4G Strategy: CSFB Balancing to F1/F2/F3

Background:

   It is found that during blind redirection to 3G, the more count of the highest priority neighbor, it is more likely to be selected as the redirection frequency to 3G, so CSFB to 3G F1/F2/F3 unbalanced.

Fact Finding:

CSFB to F1/F2/F3 was not balance, most of the CSFB fall on F1. Thus, it caused 3G voice load on F1 increased..

Pro :

•CSFB to F1/F2/F3 balanced.                            

Cons :

•No negative impacts.

•

Execution Selection Criteria :

•LTE eRAN 7.0 version

Analysis:

•  Each frequency should only have one neighbor configured as “high priority neighbor” to ensure all 3 frequency have the same probability to be selected as redirection frequency. So make sure that only co-sector neighbor’s blindhopriority to be set as “32”.

• CSFB Balancing was further optimized by turning on RsvdSwPara1_bit23. The random processing function has been optimized to balance the random distribution.

Parameter Setting :

4G Parameter	Number of CSFB 3G Neighbors	BlindHoPriority	RsvdSwPara1_bit23
Before	Different Numbers,Max.32 per 3G frequency per 4G cell	32(all neighbors)	0 (Off)
After	Only 1 neighbor per 3G frequency per 4G cell	32	1 (On)
	Other neighbors	0