Higher order Sectorization in LTE downlink with 3GPP release 10 closed loop MIMO transmission techniques

An extensive evaluation on the system performance of a conventional LTE wide beam tri-sector site network exploiting 3GPP Rel. 10 advanced closed loop MIMO transmission techniques with that of a Higher Order Sectorized (HOS) network has been carried out. The investigation emphasizes on a system performance assessment under realistic conditions. These include a real MCS link adaptation with HARQ processes, adaptive scheduling algorithms, standardized closed loop MIMO transmission techniques with the corresponding feedback mechanism and antenna characteristics as parameterized by the antenna manufacturers. The basics of HOS is first explained on the basis of a simple single transmit antenna system per sector. Antenna diversity is then included in the system. System performance comparison for a practical network with a fixed number of transmit antenna per site (24 Tx antennas/site) is carried out for various network layouts applying either MIMO or HOS. For the latter 2 variants of deployments are considered: the hard-sectorization, where multiple antennas with narrower beam width are used to cover the smaller sub-sectors and the soft-sectorization, in which fixed beam forming by means of pre-coding weights applied on an antenna array is exploited for sector forming. Constrain to Rel. 10 feedback mechanism, numerical results indicate advantages in deploying higher-order sectorization over the MIMO usage, provided that antennas with suitable pattern characteristics or enough antennas ($> 4$) to form virtual sectors are available.