LTE-Advanced Pro is a new marker for LTE starting with Rel-13 onwards. According to 3GPP, “the new term is intended to mark the point in time where the LTE platform has been dramatically enhanced to address new markets as well as adding functionality to improve efficiency”.
LTE-Advanced Pro Rel-13 Features
The first release of LTE-Advanced Pro was frozen last month (March 2016). It was brought to reality with quite extensive set of new functionalities as compared to LTE-Advanced. They are summarized below.
LTE-WiFi Aggregation (LWA) – the Carrier Wi-Fi is serving as a capacity booster counterpart, using radio level integration with LTE serving as an anchor. In LWA, UE is configured by the eNB to utilize radio resources of both, LTE and WLAN.
Licensed Assisted Access (LAA) – aggregates the licensed LTE carrier (serving as a mobility and signaling anchor – PCell) with SCell using the new LTE frame format over the unlicensed 5GHz ISM band.
Device-to-device (D2D) – direct communication between devices assisted by network utilizing sideling exploiting new transport and physical channels.
Massive CA – extends carrier aggregation towards higher number of aggregated bands and towards the use of unlicensed spectrum for mobile networking. Massive CA enables up to 32CCs and thus theoretically provides up to 640MHz of aggregated bandwidth for a single device, while still fulfilling backwards compatibility with LTE Rel-8 channel bandwidths.
Dual Connectivity (DC) –spectrum aggregation in inter-site scenario, where a macro-cell serves as a mobility anchor, whereas the additional radio link provided by Small Cell acts as local capacity booster. DC enables to switch User Plane links among available SCs, whereas the user’s context is maintained by the overlay macro-cell. In contrary to CA, DC scheme, instead of aggregating MAC layer transport blocks, the PDCP Packet Data Units are combined, thus omitting the requirement for low latency and allowing non-ideal backhaul for SC connectivity.
MTC enhancements – addressing low complexity MTC with focus to define a low complexity UE category type that supports reduced bandwidth (operation with 1.4MHz), reduced transmit power, reduced support for downlink transmission modes, ultra-long battery life via power consumption reduction techniques and extended coverage operation (up to 15dB).
3D/Full Dimension-MIMO – allow to use elevation beamforming enhancing the horizontal beam steering, and using up to 64 antenna ports with further outlook towards high frequencies for 5G.
Multi-RAT Joint Coordination – addressing joint radio resource management between various RATs including “Dynamic Spectrum Access”, where the collocated LTE and GSM systems use dedicated bandwidth part which size depends on the actual traffic demands. It uses temporal traffic statistics: e.g. when GSM load on Traffic Channel is low, LTE is allowed to use shared part of the spectrum.
LTE-Advanced Pro v.2 – enhancements envisioned for Rel-14 
As Rel-13 was frozen last month, the work on Rel-14 has already started, with the new SI/WIs targeting improvements and new features for LTE-Advanced Pro. Some of the interesting functionalities are summarized below with the target to be frozen in June 2017.
enhanced LAA (eLAA) – proposal extends LAA scheme with UL consideration to enable full DC-like capabilities for unlicensed spectrum.
enhanced LWA (eLWA) – as LWA standardized within Rel-13, considered DL-only operation, an enhanced LWA (eLWA) is proposed within Rel-14 to overcome this limitation. The new features in this enhancement include: addition of UL transmission via WLAN, support for 60GHz, PDCP optimizations for increased data rates, and SON-related features for WLANs under eNB coverage.
Vehicluar-to-Vehicular (V2V) – aims at specifying RAN support for V2V operation integrated with Uu interface within or without network coverage using sidelink including: PHY layer structure, RRM requirements, and L2/L3 protocol operation.
CP and UP latency enhancements – shortening TTI down to a single OFDMA symbol and more resource efficient UL scheduling timing are some examples of the proposed improvements targeting latency reduction.
Light connection – discussion on a new intermediate RRC state for keeping UE context alive during short active/inactive transitions (applicable for massive MTC use case with small data transmission);
Multi-connectivity – is expected to enhance DC, by providing multiple links for a UE in two options. First option considers configuration of multiple radio links per UE, where only limited, selected set of radio links is active at any given moment. Alternatively, all of the configured multiple radio links can be active.
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Marcin Dryjanski received his M.Sc. degree in telecommunications from the Poznan University of Technology in Poland in June 2008. During the past 8 years, Marcin has served as R&D Engineer, Lead Researcher, R&D Consultant, Technical Trainer and Technical Leader. He has been providing expert level courses in the area of LTE/LTE-Advanced for leading mobile operators and vendors. Marcin provides consulting services to business projects in the area of 5G related topics. In addition to that, Marcin was a workpackage leader in EU-funded research projects aiming at radio interface design for 5G including FP-7 5GNOW and FP-7 SOLDER. He co-authored a number of research papers targeting 5G radio interface design. To contact Marcin please write to: firstname.lastname@example.org