Implementation method for first-number dual-mode service processing of wide-narrow fusion terminal

Abstract

The invention relates to an implementation method for first-number dual-mode service processing of a wide-narrow fusion terminal. The method comprises the following steps: firstly, determining service preconditions: wide and narrow bands use the same number and keep a consistent current group; secondly, introducing a preferable network concept: adopting a strategy of combining user preference and automatic switching, namely, providing an interface for a user to select a preferable network according to a use scene and the user preference; on the basis of the selection, an automatic switching algorithm is triggered, when it is detected that the current network is abnormal, another mode is automatically switched immediately, and the preferred network serves as a trustworthy mode identifier of the service; and finally, proposing a calling strategy: the incoming call and the outgoing call of the current group preferentially respond to an optimal network mode, so as to ensure that the call of the attended group is established in a mode with more reliable network quality and service. And when the preferred network mode cannot respond, the terminal automatically and quickly switches to another mode to respond or initiate a call, so that the user perception-free intelligent switching is realized, and the correctness, the stability and the sustainability of the current group call service are ensured to the greatest extent.

Description

Technical Field

[0001] The present invention belongs to the technical field of cluster communications, and in particular relates to a method for implementing one-number dual-mode service processing of a broadband-narrowband converged terminal. Background Art

[0002] The current trunking communications field is undergoing a phase of "broadband and narrowband integration, and public-private integration." Narrowband standards include TETRA and PDT, while broadband standards include B-Trunc and PoC public network intercom. Various manufacturers are integrating these standards in different forms on both the system and terminal sides.

[0003] TETRA, or Terrestrial Trunked Radio, is a narrowband digital trunked communications standard developed by the European Telecommunications Standards Institute (ETSI) in the 1990s. It is designed to provide efficient and secure voice dispatch, data communications, and command and control services for professional users. TETRA utilizes TDMA (Time Division Multiple Access) technology, providing four time slots per 12.5kHz bandwidth, supporting concurrent multi-user communication. As a leading global private network communications standard, TETRA has played an irreplaceable role in public safety, transportation, industry, and other fields thanks to its high reliability, versatile dispatching, and security features.

[0004] PDT, or Police Digital Trunking, is a narrowband private network technology standard developed in 2008 by my country's Ministry of Public Security. It aims to establish a narrowband trunking standard with independent and controllable core technologies. PDT utilizes narrowband technology with a 12.5kHz bandwidth and a large-area design (a single base station can cover a radius of up to 50 kilometers), reducing network construction costs and making it particularly suitable for sparsely populated areas. Over the past decade, PDT has played a vital role in daily policing, security, and emergency response operations.

[0005] China has also developed a pure broadband trunking standard (B-Trunc) based on TD-LTE technology. The Ministry of Industry and Information Technology has designated 20 MHz bandwidth (1447-1467 MHz and 1785-1805 MHz) for use in government broadband private networks. However, due to technical limitations of broadband systems, large-scale coverage is not possible, and the massive infrastructure presents unprecedented challenges for private network construction. Due to the limitations of B-Trunc broadband trunking, many sectors in the industry are adopting public intercom (PoC) based on carrier networks as a broadband trunking solution. PoC, or Push to Talk over Cellular, is a communication technology based on cellular networks (such as 4G / 5G) that implements broadband trunking capabilities. Its core technology, VoIP (Voice over Internet Protocol), converts voice, video, and data signals into data packets, transmits them to a server via the mobile network, and then forwards them to the target user or group, supporting one-to-one and one-to-many communication modes. Unlike traditional walkie-talkies that rely on dedicated frequencies, PoC relies on carrier networks, transcending geographical distance limitations and achieving nationwide and even global coverage. PoC products can implement custom protocols or 3GPP / CX protocols.

[0006] To achieve the goal of using narrowband (PDT / TETRA) private networks while leveraging PoC broadband clusters with 4G / 5G operator networks, a broadband-narrowband converged terminal is designed, that is, a narrowband (PDT / TETRA) + LTE broadband integrated terminal. This can enrich the convergence model of voice, video, and data services. In broadband-narrowband convergence technology, broadband and narrowband systems are interconnected, and application terminals are multi-mode. This can not only maximize the role of private networks, highlight benefits, but also save investment.

[0007] For broadband-narrowband converged terminals, some manufacturers have adopted a "narrowband-first" approach, with broadband PoC enabled only when narrowband is unavailable. This approach fails to truly achieve good broadband-narrowband integration and complementarity. If narrowband (PDT / TETRA) and broadband PoC coexist, the question arises as to how to achieve better integration. Summary of the Invention

[0008] In view of the problems existing in the prior art, the purpose of the present invention is to provide a technical solution for a method for implementing one-number dual-mode service processing of a broadband-narrow converged terminal.

[0009] The method for implementing one-number dual-mode service processing of a broadband-narrow converged terminal is characterized by comprising the following steps: 1) When narrowband and broadband PoC converged terminals are connected to the same network or logged in with the same number, the user can select one of them as the preferred network. By default, narrowband is the preferred network. 2) Ensure that the wide and narrow bands remain consistent with the current group; 3) Determine the preferred network based on a strategy combining user preferences and automatic switching; 4) Develop the outbound call strategy for the current group; 5) Develop the inbound call strategy for the current group; 6) Formulate the network switching strategy for the current group call.

[0010] The method for implementing one-number dual-mode service processing of a broadband and narrowband converged terminal is characterized in that the specific steps of ensuring that the broadband and narrowbands maintain a consistent current group are: when the knob is not used to switch groups, the broadband and narrowband converged terminal switches the current group of the other mode to the current group initially configured for the preferred network; when the knob switches the current group for the preferred network, the broadband and narrowband converged terminal switches the current group of the other mode to the same current group.

[0011] The method for implementing dual-mode service processing for a broadband-narrowband converged terminal is characterized in that the strategy for determining the preferred network based on a combination of user preference and automatic switching includes: when narrowband is the preferred network, network switching is performed based on a comparison result between the narrowband signal field strength mean and a set threshold; when broadband is the preferred network, network switching is performed based on the broadband network type, signal strength, and ping value response with the PoC server.

[0012] The method for implementing dual-mode service processing of a broadband-narrow converged terminal is characterized in that the user can select the mode that he prefers more as the preferred network. When the network quality of the mode is good, the mode is used as the preferred network; when the network quality of the mode is detected to be poor or abnormal, and the network condition and access status of the other mode are both good, it automatically switches to the other mode as the preferred network.

[0013] The method for implementing a dual-mode service processing of a broadband-narrowband integrated terminal is characterized in that the narrowband signal field strength mean value is calculated as follows: the narrowband modem obtains an RSSI value every 500 milliseconds, and takes the average value C1 of the three most recent RSSI values ​​as the judgment value. C1=(RSSI-1+RSSI-2+RSSI-3) / 3 When C1 < Q1, it means that the narrowband network is poor and cannot be used as a priority network option; When C1 ≥ Q1, it indicates that the narrowband network is good and can be used as the preferred network; The broadband and narrowband converged terminal provides an interface that can dynamically set the narrowband network quality threshold Q1 according to the scenario. The default value of Q1 is -90dBm.

[0014] The method for implementing dual-mode service processing of a broadband-narrowband converged terminal is characterized in that the criteria for judging the broadband network type and signal strength are: networks below 3G are not suitable as preferred networks; the 3G network signal strength needs to reach level 4; and the 4G / 5G network signal strength needs to reach levels 2-4.

[0015] The method for implementing dual-mode service processing for a broadband-narrow converged terminal is characterized in that the judgment standard for the ping value response with the PoC server is as follows: the terminal regularly pings the PoC server, by default once per second, and the ping cycle is shortened when the response time exceeds 100ms. If the response time exceeds 100ms for five consecutive times, it is determined not to be a preferred network option; if the response time is within 100ms for five consecutive times, it is determined to be a preferred network option.

[0016] The method for implementing one-number dual-mode service processing for a broadband-narrow converged terminal is characterized in that the current group call outbound strategy is: when the broadband-narrow converged terminal is idle, press the PTT key to initiate a group call of the current group in the preferred network; if it fails, automatically switch to initiate a group call of the current group in another mode.

[0017] The method for implementing the one-number dual-mode service processing of a broadband-narrow converged terminal is characterized in that the current group call incoming strategy is: when the broadband and narrowband of the broadband-narrow converged terminal are in the same current group, the other terminal initiates a group call to the current group, and gives priority to responding to the current group call incoming on the preferred network mode. If the call is not received within a certain period of time, the group call on the other mode will be picked up.

[0018] The method for implementing one-number dual-mode service processing of a broadband-narrow converged terminal is characterized in that the network switching strategy in the current group call is: if the current mode is unexpectedly interrupted during the current group call, the converged terminal actively calls back the current group call on another mode in a call merging manner to keep the call going normally.

[0019] To better integrate broadband and narrowband services for converged broadband and narrowband terminals, this invention proposes a method for implementing dual-mode service processing on a single-number broadband and narrowband converged terminal. First, the service premise is clarified: broadband and narrowband use the same number and maintain a consistent current group. Second, the concept of a preferred network is introduced: a strategy combining user preferences with automatic switching is employed. Specifically, an interface is provided for users to select a preferred network (narrowband or broadband PoC) based on the usage scenario and user preferences. Based on this selection, an automatic switching algorithm is triggered. Upon detecting an anomaly in the current network, the system automatically switches to the other mode. This preferred network serves as a trusted service mode identifier. Finally, a call strategy is proposed: incoming and outgoing calls in the current group prioritize the preferred network mode, ensuring that calls in the on-call group are based on a mode with higher network quality and service reliability. If the preferred network mode becomes unavailable, the terminal automatically and quickly switches to the other mode to respond or initiate a call, achieving user-imperceptible intelligent switching. This maximizes the accuracy, stability, and sustainability of the current group's call service, ensuring that broadband and narrowband trunking services complement and back up each other, improving and guaranteeing the quality and success rate of on-call calls.

[0020] In traditional methods, call interruptions caused by network fluctuations often require the base station or server to initiate delayed entry after the network is restored before the previous call can be restored. If no delayed entry is received during this period, all voice information of the group call will be lost. However, the method of the present invention will determine whether the other mode is available when the call is interrupted by the network. If available, it will rejoin the previous call through call merging. The whole process can be completed within 1 second, and at most two words will be lost. Compared with the traditional method, the call content loss rate is significantly improved, which also reflects the complementary characteristics of the dual modes. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is the overall flow chart of the implementation method of the one-number dual-mode service processing of the broadband and narrowband converged terminal; Figure 2 This is the flow chart of the No. 1 dual-mode broadband preferred network switching for the broadband-narrow converged terminal; Figure 3 This is the flow chart of the switching of the No. 1 dual-mode narrowband preferred network for the broadband-narrowband converged terminal; Figure 4 This is the call processing flow for the current group of a broadband and narrowband converged terminal with one number and dual modes. DETAILED DESCRIPTION

[0022] The present invention will be further described below in conjunction with the accompanying drawings: The technical solution adopted by the present invention includes the following process: (1) The narrowband (PDT / Tetra) and broadband PoC converged terminals have the same network access (or login) number, and the user can select one of them as the preferred network (narrowband is the default preferred network).

[0023] (2) When the knob is not used to switch groups, the broadband-narrowband converged terminal needs to switch the current group of the other mode to the current group initially configured for the preferred network mode; when the knob switches the current group of the preferred network, the broadband-narrowband converged terminal needs to switch the current group of the other mode to the same current group to ensure that the broadband and narrowband modes remain consistent. In this paragraph, when the preferred network is narrowband, the other mode refers to broadband PoC; when the preferred network is broadband PoC, the other mode refers to narrowband.

[0024] (3) When narrowband is selected as the preferred network, the automatic switching algorithm for the narrowband preferred network is triggered. That is, when the narrowband (PDT / Tetra) signal is good, narrowband is selected as the preferred network by default. When the average narrowband signal strength within a certain time range is lower than the set threshold, the priority network is switched to the good broadband PoC mode. When the narrowband (PDT / Tetra) network signal strength is higher than the set threshold within a certain time range, the narrowband is switched back to the preferred network.

[0025] (4) When broadband is selected as the preferred network, the automatic switching algorithm for the broadband preferred network is triggered. That is, when the broadband PoC public network signal is good and the communication with the server is smooth, broadband is selected as the preferred network by default. When the public network signal deteriorates or the communication response time with the server is too long within a certain period of time, the priority network is switched to a good narrowband mode. When the public network signal improves and the response with the server is smooth within a certain period of time, broadband is switched back to the preferred network.

[0026] (5) Current group call outbound strategy: when the broadband-narrowband converged terminal is idle, press the PTT key to initiate a group call to the current group on the preferred network, ensuring that the group call is initiated on the mode with better network quality. If the group call to the current group on the preferred network fails (the network fails instantly, or the preferred network may still be switching), the converged terminal automatically switches to initiate a group call to the current group on another mode.

[0027] (6) Current group call incoming strategy, that is, when the broadband and narrowband of the broadband-narrowband converged terminal are in the same current group, when another terminal initiates a group call to the current group, theoretically both the broadband and narrowband of the converged terminal can receive the same current group group call incoming signaling, and give priority to responding to the current group call incoming from the preferred network module. If no group call incoming signaling from the preferred network module is received within a certain period of time, the group call from the other module will be answered.

[0028] (7) Network switching strategy in the current group call, that is, if an unexpected interruption occurs in the current mode (such as disconnection from the network or system side abnormality), the fusion terminal will immediately call back the current group call in another mode by calling in to keep the call going normally.

[0029] The present invention focuses on how to propose an implementation method for one-number dual-mode business processing on the broadband and narrowband converged terminal side. There are the following two prerequisites on the system side, but they do not belong to the patent content of the present invention and belong to the prior art.

[0030] 1) The broadband and narrowband systems have been uniformly numbered, grouped, and interconnected; 2) The broadband and narrowband switching center has achieved consistency in the call groups corresponding to the same number on the system side.

[0031] It should be noted that the narrowband method described in the present invention is applicable to both PDT and TETRA standards, and the PoC broadband method described in the present invention is applicable to PoC implemented using either a custom protocol standard or the 3GPP MCX protocol standard.

[0032] The following describes the innovative features of the present invention in detail: Broadband and narrowband converged terminal No. 1 dual-mode configuration: First, ensure that the broadband converged terminal uses the same number for narrowband network access and broadband PoC login, with no restrictions on network access or login methods; second, the broadband converged terminal needs to have an interface for users to select the preferred network (narrowband or broadband PoC). If the user does not select, the default setting is not restricted; finally, when operating the broadband and narrowband synchronization current group, when the knob is not used to switch groups, the broadband converged terminal needs to switch the other mode's current group to the current group initially configured for the preferred network; when the knob is used to switch the preferred network's current group, the broadband converged terminal needs to switch the other mode's current group to the same current group to ensure that the broadband and narrowband maintain the same current group. The method for one number dual-mode preferred network is as follows: The preferred network for converged broadband and narrowband terminals utilizes a combination of user preference and automatic program switching. Users can select their preferred mode (narrowband or broadband PoC) as the preferred network. When the network quality of that mode is good, that mode becomes the preferred network. If the automatic switching algorithm detects that the network quality of that mode is poor or abnormal, while the network and login status of the other mode are both good, it automatically switches to the other mode as the preferred network. The reason for combining user preference with automatic program switching, rather than relying solely on the program to automatically determine which is preferred, is that if the network signal is strong but the channel is congested, automatic program selection can lead to misjudgment. This means the program may determine the preferred network, but the actual call quality on that mode may be poor (intermittent). Therefore, the present invention adopts a compromise approach.

[0033] Evaluation method for No. 1 dual-mode narrowband as the preferred network: For narrowband (PDT / TETRA), the converged terminal uses the average RSSI (Received Signal Strength Indicator) value as the basis for judging narrowband network quality. That is, the narrowband modem obtains the RSSI value every 500 milliseconds. To resist instantaneous fluctuation interference, the average value C1 of the three most recent RSSI values ​​is used for judgment.

[0034] C1=(RSSI-1+RSSI-2+RSSI-3) / 3 When C1 < Q1 (set narrowband network quality threshold), it means the narrowband network is poor (unusable); When C1 ≥ Q1, the narrowband network is good (available); The broadband and narrowband converged terminal provides an interface to dynamically set the Q1 threshold based on the scenario. The default value of Q1 is -90dBm; RSSI-1, RSSI-2, and RSSI-3 are the three most recent RSSI values.

[0035] Evaluation method for No. 1 dual-mode broadband as the preferred network: For broadband, the broadband-narrow converged terminal uses two conditions as the basis for judgment, among which condition 1 is the prerequisite, and condition 2 is further judged when condition 1 is met.

[0036] Condition 1: Network type and signal strength The broadband network signal strength level in the Android system is divided into 0 to 4, 5 levels, and the numbers from small to large represent the signal from weak to strong. For networks below 3G, regardless of the network quality, they are considered unsuitable for voice calls and are not selected as the preferred network option; for 3G network signal strength less than 4, they are considered unsuitable for voice calls and are not selected as the preferred network option; for 4G and 5G network signal strength less than 2, they are considered unsuitable for voice calls and are not selected as the preferred network option.

[0037]

[0038] Condition 2: Ping response with PoC server The terminal will ping the PoC server regularly, once every second by default. Once the response time exceeds 100ms, the ping cycle will be shortened to once every 100ms. If the response time exceeds 100ms for five consecutive times, it will be determined not to be a preferred network option. If the response time is within 100ms for five consecutive times, the frequency of pinging the PoC server will be restored to once every 1 second, and it will be determined to be a preferred network option.

[0039] When determining whether broadband is the preferred network, condition 1 is prioritized. If condition 1 is met, condition 2 is further evaluated. Only when both conditions are met does broadband qualify as the preferred network. Determining broadband as the preferred network requires a combination of these two conditions. To address the issue of "strong broadband signal appearance but actual channel congestion (such as at a concert)," the actual channel resource allocation is determined by the response latency of pinging the PoC server.

[0040] No. 1 dual-mode broadband and narrowband preferred network switching process: The preferred network switching decision process is as follows. First, traffic will be diverted based on the user's preference settings. Different preferences have different decision processes.

[0041] As shown in Figure 2, when a user prefers broadband, the judgment steps are as follows: a) Determine whether the broadband has been registered. If it has been registered, proceed to step b); if it has not been registered, proceed to step c); b) Determine whether the two broadband conditions are met, and if so, set the preferred network to broadband; if not, proceed to step d); c) Determine whether narrowband has been connected to the network, and set the preferred network to narrowband; otherwise, set it to broadband; d) Determine whether narrowband is connected to the network. If not, set the preferred network to broadband. Otherwise, proceed to step e); e) Determine whether the narrowband C1 is greater than or equal to Q1. If so, the preferred network is set to narrowband; otherwise, it is set to broadband.

[0042] like Figure 3 As shown, when the user prefers narrowband, the judgment steps are: i determine whether the narrowband network has been connected, the network has entered step ii, not the network then proceed to step iii; ii. Determine whether the narrowband C1 is greater than or equal to Q1, the preferred network is set to narrowband, otherwise proceed to step iv; iii. Determine whether the broadband is registered. If the registered preferred network is set to broadband, otherwise it is set to narrowband; iv. Determine whether the broadband is registered. If not, the preferred network is set to narrowband, otherwise proceed to step v; v. Determine whether the broadband meets the two conditions. If so, the preferred network is set to broadband; otherwise, it is set to narrowband.

[0043] With this preferred network switching method, narrowband can switch to broadband within 1.5 seconds when encountering network fluctuations, and broadband can switch to narrowband within 1 second when encountering network fluctuations. This ensures that when one mode of the network is unstable, the network can quickly respond and switch to the stable mode, ensuring that communication is always carried out on the better network mode.

[0044] The current group call processing flow of the No. 1 dual-mode terminal is as follows: The current group call processing flow of the No. 1 dual-mode terminal is as follows Figure 4 As shown, the two situations of outgoing and incoming calls of the current group are explained and processed respectively.

[0045] When the user presses the PPT key to initiate a call to the current group: 1) Determine whether the group call to the current group of the preferred network is successfully initiated. If yes, proceed to step 3); otherwise, proceed to step 2); 2) Determine whether another module group call is successfully initiated. If yes, proceed to step 4); otherwise, proceed to step 5); 3) Group call is established and maintained on the preferred network; 4) A group call is established and maintained on another module; 5) It prompts that the current group call has failed.

[0046] When the terminal receives an incoming call from the current group: A. Determine whether the incoming call signaling of the preferred network group arrives first. If so, proceed to step C; otherwise, proceed to step B. B. Wait for 1 second to see if the incoming call signaling from the preferred network group arrives. If so, proceed to step C; otherwise, proceed to step D. C. Respond to the current group call of the preferred network and maintain the group call on the preferred network; D. Respond to the current group call of another module and maintain the group call of another module.

[0047] Incoming and outgoing calls to the current group prioritize the preferred network mode, ensuring that on-duty group calls are based on a more reliable network with the highest quality services. If the preferred network mode becomes unavailable, the terminal automatically and quickly switches to another mode to respond or initiate the call, achieving user-imperceptible intelligent switching and maximizing the accuracy, stability, and sustainability of the current group's call service. This ensures that broadband and narrowband trunking services complement and back up each other, improving and guaranteeing the quality and success rate of on-duty calls.

[0048] Switching networks during a group call: The network switching strategy in the current group call means that if an unexpected interruption occurs in the current mode (such as disconnection from the network or system side abnormality), the fusion terminal will immediately call back the current group call in another mode in the call merge mode to keep the call going normally.

[0049] In traditional methods, call interruptions caused by network fluctuations often require the base station or server to initiate a delayed entry after the network is restored before the previous call can be restored. If no delayed entry is received during this period, all voice information of the group call will be lost. However, when the call is interrupted due to the network, the patented method will determine whether the other mode is available. If available, it will rejoin the previous call through call merging. The whole process can be completed within 1 second, and at most two words will be lost. Compared with the traditional method, the call content loss rate is significantly improved, which also reflects the complementary characteristics of the dual modes.

[0050] The present invention relates to the field of trunking communication and intercom. The relevant terms and operations are explained as follows: Current Group: refers to the talk group currently activated and used by the intercom device. The narrowband and broadband PoC converged terminals have one current group respectively.

[0051] Knob operation: refers to switching (changing) the current group of the intercom device, activating the new current group and initiating the new current group attachment operation to the system side; for broadband and narrowband converged terminals, the present invention proposes a broadband and narrowband synchronization current group method.

[0052] Pressing the PPT key operation generally refers to initiating a group call of the current group of the intercom device; for a broadband-narrow converged terminal, it is necessary to determine whether to initiate a narrowband or broadband PoC current group call, and the present invention proposes a corresponding method.

[0053] Preferred network: that is, which mode (narrowband or broadband PoC) is prioritized for responding to the broadband-narrowband converged terminal cluster service. The present invention proposes a method for determining the preferred network.

[0054] Explanation of abbreviations and terms used in the present invention: PDT: Police Digital Trunking TETRA: Terrestrial Evolved Trunked Radio B-Trunc: Broadband Trunking Communication PoC: Push to Talk over Cellular VoIP: Voice over Internet Protocol, voice transmission based on IP LTE: Long Term Evolution TD-LTE: Time Division LTE TDMA: Time division multiple access RSSI: Received Signal Strength Indication, received signal strength indication MCX: Mission Critical X, with X = PTT or X = Video or X = Data, mission critical intercom, video, data.

Claims

1. A method for implementing one-number dual-mode service processing on a broadband-narrowband converged terminal, characterized in that The following steps are involved: 1) When narrowband and broadband PoC converged terminals are connected to the same network or logged in with the same number, the user can select one of them as the preferred network. By default, narrowband is the preferred network. 2) Ensure that the wide and narrow bands remain consistent with the current group; 3) Determine the preferred network based on a strategy combining user preferences and automatic switching; 4) Develop the outbound call strategy for the current group; 5) Develop the inbound call strategy for the current group; 6) Formulate the network switching strategy for the current group call.

2. The method for implementing dual-mode service processing of a broadband-narrow converged terminal according to claim 1, characterized in that: The specific steps for ensuring that the wide and narrow bands maintain the same current group are: when the knob is not used to switch groups, the wide and narrow fusion terminal switches the current group of the other mode to the current group initially configured for the preferred network; when the knob switches the current group for the preferred network, the wide and narrow fusion terminal switches the current group of the other mode to the same current group.

3. The method for implementing dual-mode service processing of a broadband-narrow converged terminal according to claim 1, characterized in that: The strategy of determining the preferred network based on a combination of user preference and automatic switching includes: when narrowband is the preferred network, network switching is performed based on the comparison result of the narrowband signal field strength average with the set threshold; when broadband is the preferred network, network switching is performed based on the broadband network type, signal strength and ping value response with the PoC server.

4. The method for implementing dual-mode service processing of a broadband-narrow converged terminal according to claim 3, characterized in that: Users can select the preferred mode as the preferred network. When the network quality of the mode is good, the mode will be the preferred network. When the network quality of the mode is detected to be poor or abnormal, and the network condition and access status of the other mode are good, it will automatically switch to the other mode as the preferred network.

5. The method for implementing dual-mode service processing of a broadband-narrow converged terminal according to claim 3, characterized in that: The narrowband signal strength mean value is calculated as follows: the narrowband modem obtains the RSSI value every 500 milliseconds, and the average value C1 of the three most recent RSSI values ​​is used as the judgment. C1=(RSSI-1+RSSI-2+RSSI-3) / 3 When C1 < Q1, it means that the narrowband network is poor and cannot be used as a priority network option; When C1 ≥ Q1, it indicates that the narrowband network is good and can be used as the preferred network; The broadband and narrowband converged terminal provides an interface that can dynamically set the narrowband network quality threshold Q1 according to the scenario. The default value of Q1 is -90dBm.

6. A method for implementing one-number dual-mode service processing for a broadband-narrow converged terminal according to claim 3, characterized in that: The criteria for judging the broadband network type and signal strength are as follows: networks below 3G are not suitable as preferred networks; the 3G network signal strength must reach level 4; the 4G / 5G network signal strength must reach levels 2-4.

7. A method for implementing dual-mode service processing of a broadband-narrow converged terminal according to claim 6, characterized in that: The judgment standard of the ping value response with the PoC server is: the terminal regularly pings the PoC server, once per second by default. If the response time exceeds 100ms, the ping cycle is shortened. If the response time exceeds 100ms for 5 consecutive times, it is determined not to be a preferred network option. If the response time is within 100ms for 5 consecutive times, it is determined to be a preferred network option.

8. The method for implementing one-number dual-mode service processing for a broadband-narrow converged terminal according to claim 1, characterized in that: The current group call outgoing strategy is: when the broadband-narrow converged terminal is idle, press the PTT key to initiate a group call of the current group in the preferred network. If it fails, it automatically switches to initiate a group call of the current group in another mode.

9. The method for implementing one-number dual-mode service processing for a broadband-narrow converged terminal according to claim 1, characterized in that: The current group call incoming policy is: when the broadband and narrowband of the broadband-narrowband converged terminal are in the same current group, if another terminal initiates a group call to the current group, it will give priority to responding to the current group call incoming on the preferred network mode. If it fails to receive the call within a certain period of time, it will answer the group call on the other mode.

10. A method for implementing dual-mode service processing of a broadband-narrow converged terminal according to claim 1, characterized in that: The network switching strategy in the current group call is: if the current module is unexpectedly interrupted during the current group call, the converged terminal actively calls back the current group call in another module in a call merge mode to keep the call going normally.

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