Efficient Immediate-Transmission Scheme for Emergency Packets in Closed Area Wireless Access Networks

This paper proposes an efficient immediate-transmission scheme for highly reliable and low-latency wireless communication without waiting for radio resource allocation. In the conventional, basic radio resource allocation scheme, a base station (BS) cannot transmit an emergency packet immediately without waiting until the next transmission allocation period. A technique to shorten the allocation period has been investigated, but the increased control overhead degrades the system throughput. The proposed efficient immediate-transmission scheme takes a different approach. When an emergency packet is input to a BS, it interrupts non-emergency packet transmission. The BS transmits the emergency packet multiple times with shifted subcarriers and orthogonal frequency division multiplexing (OFDM) symbols. The receiver then calculates the correlation between the applicable signals and detects the emergency packet when it exceeds a threshold. Computer simulations derived the appropriate parameters for the transmission of the emergency packet, namely, the number of subcarriers, the number of OFDM symbols, and the detection threshold. The proposed efficient immediate-transmission scheme could improve the system throughput as the generation ratio of emergency packets increases.