LTE Air Interface

Subject: 4G LTE
Category: Radio
Duration: 3 days

Course outline:

Introduction to E-UTRA

● Evolution steps of the 3GPP systems, the goals for LTE
● E-UTRA and Evolved Packet Core network architecture
● Nodes: UE, eNB, SGW, MME
● Interfaces: Uu, X2, S1, S11
● LTE bandwidths, bit rates and UE categories
● Summary of radio access techniques
● E-UTRAN protocol stack
● Alternative systems: Mobile WiMAX

Overview of OFDMA and SC-FDMA

● Fundamentals of multipath propagation (selectivity in time, frequency and space)
● Basics of OFDM transmission, subcarriers, cyclic prefix, IFFT/FFT processing
● OFDMA and SC-FDMA as extension of OFDM
● Multiple access with OFDMA and SC-FDMA
● Advantages and disadvantages of OFDM, OFDMA and SCFDMA

LTE Downlink PHY Layer Processing

● Downlink channel architecture (radio bearers, logical, transport and physical channels)
● Downlink FDD frame structure and its elements (sub-frames, slots, resource elements, physical resource blocks, PHY channels and signals)
● PHY channels and signals including: PBCH, PCFICH, PHICH, PDCCH, PDSCH, Primary and Secondary Synchronization Signals, Reference Signals)
● Various antenna pilot patterns and Reference

Signals for MIMO

● MIMO processing in 3GPP-LTE Release 8
● Placement of control channels (PCFICH, PHICH, PDCCH) in the control region
● Downlink processing chain including channel coding and rate matching, modulation, layer mapping, pre-coding, resource element mapping and OFDMA signal generation
● Downlink control information, PDCCH formats mapping of DCI into PDCCH
● PDCCH blind decoding
● PHICH assignment

LTE Uplink PHY Layer Processing

● Uplink channel architecture (radio bearers, logical, transport and physical channels)
● Uplink FDD frame structure and its elements (sub-frames, slots, resource elements, physical resource blocks, PHY channels and signal)
● PHY channels and signals including PUCCH, PUSCH, SRS, DRS, PRACH
● PUCCH formats
● Creation of SRS
● Random Access Preamble formats
● Location of PRACH in the uplink frame
● Uplink processing chain including channel coding and rate matching, modulation, resource element mapping and SCFDMA signal generation
● PUSCH hopping procedure and UE SRS procedure

LTE MAC Layer

● MAC architecture and functions
● Priority handling and multiplexing
● Hybrid ARQ (HARQ) operation (Chase combining and incremental redundancy)
● HARQ processes and processing HARQ ACKs and NACKs by PHY layer
● Discontinuous Reception (DRX) and Semi-Persistent

Scheduling (SPS)

● Adaptive Modulation and Coding
● Timing Relationship and Timing Advance
● Scheduling

LTE RRC, PDCP and RLC Layers

● RRC procedures including system info broadcasting, paging, RRC connection establishment, security establishment, NAS message transport and RRC connection reconfiguration
● Types of radio bearers
● RRC connection establishment: from RRC Idle to RRC Connected
● PDCP architecture and functions: robust header compression, ciphering and integrity protection
● RLC architecture and functions including segmentation / concatenation, retransmissions
● RLC modes: Transparent, Unacknowledged, Acknowledged
● Example LTE data flow and transport block sizes

Radio Interface Procedures

● Downlink resource assignment, resource allocation types, resource block grouping
● Modulation and transport block size determination
● Synchronization and system info acquisition
● RRC measurement reporting
● UE mobility states
● Measurements: RSRP, RSSI, RSRQ
● Overview of E-UTRA reporting events
● Cell selection / reselection
● Random Access procedure
● MIMO feedback reporting (PMI and RI)
● CQI, PHR and BSR reporting
● Uplink power control, open loop and closed loop, types of transmit power commands
● Downlink power control – operation and parameters
● X2 interference management and load balancing procedures

LTE Air Interface Demo and Experiments (tool-based)

● OFDMA and SC-FDMA waveforms
● Chosen eNB and UE signals and PHY channels shown in the time and frequency domain
● Complete downlink and uplink radio frame shown as time-frequency grid

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