HO Algorithms in Huawei GSM Network

[Arsham]

Dear Huawei Experts,

Can You suggest me which HO Algorithm to use in GSM network 1 or 2?
And what are the differences and benefits?

After swap we have both of them.

[oswe]

i believe HO I is simplier to set. i remember someone indicating HO I as the default parameters values will do it. but to activate the HO II you need to be carefull

this is some text from huawei doc
Handover Decision Based on Handover Algorithm I

According to the emergency condition of an MS in the network, the handover decision based on handover algorithm I is made in the following order: quick handover, emergency handover, enhanced dual-band network handover, load handover, and normal handover.
Handover decision based on handover algorithm I involves the following procedures:

• Determining whether the serving cell meets the triggering conditions
• Selecting corresponding candidate cells

In handover algorithm I, Inter-RAT HO Preference specifies whether a neighboring 2G cell or a neighboring 3G cell is preferred.

• When Inter-RAT HO Preference is set to Preference for 2G Cell:A neighboring 2G cell is preferred. If the candidate cell list contains suitable neighboring 3G cells but no suitable neighboring 2G cells, a neighboring 3G cell is selected.
• When Inter-RAT HO Preference is set to Preference for 3G Cell:A neighboring 3G cell is preferred. If the candidate cell list contains suitable neighboring 2G cells but no suitable neighboring 3G cells, a neighboring 2G cell is selected.
• When Inter-RAT HO Preference is set to Preference for 2G Cell:If the RX level of a candidate 2G cell is lower than or equal to HO Preference Threshold for 2G Cell, a neighboring 3G cell is preferred.

If the triggering conditions of emergency handover are met and there is at least one candidate cell, then the emergency handover timer Min Interval for Emerg.HOs is started. Another emergency handover decision can be performed only when Min Interval for Emerg.HOs times out.


Handover Decision Based on Handover Algorithm II

Handover decision based on handover algorithm II is made in the following order: forced handover, emergency handover, intra-cell handover, and inter-cell handover.
Handover decision based on handover algorithm II involves the following procedures:

• Determining whether the serving cell meets the triggering conditions
• Selecting corresponding candidate cell list for each handover type
• Performing the comprehensive decision and determining the candidate neighboring cells

The procedure for performing comprehensive decision based on handover results and determining the candidate neighboring cells is as follows:

1. The BSC selects a handover type with the highest priority from all the handovers that can be performed on each neighboring cell.
   The handover priority is as follows:
   
   • Forced handover, emergency handover, and interference handover have a high priority. Figure 1 shows the details.
     Figure 1 Handovers with high priority
     
     
     NOTE: Quick handover is classified into frequency offset handover and quick PBGT handover. Frequency offset handover has a higher priority than quick PBGT handover.
   • Intra-cell handover (excluding interference handover) and inter-cell handover have a normal priority. Figure 2 shows the details. NOTE: AMR handover has the same priority as TCHF-TCHH handover.
     
     
     Figure 2 Handovers with normal priority
     
   
   
2. The BSC ranks the candidate cells according to the network characteristics adjustment algorithm and then generates the final candidate cell list. Every neighboring cell in the candidate cell list has its own handover decision. Neighboring 2G cells and neighboring 3G cells are ranked separately.
3. In handover algorithm II, Inter-RAT HO Preference specifies whether a neighboring 2G or a neighboring 3G cell is preferred.
   
   • When Inter-RAT HO Preference is set to Preference for 2G Cell:A neighboring 2G cell is preferred. If the candidate cell list contains suitable neighboring 3G cells but no suitable neighboring 2G cells, a neighboring 3G cell is selected.
   • When Inter-RAT HO Preference is set to Preference for 3G Cell:A neighboring 3G cell is preferred. If the candidate cell list contains suitable neighboring 2G cells but no suitable neighboring 3G cells, a neighboring 2G cell is selected.
   • When Inter-RAT HO Preference is set to Preference for 2G Cell By Threshold:If the RX level of a candidate 2G cell is lower than or equal to HO Preference Threshold for 2G Cell, a neighboring 3G cell is preferred.

NOTE: When a neighboring 3G cell is preferred among the candidate cells, the priority of 3G better cell handover is the lowest.


If the triggering conditions of emergency handover are met and there is at least one candidate cell, then the emergency handover timer Min Interval for Emerg.HOs is started. Another emergency handover decision can be performed only when Min Interval for Emerg.HOs times out.

[Arsham]

Dear oswe,

Thank You for Your depth explanation!