LTE RF Channel Troubleshooting Guide_v1.1

Security Level: interna

LTE RF Channel Troubleshooting Guide

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HUAWEI TECHNOLOGIES CO., LTD.

Huawei Confdential

 Abstract 

This document describes the common faults of the LTE LTE RF channels during the IF/RF maintenance, symptoms, diagnosis methods, data reuired for diagnosis by R!"#

%ontents 

Common RF Channel Faults



Uplink Channel Faults



Uplink Interference



eNodeB Fault Connection of ntenna



!o"nlink Channel Faults

%ommon RF %hannel Faults Interference+ Interference detection cell re-erse connection+ Inter. cell hando-er statistics

%rossed connection+ RTP difference bet*een main ! di-ersity



The common faults related to the RF channels are uplin' channel fault, uplin' interference, e(ode) fault connection of antenna, do*nlin' channel fault, do*nlin' antenna fault, This document describes the analysis procedure beginning from problem symptom to conclusion#

 Antenna fault+ # 01R alarm 2# Passi-e intermodulation interference $# RTP difference bet*een main ! di-ersity or lo* RTP

! channel "ailu#e mode de$c#i%tion 1ymptom and Alarm

ALD !ault

U%lin) Inte#"e#enc e

u%lin) "ailu#e o" ALD*antenna line De+ice

AL-/0(// ! Unit 1 Channel TW&2SSI TW&2SSI Un3alanced

Ala#m li$t SSI t#ace data

M2000 M20 00 、 WEB WEBLMT LMT

downlin) "ailu#e AL-/0(/4 ! Unit 5SW Th#e$hold o" ALD*antenna C#o$$ed line De+ice

Ala#m li$t one)e6 fle lo' o" U

M2000 M20 00 、 WEB WEBLMT LMT

inte#nal Inte#"e#ence

SSI t#ace Inte#"e#ence Inte#"e#ence Detect -onito#in' 3#oad3and online "#e7uenc6 $can

M2000 M20 00 、 WEB WEBLMT LMT

$t#on' inte#"e#ence inte#"e#ence will will lead to a cell 9&I decline.

SSI t#ace Inte#"e#ence Inte#"e#ence Detect -onito#in' 3#oad3and online "#e7uenc6 $can

M2000 M20 00 、 WEB WEBLMT LMT

the local cell and a neighbor cell that has no o-erlapping co-erage are in-ol-ed in hando-er#

Hando+e# 9&I en'inee# %a#amete#

M2000 M20 00 、 OMS OMSta tar r

AL-/0(// ! Unit 1 Channel TW&2SSI TW&2SSI Un3alanced. the local cell and a neighbor cell that has no o-erlapping co-erage are in-ol-ed in hando-er#

Hando+e# 9&I en'inee# %a#amete#

M2000 M20 00 、 OMS OMSta tar r

Ala#m li$t 9&I o" acce$$ #ate one)e6 fle lo' o" U

M2000

E8te#nal Inte#"e#ence e+e#$e !ault Connection o" Antenna

!ault Connection o" Antenna C#o$$ !ault Connection o" Antenna

U%lin) "ault o" U Channel "ault Downlin) "ault o" U

Inte#modulation inte#"e#ence dec#ea$ed dec#ea$ed th#ou'h%ut and hando+e# $ucce$$ #ate

AL-/0(/: ! Unit 1 Channel TW&2SSI TW&2SSI  Too  Too Low. Low.

AL-/0(/; ! Unit T1 Channel Gain Out o"  T#an$mit  T#an$mit %owe# te$t data o" U< an'e. one)e6 fle lo' o" U

M2000

%ontents 

Common RF Channel Faults



Uplink Channel Faults



Uplink Interference



eNodeB Fault Connection of ntenna



!o"nlink Channel Faults

4plin' %hannel Faults When an u%lin) channel "ault occu#$, the $6m%tom$ a#e de'#aded cell 9&I, ! Unit 1 Channel TW&2SSI Too Low ala#m, and ! Unit 1 Channel TW&2SSI Un3alanced ala#m. I. Ha#dwa#e "ault Choo$e Monitor = Signaling Trace  = Signaling Trace Management on the -/;;; o# We3 L-T. L-T. In the na+i'ation t#ee, choo$e Cell Performance Monitoring  = Interference RSSI RSSI Statistic Detect Monitoring. The 1A SSI and 1> SSI a#e di$%la6ed in a ta3le, a$ $hown in the ne8t %a'e. Chec) Chec ) whethe# the +alue$ in thi$ ta3le a#e le$$ than the SSI +alue$ unde# em%t6 load. The th#e$hold "o# #e%o#tin' TW&2SSI TW&2SSI too low ala#m i$ –::? d>m. The SSI unde# em%t6 load i$ calculated a$ "ollow$@

–:?B:;lo'>WBN! whe#e >W >W i$ the 3andwidth in H and N! i$ the noi$e "acto# o" the ! module and it$ +alue i$ 3etween / to /.(. A$$umin' an LU /.0G /T/ cell o" /; -H 3andwidth, the SSI unde# em%t6 load i$ calculated a$ "ollow$@  –:?B:;lo'*/;:;0B/.(F –4.? d>m

4plin' %hannel Faults

4plin' %hannel Faults II# Passi-e intermodulation The #oot cau$e o" inte#modulation i$ nonlinea#it6 o" the channel$. An #ule to mea$u#e the nonlinea#it6 o" an antenna $6$tem i$ inte#modulation $u%%#e$$ion. !o# a linea# $6$tem, the out%ut to a / $i'nal in%ut i$ al$o / $i'nal$. Howe+e#, "o# a nonlinea# $6$tem, a / $i'nal in%ut 'ene#ate$ new "#e7uenc6 com%onent$ )nown a$ inte#modulation di$to#tion. The %henomenon o" 'ene#atin' new "#e7uenc6 com%onent$ i$ called inte#modulation. I" the inte#modulation di$to#tion "all in the #ece%tion 3and and inc#ea$e the u%lin) inte#"e#ence o# TW&, TW&, inte#modulation inte#"e#ence inte#" e#ence a#i$e$.

4plin' %hannel Faults The follo*ing figure sho*s the intermodulation product of signals of ) band*idth band*idth after passing a nonlinear system#

289f/ a#e in+ol+ed in hando+e# A/ and >/ a#e in+ol+ed in hando+e# A: and >/ ha+e no o+e#la%%in' co+e#a'e A/ and >/ ha+e o+e#la%%in' co+e#a'e A: and C: a#e in+ol+ed in hando+e#

C: >ecau$e the cell$ that ha+e no o+e#la%%in' co+e#a'e a#e not 3e conf'u#ed conf'u#ed nei'h3o# #elation , $o two "ault connection cell$

A/ and C: a#e in+ol+ed in hando+e# A/ and C: ha+e no o+e#la%%in' co+e#a'e A: and C: ha+e o+e#la%%in' co+e#a'e

A1 an A! "ave cross connection of antenna

e(ode) Fault %onnection of Antenna solution of re-erse %onnection of Antenna it is is common *ay to analye the hando-er hando-er success rate, ifif the cell ha-e re-erse connection of antenna, it happened in t*o cells *hich ha-e no o-erlapping co-erage and configure the neighbor relation# another cell that has o-erlapping co-erage *ith neighbor cell doesnHt hando-er#

solution of %ross %onnection of Antenna Antenna the RA and R) of the RR4 must belong to the same cell, in *hich case the the direction and co-erage area of RA are the same as those of R) to ensure RTP balance# If RA and R) of the RR4 are connected to different sectors, sectors, the problem of RTP unbalance occurs and the RTP unbalance alarm is reported# If the RTP unbalance alarm is caused by incorrect connection of RA or R) to another antenna, the symptoms are as follo*s+   At least t*o cells in t he same site sit e report an RT P unbalance alarm# a larm#  The RTP change of RA is independent of that of R)#  The RTP change of different sectors is similar#

%ontents 

Common RF Channel Faults



Uplink Channel Faults



Uplink Interference



eNodeB Fault Connection of ntenna



!o"nlink Channel Faults

"o*nlin' %hannel Faults 





If the do*nlin' channel gain is abnormal, AL>.2@27 AL>.2@27 RF 4nit T %hannel ain ut of Range is reported# Principles+ If the actual gain of the RF unit T channel de-iates from the standard gain by more than 2#@ d), this alarm is reported# Impact+ Large gain causes co-erage c o-erage o-erlap# 1mall gain causes co-erage holes, or interruption of the ser-ices in the RF unit#

  Troubleshooting I# Run the R&T BR!'(R)FF command BR!'(R)FF command to reset the RR4, eBcluding the possibility that the problem is caused by soft failure# f ailure# %hec' *hether the alarm is cleared# II# If the t he alarm is not cleared, replace the RR4 and return the replaced RR4 to R!" department for further analysis#

"o*nlin' %hannel Faults I" the 5SW +alue i$ a3no#mal, a 5SW ala#m i$ #e%o#ted. I" the ALD com%onent$ connection and match a#e %oo#, mo$t o" the out%ut mic#owa+e %owe# i$ not emitted 36 the antenna 3ut i$ #eected 3ac). La#'e #eection %owe# dama'e$ the module and cau$e$ #e+e#$e 3#ea)down in wo#$t ca$e$. 5SW i$ an e8%onential "unction o" the "o#wa#d  #e+e#$e %owe#$ and i$ inde%endent o" the in%ut $i'nal %owe#. The de"ault 5SW ala#m th#e$hold i$ /.; and $e+e#e 5SW ala#m th#e$hold can 3e $et 36 --L command -OD U. U. To a+oid module dama'e, i" the $e+e#e 5SW ala#m i$ #e%o#ted, the T1 channel $witched oJ o# de'#ade Kd> out%ut %owe#.and.  The#e"o#e,  The#e"o#e, i" the the $e+e#e $e+e#e 5SW ala#m ala#m i$ #e%o#ted, #e%o#ted, the cell %e#"o#mance %e#"o#mance dete#io#ate$ o# the cell i$ una+aila3le. una+aila3le.

"o*nlin' %hannel Faults

If a 01R alarm is reported, the possible causes are+ # The 01R alarm threshold is lo*# 2# The Cumper is incorrectly i ncorrectly installedG the feeder line is distorted, di storted, bent, damaged, or loosened# $# The 01R detection circuit of the RF unit or the hard*are of the RF unit is faulty#

"o*nlin' %hannel Faults Troubleshooting procedure Run the L&T RRU command RRU command to uery the 01R alarm threshold of the RF unit and chec' the appropriateness appropriateness of the 01R threshold# If the threshold is inappropriate, run the *)! RRU command to modify the threshold# sho*n in the right table is ratio of the reflected po*er for for different different 01R# *hen the 01R is less than #@,the ratio of the reflected po*er is relati-ely small *hich has not a significant impact on co-erage performance # *hen the 01R is more than 2#7,the ratio of the reflected po*er is relati-ely large , *hich has ob-ious impact on co-erage performance# performance# The recommended configure threshold is + 01R alarm post.processing threshold 97#: ; $7 01R alarm threshold97#7 :;27

VSWR 

Reflection power ratio

3.0

25%

2.0

11%

1.8

8%

1.5

4%

1.4

2.8%

1.3

1.7%

1.2

0.8%

"o*nlin' %hannel Faults 0ie* the 01R -alue contained in the alarm #

If the 01R is greater than 77 9unit+ 7#:, the reflection po*er is large# Run the !&' +&(R command +&(R command to uery the current 01R# Run the &TR +&(RTE&T command +&(RTE&T command to perform 01R test# (ote that the 1TR 01 RTE1T operation interrupts interrupts the ser-ice# It is common use for off.line test#

Repeat step for fi-e fi-e times at an inter-al of 2 minutes# %hec' *hether the &TR +&(RTE&T command +&(RTE&T command output sho*s significant fluctuation of the 01R# If yes, yes, *e can suspect that the AL" components is loosely connected#

"o*nlin' %hannel Faults

The difference bet*een !&' +&(R and +&(R and &TR +&(RTE&T + +&(RTE&T + "1P 01R+ it is online 01R, The uery does not affect the ser-ice, the uery band ha-e difference *ith current band, so the accuracy is not high, it *ould only as the reference# 1TR 01RTE1T+ it is offline 01R, it is tested at the same freuency as current %ell, the accuracy is much high than online 01 R , so it is used to confirm *hether the RR4 has 01R problem#

"o*nlin' %hannel Faults The procedure of onsite inspection is as follo*s+ :)ased on the net*or' planning data, chec' *hether the band of RF unit is consistent *ith the the AL" components such asantenna, feeder, Cumper, combiner, di-ider, filter, and T>A# 2: Replace one segment of the AL" at a time, and run the &TR +&(RTE&T command to chec' the result# Incorrect connection, damaged cable, or *ater in the Coint can cause standing *a-e# $: After chec'ing the AL" connection or replacing the AL", run the &TR +&(RTE&T command +&(RTE&T  command to chec' the result#  If the command output sho*s that the 01R is normal, reset the RR4 to clear the alarm# Troubleshooting Troubleshooting ends#  If the command output sho*s that the 01R still eBceeds the threshold, replace the RR4 to chec' *hether the RR4 is faulty# Return the replaced RR4 to R!" department for further analysis#

Common en'inee#in' $umma#6 ta3le o" t#ou3le$hootin' Ty#e of fault 5SW o" antenna feeder 

Detection met"os  Th#ou'h online （ DS& 5SW ） detection o# oine *ST 5SWTESTdetection 5SWTESTdetection to te$t 5SW

Remar$   Oine 5SW detection inte##u%t the cell $e#+ice

-ethod :@In the idle $e#+ice %e#iod, $ta#t $imulated load, t#ac)in' cell SSI o# cell inte#"e#ence i" the SSI o" cell cell ha$ 3een o3+iou$l6 chan'ed 3e"o#e and intermodulation a"te# $imulated loaded, it i$ indicated that the cell of antenna feeder  ha$ inte#modulation. -ethod / ： $ta#tin' 3#oad3and online "#e7uenc6 $can 36 We3L-T o# -/;;; could anal6e the inte#modulation. C#o$$ Fault %onnection of  Antenna in eNode>

-ethod :@the c#o$$ "ault connection o" antenna could 3e anal6ed acco#din' to en'inee# %a#amete#$ and cell hando+e# #ate . -ethod /@--L Command ： ST COS!EEDTST （ #ecommended in idle $e#+ice ）

e+e#$e Fault %onnection of  Antenna in eNode>

-ethod / ： fled te$t * it i$ #ecommended in the 3e'innin' o" the netwo#) con$t#uction  -ethod /@the e+e#$e "ault connection o" antenna could 3e anal6ed acco#din' to en'inee#

ST COS!EEDTST inte##u%t the cell $e#+ice

In"o#mation Collection o" U "ault detail descri#tion o! t$e #roblem #$enomenon must $a%e detail descri#tion #roblem t$rou&$ te't( screens$ots or !ault)site #$oto*

Mandator+

Failure site ,-.

For commercial sites( need to !eedback t$e !ault site O#tional recent ,-. data

T+#e o! RR/

T$e !ailure module %ersion( bands( t+#e( suc$ as t$e Mandator+ MR/( MRR/( DRF/( RR/( MRF/ etc*

1etork o! 3LD eui#ment

t$e t+#e o! 3LD netork( $et$er multi)mode base station( antenna surroundin&*

Mandator+

"on!i&ure !ile o! e1odeB

"on!i&ured !ile o! e1odeB

Mandator+

One)ke+ !ile o! LM-T

One)ke+ !ile o! LM-T

Mandator+

One)ke+ !ile o! RR/

One)ke+ !ile o! RR/

Mandator+

One)ke+ !ile o! LBB-

One)ke+ !ile o! LBB- $ic$ connect it$ RR/

O#tional

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