Working in the UK, where commercial LTE services are still not available, it is easy to forget that standardisation of LTE has been underway for many years. The first 3GPP standards were frozen way back in 2008, in 3GPP Release 8, and no fewer than five 3GPP releases containing LTE aspects have now received attention in the 3GPP standards arena.
Here I provide a short summary of the 3GPP releases relevant to LTE, including brief highlights of their contents.
3GPP Release 8 – Freeze Date 2008
Release 8 introduced LTE for the first time, with a completely new radio interface and core network, enabling substantially improved data performance compared with previous systems. Highlights included:
- up to 300Mbit/s downlink and 75Mbit/s uplink
- latency down to 10ms
- implementation in bandwidths of 1.4, 3 ,5 , 10, 15 or 20MHz, to allow for different deployment scenarios
- orthogonal frequency domain multiple access (OFDMA) downlink
- single-carrier frequency domain multiple access (SC-FDMA) uplink
- multiple input multiple output (MIMO) antennas
- flat radio network architecture, with no equivalent to the GSM BSC or UMTS RNC, and functionality distributed among the base stations (eNodeBs)
- all IP core network, the System Architecture Evolution (SAE).
3GPP Release 9 – Freeze Date 2009
Release 9 brought a number of refinements to features introduced in Release 8, along with new developments to the network architecture and new service features. These included:
- introduction of LTE femtocells in the form of the Home eNodeB (HeNB)
- self organising network (SON) features, such as optimisation of the random access channel
- evolved multimedia broadcast and multicast service (eMBMS) for the efficient delivery of the same multimedia content to multiple destinations
- location services (LCS) to pinpoint the location of a mobile device.
3GPP Release 10 – Freeze Date 2011
Release 10 provided a substantial uplift to the capacity and throughput of the LTE system and also took steps to improve the system performance for mobile devices located at some distance from a base station. Notable features included:
- up to 3Gbit/s downlink and 1.5Gbit/s uplink
- carrier aggregation (CA), allowing the combination of up to five separate carriers to enable bandwidths up to 100MHz
- higher order MIMO antenna configurations up to 8×8 downlink and 4×4 uplink
- relay nodes to support Heterogeneous Networks (“HetNets”) containing a wide variety of cell sizes
- enhanced inter-cell interference coordination (eICIC) to improve performance towards the edge of cells.
3GPP Release 11 – Freeze Date 2013
Release 11 will build on the platform of Release 10 with a number of refinements to existing capabilities, including:
- enhancements to Carrier Aggregation, MIMO, relay nodes and eICIC
- introduction of new frequency bands
- coordinated multipoint transmission and reception to enable simultaneous communication with multiple cells
- advanced receivers.
3GPP Release 12 – Freeze Date 2014
Potential features for Release 12 were discussed at a 3GPP workshop in Slovenia in June 2012. A strong requirement was the need to support the rapid increase in mobile data usage, but other items included the efficient support of diverse applications while ensuring a high quality user experience. Some of the candidates for Release 12 included:
- enhanced small cells for LTE, introducing a number of features to improve the support of HetNets
- inter-site carrier aggregation, to mix and match the capabilities and backhaul of adjacent cells
- new antenna techniques and advanced receivers to maximise the potential of large cells
- interworking between LTE and WiFi or HSPDA
- further developments of previous technologies.