Zigbee Wireless Protocol in wireless sensor networks and IoT
- 2. Features • It supports for multiple network topologies such as point-to-point, point-tomultipoint and mesh networks. • Its low duty cycle - provides long battery life. • It has low latency. • It uses Direct Sequence Spread Spectrum (DSSS). • It can have up to 65,000 nodes per network. • It has 128-bit AES encryption for secure data connections. • It is collision avoidance, provides retries and has acknowledgements. • The IEEE 802.15.4 MAC sublayer is in control of what is happening on the radio link. • Acknowledgment, retransmission, flow control, and network synchronization tasks are managed by the IEEE 802.15.4 MAC sublayer. • The specification is a packet-based radio protocol intended for low-cost, battery operated devices.
- 5. COMMUNICATION MODE • Zigbee two way data is transferred in two modes namely, non-beacon mode and beacon mode. • In a beacon mode, the coordinators and routers continuously monitor active state of incoming data hence more power is consumed. In this mode, the routers and coordinators do not sleep because at any time any node can wake up and communicate. However, it requires more power supply and its overall power consumption is low because most of the devices are in an inactive state for over long periods in the network. • In a beacon mode, when there is no data communication from end devices, then the routers and coordinators enter into sleep state. Periodically this coordinator wakes up and transmits the beacons to the routers in the network. These beacon networks are work for time slots which means, they operate when the communication needed results in lower duty cycles and longer battery usage. These beacon and non-beacon modes of Zigbee can manage periodic (sensors data), intermittent (Light switches) and repetitive data types.
- 6. SECURITY • Zigbee 3.0 provides enhanced network security. There are two methods of security that give rise to two types of network namely, • Centralized security : This method employs a coordinator/trust center that forms the network and manages the allocation of network and link security keys to joining nodes. • Distributed security : This method has no coordinator/trust center and is formed by a router. Any Zigbee router node can subsequently provide the network key to joining nodes. • Nodes adopt whichever security method is used by the network they join.
- 7. ADVANTAGES • The zigbee has flexible network structure. • It has a very long battery life. • It is low power consumption. • It is easy to install. • It can be easily implemented. • It supports large number of nodes i.e. 6500 nodes approximately. • It has a very low cost. • It is more reliable and self healing. • Setting up the network is very simple and easy. • Its network is very scalable. • It is less complex than Bluetooth • A consumer has complete authority to add or remove devices as user sees fit. • Since devices use Zigbee RF protocol, the all old IR devices are replaced
- 8. Disadvantages • It is so highly risky to be used for official private information. • Low transmission as well as low network stability, are some of Zigbee’s disadvantages that takes it a step back as compared to others. • Replacement with Zigbee compliant appliances can be costly. • It does not have many end devices available yet. • It cannot be used as outdoor wireless communication system due to it has short coverage limited. • Zigbee is vulnerable to various zigbee wireless mesh protocol. • It is not secure like Wi-Fi based secured system. • Its high maintenance cost, lack of total solution, and slow materialization.
- 9. Energy Efficient Routing Protocol • Minimize energy per packet (or per bit) • Maximize network lifetime • Routing considering available battery energy • Maximum Total Available Battery Capacity • Minimum Battery Cost Routing (MBCR) • Min–Max Battery Cost Routing (MMBCR) • Minimum Total Transmission Power Routing (MTPR)
- 10. Transport Layer • Common Transport Layer Protocol Attributes are as follows, • Reliable data transport - This task requires the ability to detect and repair losses of packets in a multi-hop wireless network. • Flow control - The receiver of a data stream might temporarily be unable to process incoming packets because of lack of memory or processor power. Flow control has so far not been a research issue in sensor networks. • Congestion control - Congestion occurs when more packets are created than the network can carry and the network starts to drop packets. Dropping packets is a waste of energy and counteracts any efforts to achieve reliability or information accuracy. Congestion-control schemes try either to avoid this situation or to react to it in a reasonable manner. One important way to avoid congestion is to control the rate at which sensor nodes generate packets. • Network abstraction - The transport layer offers a programming interface to applications, shielding the latter from the many complexities and vagaries of data transport. Since there is yet no standard transport protocol in sensor networks, there is no consensus on such an interface.
- 11. Challenges • The major challenges of transport layer protocols used in WSNs are as follows, • Providing reliable data delivery • Configuring sensor node to suit for the specific application • High packet loss due to poor link condition • Rapid change of network topology • Multipath routing • Frequent path break in end-to-end connectivity due to node failure • End-to-end error recovery