Wi-Fi

What is the Wi-Fi?

Wi-fi is a wireless network uses radio waves, just like cell phones, televisions and radios do. In fact, communication across a wireless network is a lot like two-way radio communication. When we use the Wi-Fi, a computer's wireless adapter will translates data into a radio signal and transmits it using an antenna. Then, a wireless router receives the signal and decodes it. The router sends the information to the Internet using a physical, wired ethernet connection.

For our information, the process of Wi-fi works in reverse with the router receiving information from the Internet, translating it into a radio signal and sending it to the computer's wireless adapter. Wi-Fi uses both single carrier direct-sequence spread spectrum radio technology (part of the larger family of spread spectrum systems) and multi-carrier OFDM (Orthogonal Frequency Division Multiplexing) radio technology. The regulations for unlicensed spread spectrum enabled the development of Wi-Fi, its onetime competitor HomeRF, Bluetooth, and many other products such as some types of cordless telephones.


The Wi-Fi was an unlicensed spread spectrum that first made available in the US by the Federal Communications Commission in 1985 and these FCC regulations were later copied with some changes in many other countries enabling use of this technology in all major countries. The FCC action was proposed by Michael Marcus of the FCC staff in 1980 and the subsequent regulatory action took 5 more years. It was part of a broader proposal to allow civil use of spread spectrum technology and was opposed at the time by main stream equipment manufacturers and many radio system operators. The first wireless products were brought on the market under the name WaveLAN with speeds of 1 Mbit/s to 2 Mbit/s. Vic Hayes, who held the chair of IEEE 802.11 for 10 years and has been named the 'father of Wi-Fi,' was involved in designing standards such as IEEE 802.11b, and 802.11a.


The Advantages And Disadvantages

The several advantages of the Wi-Fi are the Wi-Fi are faster than wired LANs, it is more partical and this wireless makes it more modern and help people on the go. If a wireless network router near them, they just use the laptop and surf the net or send emails without hasten. Because of the comfortable and quick installation, people often replaced old wired LANs with Wi-Fi. Some highly attended places like airports, libraries, schools or even coffee bars will offer us the constant Internet connection using exactly Wi-Fi. So retrieving new files, cruising the global network or corresponding with others will not be a problem anymore in those places. Then, the disadvantages of the Wi-Fi are it has more problems with privacy and is not secure. Also a debate among scientists that it could be damaging for human and their brains in long-term periods but this has not been proven.

Wi-Fi allows LANs (Local Area Networks) to be deployed without cabling for client devices, typically reducing the costs of network deployment and expansion. Spaces where cables cannot be run, such as outdoor areas and historical buildings, can host wireless LANs.

In 2008, wireless network adapters are built into most modern laptops. The price of chipsets for Wi-Fi continues to drop, making it an economical networking option included in even more devices. Wi-Fi has become widespread in corporate infrastructures.

Different competitive brands of access points and client network interfaces are inter-operable at a basic level of service. Products designated as "Wi-Fi Certified" by the Wi-Fi Alliance are backwards compatible. Wi-Fi is a global set of standards. Unlike mobile telephones, any standard Wi-Fi device will work anywhere in the world.

Wi-Fi is widely available in more than 220,000 public hotspots and tens of millions of homes and corporate and university campuses worldwide.WPA is not easily cracked if strong passwords are used and WPA2 encryption has no known weaknesses. New protocols for Quality of Service (WMM) make Wi-Fi more suitable for latency-sensitive applications (such as voice and video), and power saving mechanisms (WMM Power Save) improve battery operation.


Limitations

Spectrum assignments and operational limitations are not consistent worldwide. Most of Europe allows for an additional 2 channels beyond those permitted in the U.S. for the 2.4 GHz band. (1–13 vs. 1–11); Japan has one more on top of that (1–14). Europe, as of 2007, was essentially homogeneous in this respect. A very confusing aspect is the fact that a Wi-Fi signal actually occupies five channels in the 2.4 GHz band resulting in only three non-overlapped channels in the U.S.: 1, 6, 11, and three or four in Europe: 1, 5, 9, 13 can be used if all the equipment on a specific area can be guaranteed not to use 802.11b at all, even as fallback or beacon. Equivalent isotropically radiated power (EIRP) in the EU is limited to 20 dBm (100 mW).


Reach

Due to reach requirements for wireless LAN applications, power consumption is fairly high compared to some other low-bandwidth standards. Especially Zigbee and Bluetooth supporting wireless PAN applications refer to much lesser propagation range of <10m. Range is always making battery life a concern.

Wi-Fi networks have limited range. A typical Wi-Fi home router using 802.11b or 802.11g with a stock antenna might have a range of 32 m (120 ft) indoors and 95 m (300 ft) outdoors. Range also varies with frequency band. Wi-Fi in the 2.4 GHz frequency block has slightly better range than Wi-Fi in the 5 GHz frequency block. Outdoor range with improved (directional) antennas can be several kilometres or more with line-of-sight.

Wi-Fi performance decreases roughly quadratically as the range increases at constant radiation levels.

Kem Tautan Kasih-PPK Mikroelektronik

11-12 oktober 2008
Bukit Ayer Jungle Park Resort..

Pada Sabtu & Juamaat lepas, kelab mikroelektronik telah mengadakan Kem Tautan Kasih di Bukit Ayer Jungle Park Resort..Selama 2 hari 1 malam di situ, pelbagai pengalaman suka & duka berlaku. Kem ini diadakan bertujuan untuk merapatkan hubungan persaudaraan antara abang-abang dan kakak-kakak senior dengan adik-adik junior..hehe Semoga perhubungan ini terus kekal selamanya..

 

Salam Aidilfitri...

Selamat Hari Raya Maaf Zahir & Batin...

  Buat semua pensyarah,cikgu-cikgu tidak kira ketika saya belajar di tadika, sekolah rendah, sekolah menengah, matrikulasi dan UniMaP, kaum keluarga, rakan-rakan & rakyat malaysia.. Saya pohon maaf kalau saya ada tersalah laku dan kata yang telah menyinggung perasaan kalian semua. Saya pohon kalian semua maafkan saya dari hujang rambut hingga hujung kaki..Saya doakan agar raya kalian pada tahun ini adalah yang paling bahagia dan bermakna tidak kira bersama keluarga, kawan-kawan ataupun insan tersayang..hehe

    Kepada kawan-kawan yang berada di perantauan, jangan sedih-sedih jikalau tidak dapat beraya di kampung halaman.. Biasalah, hidup diperantauan ini kita perlu hidup berdikari. Bak kata pepatah,pengalaman mengajar kita erti sebuah kehidupan..

Sekian, Salam Aidilfitri dari saya..
Wassalam..