###### Abstract  
Smart cities have been envisioned to provide smartness in managing internet of things (IoT) application domains, such as transport and mobility, health care, natural resources, electricity and energy, homes and buildings, commerce and retail, society and workplace, industry, agriculture, and the environment. The growth trajectory in usage of these IoT domains has led to a heterogeneous dense network in a smart city environment. The heterogeneous dense network in smart cities has led to challenges, such as difficulties in the management of LPWAN coexistence, interference, spectrum insufficiency, QoS, and scalability issues. The existing LPWAN technologies cannot support the heterogeneous dense network challenges in smart cities. Further, it cannot support diverse IoT, including medium- to high-bandwidth applications, due to the power, complexity, and resource constraints of the LPWAN devices. Hence, this paper addresses high data rate IoT applications and heterogeneous dense networks. This paper proposes a lightweight heterogenous multihomed network (LHM-N) model for diverse smart city applications that will address dense heterogeneity network challenges in a smart city. The work aims to advocate and integrate a manageable license-free LPWAN that will coexist with 5G private and public cellular networks in the LHM-N model. This will help to provide a cost-effective solution model in a heterogeneous dense smart city environment. Further, a secured lightweight energy-efficient packet-size forwarding engine (PSFE) algorithm is presented using the discrete event simulation (DES) methodological approach in MATLAB for complexity evaluation. In addition, a 5G reduced capability (RedCap) IoT device is integrated into the (LHM-N) model to support smart city. Finally, the results show that the LHM-N model outperforms the conventional quadrature amplitude modulation (QAM) protocol scheme in terms of error rate, latency, and data throughput with reduced energy costs for medium- to high-bandwidth industrial IoT applications. This validates the suitability of the LHM-N model for high data rate IoT applications. 5G redcap; coexistence; energy-efficient; heterogenous; lightweight; LPWAN-MHS; multihoming; optimization +
Footnote †: journal: Sensor and Actuator Networks  
led to a heterogeneous dense network in a smart city environment. Supporting massively connected devices requires very low-cost end users devices, such as LPWANs [1, 2, 3]. Several LPWANs meant to satisfy diverse IoT application domains can be attributed to this dense heterogeneity in a smart city. Heterogeneity is inherent in IoT communications due to the vast range of hardware and software capabilities [4]. LPWANs are considered preferred technologies for diverse IoT connectivity compared to short-range communication technologies, such as Bluetooth, ZigBee, and Wi-Fi, due to their unique characteristics [5]. However, high-bandwidth smart city applications, such as industrial wireless sensors (smart manufacturing/smart factory), smart wearabl, and video surveillance, are not supported by LPWAN. Consequently, the third-generation partnership project (3 GPP) has finalized the specification for the 5G reduced capability (RedCap) device, which was recently published in the latest 3 GPP release-17 [6]. This will support medium to high-speed connections for bandwidth-demanding smart city applications. Hence, RedCap devices can be positioned as a lower segment than eMBB (enhanced mobile broadband) devices with little variation in complexity and coverage distance compared to LPWAN devices. This means that it has more complexity with lesser coverage than the LPWAN by achieving a balance between network performance (high bandwidth and low latency) and device costs. Nevertheless, the reduced coverage can be compensated by considering smaller data rate specifications. This will help to improve coverage distance for the NR RedCap [7]. Further, the device protocol enhancement can achieve a reduction in complexity.