Method and system for dynamically and optimally enabling ADS-B function in multi-RRH environments

Abstract

This application provides a method and system for dynamically and optimally activating ADS-B functionality in a multi-RRH environment. The method includes: receiving ADS-B broadcast information and collecting reception quality parameters in real time (assessed by the number of ADS-B messages received per unit time, the number of effectively identified aircraft, and the maximum reception distance); reporting the ADS-B broadcast information and reception quality parameters to the DU; obtaining the current communication load status of each RRH in real time through the DU; determining the optimal RRH node based on the reception quality parameters and the current communication load status; and using the optimal RRH node for dynamic ADS-B sensing. This application dynamically selects the optimal RRH node based on communication load and ADS-B reception quality, effectively improving the system's resource utilization efficiency. It is suitable for low-altitude airspace communication infrastructure construction and provides technical support for the deep integration of future aviation and communication systems.

Description

Technical Field

[0001] This invention relates to the field of communication technology, and in particular to a method and system for dynamically and preferentially enabling ADS-B function in a multi-RRH environment. Background Technology

[0002] ADS-B (Automatic Dependent Surveillance-Broadcast) is a broadcast aircraft surveillance technology that uses pulse position modulation (PPM) to broadcast the aircraft's position, speed, and other information to achieve air traffic management.

[0003] The Remote Radio Head (RRH) is a core component of modern wireless communication systems, primarily used for transmitting and receiving radio frequency (RF) signals, filtering, amplification, and A / D and D / A conversion. Its function is to convert the digital signals processed by the baseband unit (BBU) into RF signals (up-conversion) and transmit them through the antenna; simultaneously, it converts the received RF signals (down-conversion) back into digital signals for processing by the BBU. It is one of the commonly used distributed architecture components in current 4G and 5G communication systems.

[0004] Traditional ADS-B receivers are typically deployed independently and isolated from the wireless communication system, resulting in equipment redundancy and increased complexity in system deployment and maintenance.

[0005] With the rapid development of the low-altitude industry, although the technologies in the fields of air surveillance (such as ADS-B) and wireless communication (such as RRH) are mature, there is still a significant disconnect in practical applications, with a lack of integration, interoperability, and collaboration between the systems. However, with the increasing demand for low-altitude airspace management and low-altitude communication support, the need for the integration of air surveillance and communication systems is becoming increasingly urgent.

[0006] First, from the perspective of system functional architecture, the ADS-B receiver and RRH are highly similar in physical structure and signal processing flow, both including radio frequency reception, filtering, up / down conversion, analog-to-digital conversion and digital signal processing. This consistency in architecture provides a good foundation for the integration of the two at the hardware level.

[0007] Secondly, the broadcast information received by ADS-B can be directly uploaded to the regulatory platform through the existing data channels of RRH without the need to deploy a separate data backhaul link. This channel reuse method not only simplifies the system architecture but also significantly reduces the overall construction cost.

[0008] However, in existing technologies, ADS-B systems and communication RRHs are usually deployed on independent platforms, which cannot share hardware resources and a unified management and maintenance system. This results in poor interoperability between systems, high operation and maintenance costs, and makes it difficult to support the construction needs of the future low-altitude integrated communication regulatory system. Summary of the Invention

[0009] The purpose of this invention is to provide a method and system for dynamically and preferentially enabling ADS-B functionality in multiple RRH environments, aiming to solve the aforementioned problems in the prior art.

[0010] This invention provides a method for dynamically and preferentially enabling ADS-B functionality in a multi-RRH environment, comprising:

[0011] Each wireless communication radio frequency unit RRH receives ADS-B broadcast information and collects reception quality parameters in real time, and reports the ADS-B broadcast information and the reception quality parameters to the scheduling unit DU;

[0012] The current communication load status of each RRH is obtained in real time through DU. The optimal RRH node is obtained based on the reception quality parameters and the current communication load status, and the optimal RRH node is used to dynamically sense ADS-B.

[0013] This invention provides a system for dynamically and preferentially enabling ADS-B functionality in multiple RRH environments, comprising:

[0014] The data acquisition module is used to receive ADS-B broadcast information through each wireless communication radio frequency unit RRH and collect reception quality parameters in real time, and report the ADS-B broadcast information and the reception quality parameters to the scheduling unit DU;

[0015] The intelligent scheduling module is used to obtain the current communication load status of each RRH in real time through DU, obtain the optimal RRH node based on the reception quality parameters and the current communication load status, and use the optimal RRH node to perform dynamic sensing of ADS-B.

[0016] The following beneficial effects can be achieved by adopting the embodiments of the present invention: The embodiments of the present invention propose a method for realizing ADS-B sensing based on RRH. This method does not require the additional deployment of a dedicated ADS-B receiver, but utilizes existing RRH equipment to achieve functional integration, which significantly reduces construction and maintenance costs; and through hardware sharing and intelligent scheduling, it reduces equipment redundancy and effectively improves the overall integration of the system. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in one or more embodiments of this specification or in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this specification. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a flowchart of a method for dynamically and optimally enabling ADS-B functionality in multiple RRH environments according to an embodiment of the present invention;

[0019] Figure 2 This is a flowchart of the process for reading the ADS-B information list according to an embodiment of the present invention;

[0020] Figure 3 This is a flowchart of the ADS-B information update reporting process according to an embodiment of the present invention;

[0021] Figure 4 This is a schematic diagram of the subscription termination alarm process according to an embodiment of the present invention;

[0022] Figure 5 This is a flowchart illustrating the specific implementation steps of an embodiment of the present invention;

[0023] Figure 6 This is a schematic diagram of a system for dynamically and optimally enabling ADS-B functionality in multiple RRH environments, according to an embodiment of the present invention. Detailed Implementation

[0024] To enable those skilled in the art to better understand the technical solutions in one or more embodiments of this specification, the technical solutions in one or more embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this specification, and not all of the embodiments. Based on one or more embodiments of this specification, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of this document.

[0025] Method Implementation Examples

[0026] According to embodiments of the present invention, a method for dynamically and preferentially enabling ADS-B functionality in multiple RRH environments is provided. Figure 1 This is a flowchart of a method for dynamically and preferentially enabling ADS-B functionality in a multi-RRH environment according to an embodiment of the present invention. Figure 1 As shown, the method for dynamically and preferentially enabling ADS-B functionality in a multi-RRH environment according to an embodiment of the present invention specifically includes:

[0027] Step S101: Receive ADS-B broadcast information and collect reception quality parameters in real time through each wireless communication radio frequency unit RRH, and report the ADS-B broadcast information and the reception quality parameters to the scheduling unit DU;

[0028] The reception quality parameters include the number of ADS-B messages received per unit time, the number of effectively identified aircraft, and the maximum reception distance.

[0029] Step S102 involves obtaining the current communication load status of each RRH in real time through the DU, obtaining the optimal RRH node based on the received quality parameters and the current communication load status, and using the optimal RRH node to dynamically sense ADS-B. Specifically, this includes:

[0030] Based on the received quality parameters and the current communication load status, each RRH is scored using Formula 1 and Formula 2, and the RRH node with the highest score is selected as the optimal RRH node.

[0031] Formula 1;

[0032] Formula 2;

[0033] in, This represents the normalized value of the number of ADS-B messages received per unit time. This represents the normalized value of the number of unique aircraft. This represents the normalized value of the maximum receiving distance. , , This indicates the weights of the three indicators, satisfying... , This represents the receive link quality score of the i-th RRH. This represents the normalized communication load value of the i-th RRH. As a load-sensitive weighting factor, This represents the score of the i-th RRH;

[0034] The current communication load status includes the number of currently connected user terminals, uplink and downlink real-time service traffic, local processor or FPGA resource utilization, and time slot scheduling tension.

[0035] The method further includes:

[0036] The optimal RRH node is re-evaluated and scheduled according to a preset evaluation period or when ADS-B reception performance deteriorates or communication load surges;

[0037] It also provides clients with ADS-B information list reading, push notification, subscription, and subscription termination services based on the O-RAN NETCONF management framework.

[0038] The following describes in detail the above-mentioned technical solution of the present invention with reference to a specific method for dynamically and preferentially enabling ADS-B function in a multi-RRH environment according to an embodiment of the present invention.

[0039] This invention integrates ADS-B reception functionality into the RRH (Rapid Reception Hub), eliminating the need for a dedicated ADS-B receiver. This reduces deployment costs, improves system integration, and achieves deep integration of communication and aviation surveillance, making it particularly suitable for low-altitude airspace communication infrastructure construction. Typically, a base station consists of multiple radio frequency units linked to a baseband processing unit via optical fiber. This invention first provides an intelligent scheduling method for an ADS-B and RRH integrated system. This method dynamically selects the optimal RRH node to enable ADS-B monitoring in a multi-RRH deployment environment, thereby improving system resource utilization efficiency and ADS-B reception performance, and reducing the management plane load between the baseband and radio frequency units. A communication mechanism between the RRU (Rapid Reception Unit) and BBU (Baseband Unit) also needs to be designed to ensure the correctness of information transmission. This invention does not involve the encoding or decoding of ADS-B information.

[0040] I. Selection of ADS-B Master Equipment

[0041] Given that the ADS-B protocol itself is a one-way broadcast mechanism, it only includes fields such as aircraft identification information, flight status information, and additional status information, and does not include typical communication quality indicators such as received signal strength (RSSI), signal-to-noise ratio (SNR), multipath effect, or link quality. Therefore, the quality of its deployment location cannot be directly judged from the protocol level.

[0042] To achieve precise deployment of ADS-B reception functionality and optimal utilization of system resources, a multi-RRH (Remote Radio Head) collaborative evaluation and selection mechanism based on a centralized architecture is proposed. It is assumed that the system consists of at least four RRHs with ADS-B reception capabilities, all of which are connected to a unified distributed unit (DU) via a fronthaul link. The DU manages and schedules the activation of the ADS-B function.

[0043] The mechanism includes the following core steps:

[0044] 1. Initialization Phase

[0045] Upon system startup or after a predetermined time interval, all RRHs synchronously enter ADS-B monitoring mode. Within the set time window, each RRH passively receives over-the-air ADS-B broadcast signals and locally records the following key performance parameters:

[0046] A. Number of ADS-B messages received per unit time (Message Rate): Reflects air traffic density and signal reachability within the area;

[0047] B. Aircraft Count: Used to determine the number of observable targets;

[0048] C. Maximum Received Range (Max Range): Calculated using decoded ADS-B location information, this range is the distance to the farthest target that can be detected, indirectly reflecting link gain and line-of-sight conditions.

[0049] The above three indicators together constitute a proxy indicator system for receiver link quality, serving as alternative parameters when RSSI or SNR is unavailable in traditional wireless communication.

[0050] 2. Performance reporting phase

[0051] After the monitoring window ends, each RRH transmits its locally collected ADS-B performance data back to DU via the fronthaul link. To reduce bandwidth consumption, the performance information can be transmitted using normalized processing and compressed encoding. DU, as the system scheduling core, aggregates the ADS-B capability data of all RRHs to form an overall perception view.

[0052] 3. Load Awareness Phase

[0053] DU simultaneously obtains the current communication load status of each RRH, including but not limited to: the number of currently connected user terminals; uplink and downlink real-time service traffic; local processor / FPGA resource utilization; and the time slot scheduling tension.

[0054] These parameters are used to measure the current workload of communication services undertaken by the RRH, providing constraints for subsequent scheduling decisions.

[0055] 4. Optimization and Evaluation Phase

[0056] The DU scores all RRHs according to a preset comprehensive scoring function. The scoring function considers ADS-B receive quality and communication load weighting, and is defined as follows:

[0057] (1);

[0058] in, The quality score of the i-th RRH receive link (calculated by weighting the normalized values ​​of the three proxy metrics mentioned above); This represents the normalized communication load value (e.g., between 0 and 1) of the i-th RRH. As a load-sensitive weighting factor, This represents the score of the i-th RRH.

[0059] By adjusting The value can dynamically control the system's scheduling preference for ADS-B performance or communication resource protection.

[0060] In the optimization and evaluation phase, the core is to construct a reasonable scoring model that can... It is broken down into the weighted sum of the following three indicators:

[0061] (2);

[0062] in, This represents the normalized value of the number of ADS-B messages received per unit time. This represents the normalized value for the number of unique aircraft. This represents the normalized value of the maximum receiving distance; , , This indicates the weights of the three indicators, satisfying... .

[0063] The model is highly adjustable and adaptable to different environments, and supports dynamic weight adjustment strategies (such as appropriately relaxing communication load weights when the load decreases at night).

[0064] 5. Optimal RRH Selection and Activation Phase

[0065] The DU selects the RRH node with the highest score and sends it a control command to enable the ADS-B function, so that it can continuously receive ADS-B message information; the other RRH nodes retain the communication function.

[0066] 6. Maintenance and Update Phase

[0067] The system can be set to perform periodic evaluations or automatically re-execute the above scheduling process when ADS-B performance is detected to be degraded or communication load is suddenly increased.

[0068] Through the above implementation methods, the intelligent integrated deployment of ADS-B functionality in multiple RRH systems is realized, reducing redundant equipment configuration and resource waste, and effectively improving the overall operating efficiency of the system.

[0069] II. ADS-B Information Management

[0070] The ADS-B management mechanism is based on the O-RAN NETCONF management framework, and its specifications cover control plane messages for O-RUs or peer devices. This mechanism comprises two types of operating entities: the ADS-B server and the ADS-B client. Hereinafter, we will refer to them as server and client, respectively, for simplicity.

[0071] Operating entity:

[0072] 1) Server: NETCONF Server, located on RU or peer device.

[0073] 2) Client: NETCONF Client, located on DU / BBU or peer device.

[0074] The server is the main entity that maintains ADS-B information. It internally maintains an "activity information list" and sends "information notifications" to subscribers when ADS-B information changes. The information notifications only include the changed parts and do not push all current ADS-B information as a whole.

[0075] The server provides the following main functions to the outside world: "Read ADS-B information list", "Notification", "Subscription", and "Stop Subscription".

[0076] Read ADS-B information list: The client can use this function to retrieve all currently active alarm information from the server.

[0077] Subscribe / Unsubscribe: The client initiates a request to the server to subscribe to or stop the notification service.

[0078] Notification: The server pushes a notification to the client when alarm information changes.

[0079] Specifically: 1. Read the ADS-B information list, such as... Figure 2 As shown:

[0080] The client reads the ADS-B information list through the NETCONF rpc operation "get".

[0081] "Read ADS-B Information List" is a full table operation with strong initialization properties. It is mainly used during the management relationship establishment phase to obtain the initial state of ADS-B information. During operation, this method can also be used periodically at low frequency to achieve regular full table synchronization of information between alarm management and alarm management, in order to prevent information from being out of sync for a long time due to unexpected situations.

[0082] 2. Report ADS-B information updates, such as Figure 3 As shown:

[0083] After a NETCONF client subscribes to alarm notifications, the NETCONF server is responsible for sending alarm notifications (ADS-B-notif) to the client. ADS-B information reporting is presented in the form of information notifications. The server sends alarm notifications to subscribers (clients) based on filtering conditions when it detects alarm changes that require notification. Notifications are sent at the single-item level; not all information is sent to the client.

[0084] 3. Terminating the alarm subscription process, such as... Figure 4 As shown:

[0085] If you wish to terminate your subscription, the client sends "" in the subscription session. <close-session>"Simply follow the instructions."

[0086] In summary, the design of the embodiments of the present invention mainly includes the following aspects:

[0087] A. Hardware integration: Integrating the ADS-B receiving function into the wireless communication radio frequency unit (RRH) enables hardware resource sharing and reduces equipment redundancy.

[0088] B. Intelligent scheduling: By dynamically selecting the optimal RRH node to enable the ADS-B function, the communication load and ADS-B reception performance are balanced.

[0089] C. Data reuse: Utilize RRH's existing data channels to upload ADS-B information, avoiding the need to deploy a separate backhaul link.

[0090] D. Management Framework: Based on the O-RAN NETCONF management framework, the subscription, notification and update of ADS-B information are realized to ensure the efficiency of information synchronization.

[0091] E. Scoring Model: The comprehensive scoring function used in dynamic scheduling And its parameter settings.

[0092] F. Information Management Mechanism: Design of ADS-B information subscription, notification, and termination process based on NETCONF.

[0093] G. Hardware Design: Design of the hardware module for implementing ADS-B reception in RRH, including RF signal processing, filtering, and frequency conversion.

[0094] Preferably, the embodiments of the present invention also propose a fixed allocation scheme, that is, a portion of RRHs are pre-allocated specifically for ADS-B reception and do not participate in dynamic scheduling; and a distributed processing scheme, that is, each RRH independently processes ADS-B signals and aggregates the results to the monitoring platform.

[0095] Specifically, such as Figure 5 As shown, the implementation steps of this embodiment of the invention include:

[0096] Step 501: All RRHs receive ADS-B broadcast information and collect reception quality parameters;

[0097] Step 502: Each RRH reports the collected data to the scheduling unit (DU);

[0098] Step 503: DU synchronously obtains the current communication load status of each RRH;

[0099] Step 504: DU calculates the overall score for each RRH based on the preset scoring model;

[0100] Step 505: DU selects the optimal RRH and issues an instruction to enable ADS-B;

[0101] Step 506: Disable ADS-B function for other RRHs;

[0102] Step 507 (optional): Periodically re-evaluate the system or reselect RRH when performance degrades.

[0103] System Implementation Examples

[0104] According to embodiments of the present invention, a system for dynamically and preferentially enabling ADS-B function in multiple RRH environments is provided. Figure 6 This is a schematic diagram of a system for dynamically and preferentially enabling ADS-B functionality in multiple RRH environments according to an embodiment of the present invention, as shown below. Figure 6 As shown, the system for dynamically and preferentially enabling ADS-B function in multiple RRH environments according to an embodiment of the present invention specifically includes:

[0105] The data acquisition module 60 is used to receive ADS-B broadcast information through each wireless communication radio frequency unit RRH and collect reception quality parameters in real time, and report the ADS-B broadcast information and the reception quality parameters to the scheduling unit DU;

[0106] The reception quality parameters include the number of ADS-B messages received per unit time, the number of effectively identified aircraft, and the maximum reception distance.

[0107] The intelligent scheduling module 62 is used to obtain the current communication load status of each RRH in real time through DU, obtain the optimal RRH node based on the received quality parameters and the current communication load status, and use the optimal RRH node to dynamically sense ADS-B. Specifically, it is used for:

[0108] Based on the received quality parameters and the current communication load status, each RRH is scored using Formula 1 and Formula 2, and the RRH node with the highest score is selected as the optimal RRH node.

[0109] Formula 1;

[0110] Formula 2;

[0111] in, This represents the normalized value of the number of ADS-B messages received per unit time. This represents the normalized value of the number of unique aircraft. This represents the normalized value of the maximum receiving distance. , , This indicates the weights of the three indicators, satisfying... , This represents the receive link quality score of the i-th RRH. This represents the normalized communication load value of the i-th RRH. As a load-sensitive weighting factor, This represents the score of the i-th RRH;

[0112] The current communication load status includes the number of currently connected user terminals, uplink and downlink real-time service traffic, local processor or FPGA resource utilization, and time slot scheduling tension.

[0113] The system further includes:

[0114] The dynamic evaluation module is used to re-evaluate and schedule the optimal RRH node according to a preset evaluation period or when the ADS-B receiving performance degrades or the communication load increases suddenly.

[0115] The information management module is used to provide clients with ADS-B information list reading, push notification, subscription, and subscription termination services based on the O-RAN NETCONF management framework.

[0116] The embodiments of the present invention are system embodiments corresponding to the above method embodiments. The specific operation of each module can be understood by referring to the description of the method embodiments, and will not be repeated here.

[0117] In summary, the embodiments of the present invention specifically include the following beneficial effects:

[0118] 1. Reduced costs: No need to deploy a dedicated ADS-B receiver; functional integration is achieved using existing RRH equipment, significantly reducing construction and maintenance costs.

[0119] 2. Improve integration: Reduce device redundancy and improve the overall system integration through hardware sharing and intelligent scheduling.

[0120] 3. Dynamic optimization: Dynamically select the optimal RRH node based on communication load and ADS-B reception quality to improve resource utilization efficiency.

[0121] 4. Simplified operation and maintenance: Unified management of communication and ADS-B functions reduces system complexity and facilitates maintenance and upgrades.

[0122] 5. High scalability: It is suitable for the construction of low-altitude airspace communication infrastructure, providing technical support for the deep integration of future aviation and communication systems.

[0123] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for dynamically selecting and enabling ADS-B function in a multi-RRH environment, characterized in that Comprising: receiving ADS-B broadcast information and collecting receiving quality parameters in real time through ADS-B receiving modules integrated in each wireless communication radio unit RRH, and reporting the ADS-B broadcast information and the receiving quality parameters to a scheduling unit DU; obtaining current communication load states of each RRH in real time through the DU, obtaining an optimal RRH node based on the receiving quality parameters and the current communication load states, and using the optimal RRH node for dynamic sensing of ADS-B.

2. The method of claim 1, wherein, The method further comprises: re-evaluating and scheduling the optimal RRH node according to a preset evaluation period or when ADS-B receiving performance decreases and communication load suddenly increases; and providing ADS-B information list reading, push notification, subscription and stop subscription services to clients based on the O-RAN NETCONF management framework.

3. The method of claim 1, wherein, The receiving quality parameters include the number of ADS-B messages received per unit time, the number of effectively identified aircraft, and the maximum receiving distance.

4. The method of claim 1, wherein, The current communication load states include the number of currently accessed user terminals, uplink and downlink real-time traffic, local processor or FPGA resource utilization, and time slot scheduling tightness.

5. The method of claim 1, wherein, Based on the receiving quality parameters and the current communication load states, the optimal RRH node is obtained specifically by: Based on the receiving quality parameters and the current communication load states, each RRH is scored using Formula 1 and Formula 2, and the RRH node with the highest score is taken as the optimal RRH node. Formula 1 ; Equation 2; wherein, denotes a normalized value of the number of received ADS-B messages per time unit, denotes a normalized value of the number of unique aircrafts, denotes a normalized value of the maximum reception distance, , , denotes a weight of the three indicators, satisfying , denotes a reception link quality score of the i-th RRH, denotes a normalized value of the communication load of the i-th RRH, is a load-sensitive weight factor, denotes a score of the i-th RRH.

6. A system for dynamically and preferentially enabling ADS-B function in multiple RRH environments, characterized in that... Comprising: a data collection module for receiving ADS-B broadcast information and collecting receiving quality parameters in real time through ADS-B receiving modules integrated in each wireless communication radio unit RRH, and reporting the ADS-B broadcast information and the receiving quality parameters to a scheduling unit DU; an intelligent scheduling module for obtaining current communication load states of each RRH in real time through the DU, obtaining an optimal RRH node based on the receiving quality parameters and the current communication load states, and using the optimal RRH node for dynamic sensing of ADS-B.

7. The system of claim 6, wherein, The system further comprises: a dynamic evaluation module for re-evaluating and scheduling the optimal RRH node according to a preset evaluation period or when ADS-B receiving performance decreases and communication load suddenly increases; an information management module for providing ADS-B information list reading, push notification, subscription and stop subscription services to clients based on the O-RAN NETCONF management framework.

8. The system of claim 6, wherein, The receiving quality parameters include the number of ADS-B messages received per unit time, the number of effectively identified aircraft, and the maximum receiving distance.

9. The system of claim 6, wherein, The current communication load states include the number of currently accessed user terminals, uplink and downlink real-time traffic, local processor or FPGA resource utilization, and time slot scheduling tightness.

10. The system of claim 6, wherein, The intelligent scheduling module is specifically configured to: Based on the receiving quality parameters and the current communication load states, each RRH is scored using Formula 1 and Formula 2, and the RRH node with the highest score is taken as the optimal RRH node. Formula 1 ; Formula 2: wherein, denotes a normalized value of the number of received ADS-B messages per time unit, denotes a normalized value of the number of unique aircrafts, denotes a normalized value of the maximum reception distance, , , denotes a weight of the three indicators, satisfying , denotes a reception link quality score of the i-th RRH, denotes a normalized value of the communication load of the i-th RRH, is a load-sensitive weight factor, denotes a score of the i-th RRH.

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