Short and Long Multi-frames Based Multiple Access Control for Cognitive Machine Type Communication with Full-Duplex Gateway

Cognitive radio could satisfy the demand for radio spectrum urgently required by the Internet of Things employing machine type communication to connect numerous machines. In cognitive radio based machine type communication, a time division multiple access (TDMA) based interface with a reservation scheme was proposed to utilize long time opportunities due to its spectrum-efficient, energy-efficient, and deployment-economical benefits. Previous literature indicates that short idle time opportunities exist during the activities of primary users. However, it is spectrum-inefficient to use single size multi-frames in a channel of mixed short and long time opportunities; in contrast, the difficulty of using multi-frames of different lengths is how to appropriately determine that an idle period is in short or long time opportunities. Thus, this paper proposes a multiple access control (MAC) which incorporates short and long multi-frames into the TDMA based interface with a reservation scheme. With the aid of the sensing of a full-duplex gateway, the proposed MAC adaptively uses long and short multi-frames in a channel of long and fixed-length short time opportunities such that the trade-off between throughput and interference is balanced. Extensive simulation results show that the proposed multiple access control with short and long multi-frames produces high throughput while the interference of primary users is kept at a low level.