PowerPointPrsentation

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Design of Systems-on-a-Chip for Communication
Applications New Connections with
Michael Römer
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New Connections with Bluetooth

• General Introduction
• System Architecture
• Communication
• An Example Ericsson Intellectual Property

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1. Introduction

• What is Bluetooth ?
• New technology standard for wireless
  communication between devices
• Short-range radio link
• Low-power and low-cost modules
• Open specification aiming
  compatibility

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1. Introduction

• Bluetooth History
• Named after Viking king Harald Blaatand 940-981
  king of Denmark
• 1994 the decision was born by Ericsson to invent
  a radio link between mobile phones
• New opportunities for new usage models

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1. Introduction

• The Special Interest Group (SIG)
• Founded 1998 by Ericsson, IBM, Intel, Nokia
  and Toshiba
• Developed an open global standard for wireless
  radio connectivity
• Defines a Specification and Profiles
• Interoperability between different devices from
  various manufacturers

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2. System Architecture

• Overview
• Low-cost, low-power and small sized single-chip
  solution in CMOS technology
• Operates via radio transceiver in a globally
  available license-free frequency band
• Radio link allows ad hoc networking

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2. System Architecture

• 2.1 Bluetooth System
• Consisting of a Bluetooth Module and a Bluetooth
  Host
• Module is partitioned into the radio unit, the
  baseband unit and the Host Controller firmware
• Host consists of the software protocol stack and
  the application software

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Bluetooth System

• Radio transceiver enables the wireless link
  between devices
• Baseband is a controller, establishing and
  maintaining the connection
• Host Controller realizes communication between
  Module and Host
• Application software is user specified and
  implements the device functionality

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2.1 Bluetooth System

• Bluetooth Radio
• Communication between devices
• License free ISM band at 2.4 to 2.48 GHz
• Short range 10 m and medium 100 m
• Uses frequency hopping
• Supports data and voice
• Converts digital baseband
• data to an analog signal

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2.1 Bluetooth System

• Baseband
• Includes the Link Controller (LC)
• Connects Host Controller to Radio
• Functionality of clock synchronizing and
  connection establishment
• Data packet constructing decoding, crypting
  encrypting, hop selection

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Module Structure
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2.2 Software Protocol Stack

• Overview
• Driver code, allowing information exchange
  between application and Bluetooth Module
• Lower layer protocols
• Higher layer protocols
• Reuse of existing protocols and standardized data
  link

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Software Layers
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Bottom to Top protocol stack

• Incoming data from the Baseband ?
• Link Manager Protocol (LMP)
• establishes connection and receives packets ?
• Service Discovery Protocol (SDP)
• Reveals application abilities ?
• Logical Link Control and Adaptation Protocol
• (L2CAP) delivers data packets to application

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2.2 Software Protocol Stack

• Link Manager (LM)
• Enabling the physical connection via Link
  Controller (LC)
• Transmitting/receiving data
• Setting up connection and link mode
• Authentication
• Ensuring correct transmission mode

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2.2 Software Protocol Stack

• Host Controller Interface (HCI)
• Firmware connecting Host and Module
• Standard interface, independant of host hardware
  implementation
• Supports different physical connections (e.g.
  USB, PCI)
• HCI driver located in the Host

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2.2 Software Protocol Stack

• Higher layer Protocols
• Transfer Application information from Host to
  Module
• L2CAP segmentation reassembly of larger data
  packages and multiplexing
• RFCOMM emulating a serial port
• SDP Service Discovery Protocol
• OBEX object exchange client-server model

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Software Protocol Stack
Bluetooth Core Protocols (LMP, L2CAP, SDP)
Cable Replacement Protocol RFCOMM
Adopted Protocols (OBEX, UDP/TCP/IP, WAP)
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2.2 Software Protocol Stack

• Application Software
• Part of the Host and specified by the device
  manufacturer
• Above the higher layer software
• Defines the ability of the particular device

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Entire Bluetooth System
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3. Communication

• 3.1 Network Topology
• Supports point-to-point and
  point-to-multipoint connections
• Piconets and Scatternets
• Devices within range can be
  added or disconnected to
  the network immediately
  ad hoc networks

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3.1 Network Topology

• Piconet
• Consists of one master multiple slaves
• All units share one channel (bandwidth)
• All units are synchronized to one hopping
  frequency sequence
• Max. 8 units communicating

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3.1 Network Topology

• Scatternet
• Several Piconets in overlapping areas linked
  together, form a Scatternet
• Each piconet works independantly on its own
  frequency hopping channel
• Units can switch from one piconet to another
• Up to 10 piconets defined by Specification

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Scatternet
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3. Communication

• Frequency-hopping channels
• Bluetooth radios use frequency-hop (FH)
  technology to avoid interference
• Channels are divided into 625 µs intervals
  (slots) of different hop frequencies
• Nominal hop rate of 1600 hops/s
• Hopping sequence of a piconet is determined by
  the master

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Frequency-hop channel
Hop selection
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3. Communication

• Packet format
• Determined format Access code, packet header
  and optionally the payload
• Channel supports multi-packets
  
• one, three or five slots per packet
• Synchronous Connection-Oriented (SCO) links used
  for voice packets
• Asynchronous Connection-Less (ACL) links support
  multiple-slot data packets

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Connection Speed
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3. Communication

• Connection establishment
• Bluetooth devices are in standby mode by default
• Wake-up sequence visits 32 hop carriers randomly,
  based on unit identity
• Master scans for available units
  inquiry scan page scan

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3. Communication

• Connection Modes
• Active mode device is assigned a 3 bit address
  and participates actively
• Hold mode allows SCO links, one of three power
  saving modes
• Sniff mode allows SCO and ACL links, used to
  participate in two piconets
• Park mode listens to messages, but does not
  participate actively

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3. Communication

• Piconet communication
• Master controls all traffic on the channel
• Slaves add an offset to their clock to
  synchronize
• Only one slave is permitted to send a packet in a
  slave-to-master slot
• LMP enables the link, SDP discovers the
  application service and L2CAP opens a
  communication channel for the application

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3. Communication

• Scatternet communication
• Piconet units share a 1 MHz channel
• Increasing throughput by using a Scatternet
• Piconet packets are distinguished by access code
• Units may change Piconets by adjusting their
  clock and identity to the new Master

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3. Communication

• Security
• Authentication keys to prevent spoofing
• Encryption to prevent eavesdropping
• 48 bit device address
• 128 bit private user key
• Frequency hopping itself increases security

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4. Ericsson IP

• Ericsson Bluetooth Core Product (EBCP)
• Baseband SoC Intellectual Property
• Reduces cost by receiving a fully functional
  system
• Consisting of three development boards, Bluetooth
  Core, AMBA Baseband Controller, higher and lower
  layer protocols, and testing software

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EBCP hardware components
EBCP block diagram
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4. Ericsson IP

• Ericsson Bluetooth Module
• Complete solution for implementing Bluetooth
  functionality
• Consists of the three major parts
  baseband controller, memory flash and
  the radio transceiver
• Designed for two-processor solution higher
  layer protocols not included

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Ericsson Bluetooth Module
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4. Ericsson IP

• Ericsson Bluetooth Development Kit (EBDK)
• Develop applications to use with the Bluetooth
  Module
• Easiest way for first-time developer
• Launching time to markt is minimized
• Less customizable than the EBCP

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Ericsson Bluetooth Development Kit
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Summary

• Besides cable replacement Bluetooth wireless
  technology offers new network opportunities
• SIG is joined by more than 1900 members, helping
  Bluetooth to succeed on the market

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