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WiMAX and it's Simulation Books

2010-03-26T03:42:00.000-07:00

WiMAX Simulation Books

WiMAX Books: W-CDMA, Wireless Communication, Mobile WiMAX, GSM GPRS EDGE Performance, Cognitive Radio Technology, and WiMAX Operator's Manual.

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WiMAX Handover

2010-03-25T12:15:00.000-07:00

The WiMAX architecture extends the 802.16 standard and that also includes the mech-
anisms for handovers. While the 802.16 standard provides support for handover between
base stations WiMAX oﬀer protocols for handover higher up in the network structure.
The WiMAX architecture shall support mechanisms such as intra/inter ASN handover,
roaming between NSPs, seamless handover at vehicular speed and micro/macro mobility.
This section will study the architecture and its handover procedures more thoroughly
with the focus on intra/inter ASN handovers.

Access Service Network
Inside an ASN network entity there are at least one ASN Gateway (ASN GW) and a
base station. The BS handles the connection to the MS while the ASN GW takes care
of the contact with the CSN. An ASN GW can be associated with one or more BSs and
a BS can have relations to one or more ASN GWs. This segmentation
of the ASN enables multi vendor systems where diﬀerent vendors can produce diﬀerent
parts of the ASN and they still function together.
Depending on which role a BS or ASN GW take on in a handover they get diﬀerent
names. The BS in charge of the MS before the handover
is called the serving BS and the ASN GW the serving BS forwards the data to is the
serving ASN GW. The BS and ASN GW associated with the MS after the handover are
the target BS and target ASN GW respectively. The term anchoring ASN GW is used
when an ASN GW relays MS data to the serving ASN GW.

Anchoring
The anchoring ASN GW is the network’s or CSN’s attachment to the MS. Incoming
data will be sent to the anchoring ASN GW and the CSN does not need to know at
which ASN GW the MS’s current BS is located. The forwarding of data to the serving
ASN GW is performed by the anchoring ASN GW. This makes the mobility of the MS
transparent to the CSN and the need to change IP-address becomes less frequent. In
the case where the serving ASN GW is receiving the data directly from the network the
serving ASN GW is also the anchor. The anchoring ASN GW does not need to be any
of the serving or target ASN GWs.

ASN Reference Points
To identify the diﬀerent interfaces used to communicate within an ASN, with the MS and
the rest of the network a number of reference points are introduced [19], see ﬁgure 5.1
on the facing page. These reference points deﬁne the set of protocols and procedures
needed in the communication. Most of the reference points are logical mappings but
when, as in the case of R1, the functional entities are in diﬀerent physical devices the
reference point refers to a physical interface.
R1 and R3 are the reference points used in communication with entities outside of
the ASN while R6 and R8 are used inside an ASN. The R4 interface is used both inside
and outside of the ASN since it is the logical link between ASN GWs regardless of
whether they are within the same ASN or in diﬀerent ASNs. R1 is the physical interface
between the MS and the serving BS and R3 is the logical link between ASN GW and
CSN. The communication among BSs is handled through R8 while the BS-ASN GW
interaction goes via R6.

Inter ASN Handover
An inter ASN handover is a handover between BSs not part of the same ASN, see
ﬁgure 5.4 on the next page. During an inter ASN handover ASN GWs in separate ASNs
need to coordinate their actions to make the handover smooth to the MS. There are two
possible ways of dealing with the data ﬂow during an inter ASN handover, anchoring
and re-anchoring. The purpose of anchoring is to avoid an path update and hence a
redirection of the data path, where in the re-anchoring case an update will be performed.
The decision to anchor or re-anchor the data path is made by the target or an-
chor ASN GW and there are three diﬀerent decision procedures with two possible out-
comes 5.3.4. Either both parties can decide that a re-anchoring is not needed or one
of the ASN GW decides that it wants a re-anchoring. If the target ASN GW wants a
re-anchoring the anchor ASN GW will follow that decision and vice versa. It is always
the target ASN GW who will make its decision ﬁrst. What this decision is based upon is
implementation dependent and not included in the scope of the WiMAX documen.

WiMax Technology and its Implications

2010-03-25T12:06:00.000-07:00

Introduction
WiMax technology (Worldwide Interoperability for Microwave Access) allows the
opportunity for instantaneous network connections across large geographic regions without
wires. This technology developed as a natural progression from LAN (Local Area Networks)
and WIFI (Wireless Fidelity) communication systems. This technology is similar in that the
wireless connection operates on a comparable frequency with much faster connection
speeds. Currently, Intel is the only significant developer of this service. The Institute of
Electrical and Electronic Engineers, (IEEE) designates this service as 802.16.

How WiMax works
WiMax operates on the same principal as a cellular phone infrastructure. Creating a
WiMax link is achieved by connecting a tower directly to a main frame of the internet and
delivering the signal in one of two methods. The first type of service is similar to WIFI in
that it uses a lower frequency to link directly to a consumer’s computer. This type of
transmission has a smaller radius of five miles from the transmission center without wire
connections. An advantage of this type of WiMax is there is not line-of-site requirement, the
closer the consumer to the tower the better the feed.
The second type of WiMax is line-of-site. This type provides a thirty mile radius of
coverage, six times that of a non line-of-site. The disadvantage of this type of service is the
consumer is required to place the receiver in a high elevation so that a line-of-sight
connection can be established. However there are advantages to this type of connection. A
stronger link is established through higher frequencies with less interference and greater
bandwidth.
Once a WiMax link is established, the consumer can access information with great
efficiency. For example, WIFI currently runs at 54 Megabits per second under optimal
conditions. In contrast, WiMax runs at 70 Megabits per second on average. WiMax allows
more consumers to access larger amounts information at faster speeds than WIFI at high
volume peaks.

Domestic and Global applications of WiMax
WiMax allows rural areas more options in speed high connectivity. The fiber optic
infrastructure required for DSL (Digital Subscriber Line) or a broadband connection is no
longer needed. The cost incentive is greater for a provider to place a tower rather than build
the necessary network to connect the rural consumer.
Voice over Internet Protocol, (VoIP) is a design benefit of WiMax. The innovators
had this in mind when they created the larger bandwidth. Consumers could use VoIP
without impacting the speed or efficiency of the rest of the system. This has the greatest
impact for rural communities offering a choice for the consumer communication needs.
The movie industry has also adopted the WiMax system. In Park City, Utah, the
premier of the film Rize, was the first feature film to be delivered by WiMax. This has far
reaching cost saving implications for the movie industry in preventing piracy and cutting
production cost. The film industry spends approximately 1.5 billion dollars in producing,
distributing, and destroying 35mm film. WiMax could lower overall distribution costs saving
capital for movie studios. This would allow smaller, independent studios the chance to
distribute their movies with less financial burden.
Another unique advantage of WiMax allows communication systems to remain
operational during times of natural disasters and terrorist attacks. Traditional communication
systems rely on physical connections that are venerable to the elements. WiMax’s system
eliminates the need for a physical infrastructure. A tower can be easily erected in the event of
need.
Globally, WiMax can be beneficial to developing countries in which new
construction is costly and time prohibitive. Establishing a network of WiMax towers is
relatively inexpensive in comparison to traditional fiber optic infrastructures. A great benefit
of this system allows a transmitter to be placed on existing cellular towers, decreasing the
need for new construction.
Developing third world countries can use this technology as a means of establishing
connections quickly with less initial cost. The duality of the system allowing both voice and
data connection would be greatly beneficial in helping the people of these regions.

Future Implications
The future generation of WiMax technology is GAN (Global Area Network) IEEE-
802.20. This iteration allows the mobility to move within the tower radius coverage area into
the adjoining area without loss of connection. This would provide seamless, uninterrupted
connectivity from coast to coast.

Summary
WiMax offers the consumer a choice in data and voice service offering greater
connectivity with fewer infrastructures. The far reaching implications of this service allow
the consumer a choice in their communication needs while eliminating the need for wires.
This will be greatly beneficial building networks faster and with less expense.

2009-11-21T00:12:00.000-08:00

Recently we featured WiMAX deployment in Philipines by Globe Telecom & Huawei. Later on people in Dhaka Bangladesh will discover WiMAX soon.

BanglaLion Communication LTD, BRAC BD Mail Network Ltd and Augere Wireless Broadband Bangladesh Ltd — won the licences from Bangladesh Telecommunication Regulatory Commission (BTRC) to operate Broadband Wireless Access (BWA) services nationwide using WiMAX technology in 18 November 2008.

The license was obtained through an open bid process at a cost of about 31 million USD. BanglaLion was the highest bidder in obtaining the access frequency in 2.5 GHz band. The license allows using WiMAX standard 802.16e and onward revisions only. It allows VoIP services as well.

BanglaLion said it would be ready to launch WiMAX services in Dhaka by June. Apparently they will be the first company to provide WiMAX service in Bangladesh.

WiMAX in OFDM Physical layer

2009-11-05T10:35:00.000-08:00

1 Objectives:

The goal of this thesis is to implement and simulate the OFDM Physical layer specification of IEEE 802.16e-2005. Using Adaptive Modulation Techniques we analyze the performance of OFDM physical layer in mobile WiMAX based on the simulation results of Bit-Error-Rate (BER), Signal-to-Noise Ratio (SNR) and Probability of Error (Pe). The performance analysis of OFDMA-PHY is done in MATLAB 7.4 under reference channel model with channel equalizer.

2 Motivation

Some decades ago, we were purely dependent on analog system. Both the sources and transmission system were on analog format but the advancement of technology made it possible to transmit data in digital form. Along with those, the computer was getting faster to the fastest, the data payload capacity and transmission rate increased from kilobit to megabit and megabit to gigabit. From wire to wireless concept emerged and after researching and investing so much money, engineers became successful to invent wireless transmitter to transmit data. Applications like voice, Internet access, instant messaging, SMS, paging, file transferring, video conferencing, gaming and entertainment etc became a part of life. Cellular phone systems, WLAN, wide-area wireless data systems, ad-hoc wireless networks and satellite systems etc are wireless communication. All emerged based on wireless technology to provide higher throughput, immense mobility, longer range, robust backbone to thereat. The vision extended a bit more by the engineers to provide smooth transmission of multimedia anywhere on the globe through variety of applications and devices leading a new concept of wireless communication which is cheap and flexible to implement even in odd environment. This is a fact that, Wireless Broadband Access (WBA) via DSL, T1-line or cable infrastructure is not available especially in rural areas. The DSL can covers only up to near about 18,000 feet (3 miles), this means that many urban, suburban, and rural areas may not served. The Wi-Fi standard broadband connection may solve this problem a bit but not possible in everywhere due to coverage limitations. But the Metropolitan-Area Wireless standard which is called WiMAX can solve these limitations. The wireless broadband connection is much easier to deploy, have long range of coverage, easier to access and more flexible. This connectivity is really important for developing countries and IEEE 802.16 family helps to solve the last mile connectivity problems with BWA connectivity.
Simulation Results Analysis

During our simulation we used cyclic prefix to minimize the Inter Symbol Interference (ISI) on the basis of following adaptive modulation techniques through Matlab.

Binary Phase Shift Keying (BPSK)
Quadrature Phase Shift Keying (QPSK)
16-Quadrature Amplitude Modulation (16-QAM)
64-Quadrature Amplitude Modulation (64-QAM) With the help of above modulation techniques we got the following parameters,
Scattering Points of QPSK
Scattering Points of QAM
Bit Error Rate (BER)
Signal to Noise Ratio (SNR)
Probability of Error (Pe) This is the simulation environment which we used in our simulation,
Microsoft Windows XP Professional.
Matlab 7.4.0.287 (R2007a)
Microsoft Office 2007
Mersenne Twister – Random Number Generator ( RNG ) Algorithm
We used Cyclic Prefix to minimize the Inter Symbol Interference (ISI).
Performance of WiMAX has been done on the basis of BER Vs SNR in all plotting.
We have used AWGN and Rayleigh fading.

Scatter Plots of QPSK

In this subsection, we investigated the constellation of QPSK, 16-QAM and 64-QAM by using ZERO force and MMSE equalizer when FFT size is 256 and 512. After passing through AWGN channels, we got the figure 1.

Fig 1: QPSK constellation using ZERO force equalizer for FFT size 256

Bangladesh Telecommunication Regulatory Commission

2009-11-05T10:12:00.000-08:00

Invitation of proposals/offers for grant of license for Broadband Wireless Access (BWA) Services:

The Bangladesh Telecommunication Regulatory Commission (the Commission) invites proposals/offers from eligible Bangladeshi entities or joint venture companies with foreign/Bangladeshi partners (proprietorships, partnerships and companies registered under ‘Joint Stock of Companies and Firms’ under the Companies Act 1994) for grant of license to establish, maintain and operate Broadband Wireless Access (BWA) Services. Only entities having adequate financial, technical and organizational capability to serve in the field should apply with an updated list of their business record and record of experience.
The Applicant(s) companies/proprietorships for the Broadband Wireless Access (BWA) Services should be registered with Registrar, Joint Stock of Companies and Firms, as well as with the concerned chamber of commerce and industries and hold an up to date Certificate of Income Tax and/or TIN/BIN certificate. Copies of the certification of registration should be submitted with the proposal/offer.
In case of foreign companies (applying with Bangladeshi partners), the Certificate of Registration of the said foreign Company from Joint Stock of Companies or Firms or equivalent authority of its Country of Origin should be provided with the proposal/offer.
The prescribed application form along with general terms and conditions are included in the “Regulatory and Licensing Guidelines” which can be obtained from the Bangladesh Telecommunication Regulatory Commission (the Commission), Shetu Bhaban, Banani, Dhaka-1212 during working days and hours on payment of nonrefundable Tk. 50,000.00 (Taka fifty thousand) only for each copy in the form of bank draft/pay order in favour of the Bangladesh Telecommunication Regulatory Commission by making an application to the Commission in its letterhead.
All applications duly sealed are to be submitted in the tender box kept in the BTRC, Shetu Bhaban, Banani, Dhaka-1212 addressing the Chairman, Bangladesh Telecommunication Regulatory Commission on or before 12.00 hrs on 11th September, 2008. The sealed application(s) will be opened by the representatives of the Commission at 12.30 hrs in the office of the Commission on the same day in presence of the Applicant(s) who are present. Applications will not be received after the deadline i.e.12.00 hrs on 11th September, 2008.
The Commission will issue 3 (three) Licenses for Broadband Wireless Access Services as per Regulatory and Licensing Guidelines for Broadband Wireless Access Services License.
Regulatory and Licensing Guidelines containing among other things, the Guidelines for invitation of application for issuing of license for Broadband Wireless Access Services is also available in the Commission website: www.btrc.gov.bd for information only.
Any Applicant may communicate for clarification on the subject in writing along with soft copy to the Director, Legal and Licensing Division, Bangladesh Telecommunication Regulatory Commission, by 17:00 hrs of 16th August, 2008. There will be a pre-offer/pre-bid meeting for any clarification or explanation on the matter on 20th August, 2008 at a time and place to be notified later. Those who are interested to attend the pre-offer/ pre-bid meeting shall register with Director, Legal and Licensing Division, Bangladesh Telecommunication Regulatory Commission on or before 17:00 hrs 16th August, 2008.
Any proposal/offer submitted which does not comply with any of the above terms and conditions will not be accepted.
The Commission reserves the right to accept or reject any or all proposals/ offers, without assigning any reason thereof.

Director
Legal and Licensing Division
BTRC

WiMAX Quality of Services (QoS)

2009-11-05T09:55:00.000-08:00

The IEEE 802.16 standard supports up to five QoS classes. The level of
quality of service differentiation is per service flow. Each of the service flow
is having one of the scheduling types; best effort (BE), non-real time polling
service (nrtPS), real-time polling service (rt-PS), extended real-time polling
service (ert-PS) or unsolicited grant service (UGS).
WiMAX provides the five QoS classes through an architecture that is able to
process requests, perform access control and allocate the required radio
resources that are able to meet the requests that are accepted. The five QoS
classes are described as follows.

UGS: this is designed to support real-time data streams that consist of fixed sized packets issued at periodic intervals, such as back haul and voice over IP (VoIP) without silence suppression.

Ert-PS: this is designed for the extended real-time services of variable rates such as VoIP with silence suppression, interactive gaming, and video telephony.

Rt-PS: this is designed to support real-time data streams of variable rates that are issued at periodic intervals, such as MPEG video, audio and video streaming, and interactive gaming.

Nrt-PS: this is designed to support delay-tolerant data streams consisting of variable-sized data packets such as file transfer protocol (FTP), browsing, video download, and video on demand.

BE: this is designed to support data streams for which there is no minimum service requirements, and no guarantee of timely delivery of packets such as E-mail and Internet browsing.

WiMAX differentiates the service flows at the IP layer through the DiffServ
code points (DSCP). DSCP is a field in the header of IP packets used for
classifying packets entering the network in order to provide QoS guarantees.
From an IP transport perspective, the WiMAX network is divided into
multiple DSCP domains. One domain is between the base station and the
ASN gateway (ASN-GW) in every ASN termed as ASN DiffServ domain.
The second domain, CSN DiffServ domain, is between the ASN-GWs and
the HAs. The third domain is between the HAs and Internet or operator
service network.

WiMax over other technology

2009-11-03T09:27:00.000-08:00

Over the last few years many types of broadband access technologies such as DSL (Digital subscriber loop) technology, HFC (Hybrid fiber coaxial) network, FBWAN (Fixed broadband wireless access network) have been implemented.
DSL is based on the wired technology, it is quite impossible to provide service to many locations such as rural areas, home users. Besides, an xDSL local loop provides services over long distance decreasing data rate that is a great problem for communication. Moreover, The DSL uses amplifiers, repeaters which are costly and risky and hard to maintain.
Some service providers are using WLL (Wireless Local Loop) for providing services in remote areas. WLL provides bandwidth from 35kbps to 70kbps for voice and data, which is inadequate for broadband services.
WiMAX has the following advantages over other technologies.
• Flexible Architecture: WiMax supports several system architectures, including Point- to-Point, Point-to-Multipoint, and ubiquitous coverage
• High Security: WiMax supports AES (Advanced Encryption Standard) and 3DES (Triple DES, where DES is the Data Encryption Standard). By encrypting the links between the BS and the SS, WiMax provides subscribers with privacy and security across the broadband wireless interface. Security also provides operators with strong protection against theft of service.
• Quick Deployment: Compared with the deployment of wired solutions, WiMax requires little or no external plant construction.
• Interoperability: WiMax makes it easier for end-users to transport and use their SS at different locations, or with different service providers. Interoperability protects the early Investment of an operator since it can select equipment from different equipment vendors.
• Portability: WiMax SS is powered up, it identifies itself, determines the characteristics of the link with the BS, as long as the SS is registered in the system database, and then negotiates its transmission characteristics accordingly.
• Mobility: The IEEE 802.16e amendment has added key features in support of mobility. Improvements have been made to the OFDM and OFDMA physical layers to support devices and services in a mobile environment. These improvements, which include Scaleable OFDMA, MIMO, and support for idle/sleep mode and hand-off, will allow full mobility at speeds up to 160 km/hr.
• Cost-effective: WiMax will drive costs down dramatically, and the resultant competitive pricing will provide considerable cost savings for service providers and end-users.
• Wider Coverage: WiMax dynamically supports multiple modulation levels, Including BPSK, QPSK, 16-QAM, and 64-QAM. WiMax systems are able to cover a large geographic area when the path between the BS and the SS is unobstructed.
• High Capacity: WiMax uses higher modulation (64-QAM) and channel bandwidth of currently 7 MHz. WiMax systems can provide significant bandwidth to end-users [27-29]

WiMAX Applications

2009-11-02T09:52:00.000-08:00

WiMAX attribute opens the technology to a wide variety of applications because of its high transmission rate and large range. It serves as a backbone for Wi-Fi for connectivity to the Internet. It can provide broadband connec-tivity over large coverage area as compared to 802.11 standard. WiMAX is a broadband wireless communication system, which enables convergence of mobile and fixed broadband networks through a common wide-area and
flexible network architecture. The mobile WiMAX air interfaces use OFDMA for improvement in multiple path interference in nonline-of-sight environ-ment. Its ability to support both line-of-sight and nonline-of-sight connections makes it suitable for ubiquitous services offered in rural and urban areas alike. High speed and symmetrical bandwidth satisfy the needs of individual customers, public administration, and enterprises of all sizes . The technology also provides fast and cheap broadband access to markets that lack infrastructure (fiber optics or copper wire), such as rural and unwired countries. Currently, several companies offer proprietary solutions for wireless broadband access, many of which are expensive because they use chipsets from adjacent technologies, such as 802.11. Early field experiments in various countries confirm that expectations in terms of coverage, performance, and usage scenarios are indeed justified. WiMAX has changed the scenario of wireless broadband from proprietary solutions to a standards-based industry. It supports fast Internet access, high-quality audio and video communications, education, entertainment, telemedicine, telemetering, and telesurveillance. WiMAX supports personal broadband services on both fixed and mobile settings because of its high spectral efficiency and wide channelization as well as the advanced antenna technologies. This flexibility in providing both fixed and mobile access within the same infrastructure is unprecedented among wireless technologies, which are typically optimized for either mobile or fixed access.

Figure 1: WiMAX Applications.

1 Cellular Application

The main merit of WiMAX is in the area of mobile service. For a large number
of cell phone operators the major monthly operating expense on T1 backhaul
that supports their base stations as shown in Figure 2. A WiMAX substitute
for the cell phone infrastructure could be operated with as little as 10% of T1
backhaul. While replacing a cell phone infrastructure with WiMAX one can
send a large amount of data because the bandwidth of WiMAX is far greater.
The data can include voice, mobile data, TV, videoconferencing, video on
demand, etc.

Figure 2: Cellular architecture using T1 as back haul.

2 WiMAX Military Applications

As WiMAX uses higher frequencies than current military and commercial communications, existing antenna towers share a WiMAX cell tower without compromising the current communication services. WiMAX can be used to support training and war game simulations. An initial deployment of WiMAX has already been constructed by the U.S. Army Fortdix. The U.S. army is testing prestandard WiMAX gear and Xacta secure wireless system from Telos Corporation in Fort Carson in Colorado for point-to-point and point-to-multipoint communications.

The forces at different locations can be connected through WiMAX as shown in Figure 3. They can exchange their information from multiple sources, rapidly and flexibly. This is ideally suited to meet the demands of the tactical defense operations model. The mobile antennas can be attached to a vehicle and the latest data can be provided to the soldiers. A communication from command centers can be made to the different centers, regardless of the distance, and directions can be delivered to the army people. The best part of WiMAX is the handover strategy. It uses “make-before-break’’ sequence rather than “break-before-make’’ sequence.

Figure 3: WiMAX architecture for Military Applications.

3 Medical Applications

In an emergency situation where patients require immediate medical support,
WiMAX can serve as the foundation of a mobile hospital. It can be a platform
for e-health. In e-health services a doctor can diagnose his patient at some

far location with the help of e-media. The doctor ’s computer equipped with the medical instruments can be connected to the patient’s computer through WiMAX.

A patient at location 2 can send his reports, for example, blood pressure, through his computer to the doctor ’s computer as shown in Figure 4. The doctor can diagnose the patient’s disease and give him necessary treatment. The connection between the doctor and the patient is through the Internet. The two computers are connected through WiMAX.

Figure 4: Medical Applications.

Also in some emergency situations, a video consultation with a doctor can be set up and the doctor can instruct the paramedic to mobilize the victim without inflicting further damage. With WiMAX, mobile hospital vans can communicate data and other instructions within a disaster zone. The information through WiMAX can be encrypted and made secure. So in diverse conditions WiMAX can provide to the patient valuable information recommended by doctors over large distances.

4 Security Systems

WiMAX offers a simple and convenient system for security on the borders and within the country to save the nation from some terrorist attacks.
A video camera can be mounted on WiMAX antenna or some separate pole, which can be controlled at the headquarters as shown in Figure 5. This camera will keep an eye over the different activities of the enemies thereby assisting in security planning. It can also be used to provide video surveillance of smuggling and illegal entries along the borders.

WiMAX is a medium for the security of not only army but also navy.
Through the use of WiMAX one can monitor the activities on the sea. A video
camera that is mounted on the antenna of a shipyard can monitor the nearby
activities and report to the headquarter as shown in Figure 5. So WiMAX
can effectively monitor shipyards, nuclear facilities, and key transport routes.

Figure 5: WiMAX architecture for security applications.

5 Disaster Applications

WiMAX can be used in recovery from disasters, such as earthquakes and floods, when the wired networks break down. It helps in connecting the disaster location to telephone services, hospitals, and other important services. In recent hurrican disasters, WiMAX networks were installed to help recovery missions. WiMAX can enable efficient communications with emergency operation centers regardless of the distance. Similarly, WiMAX is used as backup links for broken wired links.

6 Connectivity of Banking Networks

The banking system where security is the major concern can be connected
through the WiMAX networks. Owing to the broad coverage and large con-
nectivity, WiMAX can connect a large number of diversely located banks and

ATM locations. WiMAX networks provide not only
security but also a high degree of scalability. Through WiMAX, telephone
voice, financial transactions, email, Internet, intranet, surveillance, and close
circuit television (CCTV) type of data can be communicated easily.

7 Public Safety

Through WiMAX, public safety agencies can be connected with each other. During any mishap, such as accident, fire, etc., the control office can send its command to the police station, hospital, or fire brigade office. The corresponding agencies immediately can connect to the accidental location by using WiMAX-enabled vehicles.

The video images and data from the site of accidental location can be sent to corresponding agencies. These data can be examined by the experts of the emergency staff and accordingly prescription can be communicated. A video camera in the ambulance can send the latest images of the patient before the ambulance reaches the hospital so that the doctors can get ready for further action quickly. Through WiMAX, a fireman can download the data about the best route to a fire scene.

8 Campus Connectivity

Campus system requires high data capacity, a large coverage, and high
security. WiMAX can connect various blocks within the campus.
Through this connectivity voice, data, and video information can be sent to
various interconnecting blocks as shown in Figure 6. It is very difficult to
connect various blocks through cables because the lead time to deploy a wired
solution is much longer than the lead time to deploy a WiMAX solution.

Figure 6: WiMAX campus connectivity.

9 Educational Building Connectivity

WiMAX can connect boards, colleges, schools, and the main head offices as shown in Figure 7. Through this, telephone voice, data, email, Internet, question papers, intranet, video lectures, presentations, and students’ results can be communicated at a very high rate.

By video conferencing the students can interact with the teachers of another institution (i.e., engineering college, medical colleges, etc.) like as Figure 7. A camera at college 1 delivers real-time classroom instruction to college 2, allowing the colleges to simultaneously deliver instruction from a recognized subject matter expert to a large

Figure 7: WiMAX educational building connectivity.

number of students. Colleges and schools in rural areas can be connected through WiMAX with other institutions having better facilities through WiMAX so that remotely located students can also be benefitted.

Hence it can be concluded that this broadband wireless standard supports
both the computer and telecom industries worldwide, making this technology
highly cost effective. It helps enterprises, consumers, public services, and peo-
ple in urban and rural areas over a large range with high data throughput.

Simulation of 802.16E WiMAX Systems

2009-11-01T08:09:00.000-08:00

WiMAX is a telecommunication technology aimed at providing wireless data over long distances in a variety of ways, from point-to-point links to full mobile cellular type access. It is a certification
mark used for products based on the IEEE 802.16 family of standards, which specifies a wireless metropolitan-area network technology. 802.16e is an amendment to 802.16, which uses OFDMA and provides.

Figure 1: WiMAX Network

Design a WiMAX 802.16e system in MATLAB Simulink

Simulate the system using MATLAB Simulink

Look for options for better system performance

Transmitter transmits the orginal data using OFDMA

Receiver performs estimation and recovers the orginal

data from the receiver OFDMA sysbol

Channel simulates different cases such as direct input

AWGN, and frequency-select fading

Simulation Result

Dynamic simulation of mobile WiMAX networks

2009-11-01T07:36:00.000-08:00

The main aim of the present work has been to develop a
simulator to study WiMAX 802.16e performance. The use of
simulation tools in the planning of resources in radio systems
for mobile communications in general, and in particular in
WiMAX, is essential if it is to act as a way of predicting and
analyzing the performance of effective planning. Evaluating
the performance simulation of these systems has a key role in
the process of scaling at various planning stages.
The simulation tool developed can be characterized by
three successive stages, as illustrated in Figure II-1:
Configuration, Simulation and Analysis.
This simulator is based upon and greatly extends an existing
UMTS simulator [3]. The main changes made in the structure
of the simulator may be found in the Radio Prediction Module
and System Simulation Model. They have all been changed
owing to the fact that a different kind of technology is
involved. The Analysis Modules have been adapted so as to
assess the performance of WiMAX technology and a new
module has also been added to apply different algorithms to
the resource allocation, called the Scheduling Algorithms
module

Fig. 1: Characterization of the Simulation tool

WiMAX Simulation Tools List

2009-11-01T07:11:00.000-08:00

For the best thing in WiMax is right calculation and optimization of the Radio Frequency and Capacity, Network planning, to do those things you have to choose the best simulation tool which works on the wimax system. I have tried to write a list of all the famous and mostly used simulation and planning tools in the undermentioned list. Even you can try freeware soft wares to simulate your network design.

1. MATLAB -Web Site
2. OPNET tool - web site
3. Planet EV - web site
4. EDX (SignalPro) - web site
5. Provision Communication - web site
6. Radio Mobile (Freeware) - web site 1 web site 2 web site 3
7. Atoll - web site
8. CelPlan - web site
9. ICS Telecom - web site
10. Asset 3G/WiMAX - web site
11. Winprop - web site
12. Volcano Siradel - web site
13. NS-2 (Freeware) - web site
14. NS-3 (Freeware) - web site
15. Qualnet - web site
16. NCTuns Network Simulator and Emulator - web site

WiMAX Forum

2009-11-01T01:10:00.000-07:00

IEEE 802 standards provide only the technology. It is then needed to have other organisms for the certification of conformity and the verification of interoperability. In the case of IEEE 802.11 WLAN, the Wireless Fidelity Alliance (WiFi or Wi-Fi) Consortium had a major role in the success of the WiFi technology, as it is now known. Indeed, the fact that two WiFi certified IEEE 802.11 WLAN devices are guaranteed to work together paved the way for the huge spread of WiFi products.

The certification problem was even more important for WiMAX as many product manufacturers claimed they had verified the 802.16 standard. The WiMAX (Worldwide Interoperability for Microwave Access) Forum (http://www.wimaxforum.org) was created in June 2001 with the objective that the WiMAX Forum plays exactly the same role for IEEE 802.16 as WiFi for 802.11. The WiMAX Forum provides certification of conformity, compatibility and interoperability of IEEE 802.16 products. After a period of low-down, the WiMAX Forum was reactivated in April 2003. Some sources indicate this latter date as the date of the creation of the WiMAX Forum. Intel and Nokia, along with others, played a leading role in the creation of the Forum. Then Nokia became less active, claiming that it wished to concentrate on 3G. However, Nokia is again an active player of WiMAX.

WiMAX Forum members are system and semiconductors manufacturers, other equipment vendors, network operators, academics and other telecommunication actors. A complete list of the WiMAX Forum members can be found on the Forum Member Roster web page. A nonexhaustive list of WiMAX members is proposed in Table 1.

Table 1: Some WiMAX Forum members
Open table as spreadsheet
Manufacturers	Airspan, Alcatel, Alvarion, Broadcom, Cisco, Ericsson. Fujitsu, Huawei, Intel, LG, Lucent, Motorola, Navini, Nokia, Nortel, NEC Proxim, Sagem, Samsung, Sequans, Siemens, ZTE, etc.
Service providers	British Telecom, France Telecom, KT (Korea Telecom), PCCW, Sprint Nextel, Telmex, etc.

The site of the WiMAX Forum indicates that its objective is to facilitate the deployment of broadband wireless networks based on the IEEE 802.16 standard by ensuring the compatibility and interoperability of broadband wireless equipment.

1 WiMAX Forum Working Groups

The WiMAX Forum is organised into Working Groups (WGs).The scope of these WGs is given in Table 2, as indicated on the WiMAX Forum website.

Table 2: WiMAX Forum working groups. As of July 2006, the Forum website also indicates the Global Roaming Working Group (GRWG)
Open table as spreadsheet
Working group name	Scope
Application Working Group (AWG)	Defines applications over WiMAX that are necessary to meet core competitive offerings and are uniquely enhanced by WiMAX
Certification Working Group (CWG)	Handles the operational aspects of the WiMAX Forum certification program; interfaces with the certification lab(s); selects new certification lab(s).
Marketing Working Group (MWG)	Promotes the WiMAX Forum, its brands and the standards that form the basis for worldwide interoperability of BWA systems
Network Working Group (NWG)	Creates higher-level networking specifications for fixed, nomadic, portable and mobile WiMAX systems, beyond what is defined in the scope of 802.16; specifically, the NWG defines the architecture of a WiMAX network
Regulatory Working Group (RWG)	Influences worldwide regulatory agencies to promote WiMAX-friendly, globally harmonised spectrum allocations
Service Provider Working Group (SPWG)	Gives service providers a platform for influencing BWA product and spectrum requirements to ensure that their individual market needs are fulfilled
Technical Working Group (TWG)	Develops conformance test specifications and certification services and profiles based on globally accepted practices to achieve worldwide interoperability of BWA systems

2 WiMAX Forum White Papers

The WiMAX Forum regularly publishes White Papers. These are a very useful information source about WiMAX, freely available on the Forum website. In Table 3, a nonexhaustive list of White Papers is proposed (until July 2006).

Table 3: WiMAX Forum (http://www.wimaxforum.org) White Papers, last update: July 2006. Table was drawn with the help of Ziad Noun
Open table as spreadsheet
Title	Date of latest version	Number of pages	Brief description
IEEE 802.16a standard and WiMAX -Igniting BWA	Date not mentioned	7	An overview of IEEE 802.16a standard, its PHY and MAC layers; talks also about the WiFi versus WiMAX scalability
Regulatory position and goals of the WiMAX Forum	August 2004	6	Describes the goals of WiMAX Forum (interoperability of broadband wireless products); describes also the initial frequency bands (license and license exempt)
Business case for fixed wireless access in emerging markets	June 2005	22	Describes the characteristics of emerging markets and discusses the service and revenue assumptions for business case analysis (urban, suburban, rural)
WiMAX deployment considerations for fixed wireless access in the 2.5 GHz and 3.5 GHz licensed bands	June 2005	21	About the licensed spectrum for WMAN, the radio characteristics, the range and the capacity of the system in different sccnarios (urban, suburban. etc.)
Business case models for fixed broadband wireless access based on WiMAX technology and the 802.16 standard	October 2004	24	Describes the WiMAX architecture and applications, the business case considerations and assumptions and the services oftered by WiMAX
Initial certification profiles and the European regulatory framework	September 2004	4	Describes the profiles currently identified for the initial certification process and the tentative profiles under consideration for the next round of the certification process
WiMAX's technology for LOS and NLOS environments.	August 2004	10	About the characteristics of OFDM and the other solutions used by WiMAX to solve the problems resulting from NLOS (subchannelisation, directional antennas, adaptive modulation, error correction techniques, power control, etc.)
Telephony's ‘Complete Guide to WiMAX’	May 2004	10	About WiMAX marketing and policy considerations
What WiMAX Forum certified products will bring to Wi-Fi	June 2004	10	Why WiFi is used in WiMAX, the OFDM basics, the 802.16/HiperMAN PHY and MAC layers, the operator requirements for BWA systems and the products certification
What WiMAX Forum certified products will bring to 802.16	June 2004	6	The certified products: where do WiMAX Forum certified products fit and why select them?
Fixed, nomadic, portable and mobile applications for 802.16-2004 and 802.16e WiMAX networks	November 2005	16	Compares the two possibilities of deployment for an operator: fixed WiMAX (802.16-2004) or mobile WiMAX (802.16e)
The WiMAX Forum certified program for fixed WiMAX	March 2006	15	Describes the general WiMAX certification process and specifically the fixed WiMAX system profiles certifications
Third WiMAX Forum plugfest - test methodology and key learnings	March 2006	18	Describes WiMAX March 2006 plugfest
Mobile WiMAX - Part I: a technical overview and performance evaluation	March 2006	53	Technical overview of 802.16e system (mobile WiMAX) and the corresponding WiMAX architecture
Mobile WiMAX - Part II: a comparative analysis	May 2006	47	Compares elements between mobile WiMAX and presently used 3G systems (1xEVDO and HSPA)
Mobile WiMAX: the best personal broadband experience!	June 2006	19	Provides mobile WiMAX advantages in the framework of mobile broadband access market
Executive summary: mobile WiMAX performance and comparative summary	July 2006	10	Brief overview of mobile WiMAX and summary of previous White Papcr performance data

Physical Layer or The Physical Layer of WiMAX

2009-11-01T00:28:00.000-07:00

The 802.16 Physical Transmission Chains

The modulation and OFDM transmission are the major building blocks of the WiMAX PHYsical Layer. The transmission chains of WiMAX are described for both OFDM and OFDMA PHYs.

1 The Global Chains

The PHY transmission chains of OFDM and OFDMA are illustrated in Figures 1 and 2. The blocks are the same with the small difference that OFDMA PHY includes a repetition block. The modulated symbols are then transmitted on the OFDM orthogonal subcarriers. In the following, WiMAX channel coding building blocks are described.

Figure 6.1: OFDM PHY transmission chain

Figure 6.2: OFDMA PHY transmission chain

2 Channel Coding

The radio link is a quickly varying link, often suffering from great interference. Channel coding, whose main tasks are to prevent and to correct the transmission errors of wireless systems, must have a very good performance in order to maintain high data rates. The 802.16 channel coding chain is composed of three steps: randomiser, Forward Error Correction (FEC) and interleaving. They are applied in this order at transmission. The corresponding operations at the receiver are applied in reverse order.

3 Turbo Coding

Turbo codes are one of the few FEC codes to come close to the Shannon limit, the theoretical limit of the maximum information transfer rate over a noisy channel. The turbo codes were proposed by Berrou and Glavieux (from ENST Bretagne, France) in 1993. The main feature of turbo codes that make them different from the traditional FEC codes are the use of two error-correcting codes and an interleaver. Decoding is then made iteratively taking advantage of the two sources of information

4 Transmission Convergence Sublayer (TCS)

The Transmission Convergence Sublayer (TCS) is defined in the OFDM PHY Layer and the Non-WiMAX SC PHY Layer. The TCS is located between the MAC and PHY Layers. If the TCS is enabled, the TCS converts MAC PDUs of variable size into proper-length FEC blocks, called TC PDU.

The TCS is an optional mechanism for the OFDM PHY. It can be enabled on a preburst basis for both the uplink and downlink through the burst profile definitions in the uplink and downlink channel descriptor (UCD and DCD) messages respectively. The TCS_ENABLE parameter is coded as a TLV tuple in the DCD and UCD burst profile encodings. At SS initialisation, the TCS capability is negotiated between the BS and SS through SBC-REQ/SBC-RSP MAC messages as an OFDM PHY specific parameter. The TCS is not included in the OFDMA PHY Layer.

Finally, the burst profiles of OFDM and OFDMA PHY, an important building block of IEEE 802.16 MAC layer, are described:

6.5 Burst Profile

5 Burst Profile

The burst profile is a basic tool in the 802.16 standard MAC Layer. The burst profile allocation, which changes dynamically and possibly very fast, is about physical transmission. Here the parameters of the burst profiles of WiMAX are summarised. The burst profiles are used for the link adaptation procedure.

5.1 Downlink Burst Profile Parameters

The burst profile parameters of a downlink transmission for OFDM and OFDMA PHYsical layers are proposed in Table 1. The parameter called FEC code is in fact the Modulation and Coding Scheme (MCS). For OFDM PHY, there are 20 MCS combinations of modulation (BPSK, QPSK, 16-QAM or 64-QAM), coding (CC, RS-CC, CTC or BTC) and coding rate (1/2, 2/3, 3/4 and 5/6). The most frequency-use efficient (and then less robust) MCS is 64-QAM (BTC) 5/6. For OFDMA PHY, there are 34 MCS combinations of modulation (BPSK, QPSK, 16-QAM or 64-QAM), coding (CC, ZT CC, CTC, BTC, CC with optional interleaver) and coding rate (1/2, 2/3, 3/4 and 5/6).

Table 1: Downlink burst profile parameters for OFDM and OFDMA PHYsical layers
Open table as spreadsheet
Burst profile parameter	Description
Frequency (in kHz)	Downlink frequency
FEC code type	Modulation and Coding Scheme (MCS); there are 20 MCSs in OFDM PHY and 34 MCSs in OFDMA PHY (as updated in 802.16e)
DIUC mandatory exit threshold	The CINR at or below where this burst profile can no longer be used and where a change to a more robust (but also less frequency-use efficient) burst profile is required. Expressed in 0.25 dB units.
DIUC minimum entry threshold	The minimum CINR required to start using this burst profile when changing from a more robust burst profile. Expressed in 0.25 dB units
TCS_enable (OFDM PHY only)	Enables or disables TCS

5.2 Uplink Burst Profile Parameters

The burst profile parameters of an uplink transmission for an OFDM PHY and an OFDMA PHY are proposed in Tables 2 and 3 respectively.

Table 2: Uplink burst profile parameters for the OFDMA PHYsical Layer
Open table as spreadsheet
Burst profile parameter	Description
FEC type and modulation type	There are 20 MCSs in OFDM PHY
Focused contention power boost	The power boost in dB of focused contention carriers
TCS_enable	Enables or disables TCS

Table 3: Uplink burst profile parameters for the OFDMA PHYsical Layer
Open table as spreadsheet
Burst profile parameter	Description
FEC type and modulation type	There are 52 MCSs in OFDMA PHY
Ranging data ratio	Reducing factor, in units of 1 dB, between the power used for this burst and the power used for CDMA ranging encoded as a signed integer

5.3 MCS Link Adaptation

The choice between different burst profiles or, equivalently, between different MCSs is a powerful tool. Specifically, choosing the MCS most suitable for the state of the radio channel, at each instant, leads to an optimal (highest) average data rate. This is the so-called link adaptation procedure. In the following chapters the MAC procedures that can be used for the implementation of link adaptation are described. The link adaptation algorithm in itself is not indicated in the 802.16 standard. It is left to the vendor or operator.

The order of magnitudes of SNR thresholds can be obtained from Table 4, proposed in the standard for some test conditions. These SNR thresholds are for a BER, Bit-Error Rate, measured after the FEC, that is smaller than 10⁻⁶.

Table 4: Received SNR threshold assumptions , Table 266. (From IEEE Std 802.16-2004 . Copyright IEEE 2004, IEEE. All rights reserved.)
Open table as spreadsheet
Modulation	Coding rate	Receiver SNR threshold (dB)
BPSK	1/2	6.4
QPSK	1/2	9.4
QPSK	3/4	11.2
QAM-16	1/2	16.4
QAM-16	3/4	18.2
QAM-64	1/2	22.7
QAM-64	3/4	24.4

Different types of Digital Modulation

2009-11-01T00:16:00.000-07:00

1.Digital Modulations

As for all recent communication systems, WiMAX/802.16 uses digital modulation. The now well-known principle of a digital modulation is to modulate an analogue signal with a digital sequence in order to transport this digital sequence over a given medium: fibre, radio link, etc. (see Figure 1). This has great advantages with regard to classical analogue modulation: better resistance to noise, use of high-performance digital communication and coding algorithms, etc

Figure 1: Digital modulation principle

2.Binary Phase Shift Keying (BPSK)

The BPSK is a binary digital modulation; i.e. one modulation symbol is one bit. This gives high immunity against noise and interference and a very robust modulation. A digital phase modulation, which is the case for BPSK modulation, uses phase variation to encode bits: each modulation symbol is equivalent to one phase. The phase of the BPSK modulated signal is π or -⁻π according to the value of the data bit. An often used illustration for digital modulation is the constellation. Figure 5.2 shows the BPSK constellation; the values that the signal phase can take are 0 or π.

Figure 2: The BPSK constellation
3. Quadrature Phase Shift Keying (QPSK)

When a higher spectral efficiency modulation is needed, i.e. more b/s/Hz, greater modulation symbols can be used. For example, QPSK considers two-bit modulation symbols.

Table 1 shows the possible phase values as a function of the modulation symbol. Many variants of QPSK can be used but QPSK always has a four-point constellation (see Figure 3). The decision at the receiver, e.g. between symbol ‘00’ and symbol ‘01’, is less easy than a decision between ‘0’ and ‘1’. The QPSK modulation is therefore less noiseresistant than BPSK as it has a smaller immunity against interference. A well-known digital communication principle must be kept in mind: ‘A greater data symbol modulation is more spectrum efficient but also less robust.’

Figure 3: Example of a QPSK constellation

Table 1: Possible phase values for QPSK modulation

Open table as spreadsheet
Even bits	Odd bits	Modulation symbol	ϕ_k
0	0	00	π/4
1	0	01	3π/4
1	1	11	5π/4
0	1	10	7π/4

4. Quadrature Amplitude Modulation (QAM): 16-QAM and 64-QAM

The QAM changes the amplitudes of two sinusoidal carriers depending on the digital sequence that must be transmitted; the two carriers being out of phase of +π/2, this amplitude modulation is called quadrature. It should be mentioned that according to digital communication theory, QAM-4 and QPSK are the same modulation (considering complex data symbols). Both 16-QAM (4 bits/modulation symbol) and 64-QAM (6 bits/modulation symbol) modulations are included in the IEEE 802.16 standard. The 64-QAM is the most efficient modulation of 802.16 (see Figure 4). Indeed, 6 bits are transmitted with each modulation symbol.

Figure 4: A 64-QAM constellation

The 64-QAM modulation is optional in some cases:

license-exempt bands, when the OFDM PHYsical Layer is used
for OFDMA PHY, yet the Mobile WiMAX profiles indicates that 64-QAM is mandatory in the downlink.

What is Internet Engineering Task Force (IETF)

2009-11-01T00:12:00.000-07:00

Since most data applications in wireless networks are IP-based, it comes as no surprise that the IETF and the protocols it specifies are becoming increasingly relevant to the wireless data industry. The IETF is organized in areas that organize technically related Working Groups. The current IETF areas are as follows:

Applications Area deals with applications and application protocols like presence and instant messaging, network time protocol, calendaring, and scheduling.
General Area addresses topics related to the general operation of the IETF, such as rules setting.
Routing Area specifies routing protocols and their applicability.
Internet Area defines IP protocol-related matters, such as the definition of its evolution, the support of network services such as PPP (Point-to-Point Protocol), and IP host configuration. Recently, it took on the role of specifying the Mobile IP protocol from the Routing Area, since Mobile IP is now perceived as a mobile remote IP network access technology, rather than a routing protocol.
Operations and Management Area defines network management aspects and protocols, such as the well-known Simple Network Management Protocol (SNMP) and its evolution.
Security Area addresses Internet security aspects.
Sub-IP Area is devoted to the definition of technologies and protocols that normally are located at a layer below IP in the protocol stack and are devoted to the provision of services such as VPNs, traffic engineering, and transport of link layers or even circuit emulation.
Transport Area is responsible for the definition of transport-related matters, such as QoS, transport-level protocols (for instance, recently transport protocols for carrying signaling was defined), and congestion control.

Each of these areas is led by one or two area directors. Area directors and the IETF chair are members of the Internet Engineering Steering Group (IESG), which has the role of standards quality evaluation and can strongly influence the transition of an Internet Draft to proposed standards RFC status, by returning it to the WG until it attains an adequate level of quality to be published.

Benefits of Wireless Communications with MVPN (Mobile Virtual Private Network)

2009-10-31T06:35:00.001-07:00

For wireless operators deploying latest-generation cellular systems based on packet-switched data such as GPRS and CDMA2000, and especially those targeting business customers for significant portion of their revenue stream, the importance of services based on MVPN technologies is hard to underestimate. For operators, MVPN is not only one of the required technologies for business customers' private network access but also a foundation for other services requiring interaction with private networks such as m-commerce, virtual presence and gaming applications, and multimedia applications (which includes Voice over IP-based services).

The benefits of deploying Mobile VPNs for businesses and institutions include:

Uninterrupted, media and location-independent connectivity to private networks
Seamless private network access mobility
Connectivity to a particular Internet service provider (ISP) or application service provider (ASP)
Mobile remote access outsourcing possibilities
Secure m-commerce enabler
Constant remote-workers reachability
Higher cost-effectiveness

As a result, businesses, which already had a positive experience with wireline VPN services, are now looking to wireless operators for extending these services into wireless environments. In our view, during the next few years as the latest generations of cellular systems and other wireless technologies take off, an enormous market opportunity awaits wireless carriers who can meet demands for services requiring private network access.

What is 3G or Wideband Digital Cellular System

2009-10-31T06:34:00.001-07:00

The 3rd generation wireless requirements are defined in the International Mobile Telecommunications “IMT-2000” project developed by the International Telecommunication Union (ITU). The IMT-2000 project that defined requirements for high-speed data transmission, Internet Protocol (IP)-based services, global roaming, and multimedia communications. After many communication proposals were reviewed, two global systems are emerging; wideband code division multiple access (WCDMA) and CDMA2000.

Wideband Code Division Multiple Access (WCDMA)

WCDMA is a 3rd generation digital cellular system that uses radio channels that have a wider bandwidth than 2nd generation digital cellular systems such as GSM or IS-95 CDMA. WCDMA is normally deployed in a 5 MHz channel plan.

The Third Generation Partnership Project (3GPP) oversees the creation of industry standards for the 3rd generation of mobile wireless communication systems (WCDMA). The key members of the 3GPP include standards agencies from Japan, Europe, Korea, China and the United States. The 3GPP technology, also known as the Universal Mobile Telecommunications System (UMTS), is based on an evolved GSM core network that contains 2.5G elements, namely GPRS switching nodes. This concept allows a GSM network operator to migrate to WCDMA by adding the necessary 3G radio elements to their existing network, thus creating ‘islands’ of 3G coverage when the networks first launch.

A large number of GSM operators have secured spectrum for WCDMA and many network launches are imminent, with live networks presently in Japan, the United Kingdom and Italy.

Code Division Multiple Access 2000 (CDMA2000)

CDMA2000 is a family of standards that represent an evolution from the IS- 95 code division multiple access (CDMA) system that offer enhanced packet transmission protocols to provide for advanced high-speed data services. The CDMA2000 technologies operate in the same 1.25 MHz radio channels as used by IS-95 and offer backward compatibility with IS-95.

The CDMA2000 system is overseen by the Third Generation Partnership Project 2 (3GPP2). The 3GPP2 is a standards setting project that is focused on developing global specifications for 3rd generation systems that use ANSI/TIA/EIA-41 Cellular Radio Intersystem Signaling.

Time Division Synchronous CDMA (TD-SCDMA)

On a global basis it likely that WCDMA and CDMA2000^TM will dominate the 3G market, however in China there is growing support for a homegrown standard known as Time Division Synchronous CDMA (TD-SCDMA). TDSCDMA offers voice services and data services, both circuit-switched and packet-switched, at rates up to 2 Mbps. It uses a Time Division Duplex (TDD) technique in which transmit and receive signals are sent on the same frequency but at different times. The timeslots on the radio carrier can either be allocated symmetrically for services such as speech or asymmetrically for data services where the bit rates in the two directions of transmission may differ significantly.

Upgraded Digital Cellular System (Generation 2.5)

2009-10-31T06:33:00.000-07:00

The types of upgraded 2nd generation digital cellular systems (generation 2.5) include GPRS, EDGE, and CDMA2000^TM , 1xRTT.

General Packet Radio Service (GPRS)

General Packet Radio Service (GPRS) is a portion of the GSM specification that allows packet radio service on the GSM system. The GPRS system adds (defines) new packet channels and switching nodes within the GSM system. The GPRS system provides for theoretical data transmission rates up to 172 kbps.

Enhanced Data Rates for Global Evolution (EDGE)

Enhanced Data Rates for global Evolution (EDGE) is an evolved version of the global system for mobile (GSM) radio channel that uses new phase modulation and packet transmission to provide for advanced high-speed data services. The EDGE system uses 8 levels Phase Shift Keying (8PSK) to allow one symbol change to represent 3 bits of information. This is 3 times the amount of information that is transferred by a standard 2 level Gaussian Minimum Shift Keying (GMSK) signal used by the first generation of GSM system. This results in a radio channel data transmission rate of 604.8 kbps and a net maximum delivered theoretical data transmission rate of 384 kbps. The advanced packet transmission control system allows for constantly varying data transmission rates in either direction between mobile radios.

CDMA2000™, 1xRTT

CDMA2000^TM is a 3G standard that allows operators to evolve from their existing IS-95 networks to offer 3G services. The original CDMA2000^TM proposal contained two distinct evolutionary phases, the first known as 1xRTT used the same 1.25 MHz channels as IS-95 but delivered increased capacity and data rates compared to IS-95. The second phase was known as 3xRTT that uses three times the spectrum of IS-95, that is 3.75 MHz. The 3xRTT concept would deliver data rates up to 2 Mbps, a requirement for any 3G technologies. However recent evolutions of 1xRTT are offering data rates in excess of this and therefore it is unlikely that 3xRTT is required.

By the middle of 2003 there were a total of 60 commercial 1xRTT networks offering service.

Evolution Data Only (1xEVDO)

The evolution of existing systems for data only (1xEVDO) is an evolved version of the CDMA2000^TM 1xRTT system. The 1xEVDO system uses the same 1.25 MHz radio channel bandwidth as the existing IS-95 system that provides for multiple voice channels and medium rate data services. The 1xEVDO version changes the modulation technology to allow for data transmission rates up to 2.5 Mbps. The 1xEVDO system has an upgraded packet data transmission control system that is allows for bursty data transmission rather than for more continuous voice data transmission.

Evolution Data and Voice (1xEVDV)

The evolution of existing systems for data and voice (1xEVDV) is an evolved version of the CDMA2000^TM 1xRTT system that can be used for data and voice service. The 1xEVDV system provides for both voice and high-speed data transmission services in the same 1.25 MHz radio channel bandwidth as the existing IS-95 system. The 1xEVDV Vision allows for a maximum data transmission rate of approximately 2.7 Mbps.

What is Code Division Multiple Access (IS-95 CDMA)

2009-10-31T06:16:00.001-07:00

Code Division Multiple Access (CDMA) system (IS 95) is a digital cellular system that uses CDMA access technology. IS-95 technology was initially developed by Qualcomm in the late 1980’s. CDMA cellular service began testing in the United States in San Diego, California during 1991. In 1995, IS-95 CDMA commercial service began in Hong Kong and now many CDMA systems are operating throughout the world, including a 1.9 GHz all-digital system in the USA that has been operating since November 1996 (Fig. 1).

Fig. 1: CDMA Tower

Spread spectrum radio technology has been used for many years in military applications. CDMA is a particular form of spread spectrum radio technology. In 1989, CDMA spread spectrum technology was presented to the industry standards committee but it did not meet with immediate approval. The standards committee had just resolved a two-year debate between TDMA and FDMA and was not eager to consider another access technology.

The IS-95 CDMA system allows for voice or data communications on either a 30 kHz AMPS radio channel (when used on the 800 MHz cellular band) or a new 1.25 MHz CDMA radio channel. The IS-95 CDMA radio channel allows multiple mobile telephones to communicate on the same frequency at the same time by special coding of their radio signals.

CDMA radio channels carry control, voice, and data signals simultaneously by dividing a single traffic channel (TCH) into different sub-channels. Each of these channels is identified by a unique code. When operating on a CDMA radio channel, each user is assigned to a code for transmission and reception. Some codes in the TCH transfer control channel information, and some transfer voice channel information.

The control channel that is part of a digital traffic channel on a CDMA system has new advanced features. This digital control channel (DCC) carries system and paging information, and coordinates access similar to the analog control channel (ACC). The DCC has many more capabilities than the ACC such as a precision synchronization signal, extended sleep mode, and others. Because each CDMA radio channel has many codes, more than one control channel can exist on a single CDMA radio channel and the CDMA control channels co-exist with other coded channels that are used for voice.

The IS-95 CDMA cellular system has several key attributes that are different from other cellular systems. The same CDMA radio carrier frequencies may be optionally used in adjacent cell sites, which eliminates the need for frequency planning, the wide-band radio channel provides less severe fading, which the inventors claim results in consistent quality voice transmission under varying radio signal conditions. The CDMA system is compatible with the established access technology, and it allows analog (EIA-553) and dual mode (IS-95) subscribers to use the same analog control channels. Some of the voice channels are replaced by CDMA digital transmissions, allowing several users to be multiplexed (shared) on a single RF channel. As with other digital technologies, CDMA produces capacity expansion by allowing multiple users to share a single digital RF channel.

The IS-95 CDMA radio channel divides the radio spectrum into wide 1.25 MHz digital radio channels. CDMA radio channels differ from those of other technologies in that CDMA multiplies (and therefore spreads the spectrum bandwidth of) each signal with a unique pseudo-random noise (PN) code that identifies each user within a radio channel. CDMA transmits digitized voice and control signals on the same frequency band. Each CDMA radio channel contains the signals of many ongoing calls (voice channels) together with pilot, synchronization, paging, and access (control) channels. Digital mobile telephones select the signal they are receiving by correlating (matching) the received signal with the proper PN sequence. The correlation enhances the power level of the selected signal and leaves others unenhanced.

Each IS-95 CDMA radio channel is divided into 64 separate logical (PN coded) channels. A few of these channels are used for control, and the remainders carry voice information and data. Because CDMA transmits digital information combined with unique codes, each logical channel can transfer data at different rates (e.g. 4800 b/s, 9600 b/s).

CDMA systems use a maximum of 64 coded (logical) traffic channels, but they cannot always use all of these. A CDMA radio channel of 64 traffic channels can transmit at a maximum information throughput rate of approximately 192 kbps [14], so the combined data throughput for all users cannot exceed 192 kbps. To obtain a maximum of 64 communication channels for each CDMA radio channel, the average data rate for each user should approximate 3 kbps. If the average data rate is higher, less than 64 traffic channels can be used. CDMA systems can vary the data rate for each user dependent on voice activity (variable rate speech coding), thereby decreasing the average number of bits per user to about 3.8 kbps [15]). Varying the data rate according to user requirement allows more users to share the radio channel, but with slightly reduced voice quality. This is called soft capacity limit.

In 1997 the CDMA Development Group (CDG) registered the trademark cdmaOne ^TM as a label to identify second-generation digital systems based on the IS-95 standard and related technologies.

Bangladesh WiMAX First Introduces Augere Brand Name 'Qubee'

2009-10-31T06:16:00.000-07:00

Jerry Mobbs, chief executive officer of
Augere, speaks at the launch of the
company's wireless broadband service
in Dhaka yesterday.Photo: Masthead PR

Augere Wireless Broadband Bangladesh Ltd yesterday launched the much-waited wireless broadband service through WiMax in some designated areas in Dhaka.

Augere, one of the two WiMax licensees, is the first company in Bangladesh to launch such service under the brand name 'Qubee'.

Augere is initially offering two packages. Customer will have to pay Tk 3,400 a month for the Qubee 512 kbps package. The monthly charge for the Qubee 1 Mb has been fixed at Tk 6,200, while the modem price for both the packages is Tk 7,000.

Initially, the Qubee service is available for businesses and residential customers in Gulshan, Banani, Baridhara, Mirpur and Uttara. Qubee will be available across Bangladesh soon.

WiMax is a technology that provides wireless transmission of data using a variety of transmission modes from point-to-multipoint links to portable and fully mobile internet access. The technology supports peak download rates of up to 46 Mbps and peak uplink rates of up to 14 Mbps.

Jerry Mobbs, chief executive officer of Augere Bangladesh, Russell T Ahmed, chief marketing officer, were present at the launching ceremony.

"We can offer low priced packages, but our goal is to ensure quality first," said Ahmed. "We believe our services will satisfy our customers."

Augere also unveiled a Qubee Flagship Store at Gulshan to provide 24-hour customer services.

Three bidders -- BanglaLion Communication, BRAC BD Mail Network Ltd and Augere Wireless Broadband Bangladesh Ltd -- won the WiMax licences through an auction organised by the Bangladesh Telecommunication Regulatory Commission (BTRC) in September last year. However, BRAC later refused to take the licence.

UK-based Augere Holdings owns 60 percent of Augere Wireless Broadband Bangladesh Ltd along with two local companies. Teleport Bangladesh owns 30 percent and Aamra Resources Ltd owns the remaining 10 percent.

Global System for Mobile Communication (GSM)

2009-10-31T06:14:00.000-07:00

The Global System for Mobile Communications (GSM) system is a global digital radio system that uses Time Division Multiple Access (TDMA) technology. GSM is a digital cellular technology that was initially created to provide a single-standard pan-European cellular system. GSM began development in 1982, and the first commercial GSM digital cellular system was activated in 1991. GSM technology has evolved to be used in a variety of systems and frequencies (900 MHz, 1800 MHz and 1900 MHz) including Personal Communications Services (PCS) in North America and Personal Communications Network (PCN) systems throughout the world. By the middle of 2003, 510 networks in 200 countries offered GSM service (Fig: 1).

Fig 1: GSM Network

The GSM system is a digital-only system and was not designed to be backward-compatible with the established analog systems. The GSM radio band is shared temporarily with analog cellular systems in some European nations.

When communicating in a GSM system, users can operate on the same radio channel simultaneously by sharing time slots. The GSM cellular system allows 8 mobile telephones to share a single 200 kHz bandwidth radio carrier waveform for voice or data communications. To allow duplex operation, GSM voice communication is conducted on two 200 kHz wide carrier frequency waveforms.

The GSM system has several types of control channels that carry system and paging information, and coordinates access like the control channels on analog systems. The GSM digital control channels have many more capabilities than analog control channels such as broadcast message paging, extended sleep mode, and others. Because the GSM control channels use only a portion (one or more slots), they typically co-exist on a single radio channel with other time slots that are used for voice communication.

A GSM carrier transmits at a bit rate of 270 kbps, but a single GSM digital radio channel or time slot is capable of transferring only 1/8th of that, about 33 kbps of information (actually less than that, due to the use of some bit time for non-information purposes such as synchronization bits).

Time intervals on full rate GSM channels are divided into frames with 8 time slots on two different radio frequencies. One frequency is for transmitting from the mobile telephone; the other is for receiving to the mobile telephone. During a voice conversation at the mobile set, one time slot period is dedicated for transmitting, one for receiving, and six remain idle. The mobile telephone uses some of the idle time slots to measure the signal strength of surrounding cell carrier frequencies in preparation for handover.

On the 900 MHz band, GSM digital radio channels transmit on one frequency and receive on another frequency 45 MHz higher, but not at the same time. On the 1.9 GHz band, the difference between transmit and receive frequencies is 80 MHz. The mobile telephone receives a burst of data on one frequency, then transmits a burst on another frequency, and then measures the signal strength of at least one adjacent cell, before repeating the process.

WiMAX Advantages

2009-10-31T06:13:00.000-07:00

The IEEE 802.16 standard is designed for WMAN networks. It provides inter-
operable broadband wireless connectivity to fixed and nomadic users. It
provides up to 50 km of service area and allows the users to get broadband
connectivity without the need of direct line of sight to the base station. It pro-
vides a total data rate of up to 75 Mbps, which is enough to simultaneously
support a lot of business and home requirements. The advantages of WiMAX
are given as follows.

1. High Capacity
A single WiMAX main station can serve hundreds of users. It targets a range
of up to 31 miles with target transmission rate exceeding 100 Mbps. By using
higher modulation, bandwidth can further be increased. Through WiMAX
one can transfer data, voice, Internet, video images, pictures, video conferencing, etc., at a very high data rate. So WiMAX can provide sufficient bandwidth to the end users

2. Quality of Service
The MAC layer of the WiMAX architecture is responsible for Qos. Subchannelization and different coding schemes enable end-to-end QoS. High data rate and flexible scheduling can enhance the QoS.

3. Flexible Architecture
The architecture of WiMAX is highly flexible. Depending upon the require-
ment it can connect different stations on point-to-point or point-to-multipoint
basis. Further the range can be increased with the help of directional antennas.

4. Mobility
In WiMAX, the user device can maintain an operating network data service session for real-time application as it moves at vehicular speeds within the network coverage area. It supports optimized handover schemes with latencies less than 50 ms to ensure real-time application such as voice over Internet protocol (VoIP) without service degradation. Flexible key management assures that security is maintained during handover.

5. Improved User Connectivity
The IEEE 802.16 standard keeps more users connected by virtue of its flexible channel bandwidths and adaptive modulation. WiMAX uses channels narrower than the fixed 20 MHz channels used in Wi-Fi. It can serve lower data rate users without wasting bandwidth. Adaptive modulation helps to connect them in the noisy or low-signal strength conditions.

6 Robust Carrier Class Operation
As the number of users accessing the data increases, the aggregate bandwidth is shared because of which the individual throughput starts decreasing linearly. The decrease is lesser than what is experienced under Wi-Fi. So this standard is designed for carrier class operation.

7. Scalability
WiMAX system offers scalability in network architecture as well as in radio access technology. It provides a great deal of flexibility in network deployment options and service offerings. It is designed to work in different forms of channelization from 1.25 to 20 MHz to comply with varied worldwide requirements. It can also fulfill the needs such as providing affordable Internet access in rural areas versus enhancing the capacity of broadband access in metro and suburban areas only.

8. Nonline-of-Sight Connectivity
WiMAX is based on OFDM technology and can handle nonline-of-sight connectivity. This capability helps WiMAX to communicate in a nonline-of-sight environment, which other wireless products cannot. The nonline-of-sight coverage can further be increased by using directional antennas or adaptive modulation .

9. Cost Effectiveness
Mass adoption of the standard and the use of low-cost, mass-produced chipsets can reduce costs dramatically, and the resultant competitive pric-
ing will provide considerable cost saving for service providers and end users.
Further, base stations and base station equipments need not be installed in
totality at the outlet, but can be deployed over a period of time to address
specific market segments or geographical areas of Internet to the operator.

10. Fixed and Nomadic Access
WiMAX can provide both fixed and nomadic access to its users. In fixed
access, the user device is assumed to be fixed in a single geographical area
for the duration of the network subscription. Here the user can connect and
disconnect from the network. It can select the best base station while entering
the network. The user is associated only with the same base station sector or
cell, and any reassociation with other cell is controlled by the network.
In nomadic access, the user device is assumed to be fixed in a geographical
location at least as long as the network data service session is in operation
if the user shifts to a new location in the same wireless network. The user
subscription is recognized, and a new data service session is established. The
user device is associated with the same base station during a data service
session. So WiMAX complements third-generation mobile networks by pro-
viding “nomadic’’ broadband access. Vendors can now compete to sell their
equipment, which benefits the customer base by providing lower costs and
enabling broadband access in emerging markets.

What do you mean by WiMAX Standard

2009-10-31T06:12:00.000-07:00

WiMAX technology is specified by IEEE as IEEE 802.16 standard. The technology extends as IEEE 802.16 a, b, d, and e and they operate in different frequencies band and different data rate. TheIEEE802.16-2004 includes P2P, P2MP and mesh access networks while the IEEE 802.16e-2005 includes mobility. Table 1.1 shows WiMAX Standards.

History of Mobile Cellular System

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First Generation(1G)

The 1G period began in the late 1970s and lasted through the 1980s. These systems featured the first true mobile phone systems, known at first as "cellular mobile radio telephone." These networks used analog voice signaling, and were little more sophisticated than the repeater networks used by amateur radio operators.
Second Generation (2G)
The 2G phase began in the 1990s and much of this technology is still in use. The 2G cell phone features digital voice encoding. Examples include CDMA and GSM. Since its inception, 2G technology has steadily improved, with increased bandwidth, packet routing, and the introduction of multimedia.

Third Generation (3G)
3G refers to the third generation of developments in wireless technology, especially mobile communications. The third generation, as its name suggests, follows the first generation (1G) and second generation (2G) in wireless communications.
3G includes capabilities and features such as:
• Enhanced multimedia (voice, data, video, and remote control).
• Usability on all popular modes (cellular telephone, e-mail, paging, fax, videoconferencing, and Web browsing).
• Broad bandwidth and high speed (upwards of 2 Mbps).
• Roaming capability throughout Europe, Japan, and North America.

3G offers the potential to keep people connected at all times and in all places. Researchers, engineers, and marketers are faced with the challenge of accurately predicting how much technology consumers will actually be willing to pay for. Another challenge faced by 3G services is competition from other high-speed wireless technologies, especially mobile WiMAX, and ability to roam between different kinds of wireless networks.
The current status of mobile wireless communications, as of July 2007, is a mix of 2nd and 3rd generation technologies.

WiMAX, How do WiMAX Works?

2009-10-31T06:10:00.000-07:00

Worldwide interoperability for microwave access (WiMAX), based on the
Institution of Electrical & Electronics Engineering (IEEE) 802.16 standards,
enables wireless broadband access anywhere, anytime, and on virtually
any device. When users want broadband service today, they are generally
restricted to a T1, digital subscriber loop (DSL), or cable modem-based con-
nection. However, these wireline infrastructures can be considerably more
expensive and time-consuming to deploy than a wireless system. In addi-
tion, rural areas and developing countries lack optical fiber or copper wire
infrastructure for broadband services, and service providers are unwilling
to install the necessary equipments in these areas because of little profit and
potential. WiMAX is an ideal technology for backhaul applications because
it eliminates expansive leased line or fiber alternative. WiMAX promises to
deliver high data rates over large areas to a large number of users (Shows Fig w).
It can provide broadband access to locations in the world’s rural and developing areas
where broadband is currently unavailable.

Fig w: WiMAX network

WiMAX has numerous advantages, such as improved performance and
robustness, end-to-end internet protocol (IP)-based network, secure mobility,
and broadband speeds for voice, data, and video. It is a wireless metropolitan
area network (WMAN) technology that provides interoperable broadband
wireless connectivity to fixed, portable, and nomadic users within 50 km of
service area. It allows the users to get broadband connectivity without the
need of direct line-of-sight communication to the base station and provides
total data rates up to 75 Mbps with sufficient bandwidth to simultaneously
support hundreds of residential and business areas with a single base station.
In fact WiMAX is not a technology, but rather a configuration mark, or
“stamp of approval’’ given to equipments that meet certain conformity and
interoperability tests for the IEEE 802.16 family of standards. A similar con-
fusion surrounds the term Wi-Fi (wireless fidelity), which like WiMAX, is
a certification mark for equipments based on a different set of IEEE stan-
dard from the 802.11 working group for wireless local area network (WLAN).
Neither WiMAX nor Wi-Fi is a technology but their names have been adopted
in popular usage to denote the technologies behind them. This is due to the
difficulty of using terms like IEEE 802.11 in common speech and writing.
WiMAX is a term coined to describe standard, interoperable implementation
of IEEE 802.16 wireless networks in a way similar to Wi-Fi being interopera-
ble of the 802.11 WLAN standards. However, the working of WiMAX is very
different from Wi-Fi.