Based on a lot of test experiments and theoretical analysis , the problem of electromagnetic waves transmission in the building of public flue was studied , the special nature of public flue environment and factors af-fecting the electromagnetic transmission loss were analyzed .A scheme is proposed for wireless transmission based SX1278 over IoT system of building centralized purification .The scheme uses direct sequence spread spectrum modulation to improve Anti Packet Loss performance of the system , and use truncated binary index retreat algorithm as a retransmission mechanism to resolve conflict collision of node signals .The base station ensures the synchroniza-tion and real-time property of the count by using time slice rotation scheduling algorithm .Integration test and field test results show that , the scheme is well solve the problem of the stability of the flue wireless signal transmission , and the packet loss rate and bit error rate is low , better system reliability .%在大量测试实验和理论分析的基础上，研究电磁波在楼内公共烟道的传输问题，分析公共烟道环境的特殊性以及影响电磁波传输损耗的因素。提出一种适用于楼宇集中净化物联网系统的基于SX1278的无线传输方案。该方案采用直接序列扩频调制来提高系统的抗干扰性能，采用截断二进制指数退避算法作为重传机制来解决节点信号冲突碰撞问题。通过在基站端采用时间片轮转调度，来保证计数的同步性和实时性。集成测试和实地测试结果表明，该方案很好地解决了烟道内无线信号的稳定传输问题，且丢包率和误码率较低，系统可靠性好。
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