WiMAX technology


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WiMAX technology

  2. 2. Division of Computer Engineering School of Engineering Cochin University of Science & Technology Kochi-682022 CERTIFICATE Certified that this is a bonafide record of the seminar work titled WiMAX Technology Done by Atul Kumar of VII semester Computer Science & Engineering in the year 2010 in partial fulfillment of the requirements for the award of Degree of Bachelor of Technology in Computer Science & Engineering of Cochin University of Science & Technology Dr.David Peter S Head of the Division Mr. Pramod Pavithran Seminar Guide
  3. 3. ACKNOWLEDGEMENT I consider it as a great privilege to express my heartfelt gratitude to many respected personalities who guided, inspired and helped me in successful completion of this seminar. I also express my gratitude to my seminar guide Mr. Pramod Pavithran, Reader of Division of Computer Engineering and Mr. Sudheep Elayidom M, seminar coordinator for providing me with adequate facilities, ways and means by which I was able to complete this seminar. I express my sincere gratitude for his constant support and valuable suggestions without which the successful completion of this seminar would not have been possible. I express my immense pleasure and thankfulness to all the teachers and staff of the Division of Computer Engineering, CUSAT for their co-operation and support. Last but not the least, we thank all others, and especially our classmates who in one way or another helped me in the successful completion of this seminar. ATUL KUMAR Reg. No.-12080017 CS-A, S7
  4. 4. ABSTRACT Imagine a single wireless technology that can: • make portable Internet a reality by extending public WLAN hotspots to metropolitan area coverage for mobile data-centric service delivery, • connect enterprises and residential users in urban and suburban environments where access to copper plant is difficult, • bridge the digital divide by delivering broadband in low-density areas. Thanks to its innovative technology, WiMAX will offer broadband wireless access at data rates of multiple Mbit/s to the end-user and within a range of several kilometers. The same radio technology will also offer high-speed data services to all nomadic terminals (laptops, PDAs, etc.) with an optimized trade off between throughput and coverage. Ultimately it will enable the "Portable Internet" usage replicating on the move the same user experience as at home or at the office. Given its huge benefits, WiMAX will develop as a powerful radio access solution with many integration synergies in mobile or fixed network architecture. WiMAX will also enable end-users to benefit from an "Always Best Connected" experience when accessing their applications via the best available network, at home, on the pause, or on the move. WiMAX particularly fits in Alcatel's vision for a User-Centric Broadband World in full complementarity with the other broadband access technologies: from ADSL to UMTS and their evolutions towards higher speed and data efficiency ii
  5. 5. Table of Contents Chapter Title No. Page No. 1 Introduction 1 2 What is Wimax? 2 2.1 Standards associated with Wimax 3 Why Wimax? 8 3 4 Wimax Technology 9 4.1 Technological Features 9 4.2 Technology Wimax Design 11 4.3 Types of Wimax 13 5 Wimax Technology Challenge 15 6 7 Enhancements in Wimax Wimax a complement to fixed and mobile access 18 22 8 Wimax spectrum and regulation issues 26 9 Wimax services 31 10 Relationship with different wireless technolies 34 11 Wimax in INDIA 35 12 Conclusion 39 13 References 40
  6. 6. List of figures Sl. Images No. Page No. 2.1 Wireless Standards 3 2.2 Types of 802.16 4 3.1 Data Rates 7 4.1 Radio Access Requirements 9 4.2 Wimax Tower 13 6.1 OFDM 18 9.1 Services 1 31 9.2 Services 2 33
  7. 7. WIMAX      CHAPTER 1 INTRODUCTION Broadband Wireless Access (BWA) has been serving enterprises and operators for years, to the great satisfaction of its users. However, the new IP-based standard developed by the IEEE 802.16 is likely to accelerate adoption of the technology. It will expand the scope of usage thanks to: the possibility of operating in licensed and unlicensed frequency bands, unique performance under Non-Line-of-Sight (NLOS) conditions, Quality of Service (QoS) awareness, extension to nomadicity, and more. In parallel, the WiMAX forum, backed by industry leaders, will encourage the widespread adoption of broadband wireless access by establishing a brand forthe technology and pushing interoperability between products. The purpose of this White Paper is to highlight and assess the value of WiMAX as the right solution to: • extend the currently limited coverage of public WLAN (hotspots) to citywide coverage (hot zones) - the same technology being usable at home and on the move, • blanket metropolitan areas for mobile data-centric service delivery, • offer fixed broadband access in urban and suburban areas where copper quality is poor or unbundling difficult, • bridge the digital divide in low-density areas where technical and economic factors make broadband deployment very challenging. In addition to these uses, this paper will highlight other potential applications, such as telephony or an effective point-to multipoint backhauling solution for operators or enterprises.   Division of Computer Engineering                                                                                         1          
  8. 8. WIMAX      CHAPTER 2 WHAT IS WIMAX? WiMAX is a standards-based technology enabling the delivery of last mile wireless broadband access as an alternative to wired broadband like cable and DSL. WiMAX provides fixed , nomadic, portable and, soon, mobile wireless broadband connectivity without the need for direct line-of-sight with a base station. In a typical cell radius deployment of three to ten kilometers, WiMAX Forum Certified™ systems can be expected to deliver capacity of up to 40 Mbps per channel, for fixed and portable access applications. This is enough bandwidth to simultaneously support hundreds of businesses with T-1 speed connectivity and thousands of residences with DSL speed connectivity. Mobile network deployments are expected to provide up to 15 Mbps of capacity within a typical cell radius deployment of up to three kilometers. It is expected that WiMAX technology will be incorporated in notebook computers and PDAs by 2007, allowing for urban areas and cities to become "metro zones" for portable outdoor broadband wireless access. USES: The bandwidth and range of WiMAX make it suitable for the following potential applications: • Connecting Wi-Fi hotspots with other parts of the Int • Providing a wireless alternative to cable and DSL for "last mile” broadband access. • Providing data and telecommunications services.   Division of Computer Engineering                                                                                         2          
  9. 9. WIMAX    •   Providing a source of Internet connectivity as part of a business continuity plan. That is, if a business has a fixed and a wireless Internet connection, especially from unrelated providers, they are unlikely to be affected by the same service outage.   Division of Computer Engineering                                                                                         3          
  10. 10. WIMAX      2.1 Standards Associated With Wimax 2.1 Wireless Standards IEEE 802 refers to a family of IEEE standards dealing with local area networks and metropolitan area networks. More specifically, the IEEE 802 standards are restricted to networks carrying variable-size packets. (By contrast, in cell-based networks data is transmitted in short, uniformly sized units called cells. Isochronous networks, where data is transmitted as a steady stream of octets, or groups of octets, at regular time intervals, are also out of the scope of this standard.) The number 802 was simply the next free number IEEE could assign, though “802” is sometimes associated with the date the first meeting was held — February 1980. IEEE 802.16 : The IEEE 802.16 Working Group on Broadband Wireless Access Standards, which was established by IEEE Standards Board in 1999, aims to prepare formal specifications for the global deployment of broadband Wireless Metropolitan Area Networks. The Workgroup is a unit of the IEEE 802 LAN/MAN   Division of Computer Engineering                                                                                         4          
  11. 11. WIMAX    Standards Committee. A related future technology Mobile Broadband Wireless   Access (MBWA) is under development in IEEE 802.20. Although the 802.16 family of standards is officially called Wireless MAN, it has been dubbed “WiMAX” (from "Worldwide Interoperability for Microwave Access") by an industry group called the WiMAX Forum. The mission of the Forum is to promote and certify compatibility and interoperability of broadband wireless products. 2.2 Types of 802.16 • In January 2003, the IEEE approved 802.16a as an amendment to IEEE 802.16-2001, defining (Near) Line-Of- Sight capability. • In July 2004, IEEE 802.16REVd, now published under the name IEEE 802.16-2004,introduces support for indoor CPE (NLOS) through additional radio capabilities such as antenna beam forming and OFDM sub-channeling. • Early 2005, an IEEE 802.16e variant will introduce support for mobility.   Division of Computer Engineering                                                                                         5          
  12. 12. WIMAX      See Figure 2.2 for the applications associated with each of these standards The WiMAX Forum intends to do for 802.16 what the Wi-Fi Alliance did for 802.11: • harmonize standards and certify interoperability between equipment from different vendors. Standardized interoperable solutions will result in mass mass volume and bring down cost • promote and establish a brand for the technology WiMAX, the reality beyond the hype As mentioned above, WiMAX can offer very high data rates and extended coverage. However, •75 Mbit/s capacity for the base station is achievable with a 20 MHz channel in bestpropagation conditions. But regulators will often allow only smaller channels (10 MHz orless) reducing the maximum bandwidth. • Even though 50 km is achievable under optimal conditions and with a reduced data rate (a few Mbit/s), the typical coverage will be around 5 km with indoor CPE (NLOS) and around 15 km with a CPE connected to an external antenna(LOS).   Division of Computer Engineering                                                                                         6          
  13. 13. WIMAX      CHAPTER 3 WHY WIMAX? WiMAX stands for wireless interoperatibility for microwave access. WiMAX is expected to do more for Metropolitan Area Networks (MANs) and what Wi-Fi has done for local area networks (LANs)? WiMAX is not projected to replace Wi-Fi, but to complement it by connecting Wi-Fi networks to each other or the Internet through high-speed wireless links. You can therefore use WiMAX technology to extend the power and range of Wi-Fi and cellular networks. However, in developing countries, WiMAX may become the only wireless technology because Wi-Fi and cellular have not penetrated areas that can be reached with WiMAX technology. Range The wide range of the WiMAX technology depends on the height of the antennas, if they are installed at the suitable position from where there is no barrier between the transmitter and receiver, and then we can get better range and service from it. Even though the frequency for operation of WiMAX is not definite, the most likely band at 3.5GHz is higher in frequency than the 3G bands at around 2.1 GHz. Range will, as a result, be lower, perhaps somewhere between 50% and 75% of the range of 3G. WiMAX can therefore support 30 to 50 kilometres distance with Line-of-Sight (LOS) links. As far as Non-line-of-sight (NLOS) links in concerned WiMAX can support the broad range from 3 to 10 kilometres using advanced modulation algorithm that can overcome many interfering objects that Wi-Fi systems cannot pass through. Data Rates The technology used for WiMAX is Orthogonal Frequency Division Multiplexing (OFDM), it is not appreciably more supernaturally efficient then the technology   Division of Computer Engineering                                                                                         7          
  14. 14. WIMAX    commonly used for 3G that is Wideband Code Division Multiple Access   (WCDMA). However OFDM is coupled with a high channel bandwidth, that allows greater data rates. So, on average, for an equivalent spectrum allocation, users will see similar data rates. In specific simulations, where there are few users, it is possible that WiMAX will provide a higher data rate than 3G. However, in commercial systems, such simulations are likely rare. 3.1 DATA RATES Timing It is normally believed that WiMAX will enter into the market some five years after 3G is well established. This drawback in time is likely to be important since without a convincing advantage only a few service providers will choose to move from 3G to WiMAX. However, those yet to deploy a system may find the choice balanced between the two technologies. Cost The network costs of WiMAX will be likely to be higher than for 3G because of the reduced range and hence the necessity to build more cells. The subscriber subsidy   Division of Computer Engineering                                                                                         8          
  15. 15. WIMAX    costs may be lower if WiMAX is built into processor chips, although this may not   apply if users wish to have WiMAX handsets. Quality of Service (QoS) Excellent Quality Of service management donates from variety of WiMAX features. Just as on a Wi-Fi network, WiMAX users share a data pipe and QoS can degrade as more users are added to the network. Using the QoS features of WiMAX service providers can guarantee certain users specific bandwidth amounts by limiting the bandwidth consumption of other users. Grant request mechanism for accessing to network is the first aspect of Quality of Service. The WiMAX functioning of disagreement allocates only a fixed amount of time to be given to these grant requests. Disagreement refers to the act of competing for access to the network. Because of the limited amount of time available, bandwidth cannot be consumed by contention requests. When a disagreement request comes into the network, the system compares the request with a service level agreement for the user making the request, and they are granted, or denied, access accordingly. Link by link modulation schemes is another benefit of WiMAX Quality of Service. In other words, the base station can use different modulation schemes for different links. The modulation scheme used is related directly to the distance of the link. Rather than all users' links being downgraded by the user farthest away, link by link modulation enables closer users to use higher data-rate modulation schemes   Division of Computer Engineering                                                                                         9          
  16. 16. WIMAX      CHAPTER 4 WiMAX technology 4.1 Technological features Various advanced technologies will be developed to meet services above and consequently WiMAX will support seamless mobility and technologies such as the technique for minimized power consumption of the terminal, fast link adaptation, and efficient MAC for broadband services will be developed for high data rate transmission in mobile environments. 4.1 RADIO ACCESS REQUIREMENS For the phase I standardization, PG302 decided several system parameters and Radio access requirements. Major system parameters include duplex scheme (TDD) and multiple access (OFDMA) and Channel bandwidth (10MHz) as well. Any   Division of Computer Engineering                                                                                         10          
  17. 17. WIMAX    detailed contents could be shown in Table 2. For the radio access requirements,   some parameters have been determined as follows: • Frequency reuse factor is set as 1. • Maximum guaranteed speed of user is 60 Km/h. • Radius of service coverage can be a few Km. • Maximum of spectral efficiency should be 6 bits/Hz/cell for downlink and 2 bits/Hz/cell for uplink, but the averages are 2 bits/Hz/cell for downlink and 1 bits/Hz/cell for uplink. • Handoff latency should be less than 150 ms. • Throughout per user should be 0.512 to 3 Mbps for downlink and 0.128 to 1 Mbps for uplink. Table 4.1 shows the development contents in association with system requirement. Requirements could be induced by consideration on radio access requirements Table 4.1 Deployment contents corresponding with system requirements System Requirements Deployment contents TDD to minimize required guard band High spectrum efficiency 10 MHz broadband/OFDMA   Division of Computer Engineering                                                                                         11          
  18. 18. WIMAX      To use AMC(Adaptive Modulation and Coding) supporting 64 QAM modulation with turbo code Supporting frequency reuse factor ‘1’ Using Reed Solomon sequence based subchannel to minimize other RASs interference Supporting wide coverage In the cell edge with band SINR area, the operation guaranteed with low rate FEC Supporting safety channel in order to reduce interference of the cell edge area Employing H-ARQ to enhanced link performance Guaranteeing mobility up to 60 km/h speed Supporting mobility Short OFDM symbol length can minimize the degradation due to the mobility. The pilot structure supporting channel estimation under mobility. Employing variable duty rates of TDD DL/UL Flexible resource allocation 1:1, 2:1, 5:1 DL/UL ratios are available for multiple subscriber To support multiple subscriber scheduling algorithm, management of the status of individual terminals and packet scheduling algorithm are considered   Division of Computer Engineering                                                                                         12          
  19. 19. WIMAX      Supporting various QoS Best effort/Real-time polling/Non-real-time polling Handheld support Supporting sleep mode to reduce terminal power consumption TDD Smart (optional feature) Antenna To apply the Smart Antenna for low mobility user 4.2 Technology: WiMAX Design The design of the WiMAX is ideal for challenges related with earlier versions of wired and wireless access networks. At the same time the backhaul connects the WiMAX system to the network, it is not an integrated part of WiMAX system. Normally a WiMAX network consists of two parts, a WiMAX Base Station (BS) and a WiMAX receiver also referred as Customer Premise Equipment (CPE). Backhaul Backhaul is actually a connection system from the Access Point (AP) back to the provider and to the connection from the provider to the network. A backhaul can set out any technology and media provided; it connects the system to the backbone. In most of the WiMAX deployments circumstances, it is also possible to connect several base stations with one another by use of high speed backhaul microware links. This would also allow for roaming by a WiMAX subscriber from one base station coverage area to another, similar to roaming enabled by cellular phone   Division of Computer Engineering                                                                                         13          
  20. 20. WIMAX      Receiver A WiMAX receiver, which is also referred as Customer Premise Equipment (CPE), may have a separate antenna or could be a stand-alone box or a PCMCIA card that inserted in a laptop or a desktop computer. Access to a WiMAX base station is similar to accessing a wireless access point (AP) in a Wi-Fi network, but the coverage is more. So far one of the biggest restrictions to the widespread acceptance of WiMAX has been the cost of CPE. This is not only the cost of CPE itself, but also that of installation. In the past, Broadband Wireless Access (BWA) have been predominantly Line Of Sight (LOS), requiring highly skilled labour and a truck role to install and provide a service to customer. The concept of a self-installed CPE has been difficult for BWA from the beginning, but with the advent of WiMAX, this issue seems to be getting resolvedBase Station (BS) A WiMAX base station comprises of internal devices and a WiMAX tower. A base station can normally covers the area of about 50 kilometres or 30 miles radius, but some other and environmental issues bound the limits of WiMAX range to 10 km or 6 miles. Any wireless user within the coverage area would be able to access the WiMAX services (Fig: 2). The WiMAX base stations would use the media access control layer defines in the standard and would allocate uplink and downlink bandwidth to subscribers according to their requirements on real time basis.   Division of Computer Engineering                                                                                         14          
  21. 21. WIMAX      4.2 WIMAX TOWER 4.3 Types of WiMAX The WiMAX family of standards concentrate on two types of usage models a fixed usage model and a mobile usage model. The basic element that differentiates these systems is the ground speed at which the systems are designed to manage. Based on mobility, wireless access systems are designed to operate on the move without any disruption of service; wireless access can be divided into three classes; stationary, pedestrian and vehicular. A mobile wireless access system is one that can address the vehicular class, whereas the fixed serves the stationary and pedestrian classes. This raises a question about the nomadic wireless access system, which is referred to as a system that works as a fixed wireless access system but can change its location   Division of Computer Engineering                                                                                         15          
  22. 22. WIMAX      Fixed WiMAX Service and consumer usage of WiMAX for fixed access is expected to reflect that of fixed wire-line service, with many of the standards-based requirements being confined to the air interface. Because communications takes place via wireless links from Customer Premise Equipment (CPE) to a remote Non Line-of-sight (NLOS) base station, requirements for link security are greater than those needed for a wireless service. The security mechanisms within the IEEE 802.16 standards are sufficient for fixed access service. Another challenge for the fixed access air interface is the need to set up high performance radio links capable of data rates comparable to wired broadband service, using equipment that can be self installed indoors by users, as is the case for Digital Subscriber Line (DSL) and cable modems. IEEE 802.16 standards provide advanced physical (PHY) layer techniques to achieve link margins capable of supporting high throughput in NLOS environments. Mobile WiMAX The 802.16a extension, refined in January 2003, uses a lower frequency of 2 to 11 GHz, enabling NLOS connections. The latest 802.16e task group is capitalizing on the new capabilities this provides by working on developing a specification to enable mobile WiMAX clients. These clients will be able to hand off between WiMAX base stations, enabling users to roam between service areas.   Division of Computer Engineering                                                                                         16          
  23. 23. WIMAX      CHAPTER 5 WIMAX TECHNOLOGIES CHALLENGE WiMAX, more flexibility and security Unlike WLAN, WiMAX provides a media access control (MAC) layer that uses a grant-request mechanism to authorize the exchange of data. This feature allows better exploitation of the radio resources, in particular with smart antennas, and independent management of the traffic of every user. This simplifies the support of real-time and voice applications. One of the inhibitors to widespread deployment of WLAN was the poor security feature of the first releases. WiMAX proposes the full range of security features to ensure secured data exchange: • terminal authentication by exchanging certificates to prevent rogue devices, • user authentication using the Extensible Authentication Protocol (EAP), • data encryption using the Data Encryption Standard (DES) or Advanced Encryption Standard (AES), both much more robust than the Wireless Equivalent Privacy (WEP) initially used by WLAN. Furthermore, each service is encrypted with its own security association and private keys. WiMAX, a very efficient radio solution WiMAX must be able to provide a reliable service over long distances to customers using indoor terminals or PC cards (like today's WLAN cards). These requirements, with limited transmit power to comply with health requirements, will limit the link budget. Subchannelling in uplink and smart antennas at the base station has to overcome these constraints. The WiMAX system relies on a new radio physical   Division of Computer Engineering                                                                                         17          
  24. 24. WIMAX    (PHY) layer and appropriate MAC layer to support all demands driven by the target   applications. The PHY layer modulation is based on OFDMA, in combination with a centralized MAC layer for optimized resource allocation and support of QoS for different types of services (VoIP, real-time and non real-time services, best effort). The OFDMA PHY layer is well adapted to the NLOS propagation environment in the 2 - 11 GHz frequency range. It isinherently robust when it comes to handling the significant delay spread caused by the typical NLOS reflections. Together with adaptive modulation, which is applied to each subscriber individually according to the radio channel capability, OFDMA can provide a high spectral efficiency of about 3 - 4 bit/s/Hz. However, in contrast to single carrier modulation, the OFDMA signal has an increased peak: average ratio and increased frequency accuracy requirements. Therefore, selection of appropriate power amplifiers and frequency recovery concepts are crucial. WiMAX provides flexibility in terms of channelization, carrier frequency, and duplex mode (TDD and FDD) to meet a variety of requirements for available spectrum resources and targeted services. An important and very challenging function of the WiMAX system is the support of various advancedantenna techniques, which are essential to provide high spectral efficiency, capacity, system performance, and reliability: • beam forming using smart antennas provides additional gain to bridge long distances or to increase indoor coverage; it reduces inter-cell interference and improves frequency reuse, • transmit diversity and MIMO techniques using multiple antennas take advantage of multipath reflections to improve reliability and capacity. WiMAX technology can provide coverage in both LOS and NLOS conditions. NLOS has many implementation advantages that enable operators to deliver broadband data to a wide range of customers. WiMAX technology has many advantages that allow it to provide NLOS solutions, with essential features such as OFDM technology, adaptive modulation and error correction. Furthermore, WiMAX has many optional features, such as ARQ, sub-channeling, diversity, and   Division of Computer Engineering                                                                                         18          
  25. 25. WIMAX    space-time coding that will prove invaluable to operators wishing to provide quality   and performance that rivals wireline technology. For the first time, broadband wireless operators will be able to deploy standardized equipment with the right balance of cost and performance; choosing the appropriate set of features for their particular business model. System performance Table 5.1 gives typical cell size and throughput at 3.5 GHz in various configuration and environments. Environment Typical cell size Sector throughput Urban indoor (NLOS) 1 km (5/8 miles) 21 Mbit/s w.10MHz 2.5 km (1.5 miles) 22 Mbit/s w.10 MHz 7 km (4 miles) 22 Mbit/s w. 10 MHz 5 km (3 miles) 4.5Mbit/s w.3.5 MHz 15 km (9 miles) 4.5Mbit/s w.3.5MHz channel Suburban indoor (NLOS) channel Suburban outdoor (LOS) channel Rural indoor (NLOS) channel Rural outdoor (LOS) channel 5.1 Typical Cell Size and Throughput   Division of Computer Engineering                                                                                         19          
  26. 26. WIMAX      6 ENHANCEMENTS IN WIMAX OFDM OFDM stands for Orthogonal Frequency Division Multiplexing; it’s a technology that provides the operator to beat the challenges of Non-Line-of-Sight (NLOS) transmission in the more efficient manner. OFDM waveform put forward the advantage of functioning with the larger delay spread of the NLOS background. With the excellent quality of OFDM functionality, time and use of a cyclic prefix and its also removes the Inter Symbol Interference (ISI) complications of adaptive equalization. Multiple narrowband orthogonal carriers composed because of OFDM waveform, localizing selective fading to a subset of carriers that are comparatively simple to equalize. A comparison between an OFDM signal and a single carrier signal, with the information being sent in parallel for OFDM and in series for single carrier are shown in Fig: 6.1 (WiMAX Forum) 6.1 OFDM   Division of Computer Engineering                                                                                         20          
  27. 27. WIMAX    The facility to remove delay spread, Inter Symbol Interference (ISI) and multi-path   in a proficient manner allows for higher data rate throughput. It is simpler to equalize the individual OFDM carriers than it is to equalize the broader single carrier signal. For these entire reasons modern international standard such as those set by IEEE 802.16, have created OFDM as the ideal technology. Antennas For Fixed WiMAX Applications Directional antennas enhance the fade margin by adding together extra gain. This increases the link accessibility comparisons between directional and Omnidirectional antennas. Delay spread is further reduced by directional antennas at both the Base Station and Customer Premise Equipment (CPE). The antenna pattern restrains any multi-path signals that appear in the side lobes and back lobes. The efficiency of these methods has been verified and demonstrated in booming deployments, in which the service operates under considerable NLOS fading. Adaptive Modulation WiMAX system supports adaptive modulation to regulate the Signal Modulation Scheme (SMC) depending on the Signal to Noise Ratio (SNR) state of the radio link. When the radio link is soaring in quality, the peak modulation scheme is used, offering the system additional capacity. During a signal fade, the WiMAX system can move to a lower modulation scheme to keep the connection quality and link permanence. This element allows the system to overcome time-selective fading. The key element of adaptive modulation is that it enhances the range that a higher modulation scheme can be used over, because the system can bend to the actual fading circumstances, as opposed to having a fixed scheme that is planned for the worst case situations.   Division of Computer Engineering                                                                                         21          
  28. 28. WIMAX      WiMAX & IMT-Advanced IMT-Advanced, also known as “systems beyond IMT-2000” is expected to offer constant higher data rates with high mobility to assure likely growing need for mobile WiMAX services that goes beyond what IMT-2000 can afford to provide. IMT- Advanced is awaiting technology that will require 3 to 5 years in the future with target maximum data rates, for research and examination, of up to 100 Mbits/sec in high mobility applications and up to 1 Gbit/sec in low mobility or nomadic applications. The capacity expected by IMT-Advanced is often referred to as 4G. It is commonly acknowledged that Orthogonal Frequency Division Multiple Access (OFDMA) technology will be integrated in IMT-Advanced in near future to get more the maximum benefits from the WiMAX. “IMT-Advanced is a continuing effort. The full criteria, being extended within ITUR Working Party 8F, are not expected until 2008. The specification of IMTAdvanced technologies will probably not be completed until at least 2010. In preparation for IMT-Advanced, the IEEE 802.16 Working Group has moved to initiate a new project designated as “802.16m” with the intent of developing enhancements to IEEE STD 802.16 to ensure suitability as an IMT-Advanced proposal”. Power Control Algorithms of power control are applied to enhance the general performance of the system, it is deployed by the base station sending power control information to every Customer Premise Equipments (CPEs) to control the transmit power level so that the level inward bound at the base station is at a fixed level. In a dynamical changing fading environment this pre-determined performance level indicates that the CPE only broadcasts sufficient power to meet this constraint. The communication would be that the CPE broadcast level is supported on worst case circumstances. The power control decreases the general power consumption of the CPE and the possible interference with other base stations. For Line-of-Sight (LOS)   Division of Computer Engineering                                                                                         22          
  29. 29. WIMAX    the transmission power of the CPE is approximately comparative to its distance   from the base station, for Non-Line-Of-Sight (NLOS) it is also closely dependant on the clearance and barriers. Error Detection Techniques WiMAX have built-in error detection techniques to reduce the system Signal to Noise Ratio (SNR) obligations. Convolutional Encoding, Strong Reed Solomon FEC, and interleaving algorithms are used to identify and correct errors to enhance throughput. These strong error correction techniques assist to recover corrupted frames that may have been missing due to frequency selective fading or burst errors. To remove the errors, Automatic Repeat Request (ARQ) is used that cannot be corrected by the FEC by resending the error-ed information again. This notably improves the Bit Error Rate (BER) performance for a similar maximum level.   Division of Computer Engineering                                                                                         23          
  30. 30. WIMAX      CHAPTER 7 WIMAX A COMPLEMENT TO A FIXED & MOBILE ACCESS WiMAX integrates perfectly into existing fixed and mobile networks, complementing them when needed. This section gives a more detailed analysis of WiMAX integration into fixed and the mobile markets. WiMAX for fixed wireless access Nationwide broadband access has become a priority in many countries. In most developed countries, the average broadband coverage will reach 90% in the coming years. Still, in some rural areas of such countries, broadband coverage will not exceed 50%.The service gap can be categorized by two characteristics: the type of area (rural or urban) and the level of national development (see Table 1). In developed countries, DSL service deployment has been massive in urban and suburban deployments, whereas coverage of remote areas - smaller towns and rural areas - is lagging behind. Hurdles to overcome are the poor line quality of the installed copper base, the large distances to the central offices or cabinets, or the low population density. In this context, WiMAX, with its QoS support, longer reach, and data rates similar to DSL, is naturally positioned as a viable first mile option to offer broadband access to residential users. In emerging countries, the main focus of broadband deployment is on urban and suburbanareas, and will remain so in the near future. The low POTS penetration and the low quality of the copper pair prevent mass scale DSL deployment and foster the need for alternate broadband technologies. In this context, WiMAX is positioned as an excellent option. Moreover, the possibility of offering broadband services in combination with voice services will gradually lead to narrowband WLL   Division of Computer Engineering                                                                                         24          
  31. 31. WIMAX    substitution. Parameters such as availability of the copper, distance to the remote   unit/central office, backhauling costs, and teledensity will drive the choice for one or other of these solutions. For further details, refer to the article "Providing Always-on Broadband Access to Under-served Areas" in the Alcatel Telecommunication Review(Q4 2003). WiMax is of interest for large enterprises with several locations in the same metropolitan area. WiMax will permit Operator's bypass under license conditions: building a metropolitan private network of IP lines at a very low cost (no civil works). The comparison to leased lines rental fee is in favor of Wimax even for two sites only. Deployment topologies Several topology and backhauling options are to be supported on the WiMAX base stations: wireline backhauling (typically over Ethernet), microwave Point-to-Point connection, as well as WiMAX backhaul. See Figure 3. With the latter option, thebase station has the capability to backhaul itself. This can be achieved by reserving part of the bandwidth normally used for the end-user traffic and using it for backhauling purposes. WiMAX for Portable Internet WiMAX, the natural complement to mobile and Wi-Fi networks Mobile networks offer full mobility, nation-wide coverage voice support and moderate data rates. WiMAX can then be positioned as a complementary solution by offering higher bandwidth when required, in particular in dense urban areas. Public WLAN, while offering clear benefits, is limited in coverage and mobility   Division of Computer Engineering                                                                                         25          
  32. 32. WIMAX    capabilities. WiMAX by-passes these limitations and offers broadband connectivity   in larger areas (hotzones). Wi-Fi and WiMAX solutions are also complementary, with Wi-Fi being more adapted for short-range, indoor connections (in particular in the enterprise and at home) and WiMAX for long- range outdoor connections. From nomadicity to Portable Internet While nomadicity offers connectivity within the coverage area of a single base station, Portable Internet implies session continuity throughout the network. In addition a new generation of networks with multi-access (3G, Wi-Fi, WiMAX, DSL, FTTU, etc.) enable end-users to enjoy an "Always Best Connected" experience when accessing their applications via the best available network at home, on the pause, or on the move. See Figure 4. WiMAX becomes an additional radio access solution in the global network architecture. The WiMAX CPE In most case, a simple plug and play terminal, similar to a DSL modem, provides connectivity. For customers located several kilometers from the WiMAX base station, a self-install outdoor antenna may be required to improve transmission quality. To serve isolated customers, a directive antenna pointing to the WiMAX base station may be required. For customers requesting voice in addition to broadband services, specific CPE will allow the connection of standard or VoIP phones. Ultimately, WiMAX chipset will be embedded in data-centric devices. Operator's business case WiMAX is of interest for incumbent, alternate, and mobile operators. Some business cases are possible.   Division of Computer Engineering                                                                                         26          
  33. 33. WIMAX    • The incumbent operators can use the wireless technology as a complement to DSL,   allowing them to offer DSL-like services in remote, lowdensity areas that cannot be served with DSL. • For alternate operators, the wireless technology is the solution for a competitive high-speed Internet with applicability in urban or sub-urban areas. • The larger opportunity will come with the Portable Internet usage, complementing fixed and mobile solution in urban and suburban areas. Therefore it will enhance the business case by giving access to a large potential of end users. WiMAX, the obvious choice for operators By integrating WiMAX into their networks, mobile operators can boost their service with high bandwidth, when necessary, the same applications (messaging, agenda, location-based services, …) being offered on both networks with a single billing and subscriber profile. Mobile operators can also reuse existing radio sites and backhauling equipment to facilitate the deployment of WiMAX. Fixed operators, incumbent or alternate, will offer nomadic and Portable Internet usage as an addition to their fixed access offering to complement their DSL and Wi-Fi bundle. For those having deployed WiMAX for fixed access, this is also a natural evolution of their offering.   Division of Computer Engineering                                                                                         27          
  34. 34. WIMAX      CHAPTER 8 WIMAX SPECTRUM AND REGULATION ISSUES WiMAX-compliant equipment will be allowed to operate in both licensed and unlicensed bands. The minimum channel bandwidth for WiMAX usage is 1.75 MHz per channel, while 10 MHz is considered as an optimum. Although 2.4 GHz and 5 GHz non-licensed bands are largely available, their usage could be limited to trials because of the risks of interference preventing QoS commitments. The 2.5 and 3.5 GHz licensed bands will be the most common bands for WiMAX applications. It should be noted that the 5 GHz band is also partially licensed in some countries. Most countries have already allocated licensed spectrum, generally to alternate operators. Nevertheless large quantities of spectrum are still in process of allocation, and some countries have not even defined any WiMAX licensed bands yet. WiMAX is designed to accommodate either Frequency Division Duplexing (FDD), which is more suited to enterprise traffic, or Time Division Duplexing (TDD), which is more adapted to asymmetrical traffic. Cohabitation of FDD and TDD techniques is possible within the same bands, provided guard bands are implemented. Throughput, Scalability, QoS, and Security Throughput By using a robust modulation scheme, IEEE 802.16 delivers high throughput at long ranges with a highlevel of spectral efficiency that is also tolerant of signal reflections. Dynamic adaptive modulation allows the base station to tradeoff throughput for range. For example, if the base station cannot establish a robust link to a distant subscriber using the highest order modulation scheme, 64 QAM (Quadrature Amplitude Modulation), the modulation order is reduced to 16 QAM or   Division of Computer Engineering                                                                                         28          
  35. 35. WIMAX    QPSK (Quadrature Phase Shift Keying), which reduces throughput and increases   effective range. Scalability To accommodate easy cell planning in both licensed and license-exempt spectrum worldwide, 802.16 supports flexible channel bandwidths. For example, if an operator is assigned 20 MHz of spectrum, that operator could divide it into two sectors of 10 MHz each, or 4 sectors of 5 MHz each. By focusing power on increasingly narrow sectors, the operator can increase the number of users while maintaining good range and throughput. To scale coverage even further, the operator can re-use the same spectrum in two or more sectors by creating proper isolation between base station antennas. Coverage In addition to supporting a robust and dynamic modulation scheme, the IEEE 802.16 standard also supports technologies that increase coverage, including mesh topology and “smart antenna” techniques. As radio technology improves and costs drop, the ability to increase coverage and throughput by using multiple antennas to create “transmit” and/or “receive diversity” will greatly enhance coverage in extreme environments. Quality of Service Voice capability is extremely important, especially in underserved international markets. For this reason the IEEE 802.16a standard includes Quality of Service features that enable services including voice and video that require a low-latency network. The grant/request characteristics of the 802.16 Media Access Controller (MAC) enables an operator to simultaneously provide premium guaranteed levels of service to businesses, such as T1-level service, and high-volume “best-effort”   Division of Computer Engineering                                                                                         29          
  36. 36. WIMAX    service to homes, similar to cable-level service, all within the same base station   service area cell. Security Privacy and encryption features are included in the 802.16 standard to support secure transmissions and provide authentication and data encryption. Benefits of Standards Standards are important for the wireless industry because they enable economies of scale that can bring down the cost of equipment, ensure interoperability, and reduce investment risk for operators. Without industry-wide standards, equipment manufacturers must provide all the hardware and software building blocks and platforms for themselves, including the fundamental silicon, the sub- scriber station, the base station, and the network management software that is used to provision services and remotely manage the subscriber station. With the 802.16 standard in place, suppliers can amortize their research and development costs over much higher product volume. For example, a volume silicon supplier can supply the same standard component to many equipment makers at a far lower cost than would be possible if the device manufacturers were required to develop proprietary silicon for use only by their equipment. Standards also specify minimum performance criteria for equipment, enabling a common broadband wireless access baseline platform that equipment manufacturers can use as the foundation for ongoing innovations and faster time to market. With its broad industry support, the 802.16 standard lets device manufacturers and solutions vendors do what they do best, achieving overall price/performance improvements and opening mass-market opportunities that cannot be equaled by proprietary approaches.   Division of Computer Engineering                                                                                         30          
  37. 37. WIMAX      WiMAX Focuses on Interoperability WiMAX (the Worldwide Interoperability for Microwave Access Forum) is a nonprofit corporation formed by equipment and component suppliers, including Intel Corporation, to promote the adoption of IEEE 802.16 compliant equipment by operators of broadband wireless access systems. The organization is working to facilitate the deployment of broadband wireless networks based on the IEEE 802.16 standard by helping to ensure the compatibility and interoperability of broadband wireless access equipment. In this regard, the philosophy of WiMAX for the wireless MAN is comparable to that of the Wi-Fi* Alliance in promoting the IEEE 802.11 standard for wireless LANs. In an effort to bring interoperability to Broadband Wireless Access, WiMAX is focusing its efforts on establishing a unique subset of baseline features grouped in what is referred to as “System Profiles” that all compliant equipment must satisfy. These profiles will establish a baseline protocol that allows equipment from multiple vendors to interoperate, and that also provides system integrators and service providers with the ability to purchase equipment from more than one supplier. System Profiles can address the regulatory spectrum constraints faced by operators in different geographies. For example, a service provider in Europe1 operating in the 3.5 GHz band who has been allocated 14 MHz of spectrum is likely to want equipment that supports 3.5 and/or 7 MHz channel bandwidths and TDD (time-division duplex) or FDD (frequency-division duplex) operation. Similarly, a WISP in the U.S. using licenseexempt spectrum in the 5.8 GHz UNII band may desire equipment that supports TDD and a 10 MHz bandwidth. WiMAX will establish a structured compliance procedure based upon the proven test methodology specified by ISO/IEC 96462. The process starts with standardized Test Purposes written in English, which are then translated into Standardized Abstract Test Suites in a language called TTCN3. In parallel, the Test Purposes are also used as input to generate test tables referred to as the PICS (Protocol Implementation Conformance Statement) pro forma. The end result is a complete set of test tools that WiMAX will make available to equipment developers   Division of Computer Engineering                                                                                         31          
  38. 38. WIMAX    so they can design in conformance and interoperability during the earliest possible   phase of product development. Typically, this activity will begin when the first integrated prototype becomes available. Ultimately, the WiMAX suite of conformance tests, in conjunction with interoperability events, will enable service providers to choose from multiple vendors of broadband wireless access equipment that conforms to the IEEE 802.16a standard and that is optimized for their unique operating environment. Internationally, WiMAX will work with ETSI, the European Telecommunications Standards Institute, to develop similar test suites for the ETSI HIPERMAN standard for European broadband wireless metropolitan area access. WiMAX has key benefits for operators. By choosing interoperable, standards-based equipment, the operator reduces the risk of deploying broadband wireless access systems. • Economies of scale enabled by the standard help reduce monetary risk. • Operators are not locked in to a single vendor because base stations will interoperate with subscriber stations from different manufacturers • .Ultimately, operators will benefit from lower-cost and higher-performance equipment, as equipment manufacturers rapidly create product innovations based on a common, standards-based platform.   Division of Computer Engineering                                                                                         32          
  39. 39. WIMAX      CHAPTER 9 WIMAX SERVICES Potential services WiMAX services can have potential applications in various fields. Different applications can demand different QoS, which can be classified as follows 1. INTERACTIVE SERVICES : Web Browsing, Game interface,etc 2. STREAMING SERVICES 3. BACK GROUND SERVICES: : VoD ,MPEG ,etc. FTP,E-Mail, SMS, Multicast/Broadcast ,MMS, PUSH TO TALK 9.1 SERVICES 1   Division of Computer Engineering                                                                                         33          
  40. 40. WIMAX    Possible services provided by WiMAX are widespread over various data   communication services including entertainment, information and commerce services. The first round of WiMAX technology is expected to be nomadic, meaning that CPEs will be portable, but not truly mobile. But with Samsung’s new developments on hand-over, the technology may become truly mobile, offering the 20 Mb/s to 30 Mb/s at speeds up to 120 km/h WiMAX enthusiasts are touting. For entertainment services, WiMAX will provide high quality VoD/MoD/AoD, realtime streaming broadcasting, 3G network games and MMS. Web Browsing, file downloading and interactive information services will be provided as information services by WiMAX. Commerce services such as m-commerce, mobile banking, trading will be also provided by WiMAX as well. Table 1 summarizes possible services to be provided by WiMAX. Example of WiMAX Services Application Service type VoD/MoD/AoD QoS class Streaming Realtime-Broadcasting Real Time Entertainment service Network Game Interactive MMS Background Web Browsing Interactive FTP Information service Background Interactive information Interactive m-Commerce Interactive Mobile banking Stock trading Commerce service Interactive Interactive   Division of Computer Engineering                                                                                         34          
  41. 41. WIMAX      Current Service KT offers 18.4Mbit/s/4Mbit/s for $22 a month with unlimited data usage. WiMAX seems faster than HSDPA. There are similar service in U.S. operated by wireless company but much more expensive and slower. Hanaro Telecom have announced a partnership to roll out WiMAX nationwide in Korea, excluding Seoul and six provincial cities, where independent networks will be rolled out.In November 2004, Intel and LG Electronics executives agreed to ensure compatibility between WiMAX and WiMAX technology In September 2005, Samsung Electronics signed a deal with Sprint Nextel Corporation to provide equipment for a WiMAX trial. In November 2005, KT Corporation(aka Korea Telecom) showed off WiMAX trial services during the Asia-Pacific Economic Cooperation (APEC) summit in Busan. 9.2 SERVICES2 February 10th 2006: Telecom Italia, the dominant telephony and internet service provider in Italy, together with Korean Samsung Electronics, has demonstrated to the public a WiMAX network service on the occasion of the 2006 Winter Olympics, held in Turin, with downspeed of 10 Mbit/s and upspeed of some hundreds of kbit/s even in movement up to 120 km/h.   Division of Computer Engineering                                                                                         35          
  42. 42. WIMAX    In the same event Samsung tlc div. president Kitae Lee assured a future of 20-30   Mbit/s by the end of this year (2006) and 100+ Mbit/s down / 1+ Mbit/s up in 2008 KT Corporation launched commercial WiMAX service in mid-2006 as reported Sprint (US), BT (UK), KDDI (JP), and TVA (BR) have or are trialing WiMAX. KT Corporation and SK Telecom launched WiMAX around Seoul on June 30, 2006. More about the KT launch.On April 3, 2007, KT launched WiMAX coverage for all areas of Seoul including all subway lines.   Division of Computer Engineering                                                                                         36          
  43. 43. WIMAX      CHAPTER 10 RELATIONSHIP WITH DIFFERENT WIRELESS TECHNOLOGIES 3G Wi-Fi WiMax Mobile-Fi 802.11 802.16 802.20 54 Mbps 100 Mbps 16 Mbps 50 miles Several miles Max Speed 2 Mbps Coverage Several miles 300 feet Airwave Licensed Unlicensed Either Licensed Advantage Range Speed Speed Speed ,mobility ,price ,range ,mobility Disadvantagges Slow ,expensive Short range Interference High price issues?   Division of Computer Engineering                                                                                         37          
  44. 44. WIMAX      CHAPTER 11 WIMAX IN INDIA Overview: Widespread, Affordable Connectivity Connectivity is vital to Indian business and society. Globalization and the Internet have created rapid growth in information technology-related businesses in India. Although only half a percent of the Indian population has residential Internet access (4.7 million out of 1 billion people), India’s more than 9,000 Internet cafes can be seen bustling with people everywhere in the Indian cities.These Internet services provide a means for people to stay connected with their friends and family through email, audio or video chat, and to browse the Internet for job and academic opportunities. While Indians are enthusiastic about the Internet, the lack of physical connectivity or telecommunications infrastructure and the cost and lack of broadband technologies are a big hindrance to more widespread adoption of the Internet. In fact, 14 percent of India’s 0.6 million villages still do not have a single public telephone. But wireless technologies are beginning to offer reliable alternatives to fixed-line access, offering the potential for widespread, affordable connectivity to every region, village, and person in India. The Promise of Wireless Internet Access India is increasingly embracing wireless technologies. Cellular phones based on various wireless technologies have revolutionized telecommunications in India. As the growth of fixed-line subscribers has slowed over the past several years, cellular usage has skyrocketed, nearly doubling in 2003 and growing by 159 percent so far in 2004, with 1.4 million new subscribers every month. But these cellular technologies have not delivered broadband data connectivity to the households, due to both cost and complexity. Yet India needs a way to provide widespread Internet access, access that can usher in economic growth, better education and healthcare and improved   Division of Computer Engineering                                                                                         38          
  45. 45. WIMAX    entertainment services as it has done elsewhere in the world. And the solution must   be wireless, to avoid the overwhelming cost and resources that would be required to deploy countrywide fixed-line broadband Internet infrastructure.With widespread wireless broadband facilities, the Indian information technology (IT) industry could grow beyond a few cities, students in rural areas could videoconference with educators across the country, and entertainment programs could be telecast to remote areas along with Internet telephony services, using technologies like Voice over Internet Protocol (VoIP). Improved communications could bring remote villages into the world economy, information access could speed worker productivity, and faster communication between producers and suppliers could fuel demand for Indian products. Improved Education, Health Care and Entertainment With higher bandwidth and faster speeds, broadband Internet can make education more accessible by delivering interactive distance education at a low cost. TRAI reports that in Korea, the government provided training on PC and Internet usage for low-income and disabled households with children. They also launched programs to provide these families with heavily subsidized and sometimes free PCs. Over 55 percent of all educational documents are electronic at this point. Teachers in schools have access to their own PCs with Internet connections, and are required to leverage information and communication technologies as an integral part of their curriculum.5 In India, schools and libraries in rural or remote areas without wired infrastructure or broadband services can be costeffectively connected to broadband using WiMAX. Video conferencing tools can help students to study a variety of subjects with educators who may not be able to commute to remote areas. Lecture classes from urban schools and top universities can be broadcast to rural students, and the students could use the broadband facilities of WiMAX for communicating with teachers and with their remote classmates. The Indira Gandhi National Open University (IGNOU) is already encouraging state governments and conventional universities to establish distance learning programs, providing financial support and grants for programs and   Division of Computer Engineering                                                                                         39          
  46. 46. WIMAX    facilitating development of multimedia materials for delivery through distance   learning programs,6 Other premier institutions such as the Birla Institute of Technology and Science (BITS), Pilani, are already offering distance learning programs through relationships with industry and development agencies. BITS conducts off-campus degree programs as a means of continuing education for employed professionals as part of the human resource development programs of specific organizations at various off-campus centers.” BITS offerings include degree programs in math, science and engineering, computer science, medical and healthcare and other fields. 7 Extensive and reliable broadband Internet can help these Internet-based quality distance education reach more people across the nation. Agriculture and health care can also benefit from broadband services. High-resolution pictures or real-time images of crop diseases can be transmitted to agricultural experts in a different geographic location for immediate expert advice, thus containing the crop diseases faster. Similarly, doctors can use real-time video conferencing to discuss patient symptoms with faraway experts, thus providing faster and better care to the patients. 802.16 Driving Down Costs LaBrecque estimates that there are over 2,400 wireless Internet service providers (ISPs) in the United States, serving over 6,000 markets (ISP-Market, LLC Broadband Wireless Access 2002). But they use expensive, proprietary equipment that's not interoperable with equipment from other vendors. A lack of standards has also limited the usefulness of the technology and made it hard for wireless broadband access providers to be competitive and profitable. To combat these issues the 802.16 standard was conceived. 802.16 will provide definitive standards for a carrier-class solution that can scale to support thousands of users with a single base station and provide differentiated service levels. For example, a single base station sector can provide enough data rate to simultaneously support more than 60 businesses with T1type connectivity and hundreds of homes with DSL-type connectivity.   Division of Computer Engineering                                                                                         40          
  47. 47. WIMAX    The benefits of 802.16 are many: by enabling standards-based products with fewer   variants and larger volume production, it will drive the cost of equipment down, and having standardized equipment will also encourage competition, making it possible to buy from many sources. For areas poorly served by a wired infrastructure, including many developing countries, 802.16 will be important both for its ease of implementation and its low cost The Future of WiMAX The IEEE 802.16 standard body members are working toward incremental evolution, from fixed operation to portability and mobility. The IEEE 802.16e amendment will amend the base specification to enable not just fixed, but also portable and mobile operation. IEEE 802.16f and IEEE 802.16g task groups are addressing the management interfaces for fixed and mobile operation. Clients will be able to hand-off between 802.16 base stations, enabling users to roam between service areas. In a fully mobile scenario users may be moving while simultaneously engaging in a broadband data access or multimedia streaming session. All of these improvements will help make WiMAX an even better Internet access solution for growing economies like that of India.   Division of Computer Engineering                                                                                         41          
  48. 48. WIMAX      CHAPTER 12 CONCLUSION The latest developments in the IEEE 802.16 group are driving a broadband wireless access (r) evolution thanks to a standard with unique technical characteristics. In parallel, the WiMAX forum, backed by industry leaders, helps the widespread adoption of broadband wireless access by establishing a brand for the technology. Initially, WiMAX will bridge the digital divide and thanks to competitive equipment prices, the scope of WiMAX deployment will broaden to cover markets where the low POTS penetration, high DSL unbundling costs, or poor copper quality have acted as a brake on extensive high-speed Internet and voice over broadband. WiMAX will reach its peak by making Portable Internet a reality. When WiMAX chipsets are integrated into laptops and other portable devices, it will provide highspeed data services on the move, extending today's limited coverage of public WLAN to metropolitan areas. Integrated into new generation networks with seamless roaming between various accesses, it will enable end users to enjoy an "Always Best Connected" experience. The combination of these capabilities makes WiMAX attractive for a wide diversity of people: fixed operators, mobile operators and wireless ISPs, but also for many vertical markets and local authorities. Alcatel, the worldwide broadband market leader with a market share in excess of 37%, is committed to offer complete support across the entire investment and operational cycle required for successful deployment of WiMAX services   Division of Computer Engineering                                                                                         42          
  49. 49. WIMAX      CHAPTER 13 REFERENCES 1) www.ewh.ieee.org/r4/chicago/Yu-WiMAX.pdf 2) http://computer.howstuffworks.com/wimax.htm 3) www.wimaxforum.org 4) http://standards.ieee.org/catalog/olis/lanman.html   Division of Computer Engineering                                                                                         43