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Smart Communication Systems

Modul: Autonomous Communication (MINF-KT-AC.W07, Master)
Semester: Wintersemester 2007/2008
Art: PJ (6 SWS / 6 LP)
LV-Nr.: 0435 L 743
Veranstalter: Albayrak
Zeit: Mittwoch, 14 - 16 Uhr, ab 24.10.2007
Raum: MA 544

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The area of Wireless Mesh Networks is a hot topic in telecommunications. This combined lecture-project module teaches students the basics of Wireless Mesh Networks (WMN) via 5-6 lecture sessions. Key issues focused on are: architecture, routing, MAC-layer protocols, and multi-channel communication. Students have the chance to learn the basics, analyze and research on existing schemes in this area and then design and develop their own proposed enhancements to the current protocols we have today for wireless mesh networks. This is very motivating since people with very basic knowledge of communications and networking can very quickly learn the basics of WMNs, perform some basic research and analytical evaluation of existing schemes and mechanisms and also propose their own contributions and verify them with proof of concept simulations and implementations.


The aim of this project is to become familiar with the concept of wireless mesh networks (WMN). Afterwards, after understanding the architecture and the basics, namely routing, MAC-layer and mobility issues, the extension of the current work in the direction of multi-channel and multi-radio for the MAC layer is foreseen.



Wireless Mesh Networks Overview

  • Wireless mesh networks (WMNs): consist of wireless access point/routers (mesh routers) forming a backbone to which many other client mesh nodes connect.
  • WMNs support ad hoc networking, and have the capability of self-forming, self-healing, and self-organization
  • WMNs are multi-hop wireless networks, but with a wireless infrastructure/backbone provided by mesh routers
  • Mesh routers have minimal mobility and perform dedicated routing and configuration, which significantly decreases the load of mesh clients and other end nodes
  • Mobility of end nodes is supported easily through the wireless infrastructure
  • Mesh routers integrate heterogeneous networks, including both wired and wireless. Multiple types of network access supported in WMNs
  • WMNs are not stand-alone and need to be compatible an interoperable with other wireless networks

Wireless Mesh Network Interesting Properties

  • WM Routers are self-configuring, self-healing links among themselves
  • Mixed-mode networking supported (P2P WM client access vs infrastructure (vs wireless routers or backbone))[ref: GC 2003MM NW paper]
  • Not scalable, performance strongly degrades with network size
  • Throughput/capacity enhancement via: relay nodes
  • Facilitation/ load reduction in routing via clustering
  • Scalable routing protocols: hierarchical routing too complex to manage; geographical routing: low feasibility
  • Cross-layer design: combining L2-L3 parameters && metrics; merging functions; (also L2-L4)



To understand Wireless Mesh Networks

To understand routing in general and in particular in WMN

To select a subset of suitable routing algorithms and analyze them

To understand scheduling, buffering, and other aspects of the MAC protocol




To build a mesh testbed based on Linux boxes so that the topology is a mesh topology and that each communication node is a multi-channel node



To simulate in ns2 an enhancement to a MAC protocol of choice provided that the protocol itself contains an extension or enhancement to a well-known protocol today



To implement a topology and configuration based on multi-channel communication and to configure the right routing protocols and to set the proper MAC parameters. Already protocols such as IEEE 802.11 allow setting MAC parameters e.g. for 802.11e via a web interface.


Issues to address during the project

  • Multi-path routing in the mesh part
  • QoS-aware routing or cross-layer enhanced routing decisions
  • How to make the MAC of the mesh multi-channel? And how to benefit from this?
  • How would a multi-channel MAC impact a simple randomly built mesh network: Positively: higher data rates, more efficient routing especially on multi-path? Negatively: increased complexity, necessary interfacing, etc


Woche Thema/Inhalt
1 Lecture: Introduction to Wireless Mesh Networks
  Exercise: to write a 2-3 page report on wireless mesh networks including a sample topology in MS Visio
2 Lecture: MAC, Throughput, QoS and Performance Issues in WMNs
  Exercise: to write a 2-page report on throughput theoretical values for single and multiple antenna WLAN nodes in a mesh network
3 Lecture: Routing in Wireless Mesh Networks
  Exercise: Describe one proactive and one reactive routing protocol (1-page each) used in WMNs
4 Lecture: Special Topics in WLAN-Based Wireless Mesh Networks
5 Lecture: Practical Issues with Building and Optimizing WLAN-Based WMNs
  Exercise: Build a mesh and measure different throughput levels
6 Exercise: Work on self-interference on a single box with multiple channels and multiple units (antennas): measure, analyze, optimize
7 - 8 Exercise: Routing in WMNs, configure protocols (1 or 2), tables and trace tables. Document the setup and tracing or routing procedures. Report on Linux configuration steps and routing table traces
9 - 10 Exercise: Modify routing such that MAC output from different channels is merged into a single table that performs routing for multi-channel MAC in the mesh network under question
11 Break + decision for last part of the project work. Alternative topics:
  configure 1 antenna to listen and others for the mesh and communicate (3 antennas per node communicate, 1 antenna listens)
  simulate in ns2 the flow of multiple MAC pipes and the aggregation of all flows into one via an aggregator
  define your own topic to work on during the last 4-5 weeks
12 - 15 Design and implement the project part defined in 11

Prüfungsmodalitäten, Anforderungen

Die Note setzt sich aus mehreren Teilleistungsn zusammen, die wie folgt gewichtet werden:

  • 20% reporting for exercise assignments in [weeks 1-10]
  • 25% performing basic communication between mesh nodes and deploying various routing protocols
  • 20% measurements and configurations related to multi-channel MAC
  • 35% final subproject (with implementation in testbed or simulation) + bonus for defining own subproject [weeks 11-15]

Informationen zum Modul

  • Dieses Modul kann sowohl von Studierenden im Diplom als auch in den Masterstudiengängen Informatik und Technische Informatik belegt werden.
  • Dieses Projekt ist Pflichtbestandteil des Moduls.
  • Diplomstudenten können das Projekt auch ohne die anderen Modulbestandteile belegen, die Inhalte der IV werden allerdings vorausgesetzt.
  • Im Bachelor kann diese Veranstaltung nicht belegt werden!
  • Weitere Informationen zum Modul (MINF-KT-AC.W07)
  • Ansprechpartner

    Muslim El-Kotob