UNIVERSITY COLLEGE DUBLIN DUBLIN CITY UNIVERSITYSMI || NCSR || CDVP

Advantages of Dual Channel MAC for

Wireless Sensor Networks

Antonio G. Ruzzelli, Gregory O’Hare, Raja Jurdak† and Richard Tynan

School of Informatics and Computer ScienceUniversity College Dublin

Dublin, Ireland{ruzzelli,richard.tynan,gregory.ohare}@ucd.ie

†Bren School of Information and Computer SciencesUniversity of California

Irvine CA 92697rjurdak@ics.uci.edu

UNIVERSITY COLLEGE DUBLIN DUBLIN CITY UNIVERSITYSMI || NCSR || CDVP

Ruzzelli, O’Hare, Jurdak, Tynan

Summary

UNIVERSITY COLLEGE DUBLIN DUBLIN CITY UNIVERSITYSMI || NCSR || CDVP

Ruzzelli, O’Hare, Jurdak, Tynan

Background

• Traditional low cost radios for wireless sensors operate with one frequency channel at any given time

• A profusion of MAC protocols focus on energy efficiency over one frequency channels

UNIVERSITY COLLEGE DUBLIN DUBLIN CITY UNIVERSITYSMI || NCSR || CDVP

Ruzzelli, O’Hare, Jurdak, Tynan

Unique frequency channel issues

• MACs like IEEE802.11, SMAC, TRAMA or BMAC suffer from:– High latency

(e.g. due to RTS/CTS/ACK in CSMA/CA)

– Low flexibility (Difficult to release slots unused in TDMA)

– Inefficient usage of the wireless channel(e.g. the ETP problem in CSMA/CA)

UNIVERSITY COLLEGE DUBLIN DUBLIN CITY UNIVERSITYSMI || NCSR || CDVP

Ruzzelli, O’Hare, Jurdak, Tynan

Advances in WSNs

• Novel transceivers can operate with two channels simultaneously with a relative small increase of energy consumption e.g. nRF2401

Supply current one channel in receive 18 mA

Supply current two channels in receive 23 mA

• nRF2401 is effectively mounted on the motes developed in Cork

UNIVERSITY COLLEGE DUBLIN DUBLIN CITY UNIVERSITYSMI || NCSR || CDVP

Ruzzelli, O’Hare, Jurdak, Tynan

DCMA/AP: Dual channel multiple access with adaptive preamble

• Channel Cd used for data • Channel Cc used for notifications

UNIVERSITY COLLEGE DUBLIN DUBLIN CITY UNIVERSITYSMI || NCSR || CDVP

Ruzzelli, O’Hare, Jurdak, Tynan

DCMA transmission mechanism (1)

Tx long Pa

Transmitter1

Cd

Receiver

Cd

Cc

Cc

CCA

Tx CP

Transmitter2

Cd

Cc

Tc

Tx long Pa

CCA

CCA

L i s t e n

L i s t e n

UNIVERSITY COLLEGE DUBLIN DUBLIN CITY UNIVERSITYSMI || NCSR || CDVP

Ruzzelli, O’Hare, Jurdak, Tynan

DCMA mechanism (2)

UNIVERSITY COLLEGE DUBLIN DUBLIN CITY UNIVERSITYSMI || NCSR || CDVP

Ruzzelli, O’Hare, Jurdak, Tynan

The exposed terminal problem removal

UNIVERSITY COLLEGE DUBLIN DUBLIN CITY UNIVERSITYSMI || NCSR || CDVP

Ruzzelli, O’Hare, Jurdak, Tynan

Adaptive Preamble mechanism

Transm. adaptive Preamble

Transmitter1

Cd

Receiver

Cd

Cc

Cc

CCA

Tx D A T A

Transmitter2

Cd

Cc

Tc

Transm. Adapt. Pr.

CCA

CCA

L i s t e n

L i s t e n

L i s t e n

Tx RIP

Tp

UNIVERSITY COLLEGE DUBLIN DUBLIN CITY UNIVERSITYSMI || NCSR || CDVP

Ruzzelli, O’Hare, Jurdak, Tynan

Opportunistic Crossover mechanism

• During ongoing transmission, the next scheduled RX node is notified through the alternative channel Cc.

TX RX Next RX

Channel Cd Channel Cc

UNIVERSITY COLLEGE DUBLIN DUBLIN CITY UNIVERSITYSMI || NCSR || CDVP

Ruzzelli, O’Hare, Jurdak, Tynan

Related work

UNIVERSITY COLLEGE DUBLIN DUBLIN CITY UNIVERSITYSMI || NCSR || CDVP

Ruzzelli, O’Hare, Jurdak, Tynan

Timing Analysis against BMAC

UNIVERSITY COLLEGE DUBLIN DUBLIN CITY UNIVERSITYSMI || NCSR || CDVP

Ruzzelli, O’Hare, Jurdak, Tynan

Implementation

UNIVERSITY COLLEGE DUBLIN DUBLIN CITY UNIVERSITYSMI || NCSR || CDVP

Ruzzelli, O’Hare, Jurdak, Tynan

Preliminary results

UNIVERSITY COLLEGE DUBLIN DUBLIN CITY UNIVERSITYSMI || NCSR || CDVP

Ruzzelli, O’Hare, Jurdak, Tynan

Future works

UNIVERSITY COLLEGE DUBLIN DUBLIN CITY UNIVERSITYSMI || NCSR || CDVP

Ruzzelli, O’Hare, Jurdak, Tynan

Conclusion