Friday, September 29, 2017

ZigBee for IoT

The ZigBee and Z-Wave short-range wireless technologies are used for remote monitoring and control. However, their specifications and applications are different. Both technologies are ideal for home-area networks (HANs), which is becoming an in.

Differences between ZigBee and Z-Wave:

TechnologyFrequencyModulationData RateRangeApplications
ZigBee902 to 928 MHz (Americas and Australia)2.4 - 2.483 GHz (ISM)BPSK (900 MHz band) or
OQPSK (2.4 GHz band)
250 kbps10 mHome Automation, Smart Grid, Remote control
Z-Wave908.42 MHzGFSK9.6/40 kbps30 mHome Automation, security

It is ratified in the IEEE’s 802.15.4 personal-area network (PAN) radio standard. ZigBee is an open wireless standard from the ZigBee Alliance. The IEEE 802.15.4 standard provides layer 1 (physical layer, or PHY) and layer 2 (media access controller, or MAC) of the network, while the ZigBee stack software provides the network and application layers.

The Zigbee protocol is designed to communicate data through hostile RF environments that are common in commercial and industrial applications.

Zigbee protocol features include:
  • Support for multiple network topologies such as point-to-point,
  • point-to-multipoint and mesh networks
  • Low duty cycle – provides long battery life
  • Low latency
  • Direct Sequence Spread Spectrum (DSSS)
  • Up to 65,000 nodes per network
  • 128-bit AES encryption for secure data connections
  • Collision avoidance, retries, and acknowledgments (CSMA/CA)

ZigBee Physical Layer
ZigBee PHY operates in various bands, but the most common one is in the 2.4 GHz band. It uses offset quadrature phase-shift keying (OQPSK) that transmits two bits per symbol. In 900 MHz band, it uses BPSK for modulation.  The radio uses DSSS for digital streaming.

There are three (3) kind of devices in ZigBee:
  1. ZigBee Coordinator (ZR)
  2. ZigBee Router (ZR)
  3. ZigBee End Device (ZED)

No comments:

Post a Comment