Wireless mesh networkk routing

Scenario based analysis of WMN routing protocols
Major Project
ChiragHeda
Abhishek Kona

Wireless Mesh Networks
Cheap alternative to provide internet access in offices, public space
Mesh Networking suite made available by default in One Laptop Per Child (OLPC) project
Robust Networks
Integration with existing networks

Difference between Mesh and Ad-hoc networks
Ad-hoc networks
A wireless ad hoc network is a decentralized wireless network. Each node is willing to forward data for other nodes, and so the determination of which nodes forward data is made dynamically based on the network connectivity
Traffic flows between an arbitrary pair of nodes.
Mesh networks
Type of Ad-hoc network
Traffic pattern to or from a gateway

Ad-hoc networks
Ad hoc clients are generally user to user and not fixed to any kind of infrastructure.
Mesh Networks
Clients on mesh networks are dedicated to the role of routing by relying on an infrastructure of sorts

Mesh Routing Protocols - Types
Pro-active (table driven)
Characterized by proactive checking of link state and updating of routing tables
High complexity and CPU load.
High performance-Low response time
Eg – OSPF,OLSR,MMRP, HSLS
Reactive (On-Demand)
Passive reacting on detection problems (non-working routes)
Less demanding on CPU.
Less performing-Increased response time
Eg - AODV

Factors to look for in WMN routing
Route Load Balancing
Average hop count of routes
Lossy or lossless routes
Avoidance of long hops
Effect of interference (under study)

Popular WMN routing protocols
AODV
Mobile Mesh
OSPF
HWMP
B.A.T.M.A.N
Some effective protocols are proreitery
Locust World
4G Mesh Cube
Ad Hoc routing protocols extended to WMNs

Ad hoc On Demand Distance Vector (AODV)
Developed for ad hoc networks
On demand algorithm
Deployed in OLPC router
Reactive protocol
DYMO (Dynamic On-demand MANET routing protocol) based on AODV is current research focus

Mobile Mesh
3 separate protocols for specific functions
Link Discovery - Mobile Mesh Link Discovery Protocol (MMLDP)
Routing – Mobile Mesh Routing Protocol
Border Discovery – Mobile Mesh Border Dicovery protocol

Mobile Mesh MMRP
Builds least cost path between source and destination
Sends "Link State Packet" (LSP) contains information - unique router ids and costs
Nodes can advertise routes, for routes having external broadband connection can advertise default routes
Scalable, fish eye technique used to reduce flooding of network due to LSP
Open source. Implementation available for Linux kernel

Open Shortest Path First (OSPF)
Pro-active
Metrics used to implement in WMNs
ETX-Estimated Time Count metric
Airtime as a metric
Common implementation available, implementations with metrics not available
Shortest path tree for each route is generated
Sends Link State Advertisements (LSA) to all routers
ETX uses no of packets lost on a route to compare routes
Current research on finding new metrics for OSPF in WMNs

B.A.T.M.A.N(better approach to mobile ad-hoc networking)
Inspired by OSLR protocol
Each node perceives and maintains only the information about the best next hop towards all other nodes
OGM (Originator Messages) are sent in network in selective flooding manner
Global knowledge about local topology changes becomes unnecessary
Deployed in many WMNs (MIT Roof Net project)

Hybrid Wireless Mesh Protocol (HWMP)
Protocol of choice of IEEE 802.16s WMN
Different channels established
One single control channel established
Under development, only propriety implementations available
Requires 802.16s capable NICs
Cross layer interaction in routing

References
B.A.T.M.A.N http://www.openmesh.org/wiki/BATMANConcept
A Secure Hybrid Wireless Mesh Protocol for 802.11s Mesh Network by Md. Shariful Islam Young Jig Yoon Md. Abdul HamidChoongSeon Hong
Routing in Wireless Mesh Networks using OSPF based Airtime Metric by Chandan K Reddy, Tara P Choudhury
Routing Packets into Wireless Mesh Networks by Rainer Baumann,Simon Heimlicher, Vincent Lenders, Martin May