21ECO101T

SHORT RANGE WIRELESS

COMMUNICATION

Dr. K. Dhivya
Dept. of ECE
dhivyak2@srmist.edu.in
• Unit-1: Wireless systems
• Unit-2: Antenna and Baseband coding basics
• Unit-3: RF transceivers
• Unit-4: Wireless standards
• Unit-5: Optical wireless technologies

1. Alan Bensky, “Short range Wireless Communications-

Fundamentals of RF system design and Applications”,
Elsevier Inc, 2004

2. Antti V. Raisanen, Arto Lehto, “Radio engineering for wireless

communication and sensor applications”, Artech House, 2003

3. Rolf Kraemer and Marcos Katz, “Short-range wireless

communications emerging technologies and applications”, Wiley
WWRF series, March 2009

4. Shlomi Arnon, John Barry, George Karagiannidis, Robert Schober, Murat

Uysal, “Advanced Optical Wireless Communication Systems” , Cambridge
University Press, 2012
 Unit-1 - Wireless Systems
 Introduction to wireless systems
 Reasons for the Spread of Wireless Applications
 Characteristics of Short-range Radio Wireless
Applications
 Elements of Wireless Communication Systems -
Transmitter
 Elements of Wireless Communication Systems -
Receiver
 Wireless Local Area Networks (WLAN),
 WIFI Network Architecture
 Bluetooth, Transceiver, Bluetooth Modes
 Zigbee Architecture, Frame Structure Applications
 Conflicts, Ultra-wideband Technology, Bit Sequence
detection, UWB Block Diagram
 Introduction to Wireless Systems
• A wireless system refers to a network or communication system that
transmits and receives data or information without the use of
physical cables or wired connections.
• It utilizes electromagnetic waves or radio frequencies to transmit
signals between devices, allowing for convenient and flexible
communication and connectivity.
• Wireless systems have become an integral part of modern
life, enabling various technologies such as mobile
phones, Wi-Fi networks, Bluetooth devices, wireless
sensors, and many other applications.
• These systems have revolutionized the way we
communicate, access information, and interact with
our environment.
 Types of Wireless
• Mobile
Communication
Cellular Phones (GSM( Global System for Mobile)/
CDMA(Code Division Multiple Access))
• Portable
IEEE 802.11b (Wi-Fi-Wireless Fidelity)
IEEE 802.15.3 (UWB-Ultra-Wideband)
• Fixed
IEEE 802.16 (Wireless Metropolitan Area
Network-WMAN)

*GSM- describe the protocols for second-generation digital

cellular networks used by mobile devices such as mobile
phones and tablets.
*CDMA-method of encoding several sources of data so they
may all be transmitted over a single RF carrier by one
transmitter, or by using a single RF carrier frequency with
multiple transmitters.
 Typical Frequencies

• FM Radio ~ 88 MHz
• TV Broadcast ~ 200 MHz
• GSM Phones ~ 900 MHz
• GPS ~ 1.2 GHz
• Bluetooth ~ 2.4 GHz
• WiFi ~ 2.4 GHz
 Why Wireless?
• Benefits
• Mobility: Ability to communicate anywhere!!
• Easier configuration, set up and lower installation cost

• Difficulties
• Communication medium: Free space
• Noisy and unpredictable channel
• Broadcast channel, more user ->less BW per user
• Higher equipment cost
• Usually regulated spectrum and limited BW
• Need backbone systems in order to function properly
 Challenges
• Efficient Hardware
• Low power transmitters, receivers
• Low power signal processing tools
• Efficient use of finite radio spectrum
• Cellular frequency reuse, medium access control (MAC)
protocols
• Integrated Services
• Voice, data, multimedia over the same network
• Service differentiation, priorities, resource sharing
• Network support for user mobility (mobile scenarios)
• Location identification, Handoffs,..
• Maintaining quality of service over unreliable links.
• Connectivity and coverage (internetworking)
• Cost efficiency
 Overview
• Short-range wireless communications typically refers to a wide
variety of technologies with communication ranges from a few
centimeters to several hundreds of meters.

• While the last three decades of the wireless industry have been
mostly dominated by cellular systems, short-range wireless
devices have gradually become a more integrated part of our
everyday lives over the last decade.

• The majority of these devices will be short-range wireless devices

that interconnect people with each other and their environments.
Reasons for spread of Wireless
Applications
1. Employment of higher and higher frequencies
in spectrum which was expensive previously
2. SSD (solid state devices) amplify at
mm(millimeter) wavelengths or 10’s of GHz
3. Efficient and compact antennas (planar
antennas) are available used in short-range
devices.
4. Development of SAW(Surface Acoustic Wave)
frequency determining components allows
generation of UHF with very simple circuits
5. Digital modulation techniques permits
multiplication of number of communication
channels
6. Progress in circuit miniaturization Hybrid IC
(integrated circuits) combining analog and digital
functions on one chip and RFIC (radio frequency
IC) responsible for compact size of cellular
handsets.
 Characteristic of Short Range Radio
•RF output  several microWatts up to 100 milliWatts
•Communication range several cm up to several 100 m
•Indoor operation
•Omnidirectional built-in antennas
•Simple construction and low price  consumer
applications
•Unlicensed operation
•Non critical bandwidth specifications
•UHF operation
•Battery operated Tx/Rx

Omnidirectional antenna which radiates equal radio power in all

directions perpendicular to an axis, with power varying with angle
to the axis,
Short range radio applications
Elements of Wireless Communication
Systems

1.Data source
2.RF
generating
section
3.RF
conduction and
radiation
4.Radio
channel
5.Receivers
6.Power
supply
Elements of Wireless Communication
Systems

1.Data source:
•Analog/ Digital
•Simple on/off info security intrusion detector, panic
button, manual remote control unit
•Change of state of data cause message frame
modulated on RF carrier

•Address field  identifies unit that is transmitting

•Data field conveys specific info (on/off form)
•Parity bit  detect false messages
•Computer accessories and WLAN send continuous
digital data over short –range link
–Data are organized protocol including sophisticated
error detection and correction technique
•Audio devices wireless microphone and headsets send
analog data to modulator.
–These data specially processed for better
pefromance over wireless channel
Elements of Wireless Communication Systems-
Data source-cont…
•FM transmission: pre-emphasis filter increases HF before Txion
–Receiver : De-emphasis filter will also reduce HF noise
–Dynamic range is increased by use of compander
–Txer: weak sounds are amplified more and strong signals are
amplified less
–Rxer: Opposite procedure reduces background noise while
retaining weak sounds to their proper relative level
•RFID: different aspect of data source
–Data not available in Txer but added to RF signal in an
intermediate receptor called Transducer ( may be active/passive)

COMPANDER
:
combination of
a COMPressor
and an
exPANDer.

–Txed RF is modified by transducer and detected by Rxer that

deciphers data added and passes to host computer
Elements of Wireless Communication Systems
2. Radio frequency (RF) generating section:
•Part of Txer consists of RF source (oscillator),
modulator, and amplifier.
•Simplest short range devices  all 3 functions
included in a single circuit of only one
transistor.
•RFID is different from other applications
modulation is carried out remotely from RF source

3. RF conduction and radiation:

•Built-in antennas transmission lines are
relatively short & simple
•Antennas of short range devices must be
small fraction of wavelength and
omnidirectional mostly
Elements of Wireless Communication Systems
4. Radio channel
•Range of the channel is short and equipment is used
indoors
•RF power is relatively low and regulated by telecom
authorities
•Devices often operated close to or attached to human
bodyaffects communication performance
•Reliable operating range difficult to predict
•Lack of knowledge of special propagation
characteristics by manufactures, sellers and users 
dominant reason for unreliability
•Short range devices often used to replace hard wiring
when similar performance is expected, limitations of radio
propagation compared to wires must be accounted for
each application
5. Receivers
•Similar blocks like Txer but operation is reversed
antenna, Txion line, RF amplifiers and oscillators
•Weak signals that are intercepted by antenna are
amplified above the circuit noise by low noise
amplifier(LNA)
•Desired signal is separated from all others and
shifted lower in frequency in downconverter more
effectively amplified to level required for demodulation
or detection.
•Demodulator conversion of data source implanted
on RF wave in Txer back to original form
•Txer power is limited by authorities, Rxer
sensitivity is not
•To improve system performance improve
sensitivity and selectivity to reduce interference
from unwanted sources must be done under
constraints of physics, cost, size and power
consumption
Elements of Wireless Communication Systems-
Rxer-cont…
•Important factor in LP system design and
controversial one type of modulation
•Simpler systems security and medical alarms
choice is between amplitude shift keying (ASK),
parallel to amplitude modulation (AM) in analog
system and frequency shift keying (FSK)
analogous to frequency modulation (FM)

•Downconverter takes a radio frequency (RF) signal and

converts it to a lower, intermediate frequency (IF) signal that
is suitable for digital processing.
•Selectivity is the ability of radio receiver to reject signals
close to desired frequency.
•Sensitivity of a radio receiver is its ability to amplify the
desired weak signal.
AM and FM

AM and FM modulation video link

https://www.youtube.com/watch?v=QEubAxBfqKU
Elements of Wireless Communication Systems-Power
supply
6. Power supply
•Short range devices, atleast one side of wireless link must be
completely untethered( unattached to any data or power source by wire or
fiber)
•When size limited, in hand-operated remote control Txers and security
detectors, battery size and energy is limited
•Need to change batteries not only highly inconvenient but also
expensive
•Low current consumption is important design aim for wireless
devices  harder to achieve for Rxer than Txers
•Many short range app.  intermittent Txer operation …
•Eg. security systems : Txers  kept in very low current sandby
status until data needs to be send.. …Rxer  doesn’t know when data
will be sent  must be alert all the time
•Techniques to reduce Rxer duty cycle doesn’t draw full current all
time
•Another way for reducing Rxer power consumption to operate in
reduced power standby mode, operation goes to normal when beginning
of signal is detected reduced sensitivity
Wireless Local Area Networks (WLAN)
 WLAN- Introduction
 One of the hottest applications of short-range
radio communication is wireless local area
networks.
 The early versions of WLAN had considerably
inferior data rates.
 However, advanced modulation techniques have
allowed wireless throughputs to approach and even
exceed those of wired networks
 The popularity of highly portable laptop and handheld
computers, along with the decrease in device prices,
have made computer networking a common occurrence
in multi-computer offices and homes.
 WLAN- cntd…
 Three prime disadvantages to wireless networks as
compared to wired:
1. Range limitation
2. Susceptibility to electro magnetic interference
3. Security

 The Home RF Working Group- uses SWAP (Shared

Wireless Access Protocol)
 Wi-Fi - Wi-Fi is the generic name for all devices based
on the IEEE specification 802.11 and its derivatives.
 Wi –Fi - Wireless Fidelity

 802.11 is the predominant industrial standard for WLAN

 Products adhering to it are acceptable for marketing all
over the world.
 802.11 covers the data link layer of lower-level software,
the physical layer hardware definitions, and the
interfaces between them.
 The connection between application software and the
wireless hardware is the MAC(medium access control).
 The basic specification defines three types of wireless
communication techniques: DSSS (direct sequence
spread spectrum), FSSS (frequency-hopping spread
spectrum) and IR (infra-red).
 The specification is built so that the upper application
software doesn’t have to know what wireless technique
is being used—the MAC interface firmware takes care of
that.
Open System Interconnection Reference Model
Wi –Fi – Network Architecture
• Three Wi-Fi network configurations are available.

• Fig. 11.1 shows two unattached basic service sets (BSS), each with
two stations (STA).

• The BSS is the basic building block of an 802.11 WLAN. A station

can make adhoc connections with other stations within its
wireless communication range but not with those in another BSS that is
outside of this range.

• In order to interconnect terminals that are not in direct range one with
the other, the distributed system shown in Fig. 11.2 is needed.
 Wi –Fi

• Here, terminals that are in range of a station designated as an AP

can communicate with other terminals not in direct range
but who are associated with the same or another AP.

• Two or more such APs communicate between themselves either by

a wireless or wired medium, and therefore data exchange
between all terminals in the network is supported.

• Important thing medium connecting the STAs with the APs, and
that, connecting the APs among themselves are totally
independent.
 Wi –Fi

• STA is an addressable destination, not necessarily at a fixed

location. STA’s may have varied characteristics and functions.

• A STA AP terminal, a mobile terminal, or it may have another

specified function.

• A network of arbitrary size and complexity can be maintained

through the architecture of the extended service set (ESS), shown
in Fig. 11.3.

• STAs have full mobility and may move from one BSS to another
while remaining in the network.
Wireless Local Area Networks (WLAN)
• Fig. 11.3 shows another element type—a portal. The portal is
a gateway between the WLAN and a wired LAN.
• It connects the medium over which the APs
communicate to the medium of the wired LAN—coaxial
cable or twisted pair lines.
• In addition to the functions Wi-Fi provides for distributing
data throughout the network, two other important
services, although optionally used, are provided.
• They are authentication and encryption.
• Authentication is the procedure used to establish the
identity of a station as a member of the set of stations
authorized to associate with another station.
• Encryption applies coding to data to prevent an
eavesdropper from intercepting it.
• 802.11 details the implementation of these services in the
MAC(Media Access Control).
• Further protection of confidentiality provided by higher
software layers in the network that are not part of 802.11.
Bluetooth Architecture

•Bluetooth is an example of a WPAN. (wireless

personal area networks (WPAN), which typically
serve a communication range of 10 m).
•It’s based on the creation of ad hoc, or temporary, on-
the-fly connections between digital devices associated
with an individual person and located in the vicinity of
around 10 m from him.
•Bluetooth devices in a network have the function of a
master or a slave, and all communication is between a
master and one or more slaves, never directly
between slaves.
•The basic Bluetooth network is called a piconet. It
has one master and one to seven slaves.
• A scatternet is an interrelated network of piconets
where any member of a piconet may also belong to an
adjacent piconet.
•Conceptually, a Bluetooth network is infinitely
expandable.
Bluetooth Architecture

•Fig. 12.2 shows a scatternet made up of three piconets.

•A node may be a slave in one piconet and a master in
another.
•A device may be a master in one piconet only.
Bluetooth Transceiver

• Three basic parts: RF, baseband, and application

software

• A Bluetooth chip set will usually include the RF and

baseband parts, with the application software
being contained in the system’s computer or
controller.
Bluetooth Transceiver

• The user data stream originates and terminates in the

application software.
• The baseband section manipulates the data and forms frames
or data bursts for transmission. It also controls the
frequency synthesizer according to the Bluetooth
frequency-hopping protocol.
• The Gaussian low-pass filter block before the modulator 
implemented digitally as part of a complex signal I/Q
modulation unit or it may be a discrete element
• Receiver may be one of several types.
• If a superheterodyne configuration is chosen, the filter at
the output of the down converter will be a bandpass type.
• A direct conversion receiver will use low pass filters in
complex I and Q outputs of the down converter.
IQ modulation
https://www.youtube.com/watch?v=zNbWTiKEl30
 Bluetooth Timing
 The Bluetooth protocol has a fixed-time slot of 625
microseconds.
 A transmission burst may occur within a duration of one,
three, or five consecutive slots on one hop channel.
 Transmissions are always between the piconet master
and a slave, or several slaves.
 Typically, a single-slot transmission burst lasts 366
microseconds, leaving 259 microseconds for changing
the frequency of the synthesizer
Bluetooth modes

• Bluetooth has three modes for achieving different

degrees of power consumption during
operation: sniff, hold, and park.
• Even in the normal active mode, some power saving
can be achieved.
1.Active mode:
• During normal operation, a slave can transmit in a
particular time slot only if it is specifically
addressed by the master in the proceeding slot.
• As soon as it sees that its address is not contained
in the header of the master’s message, it can “go
to sleep,” or enter a low-power state until it’s
time for the next master transmission.
• The master also indicates the length of its
transmission (one, three, or five slots) in its
message header, so the slave can extend its
sleep time during a multiple slot interval
 Bluetooth modes

1.Sniff mode:
• In this mode, sleep time is increased because the
slave knows in advance the time interval between
slots during which the master may address the
slave.

• If it’s not addressed during the agreed slot, it

returns to its low-power state for the same period
and then wakes up and listens again.

• When it is addressed, the slave continues

listening during subsequent master transmission
slots as long as it is addressed, or for an agreed time-
out period.
Bluetooth modes

3.Hold mode:
• The master can put a slave in the hold mode when data
transfer between them is being suspended for a
given period of time.

• The slave is then free to enter a low-power state, or

do something else, like participate in another
piconet.

• It still maintains its membership in the original

piconet, however.

• At the end of the agreed time interval, the slave

resynchronizes with the traffic on the piconet and
waits for instructions from the master.
Bluetooth modes

4. Park mode:
•Park has the greatest potential for power
conservation, but as opposed to hold and sniff, it is not a
directly addressable member of the piconet.

•While it is outside of direct calling, a slave in park

mode can continue to be synchronized with the piconet
and can rejoin it later, either on its own initiative or that of
the master, in a manner that is faster than if it had to join
the piconet from scratch.

•In addition to saving power, park mode can also be

considered a way to virtually increase the network’s
capacity from eight devices to 255, or even more.
Bluetooth modes
4. Park mode:
• When entering park mode, a slave gives up its active
piconet address and receives an 8-bit parked member
address.
• It goes into low-power mode but wakes up from time to time
to listen to the traffic and maintain synchronization.
• The master sends beacon transmissions periodically to
keep the network active. (Beacon kind of like a
lighthouse: it repeatedly transmits a constant signal that
other devices can see)
• Broadcast transmissions to all parked devices can be used
to invite any of them to rejoin the network.
• Parked units themselves can request reassociation with the
active network by way of messages sent during an access
window that occurs a set time after what is called a
“beacon instant”
• A polling technique is used to prevent collisions.
• Park mode was removed in Version 5 of the Bluetooth
specification.
Parameters that affect interference between Bluetooth
and Wi-Fi:
Parameters that affect interference between
Bluetooth and Wi-Fi

• Frequency and time overlap:

• A collision occurs when the interferer transmits at the
same time as the desired transmitter and is strong enough
to cause a bit or symbol error in the received packet.
• Packet length:
: • The longer the packet length of the Wi-Fi system, relative
to a constant packet length and hop rate of Bluetooth, the
longer the victim may be exposed to interference from one
or more collisions and the greater the probability of a packet
error.
• Bit rate:
• Higher the bit rate, the lower the receiver sensitivity
and therefore the more susceptible the victim will be to
packet error for given desired and interfering signal
strengths.
• Higher bit rates usually result in reduced packet length,
with the opposite effect.
Parameters that affect interference between
Bluetooth and Wi-Fi

• Use factor:
• More often the interferer transmits, the higher the
probability of packet error.
• When both communicating terminals of the
interferer are in the interfering vicinity of the
victim, the use factor is higher than if the
:
terminals are further apart and one of them does not
have adequate strength to interfere with the victim.
• Relative distances and powers:
• The received power depends on the power of
the transmitter and its distance.
• Generally, Wi-Fi systems use more power than
Bluetooth, typically 20 mW compared to 1 mW.
• Bluetooth Class 1 systems may transmit up to 100
mW, but their output is controlled to have only
enough power to give a required signal level at the
receiving terminal.
Parameters that affect interference between
Bluetooth and Wi-Fi

 Signal-to-interference ratio of the victim

receiver, SIR, for a specified symbol or frame error
ratio.
 Type of modulation, and whether error-
correction coding is used.
ZigBee

 High-level communication protocol

 The Name
 Zig-zagging of bees from flower to
flower
 Analogous to mesh networking

https://youtu.be/QXV_HgGO--g?si=-YOB-
22gOHflQv2B
Zigbee

• IEEE specification 802.15.4 associated with Zigbee,

but it should be seen as a separate entity.

• Low data rate WPAN which describes the physical

and data link layers that typically address remote
monitoring and control applications.

• An association of committed companies, the Zigbee

Alliance, has defined the network, security, and
application layers above the 802.15.4 physical
and medium access control (MAC) layers, and deals
with interoperability certification and testing
• Distinguishing features are:
• Low data rates—raw rates between 20 and 250 kbps
• Low power consumption—several months up to two
years on standard primary batteries
• Network topology appropriate for multisensor
monitoring and control applications
• Low complexity for low cost and ease of use
• Very high reliability and security
 Zigbee

• Applications:

• consumer electronics
• Home and building
automation
• Security systems
• Industrial controls
• PC peripherals
• Medical and Industrial
sensor applications
• Toys and games

Source: http://www.zigbee.org/imwp/idms/popups/pop_download.asp?ContentID=7092
Zigbee Architecture
Zigbee Architecture

• Similar to that of other IEEE standards, Wi-Fi and Bluetooth

• On the bottom are the physical layers, showing two
alternative options for the RF transceiver functions
of the specification.
• Both of these options are not expected to exist in a
single device, and indeed their transmission
characteristics—frequencies, data rates, modulation
system—are quite different.
• Embedded firmware and software layers above them
will be essentially the same no matter what physical layer
is applied.
• Just above the physical layers (PHY) is the MAC layer
which is responsible for management of the physical layer
and delivering data to and from the applications through
the layer above it.
• MAC layer functions channel access, keeping
track of slot times, and message delivery
acknowledgement.
Zigbee Architecture

• Functions of the network layer forming a network, managing

association with the network and disassociation from it, and
routing.

• Its functions and the application services above it are

defined by the Zigbee Alliance.

• Application software is not a part of the IEEE 802.15.4

specification.
• Zigbee Alliance prepares profiles, or programming
guidelines and requirements for various functional classes
in order to assure product interoperability and vendor
independence.
 These profiles define network formation, security, and
application requirements while keeping in mind the basic
Zigbee features of low power and high reliability.
 Zigbee Frame structure

• Purpose of the preamble permit acquisition of chip and symbol

timing.

• PHY header, PHR, which is signaled by a delimiter byte SFD

(Start-of-frame deliminator), notifies the baseband software in
the receiver of the length of the subsequent data.

• PSDU (PHY service data unit) is the message that has been
passed down through the higher protocol layers.
• Can have a maximum of 127 bytes although monitoring and
control applications will typically be much shorter.
Each of the new coded bits is called a chip. The
complete group of chips representing a data bit is called
a symbol
Zigbee Frame structure

• In order to avoid two or more stations trying to

transmit at the same time, a carrier sense
multiple access with collision avoidance
(CSMA-CA) routine is employed, similar to that
used in Wi-Fi, IEEE 802.11.
• The 802.15.4 receiver monitors the channel and if it
is idle it may initiate a transmission. If the channel is
occupied, the terminal must wait a random back
off period before it can again attempt access.
• Acknowledgement messages are sent without
using the collision avoidance mechanism.
 Zigbee Applications
• Promoters of Zigbee aim to cover a very large market for those
applications that require relatively low data rates.
• Open specification and a recognized certification of conformity
are an advantage in many situations.
Eg. home burglar alarm system
• Use of devices approved according to a recognized standard gives
the consumer some security against obsolescence.
• Although Zigbee claims to be appropriate for most control
applications, its declared maximum range of some 50–75m will
fall short of the requirements of many systems.
• Under the constraint of low power output for low power
consumption, greater range means reduced bandwidth and
reduced data rate.
• In fact, a great many of the applications envisaged by Zigbee can
get by very well with data rates of hundreds or a few thousand
bits per second, and by matching receiver bandwidth to these
rates for maximum sensitivity, ranges of hundreds of meters can
be achieved.
 Zigbee Applications and conflicts

• One partial answer to the range question is the deployment of

the Zigbee network in a cluster-tree configuration.
• Adjacent nodes serve as repeaters so that large areas can be
covered, as long as the greatest distance between any two
directly communicating nodes does not exceed IEEE 802.15.4
basic range capability.
• For Eg, in a multi-floor building, sensors on the top floor can
send alarms to the control box in the basement by passing
messages through sensors located on every floor and operating
as relay stations.
• There is competition between Bluetooth and Zigbee for use
in certain applications, but the overall extent of deployment
and the reliability of wireless control systems are higher
because of it.
• The proportion of wireless security and automation systems
has increased because adherence to the 802.15.4 standard
provides high reliability, security, and reduced
Ultra-wideband Technology

•Ultra-wideband Technology:
•Ultra-wideband (UWB) technology is based on transmission of
very narrow electromagnetic pulses at a low repetition rate.

•Creates a radio spectrum that is spread over a very wide

bandwidth—much wider than the bandwidth used in the
spread-spectrum systems.

• UWB transmissions are virtually undetectable by ordinary

radio receivers and therefore can exist concurrently with
existing wireless communications without demanding
additional spectrum or exclusive frequency bands.

https://youtu.be/pE-WbKLMElI?si=7xsJpiM1_hoWKySN
Advantages of UWB technology:

• Very low spectral density—Very low probability of

interference with other radio signals over its wide
bandwidth
• High immunity to interference from other radio systems
• Low probability of interception/detection by other
than the desired communication link terminals
• High multipath immunity
• Many high data rate ultra-wideband channels can
operate concurrently
• Fine range-resolution capability
• Relatively simple, low-cost construction, based on nearly
all digital architectures.
Ultra-wideband Technology
• Transmission and reception methods are unique
• UWB “carrier” is a Gaussian monopulse

Applications
• Air tags  get accurate
location
• Smart car access
• Wearable health sensors
• Wireless printers to
contactless payments
Ultra-wideband Technology- Bit Sequence detection

• A “1” monopulse is represented by a negative line

followed by a positive line, and a “0” monopulse by
the inverse—a positive line and a negative line.
• The synchronized sequence generated in the receiver
is drawn on the second line and below it the result of the
correlation operation
• ∫f(t)g(t)dt
• where f(t) is the received signal and g(t) is the
locally generated sequence.
• By sampling this output at the end of each bit period and
then resetting the correlator, the transmitted sequence
is reconstructed in the receiver.
• This is shown as the “Logic Output” which is delayed by
one symbol period.
Ultra-wideband Technology- Bit Sequence detection

• Individual bit can be represented by more than one

sequential monopulse.
• Doing so increases the processing gain by the
number of monopulses per bit.
Ultra-wideband block diagram
 Ultra-wideband block diagram

• The pulse generator block creates short impulse or step

functions with rise times on the order of tens or at the
most hundreds of picoseconds which are conditioned in the
shaping network to produce the required output spectrum.
• High speed integrated circuits or special circuit elements
such as tunnel diodes or step recovery diodes, can be
employed in the pulse generator.
• The receiver produces a replica of the known transmitted
pulse sequence which is synchronized with the incoming pulse
stream in the acquisition and tracking block.
• The baseband mixer (multiplier), integrator and sample
and hold blocks perform the correlation function and data
are output
Comparison between various short range wireless
technologies