Carrier Sense Multiple Access With Collision Avoidance And Pilots (CSMA/CAP)

Tech ID: 32790 / UC Case 2019-197-0


The traditional collision avoidance handshake consists of a request-to-send (RTS), clear-to-send (CTS), a data packet, and an acknowledgment (ACK). However, this system can result in multiple access interference on variable-length data packets and acknowledgements. This can even occur in multi-hop wireless networks when hidden terminals, exposed transmitters, or exposed receivers are present. 

Technology Description

This is augmented with the use of pilot messages. A pilot message is sent by a receiver after it sends a CTS, and a pilot is sent by a sender after its data packet, such that multiple access interference is avoided on data packets or ACKs. The system does not require full-duplex transceivers and can operate using less expensive half-duplex transceivers. There is no need for complex physical-layer techniques. Finally, variable-length data packets can be transmitted without multiple access interference (MAI). ACKs are sent without MAI.

Pictured: Eliminating MAI from exposed transmitters using pilots 


Figure 6 



Computer networking

Mesh networks 

Ad-hoc networks  



Elimination of Multiple Access Interference, including for acknowledgements 

Uses traditional carrier sensing techniques

Can use half-duplex transceivers rather than full duplex transceivers

No need for physical layer techniques


Intellectual Property Information

Patent Pending

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  • Garcia-Luna-Aceves, Jose Joaquin(JJ

Other Information


Collision avoidance, Data packet, Multiple Access Interference, Half-duplex transceivers, Router, Networking, Mesh network, Ad-hoc network

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