JP2000316182A - Base station equipment and terminal station equipment and communication system and communication control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain base station equipment, terminal station equipment, a communication system, and a communication control method for realizing efficient use of radio bands and impartial assignment of radio bands. SOLUTION: Base station equipment 1 is provided with a transmitting and receiving part 2 which transmits and receives all kinds of information by frame units with terminal station equipment 20a and 20b, a modulation system selecting part 3 which selects a modulation system, an error correction system selecting part 4 which selects an error correction system, a scheduler 5 which operates the assignment of each minislot in a frame, and a control part 6 which controls each part. The scheduler 5 operates the assignment of the minislots to be used for communication with each terminal station equipment 20a and 20b under the consideration of a modulation system or an error correction system so that the minislots in the frame can be utilized to the maximum. Therefore, it is possible to validly use a radio band, and to impartial assign the radio bands to each terminal station equipment 20a and 20b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication system for performing communication between a base station and a terminal station in units of a data frame composed of a plurality of fixed-length mini-slots.

[0002]

2. Description of the Related Art In a wireless communication environment, its propagation characteristics fluctuate greatly over time. When the distance between the base station and the terminal station is short and the line of sight is clear (line-of-sight propagation), generally, the propagation characteristics in the wireless section are good and no communication error occurs. However, when the terminal station moves out of line of sight of the base station or when the distance between the terminal station and the base station increases, the propagation characteristics rapidly deteriorate, and a communication error easily occurs.

[0003] As a technique for reducing communication errors, a technique for changing a signal modulation method or an error correction method is known. For example, when the propagation characteristics of the signal are good, it is desirable to perform transmission by an error correction method or a multi-level modulation method with a small band expansion rate to narrow the radio band of the signal. Conversely, when the signal propagation characteristics are poor, it is desirable to widen the radio band of the signal and adopt a modulation method or an error correction method that does not easily cause a communication error.

As described above, if the modulation method and the error correction method can be dynamically changed according to the wireless environment, etc.,
Information can be transmitted and received efficiently.

However, in the single carrier transmission system used in many conventional communication systems, it is difficult to adopt a different modulation system for each symbol because there is a correlation between adjacent symbols.

Recently, OFDM (Orthogonal Frequency Division Multi-Media) has been proposed as a transmission method resistant to multipath.
plexing) transmission schemes are attracting attention. OFDM transmission method is
This is a type of multi-carrier transmission system, and generates a time waveform (OFDM waveform) by performing discrete inverse Fourier transform on a plurality of subcarrier signals at once.

In the OFDM transmission method, unlike the conventional single carrier transmission method, since block processing is performed in units of symbols, adjacent OFDM symbols are uncorrelated. Therefore, in the OFDM transmission system, it is possible to easily apply a different modulation system for each symbol. Also, since the subcarriers are uncorrelated, it is also possible to apply different modulation schemes for each subcarrier.

In the conventional communication system, voice communication has been the mainstream, but in recent years the demand for data communication and the like has been increasing, and accordingly, various communication qualities have been required. .

In many of the conventional communication systems, communication is performed by allocating a fixed band to a user. If the modulation scheme or the error correction scheme is made variable while a fixed band is allocated, the data transmission rate changes. Therefore, in order to maintain a constant transmission rate, it is necessary to fix the modulation method and the error correction method.

[0010]

If the modulation method and the error correction method are made variable, the required radio band will be different even when transmitting data of the same information amount. Therefore, in order to make the modulation scheme and the error scheme variable while maintaining the communication quality such as the transmission rate constant, the radio band allocated to each user must be made variable.

In order to make the radio band allocated to each user variable, a scheduler for adjusting the radio band between users is required. In this type of scheduler, it is desirable to perform scheduling in consideration of a modulation scheme and an error correction scheme to be used in order to efficiently and fairly allocate a wireless band.

However, most of the conventional schedulers assign a fixed band to each user, and there is no one that performs a scheduling process in consideration of a modulation system and an error correction system of each user.

The present invention has been made in view of the above points, and has as its object to provide a base station apparatus and a terminal station apparatus capable of efficiently using a wireless band and fairly allocating a wireless band. , A communication system, and a communication control method.

Another object of the present invention is to provide a base station apparatus, a terminal station apparatus, a communication system, and a communication control method capable of allocating a radio band so as to obtain a communication quality desired by a user. Is to do.

[0015]

In order to solve the above-mentioned problems, the present invention is directed to a radio communication system comprising a plurality of fixed-length minislots between a plurality of terminal stations. In a base station device performing wireless communication in a communication procedure, a modulation method selecting means for selecting a modulation method for wireless communication with the wireless terminal, and an error correction method for selecting an error correction method for wireless communication with the wireless terminal Selection means, the modulation scheme selected by the modulation scheme selection means, and at least one of the error correction schemes selected by the error correction scheme selection means, the mini-slots in the frame are identified by the specific And a slot allocating means for allocating for communication with the terminal station apparatus.

According to the first aspect of the present invention, each minislot in a frame is allocated for communication with a specific terminal station apparatus based on the selected modulation scheme and error correction scheme.
The wireless band can be used efficiently, and the wireless band can be allocated fairly to each terminal station device.

According to the second aspect of the present invention, the mini-slots are allocated so that the number of empty slots of the mini-slots becomes equal to or less than a predetermined number, so that the radio band can be used efficiently.

According to the third aspect of the present invention, since the modulation system and the error correction system are selected so that the number of empty mini-slots in the frame is equal to or less than a predetermined number, the wireless band can be used efficiently.

According to the fourth aspect of the present invention, since the minislot is allocated based on the amount of information stored in the buffer, overflow of the buffer can be prevented.

According to a fifth aspect of the present invention, when at least one of the stored information amounts in the buffer is equal to or more than the first predetermined amount,
Since the minislot is preferentially assigned to the terminal station device corresponding to the buffer, the buffer overflow of the buffer can be reliably prevented.

According to the present invention, when the amount of information stored in the buffer is equal to or more than the first predetermined amount, as long as the amount of information is equal to or more than the second predetermined amount, the mini information is preferentially given to the terminal station apparatus corresponding to the buffer. Since slots are allocated, it is possible to reliably prevent overflow of the buffer.

According to the seventh aspect of the present invention, minislots are allocated in consideration of the ratio of each of the stored information amounts per unit time, so that it is possible to accurately know in advance whether or not a buffer overflow will occur. .

According to the eighth aspect of the present invention, if the input rates of all the buffers are equal to or more than the third predetermined amount, the minislot is preferentially allocated to the terminal station corresponding to the buffer having the largest amount of accumulated information. The amount of information stored in the buffer can be limited to some extent.

According to the ninth aspect of the present invention, when the input rate of the buffer is less than the third predetermined amount, the terminal station corresponding to the buffer thereafter until the input rate becomes equal to or more than the fourth predetermined amount. Since the minislot is preferentially allocated to the device, a buffer having a low input rate and a small amount of stored information is not disadvantageously treated in allocating a wireless band.

According to the tenth aspect, it is possible to efficiently perform at least one of the assignment of the wireless band for transmission to the terminal station device and the assignment of the wireless band for reception from the terminal station device.

According to an eleventh aspect of the present invention, there is provided a communication system for performing communication between a plurality of terminal station apparatuses and at least one wireless base station in a wireless communication procedure constituted by a frame comprising a plurality of fixed-length mini-slots. , A modulation scheme selection means for selecting a modulation scheme for communication between the terminal station apparatus and the radio base station, and an error correction scheme for selecting an error correction scheme for communication between the terminal station apparatus and the radio base station Selecting means, based on at least one of the modulation scheme selected by the modulation scheme selection unit and the error correction scheme selected by the error correction scheme selection unit, the minislot in the frame to a specific terminal And a slot allocating means for allocating for communication with the station device.

According to a twelfth aspect of the present invention, there is provided a communication control apparatus for performing communication between a plurality of terminal station apparatuses and at least one wireless base station in a wireless communication procedure constituted by a frame comprising a plurality of fixed-length mini-slots. In the method, a first step of selecting a modulation scheme during communication between the terminal station apparatus and the radio base station, and selecting an error correction scheme during communication between the terminal station apparatus and the radio base station Based on at least one of the second step, the modulation scheme selected in the first step, and the error correction scheme selected in the second step, each of the mini-slots in the frame is assigned to a specific terminal station. Allocating for communication with the device.

According to a thirteenth aspect of the present invention, in the terminal station apparatus for performing wireless communication with at least one wireless base station in a wireless communication procedure composed of a frame including a plurality of fixed-length minislots, A minislot recognizing means for recognizing the number of the minislots allocated for transmission of the own apparatus by the base station, a modulation scheme selecting means for selecting a modulation scheme at the time of wireless communication with the radio base station, and the radio base station An error correction method selecting means for selecting an error correction method at the time of wireless communication with the communication means, and communicating with the modulation method and the error correction method selected in advance using the number of minislots recognized by the minislot recognition means. When performing, the empty slot detecting means for detecting that a predetermined number or more empty slots among the mini-slots allocated for transmission of the own device, When the empty slot detection unit detects the predetermined number or more empty slots, at least one of the modulation scheme selected by the modulation scheme selection unit and the error correction scheme selected by the error correction scheme selection unit. Control means for changing one of the two.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a base station apparatus according to the present invention,
The terminal station device, the communication system, and the communication control method will be specifically described with reference to the drawings.

(First Embodiment) FIG. 1 is a block diagram showing a schematic configuration of a base station apparatus according to a first embodiment of the present invention. FIG. 2 is a block diagram showing a configuration in which the base station apparatus 1 of FIG. FIG. 4 is a diagram showing a data configuration of a data frame (hereinafter, simply referred to as a frame) transmitted / received between them.

As shown in FIG. 2, the frame is composed of a plurality of mini-slots, and the mini-slot length is fixed.
Here, the mini-slot is a basic unit (minimum unit) when band allocation is performed. In the present embodiment,
The case where the frame length is a fixed length will be described as an example.

For example, when communication is performed between the base station apparatus 1 and the terminal station apparatus 10 by the OFDM method, the minislot length is OF
It corresponds to the DM symbol length. That is, when a wireless packet is composed of ten OFDM symbols, one wireless packet is transmitted using ten minislots.

In the first embodiment, data communication is performed between the base station apparatus 1 and a plurality of terminal station apparatuses 10 according to the OFDM transmission method. An error correction method can be arbitrarily selected.

The base station apparatus 1 shown in FIG.
a, 20b for transmitting and receiving various types of information in frame units, a modulation scheme selection section 3 for selecting a modulation scheme, and an error correction scheme selection section 4 for selecting an error correction scheme.
And a scheduler 5 for allocating each mini-slot in the frame, and a control unit 6 for controlling each unit.

Next, the operation of the base station apparatus 1 of FIG. 1 will be described. First, from the base station apparatus 1 to the terminal station apparatuses 20a and 20b
A scheduling method related to the allocation of downlink minislots to a downlink will be described.

The control unit 6 controls the terminal station device 20 which is the destination.
For each of a and 20b, the information length of the information to be transmitted and the modulation method and error correction method of the information are input to the scheduler 5. For example, the information length of a frame transmitted to the terminal station device 20a is 48 bytes, and the modulation method is DQPS.
When the band expansion rate of K (Differentially Quadrature PSK) and the error correction method is 1/2, the information length after the band expansion is 96 bytes. If the number of OFDM subcarriers is 48, OFDM
Since one symbol is 12 bytes, eight OFDM symbols are required to transmit 96 bytes of encoded information. That is, in order to transmit one radio packet to the terminal station device 20a, it is necessary to allocate eight mini slots.

On the other hand, when the information length of the frame transmitted to the terminal station device 20b is 48 bytes, the modulation method is D8PSK, and the band expansion rate of the error correction method is 3/4, the information length after the band expansion is 64 bytes. . When the number of OFDM subcarriers is 48, one OFDM symbol is 18 bytes, and therefore, four OFDM symbols are required to transmit 64 bytes of encoded information. That is, in order to transmit one wireless packet to the terminal station device 20b, it is necessary to allocate four mini slots.

As described above, the user (the terminal station device 20a,
If different modulation schemes and error correction schemes are employed for each 20b), the required radio band will be different even when transmitting information of the same information length.

Therefore, the scheduler 5 shown in FIG. 1 does not perform the scheduling using only the data amount as a measure, but performs the scheduling in consideration of the modulation scheme and the error correction scheme actually used.

For example, in the case of the above-described example, the terminal station device 2
0a and 20b both require a communication quality of an information transmission rate of 48 bytes / frame, the terminal station device 20
When eight minislots are assigned to a and four minislots are assigned to the terminal station device 20b, both terminal station devices 20a and 20b satisfy the communication quality desired by their own stations. Become.

On the other hand, if it is necessary to fairly allocate the wireless band due to charging or the like, the terminal stations 20a, 20a
For example, eight mini-slots are assigned to each frame b. In this case, the terminal station device 20a
Communicates at an information transmission rate of 48 bytes / frame, and the terminal station device 20b communicates at an information transmission rate of 96 bytes / frame.

Here, it is assumed that as a result of scheduling performed by the scheduler 5, a space for five minislots is generated. Since the terminal station device 20a requires eight minislots per radio packet, the minislot 5
It is not possible to transmit a wireless packet using the available space. On the other hand, the terminal station device 20b requires four mini-slots per radio packet, and thus can transmit radio packets if five mini-slots are available. For this reason, the scheduler 5 allocates an empty space for five mini slots to the terminal station device 20b.

As described above, the scheduler 5 shown in FIG. 1 performs the scheduling in consideration of the modulation scheme and the error correction scheme, so that the minislots in the frame can be effectively used and the unused minislots are reduced. That is, the wireless band can be used effectively.

Next, a description will be given of a scheduling method relating to the allocation of uplink mini-slots from the terminal station devices 20a and 20b to the base station device 1. When the terminal station apparatuses 20a and 20b transmit information using the same modulation scheme and error correction scheme as the information transmitted from the base station apparatus 1, the base station apparatus 1 uses the modulation scheme transmitted by the terminal station apparatuses 20a and 20b and Since the error correction method can be determined, scheduling is performed in the same manner as for the downlink, and the uplink bandwidth is secured.

For example, for the terminal station device 20a described above, an integer multiple of eight minislots is used.
By allocating mini-slots that are integral multiples of four mini-slots to 20b, effective use of the radio band can be achieved.

When a physical header including information such as a synchronization signal is added to a wireless packet, scheduling can be performed in consideration of the physical header length. When the physical header lengths are different from each other, by selecting an appropriate physical header length in accordance with an empty minislot, minislots can be assigned in consideration of the physical header length.

More specifically, as shown in FIG. 3, a physical header selecting unit 7 for selecting any one of a plurality of physical headers having different physical header lengths is provided. The scheduling of each mini-slot is performed in consideration of the selected physical header length. At this time, the physical header length added to the radio packet for uplink and the physical header length added to the radio packet for downlink may be separately set.

As described above, according to the first embodiment, each terminal station device 20a,
Since mini-slots used for communication with the communication device 20b are allocated, mini-slots in a frame can be effectively used. Therefore, the wireless band can be used effectively, and the wireless band can be fairly allocated to each of the terminal station devices 20a and 20b.

(Second Embodiment) In a second embodiment, a buffer for temporarily storing information is prevented from overflowing.

FIG. 4 is a block diagram showing a schematic configuration of the second embodiment of the base station apparatus 1 according to the present invention. In FIG. 4, the same components as those in FIG. 1 are denoted by the same reference numerals, and different points will be mainly described below.

The base station apparatus 1 of FIG. 4 newly measures the buffers 8 provided for each of the terminal station apparatuses 20a and 20b and the amount of information stored in each buffer 8 in addition to the configuration of FIG. And a buffer amount measuring unit 9 for performing the processing. In FIG. 4, the buffers 8 are collectively displayed for simplicity.

The buffer 8 is provided in each terminal station device 20a, 20
b, and / or a reception buffer for storing information addressed to the base station device 1 from each of the terminal station devices 20a and 20b.

The scheduler 5 basically performs the same scheduling processing as in the first embodiment, but performs the scheduling processing in consideration of the amount of information stored in the buffer 8. Different from form.

FIG. 5 is a flowchart showing a scheduling process performed by the scheduler 5 of FIG. First, it is determined whether or not the amount of information stored in any of the buffers 8 is equal to or larger than a predetermined threshold A (step S1). Here, the determination process is performed based on the measurement result of the buffer amount measurement unit 9.

If the amount of information stored in any of the buffers 8 is equal to or larger than the threshold A, minislots are preferentially assigned to the terminal station devices 20a and 20b corresponding to the buffer 8 (step S2). ). Thereby, buffer overflow can be prevented.

The priority assignment in step S2 is continued until the amount of information stored in the buffer 8 becomes equal to or less than the threshold B (threshold B ≦ threshold A) (step S3).

When the amount of information stored in the buffer 8 becomes equal to or less than the threshold B, the process of step S1 is performed again.

On the other hand, in step S1, the buffer 8
If it is determined that the amount of information stored in the frame is less than the threshold A, the minislot in the frame is allocated in consideration of the modulation method and the error correction method, as in the first embodiment. As a result, the wireless band can be effectively used, and the wireless band can be fairly allocated to each terminal station device.

As described above, the buffer 8 in FIG. 4 may be a transmission buffer or a reception buffer. For example, when measuring the amount of information stored in both the transmission buffer and the reception buffer, the allocation of the downlink mini-slot from the base station apparatus 1 to the terminal station apparatuses 20a and 20b is performed based on the information stored in the transmission buffer. Can be performed, and the terminal station devices 20a, 20a
b to the base station device 1 can be allocated to the minislot for uplink.

When the mini-slot is allocated for the uplink, the amount of information stored in the transmission buffer may be used. For example, the terminal station device 20 having a large amount of information stored in the transmission buffer may allocate a large number of mini-slots for the uplink in anticipation that the information of the uplink will also be large. This is a method of allocating an uplink mini-slot in proportion to the amount of information stored in a transmission buffer.

Conversely, paying attention to the asymmetry of information, the terminal station device 20 having a large amount of information stored in the transmission buffer predicts that the information of the uplink will be small, and allocates a small number of mini-slots for the uplink. You may. This is a technique of allocating an uplink mini-slot in inverse proportion to the amount of information stored in the buffer 8.

Also, both the transmission buffer and the reception buffer may be used to allocate a mini-slot for downlink or uplink. in this way,
The present invention does not limit these specific allocation methods.

As described above, in the second embodiment, when the amount of information stored in the buffer 8 is equal to or larger than the threshold A, the minislot is preferentially assigned to the terminal station device 20 corresponding to the buffer 8. Since the allocation is performed, buffer overflow does not occur. If the amount of information stored in each buffer 8 is less than threshold A, the first
As in the first embodiment, the minislot is allocated in consideration of the modulation method and the error correction method, so that the radio band can be used effectively and the radio band can be allocated fairly to each of the terminal devices 20a and 20b. Can be.

Further, since the bandwidth for the uplink can be allocated based on the accumulated amount of the transmission or reception buffer of the base station, the traffic for the bandwidth allocation between the terminal station apparatus and the base station apparatus can be made unnecessary.

(Third Embodiment) Scheduling is performed in consideration of not only the amount of information accumulated in the buffer 8 but also the input rate of the buffer 8.

FIG. 6 is a block diagram showing a schematic configuration of the third embodiment of the base station apparatus 1 according to the present invention. 6, the same components as those in FIG. 5 are denoted by the same reference numerals, and different points will be mainly described below.

The base station apparatus 1 shown in FIG. 6 has, in addition to the configuration shown in FIG. 5, a buffer input rate measuring unit 10 for measuring the input rate of the buffer 8, that is, the rate of the amount of stored information per unit time.
Is provided.

The control unit 6 controls each of the buffer amount measuring unit 9 and the buffer input ratio measuring unit 10 and passes the information amount accumulated in the buffer 8 and the input ratio of the buffer 8 to the scheduler 5. The scheduler 5 performs a scheduling process based on the amount of information stored in the buffer 8 and the input rate of the buffer 8, and allocates a wireless band.

FIG. 7 is a flowchart showing a scheduling process performed by the scheduler 5 of FIG. Hereinafter, the processing operation of the fourth embodiment will be described based on the flowchart of FIG.

First, all terminal station devices 20a, 20b
It is determined whether or not the amount of information stored in at least one of the buffers 8 provided corresponding to the threshold value A is equal to or larger than the threshold A (step S11).

If there is a buffer 8 whose information amount is equal to or larger than the threshold A, a mini slot is preferentially allocated to the terminal station device 20 corresponding to this buffer 8 (step S12). This priority assignment is continuously performed until the amount of information stored in the terminal station device 20 becomes equal to or less than the threshold B (threshold B ≦ threshold A) (step S13).

When the amount of information falls below the threshold B,
The determination process of step S11 is performed again.

On the other hand, when it is determined in step S11 that the amount of information stored in all the buffers 8 is less than the threshold A, it is determined whether or not the input rates of all the buffers 8 are equal to or more than the threshold C (step S14). ).

If there is a buffer 8 whose input rate is less than the threshold C, minislots are preferentially assigned to the terminal station devices 20a and 20b corresponding to the buffer 8 (step S15). The reason for performing such processing is to prevent the terminal station apparatuses 20a and 20b having the buffer 8 having a small amount of accumulated information and a low input rate from being disadvantageously treated with respect to the allocation of the wireless band. is there.

Next, it is determined whether or not the amount of information stored in the buffer is greater than zero (step S16). When the accumulated information amount becomes zero, the process of step S11 is performed again. When the accumulated information amount is larger than zero, it is determined whether or not the input ratio of the buffer 8 is equal to or more than a threshold D (threshold D ≧ threshold C) (step S11). S17). If the input rate is equal to or more than the threshold D, the processing in step S11 is performed again. If the input rate is less than the threshold D, the processing in step S15 is performed again.

On the other hand, if it is determined in step S14 that the input rates of all the buffers 8 are equal to or higher than the threshold C, minislots are preferentially allocated to the terminal station device 20 having the largest amount of accumulated information. After that (step S18), the determination processing of step S11 is performed again.

As described above, in the third embodiment, the buffer 8 provided for each terminal station device 20a, 20b is provided.
In consideration of the amount of information stored in the buffer 8 and the input rate of the buffer 8, minislots used for communication with the terminal stations 20a and 20b are allocated, so that not only buffer overflow can be avoided, but also The amount of information that was
Terminal station devices 20a, 20 having buffers 8 with a low input rate
The wireless band can be fairly allocated to 0b.

Further, the scheduling method according to the fourth embodiment is effective for allocating a downlink from a base station apparatus to a terminal station apparatus, and uses an AWL (Asymmetric Wirele).
This is also effective for assigning a high-speed downlink to a communication system having a hybrid configuration such as ss Link).

(Fourth Embodiment) For example, when the terminal station apparatus 20 and the base station apparatus 1 communicate with each other, the modulation scheme is D8PSK, the error correction scheme is 3/4, and the number of OFDM subcarriers is 48.
When performing communication as a book, it is assumed that the base station apparatus 1 has allocated a radio band of 16 minislots for the uplink of the terminal station apparatus 20. In this case, the terminal station device 20
Two packets of 48-byte data (encoding information is 2 × 4
= 8 minislots), 8 (= 16-
8) Mini-slots are wasted.

Therefore, in the third embodiment described below, the terminal station apparatus 20 sets the optimum modulation scheme so that the free space of the minislots is reduced as much as possible according to the number of the minislots allocated to the own station. This is to select an error correction method.

FIG. 8 shows a fourth example of the terminal station device 20 according to the present invention.
It is a block diagram showing a schematic structure of an embodiment. The terminal station device 20 in FIG. 8 includes a transmitting / receiving unit 21 for transmitting / receiving information to / from the base station device 1, a mini-slot recognizing unit 22 for recognizing the number of mini-slots allocated to the own station, and mini-slot allocation. And a control unit 24 that controls each unit.

As in the example described above, when the minislot recognizing unit 22 recognizes that the base station apparatus 1 has allocated 16 minislots for the uplink of the terminal station apparatus 20, the scheduler 23 For example, DQPSK is selected as a modulation scheme, and an error correction scheme with a band expansion rate of 1/2 is selected. In this case, the number of minislots required to transmit information of two packets is 16 minislots. In other words, all of the assigned 16 mini-slots will be used.

As a method of notifying the base station of the modulation scheme and error correction scheme selected by the scheduler 23, for example,
There is a method of notifying in advance, and a method of including information on the selected modulation method and error correction method in the physical header. In the latter case, the physical header always uses a common modulation method and error correction method.

As described above, according to the fourth embodiment, a modulation method is used in which the minislot allocated to the own station is used as effectively as possible without changing the amount of information to be actually transmitted, and errors are less likely to occur. Since an error correction method is selected, communication errors are less likely to occur. If a communication error occurs,
Since a retransmission process is required, a new wireless band for retransmission is required. However, according to the fourth embodiment, since a communication error is less likely to occur, the frequency of the retransmission process can be reduced, and Communication efficiency is improved.

In particular, in the fourth embodiment, the frame used for communication between the base station and the terminal station has a fixed length, and the data length before modulation processing and error correction processing, for example, MPDU (MAC Protocol)
l In a communication system having a fixed length that does not depend on a modulation method or an error correction method, the bandwidth in a frame can be effectively used.

In the second to fourth embodiments described above,
When a physical header is added to a frame, the physical header selection unit 7 shown in FIG. 3 may be provided, and the minislot may be allocated in consideration of the physical header length.

[0087]

As described in detail above, according to the present invention, each minislot in a data frame is used for communication with a specific terminal station device based on the selected modulation system and error correction system. , The wireless band can be used efficiently and the wireless band can be fairly allocated to each terminal station device.

When a buffer is provided for each terminal station, scheduling is performed in consideration of the amount of information stored in the buffer, so that overflow of the buffer can be prevented.

Further, since the scheduling is performed in consideration of the input rate of the buffer, there is no risk that some terminal station apparatuses will be disadvantageously treated with respect to the allocation of the radio band.

Further, since the minislot allocated to the own station is used as effectively as possible to select a modulation method and an error correction method which are less likely to cause an error, a communication error is less likely to occur.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of a first embodiment of a base station apparatus according to the present invention.

FIG. 2 is a diagram showing a data configuration of a frame transmitted and received by the base station apparatus of FIG. 1 to and from a terminal station apparatus.

FIG. 3 is a block diagram obtained by adding a physical header selection unit to FIG. 1;

FIG. 4 is a block diagram showing a schematic configuration of a second embodiment of the base station apparatus according to the present invention.

FIG. 5 is a flowchart showing a scheduling process performed by the scheduler of FIG. 4;

FIG. 6 is a block diagram showing a schematic configuration of a third embodiment of the base station apparatus according to the present invention.

FIG. 7 is a flowchart showing a scheduling process performed by the scheduler of FIG. 6;

FIG. 8 is a block diagram showing a schematic configuration of a fourth embodiment of the terminal station device according to the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 base station apparatus 2 transmission / reception section 3 modulation scheme selection section 4 error correction selection section 5 scheduler 6 control section 10 buffer input rate measurement section 20, 20a, 20b terminal station apparatus 21 transmission / reception section 22 mini-slot recognition section 23 scheduler 24 control section

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takefumi Sakamoto 1 Komukai Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Prefecture Toshiba R & D Center (72) Inventor Osamu Moriya 1-chome Shibaura, Minato-ku, Tokyo No. 1 Toshiba Corporation Head Office (72) Inventor Minoru Minoru 1 Tokoba Toshiba-cho, Komukai-ku, Kawasaki-shi, Kanagawa F-term (reference) 5K067 AA13 BB04 CC04 DD13 DD25 DD27 DD34 DD51 EE02 EE10 EE16 EE22 EE63 EE65 EE71 GG01 HH24 HH25

Claims (13)

[Claims] 1. A base station apparatus for performing wireless communication with a plurality of terminal station apparatuses in a wireless communication procedure composed of a frame including a plurality of fixed-length mini-slots. Modulation method selecting means for selecting a modulation method, an error correction method selecting means for selecting an error correction method at the time of wireless communication with the wireless terminal, a modulation method selected by the modulation method selecting means, and the error correction Slot allocation means for allocating each of the mini-slots in the frame for communication with the specific terminal station apparatus, based on at least one of the error correction schemes selected by the scheme selection means. Base station device. 2. The terminal station apparatus to which the mini-slots are assigned, such that the number of free slots of the mini-slots in the frame is equal to or less than a predetermined number. The base station device according to claim 1. 3. A function for causing at least the modulation scheme selection means to select the modulation scheme so that the number of empty mini-slots in the frame is equal to or less than a predetermined number. 2. The base station apparatus according to claim 1, further comprising a control unit having any one of a selection function. 4. When wirelessly communicating with each of said terminal station devices,
A storage unit for temporarily storing transmission and / or reception information corresponding to each of the terminal station devices; and a storage amount measurement unit for measuring a storage information amount of each of the information stored in the storage unit. The slot allocation unit further includes: a modulation system selected by the modulation system selection unit, an error correction system selected by the error correction system selection unit, and a storage information amount measured by the storage amount measurement unit. 2. The base station apparatus according to claim 1, wherein each of the minislots in the frame is allocated for communication with a specific terminal station apparatus based on at least one of the following. 5. When the storage information amount of at least one of a plurality of pieces of information becomes equal to or more than a first predetermined amount, the slot allocating means gives priority to a terminal station apparatus corresponding to the information. The base station apparatus according to claim 4, wherein a mini slot is allocated. 6. The slot allocating means, when a mini-slot is preferentially allocated to a terminal station apparatus corresponding to the information whose storage information amount is equal to or greater than the first predetermined amount, the storage information amount is reduced. 6. The base station apparatus according to claim 5, wherein minislots are continuously assigned with priority to the terminal station apparatus while the second predetermined amount is equal to or less than the first predetermined amount. 7. A storage information amount measuring unit for measuring a ratio of each of the storage information amounts per unit time, wherein the slot allocating unit includes: a modulation method selected by the modulation method selection unit; The error correction method selected by the error correction method selection means, the storage information amount measured by the storage amount measurement unit, and the ratio of each of the storage information amounts per unit time measured by the storage information amount measurement means The base station apparatus according to claim 4, wherein each of the mini-slots in the frame is assigned based on at least one of the following. 8. The slot allocating means, when the ratio of each of the stored information amounts per unit time is equal to or more than a third predetermined amount, gives priority to the terminal station apparatus corresponding to the largest stored information amount. 8. The base station apparatus according to claim 7, wherein a minislot is allocated. 9. The slot allocating means, when at least any one of the ratios of the storage information amount per unit time is less than the third predetermined amount, the storage information amount becomes zero, Prior to allocating a mini-slot to a terminal station apparatus corresponding to the stored information amount until the ratio of each of the stored information amounts per unit time becomes equal to or greater than the third predetermined amount. The base station apparatus according to claim 8, wherein: 10. A method for communicating with at least one radio base station,
In a terminal station device that performs wireless communication in a wireless communication procedure composed of a frame including a plurality of fixed-length minislots, a minislot that recognizes the number of the minislots allocated for transmission of the own device by the wireless base station Recognizing means; modulation method selecting means for selecting a modulation method at the time of wireless communication with the wireless base station; error correcting method selecting means for selecting an error correcting method at the time of wireless communication with the wireless base station; Control means for determining at least one of a modulation scheme selected by the modulation scheme selection section and an error correction scheme selected by the error correction scheme selection section, based on the number of mini-slots recognized by the slot recognition section. A terminal station device comprising: 11. A communication system for communicating between a plurality of terminal station apparatuses and at least one wireless base station in a wireless communication procedure constituted by a frame composed of a plurality of fixed-length mini-slots. A modulation scheme selection unit that selects a modulation scheme during communication between the device and the wireless base station; an error correction scheme selection unit that selects an error correction scheme during communication between the terminal station device and the wireless base station; Based on at least one of the modulation scheme selected by the modulation scheme selection unit and the error correction scheme selected by the error correction scheme selection unit, the minislot in the frame communicates with a specific terminal station apparatus. And a slot allocating means for allocating the data to the communication system. 12. A communication control method for performing communication between a plurality of terminal station devices and at least one wireless base station in a wireless communication procedure constituted by a frame comprising a plurality of fixed-length mini-slots. A first step of selecting a modulation scheme at the time of communication between a station apparatus and the radio base station; and a second step of selecting an error correction scheme at the time of communication at the time of communication between the terminal station apparatus and the radio base station, Based on at least one of the modulation scheme selected in the first step and the error correction scheme selected in the second step, each of the mini-slots in the frame is used for communication with a specific terminal station apparatus. And a third step of allocating to the communication control method. 13. At least one radio base station,
In a terminal station device that performs wireless communication in a wireless communication procedure composed of a frame including a plurality of fixed-length minislots, a minislot that recognizes the number of the minislots allocated for transmission of the own device by the wireless base station Recognizing means; modulation method selecting means for selecting a modulation method at the time of wireless communication with the wireless base station; error correcting method selecting means for selecting an error correcting method at the time of wireless communication with the wireless base station; Using the number of mini-slots recognized by the slot recognizing means, when performing communication by the pre-selected modulation scheme and the error correction scheme, an empty slot among the mini-slots allocated for transmission of the own apparatus. Empty slot detecting means for detecting that the number is equal to or more than a predetermined number, and the predetermined number or more empty slots are detected by the empty slot detecting means. In the case, a terminal station comprising: a modulation scheme selected by the modulation scheme selection section; and control means for changing at least one of an error correction scheme selected by the error correction scheme selection section. apparatus.