There would be a lot of questions and things to research. I am not familiar with qcom hexagon SDK. I am a little familiar with osmocom-bb source code and 2G GSM details. I am currently in the very beginning stages of porting osmocom-bb to the MediaTek 6260/6261 chip which supports 2G. I also have ideas to try and work through 3G on a MediaTek 6735 (ZTE Obsidian phone). Recently there have been mentions of re-writing the PHY layer of osmocom-bb for an SDR platform like LimeSDR. https://github.com/axilirator/osmocom-bb So at the current time I assume that osmocom-bb communicates with the DSP chip on the motorola phones in a way that abstracts the PHY layer details away and relies on the proprietary Texas Instruments firmware in the DSP as-is. So I would imagine you might have to implement the PHY layer and also the interface to the PHY layer. There was a discussion about this recently on IRC #osmocom. It seems the thought was that qcom had released enough with their Hexagon SDK to allow development of a PHY layer + whatever else. Some links of interest. https://developer.qualcomm.com/ - SDK https://github.com/ttsou/openphy - LTE PHY for Ettus USRP https://androiddatahost.com/fgd43 - qcom flash image loader I have a few qcom modems that I'd be happy to do experiment on if that helps. -Craig