Performance of Narrow Band Wide Area Networks with Gateway Diversity

Abstract

This paper quantifies the coverage area of Low-Power Wide-Area Networks (LPWAN) for Packet Success Rates (PSR) above 85%, where acceptable Quality of Service (QoS) can be achieved. The network consists of battery-operated end-nodes (ENs) and multiple stationary gateways (GWs). We consider asynchronous communication that uses ALOHA-based random channel access. Each transmission from the ENs can be received by multiple GWs. Such spatial diversity results in favorable Signal-to-Noise ratios (SNR). The LoRa modulation is assumed and its specific features, such as IQ inversion, further contribute to decreasing the impact of interference. An increase in the GW density improves network performance, which allows support for a larger density of end-nodes as well as increasing the coverage area. Our simulation results show that a suburban area of up to 1.44 km2 can be covered with five GWs with up to fifty end-nodes with a PSR greater than 86%.

Beacon Success Rate versus Gateway Density in Sub-GHz Sensor Networks

“…The findings in this study indicate that enhancing beacon success rates can be achieved by implementing larger beacon intervals and increasing the number of channels. Introducing GW diversity proves advantageous in reducing beacon acquisition latency and expanding the coverage area [2]. In urban settings, the abundance of GWs enhances the potential for Gateway diversity.…”

“…In this paper, a star network topology is assumed, as depicted in Figure sensors are represented by different colored circles connecting to the GW multi-hop mesh topology is not recommended due to the already low bit-r in each link. Coverage issues are overcome by GW diversity instead [2]. Wi sity provided by the network operator, sensors can access cloud services v neighbor's GW or via the user's own GW.…”

“…The LBT mechanism is used for Uplink (UL) transmissions by the ENs to avoid interfering with each other and with the other beacons of neighboring GWs. This improves the performance significantly [1][2][3][4][5][6][7][8][9][10][11]. Nonetheless, in the Downlink (DL), GWs do not employ the LBT mechanism.…”

“…While interference in the environment cannot be controlled, intranetwork interference can be reduced by using efficient channel access algorithms such as Listen Before Talk (LBT) and frequency hopping, or Time Slotted Channel Hopping (TSCH) [1,3]. To control the collisions in random medium access, various techniques such as carrier sense and random backoff mechanisms can be used [1][2][3][4][5][6][7][8][9][10][11]. Collisions refer to the simultaneous use of the same radio channel by two or more devices transmitting at the same time.…”