inference Algorithms: Passive estimation
- algorithms of queue length and waiting times
- using transaction information. Also
- applications to many WANs and LANs..
- Integral Expressions for Normalising Constant
- in generalised product form networks

Continued

Indian Institute of Technology Bombay

Academia Industry Meet 2002, Electrical Engineering Department

In the not too distant past

QNAT:

• Queueing Network Analysis Tool for use with Mathematica

• Over 1000 downloads and good feedback.

Multiple Access Networks:

• Bandwidth Allocation Schemes in Unidirectional Bus Networks

• Performance analysis of random access protocols for ring

topology networks

• Renewal models for inter-LAN traffic

Multicasting:

• Closed queueing network models with fork-join nodes to

analyse throughput properties.

Indian Institute of Technology Bombay

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