30/07/2025
ST50H supports LoRaWAN Relay-- Providing the most cost-effective solution
(ST50H 支援LoRaWAN Relay 提供最佳成本效益解決方案)
Acsip ST50H fully supports the LoRaWAN Relay feature and has passed the LCTT test
(Acsip ST50H 完整支援 LoRaWAN Relay 功能且通過 LCTT 測試
LoRaWAN is a Low Power Wide Area Network (LPWAN) technology designed specifically for Internet of Things (IoT) devices. It provides long-range, low-power wireless communication capabilities, with a communication range of several kilometers. This makes it ideal for applications requiring wide-area coverage and where frequent battery replacement is impractical. However, in real-world deployments, some end devices may be located too far from gateways or situated in obstructed areas such as factories, tunnels, basements, or behind thick walls—making signal transmission to gateways difficult.
While adding more gateways can improve coverage, the high deployment costs and the complexity of providing power and network infrastructure can make installation challenging in certain locations. This is especially the case when only a few end devices require support, reducing cost-effectiveness. In such scenarios, introducing a Relay device offers a more flexible and cost-efficient solution. A relay node is a Class A LoRa device placed between end devices and the gateway, capable of long-term operation powered by batteries, and effectively extending system coverage.
Image Source https://blog.semtech.com/the-new-lorawan-relay-feature
Relay devices operate using a Channel Activity Detection (CAD) mechanism, listening for a very short duration (approximately 3–6 milliseconds) every second. This allows them to detect LoRa preambles in an ultra-low power mode. If LoRa activity is detected, the relay wakes up; otherwise, it returns to sleep. Each relay can support up to 16 different end devices.
End devices send a LoRa Wake-On-Radio (WOR) frame to wake up the relay. This WOR packet also carries metadata about the upcoming LoRaWAN message. Upon receiving the WOR, the relay replies with a WOR ACK, enabling synchronization. Because the relay only wakes once per second, the initial WOR frame must be about 1 second long. After synchronization is complete, the subsequent WOR frames can be significantly shorter.
Currently, the ST50H series supports relay functionality on the EU868 frequency band and has successfully passed relay certification testing provided by LCTT, meeting real-world demands for both wide coverage and low power consumption.
LoRaWAN 是一種低功耗廣域網路（LPWAN）技術，專為物聯網（IoT）裝置設計，具備長距離、低功耗的無線通訊能力，通訊範圍可達數公里，非常適合需要大範圍覆蓋、且無法頻繁更換電池的應用場景。然而，在實際部署中，有時會遇到部分節點距離過遠，或處於如工廠、隧道、地下室、厚牆等接收遮蔽死角中，導致信號難以傳遞至閘道器（Gateway）。
雖然增加閘道器能夠提升覆蓋率，但其部署成本較高、且由於電力與網路的線路配置，在部分區域可能施工不易，特別是在僅需支援少數節點的情況下，投資效益不高。此時，引入中繼( Relay )裝置可提供更具彈性與成本效益的解決方案。中繼節點為部署於終端節點與閘道器之間的 A 類 LoRa 裝置，可由電池供電並長時間運作，有效提升系統的涵蓋範圍。
圖片引用原廠連結 https://blog.semtech.com/the-new-lorawan-relay-feature
中繼設備透過 CAD (Channel Activity Detect) 機制，每秒監聽非常短的時間（約 3-6 毫秒），可以在極低功耗模式下檢測 LoRa 前導碼，如果偵測到 LoRa 活動，裝置將被喚醒，反之則重新進入睡眠狀態。一個中繼器最多可以支援 16 個不同的終端設備。
終端設備將傳送一個 LoRa WOR（Wake-On-Radio frame）來喚醒中繼器， WOR 封包同時也攜帶即將發送的 LoRaWAN 訊息概要資訊。中繼器接收到後會回傳 WOR ACK，完成時序同步。初次 WOR 因需匹配中繼器喚醒週期，會較長（約 1 秒）；同步完成後，後續 WOR 長度將大幅縮短。
目前， ST50H 系列可支持EU868頻段之中繼功能，並已通過 LCTT 所提供之中繼測試，可滿足實務上對於高覆蓋與低功耗的雙重需求。
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