CN103139890B

CN103139890B - Method, base station and the low power nodes of cell coverage area are adjusted in communication system

Info

Publication number: CN103139890B
Application number: CN201110392862.XA
Authority: CN
Inventors: 田辉; 田鹏; 高松涛; 张军; 高砾琦; 王静; 佘小明; 陈岚
Original assignee: NTT Docomo Inc
Current assignee: NTT Docomo Inc
Priority date: 2011-12-01
Filing date: 2011-12-01
Publication date: 2017-11-24
Anticipated expiration: 2031-12-01
Also published as: JP2013150301A; JP6125213B2; CN103139890A

Abstract

The embodiment of the invention discloses method, base station and the low power nodes that cell coverage area is adjusted in a kind of communication system.This method includes：First equipment obtains the first communication performance parameter of one or more users in the first equipment institute service user, the second communication performance parameter of one or more users in the second equipment institute service user of the second equipment transmission is received, the first equipment and the second equipment are respectively one in normal base station and low power nodes；Obtain first threshold and the Second Threshold not less than first threshold using the first communication performance parameter, by the second communication performance parameter and first threshold and Second Threshold respectively compared with；When the second communication performance parameter, which is less than the first covering, adjusts threshold value, adjustment mode is determined to reduce the offset value in the current cell coverage expansion scheme of low power nodes；Or when the second communication performance parameter is more than the second covering and adjusts threshold value, determine that adjustment mode to increase the offset value, is notified the second equipment by adjustment mode.

Description

Method for adjusting cell coverage in communication system, base station and low-power node

Technical Field

The embodiment of the invention relates to the technical field of wireless communication, in particular to a method for adjusting a cell coverage area in a communication system, a base station and a low-power node.

Background

As the demand for data traffic in wireless communication networks increases, traditional cell splitting will be more difficult to support data traffic capacity by deploying additional conventional base stations. Therefore, the introduction of low power nodes will become a trend of network deployment. A conventional base station refers to a base station with higher transmission power relative to a low power node, and has a larger coverage area, such as a Macro Cell base station, and the like, and also covers a larger Cell, such as a Macro Cell. The low power node is relative to a conventional base station, also called Local cell base station (Local eNodeB), and mainly includes, for example, a micro base station (micro eNodeB), a pico base station (pico eNodeB), a femto base station (femto eNodeB), a Relay node (Relay), a radio remote node (RRH), a home base station (HeNB), and the like, and its transmission power is low, so that the coverage of a cell is also small, such as a micro cell, a pico cell, and the like.

A Heterogeneous Network (Heterogeneous Network) refers to a deployment scenario including one or more base stations (including conventional base stations, such as Macro Cell base stations) described above, and can be deployed according to different requirements of application, service, and coverage, so as to effectively support the requirement of broadband media users on high data rate, shorten the distance between the users and the base stations, and greatly improve the peak data rate, peak spectral efficiency, Cell average spectral efficiency, and Cell boundary user performance of a wireless communication system.

In the heterogeneous network, since the transmission Power of the low Power node is relatively low, if the cell selection is performed according to the conventional standard, that is, completely according to the level of the downlink Reference Signal Received Power (RSRP) measured by the user, the problem of asymmetric uplink and downlink coverage of the low Power node may occur. In addition, since the coverage area of the low-power node is small, the number of access users is small, and the wireless resources cannot be fully utilized. Therefore, the prior art proposes a Cell coverage Extension (CRE) scheme, as shown in formula (1), that is, when a user performs Cell selection, an offset (bias) (in dB) is added to the received power of the original low-power node signal, and a Cell with the largest sum of the received power and the offset is selected as an access Cell. That is, the bias value enlarges the coverage of the low power node, so that more users can obtain service through the low power node, and the wireless resources of the low power node can be more fully utilized.

CellID_serving＝argmax_{i}{RSRP_i+bias_i} (1)

In the CRE technology, the setting of the bias value is very important, and directly determines the degree of coverage expansion of the low-power node, thereby influencing the number of access users.

However, a user accessing the low power node may receive a signal strength from the low power node that is less than an interfering signal strength from the macro base station due to the offset, and may be severely interfered with by the macro base station. To reduce interference, a quasi Blank Subframe (ABS) may be combined as a time domain interference coordination method. As shown in fig. 1, in order to reduce interference experienced by a low power node User (e.g., a Pico User Equipment (PUE)), a part of downlink transmission subframes of a regular base station may be configured as quasi blank subframes, and no data is transmitted on the subframes, and only some necessary signaling, such as PSS/SSS/PBCH/CRS, is transmitted.

Fig. 2 is a schematic diagram of a bias configuration process in the prior art. As shown, the conventional base station determines the bias value for all low power nodes within its coverage area according to the configuration, and informs each low power node of the bias value at system initialization. Thereafter, the system operates according to the configured bias values at initialization, that is, the conventional base station configures the bias values of the low power nodes to the users accessing the conventional base station, and the low power nodes also configure the bias values thereof to the users accessing the low power nodes. And the user selects the cells according to the received bias values of the low-power nodes and the measured received power of the cells. In the existing CRE technology, the bias value is generally uniformly set by the system, and all low-power nodes under the coverage of a conventional base station generally adopt the same bias value. Moreover, the bias value is configured only at system initialization and is not generally changed after the system starts operating.

Since there may be many low power nodes in the coverage area of a conventional base station, and the distances between the low power nodes and the conventional base station are different, the user density in the coverage area and the wireless environment are also different, it is difficult for a uniform bias value to be suitable for all low power nodes. For some low-power nodes, the uniformly set bias value may be too low, resulting in that the low-power node serves few users and does not fully utilize the resources of the low-power node; for other low power nodes, the uniformly set bias value may be too high, resulting in too many users selecting to access the cell covered by the low power node, and since the power of the actually received service signal of these users is lower than the received power of the interference signal from the conventional base station, the users may be greatly interfered, resulting in degraded communication quality.

Disclosure of Invention

In view of this, embodiments of the present invention provide a method for adjusting a cell coverage, a base station, and a low power node, which can adjust a coverage of the low power node more flexibly.

The adjusting process of the method for adjusting the cell coverage in the communication system of the embodiment of the invention mainly comprises the following steps:

the method comprises the steps that first equipment acquires first communication performance parameters of one or more users in users served by the first equipment, wherein the communication quality of the one or more users is lower than that of other users served by the first equipment;

the first device receives second communication performance parameters of one or more users of users served by the second device, wherein the second communication performance parameters are sent by the second device, the communication quality of the one or more users is poorer than that of other users served by the second device, the first device is one of a conventional base station and a low-power node, and the second device is the other one of the conventional base station and the low-power node;

obtaining a first coverage adjustment threshold and a second coverage adjustment threshold by using the communication performance parameters of the conventional base station in the first communication performance parameters and the second communication performance parameters, wherein the first coverage adjustment threshold is smaller than the second coverage adjustment threshold;

comparing the communication performance parameter of the low power node in the first communication performance parameter and the second communication performance parameter with the first coverage adjustment threshold and the second coverage adjustment threshold, respectively;

when the communication performance parameter of the low-power node is smaller than a first coverage adjustment threshold value, determining that the adjustment mode is to reduce an amplitude value on the basis of the bias value in the current CRE scheme of the low-power node; or when the communication performance parameter of the low-power node is larger than a second coverage adjustment threshold, determining that the adjustment mode is to increase an amplitude value on the basis of the bias value in the current CRE scheme of the low-power node; or when the communication performance parameter of the low-power node is greater than or equal to a first coverage adjustment threshold and less than or equal to a second coverage adjustment threshold, determining that the coverage of the low-power node does not need to be adjusted;

and the first equipment informs the second equipment of the adjustment mode.

The base station of the embodiment of the invention mainly comprises:

a parameter obtaining module, configured to obtain first communication performance parameters of one or more users of users served by a base station, where communication quality of the one or more users is lower than that of other users served by the base station; receiving second communication performance parameters of one or more users served by a low-power node, wherein the communication quality of the one or more users is poorer than that of other users served by the low-power node;

the judging module is used for obtaining a first coverage adjusting threshold and a second coverage adjusting threshold by utilizing the first communication performance parameter, wherein the first coverage adjusting threshold is smaller than the second coverage adjusting threshold; comparing a second communication performance parameter to the first coverage adjustment threshold and the second coverage adjustment threshold, respectively;

the coverage adjustment module is used for determining that the adjustment mode is an amplitude value reduction on the basis of the bias value in the current CRE scheme of the low-power node when the second communication performance parameter is smaller than the first coverage adjustment threshold; or when the second communication performance parameter is larger than the second coverage adjustment threshold, determining that the adjustment mode is to increase an amplitude value on the basis of the bias value in the current CRE scheme of the low-power node; or when the second communication performance parameter is greater than or equal to the first coverage adjustment threshold and less than or equal to the second coverage adjustment threshold, determining that the coverage area of the low-power node does not need to be adjusted; providing the adjustment to the low power node.

The low power node of the embodiment of the invention mainly comprises:

a parameter obtaining module, configured to receive first communication performance parameters of one or more users of users served by a conventional base station, where communication quality of the one or more users is lower than that of other users served by the conventional base station; acquiring second communication performance parameters of one or more users in users served by the low-power node, wherein the communication quality of the one or more users is lower than that of other users served by the low-power node;

the coverage adjustment module is used for determining that the adjustment mode is an amplitude value reduction on the basis of the bias value in the current CRE scheme of the low-power node when the second communication performance parameter is smaller than the first coverage adjustment threshold; or when the second communication performance parameter is larger than the second coverage adjustment threshold, determining that the adjustment mode is to add an amplitude value on the basis of the bias value in the current CRE scheme of the low-power node; or when the second communication performance parameter is greater than or equal to the first coverage adjustment threshold and less than or equal to the second coverage adjustment threshold, it may be determined that the coverage area of the low-power node does not need to be adjusted; providing the adjustment means to the conventional base station; and adjusting the current bias value of the low-power node according to the adjusting instruction of the conventional base station.

It can be seen from the foregoing technical solutions that the method, base station, and low power node provided in the embodiments of the present invention are applicable to heterogeneous networks of various wireless communication systems, and can adaptively adjust the coverage area of the low power node according to user communication performance parameters served by a conventional base station and the low power node in a current system, thereby improving the utilization rate of system resources and the service quality.

Drawings

Fig. 1 is a schematic diagram of an ABS mechanism in the prior art.

Fig. 2 is a schematic diagram illustrating a cell coverage configuration process in the prior art.

Fig. 3 is a schematic structural diagram of a base station according to an embodiment of the present invention.

Fig. 4 is a schematic diagram of state transition for cell coverage adjustment according to an embodiment of the present invention.

Fig. 5 is a schematic diagram illustrating a bias value adjustment process according to an embodiment of the present invention.

Fig. 6 is a flowchart of a method for adjusting a cell coverage according to an embodiment of the present invention.

Fig. 7 is a flowchart of a method for adjusting a cell coverage according to an embodiment of the present invention.

Fig. 8 is a schematic structural diagram of a wireless communication system according to an embodiment of the present invention.

Fig. 9 is a schematic structural diagram of a low power node according to an embodiment of the present invention.

Fig. 10 is a schematic structural diagram of a wireless communication system according to an embodiment of the present invention.

11a, 11b, 12a, 12b are graphs comparing simulation results of the present invention and static bias configuration method.

Fig. 13 is a diagram comparing the ratio of the number of users served by the low power node to the total number of users in the prior static configuration bias scheme when the bias initial value in the scheme of the embodiment of the present invention is respectively 12dB and 16 dB.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the embodiments of the present invention are described in further detail below with reference to the accompanying drawings.

The embodiment of the invention provides that the coverage range of the low-power node is adjusted according to the actual communication performance of users respectively served by the conventional base station and the low-power node, so that the system performance is improved.

The method of the embodiment of the invention mainly comprises the following steps: acquiring a first communication performance parameter of a user served by a conventional base station and a second communication performance parameter of a user served by a low-power node; obtaining one or more coverage adjustment thresholds using the first communication performance parameter; comparing a second communication performance parameter to the coverage adjustment threshold; if the second communication performance parameter is smaller than one of the coverage adjustment threshold values, reducing the coverage of the low-power node on the basis of the current coverage of the low-power node; or if the second communication performance parameter is larger than one of the coverage adjustment thresholds, increasing the coverage of the low-power node on the basis of the current coverage of the low-power node.

The above-described method may utilize one or more coverage adjustment thresholds. In some embodiments, a threshold may be used as a criterion for increasing the coverage of the low power node, or as a criterion for decreasing the coverage of the low power node, and may also be used as a criterion for increasing and decreasing the coverage, i.e. two sides falling on the threshold indicate that the coverage needs to be decreased or increased, respectively. In other embodiments, two or more thresholds are used as the basis for determining to increase or decrease the coverage area, and to implement other functions. These embodiments will be described in detail later.

The scheme of the present invention is described below with respect to an embodiment employing multiple coverage adjustment thresholds. The scheme of using a coverage adjustment threshold can be obtained by simplifying the following embodiments, and thus, the description is omitted.

The adjusting process of the method for adjusting the cell coverage area of the embodiment mainly comprises the following steps:

the first device receives second communication performance parameters of one or more users served by the second device, wherein the second communication performance parameters are sent by the second device, and the communication quality of the one or more users is poorer than that of other users served by the second device;

obtaining a first coverage adjustment threshold and a second coverage adjustment threshold by using the first communication performance parameter, wherein the first coverage adjustment threshold is not larger than the second coverage adjustment threshold;

comparing a second communication performance parameter to the first coverage adjustment threshold and the second coverage adjustment threshold, respectively;

when the second communication performance parameter is smaller than the first coverage adjustment threshold, determining that the adjustment mode is to reduce an amplitude value on the basis of an offset bias value in the current cell coverage extension CRE scheme of the low-power node; and/or when the second communication performance parameter is larger than a second coverage adjustment threshold, determining that the adjustment mode is to add an amplitude value on the basis of an offset bias value in the current cell coverage extension CRE scheme of the low-power node;

and the first equipment informs the second equipment of the adjustment mode.

The one or more users may select one or more users whose communication quality parameter values are lower than a preset threshold value by sorting the communication quality parameter values of all users served by the first device or the second device, or select a preset number of users in sequence from poor communication quality to good communication quality by sorting the communication quality parameter values in sequence from low to high. For example, when the communication quality parameter adopts a data rate, one or more users may be selected in sequence from a low data rate to a high data rate, or one or more users with a data rate lower than a preset threshold may be selected, and so on. When the communication Quality parameter adopts parameters such as throughput, signal-to-noise ratio, and Channel Quality Indicator (CQI), the selection method is similar, and details are not repeated here.

The above process may be performed by a conventional base station, by a low power node, or by other devices or nodes in the network. For example, the first device may be one of a regular base station and a low power node, and the second device may be the other of the regular base station and the low power node. The low power node is located within a coverage area of the regular base station.

Wherein the first coverage adjustment threshold is not greater than the second coverage adjustment threshold. If the first coverage adjustment threshold is less than the second coverage adjustment threshold, it may be determined that the coverage of the low power node does not need to be adjusted when the second communication performance parameter falls between the first coverage adjustment threshold and the second coverage adjustment threshold.

It should be noted that the terms "first", "second", and the like herein are used for clarity and convenience of description, and do not mean that they are substantially different in meaning. For example, the first communication performance parameter and the second communication performance parameter are both communication performance parameters of the user, and the "first" and the "second" are used only to distinguish the sources, and the meaning of the parameters themselves is the same.

The order of the above steps may be changed as required, and the execution order of the above parameter obtaining step and the parameter receiving step may be interchanged.

Therefore, the method can be used for heterogeneous networks of various wireless communication systems, such as heterogeneous networks of an LTE-A (Long term evolution-Advanced) system, and can adaptively adjust the coverage area of the low-power node according to the communication performance parameters of users served by the conventional base station and the low-power node in the current system, so that the utilization rate of system resources and the service quality are improved.

The above process may be performed by a conventional base station, by a low power node, or by other devices or nodes in the network. In the following embodiment, the above process is performed by a conventional base station (hereinafter referred to as a base station). Fig. 3 is a schematic structural diagram of the base station according to the embodiment. As shown in fig. 3, the base station mainly includes a parameter obtaining module 302, a determining module 303, and a coverage adjusting module 304.

The parameter obtaining module 302 is mainly configured to obtain a first communication performance parameter of a user served by the base station, and obtain a second communication performance parameter of a user served by a low power node within a coverage area of the base station.

The communication performance parameter may be measured by the base station or the low power node, or may be measured and reported by the user. The communication performance parameter may be an uplink and/or downlink communication Quality measurement such as a data rate, a throughput, a signal-to-noise ratio, a Communication Quality Indicator (CQI), and the like. The communication performance parameter may also be an original communication quality measurement value, or may also be obtained by processing the communication quality measurement value, for example, an average value over time, an average value of one or more users, a minimum value of time average values of multiple users, and the like.

The communication performance parameter may be a performance parameter of all users in the coverage area of the base station or the low power node, or may be a communication performance parameter of a part of users selected according to a predetermined policy, for example, a communication performance parameter of one or more users with poor communication quality among the users served in the coverage area, that is, the communication quality of the selected one or more users is worse than that of other users served by the base station or the low power node.

The parameter obtaining module 302 may obtain the first communication performance parameter of the user served by the base station locally, or may receive the first communication performance parameter reported by the user; the second communication performance parameters of the user sent by the low-power node within the coverage of the base station can be received, or all the performance parameters reported by the low-power node are processed to obtain the second communication performance parameters.

The low power node may send the communication performance parameters of the user obtained by the low power node to the base station periodically or according to the indication of the base station. The base station and the low-power node can use a wireless channel for information interaction and can also use a wired channel for information interaction. The manner of obtaining the second communication performance parameter by the low power node is similar to that of the base station, and is not described herein again.

The determining module 303 is mainly configured to obtain one or more coverage adjustment thresholds according to the first communication performance parameter, compare the second communication performance parameter with the coverage adjustment threshold, and provide the comparison result to the coverage adjusting module 304. For example, a first threshold and a second threshold may be obtained by using a first communication performance parameter, the second communication performance parameter may be compared with the first threshold and the second threshold, respectively, and the comparison result may be provided to the coverage adjustment module 304.

The determining module 303 may obtain the first threshold and the second threshold by using the first communication performance parameter, by using a predetermined algorithm or strategy, such as averaging, weighting, calculating by substituting a predetermined formula, and the like. The first threshold is not greater than the second threshold.

A coverage adjustment module 304, configured to notify the low-power node to narrow the coverage based on its current coverage when the second communication performance parameter is smaller than one of the coverage adjustment thresholds, for example, the first threshold; and/or, when the second communication performance parameter is greater than one of the coverage adjustment thresholds, e.g., the second threshold, notifying the low power node to increase coverage based on its current coverage.

The coverage adjustment module 304 determines an adjustment mode and an adjustment amplitude according to the comparison result of the judgment module 303, and transmits the adjustment mode and the adjustment amplitude to the low-power node. The adjustment magnitude may be an adjustment magnitude to the offset bias value in the CRE scheme. The base station may notify the low power node of the adjustment range of the bias value, or may notify the low power node of the adjusted bias value. In practice, various suitable methods can be adopted according to the needs, and the method is not limited in the text. The adjustment range may be calculated using a predetermined algorithm or selected from several alternative values using a predetermined policy, based on one or more of the first and second communication performance parameters, a ratio of the number of users of the base station to the low power node, a resource utilization rate of the low power node, and a channel variation condition.

For example, the base station may use one bit to indicate that the adjustment mode is expansion or reduction, and use one value to indicate the adjustment amplitude or the adjusted bias value; or a fixed adjustment amplitude can be agreed or configured in advance, and the base station only informs the low-power node whether the adjustment mode is expanding or shrinking.

The base station may also include other modules such as a processor CPU, memory, radio transceiver module, antenna, protocol processing module, internal bus, etc.

The CPU of the processor mainly controls and coordinates the work of each functional module; the memory is mainly used for storing various information; the wireless receiving and transmitting module and the antenna are used for receiving, transmitting and processing wireless signals; the internal bus is used for connecting each module to realize information exchange among the modules, and can be realized by one bus for connecting each module or by connecting lines among a plurality of modules. The functions of these modules are similar to those of the existing modules, and are not described in detail here.

It should be noted that the functions performed by the modules 302 and 304 are mainly initiated or dominated by these modules, and may actually need to be implemented by other modules, and may also involve cooperation among multiple modules, such as processing functions of a processor CPU, information reading from a memory, data transmission by using an internal bus, and the like, and for brevity, these functions are described as being performed by the modules 302 and 304.

In addition, in the description of the embodiments of the present invention, not all steps and modules are necessary, and some steps or modules may be omitted as necessary. The division of the modules is the division of logical functions for the convenience of description, and it is not necessary to construct devices strictly in the described division manner when implementing the division. For example, the functions of one module may be implemented by a plurality of different modules, or the functions of a plurality of modules may be combined and implemented by the same module, as necessary. These modules may be distributed among multiple physical entities or may be implemented by the same physical entity. The above-described modules are not exclusive, and the above-described apparatus may also include other modules, and for brevity of description, only the steps and modules related to the implementation of each embodiment are mentioned, and some processes and functional modules that are the same as those in the prior art are not described in detail again.

The base station can be used for heterogeneous networks of various wireless communication systems, such as heterogeneous networks of an LTE-A (Long term evolution-Advanced) system, and can adaptively adjust the coverage area of the low-power node according to communication performance parameters of users served by the base station and the low-power node, so that the utilization rate of system resources and the service quality are improved.

For example, in the base station of one embodiment,

the parameter obtaining module 302 may obtain first communication performance parameters of one or more users of users served by the base station, where communication quality of the one or more users is lower than that of other users served by the base station; receiving second communication performance parameters of one or more users served by a low-power node, wherein the communication quality of the one or more users is poorer than that of other users served by the low-power node;

the determining module 303 may obtain a first coverage adjustment threshold and a second coverage adjustment threshold by using the first communication performance parameter, where the first coverage adjustment threshold is not greater than the second coverage adjustment threshold; comparing a second communication performance parameter to the first coverage adjustment threshold and the second coverage adjustment threshold, respectively;

the coverage adjustment module 304 may determine, when the second communication performance parameter is smaller than the first coverage adjustment threshold, that the adjustment manner is to decrease by an amplitude value on the basis of the offset bias value in the current cell coverage extension CRE scheme of the low power node; or when the second communication performance parameter is larger than the second coverage adjustment threshold, determining that the adjustment mode is to increase an amplitude value on the basis of the offset bias value in the current cell coverage extension CRE scheme of the low-power node; providing the adjustment to the low power node.

It should be noted that the above has only been described with one base station and one low power node as examples. There may be many conventional base stations in the heterogeneous network, each of which may have a plurality of low power nodes of the same type or different types within its coverage area, and each or some of the base stations may perform the above-described procedure for some or all of the low power nodes within its coverage area, respectively, to adjust the coverage area of the low power nodes.

After the base station notifies the low power node of adjusting the coverage range, the base station and the low power node may respectively configure the updated bias value of the low power node to the respective served users. And the user adds the updated offset bias value to the receiving power of the original low-power node signal to perform cell selection. Therefore, the self-adaptive adjustment of the coverage range of each low-power node is realized, the selection of the user to the access cell is more reasonable, the utilization rate of system resources is improved, and the rate guarantee is provided for the edge user terminal.

In an embodiment of the present invention, the above adjustment process may be performed at intervals in order to reduce the load of the base station and reduce the signaling overhead in the network. For example, when the base station determines that the coverage area of the low power node does not need to be adjusted continuously for a preset number of times or for a certain time period t1, the adjustment is stopped. After the system has been operating for a certain time period t2 according to the current settings, the adjustment process is started again.

It is also possible to set a time duration T, also called an adjustment period, for each adjustment process, that is, every time duration T, the base station counts the communication performance parameters within the time duration, and adjusts the coverage area of the low power node once according to the above process.

One or more of the above T1, T2, T are derived from one or more of a load change situation of the cell, a number of users in the cell, a ratio of a number of users of the conventional base station and the low power node, and a channel change situation.

According to one embodiment, a base station may set a state machine for one or more low power nodes, including two states: dynamic (Active) and Static (Static). If the state machine is in Active state, it indicates that the bias value needs to be adjusted. The adjustment period is denoted by T, which may be a selected length of time, for example, several tens or hundreds of subframes (subframes) in duration, or longer. As long as it is ensured that the communication performance information obtained in the adjustment period can objectively and truly reflect the communication performance actually obtained by the user. If the state machine is in the Static state, the bias value, i.e. the coverage area of the low power node, remains unchanged, thereby saving the signaling overhead generated by the adjustment process.

Fig. 4 is a diagram illustrating state transition for cell coverage adjustment according to an embodiment of the present invention. In this embodiment, a macro base station is taken as an example of a conventional base station, a pico base station is taken as an example of a low-power node, and the macro base station uses the same state machine for all pico base stations in its coverage. It should be noted that the technical solutions described below can be extended to be applied to various conventional base stations and low power nodes, and are not limited to macro base stations and pico base stations.

And in an initialization stage, the system is in an Active state, and the macro base station adjusts the bias value of each picocell according to the user access information of the macro base station and the low-power node and the data rate information obtained by the user. Wherein the user access information may include: the number of access users of the macro base station, the number of access users of the low-power node and the like. Fig. 5 is a diagram illustrating a bias value adjustment process. As shown in fig. 5, after each adjustment period, the macrocell base station calculates the number of picocells whose bias values need to be adjusted, and if there is no picocell whose bias values need to be adjusted and s adjustment periods continuously occur in this case, it is determined that all bias values are currently set reasonably, which can meet the overall performance requirement, and therefore enters a Static state. And all the picocells keep the current bias values unchanged, and after the picocells continue to carry out m adjustment periods, the picocells return to the Active state again, and readjust the bias values to adapt to the change of the current environment. The parameters s and m are integers greater than 0, and the values can be determined according to experience or system strategies. The value of m can be determined according to the change rule of parameters such as user distribution, communication environment and the like.

In other embodiments, the base station may also set a state machine for each low power node, and the process of state transition is similar to the above process, except that the base station only needs to pay attention to whether the picocell is adjusted, and enters the Static state if the adjustment is not needed for s adjustment periods continuously.

In the following, a macro base station is taken as an example, and it is assumed that there are M pico cells within the coverage area. The cell coverage adjustment procedure of an embodiment is described in detail below with reference to fig. 6, where the adjustment period T is used as a basic time unit in this example.

In step 601, the macro base station assigns initial bias values to all pico base stations, as shown in formula (2). Initial bias value bias_initialIt may be set according to conventional methods or may be slightly larger than the bias value required by conventional methods to allow more users to access the picocell.

bias₀(i)＝bias_initial,0≤i＜M (2)

Wherein i denotes the ith pico base station, bias₀(i) Indicating the bias value at the 0 th adjustment of the ith pico base station.

Step 602, at the end of the (n + 1) th adjustment period, the ith pico base station sends the communication performance parameter of the user with the worst communication performance obtained in the period T, among the users served by the ith pico base station, to the macro base station. Wherein the communication performance parameter may be an average data rate of a user with the worst communication performanceOr the average value of the channel quality indication information such as CQI of the user with the worst downlink communication performance at each scheduled time within the period T, and the like, may select appropriate parameters as needed, and the following may be performed to select appropriate parametersFor illustration purposes.

Step 603, the macro base station determines the bias value adjustment mode of the ith pico base station and sends the adjustment instruction to the pico base station.

For example, the macro base station may make the determination according to equation (3).

In the formula (3), bias_n(i) The bias value of the ith pico base station after the nth adjustment is represented; bias_min,bias_maxRespectively representing the lower limit and the upper limit of a value range of a preset pico base station bias value in the system; the adjustment range of Δ is a preset bias value, and may be a fixed step value, or may be calculated by using a predetermined algorithm according to one or more of, for example, the first communication performance parameter, the second communication performance parameter, the number of users of the conventional base station and the low power node, the resource utilization rate of the low power node, and the channel variation condition, and may be, for example, 0.2 dB;α is a weighting coefficient, which represents a predetermined threshold value of the ratio of the user communication performance of the low power node and the user communication performance of the conventional base station, for representing the acceptable difference between the worst user performance of the low power node and the conventional base station, and can be set according to the requirement, for example, 10 can be taken.

Corresponding to the foregoing embodiment, in formula (3),as the first communication performance parameter,is a second communication performance parameter; in this example toIs a first threshold value of α DEG R^M _minIs the second threshold. When the macro base station judges that the second communication performance parameter is smaller than the first threshold value, the macro base station indicates that users with communication performance worse than that of the user with the worst performance of the macro base station service exist in the users served by the pico base station, and the pico base station is informed to reduce the bias value by a delta, so that the coverage range of the pico base station is reduced, and the user with the worst performance served by the pico base station can be selectively accessed to the macro base station or other pico base stations through a cell; when the macro base station judges that the second communication performance parameter is larger than or equal to the second threshold value, the communication performance of the user served by the pico base station is better than that of the user served by the macro base station, and the pico base station also has the capability of serving more users, so that the pico base station is informed to increase the bias value by one delta, the coverage range of the pico base station is expanded, and the pico base station can serve more users.

The above formula (3) is only a specific example, and other determination criteria may be used in practice, or a predetermined algorithm may be used to calculate an appropriate adjustment amplitude value for the pico-base station instead of using a fixed step value. The implementation here can be very flexible and is not limited here.

The adjustment instruction is an indication signal indicating that the bias value increases or decreases, and includes an adjustment mode (i.e., increase or decrease), or an adjustment mode and an adjustment amplitude, or an adjusted bias value.

After the macro base station determines the bias adjustment behavior of each pico base station, the macro user served by the macro base station is measured and configured according to the bias value adjusted by each base station, namely the adjusted bias value of the pico base station is provided for the user. And similarly, the pico base station performs measurement configuration on the served pico base station users according to the adjusted bias value. The subsequent process is the same as the conventional method and is not described in detail herein.

Step 604, if the macro base station finds that all M picocells within the coverage area of the macro base station do not need to adjust the bias values, and the judgment conclusion that the adjustment is not needed is kept unchanged for s adjustment periods, the state machine is enabled to enter the Static state.

Step 605, in the Static state, the macro base station and the pico base station do not need to exchange the information required for adjusting the bias, and the bias values of all users and all pico cells are not changed, and the Static state lasts for m adjustment periods T. After m adjustment periods, the system may have changed some traffic and communication environment, so it returns to step 602 again to make the state machine enter Active state and start a new adjustment period.

Therefore, the method can be used for the LTE-A heterogeneous network, and the bias values of all the low-power nodes can be periodically, adaptively and distributively adjusted, so that the user can select the access cell more reasonably, the utilization rate of system resources is improved, and rate guarantee is provided for the edge user terminal. In the course of adjusting the bias value, a certain static time interval is set, thereby reducing the signaling overhead of the system.

To further reduce the ping-pong effect of frequent handover of users due to periodic adjustment of coverage, one embodiment of the present invention addsFrozen flag f_incThis embodiment is described below with reference to fig. 6. This embodiment is still illustrated using one macro base station and multiple pico base stations within its coverage area.

Fig. 7 is a flowchart of a method for adjusting cell coverage according to an embodiment of the present invention. As shown in fig. 6, the flow may include the following steps.

In step 701, during initialization, the macro base station allocates an initial bias value to all picocells. The bias values of the pico cells may be the same or different. All users perform cell selection/reselection according to formula (1).

Step 702, at the end of the (n + 1) th adjustment period T, the ith pico base station obtains the worst communication performance parameters, such as average data rate, for the users served by the ith pico base station in the T periodOr the worst CQI mean value is sent to the macro base station, and the macro base station also records the worst average data rate obtained by the user served by the macro base station in the periodOr worst CQI mean.

If the pico-base station has no user access, the base station may be informed that the number of users is 0, or the feedback communication performance parameter(s) ((s))Or CQI mean) is set to a preset value, such as 0, indicating that no user is currently accessing.

Step 703, for each pico base station, if the macro base station finds that the number of access users of the pico base station is 0, it may perform a coarse tuning process of the bias value, and send an increase signal to the pico cell to increase its bias by Δ₁In anticipation of user access in the next cycle. After the (n + 1) th adjustment period, the bias value bias of the ith pico base station_n+1(i) As shown in formula (4)Shown in the figure.

bias_n+1(i)＝Median[bias_min,bias_max,bias_n(i)+Δ₁](4)

Wherein [ bias_min,bias_max]The range of bias value adjustment can be, for example, [0dB,20dB ]]；Δ₁The step size for coarse adjustment of bias value can be set as desired or calculated by a predetermined algorithm, for example, 0.6dB can be taken.

Step 704, for each pico base station, the macro base station calculates the freezing mark f of the pico base station according to formula (5)_incValue f_incThe value may be true or false.

Wherein f is_inc(i) Indicating the frozen identity of the ith pico base station, which may have an initial value of false, β indicating a predetermined threshold value for the ratio of user communication performance of the low power node to that of the conventional base station, a tolerable gap parameter representing the worst user performance of the pico cell to the macro cell, which may be, for example, 5_inc(i) Set to true; if not, f is calculated_inc(i) Is false, but if f_inc(i) If the current value of is true, f is not changed_inc(i) The value of (c).

After receiving the information sent by the pico base station, the macro base station calculates the freezing mark f of the pico base station with the service user in the coverage area according to the formula (5)_incThis value will determine whether the bias value of the pico base station can be increased in the following adjustment step (i.e., step 705).

Step 705, the macro base station implements the bias fine tuning process and sends the determined tuning instruction to the pico base station. If the number of the ith picocell access users is not 0, the bias value is judged and fine adjustment is carried out, and the bias adjusted increasing/decreasing identification is sent to the picocell base station.

According to an embodiment of the present invention, the determination in this step can be performed according to formula (6).

Wherein,indicating f obtained in step 704_incA value of false; delta₂The step size for fine tuning the bias value may be empirically set, e.g., 0.2dB, and α is a fine tuning decision parameter, another predetermined threshold value representing the ratio of the user communication performance of the low power node and the conventional base station, which represents an acceptable gap for the worst user performance between the picocell and the macrocell, which may be empirically set.

As can be seen from equation (6), as long as f_inc(i) Is set to true because the condition of equation (5) is satisfied, then the bias value of the pico base station is not allowed to increase any more in this entire round of adjustment. That is, the communication performance parameter of the pico-base station must be larger than the judgment threshold value of each time so far in the adjustment roundIt is possible to increase its protection range. Therefore, the mechanism for increasing the coverage area of the pico base station is more conservative and strict, and the ping-pong effect can be further reduced.

After all the picocell base stations receive the bias adjustment information sent by the macrocell base station, measurement configuration is carried out on the user again according to requirements, and the bias information is modified. All users will perform cell reselection according to the new configuration requirements.

And then proceed to the next adjustment period. That is, the adjustment of bias is repeated from step 702. Until the end of a certain adjustment period (fig. 5 embodiment)End of 20T period) if the macro base station finds in step 706 that all picocells do not need to adjust bias values and this state lasts s adjustment periods (s is 3 in the embodiment of fig. 5), then it enters the Static state in step 707 and resets f_incThe value is obtained.

In m adjustment periods (m is 300 in the embodiment of fig. 5) after Static, the macro base station does not change the bias values of all users and pico base stations, and the information interaction required in the above steps is not required between the macro base station and pico base stations. Returning to step 702 again after the Static time is over, the bias value adjustment is continued.

The method can decide to execute the adjustment of the bias value in the CRE scheme according to the access information and the communication performance information of users served by the conventional base station and the low-power node in the current system, and the coverage area of the low-power node without the access user is enlarged to a larger extent; for the low-power node needing to be adjusted, the adjustment is more conservative, and the coverage area of the node can be enlarged only when the communication performance of the low-power node service user is kept at a higher level all the time in the adjustment cycle, so that the ping-pong effect is avoided to a greater extent.

The flows described in fig. 6 and fig. 7 above may be implemented by the base station shown in fig. 3, for example, step 603 may be performed by the determining module 303 and the coverage adjusting module 304, and steps 604 and 605 may be performed by the coverage adjusting module 304; steps 703 to 707 may be performed by the coverage adjustment module 304.

It should be noted that in the flow described in fig. 6 and 7, not all steps are necessary, and some steps may be omitted as needed. The execution sequence of the steps is not fixed, and can be adjusted according to the needs. The processes need not include only the described steps, but may include other steps. For simplicity of description, only the steps related to implementation of the embodiments are mentioned above, and some processes identical to those in the prior art are omitted.

Fig. 8 is a schematic structural diagram of a wireless communication system according to an embodiment of the present invention. It can be seen that the conventional base station and the low power node respectively receive the communication quality measurement reports of the respective service users, respectively obtain the communication performance parameters of the respective users, summarize to the conventional base station, compare the related parameters by the conventional base station, determine the adjustment mode of the low power node, and instruct the low power node to adjust.

It should be noted that, in other embodiments of the present invention, the direction of the signaling interaction in steps 602, 603, and 702, 705 may be changed, that is, the macro base station sends the worst communication performance parameters of the user served by the macro base station, such as the worst average data rate, the worst average CQI value, and the like, to the pico base station, each pico base station calculates the bias adjustment manner and sends the adjustment manner to the macro base station, and if the macro base station agrees to perform adjustment on the pico base station, the macro base station sends the adjustment instruction to the pico base station. This can be obtained by a simple transformation of the above steps and will not be described in detail here.

Fig. 9 is a schematic structural diagram of a low power node according to an embodiment of the present invention. As shown in fig. 9, the low power node mainly includes a parameter obtaining module 902, a determining module 903, and a coverage adjusting module 904.

A parameter obtaining module 902, configured to obtain a third communication performance parameter of a user of a local service, and obtain a fourth communication performance parameter of a user of a conventional base station service to which a local cell belongs;

a determining module 903, configured to obtain one or more coverage adjustment thresholds according to the fourth communication performance parameter, compare the second communication performance parameter with the coverage adjustment threshold, and provide a comparison result to the coverage adjusting module 904; for example, the first communication performance parameter may be used to obtain a third threshold and a fourth threshold, the third communication performance parameter is compared with the third threshold and the fourth threshold, and the comparison result is provided to the coverage adjusting module 904;

a coverage adjustment module 904, configured to determine, when the third communication performance parameter is smaller than one of the coverage adjustment thresholds, for example, a third threshold, that the adjustment mode is to narrow the coverage based on the current coverage; and/or when the third communication performance parameter is greater than one of the coverage adjustment threshold values, for example, the fourth threshold value, determining the adjustment mode as expanding the coverage range on the basis of the current coverage range, and informing the conventional base station of the determined adjustment mode; and after receiving the adjusting instruction of the conventional base station, executing the adjustment of the coverage of the node according to the adjusting mode.

Similarly, the low power node may further include other modules, such as a processor CPU, a memory, a wireless transceiver module, an antenna, an internal bus, and the like, which are not described herein again.

The functions performed by the above-mentioned modules 902 and 904 are mainly initiated or dominated by these modules, and may actually need to be implemented by other modules, and may also involve cooperation among a plurality of modules, for example, processing functions of a processor CPU, information reading from a memory, data transmission by using an internal bus, and the like, and for brevity, these functions are described as being performed by the modules 902 and 904.

The parameter obtaining module 902 may locally obtain a third communication performance parameter of the user served by the low power node, or may receive the third communication performance parameter reported by the user; and receiving the fourth communication performance parameter of the user of the cell, which is sent by the conventional base station to which the cell belongs. Here, the third and fourth communication performance parameters are similar to the first and second communication performance parameters, and are not described again.

The determining module 903 may obtain the third threshold and the fourth threshold by using the fourth communication performance parameter, by using a predetermined algorithm or strategy, such as averaging, weighting, calculating by substituting into a predetermined formula, and the like. For example, the threshold value may be a multiple of the communication performance parameter of the conventional base station user, as represented in equation (3). The third threshold is not greater than the fourth threshold.

The coverage adjusting module 904 determines an adjusting manner and an adjusting amplitude according to the comparison result of the judging module 903, and notifies the conventional base station. The conventional base station is responsible for managing the low-power nodes in the coverage area, the low-power nodes need to inform the conventional base station of the adjustment mode, the conventional base station sends formal adjustment instructions after allowing, and the low-power nodes perform adjustment according to the instructions. The conventional base station can use a bit to indicate that the adjustment mode is expansion or reduction, and use a value to indicate the adjustment amplitude or the adjusted bias value; or a fixed adjustment amplitude can be appointed or configured in advance, and the base station only informs the low-power node of whether the adjustment mode is expansion or reduction; in this embodiment, the conventional base station may also use only one bit to indicate whether the low power node is allowed to adjust according to the transmitted adjustment manner.

For example, in a low power node of an embodiment:

a parameter obtaining module 902 receives first communication performance parameters of one or more users of users served by a conventional base station, where the communication quality of the one or more users is worse than that of other users served by the conventional base station, and the first communication performance parameters are sent by the conventional base station; acquiring second communication performance parameters of one or more users in users served by the low-power node, wherein the communication quality of the one or more users is lower than that of other users served by the low-power node;

the determining module 903 obtains a first coverage adjustment threshold and a second coverage adjustment threshold by using the first communication performance parameter, where the first coverage adjustment threshold is not greater than the second coverage adjustment threshold; comparing a second communication performance parameter to the first coverage adjustment threshold and the second coverage adjustment threshold, respectively;

when the second communication performance parameter is smaller than the first coverage adjustment threshold, the coverage adjustment module 904 determines that the adjustment mode is to decrease an amplitude value on the basis of the offset bias value in the current cell coverage extension CRE scheme of the low-power node; or when the second communication performance parameter is larger than the second coverage adjustment threshold, determining that the adjustment mode is to add an amplitude value on the basis of the offset bias value in the current cell coverage extension CRE scheme of the low-power node; providing the adjustment means to the conventional base station; and adjusting the offset bias value in the current cell coverage expansion CRE scheme of the low-power node according to the adjustment instruction of the conventional base station.

As described above, the modules herein are merely based on the division of logical functions, and may be implemented by a plurality of modules or by the same module. The node may also have other modules, only those related to the present embodiment are mentioned here.

In this embodiment, the adjustment process mainly dominated by the low power node may be obtained by simple transformation according to the adjustment flows shown in fig. 6 and fig. 7, and details are not described here.

After the base station informs the low-power node of the manner of adjusting the coverage area of the low-power node, the low-power node can send the updated bias value to the user in a broadcast or unicast manner. And the user adds the updated offset bias value to the receiving power of the original low-power node signal to perform cell selection. Therefore, the self-adaptive adjustment of the coverage range of each low-power node is realized, the selection of the user to the access cell is more reasonable, the utilization rate of system resources is improved, and the rate guarantee is provided for the edge user terminal.

Fig. 10 is a schematic structural diagram of a wireless communication system according to an embodiment of the present invention. It can be seen that, the conventional base station and the low power node respectively receive the communication quality measurement reports of the respective service users, respectively obtain the communication performance parameters of the respective users, the conventional base station sends the communication performance parameters of the users to the low power node, the low power node compares the relevant parameters, determines the adjustment mode of the low power node, and notifies the conventional base station. The conventional base station sends a formal bias adjusting instruction to the low-power node according to the received bias adjusting mode sent by the low-power node, and the low-power node adjusts the bias value according to the adjusting instruction.

According to the technical scheme, the cell coverage range adjusting method provided by the invention can effectively utilize the wireless resources of the low-power nodes in the heterogeneous network to perform load balancing with the conventional base station, analyze the communication performance information obtained by the conventional base station and the users of the low-power nodes, increase or reduce the bias values of the low-power nodes, and achieve the purpose of adaptively adjusting the bias values of the low-power nodes. In addition, the technical scheme of each embodiment of the invention can be used together with other existing mechanisms, such as ABS and the like, and the performance of the system can be further improved on the basis of the existing mechanisms.

FIGS. 11a to 14 are graphs showing simulation results of an embodiment of the present invention for implementing offset adjustment.

11a, 11b, 12a, 12b are comparison of simulation results of the present invention and static bias configuration method. Fig. 11a and 12a show a comparison graph of throughput of 5% users (i.e., cell edge users), and fig. 11b and 12b show a comparison graph of total throughput of cells. In the simulations of fig. 11a and 11b, Full buffer traffic is used, ABS silence ratio is set to 1/4, and the initial bias value of the present invention is 12dB, α is 10, and β is 4. The simulations of fig. 12a and 12b also use Full buffer traffic with ABS silence ratio 1/4, α being 10 and β being 4, except that the initial bias value is 16 dB. On the horizontal axis in the figure, adaptive represents the scheme of adaptively adjusting the bias value of the present invention, and the other numbers represent that the existing statically configured bias scheme adopts the number as the bias value. It can be seen that when the initial bias value of the scheme of the present invention is 12dB, the data rate of 5% UE in the technical scheme of the present invention is 35.13% higher than that of the scheme with the best effect in the scheme using the static bias value, and the total throughput of the system is 0.45% higher; when the initial bias value of the scheme of the invention is 16dB, the data rate of 5 percent of UE in the technical scheme of the invention is 36.23 percent higher than the best scheme in the scheme adopting the static bias value, and the total throughput of the system is only 3.14 percent less than the best scheme in the static scheme.

Fig. 13 is a diagram comparing the ratio of the number of users served by the low power node to the total number of users in the prior static configuration bias scheme when the bias initial value in the scheme of the embodiment of the present invention is respectively 12dB and 16 dB. Therefore, by adopting the technical scheme of the invention, the resources of the low-power node are more fully utilized.

In summary, the above are only some examples of the present invention, and are not intended to limit the scope of the present invention. Any modification, equivalent replacement, improvement and the like made within the scope of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for adjusting cell coverage in a communication system, the adjusting comprising:

when the communication performance parameter of the low-power node is smaller than a first coverage adjustment threshold value, determining that the adjustment mode is to reduce an amplitude value on the basis of an offset bias value in the current cell coverage extension CRE scheme of the low-power node; or, when the communication performance parameter of the low-power node is greater than a second coverage adjustment threshold, determining that the adjustment manner is to add an amplitude value on the basis of an offset bias value in the current cell coverage extension CRE scheme of the low-power node; or when the communication performance parameter of the low-power node is greater than or equal to a first coverage adjustment threshold and less than or equal to a second coverage adjustment threshold, determining that the coverage of the low-power node does not need to be adjusted;

and the first equipment informs the second equipment of the adjustment mode.

2. The method of claim 1, wherein: the communication performance parameters of the one or more users are: an average data rate of the one or more users for the first time period or an average of the channel quality indication information for the one or more users at the times scheduled for the first time period.

3. The method of claim 1, further comprising:

when the number of the users served by the low-power node is zero, determining an adjustment mode to increase an amplitude value on the basis of an offset bias value in the current cell coverage extension CRE scheme of the low-power node;

re-executing the adjustment process after a first duration;

when the condition that the coverage area of the low-power node does not need to be adjusted lasts for a second time length, or when the condition that the coverage areas of all the low-power nodes in the coverage area of the conventional base station do not need to be adjusted lasts for the second time length or continuously occurs for a preset number of times, ending the adjusting process and keeping the coverage area of the low-power node unchanged;

restarting the adjustment process when a third duration passes after the adjustment process is finished;

wherein one or more of the first time duration, the second time duration and the third time duration is obtained according to one or more of a load change situation of a cell, the number of users in the cell, a ratio of the number of users of a conventional base station and a low-power node and a channel change situation.

4. The method of claim 3, further comprising:

setting a freezing mark with an initial value of false;

obtaining a third threshold according to the communication performance parameter of the conventional base station, wherein the third threshold is smaller than the second coverage adjustment threshold;

when the communication performance parameter of the low-power node is smaller than a third threshold value, setting the value of the frozen identifier to true;

when the communication performance parameter of the low-power node is larger than the second coverage adjustment threshold and the value of the frozen flag is true, keeping the coverage of the low-power node unchanged; when the communication performance parameter of the low-power node is greater than the second coverage adjustment threshold and the value of the frozen identifier is false, determining that the adjustment mode is to add an amplitude value on the basis of an offset bias value in the current cell coverage extension CRE scheme of the low-power node;

after the adjustment process is finished and before the adjustment process is restarted, setting the value of the freezing mark as an initial value;

wherein the third threshold is not less than the first coverage adjustment threshold and not greater than the second coverage adjustment threshold.

5. The method of any of claims 1-4, wherein the first device notifying the second device of the manner of adjustment comprises:

the conventional base station sends an adjusting instruction to the low-power node according to the determined adjusting mode; and/or

The low-power node provides the determined adjustment mode to the conventional base station; the conventional base station sends an adjusting instruction to the low-power node according to the received adjusting mode;

the adjusting instruction comprises an adjusting mode, or the adjusting mode and an adjusting amplitude, or an adjusted coverage range parameter; the adjustment mode is used for indicating the coverage area to be increased or decreased.

6. A base station, comprising:

the coverage adjustment module is used for determining that the adjustment mode is to reduce an amplitude value on the basis of an offset bias value in the current cell coverage extension CRE scheme of the low-power node when the second communication performance parameter is smaller than the first coverage adjustment threshold; or when the second communication performance parameter is greater than the second coverage adjustment threshold, determining that the adjustment mode is to add an amplitude value on the basis of the offset bias value in the current cell coverage extension CRE scheme of the low-power node; or when the second communication performance parameter is greater than or equal to the first coverage adjustment threshold and less than or equal to the second coverage adjustment threshold, determining that the coverage area of the low-power node does not need to be adjusted; providing the adjustment to the low power node.

7. The base station of claim 6, wherein the coverage adjustment module is further to:

when the number of users served by the low-power node is zero, determining an adjustment mode to increase an amplitude value on the basis of an offset bias value in a current cell coverage extension (CRE) scheme of the low-power node;

re-executing the adjustment process after a first duration;

when the coverage of the low-power node does not need to be adjusted for a second time, or when the coverage of all the low-power nodes within the coverage of the base station does not need to be adjusted for the second time or continuously occurs for a predetermined number of times, ending the adjustment process and keeping the coverage of the low-power node unchanged;

when the adjustment process is finished and a third time length passes, restarting the adjustment process, and re-determining the adjustment mode according to the comparison result provided by the judgment module;

wherein one or more of the first time duration, the second time duration and the third time duration is obtained according to one or more of a load change condition of a cell, the number of users in the cell, a ratio of the number of users of a base station and a low-power node and a channel change condition.

8. A low power node, comprising:

the coverage adjustment module is used for determining that the adjustment mode is to reduce an amplitude value on the basis of an offset bias value in the current cell coverage extension CRE scheme of the low-power node when the second communication performance parameter is smaller than the first coverage adjustment threshold; or when the second communication performance parameter is larger than the second coverage adjustment threshold, determining that the adjustment mode is to add an amplitude value on the basis of the offset bias value in the current cell coverage extension CRE scheme of the low-power node; or when the second communication performance parameter is greater than or equal to the first coverage adjustment threshold and less than or equal to the second coverage adjustment threshold, it may be determined that the coverage area of the low-power node does not need to be adjusted; providing the adjustment means to the conventional base station; and adjusting the offset bias value in the current cell coverage expansion CRE scheme of the low-power node according to the adjustment instruction of the conventional base station.

9. The low-power node of claim 8, wherein the coverage adjustment module is further to:

when the number of users served by the low-power node is zero, determining that the adjustment mode is to increase an amplitude value on the basis of an offset bias value in the current cell coverage extension CRE scheme of the low-power node;

re-executing the adjustment process after a first duration;

when the condition that the coverage area of the low-power node does not need to be adjusted lasts for a second time or occurs for a preset number of times continuously, ending the adjusting process and keeping the coverage area of the low-power node unchanged;