Syncast Tech Report Vol.2
syncast tech report vol 2Long-distance Offline Communication × LoRa P2P × Syncast
"Syncast" is a solution that allows devices to communicate directly (Peer-to-Peer) and synchronize or share data, even in environments entirely without internet connection.
Typically, Syncast utilizes Wi-Fi and Bluetooth for high-speed data synchronization over short distances (tens of meters). However, real-world DX fields, such as mountainous areas and tunnels, often feature "communication dead zones extending for several kilometers." To tackle this, we implemented P2P communication using a proprietary protocol over the low-power wide-area wireless technology "LoRa". We verified a communication infrastructure that enables "infrastructure-less" and "kilometer-scale" ultra-long-distance two-way synchronization.
Verification Summary
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Result: Established LoRa P2P communication in a downtown office district (Marunouchi, Tokyo).
Successfully achieved stable communication in an urban area with high radio interference using "P2P mode," communicating directly between devices without routing through cellular networks or LoRaWAN gateways. -
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Tech Achievement: Demonstrated payload transmission for Syncast.
Confirmed the transmission of 256 bytes of data necessary for Syncast data synchronization. Through our proprietary implementation, we secured real-time performance with virtually no perceived latency. -
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Applicability: Two-way collaboration in disasters and remote areas.
Demonstrated the feasibility of "two-way communication," such as chatting and transmitting instructions directly between field sites.
Background: Why does Syncast need "LoRa P2P"?
Addressing the challenges of modern industrial sites and disaster BCP,
we identified three critical barriers: "Distance", "Infrastructure", and "Directionality".
Wi-Fi and Bluetooth, traditionally used by Syncast, are fast, but their range is limited to a few hundred meters. A new long-distance method was required to connect physically separated locations like expansive construction sites or scattered mountain villages.
Cellular networks (4G/LTE) are the standard for long-distance, but "dead zones" like deep mountains, tunnels, and offshore persist. Moreover, if base stations fail during a disaster, infrastructure-dependent communications completely paralyze.
While LPWA technologies like LoRaWAN enable long-distance communication, they are typically designed for aggregating sensor data to the cloud (uplink). Standard specifications (e.g., Class A) are poorly suited for "two-way synchronization" needed for interactive worker communication.
Implementation: Proprietary System via LoRa P2P
In this verification, we developed and tested a proprietary protocol
to carry Syncast's data synchronization over long-distance wireless.
By customizing a standard LoRaWAN module, we achieved gateway-less P2P communication.
System Configuration: Gateway-less Proprietary Network
- Edge Device: Raspberry Pi + STMicroelectronics B-L072Z-LRWAN1
- Comm. Method: P2P communication via proprietary protocol using LoRa modulation
- Test Data: Text data (including Japanese characters) simulating Syncast messages
* Note on Scalability: This implementation assumes P2P communication bridging specific base points. For large-scale topologies involving numerous end devices, building a structured network with gateways is recommended.
Implementation Logic: Optimizing for Syncast
While this is a relatively large payload size for LoRa, our proprietary tuning achieved low-latency transmission.
Field Results: Testing in a Downtown Office District
We conducted communication tests using Raspberry Pi units in the Marunouchi area of Tokyo, a notoriously harsh radio wave environment. We leveraged the location to verify performance on actual streets heavily densely populated with high-rise buildings.
Verification Data Details
| Environment | Office district near Tokyo Station (Marunouchi) |
|---|---|
| Distance | Approx. 250 meters |
| Data Size | 256 bytes |
| Latency | Almost real-time |
Discussion: Expectations for Line-of-Sight Communication
We confirmed stable communication between intersections on downtown streets filled with signal reflections and interference. Given the characteristics of LPWA, this strongly indicates that kilometer-scale communication is entirely possible in obstacle-free "Line-of-Sight (LoS) environments" such as mountains or riverbanks.
Furthermore, we proved that a link capable of transmitting 256 bytes per second is highly practical for syncing core field information like text chats, GPS data, and work instructions, even without the capacity for heavy media like images.
Syncast's Uniqueness and Future Outlook
Through this verification, Syncast has established a long-distance communication layer via LoRa,
complementing its existing short-range capabilities using Ditto (Wi-Fi/BLE).
Comparison: What Makes Syncast Different?
The differences between typical cloud-centralized LoRaWAN solutions and our edge-distributed Syncast solution are as follows:
| Feature | Typical LoRaWAN Services | Syncast × LoRa (Our Solution) |
|---|---|---|
| Comm. Direction | Uplink-centric (Sensor → Cloud) |
Two-way Sync (Device ⇔ Device) |
| Data Location | Cloud-centralized (Internet Required) |
Edge-distributed (No Internet Required) |
| Infrastructure | Base stations/Gateways required | Direct device communication (P2P/Mesh) |
| Main Use Cases | Meter reading, tracking, environment monitoring | Chat, instruction dispatch, situation sharing |
Future Outlook: The Best Mix of "Short-range" and "Long-range"
Our next step is the realization of a hybrid communication environment ("Syncast Hybrid Mesh")
that seamlessly integrates short-range and long-range networking.
Short-range (High Bandwidth)
Within a radius of several tens of meters, we use Wi-Fi / BLE.
Performs high-speed synchronization of rich information such as images, audio, and drawing data.
Long-range (Low Bandwidth)
For bases several kilometers apart, we synchronize using LoRa.
Reliably delivers critical, minimal information such as text chats, location data, and alerts.
Furthermore, as shown in the figure, communication is viable in both physically closed (air-gapped) and cloud-premised environments.
We envision utilizing closed networks for handling sensitive data inside factories, and cloud-mediated networks when data needs to be accessed remotely.
Users can naturally share rich media with those nearby and text with those far away "without the internet", completely unaware of the underlying communication methods.
This "Uninterrupted Connectivity" is precisely the disaster-resilient social infrastructure Syncast aims to build.
Join us in developing this technology.
For inquiries regarding the Syncast series and Ditto, consultation on creating applications that enable device-to-device communication,
or if you are interested in joining us as a Business Member or Development Member to promote this project,
please contact us via the form below or the email address.