The article discusses 4th generation. 4G mobile, aims to provide an effective solution for the next generation mobile services. Progressing from previous three generations, 4G mobile systems have been significantly improving in terms of interactive multimedia services:The first radiotelephone service was introduced in the US at the end of the 1940s, and was meant to connect mobile users in cars to the public fixed network. In the 1960s, a new system launched by Bell Systems, called Improved Mobile Telephone Service” (IMTS), brought many improvements like direct dialing and higher bandwidth. The first analog cellular systems were based on IMTS and developed in the late 1960s and early 1970s. The systems were “cellular” because coverage areas were split into smaller areas or “cells”, each of which is served by a low power transmitter and receiver.First generation:-1G analog system for mobile communications saw two key improvements during the 1970s: the invention of the microprocessor and the digitization of the control link between the mobilephone and the cell site.
AMPS ( Advance mobile phone system ) was first launched by US which is 1G mobile system. It is best on FDMA technology which allows users to make voice calls within one country. Second generation:-2G digital cellular systems were first developed at the end of the 1980s. These systems digitized not only the control link but also the voice signal. The new system provided better quality and higher capacity at lower cost to consumers. GSM (Global system for mobile communication) was the first commercially operated digital cellular system which is based on TDMA.Third generation:-3G systems promise faster communications services, including voice, fax and Internet, anytime and anywhere with seamless global roaming. ITU’s IMT-2000 global standard for 3G has opened the way to enabling innovative applications and services (e.g. multimedia entertainment, infotainment and location-based services, among others). The first 3G network was deployed in Japan in 2001. 2.5G networks, such as GPRS (Global Packet Radio Service) are already available in some parts of Europe. 3G technology supports 144 Kbps bandwidth, with high speed movement (e.g. vehicles), 384 Kbps (e.g. on campus) & 2 Mbps for stationary (e.g.inbuilding )Fourth generation:-At present the download speed for mode data is limited to 9.6 kbit/sec which is about 6 times slower than an ISDN (Integrated services digital network) fixed line connection. Recently, with 504i handsets the download data rate was increased 3-fold to 28.8kbps. However, in actual use the data rates are usually slower, especially in crowded areas, or when the network is “congested”. For third generation mobile (3G, FOMA) data rates are 384 kbps (download) maximum, typically around 200kbps, and 64kbps upload since spring 2001. Fourth generation (4G) mobile communications will have higher data transmission rates than 3G. 4G mobile data transmission rates are planned to be up to 20 megabits per second.Before understanding 4G, we must know what is 3G ? 3G initiative came from device manufactures, not from operators. In 1996 the development was initiated by Nippon Telephone & Telegraph (NTT) and Ericsson; in 1997 the Telecommunications Industry Association (TIA) in the USA chose CDMA as a technology for 3G; in 1998 the European Telecommunications Standards Institute (ETSI) did the same thing; and finally, in 1998 wideband CDMA (W-CDMA) and cdma2000 were adopted for the Universal Mobile Telecommunications System (UMTS).W-CDMA and CDMA 2000 are two major proposals for 3G. In this CDMA the information bearing signal is multiplied with another faster ate, wider bandwidth digital signal that may carry a unique orthogonal code. W-CDMA uses dedicated time division multiplexing (TDM) whereby channel estimation information is collected from another signal stream. CDMA 2000 uses common code division multiplexing (CDM) whereby channel estimation information can be collected with the signal stream.Access Technologies (FDMA, TDMA, CDMA) -FDMA: Frequency Division Multiple Access (FDMA) is the most common analog system. It is a technique whereby spectrum is divided up into frequencies and then assigned to users. With FDMA, only one subscriber at any given time is assigned to a channel. The channel therefore is closed to other conversations until the initial call is finished, or until it is handed-off to a different channel. A “full-duplex” FDMA transmission requires two channels, one for transmitting and the other for receiving. FDMA has been used for first generation analog systems.TDMA: Time Division Multiple Access (TDMA) improves spectrum capacity by splitting each frequency into time slots. TDMA allows each user to access the entire radio frequency channel for the short period of a call. Other users share this same frequency channel at different time slots. The base station continually switches from user to user on the channel. TDMA is the dominant technology for the second generation mobile cellular networks.CDMA: Code Division Multiple Access is based on “spread” spectrum technology. Since it is suitable for encrypted transmissions, it has long been used for military purposes. CDMA increases spectrum capacity by allowing all users to occupy all channels at the same time. Transmissions are spread over the whole radio band, and each voice or data call are assigned a unique code to differentiate from the other calls carried over the same spectrum. CDMA allows for a ” soft hand-off” , which means that terminals can communicate with several base stations at the same time.Beyond 3G In the field of mobile communication services, the 4G mobile services are the advanced version of the 3G mobile communication services. The 4G mobile communication services are expected to provide broadband, large capacity, high speed data transmission, providing users with high quality color video images, 3D graphic animation games, audio services in 5.1 channels. We have been researching the vision of 4G mobile communication systems, services, and architectures. We also have been developing the terminal protocol technology for high capacity, high speed packet services, public software platform technology that enables downloading application programs, multimode radio access platform technology, and high quality media coding technology over mobile networks.I was trying to turn on the security settings in my cell phone, and am now getting a message that says PUK blocked. I don’t know what is wrong, and need help regarding PUK blocked on cell phone. Please help!!! ~ Jason A PUK blocked message pops up after one enters the wrong PUK code 7 or 10 times in a row, depending on the service provider. A PUK code is required only after one blocks the SIM PIN code. The PIN code is required to lock your phone for security reasons. Before we move on to PUK blocked on cell phones, let us understand the subtle difference between a PIN code and PUK code.PIN Code vs PUK Code Personal Identification Number or PIN code helps protect your SIM card from non-sanctioned or unauthorized access. Whenever you switch on your phone, you will have to enter the PIN code if you activate the security features of your mobile phone. This PIN code is known only by you and therefore only you can access the cell phone. If you enter the wrong PIN code 2 consecutive times, it will cause your SIM card to be blocked. This will not allow you or anyone else to make or receive calls on your number. This SIM card blocked can be unblocked only by entering the PUK code. You can read how to unlock a cell phone for more information.A PUK code or Personal Unblocking Key code (PUK code) is a security feature that helps protect the user. In case of theft, unauthorized use, or accidental blocking of the PIN code by the user himself, will require a PUK code to unblock the SIM card. Only the user has the PUK code printed on the card certificate attached to the SIM card. If the user misplaces the certificates, he can get the PUK code from the network provider. This is where the security feature comes into the picture. Only the user can get the PUK code from the network provider, if he can answer certain questions and identify himself as the real owner of the cell phone. No thief in his/ her right mind will dare call up the network for the PUK code. Thus, the user can rest his mind that his data will remain inaccessible to unauthorized use. A PUK code is a 8 digit code that is unique for every user. This is a very useful feature for cell phone safety.PUK Blocked on Cell Phone Many times, it may so happen that you block your PIN code. You will call the customer care of the service provider for the PUK code or refer the SIM certificates for the PUK code. If you enter the wrong PUK code 7 to 10 times in succession, it will lead to PUK blocked. After entering the wrong PUK code 10 times in a row, the SIM card becomes permanently invalid or locked. The only solution is to purchase a new SIM card. Let us look at some solutions to the PUK blocked problem, in case of different service providers.PUK Blocked ~ AT&T When your phone becomes locked after 3 incorrect PIN entries in a row, you will require a PUK code. You can get the PUK code from AT&T by 3 methods. You can either call the customer care or use the Technical Support Chat by AT&T. The users can even log in to myWireless Account online and get their PUK code. Once you obtain your PUK code, you will need to enter it into your cell phone. Then set a new PIN code for your phone. If you enter the wrong PUK code 10 times in succession, your SIM card becomes invalidated, that is, PUK gets blocked. AT&T can be approached for a new SIM card, as your SIM card is now useless.PUK Blocked ~ LG Xenon The same case with PUK blocked with LG Xenon. This security feature too inactivates your SIM card permanently, and you will need to visit the store for a new SIM card after you see PUK blocked. Samsung mobile phones too need a new SIM card. As it is not the phone, but SIM card that is inactivated.PUK Blocked ~ T Mobile With PUK blocked in T mobile cell phone, you must have entered the PUK code wrong 10 times in a row. This causes the SIM to get deactivated and again you will have to go in for a new SIM card.So, basically, which ever the service provider, PUK blocked requires you to get a new SIM card. It does not matter whether you use a Nokia cell phone, LG phones, Motorola phone, Samsung or Sony Ericsson phone handset. The handset is not the one that’s deactivated, but its the SIM card that gets blocked. So, contact your network store for further help and getting yourself a new SIM card (new phone number). I hope this article on PUK blocked on cell phone has helped you find the solution to your phone problems. As water and electricity never go together, when water gets into a cell phone, you should most importantly remove the battery. If the cell phone is a GSM one, also make sure that you take out the SIM card. See to it that you remove the memory card, if it has one. Try to dismantle the phone, as much as possible, but do not try to dismantle it completely. To preclude major damage to the inner circuits and components of the cell phone, you need to dry out the water completely. The more time the water stays in the phone, more are the possibilities of serious damages to the parts. Many a times the cell phone will go dead after water entering it and you may feel that nothing can be done at that moment. However, using few simple drying methods, can make the phone work again. Let us know how to dry out a cell phone.We have become so addicted to cell phones, that it’s very difficult to imagine life without them. Whenever we do try to imagine, we end up convincing ourselves that it isn’t possible to survive without these technological marvels. In a study undertaken by the Institute for Social Research at the University of Michigan, 83 percent respondents agreed that cell phones had made life a lot easier for them. Although they have become an integral part of our life, not many of us are probably aware of how cell phones work. In fact, most of the people think that cell phone working principle is too complex for a layman to understand. Before we move on to how do cell phones work, let’s take a brief look at some of the basics of cell phones.What is a Cell Phone?
The simplest possible definition of a cell phone is a two-way electronic device that uses radio frequencies in order to facilitate voice and data communication over the network. Alexander Graham Bell invented the telephone in 1876, while Nikola Tesla came up with the basics of radio in 1880s. Eventually, both these technologies were combined to come up with the gadget we refer to as the cell phone or mobile phone. Over a period of time, cell phones have undergone a drastic change from just being an upgraded variant of walkie-talkies, to a much more sophisticated multimedia device. Cell phones available today are not just restricted to voice or text conversation, but also accomplish a wide range of tasks, including music downloads and internet access. To know how mobile phones work, you can read more about how does a mobile phone work.
How do Cell Phones Work?Even though modern cell phones are capable of doing much more than their conventional counterparts, their primary function still remains voice and data communication over the network. This is basically accomplished by the transmission of radio waves from one base station to another. When you attempt to call another cell phone from your phone, a signal is sent to the base station of the cell phone which you are attempting to call. A base station, also referred to as mast or antenna, is a wireless communications station set up at a particular geographical location. The geographical area covered by a single base station is known as a cell. When the signal reaches the base station, it is assigned a specific radio frequency channel in order to facilitate conversation between the two individuals without any sort of interference. After the signal is processed, it is sent to a call switching center. Here the call is transferred to another cell phone, either directly or through a local carrier. Although the entire process seems to be quite complex, it actually takes less than a minute to connect you to the cell phone you are calling.Imagine a cell phone secretly watching your behavior. Think of your mobile phone eyeing your actions and recording them in its memory. Sounds impossible? I am afraid, it isn’t. In fact, cell phones can be used to track user behavior and record conversations and text messages that are exchanged through them. A spy phone is a mobile phone or a spy device that allows a user to monitor and hear or record conversations and other activities taking place over the phone. Spy phones can function in different ways. They can be used as listening devices whereby secretive conversations can be tracked. They are popularly used by secret agencies to track criminal activities that are carried out over cellular networks. They can be used for tracking periodic calls and recording the frequency of calls from certain suspicious numbers. Spy phones can be used for monitoring business and household activities while the cell phone user is away.Previously, simple wiretapping techniques were used to spy telephonic conversations. Secret agencies and security authorities commonly used phonetapping as a tool to track the suspects’ behavior. It would enable the security officials to listen to the telephonic conversations taking place over phones they tapped. However, with the advancements in technology, spying became easier. Today, installable software can be used to record cell phone calls and messages. Also, there are cell phone spying systems, wherein a spy is automatically alerted when the cell phone user dials a certain number. There are certain software applications, which can be loaded onto the cell phones and be used for maintaining call logs, recording text messages and monitoring Internet activity over the mobile phone. Some of these applications also let a user call the target cell phone number from a preset number and track the target user’s activities. ‘Phone Dead’ is a relatively recent technology that enables a cell phone to be used as a spy phone even when switched off. In this case, the spy cell phone is configured to function in a ghost mode, whereby it silently answers the calls it receives.With the implementation of modern spying techniques, cell phones can be converted into call and text message interceptors or GSM trackers, thus making them function as spy cell phones. Besides tracking messages and conversations, spy cell phones can also alert third-party users of the target phone’s outgoing calls. Spy phones can also be used to track the target user’s location by means of GPS technologies. They can be programmed to record audio or video for a predetermined period of time.Spy cell phones give rise to legal as well as ethical concerns. Their positive side is that they can be used by parents to monitor the behavior of their children. Also, they can be used by business officials to track workplace activity. The most important application of spy cell phones is in tracking criminal activities. But there is another side to this and it is not positive. Yes, spy cell phone software is easily available. Cell phones are easily convertible to spy phones. Their ready availability makes them subject to illegitimate use. Malicious cell phone users can gain an unauthorized access to other users’ mobile phones and dampen the overall security of cellular networks.
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