Comparison of Different Wireless Standards:
The following table can be used to compare the different wireless standards.
From the table above, it is observed that Zigbee has additional features comparing to the other wireless standards. Hence the detailed functions of the Zigbee and its functioning are discussed below.
The Zigbee’s network in integration with PHY and MAC layer of IEEE 802.15.4 specification provides the following features
- Reliability in data transfer
- Minimal power consumption
- Security at desired levels
- Low cost and Flexible installation procedure for devices.
The main advantage of Zigbee protocol is support for “co-existence” and “interoperability” to communicate and function with them with interference.
The Zigbee architectural frame work consists of PHY layer and MAC layer that accounts for IEEE specification 802.15.4 to support coexistence. It adopts “DSSS (Direct Sequence Spread Spectrum)” that enables peer – to – peer radio communication. It also validates data rates, Modulation schemes and channelization techniques as specified in the protocol.
Physical Layer (IEEE 802.15.4 PHY) is implicated in exchanging data bits with the physical medium (Say radio) and the layer above it i.e. Data Link Layer (DLL).
Data Link Layer (IEEE 802.15.4 MAC) is responsible for addressing of frames. It maintains a track of outgoing and incoming data packets. It uses MAC frames. It’s main functions are:
- Assembling data frames required for transmission.
- Decomposing received frames.
Zigbee stack implements Zigbee functionalities like network mapping, routing, and Security measures such as Encryption, Authentication, and Key Mgmt. And, it also acts as mucilage between the application layer and the combined PHY and MAC layers.
The Application level consists of the applications that are required for node function. It converts input into digital format and reconverts Digital data into criteria suitable for output.
The Application layer is defined by two profiles namely, (1) Public Profiles, & (2) Private Profiles.
- Public Profiles: For the intention of interoperability.
- Private Profiles: Intended for use in closed systems.