Supporting Asymmetric Transmission for Full-Duplex Smart-Home Networks

In smart home networks, the traffic is often asymmetric (i.e., the uplink traffic load of a node is not equal to its downlink traffic load). This paper is concerned with how to achieve asymmetric transmission for a full-duplex (FD) IoT network (where the AP and nodes are FD-enabled). Most existing related schemes considered a partial FD network consisting of an FD AP and half-duplex (HD) nodes and achieved asymmetric transmission via PHY-layer mechanisms such as power control. However, for an FD network, the MAC-layer scheduling mechanism might be better to achieve asymmetric transmission than the PHY-layer power-control mechanism which will introduce complex interference management. To this end, we propose a simple and novel MAC scheduling scheme called AT-MAC to support asymmetric transmission in an FD IoT network. In our design, we differentiate uplink-dominant (UD) and downlink-dominant (DD) nodes. Upon receiving a packet, a receiver determines whether to execute a reverse transmission to the peer or to initiate a new transmission to a third node according to the type of UD and DD nodes. Next, we develop a theoretical framework to evaluate the throughput of AT-MAC. The extensive simulations verify that our design is very effective (namely, it can achieve the asymmetric transmission, while fully utilizing the FD gain to maximize the system throughput and lower the packet delay) and our theoretical model is very accurate. This paper is very helpful for designing quality-of-service-oriented FD MAC protocols.