Enhanced CSMA/CA Protocol Design for Integrated Data and Energy Transfer in WLANs

We study a distributed coordination function (DCF) aided WLAN system, where the user stations (STAs) are capable of harvesting energy either from the AP's downlink data transmission or from the AP's dedicated downlink energy transfer. The energy harvested by the STAs is then exploited for powering their own uplink data transmission. Based on the classic carrier-sense-multiple-access with collision avoidance (CSMA/CA) protocol, a pair of enhanced versions are proposed for the sake of incorporating the active energy request of the STAs and the dedicated energy transfer of the AP. The first one is the energy-backoff-interval aided CSMA/CA (EBI-CSMA/CA) protocol. The other is the energy-packet aided CSMA/CA protocol (EP-CSMA/CA). According to our simulation results, both of the protocols are capable of substantially increasing the uplink throughput, when compared to their counterpart without the dedicated energy transfer. Furthermore, the EP-CSMA/CA protocol is more energy-efficient than the EBI-CSMA/CA protocol, since it does not require frequent control signalling exchange for the energy requests and responses.