Hybrid random access method and device in satellite internet of things scenario

Abstract

The application discloses a hybrid random access method and device in a satellite Internet of Things scene, and the method comprises the following steps: a terminal of a sending end receives a synchronization signal, and frame and time slot synchronization is completed; according to the sending requirements of each terminal, it is determined that each terminal is in a non-spread spectrum mode or a spread spectrum mode, wherein the terminal of the sending end comprises a non-spread spectrum terminal and a spread spectrum terminal; a non-spread spectrum data packet is obtained by carrier modulation on a non-spread spectrum terminal signal, and a spread spectrum data packet is obtained by spread spectrum modulation on a spread spectrum terminal signal; the non-spread spectrum terminal randomly sends the modulated non-spread spectrum data packet by selecting a channel and a time slot, and the spread spectrum terminal randomly sends the modulated spread spectrum data packet by selecting a channel and a time slot. The hybrid superposition of two traditional random access modes, i.e. a non-spread spectrum random access mode and a spread spectrum random access mode, in the same system is realized, the system throughput can be improved, the business requirements of various terminals in an actual scene can be met, and the method is suitable for a working scene of massive terminal access of a satellite Internet of Things and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of satellite Internet of Things, and relates to a hybrid random access method and device in a satellite Internet of Things scenario. BACKGROUND

[0002] In recent years, with the increasing demand for message transmission, information and communication technology is constantly improving. Under this background, the concept of Internet of Things has attracted widespread attention. Since the Internet of Things can network and informatize the physical world, and integrate and communicate the two separate worlds of the physical world and the information world, the Internet of Things has become an important part of supporting intelligent industries, realizing intelligent environmental monitoring, waste management, traffic control, intelligent metering, identification positioning and tracking management and many other functions, and promoting the rapid development of various intelligent industries, providing more and more convenience for people's lives. The Internet of Things has become an important part of the new generation of information technology, and is regarded as the third industrial revolution in the development of the world's information industry after computers and the Internet, and has become one of the important driving forces of today's social development, with broad market prospects.

[0003] However, the Internet of Things service based on ground base stations is usually restricted by geographical environment (such as oceans, deserts), because it is difficult to build and maintain ground base stations in these areas, and ground base stations are also easily damaged when natural disasters (such as earthquakes) occur.

[0004] In order to solve this problem, scholars have begun to study the application potential of long-range wide area networks in low-orbit satellites as a supplement to ground Internet of Things.

[0005] For a satellite Internet of Things system, its business has certain burstiness and randomness and small data volume, and the resource allocation of the fixed allocation-based multiple access technology is not flexible enough, which will cause unnecessary waste of resources and is not suitable for application in the satellite Internet of Things system. Compared with the fixed allocation-based multiple access technology, the contention-based multiple access protocol has the advantages of high flexibility and easy implementation, and its signaling overhead is small and transmission efficiency is high, so it is a communication protocol suitable for application in the satellite Internet of Things system. However, under the condition of medium and high load, the system throughput of the contention-based multiple access protocol will have a significant or even sharp decline. SUMMARY

[0006] Invention purposes: In order to overcome the deficiencies existing in the prior art, the application provides a hybrid random access method in a satellite Internet of Things scene, in a low-orbit satellite Internet of Things scene model, for different channel environments of interference conditions, the most suitable spreading code length is used for anti-interference processing. By comparing the predicted value of the load estimation with the upper and lower threshold values, combined with the selected spreading code length, the appropriate random access mode is adaptively selected, and in the case of resisting channel interference, the system throughput is improved as much as possible.

[0007] The application provides a hybrid random access scheme in a satellite Internet of Things scene based on environmental perception, including low-orbit Internet of Things modeling and anti-interference analysis, load estimation and prediction, and random access adaptive scheme. The low-orbit Internet of Things modeling and anti-interference analysis refers to first establishing a low-orbit Internet of Things scene, and then analyzing the improvement of the anti-interference ability of different spreading conditions in this scene; the load estimation and prediction is to estimate the load condition of the current time slot according to the prior time slot state information in the communication process, and integrate all the estimation results as historical data for machine learning, and then use machine learning to predict the load condition of the future time slot; the random access adaptive scheme is to set the upper and lower threshold values of the adaptive scheme under the premise of whether to spread and the spreading code length determined by the anti-interference analysis, and adaptively switch the random access scheme through the load prediction value. This method can adaptively switch different random access schemes according to the interference condition and the load condition, can improve the system throughput in the case of negligible interference, can guarantee the communication quality and improve the throughput in the case of deteriorating signal-to-interference ratio.

[0008] Technical scheme: To achieve the above purpose, the technical scheme adopted by the application is:

[0009] In a first aspect, a hybrid random access method in a satellite Internet of Things scene is provided, comprising:

[0010] Each terminal of the sending end receives a synchronization signal to complete frame and time slot synchronization;

[0011] According to the sending requirements of each terminal, each terminal is determined to be in non-spreading or spreading mode, wherein the terminals of the sending end include non-spreading terminals and spreading terminals;

[0012] The non-spreading terminal signal is carrier modulated to obtain a non-spreading data packet, and the spreading terminal signal is first spread and then modulated to obtain a spread spectrum data packet;

[0013] The non-spreading terminal selects a channel and a time slot to randomly send the modulated non-spreading data packet, and the spreading terminal selects a channel and a time slot to randomly send the modulated spread spectrum data packet.

[0014] The receiving end receives and processes the data packet.

[0015] In some embodiments, the non-spread spectrum terminal signal is carrier modulated to obtain a non-spread spectrum data packet, comprising:

[0016] The carrier signal is A0cos(2πf0t), the non-spread spectrum information stream is modulated by the modulating signal of the encoder, and the modulated output signal s0(t) is expressed as:

[0017] s0(t) = A0m(t)cos(2πf0t)

[0018] where A0 is the carrier amplitude, and f0 is the carrier frequency.

[0019] In some embodiments, the spread spectrum terminal signal is first spread spectrum modulated to obtain a spread spectrum data packet, comprising:

[0020] Determining the spread spectrum mode: a direct sequence spread spectrum mode is used to generate the spread spectrum data packet;

[0021] Selecting the spread spectrum code c(t): c(t) is a high transmission rate binary pseudo-noise code, taking values +1 or -1, and the code rate is R c ;

[0022] Spreading and modulating the signal to be spread spectrum:

[0023] a) Spreading: based on the selected spread spectrum code c(t), the spread spectrum terminal signal is spectrum expanded to obtain a spectrum expanded composite signal where d(t) is a binary digital signal formed by the spread spectrum terminal information stream passing through the encoder, and the transmission rate is R b ;

[0024] b) Modulation: multiplying the spectrum expanded composite signal with the carrier cos(2πft), and the output signal s(t) obtained after the spread spectrum and modulation is expressed as:

[0025] s(t) = Ad(t)c(t)cos(2πft)

[0026] where A is the amplitude of the modulating signal, and f is the carrier frequency.

[0027] In some embodiments, the spread spectrum code c(t) uses an m sequence, a gold sequence, or an M sequence. Further, the spread spectrum code c(t) uses an m sequence.

[0028] In some embodiments, a channel is selected, comprising:

[0029] The total system bandwidth is B = f M -f L , where f L is the lowest frequency point allowed to access, and f M is the highest frequency point allowed to access;

[0030] a) For non-spread spectrum terminals: Set the number of non-spread spectrum sub-channels K. The non-spread spectrum data packet randomly selects channel k with a probability of 1 / K, where k = 1, 2, ..., K. The bandwidth of each sub-channel is In subchannel k: the non-spread spectrum data packet selects the channel center frequency as f = f L +(k-1)B k +mB0, where B0 is the non-spread spectrum signal bandwidth, m=1,2,…,M is the non-spread spectrum channel number, is the maximum number of channels, To remove the integer operation;

[0031] b) For spread spectrum terminals: The spread spectrum data packet selects the channel center frequency as f = f L +nB1, B1 is the signal bandwidth after spread spectrum, n=1,2,…,N is the spread spectrum channel number, is the maximum number of channels, To remove the integer operation.

[0032] In some embodiments, selecting a time slot includes:

[0033] a) For non-spread spectrum terminals, the qth terminal randomly selects time slot l with probability 1 / L among the L time slots in the data frame. q , send the data packet S of the qth terminal in the corresponding time slot q , where q = 1, 2, ..., Q is the terminal number, Q is the total number of non-spread spectrum terminals, l q =1,2,......,L;

[0034] b) For spread spectrum terminals, the hth terminal randomly selects time slot l with probability 1 / L among the L time slots in the data frame. h , send the data packet S of the hth terminal in the corresponding time slot h , where h=1,2,......,H is the terminal number, H is the total number of spread spectrum terminals, l h =1,2,......,L.

[0035] In a second aspect, a hybrid random access device in a satellite Internet of Things scenario is provided, including a processor and a storage medium;

[0036] The storage medium is used to store instructions;

[0037] The processor is configured to operate according to the instructions to execute the steps of the method according to the first aspect.

[0038] In a third aspect, a storage medium is provided, and the storage medium has stored thereon a computer program, and the computer program is executed by a processor to implement the steps of the method in the first aspect.

[0039] Beneficial effects: The hybrid random access method based on satellite Internet of Things provided by the application can transmit both traditional data packets and additional spread spectrum data packets in the same spectrum resource compared with the traditional random access technology. The spread spectrum data packets transmitted use the power difference between spread spectrum and despreading to support signal separation, thereby solving the problems caused by the traditional non-spread spectrum random access mode. The application realizes the hybrid superposition of non-spread spectrum random access and spread spectrum random access in the same system, which can improve both the throughput and the packet loss rate of the system, and the two sets of user resources can be allocated to two sets of users with different service requirements, thereby meeting the application scenarios of different business requirements of various terminals in practice and supporting the satellite Internet of Things system to provide diversified service capabilities. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 is a hybrid random access method flow chart according to an embodiment of the application;

[0041] Figure 2 is a method model schematic diagram according to an embodiment of the application;

[0042] Figure 3a is a system throughput diagram;

[0043] Figure 3b is a system packet loss rate diagram. DETAILED DESCRIPTION

[0044] The application will be further described below in conjunction with the drawings and embodiments. The following embodiments are only used to more clearly illustrate the technical solutions of the application, and cannot be used to limit the protection scope of the application.

[0045] In the description of the application, if several meanings are included, the meaning of multiple is two or more, greater than, less than, more than, etc. are understood as not including the number, above, below, within, etc. are understood as including the number. If it is described as first, second, it is only used to distinguish the technical features for the purpose, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of indicated technical features or implicitly indicating the sequence of indicated technical features.

[0046] In the description of the application, the description of the terms "one embodiment", "some embodiments", "exemplary embodiment", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the application. In the description, the exemplary description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any suitable manner in one or more embodiments or examples.

[0047] Embodiment 1

[0048] A hybrid random access method in a satellite Internet of Things scenario, comprising:

[0049] Each terminal of the sending end receives a synchronization signal to complete frame and time slot synchronization;

[0050] According to the sending requirements of each terminal itself, determine that each terminal is in non-spread spectrum or spread spectrum mode, wherein the terminals of the sending end include non-spread spectrum terminals and spread spectrum terminals;

[0051] The non-spread spectrum terminal signal is carrier modulated to obtain a non-spread spectrum data packet, and the spread spectrum terminal signal is first spread spectrum modulated and then modulated to obtain a spread spectrum data packet;

[0052] The non-spread spectrum terminal selects a channel and a time slot to randomly send the modulated non-spread spectrum data packet, and the spread spectrum terminal selects a channel and a time slot to randomly send the modulated spread spectrum data packet;

[0053] The receiving end receives and processes the data packet.

[0054] In some specific embodiments, as shown in Figure 1 A hybrid random access method in a satellite Internet of Things scenario, comprising

[0055] Step S1, the terminal receives a synchronization signal to complete frame and time slot synchronization; according to the sending requirements of the terminal itself, select non-spread spectrum and spread spectrum mode;

[0056] Step S2, for non-spread spectrum terminal signal, carrier modulation; for spread spectrum terminal signal, first spread spectrum modulation and then modulation;

[0057] (2.1) Modulate the non-spread spectrum signal.

[0058] Taking PSK modulation mode as an example. The carrier signal is A0cos(2πf0t), the modulated signal of the non-spread spectrum information stream through the encoder is m(t), and the output signal after modulation can be represented as:

[0059] s0(t)=A0m(t)cos(2πf0t)

[0060] Where A0 is the carrier amplitude, f0 is the carrier frequency. Other modulation modes can also be selected if supported by the system.

[0061] (2.2) Determine the spreading mode and spreading code of the spread spectrum signal.

[0062] a) Determine the spreading mode: This method uses direct sequence spread spectrum to generate spread spectrum data packets.

[0063] b) Select the spreading code c(t): c(t) is a high transmission rate binary pseudo-noise code, taking values +1 or -1, and the code rate is R c .

[0064] The spreading code selected by this method is an m-sequence. It should be noted that the commonly used spreading code c(t) includes m-sequence, gold sequence, M-sequence, etc., and the spreading code can be selected flexibly according to the actual situation in application.

[0065] (2.3) Spread and modulate the signal to be spread.

[0066] a) Spreading: The spread spectrum composite signal is d(t) is a binary digital signal formed by the spread spectrum terminal information stream through the encoder, and the transmission rate is R b .

[0067] b) Modulation: Taking PSK modulation mode as an example. The spread spectrum composite signal is multiplied by the carrier cos(2πft). The output signal obtained after spreading and modulation can be represented as:

[0068] s(t) = Ad(t)c(t)cos(2πft)

[0069] Where A is the modulation signal amplitude, f is the carrier frequency. Other modulation modes can also be selected if supported by the system.

[0070] Step S3, two groups of terminals select channels and time slots to send data packets;

[0071] (3.1) Select the channel; the specific method is:

[0072] The total system bandwidth is B = f M -f L , where f L is the lowest frequency point allowed to access, and f M is the highest frequency point allowed to access.

[0073] a) For non-spread spectrum terminals:

[0074] a1) setting the number of non-spread spectrum sub-channels K, non-spread spectrum data packets randomly select a channel k with a probability of 1 / K, wherein k = 1, 2, …, K, and each sub-channel has a bandwidth of B

[0075] a2) in the sub-channel k: non-spread spectrum data packets can select a channel center frequency f = f L +(k-1)B k +mB0, wherein B0 is the bandwidth of the non-spread spectrum signal, m = 1, 2, …, M is the non-spread spectrum channel number, is the maximum number of channels, is the floor operation.

[0076] b) for spread spectrum terminals:

[0077] Spread spectrum data packets can select a channel center frequency f = f L +nB1, B1 is the bandwidth of the spread spectrum signal, n = 1, 2, …, N is the spread spectrum channel number, is the maximum number of channels, is the floor operation.

[0078] (3.2) Select a time slot; the specific method is:

[0079] a) for non-spread spectrum terminals, the qth terminal randomly selects a time slot l q in the L time slots in the data frame with a probability of 1 / L, and sends the data packet S q of the qth terminal in the corresponding time slot, wherein q = 1, 2, …, Q is the terminal number, Q is the total number of non-spread spectrum terminals, l q = 1, 2, …, L;

[0080] b) for spread spectrum terminals, the hth terminal randomly selects a time slot l h in the L time slots in the data frame with a probability of 1 / L, and sends the data packet S h of the hth terminal in the corresponding time slot, wherein h = 1, 2, …, H is the terminal number, H is the total number of spread spectrum terminals, l h = 1, 2, …, L.

[0081] Step S4, the receiving end receives the data packet.

[0082] An embodiment is provided below to further verify the access method provided by the application.

[0083] Experimental scenario:

[0084] The scenario sets 500 non-spread spectrum terminals, 100 spread spectrum terminals, selects each terminal to send a data packet, 50 sub-channels, and 100 time slots. Through the direct sequence spread spectrum method, an m sequence is used as a spread spectrum code, and the spread spectrum gain is 10 dB. Each terminal randomly selects a time slot to send a data packet.

[0085] Figure 3a is a schematic diagram of throughput, Figure 3b is a schematic diagram of packet loss rate. From the simulation results, it can be seen that the hybrid random access scheme has certain improvement in throughput and packet loss rate compared with the traditional random access technology.

[0086] Embodiment 2

[0087] The embodiment also provides a hybrid random access device in a satellite Internet of Things scenario, including a processor and a storage medium;

[0088] The storage medium is used to store instructions;

[0089] The processor is used to operate according to the instructions to perform the steps of the method according to Embodiment 1.

[0090] Embodiment 3

[0091] The embodiment provides a storage medium having a computer program stored thereon, the computer program being executed by a processor to implement the steps of the method of Embodiment 1.

[0092] Those skilled in the art will understand that the embodiments of the present application can be provided as a method, a system, or a computer program product. Therefore, the present application can take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROMs, optical storage, etc.) containing computer-usable program code.

[0093] The present application is described with reference to flowcharts and / or block diagrams according to the methods, devices (systems), and computer program products of the embodiments of the present application. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, and the combination of flows and / or blocks in the flowcharts and / or block diagrams can be implemented by computer program instructions. These computer program instructions can be provided to a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing apparatus to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing apparatus produce a device that implements the functions specified in the flowcharts and / or block diagrams. Figure 1 The functions specified in one or more flows and / or blocks Figure 1 The device that implements the functions specified in one or more flows and / or blocks.

[0094] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0095] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 The steps for the function specified in one or more boxes.

[0096] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A hybrid random access method in a satellite Internet of Things scenario, characterized in that: include: Each terminal on the transmitting end receives the synchronization signal and completes frame and time slot synchronization; Determine whether each terminal is in non-spread spectrum or spread spectrum mode based on its own transmission requirements, where the transmitting terminal includes non-spread spectrum terminals and spread spectrum terminals; Carrier modulation is performed on the non-spread spectrum terminal signal to obtain a non-spread spectrum data packet, and the spread spectrum terminal signal is first spread spectrum and then modulated to obtain a spread spectrum data packet; Direct sequence spread spectrum is used to generate spread spectrum data packets; The non-spread spectrum terminal selects a channel and a time slot to randomly send the modulated non-spread spectrum data packet, and the spread spectrum terminal selects a channel and a time slot to randomly send the modulated spread spectrum data packet, wherein the selected channel includes: The total system bandwidth is B = f M -f L , where f L is the lowest frequency point allowed for access, f M It is the highest frequency point allowed for access; a) For non-spread spectrum terminals: Set the number of non-spread spectrum sub-channels K, and the non-spread spectrum data packet randomly selects channel k with a probability of 1 / K, where k = 1, 2, ..., K, and the bandwidth of each sub-channel is In subchannel k: the non-spread spectrum data packet selects the channel center frequency as f = f L +(k-1)B k +mB0, where B0 is the non-spread spectrum signal bandwidth, m=1,2,...,M is the non-spread spectrum channel number, is the maximum number of channels, To remove the integer operation; b) For spread spectrum terminals: The spread spectrum data packet selects the channel center frequency as f = f L +nB1, B1 is the signal bandwidth after spread spectrum, n=1,2,...,N is the spread spectrum channel number, is the maximum number of channels, To remove the integer operation; The selected time slots include: a) For non-spread spectrum terminals, the qth terminal randomly selects time slot l with probability 1 / L among the L time slots in the data frame. q , send the data packet S of the qth terminal in the corresponding time slot q , where q = 1, 2, ..., Q is the terminal number, Q is the total number of non-spread spectrum terminals, l q =1,2,......,L; b) For spread spectrum terminals, the hth terminal randomly selects time slot l with probability 1 / L among the L time slots in the data frame. h , send the data packet S of the hth terminal in the corresponding time slot h , where h=1,2,......,H is the terminal number, H is the total number of spread spectrum terminals, l h =1,2,......,L.

2. The hybrid random access method in the satellite Internet of Things scenario according to claim 1, characterized in that: Carrier modulation is performed on the non-spread spectrum terminal signal to obtain a non-spread spectrum data packet, including: The carrier signal is A0cos(2πf0t), the modulation signal of the non-spread spectrum information stream passing through the encoder is m(t), and the modulated output signal s0(t) is expressed as: s0(t)=A0m(t)cos(2πf0t) Where A0 is the carrier amplitude and f0 is the carrier frequency.

3. The hybrid random access method in the satellite Internet of Things scenario according to claim 1, characterized in that: The spread spectrum terminal signal is first spread spectrum and then modulated to obtain a spread spectrum data packet, including: Select the spreading code c(t): c(t) is a binary pseudo-noise code with a high transmission rate, taking the value of +1 or -1, and the code rate is R c ; Based on the selected spreading code c(t), the spread spectrum terminal signal is spectrum expanded to obtain the composite signal after spectrum expansion Where d(t) is the binary digital signal formed by the spread spectrum terminal information stream through the encoder, and the transmission rate is R b ; The composite signal after spectrum expansion The output signal s(t) obtained by multiplying the carrier cos(2πft) and spreading and modulating is expressed as: s(t)=Ad(t)c(t)cos(2πft) Where A is the modulating signal amplitude and f is the carrier frequency.

4. The hybrid random access method in the satellite Internet of Things scenario according to claim 3, characterized in that: The spreading code c(t) adopts m sequence, gold sequence or M sequence.

5. The hybrid random access method in the satellite Internet of Things scenario according to claim 3, characterized in that: The spreading code c(t) adopts an m sequence.

6. A hybrid random access device in a satellite Internet of Things scenario, characterized in that: including processors and storage media; The storage medium is used to store instructions; The processor is configured to operate according to the instructions to execute the steps of the method according to any one of claims 1 to 5.

7. A storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 5 are implemented.

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