Bluetooth

• It is named after the King of Denmark that unified different factions in

Christianity through the country.
• It is a short range RF communication.
• Low cost, low power, radio based wireless link eliminates the need for short
cable.
• Bluetooth radio technology built into both the cellular telephone and the laptop
would replace the cable used today to connect a laptop to cellular phone.
• Printers, desktops can all be wireless.
• It also provides a universal bridge to existing data networks
Goals of system design
• Global operation
• No fixed infrastructure required for
network set-up or maintenance
• Voice and data connections
• Small, low power radio
• Low cost: $5-$10 per node

Features
• Fast frequency hopping to reduce interference.
• Adaptive output power to minimize interference.
• Short data packets to maximize capacity.
• Fast acks allowing for low coding overhead for links.
• Flexible packet types that support a wide application range.
• CVSD (Continuous Variable Slope Delta Modulation) voice coding that can
withstand high bit error rates.
• Transmission/reception interface tailored to minimize power consumption
Bluetooth – properties
RF band: 2.4 GHz, ISM band
– Operates at max of 740 kbps at 2.4 GHz ISM band
– Applies fast frequency hopping 1600 hops/second
– range up to 100 meters only (cable replacement tech.)
– Can have serious interference with 802.11 2.4 GHz range network
• Range:
- 10 cm up to 10 m at 1 mW transmitting power
- up to 100m at 100mW
􀂄RF band: 2.4 GHz, ISM band
􀂄Modulation: BFSK
􀂄Peak data rate: 1 Mb/s
􀂄Number of hopping channels: 79
􀂄Carrier spacing: 1 MHz
􀂄Peak Txpower: ≤20 dBm
Bluetooth Protocol Stack

A key feature of the bluetooth specification is that it aims to allow to

devices from different manufacturers to work with one another. It defines
a software stack to enable applications, to find other bluetooth devices in
the area and discover what services they can offer and use them.
The Bluetooth stack is defined as series of layers though there are some
layers that cross several layers.
The Bluetooth protocol stack can be broken into 4 types:
1: Bluetooth Core Protocols : Baseband, LMP, L2CAP and SDP
2: Cable Replacement Protocol : RFCOMM
3: Telephony Control Protocols : TCS Binary, AT-commands
4: Adopted Protocols : Everything else (excluding Audio)

Radio
The Bluetooth air interface is based on a nominal antenna power of
0dBm. Spectrum spreading is accomplished by frequency hopping
in 79 hops displaced by 1 MHz, starting at 2.402GHz and finishing
at 2.480GHz.

Power Classes

Class Power Range

1 100mW(20dBm) 100m
2 2.5mW(4 dBm) 20m
3 1mW (0 dBm) 10m
Baseband and Link Controller
The LC carries out the Baseband protocols and other low-level link
routines of the Bluetooth system. It uses the baseband to establish
network connections, define link + packet types and provide error
correction.

Link Manager
This software entity carries out link setup, authentication, link
configuration and other protocols. It discovers other remote LM’s
and communicates with them via the Link Manager Protocol
(LMP). To perform its service provider role, the LM uses the
services of the underlying Link Controller (LC).

HCI (Host Controller Interface)

It handles communications between a separate host and the
Bluetooth module. Using it Bluetooth Application can access
Bluetooth hardware without knowledge layer or other hardware
implementation details.

L2CAP (Logical Link Control and Adaptation Protocol)

It operates over an ACL link provided by the Baseband. It
multiplexes data from higher layers and converts between different
packet sizes.

RFCOMM
It is a simple transport protocol with additional provisions for
emulating the 9 circuits of RS232 serial interface ports, and it
supports upto 60 simultaneous connections between two Bluetooth
devices.

WAP (Wireless Access Protocol) and OBEX (Object Exchange Protocol)

They provide interfaces to the higher layer parts of other
Communications Protocols.
WAP is a wireless protocol that allows mobile devices to use
data service and access the Internet. It can work with a
variety of different wireless technologies, each of which
connects at the bottom of the WAP stack as a bearer.
Bluetooth simply provides another possible bearer
beneath the WAP stack.

The OBEX definition includes:

  An object model to represent data objects that gives
information about objects and provides a standard
form for transferring them.
 A session protocol for transferring the requests and
responses between devices.

SDP (Service Discovery Protocol)

It provides the means of determining what Bluetooth services are

available on a particular device. A Bluetooth device may act as an
SDP client querying services, an SDP server providing services or
both. A single Bluetooth device will have no more than one SDP
server but may act as a client to more than one remote device. SDP
provides access only to information about services but utilization of
those services must be provided via another Bluetooth or third-
party protocol. However it provides no notification to indicate that
a server or any specific service has become available or
unavailable. Its up to the client to POLL a server to detect
unavailability.

TCS (Telephony Control Protocol Specification)

It provides telephony services, which define signaling scheme for

connecting voice and data calls; to the Bluetooth devices.

AT (Audio and Telephony Control) Commands

They are modem control commands that are used in applications,

which are configured to communicate with the modem over a serial
port.

Link Types

Within Bluetooth, two types of links have been defined:

Synchronous Connection-Oriented (SCO) link

 The SCO link is a point-to-point link between a master and a
single slave in the piconet and supports time-bounded
information like voice.
 The master maintains the SCO link by using reserved slots at
regular intervals, and thus can be considered as a circuit
switched connection between the master and slave.
 Asynchronous Connection-Less Link (ACL)
 The ACL link is a point-to-multipoint link between the master
and all the slaves participating on the piconet.
 In the slots not reserved for the SCO link(s), the master can
establish an ACL link on a per-slot basis to any slave. It
therefore functions as a packet-switched connection between the
master and all active slaves participating in the piconet.
 Only a single ACL link can exist and for most ACL packets,
packet retransmission is applied.
Packet Type/Format
The data on the piconet channel is conveyed in packets.
Each packet consists of 3 entities, the access code (68/72 bits),
the header (54 bits), and the payload (0-2745 bits) as follows:

FiFi
Access Code
Access code is used for timing synchronization, offset
compensation, paging and inquiry. There are three different types
of Access code: Channel Access Code (CAC), Device Access Code
(DAC) and Inquiry Access Code (IAC). The channel access code
identifies a unique piconet while the DAC is used for paging and
its responses. IAC is used for inquiry purpose.

Header
The header contains information for packet acknowledgement,
packet numbering for out-of-order packet reordering, flow control,
slave address and error check for header.

Payload
The packet payload can contain voice field, data field or both.
It has a data field, the payload will also contain a payload header

Bluetooth States/Modes
Stand-by mode:
 Before any connections in a piconet are created, all devices are
in STANDBY mode. In this mode, an unconnected unit
periodically "listens" for messages every 1.28 seconds.
  Each time a device wakes up, it listens on a set of 32 hop
frequencies defined for that unit.
 The connection procedure is initiated by any of the devices that
then becomes master.

Page and Inquiry States:

 A connection is made by a PAGE message if the address is
already known, or by an INQUIRY message followed by a
subsequent PAGE message if the address is unknown.
 In the initial PAGE state, the master unit will send a train of 16
identical page messages on 16 different hop frequencies defined
for the device to be paged (slave unit). If no response, the
master transmits a train on the remaining 16 hop frequencies in
the wake-up sequence.
 The INQUIRY message is typically used for finding Bluetooth
devices with an unknown address, it is very similar to the page
message, but may require one additional train period to collect
all the responses.

Connection Modes
Devices synchronized to a piconet can enter power-saving modes
in which device activity is lowered. A Bluetooth device in
the Connection state can be in any of the four following modes:

Active Mode:
 In the active mode, the Bluetooth unit actively participates
on the channel. The master schedules the transmission based
on traffic demands to and from the different slaves.
 It supports regular transmissions to keep slaves
synchronized to the channel.
 Active slaves listen in the master-to-slave slots for packets
and if an active slave is not addressed, it may sleep until the
next new master transmission.
Sniff Mode:
 In the SNIFF mode, a slave device listens to the piconet at
reduced rate, thus reducing its duty cycle.
 The SNIFF interval is programmable and depends on the
application.
 It has the highest duty cycle (least power efficient) of all 3
power saving modes (sniff, hold & park).
Hold Mode:
  The master unit can put slave units into HOLD mode,
where only an internal timer is running.
 Slave units can also demand to be put into HOLD mode.
 Data transfer restarts instantly when units transition out of
HOLD mode.
 It has an intermediate duty cycle (medium power efficient)
of the 3 power saving modes (sniff, hold & park).
Park Mode:
 In the PARK mode, a device is still synchronized to
the piconet but does not participate in the traffic.
 Parked devices have given up their MAC (AM_ADDR)
address and occasional listen to the traffic of the master to
re-synchronize and check on broadcast messages.
 It has the lowest duty cycle (power efficiency) of all 3
power saving modes (sniff, hold & park).

Different states of devices in Bluetooth are shown below:

Trends in Cellular radio and

PersonalCommunications
 PCS/PCN: PCS calls for more personalized services whereas PCN refers
to Wireless Networking Concept-any person, anywhere, anytime can make a
call using PC. PCS and PCN terms are sometime used interchangeably
 IEEE 802.11: A standard for computer communications using wireless
links[inside building].
 ETSI’s 20 Mbps HIPER LAN: Standard for indoor Wireless Networks
 IMT-2000 [International Mobile Telephone-2000 Standard]: A 3G
universal,multi-function, globally compatible Digital Mobile Radio Standard
is in making
 Satellite-based Cellular Phone Systems
 A very good Chance for Developing Nations to Improve their
Communication Networks

UMTS- Universal Mobile Telecommunication System

• This is a system capable of providing variety of mobile services to wide range of
Global Mobile Communication standards.
• UMTS is being developed by RACE (R&D in advanced Communication
technologies in Europe) as 3rd the generation wireless system
• To handle mixed range of traffic , a mixed cell layout ,that would consist of
macrocells overlaid on micro and pico cells is one of architecture plan being
considered.
• The UMTS architecture will provide radio coverage with network of Base
Stations interconnected to each other and to a fixed network exchange.
• A Metropolitan Area Network (MAN) is one possible choices for network
interconnections.

UMTS is a complete system architecture –

Simple evolution from GPRS – allows one to reuse/upgrade some of the GPRS backhaul
equipment – Backward compatible handsets and signaling to support intermode and
intersystem handoffs
• Intermode; TDD to FDD, FDD to TDD
• Intersystem: UMTS to GSM or UMTS to GPRS – UMTS supports a variety of user data
rates and both packet and circuit switched services – System composed of three main
subsystems

UE (User Equipment) that interfaces with the user

• UTRAN (UMTS Terrestrial Radio Access Network) handles all radio related
functionality – WCDMA is radio interface standard here.
• CN (Core Network) is responsible for transport functions such as switching and routing
calls and data, tracking users
• UE – ME (Mobile Equipment)
• is the single or multimode terminal used for radio communication – USIM (UMTS
Subscriber Identity Module)
• is a smart card that holds the subscriber identity, subscribed services, authentication and
encryption keys
UTRAN
– Node B (equivalent to BTS in GSM/GPRS)
• performs the air interface processing (channel coding, rate adaptation, spreading,
synchronization, power control).
• Can operate a group of antennas/radios – RNC (Radio Network Controller) (equivalent
to GSM BSC)
• Responsible for radio resource management and control of the Node Bs.
• Handoff decisions, congestion control, power control, encryption, admission control,
protocol conversion, etc.
Core Networks (CN)
– 3G MSC
• Switch and database that serves the UE in its current location for Circuit Switched (CS)
services. The MSC function is used to switch the CS transactions
– 3G GMSC (Gateway MSC)
• Switch at the point where UMTS is connected to external CS networks. All incoming
and outgoing CS connections go through GMSC.
– 3G SGSN (Serving GPRS Support Node)
• Similar to that of MSC but is used for Packet Switched (PS) services. The part of the
network that is accessed via the SGSN is often referred to as the PS domain. Upgrade
version of serving GPRS support node.
– 3G GGSN (Gateway GPRS Support Node)
• Functionality is close to that of GMSC but is in the relation to PS services. Upgraded
version of gateway GPRS support Node

The Core Network (CN) and the Interface Iu are separated into two logical domains:
• Circuit Switched Domain (CSD)
– Circuit switched service including signaling
– Resource reservation at connection setup
– 3G versions of GSM components (MSC, GMSC, VLR, HLR) – IuCS
• Packet Switched Domain (PSD)
– Handles all packet data services
– 3G versions of GPRS components (SGSN, GGSN)
– IuPS
• General approach of building on GSM/GPRS infrastructure ,helps to saves $ and faster
deployment

1G: Voice Only

Remember analog phones back in the day? Cell phones began with 1G
technology in the 1980s. 1G is the first generation of wireless cellular
technology. 1G supports voice only calls.

1G is analog technology, and the phones using it had poor battery life and
voice quality, little security, and were prone to dropped calls.

The maximum speed of 1G technology is 2.4 Kbps.

2G: SMS and MMS

Cell phones received their first major upgrade when their technology went
from 1G to 2G. This leap took place in Finland in 1991 on GSM networks
and effectively took cell phones from analog to digital communications.
The 2G telephone technology introduced call and text encryption, along with
data services such as SMS, picture messages, and MMS.

Although 2G replaced 1G and is superseded by later technology versions, it's

still used around the world.

The maximum speed of 2G with General Packet Radio Service (GPRS) is 50

Kbps. The speed is 1 Mbps with Enhanced Data Rates for GSM Evolution
(EDGE).

2.5G and 2.75G: Data, Finally

Before making the major leap from 2G to 3G wireless networks, the lesser-
known 2.5G and 2.75G were interim standards that bridged the gap to make
data transmission — slow data transmission — possible.

2.5G introduced a new packet-switching technique that was more efficient

than 2G technology. This led to 2.75G, which provided a theoretical
threefold speed increase. AT&T was the first GSM network to support
2.75G with EDGE in the U.S.

2.5G and 2.75G were not defined formally as wireless standards. They
served mostly as marketing tools to promote new cell phone features to the
public.

3G: More Data, Video Calling, and Mobile Internet

The introduction of 3G networks in 1998 ushered in faster data-transmission
speeds, so you could use your cell phone in more data-demanding ways such
as for video calling and mobile internet access. The term "mobile
broadband" was first applied to 3G cellular technology.

Like 2G, 3G evolved into the much faster 3.5G and 3.75G as more features
were introduced to bring about 4G.

The maximum speed of 3G is estimated to be around 2 Mbps for non-

moving devices and 384 Kbps in moving vehicles.
4G: The Current Standard
The fourth generation of networking, which was released in 2008, is 4G. It
supports mobile web access like 3G does and also gaming services, HD
mobile TV, video conferencing, 3D TV, and other features that demand
high speeds.

The max speed of a 4G network when the device is moving is 100 Mbps.
The speed is 1 Gbps for low-mobility communication such as when the
caller is stationary or walking.

Most current cell phone models support both 4G and 3G technologies.

5G: Coming Soon

5G is a not-yet-implemented wireless technology that's intended to improve
on 4G.

5G promises significantly faster data rates, higher connection density, much

lower latency, and energy savings, among other improvements.

The anticipated theoretical speed of 5G connections is up to 20 Gbps per

second.

Difference Between 1G, 2G, 2.5G 3G, 4G Generation In

Tabular Form
Sno. Basic Terms 1G 2G 2.5G 3G 4G
1 Full Form First Second Generation Second and a Third Fourth
Generation Half Generation Generation Generation
2 Year 1980s 1990s (1991) 2001 through 2005 released in
2003 2008 working
Fully upto
2009
3 Support voice only SMS, picture WAP, MMS, digital, Voice , Video
messages, and SMS mobile supported data, Call ,Mail
MMS. games, and GPS, VOIP
search and Video INTERNET,
directory. Conferencing, Video
Video on Streaming etc
 demand.
4 Speed 2.4kbps (GPRS) in 40- (GPRS) 20 to 40 2 Mbps for 50Mps-
50kbps Kbps non-moving 100Mbps
(EDGE) in 500kbps (EDGE) 236.8 devices and 384
– 1 Mbps kbps to 384 Kbps in moving
vehicles.
5 Dropped calls Yes Yes Yes Improvements Much better.
6 Security Little Text Encryption Encryption Infrastructure end-to-end
Security, end- encryption
to-end security
7 Voice Yes Yes Yes Yes Yes
8 Video No No No Yes Yes
9 Signals Analog Digital Digital Digital Digital
10 Technologies AMPS, NMT, GSM TDMA,CDMA W-CDMA LTE , LTE
TACS UMTS, EDGE Advanced
11 Multiple FDMA TDMA, CDMA TDMA, CDMA CDMA CDMA
Address/Access
system
12 Switching type Circuit Circuit switching Circuit Packet Packet
switching for Voice and switching for switching switching
Packet switching Voice and except for Air
for Data Packet Interface
switching for
Data
13 Internet service No Internet Narrowband Narrowband Broadband Ultra
Broadband
14 Bandwidth Analog 25 MHz 25 MHz 25 MHz 100 MHz
15 Special First wireless Digital version of Upgarde version Digital Very high
Characteristic communication 1G technology of 2G broadband, speeds, All IP
technology speed
increments

Or
Introduction
In the last two decades the wired version of LAN has gained wide popularity and large-
scale deployment. The IEEE 802.3 standard has been revised and extended every few
years.

• A wireless LAN or WLAN is a wireless local area network that uses radio waves
as its carrier.
• The last link with the users is wireless, to give a network connection to all users in
a building or campus.
• The backbone network usually uses cables

Wireless LAN
With LANs (Local Area Networks), primarily based on Ethernet, becoming
popular in the late 90s, the stage was set for the development of wireless
LANs As the name implies, integration of LAN and wireless technologies
Provide flexibility and mobility in indoor environment

Wireless LAN
Typically operate in Unlicensed bands such as ISM (Industrial, Scientific,
Medical) band
U-NII (Unlicensed National Information Infrastructure) band This
unlicensed nature allows for development and deployment by multiple
operators, vendors Especially for educational and medical purposes

WLAN
WLANs can provide connectivity in hotspot areas, homes, offices etc.
Typical settings include Coffee shops, airports, transit hubs, conferences
Universities, Schools, educational institutions
Offices, government institutions, Homes, community centres
Characteristics of wireless LANs
very flexible within reception area
Ad-hoc networks do not need planning
(almost) no wiring difficulties (e.g. historic buildings, firewalls)
more robust against disasters like, e.g., earthquakes, fire
Highspeed versions with transmission rate as high as 1000 Mbps are currently available.
Until recently wireless version of LANs were not popular because of the following
reasons:
High cost: Previously the equipments cost more.
Low data rate: Initially, the data rate supported by the WLAN is too less, so it supports
only a few applications.
Occupational safety concerns
Licensing requirements
In the last couple of years the situation has changed significantly. Cheaper, smaller and
powerful notebook computers and other mobile computing equipment have proliferated
in homes and offices. These devices share various resources such as printers, files and
Broadband Internet connections. This has opened up the need for wireless LAN. Wireless
LANs also offer a number of other advantages compared to their wired counterpart.
Before going into the technical details of Wireless LAN let us first look at various
reasons which have led to the development of WLANs.

Some of the advantages are mentioned below:

Availability of low-cost portable equipments: Due to the technology enhancements,
the equipment cost that are required for WLAN set-up have reduced a lot.
Mobility: An increasing number of LAN users are becoming mobile. These mobile
users require that they are connected to the network regardless of where they are because
they want simultaneous access to the network. This makes the use of cables, or wired
LANs, impractical if not impossible. Wireless LAN can provide users mobility, which is
likely to increase productivity, user convenience and various service opportunities.
Installation speed and simplicity: Wireless LANs are very easy to install. There is no
requirement for wiring every workstation and every room. This ease of installation makes
wireless LANs inherently flexible. If a workstation must be moved, it can be done easily
and without additional wiring, cable drops or reconfiguration of thenetwork.
Installation flexibility: If a company moves to a new location, the wireless system is
much easier to move than ripping up all of the cables that a wired system would have
snaked throughout the building. This also provides portability. Wireless technology
allows network to go anywhere wire cannot reach.
Reduced cost of ownership: While the initial cost of wireless LAN can be higher than
the cost of wired LAN hardware, it is envisaged that the overall installation expenses and
life cycle costscan be significantly lower. Long-term cost-benefits are greater in dynamic
environment requiring frequent moves and changes.
Scalability: Wireless LAN can be configured in a variety of topologies to meet the
users need and can be easily scaled to cover a large area with thousands of users roaming
within it.

WLAN Advantages
Advantages
Mobility, leads to higher efficiency and productivity
Cost effective ownership and installation (Compared to hard wired
infrastructure)
Enables dynamic network reconfigurability (hardward software upgrades).

Disadvantages
• low bandwidth compared to wired networks (1-10 Mbit/s)
• many proprietary solutions, especially for higher bit-rates, standards
take their time (e.g. IEEE 802.11)
• many national restrictions for wireless, long time to establish global
solutions like, e.g., IMT-2000
Design goals for wireless LANs
• global, seamless operation
• low power for battery use
• no special permissions or licenses needed to use the LAN
• robust transmission technology
• simplified spontaneous cooperation at meetings
• easy to use for everyone, simple management
• protection of investment in wired networks
• security (no one should be able to read my data), privacy (no one
should be able to collect user profiles), safety (low radiation)
• transparency concerning applications and higher layer protocols, but
also location awareness if necessary
Application areas
• networks in exhibition halls
• hospitals
• warehouses
 • airports
• structure of networks in historic buildings
• Extension of existing wired local area networks in offices, universities
etc.
How are WLANs Different?
• They use specialized physical and data link protocols
• They integrate into existing networks through access points which
provide a bridging function
• They let you stay connected as you roam from one coverage area to
another
• They have unique security considerations
• They have specific interoperability requirements
• They require different hardware
• They offer performance that differs from wired LANs.
WLAN Equipment
WLAN Adapter
These provide an interface between the operating system and wireless radio
signals Typically PCMCIA, Card bus, PCI and USB.
Allows laptops, desktops and other devices to connect to WLAN

WLAN Equipment
Access point
Equivalent of a LAN hub
Connected with the network backbone
Communicates with WLAN adapter through radio signal
transmission from antenna

Access Point
Range approximately 20-500 metres
Supports approximately 15-250users
Multiple APs with overlapping coverage necessary for uninterrupted
connectivity
WLAN Bridges
Provide wireless connectivity between two WLAN networks
Reduces the cost of deploying wired infrastructure

Common Topologies
The wireless LAN connects to a wired LAN
• There is a need of an access point that bridges wireless LAN traffic
into the wired LAN.
• The access point (AP) can also act as a repeater for wireless nodes,
effectively doubling the maximum possible distance between nodes.

Wireless LAN Architecture:

The process of assembling the parts of computer hardware in computer networking is called as
computer architecture. Similarly if we use this architectural technique in Wireless LAN or WiFi is
called as Wireless LAN Architecture. It is a technique of designing and arrangement of different
components in Wireless local area networking device in a specific way. Special type of device
which is the combination of transmitter and receiver called d as transceiver which is an essential
part for standard Wireless LAN architecture that is known as Access points.
Components of Wireless Architecture:
Wireless LAN architecture is composed of different components which help in establishing the
local area network between different operating systems. These components are very essential for
WiFi architecture.

1. Access point
2. Clients
3. Bridge

Access Points

A special type of routing device that is used to transmit the data between wired and
wireless networking device is called as AP. It is often connected with the help of wired devices
such as Ethernet. It only transmits or transfers the data between wireless LAN and wired network
by using infra structure mode of network. One access point can only support a small group of
networks and works more efficiently. It is operated less than hundred feet. It is denoted by AP.

Clients
Any kind of device such as personal computers, Note books, or any kind of mobile devices which
are inter linked with wireless network area referred as a client of wireless LAN architecture.

Bridge
A special type of connectors which is used to establish connections between wired network
devices such as Ethernet and different wireless networks such as wireless LAN. It is called as
bridge. It acts as a point of control in wireless LAN architecture.
Two components are also some time play an important role in Wireless LAN architecture i.e.

1. Basic Service Set (BSS)

2. Extended Service Set (ESS)