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MME<br />
S1-MME<br />
S11<br />
eNode<br />
IP<br />
GW<br />
S1-U<br />
Figure 5.1. Basic EPS Architecture (based on 3GPP TS 23.401).<br />
After the completion of Rel-8 in March of 2009, focus in 3GPP turned to Rel-9, which was subsequently<br />
completed in March 2010. Rel-9 added feature functionality and performance enhancements to both<br />
HSPA and LTE.<br />
For HSPA, Rel-9 introduced support for uplink dual-cell, as well as the capability to enable downlink dualcell<br />
deployments across non-contiguous frequency bands. Also added in Rel-9 was the support of<br />
simultaneous MIMO and DC-HSPA operation, as well as enhancements to the transmit diversity modes to<br />
improve performance with non-MIMO capable devices.<br />
For LTE, several Rel-9 features and capabilities were added to enhance upon the initial Rel-8 LTE<br />
technology, specifically:<br />
� The support of emergency services, location services and emergency warning broadcast<br />
services. These features are critical for introducing VoIP over LTE because they are required for<br />
VoLTE to meet e911 requirements<br />
� Enhancements (particularly for idle mode camping) to the Circuit Switched FallBack (CSFB)<br />
feature that was introduced in Rel-8<br />
� Enhancements for MBMS to enable broadcast/multi-cast capabilities over LTE<br />
SGi<br />
� Self-Organizing Network (SON) enhancements to optimize handover performance, improve load<br />
balancing capabilities (within LTE and between LTE and 2G/3G), optimize RACH performance<br />
and improve energy savings<br />
� The support of dual layer beamforming to improve peak rates when in beamforming mode<br />
www.4gamericas.org February 2011 Page 43<br />
S5
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