Berikut ini kumpulan tips mengenai rancangan slide presentasi yang akan saya coba selalu update setiap kali saya menemukan kesalahan baru. Semoga membantu.

Perhatikan pada semua gambar yang mengandung teks, biasanya berupa flowchart (terutama flowchart metodologi penelitian), untuk dipastikan teksnya mudah dibaca. Jangan copy paste langsung gambar dari aplikasi lain karena biasanya akan mengecil dan akibatnya  sulit untuk dibaca tulisannya. Dosen anda tidak semuanya masih muda, banyak yang sudah senior, sehingga pastikan anda menggunakan huruf besar dalam materi presentasi. Saran saya selalu buat ulang gambar grafik di slide presentasi.

Huruf slide adalah simple, jenis huruf yang jelas, ukuran huruf yang bisa dibaca dari jarak 10 m dari dinding. Memang ada perbedaan minimum size font untuk ruangan kecil (min 18 pt ) dan ruangan besar (min 24 pt ) untuk font body.

Pastikan jika akan tidak menggunakan komputer sendiri, menggunakan font yang pasti ada atau standard di aplikasi tersebut sendiri. Terkadang jika di komputer kita ada aplikasi grafis, maka font-font nonstandard akan ditambahkan dan tampil dalam menu powerpoint. Ini karena windows akan mengumpulkan semua font dan menampilkannya. Akibatnya jika anda menggunakan font khusus, tapi di komputer untuk presentasi tidak ada, maka tampilan slide anda akan berantakan. Saran saya gunakan Arial dan Times new Roman, karena di windows ataupun macOS kedua font ini ada.

Warna slide huruf yang kontras dengan latar belakangnya, jika background Jangan jadikan anda sebagai referensi, jika bagi anda mudah atau sudah jelas belum

tentu bagi orang lain adalah sama. Perhatikan yang jelas di screen komputer anda belum tentu jelas di tampilan LCD. LCD yang dimiliki departemen juga memiliki kualitas terang yang berbeda-beda sehingga belum tentu warna-warna yang anda lihat di screen komputer bisa direproduksi dengan tepat ke layar utama.

Layout yang natural dari atas ke bawah dan kiri ke kanan. Ini karena memang bahasa indonesia didesain seperti lain dengan bahasa lain di dunia.

Perhatikan cetakan handsout Presentasi. Warna-warna jelas dilayar belum tentu memiliki hasil cetak yang mudah dibaca. Kombinasi warna-warna cantik dilayar bisa mengakibatkan gambar pudar, huruf yang tidak tercetak jelas (apalagi dengan kualitas fotocopy yang buruk). Jika perlu buatlah versi hitam putih dari presentasi anda terlebih dahulu untuk dicetak sebagai handsout.

Jangan tampilkan 222,32451231. Siapa yang peduli dengan 6 angka terakhir? Bulatkan secukupnya. Kecuali ini adalah presentasi paper ilmiah yang membutuhkan detail dan detail itu perlu

Gunakan skala yang sama untuk menunjukkan perbandingan antara grafik/chart . Saya sering melihat presentasi yang membandingkan dengan skala berbeda, dan sempat bingung kenapa kok chartnya tidak banyak perubahan. Misalnya  yang dikiri menggunakan skala 50 sedangkan kanan skala 100, sehingga jika terjadi perbaikan,  menjadi tidak terlihat.

Pastikan ada NOMOR Slide, yang juga dicetak dalam handsout, karena dalam tanya jawab penguji sering meminta untuk ditampilkan slide tertentu. Tanggal tidak usah.

Animasi harus memiliki tujuan. Anda bukan lagi anak kecil, jadi gambar animasi kelinci melompat, buku terbuka dll, jika tidak memiliki nilai tambah dalam slide, malah akan mengganggu pemahaman terhadap isi slide.

Hindari Animasi dalam Slide berbasis kepada click mouse. Karena membuat anda seolah-olah sibuk mengclick-click mouse seperti orang yang nervouse menclick-click ballpointnya. Belum lagi jika tiba-tiba ada lag antara click dan animasinya (biasanya karena

komputernya lambat dan file gambar yang besar), maka akan mengganggu proses penjelasan anda. Saran saya animasikan secara otomatis tanpa harus mengclick mouse setiap slide. Gunakan mouse hanya untuk penegasan akhir slide dan pindah ke slide berikutnua

Gunakan Judul sebagai Kesimpulan Isi Slide. Gunakan judul sebagai kesimpulan apa yang kamu inginkan ketika orang melihat slide tersebut. Jika slide itu berisi sebuah grafik perbandingan dengan faktor C tertinggi misalnya maka judul slide adalah “faktor C mendominasi keseluruhan penyebab …”

In pre-launch optimization, how are missing neighbors usually detected?Usually you use a scanner and compare the best pilots in Ec/Io from the scanner against that of the active set and monitored set from an active UE. If there is a stronger pilot from a nearby cell that appears on the scanner but not on the UE, there is a possible missing neighbor. One would then verify that the neighbor appears in defined neighbor list from the OSS.

You might also like: What is an active set, monitor set and detected set? How would you find such cells from a planning tool and from a drive test

tool? TDMA In HSDPA, how does the network manage the throughput on the Radio

Interface for a user/ connection?

TRAFFIC CASES LinkWithin

0 comments Links to this postExplain the concept of a Monte Carlo Simulation for UMTS DesignThis is a simulator that randomly distributes terminals/users geographically onto the network and then checks the link budget for each terminal/connection to see if they can successfully connect or not. The simulator modifies parameters such has UE Tx Power, BTS Tx Power, requested bearer (in the case that multiple bearers could support the same service) when checking if a connection can be made. In every snapshot the simulator runs through the list of terminals/connections and attempts to make them all connect successfully, it starts a new snapshot when the number of successful connections converges. The process then starts on a new snapshot.

You might also like: Explain the different Handover types in UMTS In what cases is Open Loop Power Control used? Monte Carlo/ ASSET experienced senior RNPI/ RND engineers required 3G Mobile System TRAFFIC CASES

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0 comments Links to this postIn what cases is Open Loop Power Control used?This is a simulator that randomly distributes terminals/users geographically onto the network and then checks the link budget for each terminal/connection to see if they can successfully connect or not. The simulator modifies parameters such has UE Tx Power, BTS Tx Power, requested bearer (in the case that multiple bearers could support the same service) when checking if a connection can be made. In every snapshot the simulator runs through the list of terminals/connections and attempts to make them all connect successfully, it starts a new snapshot when the number of successful connections converges. The process then starts on a new snapshot.

You might also like: Explain Inner and Outer loop power control and who controls them. TRAFFIC CASES 3G Mobile System What is compressed mode, what is it's function, and what impact does it

have on the network? Some Question Answer of 3G

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0 comments Links to this postExplain Inner and Outer loop power control and who controls them.If they start talking about Open and Closed Loop PC, tell them you want Inner/Outer Closed Loop PC. Inner loop power control is performed by the NodeB to set the transmit power of the UE and BTS to compensate for signal variations due to fading or pathloss to maintain the set SIR (occurs up to 1500 times per sec). Outer loop power control is performed by the RNC to set the target SIR based on the required BER/BLER for the requested services (occurs up to 100 times per sec).

You might also like: In what cases is Open Loop Power Control used? 3G Mobile System Explain the concept of a Monte Carlo Simulation for UMTS Design Explain the different Handover types in UMTS Some Question Answer of 3G

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0 comments Links to this postIn HSDPA, how does the network manage the throughput on the Radio Interface for a user/ connection?Modulation (16QAM, QPSK etc), Coding (convolution coding, fire codes etc), number of codes allocated and scheduling (it's a shared resource)

You might also like: In Release '99, how does the network manage the throughput on the

Radio Interface for a user/connection? GSM Interfaces Depending on the RF conditions, what can the network do to manage

call quality? 3G Mobile System TRAFFIC CASES

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0 comments Links to this postDepending on the RF conditions, what can the network do to manage call quality?AMR - for good conditions use codec will low redundancy/overhead; for poor conditions use codec with lower bit rate requirement but higher overhead, stronger coding and more redundancy.

You might also like: What is compressed mode, what is it's function, and what impact does it

have on the network? In HSDPA, how does the network manage the throughput on the Radio

Interface for a user/ connection? What are the general triggers for an iRAT handover? In Release '99, how does the network manage the throughput on the

Radio Interface for a user/connection? What would you define as a pilot polluter?

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0 comments Links to this postWhat is the typical/most common bitrate that a voice call uses?They should say 12.2kbps but may be different if they start talking about AMR and the different rates then the know more. Prod them to see if they know the Spreading Factor (SF) used for the radio bearer, should be 128.

You might also like: What is the typical maximum active set size and what needs to be

consider when setting this? Depending on the RF conditions, what can the network do to manage

call quality? What is compressed mode, what is it's function, and what impact does it

have on the network? What are the general triggers for an iRAT handover? In what cases is Open Loop Power Control used?

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0 comments Links to this postIn Release '99, how does the network manage the throughput on the Radio Interface for a user/connection?This question is a little harder to ask, so you may need to work it differently a few times. Perhaps leading questions could be: What parameter/configuration does the network change on the air interface What you are trying to hear from the candidate is that the network assigns a radio bearer with a channelization code with a spreading factor that matches the requested service maximum bit rate.

You might also like: In HSDPA, how does the network manage the throughput on the Radio

Interface for a user/ connection? GSM Interfaces Depending on the RF conditions, what can the network do to manage

call quality?

Some Question Answer of 3G Important Topics

LinkWithin

0 comments Links to this postIf a UE is on a data call (CELL-DCH state) and there is in no activity for awhile what would you expect to see occur?UE should go from CELL-DCH to CELL-FACH then if still no activity to either CELL-PCH or URA-PCH (via CELL-FACH). If they talk about inactivity timers and mention that the state goes from CELL-DCH straight to CELL-PCH or URA-PCH, that is also possible. Bonus they say they would see RADIO BEARER RECONFIGURATION messages when the states are changing.

You might also like: Some Question Answer of 3G What would you define as a pilot polluter? Important Topics Name the 4 RRC Connected Modes (states) and describe the

characteristics of each. What is typically the requirements (criteria) for a cell to be

added/removed/replaced to/from/in the active set?LinkWithin

0 comments Links to this postName the 4 RRC Connected Modes (states) and describe the characteristics of each.Cell-DCH: UE has been allocated a dedicated physical channel in

uplink and downlink.

Cell-FACH: UE listens to RACH channel (DL) and is allocated a FACH channel (UL). Small amounts of UL/DL data can be transfers in this state. The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message.

Cell-PCH: UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel. The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message. No data can be transferred in the UL in this state.

URA-PCH: UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel. The RNC tracks the UE down to the URA level.

You might also like: Some Question Answer of 3G 3G Mobile System If a UE is on a data call (CELL-DCH state) and there is in no activity for

awhile what would you expect to see occur? What would the call flow be for a Mobile Originated Call (major RRC

messages)? In HSDPA, how does the network manage the throughput on the Radio

Interface for a user/ connection?LinkWithin

3 comments Links to this postWhat is compressed mode, what is it's function, and what impact does it have on the network?Compressed mode is when the mobile goes into a slotted transmit mode whereby it opens up an idle period (transmission gap) where it can monitor another carrier or technology (GSM). The impact is that to maintain the same bit rate, it halves the SF, and therefore increases power level causing higher interference to the network. If the SF cannot be halved then the bit rate of the bearer decreases. If they seem knowledgably, ask them if they know what messages and events trigger and configure compressed mode on/off. 2D event for on, 2F for off.  Messages would for configuration would be RADIO BEARER RECONFIGURATION, TRANSPORT CHANNEL RECONFIGFURATION or PHYSICAL CHANNEL RECONFIGURATION.

You might also like: In the Link Budget, what is a Shadow Fade Margin for and what factors

does it depend on? Important Topics What is the typical maximum active set size and what needs to be

consider when setting this? In what cases is Open Loop Power Control used? Depending on the RF conditions, what can the network do to manage

call quality?LinkWithin

0 comments Links to this postWhat are the general triggers for an iRAT handover?Ec/Io of best cell below a certain threshold (usually around -16 to -18 dB) or RSCP of best cell below a certain threshold (usually around -100 dBm)

You might also like: Explain the different Handover types in UMTS

What is compressed mode, what is it's function, and what impact does it have on the network?

What would you define as a pilot polluter? What is the typical maximum active set size and what needs to be

consider when setting this? Depending on the RF conditions, what can the network do to manage

call quality?LinkWithin

0 comments Links to this postWhat would the call flow be for a Mobile Originated Call (major RRC messages)?RRC Connect Request -> RRC Connection Setup -> RRC Setup Complete -> (SETUP, authentication encyrption, TMSI reallocation etc) -> CALL PROCEEDING-> Radio Bearer Setup -> Radio Bearer Setup Complete -> ALERT -> CONNECT -> CONNECT ACK ->DISCONNECT -> RELEASE.

You might also like: What would you define as a pilot polluter? Depending on the RF conditions, what can the network do to manage

call quality? TRAFFIC CASES What is compressed mode, what is it's function, and what impact does it

have on the network? Important Topics

LinkWithin

0 comments Links to this postHow would you find such cells from a planning tool and from a drive test tool?Ignoring low signal conditions, if the best cell RSCP is greater than say -85dBm and there are cells not in the active set but are strong enough to be in the active set then they are candidate for pilot polluters. Looking at cells that have a high noise rise, high amount of traffic compared to surrounding cells, may also indicate a pilot polluter. Areas with high Signal strength for the (Active Set Size + 1) best pilot (like the 4th best pilot if AS size is 3). In DTT, areas with poor Ec/Io but good RSCP, in the monitored set contains a cell with a good Ec/Io but cannot enter the AS because it is full. Areas where scanner shows a strong signal for a far away cell.

You might also like: What would you define as a pilot polluter? Some Question Answer of 3G

In pre-launch optimization, how are missing neighbors usually detected? What is typically the requirements (criteria) for a cell to be

added/removed/replaced to/from/in the active set? 3G Mobile System

LinkWithin

0 comments Links to this postWhat would you define as a pilot polluter?Many definitions: A cell that has a high signal strength at a location but is not part of the active set. A cell that meets the criteria for addition into the Active Set but can not enter because the active set is full.

You might also like: How would you find such cells from a planning tool and from a drive test

tool? What is the typical maximum active set size and what needs to be

consider when setting this? What is compressed mode, what is it's function, and what impact does it

have on the network? What are the general triggers for an iRAT handover? What is typically the requirements (criteria) for a cell to be

added/removed/replaced to/from/in the active set?LinkWithin

0 comments Links to this postWhat is typically the requirements (criteria) for a cell to be added/removed/replaced to/from/in the active set?For addition (Event 1a), candidate cell needs to have an Ec/Io value that is within a T_ADD threshold of the primary/reference (usually the best) cell for a specify time hysteresis. For removal (event 1b), cell needs to have Ec/Io lower than T_DROP margin for a specific time hysteresis. For replacement (event 1c), cell needs to have an Ec/Io better than the worst cell in the active set by the T_REPLACE and for a specific time hysteresis.

0 comments Links to this postWhat is the typical maximum active set size and what needs to be consider when setting this?3 to 4 cells, the larger the active set size the more likely it is that Iub link efficiency is reduced (more than one resource for a single connection due to SHO)

0 comments Links to this postIn the Link Budget, what is a Shadow Fade Margin for and what factors does it depend on?

The shadow fade margin is dependent on the target percentage area coverage, the propagation model, and the standard deviation of the lognormal shadowing (usually the same as the model's standard deviation if the fast fading effects are removed). The Shadow Fade Margin is a added margin placed in the link budget such that a guaranteed level of service can be offered "in the worst case"

1 comments Links to this postWhat is the major difference in link budgets between UMTS and GSM/TDMA?What is the major difference in link budgets between UMTS and GSM/TDMA?

 

In UMTS you generally have a link budget for each service (voice, data, video etc), in GSM you usually only use 1 for voice. Each service has a different Eb/No target. In UMTS you have to consider the target traffic load you will have and add a noise-rise margin, in GSM you may have a slight interference margin but not normally related to traffic. In UMTS some services (like voice) will show up as uplink limited but other services (like HSDPA, 384kbps service) will show as downlink limited. In UMTS you usually have to consider that all users use the same power from the BTS therefore the more number of users the lower the maximum power available per user (maximum power per connection) which is a starting point in the link budget.

1 comments Links to this postWhat is an active set, monitor set and detected set?What is an active set, monitor set and detected set?

 

Active Set: the set of cells with which the UE is currently connected/communicating with; DriveTT usually show them as SC or Pilots but they are actually cells; Monitored Set: Cells that the UE has detected and is monitoring and are known to the network, they either don't meet the criteria or the active set is full; Detected Set - Cells that the UE has detected but are not known to the network as yet (missing neighbor likely).

Ericsson Important Optimization Parameters

System ConfigurationprimaryCpichPower: Parameter that controls the power level of the Primary

CPICH.maximumTransmissionPower: Parameter that can be used to limit the total DL power in a cell to a value lower than DL power capability of the RBS.maxTxPowerUl: Used in UE functions for cell selection/ re-selection in idle mode and connected mode and also used by UTRAN to control the maximum transmitted power level a UE can use.

Capacity ManagementcompModeAdm: Absolute admission limit for the number of radio links in compressed mode in a cell.dlCodeAdm: Parameter that defines in percentage the absolute admission limit for DL code usagepwrAdm: Parameter that defines in percentage the absolute admission limit for DL power utilization.sf8Adm: Defines the absolute admission limit for the number of RLs with SF=8 (PS384) in DL.sf16Adm: Defines the absolute admission limit for the number of RLs with SF=16 (PS128 RAB) in DL.sf32Adm: Defines the absolute admission limit for the number of RLs with SF=32 (PS64) in DL.sf4AdmUl: Absolute admission limit for the number of RLs with SF=4 in UL (PS384/HS)sf8AdmUl: Defines the absolute admission limit for the number of RLs with SF=8 in UL.sf16AdmUL: Parameter that defines absolute admission limit for the number of RLs with SF=16 in UL.

Directed RetryloadSharingDirectedRetryEnabled: An RNC-wide flag for turning on the feature.directedRetryTarget: UA cell specific parameter that specifies the Directed Retry target in terms of a cell reference to an external GSM cell.loadSharingGSMThreshold: A cell specific parameter that specifies the load sharing threshold below which Directed Retry to GSM is suppressed.loadSharingGSMFraction: A cell specific parameter that specifies the fraction of qualified speech calls to be diverted to GSM.

HandovermaxActiveSet: Maximum number of cells allowed in the Active Set.IndividualOffset: Offset value which can be assigned to each cell. It is added to the measurement quantity before the UE evaluates whether or not an event has occurred. It can either be positive or negative value.measQuantity1: Defines the measurement quantity for intra-frequency reporting

evaluation. Default is EcNo.hsQualityEstimate: Indicates whether Ec/No or RSCP should be used for indicating "best cell" for HS-DSCH Cell Change. Default is RSCP.reportingRange1a: Relative threshold referred to the CPICH of the best cell in the Active Set used as evaluation criteria for event 1a (a primary CPICH enters the reporting range).reportingRange1b: Relative threshold referred to CPICH of the best cell in the Active Set used as evaluation criteria for event 1b (a primary CPICH leaves the reporting range).reportingInterval1a: Time between periodic reports at event-triggered periodic reporting for event 1atimeToTrigger1a: If event 1a condition is fulfilled during at least a time greater than or equal to timeToTrigger1a milliseconds, then event 1a occurs.timeToTrigger2dEcno: If event 2d condition is fulfilled during at least a time greater than or equal to timeToTrigger2dEcno milliseconds, then event 2d occurs

HSDPA/EULnumHsPdschCodes: Parameter that defines the number of codes allocated in a call only for HS-PDSCH (SF 16).maxNumHsPdschCodes: Defines the maximum number of HS-PDSCH codes that may be allocated in a cell.hsdpaUsersAdm: Cell parameter that defines the admission limit for the number of users assigned to the HS-DSCH. Applicable to admission requests related to RAB setup of an HSDPA service.maxNumHsdpaUsers: Limits the maximum allowed number of simultaneous HSDPA users per cell that can be served.eulServingCellUsersAdm: Defines the admission limit for the number of EUL users having the cell as serving cell.eulNonServingCellUsersAdm: Cell parameter that defines the admission limit foe the number of EUL users having the cell as non-serving cell.hsdschInactivityTimer: Time during which throughput has to be low in order to trigger a down-switch (dedicated to common state) for a UE in state DCH/HS or in state EUL/HS.

IRATusedFreqThresh2dRscp: Threshold for event 2d (the estimated quality of the currently used WCDMA RAN frequency is below a certain threshold) based on RSCP measurements.usedFreqThresh2dEcno: Threshold for event 2d (the estimated quality of the currently used WCDMA RAN frequency is below a certain threshold) based on EcNo measurements..

gsmThresh3a: Threshold for event 3a (the estimated quality of the currently used WCDMA RAN frequency is below a certain threshold and the estimated quality of the GSM system is above a certain threshold) for GSM.gsmPropRepeatInterval: Minimum time interval between proposals of the same GSM cell for handover based on the same measurement report.gsmAmountPropRepeat: Maximum number of repeated proposals (not including the first proposal) of GSM cells for handover based on the same measurement report.

Idle Mode (Selection/ Reselection)qQualMin: Minimum required quality level in the cell measured in the UE.qRxLevMin: Parameter that indicates the min. required signal strength in the cellqualMeasQuantity: Used for decision as to whether the 3G ranking for cell selection and reselection is based on EcNo or RSCP. Default is EcNo.qHyst1: Hysteresis values used for serving cell, when ranking is based on CPICH RSCPqHyst2: Hysteresis values used for serving cell, when ranking is based on CPICH EcNoqOffset1sn: Signal strength offset b/w source and target cell for cell ranking based on CPICH RSCP.qOffset2sn: Signal offset between serving cell and neighbor cell, based on CPICH EcNo.sIntraSearch: Decision on when intra-freq. measurements should be performed. Following criteria is used:sIntraSearch ≥ qQualmeas - qQualMin (where qQualmeas is the value measured by UE )sInterSearch: Parameter is used to make decision to start inter-freq. measurements.sInterSearch ≥ qQualmeas - qQualMin (where qQualmeas is the value measured by UE )sRatSearch: Decision on when GSM measurement should be performed in relation to qQualMin.sRatSearch ≥ qQualMeas – qQualMin (where qQualmeas is the value measured by UE )sHcsRatSearch: Decision on when GSM measurement should be performed in relation to qRxLevMin.sHcsRatSearch ≥ qRxLevMeas – qRxLevMin (where qRxLevMeas is the value measured by UE)

RRC connection exists when a UE went through the connection establishment procedure and has been allocated resources in the UTRAN and a U-RNTI. With RRC connection, some SRBs are allocated.

RAB (Radio Access Bearer) is created to provide user plane data transfer. RAB comprises

1. RB and

2. connection from the SRNC to the SGSN (Iu bearer).

The RAB is created on reequest from the SGSN with a specific QoS request. For a given UE, there can be multiple RABs per NAS service (speech or PS data service).

RB (Radio Bearer) is a layer 2 connection between the UE and the RNC. It is used for both control signaling and user data. RB used for signaling is called an SRB.

What is in paging message?

MIB value tag, BCCH modification time

For each paging record:

for UTRAN originated: u-RNTI, CN-ORIGINATEDPAGE-CONNECTEDMODE-UE, paging cause, CN domain id, paging record type [IMSI, TMSI, P-TMSI]

for CN originated: paging cause, CN domain id (CS or PS), CN paged UE identities (IMSI, TSMI, P-TMSI + value)

MIB value tag, BCCH modification time

for UTRAN originated: u-RNTI, CN-ORIGINATEDPAGE-CONNECTEDMODE-UE, paging cause, CN domain id, paging record type [IMSI, TMSI, P-TMSI]

for CN originated: paging cause, CN domain id (CS or PS), CN paged UE identities (IMSI, TSMI, P-TMSI + value)

LA: location area

RA: routing area

URA: UTRAN routing area

The aboves are the collections of cells.

LA and RA are for CN to track the movement of the UE to facilitate the paging of the mobile when an active radio connection is not available.

A cell can be in up to eight different URAs.

URA size depends on the UE’s velocity. Fasting moving UEs should be in a large URA to make less URA update.

TCH Drop: Reason & Solution

Drop during conversation is known as TCH drop. It takes place after connect ACK msg on TCH.TCH drop occurring.

For TCH drop first cross check the BCCH of that cell, hardware issue may be, change RXP and RLT value. Find out there is any interference ,neighbor defined.

Reasons for TCH Drop:

Wrong Parameter Planning. BAD HOSR. Hardware Fault. High TR Fail. Overshoot. Outage.

Due to Low Coverage. Due to ICM Band(CDMA)

Solutions for removal of TCH Drop:Check Parameter:

Check the BCCH Plan (C/I or C/A), Co-BSIC & Co BCCH. Check the Timer T 100(should be 20 ms)

Check Overshooting:

If a cell is picking call from long distance, Check the sample log according to TA..

Site Orientation. Effective tilt should be check. Mount position should be check

Improve HOSR:

Check the Hopping plan. Check the Neighbor Plan

High TR Fail:

Check and clear TR fail from oss end.

Check HW:

Check Alarms on site. Check TRXs,Check Slips. Check the Hopping plan. Check BB2F card., Check VSWR, Path imbalance,Connector, Connection,Check TMA

For Ericsson Vendor. When TCH is not allocated to the user after SD allocation ,it is TCH

Blocking. It is the failed call attempts which the MS user can notice. It takes place due to lack of TCH Resource.

Reasons for TCH Blocking: High Utilization of TCH Time slot faulty. Lock TRXs. HW Problem.

Solutions for removal of TCH Blocking: Implement half rate or Dual rate.

Check FRL & FRU. Add another TRX. If TRX addition not possible, try to share the traffic of that cell with the

neighboring cell by changing tilt or orientation.Useful Report for TCH Blocking: 135 TCH Congestion

Which Parameters helps to reduce TCH Congestion Rate in Huawei System?

Below mentioned parameters may cause TCH Congestion & also help you to reduce TCH Congestion:

1. TCH Traffic Busy Threshold(%) 2. RXLEV_ACCESS_MIN3. SACCH Multi-Frames and Radio Link Timeout4. SDCCH Dynamic Adjustment5. RACH Min.Access Level 6. Speech Version7. TCH Immediate Assignment8. Speech Version9. Fix Abis Prior Choose Abis Load Threshold10. Assignment Cell Load Judge Enable 11. Flex Abis Prior Choose Abis Load Threshold12. Directed Retry Load Access Threshold 13. Balance Traffic Allowed 14. Load HO Allowed 15. Load HO Step Period 16. Load HO Step Level17. Cell Direct Try Forbidden Threshold 18. Direct Retry 19. SDCCH Dynamic Adjustment 20. Direct Retry and Cell Direct Try Forbidden Threshold21. AMR TCH/H Prior Allowed22. T3103 23. T310724. F2H HO th/ H2F HO th25. Maximum Ratio Threshold of PDTCH 

TCH Drop Analysis1. Radio Link Time-Out

Every time a SACCH message can not be decoded the radio link time-out counter is decreased by 1. If the message can be decoded the counter is incremented by 2. However, the value can not exceed the initial value. The initial value is set by the parameter RLINKT for radio link time-out in the mobile station and by RLINKUP for timeout in the BSC. If the mobile moves out of coverage and no measurement reports are received in the BSC, there will be a radio link time-out and the message Channel Release (cause: abnormal release, unspecified) is sent to the mobile station and the SACCH is deactivated in the BTS. A Clear Request message is sent to the MSC. To be sure that the mobile has stopped transmitting, the BSC now waits RLINKT SACCH periods before the timeslot is released and a new call can be established on the channel.

2. Layer 2 Time-Out

If the BTS never get an acknowledge on a Layer 2 message after the time T200XN200, the BTS will send Error Indication (cause: T200 expired) to the BSC, which will send Channel Release (cause: abnormal release, timer expired) to the mobile station and a Clear Request to the MSC. The SACCH is deactivated and the BSC waits RLINKT SACCH periods before the timeslot is released and a new call can use the channel. This is only valid if the call is in steady state, i.e. not during handover or assignment.

3. Release Indication

When the BTS received a layer 2 DISC frame from the mobile it replies with a Layer 2 UA frame to the mobile station and a Release Indication to the BSC. The system does only react on Release Indication if it is received during a normal disconnection situation. If such a message is received unexpectedly this will usually cause radio link time-out or timer T200 expiration as the mobile station stops the transmitting of measurement reports. It is also possible that the release will be normal depending on when the Release Indication is received.

4. MSC Time-OutNormal Release:

If the MSC never received a response on a message (e.g. Identity Request) and there is no radio link time-out or layer 2 time-out, the MSC will send a Clear Command to the BSC. The time-out is depending on the message. When receiving Clear Command, the BSC will send a Channel Release (cause: normal release) and then deactivates the SACCH.

Reject (only SDCCH):

If the MSC never receives a response on the first message after Establish Indication, the MSC will send a reject message. If the connection was a Location Update it will be a Location Update Reject (cause: network failure) and if the connection was a mobile originating call (CM Service Request) a CM Service Reject (cause: network failure) will be sent. The MSC will then send a Clear Commandto the BSC and the call is cleared by Channel Release (cause: normal release).

5. Assignment to TCH

Before sending an Assignment Command from the BSC at TCH assignment, the following two criterion have to be fulfilled:

a. There must be a TCH channel available, i.e. no congestionb. The locating algorithm must have received at least one valid measurement report.

If either of the criterion is not fulfilled, Assignment Command will not be sent and a Channel Release (cause: abnormal release, unspecified) will be sent to the mobile station and a Clear Request to the MSC.

TCH Drop reason (1)The classification of TCH Drop Reasons are arranged in the order of priority:1.ExcessiveTiming Advance2.Low Signal Strength3.Bad Quality4.Sudden Loss of Connection5.Other Reasons

Excessive Timing Advance

The TCH Drop counters due to Excessive Timing Advance will pegged when the during the time of disconnection, the last Timing Advance value recorded was higher than the TALIM Parameter. This drop reason is commonly apparent to isolated or island sites with a wide coverage area.

Action:Check if the cell parameter TALIM is < "63" Solution:Set TALIM to a value close to 63.Tilt antenna/reduce antenna height/output power, etc. for co-channel cells.

TCH Drop Reasons (2)Low Signal Strength on Down or Uplink or Both Links

The drops counters due to Low Signal Strength will be pegged when the Signal Strength during the last Measurement Report before the call dropped is below the LOWSSDL and/or LOWSSUL Thresholds. LOWSSDL and LOWSSUL are BSC Exchange Property parameters which is used only for statistics purposes and does not affect the behavior of calls. If both UL and DL Signal Strengthare below the thresholds, only Drop due to Low SS BL will pegged. Normally a call is dropped at the border of large rural cell with insufficient coverage. Bad tunnel coverage cause many dropped calls as well as so called coverage holes. Bad indoor coverage will result in dropped calls. Building shadowing could be another reason.

Action:Check coverage plots.Check output power.Check power balance and link budget.Check if Omni site.Check antenna configuration & type.Check antenna installation.Perform drive tests & site survey.Check TRX/TS with high CONERRCNT.

Solution:

Add a repeater to increase coverage in for example a tunnel.Change to a better antenna (with higher gain) for the base station.Add a new base station if there are large coverage holes.Block/Deblock TRX

TCH Drop Reasons (3)Poor Quality on Down or Uplink or Both Links

The drops counters due to Bad Quality will be pegged when the Signal Strength during the last Measurement Report before the call dropped is above the BADQDL and/or BADQUL Thresholds. BADQDL and BADQUL (expressed in DTQU) are BSC Exchange Property parameters which is used only for statistics purposes and does not affect the behavior of calls. If both UL and DL Quality are above the thresholds, only Drop due to BAD Quality BL will pegged.

Problem on Bad Quality is usually associated with Co-channel Interference on BCCH or TCH. Faulty MAIO assignment can cause frequency collisions on co-sited cells especially on 1x1 Reuse. External interference is also one possible cause of problem on quality.

Action:Check C/I and C/A plots.Check Frequency Plan (Co-BCCH or Co-BSIC Problem).Check MAIO, HOP, HSN parameters.Check FHOP if correctly configured (BB or SY).Check for External Interference.Perform drive tests.

Solution:Change BCCH frequency.Change BSIC.Change MAIO, HOP, HSN.Change FHOP.Record RIR or on-site Frequency Scanning to identify source of interference.Use available radio features.

TCH Drop Reasons (4)Sudden Loss of Connection

Drops due to Sudden Loss are drops that have not been registered as low signal strength, excessive timing advance, bad quality or hardware (other) reasons, and the locating procedure indicates missing measurement results from the MS.

There are some common scenarios that could lead to Sudden Loss of connections such as very sudden and severe drops in signal strength, such as when subscribers enter into buildings, elevators, parking garages, etc., very sudden and severe occurrence of interference, MS runs out of battery during conversation, Handover Lost, BTS HW faults, Synchronization or A-bis link fault (transmission faults), and

MS Faults.

Action:Check BTS Error Logs, Alarms and Fault Codes.Check CONERRCNT per TRX and TS.Check Transmission Link (A-bis).Check for DIP Slips.Check LAPD Congestion.Correlate Handover Lost to Drops due to Sudden Loss

Solution:Fix Hardware Faults and Alarms.Reset TRX with high CONERRCNT.Ensure that Synchronization and A-bis Link are stable.Change RBLT with high DIP Slips.Change CONFACT or increase Transmission CapacityInvestigate HO Lost Problem

TCH Drop Reasons (5)TCH Drops due to Other ReasonsTCH drops due to Other Reasons are computed by subtracting the sum of drops due to Excessive TA, Low SS, Bad Quality and Sudden Loss from the Total TCH Drop Counts. Drops due to Other Reasons are generally associated with hardware problems, transmission link problems on A-bis, Ater or Ainterfaces, and sometimes Handover

Lost.

Action:Check BTS Error Logs.Check Alarms and Fault Codes.Check CONERRCNT per TRX and TS.Check Transmission Link (A-bis).Check for DIP Slips.Correlate Handover Lost to Drops due to Other Reasons

Solution:Fix Hardware Faults and Alarms.Reset TRX with high CONERRCNT.Ensure that Synchronization and A-bis Link are stable.Change RBLT with high DIP Slips.Investigate HO Lost Problem

Problem reason of drop in SDCCH

Low Signal Strength on Down or UplinkThe reason for poor coverage could be too few sites, wrong output power, shadowing, no indoor coverage or network equipment failure.Action: Check coverage plots.Check output power. Perform drive tests. Check BTS error logSolution: Add new sites. Increase output power. Repair faulty equipment.

Poor Quality on Down or UplinkAction: Check C/I and C/A plots. Check frequency plan. Perform drive tests.Solution: Change frequency. Use available radio features.

Too High Timing AdvanceAction: Check if the cell parameter TALIM is < style="font-weight: bold;">Solution: Set TALIM to a value close to 63. Tilt antenna/reduce antenna height/output power, etc. for cochannel cells.

Mobile Error

Some old mobiles may cause dropped calls if certain radio network features are used. Another reason is that the MS is damaged and not working properly.Action: Check MS fleet.Solution: Inform operator.

Subscriber BehaviorPoorly educated subscribers could use their handsets incorrectly by not raising antennas, choosing illadvised locations to attempt calls, etc.Action: Check customer complaints and their MS.

Battery FlawWhen a subscriber runs out of battery during a conversation, the call will be registered as dropped call due to low signal strength or others.Action: Check if MS power regulation is used. Check if DTX uplink is used.

Congestion on TCHThe SDCCH is dropped when congestion on TCH.Action: Check TCH congestionSolution: Increase capacity on TCH or using features like Assignment to another cell, Cell Load Sharing, HCS, Dynamic Half-Rate Allocation and FR-HR Mode Adaptation etc