Journal of Software:2018.29(S1):115-123

(西北大学 信息科学与技术学院, 陕西 西安 710127)
Fair Allocation Mechanism Based on the Number of Spreading Factors
LIU Ru-Yue,ZHANG Jing,ZHAO Jing-Jing,LIU Bao-Ying,CHEN Feng,ZHANG Tao
(School of Information Science and Technology, Northwest University, Xi'an 710127, China)
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Received:May 01, 2018    
> 中文摘要: LoRa网络使用宽带线性调频技术,利用设置不同的扩频因子(SF)来实现不同的传输速率.当网络中节点较多、发生碰撞时,具有高扩频因子的节点由于传输速度低、传输时间长,更易发生碰撞,传输成功率也相对较低.所以当网络中每种扩频因子分配同等数量的节点时,对于低速率的传输不够公平,因为其信道占用时间更长,碰撞概率更大.提出了一种基于扩频因子的分配机制(FSA).高扩频因子由于更易发生碰撞,传输成功率较低,因此给高扩频因子分配较少的节点、低扩频因子分配较多的节点,这样,不同扩频因子传输成功率相同.该机制有效地解决了碰撞网络中节点扩频因子分配不合理带来的公平性问题,降低了高扩频因子节点重传的概率,网络的稳定性大为提升.
中文关键词: LoRa  扩频因子  公平  碰撞  传输成功率
Abstract:LoRa network uses wideband linear frequency modulation techniques and employs different spreading factor (SF) settings to achieve different transmission rates. When there are many nodes in the network and collision occurs, nodes with higher spreading factor have lower transmission speed and longer transmission time, and are more prone to collision. The transmission success rate is also relatively low. Therefore, when each spreading factor in the network allocates the same number of nodes, it is not fair for low-rate transmission, because its channel takes longer and collision probability is greater. This paper proposes an allocation mechanism based on the spreading factor (FSA). The high spreading factor is more prone to collision and its transmission success rate is also low. Therefore, fewer nodes are assigned to the high spreading factor and low spreading factor allocates more nodes, so that the transmission success rate of different spreading factors is the same. Consequently the problem of fairness caused by the unreasonable allocation of the spreading factor of the nodes in the collision network is effectively solved, the probability of retransmission of high spreading factor nodes is reduced, and the stability of the network is greatly improved.
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基金项目:国家自然科学基金(201180026);创新人才推进计划(2018TD-026);陕西省重点研发计划(2018SF-369,2018KW-020) 国家自然科学基金(201180026);创新人才推进计划(2018TD-026);陕西省重点研发计划(2018SF-369,2018KW-020)
Foundation items:National Natural Science Foundation of China (201180026); Innovative Talents Promotion Plan (2018TD-026); Key R&D Programs in Shaanxi Province (2018SF-369, 2018KW-020)
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LIU Ru-Yue,ZHANG Jing,ZHAO Jing-Jing,LIU Bao-Ying,CHEN Feng,ZHANG Tao.Fair Allocation Mechanism Based on the Number of Spreading Factors.Journal of Software,2018,29(S1):115-123