1. Enhancement of Receiver-initiated Packet Train Protocol with Slotted Random Access for Underwater Acoustic Networks Nuttarit Leelapisut 1, Nitthita Chirdchoo 2, Muhammad Saadi 1, Lunchakorn Wuttisittikulkij 1 1. Department of Electrical Engineering, Faculty of Engineering, Chulalongkorn University 2. Sensor Network and Embedded System Research Unit, Nakhon Pathom Rajabhat University

2. Outline  Introduction  Protocol Design  Simulation & Results  Summary 2

3. Introduction Why Underwater? ▫ The ocean covers 71% of the Earth's surface and contains 97% of the planet's water. ▫ more than 95% of the underwater world remains unexplored. Example of Application in underwater ▫ Pollution monitoring ▫ Offshore exploration ▫ Oceanographic data collection 3

4. Underwater Communication Characteristics Most underwater sensor networks are based on acoustic waves. ▫ Propagation speed  1500m/s  Lead to long propagation delay  0.67s/km ▫ Scarce bandwidth availability  Lead to low datarate  a few kbps ▫ Terrestrial MAC protocols cannot be applied directly to Underwater Acoustic Networks. Example for MAC for Underwater Acoustic Network ▫ MACA-U, RIPT, SF-MAC, CS-MAC, Aloha-AN 4

5. RIPT RIPT was proposed by Chirdchoo et al.(2008) ▫ is handshaking with Receiver-initiated protocol. ▫ with packet train that can send more than one DATA packet in each handshake round. 5

6. RIPT Strong ▫ More effective in term of alleviating the hidden terminal problems. Weakness ▫ Each node must know the inter-node’s propagation delay of all other nodes. ▫ RIPT protocol adapt the frame size of data transmission period according to the number of data packets from the previous handshaking round.  May be not match with current traffic demand  Cause low Throughput 6

7. E-RIPT E-RIPT is from Enhance RIPT Main point of E-RIPT protocol ▫ Use the slotted random access at reservation time.  Reduce the requirement of original RIPT that need to know all inter-node propagation delay ▫ Set frame size after received traffic demand from neighboring node.  Increase channel utilization 7

8. Node Type Beacon node ▫ Process and Control the Slave node(s). ▫ Receive DATA packet(s) from Slave node(s). Slave node ▫ Reserve the data slot which declare from beacon ▫ Send DATA packet to Beacon node Idle node ▫ Node which wait for changing type 8

9. E-RIPT Protocol 9 Nod e 4 Slave Nod e 2 Slave Nod e 1 Beacon Nod e 3 Slave Nod e 5 Slave Nod e 6 Silent t ou t1 REV NTF1 REV-ACK ORDER BROADCAST NTF2 Beacon Slave Silent DATA REV Beacon node ID No reservation Slot NTF1 Time till t out1 REV-ACK Number of packet wish to send Time till t out1 ORDER Time and Number of DATA packet(s) for Slave to send. S all = 4

10. E-RIPT Protocol 10 Nod e 4 Slave Nod e 2 Slave Nod e 1 Beacon Nod e 3 Slave Nod e 5 Slave Nod e 6 Silent t ou t1 t ou t2 t ou t,b t ou t2 REV NTF1 REV-ACK ORDER BROADCAST NTF2 Beacon Slave Silent DATA NTF2 Time till t out2 S all = 4

11. Simulation Model We used open source simulator NS-3, with UAN module. Simulation model is the same as RIPT simulation model. ▫ 36 nodes each node has  8 1-hop neighboring nodes  16 2-hop neighboring nodes ▫ Wraparound ▫ Deviate from intersection point a maximum 10% in x and y direction Datarate = 2400 bps DATA packet length = 2400 bit Grid Spacing = 700m We choose to benchmark our protocol with RIPT and MACA-U 11

12. 12 Result-Throughput S all = No. 1-hop neighboring node

13. Result-Delay 13 S all = No. 1-hop neighboring node

14. Result-Fairness Number of packets sent with offerload per node = 0.503 ▫ RIPT, Mean = 38528.1389, SD = 4922.9368 ▫ E-RIPT S all = 8, Mean = 41608.8056, SD = 3470.5466 ▫ MACA-U, Mean = 18598.6944, SD = 906.4938 14 E-RIPT S all = 8

15. Summary E-RIPT ▫can reduce the requirement of original RIPT by using slotted random access. ▫can decrease the time latency, improve throughput and fairness of original RIPT protocol, if reservation slots are selected carefully. 15

16. Q & A 16

17. Thank you 17