1. ISM Band Radio 802.15.4 Radio Protocols and Topology
December 5, 2012 Paul Nickelsberg Orchid Technologies Engineering and Consulting, Inc.

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

3. 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

4. Personal Area Network Coordinator
Star Topology
Personal Area Network Coordinator

5. 802.15.4 Peer-to-Peer Mesh Topology
Personal Area Network Coordinator

6. Personal Area Network Coordinator
Zigbee Tree Topology
Obstruction
Personal Area Network Coordinator

7. 802.15.4 Node Types PAN Coordinator Full Function Device
Reduced Function Device
Zigbee Coordinator
Zigbee Router
Zigbee End Device

8. 802.15.4 Channel Contention ALOHA Transmit without CSMA CSMA-CA
Carrier Sense Multiple Access with Collision Avoidance

9. 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

10. 802.15.4 Channel Contention CSMA-CA MechanismTX
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

11. Beacon Enabled Network
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

12. 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

13. 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

14. 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

15. 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

16. 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)

17. 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

18. Synchronization Header SHR
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

19. Synchronization Header SHR
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

20. Synchronization Header SHR
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

21. Address Information 0 to 20 Bytes
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
Bits
Bits
Frame Type
Security
Frame Pending
ACK Request
Intra PAN
Reserved
Dest Addr Md
Frame
Version
Source Addr Md

22. 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: Compatible Frame, 01: Frame
Source Addr Mode

23. 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.

24. 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

25. 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

26. 802.15.4 RF Modem Very different from the old days!

27. 802.15.4 RF Modem Very different from the old days!