, and it is up to the network scheduler, if necessary, to coordinate the scheduling decisions between neighboring sites to avoid inter-cell interference. There is also a possibility to semi-statically configure the transmission direction of some of the slots, a feature that can allow reduced device energy consumption as it is not necessary to monitor downlink control channels in slots that are a priori known to be reserved for uplink usage (Fig. 3.38). 3.4.3 Full-Duplex Schemes The term full-duplex was traditionally used to describe a simultaneous bidirectional commu- nication, in contrast to half-duplex, which assumed time division duplexing. However, in recent years, the term has carried a new concept and that is when a device can transmit and receive at the same time and over the same carrier frequency. Some authors refer to the lat- ter scheme as in-band full duplex in the literature to distinguish this new concept from its traditional usage. It is intuitive that enabling wireless devices to operate in full-duplex mode offers the potential to double the spectral efficiency, considering that traditional approaches for increasing spectral efficiency such as adaptive coding and modulation, MIMO and smart antennas have almost reached their maximum limits. In addition, full-duplex scheme 374 Chapter 3 improves the reliability and flexibility of dynamic spectrum allocation in cognitive radio networks and enables the small cells to reuse radio resources simultaneously for access and backhaul [29]. The main challenge for a full-duplex radio is self-interference and how to manage and sup- press it. Self-interference or transmitter leakage was studied earlier and refers to the signal that leaks from the device transmitter to its own receiver. In general, the transmitter signal is about 100 dB stronger than the reference sensitivity level of the receiver. A considerable part of this transmitted signal leaks into the receiver chain, causing serious issues in decod- ing the desired signal, which could be considered noisy,