Cellular-free large-scale MIMO (Multiple Input Multiple Output) forward topology deployment method and system

Abstract

The invention discloses a cellular-free large-scale MIMO forward topology deployment method and system, and the method comprises the steps: setting at least one newly-added access point in a cellular-free large-scale MIMO system, enabling each newly-added access point to be connected with the nearest existing equipment, and calculating the expected value of the sum of the distances between the newly-added access points and the equipment connected with the newly-added access points under the topology; setting the maximum number of newly-added access points which can be connected with each existing access point as a limiting condition, and calculating an expected value of the sum of distances between the newly-added access points and equipment connected with the newly-added access points under the topology; the deployment cost of newly added access points in the chain topology, the chain topology with the limited connection number and the star topology is calculated; and comparing the three deployment costs, and taking the lowest deployment cost of the newly added access point as a target to obtain a chain topology application condition with a limited connection number. The deployment cost of the newly added access points can be effectively reduced; by increasing the number of the newly-added access points which can be connected with the existing access point, lower deployment cost of the newly-added access points can be obtained under a certain condition.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technology, and in particular to a method and system for deploying a cellular-free large-scale MIMO fronthaul topology. Background Art

[0002] Cell-free massive MIMO is considered to be the leading candidate technology for providing the best service to all user devices. In a cell-free massive MIMO system, APs (Access Points) with one or more antennas are spread throughout the area and connected to the CPU (Central Processing Unit) through a fronthaul link. Each user device can be connected to multiple access points at the same time, which are responsible for collaboratively processing the user's signals.

[0003] However, on the other hand, there are a large number of access points in the cell-free massive MIMO system. Since each access point needs to exchange a large amount of signal processing information and user data with the central processing unit (CPU), the bandwidth required for the fronthaul link increases exponentially as the number of access points increases. This will result in many fronthaul links connected to the CPU. The fronthaul service bandwidth between the CPU and the access points may surge, requiring an expensive point-to-point fronthaul topology. In order to meet the huge fronthaul bandwidth requirements, it may be necessary to deploy high-speed, low-latency optical fiber or adopt advanced wireless fronthaul technology. The implementation cost of these solutions is very high. In addition, maintaining such a complex fronthaul network structure, including equipment installation, commissioning, operation and maintenance, will also introduce additional costs and management complexity. Therefore, there is an urgent need for a solution that can achieve a scalable cell-free massive MIMO architecture and low-cost fronthaul topology deployment. Summary of the invention

[0004] In view of the above existing problems, the present invention is proposed.

[0005] Therefore, the present invention provides a non-cellular large-scale MIMO fronthaul topology deployment method and system to solve the problem that there are a large number of access points in the current system, each access point needs to exchange a large amount of signal processing information and user data with the central processor, and a scalable and low-cost fronthaul topology deployment cannot be achieved.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] In a first aspect, the present invention provides a method for deploying a non-cellular massive MIMO fronthaul topology, including: setting at least one new access point in a non-cellular massive MIMO system, each new access point connecting to an existing device closest to it to form a chain topology, and calculating the expected value of the sum of the distances between the new access point and its connected device under the topology;

[0008] The maximum number of new access points that each existing access point can connect to is set as a restriction condition to form a chain topology with a limited number of connections, and the expected value of the sum of the distances between the new access points and their connected devices under this topology is calculated;

[0009] Calculate the deployment cost of new access points in a chain topology and a chain topology with a limited number of connections, and calculate the deployment cost of new access points in a star topology where all new access points are directly connected to a central processor;

[0010] By comparing the three deployment costs and taking the lowest deployment cost of new access points as the goal, the applicable conditions of the chain topology with limited number of connections are obtained.

[0011] As a preferred solution of the non-cellular massive MIMO fronthaul topology deployment method of the present invention, wherein: at least one new access point is set in the non-cellular massive MIMO system, and each new access point is connected to the nearest existing device to form a chain topology, including:

[0012] All existing access points are directly connected to the central processor via point-to-point fronthaul links;

[0013] Each newly added access point is connected to the existing device closest to it via an optical fiber, wherein the existing device includes a central processor and an existing access point;

[0014] The distance between the newly added access point and the nearest existing device is a straight-line distance.

[0015] As a preferred solution of the method for deploying a cellular-free massive MIMO fronthaul topology according to the present invention, wherein: in the chain topology with limited number of connections, each newly added access point is connected to the nearest existing device via an optical fiber, and the existing device includes a central processor and an existing access point that has not reached the maximum number of connections;

[0016] The distance between a new access point and the existing device it is connected to is the straight-line distance.

[0017] As a preferred solution of the cellular-free massive MIMO fronthaul topology deployment method described in the present invention, the existing access points and the newly added access points respectively obey the homogeneous Poisson point processes Φ1 and Φ2 with densities λ1 and λ2 in a circular system area with an area of ​​S and a radius of R, and their distributions are independent of each other.

[0018] As a preferred solution of the method for deploying a cellular-free massive MIMO fronthaul topology according to the present invention, in the chain topology with a limited number of connections, a newly added access point is connected to any existing device by a connection probability.

[0019] As a preferred solution of the non-cellular massive MIMO fronthaul topology deployment method of the present invention, wherein: comparing three deployment costs, taking the lowest deployment cost of new access points as the goal, obtaining the applicable conditions of the chain topology with limited number of connections, including:

[0020] When the area S and the density λ1 of existing access points are the same, the connection limit number C of existing access points is changed;

[0021] Compare the deployment costs of new access points required for different fronthaul topologies under different existing access point densities λ2.

[0022] As a preferred solution of the non-cellular massive MIMO fronthaul topology deployment method of the present invention, the applicable conditions are:

[0023] when When the number of connections is limited, the chain topology saves more deployment costs of adding access points than the chain topology;

[0024] Where M is the number of the farthest existing device to which the new access point is connected, and p n It represents the probability that a new access point is connected to the nth closest existing device.

[0025] In a second aspect, the present invention provides a non-cellular massive MIMO fronthaul topology deployment system, including: a first setting and calculation module, used to set at least one new access point in the non-cellular massive MIMO system, each new access point is connected to the existing device closest to it to form a chain topology, and calculate the expected value of the sum of the distances between the new access point and its connected device under the topology;

[0026] A second setting and calculation module is used to set the maximum number of new access points that each existing access point can connect to as a restriction condition, form a chain topology with a limited number of connections, and calculate the expected value of the sum of the distances between the new access points and their connected devices under the topology;

[0027] a cost calculation module, used to calculate the deployment cost of new access points in a chain topology and a chain topology with a limited number of connections, and to calculate the deployment cost of new access points in a star topology in which all new access points are directly connected to a central processor;

[0028] The comparison module is used to compare the three deployment costs, with the goal of minimizing the deployment cost of new access points, and obtain the applicable conditions of the chain topology with limited number of connections.

[0029] In a third aspect, the present invention provides a computing device, comprising:

[0030] Memory and processor;

[0031] The memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions. When the computer-executable instructions are executed by the processor, the steps of the method for deploying a cellular-free massive MIMO fronthaul topology are implemented.

[0032] In a fourth aspect, the present invention provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, implement the steps of the method for deploying a cellular-free massive MIMO fronthaul topology.

[0033] Compared with the prior art, the present invention has the following beneficial effects: the method considers a point-to-multipoint fronthaul topology structure, in which some newly added access points share a serial fronthaul link through nearby existing access points, sets the number of newly added access points that can be connected to existing access points, and forms a chain topology with a limited number of connections; the locations of access points are modeled through a Poisson point process, which can more truly reflect spatial randomness than a grid or uniform deployment, and effectively reduces the deployment cost of newly added access points; by increasing the number of newly added access points that can be connected to existing access points, a lower deployment cost of newly added access points can be obtained under certain conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0035] Figure 1 It is a schematic diagram of the overall process of the method for deploying a cellular-free massive MIMO fronthaul topology according to the first embodiment of the present invention;

[0036] Figure 2 This is a cost comparison chart of three methods in the cellular-free massive MIMO fronthaul topology deployment method described in the second embodiment of the present invention. DETAILED DESCRIPTION

[0037] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0038] Example 1

[0039] Reference Figure 1, as an embodiment of the present invention, provides a method for deploying a cellular-free massive MIMO fronthaul topology, comprising:

[0040] S100: at least one new access point is set in the non-cellular massive MIMO system, each new access point is connected to the existing device closest to it to form a chain topology, and the expected value of the sum of the distances between the new access point and the connected device under the topology is calculated;

[0041] Specifically, the MIMO system may include 1 central processor, N1 existing access points, and N2 newly added access points.

[0042] In the embodiment of the present application, in the chain topology, at least one new access point is set in the non-cellular massive MIMO system, and each new access point is connected to the existing device closest to it to form a chain topology, including:

[0043] All existing access points are directly connected to the central processor via point-to-point fronthaul links;

[0044] Each newly added access point is connected to the existing equipment closest to it via optical fiber, and the existing equipment includes the central processor and the existing access point;

[0045] The distance from a new access point to its nearest existing device is the straight-line distance.

[0046] In the implementation manner of the present application, the existing access points and the newly added access points obey homogeneous Poisson point processes Φ1 and Φ2 with densities λ1 and λ2 respectively in a circular system area with an area of ​​S and a radius of R, and their distributions are independent of each other.

[0047] Exemplarily, the expected value of the sum of the distances between the newly added access point and its nearest existing device is expressed as:

[0048]

[0049] in, represents the distance from the i-th newly added access point to its nearest existing device, E[·] represents the expectation of the variables in brackets.

[0050] S200: setting a maximum number of newly added access points that each existing access point can connect to as a restriction condition, forming a chain topology with a limited number of connections, and calculating the expected value of the sum of the distances between the newly added access points and their connected devices under the topology;

[0051] Specifically, the maximum number restriction condition of newly added access points is set to C, which is a constant and a parameter possessed by each existing access point.

[0052] In an embodiment of the present application, in a chain topology with a limited number of connections, each newly added access point is connected to the nearest existing device via an optical fiber, and the existing device includes a central processor and an existing access point that has not reached the maximum number of connections;

[0053] The distance between a new access point and the existing device it is connected to is the straight-line distance.

[0054] In the implementation manner of the present application, in a chain topology with a limited number of connections, the connection of a newly added access point to an existing device is a random event, and the connection probability is used to characterize the connection of a newly added access point to any existing device.

[0055] For example, the number of newly added access points connected to different existing devices under the topology can be calculated according to the connection probability, and it is recorded as p n It represents the probability of a new access point connecting to the nth closest existing device. The formula is:

[0056]

[0057] in, represents the probability that a new access point is connected to the nth closest CPU and In this formula denote the gamma function and the incomplete gamma function respectively; It represents the probability of a newly added access point connecting to the existing access point closest to it, and the formula is expressed as:

[0058]

[0059] Where N is the number of all existing access points that are closest to the target access point, that is, the existing access point closest to the new access point, and the number of the closest new access point. represents the probability of satisfying the conditions in brackets, c = 3.575 is a constant, and the value of k includes non-negative integers; Indicates the number of new access points to which the nth nearest existing access point of a new access point has connected, and the existing access point is the mth nearest to these new access points, Can be traversed All values ​​of are obtained.

[0060] In an embodiment of the present application, in a chain topology with a limited number of connections, existing access points and newly added access points obey homogeneous Poisson point processes Φ1 and Φ2 with densities λ1 and λ2 respectively in a circular system area with an area of ​​S and a radius of R, and their distributions are independent of each other.

[0061] For example, further, let {p1λ2,p2λ2,…,pM λ2} represents the set of the number of existing devices connected to different distances, where M is the serial number of the farthest existing device to which the newly added access point is connected. The expected value of the sum of the distances from all newly added access points to their connected devices is expressed as:

[0062]

[0063] in, Indicates the distance from the i-th newly added access point to the existing device it is connected to.

[0064] S300: Calculating the deployment cost of a newly added access point in a chain topology and a chain topology with a limited number of connections, and calculating the deployment cost of a newly added access point in a star topology in which all newly added access points are directly connected to a central processor;

[0065] Specifically, the deployment cost of new access points includes the cost of optical fiber and new access points. The optical fiber cost includes the cost of purchasing and laying optical fiber, and the cost of new access points includes the cost of purchasing and installing new access points. The price of each kilometer of optical fiber is P f , the cost of laying optical fiber per kilometer is I f , the price of each new access point is P a , the installation price of each new access point is I a The straight-line distance between the newly added access point and the device it connects to is considered the length of the optical fiber that needs to be laid;

[0066] Furthermore, the deployment cost of a new access point in the chain topology is expressed as:

[0067]

[0068] Furthermore, the deployment cost of a new access point in a chain topology with limited connections is expressed as:

[0069]

[0070] Furthermore, in the star topology, the expected value of the sum of the distances between the newly added access points and the central processor is expressed as:

[0071]

[0072] in, represents the distance from the i-th newly added access point to the central processor;

[0073] Furthermore, the deployment cost of a new access point in the star topology is expressed as:

[0074]

[0075] S400: Compare the three deployment costs, take the lowest deployment cost of new access points as the goal, and obtain the applicable conditions of the chain topology with limited number of connections.

[0076] In the implementation manner of the present application, three deployment costs are compared, and the lowest deployment cost of new access points is taken as the goal to obtain the applicable conditions of the chain topology with limited number of connections, including:

[0077] When the area S and the density λ1 of existing access points are the same, the connection limit number C of existing access points is changed;

[0078] Compare the deployment costs of new access points required for different fronthaul topologies under different existing access point densities λ2.

[0079] It should be noted that under the same system conditions, the cost of deploying the same number of new access points is only related to the length of optical fiber required to be purchased. By comparing the deployment cost formulas of the three topologies of new access points, the applicable conditions of the chain topology with limited number of connections are obtained. By substituting the system parameters into the deployment cost formulas of the three topologies of new access points, the deployment cost of the new access points in each topology can be quickly obtained, namely: C1, C2, C3.

[0080] In the implementation mode of this application, the applicable conditions are:

[0081] when When the number of connections is limited, the chain topology saves more deployment costs of adding access points than the chain topology;

[0082] Where M is the number of the farthest existing device to which the new access point is connected, and p n It represents the probability that a new access point is connected to the nth closest existing device.

[0083] It should also be noted that by comparing C1, C2, and C3, it can be seen that when When , the chain topology is better than the star topology, and this condition is easily satisfied in real systems.

[0084] The above scheme provides a closed-form solution to the deployment cost of a chain topology with limited number of connections, proving that this method can achieve lower deployment costs under the same conditions if the judgment conditions are met, which is mainly reflected in the shorter optical fiber length required for deployment.

[0085] The above is a schematic scheme of a cellular-free massive MIMO fronthaul topology deployment method of this embodiment. It should be noted that the technical solution of the system for cellular-free massive MIMO fronthaul topology deployment and the technical solution of the above-mentioned cellular-free massive MIMO fronthaul topology deployment method belong to the same concept. For details not described in detail in the technical solution of the cellular-free massive MIMO fronthaul topology deployment system in this embodiment, please refer to the description of the technical solution of the above-mentioned cellular-free massive MIMO fronthaul topology deployment method.

[0086] The non-cellular massive MIMO fronthaul topology deployment system in this embodiment includes:

[0087] A first setting and calculation module is used to set at least one new access point in the non-cellular massive MIMO system, each new access point is connected to the existing device closest to it to form a chain topology, and calculate the expected value of the sum of the distances between the new access point and its connected device under the topology;

[0088] A second setting and calculation module is used to set the maximum number of new access points that each existing access point can connect to as a restriction condition, form a chain topology with a limited number of connections, and calculate the expected value of the sum of the distances between the new access points and their connected devices under the topology;

[0089] a cost calculation module, used to calculate the deployment cost of new access points in a chain topology and a chain topology with a limited number of connections, and to calculate the deployment cost of new access points in a star topology in which all new access points are directly connected to a central processor;

[0090] The comparison module is used to compare the three deployment costs, with the goal of minimizing the deployment cost of new access points, and obtain the applicable conditions of the chain topology with limited number of connections.

[0091] This embodiment further provides a computing device, which is applicable to the case of non-cellular massive MIMO fronthaul topology deployment, including:

[0092] A memory and a processor; the memory is used to store computer-executable instructions, and the processor is used to execute computer-executable instructions to implement the method for implementing a cellular-free large-scale MIMO fronthaul topology deployment as proposed in the above embodiment.

[0093] This embodiment also provides a storage medium on which a computer program is stored. When the program is executed by a processor, the method for implementing a cellular-free massive MIMO fronthaul topology deployment as proposed in the above embodiment is implemented.

[0094] The storage medium proposed in this embodiment and the method for implementing a cellular-free large-scale MIMO fronthaul topology deployment proposed in the above embodiment belong to the same inventive concept. The technical details not described in detail in this embodiment can be referred to the above embodiment, and this embodiment has the same beneficial effects as the above embodiment.

[0095] Through the above description of the implementation methods, the technicians in the relevant field can clearly understand that the present invention can be implemented by means of software and necessary general hardware, and of course can also be implemented by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as a computer floppy disk, read-only memory (ReadOnly, Memory, ROM), random access memory (RandomAccess Memory, RAM), flash memory (FLASH), hard disk or optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, server, or network device, etc.) to perform the methods of various embodiments of the present invention.

[0096] Example 2

[0097] Reference Figure 2 Based on the previous embodiment, this embodiment provides an application comparison case of a non-cellular massive MIMO fronthaul topology deployment method to illustrate the feasibility and beneficial effects of our solution.

[0098] The method of the present invention obtains the required fiber lengths for three different topological modes, and the fiber lengths determine the deployment cost of the newly added access points. 2 , the existing access point density λ1=10APs / km 2 Under the condition of 2 Average increase to 100APs / km 2 , the results are shown in Table 1:

[0099] Table 1 Comparison of costs in three topological states

[0100]

[0101]

[0102] Table 1 compares the required fiber lengths in different topologies. Figure 2 As shown;

[0103] It can be seen that under the current system conditions, the required optical fiber length of the chain topology considered by the method of the present invention is shorter than that of the traditional star topology, and the optical fiber length required for the chain topology with limited connection number is shorter than that of the traditional star topology. By increasing the connection limit number C, a lower deployment cost of the new access point can be achieved, which provides a reference value for fully saving the deployment cost of the new access point. At the same time, in theory, the minimum value of C that the chain topology with limited connection number saves compared with the chain topology in different MIMO systems can be obtained through the deployment cost calculation formula.

[0104] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for deploying a non-cellular massive MIMO fronthaul topology, characterized in that: include: At least one new access point is set in the non-cellular massive MIMO system, each new access point is connected to the existing device closest to it to form a chain topology, and the expected value of the sum of the distances between the new access point and its connected devices under the topology is calculated; The maximum number of new access points that each existing access point can connect to is set as a restriction condition to form a chain topology with a limited number of connections, and the expected value of the sum of the distances between the new access points and their connected devices under this topology is calculated; Calculate the deployment cost of new access points in a chain topology and a chain topology with a limited number of connections, and calculate the deployment cost of new access points in a star topology where all new access points are directly connected to a central processor; By comparing the three deployment costs and taking the lowest deployment cost of new access points as the goal, the applicable conditions of the chain topology with limited number of connections are obtained.

2. The method for deploying a cellular-free massive MIMO fronthaul topology according to claim 1, wherein: The method of setting at least one new access point in the non-cellular massive MIMO system, wherein each new access point is connected to the nearest existing device to form a chain topology, includes: All existing access points are directly connected to the central processor via point-to-point fronthaul links; Each newly added access point is connected to the existing device closest to it through an optical fiber, and the existing device includes a central processor and an existing access point; The distance between the newly added access point and the nearest existing device is a straight-line distance.

3. The method for deploying a cellular-free massive MIMO fronthaul topology according to claim 1, wherein: In the chain topology with limited number of connections, each newly added access point is connected to the nearest existing device via an optical fiber, and the existing device includes a central processor and an existing access point that has not reached the maximum number of connections; The distance between a new access point and the existing device it is connected to is the straight-line distance.

4. The method for deploying a cellular-free massive MIMO fronthaul topology according to claim 2 or 3, wherein: The existing access points and the newly added access points respectively obey homogeneous Poisson point processes Φ1 and Φ2 with densities λ1 and λ2 in a circular system region with an area of ​​S and a radius of R, and are distributed independently of each other.

5. The method for deploying a cellular-free massive MIMO fronthaul topology according to claim 3, wherein: In the chain topology with limited number of connections, a newly added access point is connected to any existing device by a connection probability.

6. The method for deploying a cellular-free massive MIMO fronthaul topology according to claim 1 or 5, wherein: By comparing the three deployment costs and taking the lowest deployment cost of new access points as the goal, we can obtain the applicable conditions for the chain topology with limited number of connections, including: When the area S and the density λ1 of existing access points are the same, the connection limit number C of existing access points is changed; Compare the deployment costs of new access points required for different fronthaul topologies under different existing access point densities λ2.

7. The method for deploying a cellular-free massive MIMO fronthaul topology according to claim 6, wherein: The applicable conditions are: when When the number of connections is limited, the chain topology saves more deployment costs of adding access points than the chain topology; Where M is the number of the farthest existing device to which the new access point is connected, and p n It represents the probability that a new access point is connected to the nth closest existing device.

8. A system using the method for deploying a cellular-free massive MIMO fronthaul topology as claimed in claim 1, characterized in that: include: A first setting and calculation module is used to set at least one new access point in the non-cellular massive MIMO system, each new access point is connected to the existing device closest to it to form a chain topology, and calculate the expected value of the sum of the distances between the new access point and its connected device under the topology; A second setting and calculation module is used to set the maximum number of new access points that each existing access point can connect to as a restriction condition, form a chain topology with a limited number of connections, and calculate the expected value of the sum of the distances between the new access points and their connected devices under the topology; a cost calculation module, used to calculate the deployment cost of new access points in a chain topology and a chain topology with a limited number of connections, and to calculate the deployment cost of new access points in a star topology in which all new access points are directly connected to a central processor; The comparison module is used to compare the three deployment costs, with the goal of minimizing the deployment cost of new access points, and obtain the applicable conditions of the chain topology with limited number of connections.

9. An electronic device, comprising: Memory and processor; The memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions. When the computer-executable instructions are executed by the processor, the steps of the cellular-free large-scale MIMO fronthaul topology deployment method described in any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, implement the steps of the method for deploying a cellular-free massive MIMO fronthaul topology as described in any one of claims 1 to 7.

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