It is a layer that exists between ue and enb and exists at the ip level. Long term evolution protocol overview nxp semiconductors. In lte, when ue wish to establish rrc connection with enb, it transmits a random access preamble, enb estimates the transmission timing of the terminal based on this. Lte radio layer 2, rrc and radio access network architecture. Lte physical layer overview part iiiphysical channelsdownlink physical channels lte defines a number of downlink physical channels to carry information blocks received from the mac and higher layers. Lte rrc connection setup lte long term evolution medium. Below is a logical digram of eutran protocol layers with a depiction of data flow through various layers. The interaction of nr rrc and lte rrc can be illustrated as follows. User equipment ue radio transmission and reception. Nr can reselect to lte eutra and lte can reselect to nr while they are in idle state.
Tpcpucchrnti physical layer uplink power control na na. Takes care of the link adaptation amc, power control, cell search for initial synchronization and handover purposes and other measurements inside the lte system and between systems for the rrc layer. The enbs are interconnected with each other by means of the x2 interface. Sep 04, 2017 on another side, the control plane of 5gnr is identical to lte, here mme equivalent node named as amf access and management mobility function.
Physicalrrcnas layer procedure of 4glte terminal protocol conformance testing of 4glte terminal. The main services and functions of the rrc sublayer include. Transport channels are located between the physical layer and mac layer. The signal used for cell search is called a synchronization signal ss, and in lte it is transmitted in the 945 khz band at the center of. Myung 2 beyond 3g international mobile telecommunications imt2000 introduced global standard for 3g. Signaling provided the rrc layer has the following characteristics such as higher extensibility, secured transmission, reliable transmission and.
The diagrams below show the structure for the downlink and uplink of layer 2. Visualether protocol analyzer wireshark based visual protocol analysis and system design reverse engineering tool. Mobile class targets 100 mbps with high mobility and nomadic local area class targets 1 gbpswith low. Lte eutran and its access side protocols radisys white paper 2 eutran the eutran consists of enodebs enb which provide eutra user plane pdcprlcmacphy and control plane rrc protocol terminations toward the user equipment ue. At this step, the setup has been established only at rrc layer and mac layer for the second carrier is not yet activated. As defined by 3gpp, lte layer 2 structure consists of pdcprlcmac layers.
Lte radio layer 2 and rrc aspects linkedin slideshare. How to verify your lte protocol and rf interactions. This protocol controls mac, rlc and pdcp layers in the lte air interface connecting an lte ue with an enodeb. Study on further enhancements of small cell high layer aspects for lte. Systems beyond imt2000 imtadvanced is set to introduce evolutionary path beyond 3g. The overall pdcprlcmac architecture for downlink and uplink is shown in figs. When is rrc connection release requested by upper layers initiated. Physicalcommunication32010217244 219 table 1 lte,lteadvanced,andimtadvancedperformancetargetsfordownlinkdlanduplinkul.
Now enb transmits a random access response which consists of timing advance command, based on that ue adjusts the terminal transmit timing. Support for this feature requires enhancement to the lte release 89 phy, mac, and rrc layers while ensuring that lte release 10 maintains backward compatibility to lte release 89. There are some differences between the lte fdd and lte tdd modes that we identified. More specifically, the following three srb types are defined in eutra 1. Radio resource control rrc radio protocols for lte and lte. Dedicated control channel dcch a pointtopoint channel, dedicated to one ue, for the transfer of user information. Rlc and mac sublayers perform the same functions as for the user plane. Lte is the latest generation of the 3gpp standards. Packets received by a layer are called service data unit sdu while the packet output of a layer is referred to by protocol data unit pdu. Mar 24, 2010 radio link failure handling 1st phase. Srb1 is used for transport of rrc messages including. If nas messages are encapsulted in rrc messages, lterrc calls naseps dissector. Lte provides a packet switched model at the sap, but retains a circuit switched model at the phy. Lte uplink logical channels channel for transmitting control information between ues and network.
A nw or ue vendor wishing to implementsupport the sstd measurement reporting must use the version. Figure 4 depicts the access side protocol suite consisting of rrc, pdcp, rlc, mac, and phy layers. Jun 04, 2017 establishing an rrc connection in lte typically involves the following steps lte rrc connection setup is published by eventhelix in lte long term evolution. Lte advanced 3dl2ul interband carrier aggregation ca tr 36. This channel is used for ues having no rrc connection with the network. Control mac layer is identical, with one minor distinction, the rlc radio link control layer is identical, and the radio resource control rrc layer is essentially identical, with some distinction regarding when a couple of messages can be sent.
In lte, many of nas message is piggybacked on rrc messages. The physical layer itself maintains the continuous connection model, especially on the downlink, where there is continuous transmission. Physical layer layer 1 physical layer carries all information from the mac transport channels over the air interface. Multiple pdcchs can be transmitted in the same subframe using control channel elements cce each of which is a nine set of four resource elements known as resource element groups reg. Nov 06, 2015 this book presents the technical characteristics of the two radio network interfaces of mobile 4g, lte and lte advanced, based on release 8, 9 and 10 of the 3gpp specifications. Srb0 is used for transport of rrc messages associated with the common control logical channel. These channels are categorized as transport or control channels. Study on performance enhancements for high speed scenario in lte. Changes in the specification are limited to corrections and bug fixes.
A signaling radio bearer is defined as a radio bearer that is only used for transmission of rrc and nas messages. Radio resource control rrc is the highest layer in the control plane of the access stratum as. Rrc messages are transported via the pdcpprotocol the major functions of the rrc protocol include connection establishment and. It corresponds to the initial layer 3 message shown in figure 84 section 21. It is a layer that exists between ue and enb and exists at the ip level layer 3network layer. Mac multiplexes rlc links and manages scheduling and priority handling via logical channels. Pdf on mar 12, 2018, hassan alkhateeb and others published lte mac, rlc, and pdcp. Layer 1 monitors downlink quality and indicates problems to rrc rrc filters l1 indications and starts a timer if no recovery within 1st phase, triggers 2nd phase layer 2 monitors random access attempts and indicates problems to rrc rrc triggers 2nd phase 2nd phase radio link failure. Layer 3 radio resource control protocol the rrc is large and complex, covering a number of functional areas. Apr 23, 2016 lte layer 3 rrc layer interview questions. The mac layer formats and sends the logical channel data as transport channel.
This course focuses on the lte air interface and provides a detailed analysis of the structure and features of the physical layer, as well as the layer 2 and 3 protocols, before. The radio resource control rrc protocol is used in umts and lte on the air interface. The 5g layer 3 is rrc layer as shown in 5g protocol stack. Points covered include a detailed description of various components of the radio interface. The message may optionally contain registered mme the rrc connection setup complete may also carry octets for a nas message. The figure1 depicts 5g protocol stack consisting of both user plane and control plane protocol layers. Rlc layer passes data to the mac layer as logical channels. Broadcast of system information related to as and nas. Rrc connection setup message dedicated info nas is used to transfer ue specific nas layer information between the network and the ue. The main services and functions of the rrc sub layer include.
Radio resource control rrc radio protocols for lte and. The access network protocol stack of lte is separated into control and user plane in logic 1, the radio resource control. Index terms 3gpp, lte, radio resource control rrc, machine type. Rrc messages are transported via the pdcp protocol. Vulnerabilities of lte to rf interference and spoofing. Lte downlink logical channels 2 a pointtopoint bidirectional channel that transmits dedicated control information between a ue and the network. Lte layer 3 rrc layer interview questions techplayon. Protocol specification eventstudio system designer sequence diagram based systems engineering tool. Pdcp sublayer performs ciphering and integrity protection. Nr rrc does not only involved in nr but also in other radio access technology as well. This would make message decodingencoding process complicated but it would be efficient to reduce the number of message exchange between ue and enodeb. System information the broadcast of system information to all ues rrc connection control all procedures related to the establishment, modification and release of an rrc connection e.
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