Tuesday, 31 May 2011

4G


4G

In the telecommunications, 4G is the fourth generation of cellular wireless standards. It is a successor to the 3G and 2G families of standards. In 2008, the ITU-R organization specified the IMT-Advanced (International Mobile Telecommunications Advanced) requirements for 4G standards, setting peak speed requirements for 4G service at 100 Mbit/s for high mobility communication (such as from trains and cars) and 1 Gbit/s for low mobility communication (such as pedestrians and stationary users).
A 4G system is expected to provide a comprehensive and secure all-IP based mobile broadband solution to laptop computer wireless modems, smartphones, and other mobile devices. Facilities such as ultra-broadband Internet access, IP telephony, gaming services, and streamed multimedia may be provided to users.
Pre-4G technologies such as mobile WiMAX and first-release Long term evolution (LTE) have been on the market since 2006 and 2009 respectively, and are often branded as 4G in marketing materials. The current versions of these technologies did not fulfill the original ITU-R requirements of data rates approximately up to 1 Gbit/s for 4G systems.
IMT-Advanced compliant versions of the above two standards are under development and called “LTE Advanced” and “WirelessMAN-Advanced” respectively. ITU has decided that “LTE Advanced” and “WirelessMAN-Advanced” should be accorded the official designation of IMT-Advanced. On December 6, 2010, ITU announced that current versions of LTE, WiMax and other evolved 3G technologies that do not fulfill "IMT-Advanced" requirements could be considered "4G", provided they represent forerunners to IMT-Advanced and "a substantial level of improvement in performance and capabilities with respect to the initial third generation systems now deployed."
In all suggestions for 4G, the CDMA spread spectrum radio technology used in 3G systems and IS-95 is abandoned and replaced byOFDMA and other frequency-domain equalization schemes. This is combined with MIMO (Multiple In Multiple Out), e.g., multiple antennas, dynamic channel allocation and channel-dependent scheduling.


The nomenclature of the generations generally refers to a change in the fundamental nature of the service, non-backwards compatible transmission technology, and new frequency bands. New generations have appeared about every ten years since the first move from 1981 analog (1G) to digital (2G) transmission in 1992. This was followed, in 2001, by 3G multi-media support, spread spectrumtransmission and at least 200 kbit/s, in 2011 expected to be followed by 4G, which refers to all-IP packet-switched networks, mobile ultra-broadband (gigabit speed) access and multi-carrier transmission

 

4G predecessors and discontinued candidate systems

3GPP Long Term Evolution (LTE)


Telia-branded Samsung LTE modem
The pre-4G technology 3GPP Long Term Evolution (LTE) is often branded "4G", but the first LTE release does not fully comply with the IMT-Advanced requirements. LTE has a theoretical net bit rate capacity of up to 100 Mbit/s in the downlink and 50 Mbit/s in the uplink if a 20 MHz channel is used — and more if multiple-input multiple-output (MIMO), i.e. antenna arrays, are used.
The physical radio interface was at an early stage named High Speed OFDM Packet Access(HSOPA), now named Evolved UMTS Terrestrial Radio Access (E-UTRA). The first LTE USB dongles do not support any other radio interface.
The world's first publicly available LTE service was opened in the two Scandinavian capitalsStockholm (Ericsson system) and Oslo (a Huawei system) on 14 December 2009, and branded 4G. The user terminals were manufactured by Samsung
 Currently, the two publicly available LTE services in the United States are provided by MetroPCS, andVerizon Wireless. AT&T also has an LTE service in planned for deployment between mid-2011 and end of 2013, Sprint Nextel has stated it's considering switching from WiMax to LTE in the near future.

Mobile WiMAX (IEEE 802.16e)

The Mobile WiMAX (IEEE 802.16e-2005) mobile wireless broadband access (MWBA) standard (also known as WiBro in South Korea) is sometimes branded 4G, and offers peak data rates of 128 Mbit/s downlink and 56 Mbit/s uplink over 20 MHz wide channels
The world's first commercial mobile WiMAX service was opened by KT in Seoul, South Korea on 30 June 2006.
Sprint Nextel has begun using Mobile WiMAX, as of September 29, 2008 branded as a "4G" network even though the current version does not fulfil the IMT Advanced requirements on 4G systems.
In Russia, Belarus and Nicaragua WiMax broadband internet access is offered by a Russian company Scartel, and is also branded 4G,Yota.

 

The following table shows a comparison of 4G candidate systems as well as other competing technologies.
Comparison of Mobile Internet Access methods 
Standard↓Family↓Primary Use↓Radio Tech↓Downlink fd(Mbit/s)↓Uplink (Mbit/s)↓Notes↓
WiMAX802.16Mobile InternetMIMO-SOFDMA128 (in 20MHz bandwidth)56 (in 20MHz bandwidth)WiMAX update IEEE 802.16m expected to offer peak rates of at least 1 Gbit/s fixed speeds and 100Mbit/s to mobile users.
LTEUMTS/4GSMGeneral 4GOFDMA/MIMO/SC-FDMA100 (in 20MHz bandwidth)50 (in 20 MHz bandwidth)LTE-Advanced update expected to offer peak rates up to 1 Gbit/s fixed speeds and 100 Mb/s to mobile users.
Flash-OFDMFlash-OFDMMobile Internet
mobility up to 200mph (350km/h)
Flash-OFDM5.3
10.6
15.9
1.8
3.6
5.4
Mobile range 30km (18 miles)
extended range 55 km (34 miles)
HIPERMANHIPERMANMobile InternetOFDM56.9
Wi-Fi802.11
(11n)
Mobile InternetOFDM/MIMO300 (using 4x4 configuration in 20MHz bandwidth) or 600 (using 4x4 configuration in 40MHz bandwidth)
Antenna, RF front end enhancements and minor protocol timer tweaks have helped deploy long range P2P networks compromising on radial coverage, throughput and/or spectra efficiency (310km & 382km)
iBurst802.20Mobile InternetHC-SDMA/TDD/MIMO9536Cell Radius: 3–12 km
Speed: 250km/h
Spectral Efficiency: 13 bits/s/Hz/cell
Spectrum Reuse Factor: "1"
EDGE EvolutionGSMMobile InternetTDMA/FDD1.60.53GPP Release 7
UMTS W-CDMA
HSDPA+HSUPA
HSPA+
UMTS/3GSMGeneral 3GCDMA/FDD

CDMA/FDD/MIMO
0.384
14.4
56
0.384
5.76
22
HSDPA widely deployed. Typical downlink rates today 2 Mbit/s, ~200 kbit/s uplink; HSPA+ downlink up to 56 Mbit/s.
UMTS-TDDUMTS/3GSMMobile InternetCDMA/TDD16Reported speeds according toIPWireless using 16QAM modulation similar to HSDPA+HSUPA
1xRTTCDMA2000Mobile phoneCDMA0.144Succeeded by EV-DO for data use, but still is used for voice and as a failover for EV-DO
EV-DO 1x Rev. 0
EV-DO 1x Rev.A
EV-DO Rev.B
CDMA2000Mobile InternetCDMA/FDD2.45
3.1
4.9xN
0.15
1.8
1.8xN
Rev B note: N is the number of 1.25 MHz chunks of spectrum used. EV-DO is not designed for voice, and requires a fallback to 1xRTT when a voice call is placed or received.
 

Posted on 06:52 by Sathish Esk

No comments


hacker is a person who breaks into computers and computer networks for profit, as protest, or sometimes by the motivation of the challenge. The subculture that has evolved around hackers is often referred to as the computer underground but is now an open community.
Other definitions of the word hacker exist that are not related to computer security. They are subject to the long standing hacker definition controversy about the true meaning of hacker. In this controversy, the term hacker is reclaimed by computer programmers who argue that someone breaking into computers is better called cracker, not making a difference between computer criminals ("black hats") and computer security experts ("white hats"). Some white hat hackers claim that they also deserve the title hacker, and that only black hats should be called crackers.

 

Hacker attitudes

Several subgroups of the computer underground with different attitudes and aims use different terms to demarcate themselves from each other, or try to exclude some specific group with which they do not agree. Eric S. Raymond (author of The New Hacker's Dictionary) advocates that members of the computer underground should be called crackers. Yet, those people see themselves as hackers and even try to include the views of Raymond in what they see as one wider hacker culture, a view harshly rejected by Raymond himself. Instead of a hacker/cracker dichotomy, they give more emphasis to a spectrum of different categories, such as white hat, grey hat,black hat and script kiddie. In contrast to Raymond, they usually reserve the term cracker. According to (Clifford R.D. 2006) a cracker or cracking is to "gain unauthorized access to a computer in order to commit another crime such as destroying information contained in that system".These subgroups may also be defined by the legal status of their activities.
White hat
A white hat hacker breaks security for non-malicious reasons, for instance testing their own security system. This classification also includes individuals who perform penetration tests and vulnerability assessments within a contractual agreement. Often, this type of 'white hat' hacker is called an ethical hacker. The International Council of Electronic Commerce Consultants, also known as the EC-Council has developed certifications, courseware, classes, and online training covering the diverse arena of Ethical Hacking.
Black hat
A Black Hat Hacker is a hacker who "violates computer security for little reason beyond maliciousness or for personal gain"(Moore,2005). Black Hat Hackers are "the epitome of all that the public fears in a computer criminal"(Moore,2006). Black Hat Hackers break into secure networks to destroy data or make the network unusable for those who are authorized to use the network.
The way Black Hat Hackers choose the networks that they are going to break into is by a process that can be broken down into two parts. This is called the pre-hacking stage.
Part 1 Targeting Targeting is when the hacker determines what network to break into. The target may be of particular interest to the hacker, or the hacker may "Port Scan" a network to determine if it is vulnerable to attacks. A port is defined as "an opening through which the computer receives data via the network"(Moore,2005). Open ports will allow a hacker to access the system.
Part 2 Research and Information Gathering It is in this stage that the hacker will visit or contact the target in some way in hopes of finding out vital information that will help them access the system. The main way that hackers get desired results from this stage is from Social Engineering, which will be explained below. Aside from Social Engineering hackers can also use a technique called Dumpster Diving. Dumpster Diving is when a hacker will literally dive into a dumpster in hopes to find documents that users have thrown away, which will help them gain access to a network.
Grey hat
A grey hat hacker is a combination of a Black Hat and a White Hat Hacker. A Grey Hat Hacker may surf the internet and hack into a computer system for the sole purpose of notifying the administrator that their system has been hacked, for example. Then they may offer to repair their system for a small fee.
Elite hacker
A social status among hackers, elite is used to describe the most skilled. Newly discovered exploits will circulate among these hackers. Elite groups such as Masters of Deception conferred a kind of credibility on their members.:86,90,117 Elite (e.g. 31337) gives the term leet speak its name.
Script kiddie
A script kiddie is a non-expert who breaks into computer systems by using pre-packaged automated tools written by others, usually with little understanding of the underlying concept—hence the term script (i.e. a prearranged plan or set of activities) kiddie (i.e. kid, child—an individual lacking knowledge and experience, immature).
Neophyte
A neophyte, "n00b", or "newbie" is someone who is new to hacking or phreaking and has almost no knowledge or experience of the workings of technology, and hacking.
Blue hat
A blue hat hacker is someone outside computer security consulting firms who is used to bug test a system prior to its launch, looking for exploits so they can be closed. Microsoft also uses the term BlueHat to represent a series of security briefing events.
Hacktivist
A hacktivist is a hacker who utilizes technology to announce a social, ideological, religious, or political message. In general, mosthacktivism involves website defacement or denial-of-service attacks. In more extreme cases, hacktivism is used as tool forcyberterrorism.

Attacks

A typical approach in an attack on Internet-connected system is:
  1. Network enumeration: Discovering information about the intended target.
  2. Vulnerability analysis: Identifying potential ways of attack.
  3. Exploitation: Attempting to compromise the system by employing the vulnerabilities found through the vulnerability analysis.
In order to do so, there are several recurring tools of the trade and techniques used by computer criminals and security experts.

Techniques

Vulnerability scanner
A vulnerability scanner is a tool used to quickly check computers on a network for known weaknesses. Hackers also commonly use port scanners. These check to see which ports on a specified computer are "open" or available to access the computer, and sometimes will detect what program or service is listening on that port, and its version number. (Note that firewalls defend computers from intruders by limiting access to ports/machines both inbound and outbound, but can still be circumvented.)
Password cracking
Password cracking is the process of recovering passwords from data that has been stored in or transmitted by a computer system. A common approach is to repeatedly try guesses for the password.
Packet sniffer
A packet sniffer is an application that captures data packets, which can be used to capture passwords and other data in transit over the network.
Spoofing attack (Phishing)
A spoofing attack involves one program, system, or website successfully masquerading as another by falsifying data and thereby being treated as a trusted system by a user or another program. The purpose of this is usually to fool programs, systems, or users into revealing confidential information, such as user names and passwords, to the attacker.
Rootkit
A rootkit is designed to conceal the compromise of a computer's security, and can represent any of a set of programs which work to subvert control of an operating system from its legitimate operators. Usually, a rootkit will obscure its installation and attempt to prevent its removal through a subversion of standard system security. Rootkits may include replacements for system binaries so that it becomes impossible for the legitimate user to detect the presence of the intruder on the system by looking at process tables.
Social engineering
Social engineering When a Hacker, typically a black hat, is in the second stage of the targeting process, he or she will typically use some social engineering tactics to get enough information to access the network. A common practice for hackers who use this technique, is to contact the system administrator and play the role of a user who cannot get access to his or her system. Hackers who use this technique have to be quite savvy and choose the words they use carefully, in order to trick the system administrator into giving them information. In some cases only an employed help desk user will answer the phone and they are generally easy to trick. Another typical hacker approach is for the hacker to act like a very angry supervisor and when the his/her authority is questioned they will threaten the help desk user with their job. Social Engineering is so effective because users are the most vulnerable part of an organization. All the security devices and programs in the world wont keep an organization safe if an employee gives away a password. Black Hat Hackers take advantage of this fact. Social Engineering can also be broken down into four sub-groups. These are intimidation, helpfulness, technical, and name-dropping.
Trojan horses
A Trojan horse is a program which seems to be doing one thing, but is actually doing another. A trojan horse can be used to set up a back door in a computer system such that the intruder can gain access later. (The name refers to the horse from the Trojan War, with conceptually similar function of deceiving defenders into bringing an intruder inside.)
Viruses
A virus is a self-replicating program that spreads by inserting copies of itself into other executable code or documents. Therefore, a computer virus behaves in a way similar to a biological virus, which spreads by inserting itself into living cells.
While some are harmless or mere hoaxes most computer viruses are considered malicious.
Worms
Like a virus, a worm is also a self-replicating program. A worm differs from a virus in that it propagates through computer networks without user intervention. Unlike a virus, it does not need to attach itself to an existing program. Many people conflate the terms "virus" and "worm", using them both to describe any self-propagating program.
Key loggers
A key logger is a tool designed to record ('log') every keystroke on an affected machine for later retrieval. Its purpose is usually to allow the user of this tool to gain access to confidential information typed on the affected machine, such as a user's password or other private data. Some key loggers uses virus-, trojan-, and rootkit-like methods to remain active and hidden. However, some key loggers are used in legitimate ways and sometimes to even enhance computer security. As an example, a business might have a key logger on a computer used at a point of sale and data collected by the key logger could be used for catching employee fraud.

    Posted on 06:48 by Sathish Esk

    No comments

    Tuesday, 3 May 2011

    People both young and old have a liking in something or the other. Even when at home when there is rain we find kids playing in the water. They make paper boats and enjoy their time. Likewise people love the time they spend in the sea shores and beaches. Some of the beaches to be visited in this territory are the Serenity Beach, the Paradise Beach, Karaikal Beach, Mahe Beach and Yanam River Cruise. Let’s get to know about the specialties of these beaches in detail. 

     The Serenity Beach is 1.5 kilometers long. It’s a beautiful site to watch as it is cool and clean. This beach is ideally suited for relaxation, swimming and sun-bath. The pleasant breeze from the Bay of Bengal makes us to have a stroll or jog or sit in the parapet by the sea. The beach has a history behind it as this witnessed the bloodiest of the battles between the French and the British. The sea front is graced by an impressive statue of the Mahatma (M.K.Gandhi) set amidst eight exquisitely carved pillars and wonderful war memorial commemorating the soldiers who lost their lives during the World War I. The Lighthouse and the 284 meters long New Pier are located further south. 

    The next is the Paradise Beach. This is called Plage Paradiso. This is located at Chunnambar near the mouth of the backwater. This is located about 8 kilometers away form Pondicherry towards Cuddalore Main Road. It is a perfect place for leisurely holiday and beach sport. The visitors can sail to the backwaters to the sands and pitch up a cozy sea side tent. One can see playing dolphins if cruised into the sea. 

     The next is the Karaikal Beach. This beach is an excellent place for watching the rising sun. The tourists can see the view of the slowly flowing Arasalar River meeting the sea which is simply breathtaking. The boating club on the beautiful backwaters of the Arasalar provides pedaller, motor and rowing boats to the tourists. The beautiful Mahe beach is a beach resort which is 22 kilometers south of Kannur in Kerala and is bordered by lush palm trees. There are numerous fishing hamlets. The Yanam river cruise is located in coastal Andhra Pradesh. Its beauty is enhanced by the spectacular Goringa Godavari River which meanders through rich mangrove forests.

    Posted on 23:30 by Sathish Esk

    No comments