fer and with bursty traffic. The liquid cluster solution with seven cells gives 18% to 39% gains. The gains from eCoMP in the average data rates are very low. The eCoMP gains with non-ideal backhaul are shown in Figure 7.30. If the backhaul latency is 5 ms, there are still clear gains visible from eCoMP. But if the latency is increased to 10 ms, the gains from inter-site coordination disappear and the performance is similar to intra-site coordination. These simulations give some guidelines for the transport network design in terms of delay requirements. 7.5 Coordinated Multipoint (CoMP) CoMP solution uses multi-cell transmission and reception for improving the radio efficiency. CoMP study was started in Release 10 and completed in Release 11. The most advanced version of CoMP - joint transmission and joint processing - requires centralized baseband solution and high data rate and low latency fibre connection between the baseband and the RF. For more detailed architecture discussion, see Chapter 5. The less demanding version - dynamic cell selection - can also operate without centralized baseband. Uplink CoMP allows to receive the transmission signal from one UE by several cells. The combination of these cells is called a CoMP set. The CoMP set can be within one eNodeB and called intra-site CoMP, or also between eNodeBs and called inter-site CoMP. These two scenarios are shown in Figure 7.31. Intra-site CoMP is simpler from the network architecture point of view since the signal combination takes place within one eNodeB. Small Cell Interference Management Intra site CoMP Macro eNodeB no. 1 Macro eNodeB no.2 including baseband including baseband Inter-site CoMP Baseband Macro eNodeB no. 1 Macro eNodeB no.2 just RF just RF Figure 7.31 Intra-site and inter-site CoMP The benefit of uplink CoMP is studied in the system simulations both in macro cellular network and in heterogeneous network with co-channel macro and pico cells. The CoMP gain is expected to be higher in HetNet scenario than in macro network. The macro ce