WiMAX Limtations - WiMAX Deployment Limitations

A general perception for WiMAX is that it delivers high speed data that is 70 Mbps 50 kilometers, but in factual situation WiMAX do some thing different. It increase Bit error rate if it operates at 50 kilometers, that’s why it important to use lower bitrates. If the range is low it helps in operating at higher bitrates.

As we know, there are majorly two types of WiMAX, fixed WiMax and Mobile WiMax, in fixed WiMAX network higher gain directional antenna is installed near the subscriber location which helps in increasing signal strengths, better data rate and throughput. However mobile networks are designed for indoors, it uses customer premises equipment (CPE) which is attached with computers and laptops or other WiMax products.

In mobile WiMax Omni directional antennas are used, which have lower-gain when compared to directional antenna; directional antennas are easy to use as they portable. 10 Mbps speed can be achieved within 10 km range if portable mobile WiMAX CPE used in line-of-sight. In contrast to this 10 Mbps speed can be delivered to only 2 km in urban areas as it is not possible to keep antenna on line-of-sight.

In current situation fixed WiMax throughputs 2Mbps at 10 km using high gain antenna. Higher gain directional antenna can be used with Mobile WiMax networks with good range and throughput but in result loose mobility.

As in all wireless or wired networks, the given bandwidth is divided among the users, it is same in WiMax also, available bandwidth is divided among the users in certain radio sector, and performance of the network can drop in case of many users in give sector. To improve the performance in this situation more radio cards are required to be installed in the base station for give sector.

Because of this varying performance of WiMax networks, lots architectures are incorporated into WiMax by independent development and within the 802.16j mobile multi-hop relay (MMR) task group.

WiMAX Features

WiMax have lots of features to its name. Lots of limitations were found as the use of Wifi technology grew around the world, to overcome these limitations and to invent better and more efficient wireless technology was realized which turned out to be WiMax. WiMax have lots of features which helped in increase usability of WiMAX around the world. It is still not been used to its full potential that’s why there may be more features which may not be known as yet, more and more exploration is required to get WiMax technology to its full use, however we know some of its significant features which are important enough to mention.

• Long Rang

Connectivity from long range is much highlighted feature of WiMax. Theoretically it is believed that WiMax technology provides range up 30 mils (50 Km). However in practical experience it is observed that it provides range up to 10 km which is still huge break through in long range connectivity. Users can connect to WiMax base station using SUI from their homes.

• Mobility

Another significant feature of WiMax technology is the connectivity on move. This technology amaze the world hence increasing the use of WiMax in some parts of the world dramatically. Especially to the urban places where cables and other network equipments are not feasible to install. Using its long range feature it provides connectivity on such area where other means of high speed Internet are not available.

The other major mobility feature of WiMax technology is that connecting devices (Laptops, PDA etc) can move in certain area and still be connected to the network.

• Interfacing
  
  

WiMax radio signals are broadcasted to its subscribers from base stations. Base stations are area where all necessary hardware is installed to provide WiMax with in its range. Since one Base station covers limited range so connecting multiple base stations to each other increase that much range for connectivity. Connecting multiple base stations to each other is not big task and can be perform in few hours.

• Accessibility

Accessing WiMax base station is not a difficult task, its long range capability provides connectivity at home from base stations within the range. To get high speed internet it’s only required to be because subscriber to WiMax service providers. They will provide you appropriate hardware to become of the subscriber. Installing the hardware is very easy; it is just plug and play. Hardware mostly connects through USB ports or Ethernet and connection can be made by clicking just a button.

There may be several other features which will surely come up as the growth of WiMax technology increases.

WiBro-wireless broadband internet - WiMax

WiBro is better than WiMAX?

The cumbersome and time-consuming negotiations and tests for the WiMAX technology could possibly be the alternative technique to an unexpected WiBro give up. That at least is speculation from the market researcher ABI Research indicates. During the WiMAX Forum is still with compatibility problems and the possible introduction of the IEEE 802.16e substandard employed, the Korean founder of the once dismissed WiBro technology even further: WiBro is already in a position to data on fast-moving equipment to pass. In tests succeeded a broadband connection to a mobile device that is 60 km / h and moving between two base stations to pass.

In Asia, demand for mobile technology is particularly high. Therefore, preparation are already in, two telecommunications companies in South Korea on the large-scale are launching WiBro wireless networks. Sections commend at the beginning of the year 2006. Even Japanese government is the very open and interested in Mobile technology

International Worldwide Interoperability for Microwave Access.

Forum (WiMAX) had official tests of the WiMAX standard IEEE 802.16-2004 for the month of October 2005. WiMAX, which stands for Worldwide Interoperability for Microwave Access. There is a new standard (IEEE 802.16e) for regional radio networks. With theoretically up to 50 km range and a data transfer rate of up to 109 Mbps (at 28 MHz bandwidth) than WiMAX the current WLAN technology, the outdoor use on-3-6 km range. WiMAX wireless LANs can transit voice data, for example voice over Ip protocol (VoIP). This is a special Quality of Service (QoS) mode planned. The WiMAX technology enables broadband connections in those regions were DSL services can not provided.

WiBro is a Korean standard. These Wimax variant is mainly the broadband data with onboard devices support. According to the company's Samsung WiBro allows Handovers for up to 120 km / h and thus as an alternative to mobile technologies of third generation (3G) UMTS as relevant.

For development outfitters WiBro and the Korean Electronics and Telecommunications Research Institute (ETRI)are working together. It had the Korean government in 2002, a frequency band of 100 MHz in the 2.3GHz spectrum for WiBro was released. In June 2004 the standard Phase 1 of WiBro allows a data throughput from 20 to 30 Mbps in cells whose radii of one to five kilometers amount.

WiBro-wireless broadband internet

WiBro-wireless broadband

Wireless Broadband (WiBro) is an alternative to WiMAX. It was developed in South Korea and even there by the Telecommunications Technology Association (TTA) of Korea standardized. As WiBro mobile the same approach as IEEE 802.16 persecuted and had a development advantage, the IEEE committee the WiBro project into the development process for 802.16e. This flowed certain developments in the mobile WiMax, particularly the transmission SOFDMA.

In 802.16e is a radio service for broadband, mobile access is defined, more or less for the mobile, wireless Internet.


Specifications of WiBro

WiBro supports with data rates between 20 Mbps and 50 Mbps It is distinguished by the handover and may, at speeds exceeding 100 kph received. The WiBro wireless cells have a radius of one to five kilometers. As the transmission frequencies using the Koreans and Japanese, a 100-MHz band at 2.3 GHz. Technically WiBro transmission works with scalable SOFDMA with 2,048 subcarrier.

WiBro offers service (QoS), making it even for streaming media and VoIP is interesting. In conjunction with the handover, it can also as an alternative to the techniques of the 3rd mobile Generation (3G) such as UMTS will be considered.

In order for the wireless broadband technologies, WiBro and WiMAX later mutually compatible, have well-known chip manufacturer and Korean firms, the WiBro project have developed for compatibility issues asserted

WiMAX Security -WiMAX Security Risks.

Possible Security issues and risks using WiMax

WiMax is quite discussed broadband technology which is yet be deployed properly in many parts of the world, it is been used effectively in few parts of world for delivering high speed internet connectivity over longer distances. This feature is making it popular to internet and telecommunication services. WiMax was developed because security issues in older technology WiFi 802.11. WiMax vendors and standard setters realized the importance of the security therefore, 802.16 working groups was designed considering several mechanisms to protect the network and the customers privacy from unauthorized access.

Authentication

An important and creative feature incorporated in 802.16 network is that each SS, (subscriber station) must have X.509 certificate, this certificate will identify the subscriber uniquely, attackers will not be able to get into the legitimate subscribers list by spoofing their identity because of X.509 certificate. X.509 hence provides enough security against major threats to services. However, lacking in base stations and service provider authentication leaves a big loop whole in the authentication mechanism used by WiMax privacy and key management (PKM), this expose WiMax subscribers to different confidentiality and availability attacks by unauthorized users. To protect from such vulnerability, amendments where made in 802.16 standards. Extensible Authentication Protocol (EAP) was introduced in 802.16e.

Encryption

Introduction of 802.16e and support for the AES provide the strong support of confidentially of data traffic. 802.16 has same issue just like 802.11 management frames are not encrypted, that increases the chances for attackers or intruders to collect information about subscribers and network.

Availability

WiMAX uses licensed Radio Frequency (RF) spectrum, which provides protection from unauthorized access to some extent. There are tools available which are easy to use for jamming the spectrum from all planned WiMAX deployments. Along with physical layer denial of service attacks, intruders can use legacy management frames to disconnect the current legitimate network connections.

WiMAX Threats

With all efforts to make WiMAX a very secure technology, there are still several potential attacks which are threats to WiMAX usabilit few of them are DOS attacks, Rogue Base Stations, Man in the middle attacks, spoofing of management frames etc. The actual testing of WiMAX security will come into play when WiMAX provider begins wide scale network deployment. This will give attackers good chance and better exposure to manipulate the network security, and access CPE equipment. Until the proper deployment of WiMax technology, Security issues are just speculations.

IEEE- 802.16a Standard specification- WiMz

The Working Group deals with 802.16 wireless access technologies to broadband networks, specifically with an air interface, so with an Air Interface for Fixed Broadband Wireless Access Systems. There are data rates of over 100 Mb / s at distances of over 50 km.

Specifications of wireless broadband technologies IEEE

For the transmission frequency used is between 10 GHz and 66 GHz and is a sight (LOS) defined. In Germany used frequency ranges at 23 GHz and 38 GHz. As in the urban area are usually no direct line of sight is available, there is still a second 802.16a specification for the frequency range between 2 GHz and 11 GHz for poor visibility conditions.

The standardization bodies of 802.16 deal equally with the media access method (MAC) and Physical Layer (PHY), with broadband transmission lines with bandwidths of 20 MHz, 25 MHz and 28 MHz for the channels of the up-and downlink is expected. As a media access process, which the different environments of the physical layer adapted to be used with 802.16 TDMA Time Division Duplex (TDD) or frequency division duplex (FDD). As the maximum data rate will be 134 Mbps for a 28-MHz channel indicated. Moreover, 802.16 defines four classes of service, guaranteed service (QoS), the time-critical transmission of audio and video files.

This Working Group, the Broadband Wireless Access (BWA) is working very closely with the 802.11 Working together. The results are incorporated into the WiMAX one.

The various 802.16 standards.
802.16a: Licensed Frequency 2 GHz to 11 GHz. The Working IEEE 802.16a operates at the MAC and PHY specification and specifies the transfer of non-visual connections (NLOS). Frequencies are important for the 3.5 GHz and 5.8 GHz licensed for royalty-free applications. The data is at a channel width of 20 MHz 75 Mbit / s. 802.16a is replaced by 802.16-2004.

Specifications of 802.16

802.16b: Licensed Exempt Frequencies, with a focus on the frequency band of between 5 GHz and 6 GHz. This group also runs under the name Wireless HUMAN (High Speed Unlicensed MAN).

802.16c: Profiles of transmission frequencies in the frequency range from 10 GHz to 66 GHz. The channel width is in the U.S. 25 MHz, 28 MHz in Europe. 802.16c is replaced by 802.16-2004.

802.16d: Profiles of transmission frequencies in the frequency range of 2 GHz to 66 GHz. Replaced by 802.16-2004. This standard provides visual and non-visual connections in the range of 2 GHz to 66 GHz.

802.16e-2005: Mobile Wireless MAN (WMAN). This working group defines a mobile access in the context of IEEE 802.16. Here are ranges of more than 10 Mbps in cells in the range of several kilometers and speeds exceeding 100 kph investigated. In addition, 16e-clients between different radio cells can switch, known as roaming. 802.16e is in conjunction with DSRC an interesting alternative for telematic and safety services in the automotive technology.

802.16f: MIB management for access networks.

802.16g: Definition of Management Plane.

802.16h: Coexistence of Networks. This Working Group deals with the problems of coexistence of different radio technologies in unlicensed bands transmission.

802.16i: Mobile One Plane Information

802.16j: bridging alternative to 802.11k. This involves Equipment for a mobile relay, which has several communications partner stations can connect.

802.16k: Bridging

802.16m: 802.16m The group is working on the high-speed transmission with up to 1 Gbit / s.

802.16-1: Air Interface for 10 GHz to 66 GHz.

802.16.2: Coexistence of Broadband Wireless Access Systems. This Working Group deals with the coexistence of existing systems. Replaced by 802.16.2-2004.

802.16.2-2004: Combines standards 802.16, 802.16a, 802.16c and 802.16d in a standard and regulate the coexistence of wireless broadband systems in the range of 10 GHz to 66 GHz.

802.16.2a: Recommended Practice for Coexistence of Fixed Broadband Wireless Access Systems. This group is the coexistence of PMP systems between 2 GHz and 11 GHz redefine.

802.16.3: Air Interface for Fixed Broadband Wireless Access Systems operating below 11 GHz. In this group are the unlicensed bands, such as the ISM band, the Personal Communications Services (PCS), and MMDS Unii for the use of a high-speed access MAN investigated.

WiMAX Products - 802.16 products cerified by Wimax Forum

WiMAX technology is new therefore its products are not as well known as products of technology Wifi known to every one. This does not mean WiMAX is not popular enough that no products are yet launched. There are several products for WiMAX subscribers which are available in market with limitations because not many subscribers demands for it. All the products which are used for WiMax deployment are installed with WiMAX chip and they are mostly certified by WiMAX forum, WiMAX forum is one of the pioneers in promoting and setting standards in WiMAX technology and its deployment.

WiMax products can be categorized into two parts, Indoor products and Out door products.

Indoor WiMax products:

WiMAX indoor products which are basically used at the subscribers end.

• WiMax indoor subscriber unit(SUI)
  

This device is indoor wireless subscriber access product which is designed on protocol IEEE 802.61-2004 standards. This device compatible to MPM equipment PMP is point Multipoint. Device has multiple Ethernet ports interface including (VoIP). SUI have LED installed on its front side which shows the strength of the signals. This is third generation device (3G). SUI uses technology called Orthogonal Frequency Division Multiplexing (OFDM) and non-line-of-sight (NLOS) technology enables handling rural and urban obstacles like trees, building even mountains to keep the connection to the link

• WiMAX External antenna
  
  

This external antenna is used to improve the signal strengths of WiMax subscribers from base station. WiMax external antennas are mostly required when subscriber is located in middle of populated or dense area; it can also be used where high mountains, and tree creates obstacles within base station and subscriber location. Antenna is connected with wire to indoor subscriber unit SUI to strengthened the signals

WiMAX Outdoor products

• Outdoor Subscriber Unit (SU-O)
  

This outdoor subscriber unit (SU-O) works exactly like SUI. The only different this product is its outdoor usability. It forms connection to WiMax base station to provide broadband access to WiMax subscriber. Its way of functionality is no different than SUI.

• WiMAX Certified Base Station
  

The world’s first WiMAX forum certified base station is Redlines’ RedMAX AN-100. This device works and base station for WiMax, it is easy to install and very cost effective for deployment. Its low latency makes sure that it provide delivery of good quality and sensitive services, including voice traffic, voice over ip (VoIP), video and data traffic.An-100 designed architecture assures over-the-air facility with help of software. It also has dynamic ability of on-the-fly services.

AN-100 base station can be used in cluster of 60 degree sectors; this supports many unique data flows and many subscribers simultaneously per sector. It synchronizes its time with GPS system for spectrums and available channels. Its hardware is easily upgradable in field by software downloads.

Future Products

There are other products which are important in normal use for general public. These are Wimax cards for laptops and desktop computers with WiMax chip install in them. Pdas and other handsets with Wimax ability. This is the future deployement of WiMax products. They are very rare in market or under testing process. The WiMax chip is not feasible to be install in such products as it has high cost. We will have to see how soon WiMax technology deployment takes over older technologies like WiFi and how soon these products comes with WiMax chip built in with in cost of range for normal user.

WiMAX - WiMAX Applications And Solutions

As mentioned several times while talking about WiMAX that this technology is not been widely adopted yet, in some parts of the world this technology is quite unknown where as some countries use WiMAX technology for residences or SOHO purpose, but it is yet be adopted on any governmental scale. These are most common applications of WiMAX which can be used for Broadband Wireless Access (BWA).

1. Residential or Home and Broadband Internet Access:

DSL and cable internet technologies are widely used in residentially and in SOHO. These technologies have strong hold on market by satisfying and meeting the needs of broadband internet users. Taking over from these users for WiMAX technology based internet may be not possible at given time, however internet provided by WiMAX bases station towers can be well utilized within the rural areas where DSL and Cable internet facilities are not available. Using WiMAX internet technology brings reliability to the customers as it being the wireless in nature there are no apparent mediums required to use it. WiMAX base station will simply connect to customer premises device and that will be all. Deploying WiMAX technology is very useful for developing countries where setup and reliability of Land line telecommunication infrastructure is poor.

2. Medium and small size business:

The WiMAX Wireless broadband Access (WBA) can be very well suited to provide the reliability and can meet the needs of small to medium scale business especially in low density area, whereas this may not work at its full potential in the area of high density. It has spectral limitation issues. There is a possibility that bandwidth may not be sufficient enough to provide access to large clients in high density area. This could bring the cost way up.

3. Backhaul networks for cellular base stations:

Backhaul networks for cellular base stations can be provided by bypassing the PSTN networks, Public Switched Telephone Network. This cost effective alternative can be achieved by cellular services by looking into Wireless backhaul. Strong WiMAX technology can be preferable choice for backhaul for enterprises such as hotspots and point to point backhaul access solutions.

4. WiFi Hotspots.

This can allow users to access internet remotely by roaming out side office and homes. There are several Hotspots and WiMax backhauls which are providing wireless solutions to wireless networks.

WiMAX - WiMAX Base Station- WiMAX Receiver- How WiMAX Works ?

WiMAX technology works little different than WiFi technology. In wifi computers can be connected through wireless LAN card to near by access point, wireless router or any Hotspot, it does not works this way when we talk about connectivity in WiMAX. WiMAX network connectivity constitutes of two parts, one can define as WiMAX tower or WiMAX booster, it is known as WiMAX Base station, whereas the other portion is WiMax receiver. Let’s talk about them in little details for better understanding the working.

1. WiMAX base station: As name explains base station is place where WiMax signals are broadcasted. It consists of electronic devices and WiMax Tower. This tower works exactly like GSM network phones towers standing high up in the air to broadcast radio signals. WiMAX tower base station can cover up 10Km radius. In theory it suggests to cover a lot more distance than just 10Km, it can reach some where about 50 km (30 miles), but in fact due to certain geographical limitations it goes as far as 10 km approx. 6 mils. Any wireless connecting device for WiMAX will connect to WiMAX network if fallen in to the range.
   
   
2. WiMAX Receiver: It is device or devices which receives the signals from WiMAX base station and connects to the WiMAX networks. These devices are usually stand alone Antenna or PCMCIA slot card for laptops or computers. Connecting to WiMAX base stations works as similar as connection of Wifi to access point works, the only difference is that WiMAX covers much wider area.

WiMAX - WiMAX Versus Wi-Fi

There is lots of confusion amoung both wimax and wifi technologies. There are many reasons for that, one could be both technologies starts with W letter, that makes some people think that they both are same technologies with different names. There is one more major reason why it makes confusing, they both belong from standard setter IEEE and there standards first 3 letter are same “802”, and both wifi and mimax technologies belong from Wireless connectivity family. Here it will be explained these two technologies may have few visiable similarities but how much they are different from each other when considered practically.

Wifi: Wifi is used for developing wireless LAN to access high speed internet or access just a network for file sharing and software services.

WiMax: WiMAX is quite latest technology and it can do far more than just developing wireless networks for high speed internet. It is also refer as Wireless broadband access, which can tranfer not only data, but voice data, video data etc and at muh higher rates..

Wifi: Wifi is capably for short range data tranfer, which can be with in hundred of meters range using non licesend spectrum to access network. WiFi is mostly connected to network in certain area which may not be connected to internet; it can be used for file sharing only.

WiMax: WiMax is designed for long distance coverage and it covers distance in kilometers, it uses licensed spectrum and unlicensed also in some case. WiMax delivers point-to-point connection to the internet from service provide to as user. In WiMax there are multiple standards of 802.16 a, b etc, so they are used for different types of access from mobile connectivity to fixed location connections.

WiFi: WiFi has introduced a quality of service similar to fixed Ethernet, where packets are priorities on their tags. This shows that quality of service (QoS) is relative to packet flow.

WiMax: WiMax uses technology based on setting up connection between end users’ device and base station. Special algorithm is scheduled for specific connection. This shows that Quality of Services (QoS) parameters can be guaranteed for each flow

WiFi is deployed much more than WiMax because of its ease of installation and cost effectiveness. It is easily deployed with in the building or room for providing internet access by third party internet service providers. Many public places, hotels, coffee shops have installed W-fi access points providing high speed internet to their customers

How WiMAX Works

The backhaul of the WiMAX system is based on the typical connection to the public wireless networks by using optical fibre, microwave link, cable or any other high speed connectivity. In few cases such as mesh networks, Point-to-Multi-Point (PMP) connectivity is also used as a backhaul. Ideally.
A base station serves subscriber stations using Non-Line-of-Sight (NLOS) or LOS Point-to-Multi-Point connectivity; and this connection is referred to as the last mile communication. Ideally, WiMAX system should use NLOS Point-to-Multi-Point antennas to connect residential or business subscribers to the Base Station (BS). A Subscriber Station typically serves a building using wired or wireless LAN. (Steven J. Vaughan-Nichols, June 2004)

What is WiMAX Technology

WiMAX system stands for Worldwide Interoperability for Microwave Access. WiMAX system technology is a telecommunications technology that offers transmission of wireless data via a number of transmission methods; such as portable or fully mobile internet access via point to multipoints links. The WiMAX system technologyoffers around 72 Mega Bits per second without any need for the cable infrastructure. WiMAX system technology is based on Standard that is IEEE 802.16, it usually also called as Broadband Wireless Access. WiMAX system Forum created the name for WiMAX technology that was formed in Mid June 2001 to encourage compliance and interoperability of the WiMAX IEEE 802.16 standard.

WiMAX technology often misinterpreted by the people by the names of mobile WiMAX system, 802.16d, fixed WiMAX system and 802.16e. Actually 802.16-2004 or 802.16d is developed by the third party as a standard and it is also referred to called as Fixed WiMAX system because this standard is lacking behind just because of the non-mobility feature that’s why it’s often called as Fixed WiMAX system. During the maturity period of WiMAX system technology system some of the amendments were made to the above mentioned 802.16d and they referred this amending standard as 802.16e. 802.16e introduced mobility and some other features amongst other standards and is also known as Mobile WiMAX system.

Less than one out of five people of the developed world and an even smaller, little percentage of people across the world have broadband internet access today. Existing technologies such as Digital Subscriber Line (DSL), cable, and fixed wireless are overwhelmed by expensive installs, problems with loop lengths, upstream upgrade issues, line-of-sight restrictions, and poor scalability.

WiMAX system is the next stage to a broadband as well as a wireless world, extending broadband wireless access to new locations and over longer distances, as well as considerably reducing the cost of bringing broadband to new areas. WiMAX system technology offers greater range and bandwidth than the other available or forthcoming broadband wireless technologies such as Wireless Fidelity (Wi-Fi) and Ultra-wideband (UWB) family of standards. It provides a wireless alternative to wired backhaul and last mile deployments that use Data Over Cable Service Interface Specification (DOGS1S) cable modems, Digital Subscriber Line technologies (DSL), T-carrier and E-carrier (Tx/Ex) systems, and Optical Carrier Level (OC-x) technologies. (Jiffy Networks, 2006)

The general initiative of metropolitan area wireless networking, as envisioned with 802.16, begins with what is called fixed wireless. A backbone of base stations is connected to a public network, and each base station carries hundreds of fixed subscriber stations, which can be both public hot spots and fire-walled enterprise networks. Later in the development cycle of 802.16e, WiMAX system is expected to encourage mobile wireless technology specifically wireless transmissions directly to mobile end users, This will be similar in function to the General Packet Radio Service (GPRS) and the one times Radio Transmission Technology (RTT) offered by mobile phone companies.

New organizations as well as individuals are increasingly adopting broadband, whereas those already using broadband are becoming dependent on it and are demanding better services with added benefits. To support this exceptional new demand, WiMAX system has emerged as a feasible solution, because of its inherent features that holds great promise for the future of wireless communications.

There has been a lot of excitement about WiMAX system and the impact that this standards based wireless network technology will have on the broadband access market. All this hype has generated great expectations, and the industry has responded with exceptional aggression and commitment toward taking broadband to the next level with WMAX system.