LTE CSFB Quality Optimization Analysis Solution

Overview
      With the overall construction and commercial application of LTE network, CSFB process, as the voice solution in early stage of the LTE network, becomes more and more important to affect user voice service perception. CSFB service analysis can analyze the success rate and delay of CSFB paging, calling, called, fallback and return etc. through the correlation of whole signaling process records such as MC, S1, SGS, S6A and S11, so as to improve the CSFB service quality rapidly and enhance the user satisfaction.

Solution
      By the end-to-end analysis on the CSFB process, it is possible to achieve the comprehensive solution for the CSFB process of the LTE network. It has developed 5 types including over 40 sub-module features based on NAS signaling decryption technology, online associated backfilling technology and end-to-end indicator system, in order to analyze and guarantee the CSFB service quality comprehensively, and among which, calling and called process analysis, process delay analysis and adjacent area analysis can provide an important analysis for the network optimization.
The range of CSFB service monitoring and collecting is shown as follows:
 

Optimization analysis modules

1. TA/LA planning and adjacent area configuration analysis
For configuration contents to be needed in the CSBF process, ZCTT signaling monitoring system develops the TA/LA planning and adjacent area configuration analysis function, which uses relevant LTE cell and CS cell in the fallback and return process to execute the adjacent area analysis, so as to find out problems like relevant error, match-missing adjacent area and mismatching adjacent area.

2. CSFB called process optimization
Compared to CSFB calling and 2G/3G called process, CSFB called process is more complex, involves more key devices and parameters, and impact greatly on the user perception. It includes the following several sub-modules:
a) Joint attachment and location updating analysis of CSFB users
b) Called paging analysis
c) Called fallback analysis
d) Calling connection analysis

3. CSFB calling process analysis
To show the end-to-end feature of CSFB calling service better, integration and improvement should be made on the basis of the original feature, in order to output the existed network problems directly and optimize easily. It includes the following several sub-modules:
a) LTE service access analysis
b) Calling fallback analysis
c) Call connection analysis

      The CSFB system of ZCTT has already been online operation stably by mobile operators in 6 cities. Also, it can customize various functional modules for the regional characteristics to solve the regional problems. Furthermore, ZCTT also cooperates with provincial operators to make the research on the CSFB to confirm what influences of equipment parameters on the network.