BLUETOOTH Overview

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BLUETOOTHOverview
I am King Harold Bluetooth who unified warring
Viking Tribes in the 10th Century. In the 21st
Century a wireless Bluetooth network is named
after me.
Where are my shoes?
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Bluetooth Overview
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Bluetooth SIG -- more

• February 1998 The Bluetooth SIG is formed
• promoter company group Ericsson, IBM, Intel,
  Nokia, Toshiba
• May 1998 The Bluetooth SIG goes public
• July 1999 1.0A spec (gt1,500 pages) is published
• December 1999 ver. 1.0B is released
• December 1999 The promoter group increases to 9
• 3Com, Lucent, Microsoft, Motorola
• February 2000 There are 1,500 adopters
• adopters "enjoy" royalty free use of the
  Bluetooth technology
• products must pass Bluetooth certification

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General Description

• A cable replacement technology
• Operates in the unlicensed ISM band at 2.4 GHz
• Frequency Hopping scheme (1600 hops/sec)
• 1 Mb/s symbol rate
• Range 10 meters
• Single chip radio baseband
• Key features
• Robustness
• low complexity
• low power, and
• low cost.

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General Description (2)

• Bluetooth supports
• Synchronous asynchronous data channels.
• Three simultaneous synchronous voice channels, or
  
• One channel, with asynchronous data and
  synchronous voice
• Each voice channel supports 64 kb/s in each
  direction.
• The channel can support max-imal 723.2 kb/s
  asymmetric (and still up to 57.6 kb/s in the
  return direction), or 433.9 kb/s symmetric.
• Bluetooth provides
• point-to-point connection (only two BlueTooth
  units involved), or
• point-to-multipoint connection.

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Piconet

• One unit acts as the master of the Piconet,
  whereas the others acts as slaves.
• Up to seven slaves can be active.
• More slaves can be synchronized locked to the
  master in parked state.
• The channel access for all the slaves in a
  piconet is controlled by the master.

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Piconet (2)
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Scatternet

• Scatternet is formed by multiple Piconets with
  overlapping coverage areas.
• Each Piconet can only have a single master
• Slaves can participate in different Piconets on a
  time-division multiplex basis.
• A master in one Piconet can be a slave in
  another Piconet.
• Each Piconet has its own hopping channel in a
  Scatternet.

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Scatternet (2)
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New Application Scenarios

• Data Access Points
• Synchronization
• Headset
• Conference Table
• Cordless Computer
• Business Card Exchange
• Instant Postcard
• Computer Speakerphone

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Bluetooth Specifications
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Bluetooth Stack
Applications
SDP
RFCOMM
Audio
L2CAP
Link Manager
Baseband
RF

• A hardware/software/protocol description
• An application framework

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Interoperability Profiles

• A profile represents a default solution for a
  usage model
• Vertical slice through the protocol stack
• Basis for interoperability and logo requirements
• Each Bluetooth device supports one or more
  profiles

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Technical Overview
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Bluetooth Radio Specification
Applications
SDP
RFCOMM
Audio
L2CAP
Link Manager
Baseband
RF
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Radio

• Low Cost
• Single chip radio (minimize external components)
• Todays technology
• Time division duplex
• Low Power
• Standby modes
• Sniff, Hold, Park
• Low voltage RF
• Robust Operation
• Fast frequency hopping 1600 hops/sec
• Strong interference protection
• Fast ARQ
• Robust access code
• Forward header correction

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Baseband
Applications
SDP
RFCOMM
Audio
L2CAP
Link Manager
Baseband
RF
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Connection Setup

• Inquiry - scan protocol
• to lean about the clock offset and device address
  of other nodes in proximity

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Piconet formation

• Page - scan protocol
• to establish links with nodes in proximity

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Addressing

• Bluetooth device address (BD_ADDR)
• 48 bit IEEE MAC address
• Active Member address (AM_ADDR)
• 3 bits active slave address
• all zero broadcast address
• Parked Member address (PM_ADDR)
• 8 bit parked slave address

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Piconet channel
FH/TDD
f1
f3
f4
f5
f2
f6
m
s1
s2
625 ?sec
1600 hops/sec
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Multi slot packets
FH/TDD
f1
f4
f5
f6
m
s1
s2
625 ?sec
Data rate depends on type of packet
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Packet Format
54 bits
72 bits
0 - 2745 bits
Access code
Header
Payload
Error correction 1/3 rate FEC 2/3 rate FEC ARQ
scheme for the data
Synchronization identification Filtering
Address Packet Type Flow control ARQ SEQN HEC
Smaller than an ATM cell ! Notice that there is
no protocol type field
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Physical Link Types

• Synchronous Connection Oriented (SCO) Link
• slot reservation at fixed intervals
• No ARQ, No CRC
• FEC (optional)
• 64 Kbps
• Asynchronous Connection-less (ACL) Link
• Polling access method
• ARQ, CRC
• FEC (optional)
• Symmetric data rate 108 - 433 Kbps
• Asymmetric data rate up to 723 Kbps

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Mixed Link Example
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Inter piconet communication
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Scatternet, scenario
How to schedule presence in two
piconets? Forwarding delay ? Missed traffic?
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Link Manager Protocol

• Setup and Management
• of Baseband connections
• Piconet Management
• Link Configuration
• Security

Applications
SDP
RFCOMM
Audio
L2CAP
Link Manager
Baseband
RF
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Link Manager Protocol

• Piconet Management
• Attach and detach slaves
• Master-slave switch
• Establishing SCO and ACL links
• Handling of low power modes ( Sniff, Hold, Park)
• Link Configuration
• packet type negotiation
• power control
• Security functions
• Authentication
• Encryption

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L2CAP
Logical Link Control and Adaptation Protocol

• L2CAP provides
• Protocol multiplexing
• Segmentation and Re-assembly
• Quality of service negotiation
• Group abstraction

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L2CAP Packet Format (CO)
16 bits
15 bits
0 - 64K bytes
DCID
Payload
Length
Minimum MTU is 48 bytes ! default is 672 bytes !
Baseband packets
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L2CAP Packet Format (CL)
16 bits
15 bits
0 - 64K bytes
DCID
Payload
PSM
Length
Baseband packets
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Serial Port Emulation using RFCOMM
Applications
SDP
RFCOMM

• Serial Port emulation on top of a packet oriented
  link
• Similar to HDLC
• For supporting legacy apps

Audio
L2CAP
Link Manager
Baseband
RF
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Bluetooth Service Discovery Protocol
Applications
SDP
RFCOMM
Audio
L2CAP
Link Manager
Baseband
RF
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Usage of SDP

• Establish L2CAP connection to remote device
• Query for services
• search for specific class of service, or
• browse for services
• Retrieve attributes that detail how to connect to
  the service
• Establish a separate (non-SDP) connection to user
  the service

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IP over Bluetooth V 1.0
Applications
SDP
RFCOMM
GOALS

• Internet access using cell phones
• Connect PDA devices laptop computers to the
  Internet via LAN access points

Audio
L2CAP
Link Manager
Baseband
RF
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LAN access point profile
IP
Access Point
PPP
RFCOMM
L2CAP
LMP
Baseband
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Research challenges
Internet
Plug-n-play applications
Resource Discovery
Routing over scatternets
Techniques for link formation
Techniques for Scatternets Formation

Will the current solutions for each layer work in
this environment?
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What is different in this scenario ?
Connection oriented, low-power link technology
Small, multi-hop networks
Simple devices
Isolated network
Dynamic network
Applications ---gt services ----gt routing ----gt
link creation
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Service discovery
Need solutions for address allocation, name
resolution, service discovery
Existing solutions in the Internet depend on
infrastructure
Judicious use of Multicast/broadcast is needed
These goals are similar to what Zero-conf WG is
already working on
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Routing over Scatternets
x5
Nodes must co-operate to forward packets (MANET
style protocols)
x1
y2
y1
Forwarding at Layer 2 or Layer 3?
x8
x6
x4
x2
Bridging or routing ?
x7
x3
What interface should be exported to the above
layer? Better coupling with the service discovery
layer is needed
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Routing in MANET

• No Routing
• Plain Flooding (PF)
• Proactive protocols
• Determine routes independent of traffic pattern
• Traditional link-state and distance-vector
  routing protocols are proactive
• Destination Sequence Distance Vector (DSDV)
• Link State Routing
• Reactive protocols
• Discover routes and maintain them only if needed
• Dynamic Source Routing (DSR)
• Ad-hoc On-Demand Distance Vector Routing (AODV)
• Hybrid protocols
• Zone Based Routing (ZBR)

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Routing In Bluetooth Scatternets (1)

• Two Approaches so far
• Maintain Active Routing Tables
• Flooding schemes
• Flood the network with routing query signals in
  order to discover a route
• Not efficient in real Bluetooth Networks

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Routing in Bluetooth Scatternets (2)

• The solution
• Apply existing ad-hoc routing protocols in
  Bluetooth Scatternets
• But
• Will they be well suited or we need to adapt them
  in Bluetooth ?
• Will they take advantage of Bluetooth specific
  characteristics ?
• Are they efficient indeed in Bluetooth ?
• Why ?

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Routing Vector Method

• Pravin Bhagwat and AdriannSegall, A routing
  Vector Method (RVM) for Routing in Bluetooth
  Scatternets

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Zone Routing Protocol

• Rohit Kapoor and Mario Gerla, A Zone Routing
  Protocol for Bluetooth Scatternets.

• Routing in Bluetooth Scatternets using a Zone
  Routing Protocol
• Hybrid solution
• Routing_zone a certain number of neighboring
  nodes
• Proactive Routing (with in the zone)
• Reactive Routing (out of zone)
• All nodes with in the zone area are aware of each
  the routes
• A large number of nodes will be included in the
  node (many piconets)
• In Bluetooth only master nodes can send to a
  node routing info so many master can be includes
  in the routing_zone
• Takes in to account the specifics of the
  Bluetooth MAC layer
• Routing information obtained from the proactive
  and reactive parts of the scheme is stored
  separately.

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Self-Routing Rrotocol

• Min-Te Sun, Chung-Kuo Chang and Ten-Hwang Lai, A
  Self-Routing Topology for Bluetooth Scatternets.

• Routing algorithm is based on b-trees that are
  embedded in a scatternet
• Routing and Scatternet formation is
• been issued with the same algorithm
• The procedure is fully automatic and
  distributed.
• This enables the self-routing
• No overhead for message routing
• Each node maintains a small fix-sized routing
  information table
• All the work is to construct the Blue-Tree
  Scatternet and then routing is easy
• Routing is then just like a usual search in a
  b-tree

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Concussions

• MANET routing protocols can not be used directly
  in Bluetooth Scatternets
• New protocols must be introduced
• Performance must be a major consideration
• Routing must be addressed together with
  Scatternet formation