JP2013090224A - Radio resource allocation method and base station - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform upper limit band restriction to each user on the radio network access side which is easily to be a bottleneck, so as to effectively utilize resources in an overall mobile communication system.SOLUTION: On receiving call connection requests from or to a plurality of terminals, a base station receives and stores restriction information related to a plurality of preset terminals; confirms existence or non-existence of an alarm indicative of a congestion condition in an upper-level network; sets an upper limit value of radio resource allocation, on the basis of the restriction information related to the plurality of terminals and the existence or non-existence of the alarm; and allocates radio resources so that radio resource allocation to each terminal does not exceed the set upper limit value.

Description

  The present invention relates to a mobile communication technology, and more particularly to a technology for controlling a bandwidth allocated to each terminal in a wireless section between a base station and the terminal.

  The charging methods used in packet communications for mobile phones include (1) flat-rate system, (2) two-stage flat-rate system, (3) pay-per-use system, and (4) upper-limit packet number and the maximum number of packets. There are methods that apply the flat rate system when the number of packets is exceeded. Among these, (2) the two-stage flat rate system is set to the first flat rate up to the first upper limit packet number, and is set to the pay-per-use rate from the first packet number up to the second packet number. This is a method in which the second fixed charge is applied when communication is performed more than the second number of packets. Specifically, first, the lower first flat fee is applied to the user, and communication is unlimited up to the first upper limit number of packets. When the first upper limit number of packets is exceeded, the fee is switched to a pay-as-you-go fee and charged according to the usage record. When the upper limit packet number (second packet number) of the pay-as-you-go fee is reached, the flat-rate system is applied again, and no matter what the communication is, no more than the second flat-rate fee is charged.

  In this way, a flat-rate system with an upper limit on the monthly usage fee is incorporated, such as (1) flat-rate system, (2) two-stage flat-rate system, and (4) a system in which the flat-rate system is applied when the maximum number of packets is exceeded. Many billing methods are adopted. In the flat rate system, even if a large amount of communication is carried out, no charge is charged beyond a certain amount. Therefore, the communication fee for each user has increased, and the influence of mass communication users (so-called heavy users) on other communications has also increased. It has become a problem.

  Non-Patent Document 1 restricts the communication speed for heavy users. Conventionally, the band restriction for such heavy users is limited to hardware such as a gateway device. It was done on the device on the core network side.

  On the other hand, in LTE, which is one of the 3.9th generation mobile communication systems, OFDMA (Orthogonal Frequency Division Multiple Access) is used for the downlink and SC-FDMA ( Single-Carrier Frequency Division Multiple Access) is used. In the LTE system, frequency division multiplexing (FDM) or time division multiplexing (TDM) is used as an uplink and downlink bidirectional communication scheme for each user in the same cell.

  The LTE radio frame has a time length of 10 ms in the time domain. This radio frame is composed of 10 subframes having a time length of 1 ms, and error correction is performed in units of subframes. Therefore, 1 ms is defined as a basic transmission time interval. The subframe is divided into two consecutive slots, and in the downlink, one slot (0.5 ms) is composed of 7 OFDM symbols.

  On the other hand, in the frequency domain, the number of subcarriers corresponding to the band allocated to each user is allocated. In LTE, 12 subcarriers (15 kHz × 12 = 180 kHz) × 7 symbols are called resource blocks and are used as basic transmission units. The aforementioned subframe is composed of two consecutive resource blocks. One subcarrier × 1 symbol is a basic unit that is individually modulated, and is called a resource element. Also in the uplink, similarly to the downlink, allocation (scheduling) to users is performed with a time length of 0.5 ms × bandwidth of 180 kHz as one resource block.

  As an algorithm applied to scheduling, there is an algorithm such as proportional fairness. In proportional fairness, the radio resources for each user are allocated with equal opportunity, and control is performed so that many slots are allocated when radio conditions are good. As a specific method for realizing proportional fairness, a technique for calculating a ratio between an average value and an instantaneous value of a user's past throughput and planning allocation of users and radio resources based on the magnitude of the ratio is disclosed in Patent Literature 1. Proportional fairness scheduling is introduced in Non-Patent Document 2 in addition to Patent Document 1.

WO 2009/131099

1xEV-DO: Utilizing efficiency improvement measures to realize the first flat-rate system for mobile data communications (Medium)-Technology Plaza: ITpro: Watanabe, Matsuda A. Jalali, R.A. Padovani, and R.A. Pankaj, “Data throughput of CDMA-HDR high efficiency-high data rate personal communication wireless system,” IEEE Proc. VTC Spring 2000, pp. 1854-1858, May 2000.

  As described in the background art, in the conventional mobile communication system, an upper limit value is set for the band allocated to each user, and the control for allocating a band equal to or lower than the upper limit value to each user is performed by a device on the core network side, for example, The base station on the radio access network side, which is performed at the gateway, has no control means for controlling the bandwidth allocated to each user below the upper limit value. For this reason, when band regulation is performed in the gateway device, the uplink data transmitted by the wireless terminal of the user whose radio condition is good without knowing it has reached the radio base station, but the band regulation performed in the gateway device. The problem of being discarded due to For the discarded data, since retransmission control such as TCP / IP occurs, there is a problem that the traffic on the radio access network side increases due to retransmission and the communication rate of the radio terminal rapidly decreases.

  Conversely, when the downlink bandwidth is regulated by a gateway device on the core network side, there is a problem that radio resources on the radio access network side cannot be effectively utilized.

The present invention has been made in order to solve the above-described problem, and allows the radio access network side, which is likely to become a bottleneck, to perform upper limit bandwidth regulation for each user, thereby effectively utilizing resources as a whole mobile communication system. The purpose is to be able to. For this reason, even if the uplink data sent from the terminal reaches the base station, it may be discarded by the GW that is band-restricted for each call. It dropped sharply.
Conversely, when downlink data is restricted in a wired section, wireless resources are not effectively utilized.
In the present invention, effective use of resources as a whole system is performed by performing band restriction in a wireless section that is likely to become a bottleneck.

  In order to solve the above-mentioned problem, in the present invention, in the allocation of radio resources to a plurality of terminals in a base station that transmits / receives data to / from a plurality of terminals by radio, the base station transfers from a plurality of terminals or to a plurality of terminals. When receiving the call connection request, the restriction information on the plurality of terminals set in advance is received and stored, the presence or absence of an alarm indicating the congestion state in the upper network is confirmed, the restriction information on the plurality of terminals and the alarm Based on the presence / absence of a radio resource, an upper limit value of radio resource allocation is set for each of a plurality of terminals, and a radio resource value that has already been allocated is subtracted from the upper limit value of each radio resource allocation. Radio resources are allocated to each terminal so that the set upper limit is not exceeded. Than is.

  According to the present invention, by controlling the upper limit bandwidth that can be allocated to each wireless terminal on the radio access network side, which is generally more likely to be a bottleneck than the core network side, It is possible to suppress congestion due to retransmission processing that occurs due to a difference in bandwidth that is limited on the side. In addition, the upper limit bandwidth can be finely controlled according to the regulation conditions of each user, and radio resources can be allocated without waste. According to the present invention, since the upper limit band is controlled in the base station, it is possible to prevent the base station from transmitting a packet that is discarded by the upper limit band restriction performed by, for example, the gateway device on the core network side.

  Furthermore, it is possible to finely control for each user the time zone for performing band regulation and the regulation value of band regulation for each base station according to the status of the base station.

It is a figure explaining the structure of the mobile communication system in one Example of this invention. It is a figure explaining the structure of the base station in one Example of this invention. It is a figure explaining the sequence of the call connection process in one Example of this invention. It is a figure which shows an example of the band control information table of an accounting server. It is a figure which shows an example of the band control information table of a base station. It is a figure which shows an example of the band control time table of a base station. It is a figure which shows an example of the maximum transmittable data amount table for every communication standard (communication system) of a base station. It is a flowchart explaining the determination processing content of the zone | band regulation value in one Example of this invention. It is a flowchart explaining the scheduling process of the downlink in one Example of this invention. It is a flowchart explaining the scheduling process of the uplink in one Example of this invention. It is an example of allocation of the slot of a downlink in one Example of invention. 4 is an example of uplink slot allocation in an embodiment of the present invention.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram showing a configuration diagram of a mobile communication system in an embodiment of the present invention.
In FIG. 1, UE1, UE2,. . UEn is a terminal connected to the base station 5. The base station 5 is connected to a gateway (GW) 1, a charging server 2, etc. via a LAN switch 4. The terminal communicates with the IP network via the GW. Here, for convenience of explanation, it is assumed that all terminals are located in the sector of the base station. In the present embodiment, the band restriction value of the radio section can be set individually for each terminal by the configuration described below.

FIG. 2 is a diagram illustrating the configuration of the base station in one embodiment of the present invention.
The base station receives the downlink traffic data received from the relay network 10 connected to the LAN switch, GW, etc. shown in FIG. 1 via the network interface 11 and stores it in the data buffer 12. In this embodiment, the base station receives, through the network interface, downlink traffic data, bandwidth regulation information for each call, an alarm for notifying that an over-band condition has occurred, and the like from the accounting server. In the following description of the present embodiment, each call, each terminal, and each user are used almost synonymously. Those pieces of information received from the accounting server are input to the band restriction information determination unit 15. The band restriction information determination unit 15 sets the band restriction information for each call received from the billing server 2, the alarm for notifying the occurrence of the over band received from the GW, and the time band for band restriction in the band restriction time table of the base station. If so, the content of the restriction time information is determined, and the restriction value for each call is determined. Based on the call restriction value determined by the band restriction information determination unit 15 and the radio quality information determined by the radio quality information determination unit 16 based on the radio signal received from the antenna 17, scheduling is performed by the scheduler 13 in the base station. Do. In the case of downlink data, the base station allocates radio resources for each terminal based on the scheduling result, and transmits the radio resource from the base station to the terminal. For uplink data transmitted from the terminal to the base station, the base station notifies each terminal of resource allocation information, which is a scheduling result, to the terminal using broadcast information.

FIG. 3 is a diagram showing a sequence of call connection processing in one embodiment of the present invention.
The call connection request S101 from the terminal includes information such as the user ID of the terminal and the communication standard (communication method) of the terminal. After receiving the call connection request S101, the base station notifies the charging server of the user ID of the terminal, and makes an acquisition request S102 of the terminal bandwidth restriction information to the charging server. The billing server notifies the base station of bandwidth restriction information corresponding to the user ID (S103). The base station that has received the band restriction information of the terminal from the charging server stores it in the memory in the base station (in the configuration example of the base station in FIG. 2, the memory in the band restriction information determination unit 15) (S104).

  If the base station receives a band restriction information or a band over occurrence alarm from GW or the like, the base station determines the band restriction information based on the contents of the alarm and the information of the band restriction time table preset in the base station. And the band regulation value is determined (S105). In the present embodiment, two types of alarms are prepared for the over-band occurrence alarm, a light over-band occurrence alarm and a severe over-band occurrence alarm depending on the over-band condition. In addition, the bandwidth restriction time table possessed by each base station is set in advance by notifying a time zone for bandwidth restriction for each base station from a maintenance device or the like. The band restriction information determination process in step 105 will be described with reference to FIGS. After the band restriction information is determined and the band restriction value is set, scheduling is performed based on the set band restriction value and the wireless communication quality between the terminal and the base station, and communication is started.

  After that, during communication, when the bandwidth severe over alarm notification, bandwidth minor over alarm notification, bandwidth over alarm release notification is received from the GW or the like, or the bandwidth regulation start time and bandwidth regulation set in the bandwidth regulation time table When the end time is reached (S108), an interruption process S109 occurs, the band restriction information determination process is performed again, and the band restriction value is updated and released (S110).

FIG. 4 is a diagram illustrating an example of a bandwidth regulation information table of the accounting server.
In the bandwidth regulation information table of the accounting server in FIG. 4, bandwidth regulation information for the maximum throughput is stored for each terminal (vertical axis). The bandwidth restriction information is set in three ways: normal time, bandwidth light alarm notification, and bandwidth severe alarm notification. These band regulation information is set according to the user contract information, the communication volume of the previous month, or the communication volume of the current month, and is stored in the accounting server table. This table may be automatically generated based on the above-mentioned user contract information managed by the accounting server, the communication volume of the previous month, or the communication volume of the current month, or may be set from the outside.

FIG. 5 shows an example of a band restriction information table in the base station.
The band restriction information table of the base station stores the band restriction information for each terminal obtained from the charging server by the base station. The base station stores the communication standard (communication method) information included in the call connection request and the band restriction information obtained from the billing server for each terminal that has made a call connection request.

Next, the band restriction time table of the base station will be described.
FIG. 6 is a diagram illustrating an example of a band restriction time table of the base station.
In the band restriction time table of the base station, the band restriction start time and end time are designated and set. Information on the band restriction time is set in advance for each base station from the maintenance device. As shown in FIG. 6, a plurality of band regulation time zones defined by the band regulation start time and end time may be provided.

FIG. 7 is a diagram illustrating an example of a table storing maximum transmission data information for each communication standard of the base station.
For each communication standard (communication method) supported by the base station, the base station stores information on the maximum transmittable data amount that can be transmitted by the terminal in the communication standard in a table.

Next, the content of the band regulation information determination process will be described.
FIG. 8 is a flowchart for explaining the contents of the base station bandwidth information determination process in one embodiment of the present invention.
FIG. 8 shows the processing contents in the band regulation information determination S105 or S110 in the sequence of FIG. When the base station obtains the bandwidth restriction information of the terminal from the accounting server when a call connection request is made from the terminal and stores it in the bandwidth restriction information table of the base station, the current time is the bandwidth restriction time set in advance from the maintenance device. It is determined whether it is within the band (S201).
If it is within the bandwidth regulation time zone, the process proceeds to S202, where the bandwidth regulation information in the bandwidth regulation time zone stored in the bandwidth regulation information table of the base station is read and substituted into A. If it is determined in step 201 that the current time is outside the band restriction time zone, the process proceeds to step 203 and 1 is substituted for A.

  After determining whether or not it is the bandwidth restriction time zone, it is confirmed whether there is an alarm for notifying the occurrence of bandwidth over. In a situation where a band minor over alarm indicating that a minor band over has occurred has been notified, the process proceeds to step 205 and the band at the time of the band minor alarm notification stored in the table of the band restriction information determination unit of the base station. The restriction information is read and assigned to B. In a situation where a band severe over alarm indicating that a severe band over has occurred has been notified, the process proceeds to step 206 and the band at the time of the band severe alarm notification stored in the table of the band restriction information determination unit of the base station. The restriction information is read and assigned to B. In the situation where the band over alarm is not notified, the process proceeds to step 207 and 1 is substituted for B.

Next, in step 208, A and B are compared, and the value which is the minimum value is set as the band regulation value. That is, when the bandwidth regulation information shown in FIG. 4 to FIG. 6 is set in the billing server or the base station, B = 1 in a situation where a band over occurrence alarm is not notified in the band regulation band. The band restriction value in the band restriction time zone of A becomes the minimum value, and the value assigned to A becomes valid and is set as the band restriction value determination result.
On the other hand, if it is not the band restriction time zone but an over band occurrence alarm is notified, A = 1, B band over alarm band restriction value becomes the minimum value, and it becomes effective. Set as a result.
In addition, when it is a bandwidth regulation time zone and a bandwidth over occurrence alarm is also notified, the value with the stricter regulation is adopted by setting the minimum value.

FIG. 9 is a flowchart of downlink scheduler processing in an embodiment of the present invention.
The base station receives downlink data from the GW and temporarily holds it in the buffer (S301). In downlink scheduling, a remaining downlink transmission permission data amount is set for each call. The remaining downlink transmission permission data amount is obtained by multiplying the maximum downlink transmittable data amount per unit time according to the communication standard by the bandwidth restriction value determined in step 208 of FIG. The maximum downlink transmittable data amount per unit time is calculated from the terminal communication standard (communication method) information stored in the table shown in FIG. 5 and the maximum downlink transmittable data amount in the communication standard of FIG.

Thereafter, the following processing is repeated for all resource blocks in the slot. In this example, the unit time is 1 second.
First, resources are allocated by an existing scheduling algorithm based on the wireless quality information, the remaining data amount, and the QoS information.
When there is no data received from the GW, or when none of the users can obtain sufficient radio quality in the corresponding resource block and there is no assigned user, the resource block is set as a free resource block S306. When there is data in the buffer and a user is allocated to the target resource block, it is determined whether or not the call is a band restriction call.
If the call is a downlink bandwidth restriction target call and the remaining downlink transmission permission data amount> 0, the remaining downlink transmission permission data amount is subtracted by the amount of data allocated to the call, and resource allocation is performed ( S309). If the call is a downlink bandwidth restriction target call and the remaining downlink transmission permission data amount of the call = 0, no resource is allocated to the call.
If the call is not a downlink bandwidth restriction target call, the remaining downlink transmission permission data amount is subtracted by the amount of data allocated to the call, and resource allocation is performed (S309). The processing so far is repeated for all resource blocks in the slot.
After completing the resource allocation to all the resource blocks in the slot, downlink data is set in the slot according to the resource allocation, and the downlink slot is transmitted to the terminal.
The remaining downlink transmission permission data amount is initialized every unit time.

FIG. 10 is a flowchart illustrating uplink scheduling processing according to an embodiment of the present invention.
The base station receives and holds the uplink resource allocation request from the terminal (S401). The base station sets a residual transmission permission data amount for each call. The remaining uplink transmission permission data amount (initial value) is obtained by multiplying the maximum uplink transmittable data amount per unit time according to the standard (communication method) by the band restriction value determined in step 208 of FIG. The maximum uplink transmittable data amount per unit time according to the standard (communication method) is calculated from the communication standard (communication method) of the terminal existing in the table of FIG. 5 and the maximum uplink transmittable data amount for the communication standard of FIG. .

Thereafter, the following processing is repeated for all resource blocks in the slot.
First, resource allocation is performed by an existing scheduling algorithm based on radio quality information, remaining data amount, and QoS information. If none of the users can obtain sufficient radio quality in the corresponding resource block and there is no assigned user, the resource block is designated as a free resource block S406. It is determined whether or not the resource block allocated to the user by scheduling is a bandwidth restriction call in step 407.
If the call is a downlink bandwidth restriction target call and the remaining downlink transmission permission data amount> 0, the remaining downlink transmission permission data amount is subtracted by the amount of data allocated to the call, and resource allocation is performed ( S409). If the call is a downlink bandwidth restriction target call and the remaining downlink transmission permission data amount of the call = 0, no resource is allocated to the call.
If the call is not a downlink bandwidth restriction target call, the remaining downlink transmission permission data amount is subtracted by the amount of data allocated to the call, and resource allocation is performed (S409). The processing so far is repeated for all resource blocks in the slot.

When the resource allocation of all the resource blocks in the slot is completed, the allocation information is notified to the terminal by broadcast information (S411). In accordance with this broadcast information, the terminal stores the uplink information in the allocated resource block and transmits it to the base station. The base station receives uplink data from the terminal and transmits it to the GW.
The base station initializes the amount of remaining uplink transmission permission data every unit time.

FIG. 11 shows an example of downlink resource allocation generated by a conventional scheduler and an example of downlink resource allocation according to the present embodiment.
Since the conventional bandwidth regulation shown in FIG. 11A is performed by the GW, the amount of data received by the base station is reduced for calls for which bandwidth regulation is performed. For this reason, there are many slots that are not allocated even though there are free radio resources.
In the bandwidth regulation of the present embodiment shown in FIG. 11B, the bandwidth of the radio resource can be reduced and the radio resource can be effectively used by regulating the bandwidth with the scheduler of the base station.

FIG. 12 shows an example of uplink resource allocation generated by a conventional scheduler and an example of uplink resource allocation according to this embodiment.
When data exceeding the allowable bandwidth in the wired section is assigned to the slot, there is a possibility that data discard in the GW may occur. When data discard occurs, retransmission occurs and efficiency is poor.
FIG. 12B is an example of uplink resource allocation generated by the scheduler of this embodiment. As in the present embodiment, the scheduler allocates radio resources in consideration of the bandwidth situation in the wired section, thereby reducing data discard in the GW and preventing a communication rate from being lowered due to retransmission processing.

  By using the embodiment described above, it is possible to perform a band restriction process when resources are allocated by the scheduler of the base station. In general, bandwidth restriction is performed in a wireless section that is more likely to be a bottleneck than a wired section, thereby suppressing congestion due to retransmission processing, and fine-tuned control based on terminal restriction conditions enables wireless resources to be allocated without waste. is there. The bandwidth restriction amount can be determined by the ratio to the maximum throughput, and an upper limit value of the maximum throughput in the restriction state can be put on a catalog or the like. Furthermore, bandwidth control is performed in the wireless section of the uplink data by notifying the base station of the traffic situation of the wired section from a device such as a GW or a LAN switch, and the traffic when congestion occurs in the wired section Can be suppressed.

DESCRIPTION OF SYMBOLS 1 Gateway 2 Charging server 3 IP network 4 LAN switch 5 Base station 6 Terminal 10 Relay network 11 Network interface 12 Data buffer 13 Scheduler 14 Wireless processing part 15 Band restriction information determination part 16 Radio quality information determination part 17 Antenna

Claims (4)

A method of assigning radio resources to a plurality of terminals in a base station that transmits and receives data to and from a plurality of terminals by radio,
Receiving and storing restriction information on the plurality of terminals set in advance when receiving a call connection request from the plurality of terminals or to the plurality of terminals;
In addition, check whether there is an alarm indicating the congestion status in the upper network,
Based on the restriction information on the plurality of terminals and the presence / absence of the alarm, an upper limit value of radio resource allocation is set for each of the plurality of terminals,
Subtracting the already assigned radio resource value from the upper limit value of each radio resource allocation, and allocating radio resources to each terminal so that the radio resource allocation to each terminal does not exceed the set upper limit value A radio resource allocation method.   The alarm notification includes an alarm indicating that the congestion state is mild and an alarm indicating that the congestion state is severe, and controls the upper limit value of the radio resource according to the congestion state. The radio resource allocation method according to claim 1.   The base station has a table in which information on a restricted time zone set in advance by a maintenance device is stored, refers to the table in which the information on the restricted time zone is stored, and the current time is within the restricted time zone The radio resource according to claim 1, wherein it is determined whether or not there is a radio resource, and if it is a regulation time zone, an upper limit value of radio resources is set based on regulation information set for the regulation time zone. Resource allocation method. A base station that transmits and receives data with a plurality of terminals wirelessly,
Receiving and storing restriction information on the plurality of terminals set in advance when receiving a call connection request from the plurality of terminals or to the plurality of terminals;
In addition, check whether there is an alarm indicating the congestion status in the upper network,
Based on the restriction information on the plurality of terminals and the presence / absence of the alarm, an upper limit value of radio resource allocation is set for each of the plurality of terminals,
Subtracting the already assigned radio resource value from the upper limit value of each radio resource allocation, and allocating radio resources to each terminal so that the radio resource allocation to each terminal does not exceed the set upper limit value Base station.

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