QoS Provision for Industrial IoT Networking: Multiantenna NOMA Based on Partial CSIT

The acquisition of small-scale fading is essential but challenging in industrial Internet of Things (IIoT). This article concerns with the quality of service (QoS) provision for IIoT uplink networking, in terms of reliability, latency, and connectivity without resorting to small-scale fading. To this end, a scheme based on multiantenna nonorthogonal multiple access (mNOMA) technique is proposed. Different from existing setups, the proposed system is designed to work in overloaded regime where the number of devices
$K$
significantly outnumbers
$N_{r}$
, the antennas equipped by the access point, i.e.,
$K\gg N_{r}$
, such that concurrent massive connectivity is enabled using off-the-shelf equipment. The design starts with the development of asymptotic performance analysis in terms of signal to interference-plus-noise ratio, where a closed-form expression is obtained taking massive connectivity, finite blocklength, and code rate into consideration jointly. The analysis implies the possibility of QoS provision without estimating small-scale fading at transmitter side. Then the insight is leveraged to develop mNOMA with special focus on minimum shift keying type waveform, which is widely adopted in low power wide area IIoT standards including IEEE 802.15 series. Power allocation and code rate adaption are employed to offer QoS guaranteed performance as the blocklength is only 512 bits, whereas dozens of devices simultaneously transmit at block error rate down to
$10^{-5}$
or even lower, as required by industrial 5.0 and beyond.