[MR Preprocessing] •
Value Range: Yes, No
•
Default Value: No
•
Description: This parameter indicates whether the BTS pre-processes the MR. This parameter determines the location where power control is performed. If this parameter is set to Yes, power control is performed by the BTS. Otherwise, the power control is performed by the BSC. When this parameter is set to No, the MR is processed by the BSC, in which case, both Transfer original MR, Transfer BS/MS power class and Sent Freq of preprocessed MR are invalid. When this parameter is set to Yes, the load over Abis interface and that over the BSC are reduced, thus shortening the response time and improving the network performance.
[Transfer Original MR] •
Value Range: Yes, No
•
Default Value: No
•
Description: This parameter indicates whether the original MR is transferred to the BSC after the BTS pre-processes the MR. When the parameter is set to Yes, the BTS transfers to the BSC both the processed MR and the original MR.
•
Remarks:In case of 4:1 configuration, this parameter must be set to No if SDCCH/8 is greater than 2.
[Transfer BS/MS Power Class] •
Value Range: Yes, No
•
Default Value: Yes
•
Description: This parameter indicates whether the original BS/MS power class is transferred to the BSC.
•
Remarks:When MR pre-processing is enabled, uplink and downlink balance measurement is affected if this parameter is set to No. In addition, power compensation
1
handovers, such as PBGT handovers, load handovers, and Concentric Cell handovers, may become abnormal.
[Sent Freq of Preprocessed MR] •
Value Range: Do not Report, Twice every second, Once every second, Once every two seconds, Once every four seconds
•
Default Value: Twice every second
•
Description: This parameter indicates the frequency that the BTS transfers the preprocessed MR to the BSC. After the MR is preprocessed by BTS, the BTS transfers the preprocessed MR to the BSC. For example, if this parameter is set to Twice every second, the BTS transfers the preprocessed MR to the BSC twice per 0.5 second.
[Allowed MR Number Lost] •
Value Range: 0~31
•
Default Value: 4
•
Description: This parameter indicates the number of MRs allowed to be lost in succession. When this threshold is not reached, the lost MR is estimated via the linear interpolation basing on the first and the last MRs received. When this threshold is reached, all previous MRs are discarded, and calculations are made again when new MRs are received.
•
Remarks: MRs fail to be decoded correctly when the signal strength in the serving cell is poor. When this threshold is reached, all previous MRs are discarded and handover may fail. Thus, it is advised to assign this parameter with a greater value to enable emergency handover.
[Filter Length for TCH Level] •
Value Range: 1~31
•
Default Value: 4
•
Description: This parameter indicates the number of MRs used for averaging the TCH signal strength. This parameter helps to avoid sharp drop of signal levels caused by Raileigh Fading and to ensure correct handover decisions.
•
Remarks: When this parameter is too large, the impact of sudden changes is reduced, and the response is delayed, thus affecting the network performance.
2
[Filter Length for TCH Qual] •
Value Range: 1~31
•
Default Value: 4
•
Description: This parameter indicates the number of MRs used for averaging the TCH signal quality.
[Filter Length for SDCCH Level] •
Value Range: 1~31
•
Default Value: 2
•
Description: This parameter indicates the number of MRs used for averaging the SDCCH signal strength. It is recommended that you assign this parameter with a lower value because the SDCCH occupation time is shorter than the TCH occupation time.
[Filter Length for SDCCH Qual] •
Value Range: 1~31
•
Default Value: 2
•
Description: This parameter indicates the number of MRs used for averaging the SDCCH signal quality. It is recommended that you assign this parameter with a lower value because the SDCCH occupation time is shorter than the TCH occupation time.
[Filter Length for Ncell RX_LEV] •
Value Range: 1~31
•
Default Value: 4
•
Description: This parameter indicates the number of MRs used for averaging the signal strength in neighboring cells. This parameter helps to avoid sharp drop of signal levels and to ensure correct handover decisions.
•
Remarks: When this parameter is too large, the impact of sudden changes is reduced, and the response is delayed, thus affecting the network performance.
3
[Filter Length for TA] •
Value Range: 1~31
•
Default Value: 4
•
Description: This parameter indicates the number of MRs used for TA averaging.
“handover failure penalty time” When MS fails to handover to a target cell, a penalty will be given on the signal level of this target cell during a so called “handover failure penalty time” period. That is, when ranking the neighbor cells in the cell list, the corresponding neighbor cell with a failure record within the penalty time will be penalized by cutting certain value on the reported signal level. [Penalty Level after HO Fail] •
Value Range: 0~63
•
Unit: dB
•
Default Value: 30
•
Description: This parameter indicates the penalty level given to a target cell. A penalty level is given to a target cell to avoid further attempts when a handover fails due to any of the following reasons: Cell congestion A message indicating internal handover refusal is received. A message indicating Um interface handover failure is received during out-going BSC handover. A message indicating Um interface handover failure is received during internal handover.
•
Remarks: This parameter is valid only before the penalty time of handover failure expires.
4
[RscPenaltyTimer] • • • •
Value Range: 0~255 Unit: Seconds Default Value: 5 Description: This parameter indicates the length of the penalty timer for handover failure between adjacent cells due to cell congestion. [UmPenaltyTimer] • • • •
Value Range: 0~255 Unit: Seconds Default Value: 10 Description: This parameter indicates the length of the penalty timer for handover failure between adjacent cells due to failed air interface connection. [CfgPenaltyTimer] • Value Range: 0~255 • Unit: Seconds • Default Value: 255 Description: This parameter indicates the length of the penalty timer for handover failure between adjacent cells due to incorrect data configuration. Penalty for Emergency Handover In case of BQ emergency handover, the original serving cell will be penalized (called signal level penalty by BQ HO ), during BQ HO penalty time, to avoid MS to be handed back to the original serving cell again within certain time. It is the same for TA handover, i.e. the original serving cell is penalized (signal level penalty by TA HO ) during TA HO penalty time. [Penalty Level after BQ HO] • Value Range: 0~63 • Unit: dB • Default Value: 63 • Description: This parameter indicates the penalty level given to the original serving cell where emergency handover is performed due to bad quality. After emergency handover is performed due to bad quality, the receive level of the original serving cell is decreased by the penalty level. Thus, other cells are given higher priority and handover to the original serving cell is not allowed. • Remarks: This parameter is valid only before the penalty time of handover due to bad quality expires. [Penalty Time after BQ HO (s)] • Value Range: 0~255 • Unit: Seconds • Default Value: 15 • Description: This parameter indicates the penalty time given to the original serving cell where emergency handover is performed due to bad quality. During the penalty time, the receive level of the original serving cell is decreased by the penalty level. Thus, other cells are given higher priority and handover to the original serving cell is not allowed.
[Penalty Level after TA HO] •
Value Range: 0~63
5
•
Unit: dB
•
Default Value: 63
•
Description: This parameter indicates the penalty level given to the original serving cell where emergency handover is performed due to TA. After emergency handover is performed due to TA, the receive level of the original serving cell is decreased by the penalty level. Thus, other cells are given higher priority and handover to the original serving cell is not allowed. This parameter is valid only before the penalty time of handover due to TA expires.
[Penalty Time after TA HO(s)] •
Value Range: 0~255
•
Unit: Seconds
•
Default Value:30
•
Description: This parameter indicates the penalty time given to the original serving cell where emergency handover is performed due to TA. During the penalty time, the receive level of the original serving cell is decreased by the penalty level. Thus, other cells are given higher priority and handover to the original serving cell is not allowed.
Penalty for MS Fast-moving Handover •
Purpose of such penalty: When MS crosses continuously several micro cells, it handover to the umbrella cell with lower hierarchical priority level, to avoid too frequent handovers which will affect the communication quality between those cells. At the same time, penalty is started to avoid handover back to original cell again. A possible example is that a fast moving car is running on a highway.
[Penalty on MS Fast Moving HO] •
Value Range: 0~63
•
Unit: dB
•
Default Value:30
•
Description: This parameter indicates the penalty given to the level in a neighboring cell when an MS is moving fast. Only the cells in the umbrella layer can give penalty to the cells in other three layers.
•
Remarks: This parameter is valid only before the penalty time of fast moving expires.
[Penalty Time on Fast Moving HO] 6
•
Value Range: 0~255
•
Unit: Seconds
•
Default Value: 40
•
Description: This parameter indicates the period during which penalty is performed on the neighboring cells of the fast moving MS. During this period, penalty on the neighboring cells (on only the other three layers except the umbrella layer) of fast moving MS is valid.
Penalty for Concentric Cell Huawei concentric cell HO failure means the failure of handover from the Underlaid to the Overlaid, or from the Overlaid to the Underlaid. [Penalty Time after UtoO HO Fails(s)] •
Value Range: 10~255 Unit: Seconds Default Value: 40
•
Description: After a UL to OL handover fails, no UL to OL handover request is allowed before the penalty time expires.
[Penalty Time after OtoU HO Fails(s)] •
Value Range: 0~255 Unit: Seconds Default Value: 10
•
Description: After an OL to UL handover fails, no OL to UL handover request is allowed before the penalty time expires.
[MaxRetry Time after UtoO Fail] •
Value Range: 0~8 Default Value: 3
•
Description: This parameter indicates the threshold of UL to OL handover failures. UL to OL handover is not allowed if the number of handover failures reaches this threshold.
•
Remarks: When this parameter is set to 0, not this threshold but the penalty time restricts the permission of handover.
Data Configuration of Penalty for Enhanced Concentric Cell [Penalty Time of UtoO HO(s)] •
Value Range: 0~255
•
Unit: Seconds
•
Default Value: 10 7
Penalty for Intra-cell HO •
Description: This parameter indicates the penalty time for forbidding ping-pong handovers. After an OL to UL handover is performed, UL to OL handover is not allowed before the penalty time expires. If this parameter is set to 0, a UL to OL handover is allowed when required.
•
Remarks: This parameter is valid only when Enhanced Concentric Cell is allowed.
•
Because of the co-channel interference and other interference, the voice quality of a MS on certain frequency may lower than the handover threshold, now, the voice quality can be satisfied if the MS hands over to another frequency in the same cell. On the other side, the signaling flow of this kind of intra-cell handover is less and handover successful ratio is higher.
•
But under some specific condition (for example: several frequency are all interfered in a cell), then continual intra-cell handover may occurred. So it is necessary to control the frequency of intra-cell handover.
[Max Consecutive HO Times] •
Value Range:1~20
•
Default Value: 3
•
Description: This parameter indicates the maximum number of consecutive intra-cell handovers allowed. If the interval of two continuous intra-cell handovers is less than a specified threshold, the two handovers are regarded as consecutive handovers.Intra-cell handover is forbidden if the number of consecutive handovers exceeds this threshold.
[Forbidden Time after Max Times] •
Value Range: 1~200
•
Unit: Seconds
•
Default Value: 20
•
Description: This parameter indicates the timer that starts when the threshold of maximum consecutive intra-cell handovers is reached. Intra-cell handovers is allowed only when the timer expires.
[Interval for Consecutive HO Jud.] •
Value Range: 1~200
•
Unit: Seconds 8
•
Default Value: 6
•
Description: This parameter indicates the period for judging whether two continuous intra-cell handovers are consecutive.
[Penalty Time after AMR TCHF-H HO Fails(s)] •
Value Range: 0~255
•
Unit: Seconds
•
Default Value: 30
•
Description: This parameter indicates the penalty time for AMR full rate to half rate (FRto-HR) handovers. Before the timer expires, no AMR FR-to-HR handover request is allowed if the previous full-half handover fails due to channel unavailability or channel mismatch.
Ranking processing of cells are major parts of the HO judgment. The ranking result is used for target cell selection of handover. The ranking processing includes: Basic ranking M rule K rule Network feature adjustment 16 bits ranking M rule will remove the cells from the candidate cell list according to the following conditions: Under the condition of non-direct retry, if “Inter-BSC SDCCH HO Allowed” is No, and this is an external neighboring cell, and the current channel is SDCCH If the cell is overload RX_LEV_DL < Min DL Power on HO Candidate Cell + Min Access Level Offset RX_LEV_UL < Min UL Power on HO Candidate Cell + Min Access Level Offset For service cell: Min Access Level Offset is 0. [Inter-BSC SDCCH HO Allowed]
9
•
Value Range: Yes, No
•
Default Value: No
•
Description: This parameter indicates whether an inter-BSC SDCCH handover is allowed. An inter-BSC SDCCH handover is triggered when an MS succeeds in requesting SDCCH but fails to request TCH in a BSC.
[Min UP Power on HO Candidate Cell] •
Value Range: 0~63 (-110 dBm to -47 dBm) Default Value: 10
•
Description: The M criterion supports the minimum value constraint of uplink received level of the neighbor cell. Expected uplink level of the neighbor cell >= (the minimum uplink power of the candidate cell for handover + the minimum access level offset)The M criterion is satisfied only when the expected downlink level of the neighbor cell >= (the minimum downlink power of the candidate cell for handover + the minimum access level offset).0-63 with 0 indicating -110 dBm and 63 indicating -47 dBm.
[Min DL Level on Candidate Cell] •
Value Range: 0~63 (-110 dBm to -47 dBm) Default Value: 15
•
Description: This parameter indicates the lower threshold of downlink receive level when a cell becomes a candidate cell.
•
Remarks: This parameter must be appropriately specified. If it is too high, some desired cells may be excluded from the candidate cells. If it is too low, an unwanted cell may become the target cell, thus leading to handover failures or call drops. A cell can become a candidate cell only when the receive level minus this parameter is greater than the minimum access level offset.
[Min Access Level Offset] •
Value Range: 0~63 Unit: dB Default Value: 0
•
Description: This offset is based on the Min DL level on Candidate Cell. For different adjacent cells, different offsets can be defined. Only when the receiving level of an adjacent cell > Min DL Level on Candidate Cell + Min Access Level Offset, then this cell become a candidate cell.
After the M rule , all the candidate cells are ranked in descending order according to the K value Service cell: K = 0
10
Neighboring cell: K = RX_LEV (n) – RX_LEV (s) Service cell: always 0 Neighboring cell: when RX_LEV_DL (n) >= RX_LEV_DL (s) + Inter-cell HO hysteresis, bit 4th is set to 0. Otherwise, set to 1 This parameter indicates the handover hysteresis between adjacent cells of the same layer. The purpose of setting this parameter is to reduce the "Ping-Pong" handovers. The value of this parameter is invalid if cells are not on the same layer. 4 dB populous urban areas and 8 dB for suburbs.
[Inter-cell HO Hysteresis](it is working in overlap area b/w. neighboring cells) •
Value Range: 0~63
•
Unit: dB
•
Default Value: 5
•
Description: This parameter indicates the handover hysteresis between adjacent cells of the same layer. The purpose of setting this parameter is to reduce the "Ping-Pong" handovers. The value of this parameter is invalid if cells are not on the same layer. 4 dB for populous urban areas and 8 dB for suburbs.
•
Each layer has sub 16 priorities
•
Total 4 layers *16 levels for each layer = 64
•
So 2*(power)6 = 64
•
So 6bits are needed to set all levels
•
1st layer level
•
000000
[Load
HO Allowed] • Value Range: Yes, No • Default Value: No • Description: This parameter indicates whether a traffic load-sharing handover is allowed. Load-sharing helps to reduce cell congestion, improve the success rate of assignment, and balance the traffic load among cells. Load-sharing functions only within the same BSC or in cells of the same layer. It applies to only TCH. If load handover is frequently required, TRX configuration and network planning should be properly adjusted. • Remarks: In areas with tight frequency reuse, extra interference may occur if Load HO Allowed is set to Yes.
11
[System Flux Threshold for Load HO] • Value Range: 0~11 • Default Value: 10 • Description: System Flux Threshold for Load HO is obtained based on message load, CPU load, and so on. The system flow level is the current flow control level of the system. 0~11:It is the system flux control level when the alarm module send out alarms information. Level 11 is the highest and level 0 is the lowest. A load handover is allowed only when the system flow is lower than this threshold. Otherwise, unexpected situations may occur. Therefore, this parameter must be set properly. Flow control threshold for the CPU to start to discard the channel access messages and paging messages: 80% Flow control threshold for the CPU to discard all the channel access messages and paging messages: 100% CPU usage smaller than 80% corresponds to level 0. CPU usage equal to or greater than CPU flow control threshold 80% corresponds to level 2. An increase of 5% means an increase of 2 levels. Level 10 is the highest. The level value can be 0, 2, 4, 6, 8, and 10.
[Load HO Threshold] Value Range: 0~100(%) Default Value: 85 Description: When the load handover is switched on, it is recommended that the Load HO Threshold is set to 85.The cell load refers to TCH usage. When the cell load exceeds the value of Load HO Threshold, the BSC starts the load handover. That is, the BSC starts the load handover after the TCH in the cell are proportionally occupied. Remarks: Even if the Load HO Allowed is set to Yes, the Load HO Threshold and Load Req. on Candidate Cell affect the queuing of the candidate cell handover. Therefore, when the cell is overloaded, the handovers such as PBGT cannot be performed if this parameter is not properly set. [Load Req. on Candidate Cell] Value Range: 0~100(%) Default Value: 75 Description: If the cell load is lower than the value of this parameter, the cell accepts users that are handed over to the cell due to their cell load. If the cell load is not lower than the value of this parameter, the cell refuses the users. Remarks: The same as that of Load HO Threshold 12
12th bit: if neighbor cell is co-BSC with the serving cell, 12th bit is set to 0. Otherwise, set to 1 13th bit: if neighbor cell is co-MSC with the serving cell, 13th bit is set to 0. Otherwise, set to 1 Service cell: is always set to 0 These two bits will be turned off when Co-BSC/MSC Adj. is set to NO [Co-BSC/MSC Adj] •
Value Range: Yes, No
•
Default Value: Yes
•
Description: This parameter indicates whether the sequence of candidate cells is adjusted. After the sequence is adjusted, the handover within the same BSC/MSC takes priority.
•
The 14th bit: Layer HO threshold adjustment bit
•
Serving cell: RX_LEV_DL >= Inter-layer HO Threshold – Inter-layer HO Hysteresis, bit 14th is set to 0
•
Neighboring cell: RX_LEV_DL >= Inter-layer HO Threshold + Inter-layer HO Hysteresis, bit 14th is set to 0.
•
If the above criterion is not met, then bit 14th is set to 1. At the same time, bit 5th- 13th bits are turned off.
•
The 15th/16th bits are reserved
[Inter-layer HO Threshold] •
Value Range: 0~63(-110 dBm to -47 dBm)
•
Default Value: 25
•
Description: In BSC handover algorithm, the M criterion is used to rank the handover candidate cells. The M criterion includes 16 bits. This parameter is one bit of the 16 bits and it affects the rank of a candidate cell. When the downlink level of a cell is lower than this threshold, the cell takes low priority as far as comprehensive sequence is concerned.
•
Remarks: Make sure that the receive level of the destination cell is higher than this threshold in inter-layer handover or load handover. Otherwise, the MS may be handed from a cell with heavy load and high level (high priority cell) to a cell with light load and low level (low priority cell), thus leading to call drops.
13
[Inter-layer HO Hysteresis] •
Value Range: 0~63
•
Unit: dB
•
Default Value: 3
•
Description: This parameter indicates the hysteresis of an inter-layer or inter-priority handover. It is used to avoid inter-layer ping-pong handovers. Actual Inter-layer HO Threshold of a serving cell = Inter-layer HO Threshold C Inter-layer HO hysteresis Actual Inter-layer HO Threshold of a neighboring cell = Inter-layer HO Threshold + Inter-layer HO hysteresis
When the quality of Um interface become worse and worse, it is for the worse uplink quality that MS can not deliver downlink MR, while the downlink quality is not bad enough for MS to receive the downlink message normally. Under this kind of urgency condition, in order to save this call, the network send handover command to MS. Attention: After MR. Preprocessing, the No DL MR handover is triggered if trigger condition is satisfied. Triggering condition No DL information in current MR Stored UL Rx_Qual Value Number >= Rx_Qual Filter Length UL Rx_Qual >= No DL MR HO UL Rx_Qual Threshold Number of Lost DL MR < Cons. No DL MR HO Allowed Limit Object cell selection Prefer neighboring cell If choose the service cell, it cannot in the penalty time for intra-cell handover. [No Dl Mr. HO Allowed] •
Value Range: Yes, No
•
Default Value: No
•
Description: This parameter is used to control the handover algorithm without downlink measurement report. If this parameter is set to 0, the no handover algorithm without 14
downlink measurement report is disabled. Therefore, handover decision without downlink measurement report is not allowed in this cell. If this parameter is set to 1, the no downlink measurement report handover algorithm is enabled. Therefore, handover decision without downlink measurement report is allowed in this cell. [No Dl Mr. Ul Qual HO Limit] •
Value Range: 0~70 (mapping to RQ (0~7)×10)
•
Default Value: 60
•
Description: This parameter indicates the uplink receive quality threshold of triggering an emergency handover when no measurement result on downlink channels is contained in the MR. The emergency handover is allowed only when the filtered uplink receive quality crossed this threshold. When an emergency handover is triggered, intercell handover takes priority. Intra-cell handover, however, is triggered if no candidate cell is available and intra-cell handovers are allowed.
[Cons. No Dl Mr. HO Allowed Limit] •
Value Range: 0~64
•
Default Value: 8
•
Description: This parameter indicates the upper threshold of consecutive MRs containing no downlink measurement result for a call. Each call is configured with a global timer, which counts the number of consecutive MRs containing no downlink measurement. When the timer exceeds this threshold, the handover is disabled and the timer is reset.
Because a MS is far away from its serving BTS, the practice TA value is more than TA threshold configured in data configuration, TA handover is triggered. Triggering condition The actual TA >= TA Threshold Object cell selection The cell must be of the highest priority in the candidate cell sequence and meet the following restrictions. Restriction The service cell cannot be the object cell.
15
HO is not allowed when TA Threshold of the neighboring cell with the same BTS is equal or smaller than that of the service cell.
[TA HO Allowed] •
Value Range: Yes, No
•
Default Value: Yes
•
Description: The parameter indicates whether a Timing Advance (TA) handover is allowed. A TA handover is triggered when the TA is higher than the triggering threshold. TA is calculated based on the distance between the MS and the BTS. The longer the distance is, the greater the TA is.
[TA Threshold] •
Value Range: 0~255
•
Unit: Bit period (A bit period corresponds to 0.55 km.)
•
Default Value: 255
•
Description: This parameter indicates the TA threshold of triggering emergency handover. Emergency handover is triggered when TA is equal to or greater than this threshold.
Interference HO For a MS or a BTS, when the receiving quality is lower than the interference quality threshold and receiving level is higher than the interference level threshold, it is considered that interference exists in serving cell, so interference handover is triggered. Triggering condition
UL/DL receiving quality>=A None AMR FR A = RXQUALn, 1<=n<=12 AMR FR A = RXQUAL1, n=1; A = RXQUALn + RXLEVoff, 2<=n<=12
Object cell selection
The cells must be of the highest priority in the candidate cell sequence and meet the following restrictions.
The service cell that is not in the penalty time for intra-cell handover. The neighboring cell with the receiving level higher than the inter layer HO Thrsh + Hysteresis.
Restriction
For none AMR FR, if one of the following conditions is met, the system will judge that interference occur: 1. Rx_lev <= 30, and Rx_qual > RXQUAL 1
16
2. Rx_lev = 31, and Rx_qual > RXQUAL 2 3. Rx_lev is within [32,35], and Rx_qual > RXQUAL3 4. Rx_lev is within [36,38], and Rx_qual >RXQUAL 4 5. Rx_lev is within [39,41], and Rx_qual > RXQUAL5 6. Rx_lev is within [42,45], and Rx_qual > RXQUAL6 7. Rx_lev is within [46,48], and Rx_qual > RXQUAL7 8. Rx_lev is within [49,52], and Rx_qual > RXQUAL8 9. Rx_lev is within [53,55], and Rx_qual > RXQUAL9 10. Rx_lev is within [56,58], and Rx_qual > RXQUAL10 11. Rx_lev is within [59,62], and Rx_qual > RXQUAL11 12. Rx_lev >= 63, and Rx_qual > RXQUAL12 [Interference HO Allowed] • • •
Value Range: Yes, No Default Value: Yes Description: The parameter indicates whether an interference handover is allowed. An interference handover is triggered when the receive level is higher than the receive threshold, but the transmission quality is lower than the handover triggering threshold. • Remarks: Both downlink and uplink interference is judged, and inter-cell handover takes priority. If no target cell is available, intra-cell interference handover can be implemented in the serving cell if intra-cell handovers are allowed. [RXQUAL1] ~ [RXQUAL12] • •
Value Range: 0~70 Description: Quality threshold 1~12 for the interference handover of nonCAMR FR voice services. The value corresponds to (quality level 0~7) x 10.See the next slide [RXLEVOff] • Value Range: 0~70 • Default Value: 5 Description: The quality level offset of the interface handover of the AMR FR service relative to nonAMR services or the AMR HR service (x 10). [Rx_Level_Drop HO Allowed] • Value Range: Yes, No Default Value: No • Description: The parameter indicates whether the emergency handover algorithm is allowed. The emergency handover algorithm is used to prevent call drops when the receive level of the MS drops rapidly. Generally this algorithm is not enabled until the conditions are met. To enable this algorithm, original MR is required for the BSC. [Filter Parameter A1~A8] • Value Range: 0~20 Default Value: 10 • Description: Filter Parameter A1~A8 and Filter Parameter B work together to decide whether the rapid drop of the receive level must be reflected in one or multiple MRs. The conditions to trigger a rapid level dropping handover are as follows; In the algorithm above, X1, X2, X3, X4, X5, X6, X7, and X8 indicate the uplink receive levels of the last eight MRs in the queue. Filter Parameter A1~A8 must meet the following conditions: A1+A2+A3+A4+A5+A6+A7+A8=80. For example, if you want to reflect the rapid drop of the cell level in a MR, you can set A3-A8 to greater than 10, A1 to 0, and A2 to 20. [Filter Parameter B] • •
Value Range: 0~200 Default Value: 0 Description: This is one of the parameters that determine whether a handover is required due to fast dropping levels.This parameter indicates the drop trend of the receive level within a period. The greater the parameter B is, a more rapid level drop is required for triggering a rapid level dropping handover.See Filter Parameter A1-A8. [Edge HO UL RX_LEV Threshold] • Value Range: 0~63 (-110 dBm to -47 dBm) Default Value: 10
17
•
Description: The parameter indicates the uplink receive level threshold of an edge handover. An edge handover will be triggered if the uplink receive level is constantly lower than "Edge HO UL RX_LEV Thrsh." for a period longer than Edge HO Valid Time(s) within Edge HO Watch Time(s). If PBGT handover is enabled, the corresponding edge handover threshold can be lowered. If PBGT handover is disabled, this parameter must be properly specified to avoid overlapping coverage and channel interference. This parameter should be adjusted based on the performance statistics and actual networks to achieve uplink-downlink balance. Remarks: Edge handover uplink/downlink receive level threshold < Uplink/downlink signal strength lower limit of HUAWEI II power control
Edge HO DL RX_LEV Threshold Parameter Name Description
Edge HO DL RX_LEV Threshold If the DL receive level remains lower than the Edge HO DL RX_LEV Threshold for a period, the edge handover is triggered. If the PBGT handover is enabled, the relevant edge handover threshold can be decreased. If the PBGT handover is not enabled and the edge handover threshold is not properly set, cross coverage, co-channel interference, and adjacent channel interference are likely to occur. The Edge HO DL RX_LEV Threshold should be adjusted based on the handover performance statistics and the actual network performance to achieve the UL/DL balance. The value of this parameter ranges from 0 to 63 (corresponding to 110 dBm to -47 dBm).
GUI Value Range [0,63] Default Value
20-90
Unit
Levels
Step
-
Configuration Policy
This parameter should be adjusted as required. If the Edge HO DL RX_LEV Threshold is set to a too small value, call drop may easily occur. If the PBGT handover is enabled, the relevant edge handover threshold can be decreased.
Recommended Value
20
Parameter Relationship
None
BSC Feature
Handover
Parameter Class Caution
Parameters About Radio Resources 1. Edge HO UL RX_LEV Threshold/Edge HO DL RX_LEV Threshold < UL RX_LEV Lower Threshold/DL RX_LEV Lower 18
Threshold in Huawei II power control algorithm. 2. Edge HO UL RX_LEV Threshold/Edge HO DL RX_LEV Threshold < UL RX_LEV Lower Threshold/DL RX_LEV Lower Threshold expected in Huawei I power control algorithm.
When the receiving level of a MS or a BTS is lower than the quality threshold, bad quality handover will be triggered. Triggering condition UL receiving quality >= UL Qual. Threshold OR DL receiving quality >= DL Qual. Threshold For AMR call, the quality threshold is DL/UL Qual. Limit AMR FR/HR Object cell selection The cells must be of the highest priority in the candidate cell sequence and meet the following restrictions. Restriction Prefer neighboring cell. If the number of neighboring cell is more than one, it is required that RX_LEV_DL (n) > RX_LEV_DL (s) + Inter-cell HO hysteresis - BQ HO Zone If there is no neighboring cell, handover can occur to the service cell, and the channel at different frequency band, different MA, different TRX or different channel (from left to right) is preference. [BQ HO Allowed] •
Value Range: Yes, No
•
Default Value: Yes
•
Description: The parameter indicates whether a Bad Quality (BQ) handover is allowed. BQ handover is triggered when Bit Error Ratio (BER) over uplink/downlink channels is higher than the triggering threshold. If BER rises, or signal strength drops, suspect that the signal power is low or channel interference increases. 19
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Remarks: Inter-cell BQ handover is preferentially performed. If no target cell is available, intra-cell BQ handover can be implemented in the serving cell if intracell handovers are allowed.
[DL Qual. Threshold] •
Value Range: 0~70 (RQ (0~7) 10)
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Default Value: 60
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Description: This parameter indicates the downlink receive quality threshold of triggering an emergency handover. When the receive quality of the downlink is greater than DL Qual Threshold, an emergency handover is triggered. When frequency hopping or DTX of the cell is enabled, it is recommended that you set this parameter to 70. When an emergency handover is triggered, inter-cell handover takes priority. An intra-cell handover, however, is triggered if no candidate cell is available and intra-cell handovers are allowed.
[UL Qual. Threshold] •
Value Range: 0~70 (RQ (0~7)10)
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Default Value: 60
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Description: This parameter indicates the uplink receive quality threshold of triggering an emergency handover. When the receive quality of the uplink is greater than UL Qual Threshold, an emergency handover is triggered due to bad quality. When frequency hopping or DTX of the cell is enabled, it is recommended that you set this parameter to 70.When an emergency handover is triggered, inter-cell handover takes priority. An intra-cell handover, however, is triggered if no candidate cell is available and intra-cell handovers are allowed.
[DL/UL QuaLimitAMRFR] •
Value Range: 0~70
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Default Value: 65
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Description: This parameter indicates the urgent switchover downlink/uplink quality control for the AMR FR service. The values of this parameter match quality levels 0-7 multiplying 10. The urgent switchover is triggered only when the downlink/uplink receiving quality of the MS is greater than the switchover threshold, that is, the receiving quality is poor. 20
[DL/UL QuaLimitAMRHR] •
Value Range: 0~70
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Default Value: 60
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Description: This parameter indicates the urgent switchover downlink quality control for the AMR HR service. The values of this parameter match quality levels 0-7 multiplying 10. The urgent switchover is triggered only when the downlink receiving quality of the MS is greater than the switchover threshold, that is, the receiving quality is poor.
[BQ HO Margin] •
Value Range: 0~127 (-64 dB to +63 dB)
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Default Value: 69
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Description: A Margin in BQ handover algorithm used to judge whether to perform BQ handover. When BQ Handover Allowed is set to Yes and Inter-cell HO Hysteresis > "Inter-cell HO Hysteresis-BQ HO Margin", the Inter-cell HO Hysteresis will act instead of the BQ HO Margin. When "Inter-cell HO HysteresisBQ HO Margin" is assigned with a value smaller than 64, MS can hand over to a lower level neighboring cell. 69 for popular urban areas, 72 for suburbs.
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Remarks: If the data is updated from M900/M1800 BSC to HUAWEI BSC6000,the default value of this parameter is 5.Then it's necessary to modify the value of this parameter to 69,otherwise the BQ HO algorithm will be invalid.
BQ HO Margin Parameter Name Description
BQ HO Margin The handover to an adjacent cell occurs when the difference between the downlink level of the adjacent cell after filtering and the downlink level of the serving cell (after power control compensation) > the Inter-cell HO hysteresis - the BQ HO Margin + 64. The handover to the adjacent cell whose level is lower than that of the serving cell (after power control compensation) can be performed, when the Inter-cell HO hysteresis is less than the BQ
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HO Margin. It is recommended that you set this parameter to approximately 69 in densely-populated urban areas and 72 in suburban areas. The level values 0 to 127 map to -64 dB to 63 dB. GUI Value Range [0,127] Default Value
69
Unit
dB
Step
-
Configuration Policy
The difference between Inter-cell HO Hysteresis and BQ HO Margin is used to filter the candidate cells. If the BQ HO Margin is set to a higher value, the threshold for the candidate cells is lowered, thus an adjacent cell is more likely to become a target cell for handover.
Recommended Value
69+5
Parameter Relationship
Inter-cell HO Hysteresis
BSC Feature
Handover
Parameter Class Caution
Parameters About Radio Resources By default, the value of this parameter is 5 when the data of M900/M1800 BSC is upgraded to the BSC6000. Modify this value to 69; otherwise, the handover algorithm supported by this parameter is invalid.
TCH assignment (SDCCH channel in underlaid) If Assignment Optimization of UL Subcell Allowed or not is set to NO, assign TCH in underlaid as the normal assignment procedure If Assignment Optimization of UL Subcell Allowed or not is set to YES, assign TCH in overlaid when the following conditions are met Cell load of underlaid > UL Subcell General Overload Threshold RX_LEV_OL >= Incoming OL Subcell HO level Threshold [UL Subcell Lower Load Threshold(%)] 22
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Value Range: 0~100
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Unit: %
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Default Value: 50
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Description: If the underlaid subcell channel occupancy ratio is smaller than the value of this parameter, some calls of the overlaid subcell is handed over to the underlaid subcell. Moreover, the MS that requests for the overlaid subcell channel is preferably assigned to the underlaid subcell channel.
[Assignment Optimization of OL Subcell Allowered Or Not] •
Value Range: Yes, No
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Default Value: No
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Description: This parameter indicates whether the channel request in the overlaid subcell is preferably assigned between overlaid subcell and underlaid subcell according to the Out Cell Low Load Thred.
RX_LEV_UL – RX_LEV (n) > Distance Between Boundaries of UL and OL Subcells－Distance Hysteresis Between Boundaries of UL and OL Subcell(dB) RX_LEV (n): RX_LEV of the strongest neighboring cell which has the same frequency band and layer with underlaid subcell, but locates in a different BTS. If there is no such a cell, this value is -110dBm There are three kinds of handover for enhanced dual band network: •
UL to OL for high load in UL
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OL to UL for moving
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OL to UL for low load in UL
Enhanced Dual Band HO(UO ) The order of handover is from the MS who is near the OL to the MS who is far away from OL. 23
Triggering condition for TCH Load HO from underlaid to overlaid Load HO of UL Subcell to OL Subcell Enable is YES Cell load of underlaid > UL Subcell General Overload Threshold RX_LEV_OL >= Incoming OL Subcell HO level Threshold RX_LEV_UL – RX_LEV (n) > Distance Between Boundaries of UL and OL Subcells(dB) Satisfying P/N rule [UL Subcell General OverLoad Threshold(%)] •
Value Range: 0~100
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Unit: %
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Default Value: 80
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Description: If the ratio of underlaid subcell channel occupancy is greater than the value of this parameter, some calls in the underlaid subcell are handed over to the overlaid subcell. Moreover, calls originated in the underlaid subcell are preferably assigned to the channel in overlaid subcell.
[UL Subcell Serious OverLoad Threshold(%)] •
Value Range: 0~100
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Unit: %
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Default Value: 90
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Description: If the ratio of the underlaid cell channel occupancy is greater than the value of this parameter, the period of handover from underlaid subcell to overlaid subcell is reduced by the value of Out Cell Load HO Modify Step every second based on the value of Out Cell Load Classification HO Period. Thus the handover from underlaid subcell to the overlaid subcell speeds up.
[Load HO From UL Subcell to OL Subcell Allowed] •
Value Range: Yes, No
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Default Value: Yes 24
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Description: When the ratio of underlaid subcell channel occupancy is high, whether some calls in the overlaid subcell are allowed to be handed over to the overlaid subcell.
[Incming OL Subcell HO Level Threshold(dB)] •
Value Range: 0~63
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Unit: dB
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Default Value: 30
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Description: This parameter indicates the lowest threshold of overlaid subcell level of the handover from underlaid subcell to overlaid subcell. When the MS receive level is higher than the value of this parameter, the BSC allows the handover of overlaid subcell cell.
[UL Subcell Load Hierarchical HO Period(s)] •
Value Range: 1~255 Unit: Seconds Default Value: 5
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Description: This parameter indicates the period of the hierarchical handover from underlaid subcell to overlaid subcell. When the ratio of underlaid subcell cell channel occupancy is greater than the value of En Iuo Out Cell General OverLoad Thred, all the calls in the cell request for handover at the same time. The BSC load is sharply increased. Thus the call may drop because the target cell is congested. Therefore the algorithm of hierarchical handover is applied to hand over the calls in the cell hierarchically to the overlaid subcell.This parameter indicates the time duration of every hierarchical handover.
[Step Length of UL Subcell Load HO(dB)] •
Value Range: 0~63 Unit: dB Default Value: 5
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Description: This parameter indicates the level step of the hierarchical handover from underlaid subcell to overlaid subcell.
[Modified Step Lenghth of UL Load HO Period(s)] •
Value Range: 1~255 Unit: Seconds Default Value: 1
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Description: If underlaid subcell load is higher than the value of Out Cell Serious OverLoad Thred, the period of handover from underlaid subcell cell to overlaid
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subcell cell is shortened by the value of Out Cell Serious OverLoad Thred every second based on the value of the Out Cell Load classification HO Period. [Total Number of ] •
Value Range: 1~255 Unit: Seconds Default Value: 5
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Description: P/N criterion: In P measurement reports, N measurement results meet handover requirements. Handover is started. This parameter indicates the P in P/N criterion.
[Satisfy Condition Time] •
Value Range: 1~255 Unit: Seconds Default Value: 4
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Description: P/N criterion: In P measurement reports, N measurement results meet handover requirements. Handover is started. This parameter indicates the N in P/N criterion.
Enhanced Dual Band HO(OU )
Triggering condition for TCH Moving HO from overlaid to underlaid
RX_LEV_OL < Outgoing OL Subcell HO level Threshold OR RX_LEV_UL – RX_LEV (n) < Distance Between Boundaries of UL and OL Subcells(dB) - Distance Hysteresis Between Boundaries of UL and OL Subcells(dB) Satisfying P/N rule
Object cell selection
The cell with highest priority. It could be underlaid subcell or normal neighboring cell
Attention: RX_LEV (n): RX_LEV of the strongest neighboring cell which has the same frequency band and layer with underlaid subcell, but locates in a different BTS. If there is no such a cell, this value is -110dBm
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