What is the principle of wireless communication technology?

Network-free communication technology is a technology that enables long-distance communication through direct communication between devices without traditional network coverage. This technology usually relies on wireless communication technologies such as Bluetooth and spread spectrum technology (such as TPUNB, and LoRa). It can achieve point-to-point voice intercom and text transmission in an open environment.

For example, the kilometre-level network-free communication technology launched by Vivo is mainly based on Bluetooth technology and combined with LoRa spread spectrum technology, enabling it to achieve a communication distance of more than 1.5 kilometres without network coverage. In addition, the vivo X200 series of mobile phones also supports SOS text broadcasting and one-to-one voice intercom functions, which allows users to maintain communication in extreme environments.

The working principle of this technology is to achieve communication in areas without network signals through direct wireless connection between devices, without relying on any external network infrastructure (such as base stations or routers). This technology is particularly suitable for outdoor activities such as hiking and camping, as well as disaster relief and other scenarios, ensuring that users can still maintain communication without network coverage.

1. Advantages and Disadvantages of Network-free Communication Technologydvantages of Network-free Communication Technology

Network-free communication technology has significant advantages, but it also has some limitations, as follows:

1. Advantages of Network-free Communication Technology

No need to rely on network infrastructure: Network-free communication technology can communicate directly between devices without cellular networks or the Internet, and is suitable for areas where network infrastructure is insufficient or damaged.

Low latency: Direct communication between devices without going through intermediate network nodes or servers reduces latency and speeds up information transmission, which is particularly beneficial for scenarios that require real-time communication, such as emergency rescue and equipment linkage.

Privacy and security: Information transmission does not pass through the public network, and data is only transferred between devices, effectively protecting user privacy. It is suitable for scenarios with high information security requirements, such as the military and law enforcement fields.

Low power consumption: Most network-free communication technologies (such as TPUNB, LoRa, Zigbee) are designed for low power consumption, suitable for small battery-powered devices, which helps to extend the service life of the device and is suitable for the Internet of Things and sensor networks.

Temporary and emergency applicability: Network-free communication is suitable for establishing temporary communication networks, which can quickly restore basic communication needs in natural disasters, emergency rescue, etc., and support rescue and information sharing.

2. Limitations of wireless communication technology

Limited communication range: Most wireless communication technologies have limited transmission distances. For example, the effective range of Bluetooth is usually around 10 meters, while that of Wi-Fi Direct is around 100 meters. Although TPUNB and LoRa have a longer coverage range, the signal attenuation is obvious in urban environments. Therefore, there are still bottlenecks in long-distance transmission.

Limited bandwidth and rate: Most wireless communication technologies have low bandwidth, which is suitable for small data transmission, but not for applications with high bandwidth requirements (such as video streaming). This limits its use in some data-intensive applications.

Limited network scalability: Wireless communication technology is more suitable for small-scale, limited node connections, and it is difficult to support the networking needs of large-scale devices. For scenarios where thousands of devices need to be connected at the same time, wireless communication may not be able to stably support it.

Data reliability and stability: Since there is no fixed network infrastructure as support, the signal is easily affected by terrain, environmental obstacles and interference, especially in complex urban environments or underground areas, where signal instability or loss is likely to occur.

Network complexity and maintenance: Although wireless communication does not require infrastructure support, some types of nodes (such as Mesh networks) are complex to manage themselves and have high maintenance costs. In addition, the failure of some nodes may affect the reliability of the overall network.

Network-free communication technology has irreplaceable advantages in specific scenarios, especially for emergency rescue, remote areas and applications with high privacy. However, limitations such as bandwidth restrictions, transmission distance and network scale also limit its widespread application. When choosing network-free communication technology, it is necessary to comprehensively consider the specific needs of the application scenario and the trade-off of communication performance.

2. How to combine Bluetooth and LoRa technologies in kilometer-level network-free communication technology

In kilometer-level network-free communication technology, the combined use of Bluetooth and LoRa spread spectrum technology is mainly reflected in the realization of long-distance communication through special protocols and algorithms. Specifically, Vivo uses this technology on its X200 series mobile phones, using the mobile phone's radio hardware, combined with Bluetooth and LoRa spread spectrum technology, to achieve a maximum communication capability of 1.5 kilometres without network coverage.

Bluetooth technology is usually used for data transmission and control within a short distance, while LoRa spread spectrum technology is used for long-distance communication. By combining these two technologies, the shortcomings of each in coverage and accuracy can be compensated, thereby achieving more comprehensive and stable communication services. For example, in indoor scenarios, Bluetooth can be used for connection and data transmission between devices, and when longer-distance communication is required, LoRa technology is used to achieve long-distance communication from the device to the cloud.

In addition, this combined technology is also economical and practical and can provide a free and efficient "no-cost communication" solution.

3. How does network-free communication technology ensure the security of data transmission?

The security of wireless communication technology relies on a variety of encryption and protocol measures to ensure that data is transmitted safely and reliably in a network-free environment. Commonly used security mechanisms:

1. End-to-end encryption

Kilometre-level wireless communication usually uses end-to-end encryption (E2EE) to ensure that after the data is encrypted at the sending end, only the receiving end can decrypt and read it. This encryption method is difficult to crack even if it is intercepted during transmission.

2. Key negotiation and exchange protocol

In order to ensure the security of the key for data encryption, these technologies often use secure key exchange protocols (such as Diffie-Hellman or Elliptic Curve Cryptography). When the two devices are connected, a secure key is generated, and the key will not be intercepted by a third party. Such protocols are particularly important in a multi-device environment, which can ensure the security of the key generation and exchange process.

3. Anonymity and authentication

Most kilometre-level wireless communication systems require identity authentication between devices (such as based on device ID or user permissions) to confirm the legitimacy of the identities of the communicating parties. Through the authentication mechanism, each device needs to undergo identity verification when communicating with other devices to prevent unauthorized devices from eavesdropping or intercepting communication data midway.

4. Frequency hopping technology Using a frequency hopping mechanism similar to Bluetooth, the signal switches between different frequency bands, thereby reducing the risk of external interference or eavesdropping. This method can increase the security of data transmission and make it more difficult to be tracked by third parties.

5. Link-layer encryption Implementing encryption at the physical link layer can prevent data from being eavesdropped or tampered with in the communication link. This encryption layer protects data integrity, and even if the transmission process is captured by a third party, it is difficult to parse the valid content.

6. Information signature and integrity check Each transmitted data packet is accompanied by an information signature, and the receiving end verifies the signature to confirm that the data has not been modified. This data integrity check ensures that the data is not tampered with or mistransmitted, and is suitable for data transmission that requires higher security. Kilometre-level network-free communication ensures the confidentiality, integrity and security of data transmission through multi-level encryption and verification measures such as end-to-end encryption, key exchange, and secure frequency hopping. These technologies not only enhance data protection but also improve anti-eavesdropping and anti-interference capabilities, making them suitable for application scenarios with higher security requirements. IV. Application of network-free communication technology in disaster relief scenarios

Application cases of network-free communication technology in disaster relief scenarios include:

Emergency rescue function: Kilometer-level network-free communication technology can be used in rescue scenarios such as extreme weather, earthquakes, and mudslides. This technology allows users to quickly send distress broadcasts to surrounding devices with one click, conveying the individual's trapped location and physical condition, thereby helping rescuers carry out rescue operations more effectively.

UAV emergency communication guarantee: The Wing Loong-2 UAV conducted a successful emergency communication guarantee drill in Muli, Sichuan. The drone is equipped with a variety of equipment, such as public network communication equipment, which can provide emergency communication services without network coverage, ensuring that rescue teams can stay in touch and coordinate rescue operations.

Outdoor adventure and scientific investigation: Kilometer-level network-free communication technology is not only suitable for disaster relief but also for outdoor adventure and scientific investigation. For example, in field adventures or scientific investigations, researchers can use this technology for remote data transmission and sharing to maintain contact between teams.

V. Which brands on the market currently use kilometre-level network-free communication technology?

The brands and products that currently use kilometre-level network-free communication technology on the market mainly include vivo and Xiaomi.

vivo: The vivo X200 series is the world's first device to launch kilometre-level network-free communication technology. This technology is based on Bluetooth and can support point-to-point voice intercom and text transmission up to 1.5 kilometres in an open environment without a network. In addition, the iQOO 13 smartphone is also equipped with this feature and first debuted on the vivo X200 series of mobile phones.

Xiaomi: Xiaomi's Xingchen communication system supports "the industry's first kilometre-level network-free call," which can achieve completely network-free two-way calls within a radius of 3.5 kilometres and supports mesh networking.