Terminology » LTE » LTE-M Protocol Stack Overview

LTE-M Protocol Stack Overview

lte m protocol stack lte phy layer mac

This page provides an overview of the LTE-M Protocol Stack, detailing both the user plane and control plane. It outlines the protocol layers, specifically PHY, MAC, RLC, PDCP, and RRC, within the LTE-M protocol stack.

Introduction

LTE-M, or Long Term Evolution for Machine-Type Communications, adheres to 3GPP specifications, similar to LTE technology. Its primary objective is to support cellular IoT device requirements, including low device cost, extensive coverage, prolonged battery life, and increased cell capacity.

LTE-M devices are categorized as Cat-0, Cat-M1, and Cat-M2, in accordance with different 3GPP releases. Specifically, LTE-M Cat-0, Cat-M1, and Cat-M2 follow 3GPP TS 36 series of rel.12, rel.13, and rel.14, respectively.

Let’s delve into the functions of each layer within the LTE-M Protocol Stack.

LTE-M Protocol Stack Layers

LTE-M Protocol Stack

The figure above illustrates the layers of the LTE-M Protocol Stack, displaying both user plane and control plane protocol layers.

LTE PHY

  • PHY (Physical Layer):
    • CRC attachment
    • Coding block
    • Scrambling/descrambling
    • Modulation/de-modulation
    • Measurement
    • Resource element mapping/demapping
    • HARQ
    • MIMO
  • MAC (Medium Access Control):
    • Uplink: Channel mapping, multiplexing, handling control elements, random access procedure, logical channel priority, HARQ, and sending BSRs.
    • Downlink: Channel mapping, de-multiplexing, DRX, handling control elements, and HARQ.
  • RLC (Radio Link Control):
    • Uplink: Buffer status report, segmentation and concatenation, ARQ (for AM mode).
    • Downlink: Re-ordering, assembly, and ARQ (for AM mode).
  • PDCP (Packet Data Convergence Protocol):
    • Uplink: Sequence number addition, handover data handling, integrity protection, ciphering, and header compression.
    • Downlink: In sequence delivery, duplicate packet detection, integrity validation, deciphering, and header decompression.
  • RRC (Radio Resource Control):
    • Configuration Management
    • Connection Management
    • Paging control
    • Security Management
    • Broadcast
    • Measurement configuration
    • Measurement Reporting
    • Cell selection and reselection
    • Mobility Management