Post on 30-Oct-2015
7/15/2019 GO_NA23_E1_1 GSM Power Control Algorithm-34
http://slidepdf.com/reader/full/gona23e11-gsm-power-control-algorithm-34 1/34
GSM Power Control Algorithm
Zte university
7/15/2019 GO_NA23_E1_1 GSM Power Control Algorithm-34
http://slidepdf.com/reader/full/gona23e11-gsm-power-control-algorithm-34 2/34
Brief Introduction
Rudiments of Power Control
ZTE Power Control Algorithms
Setting of Power Control Parameters
Application of Power Control
7/15/2019 GO_NA23_E1_1 GSM Power Control Algorithm-34
http://slidepdf.com/reader/full/gona23e11-gsm-power-control-algorithm-34 3/34
1. What is power control? Why we carry out
power control?
2. Classification of power control
3. Difference among various kinds of power
control
4. What’s the main object of power control?
5. How to conduct power control?
I. Rudiments of Power Control
7/15/2019 GO_NA23_E1_1 GSM Power Control Algorithm-34
http://slidepdf.com/reader/full/gona23e11-gsm-power-control-algorithm-34 4/34
1. What is power control? Why we carry out power
control?
What is power control?
Why should we carry out
power control?
Definition: Power control is to adjust the transmitting power of BTS
and MS according to real needs. Base: result of UL/DL measurement
Goal: to lower transmitting power, reduce interference in the whole
network and power consumption, on condition that speech quality is
ensured.
7/15/2019 GO_NA23_E1_1 GSM Power Control Algorithm-34
http://slidepdf.com/reader/full/gona23e11-gsm-power-control-algorithm-34 5/34
2. Classification of power control
Ordinary power control
Rapid power control
7/15/2019 GO_NA23_E1_1 GSM Power Control Algorithm-34
http://slidepdf.com/reader/full/gona23e11-gsm-power-control-algorithm-34 6/34
3. Difference among various kinds of power control
Static power
control
Under the non-idle mode, the network flexibly decides the
transmitting power of MS or BTS in a dynamic manner according to
radio environment.
Adopt fixed step to adjust power.
Adopt non-fixed step to adjust power, i.e. to settle power adjustment
at one go.
Power control in CS service.
Power control in PS service.
Impose restrictions on the max transmitting power of MS or BTS at
OMCR
Dynamic
power control
Ordinary power
control
Rapid power
control
CS power
control
PS power
control
7/15/2019 GO_NA23_E1_1 GSM Power Control Algorithm-34
http://slidepdf.com/reader/full/gona23e11-gsm-power-control-algorithm-34 7/34
4.What’s the main body of power control?
The main object of power control: TS and MS
Power control is directed at single subscribers, so the main
object of UL power control is single MS; for DL, it’s some timeslot
(ST) in the BTS used by the MS, Note it’s not the whole carrier.
It’s stipulated in the protocol that the transmission must be performed at
full power on the carrier of BCCH, so only UL dynamic power control
(not DL dynamic power control) can be carried out on the carrier of
BCCH.
7/15/2019 GO_NA23_E1_1 GSM Power Control Algorithm-34
http://slidepdf.com/reader/full/gona23e11-gsm-power-control-algorithm-34 8/34
5.How to conduct power control?
Collection of MS/BTS
measurement reports
Weighted average of MRs
If the average satisfies
conditions of power controldecision?
Condition for power
increase is satisfied
Condition for power
maintenance is satisfied
Condition for power
decrease is satisfied
Increase MS/BTS
transmitting power
Maintain MS/BTS
transmitting power
Decrease MS/BTS
transmitting power
Save the average
No
Yes
7/15/2019 GO_NA23_E1_1 GSM Power Control Algorithm-34
http://slidepdf.com/reader/full/gona23e11-gsm-power-control-algorithm-34 9/34
1. What power control algorithms are supported in ZTE systems?
2. What features do ZTE power control algorithms have?
3. What is sliding-window averaging?
4. What is Rapid averaging?
5. How is the initial state of ZTE power control algorithms defined?
6. How is the stable state of ZTE power control algorithms defined ?
7. What’s the relation between the initial state and stable state of ZTE power control
algorithms? 8. In which network element is ZTE power control realized?
9. How is measurement reports processed in ZTE power control algorithms?
10. How to judge conditions for power increase/decrease in ZTE power control
algorithms?
11. How to decide power increase/decrease value in ZTE power control algorithms (I)?
12. How to decide power increase/decrease value in ZTE power control algorithms (II)?
13. How to decide power increase/decrease value in ZTE power control algorithms (III)?
14. How to decide power increase/decrease value in ZTE power control algorithms (IV)?
15. Why bySub is introduced for the initial state of ZTE power control algorithms?
16. How is power control result measured in ZTE systems?
II. ZTE Power Control Algorithms
7/15/2019 GO_NA23_E1_1 GSM Power Control Algorithm-34
http://slidepdf.com/reader/full/gona23e11-gsm-power-control-algorithm-34 10/34
1. What power control algorithms are supported in
ZTE systems?
UL and DLRapid power control are notdiscriminated inversion 6.20and previousones.
7/15/2019 GO_NA23_E1_1 GSM Power Control Algorithm-34
http://slidepdf.com/reader/full/gona23e11-gsm-power-control-algorithm-34 11/34
2. What features do ZTE power control algorithms
have?
7/15/2019 GO_NA23_E1_1 GSM Power Control Algorithm-34
http://slidepdf.com/reader/full/gona23e11-gsm-power-control-algorithm-34 12/34
3. What is sliding-window averaging?
Definition: during averaging of measurement reports, when number of MR
reaches the window size (suppose it’s 4), calculate the first 4 MRs and get the
first average value; then calculate MR no.2 -5 and get the second average
value; and so on. Advantage: it can effectively disperse the influence of signal
fluctuation.
Disadvantage: it takes quite a bit of time to get the first average.
7/15/2019 GO_NA23_E1_1 GSM Power Control Algorithm-34
http://slidepdf.com/reader/full/gona23e11-gsm-power-control-algorithm-34 13/34
4. What is Rapid averaging? Definition: during averaging of measurement reports, which is not restricted by
average window, the first average value is obtained when the first MR is submitted;
and the second average value is obtained by calculating the first and second MRs;when number of MRs reaches the window size, rapid averaging is converted tosliding-window averaging.
Advantage: it reduces the time for triggering the first power control.
Disadvantage: its reliability is a bit low, as there are fewer samples of MRsparticipating in the decision.
7/15/2019 GO_NA23_E1_1 GSM Power Control Algorithm-34
http://slidepdf.com/reader/full/gona23e11-gsm-power-control-algorithm-34 14/34
5. How is the initial state of ZTE power control algorithms
defined?
When MS initially accesses into channel (SDCCH or TCH),the power control status it enters is referred as initial state.
Features of this state:
There is a big difference between the max transmitting power MS initially uses
and that actually needed.
It produces heavy influence on MS using other channels.
There is dramatic adjustment on MS and BTS power ranks, so there will be big
changes on MS and BTS power.
Usually it needs several consecutive times of rapid power adjustment.
Features of power control algorithm at this state:
Perform power control decision to each MR, adjust MS and BTS power
rank and make it reach the demanded level and quality in the shortest
time.
7/15/2019 GO_NA23_E1_1 GSM Power Control Algorithm-34
http://slidepdf.com/reader/full/gona23e11-gsm-power-control-algorithm-34 15/34
6. How is the stable state of ZTE power control
algorithms defined?
After experiencing the dramatic adjustment of power, MS reaches the requested UL
level and quality and enters a relatively stable situation, which is called stable state.
Conditions for MS entering stable state from initial state (either 1 or 2 is acceptable):
Condition 1: in most cases, MS power takes downward modulation in initial state; if
it stops downward modulation for N1 times, it’s supposed to have entered stable state.
Condition 2: when the number of measurement reports received reaches N2, MS
directly enters stable state.
Explanations on N1/N2 value:
Principle:N1<N2
Recommended value: N1-4, N2-11
N1 and N2 not only can be set some fixed value according to test result, but also can
be configured at OMCR; in order to maintain the compatibility of OMCR, currently
N1 and N2 are set the default value, and they can be adjusted through hyper-terminal.
7/15/2019 GO_NA23_E1_1 GSM Power Control Algorithm-34
http://slidepdf.com/reader/full/gona23e11-gsm-power-control-algorithm-34 16/34
7. What’s the relation between the initial state and
stable state of ZTE power control algorithms?
When MS enters initial state
of power control, it quickly
adjusts its power up to
demand;
When MS power stops
downward modulation for
N1 times, or when number
of received MRs reaches
N2, MS enters stable state;
Initial state and stable state
adopt different power
control strategies.
Initial state
MS power stops downward modulation for N1 times
Stable stateChannel release
Number of MRs received reaches N2
Channel power control enters
initial state
7/15/2019 GO_NA23_E1_1 GSM Power Control Algorithm-34
http://slidepdf.com/reader/full/gona23e11-gsm-power-control-algorithm-34 17/34
8. In which network element is ZTE power control
realized?
In ZTE system, power control is realized in BTS, which masters UL/DL dynamic
power control and reports the results to BSC at certain intervals, so that BSCcan collect related performance statistics. Refer to the following figure for the
logical location of power control elements.
7/15/2019 GO_NA23_E1_1 GSM Power Control Algorithm-34
http://slidepdf.com/reader/full/gona23e11-gsm-power-control-algorithm-34 18/34
9. How is measurement reports processed in ZTE
power control algorithms?
7/15/2019 GO_NA23_E1_1 GSM Power Control Algorithm-34
http://slidepdf.com/reader/full/gona23e11-gsm-power-control-algorithm-34 19/34
10. How to judge conditions for power
increase/decrease in ZTE power control algorithms?
LEVEL
CAUSE
QUAL
CAUSE
RESULT
0 0 POWER_STAY
0 1 DECREASE_BYQUALIT
Y0 2 INCREASE_BYQUALIT
Y
1 0 INCREASE_BYLEVEL
1 1 INCREASE_BYLEVEL
1 2 INCREASE_
BYQUALITY
2 0 DECREASE_BYLEVEL
2 1 DECREASE_BYLEVEL
2 2 INCREASE_BYQUALIT
Y
High level
threshold
Low level
threshold
Upper limit
of RxQual
Lower limit
of RxQual
Level HO
threshold
Quality HO
threshold
Increase
power
Decrease
power
Power stays
unchanged
RQ=0--7
R x l e v e l = 0 - - 6 3
LEVELCAUSE = 1
LEVELCAUSE = 0
LEVELCAUSE = 2
QUALCAUSE = 2
QUALCAUSE = 0
QUALCAUSE = 1
7/15/2019 GO_NA23_E1_1 GSM Power Control Algorithm-34
http://slidepdf.com/reader/full/gona23e11-gsm-power-control-algorithm-34 20/34
11. How to decide power increase/decrease value in
ZTE power control algorithms (I)?
7/15/2019 GO_NA23_E1_1 GSM Power Control Algorithm-34
http://slidepdf.com/reader/full/gona23e11-gsm-power-control-algorithm-34 21/34
12. How to decide power increase/decrease value of
in ZTE power control algorithms (II)?
Power control in initial state:
With the aim to carry out power control effectively, whether power is to increase or decrease, the step shall be the one set for power decrease, which shall be fixed.
1)MS power increase:
a) UL signal is bad, and no MS MR is received. If the difference between the MS power value
(computed through the current power control) and the last valid MS power value exceeds8dbm, then the current power control decision is valid, and MS power increase shall be
continued;
b) UL signal is good, MS MR is received by BTS; DL signal is bad, the power control value
hasn’t effectively controlled MS power, and the difference (bySub) exceeds 8dbm, then
power control shall not be imposed on MS any more;
2)MS power decrease:Regardless whether BTS has received MS UL MR or not, once the difference is less than
8dbm, power control shall not be imposed on MS;
3) As in BTS power measurement, the power adjustment benchmark value shall be the power
rank value of current BTS transmitting signal, and the calculation method is the same as that
of power control in stable state.
7/15/2019 GO_NA23_E1_1 GSM Power Control Algorithm-34
http://slidepdf.com/reader/full/gona23e11-gsm-power-control-algorithm-34 22/34
13. How to decide power increase/decrease value in
ZTE power control algorithms (III)?
Rapid power control: power increase/decrease in rapid power control shall be
carried out according to the following criteria. For level-related power increase/decrease control, specific conditions are needed in decision; if the
conditions are not satisfied, use the ordinary power control method.
7/15/2019 GO_NA23_E1_1 GSM Power Control Algorithm-34
http://slidepdf.com/reader/full/gona23e11-gsm-power-control-algorithm-34 23/34
14. How to decide power increase/decrease value in
ZTE power control algorithms (IV)?
Graph of ULordinary
power control:
Graph of UL
ordinary power
control with
rapid averaging
adopted:
Graph of ULrapid power
control:
7/15/2019 GO_NA23_E1_1 GSM Power Control Algorithm-34
http://slidepdf.com/reader/full/gona23e11-gsm-power-control-algorithm-34 24/34
15. Why bySub is introduced for the initial state of
ZTE power control algorithms?
After sending new power rank to MS, it takes an interval of at least three
MRs for BTS to receive MS power rank report, which makes it unable to
meet the requirement for each MR to adjust the last sent power control
value( byMSpowerSet) by 2dB in the initial state of power control.
A variable bySub is introduced, which represents the difference between
the power control value to be sent and the currently received power
value, whose limit is 8dbm.
7/15/2019 GO_NA23_E1_1 GSM Power Control Algorithm-34
http://slidepdf.com/reader/full/gona23e11-gsm-power-control-algorithm-34 25/34
16. How is power control result measured in ZTE
systems?
BTS reports power control results to BSC for performance statistics. Reporting period is
controlled by PwrCtrlReportPrd (SACCH multi-
frame) .
ZTE power control statistics are in collected inBTS measurement tasks, including cause and
times of power control. For details, please refer to
the fascicule of performance counters in attached
manuals.
7/15/2019 GO_NA23_E1_1 GSM Power Control Algorithm-34
http://slidepdf.com/reader/full/gona23e11-gsm-power-control-algorithm-34 26/34
1. What are the general cares of setting powercontrol parameters?
2. Recommended values of power control
parameters
3. What factors influence the speed of dynamic
power control?
III Setting of Power Control Parameters
7/15/2019 GO_NA23_E1_1 GSM Power Control Algorithm-34
http://slidepdf.com/reader/full/gona23e11-gsm-power-control-algorithm-34 27/34
1. What are the general cares of setting power
control parameters?
7/15/2019 GO_NA23_E1_1 GSM Power Control Algorithm-34
http://slidepdf.com/reader/full/gona23e11-gsm-power-control-algorithm-34 28/34
2. Recommended values of power control parameters
The recommended values are for reference, please make
appropriate adjustment according to actual network situations.
Parameter Recommended value 6.20.101e &subsequent
versions 6.20.101e&subsequent
versions Average window size 4 4
UL/DL RQ increase threshold 3 2 UL/DL RQ increase P/N value 2/3 2/3 UL/DL RQ decrease threshold 1 0 UL/DL RQ decrease P/N value 2/3 2/3
UL/DL level increase /
decrease thresholddefault default
UL/DL level increase /
decrease P/Nvalue2/3 2/3
Increase step 4db 4db Decrease step 2db 2db
Rapid averaging Enabled Disabled
Rapid power control Enabled Disabled
Power decrease limit 10,8,6,4,2,2,2,2 default Power control min interval 1 0
MS min power rank 18(900M)、14(1800M) 18(900M)、14(1800M) BS min power rank 15(900M)、14(1800M) 15(900M)、14(1800M)
7/15/2019 GO_NA23_E1_1 GSM Power Control Algorithm-34
http://slidepdf.com/reader/full/gona23e11-gsm-power-control-algorithm-34 29/34
3. What factors influence the speed of dynamic
power control?
7/15/2019 GO_NA23_E1_1 GSM Power Control Algorithm-34
http://slidepdf.com/reader/full/gona23e11-gsm-power-control-algorithm-34 30/34
1. In which circumstances can power control beapplied?
2. Which KPIs will be influenced by power
control?
3. In which aspects will power control influence
subscriber’s satisfaction?
IV Application of Power Control
7/15/2019 GO_NA23_E1_1 GSM Power Control Algorithm-34
http://slidepdf.com/reader/full/gona23e11-gsm-power-control-algorithm-34 31/34
1. In which circumstances can power control be
applied?
Normally UL ordinary power control is enabled, other power control types are
mainly applied in areas with dense sites, which can help reduce interference.The following table is for reference.
7/15/2019 GO_NA23_E1_1 GSM Power Control Algorithm-34
http://slidepdf.com/reader/full/gona23e11-gsm-power-control-algorithm-34 32/34
2. Which KPIs will be influenced by power control?
Power control influences transmitting power, which may impose some negative
effects on the level of coverage, and result in dramatic decrease in the
proportion of level above -75dbm.
7/15/2019 GO_NA23_E1_1 GSM Power Control Algorithm-34
http://slidepdf.com/reader/full/gona23e11-gsm-power-control-algorithm-34 33/34
3. In which aspects will power control influence
subscriber’s satisfaction?
7/15/2019 GO_NA23_E1_1 GSM Power Control Algorithm-34
http://slidepdf.com/reader/full/gona23e11-gsm-power-control-algorithm-34 34/34