RFBluetooth Tutorial: Piconets, Scatternets, and Technology Overview
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This comprehensive Bluetooth tutorial offers the basics of the technology, including key concepts such as piconets and scatternets. Bluetooth facilitates wireless communication by forming small network clusters (piconets) and combining them into larger networks (scatternets). This page explores these network structures with diagrams, providing a solid foundation for understanding Bluetooth’s capabilities.
Nowadays, Bluetooth has become an integral part of our lives due to its immense applications in audio devices, including headsets and mobile phones, home stereos, MP3 players, laptops, desktops, tablets, and more. With Bluetooth, you can transfer data (meeting schedules, phone numbers), audio, graphic images, and video from one device to another, provided they are Bluetooth compliant.
IEEE 802.15.1 standard describes detailed Bluetooth specifications.
Bluetooth Network Topologies
Image alt: Bluetooth Network Toplogies
A Bluetooth network consists of many Bluetooth users. There are two primary types of network topologies in Bluetooth: Piconet and Scatternet.
Piconet
A piconet is formed by one master and one or more slaves. There will be a maximum of 7 active slaves in the piconet. Hence, there will be about 8 maximum devices communicating in a small network referred to as a piconet. Slaves can only transmit when they have been requested by the master Bluetooth device. There can be about 255 slaves in a parked state. Active slaves are polled by the master for transmission. Each station will get an 8-bit parked address. A total of 255 parked slaves are possible in one piconet. The parked station can join in just 2 ms. All the other stations can join in more time.
Scatternet
About 10 such piconets can exist in the Bluetooth radio coverage area. Combinations of multiple piconets are known as a scatternet. A device can participate in multiple piconets. It will timeshare and needs to be synchronized with the master of the current piconet. It supports data rates based on different versions, from 720 kbps to about 24 Mbps. It will have distance coverage from about 1 to 100 meters, based on the power class supported on Bluetooth devices.
Bluetooth Technical Specifications
The following table outlines the technical features of Bluetooth technology:
| Specification | Feature Supported |
|---|---|
| RF Frequency | 2.4GHz, |
| Transmit power | 100 mW(Max.) 1mW(Min.), |
| Data rate | About 1Mbps |
| Distance | 100 meter(max.), 1 meter(min.) |
| RF Bandwidth | 220 KHz to about 1MHz |
| Modulation type | Gaussian FSK (GFSK) |
| Number of RF carriers | 79(max.), 23(min.) |
| Topology | Up to 7 links in a star configuration |
| Hopping rate | 1600 hops per second |
| Access type | FH-TDD-TDMA |
Bluetooth Applications
Following are a few of the many Bluetooth applications:
- One can receive and make calls using a Bluetooth compliant wireless headset.
- Operate a computer using a mouse/keyboard and take printouts wirelessly, eliminating cables.
- Home automation.
Conclusion
A thorough understanding of Bluetooth technology and its network topologies (piconets and scatternets) enables developers to create scalable and efficient wireless communication systems.
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