M-ary Aggregate Spread Pulse Modulation (M-ASPM) is a recently introduced physical layer (PHY) modulation technique that is well suited for use in low-power wide-area networks (LPWANs). Notably, M-ASPM combines high energy-per-bit efficiency, robustness, resistance to interference, and a number of other favorable technical characteristics, with the spread-spectrum ability to maintain the capacity of an uplink-focused network while extending its range. However, while the essential tools for detection and synchronization of pulsed spread-spectrum waveforms in general, and the M-ASPM signals in particular, have been previously provided, a practical framework for combining the detection, synchronization, and decoding of an M-ASPM packet has not been yet suggested. In this paper, we outline such a framework, and describe a prototype algorithm for its implementation. This implementation can be subsequently adapted, under given technical constraints, to specific practical complications such as, for example, significant delay spreads, external technogenic interference, or co-channel and inter-channel collisions. In addition to low latency and computational complexity, the main requirement for this prototype algorithm is that the signal quality remains effectively invariant, for a given path loss, and for a wide range of the data rates, payload sizes, lengths of pulse shaping filters (PSFs), and pulse duty cycles, for a relatively large mismatch in the frequency of the local oscillators (LOs) in the transmitter (TX) and the receiver (RX), and for the TX and RX motions at relatively high speeds. Further, this needs to be achieved without any feedback communications between the TX and RX, any hardware or software changes in the TX, and any hardware adjustments in the RX (e.g., in the LO~frequency or sampling time offsets).

M-ary Aggregate Spread Pulse Modulation (M-ASPM) is the physical layer (PHY) modulation technique that is well suited for use in low-power wide-area networks (LPWANs). Notably, M-ASPM combines high energy-per-bit efficiency, robustness, resistance to interference, and a number of other favorable technical characteristics, with the spread-spectrum ability to maintain the capacity of an uplink-focused network while extending its range. However, when all M-ASPM nodes transmit with the same average power, implementation of such capacity-preserving range extension may become impractical in complicated propagation environments with greatly varying path losses. Favorably, the efficiency of M-ASPM with constant-envelope pulses can be maintained effectively the same as the efficiency of transmitting a continuous constant-envelope waveform. Then the transmit power of different nodes can be adjusted, without sacrificing the transmission efficiency, to compensate for differences in the path attenuation. This enables us to significantly simplify planning and management of the network. In addition, such a variable-power approach generally increases the network capacity and the average energy efficiency of the nodes, as compared with the arrangement of the nodes with a constant transmit power. In this paper, we outline a practical approach to implementing such an energy-efficient M-ASPM power control, that can be used for scaling LPWANs with realistic desired and/or actual areal distributions of the uplink nodes under diverse propagation conditions.

This paper presents an overview of the M-ary Aggregate Spread Pulse Modulation (M-ASPM), and provides an assessment of its suitability and advantages for use in low-power wide-area networks (LPWANs). M-ASPM combines high energy-per-bit efficiency, robustness, resistance to interference, and a number of other favorable technical characteristics, with the spread-spectrum ability to maintain the network capacity while extending its range. Throughout the paper, LoRa is used for benchmark comparison and quantification of various M-ASPM features. In particular, we demonstrate that, while sharing many essential properties with LoRa, M-ASPM provides far more effective network range extension. When used in the same manner as LoRa, M-ASPM can serve as an appealing LoRa alternative. In addition, while being different LPWAN solutions, M-ASPM and LoRa can be designed to concurrently operate in the same spectral band and geographical area, cooperatively complementing each other’s coverage.

In low-power wide-area networks (LPWANs), various trade-offs among the bandwidth, data rates, and energy per bit have different effects on the quality of service under different propagation conditions (e.g. various types of fading), interference scenarios, multi-user requirements, and design constraints. Such compromises, and the manner in which they are implemented, fur- ther affect other technical aspects, such as system’s computational complexity and power efficiency. At the same time, this difference in trade-offs also adds to the technical flexibility in addressing a broader range of the Internet of Things (IoT) applications. This paper addresses a physical layer LPWAN approach based on the Aggregate Spread Pulse Modulation (ASPM) and provides a brief assessment of its properties in an additive white Gaussian noise (AWGN) channel. In the binary ASPM, the control of the quality of service is performed through the change in the spectral efficiency, i.e., the data rate at a given bandwidth. Implementing M-ary encoding in ASPM further enables controlling service quality through changing the energy per bit (in about an order of magnitude range) as an additional trade-off parameter. Such encoding is especially useful for improving the ASPM’s energy per bit performance, thus increasing its range and overall energy efficiency, and making it more attractive for use in LPWANs.