Let's sum up our achievements over the past month. Relay modes of our modems were worked out in one (devices of single rank) and in different frequency ranges (434 MHz / 2.4 GHz), including usage of high-speed relay links (devices of different rank). The power consumption modes (0.175 / 0.32 / 0.75 / 1.1 W) and adaptive change of processor clock frequency (0 / 64 / 170 / 487.5 MHz) depending on the task being performed were worked out. The 3rd week of continuous operation of one of the repeaters went on (Fig. 1). It works fine, but sometimes it freezes – rebooting is needed. We are working on fixing this issue. We've assembled an intermediate relay device with 2 directional antennas (Fig. 2). 2 modems that are connected directly via UART were used for this. In addition, it was possible to implement spatial transmit diversity.

Directional routing and addressing of zones/cells by different keys of PHY Layer Enc./ “DSSS modulations” (PHY Layer Direct Routing) were worked out to eliminate retransmissions and additional packet collisions when building complex MESH networks (Fig. 3). When placing a network of modules, they are surrounded by stations with only unique PHY Layer Enc. keys. By transmitting a signal with a certain “DSSS modulation”, only the desired station will receive it, while others will be able to do their tasks, and so on in the chain.

fig.3