In our last post we started by comparing you and a friend chatting in a café while a very loud talking lady was interfering with your conversation.
How embarrassing would it be to tell your friend something three times and have them never even acknowledge that they heard you…ever. In the wireless world, that’s called message acknowledgement.
Without capacity, message acknowledgement isn’t possible for some LPWA providers because it’s just too costly to support in terms of network capacity. This leaves users of those technologies susceptible to failed messages. Not so with RPMA, we have message acknowledgement as well as intelligent retransmission schemes for failed packets so that the entire message doesn’t need to be resent. RPMA keeps the conversation normal and efficient, without wasted repeats, or missed sentences.
But wait, there’s more! Now imagine you and your friend can magically understand each other even with Loud Voice lady while both of you are whispering. RPMA can do that. We can detect signals that are weaker than interfering signals that share the exact same channel. Move a channel or two over from ours and the interfering signals can be way more powerful than ours and we can still pick it out nice and clean. It’s like a wireless superpower. Because of the nature of direct-sequence spread spectrum, and our industry leading receiver sensitivity (-142 dBm) we can find signals hidden deep in the noise.
Unfortunately, our narrowband brothers don’t have the same luxuries with interference. Their messages are easily destroyed by even the shortest bursts of broadband transmissions on the same frequency. RPMA is extremely robust to interference by virtue of our MAC’s ability to handle a 50% packet error rate. That means half the packets can be lost and the message still gets through. An RPMA message is like the Zombie that no matter how shot up it gets, it just keeps on moving. Except RPMA is nicer, and doesn’t want to eat brains.
You know that friend who is always cool with last minute changes in evening plans? That’s RPMA. RPMA transmissions adapt to match the available channel quality.
Our modules have transmit power control and our MAC continually adjusts the spreading factor to use the most robust waveform possible. Finally, we have 40 channels to work with in the US because of our available 80 MHz of bandwidth so we have a lot of breathing room. RPMA’s sophisticated MAC, wealth of capacity, and intelligent use of the spectrum makes it incredibly robust to interference. This robustness has been confirmed for years in actual commercial deployments. For years RPMA has supported extremely demanding industries who need reliable communication with their devices.