1. INFOCOM 2014

2. What is MMAC? ▣ Multi-Channel MAC  Channel negotiation and assignment (sender – destination pair)  Destination discovery (same channel) and load balancing (exploit all channels) ▣ Multi-Channel Hidden Terminal Problem  If node C is a neighbor of A and B, C defers from transmission for MTU + ACK.

3. What is MMAC? (cont.) ▣ Multi-Channel Exposed Terminal Problem  What If switching to a busy channel in the middle of data transmission? (Suppose B is transimitting data to A and C is transmitting to D)

4. Previous MMAC protocols ▣ Split-phase MMAC ( SP-MMAC )  Time is devided to alternating control and data phases.  During the control phase, all nodes converge to a default channel to negotiate the channel assignment using RTS/CTS.  During the data phase, nodes exchange data on the assigned channels.  Hidden Terminal and extra message overhead avoided. However, low spectural efficiency with high contention conditions due to control phase. ▣ Dedicated Control Channel MMAC ( DCC-MMAC )  Nodes are equipped with 2 radios. One radio is always tuned to a control channel and the other radio switches between the remaining channels for transmissions.  Hidden Terminal avoided. However, higher device cost and low spectural efficiency due to dedicated control channel. (DCC can also be a bottle neck in high-contention scenarios.) ▣ Randezvous MMAC ( MMAC )  Nodes hop between channels using predefined hopping sequences.  Initial discovery is incurred until sender’s and dest’s hop sequences overlap.  No solution for Hidden Terminal Problem.

5. FD-MMAC ▣ Full-Duplex MMAC  First to exploit FD communication(single radio).  Nodes independently switch to idle channels by tracking the state of each channel. (w/o exchange of control messages)  Common synchronized time-slotted system. (GPS)  Physical Layer Technique (SIS, EVM, RSS, Signal correlation)

6. Full-Duplex in a channel ▣ Cross correlation technique (SIGCOMM’08)  Nodes can apply signal correlation techniques for detecting transmission of known bit patterns. Common in frame detection even in the presence of collisions.

7. Review ▣ Multi-channel Transmission  The delay and throughput performance of wireless networks can be significantly improved by accommodating parallel transmissions over orthogonal frequency channels. A BHT ET F E

8. Review (cont.) ▣ Problems - MMAC  Channel negotiation & destination discovery  Load balancing  Multi-channel HT, ET.

9. Full-Duplex in a channel ▣ Cross correlation technique (SIGCOMM’08)  Nodes can apply signal correlation techniques for detecting transmission of known bit patterns. Common in frame detection even in the presence of collisions. A B F E

10. State Classification RSS – Received Signal Strength

11. Hidden & Exposed A BC

12. Destination & Sender State machine

13. Sample Scenarios

14. Experimental Result ▣ Elimination of channel negotiation and VCS + single-channel ET.