For years, I've been working with the GSM specifications by now. My contributions to wireshark, airprobe and most of all the creation of OpenBSC about one year ago further forced me to become very intimate with the various GSM related protocols.
Over the last month or so, I've been looking into some 3G/UMTS specific protocols such as RANAP, as well as more recently at various LTE protocols. It seems like they're more or less all specified in ASN.1 and use a variety of encodings, e.g. PER aligned and unaligned.
Not having useful tools like a code generator for parsing and formatting messages as per those ASN.1 specifications is a major turn-off for starting any Free Software or Open Source project in this area.
It's like having to start from designing tires if you want to build a car. asn1c is a start, but it does not support all the required encodings and even ASN.1 syntax that is used in the 3GPP specs.
I really see a big demand here, otherwise Free and Open Source software development in this area will be severely hampered by the lack of required tools for even more time.
If anyone is interested in helping out to change this, please contact me!