Symbiotic radio (SR) has emerged as a spectrum- and energy-efficient paradigm to support massive Internet of Things (IoT) connections. Two multiple access schemes are proposed in this paper to facilitate the massive IoT connections using the cellular network based on the SR technique, namely, the simultaneous access (SA) scheme and the selection diversity access (SDA) scheme. In the SA scheme, the base station (BS) transmits information to the receiver while multiple IoT devices transmit their information simultaneously by passively backscattering the BS signal to the receiver, while in the SDA scheme, only the IoT device with the strongest backscatter link transmits information to the receiver. In both of the schemes, the receiver jointly decodes the information from the BS and the IoT devices. To evaluate the above two schemes, in this paper, we have derived the closed-form expressions of the ergodic rates and the outage probabilities for the cellular and IoT transmissions. Finally, numerical results are provided to verify the theoretical analysis and compare the two proposed multiple access schemes. When the number of IoT devices is small, the SDA scheme is more appealing since it can significantly reduce the computational complexity while achieving equivalent performance to the SA scheme. When the number of IoT devices is large, the SA scheme is preferable since it guarantees a significantly better rate performance and a lower outage probability.
翻译:共生无线电(SR)已经成为一种节省频谱和能源的技术,支持海量物联网(IoT)连接。本文提出了基于SR技术的两种多接入方案,以利用蜂窝网络支持海量IoT连接,即同时接入(SA)方案和选择多样性接入(SDA)方案。在SA方案中,基站(BS)向接收器发送信息,同时多个IoT设备通过被动背散射BS信号向接收器传输其信息,而在SDA方案中,只有背散射链路最强的IoT设备向接收器传输信息。在这两种方案中,接收器联合解码BS和IoT设备的信息。为评估以上两种方案,在本文中,我们推导了蜂窝和IoT传输的遇到速率和断线概率的闭合形式表达式。最后,提供数字结果以验证理论分析并比较两个提出的多接入方案。当IoT设备数量较少时,SDA方案更具吸引力,因为它可以显著减少计算复杂度,同时实现与SA方案相当的性能。当IoT设备数量较大时,SA方案更可取,因为它保证了显著更好的速率性能和更低的断线概率。