Improved Frequency Reuse Schemes with Horizontal Sector Offset for LTE

Macrocellular networks with frequency reuse across sectors of the same eNodeB and neighboring eNodeBs suffer from high interference at the cell boundaries, resulting in an uneven distribution of User Equipment (UE) throughputs. Recently, it has been shown that for multi-carrier UMTS networks a horizontal offset configuration for the second carrier can significantly increase the performance and call drop rates of the network at the cost of an increased number of handovers. In this paper, the sector offset concept is extended to LTE eNodeBs, which allows deploying offset antennas without increasing the number of sectors per eNodeB, while schedulers derive the proper antenna to UE association. In this way, the number of handovers does not increase. A novel cell-specific reference signal configuration is proposed to enable this concept. Simulations for LTE show that the proposed sector offset configuration can increase the average UE and cell-edge UE throughput up to 19% and 105%, respectively while keeping the total number of handovers nearly constant. Moreover, it is shown that the new configuration can reduce the handover failure rate up to 86%.