A Cross Layer Protocol PHY/MAC for Body Pathloss in IEEE 802.11ah IoT Networks

Internet of Things (IoT) will continue to grow while demand is needed in lots of civil areas. The new Wi-Fi 802.11ah standard from the IEEE supports IoT development. One of the 802.11ah's application is in the healthcare domain. The IoT sensor networks used by patients could support medical staff to diagnose the emergency cases and to monitor continuously. However, the human body and movement can cause interference to the transmitted signal from sensor nodes, which affects the receiving process at Access Point (AP). Thus, the AP may not reply with the Acknowledge (ACK). When the sensor nodes do not receive the ACK from the AP, the sensor nodes will retransmit the data, which will certainly increase Packet Error Rate (PER). Here, we propose a new cross layer protocol to overcome this problem. The proposal takes advantages of beacon power measurements in the node's PHY layer to determine whether there is interference from the human body or not. This information is used by the MAC layer to decide the transmission of packets. Our results show that there are significant improvements of the PER while maintaining the throughput relatively the same as the conventional protocol.