Mumbai University > Electronics Engineering > Sem 8 > Advanced Networking Technologies

Marks: 10M

1. A ZigBee system consists of several components. The most basic is the device.
2. A device can be a full-function device (FFD) or reduced-function device (RFD). A network includes at least one FFD, operating as the personal area network (PAN) coordinator.
3. The FFD can operate in three modes: a PAN coordinator, a coordinator, or a device.
4. An RFD is intended for applications that are extremely simple and do not need to send large amounts of data.
5. An FFD can talk to reduced-function or full-function devices, while an RFD can only talk to an FFD.
6. ZigBee supports three types of topologies: star topology, peer-to-peer topology, and cluster tree

7. a. In the star topology, communication is established between devices and a single zcentral controller, called the PAN coordinator.

   b. The PAN coordinator may be powered by mains while the devices will most likely be battery powered.

   c. Applications that benefit from this topology are home automation, personal computer (PC) peripherals, toys, and games.

   d. After an FFD is activated for the first time, it may establish its own network and become the PAN coordinator.

   e. Each star network chooses a PAN identifier, which is not currently used by any other network within the radio sphere of influence. This allows each star network to operate independently.

8. a. In the peer-to-peer topology, there is also one PAN coordinator.

   b. In contrast to star topology, any device can communicate with any other device as long as they are in range of one another.

   c. A peer-to-peer network can be ad hoc, self-organizing, and self-healing.

   d. Applications such as industrial control and monitoring, wireless sensor networks and asset and inventory tracking would benefit from such a topology.

   e. It also allows multiple hops to route messages from any device to any other device in the network. It can provide reliability by multipath routing.

9. a. The cluster-tree topology is a special case of a peer-to-peer network in which most devices are full-function devices and an RFD may connect to a cluster-tree network as a leaf node at the end of a branch.

   b. Any of the full-function devices can act as a coordinator and provide synchronization services to other devices and coordinators. However, only one of these coordinators is the PAN coordinator.

   c. The PAN coordinator forms the fi t cluster by establishing itself as the cluster head (CLH) with a cluster identifier (CID) of zero, choosing an unused PAN identifier, and broadcasting beacon frames to neighbouring devices.

   d. A candidate device receiving a beacon frame may request to join the network at the cluster head.

   e. If the PAN coordinator permits the device to join, it will add this new device to its neighbour list.

   f. The newly joined device will add the cluster head as its parent in its neighbour list and begin transmitting periodic beacons such that other candidate devices may then join the network at that device.

   g. Once application or network requirements are met, the PAN coordinator may instruct a device to become the cluster head of a new cluster adjacent to the first one.

   h. The advantage of the clustered structure is the increased coverage at the cost of increased message latency.