802.15.4 and Zigbee

What is ZigBee?

Technological Standard Created for Control and Sensor Networks.

  • Based on the IEEE 802.15.4 Standard.

  • Centered in small radios.

Created by the ZigBee Alliance.

  • 200+ members.

History.

  • May 2003: IEEE 802.15.4 completed.

  • December 2004: ZigBee specification ratified.

  • June 2005: public availability.

What Does ZigBee Do?

Designed for wireless controls and sensors.

  • Operates in Personal Area Networks (PAN’s) and device-to- device networks.

  • Connectivity between small packet devices.

  • Examples: control of lights, switches, thermostats, appliances, etc..

Zigbee?

  • Named for erratic, zig-zagging patterns of bees between flowers.

  • Symbolizes communication between nodes in a mesh network.

  • Network components “seen as analogous” to queen bee, drones, worker bees.

Network applications

ZigBee and Other Wireless Technologies

Features

  • Low power consumption.

  • Low cost.

  • Small packet.

  • Low offered message throughput.

  • Supports large network orders (<= 65k nodes).

  • Low to no QoS guarantees.

  • Flexible protocol design suitable for many applications.

Overview

Low Rate WPAN (LR-WPAN).

  • E.g. Sensor networks.

Simple and low cost.

  • Fully handshake protocol.

Low power consumption.

  • Years on lifetime using standard batteries.

Different topologies.

  • Star, peer-to-peer, combined.

Data rates: 20-250 kbps.

  • Low latency support.

Operates at different frequencies.

  • 868 Mhz, 915 Mhz, 2.4 GHz.

Architecture

ZigBee Alliance

  • 45+ companies: semiconductor manufacturers, IP providers, OEMs, etc.

  • Defining upper layers of protocol stack: from network to application, including application profiles.

  • First profiles published mid 2003.

IEEE 802.15.4 Working Group.

  • Defining lower layers of protocol stack: MAC and PHY.

Protocol Stack

How ZigBee Works

Topology.

  • Star.

  • Cluster Tree.

  • Mesh.

Network coordinator, routers, end devices.

2 or more devices form a PAN/WSN.

States of operation.

  • Active.

  • Sleep.

Devices.

  • Full Function Devices (FFD’s).

  • Reduced Function Devices (RFD’s).

Modes of operation.

  • Beacon.

  • Non-beacon.

Traffic types.

  • Intermittent.

  • Repetitive.

  • Periodic.

Traffic

Types

Data is periodic.

  • Application dictates rate (e.g. sensors).

Data is intermittent.

  • Application or stimulus dictates rate (optimum power savings), e.g. light switch.

Data is repetitive (fixed rate a priori).

  • Device gets guaranteed time slot (e.g. heart monitor).

Modes

Beacon mode

  • Beacon sent periodically.

  • Coordinator and end device can go to power save.

  • Lowest energy consumption.

  • Precise timing needed.

  • Beacon period (ms-m).

Non-Beacon mode

  • Coordinator/routers have to stay awake (robust power supply needed).

  • Heterogeneous network.

  • Asymmetric power.

Node-Types

ZigBee Coordinator (ZBC) (IEEE 802.15.4 FFD)

  • only one in a network.

  • initiates network.

  • stores information about the network.

  • all devices communicate with the ZBC.

  • routing functionality.

  • bridge to other networks.

ZigBee Router (ZBR) (IEEE 802.15.4 FFD)

  • optional component.

  • routes between nodes, network backbone.

  • extends network coverage.

  • manages local address allocation/de-allocation.

ZigBee End Device (ZBE) (IEEE 802.15.4 RFD)

  • optimized for low power consumption.

  • cheapest device type.

    • sensor would be deployed here.

Last updated