Mumbai University > Information Technology > Sem 7 > Wireless Technology

Marks: 10M`

Year: Dec 2015

LR(low rate) wireless personal access network is intended to serve a set of industrial residential and medical applications with low power consumption, low cost requirement and relaxed needs for data rate and Qos.

Zigbee is a low data rate, networking protocol targeted towards automation and remote control applications.

Data rate is 250kbps at 2.4Ghz, 40kbps at 915MHz, 20kbps at 868MHz LRWPAN topologies:

• Star topology: communication between devices and a single central controller called PAN coordinator e.g. Home automation
• Mesh: one PAN coordinator. Any device can communicate to another device as long as they are in range of one another. e.g. industrial control and monitoring
• Cluster: most devices are FFD and RFD may connect to a cluster tree N/W as a leaf node at end of a branch.

Device architecture of 802.15.4(LR-WPAN)

LLC: logic link control

MAC: medium access control

SSCS: Service specific convergence sublayer

PHY layer: contains RF transceiver along with low-level control mechanism

MAC sublayer: access to physical channel for all types of transfer

N/W Layer (upper layer): message routing, configuration etc.

An IEEE 802.2 logical link control (LLC) can access MAC through SSCS