One small, but important detail. The two streams have to have different spreading factors so that the streams are “Orthogonal” to each other.
7.1. LORA Modulation
The radio settings available for LORA modulation are: - The Frequency (Freq) as described in Section 7.5
- The Transmission Power (Tx Pow): in steps of 1 dBm between -18 dBm and
- Param 1: choose a Spreading Factor between SF5 and SF10
- Param 2 : choose a BandWidth (BW) of either 400 kHz, 800 kHz or 1.6 MHz
- Param 3: The Coding Rate (CR) of the Forward Error Correction applied to
the packet, of either CR 4/5, 4/6,4/7, 4/8 or CRLI 4/5, 4/6, 4/7
- Payload: size of the payload between 12 and 248 bytes
I don’t know where these parameters (SF, BW, CR, and Payload) are set. But we do know that the current modulation uses 1.6 MHz. In order to increase the process gain, we would need to maximize SF, decrease BW and increase CR/FEC. But if SF10 is already being used, the SF for the other carrier would have to have a different SF.