Turkmen Canli ± and Ashfaq Khokhar* Electrical and Computer Engineering Department ± Computer Science Department* The University of Illinois at Chicago IEEE ICC 2009

 Introduction  RMAC  PRMAC  Performance  Conclusion

 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

 RMAC ( routing enhanced MAC protocol ) ◦ INFOCOM 2007

SABC PION Final = C Next = A Prev = Null RTS

SABC PION Final = C Next = B Prev = S RTSCTS

SABC PION DATA

SABC PION Final = C Next = B Prev = S RTSCTS D The DATA will be buffered DATA PION Final = C Next = A Prev = Null RTS DATA

 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

PION PRMAC: 1 operational cycle and 4 PION packets RMAC: 3 operational cycles and 11 PION packets

PION

 Two new fields, packetsToRecv and packetsToSend, have been added to the RMAC’s PION packet  In the PION packet at the i th hop, these fields have the following meaning: ◦ i. packetsToSend is the number of packets node s i is planning to send to node d. ◦ ii. packetsToRecv is the number of packets node s i can receive from node s (i-1). i-1id packetsToRecvpacketsToSend

i-1i PION node s (i-1) asks s i if it can receive N data packets i+1i+1 d

i-1id PION i+1i+1 node s i replies to node s (i-1) that it can only receive N - x data packets node s i asks s (i+1) if it can receive M data packets M = N – x + y

: Interference Range r : Communication Range 1 th ACK 2 th ACK  The maximum number of hops between node Y and node B is  The communication latency, u, between any two nodes is computed as follows: x x x

 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

 Confirmation of PION packets: ◦ This time segment is reserved to prevent collisions during the reception of flow set up confirmation  Assuming transmission of i th PION packet ends at time T i  Any node that overhears this i th PION packet, reserves time segment given by equation : TiTi

 NAV Data Segments  Assuming node B is i th node in the flow and it is going to receive N data packets  time segment corresponding to j th data packet, TS(j), where, is given as follows:

 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 i th hop node in the PION transmission, all ACK time segments for should be reserved

 N RX and N TX do not have to be equal and if N RX is bigger than N TX, N RX - N TX packets will be buffered  Assume that node B is the i th hop node in the PION transmission. In order to receive j th data packet

 B needs to wake up at :  When : sleep at

 ns-2  200 node randomly connected network  selected 5 different source and destination node pairs and set up traffic flows

 Fig. 6 shows the end to end delay for chain scenario, normalized with respect to average end to end delay of RMAC

 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