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LoRa技术是一种调制技术，由semtech公司推出。在此基础上定义
的LoRaWAN协议解决了广域网低功耗的传输、组网问题。欢迎大家参与讨论
Yue TANG：
关于LoRa，参考TI 博文《Long-range RF communication: Why narrowband is the de facto standard》
http://www.ti.com/lit/wp/swry006/swry006.pdf
The 168 dBm link budget comes from the SX datasheet number of -148 dBm sensitivity. This sensitivity is at 18 bps (yes, 18 bits per second), which is not a usable rate for any application, just a showcase number for the datasheet frontpage. For a rate of 4.8 kbps, a solution based on TI Narrowband technology will give more range and a more robust link than a link using LoRa.
The modulation format in LoRa is Chirp Spread Spectrum (CSS), a technology invented in the 1930's. CSS is widely used in radar and ranging applications, but not in communications systems. The main reason CSS is not used in communication systems is the very weak co-existence performance, i.e. the ability to reliably operate in presence of interference. LoRa spread the signal information over a wide bandwidth (500 kHz), but will be jammed by any other system operating in this bandwidth (check out the co-channel rejection on page 21 in the SX1276 datasheet…..). Semtech claim LoRa has great co-existence, but their own datasheet measurements show performance 50 dB worse than TI narrowband solutions.
Using a wide bandwidth to send a low rate signal, using a modulation format that does not tolerate any activity in the used bandwidth, this is something that will not work in a real environment with real interference. The de-facto standard for long range communication is narrow band, this offers the best range, co-existence and robustness. For more details also check out the white paper on long range RF communication:
Albin Zhang：
回复 Yue TANG:
艾利克斯，是啊，我做过实验，jammer下，确实narrow band表现非常好。
BR. AZ
Eggsy Pang：
总结一下：
Lora在接收灵敏度确实优秀，主要是因为lora技术采用的是扩频技术，为了达到很低的码率，采用扩频码来纠正位错。比如要传一个bit，由于扩频，实际上可能传32bit，所以这里会引来一个速率问题和频谱利用率的问题。毫无疑问，一个bit要用32个bit来传，数据有效速率肯定很低。扩频带来的影响就是频谱占有率高，也就是说信道会减少。
扩频还有另外一个影响就是抗干扰能力差，因为扩频带宽宽，开的窗口大，吹进来的风和沙子自然多很多。
所以Lora适合运用于一些低速率、无线环境较纯净的场合
如果用于高速，抗干扰能力强的场合，用窄带技术的无线芯片比较适合，如TI的CC1125
