Ground network and non-ground network converged communication method and device

Abstract

The invention relates to a converged communication method and device for a ground network and a non-ground network. The method comprises the following steps: a terminal detects the signal quality of a current ground network cell, and detects the signal quality of an adjacent ground network cell if the signal quality of the current ground network cell does not meet service requirements; if the signal quality of the adjacent ground network cell does not meet the service requirement, connecting a non-ground network cell; when non-ground network cell connection is carried out, the effective service duration of a non-ground network cell is calculated, and if the effective service duration meets the terminal data transmission duration, the ground network cell is switched to the non-ground network cell; and if the effective service duration does not meet the data transmission duration, establishing dual-link communication between the ground network cell and the non-ground network cell. According to the invention, the data transmission efficiency can be improved, and stable communication performance and energy consumption balance are realized.

Description

Technical Field

[0001] The present invention relates to the field of satellite communication technology, and in particular to a ground network and non-ground network integrated communication method and device. Background Art

[0002] In modern communication networks, the service experience of terminal devices depends largely on the coverage and performance of the ground network. However, a single ground network may not be able to provide stable and efficient services to the terminal in some cases, resulting in a decline in the terminal's service experience.

[0003] First, when the ground network is congested, if there are too many terminals in the cell, or a few terminals are performing high-traffic services, the network load will be too high, limiting the performance of other terminals. Second, the signal quality of the ground network is easily affected by the environment. For example, when the signal path loss is large or the interference is serious, the signal bit error rate increases, the modulation order decreases, and the peak performance of the terminal is limited.

[0004] In addition, when the load of the ground network cell is limited, or the connection between the terminal and the cell is affected by interference or excessive link loss, the uplink / downlink rate of the terminal will drop significantly. In this case, the ground network cell cannot provide sufficient data transmission rate for the terminal, resulting in a significant increase in service delays or response timeouts.

[0005] To solve the above problems, the collaboration between non-terrestrial networks (such as satellite networks) and terrestrial networks can improve the terminal's service experience in specific scenarios and ensure communication stability and data transmission rate. Summary of the invention

[0006] Based on this, it is necessary to provide a ground network and non-ground network fusion communication method and device that can integrate the non-ground network and the ground network through the collaboration between the non-ground network and the ground network when service delay or response timeout occurs in the ground network cell.

[0007] A terrestrial network and non-terrestrial network integrated communication method, the method comprising:

[0008] The terminal detects the signal quality of the current ground network cell. If the signal quality of the current ground network cell does not meet the service requirements, the terminal detects the signal quality of the adjacent ground network cell. If the signal quality of the adjacent ground network cell does not meet the service requirements, the terminal connects to a non-ground network cell.

[0009] When connecting to a non-ground network cell, the effective service duration of the non-ground network cell is calculated. If the effective service duration meets the terminal data transmission duration, the ground network cell is switched to the non-ground network cell. If the effective service duration does not meet the data transmission duration, dual-link communication between the ground network cell and the non-ground network cell is established.

[0010] A terrestrial network and non-terrestrial network integrated communication device, the device comprising:

[0011] The judgment module is used for the terminal to detect the signal quality of the current ground network cell. If the signal quality of the current ground network cell does not meet the service requirements, the signal quality of the adjacent ground network cell is detected; if the signal quality of the adjacent ground network cell does not meet the service requirements, a connection to a non-ground network cell is performed;

[0012] The switching module is used to calculate the effective service duration of the non-ground network cell when connecting to a non-ground network cell. If the effective service duration meets the terminal data transmission duration, the ground network cell is switched to the non-ground network cell; if the effective service duration does not meet the data transmission duration, dual-link communication between the ground network cell and the non-ground network cell is established.

[0013] The above-mentioned ground network and non-ground network integrated communication method and device detect the signal quality of the current ground network cell through the terminal. If the signal quality of the current ground network cell does not meet the service requirements, the signal quality of the adjacent ground network cell is detected; if the signal quality of the adjacent ground network cell does not meet the service requirements, the non-ground network cell is connected; when connecting the non-ground network cell, the effective service time of the non-ground network cell is calculated. If the effective service time meets the terminal data transmission time, the ground network cell is switched to the non-ground network cell; if the effective service time does not meet the data transmission time, dual-link communication between the ground network cell and the non-ground network cell is established.

[0014] Through effective condition judgment, the present invention enables the terminal to dynamically switch between the ground network and the non-ground network, so that the optimal network can be selected according to the actual situation, avoiding unnecessary resources and improving network efficiency. By evaluating the effective service duration of the non-ground network cell, the terminal can ensure that there will be no interruption during the data transmission process, thereby improving the user experience. In the case of poor signal quality or insufficient service duration, dual-connection communication allows the terminal to use two networks for data transmission at the same time, reducing the pressure of a single network load, thereby achieving more stable communication performance and energy consumption balance. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0016] Figure 1 A schematic diagram of a flow chart of a method for integrating communication between a ground network and a non-ground network in one embodiment;

[0017] Figure 2 A schematic diagram of communication in a gateway forwarding mode in an embodiment;

[0018] Figure 3 is a communication schematic diagram in a base station direct connection mode in an embodiment;

[0019] Figure 4 A structural block diagram of a ground network and non-ground network integrated communication device in one embodiment;

[0020] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] It should be noted that in the present invention, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0023] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0024] The following will describe the implementation of the present invention in detail with reference to the accompanying drawings in the embodiment diagram of the present invention.

[0025] Example 1

[0026] This embodiment discloses a method for integrating communication between a ground network and a non-ground network. By judging effective conditions, the terminal can dynamically switch between the ground network and the non-ground network, so that the optimal network can be selected according to the actual situation, avoiding unnecessary resources and improving network efficiency. By evaluating the effective service time of the non-ground network cell, the terminal can ensure that there will be no interruption during the data transmission process, thereby improving the user experience. In the case of poor signal quality or insufficient service time, dual-connection communication allows the terminal to use two networks for data transmission at the same time, reducing the pressure on the single network load, thereby achieving more stable communication performance and energy consumption balance.

[0027] refer to Figure 1 The ground network and non-ground network integrated communication method in this embodiment includes the following steps:

[0028] Step 201, the terminal detects the signal quality of the current ground network cell. If the signal quality of the current ground network cell does not meet the service requirements, the terminal detects the signal quality of the adjacent ground network cell; if the signal quality of the adjacent ground network cell does not meet the service requirements, the terminal connects to a non-ground network cell.

[0029] Step 202, when connecting to a non-ground network cell, calculate the effective service duration of the non-ground network cell. If the effective service duration meets the terminal data transmission duration, switch the ground network cell to the non-ground network cell; if the effective service duration does not meet the data transmission duration, establish dual-link communication between the ground network cell and the non-ground network cell.

[0030] In the specific implementation process of step 201, the terminal detects the signal quality of the current ground network cell. When the current ground network cell has low uplink and downlink rates, and after the terminal applies for resource scheduling, if it cannot obtain sufficient resources to support its operation within a period of time, it is determined that the communication of the current ground network cell is restricted. The terminal detects the signal quality of the adjacent ground network cell. If the signal quality of the adjacent ground network cell does not meet the conditions for switching and cannot provide effective services, the terminal searches for non-ground network cells and connects to non-ground network cells. It is worth noting that under normal circumstances, the terminal generally disables the measurement and search of non-ground network cells to reduce power consumption and terminal computing overhead. Only when the communication of the current ground network cell is restricted, the detection is enabled.

[0031] In the specific implementation process of step 202, when there is a non-terrestrial network cell in the environment and the signal quality meets the set signal strength threshold, the effective service duration of the non-terrestrial network cell is calculated.

[0032] When calculating the effective service duration of the non-terrestrial network cell, the switching threshold can be set according to the transmission duration required for the remaining data of the terminal; the effective service duration of more than one non-terrestrial network cell can be calculated based on the entry time and departure time of the satellite; if the effective service duration is greater than or equal to the switching threshold, the terrestrial network cell is switched to the non-terrestrial network cell; if the effective service duration does not meet the data transmission duration, a dual-link communication between the terrestrial network cell and the non-terrestrial network cell is established. It can be understood that the setting of the signal strength threshold can ensure that the terminal detects that the signal of the non-terrestrial network is stable and of high quality in the current environment, thereby providing a reliable connection and avoiding the problem of communication interruption or unstable transmission caused by switching to the non-terrestrial network when the signal quality is poor. The setting of the switching threshold can ensure that the effective service duration of the non-terrestrial network is sufficient to support the remaining data transmission. When the terminal switches to the non-terrestrial network, it can ensure that more than one non-terrestrial network cell can provide stable data transmission, reduce frequent network switching and repeated resource applications, and improve user experience. If the effective service duration is less than the switching threshold, it means that the continuous service duration of one or more non-terrestrial network cells is insufficient to support the remaining data transmission completed by the terminal. In this case, dual-link communication between the terrestrial network cell and the non-terrestrial network cell is established to ensure the stability and reliability of data transmission.

[0033] Specifically, the signal quality of the non-terrestrial network cell includes but is not limited to signal strength RSRP, signal quality RSRQ, and signal-to-noise ratio SINR.

[0034] When calculating the effective service time, for non-ground network cells where signals can be detected, they are sorted from good to bad according to signal quality to obtain a first sorting table; for non-ground network cells where signals cannot be detected, they are sorted from near to far according to the projection points to obtain a second sorting table; the second sorting table is inserted into the end of the first sorting table, and then based on the entry time and departure time, the effective service time during which more than one non-ground network cell can provide continuous service is calculated.

[0035] In addition, a continuous threshold is set. If the switching time of adjacent non-ground network cells is less than or equal to the continuous threshold, the adjacent non-ground network cells are considered to be continuous. The total duration of continuous service of adjacent non-ground network cells can be calculated based on the entry time and the departure time. In this way, the non-ground networks in the table are calculated step by step. When the switching time of adjacent non-ground network cells is calculated to be greater than the continuous threshold, the two non-ground network cells are considered to be discontinuous; then the total duration of continuous service of more than one non-ground network cell calculated is used as the effective service duration, and the effective service duration is judged. If the effective service duration is greater than or equal to the switching threshold, the ground network cell is switched to the non-ground network cell; if the effective service duration does not meet the data transmission duration, dual-link communication between the ground network cell and the non-ground network cell is established.

[0036] In one embodiment, when establishing dual-link communication between a ground network cell and a non-ground network cell, the non-ground network service cell may be disconnected due to the short sustainable service time of the non-ground network cell. Therefore, it is necessary to maintain the control plane in the ground network to keep the connection between the terminal and the ground network core network continuous; the data interaction between the terminal and the network is mainly through the ground network, and the transmission of the terminal data is divided into two parts, which are maintained in the ground network and the non-ground network respectively. The aggregated data is fragmented and distributed to the ground network and the non-ground network, which are sent and received by the ground network cell and the non-ground network cell respectively.

[0037] It can be understood that since the terminal IP is maintained in the ground network core network, and in order to reduce the data processing overhead of the non-ground network, the data sent by the terminal to the non-ground network cell is aggregated by the ground network, and then the data is forwarded uniformly to maximize the use of spectrum resources. The reason for data aggregation is that the data sent by the terminal to the base station is composed of data from different applications and processes in the upper layer. In the physical layer, the data is combined into a queue data and continuously sent to the base station. Since the air interface data is sent alternately to the ground network cell and the non-ground network cell, the continuous queue data will be split into two parts. The data of these two parts need to be combined into one part to ensure the validity of the data. If aggregation is not performed, the data sent by the terminal to the base station needs to be sent continuously, and the data will be marked and merged into a whole data after passing through layer 2, and cannot be distinguished at the physical layer. If it is distinguished at a higher layer, the resource utilization rate will be insufficient due to the inability to obtain the resource scheduling information of the network configuration, which may cause some data to be blocked in the terminal physical layer and cannot be sent to the network (due to the small number of resources allocated to the terminal by the ground network cell or the non-ground network cell), resulting in data transmission timeout.

[0038] In addition, after the data is returned from the terminal and aggregated in the ground network, the aggregated data will be forwarded to the application server. Then, the application server processes the data and sends it back to the ground network. Then, the ground network will split the data as needed and allocate it to the ground network cell and the non-ground network cell respectively. Finally, these cells will transmit the data to the corresponding terminal. After receiving the data, the terminal will also have a data combination process.

[0039] In one of the embodiments, after dual-link communication between a terrestrial network cell and a non-terrestrial network cell is established, if the uplink resources or downlink resources that can be allocated to the terrestrial network cell or the non-terrestrial network cell within a period are too small, data is not transmitted through the link.

[0040] Specifically, if the uplink resources or downlink resources that can be allocated to a ground network cell or a non-ground network cell within a period are too small, the data of the terminal or the cell will not be transmitted through the corresponding link to avoid the overhead of data segmentation and aggregation. Furthermore, for non-ground network cells, you can choose not to allocate the corresponding resources to the terminal; for ground network cells, you still need to allocate necessary resources to ensure the normal transmission of signaling. If the allocatable resources of the ground network cell and the non-ground network cell are both less than the preset threshold, the link with relatively more resources should be reserved for data transmission.

[0041] In one of the embodiments, when dual-link communication is performed between a terrestrial network cell and a non-terrestrial network cell, a gateway forwarding mode or a base station direct connection mode is used for communication.

[0042] Specifically, according to the capabilities of the ground network cell base station, when performing dual-link communication between the ground network cell and the non-ground network cell, two communication modes, namely, a gateway forwarding mode and a base station direct connection mode, are proposed.

[0043] Among them, reference Figure 2 As shown in the figure, in the gateway forwarding mode, the ground network cell base station does not have the ability to communicate directly with the non-ground network cell base station, and needs to rely on the dedicated gateway station set up on the ground. Specifically, the ground network cell base station and the gateway station exchange data, and the gateway station then transmits data with the non-ground network cell base station. In this mode, the communication between the ground network and the non-ground network is more flexible; it can better centrally handle the coordination of cross-network communications, which is convenient for management and optimization at the system level; the system has strong compatibility and good scalability, which can meet the communication needs in different scenarios without the need to upgrade the existing ground base station network on a large scale.

[0044] refer to Figure 3As shown in the figure, in the base station direct connection mode, the ground network cell base station has the ability to communicate directly with the non-ground network cell base station, and multiple ground network cells may share a cell base station with this capability, without the need for each ground network cell base station to have such capability. In this mode, data does not need to pass through the gateway or the routing within the non-ground network, which can significantly reduce data transmission delay; improve data transmission efficiency; reduce network overhead, reduce the burden on the network and improve resource utilization; optimize network performance, enhance the stability and reliability of data transmission; and improve user experience.

[0045] In one embodiment, the method further includes: setting a condition for exiting the dual-link communication between the terrestrial network cell and the non-terrestrial network cell, which is:

[0046] When the terminal enters sleep mode, the data service is terminated, the connection with the non-ground network cell is disconnected, and the ground network cell enters an idle state; or when the ground network is restored and the resources provided by the ground network cell meet the terminal needs, the connection with the non-ground network cell is disconnected and only the ground network cell is connected; or when the effective service time of the non-ground network cell meets the switching threshold, the non-ground network cell switching is executed; or when the signal quality of the non-ground network cell deteriorates and cannot meet the connection conditions, the connection with the non-ground network cell is disconnected; or when the ground network cell deteriorates and there are no other ground network neighboring cells to switch to, the non-ground network cell switching is executed.

[0047] In addition, except for the case where the service quality of the terrestrial network cell is poor, when the service quality of the terrestrial network cell is excellent, if the terminal needs to perform big data services, the terminal can also simultaneously establish a link with the non-terrestrial network to increase the maximum data rate of the terminal.

[0048] Although this embodiment Figure 1 The steps in the process are shown in sequence as indicated by the arrows, but the steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order restriction for the execution of the steps, and the steps can be executed in other orders. Figure 1 At least part of the steps may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily executed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least part of the sub-steps or stages of other steps.

[0049] Example 2

[0050] Based on the ground network and non-ground network fusion communication method in Example 1, this embodiment discloses a ground network and non-ground network fusion communication device, such as Figure 4As shown, the ground network and non-ground network integrated communication device includes: a judgment module 401 and a switching module 402, wherein:

[0051] The judgment module 401 is used for the terminal to detect the signal quality of the current ground network cell. If the signal quality of the current ground network cell does not meet the service requirements, the signal quality of the adjacent ground network cell is detected; if the signal quality of the adjacent ground network cell does not meet the service requirements, a connection to a non-ground network cell is performed;

[0052] The switching module 402 is used to calculate the effective service duration of the non-ground network cell when connecting to a non-ground network cell. If the effective service duration meets the terminal data transmission duration, the ground network cell is switched to the non-ground network cell; if the effective service duration does not meet the data transmission duration, dual-link communication between the ground network cell and the non-ground network cell is established.

[0053] In this embodiment, the specific working process and working principle of the judgment module 401 and the switching module 402 are the same as those in the method of embodiment 1, so they are not described in detail in this embodiment. Each unit module can be implemented in whole or in part by software, hardware, or a combination thereof, and each unit module can be embedded in or independent of a processor in a computer device in the form of hardware, or can be stored in a memory in a computer device in the form of software, so that the processor can call and execute operations corresponding to each of the above unit modules.

[0054] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

[0055] The technical features of the above embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0056] The above-mentioned embodiments only express several implementation modes of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention. It should be pointed out that, for a person of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the attached claims.

Claims

1. A terrestrial network and non-terrestrial network integrated communication method, characterized in that: The method comprises: The terminal detects the signal quality of the current ground network cell. If the signal quality of the current ground network cell does not meet the service requirements, the terminal detects the signal quality of the adjacent ground network cell. If the signal quality of the adjacent ground network cell does not meet the service requirements, the terminal connects to a non-ground network cell. When connecting to a non-ground network cell, the effective service duration of the non-ground network cell is calculated. If the effective service duration meets the terminal data transmission duration, the ground network cell is switched to the non-ground network cell. If the effective service duration does not meet the data transmission duration, dual-link communication between the ground network cell and the non-ground network cell is established.

2. The terrestrial network and non-terrestrial network integrated communication method according to claim 1, characterized in that: Calculating the effective service duration of the non-terrestrial network cell, and if the effective service duration satisfies the terminal data transmission duration, switching the terrestrial network cell to the non-terrestrial network cell, includes: Set the switching threshold according to the transmission time required for the remaining data of the terminal; The effective service duration of one or more non-terrestrial network cells is calculated based on the entry time and departure time of the satellite; if the effective service duration is greater than or equal to the switching threshold, the terrestrial network cell is switched to the non-terrestrial network cell.

3. The terrestrial network and non-terrestrial network integrated communication method according to claim 2, characterized in that: The effective service duration of one or more non-terrestrial network cells is calculated based on the satellite's entry and departure times, including: For non-terrestrial network cells where signals can be detected, the cells are sorted according to the signal quality to obtain a first sorting table; for non-terrestrial network cells where signals cannot be detected, the cells are sorted according to the distance of the projection point to obtain a second sorting table; Insert the second sorting table to the end of the first sorting table; then calculate the effective service duration during which more than one non-terrestrial network cell can continuously provide service based on the entry time and the departure time.

4. The terrestrial network and non-terrestrial network integrated communication method according to claim 1, characterized in that: When dual-link communication between a ground network cell and a non-ground network cell is established, data interaction between the terminal and the network is mainly through the ground network, and data transmission is divided into two parts, which are maintained in the ground network and the non-ground network respectively.

5. The terrestrial network and non-terrestrial network integrated communication method according to claim 4, characterized in that: Data interaction between the terminal and the network is mainly through the ground network, including: The terminal IP is maintained in the ground network core network, and the data to be transmitted is aggregated in the ground network, and then the data is forwarded uniformly.

6. The terrestrial network and non-terrestrial network integrated communication method according to claim 5, characterized in that: Data transmission is divided into two parts, maintained on the ground network and non-ground network, including: The aggregated data is segmented and distributed to the ground network and the non-ground network, and sent and received by the ground network cell and the non-ground network cell respectively.

7. The terrestrial network and non-terrestrial network integrated communication method according to claim 6, characterized in that: After establishing dual-link communication between the terrestrial network cell and the non-terrestrial network cell, if the uplink resources or downlink resources that can be allocated to the terrestrial network cell or the non-terrestrial network cell within a period are too small, data is not transmitted through the link.

8. The terrestrial network and non-terrestrial network integrated communication method according to claim 6, characterized in that: When dual-link communication is performed between a ground network cell and a non-ground network cell, communication is performed in a gateway forwarding mode or a base station direct connection mode.

9. The terrestrial network and non-terrestrial network integrated communication method according to any one of claims 1 to 8, characterized in that: Also includes: The conditions for exiting the dual-link communication of the terrestrial network cell and the non-terrestrial network cell are set as follows: When the terminal goes into sleep mode, or the ground network recovers and meets demand, or the non-ground network service duration or signal quality does not meet standards, or there is no switchable neighboring area on the ground network, it will switch or disconnect between the ground and non-ground networks based on actual conditions.

10. A terrestrial network and non-terrestrial network integrated communication device, characterized in that: The device comprises: The judgment module is used for the terminal to detect the signal quality of the current ground network cell. If the signal quality of the current ground network cell does not meet the service requirements, the signal quality of the adjacent ground network cell is detected; if the signal quality of the adjacent ground network cell does not meet the service requirements, a connection to a non-ground network cell is performed; The switching module is used to calculate the effective service duration of the non-ground network cell when connecting to a non-ground network cell. If the effective service duration meets the terminal data transmission duration, the ground network cell is switched to the non-ground network cell; if the effective service duration does not meet the data transmission duration, dual-link communication between the ground network cell and the non-ground network cell is established.

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