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Page 1: webmail.aast.eduwebmail.aast.edu/~khedr/Courses/Graduate/Wireless...HOW TO START 1. Find a suitable advisor and a good group. 2. Look for a good idea, study literature & discuss, do

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Baseline: AWGN Channel

BPSK modulation

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Rayleigh Flat Fading Channel

BPSK: Coherent detection.

Conditional on h,

Averaged over h,

at high SNR.

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Conditional on h,

When error probability is very small.When error probability is large:

Typical error event is due to channel being in deep faderather than noise being large.

Typical Error Event

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Objective of DiversityIf diversity is not employed, the

resulting efficiency would be very low, as it can be deduced from the comparison of AWGN vs. Rayleigh channel BER.

Diversity refers to transmitting and/or receiving the same information via different (preferably independent) ways.

Diversity combats fading and improves the BER performance which– directly translates to power

savings,– increased system capacity.

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Selection Combining

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RESEARCH METHODS: From Problem and Hypothesis to

Experiments

Literature review

Problem andhypotheses

Experiments/analysis

Theory/paper(new knowledge)

System(prototype)

Idea

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SOME DEFINITIONS

• Research: Careful study or investigation to discover new knowledge

• basic research (no specific application in mind)

• applied research (ideas into operational form)

• Development: Systematic use of the existing knowledge

• Note. Research and development are closely related. In research a prototype is often developed.

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HOW DOES A RESEARCHER WORK?

1. Make always notes in a notebook (day book)

2. Make plans for the future all the time (outlines, roadmaps)

3. Discuss, ask questions and argue (criticism)

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COMMUNICATIONS IMPROVE CREATIVITY

YOURSELF

Encouragement, criticism

Advisor

LandmarkPaper

Other researchers

Oral communicationsWritten communications

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RESEARCH IDEAS

To find research ideas, use your own intuition/expertise and..

• know the literature, especially original landmark papers (write brief well-organized summaries)

• do experiments early in your studies, use your colleagues’ experience

• discuss with colleagues and students and teach them (seminars)

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RESEARCH PROPOSAL• Abstract• Introduction

– problem and hypothesis• Review of the literature

– good organization, concept analysis• Materials and methods

– system requirements, system specifications– plan for operation, experimental procedures– analytical and other tools

• Results– results (for example experimental data) to be expected– publication and other dissemination of research results

• Discussion and conclusions– originality, open questions, limitations– validation, significance, applications

• Time frame, budget– intermediate objectives

• Bibliography – list of references

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TIMING OF DOCTORAL THESIS (4 years)

1. Proposal2. Courses3. Literature4. Experiments5. Reports6. Papers7. Thesis8. Defence

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ROADMAP AND VISION OF TELECOMMUNICATIONS (1)

2000 2010 2020 2030 2040

Digital broadcast Mobile DVB

Wireless Internet Mobile Internet

Mobile universal

WPAN

FWA

Ad hoc networks

Satellite positioning

Supermacrocells

3D telepresence

Mobile wide-screen

Megacells

Mobile 3D voice Multi-sense interaction

Multicast/unicast

True virtual reality

Haptic interaction

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ROADMAP AND VISION OF TELECOMMUNICATIONS

(2)

Worm holes? ANSIBLE?

Teleportation? Time machines?

Telepathy? Telesocializing?

Intergalactic network?

Real-time Internet? Direct MMI? Nanobots? Holodeck?

3000 4000 5000 6000 7000

Quantum comms?

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HOW TO START1. Find a suitable advisor and a good group.

2. Look for a good idea, study literature & discuss, do not reinvent the wheel.

3. Define the problem, limit the scope, find the right approach and hypotheses (= possible solutions), write a research proposal.

4. Analyze the system, make experiments (simulations, prototypes) and discuss the results, use right tools.

5. Write a paper or thesis and listen carefully to comments and be prepared to argue and defend your claims (opponents try to find weak points in your reasoning!).

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Look for a good advisor• Be there for the length of your project• Experience on research in the same area (a doctor)

• Pedagogical skills, know the big picture, know literature

• Respected by colleagues, critical, tough methodologist

• Interested in your topic, gives comments, you respect him/her

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•Orient your advisor (system model, block diagrams, table of contents)

•Follow instructions (make notes), but also discuss and argue

•Make concise progress reports (organize the material, limit the scope)

•Do not expect ready-made solutions, but ways of thinking

•Advisor needs also credit for his/her work in the form of publications

•Get into the driver’s seat!