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IBM Wireless e-business

Bluetooth and Wireless LAN Technology Primer and Mobile Products

September 2001

David Conway-Jones

Technology Consultant,IBM EMEA Pervasive Computing

email: [email protected]


•Introduction

•Positioning of PAN/LAN/WAN

•Wireless Local Area Network (WLAN) and 802.11

•Personal Area Networks (PAN) and Bluetooth

•Future Wireless Technologies

•IBM Mobile Wireless Technology


Penetration of TechnologyOpportunities for Connection

White Goods, Entertainment Systems, Toys, Cars, Infrastructure, etc - multiple per home

TV - approx 1 per home

Mobiles60% penetration in UK

PCs and Desktops

Servers

Con

nect

ed to

In

tern

et


PAN

LAN

WAN

Person Space(office, briefcase, person)

On-campus(Office, School, Airport, Hotel)

Off-campus(Open areas)

Cellular(Kilometers)

802.11b (10’s-100’s of meters)

Bluetooth(meters to 10’s of meters)

Geography Nomenclature Wireless Technology


1. Wireless Local Area Networks (WLAN)2. WLAN Components 3. IEEE 802.11 ? 4. Mixing Vendor Equipment 5. Wireless and wired LAN interoperability 6. WLAN Range 7. Access Points 8. Roaming 9. Using a WLAN to Interconnect two LANs 10. WLAN Scenarios 11. Security 12. Technology Comparisons

Augment Wired LANs

LAN Access Point

Peer-to-peercollaboration

Infrastructure

Ad hoc


Worldwide WLAN Sales ($ in Millions)


•Two or more computers connected wirelessly using standard network protocols

•The current buzzword however generally refers to wireless LANs (WLAN).

•Controlled by a standards committee (IEEE 802.11)

•WLAN solutions for:•Business •Education •Applications where network wiring is impossible

•Warehousing •Point-of-sale handheld equipment.


There are two kinds of wireless networks:

1) An ad-hoc, or peer-to-peer wireless networks •Each computer communicates directly with each other to: send files, share printers, work collaboratively•They may not be able to access wired LAN resources, unless one of the computers acts as a bridge to the wired LAN using special software.

2) Infrastructure wireless networks (access points, hardware or software)

•Access point acts like a hub, providing connectivity for the wireless computers. It can connect (or "bridge") the wireless LAN to a wired LAN, allowing wireless computer access to LAN resources, such as file servers or the Internet.


Dedicated hardware access points (HAP)

Server

Wired Network

Wireless Network

Wireless Clients

Access Point

WiredClient


Software Access Points which run on a computer equipped with a wireless network interface card as used in an ad-hoc or peer-to-peer wireless network

Wireless Client

Server

Wired Network

Wireless Network

Wireless Client

SoftwareAccess Point

WiredClient


•Wireless networking hardware requires the use of underlying technology that deals with radio frequencies as well as data transmission.

•The most widely used standard is 802.11 produced by the Institute of Electrical and Electronic Engineers (IEEE).

•This is a standard defining all aspects of Radio Frequency Wireless networking.

•802.11 was ratified in 1997 at speeds of 1- 2 Mb/s

•The 802.11b extension runs at 1, 2, 5.5 and 11 Mb/s


•802.11a is a proposed spec running in the 5GHz IBM band with speeds of 54Mb/s scheduled for 2002

•But range is less (more like 10m)

•The 802.15 Coexistence Task Group is addressing interoperability between low-power wireless devices (Bluetooth) and 802.11b. Completion is scheduled for 2001

•IBM is a member of 802.11 and 802.15


•Because most wireless networking hardware vendors support the 802.11 standard they can inter-operate.

•Verification is recommended because there are two different modulation techniques:

•Frequency Hopping Spread Spectrum (FHSS) •Direct Sequence Spread Spectrum (DSSS)•They are not interoperable.

•When purchasing wireless networking hardware from separate vendors be sure to obtain guarantees from the vendors that the hardware will inter-operate and follows the standards.


•Within a short time all new wireless cards, like Ethernet cards, will become inexpensive, ubiquitous and totally interoperable.

•The latest version of the standard (802.11b) defines 11mbps with support for the older standard of 1mbps and 2mbps speeds. This provides compatibility with different or older equipment.

•Note that this new standard covers DS-type Networks, not FH types.

•At this point mixing Access Points is not recommended, unless it has the Wi-Fi (Wireless Fidelity) logo from WECA (Wireless Ethernet Compatibility Association)


•The Access Point acts as a “Bridge” between the wireless and wired networks

•Hardware access points are available with various types of network interfaces, such as Ethernet or Token Ring

•Software access point may also be used


• Each access point has a finite range

• The distance varies depending upon the environment; indoor, outdoor, building construction.

• Operating at the limits of the range reduces performance.

• Typical indoor ranges are 20-50 meters, outdoor are 100-200 meters

• Longer ranges are possible; performance will degrade with distance.

• Using multiple Access Points will extend the range


•Inexpensive access points have a recommended limit of 10

•More expensive access points support up to 100 wireless connections.

•Using more computers than recommended will degrade performance and reliability

•Multiple access points can be connected to a wired LAN, or to a second WLAN.

•Functions vary by manufacturer


•A wireless computer can "roam" from one access point to another

•Completely transparent to the user

•Some access point configurations require security authentication when swapping access points, usually in the form of a password dialog box.

•Access points are required to have overlapping wireless areas to achieve this.


•WLAN offers a cost-effective solution to users with difficult physical installations such as:

•campuses•hospitals•businesses with more than one location in immediate proximity but separated by public thoroughfare.

•This type of installation requires two access points.•Each access point acts as a bridge or router connecting its own LAN to the wireless connection. •The wireless connection allows the two access points to communicate with each other, and therefore interconnect the two LAN's.


•Mobile users, both on and off “campus”

•Where physical wiring is difficult or impossible

•Connecting small groups to a larger work environment.

•Wireless networking in these environments is a very cost effective alternative

•Temporary wireless LANs can easily be created for exhibitions, school or business projects, all without any trailing cabling.


•Potential security issues; physical access not required.

•802.11 wireless communications cannot be received nor decoded by simple scanners or short wave receivers.

•However, eavesdropping is possible using special equipment.

•802.11 WLAN have a function called WEP (Wired Equivalent Privacy); a form of encryption.

•Access Points can control access via unique MAC addresses.

•Virtual Private Networking (VPN) techniques will work over wireless networks in the same way as traditional wired networks. This is the best approach.


WLAN Security: SSID

•Network access control can be implemented using an SSID associated with an AP or group of APs.

•The SSID provides a mechanism to "segment" a wireless network into multiple networks serviced by one or more APs. •Each AP is programmed with an SSID corresponding to a specific wireless network. •To access this network, client computers must be configured with the correct SSID.

•The SSID acts as a simple password


WLAN Security: MAC Filtering

•A client computer can be identified by the unique MAC address of its 802.11 network card.

•Each AP can be programmed with a list of MAC addresses associated with the client computers allowed to access the AP.

•If a client's MAC address is not included in this list, the client is not allowed to associate with the AP.

•MAC address filtering provides good security, but is best suited to small networks.

•Each AP must be manually programmed with a list of MAC addresses, and the list must be kept up-to-date.


WLAN Security: WEP

•WEP provides encrypted communication

•All clients and APs on a wireless network use the same key •The key resides in the client computer and in each AP

•Support for WEP is standard

•WEP specifies the use of a 64-bit encryption key

•Implementations of non-Wi-Fi 128-bit key encryption exists

•The 802.11 standard does not specify a key management protocol, so all keys on a network must be managed manually


WLAN Security: VPN

•A VPN solution for wireless access is the most suitable alternative to WEP and MAC address filtering.

•VPN solutions are already widely deployed to provide remote workers with secure access to the network via the Internet.

•In this remote user application, the VPN provides a secure, dedicated path (or "tunnel") over an "untrusted" network-in this case, the Internet.

•Various tunneling protocols are used in conjunction with standard, centralized authentication solutions,such as Remote Authentication Dial-In User Service (RADIUS) servers.


WLAN Security: VPN

•VPN technology can also be used for secure wireless access; the "untrusted" network is the wireless network.

•The APs are configured for open access with no WEP encryption, but wireless access is isolated from the enterprise network by the VPN server and a VLAN between the APs and the VPN servers.

•The APs should still be configured with SSIDs for segmentation.

•Authentication and full encryption over the wireless network is provided through the VPN servers that also act as gateways.

•Unlike the WEP key and MAC address filtering approaches, the VPN-based solution is scalable to a very large number of users.


1. What is Bluetooth?2. Characteristics?3. Usage scenarios: Today/Tomorrow?4. 802.11 vs. Bluetooth vs. IR5. Security6. IBM’s Contribution

Cell phone

Modem Access Point

Peripherals

ThinkPad

Personal Area “Connectivity”

WorkPad


Defacto standard for wireless Personal Connectivity technology

Specification for small-form factor, low-cost, short range radio links between mobile PCs, mobile phones and other portable devices.

The Bluetooth Special Interest Group (SIG) is an industry group consisting of leaders in the telecommunications and computing industries that are driving development of the technology and bringing it to market.

IBM, Toshiba, Ericsson, Nokia, Intel - Motorola, Microsoft, Lucent and 3Com - plus 2000+ other companies


Bluetooth Market Potential

W/W Bluetooth Enabled Equipment Forecast (Units in Millions)

Source : Cahners In Stat July 2000


•Operates in the 2.4 GHz Industrial-Scientific-Medical (ISM) band at a data rate of 721Kb/s

•Uses Frequency Hopping (FH) spread spectrum, which divides the frequency band into a number of channels (2.402 - 2.480 GHz yielding 79 channels). 1600 hops/sec.

•During a connection, radio transceivers hop from one channel to another in a pseudo-random fashion, determined by the Master.

•Supports up to 8 devices in a piconet (1 master and up to 7 slaves sharing a channel).

•Up to 10 piconets can combine to form scatternets (scaling).


•A collection of devices

•Connected via Bluetooth in an ad hoc fashion.

•Starts with two devices, and may grow to eight (including the master)

•Master sets the clock and hopping pattern.

•However, when establishing a piconet, one unit will act as a master and the other(s) as slave(s) for the duration of the piconet connection.

•A Scatternet is the linking of multiple co-located piconets through the sharing of common master or slave devices.


•Built-in security.

•Non line-of-sight transmission through walls and briefcases.

•Omni-directional.

•Supports both voice and data services; easy integration of Serial links and TCP/IP for networking

•Regulated by governments worldwide, even France !

•Supports both one-to-one and one-to-many networking topologies

•Devices must be in a 10 meter radius for communications to occur.


Bluetooth Protocol Stack

WAE

WAP

vCard/vCal

Obex

TCP/UDP

IP

PPP

RFComm

ServiceDiscovery

Audio

L2CAP

BaseBand

TelephonyControl

Radio

HCI

LMP

Lower Transport

Upper Transport

Middleware

Adopted


•One-to-one

•One-to-many

(generally Serial mode)

(generally TCP/IP mode)


Dial-up Networking

Synchronization

File Transfer

•Bluetooth Usage Models for Notebooks

•Dial-Up Networking via cell phone•Syncing•File Transfer

•Target Devices•Cellphone•Desktop•Handheld•Other Notebook


Dial-up Networking

Synchronization

File Transfer

•Bluetooth Usage Models for Handhelds•Dial-up Networking via Cell phone•Syncing •File Transfer (business cards)

•Target Devices•Cell phone•Desktop•Notebook•Other handheld


Synchronization

File Transfer

Bluetooth Usage Models for DesktopSyncingFile TransferLan Access fordevices

Target DevicesHandheldNotebook


Telephony

Infrastructure

Data Access Points

Headset


•A computer network that spans a relatively large geographical area.

•Typically, a WAN consists of two or more local-area networks (LANs).

•Computers connected to a WAN are often connected through PSTNs. They can also be connected through leased lines or satellites. The largest WAN in existence is the Internet.


Personal Area NetworkingAutomotive

Wake on BluetoothHuman Interface Devices

Audio/VisualWalk-up Printing

Hidden ComputingInstant Postcard

Multi-Piconet

Cordless ComputerIntercom

FAXLAN Access

HeadsetMulti-Point

Dial-Up NetworkingFile Transfer

SynchronizationPoint to Point

Ease-of-Use

Today Tomorrow The Future


Adds weight and costDecreases reliability

Standard Connectivity Today: Many Cable Connections

• Serial• Parallel• Mouse• Keyboard• Floppy• Audio• IR• USB• Video• Docking• Power


Adds weight and costDecreases reliability

Tomorrow: Fewer Cables

Bluetooth

• USB• Video• Docking• Power

Reduces weight and costIncreases reliability

Standard Connectivity Today: Many Cable Connections

• Serial• Parallel• Mouse• Keyboard• Floppy• Audio• IR• USB• Video• Docking• Power


Personal Area Networking

Spontaneous / ad-hoc networkingComputer Supported Cooperative Work (CSCW) environmentsWorkgroup collaboration

Between many different devicesPC, PDA, Printer, Mobile phone, Communicator, Digital Camera (Still & Video)Digital TV, MP3 Playeretc…

Slave-to-slave communication is through the master


•Walk up “push” of adverts and services.

•Demo uses IBM Research Blue Drekar stack available from Alphaworks.

•Contact Yook Siong Chin.


• NOT Location Based Services• eg - Where is nearest xyz ?

• Pay for vending.

• But AWARE of the user• anticipate needs

• prepare and be ready to interact

• only need to know that the user is present• or indeed no longer present

• Bluetooth device eg Phone or PDA is ideal.• Carried with user• Individual

Location Aware Services


Total effect = real ease of use

• Come into office• PC unlocks• Buddy status says user at desk• Phone calls go to desk phone

• Go to lab• Office PC locks up• Buddy status says away from desk• Lab lights turn on• Phone calls go to lab

• Go to lunch• lab lights go off• phone calls go to mobile

• Go back to office• PC unlocks• Buddy status says user at desk• Phone calls go to desk phone

• etc...

Without pressing a

single button !


•Unique MAC address for every Bluetooth device

•Bluetooth has built-in encryption and authentication

•In addition a frequency-hopping scheme with 1600 hops/sec is employed.

•All of this, together with an automatic output power adaptation to reduce the range exactly to requirement, makes the system extremely difficult to eavesdrop


Security mode 1 (non-secure). • A device does not initiate any security procedures.

• Security mode 2 (service-level enforcement security).• A device does not initiate security procedures before channel establishment at the service level. This mode allows different and flexible access policies for applications, and is used especially for running applications with different security requirements in parallel.

• Security mode 3 (link-level enforced security). •A device allows only authenticated connections.

•Bluetooth technology has three security attributes•Authorization•Authentication•Encryption.


•Authorization•Database of services which a device has authorization to use

•Authentication•The user can choose to "auto" trust devices or "manually" trust devices.•Authentication is accomplished using a challenge-response scheme using symmetric link keys.•If the devices do not share a link key, one is created through a process called "pairing" and based on a shared secret association, like a PIN code. •If a device does not have a mechanism to enter a PIN, a restricted form link key, called a unit key, is generated based on the device's address and random number.

• Encryption can only be activated after authentication. Encryption is based on a stream cipher easily implemented in hardware or software.


•IBM is one of the original 5 founding members.

•IBM authored the discovery protocol (discovery protocol is a method to explore and discovery Bluetooth devices and services within range)

•IBM contributed to the lower layer protocol that makes up the entire Bluetooth protocol stack (link level protocol)

•IBM contributed to the Bluetooth world-wide regulatory working bodies to harmonize the 2.4GHz frequency spectrum use for Bluetooth and other government agency requirements.

•IBM funds and contributes to many of the the organization’s events.

•IBM is leading the effort to standardize IEEE 802.15, which will embrace Bluetooth as a short range wireless standard.


Infrared Bluetooth HomeRF 802.11bStandard

IrDA Bluetooth Special Interest Group de-facto

None - based on HomeRF working

groupIEEE 802.11b

Primary Use Cable replacement Cable replacement Home networking Business networkingPrimary Products Notebook and Desktop

PCs, PDAs, Mobile Phones, Printers

Notebook and Desktop PCs, PDAs, Mobile

Phones, Printers

Notebook and Desktop PCs


TechnologyOptical

Frequency Hopping Spread Spectrum

(FHSS)


(FHSS)

Direct SequenceSpread Spectrum

(DSSS)Frequency 850nm 2.4GHz 2.4GHz 2.4GHzRaw Data Rate 4Mb/s 1Mb/s 1.6 Mb/s 11 Mb/sRange line of sight 3/5 meters 10 meters 50 meters 50 meters Topology

Point to PointPoint to Point

Point to Multipoint (8 devices/pico-net)

multipoint Many to Many(CSMA)

Power output Low Low High HighRoaming No No No YesVoice No Yes Yes NoSecurity

Application IntegratedLess robust -

unique network specific IDs

Robust including Wired Equivalent Privacy (WEP)

Cost per PC (projected YE 2000/YE 2001)

$180/$80 $120/$100 $180/$80

AvailabilityPart of notebook for years; With Legacy

Free, will become an option

Option in 2000Integrated by YE 2001

Option Option and integrated in 2000

Infrared Bluetooth HomeRF 802.11bStandard

IrDA Bluetooth Special Interest Group de-facto

None - based on HomeRF working

groupIEEE 802.11b

Primary Use Cable replacement Cable replacement Home networking Business networkingPrimary Products Notebook and Desktop

PCs, PDAs, Mobile Phones, Printers

Notebook and Desktop PCs, PDAs, Mobile

Phones, Printers



TechnologyOptical


(FHSS)


(FHSS)

Direct SequenceSpread Spectrum

(DSSS)Frequency 850nm 2.4GHz 2.4GHz 2.4GHzRaw Data Rate 4Mb/s 1Mb/s 1.6 Mb/s 11 Mb/sRange line of sight 3/5 meters 10 meters 50 meters 50 meters Topology

Point to PointPoint to Point

Point to Multipoint (8 devices/pico-net)

multipoint Many to Many(CSMA)

Power output Low Low High HighRoaming No No No YesVoice No Yes Yes NoSecurity

Application IntegratedLess robust -

unique network specific IDs

Robust including Wired Equivalent Privacy (WEP)

Cost per PC (projected YE 2000/YE 2001)

$180/$80 $120/$100 $180/$80

AvailabilityPart of notebook for years; With Legacy

Free, will become an option

Option in 2000Integrated by YE 2001

Option Option and integrated in 2000


For connecting devices in your

What do you want to do?

For connecting clients to your

) ) )

Campus wide

or someone else’s

“Personal Domain”...

Bluetooth is the right choice

LAN Infrastructure...

) ) )

Airport/Hotel

or a public one

802.11b WLAN is the right choice


For creating an ad hoc Peer-to-Peer Network

Either would suffice

Bluetooth: One-to-many 802.11b: Many-to-many

Consider:•Technology install base•Size of the workgroup•Extent of the CSCW effort(Computer Supported Cooperative Work)


Other Wireless Technologies

Carrier Frequency (MHz)

Maximum Bit Rate (Kbps)

Range(m)

Advantages Problems Application

Electric field 0.1-1 20 2 Capacitive coupling limits range, data transmitted by touch, international use

Signal blocked by body, grounded objects

Identification

Magnetic field 5 250 6 Signal goes through body, international use

Antenna size Picocells data messaging

RF UHF 300-500 40 30 Low cost, efficient for distance

Local regulations

Access control, telecommand

RF microwave ISM

2400 1000 10-100 International, fast Cost, power Data networking

Optical infrared (low data rate)

Light 10 10 Simple, very inexpensive, no regulations

Directional Home remote control

Optical infrared (high data rate)

Light 1000 1 Simple, inexpensive, no regulations

Directional or high power

Infrared Data Association (IrDA) for laptops

http://www.research.ibm.com/journal/sj/384/zimmerman.html


UWB – Impulse Radio

• Ultra Wide Band• Uses picosecond mono-pulses

• Creates very wide radio spectrum

• Down in noise floor (-30 to -60dB)

• Requires very accurate timebase• Normally based on PPM techniques

• But can deliver high data rates (80+ Mbs)

• At very low power (µW)

t f

≡Fourier Transform of infinitely narrow pulse = infinitely wide frequency spectrum


Example: Pulse-LINK™

Pulse~LINK, Inc.http://www.pulselink.net/

•80Mbs

•150m


UWB

• Currently used in military applications• Squirt radios

• Difficult to detect / intercept• Low power for data rate means more portable

• Pulsed Radar• Can “see through” obstacles• Difficult to detect and protect against

• Not licensed for public use• Cuts across most currently licensed bands• Backers claim no need as there will be no interference to

normal equipment• Others doubt that – they say the background noise will

increase and some frequencies may be more impacted than others as pulses are not true impulse shape


UWB

• Wide frequency range helps with transmission through obstacles• Like bodies, walls, furniture• Harder to shield against• Helps Omni-directional transmission

• No studies on health implications• Although very low power – what are the effects

of continuous impulses across wide freq range ?


Smart Dust

• Target is sub mm sized devices

• Free floating in air

• Containing sensors• Temp, acceleration,

pressure, chemical, etc

• And communications to other particles• 5 – 10 m range

• 20kbs

• 900MHz radio

• Or km range via laser

http://robotics.eecs.berkeley.edu/~pister/SmartDust/


The Challenge for Wearables

• Need to interconnect components

• & connect within PAN to other devices

• & connect outside of PAN

UWB has lots of promise – low power – data rates high enough

But no real interoperability standards between devices

Not many off the shelf components – expensive (for now)

Hign frequencies mean CMOS fab unlikely

Probably needs to support existing standards

Most likely Bluetooth

But devices may will switch to UWB or similar

Definitely needs to support existing standards

Maybe via CPU point

802.11b/a too power hungry for WAN wearable use


1) Bluetooth: PC Card and ThinkPad UltraPort2) 802.11b PC Card, ThinkPad UltraPort and Access Point3) ThinkPad and WorkPad Proven products4) Other products “available”


IBM High Rate Wireless LAN Access

Point •£127 list price - 128bit•£105 list price - 64 bit•Plugs into the ThinkPad’s CardBus slot•Provides wireless access to corporate LAN from anywhere within a 45-90m radius•Supports speeds from 2 to 11 Mbps•64 bit encryption (WEP) or 128 bit

IBM High Rate Wireless LAN PC Card

•£486 IBM Web price•Bridges to the wired corporate LAN•Allows the user to roam within coverage area•Can support multiple users


Bluetooth PC CardFor Legacy Devices

09n9812

Bluetooth UltraPortFor Optimal Performance

09n9811

•Designed to replace peripheral cables for PDAs, printers, cameras, etc.

•Designed for personal space connectivity •Connectivity range of 10 meters

•Nominal data rate of 1 Mb/s•Built-in encryption

Ann: 9/5 GA: October Ann: 1Q 2001£143 list price £127 list price


•Wireless access to Internet and corporate networks•Wireless connection to ThinkPad

•Non-directional; phone can be in your briefcase•Wirelessly update your phone’s address book from your system

•Insulates you from rapid changes in cellular networks

Ericsson Cell Phone

BluetoothModule

Ericsson Headset R520m, T39m


Nokia Bluetooth“battery” for 6210& CF 1 card

GN Netcom 9000Headset

TDK Blue5 clip for PalmV


This is NOT a product

Linux based watch / pda“Watchpad”

•Runs X-clock really well ! •Also now includes Bluetooth

•Supports Sync , DUN and Audio

•Current demos include PIM sync, and control of PC.


Shrinking Components – Disk Drives

1 GB is :2500 high resolution photos, or1000 200 page books, or18 hours high quality music.

1980 – IBM Launches 1st GB Disk Size of a Refrigerator Weighs 250 kg Costs $40,000

2000 – IBM Launches 1st GB Micro Drive Size of Coin Weighs 25 g Costs < $500


Devices that Answer Back . . . !

Standard Palm Pilot Speech Co-Processor

Speech to TextText to Speech

Technology Demonstrator

Progressing with Device Manufacturers

Now runs on standard hPaq

Replies by Showing & Speaking

Information

Ask Question


IBM Prototype wearable

Compact Head Mount Display - Olympus PC Eye-Trek (Micro display/Earphone/Microphone)

Handy Controller - IBM Tractile(TrackPoint/Click Buttons)

ThinkPad 560X Equivalent LogicIBM YASU high density PCB

Ultimate PortabilityHeadphone Stereo Size System Unit, 0.85

lbs.(380g)

IBM MicroDrive1"Disk up to 1 G Capacity

Compact Head Mount DisplaySVGA Full Color display (Developed by Olympus)

Highlights

System Unit with motherboard and battery

Not available for sale


Visual Interaction

• Vision Pad prototype:• Transparent head

mounted display• Handheld controller• Speech input

• Augmented realityconcept – sign recognition and translation


Resources

IBM Pervasive Computing• http://www.ibm.com/pvc

Bluetooth SIG• http://www.bluetooth.com

Shameless Plug for Book• Bluetooth Revealed, published by Prentice-Hall, September

2000

AU-Systems - good Bluetooth White Paper• http://www.ausys.se/servlet/PSPDownloadServlet?

iListItemId=6833

UWB – Impulse Radio• http://www.uwb.org


Documents

PPT-File (10 MB)