What Does LoRa Gateway Mean is Really Hard to Answer
"What is LoRa Gateway?" Whenever someone asks me this question, it is difficult to know exactly how to answer it without knowing why they are asking. That's because LoRa Gateway can quote more than one thing:
Technically, it is a radio modulation scheme-a method of manipulating radio waves to encode information using a chirped multi-symbol format.
LoRa Gateway also refers to systems that support modulation, including LoRa Gateway chips and gateways.
Sometimes it refers to the LoRa Gateway communication network for IoT applications.
Essentially, LoRa Gateway is a smart way to get very good receiver sensitivity and low bit error rate (BER) from a cheap chip. This means that using LoRa Gateway instead of other radio technologies of the same price, low data rate applications can obtain a longer range.
But LoRaWAN Gateway is different. It is a media access control (MAC) layer protocol based on LoRa Gateway, using Semtech's LoRa Gateway modulation scheme. However, LoRaWAN Gateway is rarely used in industrial (private network) applications. It is more suitable for public wide area networks, because all channels are tuned to the same frequency; for single-area use, it is best to have only one network running to avoid collision problems.
Because all gateways in the network are bound to the same server, it is the server's job to decide which gateway should respond to the transmission. In large networks, any given transmission is usually heard by multiple receivers; then the server tells one gateway to respond and the other gateways ignore the transmission. This process helps avoid downlink and uplink conflicts because a single gateway is transmitting, and overlapping gateways can simply listen for other transmissions.
Another powerful feature of LoRa Gateway is the ability to demodulate several "quadrature" or simultaneous signals at the same frequency, assuming they have different chirp rates. In the data sheet, the LoRa Gateway chirp rate is called the "spreading factor", and a higher spreading factor indicates a slower chirp. Semtech's SX1301 chip supports this function. All Link Labs gateway systems can decode many simultaneous LoRa Gateway chirps at the same time, so that very large networks can be built.
Building such a LoRa Gateway network or system requires a lot of development. From LoRa Gateway to a functional wireless system is similar to from having a BPSK radio chip to having a WiFi network. The OSI layer 2 and above functions of large networks including gateways, repeaters, addressing, adaptive data rates, message retry, message confirmation, and high-capacity OFDM downlink signals are functions of systems such as LoRaWAN Gateway and Symphony Link.
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