Asynchronous Channel Hopping for Establishing Rendezvous in Cognitive Radio Networks Kaigui Bian and Jung-Min “Jerry” Park Department of Electrical and.

Asynchronous Channel Hopping for Establishing Rendezvous in Cognitive

Radio Networks

Kaigui Bian and Jung-Min “Jerry” Park

Department of Electrical and Computer EngineeringVirginia Tech

{kgbian, jungmin}@vt.edu

April 11, 2011Shanghai, China

1

IEEE INFOCOM 2011 Mini-conference

ECE 5560, Fall 2006

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Outline

Cognitive Radio (CR) Networks

The Rendezvous Problem in CR Networks

Rendezvous Protocol using Asynchronous Channel Hopping (ACH)

Performance Evaluation

Conclusion

ECE 5560, Fall 2006

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Static Frequency Allocation3

Source: D. Staelin, April 2010.

Broadcast TV470-806 MHz

ZigBee 802.15.4ISM (915 MHz)

Wi-Fi, BlueTooth,Zigbee

ISM (2.4 GHz)

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Opportunistic Spectrum Sharing (OSS) Paradigm

Unused TV bands (around 700 MHz in U.S.) = TV white space (TVWS) Cognitive Radio (CR) is an enabling technique for realizing OSS. Unlicensed (secondary) users cause NO interference to licensed

(incumbent or primary) users.

4

TV white space

Over-crowded unlicensed bands

Under-utilized licensed (TV) bands

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Outline





Conclusion

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The Rendezvous Problem

Rendezvous = control channel Needed for link setup, control information exchange, etc

In OSS, vacate any licensed channel where primary users appear. Multiple rendezvous = robustness of rendezvous

6

SERIAL ETHERNET

Ch 2

Ch 1

Ch 0

Control Data

SERIAL ETHERNET

Control Data

Vacate control channel

6

Licensedbands

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Outline





Conclusion

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Channel hopping (CH) can create rendezvous.

Multiple rendezvous channels per node pair Robust to link breakage caused by primary users

Bound for time-to-rendezvous (TTR) Small channel access delay

Independence of clock synchronization

8

Requirements for CH-based Rendezvous Protocols

88

C1 C2C0

C1 C2 C0

C1C2 C0

C1

C1

C1

C1 C2 C0

C1C2 C0

C1 C2C0

C2

C2

C2

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Random channel hopping: no TTR bound

Common channel hopping: clock syn.

Sequence-based channel hopping (Dyspan08): single rend.

9

Related Work on CH-based Rendezvous Protocols9

C1 C2C0 C1 C2C0 C1 C2C0

C1 C2C0 C1 C2C0 C1 C2C0

9

C1 C2C0

C1 C2 C0

C1 C2 C0

C1C2 C0

…...

…...

C1 C2C0 C1 C2C0 C1 C2C0C0 C1 C2

C1 C2C0 C1 C2C0 C1 C2C0C0 C1 C2

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C1 C1 C1 C0C0C0C2 C2C2

C1 C1 C1 C0C0C0C2 C2C2

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Optimal Asynchronous CH System (1)

Optimal asyn. CH scheme Max # of rend. channels, N Min sequence period, N2 slots No clock syn.

An array-based design Assumption of the Tx/Rx role

Tx and Rx use different methods Not applicable to ad hoc networks

C1 C2 C1 C1C0 C0 C0C2 C2 C1 C2 C1 C1C0 C0 C0C2 C2

10

Tx: column-based CH seq.

Rx: row-based CH seq.

0 1 2

3 4 5

6 7 8

N = 3, U = {0, 1, …, 8}

row = {0, 1, 2}

column = {1, 4, 7}

Column-wise assignment

Row-wise assignment

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Every node has a unique ID ID seq.: a = {a1,a2} Bit seq.: A = a + {0,0} + {1,1}

Two nodes are able to generate two distinct bit sequences. If a ≠ b Then A ≠ Shift (B, k)

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ID

+

ID extended to Bit seq.

A

B

A

B

A

B

“0” only seq.+“1” only seq.

ECE 5560, Fall 2006

Bit seq B = b + {0, 0} + {1, 1}= {1, 1, 0, 0, 1, 1}

Bit seq A = a + {0, 0} + {1, 1}= {1, 0, 0, 0, 1, 1}

12


Bit seq. extended to CH seq. A = {1, 0, 0, 0, 1, 1} B = {1, 1, 0, 0, 1, 1}

Every node uses the same method: Bit “1” two column-based CH seqs. Bit “0” two row-based CH seqs.

N rend. channels achieved within O(N2) slots. TTR bounded by N

12

Column-based CH seq.

u

Row-based CH seq.

v

ANode 1’s CH seq.

BNode 2’s CH seq.

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Outline





Conclusion

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Comparisons of CH Schemes14

# of rend. channels

Mean TTR

Bounded TTR

Asyn.operation

Common CH N O(1) Yes No

Random CH N O(N) No Yes

Seq.-based Rend

1 O(N2) Yes Yes

Asyn QCH 2 O(1) Yes Yes

Optimal Asyn. CH

N O(N) Yes Yes

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Simulation Results

Comparisons of asyn. CH protocols using network simulation in NS-2 Primary users occupy X < N channels at random

RCH (random CH): N rend. channels possible Optimal Asyn. CH: N rend. channels guaranteed SR (sequence-based rendezvous): 1 rend. channel

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Outline





Conclusion

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Conclusion

Addressed the rendezvous problem in MAC protocol design for CR networks

An array-based CH systems for rendezvous (control channel) establishment Robustness: max number of rend. channels Bounded time-to-rendezvous (TTR) Asynchronous rendezvous

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Questions?Thank you

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Backup Slides

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Coexistence Problem

Horizontal coexistence among unlicensed networks that have equal priority to access spectrum.

Vertical coexistence among networks that have different priorities to access spectrum.

1919

Heterogeneouscoexistence

Homogeneous or self coexistence

Horizontal coexistence

Verticalcoexistence

Coexistence

Incumbentcoexistence

TV band licensed users vs. unlicensed users

WiFi vs. BlueTooth vs. Zigbee

Cellular vs. Cellular

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Other Applications of Multiple Rendezvous CH Schemes

Jamming resistant rendezvous Attack model: a jammer randomly picks X out of N

channels to launch the jamming attack The maximized number of pair-wise rendezvous channels

guarantees the maximized jamming resistance.

SERIAL ETHERNET

Which channel to rendezvous given N

channels ?

Jammer on X channels

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Asynchronous Channel Hopping for Establishing Rendezvous in Cognitive Radio Networks Kaigui Bian and Jung-Min “Jerry” Park Department of Electrical and.

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