Long term evolution lte is the next step forward in cellular 3g services. How to verify your lte protocol and rf interactions. Feasibility study on global application of lte band 11 and of lte band 21 user equipments ues tr 36. Signaling radio bearers srb are defined as radio bearers that are used only to transmit rrc and nas messages. After discussing the major enhancements that 5g exhibits over the current lte technology, this article an overview of 5g layers describes changes along with their purposes for each of the 5g nr layers. Medium access control mac layer basically provides the radio resource allocation service and the data transfer service to the upper layer. Type 1 uses frequency division duplexing uplink and downlink separated by frequency, and tdd uses time division duplexing uplink and downlink separated in time. The tci6614 was among the first generation of lte capable socs introduced along with similar product from mindspeed, freescale and cavium.
Lte downlink physical layer channels long term evolution. Lte downlink mimo terminology codeword independent transport block of data to be transmitted a maximum of 2 is supported in lte codewords mapped to multiple layers by a serial to parallel converter process layer a stream of data to be transmitted rank number of layers to be transmitted. This document provides a brief overview of the lte network architecture as the first technical document of lte area. The mac layer passes the received rlc pdu to the rlc layer. To ensure reliability, the network uses a double radio layer and redundant control nodes. In case of long term evolution lte, the scheduler in the medium access control mac layer of the enodeb allocates the available radio resources among different ues in a cell through proper handling. In long term evolution lte, as with other cellular technologies, drive testing is a part of the network deployment and management life cycle from the early onset.
First, the lte network reference model is defined and its basic evolved packet system eps entities and the functions of each entity are described. Modeling a 4g lte system in matlab idin motedayenaval senior applications engineer mathworks. It is a layer that exists between ue and enb and exists at the ip level layer 3network layer. These channels are categorized as transport or control channels. Lte radio layer 2, rrc and radio access network architecture. Lte technology is a based on a 3gpp standard that provides for a downlink speed of up to 150 megabits per second mbps and an uplink speed of up to 50 mbps. Type of information transferred transport channels. Ran architecture evolution drivers from a network architecture perspective, the main options for lte up to the present have been either fully distributed or fully centralized baseband deployment, each with its own pros and cons. Outline general introduction precoding and beamforming antenna design introduction to lte downlink and uplink physical layer reference signals and antenna ports mimo transmission schemes in lte codewords, layers, and streams tx diversity downlink sumimo.
Load balancing optimization in lteltea cellular networks. Lte protocol stack layers in lte tutorial 12 april 2020. Request pdf performance analysis of handover measurements and layer 3 filtering for utran lte handover is one of the key functionalities which tries to keep a user equipment ue connected to. Load balancing optimization in ltelte a cellular networks. Actions when a rlc data pdu is received from lower layer. This application note gives an introduction to lte technology, including both fdd and tdd modes of operation. Physical layer layer 1 physical layer carries all information from the mac transport channels over the air interface.
In consequence if more than four layers are used, beamforming and mimo is becoming a kind of merged feature. Customers using this soc were looking to address the outdoor pico cell market. Users of the present document should be aware that the document may be subject to revision or change of status. Pdf on mar 12, 2018, hassan alkhateeb and others published lte mac, rlc, and pdcp find, read and cite all the research you need on researchgate. May 29, 20 lte physical layer has different channels defined on both uplink and downlink, each with a predefined purpose. First, the lte network reference model is defined and its basic evolved packet system eps entities and the functions of each entity are. The rlc layer assembles an upper layer sdus if receipt of. Medium access control mac radio protocols for lte and. The number of data streams or layer, supported over mimo channel, is the maximum number of txrx antennas, where one encoded block is conveyed over one layer or aggregated several layers. Overview of the 3gpp long term evolution physical layer. Downlink physical layer of lte release 10 scrambling m odulation mapper layer mapper precoding resource element mapper ofdm signal generation resource element mapper ofdm signal. The physical layer channels are widely divided into data, control and random access channels. 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. Reliable, high rate, high capacity and low latency data transfer suitable for a wide range of services mobility seamless and lossless using packet forwarding optimized for low mobile speed from 0 to 15 kmh higher mobile speed between 15 and 120 kmh also supported with high.
The design of the lte physical layer phy is heavily influenced by the requirements for high peak transmission rate 100 mbps dl50 mbps ul, spectral efficiency, and multiple channel bandwidths 1. Lte release 8 major parameters access scheme ul dfts. Stage 2, this standard comes with the detailed descriptions about 5g nr network and protocol architecture. These physical channels are fed using the transportation channels of higher layers.
How is state camped on any cell different from any cell selection state. Sounding reference signal rs when pucch or pusch is not scheduled, sounding reference signals srs are used to test the reception quality for uplink channeldependent scheduling and are transmitted in the last symbol of the subframe. Lte is designed to meet carrier needs for highspeed data and media transport as well as highcapacity voice support well into the next decade. Following illustration is the case where the number of codeword is 2 and number of layer is 4. Lte layer 3 rrc layer interview questions techplayon. In case of dispute, the reference shall be the printing on etsi printers of the pdf version kept on a specific network. The rlc layer is present on top of the medium access control mac layer and beneath other higher layers such as rrc radio resource control and pdcp packet data convergence protocol in the lte protocol stack. Overview and detailed explanations are given for the latest lte standards for radio interface architecture, the physical layer, access procedures, broadcast, relaying, spectrum and rf characteristics, and system performance. Information on the current status of this and other etsi documents is. This document serves as a guide to the fundamentals of how lte networks operate.
Apr 23, 2016 lte layer 3 rrc layer interview questions. Just to give you more intuitive understanding of these table shown above, i represented two typical items as illustration. Dynamic range test case for a 5 mhz lte signal the following example describes a dynamic range test case for a 5 mhz lte signal. The different physical layer channels on downlink are as. Previous studies also examined the interplay between tcp and cellular networks. When pucch or pusch is not scheduled, sounding reference signals srs are used to test the reception quality for uplink channeldependent scheduling and are transmitted in the last symbol of the subframe. The physical layer itself maintains the continuous connection model, especially on the downlink, where there is continuous transmission. While all the literature clearly describe how the layer mapping is to be carried out for various usecases, not one the ones i have gone through really explain the need for this stage in the pipeline.
Ul and dl time slots, downlink pilot timeslot dwpts downlink part of special subframe, uplink pilot timeslot uppts uplink part of special subframe, guard period gp. Rrc layer or pdcp sub layer with upper layers sap between upper layers transmitting receiving transmitting receivingtm rlc entity tm rlc entity um rlc entity um rlc entity. Design and development of medium access control scheduler in. Performance analysis of handover measurements and layer 3. How the information is transferred 925 radio resource control rrc medium access control mac physical layer phy logical channels transport channels control measurements layer 3 layer 2 layer 1. Pdcp, rlc, mac layers together make up lte layer 2. Lte protocol stack layers lets have a close look at all the layers available in eutran protocol stack which we have seen in previous chapter. Commagility lte small cell phy evolution to release 10 white. If you understand the full details of all these procedures, i think you can say you understand at least 60% of the whole lte. So i decided to write a separate page for layer mapping in lte advanced. The lte radio interface for 3gpp release 8 was specified recently.
Lte supports the qpsk, 16qam, 64qam and 256qam modulation formats, and all of these will also be supported by nr. In essence, the choice of architecture is a tradeoff between. Sep 04, 2017 5g nr radio protocol stack layer 2 and layer 3 september 4, 2017 march 26, 2018 admin 5g 3gpp has released specification 38. Lte provides a packet switched model at the sap, but retains a circuit switched model at the phy. 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. Lte is the latest generation of the 3gpp standards. In terms of functionality, mac layer is the most complicated and the busiest layer. According to 1 the desired lte signal will be raised to 70. Rrc layer or pdcp sub layer with upper layers sap between upper layers transmitting receiving transmitting receivingtm rlc entity tm rlc entity um rlc entity um rlc entity am rlc. Drive testing provides an accurate realworld capture of the rf environment under a particular set of network and environmental. What is difference between acceptable, suitable and reserved cell. Lte protocol stackuser control plane protocol layers in lte. Dec, 2010 telecommunication design lte rlc sub layer systems engineering realtime and embedded systems rlc sdus are exchanged upper layer i. Long term evolution protocol overview nxp semiconductors.
As part of the data transfer service, the mac layer performs procedures such as scheduling requests, buffer status reporting, random access, and hybrid automatic repeat request harq. 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. Watanabe et al outdoor lte infrastructure equipment enodeb the following describes the respective functional parts of enodeb shown in figure 2. Lte phy lab is a complete implementation of eutra physical layer according to 3gpp release 8, with substantial elements of release 9 and 10. Overview of the 3gpp long term evolution physical layer 1 1 introduction the 3gpp long term evolution lte represents a major advance in cellular technology. Mar 24, 2010 lte advanced features lte advanced supports. Lte schedulers are part of layer 2 protocol stack and are one such module which can dramatically increase or decrease the performance of the system. Dimensioning of lte network description of models and tool, coverage and capacity estimation of 3gpp long term evolution radio interface abdul basit, syed masters thesis submitted in partial fulfillment of the requirements for the degree of masters of science in technology espoo, february, 2009. Jul 10, 20 this document provides a brief overview of the lte network architecture as the first technical document of lte area. Lte control plane layer covers upper layers,nas,rrc,phy and rf. Umts long term evolution lte technology introduction. Huawei lte for rail technical white paper page 5 deployed a tdd 1. Below diagram is a more ellaborated explaining eutran protocol stack.
In lte, information is organized as a function of frequency as well as time, using a resource grid. The lte layer 2 userplane protocol stack is composed of three sublayers, as shown in. Lte includes an fdd frequency division duplex mode of operation and a tdd time division duplex mode of operation. Pdf codeword to layer mapping for multiple layers mimo. There are two types of frame structure in the lte standard, type 1 and type 2. Enhancement of the utra optimisation of the utran architecture to ensure the continued competitiveness of the 3gpp technologies for the future lte was the first and only technology recognized by the next generation mobile network alliance to meet its broad requirements target deployment in 2010. Concepts of lte rf parametric receiver tests on phy layer. The design of the lte physical layer phy is heavily influenced by the requirements for high peak transmission rate 100 mbps dl50 mbps ul, spectral efficiency, and. On the physical layer layer one, lte can be the target of jamming attacks that aim to deny the service 5 8. As defined by 3gpp, lte layer 2 structure consists of pdcprlcmac layers. The radio resource control rrc protocol is used in umts and lte on the air interface. Lte tdd which is also referred to as td lte provides the long term evolution path for tdscdma based networks. This article describes the lte link layer protocols, which abstract the physical layer and adapt its characteristics to match the.
Lte phy layer characteristics service goals data transfer rate max dl. Lte uu eutran mme s11 serving s5 gateway pdn gateway. D rlc layer concatenate combine these multiple packets sdu into a singlehuge packets and add a rlc header containing the detailed informatione. In case of dispute, the reference shall be the printing on etsi printers of the pdf version kept on a specific network drive within etsi secretariat. Changes in the specification are limited to corrections and bug fixes. In reality, each of the arrows comes in one by one in sequence. There are some differences between the lte fdd and lte tdd modes that we identified. Mac multiplexes rlc links and manages scheduling and priority handling via logical channels. Tcpip layer, pdcp layer, rlc layer, mac layer, phy layer. Acknowledgements are sent periodically to the remote peer. Developing the core of the idle mode nrrc layer for 5g analyzing top blockers issues in 4g errc idlemeasurement and develop the fix. The key technology components of the nr physical layer are modulation schemes, waveform, frame structure, reference signals, multiantenna transmission and channel coding. I recommend you take this as an index page of a thick lte book.
The rlc pdu is received correctly, so mark the block for positive acknowledgement. This page on lte protocol stack describes user plane and control plane protocol stack layers in lte. Lte 5g ps senior software developer 032018present attending technical discussion for the new implementation in nrrc layer. Now lets take a close look at all the layers which are available in eutran protocol stack seen in previous chapter. It runs under matlab octave and can be used as a linklevel simulation tool or a goldenreference phy library. Lte physical layer which in itself is a very large and featurerich topic, particularly as there are different modes of operation fddtdd and different downlink. Transport channels are located between the physical layer and mac layer. Following table would give you the very simple snapshot of these procedures.
Pdcp layer is responsible for header compression and decompression of ip data, transfer of data userplaneorcontrolplane, maintenance of pdcp sequence numbers sns, insequence delivery of upper layer pdus at reestablishment of lower layers, duplicate elimination of lower layer sdus at re. Sounding reference signal when pucch or pusch is not scheduled, sounding reference signals srs are used to test the reception quality for uplink channeldependent scheduling and are transmitted in the last symbol of the subframe. Rlc acts as an interface between pdcp and mac layers and provides services to both. Lte user plane layer consists of upper layers,nas,pdcp,rlc,mac,phy and rf. This book focuses on lte with full updates including lte advanced to provide a complete picture of the lte system. As a matter of fact, the previous research efforts focused only on layer one or layer three protocols andto the best of our knowledgeno security analysis of data link layer layer two protocols exists to. Lte protocol architecture lte protocol architecture around phy logical channels.
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