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Tuesday, September 09, 2008

Why i choose this topic???

Why I Choose This Topic

In this new era,wireless technologies are very important to people.Its connect us to the any gadget easier and faster.Its also require no wire.
With this topic,I can add my knowledge in this technology.Now,i know more about wireless technologies and how to use it.
Maybe,in the future i may use this technology to do some stuff.
Last but not least,the reason why i choose this article is to give all of you the knowledge about wireless technologies.
Thank You.

Wireless Technologies Overview


Introduction

Wireless technologies represent a rapidly emerging area of growth and importance for providing ubiquitous access to the network for all of the campus community. Students, faculty and staff increasingly want un-tethered network access from general-purpose classrooms, meeting rooms, auditoriums, and even the hallways of campus buildings. There is interest in creating mobile computing labs utilizing laptop computers equipped with wireless Ethernet cards. Recently, industry has made significant progress in resolving some constraints to the widespread adoption of wireless technologies. Some of the constraints have included disparate standards, low bandwidth, and high infrastructure and service cost. Wireless technologies can both support the institution mission and provide cost-effective solutions. Wireless is being adopted for many new applications: to connect computers, to allow remote monitoring and data acquisition, to provide access control and security, and to provide a solution for environments where wires may not be the best solution.

What follows is an overview of existing wireless technologies and related issues.


Applications

There are numerous applications for all the different wireless technologies. For the purposes of this paper, applications of wireless technologies are divided into the following:

Although a traditional classification, this way of categorizing wireless technologies also includes their differences in cost models, bandwidth, coverage areas, etc. Finally, a section is included on issues related to wireless technologies.


Voice and Messaging

Cell phones, pagers, and commercial two-way business radios can provide voice and messaging services. These devices may be based on analog or digital standards that differ primarily in the way in which they process signals and encode information. The analog standard is the Advanced Mobile Phone Service (AMPS). Digital standards are Global System for Mobile Communications (GSM), Time Division Multiple Access (TDMA), or Code Division Multiple Access (CDMA).

Normally, devices operate within networks that provide metropolitan, statewide, or nationwide coverage. These large and costly networks are operated by carriers such as AT&T, Sprint, Verizon, local phone companies, etc. and operate in different frequency bands which are allocated by the FCC. Throughput depends on the standard being used, but presently in the U.S., these networks operate throughput rates up to 16 kilobits per second (Kbps). New digital standards, also referred to as "Third-Generation Services" or 3G, are expected by 2004, and will provide 30 times faster transfer rates and enhanced capabilities. Because of the many standards, there are interoperability issues between networks, carriers, and devices. Generally, charges are based on per minute utilization or per number of messages.

Hand-held and Internet-enabled devices

Internet-enabled cell phones and Personal Digital Assistants (PDAs) have emerged as the newest products that can connect to the Internet across a digital wireless network. New protocols, such as Wireless Application Protocol (WAP), and new languages, such as WML (Wireless Markup Language) have been developed specifically for these devices to connect to the Internet. However, the majority of current Internet content is not optimized for these devices; presently, only email, stock quotes, news, messages, and simple transaction-oriented services are available. Other limitations include low bandwidth (less than 14 Kbps), low quality of service, high cost, the need for additional equipment, and high utilization of devices' battery power. Nevertheless, this type of wireless technology is growing rapidly with better and more interoperable products.


Data Networking

We differentiate between pure data applications in wireless local area networks (WLANs) and data, voice, and video converged in broadband wireless. We also briefly discuss Bluetooth, an emerging wireless technology.

Wireless Local Area Networks

Wireless Local Area Networks (WLAN) are implemented as an extension to wired LANs within a building and can provide the final few meters of connectivity between a wired network and the mobile user.

WLANs are based on the IEEE 802.11 standard. There are three physical layers for WLANs: two radio frequency specifications (RF - direct sequence and frequency hopping spread spectrum) and one infrared (IR). Most WLANs operate in the 2.4 GHz license-free frequency band and have throughput rates up to 2 Mbps. The new 802.11b standard is direct sequence only, and provides throughput rates up to 11 Mbps. Currently the predominant standard, it is widely supported by vendors such as Cisco, Lucent, Apple, etc. By the middle of 2002, a new standard, 802.11a, will operate in the 5 GHz license-free frequency band and is expected to provide throughput rates up to 54 Mbps.

WLAN configurations vary from simple, independent, peer-to-peer connections between a set of PCs, to more complex, intra-building infrastructure networks. There are also point-to-point and point-to-multipoint wireless solutions. A point-to-point solution is used to bridge between two local area networks, and to provide an alternative to cable between two geographically distant locations (up to 30 miles). Point-to-multi-point solutions connect several, separate locations to one single location or building. Both point-to-point and point-to-multipoint can be based on the 802.11b standard or on more costly infrared-based solutions that can provide throughput rates up to 622 Mbps (OC-12 speed). In a typical WLAN infrastructure configuration, there are two basic components:

  1. Access Points - An access point/base station connects to a LAN by means of Ethernet cable. Usually installed in the ceiling, access points receive, buffer, and transmit data between the WLAN and the wired network infrastructure. A single access point supports on average twenty users and has a coverage varying from 20 meters in areas with obstacles (walls, stairways, elevators) and up to 100 meters in areas with clear line of sight. A building may require several access points to provide complete coverage and allow users to roam seamlessly between access points.

  2. Wireless Client Adapter - A wireless adapter connects users via an access point to the rest of the LAN. A wireless adapter can be a PC card in a laptop, an ISA or PCI adapter in a desktop computer, or can be fully integrated within a handheld device.


Broadband Wireless

Broadband wireless (BW) is an emerging wireless technology that allows simultaneous wireless delivery of voice, data, and video. BW is considered a competing technology with Digital Subscriber Line (DSL). It is generally implemented in metropolitan areas and requires clear line of sight between the transmitter and the receiving end. BW comes in two flavors: Local multi-point distribution service (LMDS) and Multi-channel multi-point distribution service (MMDS). Both operate in FCC-licensed frequency bands.

LMDS is a high bandwidth wireless networking service in the 28-31 GHz range of the frequency spectrum and has sufficient bandwidth to broadcast all the channels of direct broadcast satellite TV, all of the local over-the-air channels, and high speed full duplex data service. Average distance between LMDS transmitters is approximately one mile apart.

MMDS operates at lower frequencies, in the 2 GHz licensed frequency bands. MMDS has wider coverage than LMDS, up to 35 miles, but has lower throughput rates. Companies such as Sprint and WorldCom own MMDS licenses in the majority of U.S. metropolitan areas. Broadband wireless still involves costly equipment and infrastructures. However, as it is more widely adopted, it is expected that the service cost will decrease.

Bluetooth

Bluetooth is a technology specification for small form factor, low-cost, short-range wireless links between mobile PCs, mobile phones, and other portable handheld devices, and connectivity to the Internet. The Bluetooth Special Interest Group (SIG) is driving development of the technology and bringing it to market and it includes promoter companies such as 3Com, Ericsson, IBM, Intel, Lucent, Motorola, Nokia, and over 1,800 Adopter/Associate member companies. Bluetooth covers a range of up to ten meters in the unlicensed 2.4GHz band. Because 802.11 WLANs also operate in the same band, there are interference issues to consider. Bluetooth technology and products started being available in 2001, but interoperability seems to be a big problem. By the time and if Bluetooth becomes an adopted technology, current WLANs will already be migrating to the 5 GHz band (mid 2002).

Important Issues for Wireless

As with any relatively new technology, there are many issues that affect implementation and utilization of wireless networks. There are both common and specific issues depending on the type of wireless network. Some of the common factors include electromagnetic interference and physical obstacles that limit coverage of wireless networks, while others are more specific, such as standards, data security, throughput, ease of use, etc.


Standards

A major obstacle for deployment of wireless networks is the existence of multiple standards. As it was mentioned previously, there are analog and digital standards in wireless telephony. While GSM is the only widely supported standard in Europe and Asia, multiple standards are in use in the U.S. As a result, the U.S. has lagged in wireless networks deployment.Just recently, organizations have been formed to ensure network and device interoperability. For example, the adoption of the 802.11b standard has made wireless data networks one of the hottest newcomers in the current wireless market.

Coverage

Another issue is coverage. Coverage mainly depends on the output power of the transmitter (FCC regulated), its location and frequency used to transmit data. For example, lower frequencies are more forgiving when it comes to physical obstacles (walls, stairways, etc.), while high frequencies require clear line of sight. For each particular application, throughput decreases as distance from the transmitter or access point increases.

Security

Data security is a major issue for wireless due to the nature of the transmission mechanism (electromagnetic signals passing through the air). It is commonly believed that voice applications are less secure than data applications. This is due to limited capabilities of existing technologies to protect information that is being transmitted. For example, in metropolitan areas, users are at risk that simple scanning devices can highjack cell phone numbers and be maliciously used. In WLANs, authentication and encryption provide data security. Current implementations include:

  1. MAC address-based access lists on access points, where only registered and recognized MAC addresses are accepted and allowed to join the network.
  2. A closed wireless system, where users have to know non-advertised the network name to be able to join.
  3. RADIUS server based authentication, where users are authenticated against a centralized RADIUS server based on their MAC address or their username and password.
  4. Wireless Equivalency Privacy (WEP) utilizes data encryption with 40-bit or 128-bit keys that are hidden from users. WEP provides three options, depending on the level of security needed: no encryption of data, combination of encrypted and non-encrypted data, and forced data encryption.
  5. High security solutions for encryption are proprietary: Cisco AP-350 and Lucent/Agere AS-2000. Both offer per user/per session encryption keys and authenticate users based on username/password scheme.

It is important to understand that in WLANs, data is encrypted only between the wireless adapter and the access point. Data travels through a wired LAN unencrypted. Therefore, data transmitted by wireless is not more secure than data transmitted through the wire, but probably not less secure. Application level encryption mechanisms, like secure web transactions (SSL), SSH, etc. are responsible for further protection of data.



What is UT doing?

Voice and messageing wireless services are provided in the Knoxville area by a number of commercial wireles providers. Wireless networking access on UT campus is provided by OIT. During 2000, DII (now OIT) has evaluated a number of products for wireless LAN access. Lucent/Agere/Orinoco/Proxim Access Server 2000 was selected. This product provides encryption with dynamic per user/per session keys by using RC4 encryption algorithm, thus preventing network sniffing. Users also have to login to the wireless network by providing their NetID username and password. This is authenticated against Radius and LDAP servers. If a user is not in LDAP or does not meet other criteria, a user is denied access to the wireless network. Since the first inception and due to limited client support and buggy software/firmware, UT has reverted to AP-2000 code in May 2002.



USB technologies

USB provides an expandable, hot-pluggable Plug and Play serial interface that ensures a standard, low-cost connection for peripheral devices such as keyboards, mice, joysticks, printers, scanners, storage devices, modems, and video conferencing cameras. Migration to USB is recommended for all peripheral devices that use legacy ports such as PS/2, serial, and parallel ports. Ultra-Wideband is a USB cable replacement technology that provides new solutions for wireless multimedia connectivity and interoperability. Drivers for most USB devices should use WDF.

Connectivity technologies

The industry specifications for system bus technologies, together with built-in bus class support in Windows operating systems, create the foundation for Plug and Play and other key user experiences on Windows-based platforms.

In addition, Windows supports device-to-PC connections through device discovery and wireless networking technologies. For devices that implement connectivity technologies, the broad range of Windows support ensures ease of use, reliability, interoperability, and greater security for end users who seek effortless, it-just-works experiences with their devices.

Wireless Technologies

To support networking solutions that consumer electronic devices and appliances can plug into, Microsoft is working on a range of wireless technologies to enable a robust set of user scenarios for local area networks (LANs), personal area networks (PANs), and wide area networks (WANs).

Windows provides extensive Native 802.11 support, which is the widely adopted standard for high-speed networking across wireless local area networks (WLANs).

Windows includes built-in support for Bluetooth wireless technology. Compatible hardware complies with the H:2 (USB) HCI specification for Bluetooth wireless technology. The hardware vendor does not have to provide a separate driver. Bluetooth L2CAP protocol drivers should use KMDF or a device-class-specific driver model such as AVStream. Drivers for RFCOMM devices should use UMDF.

Wednesday, September 03, 2008

Osama Bin Laden found!!!

It seems that Osama bin Laden would be about to be arrested! Believe it or not, he was found shopping in the streets of New York City!

OK, you do not believe we, as always. Here is a picture then: Bin Laden found!

Tuesday, September 02, 2008

olympic beijing!!!

Today, most of the people all around the world waited so eagerly when the Olympics games were announced to be held in every 4 years. Recently, the Olympic Games are the world's largest pageant of athletic skill and competitive spirit. They are also displays of nationalism, commerce and politics between nationalities of each country. Now, there were almost 203 countries currently participate in the Olympics. The Olympics are known from the history that consists of two period of time that is the ancient and modern Olympics while for each of Olympics have its own successful athletes and the countries that hosted the Olympic will have to face problems due on hosting the Olympic.

In the history of ancient Olympics games, it was a mainly part of a religious festival in honor of Zeus, the father of the Greek gods and goddesses. The festival and the games were held in Olympia. The ancient Olympic Games began in the year 776 BC, when Koroibos, a cook from the nearby city of Elis, won the stadion race, a foot race 600 feet long. According to some literary traditions, this was the only athletic event of the games for the first 13 Olympic festivals or until 724 BC. From 776 BC, the Games were held in Olympia every four years for almost 12 centuries. The first modern Olympics were held in Athens, Greece, in 1896. It took 1503 years for the Olympics to return after it were staged in Olympia in Athens Greece in the ancient era The person that has been responsible for its rebirth of the Olympic Games was a Frenchman named Baron Pierre de Coubertin, who has presented the idea in 1894. The Athens serves as the first host and recently, we have just experienced the 2008 Olympic game in Beijing, China and for the next Olympic will be held in London, England that is in 2012.

In each of the Olympic era, there were people that get involved with the Olympic Games and end up being successful athletes. In the era of the ancient Olympics games, there were a few of the names like Milo of Kroton, Theagenes of Thasos,Diagoras of Rhodes ,Polydamas of Skotoussa and Melankomas of Caria. But, one of the most legendary athletes in the ancient world is Milo of Kroton, which wore the victor's crown at Olympia no less than six times. In the game, Milo won the boys' wrestling contest in 540 BCE. Beside Milo of Kroton, one of the most legendary athletes in the same era was Theagenes of Thasos. He has become the most legendary boxer, pankratiast and runner. He have won boxing in the 75th Olympiad, 480 BCE and won in the pankration in the 76th Olympiad, 476 BCE. For the world record in the modern Olympics Irina Rodnina was the most successful athletes in history. Her three Olympic victories in 1972 with Aleksey Ulanov and in 1976 and 1980 with Aleksandr Zaytsev are a record for a pair’s skater. Her record at the World Championships was even more impressive. She won the title for ten successive years (1969-1978). For recently, in 2008 Olympics that was held in Beijing, the most successful athletes have won by the American swimmer Michael Phelps won a 13th gold medal.

The other facts about Olympic is the problems that may occur to the country that will host the Olympics games. Financing the Olympics is one of the largest problems faced by the IOC (International Olympic Council) and host countries today. Although allowing professional athletes and attracting sponsorships from major international companies solved financial problems but the large number of athletes, media and spectators makes it difficult and expensive for host cities to organize the Olympics. For example, the 2012 Summer Olympics (which will be held in London), is expected to have a budget of over £9 billion—one of the largest budgets for an Olympics to date. The other problem is, the Olympics usually being associated with one host city, most of the Olympics have had events held in other cities, especially the football and sailing events. For example, in the 2008 Beijing Olympics events were held in the territories of two different events were held in Hong Kong. This kind of problems is a norms to the country that will host an Olympic Games.

Although in every Olympics may come to a very difficult process but at the end, none of the festivals ended unsuccessfully. The Olympic Games is all about the history of ancient and modern Olympics games, the risen of a successful athletes in both era and the problems that may occurred to the Olympic host. Throughout on each festival, Olympics may come with a simple hope to all of the nationalities and ended the games with victories in hand.

The highly anticipated movie turned out to be a disappointment

i am a really big fan of Harry Potter.
but i couldn't help but being frustrated and quite angry after i left the cinema.
i had been waiting for Harry Potter and The Order of The Phoenix movie since early this year, as i expected a lot from the movie.
i read the book for a few times already and i know the storyline very well.
one of the things that made me very disappointed was how the director changed some of the scenes. and i thought that some of the scenes were very blurry. for some people who haven't read the book, they would have a lot of questions in their mind as each scene was not complete.
i think the movie was too short.
i was expecting it to be atleast 3 hours because the book is 700++ pages long.
i expected more from a box office movie.
the characters were ok except Harry, he was suppose to be an angry kid. i was expecting him to throw tantrums and shout more. but no.. he was still a polite person. Cho Chang was also a disappointment. i really disapproved when Katie Leung became Cho Chang. wasn't Cho Chang suppose to be a stunningly pretty and petite girl? i certainly think that she wasn't cut out to become Cho. not only that, she wasn't a good actress. i know it was only her second movie, but still.
Ginny Weasley's character was suppose to develop more in this movie. there should be a few love scenes as well.
Hermione, Ron, Neville and the Weasley twins weren't a disappointment. atleast these five people could act pretty well.
Luna Lovegood should be praised as well. she did very well for her debut film. and her characteristics were similar to how they were described in the book.
as for the members of the order of the phoenix, they were ok i guess. i was expecting to see more actions and dramas at 12, Grimmauld Place. Lupin was suppose to play a greater role in this movie.
the Death Eaters were good too.
but i have to say the fight at the Department of Mysteries was not elaborated well.
there was supposed to be more actions.
and i don't remember that Voldemort possessed Harry for awhile. that was bullshit.
however, i thought that the effect when there were flashbacks of the people that Harry loved was really good and i have to admit, i cried during that scene and when Sirius Black died.
Umbridge's character was well developed, i guess. but i don't remember her being a very pink person. she was annoying as described in the book.

i think that this movie was by far the worst compared to the previous ones.
i hope the director David Yates learns his lesson and will make the 6th movie better.

as for you people who haven't watched the movie, i would obviously say that the movie is highly not recommended.but still, even i, who heard the critics before i watched the movie, still eager to watch the movie and judge it myself.

whatever it is, please read the book before u watch the movie. =)

i can't wait for the final book, which will be released in 9 more days. i hope the rumours that Harry/Ron/Hermione will die is not true. coz that'll ruin my day and i'll be crying like hell.

i'm looking forward to see the death of Severus Snape and the Malfoys at the hands of Harry Potter himself. even if harry dies, he still managed to kill the assholes. Voldemort doesn't seem to bother me that much.