EU

user equipment, the user equipment. It is used to refer to all terminal devices involved in 3G \ 4G communication. Typical UE has involved the communication of mobile phones, vehicles, roadside facilities.

In the framework of the location:

At the lowermost end of the network, and the user is issued by the main communication request, a communication activity.

Connecting up with the access network (eNB).

RRC

Radio Resource Control, radio resource control. It refers to a certain strategy and by means of radio resource management, control and scheduling, improve the reliability and availability of resources.

Position in architecture

As a management control means to be present in the form of protocol layers between the UE and the access network (eNB) the control plane, providing an upper layer and a radio resource parameter and the main parameters controlling the behavior of the underlying

Down between the UE are: the media access control layer (Medium Access Control), PHY (Physical Layer)

Features

Provides connection management, messaging services such as the NAS layer;
Protocol entity of the access network provides the underlying functionality of the configuration parameters;
Responsible for UE mobility management related to measurement, control and other functions

Main technique

Call Admission Control: decide whether to accept the new user calls.
Switching technique: when the MS during a call from one base station coverage area to another base station coverage area, or from a mobile switching center (MSC) service area into the service area of another MSC, or due to outside interference caused call quality when lowered, the original voice channel must be changed and transferred to a new idle voice channel in order to maintain during a call.
Power control: conventional power control techniques is the voice service, mainly involving distributed and centralized power control, open loop and closed loop power control, based on the reception quality constant power control based. When the IP network becomes a core network, in conjunction with power control and other new technologies, such as smart antenna, multi-user detection technology, research combined error encoding control technology.
Channel assignment: a mobile cellular system in a cell system using the channel multiplexing, in the case of a multi-channel, shared, as much as possible may be used to provide a channel in the most efficient way of spectrum utilization in a communication device of each cell.
Packet scheduling technique: the presence of a mobile communication system, a large number of non-real-time packet data services, different users have different rate, the channel capacity of a user rate of the sum of all base stations within the base station can often exceed the transmission, so it must be the group scheduler determining the type of the service station so as to allocate different channel resources to the user.
End QoS guarantee: traditional IP network can not guarantee the QoS of user services, next-generation high-speed wireless mobile networks requires the ability to access Intemet, support a variety of multimedia applications and services to ensure QoS

UE under the RRC protocol state

RRCJDLE (idle state)

PLMN selection; NAS during the DRX configuration;

Broadcast information and a paging system; neighbor cell measurement;

Cell reselection mobility; uniquely identifies the UE acquires a TA region;

Within the context of the endless eNB

The RRC_CONNECTED (connected state)

The network-side UE context information; cell network side knows that the UE is located;

Network and the terminal can transmit data; mobility network control terminal;

Neighbor cell measurement; RRC connection exists:

Upon completion of the RRC connection

The UE may send and receive data from the network side, the shared channel monitor control signaling indicating control authority
The UE may report the channel quality to the network side
The UE may perform DRX network configuration