when to use tma guideline
TRANSCRIPT
-
7/31/2019 When to Use TMA Guideline
1/20
-
7/31/2019 When to Use TMA Guideline
2/20
TOWER MOUNTED AMPLIFIER GUIDELINE
2(20) RSA 100 56 - 102 Uen Rev A 2002-05-28
Ericsson AB 2002
The contents of this product are subject to revision without notice due tocontinued progress in methodology, design and manufacturing.
Ericsson assumes no legal responsibility for any error or damage resultingfrom usage of this product.
This product is classified as Ericsson Commercial In Confidence
-
7/31/2019 When to Use TMA Guideline
3/20
RSA 100 56 - 102 Uen Rev A 2002-05-28 3(20)
Contents
1Revision history ..................................................................5
2 Introduction.........................................................................5
3TMA products......................................................................5
4System aspects...................................................................7
4.1 Benefits from introducing TMA...............................................................7
4.2 Considerations when introducing TMA...................................................7
5Link budget improvement ..................................................9
5.1 Link balance and parameter variations ..................................................9
5.2 TMA benefits ........................................................................................10
5.3 Nominal figures for sensitivity and output power..................................10
5.4Alternative parameter values................................................................12
5.5 Power balance calculations..................................................................12
5.6 Link budget improvements ...................................................................14
6Conclusion ........................................................................19
7References ........................................................................20
-
7/31/2019 When to Use TMA Guideline
4/20
TOWER MOUNTED AMPLIFIER GUIDELINE
4(20) RSA 100 56 - 102 Uen Rev A 2002-05-28
-
7/31/2019 When to Use TMA Guideline
5/20
RSA 100 56 - 102 Uen Rev A 2002-05-28 5(20)
1 Revision history
Revision Date Description
2 IntroductionA Tower Mounted Amplifier (TMA) is mounted in the antenna tower close to
the receiving antenna where it amplifies the received signal before it enters the
antenna feeder. The benefit of using TMAs is an improved uplink
performance. Whether it is recommended to use TMAs depends mainly on
which type of Combining and Distribution Unit (CDU) the Radio Base Station
(RBS) is equipped with, but also what area type that is to be covered and the
network quality ambitions the operator has.
This document shall serve as a short guideline describing when it is
appropriate to use TMA in the Ericsson GSM system.
The document describes the different TMA products, the system aspects of
using TMAs and presents the potential link budget improvement by using
TMAs. The document only deals with RBS 2000.
3 TMA productsThere are two different types of TMAs: duplex and dual duplex, see Figure 1.
TMA Duplex contains one duplex filter so that the TX and RX feeder can
be connected to the same antenna.
TMA Dual Duplex contains two duplex filters, one before the LNA and
one behind. This makes it possible to use only one feeder (TX/RX)
between the RBS and the TMA and to use the same antenna for TX/RX.
Today, virtually all TMAs sold are Dual Duplex ones. There are two
reasons for this:
A/ The number of feeders is reduced
B/ Only Dual Duplex TMAs are future proof for RBS2106/2206
installations/upgrades.
-
7/31/2019 When to Use TMA Guideline
6/20
TOWER MOUNTED AMPLIFIER GUIDELINE
6(20) RSA 100 56 - 102 Uen Rev A 2002-05-28
DPX
RXTX
Duplex
DPX
DPX
TX/RX
Dual Duplex
DPX : Duplex Filter
: Low Noise Amplifier
Figure 1. Duplex and dual duplex TMA.
The current TMA product range includes the following frequency options:
Table 1. TMA products.
Duplex Dual Duplex
Frequency
band
[MHz]
Band
width
[MHz]
Frequency
band
[MHz]
Band
width
[MHz]
GSM800, RBS2000 N/A N/A 824-849 25
GSM 900, RBS 2000 N/A N/A 880-905
or
890-915
25
GSM 1800, RBS 2000 1710-1785 25, 75 1710-1785 30, 75
GSM 1900, RBS 2000 1850-1910 25, 60 1850-1910 30, 60
-
7/31/2019 When to Use TMA Guideline
7/20
RSA 100 56 - 102 Uen Rev A 2002-05-28 7(20)
4 System aspects
4.1 Benefits from introducing TMA
The TMA is mounted in the antenna tower close to the receiving antennas,
where it amplifies the received signal before it enters the antenna feeder.
Thanks to the additional amplification, the uplink RX sensitivity is improved.
There are two reasons for the improvement. Firstly, the feeder loss on the
uplink is neutralized. Secondly, the noise figure for the uplink will decrease.
In areas where noise (C/N) will limit the cell range, the improved RX
sensitivity has a potential of improving the coverage or decreasing the number
of sites required for coverage. Also the uplink speech quality and the dropped
call rate may be improved. More details under paragraph 5.1.
Improvements in speech quality and dropped call rates are often rewarded byan increase in traffic volume and billing.
The improved RX sensitivity will decrease the power consumption of the MS.
A TMA will however not help against low C/I. This is due to the fact that the
TMA will amplify the own signal (C) as well as the interference (I) and thus
not increase C/I.
In case of limited bandwidth, high traffic areas such as dense city
environments will call for tight frequency re-use and reduced cell ranges. The
deployment of TMAs under such conditions requires some extra thought.
However, if sufficient bandwidth allows TMA deployment withoutinterference constraints, network improvement can also be gained in dense
urban environments, including improving indoor coverage quality.
4.2 Considerations when introducing TMA
4.2.1 General
Placing active devices in the antenna tower puts extreme requirements on
reliability. The Ericsson TMA is designed for extremely high MTBF (Mean
Time Between Failure) and has dual LNAs and an optional LNA by-passfunctionality, to ensure a problem-free operation.
For RBS2106/2206 compatibility and to minimize the number of feeders, the
dual duplex TMA has to be used.
Todays TMA product range includes full band versions for all GSM bands
and all TMA types. Thus, TMA deployment is possible for all operators no
matter their frequency allocation from the regulators.
-
7/31/2019 When to Use TMA Guideline
8/20
TOWER MOUNTED AMPLIFIER GUIDELINE
8(20) RSA 100 56 - 102 Uen Rev A 2002-05-28
4.2.2 RXLEV Compensation
Due to its amplification, the TMA will also affect the RXLEV values sent to
the BSC. This has to be taken into account during radio network optimization.
For example a received signal that without a TMA is measured to be RXLEV
= 10 (-100 dBm) would with a TMA having 12 dB amplification be measuredas RXLEV = 22. This is an undesired behavior since it would affect parameter
settings in the BSC to a large extent. The desired behavior is that the RXLEV
values sent to the BSC are the ones corresponding to the locating reference
point for sensitivity. If a TMA is used the reference point is defined at the
antenna connector of the TMA, see Figure 2.
RBS
TMA
Reference point
without TMA
Rx antenna
Feeder and jumpers
Reference point
with TMA
Figure 2. Locating reference point for sensitivity with and without TMA.
To transform the RXLEV values from the usual reference point at the RBS
cabinet to a reference point at the antenna connector, the values for the TMA
amplification and the antenna feeder loss must be specified in the Installation
Data Base (IDB) of the RBS. Information on how to do this can be found in
the RBS Site Test Manual.
4.2.3 BSC parameters affected by TMA introduction
For detailed information on BSC parameters influence by the TMA
introduction, please refer to the applicable system release documentation.
-
7/31/2019 When to Use TMA Guideline
9/20
RSA 100 56 - 102 Uen Rev A 2002-05-28 9(20)
5 Link budget improvement
5.1 Link balance and parameter variations
The RF performance in a cell depends on many factors involved, as will be
outlined later in this section.
By initially assigning these parameter nominal values, a Nominal Cell Plan,
i.e. the first site deployment draft, can be generated.
However, it is essential to understand that real-life site performance including
the Uplink/Downlink relation follows from actual variations of these
parameters and inevitably varies over time for any cell and site. (Ref. Figure
3)
Therefore, successive planning must take parameter tolerances and site-
specific aspects etc into account, to generate a realistic cell plan targeted to adesired radio network quality level.
No. of samples
Downlink superiority vs Uplink (dB)
Downlink > UplinkUplink > Downlink
X Y Z-Z -Y -X
TMA Improvement potential zone
Figure 3. Typical Uplink/Downlink balance distribution
The reasons for the cell-specific link balance variations include:
Variations in the MS populations performance. MS output is
usually lower than nominal values etc.
Variations in real antenna diversity gain, due to relative MS
positions, indoor MS usage etc.
Downlink slant loss is only to be expected for downlink paths with
little or no reflections.
Non-stationary reflection patterns
Different fading patterns for the uplink compared to the downlink
-
7/31/2019 When to Use TMA Guideline
10/20
TOWER MOUNTED AMPLIFIER GUIDELINE
10(20) RSA 100 56 - 102 Uen Rev A 2002-05-28
5.2 TMA benefits
The benefit from deploying TMAs will depend on whether the site is
primarily downlink or uplink limited.
Dropped calls appear in areas with marginal coverage, such as:
Areas in the cell peripheries
Areas suffering from relative RF shadowing
Indoor environments
In-vehicle communication, where MS is not connected to an external
vehicle-mounted antenna
5.2.1 Potential TMA benefits in uplink limited sites:
Improving the geographic area covered, which facilitates the locationof suitable site space and ultimately reduces the number of sites
required. Up-front investment may be reduced.
Also the uplink speech quality and the dropped call rate may be
improved. The improved sensitivity can also be used to decrease the
power consumption of the MS.
5.2.2 Potential TMA benefits in downlink limited sites:
By further strengthening the uplink, call quality and dropped call rate
may be further improved, by minimizing the T_DR_SS_UL (Droppedcall rate related to low uplink signal strength).
NOTE: Operator experience has proven that quality improvements and
dropped call rate reductions can be expected also in such cells, where the
nominal uplink is stronger than the nominal downlink. The reason for this is
that nominal parameter figures are an approximation of the radio scenario at
hand.
5.3 Nominal figures for sensitivity and output power
In Table 2, sensitivity figures for different CDU types are presented with andwithout TMA. The improvement at the reference point is approximately 1.5
dB when using the TMA. Note that the reference point of this improved
sensitivity is defined at the antenna connector of the TMA (see Figure 2). For
an RBS without TMA the reference point is where the feeder cable is
connected to the RBS cabinet. This means that the sensitivity improvement by
using a TMA is 1.5 dB plus the attenuation in the feeder, i.e. the total
sensitivity improvement is typically 3-5 dB.
-
7/31/2019 When to Use TMA Guideline
11/20
RSA 100 56 - 102 Uen Rev A 2002-05-28 11(20)
Table 2. Nominal sensitivity levels with and without TMA, with reference
points according to Figure 2.
CDU Sensitivity
GSM 800
[dBm with/withou
t TMA
Sensitivity
GSM 900
[dBm with/withou
t TMA
Sensitivity
GSM 1800
dBm with/withou
t TMA
Sensitivity
GSM 1900
dBm with/withou
t TMA
CDU-A n/a -111.5/-110 -111.5/-110 -111.5/ N/A
CDU-C+ n/a -111.5/-110 -111.5/-110 -111.5/-110
CDU-D n/a -111.5/-110 -111.5/-110 n/a
CDU-F n/a -111.5/-110 -111.5/-110 n/a
CDU-G -111.5/-110 -111.5/-110 -111.5/-110 -111.5/-110
The sensitivity figures presented in Table 2 are only valid if the loss in the
feeder between the TMA and the RBS is less or equal to 4 dB. If the loss is
higher the sensitivity will deteriorate according to Table 3. For example if the
feeder loss is 8 dB, the sensitivity of an uplink equipped with CDU-A will be -
111.5 + 1.5 = -110 dBm.
Table 3 Sensitivity deterioration when the loss between the TMA and the RBS
exceeds 4 dB. Note that the figures are measured at 12 dB TMA gain.
Loss dB Sensitivity deterioration dB
4 0
6 0.5
8 1.5
10 2.5
Table 4 shows the TX output power of the RBS for different CDU types.
These values are required to analyze whether the RBS should be equipped
with a TMA or not.
-
7/31/2019 When to Use TMA Guideline
12/20
TOWER MOUNTED AMPLIFIER GUIDELINE
12(20) RSA 100 56 - 102 Uen Rev A 2002-05-28
Table 4. TX output power defined at the RBS cabinet. Figures excluding the
optional software power boost and Coherent Combining features which
increase the output power.
CDU Output
powerGSM 800
[dBm
Output
powerGSM 900
[dBm
Output
powerGSM 1800
dBm
Output
powerGSM 1900
dBm
CDU-A n/a 44.5 43.5 43.5
CDU-C+ n/a 41.0 40.0 40.0
CDU-D n/a 42.0 41.0 N/A
CDU-F n/a 43.0 42.0 N/A
CDU-G 42.0 / 45.5 1/ 42.0 / 45.5 1/ 41.0 / 44.5 1/ 41.0 / 44.5 1/
1/Output power is 3.5 dB lower when CDU-G is used in Capacity Mode
5.4 Alternative parameter values
Many operators use alternative values for some of the parameters in the power
balance calculations (ref. Paragraph 5.5). The reason is to allow for equipment
related, site related and MS population related tolerances and in some cases to
further improve the network quality.
Based on own practical experience, these operators assess the relative uplink
strength to be weaker than in this documents nominal parameter results. By
doing so, they profit from the TMAs in cases, where a nominal parameter
calculation suggest no benefit would be attainable.
Paragraph 5.1 outlines why this is possible.
Since dropped calls may be further reduced and since no significant negative
effects are generated by uplink superiority, it is always good to evaluate the
potential benefits of a stronger uplink. In paragraph 5.6, an optional parameter
margin to stress this potential is included in Tables 5, 6, 7 and 8.
Suggestions on how to perform trial evaluation of TMA benefits are available
from Ericsson (ref. 3).
5.5 Power balance calculations
To see whether it is beneficial to use a TMA one can check the power balance
of the system assuming that there is no TMA. This can be done using
equation (1). 45 polarized antennas and equal feeder loss uplink and
downlink are assumed throughout this document. For more information about
link budget equations please refer to ref. 1.
-
7/31/2019 When to Use TMA Guideline
13/20
RSA 100 56 - 102 Uen Rev A 2002-05-28 13(20)
sensslantdivMSbalRBS LGPP +++= (max))( (1)
where
PRBS(bal)
is the RBS output power at the TX reference point to be used in
order to achieve a power balance between the uplink and the
downlink. The TX reference point is where the feeder is
connected to the RBS cabinet. The RBS out put power can be
found in Table 4.
PMS(max) is the maximum MS output power. Depends on the power class.
Gdiv is the average diversity gain (usually 3.5 dB)
Lslant is the downlink propagation loss due to 45 polarized antennas
(usually 1 dB).
sens is the difference in sensitivity between the MS and RBS, i.e.MSsens - RBSsens.Note that the reference point at the RBS
cabinet should be used (see Figure 2). The recommended figure
for MS sensitivity is 104 dBm.
If the maximum output power of the RBS is higher than the balanced one (see
equation (1)), the uplink is the limiting link and the link budget can be
improved by using a TMA. The link budget improvements calculated
according to equation (1) are summarized in section 5.6.
If it is decided to use a TMA the balanced RBS output power is given by:
TMAjfsensslantdivMSbalRBS LLLGPP +++++= +(max))( (2)
where
Lf+j is the loss in feeders and jumpers between the RBS and the TMA
LTMA is the TX loss in the TMA. For TMA Duplex and Dual Duplex
this loss is 0.3 dB. For TMA Simplex there is no TX loss.
sens is the difference in sensitivity between the MS and RBS, i.e.
MSsens - RBSsens.Note that the sensitivity reference point of the
RBS now is situated at the antenna connector of the TMA.
-
7/31/2019 When to Use TMA Guideline
14/20
TOWER MOUNTED AMPLIFIER GUIDELINE
14(20) RSA 100 56 - 102 Uen Rev A 2002-05-28
5.6 Link budget improvements
5.6.1 GSM800
In Table 5, the link budget improvement of using a TMA in a GSM 800 cell is
calculated for the available CDU types. The improvement is calculated
according to equation (1) and that network planning must be based on the
lower powered mobiles at 29 dBm (0.8 W).
To accommodate for equipment related, site related and MS population
related tolerances, an uplink limiting adjustment parameter the chart below
includes some tolerances. The higher network quality requirements, the more
attention should be given to the effect of these tolerances.
Table 5. Link budget improvement of using TMAs for GSM800.
CDU-G
Capacity
CDU-G
Coverage
PMS(max)[dBm] 29 29
Gdiv [dB] 3.5 3.5
Lslant[dB] 11/
11/
MSsens [dBm] -104 -104
RBSsens [dBm] -110 -110
PRBS(bal) [dBm] 39.5 39.5
PRBS(max) [dBm] 42.01/
45.51/
Nominal TMA potential dB 3.5 6.5
Uplink adjustment2/
dB 2-4 2-4
Adjusted TMA potential2/ dB 5.5-7.5 8.5-10.5
1/If the features Software Power Boost or Coherent Combining are used, each
giving an additional 3 dB downlink power or if space diversity (no downlink
slant loss) is used, the link budget calculations should be modified accordingly.
2/Proposed uplink adjustment, as per paragraph 5.4, to capture the full potential
in improved call quality and better in-door penetration.
-
7/31/2019 When to Use TMA Guideline
15/20
RSA 100 56 - 102 Uen Rev A 2002-05-28 15(20)
5.6.2 GSM900
In Table 6, the link budget improvement of using a TMA in a GSM 900 cell is
calculated for the available CDU types. The improvement is calculated
according to equation (1).
To accommodate for equipment related, site related and MS populationrelated tolerances, an uplink limiting adjustment parameter the chart below
includes some tolerances. The higher network quality requirements, the more
attention should be given to the effect of these tolerances.
Table 6. Link budget improvement of using TMAs for GSM900.
CDU-A CDU-C+
(CDU-C)
CDU-D CDU-G
Capacity
CDU-G
Coverage
CDU-F
PMS(max)[dBm] 33 33 33 33 33 33
Gdiv [dB] 3.5 3.5 3.5 3.5 3.5 3.5
Lslant[dB] 11/
11/
11/
11/
11/
11/
MSsens [dBm] -104 -104 -104 -104 -104 -104
RBSsens [dBm] -110 -110 -110 -110 -110 -110
PRBS(bal) [dBm] 43.5 43.5 43.5 43.5 43.5 43.5
PRBS(max) [dBm] 44.51/
411/
42 42.01/
45.51/
43.0
Nominal TMA potentialdB
1.0 0 0 0 2.0 0
Uplink adjustment2/
dB 2-4 2-4 2-4 2-4 2-4 2-4
Adjusted TMA potential2/ dB 3 - 5 0 - 1.5 0.5 2.5 0.5 2.5 4-6 1.5-3.5
1/If the features Software Power Boost or Coherent Combining are used, each giving an
additional 3 dB downlink power or if space diversity (no downlink slant loss) is used, the link
budget calculations should be modified accordingly. Software power boost is not possible for
configurations using CDU-D or CDU-F. Coherent Combining is only available for CDU-G
configurations.2/
Proposed uplink adjustment, as per paragraph 5.4, to capture the full potential in improved
call quality and better in-door penetration. For GSM900/1800/1900, this adjustment to the
theoretical model is necessary, to explain the well-proven TMA network benefits also for
CDU types where the Nominal TMA potential is zero.
One of many examples of the validity of the uplink adjustment is a German
trial, which led up to a full scale GSM900 TMA deployment onto the Ericsson
GSM radio network. Figure 4 below shows this trials Dropped-Call-Rate and
-
7/31/2019 When to Use TMA Guideline
16/20
TOWER MOUNTED AMPLIFIER GUIDELINE
16(20) RSA 100 56 - 102 Uen Rev A 2002-05-28
Traffic as a function of the TMA deployment as well as a change in TX output
power.
The conclusion that the TMA deployment generates an approximately 50%
reduction in the dropped call rate already with the TX output power limited by
4 dB states the case for the Uplink adjustment parameter.
Figure 4. Recorded dropped call rate & Traffic volume as a function ofGSM900 TMA deployment and TX output power
Field Trials: Coverage & Quality Improvement at Rural Omni-Site
0
1
2
3
4
5
1 4 710
13
16
19
22
25
28
31
34
37
40
43
46
49
52
Dropped CallRate [%]
TCH Traffic[Erlang]
Day
Date 1:
TMAs installed
Date 2:
BS Tx Power
increased by 2 dB
Date 3:
BS Tx Power
increased by 4 dB
-
7/31/2019 When to Use TMA Guideline
17/20
RSA 100 56 - 102 Uen Rev A 2002-05-28 17(20)
5.6.3 GSM1800
In Table 7, link budget improvement of using a TMA in a GSM 1800 cell is
calculated for various CDU types. The improvement is calculated according to
equation (1).
Table 7. Link budget improvement of using TMAs for GSM1800.
CDU-A CDU-C+
(CDU-C)
CDU-D CDU-G
Capacity
CDU-G
Coverage
CDU-F
PMS(max)[dBm] 30 30 30 30 30 30
Gdiv [dB] 3.5 3.5 3.5 3.5 3.5 3.5
Lslant[dB] 11/
11/
11/
11/
11/
11/
MSsens[dBm
]
-104 -104 -104 -104 -104 -104
RBSsens [dBm] -110 -110 -110 -110 -110 -110
PRBS(bal) [dBm] 40.5 40.5 40.5 40.5 40.5 40.5
PRBS(max) [dBm] 43.51/
401/
411/
41 44.5 42
Nominal TMA potential
dB
3.0 0 0.5 0.5 4 1.5
Uplink adjustment2/
dB 2-4 2-4 2-4 2-4 2-4 2-4
Adjusted TMA potential2/ dB 5 - 7 1.5 3.5 2.5 4.5 2.5-4.5 6-8 3.5-5.5
1/If the features Software Power Boost or Coherent Combining are used, each giving an
additional 3 dB downlink power or if space diversity (no downlink slant loss) is used, the link
budget calculations should be modified accordingly. Software power boost is not possible for
configurations using CDU-D or CDU-F. Coherent Combining is only available for CDU-G
configurations.
2/Proposed uplink adjustment, as per paragraph 5.4, to capture the full potential in improved
call quality and better in-door penetration. For GSM900/1800/1900, this adjustment to the
theoretical model is necessary, to explain the well-proven TMA network benefits also for
CDU types where the Nominal TMA potential is zero.
-
7/31/2019 When to Use TMA Guideline
18/20
TOWER MOUNTED AMPLIFIER GUIDELINE
18(20) RSA 100 56 - 102 Uen Rev A 2002-05-28
5.6.4 GSM1900
In Table 8, the link budget improvement of using a TMA in a GSM 1900 cell.
The improvement is calculated according to equation (1).
Table 8 Link budget improvement of using TMAs for CDU C and CDU-C+ at
GSM1900. For CDU-A TMA is mandatory.
CDU-C+
(CDU-C)
CDU-D CDU-G
Capacity
CDU-G
Coverage
PMS(max) [dBm] 30 30 30 30
Gdiv [dB] 3.5 3.5 3.5 3.5
Lslant[dB] 11/
11/
11/
11/
MSsens[dBm
]
-104 -104 -104 -104
RBSsens [dBm] -110 -110 -110 -110
PRBS(bal) [dBm] 40.5 40.5 40.5 40.5
PRBS(max) [dBm] 401/
411/
41 44.5
Nominal TMA potential
dB
0 0.5 0.5 4
Uplink adjustment2/
dB
2-4 2-4 2-4 2-4
Adjusted TMA potential2/ dB 1.53.5 2.54.5 2.54.5 6-8
1/If the features Software Power Boost or Coherent Combining are used, each
giving an additional 3 dB downlink power or if space diversity (no downlink
slant loss) is used, the link budget calculations should be modified accordingly.
Software power boost is not possible for configurations using CDU-D or CDU-F.
Coherent Combining is only available for CDU-G configurations.
2/Proposed uplink adjustment, as per paragraph 5.4, to capture the full potential in
improved call quality and better in-door penetration. For GSM900/1800/1900,
this adjustment to the theoretical model is necessary, to explain the well-provenTMA network benefits also for CDU types where the Nominal TMA potential is
zero.
-
7/31/2019 When to Use TMA Guideline
19/20
RSA 100 56 - 102 Uen Rev A 2002-05-28 19(20)
6 ConclusionThe Rayleigh fading is different on the uplink and the downlink. In a non-
frequency hopping cell it could occasionally happen that only the uplink
suffers from a fading dip. In these situations the improved sensitivity of the
TMA would be beneficial even if it according to strict link budget calculationswould be superfluous.
Another aspect is that the link budget calculations are based on an MS
sensitivity of -104 dBm and MS output power of 33 dBm and 30 dBm for
GSM900 and GSM800/1800/1900 respectively. Given todays MS featuring
dual and triple band capability, built-in antenna technology and the race for
the best stand-by and talk-time performance, it is to be assumed that a modern
MS population will deviate from these values.
In the process ofcell planning, all mobiles (old as well as newer ones) should
be considered. Thus by adopting the uplink adjustment calculations in
paragraph 5.6, we can understand why many operators install TMAs for allCDU types.
Note that the link budgets are calculated for standard configurations. If the
feature Software Power Boost is used, the calculation s should be modified
according to footnotes 1/. To capture the full potential in improved call quality
and better in-door penetration, calculation modification according to foot
notes 2/ is advisable.
Lastly, remember that a TMA does not improve C/I. Thus, in areas where it is
interference rather than noise that limits the system performance (for example
in cities with tight frequencyre-use) it is questionable whether to use TMA.
Also note that in these types of environment it has shown that it is thedownlink and not the uplink that suffers from the worst quality. Efforts to
improve the uplink will therefore not contribute so much to the overall speech
quality.
-
7/31/2019 When to Use TMA Guideline
20/20
TOWER MOUNTED AMPLIFIER GUIDELINE
20(20) RSA 100 56 - 102 Uen Rev A 2002-05-28
7 References
ref. 1 RF Guidelines GSM900 (1800, 1900) MHz
16 (17,18) /100 56-HSC 103 12 Rev B, 2001
ref. 2 Sensitivity figures and output power for RBS2000 Macro
LRN/X-98:033 Rev H, 2001
ref. 3 TMA Field Trial Recommendations Guideline
RSA 100 56 - 102 Uen Rev A 2002-05-28
ref. 4 Tower Mounted Amplifiers Guideline The Ericsson GSM System R7
5/100 56 HSC 103 12 Uen Rev B, 1999