LTE Advanced: 3GPP Solution for IMT-Advanced

6.6 Conclusions

In this chapter, we have covered the LTE downlink MIMO enhancement principles as defined in 3GPP Release 10 specifications as well as the resulting performance. 3GPP has made further investigations in Release 11 to see whether there would be some additional improvements giving enough capacity gain to justify the additional complexity for supporting them, as discussed in Chapter 12. Downlink MIMO as a feature is already widely adopted in the field and also the experiences of the Release 8 performance are good showing large usability of MIMO in the practical networks. The theoretical peak data rate with and eight antenna MIMO solution could reach even 600 Mbps with a 20 MHz carrier. The performance can be improved depending on the deployment scenario with the Release 10 solutions having, however, a large dependency on the types of antennas used in the network side, favouring the same case Release 8 SU-MIMO solution, and in some cases then showing more favourable results to the Release 10 MU-MIMO operation. The widely-used X-polarized antenna structures are favouring the use of SU-MIMO.