Coordinated Multi-point Transmission For Inter-cell Interference Coordination In OFDM System Uplinks

The fast development of mobile communication systems will be proposed as a high requirement on the peak rate, latency, spectral efficiency and channel capacity.In order to meet the technical requirements of International Telecommunication Union (ITU) to IMT-Advanced. In the march 2008, when the standardization of LTE has been accomplished, 3GPP started the research on LTE-Advance. Its main research focus on resource management and optimization of the network layer.It remains a major problem that the different performance on cell-edge UE and cell-center UE in the LTE-Advanced systems. The Inter-cell Interference Coordination (ICIC) will be a key technology to improving the performance of the whole system. LTE-Advanced also takes the cell average spectrum efficiency and the cell-edge spectrum efficiency as the important improving indicators. Simultaneously, LTE-A introduced some technology to improving the cell-edge UE performance, such as Relaying Technology (relay) and Coordinated Multi-point Transmission (CoMP). In this paper, based on soft frequency reuse and taking account to the situation of load imbalance, we analysis the static/semi-static frequency allocation in CoMP, and propose an adaptive soft frequency reuse (ASFR) method. First, according to the type of UE which requesting to transmitting data, the method allocates the reserved PRB.Second, this method combines with the load situation of cell to reallocate the cell-edge band. Finally, according to the HII, cell decides to accept the reallocation or not.At the same time, we analysis the selection factor of CoMP coordination site: RSRP and delay, and taking account to the situation of load imbalance, proposed a CoMP coordination site algorithm based on RSRP+Load. Simulation results show that the ASFR can guarantee the throughput of cell-edge UE while reducing the access blocking rate, The RSRP +Load algorithm can balance the load and the signal quality to select CoMP coordination site and will not affect the performance of UE in heavy load site.In CoMP uplinks, in order to eliminate inter-cell interference, consider using the adaptive soft frequency reuse (ASFR) method to allocate the frequency, and using the RSRP + load algorithm to select CoMP coordination site, simultaneously. As well to avoid the inter-cell interference, comparing to the No-ICIC CoMP system, ASFR-ICIC-CoMP system have a throughput increasing in the cell-edge UE. In heavy load conditions, the ASFR-ICIC-CoMP not only protects the heavy loads site but also using adaptive frequency allocation to ensure a small amount of new UE to access the system. Overall, the CoMP coordination site selection algorithm based on Adaptive soft frequency reuse (ASFR) can inprove the signal quality while balancing the system load.