සෑහෙන කාලෙකින් තමයි බ්ලොග් එක පැත්තෙ ආවෙ... කොහෙද ඉතින් මේ එක්සෑම්, ඉන්ටවිව්, අසයින්මන්ට් එක්කනෙ කරන්න බැරි... මාසයක් විතර එක්සෑම් තිබුනා. ඊට පස්සෙ ඉතින් අපේ ට්‍රේනින් පටන් ගත්තනෙ... ඉතින් ඔන්න ඔහොම තමයි පහුගිය කාලෙ ගෙවුනෙ...
ට්‍රේනින් යන්න හම්බ උනේ සන්ටෙල් එකේ. එහෙ තියෙනව වයි මැක්ස් (WiMAX) නෙට්වර්ක් එකක්. ඒ ගැන ඇති වෙච්ච ආසාව නිසා, අපේ ඉලෙක්ට්‍රොනික් සංගමයෙන්(E Club) කරන්න යන E-Carrier සඟරාවට ලිපියක් ලිව්වා. ගොඩක් තාක්ෂණික කරුණු අඩංගු කරන්න ගියේ නෑ. සාමාන්‍ය තාක්ෂණික දැනුමක් තියෙන කෙනෙකුට කියවලා තේරුම් ගන්න පුලුවන් විදියට තමයි ලිව්වෙ. ඉතින් මම ඒක බ්ලොග් අවකාශයෙ අපේ කට්ටියත් එක්ක බෙදා ගන්න හිතුවා. කියවලා බලන්න.
WiMAX
-Maximizing the benefits-
WiMAX is the 4th generation of wireless networking technologies that connects the subscribers to the internet at faster speeds, from much longer ranges of distances than the current wireless technologies allow. Not only data, but voice can also be transmitted via WiMAX without much overhead. It is used as an IP based access technology. Even at the preliminary stages of its evolution, WiMAX has gained much demand from the co-operate sector as well as domestic customers over broadband connections and dial up connections.
The abbreviation WiMAX gives the meaning Wireless Interoperability for Microwave Access and the name was proposed by the WiMAX Forum, which was formed to promote conformity and interoperability of the standard. The WiMAX Forum comprises of about 582 Internet Service Providers from 150 countries over the globe which provide WiMAX broadband access.
IEEE 802.16 standard is the basis for WiMAX and ensures compatibility and interoperability between broadband wireless access equipments. There are 2 versions of this standard, namely 802.16-2004 and 802.16e-2005 which define the regulations for Fixed and mobile WiMAX respectively. Mobile WiMAX has been introduced as an amendment for 802.16-2004 to accommodate mobile devices.
There is no uniform global licensed spectrum for WiMAX, however the WiMAX Forum has published three licensed spectrum profiles: 2.3 GHz, 2.5 GHz and 3.5 GHz, in an effort to drive standardization and decrease cost. Dialog Telekom, Lanka Bell, Suntel and Sri Lanka Telecom already hold WiMax licenses in the 3.5GHz band.
Main benefits of WiMAX over other broadband technologies
- Speed (Faster than broadband service)
- Higher Throughput
- Low Cost
- Lower Latency
- Wireless (Not having to lay cables reduces cost, Easier to extend to suburban and rural areas)
- Broad Coverage (Much wider coverage than WiFi hotspots)
- Vast range of services is available.
- Both fixed and mobile versions are available
In addition, WiMAX provides a versatile range of features which makes it suited to be used as a cutting edge access technology. Some of them are listed below.
Supports multipath
WiMAX is based on OFDM (Orthogonal Frequency Division Multiplexing) which provides the physical layer which is based on an orthogonal frequency distribution. Because of its good architecture, it allows users to operate in NLOS (None Line Of Sight) conditions, which means that there is no need for the transceiver at the customer premises to be in line of sight with the Base Station tower. It is due to the enhancements in the technology to support multipath signals.
High speed data rate
The scalable architecture of physical layer is offering high speed data rate in WiMAX. Scalability of data with the available bandwidth of the channel enables to optimize the channel for much higher datarates. WiMAX supports very robust data throughput. The technology at theoretical maximums could support approximately 75 Mbps per channel. Real world performance will be considerably lower, perhaps maxing out around 45 Mbps/channel in some fixed broadband applications.
Modulation and error correction
The use of WiMAX is increasing rapidly because it supports lots of modulation and error correction facilities to the end user. It also allows a user to change the scheme according to channel condition. (AMC) Adaptive Modulation and Coding is a valuable method utilized in WiMAX to exploit throughput in a varying channel.
High reliability of data
Automatic retransmission of data supported by WiMAX at data link layer is a great feature. It is not only improving reliability but also enables ARQ (Automatic Repeat Request) which makes it necessary that each broadcast packet is recognized by the receiver, and if any unacknowledged data packets which are unspecified or misplaced to be retransmitted.
At present, WiMAX is deployed by the service providers worldwide to supply a large range of services.
- Providing portable mobile broadband connectivity across cities and countries through a variety of devices.
- A wireless alternative to cable and DSL for "last mile" broadband access.
- Providing data, voice (VoIP) and video (IPTV) services which is also known as triple play of WiMAX.
WiMAX has its small range counterpart Wi-Fi, which is very famous specially in providing wireless LAN connectivity.
- WiMAX is a long range system, covering many kilometres, that uses licensed or unlicensed spectrum to deliver connection to a network, in most cases the Internet
- Wi-Fi uses unlicensed spectrum to provide access to a local network.
- Wi-Fi runs on the Media Access Control's CSMA/CA protocol, which is connectionless, whereas WiMAX runs a connection-oriented MAC.
- WiMAX and Wi-Fi have quite different quality of service (QoS) mechanisms.
Usually, there are situations where WiMAX and Wi-Fi are used together to build the Metropolitan Area Network and the Local Area Network respectively. WiMAX Subscriber Unit connects to the metropolitan WiMAX network and a Wi-Fi router provides connectivity within the home or business for local devices such as laptops, Wi-Fi handsets and smart-phones.
A simple WiMAX network is displayed below. Only the access and transmission networks are depicted. There can be subtle variations with the change of subscriber capacity.
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Source of the picture : www.neanatha.tk |
- Internet
- ISP
- Base Stations which sometime has optical fibre connections with the ISP’s main switch.
- Secondary level base stations which are connected to the main towers with microwave connections.
- WiMAX subscriber Unit
- LAN within the subscriber premises
When paired with new MIMO (Multiple Input, Multiple Output) technology, it can deliver mobile services three to five times faster than today's third-generation (3G) standards at a lower cost. A growing number of wireless-service providers around the world are planning to use WiMax's multimedia capabilities to complement existing cellular networks and service offerings. Sri Lanka also goes under the development and implementation procedure slowly, but steadily.
WiMAX will certainly continue to maximize the limits of global communication in the next decade… The leading electronic manufacturers of the world have already developed WiMAX enabled laptops, USB dongles, smartphones, headsets and many more mobile devices as well as fixed devices such as IP phones.
The day where you go down town in a bus which has a WiMAX access point, with a WiMAX mobile phone in hand and have a video conferencing session with your cooperate business partner , experiencing high speed internet access, is not very far…!!!
