Capacity Enhancement Techniques for LTE-Advanced

Capacity Enhancement Techniques for LTE-Advanced LG 전자 윤영우연구위원 yw.yun@lge.com 1/28

3GPP specification releases 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 GSM/GPRS/EDGE enhancements Release 99 W-CDMA Release 4 1.28Mcps TDD Release 5 HSDPA, IMS Release 6 HSUPA, MBMS, IMS+ ITU-R M.1457 IMT-2000 Recommendations Release 7 HSPA+ (MIMO, HOM etc.) Release 8 LTE, SAE Today s seminar focus Release 9 Small LTE/SAE enhancements Release 10 LTE-Advanced KRnet 2011 2/28

Definition of LTE-Advanced What is IMT-Advanced? A family of radio access technologies fulfilling IMT-Advanced requirements Relates to 4G as IMT-2000 relates to 3G IMT spectrum will be available to both IMT-2000 and IMT-Advanced What is LTE-Advanced? System now under development in 3GPP aiming toward IMT-Advanced Formal name: Advanced E-UTRA /Advanced E-UTRAN Evolution from 3GPP LTE specifications, not a revolution Comparable potential of 3GPP LTE with target requirements of IMT-advanced Fast and efficient correspondence against the timeline of WP5D s specification and commercialization for IMT-advanced Cost-efficient support for backward and forward compatibility between LTE and LTE-A Natural evolution of LTE (LTE release 10 & beyond) KRnet 2011 3/28

Major Milestones for LTE-Advanced Major Milestones Study item completion in March 2010 LTE-Advanced function block work items started in December, 2009, irrespective of completion for LTE-Advanced study item Initial approval of LTE-A (Rel-10 specification) in December, 2010 Initial GCS (Global Core Specification) submission to ITU-R WP5D in April, 2011 December version will be included in GCS ASN.1 freezing is expected to be done in June 2011 Final GCS submission to ITU-R in September 2011 Final references from OP are expected to use the June 2011 Release 10 version as the basis for the transpositions Standard Roadmap ITU-R WP5D 2009 2010 2011 Complete Tech Proposals Final Submission Evaluation Consensus Specification 2012 3GPP LTE-A LTE Rel.9 LTE Rel.10 [LTE Rel.11] LTE-A SI LTE-A Functional Work Items Beyond LTE-A SI KRnet 2011 4/28

System Performance Requirements for LTE-Advanced [1] General requirement LTE-Advanced is an evolution of LTE LTE-Advanced shall meet or exceed IMT-Advanced requirements within the ITU-R time plan Extended LTE-Advanced targets are adopted LTE-Advanced targets IMT-Advanced requirements and time plan Rel. 8 LTE Time KRnet 2011 5/28

Requirements for LTE-Advanced [2] Comparison between IMT-Advanced and LTE-Advanced LTE-Advanced should at least fulfill or exceed IMT-Advanced requirements ITU Requirement 3GPP Requirement Peak data rates 1Gbps in DL 500Mbps in UL Bandwidth 40MHz (scalable BW) Up to 100MHz User plane latency 10ms Improved compared to LTE Control plane latency Peak spectrum efficiency 100ms 15bps/Hz in DL 6.75bps/Hz in UL Active Active dormant(<10ms) Camped Active (<50ms) 30bps/Hz in DL 15bps/Hz in UL Average spectrum efficiency Cell edge spectrum efficiency Set for four scenarios and several antenna configurations See next slide for case 1 requirement VoIP capacity Up to 200 UEs per 5MHz Improved compared to LTE KRnet 2011 6/28

Requirements for LTE-Advanced [3] System performance requirements for IMT-Advanced Spectrum Efficiency Cell Edge Spectrum Efficiency System Performance Requirements from TR 36.913 Peak Spectral Efficiency: DL 30bits/Hz (8x8 MIMO), UL 15bps/Hz (4x4 MIMO) 40~60% improvement of average spectrum efficiency over LTE Rel-8 UL DL Ant. Config KRnet 2011 7/28 ITU system performance requirement Environment Indoor Micro-cell Base coverage Urban Rural/ High speed Case-1 DL (4x2 MIMO) 3 2.6 2.2 1.1 UL (2x4 MIMO) 2.25 1.8 1.4 0.7 DL (4x2 MIMO) 0.1 0.075 0.06 0.04 UL (2x4 MIMO) 0.07 0.05 0.03 0.015 LTE Cell Avg. SE [bps/hz/cell] LTE-ADV Cell Avg. SE [bps/hz/cell] LTE Cell Edge SE [bps/hz/user] LTE-ADV Cell Edge SE [bps/hz/user] 1x2 0.735 1.2 0.024 0.04 2x4-2.0-0.07 2x2 1.69 x1.4-1.6 2.4 0.05 x1.4-1.6 0.07 4x2 1.87 2.6 0.06 0.09 4x4 2.67 3.7 0.08 0.12

Key features: Carrier Aggregation [1] Motivation for carrier aggregation Higher data rate support in wider bandwidth LTE-Advanced should extend up to 100MHz Backward compatible co-existence with LTE and LTE-Advanced in IMT carrier bands Aggregation of multiple component carriers into overall wider bandwidth Each component carrier can appear as LTE carrier to LTE UE System bandwidth, e.g., 100 MHz CC, e.g., 20 MHz UE capabilities Frequency 100-MHz case 40-MHz case 20-MHz case (Rel. 8 LTE) KRnet 2011 8/28

Key features: Carrier Aggregation [2] Two types of aggregation Case 1: Contiguous BW aggregation Aggregated allocation of contiguous carrier BWs Case 2: Non-contiguous BW aggregation Aggregated allocation of separated carrier BWs Contiguous carrier aggregation in a same frequency band Maybe difficult to find out frequency bands where maximum of 200MHz (FDD) can be allocated in contiguous manner Non-contiguous carrier aggregation in different frequency band Possibility for wider total bandwidth without correspondingly wider contiguous spectrum Area of practical interest from operator perspective May have some feasibility, complexity and cost issues Carrier aggregation in Rel.10 Intra band aggregation: 20MHz + 20MHz (UL & DL, band 1) Inter band aggregation: DL: 10MHz (band 1) + 10MHz (band 5) UL: no aggregation KRnet 2011 9/28

Key features: enhanced DL MIMO [1] Enhanced DL MIMO in Rel.10 LTE-Advanced Support of higher order MIMO up to 8 streams in DL Satisfy the requirement for peak spectrum efficiency, i.e., 30 bps/hz Enhanced MU-MIMO support Dynamic switching between SU-MIMO and MU-MIMO Max. 8 streams Dynamic switching btw. SU/MU MIMO Higher-order MIMO up to 8 streams Enhanced MU-MIMO KRnet 2011 10/28

Key features: enhanced DL MIMO [2] DM-RS based MIMO for LTE-Advanced CRS-based (LTE) DMRS-based (LTE-Advanced) Properties RS is used for both demodulation and measurement Precoding information should be informed to a UE Physical antenna ports can be seen by a UE RS power boosting is necessary for supporting various type of geometry UE DMRS is used for demodulation only Complementary RS is needed for the measurement Precoding information is not needed for demodulation Virtual antenna ports (stream) can be seen by a UE Precoding gain can be exploited for channel estimation Power boosting may not be needed KRnet 2011 11/28

Key features: enhanced DL MIMO [3] Performance Improvement by MU-MIMO for LTE- Advanced excerpt from TR 36.814 Cell spectral efficiency (bit/sec/hz/cell) Cell-edge user spectral efficiency (bit/sec/hz/user) Cell spectral efficiency (bit/sec/hz/cell) Cell-edge user spectral efficiency (bit/sec/hz/user) Source 1 2.77 0.110 Source 5 2.74 0.091 Source 15 2.56 0.070 Rel-8 SU-MIMO (2 x 2, L=3) 2.23 0.079 3GPP target 2.40 0.070 Performance of DL MU-MIMO 2 x 2 (C) (3GPP Case1, FDD) Source 1 5.45 0.210 Source 4 4.49 0.205 Source 5 4.42 0.223 Source 11 4.63 0.196 Source 15 4.45 0.182 Rel-8 SU-MIMO (4 x 4, L=3) 3.41 0.143 3GPP target 3.70 0.120 Performance of DL MU-MIMO 4 x 4 (C) (3GPP Case1, FDD) KRnet 2011 12/28

Key features: UL MIMO [1] UL MIMO in Rel.8 LTE UL MIMO was not supported for complexity reason 64QAM was introduced instead during Rel.8 time frame Only antenna switching Tx diversity is defined in Rel.8 LTE MU-MIMO was supported in an implicit manner (specification transparent way) UL MIMO in LTE-Advanced Crucial in satisfying 3GPP s own peak spectrum efficiency requirement The number of transmit antennas in UL Up to 4 transmit antenna are supported (4 layer transmission) Design issue for UL MIMO Multiple access scheme in case of UL SU-MIMO Number of codewords Precoder design (in consideration of PAPR characteristics) Transmit diversity for PUCCH RS modification: DM-RS, SRS (Sounding Reference Signal) Max. 4 streams Two antennas with one amplifier Two antennas with two amplifiers Four antennas with four amplifiers KRnet 2011 13/28

Key features: UL MIMO [2] Performance Improvement from 2 by 4 MIMO excerpt from TR 36.814 Cell spectral efficiency (bit/sec/hz/cell) Cell-edge user spectral efficiency (bit/sec/hz/user) Antenna Config. A Source 3 2.46 0.112 Source 15 2.26 0.093 Source 18 2.36 0.086 Rel-8 SIMO (1 x 4) 1.95 0.075 3GPP target 2.00 0.070 Antenna Config. B Cell spectral efficiency (bit/sec/hz/cell) Cell-edge user spectral efficiency (bit/sec/hz/user) Source 1 2.33 0.070 Source 3 2.37 0.118 Source 4 2.43 0.096 Source 5 2.34 0.080 Source 15 2.01 0.096 Source 18 2.12 0.087 Rel-8 SIMO (1 x 4) 2.00 0.075 3GPP target 2.00 0.070 KRnet 2011 14/28

Key features: eicic [1] Dominant Interference in case of Heterogeneous cell deployment Consist of deployments where low power nodes are placed throughout a macrocell layout The interference characteristics in a heterogeneous deployment can be significantly different than in a homogeneous deployment Mainly, two different heterogeneous scenarios are under consideration Macro-Femto (CSG: Closed Subscriber Group) case Macro-Pico case Macro enb Macro UE Macro enb Home UE Pico UE Pico enb Macro UE Home enb KRnet 2011 15/28

Key features: eicic [2] ICIC in Rel.8/9 LTE Frequency domain ICIC: not sufficient in case of HetNet scenario Because DL control channels (PCFICH/PHICH/PDCCH) are spread over the entire system bandwidth With a cell-specific interleaving structure ICIC for LTE-Advanced Cooperative Silencing (i.e., time domain ICIC technique) Subframe Aggressor UE_A Freq PDSCH Almost Blank Subframe Freq Time UE_V1 PDSCH Victim UE_V2 UE_V3 PDSCH PDSCH Time KRnet 2011 16/28

Key features: eicic [3] Coordination between the two cell layers Macro-pico (with pathloss-based cell selection) Macro-femto (with closed home enbs) ABS pattern ABS pattern ABS Macro enb Macro UE Macro enb ABS Home UE Pico UE Pico enb Macro UE Home enb KRnet 2011 17/28

Key features: eicic [4] Performance improvement by cooperative silencing Cooperative silencing together with cell range expansion can provide performance benefits under macro-pico scenario UE Throughput [kbps] and Pico-UE Ratio for configuration 4b (defined in TR 36.814) Mean 5% worst Pico-UE Ratio Macro-only 767 (Gain) 204 (Gain) 0% Reuse-1 3410 (345%) 363 (78%) 44% Silencing 4588 (498%) 184 (-10%) 44% Silencing + 6 db Bias 4282 (458%) 359 (94%) 61% Silencing + 12 db Bias 4038 (427%) 691 (239%) 75% Reference: R1-103741, LG Electronics KRnet 2011 18/28

Key features: Relay [1] What is relay? A tool to improve e.g. the coverage of high data rates, group mobility, temporary network deployment, the celledge throughput and/or to provide coverage in new areas Rel-10 relay deployment scenario Stationary relay Single hop relay No Inter relay handover Indoor Hot Spot Dead Spot (Building Shadows) Multi-hop Relay Coverage to isolated Areas Urban Hot Spot Group Mobility Dead Spot (Valley Between Buildings) Coverage Extention KRnet 2011 19/28

Key features: Relay [2] Rel-10 Relay Fixed relay No support for CA operation Layer up to 4 Cell ID Half duplex (Inband relay, Type 1 relay) TDM resource partitioning Fake MBSFN subframe Timing offset R-PDCCH enb-to-rn transmission One subframe Control Data Control Transmission Gap ( Fake MBSFN subframe ) No RN-to-UE transmission RN-to-UE transmission KRnet 2011 20/28

Other features [1] SON (Self Organizing/Optimizing Network) Reduction of Total Cost of RAN Ownership Highly probable situation of using small remote enbs (e.g. femto cell) for coverage extension and throughput enhancement SON can reduce the total cost of RAN ownership (CAPEX and OPEX) by reducing human oriented manual operations Proactive reaction of user experience always-on RAN monitoring for proactive reactions to user experiences Self Deployable Cell Always on RAN performance monitoring based on enb and UE reporting. O&M Measurement data Configuration profiles Automatic Common Channel Power Control Very low throughput reporting with location info. HO failure reporting with location info KRnet 2011 21/28

Support of HeNB Other features [2] Preferential service for closed subscriber group (CSG) Gateway to Home Network Local IP access for enterprises Femto-cell for enhancing coverage or capacity Lower Price Preferential Service High Data Rate Exclusive Access HeNB usage KRnet 2011 22/28

Other features [3] MDT (Minimization of Driving Test) One important ingredients of SON in 3GPP BEFORE AFTER Extensive manual driving tests are required for coverage optimization There are many UEs who can help NW collect the statistics for coverage optimization KRnet 2011 23/28

Other features [4] MTC (Machine Type Communication) KRnet 2011 24/28

Other features [5] CoMP (Cooperative Multipoint Transmission & Reception) Not a part of Rel.10 Likely to be standardized in Rel.11 LTE-Advanced Generally known as distributed MIMO or network MIMO Backhaul Multi-cell MIMO user : Single-cell MIMO user : enb A DL UE Data CSI X2 interface enb B UE enb C KRnet 2011 25/28

Summary of Self-Evaluation Results From the self evaluation activities for LTE-Advanced, it was found that For LTE Release 10, Both FDD and TDD RIT Component meet the minimum requirements of all 4 required test environments The complete SRIT meets the minimum requirements of all 4 required test environments. Baseline configuration exceeds ITU-R requirements with minimum extension LTE-Advanced is based on LTE Rel.8 and it is the long term evolution of LTE LTE Rel-8 can fulfill the most of requirements without any enhanced techniques. Only small updates from Rel.8 can fulfill the requirements even in the very tough conditions (UMi and UMa). More advanced configurations, e.g. CoMP, with further enhanced performance Many (18) companies including LG Electronics participated in the simulations, ensuring high reliability Self evaluation reports are captured in section 16 of Technical Report TR 36.912 KRnet 2011 26/28

References [1] 3GPP, RP-091005, Proposal for Candidate Radio Interface Technologies for IMT-Advanced Based on LTE Release 10 and Beyond [2] ITU-R, Report ITU-R M.2133 Requirements, evaluation criteria, and submission templates for the development of IMT-Advanced [3] ITU-R, Report ITU-R M.2134 Requirements related to technical system performance for IMT-Advanced Radio interface(s) *4+ 3GPP, TR 36.913, Requirements for further advancements for E-UTRA (LTE-Advanced), V8.0.0, June 2008 [5] 3GPP, RP-090743, TR TR36.912 v9.0.0, Feasibility study for Further Advancements for E-UTRA, September 2009 [6] 3GPP, RP-090744, Annex A3: Self-evaluation results *7+ 3GPP, TS 36.300 v10.3.0, Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN), Overall description, Stage 2 *8+ 3GPP, TR 36.814 v9.0.0, Further advancements for E-UTRA physical layer aspects *9+ 3GPP, TS 36.211 v10.1.0, Evolved Universal Terrestrial Radio Access (E-UTRA), Physical channels and modulation *10+ 3GPP, TS 36.212 v10.1.0, Evolved Universal Terrestrial Radio Access (E-UTRA), Multiplexing and channel coding *11+ 3GPP, TS 36.213 v10.1.0, Evolved Universal Terrestrial Radio Access (E-UTRA), Physical layer procedure *12+ 3GPP, TS 36.214 v10.1.0, Evolved Universal Terrestrial Radio Access (E-UTRA), Physical layer measurement [13] 3GPP, TS 36.216 v10.2.0 on Physical layer for relaying operation KRnet 2011 27/28

KRnet 2011 28/28 Thank You!!