on detecting termination in cognitive radio networks
TRANSCRIPT
On Detecting Termination in
Cognitive Radio Networks
Shantanu Sharma1 and Awadhesh Kumar Singh2
1 Ben-Gurion University of the Negev, Israel2 National Institute of Technology, Kurukshetra, India
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Outline
• Introduction
• Problem Statement and Our Contribution
• T-CRAN Protocol
• An Example
• Conclusion
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• Cognitive Radio Networks (CRNs)
– A collection of heterogeneous cognitive radio nodes (or processors), called secondary users
– The cognitive radio nodes (CRs) have sufficient computing power and power backup to operate on multiple heterogeneous channels (or frequency bands) in the absence of the licensed user(s), termed as primary user(s), of the respective bands
– CRs have learning, efficiency, intelligence, reliability, and adaptively capability to scan and operate on different channels
Introduction
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• Available Channel
– A channel that is not currently occupied by a primary user is called an available channel
• Neighboring Nodes
– Any two nodes that are in the transmission range of each other and tuned to a common available channel during an identical time interval
Introduction
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• Termination Detection– A termination detection (TD) protocol is used to
announce termination of a normal computation or an underlying computation
• TD is not a trivial task
• Two properties of a TD protocol– No false termination detection (safety)– Eventual termination detection (liveness)
Introduction
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• Active and Passive nodes– The nodes in the active state are called active
nodes– The nodes in the passive state are called
passive nodes– The active nodes execute an assigned
computation, and usually, after completion of the computation, they become passive
– A passive node can become active on reception of a message from an active node
Introduction
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• Two Types of TD Protocol InitiationDelayed initiation
Introduction
Concurrent initiation
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• Why TD is challenging in CRNs– Network structure and communication links– Reaction to a communication link break– No definitive logical structure
Introduction
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State-of-the-Art• Y.-C. Tseng and C.-C. Tan. Termination detection protocols for
mobile distributed systems. IEEE Trans. Parallel Distrib. Syst., 12(6):558–566, 2001
• H. Kurian, A. Rakshit, and G. Singh. Detecting termination in pervasive sensor networks. In ISADS, pages 323–332, 2009.
• P. Johnson and N. Mittal. A distributed termination detection algorithm for dynamic asynchronous systems. In ICDCS, pages 343–351, 2009
• S. Katiyar and S. Karmakar. A simple scheme for termination detection in delay tolerant networks. In ICCSN, pages 478–482, 2011.
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State-of-the-Art
• Why the existing protocols are unable to work in CRNs
– Existence of an initiator node until termination declaration
– Work on a single pre-decided channel
– Do not consider the presence of some special users (like primary users)
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Outline
• Introduction
• Problem Statement and Our Contribution
• T-CRAN Protocol
• An Example
• Conclusion
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• A termination detection protocol for cognitive radio networks
Problem Statement
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• T-CRAN: Termination detection protocol for Cognitive Radio Networks– Based on credit distribution and aggregation
• Virtual tree-like structure– A node may surrender its credit to any node
(not necessarily to its parent node)– Not mandatory for the initiator of the protocol
to stay involved until the termination of the computation.
Our Contribution
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Outline
• Introduction
• Problem Statement and Our Contribution
• T-CRAN Protocol
• An Example
• Conclusion
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• Credit distribution and aggregation based
• 3-phase protocol
• A node initiates a computation and the T-CRAN protocol2 with a fixed credit value, C, and such a node is called the chief executive node, CE
• CE may distribute the computation among its neighboring nodes, called the child nodes
• When a node finishes its computation, the node’s state becomes passive, and the node surrenders its credit
T-CRAN Protocol
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• Credit Distribution– Step 1: Initiation and distribution of a computation
and the T-CRAN protocol– Step 2: Reception of a COMputation message at a
passive node – Step 3: Reception of COMputation messages at an
active node
T-CRAN: Phase 1
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• Credit Aggregation– Step 4: Credit surrendering by active nodes
• CE can also surrender its credit
• This a beauty of the protocol
– Step 5: Three-way handshake
T-CRAN: Phase 2Virtual tree-like
structureNo need of an identical
root node
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• Termination Detection– Step 6: Termination announcement
T-CRAN: Phase 3
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• Starts concurrently with Phase 1
• The appearance of a PU can be visualized similar to the network partitioning– Primary user(s) affected CRN (CRNP)
– Non-primary user(s) affected CRN (CRNN)
T-CRAN: Primary User Detection
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• Step 7: Node failure due to the appearance of PUs– An affected node, CRj, is detected by all the
neighboring nodes
– All the neighboring nodes of CRj inform CE about such a situation using a PaN message
• Step 8: Recovery of the affected nodes– Once an affected node, CRj, becomes a non-affected
node, CRj informs CE and all its neighboring nodes, whose states are active
– CE first checks whether the computation has terminated
– If not, then CE informs CRj about the ongoing computation (with CRj’s credit value)
T-CRAN: Primary User Detection
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• Strong termination– Passive state of all the CRs + no in-transit message
• Weak termination– Two CRNs, namely CRNP and CRNN + no in-transit
message
• Local termination– Termination of the computation at a node
• Global termination– Termination of the computation at all the nodes.
• We like to have: global weak termination or global strong termination
T-CRAN: Termination Detection
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Outline
• Introduction
• Problem Statement and Our Contribution
• T-CRAN Protocol
• An Example
• Conclusion
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• 6 nodes in the system• Local channel set for every node is given in
Table, where boldface characters show the currently tuned channel at the respective nodes
An Example
Local Channel Sets Nodes
2 ,3 ,5 1
3 ,5 ,6 ,9 2
5 3
5 4
5 ,7 ,9 5
5 ,9 6
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An ExampleFirst consider without the appearance of a PU
Protocol in
itiatio
n
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An ExampleFirst consider without the appearance of a PU
Credit dist
ributio
n
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An ExampleFirst consider without the appearance of a PU
Credit surre
nder by 5
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An ExampleFirst consider without the appearance of a PU
Credit surre
nder by 3
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An ExampleFirst consider without the appearance of a PU
Credit surre
nder by 6
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An ExampleFirst consider without the appearance of a PU
Credit surre
nder by 4
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An ExampleFirst consider without the appearance of a PU
Credit
surre
nder by
the ro
ot node
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An ExampleNow consider the presence of a PU
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An ExampleNow consider the presence of a PU
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An ExampleNow consider the presence of a PU
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An ExampleNow consider the presence of a PU
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Outline
• Introduction
• Problem Statement and Our Contribution
• T-CRAN Protocol
• An Example
• Conclusion
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Conclusion
• T-CRAN Protocol– A termination detection protocol for an asynchronous
multi-hop cognitive radio networks– Based on credit distribution and aggregation approach– Capable enough to work on heterogeneous channels – Can also handle multiple computations simultaneously– Can also be implemented in dynamic networks, e.g.,
cellular, mobile ad hoc networks, and vehicular ad hoc networks
• Virtual tree-like structure– A node may surrender its credit to any node (not
necessarily to its parent node)– Reduces the waiting time to announce termination– Not mandatory for the initiator of the protocol to stay
involved until the termination of the computation
Shantanu Sharma1 and Awadhesh K. Singh2
1 Department of Computer Science, Ben-Gurion University of the Negev, Israel
[email protected] Department of Computer Engineering, National Institute of
Technology Kurukshetra, [email protected]
Presentation is available athttp://www.cs.bgu.ac.il/~sharmas/
publication.html