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3GPP Long Term Evolution Introduction

3GPP Long Term Evolution Introduction. LTE TIS 2009-12. Agenda. 1. LTE & 3GPP Standard 2. LTE Network System 3. LTE Key Technologies 4. LTE TDD Characteristics. 1. LTE & 3GPP Standard. About 3GPP LTE.

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3GPP Long Term Evolution Introduction

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  1. 3GPP Long Term EvolutionIntroduction LTE TIS 2009-12

  2. Agenda • 1. LTE & 3GPP Standard • 2. LTE Network System • 3. LTE Key Technologies • 4. LTE TDD Characteristics

  3. 1. LTE & 3GPP Standard

  4. About 3GPP LTE Since November 2004, 3GPP has been working on the Long Term Evolution (LTE) for enhancements to the Universal Mobile Telecommunications System (UMTS), and focus on adopting 4G technology. Specs (Rel-8) were finalized and approved in January 2008. LTE-Advanced study phase in progress. Target on deployment in 2010. By 2015, subscriptions could exceed 400 million, and revenues from LTE could represent more than 15% of all mobile revenues. http://www.3gpp1.net/New-UMTS-Forum-report-forecasts

  5. LTE Milestone in 3GPP Standard Evolution Rel’99 Rel’4 Rel’5 Rel’6 Rel’7 Rel’8 Rel’9/10 3GPP Release UMTS FDD DCH up to 2Mbps Core Netw. Evolution FDD repeaters 1.28Mcps TDD HSDPA Multimedia sub-system HSUPA MBMS HSPA+ i.e. MIMO, CPC, DL 64-QAM, UL 16-QAM LTE

  6. 3GPP Requirements For LTE Spectrum efficiency • DL : 3-4 times HSDPA for MIMO(2,2) • UL : 2-3 times E-DCH for MIMO(1,2) Frequency Spectrum : • Scalable bandwidth : 1.4, 3, 5, 10, 15, 20MHz • To cover all frequencies of IMT-2000: 450 MHz to 2.6 GHz Peak data rate(scaling linearly with the spectrum allocation) • DL : > 100Mb/s for 20MHz spectrum allocation • UL : > 50Mb/s for 20MHz spectrum allocation Capacity • 200 users for 5MHz, 400 users in larger spectrum allocations (active state) Latency • C-plane : < 100ms to establish U-plane • U-plane : < 10ms from UE to server Coverage • Performance targets up to 5km, slight degradation up to 30km Mobility • LTE is optimized for low speeds 0-15km/h but connection maintained for speeds up to 350 or 500km/h • Handover between 3G & 3G LTE • Real-time < 300ms • Non-real-time < 500ms

  7. LTE • >100 Mb/s DL • >50 Mb/s UL • 0.005 € • H/O with • GSM,UMTS, • CDMA… • <10ms Increased Performances & Reduced Costs with LTE HSPA • 14.4 Mb/s DL • 5.7Mb/s UL • 60ms • 0.03 € • H/O with • GSM UMTS • 384kbps DL • 128kbps UL • 120ms • 0.06 € EDGE • 220kbps DL • 750ms • Throughput • Latency • Cost per Megabyte* • Mobility • Roaming • * Source: Analysis Research, 2006

  8. LTE landscape

  9. 2. LTE Network System

  10. eNodeB cell site node • S1-MME: control plane between eNodeB and MME • S1-U: user plane between eNodeB and SAEGW 3GPP LTE system architecture • S1: interface between an eNB and an EPC, providing an interconnection point between the E-UTRAN and the EPC. It is also considered as a reference point. • X2: logical interface between two eNBs. Whilst logically representing a point to point link between eNBs, the physical realization need not be a point to point link.

  11. AP AP AP AP AP EUTRAN Network Architecture eUTRAN EPC LTE-Uu MME S1-MME eNB UE S1U S1-MME S1-MME X2C X2U AGW X2C X2U LTE-Uu S1U S1U X2C X2U eNB eNB UE IP Transport Network (IP Cloud) X2C - X2 Cplane S1U - S1 Uplane X2U - X2 Uplane S1-MME - S1 Cplane AP - Access Point (for IP cloud)

  12. Internet PSTN PSTN Internet GGSN MSC aGW SGSN RNC eNode-B eNode-B eNode-B Node-B Node-B Node-B Flat Architecture Low latency RTT: 10 ms instead of 60 ms for HSPA Short TTI (1 ms instead of 2ms for HSPA) and the flat architecture Backhaul based from day 1 on IP / MPLS transport

  13. 3GPP architecture 4 functional entities on the control plane and user plane 3 standardized UP & CP interfaces 3GPP LTE architecture 2 functional entities on the user plane: eNodeB and ASGW SGSN control plane functions => ASGW & MME RNC control plane functions => MME & eNodeB Less interfaces, some functions will disappear 4 layers into 2 layers Evolve GGSN  integrated ASGW Moving SGSN functionalities to ASGW. RNC evolutions to RRM DB on a IP distributed network for enhancing mobility management. Part of RNC mobility function being moved to ASGW & eNodeB Control plane Control plane User plane User plane ASGW ASGW AGW GGSN GGSN MME MMF MMF SGSN SGSN RNC RNC eNodeB eNodeB eNodeB NodeB NodeB Network Simplification: From 3GPP to 3GPP LTE

  14. IMS 3GPP System Architecture EvolutionMobility by “Single Gw” or Mobile IP Multimedia Stratum Network Stratum (AIPN) Other IP Access 3GPP or non-3GPP (e.g. I-WLAN, 3GPP2, LTE also) MIP HA ASGW L3 AAA (e.g. PCRF) GGSN GAN PS & Evolved PS Core Evolved UTRAN GERAN UTRAN Access System Stratum PCRF – Policy and Charging Rules Function

  15. S1 Architecture • Key points • Flex Architecture for both interfaces S1-U and S1-MME • MME and SAE GW can be split in two logical nodes or combined in the same AGW • 2 entities for control plane: eNB & MME (S1-MME interface) • eNB: UMTS NodeB plus UMTS RNC (RRC, Radio Bearer Management…) • MME: UMTS MM and SM functions • 2 entities for user plane: eNB & SAE GW (S1-U interface) • eNB: UMTS NodeB plus UMTS RNC (PDCP/RLC/MAC…) • SAE GTW: (Serving Gateway) UMTS packet core user plane • No Macro-diversity

  16. Functional Mapping (from TR 25.813) • MME Functions • Idle mode mobility • Tracking area update • Maintenance of equivalent tracking areas • Idle mode access restrictions • Security Key management • S1 connection establishment • Idle to active mode transition • Session management • RAB and QoS • S1 handling during HO • SAE GW radio related functionality • Idle S1 GTP bearer end point • QoS handling & tunnel mgt • S1 path switch during Handover

  17. Functional Mapping (from TR 25.813) • LTE functions in eNode-B • Selection of aGW at UE attachment • Routing towards aGW at UE initial access • NAS messaging encapsulated by RRC for tx over radio • Scheduling and transmission of paging messages • Scheduling and transmission of System Information • Dynamic allocation of resources to UEs in both UL and DL • Configuration and provision of eNB measurements • Radio Bearer Control • Radio Admission Control • Access restrictions in Active state • Connection Mobility Control in LTE_ACTIVE state • Active mode Handover handling • RRC, header compression, encryption, RLC, MAC, PHY • Security of User plane and RRC • Encryption of both in PDCP, integrity check of RRC • Scheduling and associated QoS handling

  18. RRM Functions (1/3) • Inter-Cell Interference Coordination (ICIC): • Managing the radio resources (notably the radio resource blocks) such that inter-cell interference is kept under control • Load Balancing (LB): • Influence the traffic load distribution in such a manner that radio resources remain highly utilized and the QoS of in-progress sessions are maintained to the possible extent (may result in handover decisions) • Inter-RAT Radio Resource Management: • In connection with inter-RAT mobility (taking into account the involved RAT resource situation, UE capabilities & operator policies)

  19. RRM Functions (2/3) • Connection Mobility Control (CMC): • Management of radio resources in connection with idle or active mode • Mobility of radio connections: handover decisions based on UE & e-NodeB measurements + potentially: neighbour cell load, traffic distribution, transport & HW resources & operator defined policies • Radio Bearer Control (RBC): • Establishment, maintenance & release of Radio Bearers • Taking into account overall resource situation, QoS requirements of in-progress sessions and of the new service) • Radio Admission Control (RAC): • Admit or reject the establishment requests for new radio bearers (taking into account overall resource situation, QoS requirements & priority levels)

  20. RRM Functions (3/3) • Packet Scheduling (PSC) • Allocate/De-allocate resources (including buffer, processing resources & resource blocks) to UP & CP packets including: • Selection of RB, whose packets are to be scheduled • Managing the necessary resources (e.g. power levels, specific resource blocks)

  21. LTE ARCHITECTURE – Control Plane Layout over S1 UE eNode-B MME

  22. LTE ARCHITECTURE – Control Plane Layout over S1 • NAS sub-layer performs: • Authentication • Security control • Idle mode mobility handling • Idle mode paging origination • RRC sub-layer performs: • Broadcasting • Paging • Connection Mgt • Radio bearer control • Mobility functions • UE measurement reporting & control • PDCP sub-layer performs: • Integrity protection & ciphering UE eNode-B MME

  23. SAE Gateway LTE ARCHITECTURE – User Plane Layout over S1 UE eNode-B MME

  24. SAE Gateway LTE ARCHITECTURE – User Plane Layout over S1 • Physical sub-layer performs: • DL: ODFMA, UL: SC-FDMA • HARQ • UL power control • Multi-stream transmission & reception (i.e. MIMO) • PDCP sub-layer performs: • Header compression • Ciphering • RLC sub-layer performs: • Transferring upper layer PDUs • In-sequence delivery of PDUs • No error correction through ARQ • Duplicate detection • Flow control • Concatenation/re-assembly of packets • MAC sub-layer performs: • Scheduling • Error correction through HARQ • Priority handling across UEs & logical channels • In-sequence delivery of RLC PDUs • Multiplexing/de-multiplexing of RLC radio bearers into/from PhCHs on TrCHs UE eNode-B MME

  25. From UE Power-up to Active Connection Cell search procedure Power-up LTE Network Frequency/Timing acquisition Acquisition p-SCH, s-SCH & Reference Signal Cell Id determination SIB message Idle CCPCH/PDSCH Message from UE (origination, registration, …) Access PRACH/PUSCH Registration procedure Registration PDSCH/PUSCH DL traffic PDSCH Traffic UL traffic PUSCH

  26. 3. LTE Key Technologies

  27. WiMAX 802.16e-2005 WiMAX 802.16m OFDM All-IP MIMO AAS OFDM All-IP MIMO AAS CDMA2000 EV-DO Rev.A EV-DO Rev.C OFDM All-IP MIMO AAS IP transport 3G LTE HSPA+ HSDPA / HSUPA OFDM All-IP MIMO AAS All-IP MIMO IP Transport Innovative Technologies Emerging in Standards Beyond 2006 2007 2008 2009 1st Commercial launches OFDM, All-IP, MIMO & AAS are the key cornerstones of new & future wireless standards

  28. MIMO 2x2, 20Mbps/5MHz Mobile PSTN 16QAM UMTS / HSDPA CDMA / EVDO WiMAX 16e POTS SISO, 10Mbps/5MHz Access Core Local Internet OFDM MIMO Mobility IMS VoIP SIP 802.11, Mesh WiMAX 16d IP Fixed Corporate DSL / Cable Ethernet Key LTE Features to Overcome Challenges • OFDMA • Increased spectral efficiency • Simplified Rx design  Cheaper UE • Scalable - Go beyond 5MHz limitation • MIMO: antenna technology • Multiple-input, multiple-output • Overcome multi-path interference • Peak rate breakthrough • IP Core: flat, scalable • Low latency: 10 ms (60 ms for HSPA) • Short TTI: 1 ms (2ms for HSPA) • Backhaul based on IP / MPLS transport • Fits with IMS, VoIP, SIP

  29. ISI + High data rates Mobile environment t t • Short symbol duration • High-order modulations  Low inter-symbol distance • Multi-path • High delay spread t Why OFDMA? • Suitable for MIMO implementation • Ease Time & Frequency scheduling • Less receiver complexity • Robust to frequency-selective fading • Robust to Inter-Symbol Interference (i.e. ISI)

  30. OFDMA Principle Power Time N-OFDM Symbol duration Frequency Sub-carrier spacing = Δf Bandwidth User#1 User#2 User#3 User#4

  31. eNode-B LTE Access Technologies OFDM UL Bdw DL Bdw FDD Frequence duplex SC-FDMA OFDMA Frame … UL slot DL slot … LTE UE TDD Time Time duplex SC-FDMA OFDMA

  32. UMTS LTE SC-FDMA Transmitter/receiver

  33. OFDM Advantages & Drawbacks • Advantages • Can easily adapt to severe channel conditions without complex equalization • Robust against narrow-band co-channel interference • Robust against Intersymbol interference (ISI) and fading • High spectral efficiency • Efficient implementation using FFT • Low sensitivity to time synchronization errors • Tuned sub-channel receiver filters are not required (unlike traditional FDM) • Facilitates Single Frequency Networks • Drawbacks • Sensitive to Doppler shift and to frequency synchronization problems • High Peak-to-Average Power Ratio

  34. MIMO Principle • Transmission • Of several independent data streams in parallel • Over uncorrelated antennas (i.e. separated by 10) • Reception • Over NTx x NRx (ideally) uncorrelated paths • Theoretical maximum rate increase factor = Min (NTx , NRx) • In a rich scattering environment; no gain in LOS environment • Practical gain in urban areas = 1.2 to 1.5 for 2x2 MIMO • Boosting capacity (DL and UL) and peak burst rate (DL), • Sensitive to SINR

  35. MIMO in 3GPP Rel’8 • In DL: 1, 2 or 4 TX antennas and 1, 2 or 4 RX antennas • Allowing multi-layer transmissions with up to four streams • MU-MIMO: allocation of different streams to different users • MU-MIMO • SU-MIMO In UL: • only MU-MIMO no SU-MIMO • Choice for MIMO mode at the Node B side • Restricted by the UE capability (e.g. number of RX antennas) • Adapted slowly (e.g. once in a com, or every xiple of 100ms) • Rank adaptation (and/or antenna subset selection) is supported for evaluation • The number of codewords transmitted to a UE is controlled through rank adaptation • MU-MIMO to a UE is determined either dynamically or semi-statically • Candidates for the UE feedback information • MIMO channel state information • Channel quality indicator (CQI), which may be used by the Node B to decide a MCS level(s).

  36. CombiningRx packets CombiningRx packets Hybrid-ARQ Principle Packet transmission R99 on a DCH channelThe erroneous block is deleted! RLC NACK RLC Re-Transmission UE RLC ACK ServingRNC Node-B Packet transmission R5 on theHS-DSCH channelThe erroneous block is stored for recombination H-ARQ NACK H-ARQ Re-Tx H-ARQ ACK ServingRNC RLC ACK Node-B UE Packet transmission LTE H-ARQThe RTT is shorter due to eNode-B concentration H-ARQ NACK H-ARQ Re-Tx H-ARQ ACK eNode-B UE

  37. LTE RRC States • Cell re-selection • Paging • TA update RRC_Idle (Idle state) Active connection (i.e. traffic) Periodic TA Update time-out Inactivity De-registration / PLMN change RRC_NULL (detached state) RRC_CONNECTED (active state) No MM context of UE in eNB / Core network Registration Traffic / HO

  38. 4. LTE TDD Characteristics

  39. TD-LTE Emerging from the FDD Shadow • TD-LTE was a key part of overall LTE standard to prevent repeat of 3G TDD failure • Alignment achieved to both Europe TDD and China TD-SCDMA, achieved to ensure easy evolution and spectrum access • Standard/LSTI: though TD-LTE standard started later than LTE FDD, China Mobile has successfully accelerated the TDD IOT timeline to be in line with FDD • TD-LTE led by China Mobile • TD-LTE is an important part of “Next Generation BB Wireless Network” identified by state M&L Projects, which is aligned with China’s Innovation Policy to be “Innovation Country” • CMCC driving TD-LTE as its next generation broadband wireless-IP network to replace GSM and TD-SCDMA and compete with WCDMA/LTE FDD operators • Unique Global Alignment • Vodafone, CMCC, Verizon have a joint agreement to promote the success of TD-LTE • United to drive success of ecosystem • Other operator groups asking for RFx and Trials to evaluateTD-LTE to allow use of unused spectrum assets

  40. Commonalities between TD-LTE and LTE FDD • The LTE infrastructure includes … • Terminal, eNB, MME, PCRF, sGW and PDN GW • TD-LTE and LTE FDD are mainly different by dedicated realization of physical layer • Hence, they are invisible to the higher layers (except for parameter configurations). The MME, PCRF and xGW are virtually identical for FDD and TDD systems • Differences are in eNB and terminals with respect to FDD and TDD due to the difference in air interface design/physical layer. Therefore, it is beneficial to exploit this similarity to build one system that can support FDD and/or TDD. SGW PDN GW MME PCRF

  41. Main Differences between TD-LTE and LTE FDD Summary • TD-LTE needs to support various TDD UL/DL allocations & needs to support coexistence with other TDD systems • Resulting TD-LTE differences • Frame structure (3GPP TS36.300/TS36.211) • Introduction of “frame structure 2” for TD-LTE • Introduction of special subframe for switching from DL to UL and coexistence with other TDD systems • System information • Cell broadcasts the TDD UL/DL configuration information • Random Access • Additional short random access format for special subframe/UpPTS • Multiple random access channels in a subframe • UL multi TTI scheduling • Multi-subframe scheduling for UL • For heavy UL configurations to save DL control overhead • ACK/NACK bundling/multiplexing on UL control channel • For heavy DL configurations to save UL control overhead • H-ARQ process number & timing • Variable number of H-ARQ processes depending on the UL/DL allocation • Power control timing • SRS configuration • Different TD-LTE spectrum allocation (3GPP TS36.101)

  42. LTE Radio Frame Structure • Two types of radio frame • Type 1 • Applicable to both FDD and TDD • Type 2 • Applicable to TDD only DwPTS: Pilot for DL UpPTS: Special uplink time slot

  43. TD-LTE Frame Structure - Uplink and Downlink Configuration – 3GPP TS36.211 Configuration 1 is supported in first release. Configuration 2 is planned in TLA2.1 (2010 Q2).

  44. H-ARQ • Uplink H-ARQ • Downlink H-ARQ • Variable number of H-ARQ processes depending on the UL/DL allocation

  45. Frequency Bands & Bandwidths – 3GPP TS36.101 UMTS FDD frequency band (60 MHz) New IMT-2000 frequency band (70 MHz) New IMT-2000 frequency band (50MHz) TD-SCDMA main frequency band (15 MHz) TD-SCDMA supplementary frequency band (40 MHz) New IMT-2000 frequency band (100MHz) TD-SCDMA supplementary frequency band (100MHz) Additional bands for approval in Rel 9 FDD Band 20 to be integrated (UL 3410-3500 MHz / DL 3510-3600 MHz) TDD Band 41 to be integrated (3400-3600 MHz)

  46. www.alcatel-lucent.com

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