Upload
cicada
View
42
Download
1
Embed Size (px)
DESCRIPTION
MERLIN: A Synergetic Integration of MAC and Routing for Distributed Sensor Networks. A.G.Ruzzelli, M.J.O ’ Grady, R.Tynan, G.M.P.O ’ Hare. Adaptive Information Cluster project (AIC) and Smart Media Institute (SMI) Department of Computer Science University College Dublin Ireland. - PowerPoint PPT Presentation
Citation preview
http://www.cs.ucd.ie/students/aruzzelli/homeMERLIN: Integrating energy-efficient MAC and Routing
MERLIN: A Synergetic Integration of MAC and Routing for Distributed Sensor Networks
A.G.Ruzzelli, M.J.O’Grady, R.Tynan, G.M.P.O’Hare.
Adaptive Information Cluster project (AIC) and
Smart Media Institute (SMI)
Department of Computer ScienceUniversity College Dublin
Ireland.http://www.adaptiveinformation.ie
http://www.cs.ucd.ie/students/aruzzelli/homeMERLIN: Integrating energy-efficient MAC and Routing
Summary
• Overview of WNSs and protocols
• Motivation
• Phase1: MERLIN design– Motivation and objectives– Fundamental concept– MAC details – Routing details
• Phase2: Simulation and results– Scheduling performance – Comparison against SMAC+ESR
• Conclusion
http://www.cs.ucd.ie/students/aruzzelli/homeMERLIN: Integrating energy-efficient MAC and Routing
Sensor network characteristics
• Energy consumption: primary objective
• The wake-up concept
• Very low duty cycle (even less than 5%)
• Small packets smaller than in ad-hoc networks (e.g. temperature data is few bytes)
• Low data traffic per node
http://www.cs.ucd.ie/students/aruzzelli/homeMERLIN: Integrating energy-efficient MAC and Routing
Communication reliability: Nodes are prone to fail and bad channel condition might affect the transmission
Scalability: Medium Access control should be able to deal with large scale networks
Unique global addressing:
Low processing capability
High end-to-end latency of packets
Important issues of protocols for WSNs
http://www.cs.ucd.ie/students/aruzzelli/homeMERLIN: Integrating energy-efficient MAC and Routing
What does MERLIN address?Energy-efficiency
• by an adaptive node activity scheduling
End-to-end latency reduction • Separate MAC and Routing layers in low duty-cycle multi-hop networks cause
an extremely high latency – (e.g. SMAC +DSR at 5% duty >35s delay for packets of 10 hops away
nodes )
Communication reliability • failure, interference, depletion, mobility Addressing a single node can
result in high error probability
Node-to-Gateway routing
Protocol generality
Initial idea presented at IWWAN04: A.G. Ruzzelli, Evers, Dulman, Van Hoesel, Havinga. “ On the design of an energy-efficient low-latency integrated protocol for Wireless Sensor networks"
What MERLIN does NOT address:•Node-to-node routing located at several hop distance
http://www.cs.ucd.ie/students/aruzzelli/homeMERLIN: Integrating energy-efficient MAC and Routing
Design goals
•MAC+Routing integration into a simple architecture;
•No usage of handshake mechanisms;
•No specific node addressing;
•Reduce latency while ensuring a very low energy consumption
•Increasing communication reliability while limiting packet overhead;
http://www.cs.ucd.ie/students/aruzzelli/homeMERLIN: Integrating energy-efficient MAC and Routing
Initial idea: Timezone division
Gateway
Node
(European EYES project, NL)
Nodes with the same color are in the same time zone
Every node sets its zone and forward the sync packet to more distant nodes.
A node division both in time and space is generated, i.e. timezone
http://www.cs.ucd.ie/students/aruzzelli/homeMERLIN: Integrating energy-efficient MAC and Routing
Division of the network in timezones
Nodes report to the closest gateway
Nodes within the same zone wake up, transmit and go into sleep simultaneously
http://www.cs.ucd.ie/students/aruzzelli/homeMERLIN: Integrating energy-efficient MAC and Routing
Timezone data traffic
Upstream multicast: Packets are forwarded to lower zones
Zone 2
Zone 3
Zone 1
Downstream multicast: Packets transmitted to higher zones
Local broadcast: Packets reach all neighbours. No forwarding performed
Sleeping
http://www.cs.ucd.ie/students/aruzzelli/homeMERLIN: Integrating energy-efficient MAC and Routing
Global allocation
Zone 1
Zone 2
Zone 3
Zone 4
Zone 5
Zone 6
Zone 7
Zone 8
Frame Frame
Frame
The allocation of further zones can be obtained by appending the same table.
The allocation of further frames is obtained by flanking the same table.
http://www.cs.ucd.ie/students/aruzzelli/homeMERLIN: Integrating energy-efficient MAC and Routing
Accessing the table
Nodes in the same timezone contend the slot for local broadcast only once each 4 frametimes
If Mod(FRAME#, NZONE) = Mod(myZone,NZONE)
To access the current slot in the table:
SLOT# = GlobalTime/SLOTTIMEcurrentSlot = Mod(SLOT#, NSLOT)
NZONE = 4NSLOT =9
http://www.cs.ucd.ie/students/aruzzelli/homeMERLIN: Integrating energy-efficient MAC and Routing
Recall that • Nodes in the same zone share the same slot for activity• transmission in MERLIN (multicast) do not address a specific receiving
node
How can simultaneous transmission be handled?How can correct/incorrect receptions be notified?
Intra-zone MAC features
Zone N
Zone N+1
Zone N-1
http://www.cs.ucd.ie/students/aruzzelli/homeMERLIN: Integrating energy-efficient MAC and Routing
Burst tones can help
• Properties– Are signal impulse Do not contain any coded
information– Are robust Several simultaneous burst can still be
identified as one burst– They are shorter that a normal ACK
• Utilization
Multicast: Bursts identify correct receptionsBACK
In transmission to the gateway
Broadcast: Bursts identify reception errorsBNACK
In local broadcast
http://www.cs.ucd.ie/students/aruzzelli/homeMERLIN: Integrating energy-efficient MAC and Routing
Asynchronous transmission Mechanism
Tx1
Tx2
Tx2
Tx1
CCA
Preamble Packet
Preamble Packet
Listen
Sleep
Sleep
Random
Random
Burst*
* burstACK if local broadcast, burst NACK if multicast
CCA
CCA
Sleep
Sleep
Sleep
Listen
Transmit
CCA
CCA
Sleep
Tc
Tc
S l o t l e n g t h
Tc
Tx1
Tx2
Rx1
Rx1 Rx1
CCAListen SleepSleep
Rx2
Burst*
Rx2Rx2
http://www.cs.ucd.ie/students/aruzzelli/homeMERLIN: Integrating energy-efficient MAC and Routing
Disadvantages
1)MERLIN does not address a specific receiving node
multiple copy of the same msg sent can be generated
increase overhead!
2) Some collisions due to the Hidden Terminal Problem (HTP)
Zone 1 Zone 2Zone 3
Zone 4Zone 5
A
B
Zone 3
A
B
?
http://www.cs.ucd.ie/students/aruzzelli/homeMERLIN: Integrating energy-efficient MAC and Routing
Routing characteristics (I)
• 3 small buffers of upstream, downstream and local broadcast are provided
• Packets organised in multiple msgs of the same data traffic type;
• Packets contain a msg-ID index of included msgs;
• Nodes, which lose the contention, keep on listening to the beginning of the transmitted packet then go into sleep;
• Nodes discard from their buffer the msgs already fowarded.
Pro : Reduce overhead in transmission!
Con : Small increase of node activity;
Increase complexity.
Channel contention
messagesMsg-index
Discard msgs already forwarded from their queue
P a c k e t
Listen to the packet index
Controlled multipath
http://www.cs.ucd.ie/students/aruzzelli/homeMERLIN: Integrating energy-efficient MAC and Routing
Routing characteristics (II)
Timezone maintenance• Timezone update are sent periodically;
• Failed reception of timezone update from zone N-1 node to zone N node triggers a upstream multicast of Timezone Update request (TUR)
– N-1 node/s reply Connection reestablished
• N-1 failed local broadcast TUR– At least one reply change of zoen to N+1
• N failed downstream broadcast TUR
1
23
3
4
2
4
1
3
4
2
TUR
1
3
4
2
TUR
1
3
4
2
6
5
http://www.cs.ucd.ie/students/aruzzelli/homeMERLIN: Integrating energy-efficient MAC and Routing
Assessment
Simulation tool: OmNet++
Framework: EU EYES project
Evaluation against SMAC+ESR
In Progress:
Philips Sand node implementation
http://www.cs.ucd.ie/students/aruzzelli/homeMERLIN: Integrating energy-efficient MAC and Routing
Scenario and Setup•Scenarios
•5 nodes two-hops
•70 nodes Random multihop
•Metrics:•Energy consumption per RX packet •Network lifetime•E-to-E latency•Total packet overhead•% sleeping time
•Parameters:•Duty cycle (acting on CW and frametime size)•Low traffic conditions (12 packet/min)•High traffic conditions (60 packet/min)
Sources
Forwarder
Destinations
http://www.cs.ucd.ie/students/aruzzelli/homeMERLIN: Integrating energy-efficient MAC and Routing
Low traffic 2-hops scenario
http://www.cs.ucd.ie/students/aruzzelli/homeMERLIN: Integrating energy-efficient MAC and Routing
High traffic 2-hops scenario
http://www.cs.ucd.ie/students/aruzzelli/homeMERLIN: Integrating energy-efficient MAC and Routing
Multihop scenario: Lifetime
Note: These graphs have little relevance if not related to the EtoE latency
http://www.cs.ucd.ie/students/aruzzelli/homeMERLIN: Integrating energy-efficient MAC and Routing
Multihop scenario: Latency/energy
Given a certain sustainable latency, MERLIN consumes between 2 and 2.5 times less energy than SMAC+ESR
http://www.cs.ucd.ie/students/aruzzelli/homeMERLIN: Integrating energy-efficient MAC and Routing
Total packet overhead
The MAC routing integrated nature MERLIN results in a smaller packet overhead than SMAC+ ESR.
http://www.cs.ucd.ie/students/aruzzelli/homeMERLIN: Integrating energy-efficient MAC and Routing
Conclusion
• Description and simulated results of MERLIN have been presented;
• MERLIN is suitable for large scale sensor networks with energy consumption as main goal;
• MERLIN is suitable for communication to a from the gateway
• The multicast mechanism with burst ACK showed large improvement on the communication reliability
• The integrated nature and the absence of handshake mechanisms help reducing the EtoE packet delay
• EtoE delay can be traded-off for a longer network lifetime Results showed lifetime being extended by a factor of 2.5 of MERLIN with respect to SMAC
http://www.cs.ucd.ie/students/aruzzelli/homeMERLIN: Integrating energy-efficient MAC and Routing
Thank you for your kind attention