Transcript LTE SYSTEM CONSTANTS INTRODUCTION

LTE
SYSTEM CONSTANTS
INTRODUCTION
System Constant
• Low layer configuration out of MO parameters
• Service aware and performance sensitive
• System constant type : Node Internal
parameters and RRC parameters
• System constant generally relate to : baseband
module, L1 layer format , Mac layer
scheduling ,etc
WH Trail Project System
Constant Configuration
ID
110
304
306
174
73
637
25
26
28
872
Value
-96
2
6
1
86
0
100
100
5
0
System Constant : 110
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preambleInitialReceivedTargetPower
Preamble initial received target power. Value in dBm.
Min: -120 Max: -90 Default: -110
WH trail eNB : -96
Note:
increase the preamble initial received target power will
request random access success with a better radio
environment , which will help to increase the UE
attach/cell-selection success rate
System Constant : 304
• dlMaxNrOfSePerTtiAndCell
• An upper threshold on the maximum number of
entities that the DL scheduler is allowed to schedule
per cell in one TTI.
• Min: 1 Max: 10 Default: 6
• WH Trail :2
Note:
In the DL, no advantage when time multiplex or
frequency multiplex .
System Constant : 306
• ulMaxNrOfSePerTtiAndCell
• An upper threshold on the maximum number of entities that the
UL scheduler is allowed to schedule per cell in one TTI.
• Min: 1
Max: 8 Default: 6
• WH Trail : 6
Note:
Suggestion value is max value . In the UL , frequency multiplexing
is a bit more efficient especially for cell edge . For more user in one
TTI , every user get less RB , so UE can concentrate all power
into less RB , then power per RB will be higher , finally the better
SINR will be got for higher throughput .
System Constant : 174
• periodicSrTimer
• Timer used to simulate the reception of SR
(Scheduling Request ) until we receive SRs from the
UE
• Min: 1
Max: 80
Default: 80 Unit: ms
• WH Trail: 1
Note:
Decrease the SR simulate time , help to decrease the
time cost on scheduling which will help to decrease
the E2E service delay .
System Constant : 73
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initialBufferSizeDefault
Target TB size assigned in response to SR when srCause is default
Min: 2
Max: 2400
Default: 86 Unit: Byte
WH Trail: 86
Note:
Manually set the SC value as the default , in another words this
manually setting is no real effect .
Smaller TB size caused shorter delay but cost more resource;
larger TB size cause larger delay but cost less resource .
System Constant : 637
• ulPreschedulingOn
• A flag to enable/disable the prescheduling feature in
the node. (0=disabled, 1=enabled)
• Default: 0
• WH Trail: 0
Note:
Pre-scheduling working without receiving scheduling
request (SR) , it help to improve E2E service latency .
System Constant : 25
• dlGinrForgettingFactorLarge
• Time domain DL GINR filtering parameter for a large forgetting
factor
• Min: 1
Max: 100
Default: 75 Unit: %
• WH Trail: 100
Note:
Increase the forgetting factor to decrease the frequency of link
adaption sensitivity . In some fast short time poor radio
environment , ‘dull’ scheduling keep may keep the throughput
more stable .
System Constant : 26
• dlGinrForgettingFactorSmall
• Time domain DL GINR filtering parameter for a small forgetting
factor
• Min: 1
Max: 100
Default: 70 Unit: 100%
• WH Trail: 100
Note:
Increase the forgetting factor to decrease the frequency of link
adaption sensitivity . In some fast short time poor radio
environment , ‘dull’ scheduling may keep the throughput more
stable .
System Constant : 28
• cqiReportTimerAperiodic
• The timer value when a new periodic CQI report should be
scheduled for a UE
• Min: 0
Max: 255
Default: 10 Unit:ms
• WH Trail: 100
Note:
More CQI report cost more PUSCH resource , in trail system
traffic load and radio environment is kept over a stable level ,
so most of CQI report carry the same information . So lengthen
the CQI periodic time help to decrease the PUSCH load and
release the resource for traffic
System Constant : 872
• deltaPsdRs2Tx
• Delta PSD in dB for the cell specific Reference Signal (CRS)
relative to the reference PSD when using 2 Tx antenna ports.
• Min: 0
Max: 2 Default: 2 (0=0dB;1=1.77dB;2=3dB)
• WH Trail: 0
Note:
Generally speaking , RS is 3dB higher . if it set to 0 , it will help to
reduce the intra-LTE interference .
System Constant Modify
Example:
• Modify the system constant
acc ENodeBFunction=1,SystemConstants=1 writeSystConst
306
(SC)
6
( value )
• Reset the system constant
acc ENodeBFunction=1,SystemConstants=1 resetSystConst
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