distributed algorithms in multi-channel wireless ad hoc networks under the sinr model
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Distributed Algorithms in Multi-channel Wireless Ad Hoc Networks under the SINR Model. Dongxiao Yu Department of Computer Science The University of Hong Kong. *. Wireless Ad Hoc Networks. Application Scenarios Data gathering Monitoring, Surveillance Disaster relief Medical Applications - PowerPoint PPT PresentationTRANSCRIPT
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Distributed Algorithms in Multi-channel Wireless Ad Hoc Networks under the SINR Model
Dongxiao Yu
Department of Computer Science
The University of Hong Kong
Wireless Ad Hoc Networks
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Application Scenarios– Data gathering– Monitoring, Surveillance– Disaster relief– Medical Applications– Many others
Wireless Ad Hoc Network
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• Composed by autonomous devices (nodes)
No built-in infrastructure
Communicate on shared channels
-- collisions, interference, …
Limited hardware capability
Little knowledge on network
Asynchronous deployment
Mobility
SINR-style Models
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Signal-to-Noise-plus-Interference Ratio model Message arrives if SINR is larger than β at the receiver
Problems Studied under SINR Model
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Problems Studied
-- Dominating set
-- Local broadcast
-- Broadcast and Multiple-message broadcast
-- Data aggregation and collection
-- Capacity and link scheduling
-- Connectivity
-- Coloring
-- Many others
• Most Work are done in single-channel networks
Motivation
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• Wireless devices can now operate on multiple channels -- Devices using the 802.11 standard have access to around a dozen
channels
-- Devices using the Bluetooth standard have access to around 75
Motivation
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• Under the graph-based model
-- Symmetry breaking problems, such as leader election wake-up maximal independent set connected dominating set -- Communication problems, such as broadcast and multiple-message broadcast
• Largely unexplored how to leverage the utilization of multiple channels to speed up communications, especially under the SINR model
Communication Model
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• n nodes are arbitrarily placed on the plane
• Multi-hop
• Synchronous communications
• No collision detection and physical carrier sensing
• Interference Model: SINR
• F channels
--In each round, a node selects one channel to operate on: transmit or
listen
--Learns nothing about events on other channels
Challenges
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• Intuitively, it might think that F channels can always speed up communication for F times
• This is not easy -- In each round, each node can only operate on one channel
• For some problems, e.g., multi-hop wake up, multiple channels can not help giving faster algorithms even in the UDG model
Information Exchange
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Given a network with n nodes,•Each node initially holds a distinct information packet•Each node then tries to send its packet to all nodes within a given
range R•Objective: minimize the time of accomplishing the information
exchange task, over all network topologies•A building block for many upper-layer applications
-- Information broadcast
-- Routing
-- Network topology learning
-- Many others…
Main Result
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• A randomized algorithm accomplishing information exchange in
O((Δ/F+Δlogn/P)logn+log2n) rounds with high probability
-- P is the bound on the number of packets in a message
Node Coloring
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Given a network with n nodes and a distance parameter R,
•The node coloring problem is color all nodes such that any pair of
nodes within distance R are assigned different colors
•Objective: minimize the number of colors and the time of the coloring
process
•In theory, one of the most basic symmetry breaking problem in
distributed computing
•In practice, abstract MAC protocol design, such as TDMA and FDMA
Main Result
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•A randomized algorithm properly coloring all nodes using O(Δ) colors
in O(Δlogn/F+polylog n) rounds with high probability
•Comparing to the best O(Δlog n+log2n) result in single-channel
networks
Future Work
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• Consider more fundamental problems in multi-channel networks, e.g.,
broadcast and multiple-message broadcast
• Consider lower bound
• Consider deterministic algorithms
• Consider multi-channel models with harsher restrictions, such as
unreliable channels, asynchronous communications
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Thank You!