Dr John Schormans, BSc(Eng) PhD CEng MIET SFHEA

Teaching

Communications Systems (Postgraduate/Undergraduate)

This module provides a broad background to communications systems and the associated underlying theory. The module will provide an introduction to the generic communication system model, and how it is affected by noise. This will also include switching networks, PCM and SQNR, voice over packet. It will cover and introduction to information: the information measure, entropy and the binary symmetric channel model; coding: for compression and for error detection and correction.

Modelling and Performance (Postgraduate/Undergraduate)

Background material: probability, conditional probability, Markov models, Queue modelling of OS, e.g. multi-tasking, proof (and uses) of Little¿s law. Workload modelling: exponential versus Pareto; call centre analysis. Simulation-how to generate random numbers from arbitrary distributions, steady state versus terminating; output analysis; some simple simulation applications. Reliability theory: oriented towards electronic systems, though e.g. passive component failure, and then to microprocessor (embedded software) systems through s/w failures Network Science: introduction to the fundamental ideas in network science: graph theory, network metrics, network models, network robustness. Approach to modelling emergence and topological robustness of supply networks, communication networks and general human-technology interaction.

Signals and Information (Undergraduate)

This first year module introduces the fundamentals of signals, Fourier Series, information theory and signal statistics. Topics covered include: signal fundamentals such as discrete versus continuous time signals; signal average, energy and power; orthogonality; Fourier Series. The module also provides an introduction to information theory, including the information measure, entropy and the binary symmetric channel. Basic ideas in statistics will also be introduced. It will be taught by a combination of lectures, tutorials and labs.

Research

Research Interests:

My main focus is on analysis, simulation and measurement of packet?based networks, in wired and wireless scenarios. This includes evaluat ing QoE as well as more traditional network performance metrics.

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Current and recent PhD students

Current:

Adrian Woodrough - A network-centric vertical handover algorithm for Mobile Satellite Services

Tianhao Guo - User-Experience Informed Resource Allocation in Wireless Networks

Abdul Wahab - error propagation in measuring QoE from QoS metrics

Nafi Ahmad

Completed

Mujtaba Roshan - Experimenting with network measurements and evaluating user QoE

Amna Wahid - Measurement of Overflow Probability in a Packet Buffer

Xingyu Han - Channel Adaptive Analy sis in Wireless Networks with Application to Routing

Zhong Bo - Heterogeneous Traffic Cross-Layer QoS Provision with Dynamic Spectrum A llocation in OFDM-Based Cognitive Radio Networks

Amna Wahid - Optimising the sampling rate when measuring packet-level performance in p acket networks

Adrian Woodrough (part time, while working for Inmarsat, London, UK) - Analysis of hand-over strategies in satellite net works

Ling Xu - Planning Simulation Run Length in Packet Queues

Vindya Amaradasa - Traffic aggregation techniques for non-FIFO schedulers, 2009

Syeda Samana Naqvi - packet level measurements over wireless MPhil, 2008

Maheen HASIB: Analysis of packet loss probing in packet networks . June 2006

Shaowen LU: A systematic multi-level abstraction approach to error constrained time-stepped accelerated simulation for MANETs . 2006

Sharifah ARIFFIN: Accelerated simulation of a packet buffer with a non-FIFO scheduler . March 2006

Ali RAZA: Layered Space Time Architectures For Mimo Wireless Channels . 2006

Chi Ming LEUNG: Non-Intrusive Measurement in Packet Networks and its Applications . February 2004

Ho I (Athen) MA: Accelerated Simulation of Power-Law Traffic in Packet Networks . September 2003

Robert STEWART, End-toEnd Delay Analysis for Small/Medium Scale IP Networks November 2002

Arif AL-HAMMADI Intel ligent Techniques for VBR Traffic Control in ATM Networks . March 2000

Tijana TIMOTIJEVIC  System Level Performance of ATM Transmission over a DS-CDMA Satellite Link April 1999

Sufian YOUSEF, APU, 1995

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GR/K83489/01

ATM NETWORKS: MANAGING THE RESOURCES AND CONTROLLING THE TRAFFIC

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Focusing on EP/G012628/1< span style="box-sizing: border-box; font-weight: 700;"> Optimal design of performance measurement experiments for complex, large-scale networks, Key Findings:

Broadband packet communications networks, exemplified by the internet, are supporting virtually all information exchange internationally. Packet-lev el performance (packet loss and delay) is the dominant factor controlling user experience of these networks, and as user experience is ultimately the key factor driving commercial success, the key network performance measures must be accurately monitored.

A challenging unsolved problem in packet networking has lo ng been: how do we monitor packet level performance in an optimal fashion? This is equivalent to asking how we can ensure that the samples of loss and delay taken from a network c ontain the maximum amount of information (or that they have minimum variance and bias).

In this project we addressed this question. By modelling networks using Markov state models we have been able to treat network measurement and monitoring as numerical experiments. This crucial step then allowed us to optimise these measurement experiments using the Statistical Theory of the Design Of Experiments (DOE).

The major results of this project includ e a utility based framework for optimisation of packet network measurement, and a new approach to optimal sampling based on the maximisation of Fisher Information. This latter bre akthrough led directly to the development of framework for a new science of DOE that allows the ?items? in any experiment to be inter-connected. This is new, and has the potential to revolutionise the use of DOE across a wide range of domains, including agriculture, drug development, viral-marketing techniques, and social policy research as well as in comm unications networking.

Potential use in non-academic contexts

Potential use in non-academic contexts: Network and Service Providers have an urgent need to accurately monitor the performance of their networks, essentially to ensure that they are meeting the guarantees th at are written into their Service Level Agreements (SLAs). Our research can be used directly to set-up pre-existing network monitoring equipment to ensure that best possible use i s made of the monitoring equipment.

 KEY RECENT PAPERS:

Holistic assessment of call centre performance

Smith EA, Schormans JA

QoS-Aware Energy-Efficient Cooperative Scheme for Cluster-Based IoT Systems

Song L, Chai KK, Chen Y, Schormans J, Loo J, Vinel A

Optimal design of experiments on connected units with application to social networks

Parker BM, Gilmour SG, Schormans J

Self-organising cluster-based cooperative load balancing in OFDMA cellular networks

Xu L, Chen Y, Chai KK, Schormans J, Cuthbert L

Optimal design of measurements on queueing systems

Parker BM, Gilmour S, Schormans J, Maruri-Aguilar H

QUEUEING SYSTEMS 79(3-4):365-390 Apr 2015

Increasing throughput in IEEE 802.11 by optimal selection of backoff parameters

Gilmour SG, Schormans JA, Parker BM

IET Networks 4(1):21-29 01 Jan 2015 DOI for this publication

Utility based framework for optimal network measurement

Schormans J, Parker BM, Gilmour SG

IET Networks 4(1):10-20 01 Jan 20 15 DOI for this publication

Evaluating QoE in Cognitive Radio Networks for Improved Network and User Performance

Zhong B, Schormans J, Bodanese E

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Performance comparisons between cellular-only and cellular/WLAN integrated systems based on analytical models

Song G, Yang L, Wu J, Schormans J

Frontiers of Computer Science 7(4):486-495 01 Aug 2013 DOI for this publication

Self-organising cluster-based cooperative load balancing in OFDMA cellular networks

Xu L, Chen Y, Chai KK, Schormans J, Cuthbert L

Wireless Co mmunications and Mobile Computing 2013 DOI for this publication

A Performance Study of Hierarchical Heterogeneous Wireless Integrated Networks

Song G, Wu J, Schormans J, Yang L, Cuthbert L

APPLIED MATHEMATICS & INFORMATION SCIENCES 6(2):497S-504S Apr 2012 Author URL

Erlang's fixed-point approxim ation for performance analysis of HetNets

Song G, Wu J, Schormans J, Cuthbert L

Journal of Applied Mathematics 2012 20 Jun 2012 DOI for this publication

Design of Experiments for Categorical Repeated Measurements in Packet Communication Networks

Parker BM, Gilmour SG, Schormans JA

TECHNOMETRICS 53(4): 339-352 Nov 2011 Author URL DOI for this publication

Publications