关键词: LoRaWAN, 信道接入方法, 先听后说, 模拟退火算法, 竞争窗口

Abstract:

The pure ALOHA channel access method defined in the standard LoRaWAN protocol can cause a lot of collisions and transmissions failed when in a heavy load, it challenges the scalability and reliability of the LoRa network greatly. A new channel access method, LBT-SA （Listen Before Talk combined with Simulated Annealing）, is proposed. This method reduces the probability that multiple devices access the channel by detecting the channel before sending, and searches for a smaller backoff time by taking the backoff time required for successful transmission as the initial value. Simulation results show that LBT-SA can not only maintain the packet delivery rate provided by LBT with binary exponential backoff algorithm, but also minimize the unnecessary backoff in the transmission, thus reducing the delay. In a scenario where up to 10,000 end-devices access a single gateway, the average backoff time of the algorithm is reduced by at least 16.38%.

Key words: LoRaWAN, channel access method, listen before talk, simulated annealing algorithm, competition window