A slotted message access protocol can be implemented for transmitting short packets. Each beacon period may be divided into multiple time slots. At least one time slot may be assigned to a network device per beacon period based, at least in part, on latency specifications of packets that the network device is configured to transmit. In one example, some of the unassigned time slots may be designated as contention-based time slots. Network devices may contend with each other to gain control of and transmit packets during a contention-based time slot based on the priority level of the packets to be transmitted. Network devices may also use an encryption key and an initialization vector for securely exchanging short packets. Furthermore, a repeater network device may be designated to retransmit a packet, received from an original transmitting network device, during a communication time slot assigned to the original transmitting network device.