GSM Vs CDMA Technology

In cellular service there are two main competing network technologies: Global System for Mobile Communications (GSM) and Code Division Multiple Access (CDMA). Some moving companies included are: Sprint PCS, Cingular Wireless, Verizon and T-Mobile among others. Understand the difference between GSM and CDMA will allow the consumer to choose a company that uses the most appropriate network technology needs.

The Asociacón GSM is an international organization founded in 1987 dedicated to providing, developing and overseeing the global standard for wireless GSM. CDMA is a standard designed by Qualcomm in the United States has been the dominant network standard for North America and parts of Asia. However, GSM networks continue to make inroads in the U.S., CDMA networks are moving in other parts of the world.

There are points on both sides that firmly believe their own GSM or CDMA architecture is superior to another brand. Consumers requiring more information lend as much interest to the investment that will make the following recommendations can be helpful.

Coverage: The most important factor is to get a service that is in areas where it is to use the phone. Seeing the maps of the competitors and coverage in your area, you will discover if it is GSM or CDMA service indicates that you need.

Data transfer rate: The development of technology in cell phones is very continuous and markings must meet the needs of the user who buys these brands, some progress would be the streaming video devices, podcast receivers and email devices electronic, speed is important for those who not only use the phone to make calls. CDMA has been traditionally faster than GSM, though both technologies continue to compete in this subject over the years. Both boast "3G" or third generation technologies.

EVDO, also known as CDMA2000, CDMA is the answer to the speed requirements of consumers who need it has a download speed of 2 megabits per second, although some reports indicate that reached speeds are around 300 -700 kilobits per second (kbps). This is comparable to DSL base. As of fall 2005, EVDO is deployed. But this device is not available for all phones, it requires a phone with CDMA2000 and ready reference.

GSM's answer is EDGE (Enhanced Data Rates for GSM Evolution), with data rates up to 384 kbps, with speeds reached 70 to 140 kbps. With the addition of technologies that are still in beta that will include UMTS (Universal Mobile Telephone Standard) and HSDPA (High Speed ​​Downlink Packet Access), speeds reportedly increase to about 275-380 kbps. This technology is also known as W-CDMA, but is not compatible with CDMA networks. For this purpose you must use a phone with EDGE technology.

In the case of EVDO, theoretical high traffic can degrade speed and performance, while the EDGE network is more susceptible to interference. Both require a central location within the signal range to get the best speeds, while the performance of the signal decreases with distance.

Mie Scattering technique

Linear scattering may also occur at in homogeneities which are comparable in size with the guided wavelength. These result from the no perfect cylindrical structure of the wave guide and may be caused by fiber imperfections such as irregularities in the core- cladding interface, core- cladding refractive index differences along the fiber length, diameter fluctuations, strains and bubbles. The scattering created by such in homogeneities is mainly in the forward direction and is called Mie Scattering. Depending upon the fiber material, design and manufacture, Mie scattering can cause significant losses. The in homogeneities may be reduced by

-         removing imperfections due to the glass manufacturing process,

-         carefully controlled extrusion and coating of the fiber

-         Increasing the fiber guidance by increasing the relative refractive index difference.Read More

Complexity of Substitution Encryption and Decryption

An important issue in using any cryptosystem is the time it takes to turn plaintext into ciphertext, and vice versa. Especially in the field it is essential that the scrambling and unscrambling do not deter the authorized parties from completing their missions. The timing is directly related to the complexity of the encryption algorithm. For example encryption and decryption with substation ciphers can be performed by direct lookup in a table illustrating the correspondence, like the ones shown in example. One way thinking of this expression is that if one message is twice as long as another, it will take twice as long to encrypt.

Substitution Ciphers of Computing System

Children sometimes devise ‘secret codes’ that use a correspondence table with which to substitute a character or symbol for each character of the original message. This technique is called a monoalphabetic cipher or simple substitution, A substitution is an acceptance way of encryption text. Read More

Cryptanalysis in security system

A cryptanalysts chore is to break an encryption. That is the cryptanalyst attempts to m, deduce the original meaning of a ciphertext message. Better yet, he or she hopes to determine which decrypting algorithm matches the encrypting algorithm, so that other message encoded in the same way can be broken. Thus a cryptanalyst can do any or all of six different things-

Attempt to break a single message

Attempt to recognize patterns in encrypted messages, to be able to break subsequent ones by applying a straightforward decryption algorithm

Attempt to infer some meaning without even breaking the encryption, such as noticing an unusual frequency of communication or determining something by whether the communication was short or long.

Attempt to deduce the key in order to break subsequent message easily

Attempt to find weaknesses in the implementation or environment of use of encryption.

Terminology process

Encryption is the process of encoding a message so that its meaning is not obvious. Decryption is the reverse process, transforming an encrypted message back into its normal, original form. Alternatively the terms encode and decode or encipher and decipher are used instead of encrypt and decrypt. That is we say that we encode encrypt or encipher the original message to hide its meaning. Then we decode, decrypt or decipher it to reveal the original message. A system for encryption and decryption is called a cryptosystem.

The original form of a message is known as plaintext, and the encrypted form is called cipher text. For convenience in explanation, we denote a plaintext message p as a sequence of individual characters p={p1, p2, …..pn}. Similarly cipher text is written as C={c1, c2,…..cm}. for instance, the plaintext message “ I want cookies” can be through  of as the message string { I, w ,a, n, t, c, o, o, k, I, e, s}. it may be transformed into cipher text { c1, c2, ……c14} and the encryption algorithm tells us how the transformation is done.            

Controls in security system

To consider the controls or countermeasures that attempts to prevent exploiting computing system vulnerabilities, we begin by thinking about traditional ways to enhance physical security. In the middle ages, castles and fortresses were built to protect the valuable people and property inside. The fortress might have had one or more security characteristics including-

• A strong gate or door to repel invaders
• Heavy walls to withstand objects thrown or projected against them
• A surrounding moat, to control access
• Arrow slits to let archers shoot at approaching enemies

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Career Criminals

By contrast the career computer criminal understands the targets of computer crime. Criminals seldom change fields from arson or auto theft to computing more often criminals begin as computer professionals who engage in computer crime finding the prospects and payoff good. There is some evidence that organized crime and international groups are engaging in computer crime. Recently electronic spies and information brokers have begun to recognize that trading in companies or individuals secrets can be lucrative. 

What is Amateurs?

Amateurs have committed most of the computer crimes reported to date. Most embezzlers are not career criminals but rather are normal who observe a weakness in a y security system that allows them to access cash or other valuables. In the same sense computer criminals are ordinary computer professionals or users doing their jobs, when they discover they have access to something valuable. When no one objects the amateur may start using the computer at work to write letters maintain soccer league team standings or do accounting.