Z-Wave Protocol

Z-Wave it is a wireless communication protocol used by automatic or automotive appliances for the purpose of connection and communication. It is invented in 1999 by Zensys a Danish-American company. In this article we are going to see some characteristics of Z-Wave, Components of Z-Wave, Z-Wave protocol stack, and some applications of Z-Wave.

Z-Wave Protocol Stack :

Z-Wave protocol stack contains five layers physical layer, MAC layer, transport layer, network layer, and application layer.

• PHY layer: This layer has many functions but the important one is modulation and coding. In this layer, data is transferred in 8-bit blocks and the most significant bit is sent first.
• MAC layer: MAC layer as the name suggests takes care of medium access control among slave nodes based on collision avoidance and backoff algorithms. also, it takes care of network operations based on Home ID, Node ID, and other parameters in the z-wave frame.
• Transport layer: Z-Wave transport layer is mainly responsible for retransmission, packet acknowledgement, and packet origin authentication. the z-wave layer consists of four basic frame types: 
  • Single cast frame  
  • ACK frame
  • Multicast frame 
  • Broadcast frame
• Network layer:  Z-Wave network layer controls the frame routing from one node to another node.
• Application layer: This layer is responsible for decoding and execution of commands in the z-wave network.

The following diagram shows us various layers of the z-wave protocol stack:

Z-Wave Components :

The components of z-wave include controllers, slave nodes, Home ID, Node ID, and routing tables.

• Controllers: A controller is a unit that has the ability to compile a routing table of the network and can calculate routes to the different nodes. There are two types of controllers – 
  • Primary controller: Primary controller is the device that contains a description of the z-wave network and controls the output. It assigns network ID or Home ID or Node ID to the z-wave during the enrollment process.  
  • Secondary controller: It also has a Network ID and it remains constant to maintain routing tables.
• Slave nodes:  Slave nodes are the nodes that do not contain routing tables but may contain a network map. slave nodes have the ability to receive frames and respond to them if necessary.
• Home ID:  The ID used by z-Wave for the separation of the network from each other is called Home ID. It is created by the primary controller and is 32-bit in size. 
• Node ID:  The identification number or an address that is given to every device during the process of inclusion is called Node ID. 
• Routing table:  It is used by controllers for calculating routes. 

The following diagram shows us z-wave network .

Characteristics of Z-Wave :

• Uses RF for signaling and control
• Frequency : 900 MHz (ISM)
• Range : 30 meter
• Data rates : upto 100 kbps
• FSK Modulation

  Applications of Z-Wave :

• Home automation
• Water management using flood sensors
• Fingerprint scanner