LPWAN is a wireless network technology that uses low bit rate for long-distance communication. The LPWAN has a transmission speed of between 0.3 kbit/s and 50 kbit/s per channel. The most salient features of this technology are low energy consumption, low cost and support for long-distance data transmission. Therefore, it can meet the operational needs of IoT devices on city levels. It is suitable for the domains of low-frequency data transmission, such as, environment monitoring, vehicular fleet management, smart parking and water pipes detection. However, LPWAN also has its drawbacks. For example, its transmission speed is very slow; some technologies limit the update frequency of communication, so it is not always possible to complete information transmission. This section describes the three technologies with the highest penetration rate in the Low Power Wide Area Network (LPWAN): 'SIGFOX', 'LoRa' and 'NB-IoT'¹.

1蕭佑和,「萬物聯網，淺談IoT低功耗廣域網路趨勢：LoRa、SIGFOX、NB-IoT」,博客,2018 年 1 月 28 日。

• 1SIXFOX^1,2,3
SIGFOX is the technology with the lowest transmission speed among low-power WAN technologies. Its transmission speed is only 100 bits/s; also, each device can transmit only up to 140 messages per day and the payload of each message cannot exceed 12 bytes. The advantages of such configuration include : saving a great amount of power consumed by the device and the possibility of allocating bandwidth to more devices under the same network construction at the same time. At present, a single SIGFOX base station can be connected to up to 1 million devices. This is very important to the IoT, which is established by a large number of devices. SIGFOX currently uses the Sub-1 GHz ISM band for communication. This communication frequency band is an unlicensed frequency band. Users do not need to apply for permits or pay fees. They only need to comply with certain transmission power (generally less than 1W), and do not cause interference to other frequency bands. The biggest feature of SIGFOX is that it focuses on a single operator (SIGFOX Network Operator, SNO), providing services in a region and establishing the same IoT network worldwide.

2李一詩,「物聯網重點技術 LPWAN 解析，6大主要技術、各家優勢與產業發展、商業模式與智慧城市應用」,博客,2017 年 3 月 2 日。

3李文恩,「低功耗廣域網路串起物聯網裝置（4）：Sigfox」,博客,2017 年 3 月 31 日。


• 2LoRa^1,2,4
The LoRa name originated from 'Long Range', which indicates that this technology can support communications over extremely long distances. Although its communication distance is slightly shorter than SIGFOX, its transmission bandwidth is higher. In addition to being capable of one-way communication transmission like SIGFOX, it can also execute two-way data exchange. LoRa divides communication transmission into three different classes: Class A, Class B, and Class C by power consumption and transmission speed. The Class A method saves the most power, but the latency in data download is relatively noticeable. Most network systems nowadays use a mesh topology, but LoRa uses a star topology to reduce the complexity and power consumption of the overall network. Like SIGFOX, LoRa uses unlicensed bands. However, unlike SIGFOX which adopts an operational mode in which network is provided exclusively by a single operator in an area, LoRa allows anyone to set up a base station to build a network environment. With more than 500 members now, LoRa is the most sought-after LPWAN technology.

4李文恩,「低功耗廣域網路串起物聯網裝置（2）：LoRa」,博客,2017 年 3 月 21 日。


• 3NB-IoT^1,2,5
NB-IoT, or Narrow Band Internet of Things in full name, is a narrowband radio communication technology designed specifically for IoT devices. The biggest difference between NB-IoT and SIGFOX and LoRa is that it transmits data using licensed frequency bands, which are the same communication bands as the ones used by ordinary mobile phones. The advantage is that the signal is relatively stable and not susceptible to interference, which can reduce communication latency, ensure data security and maintain a high level of network transmission quality. The excellent service quality of NB-IoT makes it suitable to be used in involving financial and security, such as, monitoring banking facilities, alarm systems, health/medical applications, etc.

Another difference among NB-IoT and SIGFOX and LoRa is that NB-IoT does not need to re-establish the network and base station because it is compatible with the base stations of 4G LTE mobile communication. In other words, if an area is covered by 4G LTE mobile communication, there is no need to set up a dedicated base station. However, the cost of NB-IoT is higher than SIGFOX and LoRa and fees are incurred when each device is for executing data communication. Therefore, NB-IoT is more suitable for tracking goods with high prices or applications that are directly related to consumers.

5李文恩,「低功耗廣域網路串起物聯網裝置（3）：NB-IoT」,博客,2017 年 3 月 24 日。