2G Connected Mode (Handover Control) CS RACH Min. Access Level Layer of The Cell Edge HO UL RX_LEV Threshold Edge HO DL RX_LEV Threshold Inter-layer HO Threshold Inter-layer HO Hysteresis Min UL Level on Candidate Cell Min DL Level on Candidate Cell Min Power Level For Directed Retry Inter-cell HO Hysteresis Min Access Level Offset PBGT HO Threshold BQ HO Margin Adjacent Cell Inter-layer HO Hysteresis
Macro Layer
GSM900
GSM900
GSM900 Edge HO UL RX_LEV Threshold Edge HO DL RX_LEV Threshold TA Handover Bad Quality HO Load Handover
Filtered downlink RX level of the target cell ≥ Inter-layer HO Threshold + Adjacent Cell Interlayer HO Hysteresis - 64 DCS1800
CS RACH Min. Access Level Layer of The Cell Edge HO UL RX_LEV Threshold Edge HO DL RX_LEV Threshold Inter-layer HO Threshold Inter-layer HO Hysteresis Min UL Level on Candidate Cell Min DL Level on Candidate Cell Min Power Level For Directed Retry Inter-cell HO Hysteresis Min Access Level Offset PBGT HO Threshold BQ HO Margin Adjacent Cell Inter-layer HO Hysteresis
-106 2 12 15 25 2 10 15 25 68 0 68 69 67
DCS1800
Micro Layer
DCS1800
-106 3 12 15 25 2 10 15 25 68 0 68 69 67
2G&3G Cell Selection & Reselection
GSM900
DCS1800
WCDMA
DCS1800 Minimum Access RXLEV MS_TXPWR_MAX_CCH CBQ (Cell Bar Qualify ) CBA (Cell Bar Access ) CRO (Cell Reselection Offset) TO (Temporary Offset) PT (Penalty Time) CRH (Cell Reselection Hysteresis) Qsearch I Qsearch C Initial FDD Q Offset FDD RSCP Min. FDD REP QUANT FDD Multirate Reporting FDD Qmin FDD Qmin Offset Qsearch P Qsearch C
GSM900 -102 30 (0) No No 8 0 0 6 db. 7 Use_Qsearch_I 0 6 EcN0 2 5 0 7 15
Minimum Access RXLEV MS_TXPWR_MAX_CCH CBQ (Cell Bar Qualify ) CBA (Cell Bar Access ) CRO (Cell Reselection Offset) TO (Temporary Offset) PT (Penalty Time) CRH (Cell Reselection Hysteresis) Qsearch I Qsearch C Initial FDD Q Offset FDD RSCP Min. FDD REP QUANT FDD Multirate Reporting FDD Qmin FDD Qmin Offset Qsearch P Qsearch C
WCDMA -102 33 (5) No No 0 0 0 6 db. 7 Use_Qsearch_I 0 6 EcN0 2 5 0 7 15
Cell Sel-reselection quality measure CPICH_ECNO Hysteresis 1 for idle mode 2 Hysteresis 1 for connect mode 2 Hysteresis 2 for idle mode 1 Hysteresis 2 for connect mode 1 Reselection delay time 1 Min quality level -18 Min Rx level -58 Min Rx level Extend Support FALSE Delta Min Rx level Max allowed UE UL TX power 24 Intra-freq cell reselection threshold for idle mode 5 Inter-freq cell reselection threshold for idle mode 4 Intra-freq cell reselection threshold for connect mode 5 Inter-freq cell reselection threshold for connect mode 4 Inter-RAT cell reselection threshold 2 Absolute priority level of the serving cell 4 RSCP threshold for low-prio-freq measurement initiation 2 Ec/No threshold for low-prio-freq measurement initiation 2 RSCP threshold for low-prio-freq reselection 1
Inter-RAT & Inter-Frequency Handover
Inter-freq CS Measure Start Ec/No THD Inter-freq CS Measure Stop Ec/No THD Inter-freq R99 PS Measure Start Ec/No THD Inter-freq R99 PS Measure Stop Ec/No THD Inter-freq H Measure Start Ec/No THD Inter-freq H Measure Stop Ec/No THD Inter-freq CS Measure Start RSCP THD Inter-freq CS Measure Stop RSCP THD Inter-freq R99 PS Measure Start RSCP THD Inter-freq R99 PS Measure Stop RSCP THD Inter-freq H Measure Start RSCP THD Inter-freq H Measure Stop RSCP THD Inter-freq CS Target Frequency Trigger Ec/No THD Inter-freq R99 PS Target Frequency Trigger Ec/No THD Inter-freq HSPA Target Frequency Trigger Ec/No THD Inter-freq CS Target Freqency Trigger RSCP THD Inter-freq R99 PS Target Frequency Trigger RSCP THD Inter-freq HSPA Target Freqency Trigger RSCP THD Inter-freq CS Used frequency trigger Ec/No THD Inter-freq R99 PS Used frequency trigger Ec/No THD Inter-freq H Used frequency trigger Ec/No THD Inter-freq CS Used frequency trigger RSCP THD Inter-freq R99 PS Used frequency trigger RSCP THD Inter-freq H Used frequency trigger RSCP THD Inter-freq Handover Min Access Ec/No THD Inter-freq Handover Min Access RSCP THD
-14 -12 -14 -12 -14 -12 -95 -92 -95 -92 -95 -92 -12 -12 -12 -92 -92 -92 -12 -12 -12 -92 -92 -92 -16 -115
GSM
WCDMA F1
WCDMA F2
Inter-RAT CS Measure Start Ec/No THD Inter-RAT CS Measure Stop Ec/No THD Inter-RAT R99 PS Measure Start Ec/No THD Inter-RAT R99 PS Measure Stop Ec/No THD Inter-RAT HSPA Measure Start Ec/No THD Inter-RAT HSPA Measure Stop Ec/No THD Inter-RAT CS Measure Start RSCP THD Inter-RAT CS Measure Stop RSCP THD Inter-RAT R99 PS Measure Start RSCP THD Inter-RAT R99 PS Measure Stop RSCP THD Inter-RAT HSPA Measure Start RSCP THD Inter-RAT HSPA Measure Stop RSCP THD
-14 -11 -15 -13 -15 -13 -100 -97 -110 -107 -110 -107
CS RACH Min. Access Level Meaning: This parameter specifies the level threshold for the random access of the MS. If the receive level of the RACH burst in the CS domain is smaller than the value of CS RACH Min.Access Level, the BTS regards this access as an invalid one and no decoding is performed. If the receive level of the RACH burst is greater than the value of CS RACH Min. Access Level, the BTS considers that an access request exists on this timeslot, and determines together with the value of Random Access Error Threshold whether the RACH access is valid. GUI Value Range: -121~-104 Unit: dBm Actual Value Range: -121~-104 MML Default Value: None Recommended Value: -109 Parameter Relationship: The value of this parameter must be smaller than RACH Busy Threshold in the SET GCELLCCBASIC command. Service Interrupted After Modification : No (No impact on the UE in idle mode) Impact on Network Performance: If this parameter is set to a greater value, the call drop rate decreases but the traffic volume and paging success rate are affected.
Layer of The Cell A network basically consists of four layers, namely, Umbrella, Macro, Micro, and Pico. Cell priorities influence the sorting of neighboring cells during handovers as well as handover algorithms including PBGT and inter-layer handovers. For example, PBGT handovers can only occur among cells on a same layer and of a same priority level. If you assign different layers and priorities to a 1800-M cell and a 900-M cell, PBGT handovers from the 1800-M cell to the 900-M cell will not occur. This causes slow handovers even when the receive quality is good. There are four network layers, that is, layer 1 to layer 4. A lower layer No. indicates a higher priority. The cell priority is determined by both the network layer and the "PRIOR" parameter.
Edge HO Meaning: Whether to enable the edge handover algorithm. When an MS makes a call at the edge of a cell, the call may drop if the received signal level is too low. To avoid such a call drop, the edge handover algorithm is involved. When the uplink signal level of the serving cell is less than "Edge HO UL RX_LEV Threshold" or the downlink signal level of the serving cell is less than "Edge HO DL RX_LEV Threshold", the edge handover is triggered. GUI Value Range: NO(No), YES(Yes) Actual Value Range: NO, YES Default Value: YES Unit: None
Inter-layer HO Threshold & Interlayer HO Hysteresis Handover threshold during the handovers between cells on different layers or of different priorities. This value is used to suppress inter-layer ping-pong handovers. Inter-layer handover threshold of the serving cell = "Inter-layer HO threshold" - "Inter-layer HO Hysteresis"; Inter-layer handover threshold of a neighboring cell = "Inter-layer HO Threshold" + "Adjacent Cell Inter-layer HO Hysteresis" - 64. Set this parameter properly to ensure that hierarchical handover and load-based handover can function properly. During hierarchical handover and load-based handover, the downlink received level of the target cell must be greater than this threshold.
Min UL/DL Level on Candidate Cell Meaning: Limit on the minimum uplink receive level for a neighboring cell. You are advised to use the default value 0 for this parameter because the receive level for a neighboring cell can be limited by Min DL Level on Candidate Cell. The uplink receive level for a neighboring cell cannot be obtained from a live network. It is estimated using the following formula: Uplink receive level for a neighboring cell = Maximum transmit power of an MS - (BTS transmit power Downlink receive level for a neighboring cell). GUI Value Range: 0~63 Unit: dB Actual Value Range: 0~63 MML Default Value: None Recommended Value: 0 Parameter Relationship: None Service Interrupted After Modification : No (No impact on the UE in idle mode) Impact on Network Performance: You are advised to use the default value 0 for this parameter. Meaning: If the downlink received signal level of a neighbor cell is greater than Min DL Level on Candidate Cell plus Min Access Level Offset, the neighbor cell can be listed in the candidate cell queue for handover. GUI Value Range: 0~63 Unit: dB Actual Value Range: 0~63 MML Default Value: None Recommended Value: 10 Parameter Relationship: None Service Interrupted After Modification : No (No impact on the UE in idle mode) Impact on Network Performance: This parameter limits the number of candidate cells. If this parameter is set to a greater value, some desired cells may be excluded from the candidate cells and call drops may occur. If this parameter is set to a smaller value, an unwanted cell may become the candidate cell, thus leading to handover failures or call drops.
Min Power Level For Directed Retry Meaning: In a direct retry, when the receive level of a neighboring cell is no smaller than this parameter, the neighboring cell can be a candidate cell for the direct retry. The parameter is invalid in handover algorithm II. GUI Value Range: 0~63 Unit: dB Actual Value Range: 0~63 MML Default Value: None Recommended Value: 16 Parameter Relationship: This parameter is valid only when HOCTRLSWITCH is set to HOALGORITHM1. Service Interrupted After Modification : No (No impact on the UE in idle mode) Impact on Network Performance: None
Inter-cell HO Hysteresis Hysteresis value during the handovers between cells, This value is used to suppress ping-pong handovers between cells. The actual value of this parameter is equal to the GUI value minus 64 When "Current HO Control Algorithm" in "SET GCELLHOBASIC" is set to HOALGORITHM1(Handover algorithm I), "Inter-cell HO Hysteresis" should be set within the range of 64-127.When "Current HO Control Algorithm" in "SET GCELLHOBASIC" is set to HOALGORITHM2(Handover algorithm II), "Inter-cell HO Hysteresis" should be set within the range of 0-127.
Min Access Level Offset Minimum receive level offset. MSs can be handed over back to a neighboring cell when both of the following conditions are met: Downlink receive level of the neighboring cell >= Value of "HOCDCMINDWPWR" + Value of this parameter Uplink receive level of the neighboring cell >= Value of "HOCDCMINUPPWR" + Value of this parameter This parameter is based on "HOCDCMINDWPWR" and "HOCDCMINUPPWR". Different offset can be set for different neighboring cells. The following condition must be met for a neighboring cell to be added into the candidate cell queue: Neighboring cell uplink level >= ("HOCDCMINUPPWR" + "MINOFFSET"); Neighboring cell downlink level >= ("HOCDCMINDWPWR" + "MINOFFSET").
PBGT HO Threshold PBGT handovers to a neighboring cell are allowed only when the downlink level difference between the neighboring cell and the serving cell is larger than this parameter. When the value of this parameter is smaller than 64, handovers to a neighboring cell with a lower level than the current serving cell are allowed. The actual value of this parameter is equal to the GUI value minus 64. In densely populated urban areas, the recommended value is 68; in the suburbs, the recommended value is 72
BQ HO Margin Difference between the downlink receive level of the serving cell and that of a neighboring cell during bad quality handovers. This parameter is used to calculate the bad quality handover hysteresis based on the following formula: Bad quality handover hysteresis = Value of "INTERCELLHYST" -Value of this parameter Bad quality handovers to a neighboring cell can be triggered when the following condition is met: (Downlink receive level of the neighboring cell after filtering - Downlink receive level of the serving cell after power control compensation) > (Value of "INTERCELLHYST " - 64) - (Value of this parameter - 64). The actual value of this parameter is equal to the GUI value minus 64 This parameter is used with "INTERCELLHYST" to calculate the bad quality handover hysteresis
Adjacent Cell Inter-layer HO Hysteresis Hysteresis value during the handovers between cells on different layers or of different priorities. This value is used to suppress inter-layer Ping-Pong handovers. The actual value of this parameter is equal to the GUI value minus 64 Inter-layer HO threshold of the serving cell = "Inter-layer HO threshold" - "Inter-layer HO Hysteresis". Interlayer HO threshold of the neighboring cell = "Inter-layer HO threshold" + "Adjacent Cell Inter-layer HO Hysteresis" - 64. The value of "Inter-layer HO threshold" can be set through "SET GCELLHOBASIC"
TA Handover This parameter specifies the actual coverage area of a cell. After receiving the channel request message or handover access message, the BTS determines whether the channel assignment or handover is performed in the cell by comparing the TA and the value of this parameter. The value of this parameter correlates with Cell ExtType. If this parameter is set to a too small value, the handover success rate may be affected
Bad Quality Handover Whether to enable the bad quality (BQ) handover algorithm. Whether to trigger BQ handover depends on the uplink and downlink transmit quality (measured by using BER). If the uplink or downlink BQ exceeds the BQ handover threshold, emergency BQ handover is triggered. The possible causes of BER increase (or quality degradation) include too low signal power and channel interference.
Load Handover Huawei 2G Load HO feature:
Load HO Allowed: This parameter is for traffic sharing between cells, if it adjusted “Yes” then it is enabled, if “No” then it is disabled. Load HO Bandwidth: The setting of this parameter depends on Edge HO DL Rx_Lev threshold parameter. Load HO can be performed, only receive signal level of the serving cell is between this threshold (Edge HO DL Rx_Lev; Edge HO DL Rx_Lev + Load HO Bandwidth). The value of this parameter ranges from 0 to 63 (corresponding to -110 dbm to -47 dbm). Load HO Threshold: Load HO is triggered when the occupation of TCHs in the serving cell reaches to this threshold. Threshold is 0 % - 100 %, default value is 85 %. Load Req. on Candidate Cell: If the cell load is smaller than this value then the serving cell will receive MSs handed over from other cells, otherwise MSs handed over will be rejected. Threshold is 0 % - 100 %, default value is 75 %. Load HO Step Period: If the cell load of the serving cell is equal or more than Load HO Threshold, then all MSs between defined bandwidth try to load HO. That is why for not overloading Central Processing Unit (CPU) of the BSC boards Huawei uses Load HO Step Period. Load HO performs according to this period with consecutively not all MSs at the same time. If it is set to a too greater value, the handover time of each level is long. Default value is 10 seconds.
Load HO Step Level: Load handover may lead to many handovers. Therefore, the load of the system CPU should be considered before load handover is performed. In other words, the system traffic volume should be taken into account. In addition, to prevent too many MSs from being handed over at a time, load handover is performed step by step. In other words, the edge handover threshold is increased on the basis of Load HO Step Level (CLS_Ramp) and Load HO Step Period (CLS_Period). When the increase in the edge handover threshold equals Load HO Bandwidth (CLS_Offset), the edge handover threshold is not increased any more.
Edge HO DL RxLev Thres. (-95db)
Edge HO DL RxLev Thres. + Load HO Bandwidth (-70db)
-95db
-70db
Load HO Step Level Load HO Step Period (5 sec.)
Load HO Bandwidth Load HO can be performed if the load of the serving cell is reached to Load HO threshold
Minimum Access RXLEV Minimum received signal level of the MS. This level is reported in the system information. This parameter specifies the minimum receive level of an MS to access the BSS. For details. see GSM Rec. 05.08. The value of this parameter ranges from 0 to 63 (corresponding to -110 dBm to -47 dBm) If the value of this parameter is too small, the required level of received signals is low. Therefore, many MSs attempt to camp on the cell, thus increasing the load of the cell and the risk of call drops. In such a case, you must set the parameter based on the balance conditions of the uplink and downlink levels
MS_TXPWR_MAX_CCH Maximum transmit power level of MSs. As one of the cell reselection parameters in system message 3, this parameter is used to control the transmit power of MSs. For details, see GSM Rec. 05.05. In a GSM900 cell, the maximum power control level of an MS ranges from 0 to 19, corresponding respectively to the following values (unit: dBm): 43, 41, 39, 37, 35, 33, 31, 29, 27, 25, 23, 21, 19, 17, 15, 13, 11, 9, 7, and 5.Generally, the maximum transmit power supported by an MS is level 5 (corresponding to 33 dBm). The minimum transmit power supported by an MS is level 19 (corresponding to 5 dBm). Other transmit power levels are reserved for high-power MSs. In a GSM1800 or GSM1900 cell, the maximum power control level of an MS ranges from 0 to 31, corresponding respectively to the following values (unit: dBm): 30, 28, 26, 24, 22, 20, 18, 16, 14, 12, 10, 8, 6, 4, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 36, 34, and 32. Generally, the maximum transmit power supported by an MS is level 0 (corresponding to 30 dBm). The minimum transmit power supported by an MS is level 15 (corresponding to 0 dBm). Other transmit power levels are reserved for high-power MSs The default value of "MS_TXPWR_MAX_CCH" in the GSM900 and GSM850 cells is 5; the default value of "MS_TXPWR_MAX_CCH" in the DCS1800 and PCS1900 cells is 0
Cell Bar Qualify Used together with "Cell Bar Access" to decide the priority status of a cell. See GSM Rec. 0408. This parameter does not affect cell reselection but cell selection only. Cell Bar Qualify Cell Bar Access Cell selection priority Cell reselection priority NO NO Normal Normal NO YES Prohibited Prohibited YES NO Low Normal YES YES Low Normal If the value of "Cell Bar Access" is YES and the value of "Cell Bar Qualify" is NO, new call access is prohibited but handover access is allowed
Cell Bar Access Used together with "Cell Bar Qualify" to decide the priority status of a cell. Refer to GSM Rec. 04.08. Cell Bar Qualify Cell Bar Access Cell selection priority Cell reselection priority NO NO Normal Normal NO YES Prohibited Prohibited YES NO Low Normal YES YES Low Normal The CBA function applies to special scenarios. If this parameter is set to YES and "Cell Bar Qualify" is set to no, only handovers are allowed in a cell, and direct access of an MS is not allowed. This condition applies to a dual-network coverage cell. For a common cell, this parameter should be set to NO.
