JP5031901B2 - Radio communication system, radio communication apparatus, and radio resource management method - Google Patents

Description

  The present invention relates to a radio communication system, and more particularly to a radio resource management technique in a radio communication system.

Recent cellular radio communication systems such as mobile phones are diverse, from information with relatively few bits such as voice and text mail, to information with many bits such as mail and video data of videophones with photos attached. It is required to transmit the information. In order to meet this demand, a cellular radio communication system uses a plurality of packet sizes and a plurality of modulation schemes corresponding to the amount of data to be transmitted (number of bits). In addition, some terminals in the system have a very good radio wave propagation environment because they exist in the vicinity of the base station or in a position where they can be seen. On the other hand, some terminals have a poor radio wave propagation environment because they exist behind buildings where radio waves from the base station are blocked or in places where interference power from other cells is large.
For this reason, in the system, radio resources are divided finely in time × frequency × space, radio resources allocated to the terminals are sequentially determined according to the radio wave propagation environment of each terminal, and the packet size used in each radio resource And the modulation method are combined appropriately. As a result, the frequency utilization efficiency of the entire system is improved. Functions such as radio resource allocation, distribution change, and resource release are collectively referred to as a radio resource management function.
The wireless communication network standardized by 3GPP (3rd Generation Partnership Project) has a three-layer configuration as shown in FIG. However, when shifting to the 3.9th generation, a node B (Node B: radio base station) and RNC (Radio Network controller: radio network controller), which have been separated separately, are integrated into one enhanced node. By accommodating it in B (hereinafter abbreviated as eNB), the architecture has been greatly changed to a two-layer configuration as shown in FIG.
Along with this architecture change, most of the radio resource management functions that were conventionally implemented in the RNC have been moved to the eNB (see 3GPP TR25.912 v7.2.0 (2007-06), Chapter 11). For example, functions such as Radio Bearer Control, Radio Admission Control, and Connection Mobility Control are implemented in the eNB. However, there are still problems to be investigated in implementation of ICIC (Inter-cell Interference Coordination) that needs to be adjusted between cells (eNBs).
Here, inter-cell interference and ICIC will be described with reference to FIG. In a system using OFDMA (Orthogonal Frequency Division Multiple Access) and having a frequency repetition rate of 1, the same frequency band is used for a certain cell and an adjacent cell. In the case illustrated in FIG. 2, a radio resource 205 used for communication between an eNB 202 of a certain cell 201 and a terminal A 204 in the vicinity of the boundary between the cell 201 and the adjacent cell 203, an eNB 206 of the adjacent cell 203, and a cell The radio resource 208 used for communication with the terminal B 207 inside 203 may overlap in time and frequency. In this case, since the terminal A 204 is in the vicinity of the boundary between the cell 201 and the cell 203, a radio wave for communication from the eNB 206 toward the terminal B 207 is received. Radio waves for communication directed toward these other terminals become noise (interference) with respect to the radio wave 205 that is originally desired to be received. In order to avoid such a phenomenon, devising how to allocate radio resources in cooperation between eNBs or the entire system is called ICIC (inter-cell interference control).
As a first specific example of ICIC, information such as the load status (congestion level) of the own cell and radio resources allocated to terminals in the vicinity of the cell boundary are exchanged between eNBs. It is conceivable to change the allocation limit for the scheduler, such as limiting transmission power in a specific radio resource block to a certain value or prohibiting allocation to a specific radio resource block (3GPP TR25.814 v7.1). 0.0 (2006-09) 7.1.2.6).
Periods for reconfiguring (setting, canceling, changing) restrictions are every few days (every few days between eNBs, only the contents of restrictions are exchanged), every few minutes (every tens of seconds to every minute between eNBs) Two types of detailed information necessary for determining whether or not to change the limit are exchanged).
Except for the above-described allocation restriction, the scheduler of each eNB controls the allocation of radio resources to terminals. Each eNB has, with respect to a plurality of terminals communicating within its own cell, presence / absence of data to be transmitted to the terminal in the scheduling interval; elapsed time since the resource was allocated to the terminal last time; Resource allocation is determined in consideration of conditions such as whether the terminal's QoS (Quality of Service) requirement is satisfied.
The scheduling target differs depending on the policy of each eNB, but basically the efficiency is improved when all radio resources are used without bias. Conversely, the more allocation restrictions imposed by ICIC described above, the higher the probability that the resource is not allocated to the resource to be allocated (good conditions), and the throughput decreases.
As a second specific example of ICIC, FFR (Fractional Frequency Reuse) proposed for the 3.5th generation is known as a method for coordinating radio resource allocation in cooperation with the entire system (international frequency). Publication WO / 2006/020032 pamphlet and Satoshi Konishi, Satoshi KONISHI, A Study on Fractional Frequency Reuse for OFDM Cellular System, A Study on the Fractional Information Electronica 7 Communication Society Conference Proceedings 1, PROCEEDINGS OF THE 2007 IEICE COMMUNICATI NS SOCIETY CONFERENCE, 2007.09.11, B-5-59, see p.381). The principle of FFR will be described with reference to FIG. In the RNC in the conventional network configuration described above, the terminal 303 near the cell boundary and the other terminal 304 (that is, near the eNB 302) are distinguished from the eNB 302 of a certain cell 301, and a certain frequency band B is set. The resource allocation is limited so that it is allocated to the terminal 303 near the cell boundary and another frequency band A is allocated to the other terminal 304 (in the center of the cell). For the eNB 306 of the adjacent cell 305, another frequency band C is assigned to the terminal 307 near the cell boundary, and the above-mentioned frequency band A is assigned to the other terminal 308 (inside the cell) Limit resource allocation.
In this way, the terminal in the center of the cell is assigned the same frequency band A in all the eNBs, and the frequency band assigned to the terminals in the vicinity of the cell boundary is allocated so as not to overlap between the cells. By limiting, it is possible to suppress an increase in a required frequency band (frequency resource subdivision) while performing ICIC.
As shown in FIG. 3, when FFR is performed on seven cells, the radio resources of each eNB may be divided into four in the frequency direction, but without performing FFR, in all cells, around the cell boundary. If different frequency bands are to be assigned to a terminal and other terminals, it is necessary to divide the radio resource into 14 in the frequency direction. On the other hand, if FFR is not performed and terminals located in the vicinity of the cell boundary are not preferential, it is possible to freely assign all frequencies without dividing in the frequency direction. Compared to this case, even with FFR, by implementing ICIC, the number of radio resources that can be used for scheduling decreases, and the throughput tends to decrease.

As described above, in-cell scheduling efficiency in each eNB and allocation restriction by ICIC are essentially contradictory controls. From time to time, unless the resource allocation is limited so as to match the load situation in the cell and the effect obtained by ICIC, the throughput is rather lowered.
In order to limit allocation according to the situation, it is possible to judge the situation more accurately by collecting system information over a wide range. Further, by optimizing the entire system, it is possible to obtain the effect of ICIC even with a smaller allocation limit. On the other hand, if it takes a long time to make a decision, it is impossible to follow the change in the situation. Therefore, it is necessary to shorten the period of information collection and control. If a large amount of system information is collected and controlled in a short cycle, there is a problem that the amount of communication between eNBs or in the system increases, and the capacity of the backbone network is compressed.
That is, the problem to be solved by the present invention is to collect resource information over a wide range so that the ICIC does not adversely affect the intra-cell scheduling, and to meet the traffic distribution and the effect obtained by the ICIC. It is an object to provide a resource allocation method that appropriately restricts the allocation of resources and does not reduce the capacity of the backbone network.
A typical example of the present invention is as follows. That is, a radio station that provides a radio communication area and is connected to a core network via a gateway, and is obtained by dividing radio resources that can be used in the radio communication area provided by the base station in predetermined units. Whether each resource block can be assigned to a terminal in the vicinity of the boundary of the wireless communication area and whether to assign to a terminal outside the boundary of the wireless communication area is set to a maintenance device, an ASGW, a specific eNB, Alternatively, an interface for receiving from a central control device provided separately from the maintenance device to optimize the entire system is provided, and a plurality of profiles defining the radio resource allocation restrictions are set through the interface, and the profile Specified by the profile of the specified identifier. By applying that quotas, and allocates the radio resources.
According to the embodiment of the present invention, ICIC control (that is, wireless communication) that collects and optimizes information over a wide range from the system device (maintenance device, ASGW, central control device, or specific eNB) higher than the eNB over the entire system. (Resource allocation limit) can be imposed on each eNB, and traffic within the system can be achieved without increasing the amount of communication between eNBs or between systems by switching the content of the allocation limit in a fast and linked manner within the system. It is possible to realize an ICIC that efficiently follows changes in the distribution and is not wasteful.

FIG. 1 is a block diagram showing a wireless communication network configuration from the third generation to the 3.5th generation.
FIG. 2 is a block diagram showing the principle of occurrence of inter-cell interference.
FIG. 3 is a block diagram showing the principle of FFR and a second specific example of ICIC.
FIG. 4 is a block diagram showing a wireless communication network configuration according to the embodiment of the present invention.
FIG. 5 is a diagram illustrating a structure of a radio resource block according to the embodiment of this invention.
FIG. 6 is a diagram illustrating a first example of allocation restriction for the eNB from the maintenance device according to the embodiment of this invention.
FIG. 7 is a diagram illustrating a second example of allocation restriction on the eNB from the maintenance device according to the embodiment of this invention.
FIG. 8 is a table showing resource allocation restrictions classified into four according to the traffic and the mobility of terminals in a cell in which an eNB according to the embodiment of the present invention is installed.
FIG. 9 shows the difference in control tendency between the fixed point switching method based on the RRM profile of the embodiment of the present invention, the control used in combination with the adaptive control method based on the adjustment between eNBs, and the case of only the adaptive control method. FIG.
FIG. 10 is a flowchart of processing for setting a plurality of allocation restrictions in an eNB from the maintenance device according to the embodiment of this invention.
FIG. 11 is a flowchart of the RRM profile switching process according to the embodiment of this invention.
FIG. 12 is a flowchart of RRM profile content update processing according to the embodiment of this invention.
FIG. 13 is an explanatory diagram illustrating an example of member variables and parameters according to the embodiment of this invention.

First, an outline of the present invention will be described. The following three points are typical features of the present invention.
(1) Each eNB in the system uses a three-dimensional structure array, and assigns each radio resource to a terminal near the cell boundary, and to other terminals (inside the cell) An interface is provided for receiving a permission indication. Here, if the classification of “terminals in the vicinity of the cell boundary” and “terminals in the cell” are extremely different between eNBs, the expected effect may not be obtained even if resource allocation restrictions are imposed. In order to avoid such a case, there is a restriction on the classification method and boundary value of “terminals around the cell boundary” and “terminals inside the cell” corresponding to the above three-dimensional structure array 1: 1. It also has an interface for receiving settings. A three-dimensional structure array, a classification method corresponding to the three-dimensional structure array, and setting of boundary values are combined to define one RRM profile.
In addition to the boundary value, information indicating that the boundary value is not fixed may be defined.
(2) Through the above-described interface, a plurality of RRM profiles are set for each eNB in the system from a system device (maintenance device, ASGW, central control device, or specific eNB) higher than the eNB and set. The assigned allocation limit can be switched.
(3) By using the fixed point switching method based on the RRM profile described above in combination with an adaptive control method based on adjustment between eNBs as in the first specific example of ICIC, it quickly follows changes in traffic distribution in the system. In addition, an ICIC without waste is realized.
An embodiment of the present invention will be described with reference to FIGS.
FIG. 4 is a block diagram showing a configuration of a wireless communication network according to the embodiment of this invention.
The wireless communication network according to the present embodiment includes a plurality of enhanced Node Bs (eNBs) 401 to 405, an Access Gateway (ASGW) 406, a maintenance device 407, and a central control device 412. Terminals 408 and 409 are connected to the respective eNBs 401 to 405.
The eNBs 401 to 405 have a radio base station function and a radio network control device function (for example, a part of the RNC function), form a radio interface with a terminal in its own cell (radio communication area), and Provides a wireless transmission / reception function for wirelessly transmitting information. The eNBs 401 to 405 perform radio resource scheduling in its own cell, retransmission control, determination of necessity of handover to another cell, and the like.
The ASGW 406 connects between the core network 410 of the mobile phone operator and the wireless network 411. Also, the ASGW 406 terminates the packet and calls the terminal by paging. The maintenance device 407 monitors a failure in the wireless communication network, controls the wireless communication network, and collects statistical information. In addition to the maintenance device 407, a central control device 412 for optimizing the entire system may be provided separately. The central controller 412 has an arbitrary configuration.
Each eNB 401 to 405 is connected to the ASGW 406 and transmits user data. Each eNB 401 to 405 is also connected to other neighboring eNBs, and exchanges control information for handover and ICIC adjustment. Each of the eNBs 401 to 405 is connected to the maintenance device 407, receives the setting of the system parameter value from the maintenance device 407, and reports statistical information to the maintenance device 407. The ASGW 406 is also connected to the maintenance device 407.
In particular, the present invention relates to an eNB scheduling function and an interface between a maintenance device and an eNB, an ASGW and an eNB, a central control device and an eNB, and an eNB and an eNB.
In a wireless communication system using OFDMA and capable of multiple transmissions in the spatial direction using a plurality of transmission / reception antennas, radio resources that can be used when communicating from an eNB to a plurality of terminals in its own cell are
(A) Frequency direction
(B) Time direction
(C) Spatial direction
Are divided into three dimensions and multiplexed in these three dimensions.
In the example shown in FIG. 5, four subchannels are divided in the frequency direction 501, three time division multiplex interlaces in the time direction 502, and four beam patterns in the spatial direction 503. The scheduling function of the eNB distributes 48 radio resource blocks to terminals in communication within the own cell per one scheduling period. When adaptive modulation is performed, the radio resource allocation is further determined in consideration of the overall resource allocation balance with respect to the packet size, modulation scheme, and transmission power used in each radio resource block 504.
The first feature of the present invention is that the maintenance device 407, the ASGW 406, the central control device 412, or a specific eNB 401 to 405 is used for each eNB in the system to each radio resource by using a three-dimensional structure array. This is the point of setting whether to assign terminals in the vicinity of the cell boundary and whether to assign terminals other than the above (inside the cell). Hereinafter, the case where the setting is made from the maintenance device 407 will be described as an example. However, the setting may be made from the ASGW 406, the central control device 412, or any one of the eNBs 401 to 405.
An advantage of using the ASGW 406 is that it is connected to a large number of eNBs on an existing network and can collect a wide range of information in association with call control of each eNB. On the other hand, since the range to which the ASGW 406 is connected is wide, there is a problem that processing delay of information collection and determination becomes large.
As an advantage of using any of the eNBs, the range connected in reverse to the ASGW 406 is narrow, but there is a point that information on short-range eNBs can be collected quickly and high-speed feedback control can be performed.
As a merit of using the maintenance device 407, the maintenance device 407 is connected to the ASGW 406 and each eNB on an existing network, and can collect information in a wider range than each eNB and in a narrower range than the ASGW 406.
Furthermore, as a merit of adding the central control device 412 separately, a large-capacity storage for processing and storing information that has not been collected by the conventional maintenance device 407, and a CPU for performing an optimization calculation with a large load By enhancing the function, it is possible to realize an advanced system optimization function that is not restricted by the configuration of the existing maintenance device 407.
From the maintenance device 407 to the eNBs 401 to 405, as the above-mentioned allocation limitation of each radio resource block,
(1) Maximum value of transmission power in the radio resource block,
(2) Whether or not the radio resource block can be allocated to terminals around the cell boundary,
(3) Whether the radio resource block can be allocated to terminals other than the above (inside the cell),
Is set. As a setting method, a three-dimensional structure array R [f] [t] [s] corresponding to the three dimensions (A) frequency, (B) time, and (C) space described above is prepared, and each radio resource is prepared. The allocation restrictions (1) to (3) above are defined as member variables for each block. FIG. 13 shows a member variable table and parameter examples. The maintenance device 407 does not need to notify the eNBs 401 to 405 of information on all elements of this structure array, and only the part whose value changes from the default value (that is, the part with restrictions) may be notified. Furthermore, when notifying the limited part, it is not necessary to notify each block, and the limited range and the content of the limitation may be notified.
As a first example (RRM profile 1) of allocation restriction from the maintenance device 407 to the eNB, as in the above-described second specific example of ICIC, FFR (adding restriction in the frequency direction of (A)) is performed Will be notified as follows.
R [f = 0] [*] [*] = {−, 0, 1}: frequency A in FIG. 3, 601 in FIG.
R [f = 1] [*] [*] = {−, 1, 0}: frequency B in FIG. 3, 602 in FIG.
R [f <1] [*] [*] = {−, 0, 0}: frequencies C and D in FIG. 3, 603 in FIG.
Here, “*” represents all the array elements, and “−” represents that the default value may be left as it is.
FIG. 6 shows the resource allocation category of the first example of allocation limitation.
The resource 601 is a resource assigned to a user inside the cell. A resource 602 is a resource allocated to users located around the cell boundary. The resource 603 is a resource that is not used in this cell (a resource that is not allocated).
Next, as a second example (RRM profile 2) of allocation restriction on the eNB from the maintenance device 407, the beam patterns that do not overlap in adjacent eNBs are concentrated in a specific interlace, and the allocation to terminals near the cell boundary is concentrated. When using ICIC by using, it notifies as follows.
R [*] [t = 1] [s <2] = {−, 1, 0}: 701 in FIG.
R [*] [t = 1] [s ≧ 2] = {−, 0, 0}: 702 in FIG.
R [*] [t ≠ 1] [*] = {−, 0, 1}: 703 in FIG.
FIG. 7 shows the resource allocation category of the second example of allocation limitation.
The resource 701 is a resource allocated to users around the cell boundary, and is divided into two regions on the space axis. The resource 702 is a resource that is not used in this cell (a resource that is not allocated). The resource 703 is a resource assigned to a user inside the cell.
As is apparent from these examples, according to the embodiment of the present invention, since it is possible to specify a restriction in three dimensions, it is possible to give an ICIC restriction by a combination of a plurality of axes.
Further, when the maintenance device 407, the ASGW 406, the central control device 412, or the specific eNB 401 to 405 corresponds to the above three-dimensional structure array in a 1: 1 ratio, Define the classification method and boundary values of “terminals in the vicinity of the boundary” and “terminals in the cell”, from the maintenance device 407, the ASGW 406, the central control device 412, or the specific eNB 401 to 405 to each eNB in the system On the other hand, this classification method and boundary value, or setting this boundary value is also one of the characteristics.
As a first example of the classification method, in a cell having a radius Ym centered on the base station, a terminal located within a radius Xm (<Ym) from the base station is referred to as a “terminal inside the cell” and a radius Xm. A method of distinguishing terminals located below Ym from “terminals near the cell boundary” can be considered. Actually, it is difficult for the base station to know the position of each terminal accurately only through normal communication with the mobile phone. A method is conceivable in which the position is measured using a GPS receiver separately mounted on the terminal, or the position is calculated by a three-point survey method based on the arrival time differences of pilot signals received from a plurality of base stations.
As a second example of the classification method, a terminal that attenuates in proportion to the distance from the base station and whose terminal pilot reception power amount is equal to or greater than a predetermined threshold (X dBm) is defined as a “terminal inside the cell”. A method may be considered in which terminals smaller than the threshold are classified as “terminals in the vicinity of the cell boundary”. The amount of pilot reception power is roughly proportional to the distance from the base station of the terminal, but there is a possibility that a terminal in a place where radio waves are difficult to reach, such as underground or valleys of buildings, may be classified into an incorrect category. However, it is considered that it is better to preferentially treat a terminal having a poor reception state even if it is not in the vicinity of the cell boundary in order to give the allocation limitation of the radio resource block, which is considered to be effective as a classification method.
As a second example of the classification method, a terminal whose pilot received power to interference power ratio is equal to or higher than a predetermined threshold (XdB) is defined as “terminal located inside the cell”, and a terminal smaller than the predetermined threshold is defined as “terminal located around the cell boundary” "Can be considered. In this case, the classification is made in consideration of the influence of interference from the surroundings, which is considered to be a more effective classification method.
Next, as an example of setting the boundary value, when the terminals are arranged in order according to each classification method so that the classification can be changed according to the terminal distribution in the cell, instead of being defined by the absolute value in the classification method described above. A method of classifying terminals within a predetermined threshold (X%) from the vicinity of the base station as “terminals inside the cell” and terminals exceeding the predetermined threshold as “terminals around the cell boundary” can be considered. .
Further, as a third example of the sorting method, it is possible to leave the sorting method and the boundary value to the discretion of each eNB without limiting the sorting method and the boundary value. For example, when the frequency is divided and allocated between cells as in the FFR described above, if it is within the maximum value of the transmission power, it does not affect other cells even if the allocation division is unbalanced between eNBs. Therefore, the expected effect can be obtained.
As described above, the cell boundary classification method and the boundary value can be set from a system device higher than the eNB (for example, the ASGW 406, the maintenance device 407, the central control device 412, etc.). It is possible to obtain the expected ICIC effect by aligning the “terminal” and “terminal in the cell” so that they do not vary extremely between eNBs.
The second feature of the present invention is that the maintenance device 407, the ASGW 406, the central control device 412 or the eNBs 401 to 405 sets a plurality of RRM profiles described above for each eNB in the system, and sets the assigned allocation. The limitation is that the limit can be switched.
In the following, the case of setting from the maintenance device 407 will be described as an example, but it is also possible to set from any of the ASGW 406, the central control device 412, or the eNBs 401 to 405.
The flow of processing for setting a plurality of RRM profiles in the eNB 401 from the maintenance device 407 will be described using FIG.
From the maintenance device 407, setting of the above-described restricted portion of the structure array as the RRM profile #N, and setting of the sorting method and the boundary value (or only the boundary value, information indicating that the boundary value is not determined) Is sent to the eNB 401 (step 1001). The eNB 401 writes the received RRM profile #N in the #N area of the RRM profile table (step 1002). When the writing of the RRM profile is completed, the eNB 401 reports the completion of writing of the RRM profile #N to the maintenance device 407 (step 1003). Note that it is possible to process the areas # 1 to # 4 collectively as shown in the figure, but it is also possible to process in the order of steps 1001, 1002, and 1003 for each area.
The maintenance device 407 designates which RRM profile is valid after the setting of the RRM profile by the RRM profile number. In the illustrated case, # 2 is designated (step 1004).
The eNB 401 reads the region of the RRM profile table corresponding to the designated number (step 1005), and applies the read RRM profile to the radio resource allocation restriction in its own cell (step 1006).
Thereafter, the eNB 401 reports to the maintenance device 407 that the designated RRM profile number # 2 has been validated (step 1007).
The maintenance device 407 sets the RRM profile by the same process in the other eNBs 402 to 405, but the content of the set RRM profile may be different depending on the eNB (even if it is the same RRM profile number). Also, the number designated as valid may be different depending on the eNB.
FIG. 11 shows a flow of RRM profile switching processing. The RRM profile switching process is the same as steps 1004 to 1007 of the allocation restriction setting process.
That is, the maintenance device 407 designates which RRM profile is valid by the RRM profile number when switching the RRM profile. In the illustrated case, # 1 is designated (step 1101).
The eNB 401 reads the region # 1 of the RRM profile table corresponding to the designated number (step 1102), and applies the read RRM profile to the radio resource allocation restriction in its own cell (step 1103).
Thereafter, the eNB 401 reports to the maintenance device 407 that the designated RRM profile number # 1 has been validated (step 1104).
In addition to the method of specifying an effective profile number from the maintenance device 407 to the eNB 401 at the time of switching as shown in the figure, the RRM profile is switched by specifying the effective profile number and switching timing in accordance with the maintenance device 407. It is also conceivable to change the allocation restriction to the profile number when the switching timing is set in advance through the interface and the switching timing set by the timer of the eNB 401 is reached.
FIG. 12 shows a flow of RRM profile content update processing. The RRM profile content update process is the same as steps 1001 to 1007 of the assignment restriction setting process.
That is, the maintenance device 407 sends an RRM profile whose contents are updated to the eNB 401. In the illustrated case, RRM profile # 1 is transmitted (step 1201). The eNB 401 writes the received RRM profile # 1 in the # 1 area of the RRM profile table (step 1202). When the writing of the RRM profile is completed, the eNB 401 reports the completion of writing of the RRM profile # 1 to the maintenance device 407 (step 1203).
The maintenance device 407 designates which RRM profile is to be validated by the RRM profile number after the update of the RRM profile is completed. In the illustrated case, the updated # 1 is designated (step 1204).
The eNB 401 reads the region of the RRM profile table corresponding to the designated number (step 1205), and applies the read RRM profile to the radio resource allocation restriction in its own cell (step 1206).
Thereafter, the eNB 401 reports to the maintenance device 407 that the designated RRM profile number # 1 has been validated (step 1207).
As a specific configuration example of the RRM profile, a first example of allocation restriction from the maintenance apparatus 407 to the eNB 401 is set as the RRM profile # 1, and a second example of allocation restriction from the maintenance apparatus 407 to the eNB 402 is the RRM profile # 2. Consider the case where it is set as
As shown in FIG. 6, in RRM profile 1, only half of all radio resources are used, so the throughput is low, but the effect of ICIC is high, and among the resources for terminals around the cell boundary, diversity in time direction and space direction Can be expected. As shown in FIG. 7, RRM profile 2 allocates 2/3 of the total radio resources to terminals located inside the cell, so that the throughput is higher than that of RRM profile # 1, but many terminals are around the cell boundary. If it exists, resources cannot be allocated. Which profile is appropriate to use depends on the environment in which the eNB to be set is installed and the state of the cell, as well as the relative state of not only the cell but also neighboring cells. Determined by. The cell state varies depending on the time of day, day of the week, season, and the presence / absence of a special event. This variation is often governed by factors outside the wireless communication system, such as what kind of facilities are in the cell, how people move according to the day of the week, time of day, weather, season, and so on. In order to select an appropriate profile, such factors should be considered.
FIG. 8 shows a diagram classified into four categories according to the amount of traffic (traffic) in the cell in which the eNB 401 is installed and the mobility of the terminal (mobility).
The first quadrant 801 in FIG. 8 is a case where both traffic and mobility are high. For example, the first quadrant 801 is a place where the movement of people is large and the number of people is large (station, department store, etc. at the time of congestion). In such a place, since it is considered that the terminal does not stay around the cell edge for a long time, a type of RRM profile in which throughput is more important than ICIC is suitable.
The second quadrant 802 in FIG. 8 is a case where traffic is high but mobility is low. For example, a place where many people are crowded but communicate at a fixed position (in a time zone where there are many homes such as nights and weekends). Collective housing, office hours, school hours, etc.). In such a place, throughput is important, but it is estimated that some terminals stay around the cell edge. Therefore, while securing a part of the radio resources for ICIC, the overall type is focused on throughput. RRM profiles are suitable.
The third quadrant 803 in FIG. 8 is a case where both traffic and mobility are low. For example, a place where there is a low probability of communication occurring in a cell (mountainous part, daytime such as daytime on weekdays, etc.) City). In such a place, in order to cover a wide area, a type of RRM profile in which ICIC is regarded as important is suitable. However, it is desirable to increase the degree of freedom of allocation so that a single terminal can occupy many resources.
The fourth quadrant 804 in FIG. 8 is a case where traffic is low but mobility is high. For example, a place where a terminal passes by a mobile object (on the road, along a railroad, offices other than working hours, night school, etc.) ). In such a place, a type of RRM profile that emphasizes ICIC is suitable. In particular, it is desirable to secure a large number of resources for terminals around the cell boundary so that good resources can be reliably allocated to terminals with high mobility.
The RRM profile 1 described above is of the fourth quadrant type, and the RRM profile 2 is of the second quadrant type. Therefore, an eNB installed in an office, a school, a housing complex (a housing complex), or the like is suitable for the eNB in which the RRM profile 1 is set. Also, in places such as offices and schools where there are many people during the daytime on weekdays, it is appropriate to apply the RRM profile 2 during the daytime on weekdays and to apply the RRM profile 1 during nighttime and body days. Furthermore, in places where there are many people at night and on body days (such as housing estates), it is appropriate to apply the RRM profile 1 during the daytime on weekdays and the RRM profile 2 during the night and body days.
The third feature of the present invention is that the fixed point switching method based on the RRM profile described above is used in combination with an adaptive control method based on adjustment between eNBs as in the first specific example of ICIC.
For example, the maintenance device 407 acquires statistical information including the cell traffic and the terminal mobility from each eNB 401 to 405 periodically (for example, at intervals of 1 to 2 hours). It is also possible to measure the radio wave propagation situation around the cell using an electric vehicle. The system administrator can predict the traffic trend of the cell by time zone by statistically processing and analyzing the information obtained in this way by hour, day of the week, season, and weather. . Then, the system administrator determines a plurality of RRM profiles and RRM profile switching timings, and sets the determined RRM profiles and the switching timings in the eNBs 401 to 405. The eNBs 401 to 405 superimpose the allocation limitation based on the RRM profile specified by the maintenance device 407 and the allocation limitation exchanged between the eNBs 401 to 405 as time elapses, and perform resource scheduling within the range of both limitations. . When the maintenance device 407 is instructed to switch the RRM profile, among the connected calls, for a call with severe QoS restrictions (for example, a voice call), the communication is continued without changing the allocation restriction suddenly. Do. On the other hand, resources for newly generated calls and best-effort packet communications are allocated according to the designation of the new profile.
FIG. 9 shows a change 901 in weekday daytime traffic volume in an eNB installed in a place where there are many people during the daytime, such as offices and schools, as in the above example. FIG. 9 also shows a traffic fluctuation 902 controlled by adaptive control and a traffic fluctuation 905 controlled by using both adaptive control and fixed point switching.
As in the first specific example of ICIC, the traffic fluctuation 902 of the adaptive control method based on the adjustment between the eNBs 401 to 405 follows the change 901 of the actual traffic with a certain delay, and thus corresponds to a sudden change. In addition, control overshoot occurs. On the other hand, in the fixed point switching method based on the RRM profile, the time zone in which traffic rapidly fluctuates and the directionality thereof are predicted from statistical information in advance, and can be assigned by switching from the RRM profile 1 to the RRM profile 2 at 9:00 am (903). Wireless terminals are increased, and a terminal located around the cell boundary is supported by switching to the RRM profile 1 again at 17:00 (904). By using together with the adaptive control method, as shown by a thin line 905, it is possible to quickly follow the change in traffic distribution in the system and realize a wasteful ICIC.
Even after setting the RRM profile and its switching time on the maintenance device 407 side, more accurate fixed-point switching can be performed by checking the traffic periodically and adjusting the contents and switching time of each profile based on the survey results. Can be implemented. When adding base stations, first set the conventional RRM profile to the initial value, operate the base station while covering the change by adaptive control, investigate statistical information etc. during the operation, and analyze the investigation results It is possible to adjust the contents of the RRM profile and the switching time based on the result.

  The present invention can be applied to a radio communication system that allocates radio resources to terminals in multi-dimensional structure arrangement and parameter setting. In particular, it is suitable for a radio resource management system in a radio communication system including a radio base station having a radio network control function.

Claims (33)

A base station that provides a wireless communication area and is connected to a core network via a gateway,
Whether to allocate terminals in the vicinity of the boundary of the radio communication area to each radio resource block obtained by dividing a radio resource usable in the radio communication area provided by the base station in a predetermined unit, and the radio communication It has an interface to receive the setting of whether to assign terminals that are outside the boundary of the area,
A plurality of profiles defining allocation restrictions of the radio resource are set through the interface,
A base station characterized by allocating the radio resource by applying an allocation restriction indicated by a profile of the designated identifier when receiving a designation of a profile identifier. The base station according to claim 1, wherein
The base station, wherein the radio resource block is obtained by dividing radio resources that can be used in a radio communication area provided by the base station according to frequency, time, and space axes. The base station according to claim 1, wherein
The radio resource allocation limit set by the plurality of patterns is defined according to a three-dimensional structure array according to frequency, time, and space,
The member function of the structure includes at least a variable indicating whether or not allocation to a terminal near the boundary of the wireless communication area and a variable indicating whether or not allocation to a terminal outside the boundary of the wireless communication area is possible. A base station characterized by that. The base station according to claim 1, wherein
The allocation restriction indicated by the profile and the switching timing of the profile are determined based on the communication amount of the base station and the mobility of the terminal in a wireless communication area provided by the base station. base station. The base station according to claim 1, wherein
A base that allocates the radio resource based on an allocation limit indicated by a profile number of the designated identifier and an allocation limit of a specific radio resource determined with another base station. Bureau. The base station according to claim 1, wherein
The base station, wherein the plurality of set profiles are switched based on a clock provided in the base station. The base station according to claim 1, wherein
The interface further receives a classification method and a boundary value in the classification method, or a boundary value in a certain classification method of a terminal outside the boundary of the wireless communication area and a terminal outside the boundary of the wireless communication area,
A base station that allocates radio resources based on the classification method and a boundary value in the classification method or a boundary value in the certain classification method. The base station according to claim 1, wherein
Whether it is a terminal around the boundary of the wireless communication area or a terminal outside the boundary of the wireless communication area,
(1) Based on the distance from the base station,
(2) based on the strength of the pilot signal of the base station received by the terminal, or
(3) A base station characterized in that it is determined based on a pilot reception power to interference power ratio of a pilot signal of the base station received by the terminal. The base station according to claim 1, wherein
A base station characterized in that a predetermined percentage of the terminals in the wireless communication area are terminals located outside the boundary of the wireless communication area. The base station according to claim 1, wherein
A base station characterized in that whether a terminal is located around the boundary of the wireless communication area or a terminal located outside the boundary of the wireless communication area is determined by a predetermined condition for each eNB. The base station according to claim 1, wherein
The base station, wherein the profile includes information indicating that the boundary value is not fixed. A device that provides a wireless communication area and is connected to a base station connected to a core network via a gateway,
Whether or not the base station can allocate each of the radio resource blocks obtained by dividing the radio resources that can be used in the radio communication area provided by the base station to terminals in the vicinity of the boundary of the radio communication area. And an interface for receiving a setting for whether or not to assign to terminals outside the boundary of the wireless communication area,
The device is
A plurality of profiles defining the radio resource allocation restrictions are set in the base station through the interface,
An apparatus for assigning a radio resource by applying an assignment restriction indicated by a profile of the designated identifier by designating an identifier of the set profile. The apparatus according to claim 12, comprising:
The radio resource block is an apparatus in which radio resources usable in a radio communication area provided by the base station are divided according to frequency, time, and space axes. The apparatus according to claim 12, comprising:
The radio resource allocation limit set by the plurality of patterns is defined according to a three-dimensional structure array according to frequency, time, and space,
The member function of the structure includes at least a variable indicating whether or not allocation to a terminal near the boundary of the wireless communication area and a variable indicating whether or not allocation to a terminal outside the boundary of the wireless communication area is possible. A device characterized by that. The apparatus according to claim 12, comprising:
The allocation restriction indicated by the profile and the switching timing of the profile are determined based on the communication amount of the base station and the mobility of the terminal in a wireless communication area provided by the base station. apparatus. The apparatus according to claim 12, comprising:
The base station is configured to allocate the radio resource based on an allocation limit indicated by a profile number of the designated identifier and an allocation limit of a specific radio resource determined with another base station. A device characterized by setting. The apparatus according to claim 12, comprising:
An apparatus configured to set the base station so as to switch the plurality of set profiles based on a clock provided in the base station. The apparatus according to claim 12, comprising:
Further, a classification method and a boundary value in the classification method, or a boundary value in a certain classification method, between a terminal located around the boundary of the wireless communication area and a terminal located outside the boundary of the wireless communication area is transmitted to the base station. ,
To the base station, the boundary values at the division method and the classification method, or apparatus according to claim Rukoto to assign a radio resource on the basis of the boundary value in the certain segment method. The apparatus according to claim 12, comprising:
Whether it is a terminal around the boundary of the wireless communication area or a terminal outside the boundary of the wireless communication area,
(1) Based on the distance from the base station,
(2) based on the strength of the pilot signal of the base station received by the terminal, or
(3) An apparatus characterized by being determined based on a pilot reception power to interference power ratio of a pilot signal of the base station received by the terminal. The apparatus according to claim 12, comprising:
A device characterized in that a predetermined percentage of the terminals in the wireless communication area are terminals located outside the boundary of the wireless communication area. The apparatus according to claim 12, comprising:
An apparatus characterized in that whether a terminal is located around the boundary of the wireless communication area or a terminal located outside the boundary of the wireless communication area is determined for each eNB under a predetermined condition. The apparatus according to claim 12, comprising:
The apparatus according to claim 1, wherein the profile includes information indicating that the boundary value is not determined. A base station that provides a radio communication area and is connected to a core network via a gateway, and a radio resource allocation method in a radio communication system including a device connected to the base station,
Whether or not the base station can allocate each of the radio resource blocks obtained by dividing the radio resources that can be used in the radio communication area provided by the base station to terminals in the vicinity of the boundary of the radio communication area. And an interface for receiving a setting for whether or not to assign to terminals outside the boundary of the wireless communication area,
The method
A plurality of profiles defining the radio resource allocation restrictions are set in the base station through the interface,
Specify the identifier of the profile to be applied,
A radio resource allocation method, wherein the radio resource is allocated by applying an allocation restriction indicated by the specified identifier profile. The radio resource allocation method according to claim 23, wherein
A radio resource allocation method comprising: generating the radio resource block by dividing radio resources that can be used in a radio communication area provided by the base station according to frequency, time, and space axes. . The radio resource allocation method according to claim 23, wherein
The radio resource allocation limit set by the plurality of patterns is defined according to a three-dimensional structure array according to frequency, time, and space,
The member function of the structure includes at least a variable indicating whether or not allocation to a terminal near the boundary of the wireless communication area and a variable indicating whether or not allocation to a terminal outside the boundary of the wireless communication area is possible. A radio resource allocating method characterized by the above. The radio resource allocation method according to claim 23, wherein
The allocation restriction indicated by the profile and the switching timing of the profile are determined based on the communication amount of the base station and the mobility of the terminal in the wireless communication area provided by the base station. A radio resource allocation method as a feature. The radio resource allocation method according to claim 23, wherein
The radio resource is allocated based on an allocation limit indicated by a profile number of the specified identifier and an allocation limit of a specific radio resource determined with another base station. Resource allocation method. The radio resource allocation method according to claim 23, wherein
A radio resource allocation method, wherein the plurality of set profiles are switched based on a clock provided in the base station. The radio resource allocation method according to claim 23, wherein
Further, a classification method and a boundary value in the classification method, or a boundary value in a certain classification method, between the terminal in the vicinity of the boundary of the wireless communication area and the terminal in the vicinity of the boundary of the wireless communication area, or the boundary value in a certain classification method are A radio resource allocation method comprising: setting a radio station. A radio resource allocation method according to claim 23,
Whether it is a terminal that is around the boundary of the wireless communication area or a terminal that is outside the boundary of the wireless communication area,
(1) Based on the distance from the base station,
(2) based on the strength of the pilot signal of the base station received by the terminal, or
(3) A radio resource allocation method characterized in that the radio resource allocation method is determined based on a pilot reception power to interference power ratio of a pilot signal of the base station received by the terminal. A radio resource allocation method according to claim 23,
A radio resource allocation method, wherein a predetermined percentage of the terminals in the radio communication area are terminals located outside the boundary of the radio communication area. A radio resource allocation method according to claim 23,
A radio resource allocation method, characterized in that whether a terminal is located around a boundary of a wireless communication area or a terminal located outside a boundary of a wireless communication area is determined for each eNB under a predetermined condition. A radio resource allocation method according to claim 23,
The radio resource allocation method according to claim 1, wherein the profile includes information indicating that the boundary value is not determined.

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