A wireless link connection switching method and mobile terminal

Abstract

This invention belongs to the field of wireless communication network technology and relates to a wireless link connection handover method and a mobile terminal. The method includes: acquiring the downlink reference signal of the serving cell and calculating the fading change rate; storing the dedicated random access resources reserved by the target base station; calculating the predicted remaining time of wireless link quality degradation to the demodulation threshold power value based on the fading change rate; determining the average signaling processing cycle; and if the predicted remaining time is less than the average signaling processing cycle, retrieving the dedicated random access resources and sending a non-contention random access preamble to the target base station. This invention separates wireless resource negotiation and physical link handover in the time dimension, converts the real-time reception of handover commands into reliable extraction of locally stored parameters, eliminates the risk of link breakage caused by the mismatch between signaling flow delay and rapid channel fading, enhances the access autonomy of mobile terminals in high-dynamic scenarios, and ensures continuous service transmission.

Description

Technical Field

[0001] This invention relates to the field of wireless communication network technology, and in particular to a wireless link connection switching method and a mobile terminal. Background Technology

[0002] Current mobile communication standard protocols generally adopt a serial signaling interaction logic centrally controlled by the network side. When a mobile terminal communicates in a serving cell, it continuously measures the downlink reference signal quality of the serving cell and neighboring cells. When the signal measurement value meets the preset triggering conditions, the mobile terminal reports a measurement report to the source base station. The source base station completes the handover decision based on the measurement report and completes radio resource reservation and terminal context preparation with the target base station. The source base station sends a radio resource control reconfiguration message containing the target cell access parameters to the mobile terminal. After successfully receiving and demodulating the reconfiguration message, the mobile terminal disconnects the physical connection with the serving cell and initiates a random access procedure to the target cell.

[0003] However, with the widespread adoption of high-dynamic scenarios such as communication along high-speed railways, dense urban building obstruction, and low-altitude aircraft communication, the fading characteristics of wireless channels exhibit a strong nonlinear and precipitous decline trend. In these scenarios, the rate of radio frequency signal degradation objectively far exceeds the feedback flow rate of network layer signaling. This fundamental misalignment between the physical layer evolution trend and the network layer timing mechanism poses a severe performance challenge to existing serial switching logic. Not only does the underlying physical channel, i.e., the hardware carrier of the communication link, have an objective response limit when dealing with nonlinear and rapid fading, the connection switching control method at the network protocol stack software level also has deep-seated defects. For example, Chinese invention patent application CN118828728A discloses a timing advance acquisition method, a bottom-level switching method and device, and a computer-readable storage medium, proposing to implement bottom-level switching. The method involves sending a random access preamble to the candidate cell and receiving a random access response with a pre-timed advance, attempting to obtain the target cell's synchronization parameters in advance to shorten the handover interruption delay. This scheme implicitly relies on idealized underlying objective properties, namely, that the source cell's radio link has absolute stability and ample time margin during the handover preparation phase, to support the complete random access signaling cross-regional round-trip interaction. Analyzing this in the context of highly dynamic evolution scenarios such as high-speed railways or dense buildings, where physical channel deterioration often occurs rapidly at the millisecond level, the absolute delay of signaling flow between base stations is objectively much greater than the critical period of channel collapse. Existing technologies have a fundamental mismatch between basic constraints and actual extreme operating conditions, and are still trapped in the paradox of relying on real-time cross-regional signaling interaction to cope with nonlinear rapid fading mechanisms. Once the channel drops rapidly, the signaling link that has obtained parameters in advance will likely be interrupted, triggering systemic connection reconstruction.

[0004] Therefore, the technical problem to be solved by this invention is how to achieve asynchronous decoupling of resource reservation and link handover by reconstructing the signaling interaction and action execution timing of wireless link switching, thereby improving the reliability of connection migration in high dynamic fading scenarios. Summary of the Invention

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a wireless link connection switching method, comprising the following steps: Step S101: The mobile terminal acquires the downlink reference signal of the serving cell, measures and obtains the reference signal received power sequence within the current sliding time window; Step S102: Based on the reference signal received power sequence, calculate the fading change rate of the reference signal received power of the serving cell in the time domain. The fading change rate is used to characterize the degradation rate of the wireless link quality. Step S103: The mobile terminal receives the handover pre-configuration information sent by the source base station, extracts and stores the dedicated random access resources reserved by the target base station. The dedicated random access resources include a non-contention random access preamble and an access time-frequency resource mask. Step S104: Based on the fading change rate and the currently measured instantaneous reference signal received power, calculate the predicted remaining time when the quality of the wireless link deteriorates to the demodulation threshold power value. The demodulation threshold power value is determined by the minimum received energy required for the mobile terminal to decode the radio resource control reconfiguration message. Step S105: The mobile terminal monitors the closed-loop time from reporting the measurement report to receiving the handover command in the historical handover process, and calculates the average signaling processing cycle. Step S106: Determine whether the predicted remaining duration is less than the average signaling processing cycle; In step S107, if the predicted remaining duration is less than the average signaling processing cycle, before the wireless link quality degrades to the demodulation threshold power value, the mobile terminal retrieves dedicated random access resources and sends a non-contention random access preamble to the target base station to complete the physical link handover.

[0006] Preferably, the process of calculating the fading change rate in step S102 includes: obtaining the first power sample value at the start time and the second power sample value at the end time within the sliding time window; calculating the difference between the first power sample value and the second power sample value, and confirming the ratio of the difference to the length of the sliding time window as the fading change rate.

[0007] Preferably, the process of determining the demodulation threshold power value includes: obtaining the modulation and coding scheme level and the maximum number of retransmissions corresponding to the radio resource control reconfiguration message; determining the minimum average received power required to ensure that the decoding bit error rate of the radio resource control reconfiguration message is less than 1% based on the modulation and coding scheme level and the maximum number of retransmissions, and confirming the minimum average received power as the demodulation threshold power value.

[0008] Preferably, the average signaling processing cycle includes the sum of the transmission delay of the mobile terminal reporting the measurement report, the calculation delay of the source base station making the handover decision, the signaling interaction delay of resource preparation between base stations, and the downlink processing delay of the mobile terminal receiving and parsing the handover command.

[0009] Preferably, after storing the dedicated random access resources in step S103, the method further includes: starting a validity monitoring timer for the dedicated random access resources; if the validity monitoring timer expires and no handover is triggered, the locally stored dedicated random access resources are cleared, and a resource refresh request is sent to the source base station.

[0010] Preferably, the triggering strategy for correcting the measurement report is based on the fading change rate. The process includes: obtaining a baseline trigger threshold and, based on the magnitude of the fading change rate, inversely reducing the trigger duration parameter corresponding to the baseline trigger threshold, so as to report the measurement report in advance in scenarios where the wireless link quality deteriorates rapidly.

[0011] Preferably, before sending the non-contention random access preamble to the target base station in step S107, the method further includes: measuring the signal rise gradient of multiple candidate neighboring cells, whereby the signal rise gradient characterizes the growth rate of the received power of the reference signal in the neighboring cell; selecting the candidate neighboring cell with the largest difference between the signal rise gradient and the fading change rate as the target cell; and determining the target base station corresponding to the target cell.

[0012] Preferably, step S102 further includes: performing second-order differential processing on the received power sequence of the reference signal to calculate the fading acceleration of the wireless link; in step S104, using the fading acceleration to perform nonlinear extrapolation compensation on the predicted remaining duration.

[0013] Preferably, in step S107, while sending the non-contention random access preamble to the target base station, the method further includes: sending a link interruption warning signal through the physical uplink control channel of the serving cell to trigger the source base station to initiate forwarding operations for user plane data.

[0014] A mobile terminal for a wireless link connection switching method includes: a memory for storing computer program instructions; and a processor for executing the computer program instructions.

[0015] The beneficial effects of this invention are: Firstly, in the connection handover of the radio link, by physically separating the radio resource negotiation phase of the target cell from the handover phase of the physical link in the time dimension, the inherent contradiction of the control signaling flow rate lagging behind the nonlinear fading rate of the physical channel in the mobile communication network is resolved. This allows the signaling preparation process of the radio resource control layer to be placed in the safe range before the channel quality of the serving cell falls below the decoding threshold. The downlink command transmission process, which is originally very easy to be interrupted in the rapid fading environment, is transformed into a reliable extraction action of the mobile terminal from the reserved parameters in the local storage space. Thus, without changing the existing air interface interaction architecture, the risk of link breakage caused by the superposition of signaling round-trip absolute delay and channel drop is eliminated.

[0016] Secondly, the fading gradient is introduced as a dynamic prediction quantity to trigger the reserved resources on the network side, so as to achieve accurate prediction of the evolution trend of wireless link quality. Compared with the static judgment method that relies on a single strength threshold, the present invention can dynamically adjust the timing of the reservation request according to the rate of signal degradation, so as to obtain a defense window sufficient to cover the processing delay for the background resource preparation between the source base station and the target base station, and effectively prevent the handover process from being terminated prematurely due to the measurement report being reported too late in high-speed movement or complex obstruction conditions.

[0017] Third, the constructed autonomous transition mechanism achieves deep collaboration between centralized resource management on the network side and distributed access decision-making on the terminal side. While maintaining the data carrying capacity of the serving cell, the mobile terminal obtains autonomous handover authority when the physical link reaches the critical maintenance threshold by silently caching the backup configuration context. This mechanism makes the final access process no longer restricted by the real-time downlink control signaling decoding status. Even in extreme scenarios where the serving cell link collapses instantaneously, the mobile terminal can still initiate random access to the target cell based on the locally pre-stored dedicated random access preamble, ensuring the continuity of service transmission and reducing the frequency of connection reconstruction caused by wireless link failure. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein: Figure 1 This is a flowchart of the wireless link autonomous handover method for fading rate prediction involved in the present invention. Figure 2 This invention relates to a mobile terminal logic module and hardware connection diagram that supports autonomous link handover. Detailed Implementation

[0019] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0020] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0021] Secondly, an embodiment or embodiment referred to herein refers to a specific feature, structure or characteristic that may be included in at least one implementation of the present invention. An embodiment appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0022] This invention is described in detail with reference to the schematic diagrams. When describing the embodiments of this invention, for ease of explanation, the cross-sectional views of the device structure will be partially enlarged without adhering to the general scale. Moreover, the schematic diagrams are only examples and should not limit the scope of protection of this invention. In addition, in actual manufacturing, the three-dimensional spatial dimensions of length, width and depth should be included.

[0023] Furthermore, in the description of this invention, it should be noted that the terms such as "upper," "lower," "inner," and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or component referred to has a specific orientation, or is constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention. In addition, the terms "first," "second," or "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0024] Unless otherwise explicitly specified and limited, the terms installation, connection, and linking in this invention should be interpreted broadly. For example, they can refer to fixed connection, detachable connection, or integrated connection; similarly, they can refer to mechanical connection, electrical connection, or direct connection, or indirect connection through an intermediate medium, or internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0025] Example 1: This example relates to a wireless link connection switching method, applied to a mobile terminal in a wireless communication network. The method includes the following steps: Step S101: The mobile terminal acquires the downlink reference signal of the serving cell, measures and obtains the reference signal received power sequence within the current sliding time window; Step S102: Based on the reference signal received power sequence, calculate the fading change rate of the reference signal received power of the serving cell in the time domain. The fading change rate is used to characterize the degradation rate of the wireless link quality. Step S103: The mobile terminal receives the handover pre-configuration information sent by the source base station, extracts and stores the dedicated random access resources reserved by the target base station. The dedicated random access resources include a non-contention random access preamble and an access time-frequency resource mask. Step S104: Based on the fading change rate and the currently measured instantaneous reference signal received power, calculate the predicted remaining time when the quality of the wireless link deteriorates to the demodulation threshold power value. The demodulation threshold power value is determined by the minimum received energy required for the mobile terminal to decode the radio resource control reconfiguration message. Step S105: The mobile terminal monitors the closed-loop time from reporting the measurement report to receiving the handover command in the historical handover process, and calculates the average signaling processing cycle. Step S106: Determine whether the predicted remaining duration is less than the average signaling processing cycle; In step S107, if the predicted remaining duration is less than the average signaling processing cycle, before the wireless link quality degrades to the demodulation threshold power value, the mobile terminal retrieves dedicated random access resources and sends a non-contention random access preamble to the target base station to complete the physical link handover.

[0026] The process of calculating the fading change rate in step S102 of this embodiment includes: obtaining the first power sample value at the start time and the second power sample value at the end time within the sliding time window; calculating the difference between the first power sample value and the second power sample value, and confirming the ratio of the difference to the length of the sliding time window as the fading change rate.

[0027] The process of determining the demodulation threshold power value described in this embodiment includes: obtaining the modulation and coding scheme level and the maximum number of retransmissions corresponding to the radio resource control reconfiguration message; determining the minimum average received power required to ensure that the decoding bit error rate of the radio resource control reconfiguration message is less than 1% based on the modulation and coding scheme level and the maximum number of retransmissions, and confirming the minimum average received power as the demodulation threshold power value.

[0028] The average signaling processing cycle described in this embodiment includes the sum of the transmission delay of the mobile terminal reporting the measurement report, the calculation delay of the source base station making the handover decision, the signaling interaction delay of resource preparation between base stations, and the downlink processing delay of the mobile terminal receiving and parsing the handover command.

[0029] After storing the dedicated random access resources in step S103 of this embodiment, the method further includes: starting a validity monitoring timer for the dedicated random access resources; if the validity monitoring timer times out and no handover is triggered, the locally stored dedicated random access resources are cleared, and a resource refresh request is sent to the source base station.

[0030] The fading change rate described in this embodiment is used to correct the triggering strategy of the measurement report. The process includes: obtaining a reference triggering threshold, and proportionally reducing the triggering duration parameter corresponding to the reference triggering threshold according to the magnitude of the fading change rate, so as to report the measurement report in advance in the scenario of rapid degradation of wireless link quality.

[0031] In step S107 of this embodiment, before sending the non-contention random access preamble to the target base station, the method further includes: measuring the signal rise gradient of multiple candidate neighboring cells, where the signal rise gradient characterizes the growth rate of the received power of the reference signal in the neighboring cell; selecting the candidate neighboring cell with the largest difference between the signal rise gradient and the fading change rate as the target cell; and determining the target base station corresponding to the target cell.

[0032] In step S102 of this embodiment, the following steps are also included: performing second-order differential processing on the received power sequence of the reference signal to calculate the fading acceleration of the wireless link; in step S104, the fading acceleration is used to perform nonlinear extrapolation compensation on the predicted remaining duration.

[0033] In step S107 of this embodiment, while sending the non-contention random access preamble to the target base station, the method also includes: sending a link interruption warning signal through the physical uplink control channel of the serving cell to trigger the source base station to initiate forwarding operations for user plane data.

[0034] The mobile terminal of the wireless link connection switching method described in this embodiment includes: a memory for storing computer program instructions; and a processor for executing the computer program.

[0035] Example 2: In this example, within a wireless communication network environment along a high-speed railway, a mobile terminal traverses the base station coverage area at a speed of 350 km / h. Due to severe multipath effects and Doppler shift in the geographical environment, the received power of the reference signal of the serving cell exhibits a non-linear drop. The mobile terminal monitors the downlink reference signal of the serving cell within a sliding time window, acquires a continuous sequence of received reference signal power, and calculates the fading change rate, which characterizes the rate of link quality degradation, based on this sequence. The formula for calculating the fading change rate is as follows: ,in, The rate of change of decay, The reference signal received power at the start of the sliding time window. The reference signal received power at the end of the sliding time window. This represents the length of the sliding time window.

[0036] When the mobile terminal determines the fading rate When the preset defense threshold is exceeded and the current instantaneous reference signal received power is above the interaction baseline threshold, the mobile terminal sends a reservation request message carrying the target cell identifier to the source base station, enabling the network side to complete resource negotiation in advance. This reservation request message, at the signaling level, manifests as an enhanced measurement report or a specifically defined RRC connection reconfiguration request. The mobile terminal sends this message through the uplink DCCH channel, which includes the physical cell identifier (PCI) of the target cell and a request type indicator bit, explicitly indicating that this message is not a traditional event-triggered report, but rather a request for advance allocation of dedicated random access resources. After receiving the reservation request message, the source base station performs a resource preparation process with the target base station through the Xn or S1 interface between base stations. The dedicated control channel sends handover pre-configuration information, including a dedicated random access preamble, to the mobile terminal, thereby completing asynchronous resource reservation. The mobile terminal receives and parses the backup configuration context sent by the source base station, extracts the dedicated random access preamble and the cell radio network temporary identifier contained therein, and writes them into a specific cache area of ​​the local memory, while maintaining the current data communication bearer with the serving cell. As the mobile terminal continues to move at high speed, when the instantaneous reference signal received power of the serving cell drops below the preset critical execution threshold, the mobile terminal disconnects the physical link with the current serving cell, retrieves the backup configuration context pre-stored in the local memory, and initiates a random access procedure to the target cell according to the dedicated random access preamble indicated by the context.

[0037] Example 3: In this example, under the simulated nonlinear fading channel condition at a mobile speed of 350 km / h, the experiment constructs a basic data stream using a high-fidelity network simulation platform. The physical layer signal characteristics of this data stream are generated based on the fast fading random process defined in the 3GPP standard. On this basis, additive white Gaussian noise with a signal-to-noise ratio of 20 dB and Doppler frequency shift fluctuations are actively superimposed on the downlink reference signal sequence to simulate radio frequency interference and physical channel distortion in a high-speed mobile environment. The experiment targets a sliding time window. The value of this parameter is used for decision analysis. The setting of this parameter is limited by the technical trade-off between signal sampling frequency and link quality prediction accuracy. A short-period sliding time window improves the response speed to sudden fading but is easily affected by transient thermal noise, leading to false triggering. A long-period sliding time window smooths out noise interference but introduces prediction lag. This experiment determines the value based on the Nyquist sampling theorem and the rate of change of the fast fading envelope. The demodulation threshold power value is set at 40ms, and is determined based on the modulation and coding scheme level and the maximum retransmission count. The received level is -112.4 dBm, to maintain the decoding error rate of radio resource control reconfiguration messages below a preset target at this received level.

[0038] After the experiment started, the processor collected reference signal received power sampling points of the serving cell. In a certain fast fading interval, the observed original reference signal received power sequence decreased from -92.5dBm at the beginning to -104.8dBm 40ms later. At this time, the fading change rate was calculated according to the formula. The value is 0.3075 dB / ms, and the mobile terminal is based on the fading rate. And based on the currently measured instantaneous reference signal received power, calculate the wireless link quality degradation to the demodulation threshold power value. Predicted remaining time Simultaneously, the closed-loop time from reporting the measurement report to receiving the handover command in the historical handover process is monitored, and the average signaling processing cycle is calculated. The time is 65.2ms, when the judgment is made. Less than When the mobile terminal's instantaneous reference signal received power is still above the interaction baseline threshold of -102.3dBm, it sends a reservation request message to the source base station and obtains a cached backup configuration context containing the target cell access parameters. This addresses the physical phenomenon of shortened channel coherence time caused by Doppler frequency shift in high dynamic scenarios, eliminates the spatiotemporal scale matching error between the statistical window and channel transients, and the processor executes a nonlinear extrapolation compensation procedure. The input terminal obtains the continuously sampled reference signal received power sequence within the sliding time window. The processor calls a digital low-pass filter to remove fast fading feature components with a period of less than 2ms from the sequence, retaining the shadow fading feature components. Here, 2ms is used as the filter period setting to filter out surface fast fading caused by multipath effects. Although the 40ms sliding time window is shorter than that of ultra-long period shadow fading, due to envelope fluctuations and thermal noise in the RF front end, the drastic changes in spatial location in the high-speed railway (above 350km / h) or millimeter-wave narrow-beam scenarios targeted by this invention cause shadow fading or occlusion effects to show a significant monotonic decreasing trend within tens of milliseconds. The local average power point sequence obtained by 2ms filtering can accurately fit the evolution gradient of signal degradation within the 40ms window, thus enabling accurate prediction of subsequent degradation trends in the early stages of shadow fading evolution. The processor extracts the power sample values ​​at the start, middle, and end times of the filtered sequence at equal intervals and calculates the wireless link fading acceleration. The specific mathematical relationship is as follows: ,in, This represents the fading acceleration, characterizing the second-order rate of change of the channel's nonlinear degradation. , , The extracted power sample values ​​are sequentially represented at the start time, the middle time, and the end time. This represents the time interval between adjacent sampling moments. After obtaining the fading acceleration, the processor extends the linear prediction based on a single fading gradient to a second-order evolution model following the basic kinematic equations, and solves the quadratic equations. After determining the compensation duration, the processor extracts the positive real roots of the equation as the output prediction of the remaining duration and updates it to the local register. Subsequent timing logic is then executed. In actual calculations, since the Reference Signal Received Power (RSRP) uses dBm as the unit of measurement, its fading along the spatial path typically exhibits nonlinear characteristics. In the high-dynamic scenario of this invention, due to the sliding time window... With a short period of 40ms, within this surface time window, the logarithmic power fading trend of the physical channel can be approximated as a piecewise quadratic function evolution. Therefore, using fading acceleration... With fading gradient The constructed quadratic equation is essentially a second-order Taylor expansion approximation of the evolution trend of the logarithmic domain signal. The predicted remaining time is obtained by solving this equation. It can accurately detect when the signal drops to the demodulation threshold power value. The critical time point is determined, thereby mapping the rapid nonlinear deterioration of the physical layer signal into a deterministic execution cycle in the time domain, providing a physically statistically significant input for subsequent autonomous handover decisions.

[0039] When the instantaneous reference signal received power dropped to -110.5 dBm, the experimental group of this invention retrieved the backup configuration context from the local buffer and initiated random access. In contrast, the control group, which did not employ this invention's scheme, triggered the traditional measurement report reporting process at the same location. Because the physical link quality had deteriorated below the decoding threshold of the radio resource control reconfiguration message due to nonlinear fading, the control group could not receive the handover command and experienced radio link failure. The random access success rate of the experimental group was 98.6%, while that of the control group was 72.3%. This comparative data confirms the synergistic effect between the fading change rate identification and remaining duration prediction mechanisms, transforming the handover triggering from passively waiting for instructions to autonomous scheduling based on channel evolution laws, by adjusting the demodulation threshold power value. Boundary tests were conducted using the bias amount and it was found that when When the setting is too high, the system prematurely determines the remaining time target, leading to redundant pre-configured signaling interactions under channel fluctuations. When the setting is too low, the triggering time of the reservation request message lags behind the physical channel deterioration rate, causing the demodulation success rate of the backup configuration context to drop below 85%. The test data shows a balance between handover success rate and signaling overhead in the range of -112.0dBm to -113.0dBm, thus providing a definite physical basis for the parameter range defined by this method.

[0040] Example 4: This example combines Figures 1 to 2 A description of a wireless link connection switching method and a mobile terminal, such as... Figure 1 As shown, step S101 obtains the downlink reference signal of the serving cell and measures the reference signal received power sequence within the current sliding time window. In step S102, the fading rate of the serving cell's reference signal received power in the time domain is calculated based on the reference signal received power sequence to characterize the rate of degradation of the radio link quality. In step S103, the mobile terminal receives the handover pre-configuration information sent by the source base station and extracts the dedicated random access resources reserved by the target base station, including the non-contention random access preamble and the access time-frequency resource mask. Then, step S104 calculates the radio link quality based on the fading rate and the currently measured instantaneous reference signal received power. The predicted remaining time until the link quality deteriorates to the demodulation threshold power value is determined by the minimum received energy required for the mobile terminal to decode the radio resource control reconfiguration message. The average signaling processing cycle is calculated by monitoring the closed-loop time from reporting the measurement report to receiving the handover command in the historical handover process in step S105. Then, in step S106, it is determined whether the predicted remaining time is less than the average signaling processing cycle. If the determination condition is met, step S107 is executed. Before the radio link quality deteriorates to the demodulation threshold power value, the mobile terminal retrieves the dedicated random access resource and sends a non-contention random access preamble to the target base station to complete the physical link handover.

[0041] like Figure 2 As shown, in the hardware and logic architecture of the mobile terminal, its radio frequency receiving link is responsible for capturing the downlink reference signal and sending it to the physical layer register. The physical layer register generates the reference signal received power sequence and inputs it to the fading change rate calculation module in the processor's computing core. The processor's computing core specifically includes the fading change rate calculation module, the timing prediction engine, and the autonomous handover decision logic. The fading change rate calculation module is used to process the reference signal received power sequence, the timing prediction engine is used to evaluate and predict the remaining duration, and the autonomous handover decision logic is used to compare the average signaling processing cycle and generate control commands. At the same time, the memory unit is responsible for managing the backup configuration context (including dedicated random access resources) and running the resource validity monitoring timer. When the handover logic is triggered, the media access control unit (MAC) retrieves the non-contention random access preamble from the memory unit and transmits the access signal to the target base station through the radio frequency transmission link.

[0042] Example 5: In this example, within a wireless communication network environment comprised of densely built-up urban buildings, a mobile terminal encounters shadow fading during movement. The downlink signal power of the serving cell experiences a non-linear drop depending on the location of the obstruction. If the defense threshold is set too high, the mobile terminal cannot pre-store the backup configuration context before the link is interrupted. If the defense threshold is set too low, redundant reservation request messages will be generated under normal signal fluctuations, increasing the processor load and consuming air interface signaling resources. The mobile terminal utilizes the processor to run a prediction duration calculation algorithm, which includes: reading the current instantaneous reference signal received power from the physical layer register. and the preset demodulation threshold power value Retrieve the calculated rate of change of decay. Determine the remaining predicted duration based on the linear fading model. The specific calculation formula is as follows: ,in, To predict the remaining duration, The current instantaneous reference signal received power, The minimum receive energy threshold required for a mobile terminal to decode Radio Resource Control reconfiguration messages. This represents the rate of change in fading.

[0043] To determine the specific value of the defense threshold, the mobile terminal initiates a parameter calibration procedure, which includes: First, statistically analyzing the number of historical wireless link failures and the corresponding historical fading gradient sequence within a preset time period; Second, using the wireless link failure rate as a cost function, searching for the minimum gradient value that makes the failure rate lower than 1.5% through a one-dimensional optimization method; Third, determining this minimum gradient value as the defense threshold. In this deployment example, through statistical analysis of 1000 handover samples, the defense threshold was calibrated to 0.38 dB / ms. Simultaneously, the interaction baseline threshold was set to -105.0 dBm based on the receiver's sensitivity specifications to ensure that the reservation request message achieves a demodulation signal-to-noise ratio gain of no less than 10 dB at the physical layer. When the mobile terminal determines... Three consecutive sampling periods shorter than the average signaling processing period At this time, the processor sends a trigger signal to the radio resource control layer to retrieve the cached backup configuration context in local memory. This context is stored in memory as an array and contains the physical cell identifier of the target cell, the dedicated random access preamble index, and the corresponding timing advance deviation value. The mobile terminal completes the hardware preloading of the target cell access parameters before the serving cell reference signal received power drops to -112.0dBm.

[0044] As the power of the received reference signal drops below the modulation threshold, the processor shuts down the radio frequency transmission link with the source base station according to the interrupt vector table instruction, and simultaneously drives the media access control unit to retrieve the dedicated random access preamble in memory. It then initiates an access request at the first available time-frequency resource location of the physical random access channel. The success rate of the mobile terminal's handover processing increases from 75.4% to 99.1%, and the service interruption duration caused by a single handover is stabilized within 20ms, meeting the transmission requirements of high-definition video services in dynamic fading environments.

[0045] Example 6: In this example, in a communication network deployment scenario allocated to the millimeter-wave frequency band, the mobile terminal determines the average signaling processing cycle through an initialization calibration procedure. During the test period, the processor recorded the signaling interaction delay for 50 handover processes. The signaling interaction delay is the time difference between the start time when the mobile terminal sends a measurement report at the physical layer and the end time when it receives the radio resource control reconfiguration message from the source base station at the physical layer. The processor sorted the collected delay samples and removed fluctuation points that deviated from the sample median by more than 20%. It then calculated a weighted moving average for the remaining samples to obtain the average signaling processing cycle under the current network topology. The value is 68.5ms. The processor writes this value to the system parameter area of ​​non-volatile memory as the basis for determining the remaining prediction time. The benchmark for whether the triggering conditions are met.

[0046] In scenarios where the mobile terminal transitions from an urban area to a suburban environment with fewer obstructions, a dynamic adaptation procedure for the defense threshold is initiated. The processor updates the offset factor of the defense threshold based on the measured background noise power spectral density and Doppler spread width. If an increase in the coherence time of the physical channel and a decrease in the variance of shadow fading fluctuations are detected, the processor adjusts the defense threshold from 0.38 dB / ms to 0.32 dB / ms. This delays the transmission of the reservation request message under conditions of reduced channel degradation rate, reduces pre-configuration signaling interactions caused by random channel fluctuations, and ensures the deterministic nature of the dynamic adjustment process. The processor executes an environmental feature quantization mapping procedure to update the defense threshold. The baseband processing unit calculates the autocorrelation function of the received signal to obtain the Doppler spread width, calculates the average value of the received energy within a preset number of idle resource blocks, and obtains the background noise power spectral density. The processor calculates the offset factor based on the measured environmental features, with the specific relationship as follows: ,in, Indicates the offset factor. Indicates the Doppler extension width. Represents the background noise power spectral density. This is the Doppler sensitivity coefficient. This is the noise sensitivity coefficient. and The specific values ​​are determined by the offline calibration process at the front-end hardware level. The test platform feeds the terminal with a sequence of known Doppler frequency shift and additive noise normalized fading channel models, records the terminal's critical defense threshold for maintaining a preset handover success rate, and uses the least squares method to fit a fixed constant value which is burned into non-volatile memory. During the online operation phase, the processor obtains the system initialization baseline defense threshold and the calculated offset factor. Perform a summation operation, extract the summation result to cover the defense threshold within the current system parameter area, and complete the boundary adaptive update.

[0047] Example 7: In this example, in a specific wireless network deployment scenario, the mobile terminal determines the demodulation threshold power value through the system initialization calibration procedure. The processor reads the thermal noise power level of the current RF receiver link in a zero-input state. Combining this with the preset modulation and coding strategy level and the target decoding block error rate constant, it retrieves the link-level receiver sensitivity curve stored in memory to calculate the minimum power level required for successful decoding of the radio resource control reconfiguration message at the physical layer. This minimum power level is then used as the demodulation threshold power value. Write to the system running parameters area.

[0048] In high-dynamic scenarios involving obstruction by specific building clusters, the mobile terminal determines a defense threshold through offline sampling analysis. The processor acquires the downlink reference signal received power observation sequence at different moving speeds, calculates the first-order difference mean of the observation sequence at a preset sampling step size, and statistically analyzes the signal fading gradient distribution within 200ms before the wireless link failure event. The minimum gradient value in this distribution that covers more than 95% of successful handover samples is selected as the defense threshold to ensure the predicted remaining time between the triggering time of the reservation request message and the physical channel breakage time. Greater than the average signaling processing cycle .

[0049] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the protection scope of the present invention.

Claims

1. A wireless link connection switching method, applied to a mobile terminal in a wireless communication network, characterized in that, The method includes the following steps: Step S101: The mobile terminal acquires the downlink reference signal of the serving cell, measures and obtains the reference signal received power sequence within the current sliding time window; Step S102: Based on the reference signal received power sequence, calculate the fading change rate of the reference signal received power of the serving cell in the time domain. The fading change rate is used to characterize the degradation rate of the wireless link quality. Step S103: The mobile terminal receives the handover pre-configuration information sent by the source base station, extracts and stores the dedicated random access resources reserved by the target base station. The dedicated random access resources include a non-contention random access preamble and an access time-frequency resource mask. Step S104: Based on the fading change rate and the currently measured instantaneous reference signal received power, calculate the predicted remaining time when the quality of the wireless link deteriorates to the demodulation threshold power value. The demodulation threshold power value is determined by the minimum received energy required for the mobile terminal to decode the radio resource control reconfiguration message. Step S105: The mobile terminal monitors the closed-loop time from reporting the measurement report to receiving the handover command in the historical handover process, and calculates the average signaling processing cycle. Step S106: Determine whether the predicted remaining duration is less than the average signaling processing cycle; In step S107, if the predicted remaining duration is less than the average signaling processing cycle, before the wireless link quality degrades to the demodulation threshold power value, the mobile terminal retrieves dedicated random access resources and sends a non-contention random access preamble to the target base station to complete the physical link handover.

2. The wireless link connection switching method according to claim 1, characterized in that, The process of calculating the fading change rate in step S102 includes: obtaining the first power sample value at the start time and the second power sample value at the end time within the sliding time window; calculating the difference between the first power sample value and the second power sample value, and confirming the ratio of the difference to the length of the sliding time window as the fading change rate.

3. The wireless link connection switching method according to claim 1, characterized in that, The process of determining the demodulation threshold power value includes: obtaining the modulation and coding scheme level and the maximum number of retransmissions corresponding to the radio resource control reconfiguration message; based on the modulation and coding scheme level and the maximum number of retransmissions, determining the minimum average received power required to ensure that the decoding bit error rate of the radio resource control reconfiguration message is less than 1%, and confirming the minimum average received power as the demodulation threshold power value.

4. The wireless link connection switching method according to claim 1, characterized in that, The average signaling processing cycle includes the sum of the transmission delay of the mobile terminal reporting the measurement report, the calculation delay of the source base station making the handover decision, the signaling interaction delay of resource preparation between base stations, and the downlink processing delay of the mobile terminal receiving and parsing the handover command.

5. The wireless link connection switching method according to claim 1, characterized in that, After storing the dedicated random access resources in step S103, the method further includes: starting a validity monitoring timer for the dedicated random access resources; if the validity monitoring timer expires and no handover is triggered, the locally stored dedicated random access resources are cleared and a resource refresh request is sent to the source base station.

6. The wireless link connection switching method according to claim 1, characterized in that, The fading change rate is used to correct the triggering strategy of the measurement report. The process includes: obtaining the baseline trigger threshold, and proportionally reducing the trigger duration parameter corresponding to the baseline trigger threshold according to the magnitude of the fading change rate, so as to report the measurement report in advance in the scenario of rapid degradation of wireless link quality.

7. The wireless link connection switching method according to claim 1, characterized in that, Before sending the non-contention random access preamble to the target base station in step S107, the method further includes: measuring the signal rise gradient of multiple candidate neighboring cells, where the signal rise gradient characterizes the growth rate of the received power of the reference signal in the neighboring cell; selecting the candidate neighboring cell with the largest difference between the signal rise gradient and the fading change rate as the target cell; and determining the target base station corresponding to the target cell.

8. The wireless link connection switching method according to claim 1, characterized in that, Step S102 further includes: performing second-order differential processing on the received power sequence of the reference signal to calculate the fading acceleration of the wireless link; in step S104, using the fading acceleration to perform nonlinear extrapolation compensation on the predicted remaining duration.

9. A wireless link connection switching method according to claim 1, characterized in that, In step S107, while sending the non-contention random access preamble to the target base station, the method also includes: sending a link interruption warning signal through the physical uplink control channel of the serving cell to trigger the source base station to initiate forwarding operations for user plane data.

10. A mobile terminal with a wireless link connection switching method, characterized in that, Includes: memory, used to store computer program instructions; A processor for executing computer program instructions to implement the steps of the method as described in claim 1.

Images