8/9/2019 Types of UE Feedback
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Types of UE Feedback: The Measurement Report
Bill
22 Jan 2013 10:52 PM
• Comments 0
As UEs have become smarter and the air interface more
complex, the need for moredetailed communication between the UE and
the network has increased dramatically.The UE has become the eyes
and the ears of the radio access network. Its main goal isto find
the best cell and maximie performance with that cell.
To help the UE accomplish this, the e!ode" gathers several
pieces of information fromthe UE and then ad#usts its$ downlink
transmissions accordingly. The UE tells thenetwork what cells it
can see and how strong it can see them, its current
channelconditions, the current state of its$ memory buffer, which
antennas should betransmitting in the downlink, how many different
transmission streams can be supportedsimultaneously,
acknowledgements when data is received successfully, and any
otherinformation that the network wants to know.
This is the first in a series of blogs on these different types
of UE feedback. This blogwill focus on the measurement report. The
measurement report is the mechanism usedby the UE to tell the
network whatever results have been re%uested. Typically, these
aremeasurements of the surrounding cells. They can also include
re%uestedmeasurements of block error rate, transmit power and other
UE&based parameters. TheUE learns the re%uested information
using a measurement configuration.
'hen a UE is in (()&)*!!E)TE+ mode, this measurement
configuration is providedto the UE by means of dedicated signaling
typically using theRRCConnectionReconfiguration message.
The measurement configuration provided to the UE includes the
following parameters-
. /easurement *b#ects- the ob#ects on which the UE shall perform
themeasurements i.e. fre%uencies and cells. In other words- who
should the UEmeasure0 These include intra& and inter&
fre%uency neighbors, I(AT U/T1neighbors, I(AT 21/ neighbors and
I(AT )+/A3444 5(6+ and x(TTneighbors.
3. (eporting )onfigurations- the criteria used by the UE to
trigger the transmissionof a measurement report and the %uantities
that the UE includes in the report. Inother words- when should the
UE send a report0 This trigger can either beperiodical or
event&based.
7. /easurement Identities- an identifier that links one
measurement ob#ect with onereporting configuration. In other words-
the UE needs to keep track of the ob#ectsto be measured and their
specific triggers. The measurement identity is used asa reference
number in the measurement report.
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8. 9uantity configurations- the measurement %uantities and
associated filteringused for all event evaluation and related
reporting per (adio Access Technology.
:. /easurement gaps- periods of time that the UE may use to
performmeasurements while in connected mode.
The UE maintains a single measurement ob#ect list, a single
reporting configuration listand a single measurement identities
list. Any measurement ob#ect can be linked to anyreporting
configuration of the same (AT type.
As mentioned earlier, a report can be event&triggered
or periodical. An event&basedmeasurement report will be
transmitted when the criteria for any of the following eventshave
been met-
A1- 1erving )ell becomes better than a defined threshold
A2- 1erving )ell becomes worse than a defined threshold
A3- !eighbor cell becomes some offset better than the primary
cell
A4- !eighbor cell becomes better than a defined threshold
A5- 6rimary cell becomes worse than a defined threshold and a
neighbor becomesbetter than a second threshold
A6- !eighbor cell becomes some offset better than the serving
cell
B1- Inter&(AT neighbor becomes better a defined
threshold
B2- 6rimary cell becomes worse than a defined threshold and
inter&(AT neighborbecomes better than a second threshold
6eriodical measurement reports are sent based on the reporting
configuration. ;orinstance, it could be configured that the UE
report its$ transmit power every 3 seconds or its$ transport
channel block error rate every second. This is
operator&specific.
'e have discussed the vehicle used by the UE to tell the network
what it can see aswell as other operator&configured parameters.
Another piece of information that thenetwork needs to be successful
is some indication of the channel conditions at the UE.This will
help the network adapt its downlink transmission to match the UE$s
capabilityat that time. These channel %uality indicators or )9I$s
will be the sub#ect of the nextblog in this series.
Source- (adio (esource)ontrol =(()> 6rotocol specification
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