The difference between 2.4G technology and standard Bluetooth protocol

The most popular wireless low-latency transmission application nowadays is 2.4G technology, which is used in devices such as a mouse, remote controllers, and audio transmitters. 2.4G technology has a more flexible usage and transmission behavior, including data confidentiality mechanisms, which can be freely designed by developers. However, for developers, they must have sufficient development experience to implement the entire application. In addition to the 2.4G device itself, they also need to bind an additional 2.4G transceiver. Once the 2.4G transceiver is lost, the 2.4G device becomes useless and cannot effectively utilize the Bluetooth module on a computer, tablet, or mobile phone.

In contrast, the standard Bluetooth protocol has defined most of the functions required for applications. If developers can directly use the protocols established by the association, they can effectively reduce the manpower and time required for product development. Therefore, devices that use standard Bluetooth private protocols have the advantages of lower latency and being easier to implement than application functions.

Report Rate and Dots per Inch for mouse applications

In mouse applications, the Report Rate and Dots per Inch are two important parameters that have a significant impact on user experience. The Report Rate determines the speed at which the mouse sends data and reacts to user input. A higher Report Rate means faster response times, resulting in less delay and drag. On the other hand, the Dots per Inch determines the distance the mouse moves on the screen, with one inch of movement corresponding to a certain number of pixels on the screen. A higher Dots per Inch means the mouse moves a greater distance on the screen, but a higher sensitivity is not always better, as it may not be suitable for precise operations.

A standard office mouse usually has a Report Rate of 125Hz, which is sufficient for general computer use. However, for applications that require low-latency and precise controls, such as a gaming mouse and controllers, a minimum Report Rate of 500Hz is required. Today's 2.4G gaming mouse have a Report Rate of up to 1kHz, which translates to a transmission delay of only 1 millisecond per data packet. In contrast, the minimum period of the standard Bluetooth Low Energy (BLE) protocol is 7.5 milliseconds, resulting in a Report Rate of approximately 133Hz. Although this is sufficient for office mouse, it is still too slow for gaming mouse, making the technology of the Report Rate a critical issue in low-latency applications.

In the example shown below (Figure 1 for 1kHz Report Rate and Figure 2 for 125Hz Report Rate), when moving at the same speed, the mouse with a lower Report Rate has a greater distance between its movement trajectory, resulting in heavier drag.

Figure 1: diagram of 1kHz report rate

Figure 2: diagram of 125Hz report rate

Realtek Bluetooth with ultra-low latency of 1.25msec LE effectively reduces development costs

To achieve high report rates and low latency comparable to 2.4G, Realtek has introduced a 1.25msec Bluetooth technology with performance close to 2.4G, achieving a high report rate of 800Hz. In addition, devices using this technology can directly use the transmission, encryption, frequency hopping, and applications defined in the standard Bluetooth protocol, effectively reducing development manpower and time. At the same moving speed, as shown in Figure 3, the mouse trajectory with an 800Hz report rate is already close to 1kHz.

It is worth mentioning that devices supporting this BLE proprietary protocol does not only have to use Realtek's own dongle to achieve ultra-low latency but can also be paired with Bluetooth modules on computers, tablets, or mobile phones and automatically switch to the standard Bluetooth protocol, even if the dongle is lost, the original function will not be lost.

Figure 3: diagram of 800Hz report rate

Realtek Bluetooth BEE series supports development

Excellent low latency can bring users a good user experience. The RTL8762D and RTL8762E of the Realtek Bluetooth BEE series can support the ultra-low latency 1.25msec Bluetooth proprietary protocol, which saves development costs and time for customers and provides excellent qualities to the products.