Transcript bhoot pres1

Wide Area Wi-Fi
Sam Bhoot
Wide Area Wi-Fi
 Definition: Wi-Fi (Wireless Fidelity) n. – popular term
for high frequency wireless local area networks
operating on the 802.11 standard.
 Problem: Local Area Network
 Question: How to extend this to Wide Area Network?
Wide Area Wi-Fi
 Solution 1 - Mesh Networks:
 Multi-hop systems in which devices assist each
other in transmitting packets through the network.
 Created using a series of special 802.11b access
points (Mesh AP’s) that create a single, scalable
wireless network.
Wide Area Wi-Fi
 Mesh Networks:
 A Mesh AP can send and receive messages and also
functions as a router that can relay messages for its
neighbors.
 Through the relaying process, data will find its way to
its destination, passing through intermediate Mesh
AP’s.
Wide Area Wi-Fi
 Mesh Networks:
 A mesh network offers multiple redundant
communications paths throughout the network.
 If one link fails for any reason, the network
automatically routes messages through alternate
paths.
Wide Area Wi-Fi
 Mesh Networks:
 Advantages
 Low power transmissions to reach nearby nodes
so less interference with radio signals from other
nodes. The network is able to benefit from channel
reuse, resulting in improved spatial capacity.
 Traffic balancing by dynamically routing traffic
around a congested node.
 Less broadband connections required.
Wide Area Wi-Fi
 Mesh Networks:
 Disadvantages
 Deriving an optimum routing protocol to minimize
the number of hops. Dynamic networks eat up
bandwidth updating the nodes of the topology.
 Ensuring security of packets transmitted from an
outside agent stealing bandwidth.
 Significantly lowers the capacity of the Wi-Fi
network.
Wide Area Wi-Fi
 Mesh Networks:
 Main Problem:
 How to assign IP addresses to mesh nodes?
 Solution is to use IPv6 but still impractical.
 Use 10.x.x.x numbers and go through and use
NAT.
 Home Clients will have to go through two NATs.
 Leads to complicated issues with proper
routing.
Wide Area Wi-Fi
 Solution 2 - Repeater / Router:
 Software that creates meshes instead of a
hierarchical wireless LAN.
 The software loads on the wireless adapter card and
turns every adapter into a repeater-router, instead of
an endpoint looking for an access point.
Wide Area Wi-Fi
 Repeater / Router:
 End results
 Wireless LAN can extend wherever mesh clients
exist.
 Since users connect to nearest WLAN device
instead of distant AP, throughput will be maximum.
 Software being developed by MeshNetworks,
SkyPilot, Ember, and CoWave Networks.
Wide Area Wi-Fi
 Future of Wide Area Networking:
 802.16 Wireless MAN
 Feasible backhaul for connecting Wi-Fi Hotspots
together.
 Base-stations similar to cellular costing about $20k
each serving 60 customers with T1 speed
connections.
 Operates in the 10-66 GHz range with data rates
of up to 120 Mbps.