ZigBee NET Frame Generation and Decoding
This example shows how to use the Communications System Toolbox™ Library for the ZigBee® Protocol to generate and decode NET frames of the ZigBee specification [ 1 ].
The ZigBee standard specifies the network (NET or NWK) and application (APP) layers for low-rate wireless personal area networks. These NET- and APP-layer specifications build upon the PHY and MAC specifications of IEEE® 802.15.4 [ 2 ]. ZigBee devices find application in home automation and sensor networking and are highly relevant to the Internet of Things (IoT) trend.
A zigbee.NETFrameConfig configuration object is used both in generating and decoding ZigBee NET frames. Such objects describe a NET-layer frame and specify its frame type and all applicable properties. The zigbee.NETFrameGenerator function accepts a zigbee.NETFrameConfig object describing the frame, and optionally a NET-layer payload (APP-layer frame) in bytes (two-characters), and outputs the NET frame in bytes. The zigbee.NETFrameDecoder function accepts a NET Protocol Data Unit (NPDU) in bytes and outputs a zigbee.NETFrameConfig object describing the frame and possibly a NET-layer frame in bytes. Clause 3.3 in [ 1 ] describes the NET frame formats.
Decoding NET Frames of Home Automation ZigBee Radios
This section decodes NET frames transmitted from a commercial ZigBee radio enabling home automation, and captured using a USRP® B200-mini radio and the Communications System Toolbox Support Package for USRP® radio.
The zigbee.NETFrameDecoder function can decode NET-layer ZigBee data frames and the header of net-command frame types.
load zigbeeNETCaptures % netFrame [netConfig, netPayload] = zigbee.NETFrameDecoder(netFrame); netConfig %#ok<NOPTS>
netConfig = NETFrameConfig with properties: FrameType: 'Data' ProtocolVersion: 'ZigBee 2007' SequenceNumber: 212 Addressing: SourceAddress: '0000' DestinationAddress: '35EA' IEEEAddressing: 'None' Security: Security: 1 DataEncryption: 0 MICLength: 0 KeyIdentifier: 'Network' ExtendedNonce: 1 FrameCounter: 193458 SecuritySourceAddress: '24FD5B00000014B6' KeySequence: 0 Routing: Radius: 30 DiscoverRoute: 1 SourceRouting: 1 RelayIndex: 0 RelayList: [0x4 char] Multicast: Multicast: 0
Note that NET-layer decoding indicates that the NET-layer payload is encrypted (Security = true). Security can be used either in the network or the application layer; this frame uses network-layer security. On the one hand, the DataEncryption field is false in the frame and the Message Integrity Code (MIC) length is zero, which indicate that security level #0 is used and that the payload is not encryped. However, according to the ZigBee standard (Clause 18.104.22.168 in [ 1 ]), these two fields are overwritten with values locally stored during network setup. In this case, this frame was secured with security level #5, which means that the NET-payload is encrypted and that the MIC length is 32 bits.
Generating NET Frames
The zigbee.NETFrameGenerator function can generate unsecure NET-layer ZigBee data frames. The configuration object can be further customized.
netConfig = zigbee.NETFrameConfig('SequenceNumber', 123, 'DestinationAddress', 'E568'); numOctets = 50; payload = dec2hex(randi([0 2^8-1], numOctets, 1), 2); netFrame = zigbee.NETFrameGenerator(netConfig, payload);
You can further explore the following generator and decoding functions, as well as the configuration object:
- ZigBee Alliance, ZigBee Specification Document 053474r17, 2007
- IEEE 802.15.4-2011 - IEEE Standard for Local and metropolitan area networks--Part 15.4: Low-Rate Wireless Personal Area Networks (LR-WPANs)