Kamis, 29 November 2012

Sdcch congestion rate optimization guide



When SDCCH are required?
The requests for the SDCCH in GSM are mainly made in the following two procedures:
A. The procedure for requesting the SDCCH for services such as point-to-point calls, location updating (only SDCCH), call re-establishment, or short messages;
B. The procedure of SDCCH handovers (including both the intra-BSC and inter-BSC handovers)

Principles of SDCCH Congestion Rate: 
SDCCH congestion rate is one of the important counters that indicate accessibility in circuit service. This counter provides the ratio of failed SDCCH seizures due to busy SDCCH to the total requests for the SDCCH. SDCCH congestion rate indicates the failed requests for the SDCCH for various reasons. SDCCH congestion rate also indicates the status of the SDCCH resource utilization.

Definition & Formula of SDCCH Congestion : 
The definition and formula of SDCCH congestion rate are as follows:
• Definition:
Ratio of failed SDCCH seizures due to busy SDCCH to the total requests for the SDCCH
• Formula:
SDCCH congestion rate = Failed SDCCH seizures due to busy SDCCH/Total requests for the SDCCH x 100%

Factors of SDCCH Congestion Rate in GSM : 

4.1 Congestion Caused by Faults on Equipment or Transmission : 
The faults on BTS, BSC, and Abis interface, such as broken LAPD link, cause the SDCCH congestion. The alarm "Excessive Loss of E1/T1 Signals in an Hour" also causes the SDCCH congestion.

4.2 Congestion Caused by Insufficient Signaling Resources : 
The heavy traffic and burst traffic cause the SDCCH congestion. Proper setting of the number of SDCCHs and TCHs, and the SDCCH dynamic conversion function can relieve the congestion.

4.3 Congestion Caused by Improper Data Configuration : 
The SDCCH congestion relates to the relevant parameters of the BSC such as SDCCH Availability, LAC and T3101 (the timer used in the immediate assignment procedure), and T3212 (the timer used for periodic updating). If these parameters are set correctly, the SDCCH congestion can be relieved. In addition, if the assignment procedure is set to Late Assignment, the time of the SDCCH being occupied increases, which may lead to congestion.

4.4 Congestion Caused by Interference : 
Interference on the Um interface also causes congestion. For example, if the main BCCH in the serving cell and the TCH in the neighboring cell share the same TRX frequency and BTS BSIC, the handover access on this TCH may be mistaken as random access. As a result, the SDCCH is abnormally allocated and congestion occurs. The excessive receive sensibility can also make the interference signal mistaken as access signal, which leads to congestion.

Analysis Procedure of SDCCH Congestion Rate : 
SDCCH congestion rate is classified into BSC-level and cell-level according to the statistic object of the counter. The SDCCH congestion rate of a BSC is composed of the SDCCH congestion rate of a series of cells. Procedure of SDCCH congestion rate analysis is as shown below:

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First, determine the level of the SDCCH congestion rate. If the congestion occurs in a large area, check the traffic volume and the setting of T3212. Then, calculate the SDCCH capacity to check whether it meets the system demand and whether the faults exist on system-level equipment or transmission. If congestion occurs in only a few cells, check the hardware, data configuration, and Um interface quality of the cell.

Below given is the analysis & optimization procedure for SDCCH Congestion Rate : 

Checking Channel Configuration : 
Query the traffic statistics to see whether the traffic volume on the SDCCH and TCH are higher than the normal value. If the congestion is caused by excessive traffic on the SDCCH, for multi-TRX BTSs, enable SDCCH dynamic allocation function or increase the number of SDCCH channels to relieve the congestion. For cells with only one TRX or without extra channels, enable the very early immediate assignment procedure. In the very early immediate assignment procedure, the TCH channel is immediately assigned when the SDCCH has no available resource during the processing of access request. In this case, a TCH can be used as only one SDCCH, which is a waste of the TCH resources.

All the services such as location updating, MS attach/detach, call setup, short messages are performed on the Schiff a certain service causes burst traffic, the SDCCH congestion may occur.
In this case, check whether the abnormity of Channel Requests, Successful Immediate Assignments or Successful SDCCH Seizures is caused by the service of location updating, MOC, paging, or short message. Note that you should check the history traffic statistics when querying these traffic counters to see whether they fluctuate during a certain period.

If the SDCCH congestion is caused by certain burst services such as location updating and short messages, use the following methods according to the specific configuration of the BTSs.

a. For the BTS with multiple TRXs, enable the SDCCH dynamic allocation function or increase the number of SDCCH channels.

b. For the cell with only one TRX or without extra channels, enable the immediate assignment procedure. In the immediate assignment procedure, the TCH is immediately assigned when the SDCCH has no available resource during the processing of access request.

c. Increase the number of TRXs.
It is difficult to avoid the SDCCH congestion caused by network burst services; however, you can take some relief measures such as increasing the number of SDCCHs or enabling the SDCCH dynamic conversion function.

Rabu, 28 November 2012

UMTS Pilot channel failure ,high downlink interference


Symptoms
From the drive test, following symptoms will be observed by using TEMS:
• Received Ec/No of the pilot channel is less than –16dB and
• Received RSCP of the pilot channel is high enough to maintain the connection, e.g. > -100dBm and
• DL RSSI is very high and
• The connection finally drops.

Reason 1 – no dominant cell

There are many overlapping cells at the problem area. The received signal strengths of these pilots are almost the same.

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Solution 
The most direct and effective way to solve this problem is to increase the pilot channel power Primary CPICH power of the desired cell.

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The drawbacks of this solution are:
• Due to uneven pilot power setting, some UEs might no longer be connected to the “closest” cell with respect to the pathloss. Then they transmit with high UE powers. As a result, the uplink interference level of the carrier is consequently increased. It means uplink is not optimized and this phenomenon is called as uplink near-far problem. It is recommended that

–Reporting Range 1a: threshold for addition window/2 ≤ difference of the pilot power settings of two neighboring cells ≤ Reporting Range 1a: threshold for addition window/2

• In case the pilot power of a cell is increased, the required power for the downlink DPCHs in that cell also increase. Finally, the load of the cell becomes high and then cell blocking may happen.
• The downlink interference level of the carrier will be higher.
• The cell with higher pilot power will absorb more UEs from its adjacent cells. Then the load of the cell will be higher.
• Pilot power changes may lead to uplink coverage and pilot coverage imbalance problems.

Reason 2 – dominant interferer

An undesired cell with very high signal strength is found in the problem area.

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Solution 1
The simplest solution to overcome this problem is to include the overshooting cell into the neighboring cell list. This means the interferer now becomes a useful radio link.
The drawbacks of the solution 1 are:
• It creates more unnecessary handovers and excessive numbers of UEs are in soft handover.
• If the overshooting cell is physically far way to the problem area, the handover sequence might be messed up after including it into the neighboring cell list.

Solution 2
An alternative solution is to change the antenna configuration of the overshooting cell, e.g. tilting down the antenna, re-directing the antenna orientation, reducing the antenna height.
With this solution, UL/DL coverage imbalance problem will not occur in the interferer because both UL/DL pathloss is modified simultaneously. Moreover, the interferer probably will cover fewer UEs, and transmit a lower total downlink power. This means that its downlink interference contribution might be further decreased.

The main drawback of the solution 2 is:
• Neighboring cells of the interferer will cover a larger area and will thus absorb additional UEs. The risk of high blocking rate therefore increases in these cells. Moreover, due to transmit high Tx power, they might become interferers if their coverages are not well confined.

Solution 3
The third possible solution is to decrease the pilot power Primary CPICH power of the overshooting cell.
The drawbacks of the solution 3 are:
• Reducing the pilot power, the downlink channel estimation in the UE is affected. This influences the downlink quality. In the end, the UE might request more power from base stations.
• When the pilot power is reduced, the maximum allowed DL DCH power decreases. Then, outage of the downlink DPCH will be higher if the pilot power is reduced too much.

Reason 3 – low best serving PPilot/PTot
The received Ec/No of the best serving pilot channel is very low (near or less than –16dB) even though there is no other cell. It means the pilot power setting is not large enough to fulfill existing downlink load.

Solution 1
The best solution is to add a new site with “good coverage control” at the problematic area.

Solution 2 
The direct but ineffective solution is to increase the pilot channel power Primary CPICH power of the problematic cell. With high pilot power, the common channel powers and the required power for the downlink DPCHs will be increased. At the end, the ratio of the PPilot/PTot does not increase much.

UE-Analysis-Clasification Tems Analysis


CONTENTS
1 INTRODUCTION
2 SCOPE
3 LONG CALL TEST
3.1 Radio Frequency
3.1.1 Missing neighbour relationship
3.1.2 Poor coverage
3.1.3 Bad Ec/No
3.2 Site/System problem
3.2.1 Unable to add/remove SC to/from the AS
3.2.2 ASU without MR
3.3 Not classified
3.3.1 Ec/No dropping very fast .
3.3.2 UE Tx Power down after RL removal
4 SHORT CALL TEST
4.1 Radio Frequency
4.1.1 Poor coverage
4.1.2 Bad Ec/No
4.2 Site/System problem
4.2.1 CM service reject
4.3 UE Problem
4.3.1 UE freeze
4.3.2 Call attempt to the worst cell
4.3.3 Only one RRC Connection Request.
4.3.4 Best SC removed from the AS
4.3.5 Motorola A835 incorrect sequence number
4.4 Not classified
4.4.1 L1 Synchronization problem
4.4.2 RRC Connection Request with no AICH
4.4.3 RRC Connection Release after Radio Bearer Reconfiguration Complete
4.4.4 Out of synchronization RL
4.5 Other



UE-Analysis-Clasification Tems Analysis -

Selasa, 27 November 2012

Lte Frequency


E-UTRA frequency band (36.101)

BandNameBandwidth
(MHz)
Downlink (MHz)Uplink (MHz)Duplex spacing
(MHz)
Equivalent
UMTS band
Low
Earfcn
High
Earfcn
Low
Earfcn
High
Earfcn
1IMT 2.1 GHz602110
0
2170
599
1920
18000
1980
18599
1901
2PCS 1900601930
600
1990
1199
1850
18600
1910
19199
802
3DCS 1800751805
1200
1880
1949
1710
19200
1785
19949
953
4AWS452110
1950
2155
2399
1710
19950
1755
20399
4004
5850 MHz25869
2400
894
2649
824
20400
849
20649
455
6UTRA only10875
2650
885
2749
830
20650
840
20749
456
72.6 GHz702620
2750
2690
3449
2500
20750
2570
21449
1207
8900 MHz35925
3450
960
3799
880
21450
915
21799
458
91700 MHz351844.9
3800
1879.9
4149
1749.9
21800
1784.9
22149
959
10Extended AWS602110
4150
2170
4749
1710
22150
1770
22749
40010
111.5 GHz Lower201475.9
4750
1495.9
4949
1427.9
22750
1447.9
22949
4811
12700 MHz Lower, A+B+C17729
5010
746
5179
699
23010
716
23179
3012
13700 MHz Upper10746
5180
756
5279
777
23180
787
23279
-3113
14Public Safety10758
5280
768
5379
788
23280
798
23379
-3014
17700 MHz Lower, B+C12734
5730
746
5849
704
23730
716
23849
30 
18Japan 800 MHz lower15860
5850
875
5999
815
23850
830
23999
45 
19Japan 800 MHz upper15875
6000
890
6149
830
24000
845
24149
4519
20800 MHz EDD30791
6150
821
6449
832
24150
862
24449
-4120
211.5 GHz Upper151495.9
6450
1510.9
6599
1447.9
24450
1462.9
24599
4821
223.5 Ghz803510
6600
3590
7399
3410
24600
3490
25399
10022
232 GHz S-Band202180
7500
2200
7699
2000
25500
2020
25699
180 
24L Band341525
7700
1559
8039
1626.5
25700
1660.5
26039
-101.5 
25PCS 1900 + G Block651930
8040
1995
8689
1850
26040
1915
26689
8025
26800 MHz iDEN35859
8690
894
9039
814
26690
849
27039
4526
27850 MHz lower17852
9040
869
9209
807
27040
824
27209
45 
28700 MHz APAC45758
9210
803
9659
703
27210
748
27659
55 
33TDD 2000201900
36000
1920
36199
  Tdd 
34TDD 2000152010
36200
2025
36349
  Tdd 
35TDD 1900601850
36350
1910
36949
  Tdd 
36TDD 1900601930
36950
1990
37549
  Tdd 
37TDD PCS201910
37550
1930
37749
  Tdd 
38TDD 2.6 GHz502570
37750
2620
38249
  Tdd 
39China TDD 1.9 GHz401880
38250
1920
38649
  Tdd 
40China TDD 2.3 GHz1002300
38650
2400
39649
  Tdd 
41TDD 2.5 GHz1942496
39650
2690
41589
  Tdd 
42TDD 3.4 GHz2003400
41590
3600
43589
  Tdd 
43TDD 3.6 GHz2003600
43590
3800
45589
  Tdd 
44700 MHz APAC100703
45590
803
46589
  Tdd 

U.S. FCC 700MHz band for commercial services

FCC 700MHz band plan
lte band

U.S. FCC broadband PCS band

PCS band plan
PCS band plan

U.S. Advanced Wireless Services (AWS-1) band

AWS band plan
AWS band plan

U.S. 2300 MHz Wireless Communications Services (WCS) band

WCS band plan

LTE FDD spectrum

LTE FDD spectrum
LTE FDD spectrum

LTE TDD spectrum

LTE TDD spectrum
LTE TDD spectrum

cdma2000 bands


Band class (C.S0057-E)

CDMA2000 band class
BandNameBandwidth
(MHz)
Downlink (MHz)Uplink (MHz)Duplex spacing
(MHz)
LowHighLowHigh
0800 MHz Cellular3486089481584945
1PCS 190060193019901850191080
2TACS4391796087291545
3JTACS38832870887925-55
4Korean PCS30184018701750178090
5450 MHz7342049341048310
62 GHz IMT-2000602110217019201980190
7700 MHz Upper12746758776788-30
81800 MHz75180518801710178595
9900 MHz3592596088091545
10Secondary 800 MHz8985194080690145
11400 MHz European PAMR7342049341048310
12800 MHz PAMR691592187087645
132.5 GHz IMT-2000 Extension702620269025002570120
14US PCS 1.9 GHz65193019951850192580
15AWS452110215517101755400
16US 2.5 GHz662624269025022568122
18700 MHz Public Safety12757769787799-30
19700 MHz Lower1872874669871630
20L-Band34152515591626.51660.5-101.5
21S-Band202180220020002020180

CDMA2000 spectrum

CDMA2000 spectrum
cdma spectrum

CDMA channel numbers and corresponding frequencies

Band class 0 / 800 MHz Cellular
BlockTransmit frequency band (MHz)Top
Mobile StationBase StationBandwidth UL / DL
 A0824.025835.005869.025880.00511
 A0+844.995846.495889.995891.4952
 A1824.025835.005869.025880.00511
 A1+844.995848.985889.995893.9854
 A2824.025829.995869.025874.9956
 A3815.025829.995860.025874.99515
 B0835.005844.995880.005889.99510
 B0+846.495848.985891.495893.9852
 B1835.005844.995880.005889.99510

Band class 1 / PCS 1900
BlockTransmit frequency band (MHz)Top
Mobile StationBase StationBandwidth UL / DL
 A185018651930194515
 D18651870194519505
 B187018851950196515
 E18851890196519705
 F18901895197019755
 C189519101975199015

Band class 2 / TACS
BlockTransmit frequency band (MHz)Top
Mobile StationBase StationBandwidth UL / DL
 A872.0125879.9875917.0125924.98758
 A+890.0125897.4875935.0125942.48757
 A++905.0125908.9875950.0125953.98754
 B880.0125887.9875925.0125932.98758
 B+897.5125904.9875942.5125949.98757
 B++909.0125914.9875954.0125959.98756
 ATG894895.5849850.52

Band class 3 / JTACS
BlockTransmit frequency band (MHz)Top
Mobile StationBase StationBandwidth UL / DL
 A887.0125888.9875832.0125833.98752
 A+893.0125898838.01258435
 A++898.0125900.9875843.0125845.98753
 A+++915.0125924.9875860.0125869.987510

Band class 4 / Korean PCS
BlockTransmit frequency band (MHz)Top
Mobile StationBase StationBandwidth UL / DL
 A175017601840185010
 B176017701850186010
 C177017801860187010

Band class 5 / 450 MHz
BlockTransmit frequency band (MHz)Top
Mobile StationBase StationBandwidth UL / DL
 A452.5457.475462.5467.4755
 B452456.475462466.4754
 C450454.8460464.85
 D411.675415.85421.675425.854
 E415.5419.975425.5429.9754
 F479483.48489493.484
 G455.23459.99465.23469.995
 H451.31455.73461.31465.734
 I451.325455.725461.325465.7254
 J455.25459.975465.25469.9755
 K479483.475489493.4754
 L410414.975420424.9755
 M450457.475461.25469.9757 / 9
 N450457.475460469.9757 / 10

Band class 6 / 2 GHz IMT-2000
BlockTransmit frequency band (MHz)Top
Mobile StationBase StationBandwidth UL / DL
 Low, not valid19201922.4521102112.452
 SR11922.51977.52112.52167.555
 High, not valid1977.551979.952167.552169.952

Band class 7 / 700 MHz Upper
BlockTransmit frequency band (MHz)Top
Mobile StationBase StationBandwidth UL / DL
 C77678774675711
 A7877887577581

Band class 8 / 1800 MHz
BlockTransmit frequency band (MHz)Top
Mobile StationBase StationBandwidth UL / DL
 Low, not valid17101711.218051806.21
 SR11711.251783.751806.251878.7573
 High, not valid1783.81784.951878.81879.951

Band class 9 / 900 MHz
BlockTransmit frequency band (MHz)Top
Mobile StationBase StationBandwidth UL / DL
 Low, not valid880881.2925926.21
 SR1881.25913.75926.25958.7533
 High, not valid913.8914.95958.8959.951

Band class 10 / Secondary 800 MHz
BlockTransmit frequency band (MHz)Top
Mobile StationBase StationBandwidth UL / DL
 A806810.975851855.9755
 B811815.975856860.9755
 C816820.975861865.9755
 D821823.975866868.9753
 E896900.975935939.9755

Band class 11 / 400 MHz European PAMR
BlockTransmit frequency band (MHz)Top
Mobile StationBase StationBandwidth UL / DL
 A452.5457.475462.5467.4755
 B452456.475462466.4754
 C450454.8460464.85
 D411.675415.85421.675425.854
 E415.5419.975425.5429.9754
 I451.325455.725461.325465.7254
 J455.25459.975465.25469.9755
 K479483.475489493.4754
 L410414.975420424.9755

Band class 12 / 800 MHz PAMR
BlockTransmit frequency band (MHz)Top
Mobile StationBase StationBandwidth UL / DL
 A,C870.0125875.9875915.0125920.98756
 B871.5125874.4875916.5125919.48753

Band class 13 / 2.5 GHz IMT-2000 Extension
BlockTransmit frequency band (MHz)Top
Mobile StationBase StationBandwidth UL / DL
 A25002505262026255
 B25052510262526305
 C25102515263026355
 D25152520263526405
 E25202525264026455
 F25252530264526505
 G25302535265026555
 H25352540265526605
 I25402545266026655
 J25452550266526705
 K25502555267026755
 L25552560267526805
 M25602565268026855
 N25652570268526905

Band class 14 / US PCS 1.9 GHz
BlockTransmit frequency band (MHz)Top
Mobile StationBase StationBandwidth UL / DL
 A185018651930194515
 D18651870194519505
 B187018851950196515
 E18851890196519705
 F18901895197019755
 C189519101975199015
 G19101915199019955

Band class 15 / AWS
BlockTransmit frequency band (MHz)Top
Mobile StationBase StationBandwidth UL / DL
 A171017202110212010
 B172017302120213010
 C17301735213021355
 D17351740213521405
 E17401745214021455
 F174517552145215510

Band class 16 / US 2.5 GHz
BlockTransmit frequency band (MHz)Top
Mobile StationBase StationBandwidth UL / DL
 A25022518.526242640.517
 B2518.525352640.5265717
 C25352551.526572673.517
 D2551.525682673.5269017

Band class 18 / 700 MHz Public Safety
BlockTransmit frequency band (MHz)Top
Mobile StationBase StationBandwidth UL / DL
 A7877887577581
 D7887937587635
 Public Safety Broadband7937987637685
 Public Safety Guard band7987997687691

Band class 19 / 700 MHz Lower
BlockTransmit frequency band (MHz)Top
Mobile StationBase StationBandwidth UL / DL
 A6987047287346
 B7047107347406
 C7107167407466

Band class 20 / L-Band
BlockTransmit frequency band (MHz)Top
Mobile StationBase StationBandwidth UL / DL
 Low, not valid1626.51627.115251525.61
 SR11627.151659.851525.651558.3533
 High, not valid1659.91660.51558.415591

Band class 21 / S-Band
BlockTransmit frequency band (MHz)Top
Mobile StationBase StationBandwidth UL / DL
 A200020102190220010
 B201020202180219010

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