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PRMAC: Pipelined Routing Enhanced MAC Protocol for Wireless Sensor Networks. Turkmen Canli ± and Ashfaq Khokhar * Electrical and Computer Engineering Department ± Computer Science Department* The University of Illinois at Chicago IEEE ICC 2009. Outline. Introduction RMAC PRMAC
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PRMAC: Pipelined Routing Enhanced MAC Protocol for Wireless Sensor Networks Turkmen Canli± and AshfaqKhokhar* Electrical and Computer Engineering Department± Computer Science Department* The University of Illinois at Chicago IEEE ICC 2009
Outline • Introduction • RMAC • PRMAC • Performance • Conclusion
Introduction • Duty cycling • Is widely used in design MAC protocols in WSNs • To mitigate this energy consumption of idle listening • One-hop • S-MAC • Multi-hop • RMAC • PRMAC
Related work • RMAC ( routing enhanced MAC protocol) • INFOCOM 2007
RMAC S A B C RTS PION Final = C Next = A Prev = Null
RMAC S A B C CTS RTS PION Final = C Next = B Prev = S
RMAC DATA S A B C DATA DATA DATA PION PION
RMAC DATA DATA S A B C D DATA CTS RTS RTS The DATA will be buffered PION Final = C Next = A Prev = Null PION Final = C Next = B Prev = S
Drawbacks of RMAC • In the sleep period, single data packet is transmitted over multiple hops within one cycle. However, the protocol require new flow set up for every data packet • If intermediate nodes in the flow have packets for the final destination of the flow, RMAC sets up new flow for all these packets
PRMAC PION PRMAC: 1 operational cycle and 4 PION packets RMAC: 3 operational cycles and 11 PION packets
PRMAC DATA Period PION
PRMAC DATA Period • Two new fields, packetsToRecv and packetsToSend, have been added to the RMAC’s PION packet • In the PION packet at the ith hop, these fields have the following meaning: • i. packetsToSend is the number of packets node si is planning to send to node d. • ii. packetsToRecv is the number of packets node si can receive from node s(i-1) . i-1 i d packetsToRecv packetsToSend
PRMAC DATA Period i-1 i i+1 d PION node s(i-1) asks si if it can receive N data packets
PRMAC DATA Period i-1 i i+1 d PION node si replies to node s(i-1) that it can only receive N - xdata packets node si asks s(i+1) if it can receive M data packets M = N – x + y
PRMAC Tp • The maximum number of hops between node Y and node Bis • The communication latency, u, between any two nodes is computed as follows: x x x 1th ACK 2th ACK :Interference Range r :Communication Range
PRMAC Network Allocation Vector (NAV) • NAV policy for nodes overhearing a PION packet that are neither previous nor next hop nodes • It reserves 3 time segments, for the confirmation of PION, data, and ACK segments
PRMAC Network Allocation Vector (NAV) • Confirmation of PION packets: • This time segment is reserved to prevent collisions during the reception of flow set up confirmation • Assuming transmission of ith PION packet ends at time Ti • Any node that overhears this ith PION packet, reserves time segment given by equation : Ti
PRMAC Network Allocation Vector (NAV) • NAV Data Segments • Assuming node B is ith node in the flow and it is going to receive N data packets • time segment corresponding to jth data packet, TS(j), where , is given as follows:
PRMAC Network Allocation Vector (NAV) • ACK Segments: • packetsToSend (M) field of the PION packet includes the number of the data packets node B is expected to send • Assuming node B is the ith hop node in the PION transmission, all ACK time segments for should be reserved
PRMAC Data Transmission • NRXand NTX do not have to be equal and if NRXis bigger than NTX, NRX - NTX packets will be buffered • Assume that node Bis the ith hop node in the PION transmission. In order to receive jth data packet
PRMAC Data Transmission • Bneeds to wake up at : • When : • When : sleep at
Performance • ns-2 • 200 node randomly connected network • selected 5 different source and destination node pairs and set up traffic flows
Normalized delay • Fig. 6 shows the end to end delay for chain scenario, normalized with respect to average end to end delay of RMAC
Conclusion • We have presented PRMAC, a cross layer optimization based pipelined routing enhanced MAC protocol for wireless sensor networks • Depending on traffic load, PRMAC can schedule multihop transmission of multiple packets