The symmetric-key cryptography, also called secret key cryptography, is a cryptographic method using the same key to encrypt and decrypt, ie, that the security of the algorithm is based on the key and not in algorithm. Examples of this type of cryptographic algorithms are: AES, DES, 3DES and RC5.

The spectrum Regarding the spectrum, LTE becomes quite flexible, allowing bandwidths of 1.25MHz, 1.6MHz, 2.5MHz, 5MHz, 10MHz, 15MHz and 20MHz in the downlink and uplink [4]. Furthermore, it supports broadcast transmission in downlink and uplink-downlink modes, on the other hand, radio resources for broadcast transmissions can be modified according to the operator needs. The various scenarios which may present between the interaction of different service providers and other networks that they have, are not largely affected because manufacturers have planned coexistence, within the same geographic area, of the EUTRAN with other networks such as 3G and coexistence between adjacent operators,…

Macro-cells are not very efficient [1] in the residential area due to penetration problems that have been mentioned in a previous article, also in the macro-cells there are many users and is more difficult to provide QoS to all of them. For these reasons Internet Service Providers (ISP) have opted for femto-cell implementation at residential level, in order to increase the quality of services provided. Femto-cells are low-power base stations that provide low cost and high quality wireless services to residential, in this area offer a coverage of approximately 10 m [2], which are designed to integrate automatically with macro-cell…

Duplex Systems transmission: LTE-FDD and LTE-TDD FDD (Frequency Division Duplex) is a scheme of transmitting and receiving signals, this system allows full duplex communication using two different frequencies, one for the downlink and one for uplink, maintaining a separation band between said frequencies in order no overlap of channels, it makes that the FDD spectral efficiency is not very good. However, one advantage of this multiplexing scheme is that it does not introduce additional delays or latency. On the other hand, TDD (Time Division Duplex) is another multiplexing technique for communication that uses a single channel or frequency, for information…

With so much information that comes every day around the fourth generation mobile (4G), it is very common that we like to be updated, we care about general aspects of the architecture of this new technology. Well, "System Architecture Evolution" (SAE) or also known as EPC ("Evolved Packed Core") has its development from the year 2004 until 2009, during that time many studies have been deployed which allowed to define the standards that describes the architecture of the core network. The specifications are in chronological order in the following figure:   Figura # 1: SAE evolution [1].