The initial enhancements were included to LTE in 3GPP release 9 as frozen in Dec 2009. These enhancements were the improvements which were left behind from release 8 or perhaps some of them provided some minor improvements in the release 8 features. These enhancements/improvements are listed below
- Femto Cell as LTE Home eNodeB
- MIMO Beam-forming
- Evolved Multimedia Broadcast and Multicast Service (eMBMS)
- Self Organizing Networks (SON) enhancement with Optimization Features like RACH Optimization, Mobility Robustness Optimization (MRO), Inter Cell Interference Co-ordination (ICIC)
- LTE Positioning Services
- Public Warning System Enhancement – Commercial Mobile Alert System (CMAS)
Femto cell is basically a small cell used in offices or homes and connected to providers’ networks through landline broadband connection. LTE femto cell new requirements were added to release 9 to use LTE in the small cell deployments
Beamforming is used to increase cell edge throughput by directing beam towards specific UE by UE position estimation at eNodeB. In release 8, LTE supported single layer beam forming based on user-specific Reference Symbols. In release 9, single layer beam forming has been extended to multilayer beam forming to enhance the cell edge user experience.
SON means self Organise Network where the network can perform its installation, optimization, and healing by its own in order to reduce manual work and cost associated with technical support. The idea of SON was introduced in release 8 though the focus was more towards eNodeBs self-configuration features like PCI selection, Automatic Neighbor Relation whereas in release 9, requirements for self-optimization were also added. These optimizations were RACH optimization, Mobility (Handover) Optimization.
evolved multimedia broadcast and multicast service where operators have the capability to broadcast services over LTE network. The idea is not novel to the LTE and has been used in legacy 3G networks as well but for LTE, the MBMS channel has been evolved from data rate and capacity perspective. The MBMS was already defined at the physical layer in release 8 but with release 9, higher layer and network layer aspects were completed as part of release 9.
For UE positioning, there are three position methods are specified in LTE release 9 i.e. Assisted GPS (A-GPS), Observed Time difference of arrival (OTDOA) and Enhanced Cell ID (E-CID). The goal is to improve the accuracy of user locations which can be utilized in LTE for beam-forming. Location-based Services and etc.
Public Warning System helps the public to receive timely and accurate alerts related to natural disasters or other critical situations. Commercial Mobile Alert System (CMAS) was introduced in release 9 in addition to Earthquake and Tsunami Warning System (ETWS) introduced in release 8.