MAC Layer DATA/ACK Handshake in the Hybrid VLC-RF System
Knightly, Edward W
Master of Science
The hybrid VLC-RF system utilizes a uni-directional VLC link for downlink and the legacy Wi-Fi link for uplink transmission. However, simply integrating the two links without any modi cation in the MAC layer would cause problems for the MAC layer DATA/ACK handshake. The acknowledgements for VLC packets have to be transmitted via ra- dio. Because of the Wi-Fi channel's contention based random access, the transmission will be delayed and degrades the performance of the legacy Wi-Fi, especially when the Wi-Fi channel is heavily loaded. In my the- sis, I design and analyze the Spoofed NAV Triggered Multi-client ACKs (STMA) scheme to transmit the delay-sensitive VLC ACK timely while keep the degradation of legacy Wi-Fi under-control. I implement the key components of STMA and evaluate its performance with a combination of over-the-air experiments and trace-driven simulations. The result shows that in a dense WLAN scenario, STMA reduces the response delay and legacy Wi-Fi degradation signi cantly in comparison to 802.11 contention- based approach.
Hybrid VLC-RF; MAC Protocol; DATA/ACK Handshake