Agricultural internet of things terminal access resource dynamic optimization method under 5G network slice

Abstract

The present application relates to a kind of 5G network slice under agricultural IOT terminal access resource dynamic optimization method, belong to 5G agricultural IOT access optimization technical field, including: receiving the access request of agricultural IOT terminal carrying target network slice identifier, read the available resource of target network slice in random access, RRC connection establishment, slice admission and initial uplink authorization stage, and determine current limited access stage according to access procedure;When terminal has completed the pre-access step before current limited stage and corresponding resource is lower than stage resource demand, reserve pre-access result, suspend subsequent service bearer establishment and enter access maintaining state;When corresponding access resource is released in access maintaining time, continue to complete target network slice access based on pre-access result, if corresponding resource is not released when maintaining time expires, then recover the pre-access resource that has been occupied and reconfigure access time window, improve resource connection utilization and terminal access stability.

Description

Technical Field

[0001] This invention relates to the optimization of access resources for agricultural IoT terminals under 5G network slicing, specifically a method for dynamic optimization of access resources for agricultural IoT terminals under 5G network slicing. Background Technology

[0002] In existing technologies, 5G network slice resource management typically allocates resources uniformly based on service demands, network load, or resource pool status to ensure service quality and resource utilization across different slices. A recently published Chinese patent, CN112492687B, discloses an adaptive resource allocation method and system based on wireless network slices. This scheme constructs virtual resource pools with different characteristics, guided by the diverse service needs of each user, connecting users to network slices that meet their service requirements. Resource scheduling is then performed based on the differentiated needs of each network slice. When wireless network conditions or user service demands change, the selection of access network slices and corresponding resource allocation are adjusted according to threshold values ​​to avoid network overload or resource oversupply. The published text of this scheme also points out that network slicing is used to deploy multiple virtual logical networks on a unified underlying physical infrastructure, but existing resource allocation methods still suffer from problems such as difficulty in differentiating allocation based on user service differences, difficulty in timely adjustment of allocation, and insufficient consideration of cached resources.

[0003] For example, Chinese patent CN116546646A discloses a resource allocation method and apparatus for network slicing, published on August 4, 2023, and currently under examination. This scheme statistically analyzes and categorizes resource information from the main resource manager, constructs a resource allocation network and optimizes parameters, obtains allocation target information, performs resource allocation, records allocation information, and optimizes the performance of the main resource manager. The published text states that network slicing needs to be differentiated to meet the demands of high reliability, low latency, and massive connections; reasonable resource allocation is crucial for ensuring the normal operation of network slicing. At the same time, its background section acknowledges that existing methods may still suffer from problems such as low efficiency in allocation strategy formulation, poor stability of user device connections, high redundant data consumption, and insufficient resource allocation efficiency.

[0004] The aforementioned existing technologies can improve resource allocation efficiency from the perspectives of the overall slice, resource pool, user service type, or resource manager. However, their focus is mainly on the overall scheduling and policy generation of slice resources, and they have not fully addressed the phased resource constraints encountered during the access process of agricultural IoT terminals. Agricultural IoT terminals typically exhibit characteristics such as batch access, periodic reporting, low-power maintenance, and bursty service. In the target network slice, stages such as random access, RRC connection establishment, slice admission, and initial uplink authorization may experience insufficient available preambles, insufficient available connections, insufficient admission margin, or insufficient authorization quota, respectively. If access requests are processed solely based on the availability of overall slice resources, terminals that have completed the pre-access steps may be forced to revert due to insufficient resources in subsequent single stages. This leads to repeated occupation of pre-access resources, increased re-access attempts, and difficulty in timely reuse of access resources released within the same network slice. Therefore, it is necessary to propose a dynamic optimization method that can identify the current restricted access stage, retain the pre-access results, and continue access after resource release to adapt to the phased access needs of agricultural IoT terminals under 5G network slices. Summary of the Invention

[0005] The purpose of this invention is to provide a method for dynamically optimizing access resources for agricultural IoT terminals under 5G network slicing, thereby addressing some of the drawbacks and shortcomings pointed out in the background art.

[0006] The present invention adopts the following technical solution to solve the above-mentioned technical problems: The system receives access requests from agricultural IoT terminals carrying the identifier of a target network slice, reads the available number of preambles, available number of connections, admission margin, and authorization limit of the target network slice in the random access, RRC connection establishment, slice admission, and initial uplink authorization stages, and determines the stages that are lower than the corresponding stage requirements as the current restricted access stages according to the terminal access process. When the agricultural IoT terminal has completed the pre-access steps before the current restricted access stage, and the resources corresponding to the current restricted access stage are lower than the stage resource requirements of the access request, the pre-access results formed by the agricultural IoT terminal are retained, the subsequent service bearer establishment is suspended, and the agricultural IoT terminal enters the access hold state. When the access resources corresponding to the resource requirements of the stage are released during the access retention period, the target network slice access is continued based on the previous access results; when the access retention period expires and the access resources corresponding to the resource requirements of the stage are not released, the previous access resources occupied by the agricultural IoT terminal are reclaimed and the access time window is reconfigured.

[0007] Furthermore, after the agricultural IoT terminal enters the access hold state, it marks the completed pre-access steps as the fulfilled access segment and the currently restricted access stage as the access segment to be supplemented; when a new agricultural IoT terminal access request is received, if the access resources it requires correspond to the fulfilled access segment, it is allowed to use the pre-access resources in the target network slice that are not still occupied.

[0008] Furthermore, when retaining the previous access result, the access context that has a calling relationship with continued access is retained according to the current restricted access stage, and the previous access resources that are not called by the authentication status, slice selection result or temporary terminal identifier required for continued access are released; when the current restricted access stage is moved to the next stage, the released previous access resources are removed from the subsequent access resource requirements.

[0009] Furthermore, during the access hold time, if the access resources released by the target network slice in a single instance are all lower than the resource requirements of the stage, the connection status of each released resource is recorded; when the adjacent release interval does not exceed the preset connection interval and the cumulative released resources reach the current limited access stage requirements, the agricultural IoT terminal continues to access based on the previous access results; otherwise, the access hold status is maintained.

[0010] Furthermore, when retaining the access context, the RRC connection context, temporary terminal identifier, and slice selection result that do not require re-authentication are used as the latch context, and the random access response window and initial uplink authorization quota that can be reissued by the target network slice are used as releasable resources; when continuing access, the latch context is invoked first, and the missing parts of the releasable resources are reissued by the target network slice.

[0011] Furthermore, when releasing the pre-access resources, the corresponding agricultural IoT terminal, the current restricted access stage, and the release source are recorded; when the target network slice replenishes subsequent access resources within the access retention time, the released pre-access resources are first restored according to the release source, and the unrestored parts are reconfigured by the target network slice.

[0012] Furthermore, when the currently restricted access phase is shifted to the next stage, the previous access result is re-verified; if the access context still corresponds to the same target network slice and the access hold time has not been exceeded, the previous access result is retained; if the target network slice corresponding to the access context has changed, or the access hold time has been exceeded, the previous access resources that have not been released are reclaimed and the access time window is reconfigured.

[0013] Furthermore, when recording the continuity status of each released resource, the access resources released within the same currently restricted access phase are formed into continuity segments according to the order of release and resource type; when the previous continuity segment has been occupied by other agricultural IoT terminals, or the access resource type corresponding to the next continuity segment does not match the access request, the next continuity segment is stopped from being included in the cumulative released resources.

[0014] Furthermore, while maintaining the access hold state, if the time when the target network slice releases access resources again is earlier than the start time of the reconfigured access time window, the access hold time is extended and the resource release continues to accumulate; if the time when the access resources are released again is later than the start time, the access hold state is ended and access is initiated according to the reconfigured access time window.

[0015] Furthermore, after ceasing to include the subsequent connection segment in the cumulative released resources, the subsequent connection segment is transferred to the bypass access resource pool; when there is a new access request in the target network slice that needs to occupy the access resource type corresponding to the subsequent connection segment, the new access request is allowed to use the bypass access resource pool to complete the corresponding access stage, and it is prohibited from occupying the connection segments already accumulated by the agricultural IoT terminal.

[0016] After receiving an access request from an agricultural IoT terminal carrying a target network slice identifier, this invention reads the available preamble quantity, available connection quantity, admission margin, and authorization quota for the random access, RRC connection establishment, slice admission, and initial uplink authorization stages, respectively. It then determines the currently restricted access stage according to the terminal access process. This allows the reasons for access failure to be refined from insufficient overall slice resources to specific access stages, avoiding general treatment of different types of access resources and improving the accuracy of resource scheduling.

[0017] When an agricultural IoT terminal has completed the preliminary access steps prior to the current restricted stage, and the resources corresponding to the current restricted stage are lower than the stage's resource requirements, this invention retains the established preliminary access results, suspends subsequent service bearer establishment, and puts the terminal into an access hold state. Through this processing method, the terminal does not need to immediately re-execute the complete access process due to insufficient resources in a local stage, reducing the redundant consumption of random access, connection establishment, and related context, and lowering the instantaneous load on the target network slice in scenarios involving batch agricultural terminal access.

[0018] When access resources corresponding to the phased resource requirements are released during the access hold period, this invention continues to complete the target network slice access based on the previous access results; if the corresponding resources are not released before the hold period expires, the occupied previous access resources are reclaimed and the access time window is reconfigured. This creates a clear boundary between continued access and resource reclamation, improving the continuity utilization rate of phased resource releases while avoiding the retention of previous resources due to long-term hold, thus ensuring both stability and resource utilization efficiency in the agricultural IoT terminal access process. Attached Figure Description

[0019] Figure 1 This is a flowchart of the method for dynamically optimizing access resources for agricultural Internet of Things (IoT) terminals according to the present invention.

[0020] Figure 2 This is a stage resource difference verification diagram in Embodiment 1 of the present invention.

[0021] Figure 3 This is a diagram showing the latching and release of the pre-access result in Embodiment 1 of the present invention.

[0022] Figure 4 This is a verification diagram of the duration of acceptance in Embodiment 1 of the present invention.

[0023] Figure 5 This is the cumulative resource verification diagram for the continuation segment in Embodiment 2 of the present invention.

[0024] Figure 6 This is a diagram showing the isolation and reuse of the bypass access resource pool in Embodiment 2 of the present invention.

[0025] Figure 7 This is a verification diagram of the extended access hold time in Embodiment 2 of the present invention. Detailed Implementation

[0026] As attached Figure 1As shown, in one embodiment, the network-side access control unit receives an access request sent by an agricultural IoT terminal, the access request carrying a target network slice identifier. Based on the target network slice identifier, the network-side access control unit reads the available preamble quantity, available connection quantity, admission margin, and authorization limit of the target network slice in the random access phase, RRC connection establishment phase, slice admission phase, and initial uplink authorization phase, respectively, and compares these resource quantities with the phase resource requirements required for the agricultural IoT terminal to complete the corresponding access phase. The phase resource requirements are determined by the terminal access type, service reporting priority, and access phase configuration of the target network slice corresponding to the access request, and are used to characterize the minimum available resource quantity required for the agricultural IoT terminal to complete the corresponding access phase. During the comparison, the network-side access control unit reads the resource status segment by segment according to the order of the terminal access process. When the resource quantity of a certain access phase is lower than the resource requirement of the corresponding phase, the access phase is determined as the currently restricted access phase; when multiple access phases are all lower than the resource requirements of the corresponding phases, the access phase that first shows insufficient resources in the process sequence is taken as the currently restricted access phase, thereby avoiding the direct interruption of the entire access process before the resources of subsequent phases are available.

[0027] After determining the current restricted access phase, the network-side access control unit continues to read the access processing results already completed by the agricultural IoT terminal. If the agricultural IoT terminal has completed the preliminary access steps prior to the current restricted access phase, and the resources corresponding to the current restricted access phase are still lower than the phase resource requirements of the access request, the network-side access control unit does not immediately release all the access results already formed by the agricultural IoT terminal. Instead, it retains the preliminary access results related to continued access, suspends subsequent service bearer establishment, and places the agricultural IoT terminal into an access hold state. The access hold state is used to maintain the preliminary access foundation already established between the agricultural IoT terminal and the target network slice, so that after subsequent resource release, it can continue access from the restricted phase without having to re-occupy preliminary resources such as random access preamble, connection establishment processing, or slice selection processing. The preliminary access results include at least the access context that can prove that the agricultural IoT terminal has completed the preliminary access phase, the target network slice correspondence, and the terminal's temporary access state, and the preliminary access results remain valid only during the access hold period.

[0028] During the access hold period, the network-side access control unit continuously reads the resource release status of the target network slice. The access hold period is pre-configured by the resource scheduling cycle of the target network slice, the service reporting priority of the agricultural IoT terminal, and the effective retention duration of the previous access results, and is constrained during the access hold process by reconfiguring the access time window. When the released access resources correspond to the stage resource requirements and can accommodate the current restricted access stage, the network-side access control unit calls the retained previous access results to continue the access processing of the agricultural IoT terminal to the target network slice and restores the establishment of subsequent service bearers. If the target network slice has not released access resources corresponding to the stage resource requirements after the access hold period expires, the network-side access control unit ends the access hold state of the agricultural IoT terminal, reclaims the previously occupied previous access resources, and reconfigures the access time window for the agricultural IoT terminal, enabling it to re-initiate access within the new access time window, thereby reducing invalid resource occupation and improving the efficiency of the target network slice in accepting access requests from agricultural IoT terminals.

[0029] In one implementation, after an agricultural IoT terminal enters the access hold state, the network-side access control unit no longer treats all completed access processes of the terminal as a single occupied object. Instead, it segments and marks the completed and restricted parts according to the terminal's access process. Specifically, the completed preliminary access steps of the agricultural IoT terminal are marked as fulfilled access segments, and the currently restricted access stage that caused the current access pause is marked as a pending access segment. Both fulfilled access segments and pending access segments are associated with the same target network slice identifier and the same agricultural IoT terminal identifier, and the pending access segment records its corresponding resource type and stage resource requirements. Through this segmentation marking, the target network slice can distinguish between stages that have already formed access results but no longer need to be repeated, and stages that still need to wait for resource release before continuing execution, thereby avoiding the overall locking of resources in the access hold state.

[0030] When the network-side access control unit receives a new access request from an agricultural IoT terminal while the terminal is in access hold mode, it first reads the resource requirements corresponding to the new access request and maps them to the fulfilled access segments and the supplementary access segments. If the access resources required by the new access request correspond to the fulfilled access segments, and there are still unused pre-access resources in the target network slice that have not been occupied by the terminal in access hold mode, then the new access request is allowed to use these pre-access resources to complete the corresponding access stage. This is allowed on the condition that the latching context of the original agricultural IoT terminal is not changed and the resources required for the supplementary access segments are not occupied. Therefore, without disrupting the pre-access results of the original agricultural IoT terminal, the pre-access resources in the target network slice that are not currently occupied can be reused by the new agricultural IoT terminal, reducing idle resource retention caused by access hold mode and improving access resource utilization in scenarios with centralized access of agricultural IoT terminals.

[0031] In one implementation, when retaining the preliminary access results of agricultural IoT terminals, the network-side access control unit does not lock all existing access processing states. Instead, it filters access contexts that have a calling relationship with subsequent access based on the current restricted access stage. The access context supports the agricultural IoT terminal in continuing execution from the current restricted access stage after resource replenishment. Specifically, it can correspond to completed authentication states, slice selection results, temporary terminal identifiers, and RRC connection-related states. For preliminary access resources not called by the authentication states, slice selection results, or temporary terminal identifiers required for continued access, the network-side access control unit releases them to the available resource set of the target network slice, allowing these resources to be used by other access requests. When the current restricted access stage shifts due to changes in target network slice resources, it indicates that some subsequent stages are ready to take over. The network-side access control unit removes previously released preliminary access resources that no longer need to be re-applied for from the subsequent access resource requirements, ensuring that subsequent resource configuration only covers the access stages that still need to be replenished.

[0032] When retaining the access context, the network-side access control unit uses the RRC connection context, temporary terminal identifier, and slice selection result (which do not require re-authentication) as the latching context. The latching context maintains the confirmed access relationship between the agricultural IoT terminal and the target network slice, preventing the agricultural IoT terminal from repeatedly performing authentication, slice selection, and temporary terminal identifier allocation during access recovery. The network-side access control unit also uses the random access response window and initial uplink authorization quota, which can be reissued by the target network slice, as releasable resources, allowing these resources to return to the resource scheduling scope of the target network slice during access retention. When the agricultural IoT terminal continues to access the network, the network-side access control unit prioritizes calling the latching context to confirm that it still corresponds to the original target network slice and the original agricultural IoT terminal. Then, the target network slice reissues the missing parts of the releasable resources, thereby reducing the overhead of repeated access while ensuring the continuity of the access recovery process.

[0033] When releasing prior access resources, the network-side access control unit records the agricultural IoT terminal corresponding to the released resource, the current restricted access stage, and the release source. The release source is used to distinguish whether the resource originates from a random access response window, an initial uplink authorization quota, or other prior resources that can be reissued. After the target network slice replenishes subsequent access resources within the access hold time, the network-side access control unit first restores the released prior access resources according to the release source, enabling the agricultural IoT terminal to continue accessing along the original prior access result. If some released resources cannot be restored due to being occupied by other access requests, or changes in the corresponding scheduling time slot, response window, or authorization object, the target network slice reconfigures these resources and maps the reconfigured resources to the latching context, so that the continued access process can inherit the original access flow.

[0034] When the currently restricted access phase is postponed, the network-side access control unit performs a continuation verification of the previous access result. During the continuation verification, it first reads the target network slice identifier and agricultural IoT terminal identifier corresponding to the access context, and then reads the remaining status of the access hold time. If the access context still corresponds to the same target network slice and the access hold time has not exceeded, the previous access result is retained, and the agricultural IoT terminal is allowed to continue waiting or continuing to access based on the previous access result. If the target network slice corresponding to the access context has changed, or the access hold time has exceeded, it means that the original previous access result can no longer reliably carry over the subsequent access process. The network-side access control unit reclaims the previous access resources that are still occupied but not yet released, and reconfigures the access time window for the agricultural IoT terminal, so that it can re-initiate the target network slice access according to the new access sequence.

[0035] In one implementation, the network-side access control unit continuously monitors the resource release status of the target network slice during the access hold period. If the access resources released by the target network slice are all below the stage resource requirement at each release, the network-side access control unit does not immediately end the access hold state. Instead, it records the resource type, release time, access stage, and continuity status between each released resource and the preceding and following released resources. The continuity status indicates whether the multiple released access resources can jointly take over the same currently restricted access stage. It is marked as continuity when the access stage to which the released resources belong is consistent, the resource type matches, the released resources are not occupied by other agricultural IoT terminals, and the interval between adjacent releases does not exceed a preset continuity interval. When the interval between two adjacent releases does not exceed the preset continuity interval, and the cumulative released resources have reached the current restricted stage resource requirement, the network-side access control unit calls the previous access result already retained by the agricultural IoT terminal, allowing it to continue accessing the target network slice from the current restricted access stage. If the interval between adjacent releases exceeds the preset continuity interval, or the cumulative released resources still do not reach the current restricted stage resource requirement, the access hold state of the agricultural IoT terminal continues to be maintained to wait for subsequent resource replenishment.

[0036] When recording the availability of resources released in each instance, the network-side access control unit forms multiple connection segments based on the release order and resource type of the access resources released within the same currently restricted access phase. Each connection segment corresponds to one released available access resource, and its resource type, release time, availability status, and whether it can still be used for access recovery of agricultural IoT terminals are recorded. If the previous connection segment is already occupied by another agricultural IoT terminal, it means that it can no longer form a continuous access resource with the subsequent connection segment, and the network-side access control unit stops counting the subsequent connection segment into the cumulative released resources. If the previous connection segment is still available, but the access resource type corresponding to the subsequent segment does not match the access request, the network-side access control unit also stops counting the subsequent connection segment into the cumulative released resources, thereby avoiding access recovery failure caused by the incorrect merging of different resource types.

[0037] During the access hold period, the network-side access control unit also reads the time when the target network slice releases access resources again and compares this release time with the start time of the reconfigured access time window. If the time when the target network slice releases access resources again is earlier than the start time of the reconfigured access time window, it indicates that the agricultural IoT terminal still has the opportunity to complete the connection through the access hold period. The network-side access control unit extends the access hold period and continues to include released resources that meet the connection conditions in the cumulative released resources. The extended access hold period does not exceed the effective hold duration of the previous access result and does not change the start order of the reconfigured access time window. If the time when the access resources are released again is later than the start time, it indicates that continuing to maintain the original access state can no longer effectively undertake the subsequent access process. The network-side access control unit ends the access hold period and controls the agricultural IoT terminal to initiate access according to the reconfigured access time window.

[0038] After ceasing the inclusion of subsequent connection segments in the accumulated released resources, the network-side access control unit does not directly discard the subsequent connection segment but transfers it to the bypass access resource pool. The bypass access resource pool stores access resources that cannot form a connection relationship with the connection segments already accumulated by the original agricultural IoT terminal but still possess independent usage conditions. Independent usage conditions are that the subsequent connection segment is not occupied, remains within the schedulable range of the target network slice, and can independently meet the resource type requirements of other access requests in their corresponding access stages. When a new access request exists in the target network slice, and the access resource type required by this new access request is consistent with the access resource type corresponding to the subsequent connection segment, the network-side access control unit allows the new access request to use the bypass access resource pool to complete the corresponding access stage. Simultaneously, the network-side access control unit prohibits the new access request from occupying the connection segments already accumulated by the original agricultural IoT terminal, ensuring that bypass resource utilization does not disrupt the access recovery foundation of the original agricultural IoT terminal, thus balancing access continuity and target network slice resource utilization. Example

[0039] In an agricultural irrigation monitoring system deployed by a certain unit, multiple agricultural IoT terminals initiate access to a target network slice within the same data collection cycle. The network-side access control unit receives an access request sent by an agricultural IoT terminal, the access request carrying the target network slice identifier. Based on the target network slice identifier, the network-side access control unit reads the available preamble quantity in the random access phase, the available connection quantity in the RRC connection establishment phase, the admission margin in the slice admission phase, and the authorization quota in the initial uplink authorization phase of the target network slice, and compares the available resource quantity in each access phase with the phase resource requirements required for the agricultural IoT terminal to complete the corresponding access phase. Figure 2The available resources and resource requirements for the four access phases are presented side by side, with the shaded area of ​​the RRC connection establishment phase highlighting the resource-scarce areas, making the currently restricted access phase easily distinguishable from other resource-sufficient phases.

[0040] To determine the current restricted access phase, the network-side access control unit calculates the resource difference for each phase according to the access process sequence: random access phase, RRC connection establishment phase, slice admission phase, and initial uplink authorization phase.

[0041] in, Indicates the access phase sequence number. Indicates the random access phase. This indicates the RRC connection establishment phase. This indicates the slice admission stage. Indicates the initial uplink authorization phase; Indicates the target network slice in the th... The amount of available resources in each access phase; This indicates that the agricultural IoT terminal has completed its first... The resource requirements for each access phase; Indicates the first Resource differences at each access stage. If A value less than 0 indicates that the available resources are insufficient for this stage; if multiple stages... If all values ​​are less than 0, the network-side access control unit will determine the stage in the access process sequence where resource shortage occurs first as the current restricted access stage.

[0042] When inputting specific data, the target network slice has 36 available preambles in the random access phase, corresponding to a resource requirement of 8. Resources are sufficient during the random access phase. The target network slice has 5 available connections during the RRC connection establishment phase, corresponding to a resource requirement of 7. The RRC connection establishment phase suffers from insufficient resources. The target network slice has an admission margin of 12 slices during the slice admission phase, corresponding to a resource requirement of 3 slices. Resources are sufficient during the slice admission phase. The target network slice has an authorization quota of 18 authorization units in the initial uplink authorization phase, corresponding to a resource requirement of 6 units. Resources were sufficient during the initial uplink authorization phase. Figure 2In the random access phase, slice admission phase, and initial uplink authorization phase, the available resources are shown to be higher than the phase resource requirements. In the RRC connection establishment phase, the number of available connections is shown to be lower than the phase resource requirements. This corresponds to the only negative difference in the calculation results, and causes the network-side access control unit to determine the RRC connection establishment phase as the current restricted access phase.

[0043] After determining that the RRC connection establishment phase is the currently restricted access phase, the network-side access control unit continues to read the access processing results already completed by the agricultural IoT terminal. The agricultural IoT terminal has completed the random access phase and has generated random access completion results, a temporary terminal identifier, a target network slice correspondence, and an RRC connection pending establishment status. Since the number of available connections corresponding to the current restricted access phase is lower than the phase's resource requirements, the network-side access control unit does not release all the previous access results already generated by the agricultural IoT terminal. Instead, it suspends subsequent service bearer establishment and puts the agricultural IoT terminal into an access hold state.

[0044] After the agricultural IoT terminal enters the access hold state, the network-side access control unit marks the completed random access phase as a fulfilled access segment and the RRC connection establishment phase as a pending access segment. The fulfilled access segment indicates that the agricultural IoT terminal has completed the preliminary access steps and does not need to be repeated, while the pending access segment indicates the current restricted access phase that needs to wait for the target network slice to replenish connection resources before continuing. Figure 3 The access process is sequentially expressed to represent the relationships between: random access fulfilled, RRC connection establishment pending completion, slice admission subsequent acceptance, and initial uplink authorization that can be reissued. This ensures that the processing boundaries of the initial access results, the restricted phase, and the subsequent phases correspond within the same access link. Through this segmentation, the target network slice can distinguish between the initial access results and the access resources pending completion, avoiding locking the entire access processing status of the agricultural IoT terminal.

[0045] In the access hold state, if the network-side access control unit receives a new agricultural IoT terminal access request, it first reads the phase resource requirements corresponding to the new access request and maps them to the fulfilled access segments and the pending access segments. If the access resources required by the new access request correspond to the fulfilled access segments, and there are still pre-existing access resources in the target network slice that have not been occupied by the access hold terminal, then the network-side access control unit allows the new access request to use these pre-existing access resources to complete the corresponding access phase. This process does not change the original agricultural IoT terminal's temporary terminal identifier, the target network slice mapping, or the RRC connection pending establishment status, nor does it occupy the connection resources required by the original agricultural IoT terminal's pending access segment.

[0046] When retaining the results of previous access attempts, the network-side access control unit filters access contexts that have a calling relationship with subsequent continued access, based on the currently restricted access stage of RRC connection establishment. These access contexts include the confirmed target network slice identifier, the temporary identifier of the agricultural IoT terminal, the random access completion result, and the RRC connection pending establishment status related to continued access. For previous access resources not called by the temporary terminal identifier, target network slice correspondence, or RRC connection pending establishment status required for continued access, the network-side access control unit releases them to the available resource set of the target network slice, enabling these resources to be used by other access requests.

[0047] When retaining the access context, the network-side access control unit uses the temporary terminal identifier (which does not need to be reassigned), the target network slice correspondence, and the RRC connection pending establishment status as the latching context. This latching context is used to maintain the confirmed access relationship between the agricultural IoT terminal and the target network slice, ensuring that the agricultural IoT terminal does not need to repeat the random access, target network slice identifier confirmation, and temporary terminal identifier allocation processes when access is restored. The network-side access control unit also uses the random access response window and initial uplink authorization quota, which can be reissued by the target network slice, as releasable resources, allowing these resources to return to the resource scheduling scope of the target network slice during the access retention period. Figure 3 The lower-level processing relationship further indicates that the latching context is used to support the continued access of the original agricultural IoT terminal, while the releaseable resources wait for reissue according to the release source within the resource scheduling scope. The two correspond to two different processing directions: retention and release.

[0048] To verify whether the results of the previous access can still be retained, the network-side access control unit calculates the duration that can be maintained:

[0049] in, Indicates the duration for which the service can be maintained; Indicates the access hold time; Indicates the effective duration of the latch context; This represents the duration from the start time of the reconfiguration access time window to the current time. This calculation is used to select the earliest arriving constraint time among the access hold time, latch context effective hold time, and the start time of the reconfiguration access time window. If the target network slice is in If the network-side access control unit replenishes the connection resources required during the RRC connection establishment phase, it will allow the agricultural IoT terminal to continue accessing based on the previously retained access results; if more than [a certain number of] connections are established, the connection will be terminated. If the connection resources are still not replenished, the original previous access results will no longer be retained.

[0050] Access hold time during specific data input The effective holding time of the latched context is 1200ms. Set the access time window start time to 1800ms and reconfigure the time interval between the current time and the start time. If it is 1500ms, then This result indicates that the network-side access control unit retains the latching context of the agricultural IoT terminal for 1200ms, waiting for the target network slice to replenish the connection resources required for the RRC connection establishment phase. Since the current number of available connections during the RRC connection establishment phase is 5, and the corresponding resource requirement for this phase is 7, the target network slice needs to release at least 2 available connections to ensure that the number of available connections during the RRC connection establishment phase meets the resource requirements for that phase. Figure 4 The horizontal timeline displays the three durations: access hold time, latch context validity duration, and reconfiguration time window start constraint. Among them, 1200ms is the first constraint to arrive. The connection resource replenishment time at 900ms is earlier than this constraint, so the time condition for continuing to call the previous access result is met.

[0051] Once the target network slice replenishes the connection resources required for the RRC connection establishment phase within the access hold time, the network-side access control unit first calls the latch context to confirm that the target network slice identifier still corresponds to the original target network slice, the temporary terminal identifier still corresponds to the original agricultural IoT terminal, and the RRC connection pending establishment status has not expired. After confirmation, the network-side access control unit restores the previously released access resources according to the release source. For random access response windows and initial uplink authorization quotas that can be reissued by the target network slice, the network-side access control unit reissues them according to the release source; for those that cannot be restored due to being occupied by other access requests, the target network slice reconfigures them and maps the reconfigured resources to the latch context. Figure 3 The convergence processing box in the middle indicates that after the resources are replenished, the latched context and the releasable resources are no longer processed separately and in isolation, but are called, reissued and matched in the same continued access process.

[0052] When changes in the target network slice resources shift the currently restricted access phase from the RRC connection establishment phase to a subsequent access phase, the network-side access control unit performs a continuation verification of the previous access result. During continuation verification, the network-side access control unit reads the target network slice identifier and the agricultural IoT terminal identifier corresponding to the access context, and reads the remaining status of the access hold time. If the access context still corresponds to the same target network slice and the same agricultural IoT terminal, and the access hold time has not exceeded, the previous access result is retained, and the agricultural IoT terminal is allowed to continue waiting or continuing to access based on the previous access result. If the target network slice corresponding to the access context changes, or the access hold time has exceeded, the network-side access control unit reclaims the previously occupied previous access resources (excluding those already released) and reconfigures the access time window for the agricultural IoT terminal.

[0053] Through the above processing, when the network-side access control unit is temporarily short of resources during the RRC connection establishment phase, it does not immediately interrupt the access process of the agricultural IoT terminal to the target network slice. Instead, it retains the previous access results related to continuing access, releases the previous access resources that can be reissued to the resource scheduling range of the target network slice, and continues to complete the access based on the latching context after the connection resources are replenished. Figure 2 , Figure 3 and Figure 4 The above processing steps are addressed from three levels: resource difference identification, pre-access result diversion processing, and hold duration verification. This ensures a continuous flow between determining the currently restricted access stage, retaining the latched context, re-issuing releasable resources, and establishing conditions for continued access. This approach reduces the overhead of agricultural IoT terminals repeatedly occupying random access preambles, repeatedly confirming target network slice identifiers, and repeatedly allocating temporary terminal identifiers. Simultaneously, it improves the utilization rate of access resources for target network slices in scenarios with concentrated access by agricultural IoT terminals. Example

[0054] In an agricultural greenhouse environmental data acquisition system deployed by a certain organization, multiple temperature and humidity acquisition terminals initiate access under the same target network slice. The network-side access control unit had already put one agricultural IoT terminal into an access hold state during the previous access process. The current restricted access phase for this agricultural IoT terminal is the initial uplink authorization phase, which requires 10 authorized units. During the access hold state, the network-side access control unit does not immediately reclaim the previous access results already established by the agricultural IoT terminal. Instead, it continuously reads the access resources released by the target network slice during the initial uplink authorization phase and records the resource type, release time, access phase, and continuity status between each released resource and those released before and after.

[0055] The target network slice releases 4, 3, 5, and 2 authorized units sequentially during the access hold period. The first, second, and third resource releases all belong to the initial uplink authorization phase, while the fourth resource release belongs to the RRC connection establishment phase. The network-side access control unit forms four connection segments according to the release order and resource type, and records whether each connection segment can still be used for the access recovery of the original agricultural IoT terminal. The release intervals for the first to third times are 180ms and 220ms, respectively, with a preset connection interval of 300ms. Furthermore, the resources released in the third time have not yet been occupied by other agricultural IoT terminals; therefore, the first three connection segments are eligible to merge and take over the same currently restricted access phase. Figure 5 The single release amount and cumulative release amount of the four continuation segments are expressed simultaneously. The regions where the first three segments are located form a continuous cumulative upward path. Although the fourth segment releases resources, the cumulative value does not continue to increase due to resource type mismatch. This corresponds to the screening result of the network-side access control unit for the continuation status.

[0056] To calculate the cumulative released resources that can be included, the network-side access control unit uses the following relationship:

[0057] in, This indicates the cumulative released resources that can be included in the restoration of access to the original agricultural IoT terminals; Indicates the release order of consecutive segments; Indicates the number of contiguous segments that have been read; Indicates the first The amount of access resources released by each continuation segment; Indicates the first The resource type matching status of each continuation segment is set to 1 if the resource type matches the current restricted access stage, and 0 if they do not match. Indicates the first The connectability status of each connection segment is set to 1 if the segment is not occupied by other agricultural IoT terminals and the release interval between it and the previous connectable segment does not exceed a preset connection interval; otherwise, it is set to 0. For the first connection segment, if it is not occupied and the resource type matches, Take 1.

[0058] During specific data input, the first continuation segment releases 4 authorized units, which match the resource type and are not occupied, and are included in the cumulative released resources; the second continuation segment releases 3 authorized units, which match the resource type, and the release interval between it and the first continuation segment is 180ms, which does not exceed the preset continuation interval of 300ms, and are included in the cumulative released resources; the third continuation segment releases 5 authorized units, which match the resource type, and the release interval between it and the second continuation segment is 220ms, which does not exceed the preset continuation interval of 300ms, and is not occupied by other agricultural IoT terminals, and are included in the cumulative released resources. Therefore, we obtain:

[0059] The agricultural IoT terminal requires 10 authorized units during the initial uplink authorization phase. The cumulative released resources from the first three segments amount to 12 authorized units, which meets the current limited access phase requirement. Based on this, the network-side access control unit retrieves the previously saved access results from the agricultural IoT terminal, enabling it to continue accessing the target network slice from the initial uplink authorization phase and resuming subsequent service bearer establishment. Figure 5 The resource requirement line for the current phase is at 10 authorized units, and the cumulative released resources reach 12 authorized units at the third continuation segment, indicating that the initial uplink authorization phase of the original agricultural IoT terminal has obtained sufficient resources to support continued access. Since the cumulative released resources have covered the phase resource requirement, the extra 2 authorized units do not change the fact that the current restricted access phase has been supplemented, and the network-side access control unit can treat them as remaining schedulable resources within the same continuation segment.

[0060] The fourth continuation segment releases two authorized units, but its access phase is the RRC connection establishment phase, and the corresponding access resource type does not match the current restricted initial uplink authorization phase of the agricultural IoT terminal. If the fourth continuation segment is substituted into the above relationship, its resource type matching status... The value is 0, therefore this segment contributes 0 to the cumulative released resources of the original agricultural IoT terminal. The network-side access control unit stops including this subsequent segment in the cumulative released resources of the original agricultural IoT terminal to avoid the incorrect merging of resources from different access stages and to prevent the network-side access control unit from incorrectly resuming the access process if the initial uplink authorized resources are not actually replenished.

[0061] After ceasing to include the fourth connection segment in the cumulative released resources, the network-side access control unit does not directly discard the subsequent connection segment. Instead, it reads its independent usage conditions. If the fourth connection segment is not occupied, is still within the schedulable range of the target network slice, and can independently meet the resource type requirements of other access requests during the RRC connection establishment phase, the network-side access control unit transfers the subsequent connection segment to the bypass access resource pool. When a new agricultural IoT terminal access request exists in the target network slice, and this new access request requires access resources during the RRC connection establishment phase, the network-side access control unit allows the new access request to use the bypass access resource pool to complete the corresponding access phase. Figure 6 The first to third consecutive segments are merged into the cumulative released resource path, and the fourth consecutive segment is introduced into the bypass access resource pool path, so that the original agricultural IoT terminal's continued access path and the bypass reuse path of the new access request are separated from each other.

[0062] When the network-side access control unit allows a new access request to use the bypass access resource pool, it simultaneously prohibits the new access request from occupying the connection segments already accumulated by the original agricultural IoT terminal. The accumulated connection segments include the first, second, and third connection segments, which have already been used to support the continued access of the original agricultural IoT terminal during the initial uplink authorization phase. Figure 6 The isolation restriction path further indicates that the bypass access resource pool only receives connection segments that cannot be merged into the original accumulated released resources, and does not revert to occupy the connection segments already accumulated by the original agricultural IoT terminal. Through this isolation process, the bypass access resource pool only reuses access resources that cannot form a connection relationship with the original agricultural IoT terminal but still have the conditions for independent use, without affecting the original agricultural IoT terminal's access recovery based on the accumulated released resources.

[0063] During the access hold-up period, the network-side access control unit also reads the time when the target network slice releases access resources again and compares this release time with the start time of the reconfigured access time window. To determine whether to extend the access hold-up time, the network-side access control unit uses the following relationship:

[0064] in, This indicates that access resources will be released in advance. This indicates the time elapsed since the start time of the reconfigured access time window was last set. This indicates the time elapsed since the target network slice released its access resources again. When When the value is greater than 0, it indicates that the time for releasing access resources again is earlier than the start time of reconfiguring the access time window, and the original agricultural IoT terminal still has the opportunity to complete the connection by maintaining the access status; when When the value is less than or equal to 0, it means that the time to release access resources again is no earlier than the start time of the reconfiguration access time window, and continuing to maintain the original access state cannot effectively accept subsequent access processes.

[0065] When inputting specific data, if the start time of the access time window is reconfigured to be 900ms from the current time, and the time for releasing access resources is 650ms from the current time, then:

[0066] because If the value is greater than 0, the network-side access control unit confirms that the time when the target network slice releases access resources again is earlier than the start time of the reconfiguration access time window. Therefore, the access hold time is extended, and released resources that meet the connection conditions are continued to be included in the cumulative released resources. Figure 7 Using the 650ms and 900ms time constraints as a reference, the re-release time at 650ms is before the start time of the reconfiguration time window, and the 250ms advance between the two corresponds to the time basis for extending the access hold time. For the fourth segment that has been transferred to the bypass access resource pool, the network-side access control unit will not re-include it in the original agricultural IoT terminal's cumulative released resources due to the extension of the access hold time, unless its resource type re-corresponds to the original agricultural IoT terminal's current restricted access stage and meets the conditions of being unoccupied and the release interval.

[0067] If, during the extended access hold period, the target network slice continues to release access resources matching the initial uplink authorization phase, the network-side access control unit continues to read the release time, resource type, and occupancy status, and compares it with the previous eligible segment for connection. If the release interval does not exceed the preset connection interval and the resource type matches, it continues to be counted in the cumulative released resources; if the release interval exceeds the preset connection interval, or the released resources have been occupied by other agricultural IoT terminals, they are no longer counted in the original agricultural IoT terminal's cumulative released resources, and it is determined whether to transfer them to the bypass access resource pool based on their independent usage conditions.

[0068] If the target network slice releases access resources later than the start time of the reconfigured access time window, the network-side access control unit ends the access hold state and controls the agricultural IoT terminal to re-initiate access according to the reconfigured access time window. In this case, the previously accumulated connection segments of the agricultural IoT terminal are no longer used as the basis for continued access. The network-side access control unit reclaims the access resources it still occupies. Connection segments that have been transferred to the bypass access resource pool and are not used remain within the schedulable range of the target network slice for matching subsequent new agricultural IoT terminal access requests.

[0069] In this way, when the target network slice's resources are insufficient in a single release, the network-side access control unit can effectively accumulate multiple connection segments within the same currently restricted access phase using the available connection status, and promptly stop erroneous accumulation when resource types do not match or segments are occupied. At the same time, it controls the extension or termination of the access hold time by comparing the release time with the start time of the reconfigured access time window, and reuses access resources that cannot serve the original agricultural IoT terminals but can still be used independently using the bypass access resource pool. Figure 5 , Figure 6 and Figure 7 The three processing stages correspond to the cumulative release of resources reaching the stage resource requirements, the isolation and reuse of the bypass access resource pool, and the verification of the extended access retention time. This enables multiple scattered released resources to form a continuous processing relationship between the original terminal connection, bypass reuse, and time constraints, thereby taking into account both the continuity of agricultural IoT terminal access recovery and the utilization rate of target network slice access resources.

Claims

1. A method for dynamically optimizing access resources for agricultural IoT terminals under 5G network slicing, characterized in that, Receive an access request from an agricultural IoT terminal carrying a target network slice identifier, read the available number of preambles, available number of connections, admission margin, and authorization limit of the target network slice in the random access, RRC connection establishment, slice admission, and initial uplink authorization stages, and determine the stage that is lower than the corresponding stage requirement value as the current restricted access stage according to the terminal access process; When the agricultural IoT terminal has completed the pre-access steps before the current restricted access stage, and the resources corresponding to the current restricted access stage are lower than the stage resource requirements of the access request, the pre-access results formed by the agricultural IoT terminal are retained, the subsequent service bearer establishment is suspended, and the agricultural IoT terminal enters the access hold state. When the access resources corresponding to the resource requirements of the stage are released during the access retention period, the target network slice access is continued based on the previous access results; when the access retention period expires and the access resources corresponding to the resource requirements of the stage are not released, the previous access resources occupied by the agricultural IoT terminal are reclaimed and the access time window is reconfigured.

2. The optimization method according to claim 1, characterized in that, After the agricultural IoT terminal enters the access hold state, it marks the completed pre-access steps as the fulfilled access segment and the currently restricted access stage as the access segment to be supplemented. When a new agricultural IoT terminal access request is received, if the access resources it requires correspond to the fulfilled access segment, it is allowed to use the pre-access resources in the target network slice that are not still occupied.

3. The optimization method according to claim 1, characterized in that, Based on the current restricted access phase, retain the access context that has a calling relationship with continued access, and release the previous access resources that are not called by the authentication status, slice selection result or temporary terminal identifier required for continued access; When the currently restricted access phase is shifted to a later stage, the previously released access resources will be removed from the subsequent access resource requirements.

4. The optimization method according to claim 1, characterized in that, If the access resources released by the target network slice are all lower than the resource requirements of the stage in a single release, the connection status of each released resource is recorded; when the interval between adjacent releases does not exceed the preset connection interval and the cumulative released resources reach the current limited access stage requirements, the agricultural IoT terminal continues to access based on the previous access results; otherwise, the access hold status is maintained.

5. The optimization method according to claim 3, characterized in that, When retaining the access context, the RRC connection context, temporary terminal identifier and slice selection result that do not require re-authentication are used as latch context, and the random access response window and initial uplink authorization quota that can be reissued by the target network slice are used as releasable resources. When access continues, the latch context is invoked first, and the missing part of the releasable resource is resent by the target network slice.

6. The optimization method according to claim 3, characterized in that, The data includes the agricultural IoT terminals, the current restricted access phase, and the release source. When the target network slice replenishes subsequent access resources within the access retention period, the previously released access resources are restored according to the release source, and the unrestored portion is reconfigured by the target network slice.

7. The optimization method according to claim 3, characterized in that, When the currently restricted access phase is shifted to the next stage, the previous access result is re-verified. If the access context still corresponds to the same target network slice and the access hold time has not been exceeded, the previous access result is retained. If the target network slice corresponding to the access context changes or the access hold time has been exceeded, the previous access resources that have not been released are reclaimed and the access time window is reconfigured.

8. The optimization method according to claim 4, characterized in that, When recording the continuity status of each released resource, the access resources released within the same currently restricted access phase are grouped into continuity segments according to the order of release and resource type. When the previous continuity segment has been occupied by other agricultural IoT terminals, or the access resource type corresponding to the next continuity segment does not match the access request, the next continuity segment is stopped from being included in the cumulative released resources.

9. The optimization method according to claim 4, characterized in that, If the target network slice releases access resources again before the start time of the reconfigured access time window, the access hold time is extended and resources are released continuously; if the access resources are released again after the start time, the access hold state is terminated and access is initiated according to the reconfigured access time window.

10. The optimization method according to claim 8, characterized in that, The next connection segment is transferred to the bypass access resource pool; when there is a new access request in the target network slice that needs to occupy the access resource type corresponding to the next connection segment, the new access request is allowed to use the bypass access resource pool to complete the corresponding access stage, and it is prohibited from occupying the connection segments already accumulated by the agricultural IoT terminal.

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