This paper addresses the design of multiple access protocol for healthcare internet of things (HIoT) networking, where devices are massively deployed to facilitate ubiquitous service provision. While non-orthogonal multiple access (NOMA) has been considered a major breakthrough for next generation smart healthcare network and beyond, automated random access enabled massive connectivity remains a challenge. To this end, automated massive connectivity protocol is developed, where multiple devices compete for a power level to gain access whenever needed. The power level is selected randomly from a predetermined set derived using large dimensional analysis presuming user-load K significantly outnumbers the antennas equipped at access point (AP). As a contention-based random access protocol, the contention is resolved using ALOHA protocol. Moreover, simple forward error corrections (FECs) are introduced to enable massive connectivity in finite blocklength regime as well as to mitigate severe interference. In contrast to existing multiple-input multiple-output NOMA (MIMO-NOMA), the proposed scheme avoids spectral efficiency penalty due to preamble and the potentially long latency due to infinite blocklength as a result of density evolution method. The simulated results demonstrate that quality of service (QoS) in terms of enhanced random access, improved spectral efficiency and reduced power consumption, which justify the proposed MIMO-NOMA design evidently.

Low-power devices are massively deployed to facilitate real-time sensing and data transmission requested in low-power wide-area network. However, the dominating signaling, i.e., continuous phase modulation (CPM), barely gains attention in the context of supporting massive connectivity, not to mention ultra-reliable low-latency communications (URLLC), a primary concern in industrial network automation. To this end, autoconfigurable nonorthogonal multiple access (AC-NOMA) based on CPM signaling is proposed. The term autoconfiguration is used since each device selects a setup from a pool of configurations whenever connecting to the access point in a random and distributive way. It is proven, using ideal power allocation and phase shaping technique, that AC-NOMA offers drastically improved user load and near capacity performance even in finite blocklength regime. Moreover, to enable massive yet sporadic access, slotted ALOHA is combined with AC-NOMA. It is proven that the resultant scheme outperforms power-domain NOMA in terms of throughput even with reduced transmit power and simple forward error correction schemes, such as repetition and convolutional coding. The throughput is further improved using semi-AC-NOMA with slightly increased latency. It is demonstrated that both designs can support very high user load while enabling URLLC in finite blocklength regime, where the packet size is merely 256 bits while the error rate is $10^{-5}$ , which are also desirable in a number of applications, including satellite communications, visible light communications, etc.

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.

A class of simplified maximum-likelihood receivers designed for continuous phase modulation based multiuser systems is proposed. The presented receiver is built upon a front end employing mismatched filters and a maximum-likelihood detector defined in a low-dimensional signal space. The performance of the proposed receivers is analyzed and compared to some existing receivers. Some schemes are designed to implement the proposed receivers and to reveal the roles of different system parameters. Analysis and numerical results show that the proposed receivers can approach the optimum multiuser receivers with significantly (even exponentially in some cases) reduced complexity and marginal performance degradation.

Drone-aided networking is considered a potential candidate for internet of things (IoT) networking in 5G and beyond, where drones are deployed to serve a large number of devices simultaneously for data collection, surveillance, remote sensing, etc. However, challenges arise due to massive connectivity requests as well as limited power budgets. To this end, this paper focuses on the design of drone-aided IoT networking, where a drone access point serves a large number of devices for efficient data transmission, collection, and remote sensing. Constant envelope signaling such as minimum shift keying (MSK) family is considered to avoid potential significant power inefficiency due to nonlinear distortion. To this end, code-domain non-orthogonal multiple access (NOMA) is developed and analyzed in terms of achievable sum spectral efficiency. Further, power allocation is derived based on the aforementioned analysis and is demonstrated to offer significantly improved performance in terms of sum spectral efficiency and user load. Simulation results confirm the feasibility of the proposed design and shows that the designed system can attain the promised performance using either simple convolutional code or complex polar code. The proposed system can be used in scenarios such as deep space communications, where MSK family signaling is adopted as well.