Introduction ETSN01 Advanced Telecommunications. Emma Fitzgerald

Transcription

1 Introduction ETSN01 Advanced Telecommunications Emma Fitzgerald 2015

2 Course administration and overview Expected outcomes Pre-requisites Course structure Teaching team Assessment General points Socrative A concrete example Lund University Slide 2 of 18

3 Components Two main parts Performance models / mechanisms in-depth Stochastic nature of networks Queuing theory, Markovian processes, simulations Understanding the need to analyse and dimensioning Systems building Centrally designed architectures Routing and switching functions Server functions Distributed architectures (unplanned) Medium access control in unlicensed spectrum (WiFi) Ad hoc and Mesh Lund University Slide 3 of 18

4 Expected outcomes In-depth understanding of the design choices in common network design, where some of the most common standards come from Ability to analyse simple networked systems (nice distributions) and dimension components such as buffers and links Ability to implement discrete event simulators and carry out experiments scientifically (understanding of errors, limitations, etc.) Knowledge about most common systems constructs, the telecom and datacom system models and common implementations Awareness of current issues and future directions of network constructs The focus is largely on wireless technologies from the systems perspective Lund University Slide 4 of 18

5 Pre-requisites In order to be successful in this course, the following skills are assumed: Basic course on network protocols and IP systems (must) Basic course in statistics / stochastic processes Programming (not required but helpful) Lund University Slide 5 of 18

6 Course content and structure Week Lecture Material Lab 1 Introduction, probability review, simulation Compendium chapters 1 and 2 No lab 2 MAC 1: Reservation schemes, Compendium chapter 3 Lab 1: TDMA queueing theory 3 Queueing networks, MAC 2: Compendium chapters 3 and 4, Lab 1: TDMA Random access Manitpornsut et al. (2009) 4 Modelling, network constructs Kleinrock and Tobagi (1975), Bianchi (2001), Rührup (2009), Gupta and Kumar (2000) Lab 2: CSMA 5 Congestion control and TCP, Compendium chapters 5 and Lab 2: CSMA quality of service 6, Floyd and Jacobson (1993), Karn and Partridge (1987), Jacobson (1995), RFC 6298, RFC 1633, RFC Quality of service (cont.), cellular Compendium chapters 6 and 7, Lab 3: Queueing disciplines networks RFC 1633, RFC Guest lecture, review Lab 3: Queueing disciplines

7 Literature Recommended books (not compulsory for the course!) Mobile Communications Jochen Schiller, Addisson Wesley, ISBN High Speed Networks and Internets: Performance and Quality of Service William Stallings, Prentice Hall ISBN Queueing Systems Volume 1: Theory Leonard Kleinrock, Wiley Interscience ISBN Lund University Slide 7 of 18

8 Teaching team Course co-ordinator, lecturer Emma Fitzgerald E:3128 / MAPCI Tutor Antonio Franco antonio.franco@eit.lth.se E:3124b / MAPCI Examiner Björn Landfedlt bjorn.landfeldt@eit.lth.se E:3145 / MAPCI MAPCI: Mobilvägen 10, level 2 Lund University Slide 8 of 18

9 Assessment Check how well you follow and are able to understand the tutorials and labs Take home assignment (literature review, theory, simulation tasks) (2.5 cp) Final exam (5 cp) Lund University Slide 9 of 18

10 General points How to succeed Start early, a lost week is hard to make up for Get on top of your simulation skills As in all large scale systems courses, the material may sometimes seem simple but relationships are sometimes nested and very complex, dont be fooled! The course requires self-study: study the compendium, the extra material and the notes, not just the notes. All submitted code and text will be tested for plagiarism. Academic dishonesty is not an option. Lund University Slide 10 of 18

11 Socrative In this course we will use Socrative, an interactive learning tool When you see this symbol do on Socrative it means there is an activity to Go to socrative.com, click on Student login and enter ETSN01 as the room name There will also be an exit quiz at the end of each lecture to check what you have learned and how the course is going Socrative questions are not part of the assessment: they are only there to help both you and me! Lund University Slide 11 of 18

12 Expected outcomes Pre-requisites Course structure Teaching team Assessment General points Socrative A concrete example Socrative Example Which do you like best? A Kanelbulle B Semla C Wienerbro d D Lussekatt E Vaniljbulle Lund University Slide 12 of 18

13 Network Performance Modelling the art of analysing and understanding your network behaviour Lund University Slide 13 of 18

14 Illustrative example problem TCP is the most common transport protocol in use Designed with many mechanisms to achieve reliability, flow control, congestion control etc. Side effects present in any protocol design, in this case: Bandwidth is round trip time (RTT) and loss constrained Lets look at it! Lund University Slide 14 of 18

15 TCP bandwidth limitation Postulate BW max = MSS C RT T p C = 3 2 BW: bandwidth, MSS: maximum segment size, RTT: round trip time, p: packet loss probability Assume best conditions No buffer limitation Only occasional packet loss, probability p Constant RTT Link delivers 1/p consecutive packets Window opens 1/window segments per ack (RTT) Lund University Slide 15 of 18

16 Graphical representation

17 Why is this a problem? Long end-to-end path, maximum segment size (MSS) likely to be fixed We need to control delay and packet loss to help TCP Many TCP connections share resources end-to-end What is causing delay and packet loss? How do we control delay and packet loss? How do we engineer networked systems to meet demands? Lund University Slide 17 of 18

18 In the course we will look at Static dimensioning Analytically queuing theory Experimentally simulations Dynamic methods Congestion control protocols (TCP is one example) Per router congestion control Important point: Networks behave stochastically Start with Simulation, followed by queuing theory Lund University Slide 18 of 18