ECE Senior Capstone Project 2017 Tech Notes

How Bluetooth Works

By Jeffrey Wu, ECE 17

Introduction

• Objective: Understand Bluetooth as a communication technology, particularly for Indoor Navigation for the Visually Impaired.
• Application: System for low vision individuals to navigate autonomously in buildings.
• Advantages of Bluetooth:
  • Low power usage.
  • Effective for location tracking and communication.
  • Versatile tool for various wireless/ad hoc networks.
  • Knowledge of Bluetooth enhances understanding of communication protocols.

History of Bluetooth

• Initial Purpose: Alternative to cables, creating a universal telecommunications protocol standard.
• Characteristics:
  • Short-range wireless communication.
  • Forms ad hoc networks for information exchange/broadcast.
• Current Uses:
  • Dynamic Personal Area Networks (PANs).
  • Hands-free phone connections, speakers, computer-electrical component connections.

Bluetooth Functionality

• Operation Modes:
  • Basic Rate (BR).
  • Low Energy (LE).
• Basic Rate Features:
  • Enhanced Data Rate (EDR) for higher data transfer and complexity at a higher cost.
• Frequency Range:
  • Operates between 2.4 GHz and 2.4835 GHz.
  • 79 bands, 1 MHz wide each, spaced by 1MHz.
  • Guard bands: 2 MHz at the bottom, 3.5 MHz at the top.

Device Discovery Process

• Connection Establishment:
  • Inquiry packets sent by one device.
  • Discoverable device scans channels for inquiry packets.
  • Connection setup via Frequency Hopping Synchronization (FHS) packet.
  • Devices communicate and hop channels for bandwidth efficiency.

Communication Techniques

• Frequency Hopping & Packet Switching:
  • Data sent in small packets with order numbers.
  • Packets find the fastest route to the receiver.
  • Synchronization via a master device controlling clock and pattern.

Bluetooth Low Energy (LE)

• Frequency Band Use:
  • Same band as BR and EDR but only 40 channels with 2 MHz separation.
• Channels:
  • 3 advertising channels for packet transmission and reception.
• Communication Process:
  • Advertiser sends packets, scanner receives.
  • Initiator listens for connectable packets to establish a connection.
  • Uses frequency hopping for efficient transmission.

Advantages and Limitations

• Advantages:
  • Quick, low-power one-way communication.
  • Versatile for two-way communication similar to BR.
• Drawbacks:
  • Fewer channels than BR, leading to slower transmission.

Conclusion

• Utility of Bluetooth:
  • Easy to use, set up, and cost-effective.
  • Viable option for the Indoor Navigation project if location accuracy is sufficient.
• Versatility:
  • Wide applicability in various projects and solutions.

References

• Sources:
  • Bluetooth Core Specification, BluePos studies, RSSI-based indoor localization.
  • Advanced computing and localization systems research.

This document serves as a comprehensive overview of Bluetooth technology, focusing on its history, functionality, and application in specific projects like Indoor Navigation for the Visually Impaired.