tma systems for gsm and dcs(20091214)
DESCRIPTION
GSMTRANSCRIPT
TMA Applicationfor GSM System
Jin Gang MeiJin Gang Mei
Project Manager
Comba Telecom Ltd
© 2009 Comba Telecom, All Rights Reserved2
Topics
1. Tower-Mounted Amplifiers (TMA)2. TMA Components3. Benefits of TMA System4. Comba TMA Systems5. Link Balance with TMA6. Case Study - TMA SItes Selection7. TMA Installation
© 2009 Comba Telecom, All Rights Reserved3
What is a TMA System?
What is a TMA?• A Low noise receiver
amplifier used to improve the up-link sensitivity of the BTS.
Why is it necessary?• To extend and maximise
coverage by providing network balance
• To improve the quality of service to the subscriber
• To reduce the infrastructure cost to the operator
BTS
TMA
PowerSupply
BTS
Antenna
TMA
LNA
© 2009 Comba Telecom, All Rights Reserved4
TMA Installation
Service Antenna
TMA
BTS
© 2009 Comba Telecom, All Rights Reserved5
Increasing Cell Radius
• A TMA located on the tower top can increase uplink range by 55% and bring the cell into balance.
• GSM,DCS & WCDMA systems virtually demand TMAs due to higher path loss and limited mobile transmit power.
• The risk of *not* using a TMA is lost calls near the cell boundary.
DownlinkDownlink
UplinkUplinkwithout TMAwithout TMA
UplinkUplinkwith TMAwith TMA
© 2009 Comba Telecom, All Rights Reserved6
Sensitivity Improvement
LNA
BTS Receiver
BTSLNANF _
Feeder and Jumpers
dBLf 4=
-90
-100
-110
-130
dBm
-12010 dB
3 dB
Thermal Noise Noise Figure in BTS
AB C
BTSLNAG _
Without TMAWithout TMA
dBNF BTSLNA 3_ =dBG BTSLNA 14_ =
6 dB
BTS Receiver
Feeder and Jumpers
dBLf 4=
-90
-100
-110
-130
dBm
-12010 dB
Thermal Noise Noise Figure in Active Component
AC D
5.5 dB
LNALNA
TMANF TMAG
TMA
BBTSLNANF _
With TMAWith TMA
dBNFTMA 5.1=dBGTMA 11=
8.5 dB
dBNF BTSLNA 3_ =dBG BTSLNA 6_ =
8.5 dB
BTSLNAG _
© 2009 Comba Telecom, All Rights Reserved7
Tower-Mounted Amplifiers (TMA)
Advantages of TMA• Extended network coverage
– Remove up-link limitation• Improved Network Quality
– Fewer dropped calls– Higher call throughput– Satisfied subscribers
• Reduces MS output power– Longer battery life and
less interference.• Reduced infrastructure cost
– Fewer sites
Disadvantages• Reduces the overall Mean
Time Between Failure (MTBF).
• Maintenance and supervision is more difficult.
• Lower intermodulation performance of site.
© 2009 Comba Telecom, All Rights Reserved8
What comprises a TMA System?
It consists of 3 main components:
• Tower Mounted Amplifier– A low noise amplifier with bypass switch.
• Current Injector or Bias Tee – Facilitates injection of dc power onto the RF cable.
• Power Distribution & Management (PDM)– provides power and alarm handling up to 6 TMAs.
© 2009 Comba Telecom, All Rights Reserved9
Tower Mounted Amplifier – Dual Duplex
ANT1 Port
BTS1 Port
Bias Tee
BTS PDM
+12VAlarm
To BTS
Bias Tee
Tx Fil
LNA LNA
Rx1 Fil
Rx2 Fil
Rx-Bypass
Bias Tee
Tx Fil
LNALNA
Rx1 Fil
Rx2 Fil
LNA
0 A
larm
Gen
erat
ion
Uni
t Rx-
BypassLN
A1
Ala
rmG
ener
atio
n U
nit
ANT0 Port
Bias Tee
BTS0 Port
To Antenna To Antenna
ANT1 Port
BTS1 Port
Bias Tee
BTS PDM
+12VAlarm
To BTS
Bias Tee
Tx Fil
LNA LNALNALNA LNALNA
Rx1 Fil
Rx2 Fil
Rx-Bypass
Bias Tee
Tx Fil
LNALNA LNALNALNALNA
Rx1 Fil
Rx2 Fil
LNA
0 A
larm
Gen
erat
ion
Uni
t LN
A0
Ala
rmG
ener
atio
n U
nit
Rx-Bypass
LNA
1 A
larm
Gen
erat
ion
Uni
t LN
A1
Ala
rmG
ener
atio
n U
nit
ANT0 Port
Bias Tee
BTS0 Port
To Antenna To Antenna
© 2009 Comba Telecom, All Rights Reserved10
Tower Mounted Amplifier – Single Duplex
Bias Tee
Tx Fil
ANT Port
BTS Port
Bias Tee
BTS PDM
+12VAlarm
To BTS
LNALNA LNALNALNALNA
Rx1 Fil
Rx2 Fil
LNA
Ala
rmG
ener
atio
n U
nit
LNA
Ala
rmG
ener
atio
n U
nit
Rx-Bypass
To Antenna
© 2009 Comba Telecom, All Rights Reserved11
TMA Naming Convention
• TA-G12FD– Twin GSM900 TMA with
fixed uplink gain of 12dB
• TA-C12FS03– Single CDMA850 TMA with
fixed uplink gain of 12dB– ’03’ denotes 3rd design
version
• TA – Tower Amplifier
• C – CDMA850• G – GSM900• E – EGSM900• D – DCS1800• P – PCS1900• W – WCDMA
• 12 – Uplink Gain 12dB• F – Fixed Gain• S – Singe TMA• D – Twin TMA
© 2009 Comba Telecom, All Rights Reserved12
TMA Solutions
TMA
Type CDMA GSM EGSM DCS UMTS(AISG1.1)
Single 12, 18dB 12dB 12dB 12dB 12dB
Twin - 12dB 12dB 12dB 12dB
TA-G12FSGSM900 Single TMA
TA-D12FDDCS1800 Twin TMA
TA-W12FDAWCDMA TMA AISG1.1
© 2009 Comba Telecom, All Rights Reserved13
Single TMA Dimension - TA-G12FS02
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Dual TMA Dimension – TA-D12FD
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Dual TMA Dimensions – TA-P12FD
250383.6
224
58.5
90.5
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GSM1800 Dual Duplex TMA – TA-D12FD
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GSM1800 Dual Duplex TMA – TA-D12FD
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Power Distribution Management Unit (PDM)
• Converts BTS voltage (-48VDC or +24VDC) to +12 VDC.• Power distribution to the TMA via a CIN.• Supervises TMA current consumption.
+12V +12V
BTS Sector
TMA
-48V
TMA
Tx/Rx Rx
Antenna
ANTANT
BTS BTS To BTS AlarmRelay Contacts
BT
Power Distribution & Management
© 2009 Comba Telecom, All Rights Reserved19
Power Distribution Management Unit (PDM)
Unit A Unit B Unit C
-48V+24V GNDVIN
ALARM1Vout A Vout B POWER
ALARM2 ALARM1Vout A Vout B POWER
ALARM2 ALARM1Vout A Vout B POWER
ALARM24515
2
482
© 2009 Comba Telecom, All Rights Reserved20
Power Distribution Management Unit (PDM)
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Bias Tee (Current Injector)
• Injects dc power onto the feeder for the TMA.
• Acts as a surge protector.• N or 7/16 connectors in any
combination.• IP65, weather protected for
outdoor environment.
DCInput
TMA BTS
Spark gap
λ/4 λ/4
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Current Injector – Outline Drawing
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Current Injector – BT-Mx
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Single Sector Cell with V-Pol Antennas
BTS
PDM
Single TMA
Bias tee
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Single Sector Cell with X-Pol antenna
Tx/Rx Rx
Twin TMA
BTS
PDM
Bias Tee
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3 Sectors Cell with V-Pol
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3 Sectors Cell with X-Pol Antennas
Tx/Rx Rx
Twin TMA
Tx/Rx Rx
Twin TMA
Tx/Rx Rx
Twin TMA
© 2009 Comba Telecom, All Rights Reserved28
Uplink Sensitivity Improvement with TMA
© 2009 Comba Telecom, All Rights Reserved29
What is Noise?
• Noise comes from unavoidable thermal movements in all material. • This creates a “noise floor” that depends on:
– Boltzmann’s constant, k = 1.38 x 10-23 [K-1] – Temperature, T (normally 20 deg C = 293 K)– Bandwidth, B (normally calculated in one Hertz)
• This gives us the noise formula
• Noise power spectral density is the noise per Hz of bandwidth
• At room temperature,
• For 200kHz wide GSM channel, the thermal noise power is
( ) dBW log10 kTBPn =
( ) HzdBW log10 0 kTN =
HzdBm 1740 −=N
dBm 121−=nP
© 2009 Comba Telecom, All Rights Reserved30
Amplifier Gain and Noise Figure
• The noise figure, NF, of a device is defined (in dB) as the difference in SNR between the i/p and o/p signals.
• In linear units, it is called noise factor, F.
( ) ( )( ) ⎥⎦
⎤⎢⎣
⎡=
o
i
NSNSdBNF log10
Inputsignal Amplifier Output
signal
Gain = 5 dBNoise Figure = 2 dB
Thermal noisefloor
-110 dBm
Output signallevel-105 dBm
-121 dBm
-114 dBm
S/N = 9 dB
Power
Freq
Thermal noisefloor
-121 dBm
-110 dBmInput signal
level
S/N = 11 dB
Power
Freq
© 2009 Comba Telecom, All Rights Reserved31
Calculation of Receiver Sensitivity
• Thermal noise floor is given by
• The noise at the input of a receiver is known as the receiver noise floor, and is given by
where NFr is the noise figure of the receiver
• The sensitivity of a receiver is given by
• For GMSK modulation, we need a detection SNR of 9 dB• If the receiver noise figure is 2 dB, then the sensitivity is
( )( ) dBm 30log10
dBW log10
+==
kTBkTBPn
( ) dBW log10 rnr NFkTBP +=
SNRNFPSNRPP rnnrsens ++=+=
dBm 11092121 −=++−=sensP
© 2009 Comba Telecom, All Rights Reserved32
NF in Cascade Amplifier Stages
InputAmp 1
Output
G1, NF1
Amp 2 Amp 3
G2, NF2 G3, NF3
• The overall noise figure, NFT, of a number of cascaded devices can be calculated from Friis' equation:
where gain and noise factor values are in linear units.
⎟⎟⎠
⎞⎜⎜⎝
⎛⋅⋅⋅+
−+
−+= 11log10
21
3
1
21
GGF
GFFNFT
• The noise factor of the first stage contributes significantly to the overall noise figure.
© 2009 Comba Telecom, All Rights Reserved33
TMA RF Impact
BPF
TMA
Gain + NF
Signal 1
Signal 2
TMA input Noise Thermal Noise floor
SNR 2
SNR 1
LNA
Signal at antennaterminal
Signal in to feeder
Signal afterfeeder losses
No TMA
Signal after TMA
Signal afterfeeder losses
With TMA
© 2009 Comba Telecom, All Rights Reserved34
BTS without TMA
Example 1• Consider a GSM 1800 BTS
uplink arrangement as shown. • Assuming that a detection
SNR of 9 dB is needed, determine the minimum BTS receive power level needed (after the antenna).
RX
Detection
DuplexerBTS
NF = 5 dBS/N = 9 dB
Loss = 1 dB
Loss = 3.3 dB
Jumper
Jumper
Feeder cable7/8", 50 m
Loss = 0.5 dB
Loss = 0.5 dB
Antenna
Received power
RX sensitivity
© 2009 Comba Telecom, All Rights Reserved35
BTS without TMA
Solution
• Thermal Noise Floor
• Receiver sensitivity
• Received power
[ ]
dBmdBW
kTBPn
121 151
102002901038.1log10
log10323
−=−=
×⋅⋅×=
=−
dBmPsens
07159121
−=++−=
dBmPr
01.715.03.35.01107
−=++++−=
RX
Detection
DuplexerBTS
NF = 5 dBS/N = 9 dB
Loss = 1 dB
Loss = 3.3 dB
Jumper
Jumper
Feeder cable7/8", 50 m
Loss = 0.5 dB
Loss = 0.5 dB
Antenna
Received power
RX sensitivitysensP
rP
© 2009 Comba Telecom, All Rights Reserved36
BTS with TMA
Example 2• Consider the BTS receive
system with TMA. • Determine the improvement in
the minimum BTS received power.
RX
Detection
DuplexerBTS
S/N = 9 dB
Loss = 3.3 dB
Received power
RX sensitivity
NF = 1.4 dBGain = 12 dB
Loss = 0.3 dB Overall
Loss = 0.5 dB
NF = 5 dB
Loss = 1 dB
Loss = 0.5 dB
Loss = 0.5 dBNoise Figure
© 2009 Comba Telecom, All Rights Reserved37
BTS with TMA
Solution
• Overall noise figure, NFT
• Received power
• Improvement in sensitivity
[ ]
dB 12.305.2log10
5.017.038.1log101010
11010
11010log10 106.51012
105
1012
106.5104.1
==
++=
⎥⎦
⎤⎢⎣
⎡ −+
−+=
dBmPr
08.415.012.39121
−=+++−=
( ) dB 70.64.1087.101 =−−−=
RX
Detection
DuplexerBTS
S/N = 9 dB
Loss = 3.3 dB
Received power
RX sensitivity
NF = 1.4 dBGain = 12 dB
Loss = 0.3 dB Overall
Loss = 0.5 dB
NF = 5 dB
Loss = 1 dB
Loss = 0.5 dB
Loss = 0.5 dBNoise Figure
© 2009 Comba Telecom, All Rights Reserved38
Sensitivity Improvement
Receiver Sensitivity. (TMA NF 1.5 dB, BTS NF 5 dB)
-111.00
-109.00
-107.00
-105.00
-103.00
-101.00
-99.00
-97.00
1 2 3 4 5Cable loss (dB)
Nom
inal
det
ecta
ble
sign
al
No TMA
TMA Gain 6 dB
TMA Gain 12 dB
TMA Gain 15 dB
© 2009 Comba Telecom, All Rights Reserved39
GSM1800 TMA Trial SiteCase Study
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Performance Measurement
Handover Request Ratio due to• Uplink Signal (UL_RxLev)• Downlink Signal (DL_RxLev)• Uplink Quality (UL_RxQual)• Downlink Quality (DL_RxQual)• Power Budget (PB)
Drop Call Measurements• TCH Drop Call Rate (Drop #2)• Subscriber Perceived Drop Call Rate (Drop #3)• ErlangMin/Drop
© 2009 Comba Telecom, All Rights Reserved41
Summary of Performance
• The uplink is stronger than the downlink (more HO due to DL).• Majority of the handovers are due to better servers (HO due to PB).• Generally, uplink quality has improved (lesser HO due to UQ).• Drop calls has reduced.• ErlangMin/Drop has increased to 85.81.• Neighbouring cells’ performance would also improve
– because calls that are handed over to them are due to better signal strength.
• Coverage or whether a subscriber can initiate a call is dependent on the downlink signals. In what used to be boundary coverage areas, the subscribers can now make AND expect to finish the calls.
© 2009 Comba Telecom, All Rights Reserved42
Guidelines on Site Selection for TMA
• High TCH Drop Call Rate or High HO Failures,they are due to leak of uplink signal strength
• HO reason or Drop reason is due to poor uplink signal level and/or quality
• Handover due to Power Budget is low (~ 50% or less)• High feeder loss (> 2dB)• High BTS output power or low combining loss ,the downlink
coverage is big enough)• Link is “breaking” on uplink the uplink coverage is limited• No congestion in Both SDDCH and TCH
© 2009 Comba Telecom, All Rights Reserved43
Case of Site Selection for TMA
• Analysing the following statistic of BSC 40, the duration is more than 1 week
• filter the site satisfied 1. DL_Lev-UL_Lev>02. Number of handover attempts due to uplink received strength (on
SDCCH)=03. %age of HO Attempts due to UL Lev>20%
{%HO_ATTEMPT_UL_LEV_LOW=HO_ATTEMPT_UL_LEV_LOW/( HO_ATTEMPT_UL_LEV_LOW+ HO_ATTEMPT_DL_QUAL_LOW+ HO_ATTEMPT_PBGT+ HO_ATTEMPT_DL_LEV_LOW+ HO_ATTEMPT_UL_QUAL_LOW )}
4. TCH in congestion rate(include handover)(%)=05. TCH in call drop rate(exclude handover)(%)>0;TCH in call drop
rate(include handover)(%)>06. Subscriber Perceived TCH Drop Call Rate >1%(Subscriber
Perceived TCH Drop Call Rate=TCH in call drop rate(include handover)(%))
© 2009 Comba Telecom, All Rights Reserved44
Sites of Priority 1
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Sites of Priority 2
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Principle of Priority
• Priority 1 (P1): Sites with – HO Request due to weak UL Signal Strength > 20%, and Subscriber
Perceived TCH Drop Call Rate > 3%• Priority 2 (P2): Sites with
– HO Request due to weak UL Signal Strength > 20%, and Subscriber Perceived TCH Drop Call Rate 2% to 3%
• Priority 3 (P3): Sites with – HO Request due to weak UL Signal Strength > 20%, and Subscriber
Perceived TCH Drop Call Rate 1% to 2%
• If there is a “1” mark on the either one of the 3 columns, it means that one of the above criteria is satisfied, and a TMA is recommended based on the priority level.
• CMPak’s Drop Call target is < 3% for rural sites (low traffic) and <2%for urban sites (high traffic).
© 2009 Comba Telecom, All Rights Reserved47
TMA System Installation
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Connecting TMA to Antenna
• ANT port connects to Antenna port• BTS port connects to feeder cable
leading to BTS• TMA does not work in reverse
connection• Reverse connection will short DC
current supply short to groundANT0 ANT1
BTS0 BTS1
Tx/Rx Rx
Antenna
BTS
© 2009 Comba Telecom, All Rights Reserved49
Mounting of TMA
• TMA is pre-fixed with mounting brackets• TMA can be mounted on wall using 4xM8 masonry bolts • For pole mounting, ring clamps are used to fasten the TMA onto the
pole.
© 2009 Comba Telecom, All Rights Reserved50
Bias Tee Connection
• ANT port connects to feeder cable leading to antenna• BTS port connects to feeder cable leading to BTS• Two types of bias tee :
Model Connector Type
ANT 7/16 DIN-Female
BTS 7/16 DIN-Male
ANT 7/16 DIN-Male
BTS 7/16 DIN-FemaleBT-M2
BT-M1
© 2009 Comba Telecom, All Rights Reserved51
Bias Tee Connection
• Bias tee must be position in front of lightning protection devices• Lightning protection devices placed in front of bias tee will caused
bias tee to malfunction
ANTENNA
BTS
ANT
BTSBTS
ANT
lightning protection devices
© 2009 Comba Telecom, All Rights Reserved52
Connecting Bias Tee to PDM
• Bias tee is connected to PDM using RG174-KW3 cable
BTS
ANT
BTS
ANT
Power cable (RG174-KW3)
Power cable (RG174-KW3)
© 2009 Comba Telecom, All Rights Reserved53
PDM Connection
• Connection at VIN port is polarity independent• Alarms are send via cable connected from Alarm 1 connector to
BTS installation
Main power supply: +24VDC or -48VDC BTS external
alarm
PDM Power Cable
© 2009 Comba Telecom, All Rights Reserved54
Alarms
• Alarms are activated under the following circumstances– +12VDC power module failure– Broken connection between PDM and Bias tee– TMA LNA failure
• Alarm 1 pin configurations
• When alarm occurs, PIN 1-2 or 3-4 will become shorted/closed
PIN 1 2 3 4
Function Normally Open
Common Common Normally Open
© 2009 Comba Telecom, All Rights Reserved55
LED Indicators on PDM
• Two LEDs for TMA alarms and one LED for power supply alarm• Green = Normal; Red = Alarm
Power supply alarmTMA alarms
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TMA SYSTEM CONNECTION
© 2009 Comba Telecom, All Rights Reserved57
THANK YOU
Jin Gang Mei
Project Manager