01_ra47031en01gla0_introduction to inter layer mobility and measurementsv3

8/11/2019 01_RA47031EN01GLA0_Introduction to Inter Layer Mobility and MeasurementsV3

1/32

Introduction to Multi-Layer Measurements

RA47031EN01GLA0


2/32


RA47031EN01GLA0


3/32


RA47031EN01GLA0

After completing this module, you will be able to:

Explain radio measurements in LTE, WCDMA and GSM/EGPRS.

Explain general principles of inter-layer mobility.

Describe the principles of Hierarchical Cell Structures.


4/32


RA47031EN01GLA0


5/32


RA47031EN01GLA0

Key drivers for Inter-layer mobility

Mobile subscribers - moving across different coverage areas of different network

layers.

Network layers have different capacitiesbandwidth / throughput.

Potential for load balancing across layers.


6/32


RA47031EN01GLA0


7/32


8/32


RA47031EN01GLA0

HCS introduces an additional cell (re-)selection criterion.

In order to cope with UEs travelling fast through smaller cells (e.g. through micro or pico

cells), the cell reselection procedure can be performed towards bigger cells on lower priority

layers e.g. to macro cells so as to avoid unnecessary cell reselections.


9/32


RA47031EN01GLA0


10/32


RA47031EN01GLA0

The 3GPP priority concept could be considered an extension and generalisation of the

3G-specific HCS concept


11/32


RA47031EN01GLA0


12/32


RA47031EN01GLA0


13/32


RA47031EN01GLA0


14/32


RA47031EN01GLA0


15/32


RA47031EN01GLA0


16/32


RA47031EN01GLA0


17/32


RA47031EN01GLA0


18/32


RA47031EN01GLA0

From TS 25215 v9.2.0


19/32


RA47031EN01GLA0

UTRAN controls the measurements in the UE, either by Broadcasting system informationon the BCCH, and/or by Transmitting a Measurement Controlmessage on the DCCH.

If the UE is in the RRC idle mode, it receives relevant measurement information fromthe BCCH. SIB 3 contains parameters for cell selection and Reselection. In parallel, SIB11 is used to deliver measurement control information to the UE for the serving cell.SIB 3 & 11 are read and valid in the RRC idle state.

If the UE is in the CELL_FACH, CELL_PCH& URA_PCH, It is connected to one cell onlyand responsible for cell selection and Reselection. It retrieves the parameters for cellselection from SIB type 4. The measurement control information is broadcasted withSIB 12. SIB 4 & SIB 12 are read and valid, when the UE is in the CELL_FACH, CELL_PCH& URA_PCH sub-state. If SIB 4 resp. If SIB 12 is not broadcasted, then SIB 3 resp. SIB 11

parameters are used instead. In the sub-state CELL_DCH, the UE is not reading SIBtype 3/4 & 11/12. The parameters of SIB 12 (SIB 11, if SIB 12 is not available) can bestill valid in this state.

The RRC message Measurement Control can be transmitted to the UE, if a DCCH hasbeen setup between the UE and UTRAN. This message informs the UE about the typeof measurement, which has to be conducted. Each measurement command links ameasurement with a measurement identity, quantity, objects, reporting quantities,reporting criteria, type, etc.


20/32


RA47031EN01GLA0

How does a UE perform measurements after a transition in the CELL_DCH state?

Two cases have to be distinguished:

1. Transition from the RRC idle state to the CELL_DCH sub-state

In the RRC idle state, the UE retrieved the measurement control parameters from the

SIB type 11. Information Elements, which contain intra-frequency, inter-frequency,inter-RAT and traffic volume measurement system information, may be included in the

SIB 11. If they are included, the UE can send a measurement report, when a

measurement reporting criteria is fulfilled.

As soon as the UE receives a Measurement Control message including one of the above

mentioned measurement types, it replaces its internal stored data based on the SIB11

by the parameters delivered with the Measurement Control message.

2. Transition from the CELL_FACH to the CELL_DCH sub-state.

In the CELL_FACH sub-state, the SIB 12 (or SIB 11, if there is no SIB 12) is valid including

all relevant measurement control parameters. If the UE transits to the CELL_DCH sub-

state, the system information stays valid, as long as there was no Measurement Controlmessage, which replaces the parameters.

But what happens, if the UE was in the CELL_DCH sub-state, it has received

Measurement Control messages, and it then transits to the CELL_FACH sub-state?

In the CELL_FACH sub-state, the UE reads SIB 12 (SIB 11), and its measurement

control parameters become valid. But when the UE then transits back to the

CELL_DCH sub-state, the UE resumes with the measurements and associated

reporting, as they were stored before the transition to the CELL_FACH (or any other

RRC connected) sub-state.


21/32


RA47031EN01GLA0

The RRC message Measurement Controlis used to setup, modify or release a measurement in

the UE.

The UE gets information on how to perform a specific type of measurement. A

measurement is either conducted periodically or driven by an event. Then, the UE returns a

measurement report. The Measurement Control message is transmitted on a DCCH via an RLC entity in the

acknowledged mode. i.e. the UE is either in CELL_DCH or CELL_FACH.

If the setup of a measurement fails, the UE returns the RRC message Measurement Control

Failure. It is transmitted on a UL DCCH via a RLC entity in the acknowledged mode.

The RRC message Measurement Reportis specified to deliver measurement results from UE

to UTRAN (RNC). This message is transmitted on a DCCH. The RLC entity can be in the

acknowledged or unacknowledged mode. The RLC entity mode is set by the RRC message

Measurement Control. Measurement results can only be transmitted in the CELL_DCH or

CELL_FACH sub-state. CELL_DCH: If a reporting criterion is met, the UE transmits a Measurement Report. A

measurement identity identifies the measurement as specified by UTRAN. It includes

measurement quantities and identifies the measurement event.

CELL_FACH: Traffic volume measurements and positioning measurements are reported by

the UE. Intra-frequency measurements are reported via the RACH, whereby the UE learns

from the BCCH (SIB11 or SIB12) the maximum numbers of cells, it can report.

CELL_PCH or URA_PCH:UE must perform a cell update. Cell update cause is UL data

transmission. Then they are in the CELL_FACH state, where the Measurement Report can

be sent. The measurement report either holds traffic volume measurements or positioning

measurements.


22/32


RA47031EN01GLA0

With the RRC message Measurement Control, UTRAN commands the UE to performmeasurements on its behalf.

There is a set of different types of measurements which can be conducted: Intra-Frequency Measurements Inter-Frequency Measurements Inter-RAT Measurements UE-Internal Measurements Traffic Volume Measurements Quality Measurements UE Positioning Methods

As a consequence, a UE may be forced to conduct several different types of measurementssimultaneously. Each type of measurement is identified by an allocated MeasurementIdentity. Some measurements are not conducted continuously.

UTRAN tells the UE once, how to perform a type of measurement. Whenever necessary, it just

informs the UE to conduct the measurements of a measurement type by just telling it theassociated measurement identity.

Each measurement type comes with a measurement command: setup, modify, and release.

Finally, UTRAN informs the UE how to deliver the measurement reports: Delivery on an acknowledged or unacknowledged RLC, and Periodical or event triggered reporting.

In the RRC message Measurement Control, is the PhyCH information elements, where the UEcan gain DPCH compressed mode status information.


23/32


RA47031EN01GLA0


24/32


RA47031EN01GLA0

Source: Chris Johnson


25/32


RA47031EN01GLA0


26/32


RA47031EN01GLA0

List of detected preambles: The eNB shall report a list of detected PRACH

preambles to higher layers. Higher layers utilize this info for the RACH

procedure.

Transport BLER: The ACK/ NACKs for each transmission of the HARQ process

are reported to the MAC. Based on these ACK/NACKs the higher layers

compute the BLER for RRM issues.

TA: The eNB needs to measure the initial timing advance (TA) of the uplink

channels based on the RACH preamble.

Average RSSI: Measured in UL by eNB. It can be used as a level indicator for

the UL power control. The RSSI measurements are all UE related and shall be

separately performed for ( TTI intervals)

UL data allocation (PUSCH)

UL control channel (PUCCH)

Sounding reference signal (SRS)Average SINR: In UL the eNB measures SINR per UE. The average SINR can be

used as a quality indicator for the UL power control

UL CSI: channel state information per PRB for each UE. The CSI shall be the

received signal power averaged per PRB.


27/32


RA47031EN01GLA0

Seems that it has been removed: E-UTRA Carrier Received Signal Strength

Indicator, comprises the total received wideband power observed by the UE

from all RS symbols for antenna port 0, including co-channel serving and non-

serving cells, adjacent channel interference, thermal noise etc.


28/32


RA47031EN01GLA0

Thermal noise power and Received Interference Power are measured for the

same period of time.


29/32


RA47031EN01GLA0

The purpose of CSI feedback is to provide the eNodeB information about DL

channel state to help in the scheduling decision.

Compared to the WCDMA/HSPA, the main new feature in the channel feedback is the

frequency selectivity of the report

CSI is measured by the UE and signaled to the eNodeB using PUCCH or PUSCH

Channel state information in LTE can be divided into three categories:

CQI- Channel Quality Indicator

RI- Rank Indicator

PMI- Precoding Matrix Indicator

In general the CSI reported by the UE is just a recommendation

The eNodeB does not need to follow it

The corresponding procedure for providing UL channel state information is called

Channel Sounding; it is done using the Sounding Reference Symbols, SRS (not

considered in this presentation)


30/32


RA47031EN01GLA0


31/32


32/32


01_ra47031en01gla0_introduction to inter layer mobility and measurementsv3

Documents