1. Ch 7. Wireless Personal Area Networks
Myungchul Kim

2. Wireless Personal Area Networks
WPANs
Bluetooth
Home Networking
UWB Overview
Wireless Sensor Networks

3. WPANs Short range networks (< 10 meters)
Used in homes, cars, small offices
Can be interconnected to form large networks
IEEE is the main standards environment
Many active areas of work: Bluetooth, UWB, Wireless sensor networks, Zigbees

4. Bluetooth Wireless LANs
Overview
Applications and Examples
Piconets and Scatternets
Standards Overview
Core standards

5. Bluetooth Overview Supports open-ended list of applications
Founders: Ericsson, IBM, Intel, Nokia, Toshiba; May 98
Currently: Over 1000 companies
Low-cost, short range radio link between mobile PCs, phones and other portable devices
2.4 GHz ISM band (unlicensed): Short packets, fast-hopping, and FEC limits impacts of interference
Software for service and device discovery
Typical application: cellular phone to PDA or earphone
Supports open-ended list of applications
Data, audio, graphics, video
Many products from Nokia, Motorola, Apple, etc.
Bluetooth.com and palowireless.com/bluetooth have great deal of info

6. Bluetooth PSTN Access Point Wired LAN Bluetooth Piconet
Cellular
Network
Wired
LAN
Bluetooth Piconet
(1 Mbps, 10 meters)

7. Bluetooth Application Areas
Cable replacement
Eliminates need for numerous cable attachments for connection (e.g., RS232)
Data and voice access points
Real-time voice and data transmissions
Ad hoc networking
Device with Bluetooth radio can establish connection with another when in range

8. Piconets and Scatternets
Basic unit of Bluetooth networking
Master and one to seven slave devices
Master determines channel and phase
Scatternet
Device in one piconet may exist as master or slave in another piconet
Allows many devices to share same area
Makes efficient use of bandwidth

9. Bluetooth Configurations
Master A B
Slave/Master E D C
Slave
Slave
Slave F G H
Slave
Slave
Slave
2.4 GHZ ISM band supports around 80 physical channels with 1 MHz. bandwidth
These 80 channels are managed through piconets and scatternets
All radios in a scatternet share the same frequency hopping (FHSS)

10. Bluetooth Piconets PC Slave Master PC Master Slave Piconet2 (Cubicle2)
printer
Ear
Phone
Slave
/Master
Cellular
Phone PC
Slave
Slave
Piconet1
(Cubicle 1)
printer
Slave
Slave PC
Piconet3
(Cubicle3)

11. Bluetooth versus Wi-Fi
Table 7‑2: Bluetooth versus Wi-Fi
Bluetooth versus Wi-Fi
Factor
Wi-Fi
Bluetooth
Data Rate
11 Mbps
1 Mbps
Distance Covered (range)
100 meters
10 meters
Application focus
Cable replacement
Connection to corporate networks
Ease of use
Piconets good for small networks
Complex even for 2 devices
Security
Short distance, multiple levels (link level, app level)
WEP
Power
Very low power (smaller devices such as consumer electronics)
High power

12. State Transitions in Bluetooth
Standby
Disconnected
State
Page
Inquire
Connecting
State
Active
Active State
Park,
Sniff,
Hold-
Low-Power States
Typical Scenario:
Devices initially in standby mode
Issue an inquire (I am available, does someone need me)
Devices scan the inquire list and then page the ones they want to invite
Devices go into an active transfer mode (Piconet)
If too many in a piconet, go into park-sniff-hold mode
After transfer go into standby mode

13. Bluetooth Standards Documents
Standards specifications
Details of various layers of Bluetooth protocol architecture (more than 1500 pages)
Bluetooth is a layered protocol architecture
Core protocols (5 layer) - required
Cable replacement and telephony control protocols
Adopted protocols (PPP, WAP,,) .
Profile specifications
Use of Bluetooth technology to support various applications

14. Protocol Architecture
Core protocols
Radio layer - Bluetooth transceiver operating in the 2.4 GHz
Baseband layer -Bluetooth Link Controller (LC) low- level link routines (complex).
Link Manager Protocol (LMP) is used by the Link Managers (on both side) for link
Host Controller Interface (HCI) a command interface to access to hardware status and control registers.
Logical Link Control and Adaptation Protocol (L2CAP) supports higher level protocol multiplexing
Service Discovery Protocol (SDP) applications to discover which services are provided by a Bluetooth device

15. Bluetooth Stack Legend Core vCard/vCal WAE AT- Commands TCS Bin SDP
Cable
replacement
OBEX
WAP
Telephony
control
TCP UDP IP
Adopted
PPP
Audio
RFCOMM
Logical Link Control and Adaptation Protocol ( L2CAP)
Host Controller Interface
Link Management Protocol (LMP)
Baseband
Bluetooth Radio
Shaded areas (see legend) represent different families of Bluetooth Protocols

16. Protocol Architecture (cont.)
Cable replacement protocol: provides emulation of serial ports over the L2CAP protocol (e.g., emulates EIA RS232 communications over the Bluerooth baseband layer.
Telephony control protocols: (TCS BIN) defines the signalling and control sequences needed for telephone conversations over Bluetooth.
Adopted protocols: minimize new by Bluetooth:
PPP: used to transport IP packets over point-to-point links such as dial-up lines.
TCP/UDP/IP. foundation protocols for the Internet
OBEX: The object-exchange protocol developed for the exchange of objects (similar to HTTP, vCard and vCalendar)
WAE/WAP: The Wireless Application Protocol and Wireless Application environment are included in Bluetooth.

17. Usage Models
File transfer: to transfer files over Bluetooth. protocols used can be SDP or OBEX.
Internet bridge (Dial-Up networking): to wirelessly connect a PC with a cordless modem or a cellular phone uses PPP and AT protocols
LAN access: connect a piconet device to access a LAN. uses SDP and PPP-IP protocols.
Synchronization: synchronize device-to-device PIM (personal information management) information such as calendars and phone books. The model uses OBEX and IrMC (infrared mobile communications)
Three-in-one phone: Telephone headsets and handsets can be used in this model as audio input and output devices. This model uses Audio, SDP, and AT commands.

18. Usage Models SDP SDP L2CAP L2CAP a) File Transfer
File Transfer Application
Modem Emulation or Driver Application
OBEX
AT Commands
PPP
SDP
SDP
RFCOMM
RFCOMM
L2CAP
L2CAP
a) File Transfer
b) Dial-Up Networking
LAN Access Application
Synchronization Application IP
IrMC
PPP
SDP
OBEX
SDP
RFCOMM
RFCOMM
L2CAP
L2CAP
c) LAN Access
c) LAN Access

19. Radio Specification Several classes of transmitters
2.4 GHZ ISM band that can support around 80 physical channels with 1 MHz. bandwidth
These 80 channels are managed through piconets and scatternets.
Several classes of transmitters
Class 1: Outputs 100 mW for maximum range
Power control mandatory
Provides greatest distance
Class 2: Outputs 2.4 mW at maximum
Power control optional
Class 3: Nominal output is 1 mW
Lowest power
Much less powerful than cellular phones (GSM operates at 1 to 3 Watts)

20. Baseband Specification
Very complicated
Specifies
Frequency hopping
Physical Links
Bluetooth Packet Fields
Error correction
Logical Channels
Bluetooth Audio
Bluetooth Security

21. Baseband Specification
Frequency Hopping in Bluetooth. FH occurs by jumping from one channel to another (80). (all devices on a piconet share same).
Physical Links between Master and Slave.
Synchronous connection oriented (SCO). point-to-point connection of master and slave. Mainly for voice
Asynchronous connectionless (ACL). Point-to-multipoint link between master and all slaves is also supported.
Bluetooth Packet Fields. Single slot & multiple slot
consist of three fields:
Access code – used for timing synchronization, offset compensation, paging, and inquiry
Header – used to identify packet type and carry protocol control information
Payload – contains user voice or data and payload header, if present

22. Baseband Specification (cont.)
Error Correction Schemes:. different types of error correction codes that includes ARQ.
Logical Channels and Channel Control: Bluetooth defines five types of channels for different types of payload such as Link control (LC), Link manager (LM), User asynchronous (UA), User isochronous (UI), and User synchronous (US).
Bluetooth Audio. choice of two
pulse code modulation (PCM)
continuously variable slope delta (CVSD) modulation.(variable step)
The choice is made by link manager
Bluetooth Link Security. includes Authentication, Encryption (privacy) and Key management.

23. Link Management Protocol (LMP)
LMP manages the radio links between Bluetooth masters and slaves.
LMP specifies exchange of LMP PDUs
PDUs supported by the LMP:
General response
Security Service
Authentication
Pairing: establish a key between authenticated pairs
Change link key
Change current link key
Encryption

24. L2CAP
Provides a link-layer protocol between entities with a number of services
Similar to LLC
Relies on lower layer for flow and error control
Makes use of ACL links, does not support SCO links
Provides two alternative services to upper-layer protocols
Connection service
Connection-mode service

25. Cordless Systems and Wireless Local Loop
Cordless networks
Wireless MANs (Wireless Local Loops)

26. Cordless Phone Public Switched Telephone Network (PSTN) Handset
Base Unit
Basically a cellular phone with no location services
Typical coverage is meters
User owns handset and base unit -- no initial need for standards

27. Cordless System Operating Environments
Residential – a single base station can provide in-house voice and data support
Office
A single base station can support a small office
Multiple base stations in a cellular configuration can support a larger office
Telepoint – a base station set up in a public place, such as an airport

28. Time Division Duplex (TDD)
Also known as time-compression multiplexing
Data transmitted in one direction at a time, with transmission between the two directions
Simple TDD: Bit stream is divided into equal segments, compressed in time to a higher transmission rate, and transmitted in bursts
Wireless TDD typically used with TDMA
A number of users receive forward channel signals in turn and then transmit reverse channel signals in turn, all on same carrier frequency
TDMA/TDD used more often :
Improved ability to cope with fast fading (base station can detect strongest signals and send at the same)
Improved capacity allocation (can assign more slots to forward channel for improved forward traffic)

29. TDD

30. Cordless Standards
DECT (Digital Enhanced Cordless Telecommunications) developed in Europe
PWT (Personal Wireless telecomm) developed in US
DECT is most commonly used standard (mainly
DECT Architecture (suited for voice)
Physical layer – data transmitted in TDMA-TDD frames over one of 10 RF carriers
Medium access control (MAC) layer – selects establishes/releases connections on physical channels; supports three services:
Broadcast
Connection oriented
Connectionless
Data link control layer – provides for the reliable transmission of messages using traditional data link control procedures

31. Home R/F

32. Home R/F Specification
150 feet,
10 Mbps

33. How SWAP (Shared Wireless Application Protocol) Supports Voice and Data

34. UWB -- Overview
Ultra Wideband (UWB) is emerging as a new wireless personal area network technology.
Originally developed in the 1960s for the military.
FCC approved the commercial implementation of UWB in February 2002, within limits.
UWB provides high data rates (around 50 Mbps) in very short distances (10 meters).
UWB is a radio system that uses narrow pulses (millions of pulses per second) for communication and sensing by using short-range radar.
UWB radio sends data in millions of pulses across a wide frequency band
Legal in the US as long as it uses less power than normal radio frequency leakage.

35. Wireless Sensor Networks (Overview)
WSNs typically consist of small, low-powered devices (sensors)
Sensors can be developed to measure temperature, humidity, motion, color changes in a painting, or any other measurable thing.
Most WSNs consist of millions of tiny processors communicating over slow wireless networks,
WSNs may consist of devices with a wide range of computation, communication, and sensing capabilities.
The WSNs may use Bluetooth or IEEE networks
ZigBee IEEE

36. Sensor Node (Mote)

37. WSN Hierarchy

38. WSN Design

39. WSN Protocol Stack

40. Summary WPANs Bluetooth Home Networking UWB Overview
Wireless Sensor Networks