Random access method, random access system and equipment for satellite communication and medium

Abstract

The invention discloses a random access method and system for satellite communication, equipment and a medium, and the method comprises the steps: determining the total number of user equipment in a user equipment group, and selecting a plurality of pilot frequency patterns from a pilot frequency pattern library; selecting an optimal pilot frequency pattern from the plurality of pilot frequency patterns according to the success rate of accessing the satellite by each user equipment in the user equipment group; and each user equipment in the user equipment group sends a pilot signal to the satellite according to the optimal pilot pattern. The success rate of accessing the satellite by the user equipment is improved.

Description

Technical Field

[0001] The present application relates to the field of satellite Internet technology, and in particular to a random access method, random access system, device and medium for satellite communication. Background Art

[0002] The design of traditional satellite uplink access channels is limited by the time-frequency dimension and may not be able to flexibly respond to different signal propagation conditions and interference situations in a dynamically changing environment. In satellite communication scenarios, the design of the existing satellite uplink access channel frequency hopping pattern does not consider the spatial domain isolation capability provided by satellite beam scheduling. In the face of high-density users, the satellite uplink access channel faces the problem of resource competition, which affects the success rate of random access. Summary of the invention

[0003] In view of this, the present application provides a random access method, random access system, device and medium for satellite communication.

[0004] The present application discloses a random access method for satellite communication, which comprises: Determine the total number of user equipment in the user equipment group, and select a number of pilot patterns corresponding to the user equipment group from a pilot pattern library; each of the pilot patterns is related to the total number of user equipment in the user equipment group, time, and frequency; Selecting an optimal pilot pattern from the plurality of pilot patterns according to a success rate of each user equipment in the user equipment group accessing the satellite; Each user equipment in the user equipment group sends the pilot signal to the satellite according to the optimal pilot pattern; the pilot signal is used to indicate a random access request sent by each user equipment in the user equipment group to the satellite.

[0005] Furthermore, the method for acquiring the pilot pattern library is: Establishing a plurality of pilot patterns corresponding to the user equipment group according to the number of subcarriers, the subcarrier spacing, and the number of pilot signals sent by each user equipment in the user equipment group to the satellite each time; A plurality of pilot patterns corresponding to all the user equipment groups together constitute the pilot pattern library.

[0006] Further, the establishing of a plurality of pilot patterns corresponding to the user equipment group according to the number of subcarriers, the subcarrier spacing, and the number of pilot signals sent by each user equipment in the user equipment group to the satellite each time includes: Determine the total number of user equipments corresponding to each pilot pattern according to the number of user equipments in each of the multiple cells, so as to establish a plurality of pilot patterns corresponding to the user equipment group; the multiple cells are located in the same beam position in the satellite transmission beam; each pilot pattern is used to provide time and frequency for all user equipments in the corresponding user equipment group to access the satellite; The plurality of pilot patterns are obtained according to the frequency and time at which each user equipment in the user equipment group accesses the satellite, and a preset frequency hopping rule; the preset frequency hopping rule is associated with different frequency hopping intervals.

[0007] Further, the establishing of a plurality of pilot patterns corresponding to the user equipment group according to the number of subcarriers, the subcarrier spacing, and the number of pilot signals sent by each user equipment in the user equipment group to the satellite each time includes: According to the number of wave positions within the satellite coverage, the area of ​​each wave position, and the spatial density distribution function corresponding to each wave position, the number of all user equipment in each wave position is obtained; Divide each of the wave positions into a plurality of cells, and obtain the number of user equipment in each cell according to the number of all user equipment in each of the wave positions; The number of user devices corresponding to each pilot pattern is determined according to the number of user devices in each cell, the total frequency band resources allocated to each cell, the frequency band resources used by each pilot pattern, the total time resources allocated to each cell, and the time resources used by each pilot pattern.

[0008] Furthermore, the method for acquiring the frequency and time at which each user equipment in the user equipment group accesses the satellite includes: According to the number of subcarriers and the subcarrier spacing, obtaining a frequency at which each user equipment corresponding to each pilot pattern accesses the satellite; The time for each user equipment corresponding to each pilot pattern to access the satellite is obtained according to the number of pilot signals sent to the satellite by each user equipment corresponding to each pilot pattern and the time required to send each pilot signal.

[0009] Further, selecting an optimal pilot pattern from the plurality of pilot patterns according to a success rate of each user equipment in the user equipment group accessing a satellite comprises: Obtaining a success rate of each user equipment in the user equipment group accessing a satellite; According to the success rate of each user equipment in the user equipment group accessing the satellite, an optimal pilot pattern is selected from the plurality of pilot patterns corresponding to the user equipment group.

[0010] Further, the obtaining the success rate of each user equipment in the user equipment group accessing the satellite includes: taking a signal transmission response between each user equipment in the user equipment group and the satellite as channel fading; Obtaining, according to the channel fading and the signal-to-noise ratio, an error detection rate of the satellite for the signal sent by each of the user equipments; The success rate of each user equipment in the user equipment group accessing the satellite is obtained according to the false detection rate of the signal sent by each user equipment received by the satellite.

[0011] Further, selecting the best pilot pattern from the plurality of pilot patterns corresponding to the user equipment group according to the success rate of each user equipment in the user equipment group accessing the satellite includes: The success rate of each user equipment in the user equipment group accessing the satellite is summed, and the maximum value of the summed result is obtained to select the best pilot pattern from the several pilot patterns corresponding to the user equipment group.

[0012] Further, the summing up the success rate of each user equipment in the user equipment group accessing the satellite and maximizing the summed result to select the best pilot pattern from the plurality of pilot patterns corresponding to the user equipment group includes: The success rate of each user equipment in the user equipment group accessing the satellite is summed, and the maximum value of the summation result is obtained under the premise of satisfying the constraint conditions, so as to select the optimal pilot pattern from the several pilot patterns corresponding to the user equipment group; the constraint conditions include constraints on the number of all user equipment corresponding to each pilot pattern, the success rate of each user equipment corresponding to each pilot pattern accessing the satellite, and the interference between the user equipment corresponding to each pilot pattern.

[0013] Further, each user equipment in the user equipment group sends the pilot signal to the satellite according to the optimal pilot pattern, including: All user equipments in each user equipment group determine the time and frequency of sending the pilot signal to the satellite according to the corresponding optimal pilot pattern; All user equipments in each of the user equipment groups transmit the pilot signal to the satellite within the determined time and frequency.

[0014] Furthermore, it also includes: Inputting the pilot signal sent by all user equipments in the user equipment group to the satellite into a sub-band filter for sub-band filtering, completing filtering and shaping, and generating a baseband waveform; The baseband waveform is sent to the satellite after being processed by correlation; the correlation processing includes digital-to-analog conversion and radio frequency amplification.

[0015] Furthermore, the method for configuring the sub-band filter comprises: Estimate the detection success rate of the UFMC symbol according to the key parameters of the subband filter, the signal transmission response and the signal peak-to-average ratio; the key parameters include type, length, number of subbands and sideband suppression ratio; Obtaining a UFMC time efficiency according to a ratio of a length of the subband filter to the UFMC symbol; Obtaining an uplink random access channel capacity according to the detection success rate of the UFMC symbol and the UFMC time efficiency; According to the uplink random access channel capacity, key parameters of the optimized subband filter are obtained.

[0016] Furthermore, obtaining the optimized key parameters of the subband filter according to the uplink random access channel capacity includes: Under the premise of satisfying preset constraints, the uplink random access channel capacity is maximized to obtain the optimized key parameters of the subband filter; the preset constraints include that the Hessian matrix is ​​greater than zero, and the Hessian matrix is ​​determined according to the uplink random access channel capacity.

[0017] Furthermore, the method for obtaining the signal transmission response includes: The signal transmission response is obtained according to the path loss between the satellite and the user equipment, the scintillation effect, the atmospheric absorption, the impulse response function of the transmission delay, the transmission delay, the Doppler frequency shift, the TDL model in the small-scale fading, the influence of the onboard radio frequency device, and the phased array antenna array response.

[0018] The present application also discloses a random access system for satellite communication, which comprises: A pilot pattern selection module, used to determine the total number of user equipment in the user equipment group, and select a number of pilot patterns corresponding to the user equipment group from a pilot pattern library; each of the pilot patterns is related to the total number of user equipment in the user equipment group, time, and frequency; An optimal pilot pattern selection module, configured to select an optimal pilot pattern from the plurality of pilot patterns according to a success rate of each user equipment in the user equipment group accessing a satellite; A pilot signal sending module is used for each user equipment in the user equipment group to send the pilot signal to the satellite according to the optimal pilot pattern; the pilot signal is used to indicate a random access request sent by each user equipment in the user equipment group to the satellite.

[0019] The present application also discloses an electronic device, including a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the random access method for satellite communication described above is implemented.

[0020] The present application also discloses a computer-readable storage medium, which includes a computer program or instruction. When the computer program or instruction is executed on a computer, the computer executes the random access method for satellite communication described above.

[0021] Due to the adoption of the above technical solution, the present application has the following advantages: in the satellite Internet of Things communication scenario, the random access success rate and resource utilization rate of the satellite uplink access channel are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the embodiments of the present application. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0023] Figure 1 A schematic diagram of a random access method for satellite communication according to an embodiment of the present application; FIG. 2( a ) is a schematic diagram of a pilot pattern sample for one user equipment according to an embodiment of the present application; FIG2( b ) is a schematic diagram of a pilot pattern sample for three user equipments according to an embodiment of the present application; FIG3( a ) is a schematic diagram of a pilot pattern sample for six user equipments according to an embodiment of the present application; FIG3( b ) is a schematic diagram of another pilot pattern example for six user equipments according to an embodiment of the present application; FIG3( c ) is a schematic diagram of another pilot pattern sample for 6 user equipments according to an embodiment of the present application; FIG4(a) is a schematic diagram of a pilot pattern example of 12 subcarriers under 12 user equipments in an embodiment of the present application; FIG4( b ) is a schematic diagram of a pilot pattern example of 36 subcarriers in the case of 12 user equipments according to an embodiment of the present application; Figure 5A curve diagram showing the variation of the error detection rate versus signal ratio of a narrowband physical random access channel in an embodiment of the present application; Figure 6 A block diagram of a random access system for satellite communication according to an embodiment of the present application; Figure 7 A block diagram of an electronic device according to an embodiment of the present application. DETAILED DESCRIPTION

[0024] The present application is further described in conjunction with the accompanying drawings and embodiments, and the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by ordinary technicians in this field should fall within the scope of protection of the embodiments of the present application.

[0025] The technical problem to be solved in this application is to improve the random access success rate and resource utilization rate of the satellite uplink access channel in the satellite Internet of Things communication scenario. During the satellite phased array agile beam service cycle, for ground user equipment under different beams, there are differences and commonalities in the communication angle, signal round-trip delay, Doppler frequency shift, etc. And as the satellite moves, the channel conditions gradually change. Utilize the prior relative position information of the satellite and the receiving wave position, reasonably and differentially allocate resources, utilize the spatial domain isolation brought by different beams and cell divisions, reduce interference, and improve the overall time-frequency resource efficiency. In the current Internet of Things communication system, CP-OFDM (Cyclic Prefix Orthogonal Frequency Division Multiplexing) / SC-FDMA (Single-Carrier Frequency-Division Multiple Access) waveforms are generally used, and the use of cyclic prefixes seriously affects the time-frequency resource efficiency. The candidate UFMC (Universal Filtered Multi-Carrier) waveform has certain time-frequency robustness without using cyclic prefixes, which effectively improves resource utilization efficiency. Therefore, how to achieve on-demand automatic adjustment of the subband filter parameter configuration that generates the UFMC waveform is the key to solving the inflexible and low efficiency of satellite uplink access channel time-frequency resource utilization. The key issues are as follows: (1) Design of NPRACH (Narrowband Physical Random Access Channel) frequency hopping pattern based on satellite communication scenario: The NPRACH frequency hopping pattern specified in the current 3GPP (3rd Generation Partnership Project) protocol distinguishes different random access user devices by dividing time and frequency resources. In the satellite communication scenario, the isolation of different user devices in the spatial domain can be achieved through different beams and cell divisions. Reasonable use of the characteristics of this scenario and construction of space-time-frequency hopping patterns are the key to improving the overall time-frequency resource efficiency.

[0026] (2) Adaptively adjusted high-efficiency UFMC waveform: The CP-OFDM waveform currently used generally has room for improvement in signal utilization efficiency because its cyclic prefix (CP) does not transmit additional valid information. As a candidate waveform for 5G, UFMC has a certain improvement in time resource utilization efficiency because it does not use CP. At the same time, the UFMC waveform has different anti-time and frequency deviation capabilities under different filter parameter configurations. Adjusting the UFMC filter parameter configuration in a timely manner according to different communication conditions is the key to efficiently realizing the UFMC waveform's inherent anti-interference capability.

[0027] In view of the above technical problems, see Figure 1 , an embodiment of the present application provides a random access method for satellite communication, which includes: Step 101: Determine the total number of user equipments in a user equipment group, and select several pilot patterns corresponding to the user equipment group from a pilot pattern library; each pilot pattern is related to the total number of user equipments in the user equipment group, time and frequency.

[0028] Each user equipment group consists of several user equipments, and each user equipment group corresponds to several pilot patterns.

[0029] In one embodiment of the present application, a method for acquiring a pilot pattern library is as follows: based on the number of subcarriers, the subcarrier spacing, and the number of pilot signals sent by each user device in the user device group to the satellite each time, a plurality of pilot patterns corresponding to the user device group are established; and a plurality of pilot patterns corresponding to all user device groups are collectively combined to form a pilot pattern library.

[0030] In one embodiment of the present application, a plurality of pilot patterns corresponding to the user equipment group are established according to the number of subcarriers, the subcarrier spacing, and the number of pilot signals sent by each user equipment in the user equipment group to the satellite each time, including: According to the number of user devices in each of the multiple cells, the total number of user devices corresponding to each pilot pattern is determined to establish several pilot patterns corresponding to the user device group; the multiple cells are located in the same wave position in the satellite transmission beam; each pilot pattern is used to provide the time and frequency for all user devices in the corresponding user device group to access the satellite; according to the frequency and time of each user device in the user device group accessing the satellite, and the preset frequency hopping rule, several pilot patterns are obtained; the preset frequency hopping rule is associated with different frequency hopping intervals. Among them, several pilot patterns are designed for each user device group, and each pilot pattern in the several pilot patterns is used to indicate the time and frequency of all user devices in the user device group it serves (corresponds to) to access the satellite. Since the number of users in each cell may vary in actual situations, corresponding pilot patterns are established for different application scenarios (different user device groups) to provide references for accessing the satellite for all user devices in the cells that need to provide services.

[0031] In one embodiment of the present application, a plurality of pilot patterns corresponding to the user equipment group are established according to the number of subcarriers, the subcarrier spacing, and the number of pilot signals sent by each user equipment in the user equipment group to the satellite each time, including: According to the number of wave positions within the satellite coverage area, the area of ​​each wave position, and the spatial density distribution function corresponding to each wave position, the number of all user devices in each wave position is obtained; each wave position is divided into multiple cells, and the number of user devices in each cell is obtained according to the number of user devices in each cell, the total frequency band resources allocated to each cell, the frequency band resources used by each pilot pattern, the total time resources allocated to each cell, and the time resources used by each pilot pattern, the number of user devices corresponding to each pilot pattern is determined.

[0032] Specifically, based on the geographic distribution data of global user devices, we can combine the original data provided by authoritative data sources (such as ITU (International Telecommunication Union), GSMA (Global System for Mobile Communications Association) or IoT Analytics, etc.), use GIS (Geographic Information System) for data processing and spatial analysis, calculate the user device density per unit area on a global scale, and express it as a spatial density distribution function. Specifically, first obtain the geographic distribution information of user devices through authoritative data sources, including the number and spatial location of devices in each region. Subsequently, with the help of GIS tools, the earth's surface is divided into multiple spatial units through geographic statistical methods (such as grid division or Thiessen polygons), and the device density of each unit is calculated. On this basis, statistical models such as KDE (Kernel Density Estimation) are introduced to convert discrete device location data into continuous spatial density distribution, and finally form a global spatial density distribution function, which is recorded as .

[0033] Suppose that the satellite Internet system is divided into two parts: , The area of ​​a wave position is , and The spatial density distribution function corresponding to the wave position Multiplying them gives Number of user devices in a wave .

[0034]

[0035] The first The wave position is divided into For the sake of simplicity, it is assumed here that Within a wave The number of user equipments in each cell is the same, denoted as ,but:

[0036] The number of devices served by each pilot pattern is , by the number of devices in the cell , the total frequency bandwidth resources allocated to the cell , the frequency band resources (bandwidth) used by each pilot pattern , the total time resources allocated to the cell , the time resources used by each pilot pattern The calculation formula is:

[0037] in, Obtained from upper-layer resource scheduling information, Referring to the current protocol, it is generally set to 45kHz.

[0038] In one embodiment of the present application, a method for acquiring the frequency and time at which each user equipment in a user equipment group accesses a satellite includes: According to the number of subcarriers and the subcarrier spacing, the frequency at which each user device corresponding to each pilot pattern accesses the satellite is obtained; according to the number of pilot signals sent to the satellite each time by each user device corresponding to each pilot pattern and the time required to send each pilot signal, the time at which each user device corresponding to each pilot pattern accesses the satellite is obtained.

[0039] Specifically, on the uplink from the user equipment to the satellite, multiple groups of different pilot signals are designed, and the frequency point, time interval, frequency interval, and the distribution of each frequency point of each group of pilot signals need to be set in each group of pilot signals. For example, referring to Figure 2 (a), the embodiment of the present application provides a pilot pattern for one user equipment, the horizontal axis t represents time, the vertical axis f represents frequency, the width of each rectangle represents the carrier spacing, the length of each rectangle is equal to the duration of one symbol, and the number of rectangles in each row on the time axis is equal to the number of symbols. Each colored rectangle indicates that the user equipment can send a pilot signal within the time and frequency corresponding to the colored rectangle. Each colored rectangle corresponds to a user equipment. In Figure 2 (a), according to the direction of increasing time, the first colored rectangle to the fourth colored rectangle are a group, which represents that the user equipment sends 4 pilot signals to the satellite continuously each time. A pilot signal is sent through a symbol each time, and the duration of sending a pilot signal is the symbol duration in Table 1.

[0040] In the case of a small number of devices (no more than 12) in FIG. 2(a) and FIG. 2(b), a pilot pattern occupying 12 subcarriers can be designed, and specific parameters are shown in Table 1.

[0041] Table 1 Pilot pattern parameters (12 subcarriers)

[0042] Combined with Figure 2(a), the frequency hopping interval in Table 1 is 1→6→1 (a frequency hopping rule), and 1→6→1 means that the intervals between each group of sent pilot signals are 1 frequency interval, 6 frequency intervals, and 1 frequency interval, respectively. 1 frequency interval is equal to 1 subcarrier interval. The bandwidth in Table 1 refers to the bandwidth of the entire pilot pattern, which is equal to the subcarrier interval multiplied by the number of subcarriers. The frequency hopping period is the symbol duration multiplied by the number of symbols. 1 subcarrier interval corresponds to 1 subcarrier, that is, the number of subcarrier intervals is equal to the number of subcarriers.

[0043] It should be noted that for the relevant explanations of Figure 2(b), Figure 3(a), Figure 3(b), Figure 3(c), Figure 4(a), Figure 4(b) and Table 3, please refer to the above introduction to Figure 2(a) and Table 1.

[0044] In terms of specific design, taking the case of one user device in FIG. 2( a ), that is, the total number of user devices in the user device group is 1, as an example, the specific configuration is shown in Table 2: Table 2 Example configuration of a pilot pattern for 1 device

[0045] The frequency point numbers in Table 2 represent the number of each colored rectangle from top to bottom (frequency from high to low) in the vertical axis direction. Time refers to the number of the colored rectangle from left to right in the horizontal axis direction. Frequency point hopping refers to the relative change between the values ​​of adjacent different frequency point numbers. For example, the relative frequency 3.75kHz corresponding to frequency point number 1 is obtained by adding the product of the frequency point hopping (-1) and the width of a colored rectangle (subcarrier spacing 3.75kHz) to the relative frequency 7.5kHz of frequency point 2.

[0046] When there are a large number of user devices, there will be a certain congestion risk if a pilot pattern that occupies 12 subcarriers is used as shown in FIG4(a). A pilot pattern that occupies 36 subcarriers (FIG4(b)) or more subcarriers may be used. The specific parameters of the pilot pattern of 36 subcarriers are shown in Table 3.

[0047] Table 3 Pilot pattern parameters (36 subcarriers)

[0048] In summary, according to the examples given in Figures 2(a), 2(b), 3(a), 3(b), 3(c), 4(a), and 4(b), different pilot patterns are designed for different user equipment groups, and a pilot pattern library with three-dimensional constraints of "number of devices-time-frequency" is established. The pilot pattern library consists of pilot patterns corresponding to different user equipment groups.

[0049] The embodiments of the present application fully utilize the advantages of spatial domain isolation provided by satellite phased array beam hopping in satellite communication scenarios, construct a space-time-frequency three-dimensional frequency hopping pattern, reduce user equipment interference between different beams and different cells, and fully utilize system resources; and adjust the pilot pattern allocation according to the real-time information of random access of user equipment, thereby improving the success rate of user equipment accessing the satellite.

[0050] Step 102: Select an optimal pilot pattern from a plurality of pilot patterns according to the success rate of each user equipment in the user equipment group accessing the satellite.

[0051] In one embodiment of the present application, an optimal pilot pattern is selected from a plurality of pilot patterns according to a success rate of each user device in a user device group accessing a satellite, including: obtaining a success rate of each user device in a user device group accessing a satellite; and selecting an optimal pilot pattern from a plurality of pilot patterns corresponding to the user device group according to a success rate of each user device in a user device group accessing a satellite.

[0052] In one embodiment of the present application, the success rate of each user device in the user device group accessing the satellite is obtained, including: taking the signal transmission response between each user device in the user device group and the satellite as channel fading; obtaining the false detection rate of the satellite for the signal sent by each user device received based on the channel fading and the signal-to-noise ratio; and obtaining the success rate of each user device in the user device group accessing the satellite based on the false detection rate of the satellite for the signal sent by each user device received.

[0053] In one embodiment of the present application, based on the success rate of each user device in the user device group accessing the satellite, an optimal pilot pattern is selected from several pilot patterns corresponding to the user device group, including: summing the success rate of each user device in the user device group accessing the satellite, and taking the maximum value of the summed result to select the optimal pilot pattern from the several pilot patterns corresponding to the user device group.

[0054] In one embodiment of the present application, the success rate of each user device in the user device group accessing the satellite is summed, and the maximum value is obtained for the summed result to select the optimal pilot pattern from the several pilot patterns corresponding to the user device group, including: summing the success rate of each user device in the user device group accessing the satellite, and under the premise of satisfying constraint conditions, obtaining the maximum value for the summed result to select the optimal pilot pattern from the several pilot patterns corresponding to the user device group; the constraint conditions include constraints on the number of all user devices corresponding to each pilot pattern, the success rate of each user device corresponding to each pilot pattern accessing the satellite, and the interference between the user devices corresponding to each pilot pattern.

[0055] Specifically, the total number of user equipments in the user equipment group (ie, the number of user equipments served by each pilot pattern) is assumed to be Sometimes, there is pilot patterns, each pilot pattern is recorded as , Each user equipment group corresponds to several pilot patterns.

[0056] The number of accessible user devices , Single user device access success rate , interference between user devices As constraints, the optimal pilot combination corresponding to different user equipment groups is obtained. Among them, the access success rate of a single user equipment in the user equipment group needs to be taken as the channel fading by the signal transmission response, and the uplink false detection rate is further solved or obtained by simulation. According to the link budget formula, the signal-to-noise ratio is obtained from the channel fading; usually, the corresponding relationship between the signal-to-noise ratio and the false detection rate can be obtained by simulation, such as Figure 5 As shown in Figure 2, the uplink false detection rate is obtained based on the signal-to-noise ratio.

[0057] The optimal pilot combination is obtained by solving the optimization problem. The mathematical expression of the optimization problem is as follows:

[0058] in, The number of accessible user devices is The pilot pattern at time (the target variable of the optimal solution). The number of accessible user devices is The total number of pilot patterns corresponding to .

[0059] Constraints: a) Constraint on the total number of user devices in a user device group:

[0060] b) Constraints on access success rate of a single user equipment in a user equipment group:

[0061] c) Interference constraints between user equipments in a user equipment group:

[0062] in, is the system's accessible user equipment capacity, is the access success rate of a single user device in the user device group, It is the minimum requirement for the access success rate of a single user device in a user device group. Is a user device in the user device group The interference between user devices, is the maximum interference allowed between user equipments. The access success rate of a single user equipment in a user equipment group is the probability that the satellite successfully detects the random access request sent by the user equipment.

[0063] For the optimization problem proposed above, the Lagrangian dual method can be used to solve it. First, the Lagrangian function is constructed, the optimization problem is combined with the constraints, and the Lagrangian multiplier is introduced. Then, by solving the dual problem of the Lagrangian function, the Lagrangian function about the optimization variable is maximized, and the dual function value about the Lagrangian multiplier is minimized. Finally, the optimal solution or approximate solution of the original problem is found by iteratively adjusting the Lagrangian multiplier and combining the KKT (Karush-Kuhn-Tucker) condition, that is, the optimal pilot pattern corresponding to all user devices in the user device group is obtained.

[0064] Step 103: Each user equipment in the user equipment group sends a pilot signal to the satellite according to the optimal pilot pattern; the pilot signal is used to indicate a random access request sent by each user equipment in the user equipment group to the satellite.

[0065] In one embodiment of the present application, each user device in a user device group sends a pilot signal to a satellite according to an optimal pilot pattern, including: all user devices in each user device group determine the time and frequency of sending the pilot signal to the satellite according to their corresponding optimal pilot pattern; all user devices in each user device group send the pilot signal to the satellite within the determined time and frequency.

[0066] The embodiments of the present application are aimed at low-orbit satellite Internet of Things scenarios. By integrating the satellite beam space domain isolation capability, a space-time-frequency hopping pattern is constructed to achieve performance improvements such as low latency, high random access success rate and high-density access.

[0067] The present application also includes: The pilot signals sent by all user equipments in the user equipment group to the satellite are input into the sub-band filter for sub-band filtering, and filter shaping is completed to generate a baseband waveform; the baseband waveform is sent to the satellite after correlation processing; the correlation processing includes digital-to-analog conversion and radio frequency amplification.

[0068] In one embodiment of the present application, a method for configuring a subband filter includes: estimating a detection success rate of a UFMC symbol based on key parameters of the subband filter, a signal transmission response, and a signal peak-to-average ratio; the key parameters include type, length, number of subbands, and sideband suppression ratio; obtaining a UFMC time efficiency based on a ratio of the length of the subband filter to the UFMC symbol; obtaining an uplink random access channel capacity based on the detection success rate of the UFMC symbol and the UFMC time efficiency; and obtaining key parameters of an optimized subband filter based on the uplink random access channel capacity.

[0069] In one embodiment of the present application, according to the uplink random access channel capacity, the key parameters of the optimized subband filter are obtained, including: maximizing the uplink random access channel capacity under the premise of satisfying preset constraints, and obtaining the key parameters of the optimized subband filter; the preset constraints include that the Hessian matrix is ​​greater than zero, and the Hessian matrix is ​​determined according to the uplink random access channel capacity.

[0070] Specifically, first, according to the signal transmission response , signal peak-to-average ratio and the key parameters of the subband filter (type ,length , number of subbands B, sideband suppression ratio ), estimates the ideal detection success rate of UFMC symbols :

[0071] in, is the transmission delay, is the function for calculating the detection success rate; Then, according to the filter length Relative symbol length The ratio of , calculate the UFMC time efficiency :

[0072] At this time, the uplink random access channel capacity C can be expressed as:

[0073] Considering the positive definiteness condition of the Hessian matrix, the uplink random access channel capacity optimization is expressed as:

[0074]

[0075] Where H is the Hessian matrix, is the gradient operator, To be constrained by.

[0076] By adjusting the type of subband filter ,length , number of subbands N, sideband suppression ratio , find the best balance point between detection success rate and time efficiency, so that C can achieve the maximum value. The parameters of the sub-band filter when the best balance point is reached are the sub-band filter configuration required for the uplink.

[0077] The embodiment of this application considers the low-orbit satellite IoT scenario, and conducts research on the adaptability of 5G / 6G air interface alternative waveforms in low-orbit satellite IoT links based on the optimization suggestions for multi-carrier waveforms in international 5G / 6G. The UFMC waveform that does not use CP is preferred to achieve waveform design that satisfies performance compromises such as high efficiency of short data packet transmission, low out-of-band radiation, and low complexity, as well as the optimal filter design that adapts to massive narrowband access to low-orbit satellite IoT scenarios.

[0078] When the satellite Internet system is working, the user equipment in each waveband needs to select a pilot pattern that matches the signal transmission response of its waveband from its corresponding several pilot patterns, and then configure the subband filter according to the pilot signal sent by the user equipment to the satellite, complete the filtering and shaping, and finally generate the baseband waveform.

[0079] Specific baseband UFMC waveform signal It is expressed as follows:

[0080] Wherein, k refers to the kth symbol; m refers to the mth subcarrier; Refers to the information for distinguishing the user equipment of the mth subcarrier of the bth subband, which is determined in step 101; N is the number of points of the inverse Fourier transform; B is the total number of subbands; is the total number of subcarriers in the b-th subband; is the subband filter function of the bth subband, depending on the type of filter ,length , Sideband Suppression Ratio OK, the type of filter ,length SSBSR It can be calculated from the above embodiments.

[0081] The embodiment of the present application selects the UFMC waveform as a new waveform adapted to the satellite IoT random access pilot signal, taking advantage of its non-cyclic prefix to improve the system's time efficiency. The parameter range of the subband filter corresponding to the UFMC waveform is preliminarily defined for the IoT frame structure. At the same time, the transmission delay and Doppler shift, signal-to-noise ratio and time efficiency are comprehensively considered to clarify the most suitable subband filter parameters corresponding to the UFMC waveform, and realize on-demand automatic adjustment of the UFMC waveform parameter configuration according to real-time feedback information.

[0082] In the above-mentioned embodiment of the present application, the method for obtaining the signal transmission response includes: obtaining the signal transmission response according to the path loss between the satellite and the user equipment, the scintillation effect, the atmospheric absorption, the impulse response function of the transmission delay, the transmission delay, the Doppler frequency shift, the TDL model in the small-scale fading, the influence of the on-board RF device, and the phased array antenna array response.

[0083] Specifically, the signal transmission response may be obtained by: calculating the satellite motion trajectory according to the satellite orbit information and the satellite Kepler orbit model; and calculating the signal transmission response from each position point in the satellite motion trajectory to the position point where the user equipment is located.

[0084] Specifically, according to the orbital information of the satellite, specifically the six orbital numbers (i.e., the longitude of the ascending node, the semi-major axis of the orbit, the eccentricity of the orbit, the argument of perigee, the orbital inclination, and the true perigee angle), the motion trajectory of the satellite can be calculated based on the SGP4 (Simplified General PerturbationModel 4) algorithm, which also includes the spatial position and velocity of the satellite at any time. To calculate the signal transmission response, it is necessary to first determine the position of the satellite and the location of the user equipment. The satellite's position coordinates are converted from the Earth-Centered Inertial (ECI) coordinate system to the Earth-Centered, Earth-Fixed (ECEF) coordinate system to form a coordinate system of the Earth-Centered, Earth-Fixed coordinate system. The location of the user equipment can be obtained after positioning by the global satellite navigation system built into the user equipment. On this basis, referring to relevant protocols such as ITU-R P.618, the signal transmission response is designed as follows:

[0085] in, is the path loss, For the flickering effect, Absorbed by the atmosphere, is the impulse response function of the transmission delay, is the transmission delay, is the Doppler shift, is the TDL (tapped delay line) model in small-scale fading, Due to the influence of onboard radio frequency devices, is the phased array antenna array response.

[0086] Among them, the transmission delay The calculation formula is:

[0087] in, It indicates the transmission pitch angle of the signal sent by the user equipment to the satellite at time t. represents the speed of light, represents the radius of the Earth, Indicates the satellite orbit altitude.

[0088] See also Figure 6 The embodiment of the present application also provides a random access system for satellite communication, which includes: A pilot pattern selection module, used to determine the total number of user equipment in the user equipment group, and select a number of pilot patterns corresponding to the user equipment group from a pilot pattern library; each of the pilot patterns is related to the total number of user equipment in the user equipment group, time, and frequency; An optimal pilot pattern selection module, configured to select an optimal pilot pattern from the plurality of pilot patterns according to a success rate of each user equipment in the user equipment group accessing a satellite; A pilot signal sending module is used for each user equipment in the user equipment group to send the pilot signal to the satellite according to the optimal pilot pattern; the pilot signal is used to indicate a random access request sent by each user equipment in the user equipment group to the satellite.

[0089] See also Figure 7 An embodiment of the present application also provides an electronic device, including a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the random access method for satellite communication described in the above embodiment is implemented.

[0090] An embodiment of the present application also provides a computer-readable storage medium, which includes a computer program or instructions. When the computer program or instructions are executed on a computer, the computer executes the random access method for satellite communication described in the above embodiment.

[0091] It should be noted that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0092] Those skilled in the art should clearly understand that, for the convenience and brevity of description, the specific working processes of the random access system for satellite communications, the electronic device and the computer-readable storage medium described in the above embodiments can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0093] A person skilled in the art will understand that all or part of the steps to implement the above embodiments may be accomplished by hardware, or may be accomplished by instructing the relevant hardware through a program, and the program may be stored in a computer-readable storage medium, and the above-mentioned storage medium may be a read-only memory, a disk, or an optical disk, etc.

[0094] The above are only optional embodiments of the present application, which are only used to illustrate the technical solution of the present application rather than to limit it. Without departing from the spirit and scope of the present application, modifications, equivalent substitutions, improvements, etc. to the specific implementation methods of the present application should all be included in the protection scope of the present application.

Claims

1. A random access method for satellite communication, characterized in that: include: Determine the total number of user equipments in the user equipment group, and select a number of pilot patterns corresponding to the user equipment group from a pilot pattern library; Each of the pilot patterns is related to the total number, time and frequency of user equipment in the user equipment group; Selecting an optimal pilot pattern from the plurality of pilot patterns according to a success rate of each user equipment in the user equipment group accessing the satellite; Each user equipment in the user equipment group sends the pilot signal to the satellite according to the optimal pilot pattern; The pilot signal is used to indicate a random access request sent by each user equipment in the user equipment group to the satellite.

2. The random access method for satellite communication according to claim 1, characterized in that: The method for acquiring the pilot pattern library is: Establishing a plurality of pilot patterns corresponding to the user equipment group according to the number of subcarriers, the subcarrier spacing, and the number of pilot signals sent by each user equipment in the user equipment group to the satellite each time; The pilot pattern library is formed by combining a plurality of pilot patterns corresponding to all the user equipment groups.

3. The random access method for satellite communication according to claim 2, characterized in that: The establishing a plurality of pilot patterns corresponding to the user equipment group according to the number of subcarriers, the subcarrier spacing, and the number of pilot signals sent by each user equipment in the user equipment group to the satellite each time includes: Determine the total number of user equipments corresponding to each pilot pattern according to the number of user equipments in each of the multiple cells, so as to establish a plurality of pilot patterns corresponding to the user equipment group; the multiple cells are located in the same beam position in the satellite transmission beam; each pilot pattern is used to provide time and frequency for all user equipments in the corresponding user equipment group to access the satellite; The plurality of pilot patterns are obtained according to the frequency and time at which each user equipment in the user equipment group accesses the satellite, and a preset frequency hopping rule; the preset frequency hopping rule is associated with different frequency hopping intervals.

4. The random access method for satellite communication according to claim 3, characterized in that: The establishing a plurality of pilot patterns corresponding to the user equipment group according to the number of subcarriers, the subcarrier spacing, and the number of pilot signals sent by each user equipment in the user equipment group to the satellite each time includes: According to the number of wave positions within the satellite coverage, the area of ​​each wave position, and the spatial density distribution function corresponding to each wave position, the number of all user equipment in each wave position is obtained; Divide each of the wave positions into a plurality of cells, and obtain the number of user equipment in each cell according to the number of all user equipment in each of the wave positions; The number of user devices corresponding to each pilot pattern is determined according to the number of user devices in each cell, the total frequency band resources allocated to each cell, the frequency band resources used by each pilot pattern, the total time resources allocated to each cell, and the time resources used by each pilot pattern.

5. The random access method for satellite communication according to claim 3, characterized in that: The method for acquiring the frequency and time at which each user equipment in the user equipment group accesses the satellite comprises: According to the number of subcarriers and the subcarrier spacing, obtaining a frequency at which each user equipment corresponding to each pilot pattern accesses the satellite; The time for each user equipment corresponding to each pilot pattern to access the satellite is obtained according to the number of pilot signals sent to the satellite by each user equipment corresponding to each pilot pattern and the time required to send each pilot signal.

6. The random access method for satellite communication according to claim 1, characterized in that: The selecting the best pilot pattern from the plurality of pilot patterns according to the success rate of each user equipment in the user equipment group accessing the satellite comprises: Obtaining a success rate of each user equipment in the user equipment group accessing a satellite; According to the success rate of each user equipment in the user equipment group accessing the satellite, an optimal pilot pattern is selected from the plurality of pilot patterns corresponding to the user equipment group.

7. The random access method for satellite communication according to claim 6, characterized in that: The obtaining the success rate of each user equipment in the user equipment group accessing the satellite includes: taking a signal transmission response between each user equipment in the user equipment group and the satellite as channel fading; Obtaining, according to the channel fading and the signal-to-noise ratio, an error detection rate of the satellite for the signal sent by each of the user equipments; The success rate of each user equipment in the user equipment group accessing the satellite is obtained according to the false detection rate of the signal sent by each user equipment received by the satellite.

8. The random access method for satellite communication according to claim 6, characterized in that: The selecting the best pilot pattern from the plurality of pilot patterns corresponding to the user equipment group according to the success rate of each user equipment in the user equipment group accessing the satellite comprises: The success rate of each user equipment in the user equipment group accessing the satellite is summed, and the maximum value of the summed result is obtained to select the best pilot pattern from the several pilot patterns corresponding to the user equipment group.

9. The random access method for satellite communication according to claim 8, characterized in that: The step of summing up the success rate of each user equipment in the user equipment group accessing the satellite and maximizing the summed result to select the best pilot pattern from the plurality of pilot patterns corresponding to the user equipment group includes: The success rate of each user equipment in the user equipment group accessing the satellite is summed, and the maximum value of the summation result is obtained under the premise of satisfying the constraint conditions, so as to select the optimal pilot pattern from the several pilot patterns corresponding to the user equipment group; the constraint conditions include constraints on the number of all user equipment corresponding to each pilot pattern, the success rate of each user equipment corresponding to each pilot pattern accessing the satellite, and the interference between the user equipment corresponding to each pilot pattern.

10. The random access method for satellite communication according to claim 1, characterized in that: Each user equipment in the user equipment group sends the pilot signal to the satellite according to the optimal pilot pattern, including: All user equipments in each user equipment group determine the time and frequency of sending the pilot signal to the satellite according to the corresponding optimal pilot pattern; All user equipments in each of the user equipment groups transmit the pilot signal to the satellite within the determined time and frequency.

11. The random access method for satellite communication according to any one of claims 1 to 10, characterized in that: Also includes: Inputting the pilot signal sent by all user equipments in the user equipment group to the satellite into a sub-band filter for sub-band filtering, completing filtering and shaping, and generating a baseband waveform; The baseband waveform is sent to the satellite after being processed by correlation; the correlation processing includes digital-to-analog conversion and radio frequency amplification.

12. The random access method for satellite communication according to claim 11, characterized in that: The method for configuring the sub-band filter comprises: Estimate the detection success rate of the UFMC symbol according to the key parameters of the subband filter, the signal transmission response and the signal peak-to-average ratio; the key parameters include type, length, number of subbands and sideband suppression ratio; Obtaining a UFMC time efficiency according to a ratio of a length of the subband filter to the UFMC symbol; Obtaining an uplink random access channel capacity according to the detection success rate of the UFMC symbol and the UFMC time efficiency; According to the uplink random access channel capacity, key parameters of the optimized subband filter are obtained.

13. The random access method for satellite communication according to claim 12, characterized in that: The step of obtaining the optimized key parameters of the subband filter according to the uplink random access channel capacity includes: Under the premise of satisfying preset constraints, the uplink random access channel capacity is maximized to obtain the optimized key parameters of the subband filter; the preset constraints include that the Hessian matrix is ​​greater than zero, and the Hessian matrix is ​​determined according to the uplink random access channel capacity.

14. The random access method for satellite communication according to claim 7 or 12, characterized in that: The method for obtaining the signal transmission response comprises: The signal transmission response is obtained according to the path loss between the satellite and the user equipment, the scintillation effect, the atmospheric absorption, the impulse response function of the transmission delay, the transmission delay, the Doppler frequency shift, the TDL model in the small-scale fading, the influence of the onboard radio frequency device, and the phased array antenna array response.

15. A random access system for satellite communication, characterized in that: include: A pilot pattern selection module, used to determine the total number of user equipments in a user equipment group, and select a number of pilot patterns corresponding to the user equipment group from a pilot pattern library; Each of the pilot patterns is related to the total number, time and frequency of user equipment in the user equipment group; An optimal pilot pattern selection module, configured to select an optimal pilot pattern from the plurality of pilot patterns according to a success rate of each user equipment in the user equipment group accessing a satellite; A pilot signal sending module, configured for each user equipment in the user equipment group to send the pilot signal to the satellite according to the optimal pilot pattern; The pilot signal is used to indicate a random access request sent by each user equipment in the user equipment group to the satellite.

16. An electronic device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the computer program is executed by the processor, the random access method for satellite communication according to any one of claims 1 to 14 is implemented.

17. A computer-readable storage medium, characterized in that: The computer-readable storage medium includes a computer program or an instruction. When the computer program or the instruction is executed on a computer, the computer is enabled to execute the random access method for satellite communication according to any one of claims 1 to 14.

Images