LTE Design Targets & SAE

8/2/2019 LTE Design Targets & SAE

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eNB functionality.Interfaces overview.


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Cell control and MME pool support

eNB owns and controls the radio resources of

its own cells.

Cell resources are requested by and grantedto MMEs in an ordered fashion. This

arrangement supports the MME poolingconcept. S-GW pooling is managed by theMMEs and is not really seen in the eNB.


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Mobility control

The eNB is responsible for controlling the

mobility for terminals in active state.

This is done by ordering the UE to performmeasurement and then performinghandover when necessary.


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Control and User Plane securityThe ciphering of user plane data over the radio

interface isterminated in the eNB. Also the ciphering andintegrityprotection of RRC signaling is terminated in the

eNB. Shared Channel handlingSince the eNB owns the cell resources, the eNB alsohandlesthe shared and random access channels used forsignaling andinitial access.


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Segmentation/ConcatenationRadio Link Control (RLC) Service Data Units (SDUs)receivedfrom the Packet Data Convergence Protocol (PDCP) layerconsist of whole IP packets and may be larger than thetransport block size provided by the physical layer.Thus, theRLC layer must support segmentation andconcatenation toadapt the payload to the transport block size. HARQA Medium Access Control (MAC) Hybrid AutomaticRepeatreQuest (HARQ) layer with fast feedback provides ameans forquickly correcting most errors from the radio channel.


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Scheduling

A scheduling with support for QoS providesfor efficientscheduling of UP and CP data. Multiplexing and Mapping

The eNB performs mapping of logical channelsonto transport channels.


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Physical layer functionalityThe eNB handles the physical layer such as

scrambling, Tx diversity, beamforming processingand OFDM modulation.The eNB also handles layer one functions like linkadaptation and power control. Measurements and reporting

eNB provides functions for configuring and makingmeasurements on the radio environment and eNB-internal variables and conditions. The collected datais used internally for RRM but can be reported forthe purpose of multi-cellRRM.


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RADIO RESOURCE CONTRO L (RRC)

Broadcast of System Information related to the non -

accessstratum Broadcast of System Information related to the accessstratum Paging

Establishment, maintenance and release of an RRCconnection

between the UE and E-UTRAN including: Allocation of temporary identifiers between UE and

EUTRAN

Configuration of radio resources for RRC connectionincluding SRBs


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Mobility functions including:o UE measurement reporting and control of the reportingfor inter-cell and inter-RAT mobilityo Inter-cell handovero UE cell selection and reselection and controlof cell

selection and reselection;o UE Context transfer between eNBs.o NAS direct message transfer to/from NAS

from/to UE .


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Documents

LTE Design Targets & SAE