“Wireless Mesh Networks”

Πανεπιστήμιο Μακεδονίας, Τμήμα Διοίκησης Τεχνολογίας

Μάθημα: Ασύρματες ΤηλεπικοινωνίεςΔιδάσκων: 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:1. Infrastructure wireless mesh networks: Mesh

routers form an infrastructure for clients. 2. Client wireless mesh networks: Client nodes

constitute the actual network to perform routing and configuration functionalities.

3. 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]

HealthcareWireless 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.

WarehousesThere 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?1. 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.

2. 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.

3. 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.