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Day two 10 november 2012 Day two 10 november 2012 Presentation Transcript

  • Jakarta 10 November 2012 Arief Hamdani Gunawan1. Introduction to LTE 5. LTE Radio Procedures2. OFDMA 6. LTE Uplink Physical Channels and Signals3. SC-FDMA 7. LTE Mobility4. LTE Network and Protocol 8. LTE Test and Measurement
  • Day Two:10 November 2012 Arief Hamdani Gunawan
  • Session 5: LTE Radio Procedures•LTE Initial Access•Downlink physical channels and signals•Cell search in LTE•Primary Synchronization Signal•Secondary Synchronization Signal•Cell search in LTE, reference signals•Downlink Reference Signals•Cell Search in LTE, essential system information•System Information Broadcast in LTE•Random Access Procedure•How to derive information in LTE•Hybrid ARQ in Downlink•Default EPS Bearer Setup
  • LTE Initial Access
  • Downlink physical channels and signals
  • DL Physical Layer Procedures• Cell search and synchronization• Scheduling – Dilakukan di base station (eNodeB) – PDCCH (Phy DL Control Channel) menginformasikan alokasi time/freq resource dan format transmisi yang digunakan kepada user. – Scheduler mengevaluasi berbagai tipe informasi (parameter QoS, pengukuran dari UE, kapabilitas UE, buffer status)• Link Adaptation – Skema modulasi dan coding untuk shared data channel diadaptasi sesuai dengan kualitas link radio. – Untuk tujuan ini, UE secara teratur melaporkan Channel Quality Indicator (CQI) ke eNodeB.• Hybrid ARQ (Automatic Repeat Request) 6
  • Cell Search in LTE
  • Synchronization & Cell Search• UE yang ingin mengakses suatu sel LTE, terlebih dahulu harus melakukan prosedur Cell Search.• Cell Search terdiri dari serangkaian tahapan sinkronisasi, dimana UE menentukan parameter waktu & frekuensi yang diperlukan untuk mendemodulasi sinyal DL dan untuk mengirimkan sinyal UL dengan timing yang tepat.• Tiga kebutuhan sinkronisasi utama: – Symbol timing acquisition – Carrier frequency synchronization – Sampling clock synchronization 8
  • Case Study Cell Search for Multiple Bandwidths - Problem• LTE offers system flexibility by supporting systems and UEs of multiple bandwidths.• Challenge in synchronization & bandwidth detection.• Unbalance traffic loads may result 9
  • Case Study Cell Search for Multiple Bandwidths - Solution Step 1: Cell search using synchronization channel detect center 1.25 spectrum •The UE first detect the central of entire 20-MHz spectrum part of the spectrum regardless of Step 2: the transmission bandwidth BCH reception capability of the UE and that of the cell site (BTS). Step 3: •UE moves to the transmission UE shifts to the center of carrier frequency assigned bandwidth according to the UE by the system and initiates data transmission capability for actual communicationSource: 3GPP R1-061651, “3GPP TR 25.814 v 1.5.0” 10
  • Synchronization SequenceDua prosedur cell search dalam LTE :• INITIAL SYNCHRONIZATION – UE mendeteksi suatu sel LTE dan mendekode semua informasi yang diperlukan untuk registrasi. – Diperlukan pada saat UE di-ON-kan atau ketika kehilangan koneksi dengan serving cell.• NEW CELL IDENTIFICATION – Dilakukan ketika UE sudah terhubung ke suatu sel LTE dan sedang dalam proses mendeteksi suatu sel tetangga baru. – Dalam hal ini UE melaporkan hasil pengukuran yang terkait dengan sel baru ke serving cell, sebagai persiapan untuk handover. 11
  • Cell Search procedure RS : Reference Signal PBCH : Physical Broadcast Channel PSS : non-coherent detection SSS : non-coherent/coherent detection• PSS (Primary Synchronization Signal) dan SSS (Secondary Synchronization Signal) adalah kanal-kanal fisik yang di-broadcast dalam setiap sel.• Pendeteksian dua kanal ini : – memungkinkan dilakukannya sinkronisasi waktu & frekwensi. – memberikan identitas phy layer dari sel dan panjang cyclic prefix kepada UE. – memberitahu UE apakah sel menggunakan FDD atau TDD. 12
  • Primary Synchronization Signal
  • Secondary Synchronization Signal
  • PSS and SSS frame and slot structure in FDD 15
  • PSS and SSS frame and slot structure in TDD 16
  • Cell search in LTE, reference signals
  • Downlink reference signals
  • Reference Signals & Channel Estimation• Berbeda dengan jaringan berorientasi paket, LTE tidak menggunakan PHY Preamble untuk memfasilitasi estimasi carrier offset, estimasi kanal, sinkronisasi waktu, dsb.• Sebaliknya LTE menggunakan sinyal referensi khusus yang disisipkan dalam PRB.• Sinyal referensi tsb dikirimkan selama simbol OFDM pertama dan kelima dari setiap slot untuk short CP, dan simbol OFDM pertama dan ke-empat untuk long CP.• Simbol-simbol referensi dikirimkan setiap selang 6 subcarrier.• Dalam LTE downlink, terdapat 3 tipe RS : – Cell-specific RS – UE-specific RS – MBSFN-specific RS 19
  • DL Reference Signal Structure for 2 & 4 Antenna Transmission 20
  • RS-aided Channel Estimation• Problem estimasi kanal berhubungan dengan model kanal yang diasumsikan, yang ditentukan oleh karakteristik propagasi fisik, termasuk jumlah antena Tx/Rx, bandwidth transmisi, carrier frequency, konfigurasi sel dan kecepatan relatif antara eNodeB dan UE.• Kondisi propagasi mencirikan fungsi korelasi kanal dalam 3-dimensi, yaitu : domain frekwensi, domain waktu dan domain ruang (spatial).• Frequency-Domain Channel Estimation – menggunakan Linear Interpolation Estimator – menggunakan IFFT Estimator• Time-Domain Channel Estimation – menggunakan Finite & Infinite Length MMSE (Min Mean Squared Error) – menggunakan Normalized Least-Mean-Square• Spatial-Domain Channel Estimation 21
  • Cell search in LTE, essential system information
  • Downlink Physical Channels and Signals P-SCH and S-SCH Physical Downlink Shared Channel Physical Downlink Control Channel Physical Broadcast Channel Physical Control Format Indicator Channel Physical Multicast Channel Physical Hybrid ARQ Indicator ChannelP-SCH : Primary Synchronization ChannelS-SCH : Secondary Synchronization Channel 23
  • LTE Downlink Physical Channels 1 24
  • LTE Downlink Physical Channels 2 25
  • System information broadcast in LTE
  • Random Access Procedure
  • How to derive information in LTE?
  • Indicating PDCCH format
  • Channel Coding & Link Adaptation• Prinsip link adaptation menjadi landasan perancangan suatu interface radio yang efisien untuk trafik data berbasis paket-switched.• Link adaptation dalam LTE dilakukan dengan mengatur laju data informasi yang dikirim (skema modulasi dan channel coding rate) secara dinamis, sesuai dengan kualitas radio link.• Link adaptation mempunyai hubungan yang sangat erat dengan perancangan skema channel coding yang digunakan untuk FEC.• Skema channel coding untuk FEC yang digunakan dalam LTE : – Convolutional Coding – Turbo Coding – LDPC (Low Density Parity Check) coding• Fitur advanced channel coding yang ditambahkan dalam LTE adalah : HARQ (Hybrid Automatic Repeat Request). 30
  • Link Adaptation• UE: Reports the finest possible granularity – The reporting scheme and granularity depend on the radio channel quality variation!• ENB: Receives mobility and quality information – Incremental feedback information forms a rough picture of the radio channel with the first report (s). The granularity gets finer and finer with each report. 31
  • Adaptive Modulation• Adaptive Modulation & Coding memastikan error rate tetap dibawah limit yang dapat diterima, dengan pengaturan modulasi dan coding rate secara dinamis.• Level modulasi yang lebih rendah meningkatkan link budget dan fade margin.• Perubahan lingkungan propagasi menyebabkan perubahan skema modulasi dan coding.• Dalam perencanaan kapasitas, variasi kanal propagasi jangka-panjang harus diperhitungkan. 32
  • Typical SNR Performance of LTE Modulation and Coding 33
  • Adaptive Modulation & Coding 34
  • QoS parameters for QCI
  • Hybrid ARQ in the downlink• ACK/NACK for data packets transmitted in the downlink is the same as for HSDPA, where the UE is able to request retransmission of incorrectly received data packets, – ACK/NACK is transmitted in UL, either on PUCCH (Physical Uplink Control Channel) or multiplexed within PUSCH (Physical Uplink Shared Channel) see description of those UL channels for details), – ACK/NACK transmission refers to the data packet received four sub-frames (= 4 ms) before, – 8 HARQ processes can be used in parallel in downlink.
  • Hybrid ARQ Operation
  • Default EPS bearer setup
  • Session 6: Uplink Physical Channels and Signals •Scheduling of UL Data •UL Frequency Hopping •Demodulation Reference Signal (DRS) in the UL •Sounding Reference Signal (SRS) in the UL •PUSCH power control & timing relation •Acknowledging UL data packets on PHICH •Physical UL Control Channel
  • Uplink physical channels and signals
  • Scheduling of uplink data
  • Uplink Physical Channels and Signals Physical Random Access Channel Physical Uplink Shared Channel Physical Uplink Control Channel• PUSCH (Physical Uplink Shared Channel): used for uplink shared data transmission.• PUCCH (Physical Uplink Control Channel): used to carry ACK/NACK, CQI for downlink transmission and scheduling request for uplink transmission. 42
  • Uplink Data Transmission• Pada uplink, data dialokasikan dalam beberapa resource block (RB).• Ukuran RB untuk uplink sama dengan yang digunakan untuk downlink, tetapi untuk menyederhanakan disain DFT dalam pemrosesan sinyal uplink, tidak semua kelipatan bulat digunakan (hanya kelipatan 2, 3 dan 5).• Interval waktu transmisi uplink adalah 1 ms (sama dengan downlink).• User data dibawa pada Physical Uplink Shared Channel (PUSCH), yang ditentukan oleh BW transmisi dan pola frequency hoping.• Physical Uplink Control Channel (PUCCH) membawa informasi kontrol uplink, seperti : laporan CQI dan informasi ACK/NACK, yang terkait dengan paket-paket data yang diterima pada arah downlink. 43
  • UL frequency hoppingIntra- and inter-subframe hopping,• Intra-subframe hopping. UE hops to another frequency allocation from one slot to another within one subframe,• Inter-subframe hopping. Frequency allocation changes from one subframe to another one,Two types of hopping,• Type I. Explicit frequency offset is used in the 2nd slot, can be configured and is indicated to the UE by resource block assignment / hopping resource allocation field in DCI format 0,• Type II. Use of pre-defined hopping pattern, allocated BW is divided into sub-bands, hopping is done from one sub-band to another from one slot or subframe depending on configured frequency hopping scheme. Screenshots of R&S® SMU200A Vector Signal Generator
  • Demodulation Reference Signal (DRS) in the UL
  • Sounding Reference Signal (SRS) in the UL
  • PUSCH power control & timing relation
  • Random Access• Suatu LTE UE (User Equipment) hanya dapat di-scheduled untuk transmisi uplink, apabila uplink transmission timing-nya sinkron.• Oleh karena itu LTE RACH (Random Access Channel) memainkan peran penting sebagai interface antara non-synchronized UE dan skema transmisi othogonal pada akses radio uplink LTE.• Prosedur LTE random access mempunyai dua bentuk, yaitu : contention- based atau contention-free.• Dalam prosedur contention-based, suatu random access preamble signature dipilih secara acak oleh UE, yang kemungkinan dapat menyebabkan lebih dari satu UE mengirimkan signature yang sama secara simultan.• Dalam prosedur contention-free, eNodeB memiliki opsi untuk mencegah terjadinya contention dengan mengalokasikan suatu dedicated signature kepada UE. 48
  • Contention-based Random Access Procedure Step 1 : Preamble transmission Step 2 : Random Access Response Step 3 : L2/L3 message Step 4 : Contention resolution message 49
  • Contention-free Random Access Procedure Prosedur contention-free random access dapat diterapkan dalam hal diperlukan low latency, seperti handover dan new downlink data. 50
  • UL Transmission Procedures• Uplink scheduling – Dilakukan oleh base station (eNodeB) – PDCCH (Phy DL Control Channel) menginformasikan alokasi time/freq resource dan format transmisi yang digunakan kepada user. – Scheduler mengevaluasi berbagai tipe informasi (parameter QoS, pengukuran dari UE, kapabilitas UE, buffer status)• Uplink Adaptation – Untuk keperluan adaptasi uplink, dapat digunakan : transmission power control, adaptive modulation & channel coding rate, serta adaptive transmission BW.• Uplink timing control – Diperlukan untuk menyelaraskan waktu transmisi dari UE-UE yang berbeda, dengan receiver window dari eNodeB.• Hybrid ARQ 51
  • Acknowledging UL data packets on PHICH
  • Physical Uplink Control ChannelPUCCH carries Uplink Control Information (UCI), when no PUSCH is available,• If PUSCH is available, means resources have been allocated to the UE for data transmission, UCI are multiplexed with user data,UCI are Scheduling Requests (SR), ACK/NACK information related to DL data packets, CQI, Pre-coding Matrix Information (PMI) and Rank Indication (RI) for MIMO,PUCCH is transmitted on reserved frequency regions, configured by higher layers, which are located at the edge of the available bandwidth• Minimizing effects of a possible frequency-selective fading affecting the radio channel,• Inter-slot hopping is used on PUCCH,• A RB can be configured to support a mix of PUCCH formats (2/2a/2b and 1/1a/1b) or exclusively 2/2a/2b,
  • PUCCH• CQI / PMI / RI are only signaled via PUCCH when periodic reporting is requested, scheduled and a periodic reporting is only done via PUSCH
  • Physical Channel Procedure (1/2)
  • Physical Channel Procedure (2/2)
  • Test Carries the DL-SCH and PCH 1 A Cell ID detection, 2 radio frame detection BOperation BW, CP length,MIMO config, cell ID, etc 3 C SCH symbol timing detection, frequency 4 offset detection DRB assignment, transport format, RSN#, HARQ Proc#, TCP Command,Cyclic shift for DMRS, UE 5 E identification
  • Answer SCH symbol timing detection, frequency offset detection Cell ID detection, radio frame detection Operation BW, CP length, MIMO config, cell ID, etc RB assignment, transport format,RSN#, HARQ Proc#, TCP Command, Cyclic shift for DMRS, UE identification Carries the DL-SCH and PCH
  • Session 7: LTE Mobility•Handover (Intra-MME / Serving Gateway)•LTE Interworking with 2G/3G: Two RRC States:Connected and Idle•LTE Interworking with CDMA2000 1xRTT andHRPD•MIMO•LTE MIMO downlink modes•LTE downlink transmitter chain•Downlink transmitter diversity - Space FrequencyBlock Coding (2 Tx antenna case)•Downlink Spatial Multiplexing - codebook basedprecoding•LTE MIMO UL Schemes
  • Logical High Level Architecture for The Evolved System GB GERAN GPRS Core Rx+ Iu SGSN S4 Operator’s UTRAN S6 S7 IP Services (e.g. IMS, PSS, S3 etc,) IASA MME 3GPP SAE S2beNB eNB UPE S5a anchor S5b anchor S1 SGi eNB eNB S2a WLAN 3GPP Evolved RAN (LTE) EPC (SAE) EPDG IP Access Trusted non 3GPP WLAN IP Access Access Network• EPS uses the concept of EPS bearers to route IP traffic from a gateway in the PDN to the UE.• A bearer is an IP packet flow with a defined Quality of Service (QoS) between the gateway and the UE.• The E-UTRAN and EPC together set up and release bearers as required by applications.
  • SAE Bearer Model
  • Overview of the evolved system architecture User and bearer information exchange for inter 3GPP access system mobilityC-Plane : S1-C between eNB and MMEU-Plane : S1-U between eNB and UPE Transfer of subscription and authentication data for user MME : Mobility Management Entity access to the evolved system (AAA UPE : User Plane Entity interface) 3GPP Anchor : Mobility anchor between 2G/3G and LTE access systems (based on GTP) SAE Anchor : Mobility anchor between 3GPP access systems (2G/3G/LTE) and non-3GPP access systems (e.g. WLAN, WiMAX).
  • SAE Architecture – Functions per Element
  • SAE Architecture 3GPP2 Operatordetailed view, non-roaming case, 3GPP2 accesses
  • SAE Roaming supportextending today’s successful model
  • SAE impact on IMS overview
  • Handover (Intra-MME/Serving Gateway)
  • LTE Interworking with 2G/3GTwo RRC states: CONNECTED & IDLE
  • LTE Interworking with CDMA2000 1xRTT and HRPD (High Rate Packet Data)
  • Introduction to MIMO:gains to exploit from multiple antenna usage Transmit diversity (TxD) • Combat fading • Replicas of the same signal sent on several Tx antennas • Get a higher SNR at the Rx Spatial multiplexing (SM) • Different data streams sent simultaneously on different antennas • Higher data rate • No diversity gain • Limitation due to path correlation Beamforming
  • Multiple Antenna Technique: Four Basic Model 71
  • Multiple Antenna Technique Two popular techniques in MIMO wireless systems:Spatial Diversity: Increased SNR Spatial Multiplexing: Increased rate• Receive and transmit diversity mitigates • Spatial multiplexing yields substantial fading and improves link quality increase spectral efficiency 72
  • Spatial DiversityTransmit Diversity• Space-time Code (STC): Redundant data sent over time and space domains (antennas).• Receive SNR increase about linearity with diversity order Nr Nt• Provide diversity gain to combat fading• Optional in 802.16d (2x2 Alamouti STBC), used in 3G CDMA 73
  • Spatial MultiplexingMIMO Multiplexing• Data is not redundant – less diversity but less repetition• Provides multiplexing gain to increase data-rate• Low (no) diversity compared with STC 74
  • MIMO Operation 75
  • Diversity & MIMO 76
  • LTE MIMO: downlink modes• Transmit diversity: – Space Frequency Block Coding (SFBC) – Increasing robustness of transmission• Spatial multiplexing: – Transmission of different data streams simultaneously over multiple spatial layers – Codebook based precoding – Open loop mode for high mobile speeds possible• Cyclic delay diversity (CDD): – Addition of antenna specific cyclic shifts – Results in additional multipath / increased frequency diversity
  • LTE downlink transmitter chain
  • Downlink transmit diversitySpace-Frequency Block Coding (2 Tx antenna case)
  • Downlink spatial multiplexing codebook based precoding
  • LTE MIMO: uplink schemes• Uplink transmit antenna selection: – 1 RF chain, 2 TX antennas at UE side – Closed loop selection of transmit antenna – eNodeB signals antenna selection to UE – Optional for UE to support• Multi-user MIMO / collaborative MIMO: – Simultaneous transmission from 2 Ues on same time/frequency resource – Each UE with single transmit antenna – eNodeB selects UEs with close-to orthogonal radio channels
  • Multi User Scheduling• Scheduler (untuk transmisi unicast) secara dinamis mengontrol resource waktu dan frekwensi mana yang akan dialokasikan kepada suatu user pada suatu waktu tertentu.• DL control signalling memberitahu UE, resource dan format transmisi seperti apa yang sudah dialokasikan.• Scheduler dapat secara dinamis memilih strategi multiplexing terbaik dari beberapa metode yang ada, misalnya : localized atau distributed allocation.• Scheduling berinteraksi erat dengan link adaptation dan HARQ.• Pertimbangan scheduling antara lain didasarkan pada : – minimum & maximum data rate – daya yang tersedia untuk di-share – Persyaratan target BER – parameter QoS – laporan CQI (Channel Quality Indicator) – kapabilitas UE 82
  • Channel-Dependent Scheduling• Shared channel transmission • Scheduling in time and frequency• Select user and data rate on domain instantaneous channel quality – Link adaptation in time domain – Time-domain adaptation used only already in HSPA 83
  • Packet-scheduling framework • Packet scheduler adalah entitas pengendali untuk seluruh proses scheduling. • Berkonsultasi dengan modul LA (Link Adaptation) untuk memperoleh estimasi data rate yang dapat disuport untuk user tertentu dalam sel. • LA dapat menggunakan frequency- selective CQI feedback dari user, untuk memastikan estimasi data rate yang sesuai dengan target BLER tertentu. • Modul Offset calculation dalam proses link-adaptation dapat digunakan untuk menstabilkan performansi BLER dalam kondisi LA yang tidak pasti. 84
  • Quiz MIMO isfirstly introduced on which Release?
  • Session 8: LTE Test and Measurement •LTE RF Testing aspects •eNB Modulation quality measurements •ACLR in DL (FDD) •eNB Performance Requirements •UE RF Testing Aspects •Transmit Modulation •Inband Emission •IQ Component •ACLR Measurement •Receiver characteristics •LTE Wireless device testing from R&D upto conformance •Stages of LTE terminal testing •LTE Terminal Interoperability testing •Test Scenarios for LTE Terminal IOT •LTE Conformance Testing •LTE Terminal Certification •LTE Field Trials
  • System architecture for 3GPP access networks
  • PCRF• It is responsible for policy control decision-making, as well as for controlling the flow-based charging functionalities in the Policy Control Enforcement Function (PCEF) which resides in the P-GW.• The PCRF provides the QoS authorization (QoS class identifier and bitrates) that decides how a certain data flow will be treated in the PCEF and ensures that this is in accordance with the user’s subscription profile.
  • P-GW• The P-GW is responsible for IP address allocation for the UE, as well as QoS enforcement and flow-based charging according to rules from the PCRF.• The P-GW is responsible for the filtering of downlink user IP packets into the different QoS based bearers. This is performed based on Traffic Flow Templates (TFTs).• The P-GW performs QoS enforcement for Guaranteed Bit Rate (GBR) bearers.• It also serves as the mobility anchor for inter-working with non-3GPP technologies such as CDMA2000 and WiMAX networks.
  • S-GW• All user IP packets are transferred through the S-GW, which serves as the local mobility anchor for the data bearers when the UE moves between eNodeBs.• It also retains the information about the bearers when the UE is in idle state (known as ECM-IDLE) and temporarily buffers downlink data while the MME initiates paging of the UE to re- establish the bearers.• In addition, the S-GW performs some administrative functions in the visited network such as collecting information for charging (e.g. the volume of data sent to or received from the user), and legal interception.• It also serves as the mobility anchor for inter-working with other 3GPP technologies such as GPRS and UMTS.
  • MME• The MME is the control node which processes the signaling between the UE and the CN.• The protocols running between the UE and the CN are known as the Non-Access Stratum (NAS) protocols.• The main functions supported by the MME are classified as: – Functions related to bearer management. This includes the establishment, maintenance and release of the bearers, and is handled by the session management layer in the NAS protocol. – Functions related to connection management. This includes the establishment of the connection and security between the network and UE, and is handled by the connection or mobility management layer in the NAS protocol layer.
  • HSS• Home Subscription Server (HSS) is the subscription data repository for all permanent user data. It also records the location of the user in the level of visited network control node, such as MME. It is a database server maintained centrally in the home operator’s premises.• The HSS stores the master copy of the subscriber profi le, which contains information about the services that are applicable to the user, including information about the allowed PDN connections, and whether roaming to a particular visited network is allowed or not. For supporting mobility between non- 3GPP ANs, the HSS also stores the Identities of those P-GWs that are in use. The permanent key, which is used to calculate the authentication vectors that are sent to a visited network for user authentication and deriving subsequent keys for encryption and integrity protection, is stored in the Authentication Center (AuC), which is typically part of the HSS.• In all signaling related to these functions, the HSS interacts with the MME. The HSS will need to be able to connect with every MME in the whole network, where its UEs are allowed to move. For each UE, the HSS records will point to one serving MME at a time, and as soon as a new MME reports that it is serving the UE, the HSS will cancel the location from the previous MME.
  • EPS Connection Management• To reduce the overhead in the E-UTRAN and processing in the UE, all UE- related information in the access network can be released during long periods of data inactivity.• This state is called EPS Connection Management IDLE (ECM-IDLE). The MME retains the UE context and the information about the established bearers during these idle periods.• To allow the network to contact an ECM-IDLE UE, the UE updates the network as to its new location whenever it moves out of its current Tracking Area (TA); this procedure is called a ‘Tracking Area Update’. The MME is responsible for keeping track of the user location while the UE is in ECM-IDLE.• When there is a need to deliver downlink data to an ECM-IDLE UE, the MME sends a paging message to all the eNodeBs in its current TA, and the eNodeBs page the UE over the radio interface. On receipt of a paging message, the UE performs a service request procedure which results in moving the UE to ECM-CONNECTED state.
  • MME connections to other logical nodes and main functions
  • S-GW connections to other logical nodes and main functions
  • P-GW connections to other logical nodes and main functions
  • PCRF connections to other logical nodes and main functionsEach PCRF may be associated with one or more AF, P-GW and S-GW. There is onlyone PCRF associated with each PDN connection that a single UE has.
  • LTE RF Testing Aspects Base station (eNodeB) according to 3GPP• Measurements are performed using • Rx characteristics (= Uplink): Fixed Reference Channels (FRC) and Reference sensitivity level, Dynamic EUTRA Test Models (E-TM), range, In-channel selectivity,• Tx characteristic (= Downlink) Adjacent channel selectivity (ACS) – Base station output power and narrow-band blocking, Blocking, – Output power dynamics: RE Power Receiver spurious emissions, Receiver Control dynamic range, total power intermodulation dynamic range, • Performance requirements, – Transmit ON/OFF power: Transmitter – …for PUSCH: Fading conditions, UL OFF power, transmitter transient timing adjustment, high speed train, period, HARQ-ACK multiplexed in PUSCH, – Transmitted signal quality: Frequency – …for PUCCH: DTX to ACK performance, Error, Error Vector Magnitude (EVM), ACK missed detection PUCCH format 1a Time alignment between transmitter (single user), CQI missed detection for antennas, DL RS power, etc. … PUCCH format 2, ACK missed detection – Unwanted emissions: Occupied PUCCH format 1a (multiple user) Bandwidth, Adjacent Channel Leakage – PRACH performance: FALSE detection Power Ratio (ACLR), Operating band probability, detection requirements unwanted emissions, etc. … – Transmitter spurious emissions and intermodulation, 3GPP TS 36.104: Base Station (BS) radio transmission and reception
  • eNB modulation quality measurements• Frequency error – If frequency error is larger than a few subcarrier, demodulation at the UE might not work properly and cause network interference, – Quick test: OBW, Limit for frequency error after demodulation 0.05 ppm + 12 Hz (1ms),• Error Vector Magnitude (EVM), – Amount of distortion effecting the receiver to demodulate the signal properly, – Limit changes for modulation schemes QPSK (17.5%), 16QAM (12.5%), 64QAM (8%),• Time alignment, – Only TX test defined for multiple antennas, measurement is to measure the time delay between the signals for the two transmitting antennas, delay shall not exceed 65 ns,• DL RS power – “Comparable” to WCDMA measurement CPICH RSCP; absolute DL RS power is indicated on SIB Type 2, measured DL RS power shall be in the range of ±2.1 dB,
  • ACLR in DL (FDD)
  • ACLR in DL (FDD):No filter definition in LTE!
  • eNB performance requirements PRACH and preamble testing I• PRACH testing is one of the performance requirements defined in 3GPP TS 36.141 E-UTRA BS conformance testing, – Total probability of FALSE detection of preamble (Pfa 0.1% or less), – Probability of detection of preamble (Pd = 99% at defined SNR), – Two modes of testing: normal and high-speed mode, • Different SNR and fading profiles are used (table shows settings for normal mode),
  • eNB performance requirements PRACH and preamble testing I– Depending on the mode different preambles are used to check detection probability (table shows preamble to be used for normal mode),
  • eNB performance requirements PRACH and preamble testing II • According to 3GPP TS 36.211 the NCS value is not set directly instead it is translated to a NCS configuration value, • This value is set in the signal generator R&S® SMx or R&S® AMU,Screenshot taken from R&S®SMU200A VectorSignal Generator
  • UE RF testing
  • LTE RF Testing Aspects User Equipment (UE) according to 3GPPTx characteristic Rx characteristics• Transmit power, • Reference sensitivity level,• Output power dynamics, • UE maximum input level,• Transmit Signal Quality, • Adjacent channel selectivity, – Frequency error, EVM vs. • Blocking characteristics, subcarrier, EVM vs. symbol, LO leakage, IQ imbalance, Inband • Intermodulation characteristics, emission, spectrum flatness, • Spurious emissions,• Output RF spectrum emissions, Performance requirements – Occupied bandwidth, Spectrum • Demodulation FDD PDSCH (FRC), Emission Mask (SEM), Adjacent Channel Leakage Power Ratio • Demodulation FDD (ACLR), PCFICH/PDCCH (FRC)• Spurious Emission,• Transmit Intermodulation, 3GPP TS 36.101: User Equipment (UE) radio transmission and reception
  • Transmit modulationAccording to 3GPP specification LO leakage (or IQ origin offset) is removed from evaluatedsignal before calculating EVM and in-band emission.
  • In-band emission
  • IQ component• Also known is LO leakage, IQ offset, etc.,• Measure of carrier feedthrough present in the signal,• Removed from measured waveform, before calculating EVM and in-band emission (3GPP TS 36.101 V8.3.0, Annex F),• In difference to DL the DC subcarrier in UL is used for transmission, but subcarriers are shifted half of subcarrier spacing (= 7.5 kHz) to be symmetric around DC carrier,• Due to this frequency shift energy of the LO falls into the two central subcarrier
  • ACLR measurement I
  • Receiver characteristics• Throughput shall be >95% for… – Reference Sensitivity Level, – Adjacent Channel Selectivity, – Blocking Characteristics,• …using the well-defined DL reference channels according to 3GPP specification
  • LTE wireless device testingfrom R&D up to conformance
  • Stages of LTE terminal testing
  • LTE terminal interoperability testing motivation• Interoperability testing is used to verify – Connectivity of the UE with the real network (by means of base station simulators) – Service quality, end-to-end performance – Different LTE features and parametrizations – Interworking between LTE and legacy technologies• The complete UE protocol stack is tested.• IOT test scenarios are based on requirements from real network operation and typical use cases.
  • LTE terminal interoperability testing example test scenarios• Registration• UE initiated detach• Network initiated detach• Mobile originated EPS bearer establishment• Mobile terminated EPS bearer establishment• Cell (re-)selection• GUTI reallocation• Tracking are update• …• Plus: end-to-end scenarios (video streaming, VoIP, …)• Plus: intra-LTE mobility, inter-RAT mobility
  • Test scenarios for LTE terminal IOTdifferent sources for maximum test coverage
  • LTE conformance testing motivation• Verifying compliance of terminals to 3GPP LTE standard – by validated test cases implemented on registered test platforms – in order to ensure worldwide interoperability of the terminal within every mobile network• 3GPP RAN5 defines conformance test specifications for – RF – Radio Resource Management (RRM) – Signaling• Certification organizations (e.g. GCF) define certification criteria based on RAN5 test specifications
  • LTE field trial testing andcoverage measurements
  • LTE field trials requirements from different deployment scenarios• Bandwidths from 1.4 MHz to 20 MHz• Different LTE FDD and TDD frequency bands• Combination with legacy technologies (GSM/EDGE, WCDMA/HSPA, CDMA2000 1xEV- DO)• Spectrum clearance and refarming scenarios• Femto cell / Home eNB scenarios
  • LTE field trials scope of test tools• Field trials provide input for: – Calibration and verification of planning tools for different deployment scenarios – Network optimization (capacity and quality) – Quality of service verification – Definition of Key Performance Indicators (KPIs) and verification, also from subscriber’s point of view• Parallel use of scanners / measurement receivers for comparison with UE and base station behaviour• Support of IOT activities
  • Example result from the fieldscanner measurements for LTE
  • 10 Steps to Determine 3G/4G IP Data Throughput1. Will my device connect? 6. What happens if I try real2. Do I have a good quality application? transmitter? 7. What happens under non-3. Do I have a good quality ideal conditions? receiver? 8. Is it robust?4. Can I achieve max E2E 9. Does it work closed loop? tput under ideal 10. How good is my battery conditions with UDP life?5. What about with TCP and simultaneous UL/DL?
  • Step 1: Will my device connect?
  • Step 1: Will my device connect?• Is the UE able to sync to the DL?•Can I get through the connection set-up• Can I ping my UE?• If not take a log and de-bug message exchange•Make edits as required with Message editor
  • 2. Do I have a good quality Transmitter? RF test• High data throughput testing relies on good quality UL transmissions• Look for the following: – Ensure you have appropriate power and attenuation settings – High EVM for high order modulation schemes – High EVM at the band edge – Spurs both in band and out of band – Linearity issues/ spectral growth – Switching transients, LO settling time – Repeat tests with any “other” radio’s active
  • 3GPP Tx Measurements
  • UL RF Measurements
  • 3. Do I have a good quality receiver?• High Data throughput testing relies on good a quality receiver• Look for the following: – sensitivity for different modulation schemes – Max input level performance – susceptibility to interference (simultaneous UL/DL, other radios, spurs from digital board, …)
  • 3. Do I have a good quality receiver?
  • DL Data Throughput for TD LTE(20MHz channel, 2x2 MIMO, UL/DL config 5, special subframe config 6)
  • Measurement Technique: UDP vs FTP (TCP) UDP FTP+ Unacknowledged + Simulates real-world file+ removes flow control transfers complexity +Transferred files can be viewed+ removes higher layer acks and/or compared+ Less susceptible latency - Adds flow control complexity- Not the full story for file - Add higher layer acks and transfers retransmissions- Not suitable for used in shared - TCP Control algorithms sensitivenetworks to multiple parameters - Test system configuration can affect results
  • 5. Can I achieve max E2E tput under ideal conditions with TCP?• TCP adds higher layer support for error detection, re-transmissions, congestion control and flow control• TCP flow control algorithms interpret “lost” packets as congestion• Careful consideration of parameters such as window size, number of parallel process, segment size etc. need to be considered
  • TCP “Flapping”
  • 6. What happens if I try a real application? … (Voice, video, ftp …)
  • 7. What happens under non-ideal conditions? •Typically fade the DL and use robust UL •Perform test mode and E2E testing •Measure MAC (BLER & Tput) and IP layer throughput •Use TCP with care!
  • 8. Is it robust? …• E2E IP tests PHY, MAC, PDCP, and IP layers all working together at full rate• Check processor can handle multiple real time activities – add SMS and voice calls during E2E IP• Check there are no memory overflow/leakage issues
  • 9. Does it work closed loop?•BLER/Tput Testing•Supports Test Mode and E2E Testing
  • 10. How good is my battery life?
  • Case StudyAutomated Measurements Give Repeatable 21Mbps Results!
  • Case StudyDevice Performance: MIPS Matter!
  • Case StudyCat14 (21Mbps) Devices – Better the second time around
  • Case StudyNot All HSDPA Cat 6 Devices Have the Same Throughput
  • Final Note
  • Test LTE DL peak rate 64 QAM 20 MHz 4x4 MIMO How muchtheoretical Mbps per antenna?
  • References• Telecommunication management; Performance Management (PM); Performance measurements; Universal Terrestrial Radio Access Network (UTRAN)• http://www.3gpp.org/ftp/Specs/html-info/32405• Terminal conformance specification, Radio transmission and reception (FDD)• http://www.3gpp.org/ftp/Specs/html-info/34121.htm• User Equipment (UE) radio transmission and reception (FDD)• http://www.3gpp.org/ftp/Specs/html-info/25101.htm
  • The EndThank You