Due to the broadcast nature and lack of collision detection mechanism, wireless networks suffer from collision. Collision happens when two or more data packets overlap in the time domain at receiver and none of them can be received correctly. Collision increases packet delivery delay, decreases network throughput and incurs extra energy cost because of retransmissions. To tackle collision, researchers propose abundant protocols in Medium Access Control (MAC) layer. The essential idea behind these protocols is to properly coordinate multiple senders to access a shared channel and avoid the case where there are two or more senders accessing a shared channel simultaneously. While in recent years, an increasing number of protocols are invented to approach collision in the physical l...[ Read more ]

Due to the broadcast nature and lack of collision detection mechanism, wireless networks suffer from collision. Collision happens when two or more data packets overlap in the time domain at receiver and none of them can be received correctly. Collision increases packet delivery delay, decreases network throughput and incurs extra energy cost because of retransmissions. To tackle collision, researchers propose abundant protocols in Medium Access Control (MAC) layer. The essential idea behind these protocols is to properly coordinate multiple senders to access a shared channel and avoid the case where there are two or more senders accessing a shared channel simultaneously. While in recent years, an increasing number of protocols are invented to approach collision in the physical layer (PHY). PHY layer demonstrates promising properties, e.g., power indicator like RSSI, the effect of capture and constructive interference, which enable us resolve collision from its nature as wireless signals.

This thesis first draws a new logical roadmap along which we understand and deal with collision. The roadmap is: collision avoidance → collision tolerance → collision cancellation → collision exploitation. We in the beginning avoid collision out of its harm, and then we can just tolerate them with some “powerful weapons”. After that, we try to cancel collision with more powerful techniques and finally we realize that collision could be utilized to assists us. Guided by this roadmap, the thesis mainly addresses collision to achieve energy-efficient scheduling and near-optimal channel utilization, respectively in the stages of collision avoidance and tolerance. In the stages of cancellation and exploitation, we recover collided signals by signal cancellation and make use of collision patterns and even generate collision to build a decoupled control plane based on the data plane.