Handover is the process of switching among the
available services without any interruption. Vertical handover is
a technique of switching from one type of a network to another
type of network (e.g., from WiFi to WiMAX). Seamless handover
between different access technologies is a great challenge as it
needs to obey different performance of QoS and security
constraints. Service users are becoming more demanding
regarding roaming capabilities across different networking
technologies such as WiFi, WiMAX, and CDMA as they claim
service continuity with QoS requirement and good security
features. Vertical Handover Decision (VHD) algorithms need to
be designed to provide the required Quality of Service (QoS) to a
wide range of applications while allowing seamless roaming
among a number of access network technologies. This paper is
about the implementation of the VHD algorithms designed to
satisfy these requirements. A combination of 3 parameters i.e.
Data Rate, SINR and RSS are evaluated to take decision of the
best network among available.
BER PERFORMANCE ANALYSIS FOR WIMAX PHY LAYER UNDER DIFFERENT CHANNEL CONDITIONSijistjournal
This paper gives an introduction on the IEEE 802.16 standard – WIMAX or Worldwide Interoperability for
Microwave Access. The different parts give details on the architectural specifications of WiMAX networks
and also on the working principle of WiMAX networks including its services provided. It also provides brief
descriptions on its salient features of this technology and how it benefits the networking industry. A brief
outline of the basic building blocks or equipment of WiMAX architecture is also provided. This paper also
evaluates the simulation performance of IEEE 802.16 OFDM PHY layer. The Stanford University Interim
(SUI) channel model under varying parameters is selected for the wireless channel in the simulation. The
performance measurements and analysis was done in simulation developed in MATLAB.
Handover is the process of switching among the
available services without any interruption. Vertical handover is
a technique of switching from one type of a network to another
type of network (e.g., from WiFi to WiMAX). Seamless handover
between different access technologies is a great challenge as it
needs to obey different performance of QoS and security
constraints. Service users are becoming more demanding
regarding roaming capabilities across different networking
technologies such as WiFi, WiMAX, and CDMA as they claim
service continuity with QoS requirement and good security
features. Vertical Handover Decision (VHD) algorithms need to
be designed to provide the required Quality of Service (QoS) to a
wide range of applications while allowing seamless roaming
among a number of access network technologies. This paper is
about the implementation of the VHD algorithms designed to
satisfy these requirements. A combination of 3 parameters i.e.
Data Rate, SINR and RSS are evaluated to take decision of the
best network among available.
BER PERFORMANCE ANALYSIS FOR WIMAX PHY LAYER UNDER DIFFERENT CHANNEL CONDITIONSijistjournal
This paper gives an introduction on the IEEE 802.16 standard – WIMAX or Worldwide Interoperability for
Microwave Access. The different parts give details on the architectural specifications of WiMAX networks
and also on the working principle of WiMAX networks including its services provided. It also provides brief
descriptions on its salient features of this technology and how it benefits the networking industry. A brief
outline of the basic building blocks or equipment of WiMAX architecture is also provided. This paper also
evaluates the simulation performance of IEEE 802.16 OFDM PHY layer. The Stanford University Interim
(SUI) channel model under varying parameters is selected for the wireless channel in the simulation. The
performance measurements and analysis was done in simulation developed in MATLAB.
Next Generation 4G WiMAX Networks - IEEE 802.16 Standard: cscpconf
This paper gives an overview about the various PHY and MAC layer specification which define
the IEEE 802.16 standard and which define the Fixed WiMAX (Ver. 802.16d-2004) and Mobile
WiMAX (Ver. 802.16e-2005) network scenarios. We also discuss about the various updates in
the Advanced Air Interface update (802.16m – 2011), which aims at fulfilling the 4G requirements as put forward by the ITU IMT-Advanced requirements.
This paper provides a high-level comparison
between LTE and WiMAX. The focus is on two primary areas: System Architecture and Physical Layer. The System Architecture describes the different functional elements in LTE and WiMAX and attempts to map similar functionality (such as mobility, security, access-gateway). We also compare and contrast the various aspects (such as transmission modes, duplexing types) of the physical layer.
SIP-Based Mobility Management for LTE-WiMAX-WLAN Interworking Using IMS Archi...CSCJournals
In this paper, we propose an architecture framework for interworking of Long Term Evolution (LTE), Worldwide Interoperability for Microwave Access (WiMAX) and Wireless Local Area Network (WLAN) technologies. The aim is to offer users of various networks seamless high quality IP-based multimedia services access anywhere at any time. IP Multimedia Subsystem (IMS) is used in the proposed architecture for providing a platform through which telecommunications operators can merge the various networks. A Session Initiation Protocol (SIP) REFER method which provides uninterrupted service continuity is introduced. The proposed LTE-WiMAX and LTE-WLAN tight coupled interworking is compared with the UMTS- WiMAX and UMTS-WLAN tight coupled interworking. The two heterogeneous networks are simulated using OPNET Modeler 17.1. Various metrics are obtained to test the performance of the proposed technique. Results show that successful VoIP session handoffs with acceptable Quality of Services (QoS) levels can be performed. Results also show that the proposed architecture outperforms the pervious architecture.
Smart Communication System (SCS) defines the operation philosophy for the interface of new
generation power line carrier equipment PLC [1] with legacy fiber optic and radio communication
systems converging all them in a homogeneous communication network allowing packet switching
over the mesh grid using all existing point to point links even if they are TDM nature.
Modem = modulator + demodulator.
A modem is a device or program that enables a computer to transmit data over, for example, telephone or cable lines. Computer information is stored digitally, whereas information transmitted over telephone lines is transmitted in the form of analog waves.
A Novel Resource Allocation Method For Multicasting Network Using Call Admiss...IJTET Journal
Abstract— WiMAX relay networks make resource allocation decisions once per frame. An IEEE 802.16j frame consists of a downlink sub frame and an uplink sub frame. This study focuses on the downlink multicast problems. The downlink sub frame can be divided into an access zone and a relay zone. In the access zone, the BS transmits the video data to its served RSs and SSs. In the relay zone, the RSs further relay the video data to their served SSs. To determine the data transmissions within each frame, the BS should make a scheduling decision at the beginning of each frame using an appropriate resource allocation scheme. WiMAX is generally used to reduce the delays and packet loss. It a wireless standard designed to provide data transfer. In this paper mainly focuses on implementing BGWA based algorithm in order to avoid unwanted intrusion occurrences in handoff time. The Mobile Motion Prediction algorithm generally keeps track of the positions of the mobile stations and their relevant connections. The task of motion prediction is to track the motion of the mobile station in different gateways. Then different prediction methods are applied according to the sensitivity of the range to gain high precision. CAC Approach can be used to the worldwide interoperability for microwave access (WiMAX) is a promising technology for last-mile Internet access, particularly in the areas where wired infrastructures are not available. Mainly this approach is used to transmitting the video/Audio sending from base station to relay station with transmitting or secretes code.
Next Generation 4G WiMAX Networks - IEEE 802.16 Standard: cscpconf
This paper gives an overview about the various PHY and MAC layer specification which define
the IEEE 802.16 standard and which define the Fixed WiMAX (Ver. 802.16d-2004) and Mobile
WiMAX (Ver. 802.16e-2005) network scenarios. We also discuss about the various updates in
the Advanced Air Interface update (802.16m – 2011), which aims at fulfilling the 4G requirements as put forward by the ITU IMT-Advanced requirements.
This paper provides a high-level comparison
between LTE and WiMAX. The focus is on two primary areas: System Architecture and Physical Layer. The System Architecture describes the different functional elements in LTE and WiMAX and attempts to map similar functionality (such as mobility, security, access-gateway). We also compare and contrast the various aspects (such as transmission modes, duplexing types) of the physical layer.
SIP-Based Mobility Management for LTE-WiMAX-WLAN Interworking Using IMS Archi...CSCJournals
In this paper, we propose an architecture framework for interworking of Long Term Evolution (LTE), Worldwide Interoperability for Microwave Access (WiMAX) and Wireless Local Area Network (WLAN) technologies. The aim is to offer users of various networks seamless high quality IP-based multimedia services access anywhere at any time. IP Multimedia Subsystem (IMS) is used in the proposed architecture for providing a platform through which telecommunications operators can merge the various networks. A Session Initiation Protocol (SIP) REFER method which provides uninterrupted service continuity is introduced. The proposed LTE-WiMAX and LTE-WLAN tight coupled interworking is compared with the UMTS- WiMAX and UMTS-WLAN tight coupled interworking. The two heterogeneous networks are simulated using OPNET Modeler 17.1. Various metrics are obtained to test the performance of the proposed technique. Results show that successful VoIP session handoffs with acceptable Quality of Services (QoS) levels can be performed. Results also show that the proposed architecture outperforms the pervious architecture.
Smart Communication System (SCS) defines the operation philosophy for the interface of new
generation power line carrier equipment PLC [1] with legacy fiber optic and radio communication
systems converging all them in a homogeneous communication network allowing packet switching
over the mesh grid using all existing point to point links even if they are TDM nature.
Modem = modulator + demodulator.
A modem is a device or program that enables a computer to transmit data over, for example, telephone or cable lines. Computer information is stored digitally, whereas information transmitted over telephone lines is transmitted in the form of analog waves.
A Novel Resource Allocation Method For Multicasting Network Using Call Admiss...IJTET Journal
Abstract— WiMAX relay networks make resource allocation decisions once per frame. An IEEE 802.16j frame consists of a downlink sub frame and an uplink sub frame. This study focuses on the downlink multicast problems. The downlink sub frame can be divided into an access zone and a relay zone. In the access zone, the BS transmits the video data to its served RSs and SSs. In the relay zone, the RSs further relay the video data to their served SSs. To determine the data transmissions within each frame, the BS should make a scheduling decision at the beginning of each frame using an appropriate resource allocation scheme. WiMAX is generally used to reduce the delays and packet loss. It a wireless standard designed to provide data transfer. In this paper mainly focuses on implementing BGWA based algorithm in order to avoid unwanted intrusion occurrences in handoff time. The Mobile Motion Prediction algorithm generally keeps track of the positions of the mobile stations and their relevant connections. The task of motion prediction is to track the motion of the mobile station in different gateways. Then different prediction methods are applied according to the sensitivity of the range to gain high precision. CAC Approach can be used to the worldwide interoperability for microwave access (WiMAX) is a promising technology for last-mile Internet access, particularly in the areas where wired infrastructures are not available. Mainly this approach is used to transmitting the video/Audio sending from base station to relay station with transmitting or secretes code.
EMERGING BROADBAND WIRELESS TECHNOLOGIES: WIFI AND WIMAXcscpconf
Now-a-days there is high demand for broadband mobile services. Traditional high-speed
broadband solutions depend on wired technologies namely digital subscriber line (DSL). Wifi
and Wimax are useful in providing any type of connectivity such as the fixed or portable or
nomadic connectivity without the requirement of LoS (Line of Sight) of the base station. Mobile
Broadband Wireless Network (MBWN) is a flexible and economical solution for remote areas
where wired technology and also terminal mobility cannot be provided. The IEEE Wi-Fi and
Wi-Max/802.16 are the most promising technologies for broadband wireless metropolitan area networks (WMANs) and these are capable of providing high throughput even on long distances with varied QoS. These technologies ensure a wireless network that enables high speed Internet access to residential, small and medium business customers, as well as Internet access for WiFi hot spots and cellular base stations. These offer support to both point-to-multipoint (P2MP) and multipoint-to-multipoint (mesh) nodes and offers high speed data (voice, video) service to the customers. In this paper, we study the issues related to, benefits and deployment of these technologies.
The relay stations are widely used in major wireless technologies such as WiMAX (Worldwide Interoperability for Microwave Access) and LTE (Long term evolution) which provide cost effective service to the operators and end users. It is quite challenging to provide guaranteed Quality of Service (QoS) in WiMAX networks in cost effective manner.
Search Results
WiMAX (Worldwide Interoperability for Microwave Access) is a wireless industry coalition dedicated to the advancement of IEEE 802.16 standards for broadband wireless access (BWA) networks.
High frequency of low noise amplifier architecture for WiMAX application: A r...IJECEIAES
The low noise amplifier (LNA) circuit is exceptionally imperative as it promotes and initializes general execution performance and quality of the mobile communication system. LNA's design in radio frequency (R.F.) circuit requires the trade-off numerous imperative features' including gain, noise figure (N.F.), bandwidth, stability, sensitivity, power consumption, and complexity. Improvements to the LNA's overall performance should be made to fulfil the worldwide interoperability for microwave access (WiMAX) specifications' prerequisites. The development of front-end receiver, particularly the LNA, is genuinely pivotal for long-distance communications up to 50 km for a particular system with particular requirements. The LNA architecture has recently been designed to concentrate on a single transistor, cascode, or cascade constrained in gain, bandwidth, and noise figure.
THIS IS A PRESENTATION PREPARED BY ME AND MY PARTENER AS A CLASS PROJECT..DONT RATE IT VERY HIGH MYSELF COZ DID NOT SPENT MUCH TIME ON IT..BUT WIL WORK JUST FINE..DATA AVAILABLE WERE LATEST AND WE DID PUT AN EFFORT :)..
NO PDF BUT PPT FORMAT COZ DONT WANT TO TAKE CREDIT JUST HELP FELLOW STUDENTS...A THNX WUD DO....:)..IF U DONT LIKE THEN ALSO SAY..I'LL APPRECIATE IT
1. manasa066@gmail.com
BRAHMAIAH COLLEGE OF ENGINEERING
A Paper presentation on…
Wi-max
By
D.ANUSHA
R.MANASA
III B.Tech-II SEMISTER.
ROLL: 092M1A0406
BCEN Engineering College
NH-5,N.R. palem,SPSR
NELLORE (Dist.). 524366
Mobile no:+91- 9989741124
III B.Tech-II SEMISTER.
ROLL: 092M1A0424
BCEN Engineering College
NH-5,N.R. palem,SPSR
NELLORE (Dist.). 524366
Mobile no:+91-9440637769
e-mail : manasa066@gmail.com
e-mail: anushadevireddyece@gmail.com,
1
2. “WiMAX”
-
Emerging wireless technology
ABSTRACT
New and increasingly advanced data services are driving up wireless
traffic, which is being further boosted by growth in voice applications in advanced
market segments as the migration from fixed to mobile voice continues. This is already
putting pressure on some networks and may be leading to difficulties in maintaining
acceptable levels of service to subscribers.
For the past few decades the lower band width applications are growing
but the
growth of broad band
additional features in physical layer
data applications is slow. Hence we
and MAC layer and the benefits of
require technology which helps in the
each feature.
growth of the broad band data
This paper focuses on
applications. WiMAX is such a
technology which helps in point-tomultipoint broadband wireless access
with out the need of direct line of
sight connectivity with base station.
the major technical comparisons (like
QOS and coverage) between WiMAX
and
other
technologies.
It
also
explains about the ability of the
WiMAX to provide efficient service
This
paper
explains
about the WiMAX technology, its
in multipath environment.
3. broadband connectivity without the
need for Direct line-of-sight with a
base station.
III.What is wimax?
WiMAX
is
an
acronym that stands for “Worldwide
II. Introduction:
Interoperability
group number 16 of IEEE 802,
decades, low-bandwidth applications
specializing
such as downloading ring tones and
email
point-to-multipoint
known as WiMAX. There are at least
but the growth of broadband data
as
in
broadband wireless access. It also is
SMS are experiencing sharp growth,
such
Microwave
Access”. IEEE 802.16 is working
For the past couple
applications
for
four 802.16 standards: 802.16, 802.16a,
and
802.16-2004 (802.16), and 802.16e.
downloading/ uploading files with a
WiMAX
laptop computer or PDA has been
slow. The demand for broadband
conflict
access
complements it.
continues
to
escalate
with
WiFi
does
but
not
actually
WiMAX is a
worldwide and lower-bandwidth wire
wireless metropolitan area network
line methods have failed to satisfy the
(MAN) technology that will connect
need for higher bandwidth integrated
IEEE 802.11 (WiFi) hotspots to the
data and voice services. WiMAX is
Internet
radio technology that promises two-
extension to cable and DSL for last
way
several
km broadband access. IEEE 802.16
megabits per second with ranges of
provides up to 50 km of linear
several miles. It is believed that the
service
technology
DSL
connectivity without a direct line of
(Digital Subscriber Line) and cable
sight to a base station. The technology
broadband services because it offers
also provides shared data rates up to
similar speeds but is less expensive to
70 Mbit/s.
Internet
access
can
at
challenge
set up. The intention for WiMAX is to
Mobile
provide
a
wireless
area range and allows user’s
The portable version of
provide fixed, nomadic, portable and,
eventually,
and
WiMAX,
wireless
3
IEEE
802.16
utilizes
4. Orthogonal
Frequency
Division
Multiplexing
Access
(OFDM/OFDMA)
where
the
spectrum is divided into many subcarriers. Each sub-carrier then uses
QPSK or QAM for modulation.
WiMAX standard relies mainly on
spectrum in the 2 to 11 GHz range.
The WiMAX specification improves
upon many of the limitations of the
WiFi standard by providing increased
bandwidth and stronger encryption
In
reviewing
the
standard, the technical details and
For years, the wildly
features that differentiate WiMAX
successful 802.11 x or WiFi wireless
certified equipment from WiFi or
LAN technology has been used in
other
BWA applications. When the WLAN
technologies
can
best
be
illustrated by focusing on the two
technology was examined closely, it
layers addressed in the standard, the
was evident that the overall design
physical (PHY) and the media access
and feature set available was not well
control (MAC) layer design.
suited for outdoor Broadband wireless
access (BWA) applications. WiMAX
III. a) WIMAX PHY Layer:
is suited for both indoor and outdoor
BWA; hence it solves the major
The first version of the
problem.
802.16 standard released addressed
Line-of-Sight (LOS) environments at
high frequency bands operating in the
10-66
GHz
range,
whereas
the
recently adopted amendment,
the
802.16a standard, is designed for
systems operating in bands between 2
GHz and 11 GHz. The significant
difference
between
these
two
frequency bands lies in the ability to
4
5. support Non-Line -of-Sight (NLOS)
of the PHY layer features of the IEEE
operation in the lower frequencies,
802.16a standard.
something that is not possible in
higher
bands.
Consequently,
the
802.16a amendment to the standard
opened up the opportunity for major
changes
to
the
PHY
layer
specifications specifically to address
the needs of the 2-11 GHz bands. This
is achieved through the introduction
of three new PHY-layer specifications
(a new Single Carrier PHY, a 256
point FFT OFDM PHY, and a 2048
point FFT OFDMA PHY);
Some of the other
PHY layer features of 802.16a that are
instrumental in giving this technology
the
power
to
deliver
robust
performance in a broad range of
channel environments are; flexible
channel
widths,
adaptive
burst
profiles, forward error correction with
concatenated
Reed-Solomon
and
convolutional encoding, optional AAS
(advanced
antenna
systems)
improve
range/capacity,
to
DFS
(dynamic frequency selection)-which
helps in minimizing interference, and
STC (space-time coding) to enhance
performance in fading environments
through spatial diversity. Table 1
gives a high level overview of some
5
6. b) IEEE 802.16a MAC Layer:The
802.16a standard uses a slotted TDMA
protocol scheduled by the base station to
allocate capacity to subscribers in a
point-to-multipoint network topology. By
tarting with a TDMA approach with
intelligent scheduling, WiMAX systems
will be able to deliver not only high
speed data with SLAs, but latency
sensitive services such as voice and
video or database access are also
supported. The standard delivers QoS
beyond mere prioritization, a technique
that is very limited in effectiveness as
traffic load and the number of
subscriber’s increases. The MAC layer in
6
7. WiMAX certified systems has also been
designed to address the harsh physical
layer environment where interference,
fast fading and other phenomena are
prevalent in outdoor operation.
802.11 MAC was never designed for
and is incapable of supporting.
a) Coverage:
IV.WiMAX Scalability:
The BWA standard is
At the PHY layer the
designed for optimal performance in
standard supports flexible RF channel
bandwidths
and
reuse
of
all types of propagation environments,
these
including LOS, near LOS and NLOS
channels (frequency reuse) as a way to
environments, and delivers reliable
increase cell capacity as the network
robust performance even in cases
grows. The standard also specifies
where extreme link pathologies have
support for automatic transmit power
control
and
measurements
layer
tools
channel
been introduced. The robust OFDM
quality
waveform
as additional PHY
to
support
planning/deployment
and
spectrum
cell
efficient
single
STC,
(mesh
Advanced
networks)
and
antenna
diversity)
can
be
employed to improve coverage even
further. These advanced techniques
can also be used to increase spectral
CSMA/CA foundation of 802.11,
efficiency,
basically a wireless Ethernet protocol,
capacity,
reuse,
and
average and peak throughput per RF
scales about as well as does Ethernet.
channel. In addition, not all OFDM is
That is to say - poorly. Just as in an
the same. The OFDM designed for
Ethernet LAN, more users results in a
BWA has in it the ability to support
geometric reduction of throughput, so
MAC
channel.
antenna techniques (beam-forming,
In the MAC layer, the
CSMA/CA
RF
topologies
through
number of subscribers grows.
the
spectral
kilometers with up to 70 Mbps in a
sectorization and cell splitting as the
does
high
efficiency over ranges from 2 to 40
spectrum use. Operators can reallocate
supports
longer range transmissions and the
for
multi-path or reflections encountered.
WLANs. In contrast the MAC layer in
In contrast, WLANs and 802.11
the 802.16 standard has been designed
systems have at their core either a
to scale from one up to 100's of users
basic CDMA approach or use OFDM
within one RF channel, a feat the
with a much different design, and
7
8. have as a requirement low power
implementation will never be able to
consumption
deliver the QoS of a BWA, 802.16
limiting
the
range.
OFDM in the WLAN was created
systems.
with the vision of the systems
covering tens and maybe a few
V. ROLE OF ‘OFDMA’ IN
hundreds of meters versus 802.16
which is designed for higher power
MULTIPATH
and an OFDM approach that supports
ENIRONMENT:
deployments in the tens of kilometers.
b) Quality of service:
The
802.16a
MAC
relies on a Grant/Request protocol for
access to the medium and it supports
differentiated service The protocol
employs TDM data streams on the DL
(downlink) and TDMA on the UL
(uplink),
with
the
hooks
for a
Technologies
centralized scheduler to support delay-
using
sensitive services like voice and
DSSS (802.11b, CDMA) and other
video. By assuring collision-free data
wide band technologies are very
access to the channel, the 16a MAC
susceptible to multipath fading, since
improves total system throughput and
the delay time can easily exceed the
bandwidth efficiency, in comparison
symbol duration, which causes the
with
access
symbols to completely overlap (ISI).
CSMA-CA
The use of several parallel sub-
protocol used in WLANs. The 16a
carriers for OFDMA enables much
MAC also assures bounded delay on
longer symbol duration, which makes
the data. The TDM/TDMA access
the signal more robust to multipath
technique also ensures easier support
time dispersion
contention-based
techniques
like
the
for multicast and broadcast services.
a). Multipath: Frequency Selective
With a CSMA/CA approach at its
core,
WLANs
in
their
Fading
current
8
9. This type of fading
affects
certain
VI.
frequencies
Modulation and Coding (AMC):
of
a
OFDMA
with
Adaptive
transmission and can result in deep
fading at certain frequencies. One
reason this occurs is because of the
wide band nature of the signals. When
a signal is reflected off a surface,
different frequencies will reflect in
different ways. In Figure below, both
CDMA (left) and OFDMA (right)
experience selective fading near the
center of the band. With optimal
channel coding and interleaving, these
errors can be corrected. CDMA tries
to overcome this by spreading the
signal out and then equalizing the
whole signal. OFDMA is therefore
much more resilient to frequency
Both
selective fading when compared to
(HSDPA)
and
CDMA.
Quadrature
Phase
W-CDMA
OFDM
utilize
Shift
Keying
(QPSK) and Quadrature Amplitude
Modulation (QAM). It should be
noted here that for WCDMA, AMC is
only used on the downlink, since the
uplink still relies on WCDMA which
uses QPSK but not QAM. Modulation
and coding rates can be changed to
achieve higher throughput, but higher
order modulation will require better
Signal
to
illustrates
Noise
Ratio.
Figure
how
higher
order
modulations like QAM 64 are used
closer to the base station, while lower
9
10. order modulations like QPSK are used
In Figure below, you
to extend the range of the base
can see how sub-channels could be
station
results
chosen depending on the received
conducted for one of the 3GPP
signal strength. The sub-channels on
Working Groups [2], show that while
which
OFDM
the
significant fading are avoided and
maximum throughput of 9.6 Mbps
power is concentrated on channels
(16QAM), WCDMA does not exceed
with better channel conditions. The
3 Mbps. From these results, it appears
signals on the top indicate the
that even higher discrepancy may be
received signal strength, while the
found
higher
bottom part of the figure indicates
modulation and code rates to yield
which sub-carriers are then chosen for
even higher throughput for OFDM.
each signal.
.
is
Performance
able
when
to
achieve
utilizing
the
user
Adaptive Modulation and
Coding
(AMC)
With
OFDMA,
choose
sub
client
give
OFDMA
channels
based
further advantages since the flexibility
locations
with
to change the modulation for specific
eliminating the impact of deep fades.
sub-channels allows you to optimize
CDMA-based technologies utilize the
at
same frequency band regardless of
the
frequency
level.
Another
alternative would be to assign those
could
the
multipath
may
device
experiencing
a
environment
in
is
where the user is.
sub channels to a different user who
may have better channel conditions
for that particular sub-channel. This
could allow users to concentrate
transmit power on specific subchannels, resulting in improvements
to the uplink budget and providing
greater range. This technique is
known as Space Division Multiple
Access (SDMA).
10
on
the
geographical
potential
of
11. VII.ADVANCED
TECHNIQUES:
RADIO
a) Transmit and receive diversity
schemes:
Transmit and Receive
Diversity schemes are used to take
advantage of multipath and reflected
signals
that
occur
in
Adaptive
NLOS
antenna
environments. By utilizing multiple
systems (AAS) are an optional part of
antennas (transmit and/or receive),
the 802.16 standard. AAS equipped
fading, interference and path loss can
base stations can create beams that
be reduced. The OFDMA transmit
can be steered, focusing the transmit
diversity option uses space time
energy to achieve greater range as
coding.
diversity,
shown in the figure. When receiving,
techniques such as maximum ratio
they can focus in the particular
combining (MRC) take advantage of
direction of the receiver. This helps
two separate receive paths.
eliminate unwanted interference from
For
receive
other locations.
VIII. Conclusion:
Thus WiMAX systems
for portable/nomadic use will have
better
performance,
interference
rejection, multipath tolerance, high
data quality of service support (data
oriented MAC, symmetric link) and
lower future equipment costs i.e., low
chipset
complexity,
high
spectral
efficiencies. And hence WiMAX can
complement existing and emerging
3G mobile and wireline networks, and
b) Smart Antenna Technology:
play a significant role in helping
11
12. •
service provides deliver converged
service offerings
V.Poornima,
III/IV B-tech,
E.C.E,
IX. BIBLIOGRAPHY:
L.B.R.College of Engineering ,
MYLAVARAM.
Understanding “WiMAX”- Joe
E-MAIL ADDRESS:
Laslo & Michael gartenberg
v_poornima06@yahoo.co.in
www.intel.com/ebusiness/pdf/w
ireless/intel
Residential Address:
www.intel.com/netcomms/techn
P.Tabitha Priyadarshini,
ologies/wimax
D/o P.Venkata Ratnam,
P. S. Henry, “Wi-Fi: What’s
Door no- 21-171,
next?” IEEE Communications
Santhinagar, Main road,
Magazine
Tiruvuru. – 521235 (Krishna dst.)
WWW.WiMaxeed.COM.
WiMAX Handbook –Frank
PHONE: 9848783201
ohrtman
College Address:
L.B.R College of Engineering ,
L.B.R.nagar,
MYLAVAM.
AUTHORS :
•
P.Tabitha Priyadarshini,
III/IV B-tech,
E.C.E,
L.B.R. College of Engineering,
MYLAVARAM.
E-MAIL ADDRESS:
p_tabitha86@yahoo.co.in
12
(Krishna dst. A.P)