Wireless USB bridging system

Abstract

The application discloses a wireless USB bridging system and belongs to the field of USB bus bridging. The system comprises a first bridging device, a second bridging device and a wireless communication link connecting the first bridging device and the second bridging device. The application effectively solves the problems of easy disconnection of USB session, frequent re-enumeration and the like under the scenes of wireless link fluctuation, congestion and short-time interruption by means of protocol layer transparent bridging, control plane priority scheduling, link quality sensing and state caching mechanism, and improves the connection stability. Relying on dynamic priority scheduling and safety bandwidth calculation, the high-priority control data transmission such as enumeration, configuration and heartbeat is preferentially guaranteed, and the bulk data is intelligently degraded, so that the response speed and bandwidth utilization are balanced. The state caching on the host side can quickly respond to the enumeration and control request, reduces the wireless round-trip delay and optimizes the interactive fluency. The dual-link separation bearing architecture is adopted, the control plane is stable and alive, the data plane is high-speed transmission, and the system anti-interference ability and reliability are enhanced.

Description

Technical Field

[0001] This invention relates to the field of USB bus bridging, and more particularly to a wireless USB bridging system. Background Technology

[0002] USB connectivity offers advantages such as plug-and-play functionality, a wide range of device types, and a mature driver ecosystem. However, traditional USB connections rely on physical cables. With the increasing number of mobile terminals, VR / motion-sensing devices, debugging equipment, laboratory equipment, rack maintenance equipment, and industrial control peripherals, users are often limited by factors such as cable length, ease of plugging and unplugging, interface wear, wiring complexity, and power supply drop during temporary connections, cross-location connections, or equipment maintenance.

[0003] While wireless communication technologies such as Wi-Fi, Bluetooth, Starlink, UWB, and WiGig can transmit ordinary data, ordinary wireless transmission cannot inherently enable a computer host to recognize a remote USB device, nor can it automatically maintain USB enumeration, endpoint status, transmission type, and composite device interface relationships. Existing wireless mice, Bluetooth headsets, and wireless screen mirroring products are mostly wireless solutions for a single device category or a single business scenario; USB-over-IP or remote USB hubs are more geared towards local area network remote sharing and typically do not focus on USB session persistence under wireless link fluctuations or dynamic multi-protocol scheduling.

[0004] Furthermore, the D+ / D- lines in a USB cable are not ordinary data lines that can be directly split and forwarded. Instead, they are high-speed signals with strict electrical timing, differential impedance, and host polling mechanisms. Simply converting the physical signals into wireless data packets is insufficient to meet nanosecond-level timing requirements. Therefore, a system is needed that performs bridging, state synchronization, and data scheduling at the protocol layer to address the USB session continuity issue under fluctuating wireless link environments. Summary of the Invention

[0005] Purpose of the invention: The invention provides a wireless USB bridging system that solves the problems mentioned in the background art.

[0006] Technical Solution: To solve the above-mentioned technical problems, according to one aspect of the present invention, more specifically, a wireless USB bridging system includes a first bridging device, a second bridging device, and a wireless communication link connecting the first bridging device and the second bridging device. The overall architecture adopts a five-layer technical system: L1 USB session retention layer, L2 USB transmission type identification layer, L3 service scenario identification layer, L4 wireless link quality awareness layer, and L5 multi-link transmission layer.

[0007] (a) First bridging device (computer side / host side) The first bridging device is located on the USB host side and connects to the USB host via a USB interface. It internally includes the following modules: USB Device Emulation Module: Based on real USB device information synchronized from the second bridging device, this module presents one or more virtual USB devices or virtual USB composite devices to the USB host, enabling the host to perform local enumeration. It supports emulating USB devices or USB composite devices and can simultaneously present multiple interfaces (such as HID, MTP, ADB, etc.).

[0008] State caching module: Used to cache at least one of the following: device descriptor, configuration descriptor, interface descriptor, endpoint descriptor, device state, and the result of the most recent control request for the real USB device. Its functions include: quickly responding to host enumeration and control requests, reducing the impact of wireless round-trip latency; maintaining the representation of virtual devices during soft disconnections; and synchronizing state differences after the link is restored.

[0009] The transmission classification module classifies transmission requests between the USB host and USB devices, identifying at least Control, Bulk, Interrupt, and Isochronous transmissions. Furthermore, this module identifies at least one of the following service scenarios based on USB interface class, endpoint type, transmission direction, packet size, periodicity, or vendor protocol identifier: HID, MTP, ADB, USB network sharing, USB audio, and USB video.

[0010] Link detection module: Used to collect real-time quality parameters of the wireless communication link, including at least one of RSSI, SNR, MCS, channel bandwidth, number of spatial streams, packet loss rate, retransmission rate, RTT, jitter, and real-time effective throughput. It dynamically calculates the secure available transmission budget based on the link quality parameters. The specific calculation method is: `safe_bw = measured_goodput × dynamic_margin`, where the dynamic security factor `dynamic_margin` varies with the link stability: 0.85~0.90 for a stable link, 0.70~0.80 for a normal link, 0.50~0.70 for fluctuating links, and only the control plane and heartbeat channel are retained when the link is in danger.

[0011] The priority scheduling module prioritizes data related to USB enumeration, configuration, state synchronization, endpoint control, or session keep-alive, giving it a higher priority than batch data. Internally, it maintains a priority queue, with priorities from highest to lowest: P0 control plane (enumeration, descriptors, endpoint status, configuration requests, heartbeats, error recovery), P1 event plane (HID, status notifications, ADB control commands), P2 real-time streams (audio, compressed video), P3 batch data (MTP, USB flash drive read / write, ADB push / pull), and P4 non-critical background streams (log synchronization, background scanning). When wireless link congestion or quality degradation occurs, high-priority data transmission is prioritized, and lower-priority queues are preempted when necessary. Batch transmissions or low-priority data are subject to rate limiting, queuing, pausing, retransmission, or degradation. For isochronous transmissions, bandwidth reservation, buffer adjustment, bitrate reduction, frame dropping, or frame skipping strategies are employed.

[0012] Soft disconnection recovery module: Used to implement the soft disconnection state machine. This state machine includes: normal connection → slight link degradation (rate limiting Bulk / increasing control plane reservation) → continued link deterioration (freezing low-priority endpoints / retaining Control+Heartbeat) → short interruption (virtual device softly keeps online / suspends data plane) → link recovery (state resynchronization / queue restoration / partial reset if necessary) → restoration of normal connection. When a short-term anomaly occurs in the wireless link, the virtual USB device is kept online to the USB host, and low-priority endpoint data is frozen or delayed; after the link recovers, state resynchronization, queue restoration, and error cleanup are performed with the second bridging device.

[0013] Security authentication module: Used to complete device binding, key negotiation, whitelist or encryption authentication with the second bridging device, establish a trusted connection, and prevent unauthorized access.

[0014] Multi-link management module (optional): When multiple wireless links are configured, it is responsible for allocating different types of data on different links and performing switching or fallback when the link quality changes.

[0015] (ii) Second bridging device (equipment end / external device side) The second bridging device is located on the USB device side and connects to one or more physical USB devices via a USB interface. It internally includes the following modules: USB Host Control Module: Used to enumerate and control connected real USB devices, obtaining their device descriptors, configuration descriptors, interface descriptors, endpoint descriptors, and current status. It assumes the role of USB Host, performing low-level USB communication with the real devices.

[0016] State synchronization module: Used to synchronize the acquired real USB device information to the first bridging device, and to cooperate with the first bridging device to complete state resynchronization after the link is restored. The synchronized content includes at least descriptor information, configuration status, interface information, endpoint information, and device status.

[0017] Security authentication module: used to complete pairing and encrypted authentication with the first bridging device.

[0018] Multi-link management module (optional): Corresponding to the multi-link management module of the first bridging device, it is responsible for sending and receiving data on multiple wireless links.

[0019] External power supply interface: Used to supply power to the connected USB device through an external power supply, local battery or independent power supply interface, so as to separate the data carrying and power supply path and avoid the voltage drop and wiring complexity caused by long USB cables.

[0020] (III) Wireless Communication Link The wireless communication link is a point-to-point or multi-link wireless connection, carrying USB session data between the first bridging device and the second bridging device after encapsulation, classification, scheduling, and recovery processing. It can be implemented based on one or more wireless communication protocols such as Wi-Fi (including 2.4GHz, 5GHz, 6GHz), Bluetooth, Starflash, UWB, and WiGig. In a multi-link configuration, at least two wireless links can be set up, one for carrying control plane or session keep-alive data (e.g., a stable 2.4GHz low-frequency link), and the other for carrying bulk data or high-speed data (e.g., a 5GHz / 6GHz high-speed link). When the quality of the high-speed data link degrades, the system switches or maintains control plane data on the low-speed stable link and reduces or suspends high-speed data plane transmission.

[0021] Beneficial effects: This invention effectively addresses issues such as USB session disconnection, frequent re-enumeration, and control request blocking in scenarios involving wireless link fluctuations, congestion, and short-term interruptions by employing protocol-layer transparent bridging, control plane priority scheduling, link quality awareness, and state caching mechanisms, thereby improving connection stability. Relying on dynamic priority scheduling and secure bandwidth calculation, it prioritizes the transmission of high-priority control data such as enumeration, configuration, and heartbeat, while intelligently downgrading batch data, balancing response speed and bandwidth utilization. Host-side state caching enables rapid response to enumeration and control requests, reducing wireless round-trip latency and optimizing interaction smoothness. A dual-link separation architecture ensures stable control plane keep-alive and high-speed data plane transmission, enhancing system anti-interference capabilities and reliability. Separation of data and power supply paths solves the problem of voltage drop in long-distance USB cables, stably driving high-power peripherals. The system is compatible with various USB hosts and peripherals, allowing for plug-and-play operation without modifying existing devices. Furthermore, secure authentication and encrypted transmission establish a trusted connection, preventing unauthorized access and data eavesdropping, comprehensively improving the practicality, stability, and security of wireless USB bridging. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram of the priority queue scheduling of the present invention; Figure 3 This is a schematic diagram of the soft disconnection state machine of the present invention; Figure 4 This is a schematic diagram of a dual-link bearer embodiment of the present invention. Detailed Implementation

[0023] To make the technical solution of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] Example 1: Single Wireless Link Infrastructure In this embodiment, the wireless communication link is a single wireless link (e.g., 2.4GHz or 5GHz Wi-Fi). The first bridging device and the second bridging device are connected point-to-point.

[0025] The work process is as follows: 1. The USB host control module of the second bridging device enumerates the connected real USB devices (such as a composite device consisting of a USB flash drive and an HID keyboard) and obtains complete descriptor information, configuration, interface and endpoint information.

[0026] 2. The status synchronization module synchronizes this information to the first bridging device via a wireless link.

[0027] 3. The state cache module of the first bridging device stores this information; the USB device emulation module presents a virtual USB composite device to the USB host based on this information, and the host completes local enumeration.

[0028] 4. When the host initiates data transmission, the transmission classification module identifies the transmission type (Control, Bulk, Interrupt, etc.). For Control transmissions (such as obtaining device status), the priority scheduling module places them in the P0 queue and sends them immediately. For Bulk transmissions (such as reading and writing files on a USB flash drive), they are placed in the P3 queue.

[0029] 5. The link detection module monitors parameters such as RSSI, packet loss rate, and RTT in real time to calculate the secure available bandwidth. For example, if the measured effective throughput is 30Mbps and the dynamic security factor is set to 0.7, the secure bandwidth is 21Mbps. The scheduling module limits the bulk traffic to not exceeding this budget.

[0030] 6. When the wireless link experiences a brief interruption due to interference, the soft disconnection recovery module is activated: the first bridging device maintains the virtual device online status and does not report the disconnection to the host; the P3 and P4 queues are frozen, and only the P0 heartbeat channel is retained. After the interruption is recovered, both ends resynchronize their states (compare endpoint states, configuration versions, etc.), restore the frozen queues, and resume transmission from the point of interruption.

[0031] 7. Comparative experiments show that, compared with the ordinary forwarding scheme, this embodiment reduces the control request timeout rate by more than 80% and the number of re-enumerations by 90% in the context of link fluctuation.

[0032] Example 2: Dual-link control / data separation architecture In this embodiment, the wireless communication link includes two independent wireless links: one is a 2.4GHz low-speed stable link (for the control plane), and the other is a 5GHz high-speed data link (for bulk data).

[0033] Both the first and second bridging devices include a multi-link management module. The system allocates P0 / P1 data such as Control transmission, heartbeat, and status synchronization to the 2.4GHz link; and allocates P2 / P3 data such as Bulk and Isochronous to the 5GHz link.

[0034] The link detection module monitors the quality of both links separately. When the packet loss rate of the 5GHz link increases due to distance or obstruction, the multi-link management module automatically keeps newly generated control plane data on the 2.4GHz link while reducing or suspending batch transmissions on the 5GHz link. If the 5GHz link is completely interrupted, the system continues to maintain the session through the 2.4GHz link and attempts to rebuild the 5GHz link.

[0035] The advantage of this architecture is that even with frequent fluctuations in the high-speed link, the control plane remains stable, and the device will not go offline. Experiments show that even with a 5GHz link interruption lasting up to 5 seconds, the USB session can still be maintained, and data transmission can continue after recovery.

[0036] Example 3: Business Scenario Identification and Template Scheduling In this embodiment, the transmission classification module further integrates the business scenario recognition function.

[0037] When the USB interface class is detected as 0x03 (HID), the endpoint type is interrupt transmission, and the cycle is short, it is identified as an HID keyboard and mouse scenario, and the template is called: extremely low bandwidth but low latency takes priority, and control plane synchronization takes priority.

[0038] When an interface class of 0xFF (vendor-specific) is detected and it exhibits "adb" related protocol characteristics, it is identified as an ADB debugging scenario. Scheduling template: Shell / control commands have high priority, push / pull file streams have low priority. When the link deteriorates, the file transfer rate is limited to 20% of the safety budget, but real-time response to adb shell commands is guaranteed.

[0039] When UAC or UVC class and isochronous endpoints are detected, it is identified as an audio / video scene. Template: Reserve a fixed bandwidth (e.g., 1Mbps) to allow for reduced bitrate or frame drops during congestion, but prohibit infinite retransmissions to ensure real-time performance.

[0040] When MTP / PTP protocol is detected, it is identified as a file transfer scenario. The following template is invoked: rate limiting and queuing are allowed; batch transfers are paused when the link deteriorates; and resume downloads after recovery are supported.

[0041] This embodiment enables the system to perform more intelligent scheduling based on business semantics, thereby improving the user experience.

[0042] Example 4: Detailed Explanation of State Caching and Soft Disconnection Recovery This embodiment focuses on describing the details of the cooperation between the state caching module and the soft disconnection recovery module.

[0043] During normal operation, the state caching module not only caches static descriptors, but also dynamically records the most recent endpoint state, current configuration value, alternative settings, and the result of the most recent successfully responded control request.

[0044] When the USB host initiates a standard device request (such as Get_Descriptor, Get_Configuration), the USB device emulation module of the first bridging device preferentially retrieves the data response from its local cache, without waiting for a round trip via the wireless link. Testing has shown that this reduces the average latency of the enumeration phase from approximately 5-10 ms wireless RTT to the microsecond level.

[0045] When the wireless link is interrupted, the soft disconnection recovery module starts a configurable protection timer (e.g., 3 seconds). During the timer, the host sees the virtual device as still online, and any requests to the device are temporarily buffered by the first bridging device or a "busy" status is returned (but not a device not found status). After the link is restored, the soft disconnection recovery module performs incremental synchronization with the state synchronization module of the second bridging device: comparing the buffered endpoint states and incomplete transaction lists at both ends, synchronizing only the differences. After synchronization is complete, the recovery queue is processed. If the timer times out, it is determined to be a long-term disconnection, and the host is notified that the device has been unplugged.

[0046] Example 5: Separation of Power Supply and Data In this embodiment, the second bridging device includes an external power supply interface (e.g., a USB-C PD input or a DC 5V socket) for connecting an external power adapter or battery. The connected USB device (such as a high-capacity external hard drive) is powered by this external power source, while the USB data signal interacts with the actual device through the USB host control module of the second bridging device and is then transmitted back to the host via a wireless link. This way, even if the remote device has high power consumption, it will not malfunction due to voltage drop over long USB cables, and there is no need to provide high-power output on the computer side. This invention achieves complete separation of data transmission and power supply paths.

[0047] Example 6: Secure Pairing and Encryption To prevent unauthorized bridging devices from accessing the network, both the first and second bridging devices include a security authentication module. During initial pairing, the user presses the pairing buttons on both ends, and the modules negotiate a key using WPA3 or a similar protocol to establish an encrypted connection. Afterward, both ends exchange and store whitelist identifiers for each other's devices. Any new device attempting to connect must go through the same authentication process. All wirelessly transmitted USB data (including control commands and device content) is encrypted to prevent eavesdropping and tampering.

[0048] Other implementation methods This invention is not limited to the embodiments described above. For example, the wireless link can employ low-latency technologies such as Starlink or UWB; there can be more than two links, one of which is dedicated to heartbeat keep-alive; the service scenario template can be user-defined or updated in the cloud. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention.

[0049] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A wireless USB bridging system, characterized in that, include: The first bridging device is located on the USB host side and is connected to the USB host via a USB interface; The second bridging device is located on the USB device side and connects to one or more real USB devices via a USB interface. A wireless communication link connects the first bridging device and the second bridging device; The second bridging device includes: USB host control module: used to enumerate and control the real USB device, and obtain the descriptor information, configuration status, interface information and endpoint information of the real USB device; Status synchronization module: used to synchronize the acquired information of the real USB device to the first bridging device; The first bridging device includes: USB device emulation module: used to present a virtual USB device or a virtual USB composite device to the USB host based on synchronized information; State caching module: used to cache at least one of the following: descriptor information, configuration information, interface information, endpoint information, and device state of the actual USB device; Transmission Classification Module: Used to classify transmission requests between the USB host and USB devices, identifying at least one or more of the following: control transmissions, bulk transmissions, interrupt transmissions, and isochronous transmissions. Link detection module: used to collect real-time quality parameters of the wireless communication link and dynamically calculate the secure and available transmission budget based on the link quality parameters; Priority scheduling module: It is used to set the priority of data related to USB enumeration, configuration, state synchronization, endpoint control or session keep-alive to higher priority than batch data, and to prioritize the transmission of high-priority data when wireless link congestion or quality degradation occurs, and to perform rate limiting, queuing, pausing, retransmission or degradation processing on batch transmission or low-priority data. Soft disconnection recovery module: used to maintain the online status of the virtual USB device when a short-term abnormality occurs in the wireless link, and to resynchronize the status with the second bridging device after the link is restored.

2. The wireless USB bridging system according to claim 1, characterized in that, The link quality parameters include at least one of RSSI, SNR, MCS, channel bandwidth, number of spatial streams, packet loss rate, retransmission rate, RTT, jitter, and real-time effective throughput; the secure available transmission budget is obtained by multiplying the measured effective throughput by a dynamic security factor, which varies dynamically with the link stability: 0.85~0.90 when the link is stable, 0.70~0.80 when the link is generally stable, 0.50~0.70 when the link fluctuates, and only the control plane and heartbeat channel are retained when the link is in danger.

3. The wireless USB bridging system according to claim 1, characterized in that, The high-priority data includes at least one of device descriptor requests, configuration requests, endpoint status requests, control transfers, heartbeat packets, and status synchronization data.

4. The wireless USB bridging system according to claim 1, characterized in that, The transmission classification module is also used to identify at least one of the following service scenarios based on USB interface class, endpoint type, transmission direction, data packet size, periodicity, or vendor protocol identifier: HID, MTP, ADB, USB network sharing, USB audio, and USB video. The priority scheduling module calls the scheduling template corresponding to the service scenario for scheduling, wherein: when the service scenario is an ADB debugging scenario, ADB control commands are set to high priority and ADB file transfer is set to low priority; when the service scenario is an MTP file transfer scenario, batch transmission is paused when the link deteriorates, and resumed after recovery.

5. The wireless USB bridging system according to claim 1, characterized in that, For batch transmission, the priority scheduling module adopts at least one of the following degradation strategies: rate limiting, fragmentation, queuing, breakpoint resumption, pause recovery, or congestion window adjustment; for isochronous transmission, the adopted strategies include at least one of the following: bandwidth reservation, buffer adjustment, bit rate reduction, frame dropping, or frame skipping.

6. The wireless USB bridging system according to claim 1, characterized in that, The soft disconnection recovery module is configured to: when the wireless link is temporarily abnormal, keep the virtual USB device visible to the USB host and freeze or delay low-priority endpoint data; after the link is restored, perform state resynchronization and queue recovery.

7. The wireless USB bridging system according to claim 1, characterized in that, The wireless communication link includes at least two wireless links, one of which is used to carry control plane or session keep-alive data, and the other is used to carry batch data or high-speed data; the low-speed stable link is a 2.4GHz wireless link, and the high-speed data link is a 5GHz or 6GHz wireless link; when the quality of the high-speed data link degrades, the priority scheduling module will switch or keep the control plane data on the low-speed stable link, and reduce or suspend the high-speed data plane transmission.

8. The wireless USB bridging system according to claim 1, characterized in that, The first bridging device and the second bridging device also include a security authentication module for establishing a trusted connection through device binding, key negotiation, whitelisting, or encryption authentication.

9. The wireless USB bridging system according to claim 1, characterized in that, The second bridging device also includes an external power supply interface for independently supplying power to the connected USB device via an external power source or a local battery, thereby separating the data transmission path from the power supply path.

10. The wireless USB bridging system according to claim 1, characterized in that, The state caching module is also used to cache the result of the most recent control request and to perform incremental state synchronization with the second bridging device when the soft disconnection is restored. The priority scheduling module maintains a priority queue, which includes, from high to low priority, the following queues: control plane queue, event plane queue, real-time stream queue, batch data queue, and non-critical background stream queue.

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