t (CoMP) Transmission, which enables the eNodeBs to operate more jointly. In Releases 8-10, the UE was communicating with one eNodeB at the time, while with Release 11 CoMP, the possibility to provide feedback for more than one eNodeB was introduced and similarly the possibility for receiving data from even more multiple eNodeBs. Likely in the uplink direction, CoMP could be achieved as well by eNodeB implementation where the multiple receivers in different cells/sectors are receiving the transmission from a single UE. There are different types of CoMP operation possible in Release 11, with all of them relying on fast connectivity between eNodeBs. Would there be more delay (as was studied in Release 12), performance loss would be easily resulting, as was the case with the studies for eNodeB scheduler coordination. The following CoMP modes can be identified: Coordinated Scheduling and Beamforming (CS/CB) requires the least amount of informa- tion exchange between eNodeBs since UEs receive a data transmission from their respective serving cell only, but adjacent cells perform coordinated scheduling and/or transmitter pre- coding to avoid or reduce the inter-cell interference. LTE Small Cell Optimization Release 11 Joint Transmission Co-ordinated scheduling/Beamforming UE with multicell feedback Figure 2.16 Different downlink CoMP schemes in Release 11 Joint Processing (JP) CoMP aims to provide the UE data for multiple transmission points (eNodeBs) SO more than just the serving cell can take part of the transmission for a UE. This requires large bandwidth, very low latency backhaul, in practice, fibre connectivity, between eNodeB sites. The possible modes are Dynamic Cell Selection (DCS) where the data would be sent always from one eNodeB only (based on the UE feedback) or Joint Transmission (JT) CoMP where multiple cells jointly and coherently transmit to one or multiple terminals on the same time and frequency resources. Use of the same time and frequency resources is important element of CoMP as then the transmis