 on the user locations. Release 11 improved eICIC with UE interference cancellation. Release 11 defined CoMP which is the most advanced multi-cell transmission solution with joint processing. Joint processing sets highest requirements for the transport: in practice, direct fibre connection is required between the baseband unit and the RF head. Release 12 added eCoMP that also allows to use non-ideal backhaul without direct fibre. Table 7.4 Comparison of different interference mitigation solutions Inter-cell Enhanced inter-cell Coordinated Enhanced interference interference multipoint coordinated coordination coordination (CoMP) multipoint (ICIC) (eICIC) (eCoMP) Operating domain Frequency domain Time domain Additionally Additionally spatial domain spatial domain (antennas) (antennas) Operating CQI feedback in Time-domain Multi-cell Fast multi-cell principle frequency resource sharing transmission coordination domain in HetNet and reception over non-ideal backhaul Base station time Not needed (only synchronization frequency synchronization) Transport No requirements Low requirements - High transport Low requirements requirements only control plane requirements for joint processing 3GPP Release Release 8 eICIC in Release 10 Release 11 Release 12 feICIC in Release 11 LTE Small Cell Optimization eCoMP uses resource coordination between eNodeBs via X2 interface. eCoMP can improve cell edge data rates by 20%. References [1] B. Soret, K. I. Pedersen, N. Jorgen, and V. Fernandez-Lopez, 'Interference Coordination for Dense Wireless Networks', IEEE Communications Magazine, 53, 102-109 (2015). [2] K. I. Pedersen, Y. Wang, S. Strzyz, and F. Frederiksen, 'Enhanced Inter-cell Interference Coordination in Co-channel Multi-layer LTE-Advanced Networks', IEEE Wireless Communications Magazine, 20, 120-127 (2013). [3] B. Soret, H. Wang, K. I. Pedersen, and C. Rosa, 'Multicell Cooperation for LTE-Advanced Heterogeneous Network Scenarios', IEEE Wireless Communications Magazine, 20(1), 27-34, (2013). [4] Y. Wang, B. Soret, and K. I. Ped