Networking has become an inherent requirement for the development of IoT applications, and wireless connectivity technologies are no longer limited to short-range communication; they are evolving towards longer distances and broader coverage. This is where Low Power Wide Area Network (LPWAN) comes into play. LoRa, as a wireless technology within LPWAN, has a more mature industrial chain and earlier commercialization compared to other wireless technologies such as Sigfox and NB-IoT, making LoRa solutions (end devices + gateways) an ideal technical choice for large-scale IoT deployment.
LoRa operates at the physical layer or wireless modulation level to establish long-distance communication links. Many traditional wireless systems use Frequency Shift Keying (FSK) modulation as the physical layer due to its effectiveness in achieving low power consumption. LoRa, based on linear frequency spread spectrum modulation, retains the low power characteristics similar to FSK while significantly increasing communication distance. Linear spreading has been used in military and space communications for decades, as it enables long communication ranges and robustness against interference, leading to its initial commercialization.
LoRa and LoRaWAN
The advantage of LoRa lies in its long-distance capabilities from a technical perspective. A single gateway or base station can cover an entire city or an area of hundreds of square kilometers. While distance at a given location largely depends on the environment or obstacles, LoRa and LoRaWAN offer a link budget superior to any other standardized communication technology. The link budget, usually expressed in decibels (dB), is the primary factor determining distance in a given environment.
LoRaWAN defines the communication protocol and system architecture of the network, while the LoRa physical layer enables long-distance communication links. LoRaWAN is designed from the ground up, optimized for battery life, capacity, distance, and cost for LPWAN. It provides an overview of LoRaWAN specifications for different regions and a high-level comparison of various technologies competing in the LPWAN space.
In a LoRaWAN network, nodes communicate asynchronously, sending data whenever it is ready, whether event-driven or time-scheduled. In mesh or synchronous networks like cellular systems, nodes must wake up frequently to synchronize with the network and check for messages. This synchronization consumes energy, which is a major factor reducing battery life. A recent study by GSMA compared different LPWAN technologies and found that LoRaWAN offers a 3 to 5 times advantage over other options.
Features of LoRa
As a wireless technology, LoRa operates in the Sub-GHz frequency band, enabling long-distance communication with low power consumption, making it suitable for battery-powered devices or those powered by energy harvesting. The lower data rates also extend battery life and increase network capacity. LoRa signals exhibit strong penetration through buildings. These technological characteristics make LoRa particularly suitable for low-cost, large-scale IoT deployments.
Key data highlights include a reception sensitivity that can reach distances of 15 kilometers, a receiving current of 10 mA, and a sleep current of less than 200 µA.
LoRa Network Capacity
To enable long-range star networks, gateways must possess very high capacity or performance to receive messages from a large number of nodes. High network capacity is achieved through adaptive data rates and multi-channel, multi-modulation transceivers within the gateway, allowing simultaneous message reception across multiple channels. Key factors influencing capacity include the number of concurrent channels, data rates (air time), payload length, and how frequently nodes transmit data. Since LoRa is based on spread spectrum modulation, signals become orthogonal when different spreading factors are used. When the spreading factor changes, the effective data rate also changes. Gateways take advantage of this feature, allowing multiple different data rates to be received on the same channel simultaneously.
If a node has a good connection and is close to the gateway, there is no reason to consistently use the lowest data rate, as filling the available spectrum takes longer than necessary. The higher the data transmission rate, the shorter the air time, freeing up more potential space for other nodes to transmit data. Adaptive data rates also optimize battery life for nodes.
For adaptive data rates to function effectively, there must be sufficient downlink capacity. These characteristics endow LoRaWAN with very high capacity, making the network more scalable. Networks can be deployed with minimal infrastructure, and when capacity is needed, additional gateways can be added, data rates adjusted, and interference reduced, scaling network capacity by 6 to 8 times. Other LPWAN technologies lack the scalability of LoRaWAN due to technological trade-offs that limit downlink capacity, resulting in asymmetric downlink and uplink distances.
The Implementation of LoRa
LPWAN can be divided into two categories: one operates in unlicensed spectra, including technologies like LoRa and SigFox; the other operates in licensed spectra, supported by 3GPP for 2G/3G/4G cellular communication technologies, such as EC-GSM, LTE Cat-M, and NB-IoT.
South Korea has achieved a 99% population coverage with LoRa deployment, while China is still in its early stages without a mature network rollout. Many giants, such as China Mobile and ZTE, are actively promoting LoRa, yet another wide-area network communication technology is being pushed by China Mobile and Huawei: NB-IoT. Both technologies are still in the strategic layout phase, while other technologies remain in a wait-and-see stage. Enterprises utilizing LoRa technology for smart homes and intelligent communities are also in the experimental stage, but LoRa has received positive feedback for its low power consumption and high stability. Therefore, LoRa remains worthy of research and promotion, not merely a trend.
LoRa Architecture
LoRa, Wi-Fi, and BLE
From the perspective of replacing Wi-Fi or 3/4G, LoRa's technology has limited individual traffic bandwidth capacity. Compared to BLE, LoRa struggles to compete in the near-field communication market, making it nearly impossible to replace BLE in many aspects of smart homes.
If LoRa aims to enter the smart home sector, it faces the advantages of access interfaces such as ZigBee, Bluetooth, and Wi-Fi, as it seeks to capture existing market share. Without strong backing from leading smart home manufacturers, it will be challenging to succeed. Currently, no smart home company can claim significant dominance, but internal reports suggest that some advanced domestic smart home enterprises are beginning to research LoRa wireless systems, indicating a potential for strong promotion in China if the opportunity arises.
