on detecting termination in cognitive radio networks

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

2

Outline

• Introduction

• Problem Statement and Our Contribution

• T-CRAN Protocol

• An Example

• Conclusion

3

• 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

6

• 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

9

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

25

An ExampleFirst consider without the appearance of a PU

Credit dist

ributio

n

26

An ExampleFirst consider without the appearance of a PU

Credit surre

nder by 5

27

An ExampleFirst consider without the appearance of a PU

Credit surre

nder by 3

28

An ExampleFirst consider without the appearance of a PU

Credit surre

nder by 6

29

An ExampleFirst consider without the appearance of a PU

Credit surre

nder by 4

30

An ExampleFirst consider without the appearance of a PU

Credit

surre

nder by

the ro

ot node

31

An ExampleNow consider the presence of a PU

32

An ExampleNow consider the presence of a PU

33

An ExampleNow consider the presence of a PU

34

An ExampleNow consider the presence of a PU

35

Outline

• Introduction

• Problem Statement and Our Contribution

• T-CRAN Protocol

• An Example

• Conclusion

36

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

to_shantanusharma@ieee.org2 Department of Computer Engineering, National Institute of

Technology Kurukshetra, Indiaaksinreck@ieee.org

Presentation is available athttp://www.cs.bgu.ac.il/~sharmas/

publication.html