Success Prioritized Slotted ALOHA with Sleep Function

For future machine-type communication systems, the frame duration will shorten because the sensor data size is small and the PHY rate gets higher. The contention interval caused by the propagation delay and the processing time becomes relatively larger as compared with the frame duration. The advantage of carrier sense function for random access protocols is impaired. To enhance the energy efficiency of wireless communication devices, the frequent use of carrier sense function will not be desirable because the receiver is active during sensing the wireless channel. In this paper, we propose a non-persistent slotted ALOHA (SALOHA) that the transceiver is in the sleep mode except for transmit and observation slots on the assumption of immediate ACK or self ACK. We incorporate a success prioritized backoff algorithm into SALOHA in order to enhance the throughput and reduce the energy efficiency and the delay. We clarify the closed-form expressions of network throughput and per-node consumed current for given saturated network traffic. A network simulator shows the unsaturated network performances such as the network throughput and the average delay. Furthermore, we design the contention window (CW) so as to maximize the network throughput.