Decryption procedure for a trunking group call and user setup

Abstract

A decryption method for a trunking group call applied to a user equipment, comprising: monitoring (S1) group call data in a current cell and obtaining a hyperframe number of the current cell, which is a first hyperframe number, from a base station of the current cell; when switching from the current cell to a target cell, obtaining (S2) the group call data from a base station of the target cell and obtaining an interval range of a hyperframe number of the target cell according to the first hyperframe number, wherein the hyperframe number of the target cell is a second hyperframe number; Traversing (S3) the second hyperframe number according to the interval range of the second hyperframe number and obtaining a plaintext according to the second hyperframe number and comparing the group call session information contained in the plaintext with the group call data of the current cell; and if a comparison result matches, after successful decryption by traversing the second hyperframe, performing (S4) a decryption operation according to the second hyperframe number, wherein the step of switching from the current cell to a target cell comprises: initiating and establishing (S21) a group call session such that when establishing a trunking service transmission by the base station, a field for transmitting encryption parameters of the group call data is newly added and the encryption parameters are stored; Switching (S22) from the current cell to the target cell, re-adding or multiplexing a signal for transmitting a session key identifier of the current cell or for directly transmitting a key of the current cell; and Receiving (S23) encrypted group call data of the target cell; and wherein the step of performing a decryption operation according to the second hyperframe number comprises: Performing (S24) the decryption operation with the encrypted group call data of the target cell according to the second hyperframe number.

Description

[TECHNICAL FIELD]

[0001] The present invention relates to the field of mobile communications, and more particularly to a decryption method for a trunking group call and a user equipment. [BACKGROUND OF THE INVENTION]

[0002] After initiating a multicast session, cells at a base station establish a session and apply encryption parameters to transmit a call code stream. The encryption parameters configured for each cell may be inconsistent, resulting in the encryption contexts of each cell becoming unsynchronized. When a user device switches from a current cell to a neighboring target cell, the encryption parameters and state of each cell must be obtained before decryption can be performed, resulting in a time delay and disruption of the multicast service.

[0003] CN 1 04 684 030 A discloses a method for implementing the synchronization of security parameters in a cluster system.

[0004] US 2013 / 0165129 A1 discloses methods for transmitting a communication session between companion devices. [SUMMARY OF THE INVENTION]

[0005] The technical problem to be solved by the present invention is to provide a decryption method for a trunked group call and a user equipment that reduce the time delay of the interruption of the group call service and improve the user experience.

[0006] To solve the above technical problem, a technical solution used by the present invention comprises providing a trunking group call decryption method applied to a user equipment, comprising: monitoring group call data in a current cell and obtaining a hyperframe number (HFN) of the current cell, which is a first hyperframe number, from a base station of the current cell; when switching from the current cell to a target cell, obtaining the group call data from a base station of the target cell and obtaining an interval range of a hyperframe number of the target cell according to the first hyperframe number, wherein the hyperframe number of the target cell is a second hyperframe number; Traversing the second hyperframe number according to the interval range of the second hyperframe number and obtaining a plaintext according to the second hyperframe number and comparing the group call session information contained in the plaintext with the group call data of the current cell; and if a comparison result matches, after successful decryption by traversing the second hyperframe, performing a decryption operation according to the second hyperframe number.

[0007] In the step of obtaining the group call data from a base station of the target cell and obtaining an interval range of a hyperframe number of the target cell according to the first hyperframe number, the second hyperframe number is within an interval range of [XM, X+N], where X is the first hyperframe number and both M and N are natural numbers; and wherein the step of traversing the second hyperframe number according to the interval range of the second hyperframe number and obtaining a plaintext according to the second hyperframe number comprises: Changing a value of the second hyperframe number within the interval range of [XM, X+N], and performing a decryption operation according to the changed value of the second hyperframe number to obtain the plaintext.

[0008] In the step of performing a decryption operation according to the second hyperframe number after successful decryption by traversing the second hyperframe number, an order of traversing the second hyperframe number is as follows: X→X−1→X+1→X−2→X+2…→X−M…→X+N.

[0009] If the group call data is configured as PDCP SN 5Bit and a packet interval is 20 ms, M and N are set to 2.

[0010] The step of switching from the current to a target cell includes: Initiating and establishing a group call session such that, when establishing a trunking service transmission by the base station, a field for transmitting encryption parameters of the group call data is newly added and the encryption parameters are stored; Switching from the current cell to the target cell, re-adding or multiplexing a signal to transmit a session key identifier of the current cell or to directly transmit a key of the current cell; and Receiving encrypted group call data from the target cell, and the step of performing a decryption operation according to the second hyperframe number comprises: Performing the decryption operation on the encrypted group call data of the target cell according to the second hyperframe number.

[0011] Before the step of receiving encrypted group call data of the target cell, the method further comprises: Sending the session key identifier of the current cell or the key of the current cell to the base station of the target cell and comparing the session key identifier of the current cell or the key of the current cell with a key of the target cell by the base station of the target cell; if consistent, receiving the encrypted group call data of the target cell from the base station of the target cell; and if inconsistent, sending the target cell key to the current cell base station while receiving encrypted target cell multicast data from the target cell base station, and sending the target cell key from the current cell base station to the user equipment.

[0012] The step of switching from the current cell to a target cell includes: Initiating and establishing a group call session such that when establishing a trunking service transmission by the base station, a field for transmitting encryption parameters of the group call data is newly added and the encryption parameters are stored; and Receiving encrypted group call data of the target cell from the base station of the target cell.

[0013] To solve the above technical problem, a technical solution applied by the present invention includes: providing a user facility comprising: a monitoring module configured to monitor group call data of the user equipment in a current cell and to receive from a base station of the current cell a hyperframe number of the current cell that is a first hyperframe number; a transceiver module configured to receive, when switching the user equipment from the current cell to a target cell, the group call data from a base station of the target cell and to obtain an interval range of a hyperframe number of the target cell according to the first hyperframe number, wherein the hyperframe number of the target cell is a second hyperframe number; and a processing module connected to the monitoring module and the transmitting / receiving module and configured to traverse the second hyperframe number according to the interval range of the second hyperframe number, obtain a plaintext according to the second hyperframe number, and compare multicast session information contained in the plaintext with the multicast data of the current cell; and if a comparison result is consistent, after successful decryption by traversing the second hyperframe number, perform a decryption operation according to the second hyperframe number.

[0014] The second hyperframe number lies within an interval range of [XM, X+N], where X is the first hyperframe number and both M and N are natural numbers; and a value of the second hyperframe number is changed within the interval range of [XM, X+N], and a decryption operation is performed by the processing module according to the changed value of the second hyperframe number to obtain the plaintext.

[0015] An order for the processing module to traverse the second hyperframe number is as follows: X→X−1→X+1→X−2→X+2…→X−M…→X+N.

[0016] If the group call data is configured as PDCP SN 5Bit and a packet interval is 20 ms, M and N are set to 2.

[0017] The user equipment further comprises a setup module and a key module, wherein when the user equipment switches from the current cell to the target cell, the setup module initiates and establishes a group call session, so that when a trunking service transmission is established by the base station, a field for transmitting encryption parameters of the group call data is newly added and the encryption parameters are stored; when switching from the current cell to the target cell, a signal is re-added or multiplexed to transmit a session key identifier of the current cell or to directly transmit a key of the current cell; the transceiver module receives encrypted group call data from the target cell; and the processing module performs the decryption process on the encrypted group call data of the target cell according to the second hyperframe number.

[0018] The key module further transmits the current cell session key identifier or the current cell key to the target cell base station, and the target cell base station compares the current cell session key identifier or the current cell key with a target cell key; if consistent, the transceiver module receives the target cell encrypted multicast data from the target cell base station; and if inconsistent, the target cell key is transmitted to the current cell base station while receiving the target cell encrypted multicast data from the target cell base station, and the current cell base station transmits the target cell key to the user equipment.

[0019] The user device further comprises a device module, wherein the setup module initiates and establishes a group call session when switching the user setup from the current cell to the target cell, so that when establishing a trunking service transmission by the base station, a field for transmitting encryption parameters of the group call data is newly added and the encryption parameters are stored; and the transceiver module receives encrypted group call data of the target cell from the base station of the target cell.

[0020] To solve the above technical problem, a technical solution used by the present invention comprises providing a user device comprising: a memory configured to store program instructions; a processor configured to monitor group call data of the user equipment in a current cell and to receive from a base station of the current cell a hyperframe number of the current cell that is a first hyperframe number; wherein the processor is further configured to receive, upon switching the user equipment from the current cell to a target cell, the group call data from a base station of the target cell and to obtain an interval range of a hyperframe number of the target cell according to the first hyperframe number, wherein the hyperframe number of the target cell is a second hyperframe number; and a controller configured to traverse the second hyperframe number according to the interval range of the second hyperframe number, obtain a plaintext according to the second hyperframe number, and compare multicast session information contained in the plaintext with the multicast data of the current cell; and, if a comparison result is consistent, perform a decryption operation according to the second hyperframe number after successful decryption by traversing the second hyperframe number.

[0021] The second hyperframe number lies within an interval range of [XM, X+N], where X is the first hyperframe number and both M and N are natural numbers; and wherein a value of the second hyperframe number is changed within the interval range of [XM, X+N], and a decryption operation is performed by the processing module according to the changed value of the second hyperframe number to obtain the plaintext.

[0022] An order for the processing module to traverse the second hyperframe number is as follows: X→X−1→X+1→X−2→X+2…→X−M…→X+N; If the group call data is configured as PDCP SN 5Bit and a packet interval is 20 ms, M and N are set to 2.

[0023] When switching the user equipment from the current cell to the target cell, the processor initiates and establishes a group call session, so that when the base station establishes a trunking service transmission, a field for transmitting encryption parameters of the group call data is newly added and the encryption parameters are stored; and

[0024] When switching the user equipment from the current cell to the destination cell, a signal is re-added or multiplexed by the processor to transmit a session key identifier of the current cell or directly transmit a key of the current cell; wherein the processor receives encrypted multicast data of the destination cell; and the controller performs the decryption operation on the encrypted group call data of the target cell according to the second hyperframe number.

[0025] The processor further sends the current cell session key identifier or the current cell key to the base station of the target cell, and the base station of the target cell compares the current cell session key identifier or the current cell key with a key of the target cell; and, if consistent, the processor receives the encrypted target cell multicast data from the base station of the target cell; and if inconsistent, the processor sends the target cell key to the current cell base station while receiving encrypted multicast cell data from the target cell base station, and the current cell base station sends the target cell key to the user equipment.

[0026] When the user equipment switches to the target cell, the processor initiates and establishes a group call session so that when the base station establishes a trunking service transmission, a field for transmitting encryption parameters of the group call data is newly added and the encryption parameters are stored; and the processor receives encrypted group call data of the target cell from the base station of the target cell.

[0027] The present invention has the following advantageous effects: unlike the prior art, when switching the user equipment from the current cell to the destination cell, the trunked group call decryption method according to the present invention derives an appropriate interval range of the second hyperframe number of the destination cell according to the first hyperframe number of the user equipment in the current cell, traverses the second hyperframe number according to the interval range of the second hyperframe number, performs traversal decryption according to the second hyperframe number, and performs decryption operation according to the second hyperframe number after successful decryption, so that the time delay of interruption of a group call service decreases and the user experience is improved. [BRIEF DESCRIPTION OF THE DRAWINGS] Fig. 1 shows a flowchart of a decryption method for a trunked group call according to the present invention; Fig. Figure 2 shows a flowchart of certain steps of a first embodiment in Fig. 1; Fig. 3 shows a flowchart of certain steps in Fig. 2; Fig. 4 shows a flowchart of certain steps of a second embodiment in Fig. 1; Fig. 5 shows a block diagram of a user equipment based on the trunking group call decryption method according to the present invention; and Fig. 6 shows a hardware structure diagram of the user equipment based on the trunking group call decryption method according to the present invention. [DETAILED DESCRIPTION]

[0028] The technical solutions of the various exemplary embodiments of the present invention will be described clearly and completely below with reference to the accompanying drawings of the embodiments of the invention. Note that, unless conflicting, the following embodiments and features of the embodiments may be combined with each other.

[0029] Fig. Figure 1 shows a flowchart of a trunked group call decryption method according to the present invention. The method disclosed in the embodiment is applied to a user device, and the method includes the following steps.

[0030] In step S1, group call data in a current cell is monitored, and a hyperframe number of the current cell, which is a first hyperframe number, is obtained from a base station of the current cell.

[0031] Each base station performs multicast data transmission with a plurality of cells. According to the embodiment, the current cell and the target cell can perform multicast data transmission with the same base station or with two different base stations. After initiating a multicast session, each cell under the base station establishes the session approximately synchronously and transmits multicast code streams using encryption parameters to ensure that the number and content of the multicast code streams are the same in different cells, so that the hyperframe numbers (HFN) of a Packet Data Convergence Protocol (PDCP) layer are approximately the same.

[0032] In step S2, when switching from the current cell to a target cell, the group call data is obtained from a base station of the target cell, and an interval range of a hyperframe number of the target cell is obtained according to the first hyperframe number, the hyperframe number of the target cell being a second hyperframe number.

[0033] The second hyperframe number lies within an interval range of [XM, X+N], where X is the first hyperframe number and both M and N are natural numbers.

[0034] How Fig. 2, a first embodiment of switching from the current cell to a target cell in step S2 comprises the following steps.

[0035] In step S21, a group call session is initiated and established so that when establishing a trunking service transmission by the base station, a field for transmitting encryption parameters of the group call data is newly added and the encryption parameters are stored.

[0036] When establishing a group call service, a calling user device receives a call device identifier and area coverage information set by the calling user, and sends a first call setup request to a control device. The first request includes the calling user's call device identifier, a group call service type, and area coverage information set by the calling user. It should be noted that in this step, the calling user device may be a user terminal, a vehicle-mounted terminal, a dispatch console, etc. Furthermore, in trunked communication systems with different control modes, the control device may be a control center or a base station.

[0037] When a group call establishment request sent from the control device as a called user equipment is received, the group call establishment request including the device ID of the calling user, the area coverage information set by the calling user, as well as a group ID and traffic channel-associated position information of the called user equipment is obtained, and the position information of the called user equipment is judged to be within the area coverage; further, if the position information of the called user equipment is within the area coverage, the called user equipment participates in the group call service and switches to the traffic channel.In this step, it should be noted that in the trunking communication systems with different control modes, the group ID and the traffic channel can be assigned either by the control center or by the base station, or either the group ID or the traffic channel can be assigned by the control center and the other of them by the base station.

[0038] In step S22, when switching from the current cell to the target cell, a signal is newly added or multiplexed to transmit a session key identifier of the current cell or to directly transmit a key of the current cell.

[0039] ShortMac-i can be used as a session key identifier.

[0040] In step S23, the encrypted group call data of the target cells is received.

[0041] In step S24, the decryption operation is performed on the encrypted multicast data of the target cell according to the second hyperframe number.

[0042] As in Fig. 3, the following steps are further performed between step S22 and step S23.

[0043] In step S221, the session key identifier of the current cell or the key of the current cell is sent to the base station of the target cell, and the base station of the target cell compares the session key identifier of the current cell or the key of the current cell with a key of the target cell to judge whether the two are consistent.

[0044] In step S222, if consistent, the encrypted group call data of the target cell is received by the base station of the target cell.

[0045] In step S223, if inconsistent, the key of the target cell is sent to the base station of the current cell while receiving encrypted multicast data of the target cell from the base station of the target cell, and the key of the target cell is sent from the base station of the current cell to the user equipment.

[0046] In the first embodiment, the user equipment switches to a connected state from the current cell to the target cell.

[0047] As in Fig. 4, a second embodiment of switching from the current cell to a target cell in step S2 comprises the following steps.

[0048] In step S25, a group call session is initiated and established, so that when establishing a trunking service transmission by the base station, a field for transmitting encryption parameters of the group call data is newly added and the encryption parameters are stored.

[0049] When a group call service is established as a calling user equipment, a calling user equipment identifier and area coverage information set by the calling user are obtained, and a first call setup request is sent to a control center. The first request includes the calling user equipment identifier, a group call service type, and the area coverage information set by the calling user. In this step, it should be noted that the calling user equipment may be a user terminal, a vehicle-mounted terminal, a dispatcher console, etc. Furthermore, in trunked communication systems with different control modes, the control device may be a control center or a base station.

[0050] When a group call setup request sent from the control device as a calling user equipment is received, the group call setup request containing the calling user equipment ID, the area coverage information set by the calling user, as well as a group ID and traffic channel-associated position information of the called user equipment is obtained, and the position information of the called user equipment is judged to determine whether it is within the area coverage. Furthermore, if the position information of the called user equipment is within the area coverage, the called user equipment participates in the group call service and switches to the traffic channel.In this step, it should be noted that in trunking communication systems with different control modes, the group identifier and traffic channel can be assigned either by the control center or by the base station, or the group identifier or traffic channel can be assigned by the control center and the other by the base station.

[0051] In step S26, the encrypted group call data of the target cell is received by the base station of the target cell.

[0052] According to the second embodiment, the user device switches from the current cell to the target cell in the idle state.

[0053] In step S3, the second hyperframe number is traversed according to the interval range of the second hyperframe number and a plaintext according to the second hyperframe number is obtained, and group call session information included in the plaintext is compared with the group call data of the current cell.

[0054] Obtaining the plaintext according to the second hyperframe number specifically comprises: changing a value of the second hyperframe number within the interval range of [XM, X+N] and performing a decryption operation according to the changed value of the second hyperframe number to obtain the plaintext.

[0055] In step S4, if the comparison result is consistent, if decryption is successful by traversing the second hyperframe number, a decryption operation is performed according to the second hyperframe number.

[0056] The traversal of the second hyperframe number for successful decryption comprises in particular: an order of traversing the second hyperframe number: X→X−1→X+1→X−2→X+2…→X−M…→X+N.

[0057] In the embodiment, the group call data is preferably configured as PDCP SN 5-bit with a packet interval of 20 ms, with M and N set to 2 and the other group call configurations set to 1. Of course, the larger the configurations, the more reliable they are, but the time required also increases accordingly.

[0058] Input parameters for decryption include a hyperframe number, a secret key, a ciphertext block of group call data, an encryption algorithm, and other parameters. Only the hyperframe number can be different for different cells, so constant parameters are used to perform a standard decryption process in which only the hyperframe number values ​​are changed to obtain the plaintext. The group call session information contained in the plaintext is compared with a group call context of the user device in the current cell. If the comparison result is consistent, the process changes from traversing the hyperframe number to decryption, and the hyperframe number value is considered a valid value, and then the hyperframe number value is retained for the decryption operation.

[0059] When switching the user equipment from the current cell to the destination cell, the trunking group call decryption method derives an appropriate interval range of the second hyperframe number of the destination cell according to the first hyperframe number of the user equipment in the current cell and performs traversal decryption according to the second hyperframe number to reduce the time delay of the group call service interruption and improve the user experience.

[0060] Fig. Figure 5 shows a block diagram of a user equipment based on the trunked group call decryption method according to the present invention. The user equipment includes a device module 10, a key module 20, a monitoring module 30, a transceiver module 40, and a processing module 50.

[0061] The monitoring module 30 is configured to monitor group call data of the user equipment in a current cell and to obtain from a base station of the current cell a hyperframe number of the current cell, which is the first hyperframe number.

[0062] Each base station performs multicast data transmission with a plurality of cells. In the embodiment, the current cell and the target cell may perform multicast data transmission with the same base station or with two different base stations. After initiating a multicast session, each cell under the base station establishes the session approximately synchronously and transmits multicast code streams using encryption parameters to ensure that the number and content of multicast code streams are the same in different cells, so that the hyperframe numbers (HFNs) of a Packet Data Convergence Protocol (PDCP) layer are approximately the same.

[0063] The transceiver module 40 is configured to receive the group call data from a base station of the target cell when switching the user equipment from the current cell to the target cell and to obtain an interval range of a hyperframe number of the target cell according to the first hyperframe number, wherein the hyperframe number of the target cell is a second hyperframe number.

[0064] The second hyperframe number lies within an interval range of [XM, X+N], where X is the first hyperframe number and both M and N are natural numbers.

[0065] A first embodiment of switching from the current cell to a target cell comprises the following steps.

[0066] The setup module 10 is configured to initiate and establish a group call session such that when a trunking service transmission is established by the base station, a field is newly added to transmit encryption parameters of the group call data and the decryption parameters are stored.

[0067] When establishing a group call service, a calling user equipment identifier and area coverage information set by the calling user are obtained as the calling user equipment, and a first call setup request is sent to a control device. The first request includes the calling user equipment identifier, a group call service type, and the area coverage information set by the calling user. In this step, it should be noted that the calling user equipment may be a user terminal, a vehicle-mounted terminal, a dispatcher console, etc. Furthermore, in trunked communication systems with different control modes, the control device may be a control center or a base station.

[0068] When a group call setup request sent from the control device as a calling user equipment is received, the group call setup request containing the calling user equipment ID, the area coverage information set by the calling user, as well as a group ID and traffic channel-associated position information of the called user equipment is obtained, and the position information of the called user equipment is judged to be within the area coverage; further, if the position information of the called user equipment is within the area coverage, the called user equipment participates in the group call service and switches to the traffic channel.In this step, it should be noted that in trunking communication systems with different control modes, the group identifier and traffic channel can be assigned either by the control center or by the base station, or either the group identifier or the traffic channel can be assigned by the control center and the other by the base station.

[0069] The key module 20 is configured to re-add or multiplex a signal to transmit a session key identifier of the current cell or to directly transmit a key of the current cell when switching the user equipment from the current cell to the target cell.

[0070] ShortMac-i can be used as a session key identifier.

[0071] The transceiver module 40 receives the encrypted group call data of the target cell.

[0072] The processing module 50 is configured to perform the decryption operation on the encrypted multicast data of the target cell according to the second hyperframe number.

[0073] The key module 20 is further configured to transmit the current cell session key identifier or the current cell key to the target cell base station, and the target cell base station compares the current cell session key identifier or the current cell key with a target cell key.

[0074] If consistent, the transceiver module 40 receives the encrypted group call data of the target cell from the base station of the target cell.

[0075] If inconsistent, the transceiver module 40 sends the target cell key to the current cell base station while receiving encrypted multicast data of the target cell from the target cell base station, and the target cell key is sent from the current cell base station to the user equipment.

[0076] In the first embodiment, the user equipment switches from the current cell to the target cell in a connected state.

[0077] A second embodiment of switching the current cell to a target cell comprises the following steps.

[0078] The setup module 10 is configured to initiate and establish a group call session such that when a trunking service transmission is established by the base station, a field for transmitting group call encryption parameters is newly added and the group call encryption parameters are stored.

[0079] When establishing a group call service, a calling user equipment identifier and area coverage information set by the calling user are obtained as the calling user equipment, and a first request to establish a call is sent to a control device. The first request includes the calling user equipment identifier, a group call service type, and the area coverage information set by the calling user. In this step, it should be noted that the calling user equipment may be a user terminal, a vehicle-mounted terminal, a dispatcher console, etc. Furthermore, in trunking communication systems with different control modes, the control device may be a control center or a base station.

[0080] Upon receiving a group call setup request sent from the control device as a calling user equipment, the group call setup request including the calling user equipment ID, the area coverage information set by the calling user, as well as a group ID and traffic channel-associated position information of the called user equipment is obtained, and the position information of the called user equipment is judged to be within the area coverage; further, if the position information of the calling user equipment is within the area coverage, the calling user equipment participates in the group call service and switches to the traffic channel.In this step, it should be noted that in the trunking communication systems with different control modes, the group ID and the traffic channel can be assigned either by the control center or by the base station, or either the group ID or the traffic channel is assigned by the control center and the other by the base station.

[0081] The transceiver module 40 receives the encrypted group call data of the target cell from the base station of the target cell.

[0082] In the second embodiment, the user device switches from the current cell to the target cell in the idle state.

[0083] The processing module 50 is configured to traverse the second hyperframe number according to the interval range of the second hyperframe number and obtain a plaintext according to the second hyperframe number, and compare the multicast session information included in the plaintext with the multicast data of the current cell.

[0084] Obtaining the plaintext according to the second hyperframe number specifically includes: changing a value of the second hyperframe number within the interval range of [XM, X+N], and performing a decryption operation according to the changed value of the second hyperframe number to obtain the plaintext.

[0085] If the comparison result is consistent, a decryption operation according to the second hyperframe number is performed by successfully decrypting by traversing the second hyperframe number with the processing module 50.

[0086] In particular, traversing the second hyperframe number for successful decryption comprises an order of traversing the second hyperframe number as follows: X→X-1→X+1→X-2→X+2...→XM...→X+N.

[0087] In the embodiment, the group call data is preferably configured as PDCP SN 5-bit with a packet interval of 20 ms, where M and N are set to 2, and the other group call configurations are set to 1. The larger the configurations, the more reliable they are, but the time required also increases accordingly.

[0088] Input parameters for decryption include a hyperframe number, a secret key, a ciphertext block of the group call data, a decryption algorithm, and other parameters. Only the hyperframe number can be different for different cells, so constant parameters can be used to perform a standard decryption process by changing only the hyperframe number values ​​to obtain the plaintext. The group call session information contained in the plaintext is compared with a group call context of the user device in the current cell. If the comparison result is consistent, the process of traversing the hyperframe number for decryption is terminated, and the hyperframe number value is considered a valid value, and then the hyperframe number value is retained for the decryption operation.

[0089] The aforementioned modules of the user equipment according to the embodiment of the present invention carry out the decryption method based on a trunking group call according to the present embodiment and have the same technical effects as the method.

[0090] It should be understood that the division of the above modules is a logical functional division, and further divisions may be provided during the actual implementation. For example, two modules may be integrated into another system, or some of the features may be ignored or not implemented. Furthermore, the modules may be interconnected via some interfaces, electrically connected, or connected by other means. The above modules may be implemented in the form of software functional blocks or in the form of hardware, as shown in Fig. 6 shown.

[0091] Fig. Figure 6 shows a hardware structure diagram of the user equipment based on the encryption method for a trunked group call according to the present invention. The user equipment includes a memory 110, a processor 120, a controller 130, and a communication bus 140. The communication bus 140 is used by the processor 120 to retrieve various data, and the memory 110 is used to store program instructions. For ease of explanation, the number of the processor 120, the memory 110, the communication bus 140, and the controller 130 is as shown in Fig. 6 shown, one.

[0092] The memory 110 stores all program instructions of the setup module 10, the key module 20, the monitoring module 30, the transceiver module 40 and the processing module 50.

[0093] The processor 120 monitors the group call data of the user equipment in a current cell and receives a hyperframe number of the current cell as the first hyperframe number from the base station of the current cell.

[0094] Each base station performs multi-cell multicast data transmission. In the embodiment, the current cell and the target cell can perform multicast data transmission with the same base station or with two different base stations. After initiating a multicast session, each cell under the base station establishes the session approximately synchronously and transmits multicast code streams using decryption parameters to ensure that the number and content of multicast code streams are the same in different cells, so that the hyperframe number (HFN) of the Packet Data Convergence Protocol (PDCP) layer will be approximately the same.

[0095] When switching the user equipment from the current cell to the target cell, the processor 120 receives the group call data from the base station of the target cell and obtains an interval range of a hyperframe number of the target cell corresponding to the first hyperframe number, the hyperframe number of the target cell being a second hyperframe number.

[0096] The second hyperframe number lies within an interval range of [XM, X+N], where X is the first hyperframe number and both M and N are natural numbers.

[0097] A first embodiment of switching the user device from the current cell to a target cell comprises the following steps.

[0098] The processor 120 initiates and establishes a group call session such that when the base station establishes a trunking service transmission, a field for transmitting encryption parameters of the group call data is newly added and the encryption parameters are stored.

[0099] When establishing a group call service, as the calling user equipment, a user equipment identifier and area coverage information set by the calling user are obtained, and a first call setup request is sent to a control device. The first request includes the calling user equipment identifier, a group call service type, and the area coverage information set by the calling user. It should be noted that in this step, the calling user equipment may be a user terminal, a vehicle-mounted terminal, a dispatcher console, etc. Furthermore, in trunked communication systems with different control modes, the control device may be a control center or a base station.

[0100] When a group call setup request sent from the control device as a called user equipment is received, the group call setup request containing the calling user equipment ID, the area coverage information set by the calling user, as well as a group ID and traffic channel-associated position information of the called user equipment is received, and the position information of the called user equipment is judged to be within the area coverage; further, if the position information of the called user equipment is within the area coverage, the called user equipment participates in the group call service and switches to the traffic channel.In this step, it should be noted that in trunking communication systems with different control modes, the group identifier and traffic channel can be assigned either by the control center or by the base station, or the group identifier or traffic channel can be assigned by the control center and the other by the base station.

[0101] When switching the user device from the current cell to the target cell, the processor 120 adds or multiplexes a signal to transmit a session key identifier of the current cell or to directly transmit a key of the current cell.

[0102] ShortMac-i can be used as a session key identifier.

[0103] The processor 120 receives the encrypted group call data of the target cell.

[0104] The controller 130 is configured to perform the decryption operation on the encrypted multicast data of the target cell according to the second hyperframe number.

[0105] The processor 120 further sends the current cell session key identifier or the current cell key to the base station of the target cell, and the base station of the target cell compares the current cell session key identifier or the current cell key with a key of the target cell.

[0106] If consistent, the processor 120 receives the encrypted group call data of the target cell from the base station of the target cell.

[0107] If inconsistent, the processor 120 sends the target cell key to the current cell base station while receiving encrypted target cell multicast data from the target cell base station, and the target cell base station sends the target cell key to the user equipment.

[0108] In the first embodiment, the user equipment switches to a connected state from the current cell to the target cell.

[0109] A second embodiment of switching the user device from the current cell to a target cell comprises the following steps.

[0110] The processor 120 initiates and establishes a multicast session such that when the base station establishes a trunking service transmission, a field for transmitting multicast encryption parameters is newly added and the multicast encryption parameters are stored.

[0111] When establishing a group call service, as a calling user equipment, the calling user equipment identifier and area coverage information set by the calling user are obtained, and a first request to establish a call is sent to a control device. The first request includes the calling user equipment identifier, a group call service type, and area coverage information set by the calling user. In this step, it should be noted that the calling user equipment may be a user terminal, a vehicle-mounted terminal, a dispatch console, etc. Furthermore, in trunked communication systems with different control modes, the control device may be a control center or a base station.

[0112] When receiving a group call setup request sent by the control device as a called user device, the group call setup request, which contains the calling user device identifier, the range information set by the calling user, as well as the group identifier and the position information associated with the traffic channel of the called user device, is obtained, and the position information of the called user device is judged as to whether it is within the range; furthermore, if the position information of the called user device is within the range, the called user device participates in the group call service and switches to the traffic channel.In this step, it should be noted that in the trunking communication systems with different control modes, the group ID and traffic channel are assigned either by the control center or by the base station, or the group ID or traffic channel are assigned by the control center and the other by the base station.

[0113] The processor 120 receives the encrypted group call data of the target cell from the base station of the target cell.

[0114] In the second embodiment, the user device switches from the current cell to the target cell in the idle state.

[0115] The controller 130 is configured to traverse the second hyperframe number according to the interval range of the second hyperframe number and obtain a plaintext according to the second hyperframe number, and compare the multicast session information included in the plaintext with the multicast data of the current cell.

[0116] Obtaining the plaintext according to the second hyperframe number specifically includes: changing a value of the second hyperframe number within the interval range of [XM, X+N], and performing a decryption operation according to the changed value of the second hyperframe number to obtain the plaintext.

[0117] If the comparison result is consistent, after successful decryption by passing through the second hyperframe number with the controller 130, a decryption operation is performed according to the second hyperframe number.

[0118] In particular, traversing the second hyperframe number for successful decryption comprises an order of traversing the second hyperframe number as follows: X→X-1→X+1→X-2→X+2...→XM...→X+N.

[0119] In the embodiment, the group call data is preferably configured as PDCP SN 5-bit with a packet interval of 20 ms, with M and N set to 2, and the other group call configurations set to 1. Of course, the larger the configurations, the more reliable they are, but the time required also increases accordingly.

[0120] Input parameters for decryption include a hyperframe number, a secret key, a ciphertext block of the group call data, a decryption algorithm, and other parameters. Only the hyperframe number can be different for different cells, so constant parameters can be used to perform a standard decryption process in which only the hyperframe number values ​​are changed to obtain the plaintext. The group call session information contained in the plaintext is compared with a group call context of the user device in the current cells. If a comparison result is consistent, the process of traversing the hyperframe number for decryption is terminated, and the hyperframe number value is considered a valid value, and then the hyperframe number value is retained for the decryption process.

[0121] When switching the user equipment from the current cell to the destination cell, the trunking group call decryption method derives an appropriate interval range for the second hyperframe number of the destination cell according to the first hyperframe number of the user equipment in the current cell, traverses the second hyperframe number according to the interval range of the second hyperframe number, performs traversal decryption according to the second hyperframe number, and performs decryption operation according to the second hyperframe number after successful decryption, so that the time delay when the group call service is interrupted decreases and the user experience is improved.

[0122] The above descriptions are merely embodiments of the invention and are not intended to limit the scope of the invention. Any equivalent structures or equivalent changes in process made using the description of the invention or the accompanying drawings, or used directly or indirectly in other related technical fields, are also included within the scope of the invention.

Claims

A decryption method for a trunking group call applied to a user equipment, comprising:monitoring (S1) group call data in a current cell and obtaining a hyperframe number of the current cell, which is a first hyperframe number, from a base station of the current cell;when switching from the current cell to a target cell, obtaining (S2) the group call data from a base station of the target cell and obtaining an interval range of a hyperframe number of the target cell according to the first hyperframe number, wherein the hyperframe number of the target cell is a second hyperframe number;traversing (S3) the second hyperframe number according to the interval range of the second hyperframe number and obtaining a plaintext according to the second hyperframe number and comparing the group call session information contained in the plaintext with the group call data of the current cell;andif a comparison result matches, after successful decryption by traversing the second hyperframe, performing (S4) a decryption operation according to the second hyperframe number,wherein the step of switching from the current cell to a target cell comprises:initiating and establishing (S21) a multicast session such that, upon establishing a trunking service transmission by the base station, a field for transmitting encryption parameters of the multicast data is newly added and the encryption parameters are stored;switching (S22) from the current cell to the target cell, re-adding or multiplexing a signal for transmitting a session key identifier of the current cell or for directly transmitting a key of the current cell; andreceiving (S23) encrypted multicast data of the target cell;andwherein the step of performing a decryption operation according to the second hyperframe number comprises:performing (S24) the decryption operation on the encrypted multicast data of the target cell according to the second hyperframe number; The decryption method for a trunked multicast according to claim 1, wherein, in the step of obtaining the multicast data from a base station of the target cell and obtaining an interval range of a hyperframe number of the target cell according to the first hyperframe number: the second hyperframe number is within an interval range of [XM, X+N], where X is the first hyperframe number and both M and N are natural numbers; and the step of traversing the second hyperframe number according to the interval range of the second hyperframe number and obtaining a plaintext according to the second hyperframe number comprises: changing a value of the second hyperframe number within the interval range of [XM, X+N], and performing a decryption operation according to the changed value of the second hyperframe number to obtain the plaintext. A decryption method for a trunking group call according to claim 2, wherein in the step, after successful decryption by traversing the second hyperframe number, of performing a decryption operation according to the second hyperframe number, an order of traversing the second hyperframe number is as follows: X → X − 1 → X + 1 → X − 2 → X + 2 ... → X − M ... → X + N . A trunking group call decryption method according to claim 2, wherein when the group call data is configured as PDCP SN 5bit and a packet interval is 20 ms, M and N are set to 2. The trunked multicast decryption method of claim 1, wherein, prior to the step of receiving encrypted multicast data of the target cell, the method further comprises:sending the current cell session key identifier or the current cell key to the base station of the target cell, and comparing, by the base station of the target cell, the current cell session key identifier or the current cell key with a target cell key;if consistent, receiving the encrypted multicast data of the target cell from the base station of the target cell; andif inconsistent, sending the target cell key to the base station of the current cell while receiving encrypted multicast data of the target cell from the base station of the target cell, and sending the target cell key from the base station of the current cell to the user equipment. The trunked multicast decryption method of claim 1, wherein the step of switching from the current cell to a target cell comprises:initiating and establishing a multicast session such that, upon establishing a trunking service transmission by the base station, a field for transmitting encryption parameters of the multicast data is newly added and the encryption parameters are stored; andreceiving encrypted multicast data of the target cell from the base station of the target cell. A user equipment comprising:a monitoring module (30) configured to monitor multicast data of the user equipment in a current cell and to obtain from a base station of the current cell a hyperframe number of the current cell, which is a first hyperframe number;a transceiver module (40) configured to receive, when switching the user equipment from the current cell to a target cell, the multicast data from a base station of the target cell and to obtain an interval range of a hyperframe number of the target cell according to the first hyperframe number, wherein the hyperframe number of the target cell is a second hyperframe number;a processing module (50) connected to the monitoring module and the transmit-receive module and configured to traverse the second hyperframe number according to the interval range of the second hyperframe number, obtain a plaintext according to the second hyperframe number, and compare group call session information contained in the plaintext with the group call data of the current cell; and if a comparison result is consistent, after successful decryption by traversing the second hyperframe number, perform a decryption operation according to the second hyperframe number;and a device module (10) and a key module (20), wherein, when the user equipment switches from the current cell to the target cell, the device module initiates and establishes a multicast session, so that when a trunking service transmission is established by the base station, a field for transmitting encryption parameters of the multicast data is newly added and the encryption parameters are stored; when switching from the current cell to the target cell, a signal for transmitting a session key identifier of the current cell or for directly transmitting a key of the current cell is newly added or multiplexed; the transceiver module receives encrypted multicast data of the target cell; and the processing module performs the decryption process on the encrypted multicast data of the target cell according to the second hyperframe number. The user equipment of claim 7, wherein the second hyperframe number is within an interval range of [XM, X+N], X is the first hyperframe number, and both M and N are natural numbers; and a value of the second hyperframe number is changed within the interval range of [XM, X+N], and a decryption operation is performed by the processing module according to the changed value of the second hyperframe number to obtain the plaintext. User equipment according to claim 8, wherein an order for the processing module to traverse the second hyperframe number is as follows: X → X − 1 → X + 1 → X − 2 → X + 2 ... → X − M ... → X + N . User equipment according to claim 9, wherein when the group call data is configured as PDCP SN 5bit and a packet interval is 20 ms, M and N are set to 2. The user equipment of claim 7, wherein the key module further transmits the current cell session key identifier or the current cell key to the base station of the target cell, and the base station of the target cell compares the current cell session key identifier or the current cell key with a target cell key; if consistent, the transceiver module receives the encrypted target cell multicast data from the base station of the target cell; and if inconsistent, the target cell key is transmitted to the base station of the current cell while receiving encrypted target cell multicast data from the base station of the target cell, and the base station of the current cell transmits the target cell key to the user equipment. The user equipment of claim 7, further comprising a setup module, wherein the setup module initiates and establishes a multicast session upon switching the user equipment from the current cell to the target cell, such that upon establishing a trunking service transmission by the base station, a field for transmitting encryption parameters of the multicast data is newly added and the encryption parameters are stored; and the transceiver module receives encrypted multicast data of the target cell from the base station of the target cell. A user device comprising: a memory (110) configured to store program instructions; a processor (120) configured to monitor multicast data of the user device in a current cell and to obtain, from a base station of the current cell, a hyperframe number of the current cell that is a first hyperframe number; wherein the processor is further configured to, upon switching the user device from the current cell to a target cell, receive the multicast data from a base station of the target cell and obtain an interval range of a hyperframe number of the target cell according to the first hyperframe number, the hyperframe number of the target cell being a second hyperframe number;anda controller (130) configured to traverse the second hyperframe number according to the interval range of the second hyperframe number, obtain a plaintext according to the second hyperframe number, and compare group call session information contained in the plaintext with the group call data of the current cell; and if a comparison result is consistent, after successful decryption by traversing the second hyperframe number, perform a decryption operation according to the second hyperframe number, wherein, upon switching the user equipment from the current cell to the target cell, the processor initiates and establishes a group call session, so that when establishing a trunking service transmission by the base station, a field for transmitting encryption parameters of the group call data is newly added and the encryption parameters are stored;when switching the user equipment from the current cell to the target cell, the processor newly adds or multiplexes a signal to transmit a session key identifier of the current cell or directly transmits a key of the current cell; the processor receives encrypted multicast data of the target cell; and the controller performs the decryption process on the encrypted multicast data of the target cell according to the second hyperframe number.; The user equipment of claim 13, wherein the second hyperframe number is within an interval range of [XM, X+N], X is the first hyperframe number, and both M and N are natural numbers; and a value of the second hyperframe number is changed within the interval range of [XM, X+N], and a decryption process is performed by the processing module according to the changed value of the second hyperframe number to obtain the plaintext. User equipment according to claim 14, wherein an order for the processing module to traverse the second hyperframe number is as follows: X → X − 1 → X + 1 → X − 2 → X + 2 … → X − M … → X + N ; and if the group call data is configured as PDCP SN 5bit and a packet interval is 20 ms, M and N are set to 2. The user equipment of claim 13, wherein the processor further sends the current cell session key identifier or the current cell key to the base station of the target cell, and the base station of the target cell compares the current cell session key identifier or the current cell key with a target cell key; if consistent, the processor receives the encrypted target cell multicast data from the base station of the target cell; and if inconsistent, the processor sends the target cell key to the base station of the current cell while receiving encrypted target cell multicast data from the base station of the target cell, and the base station of the current cell sends the target cell key to the user equipment. The user equipment of claim 13, wherein, upon switching the user equipment from the current cell to the target cell, the processor initiates and establishes a multicast session such that, upon establishing a trunking service transmission by the base station, a field for transmitting encryption parameters of the multicast data is newly added and the encryption parameters are stored; and the processor receives encrypted multicast data of the target cell from the base station of the target cell.

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