ISM Band Radio 802.15.4 Radio Protocols and Topology December 5, 2012 Paul Nickelsberg Orchid Technologies Engineering and Consulting, Inc. www.orchid-tech.com

802.15.4 Protocols & Topology Network Topology defines the structure of the entire network Network Protocol defines the structure of the single message

802.15.4 Topology LR-WPAN: Low Rate Wireless Personal Area Network WPAN: Wireless Personal Area Network PAN: Personal Area Network I use these terms interchangeably in this presentation

Personal Area Network Coordinator 802.15.4 Star Topology Personal Area Network Coordinator

802.15.4 Peer-to-Peer Mesh Topology Personal Area Network Coordinator

Personal Area Network Coordinator 802.15.4 Zigbee Tree Topology Obstruction Personal Area Network Coordinator

802.15.4 Node Types PAN Coordinator Full Function Device Reduced Function Device Zigbee Coordinator Zigbee Router Zigbee End Device

802.15.4 Channel Contention ALOHA Transmit without CSMA CSMA-CA Carrier Sense Multiple Access with Collision Avoidance

802.15.4 Channel Contention ALOHA Mechanism Packet ACK Packet Node 1 Packet ACK Node 2 Packet Node 3 No Contention Packets get through Contention, neither Packet gets through

802.15.4 Channel Contention CSMA-CA Mechanism TX Packet ACK Node 1 TX TX BO Listen Packet ACK BO Listen Packet ACK Node 2 TX BO Listen BO Listen Packet ACK Node 3 Not Deterministic BO = Back Off

Beacon Enabled Network 802.15.4 Beacon Topologies Non-Beacon Network Lower power requirements No Contention Free Operation Nodes are unsynchronized Beacon Enabled Network Higher power requirements Provide Contention Free Operation Nodes synchronized to Beacon

802.15.4 Topology Non-Beacon Enabled Network Messages are sent only when required Simple Structure Low Message Rates TIME Ack Ack Ack Listen Packet Listen Packet Listen Back-off Back-off Back-off Packet

802.15.4 Topology Beacon Enabled Network Contention Access Period Contention Free Period Inactive Period Beacon Beacon 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 1 2 TIME Ack Ack Ack Listen Back-off Packet Back-off Listen Packet Packet

802.15.4 Topology Beacon Enabled Network Sent by PAN Coordinator Synchronizes Network Contention Access Period CSMA-CA Multiple Access Periods Contention Free Period Guaranteed Time Slot Access Periods (GTS) Inactive Period Period of Network Inactivity

802.15.4 Message Protocol Application Application Application Data Processing APDU APDU Network Data Processing NPDU NPDU MAC Data Processing MPDU MPDU PHY Data Processing PPDU PPDU Transmitter Receiver

802.15.4 PHY Protocol MAC Protocol Data Unit (MPDU) General structure, designed with mechanisms to improve the probability of successful data transmission MAC Protocol Data Unit (MPDU) MAC Header MHR MAC Payload MAC Footer MFR Synchronization Header SHR PHY Header PHR PHY Payload PSDU PHY Protocol Data Unit (PPDU)

802.15.4 PHY Protocol MAC Header MHR MAC Payload MAC Footer MFR Synchronization Header SHR PHY Header PHR PHY Payload PSDU 0x00 0x00 0x00 0x00 0xA7 Preamble Sequence 4 Bytes of 0x00 Data Start of Frame Delimiter 1 Byte of 0xA7

Synchronization Header SHR 802.15.4 PHY Protocol MAC Header MHR MAC Payload MAC Footer MFR Synchronization Header SHR PHY Header PHR PHY Payload PSDU 2.4 GHz, 32 Bit Chips 0x00 0x00 0x00 0x00 0xA7 11011001110000110101001000101110 11011001110000110101001000101110

Synchronization Header SHR 802.15.4 PHY Protocol MAC Header MHR MAC Payload MAC Footer MFR Synchronization Header SHR PHY Header PHR PHY Payload PSDU 915 MHz, 16 Bit Chips 0x00 0x00 0x00 0x00 0xA7 0011111000100101 0011111000100101

Synchronization Header SHR 802.15.4 PHY Protocol MAC Header MHR MAC Payload MAC Footer MFR Synchronization Header SHR PHY Header PHR PHY Payload PSDU Frame Length Frame length is 1 Byte, MSB always 0, Max Length is 127 Values 0 – 4 is Reserved, Value 5 is ACK, Values 6 – 8 is Reserved, Values 9 through 127 is PSDU packet size

Address Information 0 to 20 Bytes 802.15.4 PHY Protocol MAC Header MHR MAC Payload MAC Footer MFR Frame Control Field Sequence Number Address Information 0 to 20 Bytes Bits 0 - 2 Bit 3 Bit 4 Bit 5 Bit 6 Bits 7 – 9 Bits 10 - 11 Bits 12 - 13 Bits 14 - 15 Frame Type Security Frame Pending ACK Request Intra PAN Reserved Dest Addr Md Frame Version Source Addr Md

802.15.4 PHY Protocol Frame Control Field FCS Field Field Description Frame Type 000:Beacon, 001:Data, 010:Ack, 011:MAC CMD Security 1:MAC Sub-layer Security Enabled Pending 1:More Data to be transmitted ACK Request 1:Recipient must ACK the transmitted message Intra PAN 1:Send PAN ID with Address Dest Addr Mode 00: PAN ID and Addr Not Present, 01: Reserved 10: Address Field Contains Short Address (16 Bits) 11: Address Field Contains Long Address (64 Bits) Frame Version 00: 802.15.4-2003 Compatible Frame, 01: 802.15.4 Frame Source Addr Mode

802.15.4 PHY Protocol Finally! MAC Header MHR MAC Payload MAC Footer MFR Finally! This is our data. Max size per packet is 127 Bytes less the MAC Header Size. In a Zigbee network the network layer information will reside here with our application data.

802.15.4 PHY Protocol Frame Check is a Sixteen bit CRC MAC Header MHR MAC Payload MAC Footer MFR Frame Check 1 Frame Check 2 Frame Check is a Sixteen bit CRC

802.15.4 PHY Protocol PHY Protocol Data Unit (PPDU) MAC Header MHR MAC Payload MAC Footer MFR Synchronization Header SHR PHY Header PHR PHY Payload PSDU PHY Protocol Data Unit (PPDU) Approx 4.2 mSec to send 127 Byte Message Back-off and Listen Times Not Included

802.15.4 RF Modem Very different from the old days!

802.15.4 RF Modem Very different from the old days!