“Wireless Mesh Networks”
Πανεπιστήμιο Μακεδονίας,
Τμήμα Διοίκησης Τεχνολογίας
Μάθημα: Ασύρματες Τηλεπικοινωνίες
Διδάσκων: κ. Χατζημίσιος
Μάιος 2009.
Ζλάτης Χρήστος
Α.Μ. 45/06
tm0645@uom.gr

Contents
 Introduction – Definitions
 Technology & Network architecture
 Advantages of WMNs
 Critical Design factors
 Research Challenges & problems
 Applications of WMNs
 Conclusion

Introduction – Definitions
 "A mesh network is a network that employs one of two
connection arrangements, full mesh topology or partial
mesh topology. In the full mesh topology, each node is
connected directly to each of the others. In the partial
mesh topology, nodes are connected to only some, not
all, of the other nodes.“
[TechTarget and Telecom Glossary 2K definition]
 Wireless mesh networks (WMNs) are regarded as an
economical alternative key technology for next-
generation wireless networking.
 Wireless mesh networks can easily, effectively and
wirelessly connect entire cities using inexpensive,
existing technology.

Let’s talk about Technology and
Network architecture… [1/2]
 Wireless mesh networks (WMNs) are dynamically self-
organized and self-configured and they are comprised of
two types of nodes: mesh routers and mesh
clients.
 Three types of wireless mesh networks:
 Infrastructure wireless mesh networks: Mesh
routers form an infrastructure for clients.
 Client wireless mesh networks: Client nodes
constitute the actual network to perform routing and
configuration functionalities.
 Hybrid wireless mesh networks: Mesh clients can
perform mesh functions with other mesh clients as well
as accessing the network.

Let’s talk about Technology and
Network architecture… [2/2]
 In a wireless mesh network, only one node needs to
be physically wired to a network connection like a
DSL Internet modem.
That one wired node then shares its Internet
connection wirelessly with all other nodes in its
vicinity. Those nodes then share the connection
wirelessly with the nodes closest to them.
 The more nodes  the further the connection spreads 
creating a wireless "cloud of connectivity" that can
serve a small office or a city of millions.
 WMNs have rapid commercialization in many application
scenarios such as broadband home networking,
community networking, building automation, high-
speed metropolitan area networks, and enterprise
networking.

Why WMNs are interesting?
 Fewer wires  less cost to set up a network
 More nodes  bigger and faster wireless networks
 Same WiFi standards (802.11a, b and g)
 Useful for Non-Line-of-Sight (NLoS) network
configurations  wireless signals are intermittently
blocked.
 “Self configuring" networks  the network
automatically incorporates a new node into the existing
structure without needing any adjustments by a network
administrator.
 “Self healing" networks  the network automatically
finds the fastest and most reliable paths to send data,
even if nodes are blocked or lose their signal.
 Wireless mesh configurations allow local networks to
run faster  local packets don't have to travel back to
a central server.

What are the Advantages of WMNs?
 Price: 802.11 radios are quite cheap, but the radios are
often still expensive. Each mesh node runs both as a
client and as a repeater  less radios.
 Ease and simplicity: Pre-installed wireless mesh
software, standard wireless protocols  the setup is
extremely simple.
 Organization and business models: A decentralized
ownership model  each participant in the network
owns and maintains their own hardware  simplify the
financial and community aspects of the system.
 Integration: Mesh hardware is typically small,
noiseless, and easily encapsulated in weatherproof
boxes.
 Power: The substrate nodes of a mesh network can be
built with extremely low power requirements 
autonomous units with solar, wind, or hydro power.

What are the Critical Design
Factors?
 Radio Techniques.  increase capacity and flexibility
of wireless systems (directional and smart antennas,
MIMO systems and multi-radio/multi-channel systems).
 Scalability. Without support of this feature, the
network performance degrades significantly as the
network size increases.
 Mesh Connectivity.  network self-organization and
topology control algorithms are needed.
 Broadband and QoS. Different from classical ad hoc
networks, most applications of WMNs are broadband
services with heterogeneous QoS requirements.
 Ease of Use. Protocols must be designed to enable the
network to be as autonomous as possible  network
management tools need to be developed

What are the Research Challenges?
 Scalability. Based on existing MAC, routing, and
transport protocols, network performance is not scalable
with either the number of nodes or the number of hops
in the network.
 This problem can be alleviated by increasing the
network capacity through using multiple
channels/radios per node or developing wireless radios
with higher transmission speed.
 Security. WMNs are vulnerable to security attacks in
various protocol layers.
 Still exists a need for a comprehensive
mechanism to prevent or counter attacks in all protocol
layers.
 Moreover, there is a need for self-organization and
self configuration capability, improved protocols and
new schemes.

Let’s talk about Applications of
WMNs… [1/2]
 Developing Countries
 Solar-powered nodes can be connected to one cellular
or satellite Internet connection, which could keep a
whole village online.
 Isolated Locations, Rugged Terrain
 A series of nodes would be mounted from the nearest
available wired access point out to the hard-to-reach
area.
 Education
 This solution eliminates the need to bury cables in old
buildings and across campuses. Mesh networks also
have the capacity to handle the high-bandwidth needs.
 Safety and Security
 Schools can also monitor security cameras and keep
all personnel in constant communication in emergency
situations.

Let’s talk about Applications of
WMNs… [2/2]
 Healthcare
Wireless mesh nodes can send signals short distances to
ensure access in every operating room, lab and office.
 The ability to connect to the network is crucial as
more doctors and caregivers maintain and update
patient information on portable electronic devices carried
from room to room.
 Hospitality
 Wireless mesh networks are quick and easy to set up
indoors and outdoors without having to remodel existing
structures or disrupt business.
 Warehouses
There is simply no effective way to keep track of stock
and shipping logistics without the types of Ethernet-
enabled handheld scanners used in modern warehouses.
 Wireless mesh networks can ensure connectivity
throughout a huge warehouse structure with little effort.

The future of the WMNs
applications?
 The U.S. military, which helped develop wireless mesh
technology, foresees a day when thousands of
microchip-size mesh nodes can be dropped onto a
battlefield to set up instant scouting and surveillance
networks. Information can be routed to both ground
troops and headquarter personnel.
 Carmakers and telecom companies are working to
develop Intelligent Transport Systems (ITS)
powered by street and highway-based wireless mesh
networks. Using an automated network of surveillance
cameras and in-car sensors, public safety officials can
tightly monitor traffic accidents and dangerous road
conditions.
 PC Magazine reports that there's even technology which
promise upgrades for in-car entertainment options
like digital music and movie downloads.

Conclusion
 The Internet: The Original Mesh Network
“The Internet is the world's largest mesh network.
Information travels across the Internet by being
bounced automatically from one router to the next until
it reaches its destination. The Internet is often depicted
as a "cloud" or "web" of connectivity because of the
billions of potential paths across which data can travel.”
Case Studies
 Afrimesh, Simple & Easy dashboard for network
management of wireless mesh networks for rural Africa.
 Patmos, the first Greek Wireless Mess networked island
with hot zones and hotspots by Nortel company.