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Structure of the 3GPP NR (5G) Specification

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Here's a high-level technical overview of the structure of the 3GPP NR (5G) specification:

  1. Physical Layer (PHY):
    • Numerology and Frame Structure: Defines the basic time and frequency structure of the radio frame, subframes, slots, and symbols. It includes parameters like subcarrier spacing, slot formats, and the structure of the synchronization signal.
    • Modulation and Coding Schemes (MCS): Specifies the modulation schemes and error correction coding used for data transmission over the air interface.
    • Multiple Access Schemes: Describes the methods by which multiple users share the same time and frequency resources, such as Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), and Orthogonal Frequency Division Multiple Access (OFDMA).
  2. MAC (Medium Access Control) Layer:
    • Logical Channels: Defines different types of logical channels used for transmitting specific types of information, such as control information, user data, and broadcast information.
    • Multiplexing and Demultiplexing: Specifies how multiple logical channels are multiplexed onto transport channels and demultiplexed at the receiver.
  3. RLC (Radio Link Control) Layer:
    • Reordering and Concatenation: Manages the reordering of out-of-sequence protocol data units (PDUs) and the concatenation of smaller PDUs into larger ones.
    • Error Correction and Detection: Implements error correction and detection mechanisms to ensure reliable data transmission.
  4. PDCP (Packet Data Convergence Protocol) Layer:
    • Header Compression: Reduces the overhead of IP/UDP/RTP headers to improve efficiency.
    • Ciphering and Integrity Protection: Provides security functions such as encryption and integrity protection for user data.
  5. RRC (Radio Resource Control) Layer:
    • Connection Establishment and Release: Manages the establishment, maintenance, and release of radio connections.
    • Mobility Management: Handles procedures related to handovers and cell changes.
    • Security Control: Implements security-related functions such as key management and authentication.
  6. SDAP (Service Data Adaptation Protocol) Layer:
    • QoS (Quality of Service) Control: Ensures the delivery of different services with varying quality requirements.
    • Header Conversion: Adapts the packet data format to suit the needs of the radio interface.
  7. SM (Session Management) Layer:
    • PDN Connectivity Establishment and Release: Manages the establishment and release of connections to packet data networks (PDN).
    • UE (User Equipment) Triggered Services: Supports services initiated by the user equipment.