ZIGBEECompared to

BLUETOOTHBy,

Karthik Reddy kotha910-02-0670

Presentation Outline

What ZigBee isWhat ZigBee doesHow ZigBee worksBluetooth.Differences and similarities between Zigbee

and Bluetooth. how to make them coexist.

ZigBee

What is ZigBee?

• ZigBee is a standard wireless network protocol designed for low data rate control networks.

• It is layered on top of the IEEE 802.15.4 specification and provides a standard methodology for functions, including network formation, messaging and device discovery.

• for the unique needs of remote monitoring and control applications, including simplicity, reliability, low-cost and low-power.

ZigBee

Zigbee characteristics

• 2.4GHz and 868/915 MHz • The number of channels allotted to each frequency band is fixed at 16

channels in the 2.45 GHz band, 10 channels in the 915 MHz band, and 1 channel in the 868 MHz band.

• Maximum data 250 kbps @2.4 GHz, 40 kbps @ 915 MHz, and 20 kbps @868 MHz.

• Allocation of guaranteed time slots (GTSs).• Carrier sense multiple access with collision avoidance (CSMA-CA)

channel access Yields high throughput and low latency for low duty cycle devices like sensors and controls.

• Low power consumption with battery life ranging from months to years. Energy detection (ED).Link quality indication (LQI).

CHANNELS

What Does ZigBee Do?

• Designed for wireless controls and sensors• Operates in Personal Area Networks (PAN’s) and

device-to-device networks• Connectivity between small packet devices• Control of lights, switches, thermostats, appliances,

etc.

ZigBee

ARCHITECTURE

ZigBee Application layer

ZigBee Network layer

802.15.4 MAC

802.15.4 PHY E868/915 Mhz

802.15.4 PHY

Physical (PHY) layer:• The PHY service enables the transmission and reception of PHY protocol

data units(PPDU) across the physical radio channel.The features of the IEEE 802.15.4 PHY physical layer are Activation and deactivation of the radio transceiver, energy detection (ED), Link quality indication (LQI), channel selection, clear channel assessment (CCA) and transmitting as well as receiving packets across the physical medium.

Media access control (MAC) layer:• The MAC service enables the transmission and reception of MAC protocol

data units (MPDU) across the PHY data service. The features of MAC sub layer are beacon management, channel access, GTS management, frame validation, acknowledged framedelivery, association and disassociation.

How ZigBee Works

• Topology– Star– Cluster Tree– Mesh

ZigBee

How ZigBee Works

• States of operation– Active– Sleep

• Devices– Full Function Devices (FFD’s)– Reduced Function Devices (RFD’s)

ZigBee

STAR TOPOLOGY

CLUSTER NETWORKS

Zigbee mesh network

s

Research in ZigBee is being conducted in different fields:

• Wireless and sensor networks.• Wireless communications.• Neuro-engineering.

ZigBee

• ZIGBEE Coexistence with other standards– Relatively wideband interference, such as that

generated by IEEE 802.11b networks– Impact of interference from Bluetooth (802.15.1)

devices should be minimal.

Bluetooth

• Bluetooth operates in the unlicensed 2.4 gigahertz (GHz) to 2.4835 GHz .

• Bluetooth employs frequency hopping spread spectrum (FHSS) technology for all transmissions.

• FHSS reduces interference and transmission errors and provides a limited level of transmission security.

Bluetooth architecture• Bluetooth permits devices to establish either ad hoc or infrastructure

networks. • Ad hoc networks provide easy connection establishment between mobile

devices in the same physical area (e.g., the same room) without the use of any infrastructure devices. A Bluetooth client is simply a device with a Bluetooth radio and software incorporating the Bluetooth protocol stack and interfaces.

Bluetooth Ad Hoc Topology

Bluetooth Networks (Multiple Scatternets)

Coexistence components

• 1. Channel estimation • 2. MAC layer protocol behavior • 3. Channel selection• 4. Modulation• 5. Protocol collaboration

-> Channel estimation:-1 .Received Signal Strength Indication2. Carrier Sense3. Packet Error Rate4. Packet Acknowledgment

->MAC Layer Protocol Behavior:1. Bluetooth packet size selection2. Backoff and scheduling.

-> Channel Selection:Channels may be dynamically selected based on the channel status– IEEE 802.11b DSSS selects a center channel– Zigbee dynamically selects a channel at initialization and during normal Operation.– Bluetooth may reduce its hopping set in response to channel assessment information.

-> Modulation: • Spread spectrum techniques

– a transmission bandwidth that is several orders of magnitude greater than the minimum required signal bandwidth so that many users can simultaneously use the same bandwidth.– Pseudorandom signal with noise-like properties– Inherent interference rejection capability– Elimination of narrowband interference– Resistance to multipath fading due to frequency diversity.

-> Protocol Collaboration:Collaborative methods rely on communication between different protocols at a specific protocol layer in order to achieve coexistence– Protocols implemented on the same physical device can be collaborative– Multi-radio and “cognitive radio” technologies

Differences between Zigbee and Bluetooth

Zigbee Bluetooth

Application focus Monitoring and control Cable replacement

System resources 4KB-32KB 250KB+

Battery life 100-1000+ 1-7

Network size Unlimited 7

Bandwidth 20-250 720

Transmission range 1-100+ 1-10

Success metrics Reliability, power, cost Cost convenience

Typical network join timeBluetooth: 3 secondsZigBee: 30 milliseconds

similarities• Bluetooth and ZigBee have much in common. Both are types of IEEE

802.15 "wireless personal-area networks," or WPANs. Both run in the 2.4-GHz unlicensed frequency band, and both use small form factors and low power.

• Bluetooth and Zigbee eliminates cabling between electronic products and accessories .

• They use spread spectrum modulation techniques.• They are both short range devices .

ZigBee’s Future

ZigBee

CONCLUSION The ZigBee Standard enables the broad-based deployment of reliable

wireless networks with low complexity, low cost solutions and provides the ability for a product to run for years on inexpensive primary batteries. The mission of the ZigBee Working Group is to bring about the existence of a broad range of interoperable consumer devices by establishing open industry specifications for unlicensed, control and entertainment devices requiring the lowest cost and lowest power consumption communications between compliant devices anywhere in and around the home.

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