07-04-2011, 04:15 PM
[attachment=11875]
Introduction
What is Zigbee?
Technological Standard created for control and sensor networks.
Based on IEEE 802.15.4 Standard.
Developed By Zigbee Alliance
Motivation
The ZigBee standard was developed to address the following needs:
• Low cost and secure
• Reliable and self healing
• Flexible and extendable
• Low power consumption
• Easy and inexpensive to deploy
• Global with use of unlicensed radio bands
• Integrated intelligence for network set-up and message routing
The ZigBee Name
Named for erratic, zig-zagging patterns of bees between flowers
Symbolizes communication between nodes in a mesh network
Network components analogous to queen bee, drones, worker bees
IEEE 802.15.4 & ZigBee In Context
IEEE 802.15.4 Overview
Standard for Low- rate Wireless Personal Area Networks (LR-WPANs)
Includes features such as low power consumption , high density of nodes per network , low cost and simple implementation
Uses the unlicensed frequency bands 16 channels at 2.4 GHz , 10 channels at 915 MHz and 1 channel at 868 Mhz.
Device types- PAN Coordinator , Fully Functional Device , Reduced Functional Device
Topologies - star , peer-to-peer , cluster-tree
IEEE 802.15.4 PHY(Physical layer)
Provides interface between MAC Layer and physical radio channel
Consists of two services PHY data service, PHY management service which form the Physical Layer
Management Entity (PLME)
Features are activation and deactivation of radio transreciever ,energy detection (ED), Link Quality Indication (LQI), channel selection , Clear Channel Assessment(CCA) and transmitting and receiving packet
• Each Physical Protocol Data Unit(PPDU) consists of Physical header , Synchronisation header and a variable payload
IEEE 802.15.4 MAC
Interface between System Specific Convergence Sublayer (SSCS) and PHY
Responsible for reliable communication between a node and its neighbours
Two services MAC data service and MAC management service forming MAC Layer Management Entity
MAC data service enables transmission and reception of MAC Data Protocol Units (MPDU)
Features are beacon management , channel access , GTS management