I am not completely sure about the end goal of this project. However I know what should be done initially to get cellular logs:
Getting Network Logs:
1. First the mobile device which you are using should have Qualcomm chipset SD835, SD845 etc. Intel will work too but had issues with AT commands.
2. In order to obtain networking logs i.e communication between BTS and UE, you need to get network logs from cellular processor using AT commands.
3. In order to obtain network logs you need to get root access of mobile device i.e install custom ROM on mobile device.
Selecting And Parsing Network Logs:
1. Once network logs are obtained then you need select logs e.g gsm, wcdma, LTE etc
2. Then comes parssing stage. Luckily there are Wireshark libraries which perform this task and give results in tree structures but there are limitations e.g libraries may not be able parse logs from all layers i.e LTE protocol stack layer 1 to 3
3. Once parsing is done then a comprehensive study of 3gpp documents is required in order to study network messages and shortlist required messages.
4. Once key network messages are shortlisted only then tasks comes decipher and other tasks.
In short. This project is extremely critical, time consuming and costly. This project requires a team not an individual. I know these details because I have this kind of work in a ln organization.
Frankly speaking if any freelancer claims he can do this job in 20 or 30 days, he is an absolute idiot.