f any frame can be allocated either to uplink or to downlink based on the traffic needs. The downside of the dynamic allocation is increased inter-cell interference: at the same time when one cell's UE may be transmitting in the uplink, another UE close may be receiving from another cell, and thus experiences this inter-cell interference to the fullest. Thus dynamic TDD is more promising in relatively small cells. This cell-edge phenomenon can be mitigated with advanced receiver designs and inter-cell interference coordination. The dynamic TDD frame structure can be designed to be compatible with full-duplex TDD, where the transmission and reception take place at the same time, and the transmitted signal is cancelled from the received signal (Fig- ure 17.4). In this case some frames would be scheduled to have both DL and UL transmission at the same time. Due to the massive power difference of the transmitted and received sig- nals, even after the cancellation there is some residual interference injected to the received Control Data (entirely DL or entirely UL) OFDM symbol Subframe Figure 17.4 An example of a dynamic TDD-compatible frame structure LTE Small Cell Optimization Power OFDMA Demodulator receiver User 1 User 1 User 2 IC receiver to cancel User 1 Demodulator signal Signal at eNodeB transmitter OFDMA receiver User 2 Figure 17.5 NOMA principle signal leading to somewhat reduced link performance when compared to just transmitting or receiving. The cost and complexity of the self-cancellation related to full-duplex operation may make it more practical for the base stations than terminals. In this set-up the base station would receive a transmission from one UE and at the same time transmit to another one. Notably the dynamic TDD frame structure with sub-frame duration of a fraction of a millisecond is suitable for low-cost in-band self-backhauling access points. The low-cost design approach allows for using the same RF transceiver for both access and backhaul links in an opportunistically time-divided manner