Download - Wireless Personal Area Networks
Wireless Personal Area Networks
CS4422 Wireless and Broadband Networking
Dilum Bandara
Some slides extracted from ZigBee by J. Dohl, F. Diehm, & P. Grosa and
ZigBee by E. Ünal CSE 401 Special Topics In Computer Networks
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Outline Bluetooth ZigBee Ultra-Wideband
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OSI Stack
Source: http://walkwidnetwork.blogspot.com/2013/04/physical-layer-osi-model.html
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OSI vs. TCP/IP
Source: http://blog.anuesystems.com/category/span-and-taps/
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Bluetooth – IEEE 802.15.1 Developed by Ericson Now managed by Bluetooth Special Interest Group 2.4 – 2.48 GHz ISM band Range – 10 m Bandwidth – 2.1 Mbps (shared) (version 2.0)
Version 4.0 Includes Classic Bluetooth, Bluetooth high speed & Bluetooth low
energy protocols Bluetooth high-speed based on Wi-Fi Classic Bluetooth based on legacy Bluetooth protocols
Low power consumption Found in mobile phones, laptops, computer peripherals,
printers, etc.
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Bluetooth Applications Cable replacement
Phone to PC connection Connecting computing devices Digital imaging Smart car systems
Multiparty data exchange Exchange business cards, calendar events Share presentation material Synchronize information between multiple terminals Play multi-player games
Personal trusted device Reliable e-commerce transactions Local value added services Locking & access control
Stick N Find
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Bluetooth Piconet
Through master No slave-to-slave communication Up to 7 active slaves 255 parked slaves
Source: www.techrepublic.com/article/secure-your-bluetooth-wireless-networks-and-protect-your-data/6139987
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Bluetooth Scatternet By connecting 2+
piconets No direct support at
Baseband Layer
Source: www.techrepublic.com/article/secure-your-bluetooth-wireless-networks-and-protect-your-data/6139987
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Bluetooth Protocol Stack
Source: http://withfriendship.com/user/sathvi/bluetooth-stack.php
Protocols & Usage Models
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PPP
RFCOMM
TCP/IP
Baseband
L2CAP
OBEX
IrMC
TCS-BIN
Audio
SyncDial-up
net.
Usage Models
FileTransfer
AT-commands
Fax HeadsetLAN
AccessCordlessPhone
SDP
LMP
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Bluetooth Protocol Stack (Cont.)
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Bluetooth Applications/Profiles Set of application protocols Definitions of possible applications & specify general
behaviors Resides on top of Bluetooth core specification &
(optionally) additional protocols Example profiles
Hands-Free Profile (HFP) Basic Printing Profile (BPP) Audio/Video Remote Control Profile (AVRCP) File Transfer Profile (FTP) Human Interface Device Profile (HID) Personal Area Networking Profile (PAN) Generic Object Exchange Profile (GOEP)
OBEX
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Other Key Layers Link Management Protocol (LMP)
Set-up & control of radio link between 2 devices Logical Link Control & Adaptation Protocol (L2CAP)
Multiplex multiple logical connections between 2 devices using different higher-level protocols
Provides segmentation & reassembly of on-air packets Service Discovery Protocol (SDP)
Allows a device to discover services offered by other devices, & their associated parameters
Baseband layer Physical layer Manages physical channels & links Error correction, data whitening, hop selection, & security
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Physical Channel Required to use spread spectrum technology as
it’s in ISM band 79 RF channels spaced 1 MHz apart
Channel – frequency range in which communication occurs
Frequency hoping Channel represented by a pseudo-random hopping
sequence hopping through 79 channels Piconet – all devices use same channel
Hopping sequence is unique for the piconet & is determined by device address (BD_ADDR) of master
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Physical Channel (Cont.) Traffic controlled by master Master clock used for all timing & scheduling activities Master transmissions at even slots, slaves always at odd
slots Packet start aligned with slot start Packet extended over up to 5 slots
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Packets
Access code Used for timing synchronization, offset compensation, paging &
inquiry Header
Contains information for packet acknowledgement, packet numbering for out-of-order packet reordering, flow control, slave address, & error check for header
Payload Can contain either voice field, data field, or both
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ZigBee IEEE 802.15.4 covers physical layer & MAC
layer of low-rate WPAN ZigBee adds network construction, application
services, & more on top of IEEE 802.15.4 Star networks, peer-to-peer/mesh networks, &
cluster-tree networks By ZigBee Alliance
Very low power consumption long battery life Low data rate Low complexity circuits & small size low cost
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ZigBee Applications
Telecom Services
m-commerceinfo servicesobject interaction (Internet of Things)
ZigBeeWireless Control that
Simply Works
TVVCRDVD/CDremote
securityHVAClighting controlaccess controlirrigation
PC& Peripherals
asset mgtprocess control
environmentalenergy mgt
Personal Health Care
securityHVACAMR
lighting controlaccess control
patient monitoring
fitness monitoring
Source: http://zigbee.org/
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IEEE 802.15.4 Devıce Types LR-WPAN devices defined by IEEE 802.15.4
1. Full Functional Device (FFD) Can work as a PAN coordinator, as a coordinator, or
as a simple device Can communicate with either another FFD or a RFD
2. Reduced Functional Device (RFD) For applications that don’t need to transmit large
volumes of data & have to communicate only with a specific FFD
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IEEE/ZigBee Topologies
Source: http://wireless.arcada.fi/MOBWI/material/PAN_5_2.html
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ZigBee Topologies (Cont.)
1. Star Topology Pros
Easy to synchronize Low latency
Cons Small scale
2. Mesh/P2P Topology Pros
Robust multi-hop communication
Multi-path communication Flexible network Lower latency
Cons Route discovery is costly Needs to store routing
table
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ZigBee Topologies (Cont.)
3. Cluster Tree Topology Pros
Low routing cost Multi-hop communication Scalable
Cons Route reconstruction is costly Latency may be quite long Root not becomes a single point of failure
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ZigBee Protocol Stack
Source: www.sena.com/products/industrial_zigbee/zigbee_summary.php
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Physical Layer Defined in 802.15.4 2 different services
Data service Controls radio
Management service Energy detection in the channel Clear channel assesment before sending messages Link Quality Indication (LQI) for received packets
Bands
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ZigBee Frequency Bands
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PHY Protocol Data Unit (PPDU)
Preamble for chip & symbol synchronization Contains either data or data acknowledgement Packet size 8-127 Octets Contains MAC Protocol Data Unit (MPDU)
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MAC Layer 2 services
Data service Tx & Rx MPDUs
Management service If coordinator
Manages network beacons, PAN association & disassociation, frame validation, & acknowledgment
CSMA/CA for channel access
Support device security
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Traffic-Modes – Device to PAN Coordinator
Beacon mode Beacon send periodically Coordinator & end device
can go to sleep Lowest energy
consumption Precise timing needed Beacon period (ms-min)
Source: IEEE 802.15.4 Standard (2006)
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Traffic-Modes – Device to PAN Coordinator (Cont.)
Non-Beacon mode Coordinator/routers have
to stay awake Heterogeneous network Asymmetric power
Source: IEEE 802.15.4 Standard (2006)
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Data Transfer From PAN Coordınator
Source: IEEE 802.15.4 Standard (2006)
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MAC Layer – Managing PANs
Channel scanning Active, passive
PAN ID conflict detection & resolution Starting a PAN Sending beacons Device discovery Device association/disassociation Synchronization (beacon/nonbeacon) Orphaned device realignment
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MAC Layer – Frame Security Provided security features
Access control Data encryption Frame integrity Sequential freshness
Available security modes Unsecured mode ACL mode Secured mode
Available security suites AES-CTR AES-CCM AES-CBC-MAC
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Network Layer
Distributed address assignment Tree structure or self managed by higher layer 16-bit network space divided among child routers Child routers divide their space again for their children Depends on
Maximum child count per parent Maximum child-routers per parent Maximum network depth
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Network Layer (Cont.)
Route discovery Find or update route between specific source &
destination Started if no active route present in routing table Broadcast routing request (RREQ) packets Generates routing table entries for hops to source Endpoint router responds with Routing response
(RREP) packet Routes generated for hops to destination Routing table entry generated in source device
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Route DiscoveryRREQRREP
1 2 3
4
2
1
5
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Network Layer (Cont.)
Routing Check if routing table entry exists Initiate route discovery if possible Hierarchical routing as fallback
Route maintenance Track failed deliveries to neighbors Initiate route repair when threshold reached Careful with network load! In case of total connectivity loss
Orphaning procedure Re-association with network
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ZigBee Profiles
Describes a common language for exchanging data
Defines offered services Device interoperability across different
manufacturers Standard profiles available from the ZigBee
Alliance Profiles contain device descriptions Unique identifier (licensed by the ZigBee Alliance)
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ZigBee vs. BluetoothFeature(s) Bluetooth ZigBee
Power Profile days years
Complexity complex Simple
Nodes/Master 7 64000
Latency 10 seconds 30 ms – 1s
Range 10m 70m ~ 300m
Extendibility no Yes
Data Rate 1 Mbps 250 Kbps
Security 64bit, 128bit 128bit AES & Application Layer
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ZigBee vs. BluetoothS
HO
RT
<
R
AN
GE
>
L
ON
G
LOW < DATA RATE > HIGH
PAN
LAN
Text Graphics
Internet Hi-fi Audio
StreamingVideo
DigitalVideo
Multi-channelVideo
802.15.1Bluetooth1
802.15.1Bluetooth 2
802.15.4ZigBee
802.11b
802.11a/HL2 & 802.11g
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Ultra-Wideband Short-range technology for high-speed WPANs
3.1 – 10.6 GHz, 15 MHz channels (up to 5) 10 m
Applications – Cell phones, HDTV, DVD players, audio players, etc.
Source: www.ice.rwth-aachen.de/index.php?id=630&tx_felogin_pi1[forgot]=1&tx_iceprojects_pi1[uid]=155
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Ultra-Wideband (Cont.) Emit large no of very-short pluses over a wide
bandwidth Few nanoseconds or less
Gains few 100s of Mbps Channel capacity proportional to used bandwidth
No specific frequency allocation Operate on frequency band allocated to other
technologies Secure
Like other spread spectrum technologies
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Protocol Stack
Wireless USB, Wireless IP, Bluetooth over UWB, & IEEE1394 over UWB can be operated over a common radio platform
Source: http://research.nokia.com/page/244
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Summary Bluetooth
Spread Spectrum Moderate rate, short-range (10 m – 100 m)
ZigBee Low rate, low power, short range (10 m – 100 m)
Ultra-Wideband High rate, very-short range