3GPP release 10 driving force to further develop LTE technology towards LTE–Advanced. LTE Release 10 was to provide higher bit rates in a cost efficient way and, at the same time, completely fulfil the requirements set by ITU for IMT Advanced, also referred to as 4G. Its specifications freeze in 2011.
- Increased peak data rate, DL 3 Gbps, UL 1.5 Gbps
- Higher spectral efficiency, from a maximum of 16bps/Hz in Release 8 to 30 bps/Hz in Release 10
- Carrier aggregation (CA), allowing the combination of up to five separate carriers to enable bandwidths up to 100MHz
- MIMO antenna configurations up to 8×8 downlink and 4×4 uplink
- Increased number of simultaneously active subscribers
- Improved performance at cell edges, e.g. for DL 2×2 MIMO at least 2.40 bps/Hz/cell.
The main features that LTE Release 10 introduce are
- Carrier Aggregation
- Enhanced Downlink Multiple Antenna Transmission for LTE
- Uplink Multiple Antenna Transmission for LTE
- Relay for LTE
- New LTE Bands for US and ATC
- Self Optimizing Networks (SON) Enhancements
- Enhancements to MBMS
Carrier Aggregation 3GPP release 10 needs to support wider transmission bandwidths than the currently supported 20 MHz specified in Rel.8/9 while maintaining the backwards compatibility with Rel-8/9. The preferred solution to this is carrier aggregation , where multiple component carriers are aggregated to form a larger overall transmission bandwidth.The carrier aggregation suppose to consider following scenarios.
- Release-8/9 backward compatible carriers are the basic building blocks and should be supported
- Release-10 signalling shall support aggregation of up to 5 DL CCs and 5 UL CCs, irrespective of intra- or inter-band CA.
- Release-10 shall be support both intra- and inter-band aggregation.
- Releasel-10 shall b e support inter-band aggregation under deployments with RRH and repeaters, i.e., with different signal reception timings across CCs of different bands.
- UE-specific asymmetric number of component carriers in DL and UL shall be supported
- Component carriers can have any of the bandwidths supported in Rel-8
- The signalling and protocol specifications to support carrier aggregation shall be designed in a generic way
- Specification of carrier aggregation bands shall be done in Release independent manner.
- UL and DL control channel structure
- L1 procedures shall support CA
- L2/L3 protocols and procedures shall support CA
- UE and BS RF core requirements
Enhanced Downlink Multiple Antenna Transmission for LTE supporting downlink SU-MIMO with up to eight layer spatial multiplexing is needed to fulfill target for LTE-Advanced on peak rate spectral efficiency of 30 b/s/Hz.During the LTE-Advanced study, enhanced downlink MU-MIMO with UE specific reference signal was identified as critical to fulfill the IMT-Advanced requirements for average spectrum efficiency. To achieve this following features and procedure are considered
- Release 10 specify support downlink SU-MIMO for up to 8×8, considering practical antenna arrangements
- Release 10 defines two types of Reference Signal (RS), RS for PDSCH demodulation and RS for CSI (CQI/RI/PMI) reporting
- Mapping of PDSCH to the non-control region of Normal and MBSFN subframes
- New CSI feedback scheme
- New DCI format 2C
Uplink Multiple Antenna Transmission for supporting UL SU-MIMO with up to four layer spatial multiplexing is needed to fulfil requirements for LTE-Advanced on peak rate spectral efficiency of 15 b/s/Hz. During the LTE-Advanced study item, UL transmission diversity for PUCCH and codebook based transmission for PUSCH will help ensure that LTE-Advanced system deployments offer good cell edge and average performance.
3GPP release shall fulfil the following objectives in regards with uplink MIMO:
- Release 10 Specifies UL SU-MIMO for up to 4×4 MIMO, considering practical UE implementation.
- New DCI format 4
- Addition in precoded DRS
- Additional SRS
- Uplink transmit diversity scheme on the PUCCH
- Additional physical control signalling
Relay for LTE have been introduced in release 10 LTE-Advanced study item. One of the prime perceived benefits of relay is to provide extended LTE coverage in targeted areas at low cost. In order to maximize the benefits for cost-effective coverage improvements, relays are standardized as part of release 10.
The overall objective of Relays is coverage-improvement with the following configurations:
- The eNodeB-to-relay link operates in the same carrier frequency as the relay-to-UE link.
- The eNodeB-to-relay link operates in a different carrier frequency from the relay-to-UE link.
For each of the above configurations, 3GPP addresses the case where the eNB-to-relay link is operating in the same carrier frequency as eNodeB-to-UE link.
A Relay shall have the following characteristics:
- It control cells, each of which appears to a UE as a separate cell distinct from the donor cell
- The cells shall have their own Physical Cell ID (defined in LTE Rel-8) and the relay node shall transmit its own synchronization channels, reference symbols,
- The UE shall receive scheduling information and HARQ feedback directly from the relay node and send its control channels (SR/CQI/ACK) to the relay node
No UE impact expected from functionality because of relay and all legacy LTE UEs shall be served by the relay cell.
New LTE Bands for US and ATC
- Introduce support for the 2496 -2690MHz band for LTE-TDD in the US
- Added the 2 GHz band LTE for ATC (Ancillary Terrestrial Component) of MSS (Mobile Satellite Services) in North America (2180 – 2200 MHz: Down-link 2000 – 2020 MHz: Up-link)
- Added the L-Band LTE for ATC of MSS in North America to 3GPP core specifications for LTE FDD networks(1525 – 1559 MHz: Down-link,1626.5 – 1660.5 MHz: Up-link )
Self Optimizing Networks (SON) Enhancements in release 10 considers the feature like CCO, MRO and MLB and brief is give below.
Coverage and Capacity Optimization (CCO):The use case is to enable detection of following problems:
- Priority 1: coverage problems, e.g. coverage holes
- Priority 2: capacity problems
Mobility Robustness Optimization (MRO) enhancements to enable detection and to provide tools for possible correction of following problems:
- Connection failures in inter-RAT environment:
- Priority 1: at HOs from LTE to UMTS/GSM
- Priority 2: at HOs from UMTS/GSM to LTE
- Obtaining UE measurements in case of unsuccessful re-establishment after connection failure
- Ping-pongs in idle mode (inter-RAT and intra-LTE environment)
- Ping-pongs in active mode (inter-RAT)
- HO to wrong cell (in intra-LTE environment) that does not cause connection failure (e.g. short stay problem)
Mobility Load Balancing (MLB) enhancements to fulfil following objectives:
- Improving reliability of MLB in intra-LTE scenarios
- Improving functionality of the MLB in inter-RAT scenarios (the transport method agreed for Release 9 should be used for Release 10).
Enhancements to MBMS
In Release 9 a core set of MBMS features was specified. There is a need to further evolve it in order to make the MBMS of LTE competitive. In Release 9 the network has no feedback from the MBMS UEs about the reception status of the MBMS service. A mechanism is needed to determine if there are sufficient UEs interested in receiving a service to enable the operator to decide if it is appropriate to deliver the service via MBSFN. This will allow the operator to choose between enabling or disabling MBSFN transmission for each service. Release 10 specifies following enhancements to support MBMS
- Enable statistical multiplexing gains for variable bit rate services.
- Support of Allocation and Retention Priority (ARP) pre-emption function for MBMS E-RABs.
- Specify a simple mechanism to enable the network to know the reception status of UEs receiving a given MBMS service in the RRC connected mode
- To allow network to know whether or not it is appropriate to activate/deactivate the service via MBSFN.
- The impact of such mechanisms on legacy devices should be minimized (it is tolerable if reception status of legacy devices stays unknown to the network).
- RAN groups should liaise with SA and CT according to the progress of aspects related to the non RAN parts of the solution