LTE Air Interface - Technical Analysis
- Duration: 4 days
- Level: Level 4
LTE Air Interface - Technical Analysis (4 days)
This workshop brings together two industry leaders to provide unique and unrivalled insight into the LTE radio interface. In so doing, it examines key LTE radio interface procedures and protocols. Lab sessions enable students to encode RRC ASN.1 messages in a practical manner putting to practice key parameters. The workshop examines LTE physical layer in detail, using various demo and practical lab sessions to demystify Physical Channel mapping, Hybrid ARQ operation and Downlink Channel Estimation. Unique to our offering is the blend of theoretical course and hands-on software simulation modelling. No experience required.
Course Outline
Divided into 10 sections, the topics covered will include:
Section 1: Introducing LTE (1 hour)
- 3GPP Evolution, From R5 to R10, the goals of LTE.
- Review of the LTE Architecture, E-UTRAN, E-UTRA, eNB and E-UTRAN interfaces, EPC, MME, S-GW, PDN Gateway, SGSN, IMS.
- User Equipment functionality and Identities, IMSI, GUTI, M-TMSI, S-TMSI and C-RNTI.
- Network Identities, TAI (Tracking Area Identity) and Cell Identity.
- LTE performance
- Spectrum and Channel Bandwidths Options.
Section 2: Review of the LTE Physical Layer (1.5 hours)
- Services provided by the Physical Layer.
- E-UTRA Physical Layer, overview of OFDMA and SC-FDMA, subcarriers, OFDM symbols, cyclic prefix, Physical Resource Block.
- LTE generic frame structure, slots and subframes, frequency bands, carrier frequencies and EARFCN.
- The LTE downlink physical channels - PBCH, PCFICH, PDCCH, PHICH, Synchronization and Reference Signals.
- The LTE uplink physical channels - PRACH, PUCCH, PUSCH, uplink reference signals.
- Modulation and Coding, QPSK, 16QAM, 64QAM, Turbo Coding.
Section 3: LTE Air Interface Protocols (3.5 hours)
- Defined the use of NAS, IP, RRC, PDCP, RLC and MAC.
- The E-UTRA Interface, Stratums, NAS Control Plane, NAS User Plane, NAS Messages, EMM Messages and ESM Messages.
- LTE States, EPS Mobility Management States, EMM States in the UE, EMM States in the MME, EPS Connection Management States.
- The E-UTRA Protocols, Radio Resource Control, RRC Messages, RRC States, Establishment of an RRC Connection.
- PDCP services and functions, PDCP profiles, compression standards, PDCP headers and frame formats.
- RLC, RLC Transparent Mode, RLC Unacknowledged Mode and RLC Acknowledged Mode, RLC PDUs, the TMD PDU, UMD PDU, AMD PDU, AMD Segment PDU and the RLC Status PDU.
MAC functions and operation. - Logical Channels - BCCH, PCCH, CCCH, DCCH, DTCH.
- Transport Channels - BCH, DL-SCH, PCH, UL-SCH, RACH.
- Mapping Logical Channels into Transport Channels - RNTI Identities, random access process, non-contention based random access procedure.
Section 4: LTE Operational Procedures (2.5 hours)
- Contents of RRC MIB and SIB messages, Scheduling Options.
- PLMN selection and Initial Cell Selection algorithms, Optimization of Parameters.
- LTE initial procedures, RRC Connection, Signalling Radio Bearers.
- Attach, PDN connectivity and Default and Dedicated Bearer Establishment.
- RRC UE Capability and Security.
- RRC Messages in operation.
- SON Architecture and Automatic Neighbour Relationship procedures.
- E-UTRA and LTE Security - authentication, algorithms and keys, ciphering and integrity.
- End to End Downlink and Uplink IP Data Flow.
Section 5: LTE Mobility (1 hour)
- LTE mobility, LTE cell planning, capacity and coverage planning, frequency deployment options.
- Soft Frequency Re-use Options.
- Mobility functional architecture, role of the eNB and MME, Tracking Areas.
- Idle Mode procedures, LTE Idle Mode monitoring requirements.
- E-UTRA Measurements, RSSI, RSRP, RSRQ.
- Cell reselection, intra-frequency measurements, inter-frequency and inter-RAT measurements, high and medium mobility states, ranking of cells, Tracking Area Update.
- Mobility in the LTE Active State, measurements and gap configurations, event triggers, timing, the handover process.
- EPC mobility (Relocation).
- Femto cells, scenarios and assumptions, HeNB selection.
- 3GPP interworking, E-UTRAN to UTRAN / GERAN RAU procedure, E-UTRAN to UTRAN / GERAN handover procedure.
Section 6: OFDM in LTE (1 hour)
- OFDM motivation: spectral efficiency, equalization, bandwidth flexibility, resilience to multipath.
- OFDM signal structure: subcarriers, orthogonality, the cyclic prefix, OFDM symbols, fundamental period.
- OFDM signal structure in LTE: the resource grid, resource elements, resource blocks, slots and subframes.
- Generation of OFDM signals using the IDFT, efficient implementation with IFFT.
- The cyclic prefix: OFDM signals and multipath, LTI system response, mobility, channel delay spread.
- OFDM windowing: out of band emissions reduction, windowing versus filtering versus EVM.
- Oversampling and upconversion of OFDM signals, baseband spectral occupancy, filtering considerations.
- Peak to average power ratio reduction techniques, clipping, peak windowing, peak cancellation.
- SC-FDMA: LTE uplink modulation, DFTS-OFDM, subcarrier mapping.
Section 7: LTE Multiplexing and Channel Coding (2 hours)
- Transport channels & control information: DL-SCH, PCH, BCH, DCI, CFI, HI, UL-SCH and UCI.
- Mapping of transport channels to physical channels.
- CRC coding, polynomials, CRC masking of DCI messages and BCH coding.
- Code block segmentation, filler bits, turbo coder block sizes, code block CRC attachment.
- Convolutional and turbo coding, tail biting, Quadratic Permutation Polynomial (QPP) interleaving.
- Rate matching, bit selection and pruning, subblock interleaving, role of HARQ.
- Transport channel and control information processing chains.
- HARQ in LTE, incremental redundancy, Chase combining, stop and wait processes.
Section 8: MIMO Review (1 hour)
- Motivation, increased capacity, increased robustness.
- Multiantenna systems classification, SISO, MISO, SIMO and MIMO. Beamforming, diversity, spatial multiplexing.
- Transmit and receive diversity, diversity gain.
- The Alamouti sheme, space time coding, space frequency coding, decoding procedure.
- Delay diversity and cyclic delay diversity (CDD), relationship with OFDM and multipath.
- Beamforming, SNR maximisation.
- Spatial multiplexing, narrowband assumption, channel matrix, channel rank, spatial streams and layers.
- Equalising and predistortion in MIMO systems, noise enhancement, advantages and disadvantages.
- Precoding and combining in MIMO: Singular value decomposition (SVD), codebook and non-codebook based precoding, signalling overhead.
- Codebook based precoding, desired codebook attributes, codebook selection, signalling overhead .
Section 9: Downlink Physical Channels and Signals (3 hours)
- Downlink physical channel processing chain, scrambling, modulation, layer mapping, precoding.
- Codewords and layers, antenna ports and physical antennas.
- Scrambling and modulation, PRBS initialisation, BPSK, QPSK, 16QAM and 64QAM constellations.
Downlink multi-antenna processing, transmission schemes, layer mapping and precoding, transmit - diversity, cyclic delay diversity (CDD), spatial multiplexing, beamforming.
- Cell identities. Cell identity group, identity within the group, mapping to cell search procedure.
- Synchronisation signals: PSS & SSS, structure, mapping to resource grid, timing acquisition, cell search.
- Reference signals: Cell specific, UE specific & MBSFN, reference signal antenna ports, channel estimation.
- Downlink physical channels: PBCH, PCFICH, PHICH, PDSCH & PDCCH, processing chains.
- The control region, Resource Element Groups (REGs), Control Channel Elements (CCEs), PDCCH search spaces, role of CFI.
- Mapping of physical channels and signals to the resource grid, relationship between antenna ports and physical antennas.
- Closed and open loop spatial multiplexing, precoding matrix selection, role of PMI and RI.
- Codebook based and non-codebook based beamforming in LTE.
- Transmit diversity, space frequency block coding matrices.
Section 10: Uplink Modulation (1 hour)
- Uplink physical channel processing chain, scrambling, modulation, SC-FDMA precoding.
- Scrambling and modulation, BPSK, QPSK, 16QAM and 64QAM constellations.
- SC-FDMA symbol construction, DFT sizes, uplink resource allocation size restrictions, subcarrier mapping.
- Uplink reference signals: DRS and SRS, uplink channel estimation problem, SRS structure and timing.
- Uplink physical channels: PDSCH, PDCCH & PRACH processing chains.
- Control information: Channel Quality Information (CQI), Rank Indication (RI), Precoding Matrix Indication (PMI), HARQ Indicator (HI), Scheduling Request (SR).
- Control signalling on PUSCH, data and control interleaving and multiplexing, ACK/NACK placeholder bits.
- Control signalling on PUCCH, PUCCH Formats 1, 1a, 1b, 2, 2a, 2b, PUCCH resources, cyclic shifts, resource element mapping.
LAB Sessions
The course contains a number of practical elements in the form of demonstrations and lab sessions. These include:
Lab Session 1: RRC Signalling Messages and Parameters (1.5 hours)
- Getting ASN.1 from 3GPP LTE RRC Specifications.
- ASN.1 Message Encoding.
- Encoding the MIB and SIB Messages.
- RRC Connection and Connection Setup Messages.
Lab Session 2: RRC Measurement Configuration (1 hour)
- Generating the RRC Connection Reconfiguration Message.
- Measurement Configuration Options.
- Encoding Intra and Inter LTE Mobility Parameters.
Lab Session 3: Mapping of Physical Channels to the Resource Grid (1 hour)
- Generating the resource grid.
- Generating physical channels and physical signals.
- Mapping to the resource grid.
- Effect of Cell Id.
- Effect of antenna port.
Lab Session 4: Hybrid ARQ for PDSCH (0.5 hour)
- PDSCH transmission and reception processing.
- Uncoded performance of QPSK, 16QAM and 64QAM.
- Coded performance without Hybrid ARQ.
- Coded performance improvement with Hybrid ARQ.
Lab Session 5: Downlink Channel Estimation (1.5 hours)
- Channel estimation using DRS.
- Interpolation of estimates.
- Resource grid edge effects.
- Effect of channel conditions in estimates.
- Received signal equalisation.
Demo 1: LTE OFDM Transmission Mask (0.5 hour)
- Transmission mask specifications.
- Windowing effects.
- Additional filtering requirements.
Demo 2: MIMO in LTE (0.5 hour)
- Beamforming radiation pattern examples.
- 2 and 4 antenna MIMO directional capability examples.
Demo 3: RRC Random Access (0.5 hour)
- Cell Random Access Options.
- SIB 2 Configuration Parameters.
Who Should Attend
Engineers and managers involved in design and testing of the LTE Radio Interface. Personnel who desire a comprehensive explanation of the LTE Radio Interface.