Wireless system Analysis is based on two part. Radio Access Network part and Core technologies.
In the Radio Part, the technologies are evolving towards higher efficiency ( i.e. being able to encode/or send more data on the same radio signal ( or the carrier frequency). The movement is from TDM/FDM ( or 2G GSM), CDMA (IS95, CDMA 1x ) to WCDMA ( 3G) to OFDM (4G & LTE) .
In the Core, technologies are evolving from circuit switched to being packet switched. This basically means that instead of reserving a whole circuit for the duration of the call, you are dividing it in to data packets , which are re-assembled at the recieving end. IMS has multiple releases and stages, through which this move is being achieved.
In the Core, technologies are evolving from circuit switched to being packet switched. This basically means that instead of reserving a whole circuit for the duration of the call, you are dividing it in to data packets , which are re-assembled at the recieving end. IMS has multiple releases and stages, through which this move is being achieved.
IP Multimedia Service (IMS) is an architectural framework for delivering Internet Protocol (IP) multimedia services. It was originally designed by the wireless standards body 3rd Generation Partnership Project (3GPP), as a part of the vision for evolving mobile networks beyond GSM. Its original formulation (3GPP R5) represented an approach to delivering "Internet services" over GPRS.
Relational Analysis of LTE, IMS, SAE, EPC
LTE (Long Term Evolution) is the 4G wireless access technology from 3GPP like UMTS was the 3G or GPRS the 2.5G. Because it provides IP based only access and a lot of bandwidth 3GPP decided to study what converged architecture will support it. The study was called System Architecture Evolution (SAE). The Evolved Packet Core is the result of this study. It is the All-IP architecture to which LTE and other 3GPP (UMTS,GPRS) and non-3GPP (WiMAX,HRPD,WLAN etc) access systems connect to. The EPC provides a converged solution for Security, QoS , Mobility and connection to the IP based services (IMS or the Internet).Sometimes the term Evolved Packet System (EPS) is also used but it just refers to the EPC and the LTE access network (E-UTRAN) together.
IMS is on top of the EPC but its just considered one of the possible IP Services layer. There is a data interface (SGi) from the main gateway of the EPC (the PDN-Gw) to IMS and also a signaling/control interface (Rx) from the application function (the P-CSCF in IMS) to the main session controller in charge of the authorization, admission control, resource reservation, QoS (PCRF).
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