 shown in Figure 1.8. All the Release 8 Release 9 Release 10 150 (300) Mbps eMBMS Carrier aggregation 4 X 4 MIMO VoLTE Downlink 8 X 8 MIMO Flat architecture Femto Uplink 4 X 4 MIMO Low latency HetNet with eICIC Release 11 Release 12 Release 13 Dual connectivity LAA (LTE-U) feICIC eCoMP Advanced UE 3D beamforming Enhanced CA D2D enhancements Figure 1.6 Main contents of each release LTE Small Cell Optimization 1 Gbps 600 Mbps 100 MHz 450 Mbps 4CA or 4 X 4 300 Mbps 150 Mbps 20 + 20 MHz 2 X 2 MIMO 150 Mbps 2 X 2 MIMO 10 + 10 MHz 20 MHz 2 X 2 MIMO 2 X 2 MIMO Figure 1.7 Peak data rate evolution in commercial devices spectrum between 700 and 2600 MHz will be aggregated together. The carrier aggregation of the multiple spectrum blocks together helps in terms of network traffic management and load balancing in addition to providing more capacity and higher data rates. The higher frequency at 3.5 GHz can also be aggregated in the macro cells especially if the site density is high in the urban areas. Another option is to use 3.5 GHz band in the small cell layer. The unlicensed band at 5 GHz can be utilized in the small cells for more spectrum [3]. In the best case, more than 1 GHz of licensed spectrum is available for the mobile operators and more when considering the unlicensed spectrum. 1.6 Small Cell Deployments The small cell deployments are driven by the need for improved network quality, higher data rates and more capacity. So far most of the base stations have been high power macro base 5 GHz unlicensed band for small cells 3.5 GHz in small cells or macro cells 700-3500 MHz aggregated together Figure 1.8 Example spectrum resources for LTE usage Introduction Figure 1.9 The LTE micro cell base station with 5 kg, 5 L and 5+5 W stations while some small cells are being deployed in the advanced LTE networks. The small cell rollouts have come simpler than earlier because the new products are compact and include SON features for automatic configuration and optimization. An example micro base station product is shown in Figu