Interference Management For Dynamic TDD In C-RAN

The explosive data traffic of mobile phones making a challenge for the future of the 5G cellular networks.Predictions suggest that by 2025 there will be a "10,000-fold increase in data traffic demana".It is obvious that current networks will be unable to handle this situation.Multiple-input multiple-output(MIMO)technology can provide the degrees of freedom to support multi-user transmission.On the other hand,Dynamic Time Division Duplex(D-TDD)system shows great potentials in handling the user traffic,where the uplink(UL)and downlink(DL)transmission resources are flexibly scheduled among cells.However,the interference limits the potential performance improvement of the D-TDD system.Many interference mitigation schemes have been proposed to manage interference in the conventional cellular networks and the heterogeneous networks(HetNets).A new promising network with a centralization controller,i.e.,the Cloud Radio Access Network(C-RAN),has been proposed to improve the energy and spectrum efficiency for further improvement of network performance while reducing the cost expense.In our research,we will consider the multi-cell and multi-user MIMO D-TDD system,where each cell consists of a base station(BS)with M antennas and N users each equipped with L antennas.In general,the BS assumed to perform either downlink or uplink transmission based on the instantaneous traffic demand.Regarding the implementation of MU-MIMO with D-TDD,two kinds of interference will occur in the network,the first one is the intra-cell interference caused by the MU-MIMO within each cell while the second one is the inter-cell interference caused by the unique properties of D-TDD.In order to reduce the severe interference in D-TDD system,we propose an opportunistic interference alignment(OIA)inspired scheme for D-TDD system,which is named as OIA-DTDD.In particular,we propose novel user selection with the help of a reference signal space(RSS)to achieve the interference-aware user scheduling.In this way,the intra-cell and inter-cell interference can be mitigated.Furthermore,we propose novel RSS-based transciver design to fruther control the BS-BS inter-cell interference.Our overall OIA-DTDD scheme shows significant performance improvement as compared to the conventional non-interference aware solutions.