JP2011055221A - Wireless communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively achieve direct communication between mobile stations in a wireless communication system of an OFDMA-TDD communication type which has a base station apparatus and a plurality of mobile station devices. <P>SOLUTION: In the wireless communication system, the mobile station devices transmit requests for performing the direction communication between the mobile stations without interposing the base station apparatus to the base station apparatus. The base station apparatus controls uplink data areas 25 included in a radio frame so that all the uplink data areas are used for communication between the mobile station devices and the base station apparatus when all the mobile station devices communicate only with the base station apparatus, and controls the uplink data areas so as to a part 26 of the uplink data areas as a communication area for performing the direct communication between the mobile stations so that the number of OFDMA symbols in the communication area for performing the direct communication between the mobile stations is minimized when the requests are received from the mobile station devices. The mobile station devices perform the direct communication between the mobile stations using the assigned communication area. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a wireless communication system that uses, for example, OFDMA (Orthogonal Frequency Division Multiple Access) -TDD (Time Division Duplex) communication method, and more particularly to direct communication between mobile station devices (hereinafter referred to as direct communication between mobile stations). It is related with the radio | wireless communications system which implement | achieves communication.

  For example, in an Orthogonal Division Multiplexing (OFDM) scheme, a data sequence to be transmitted is divided into a plurality of pieces and transmitted in parallel using a plurality of subcarriers. Therefore, in this method, even under frequency selective fading, since it can be regarded as flat fading with each subcarrier, the influence of distortion due to multipath can be reduced. Also, by inserting a signal called CP (Cyclic Prefix), the influence of intersymbol interference can be removed, and high-speed and high-quality data transmission is possible.

OFDMA is a multiple access scheme based on OFDM, which realizes multiple access by sharing all subcarriers among multiple users and adaptively assigning specific subcarriers and specific symbols to each user. .
In a multi-user system using OFDM, it is common to manage multiple channel assignments in the downlink and uplink directions by applying multiple access using OFDMA.
In general, the direction from the base station apparatus to the mobile station apparatus is the downlink direction, and the direction from the mobile station apparatus to the base station apparatus is the uplink direction.

FIG. 4 shows an example of the frame configuration of the conventional system when the duplex system is the TDD system. The horizontal direction represents the OFDM symbol direction (time direction), and the vertical direction represents the subcarrier direction (frequency direction).
The frame of this example is provided with the region of the synchronization signal 21, the downlink control region 22, and the downlink data region 23 as the downlink subframe region, and the uplink control region 24, the uplink data region 23 as the uplink subframe region. A data area 41 is provided.

  The downlink subframe always starts with a synchronization signal 21 (also called a preamble), and the mobile station apparatus detects the synchronization signal 21 and pulls in frame synchronization. Next, the mobile station apparatus outputs a time / frequency synchronization signal in the uplink control region 24, and the base station apparatus determines the time lag in transmission timing and the transmission frequency of the mobile station apparatus from the time / frequency synchronization signal. A shift is detected, and a time correction amount and a frequency correction amount are output in the downlink control region 22 to the mobile station apparatus. Then, the mobile station apparatus outputs a transmission signal without causing interference to other users by correcting a transmission timing shift and a transmission frequency shift based on the received time correction amount and the frequency correction amount. Ready to do.

  When the mobile station apparatus completes connection with the base station apparatus in this way, the base station apparatus sets the allocation of the downlink data area 23 and the uplink data area 41 to the user for each frame, and Information is output from the downlink control area 22, and transmission data is output from the downlink data area 23 based on the allocation. Then, the mobile station apparatus receives the data addressed to itself in the downlink data area 23 based on the allocation information received in the downlink control area 22, and outputs transmission data in the uplink data area 41 based on the allocation. To do.

  As described above, in the frame configuration according to the conventional example, data transmission from the base station apparatus to the mobile station apparatus is performed in the downlink data area 23, and data transmission from the mobile station apparatus to the base station apparatus is performed in the uplink data area 41. This realizes data communication between the base station apparatus and the mobile station apparatus.

JP 2007-053579 A

  However, in the OFDMA-TDD communication method according to the conventional example as described above, the downlink direction is limited to communication from the base station apparatus to the mobile station apparatus, and the uplink direction is limited to communication from the mobile station apparatus to the base station apparatus. Therefore, the mobile station devices cannot directly communicate (direct communication between mobile stations) without going through the base station device.

  Therefore, in the OFDMA-TDD radio system according to the conventional example described above, a specific subcarrier is always assigned as a dedicated channel for direct communication between mobile stations, and the mobile station uses the dedicated channel in a state independent of the base station apparatus. Although it is conceivable to perform direct communication between stations, if signals are transmitted asynchronously to the base station apparatus, interference between OFDM symbols occurs, and if there is an offset in the transmission frequency of the mobile station apparatus, inter-carrier interference occurs. There was a problem that the characteristics deteriorated significantly. Further, even when direct communication between mobile stations is not performed, the dedicated channel is always secured, so that there is a problem that transmission efficiency is lowered.

The present invention has been made in view of such conventional circumstances. For example, it is an object of the present invention to provide a communication system capable of effectively realizing direct communication between mobile stations in an OFDMA-TDD communication system. To do.
As a specific example, the present invention provides a wireless communication system capable of realizing direct communication between mobile stations without degradation of communication quality and transmission efficiency in an OFDMA-TDD communication system.
In addition, as a specific example, an object of the present invention is to provide a wireless communication system capable of suppressing power consumption of a mobile station apparatus by reducing power consumption during direct communication between mobile stations.

In order to achieve the above object, in the present invention, an OFDMA-TDD communication wireless communication system having a base station apparatus and a plurality of mobile station apparatuses has the following configuration.
That is, in the mobile station apparatus, the request transmission means transmits a request for performing direct communication between the mobile station apparatuses to the base station apparatus without going through the base station apparatus. In the base station apparatus, when all the mobile station apparatuses communicate with only the base station apparatus with respect to the uplink data area included in the radio frame, all the uplink data areas are mobile stations. When a request for performing direct communication between the mobile station devices is received from the mobile station device, direct communication between the mobile station devices is controlled. In order to minimize the number of OFDMA symbols in the communication area for performing communication, control is performed so that a part of the uplink data area is allocated as a communication area for direct communication between mobile station apparatuses. In the mobile station apparatus, direct communication means performs direct communication between the mobile station apparatuses using a communication area assigned as a communication area for direct communication between the mobile station apparatuses by the base station apparatus.

Therefore, for example, in the OFDMA-TDD communication system, direct communication between mobile stations can be realized without deterioration of communication quality and transmission efficiency. As an example, it is possible to prevent inter-symbol interference and inter-carrier interference while ensuring time and frequency synchronization with the base station apparatus while performing direct communication between mobile station apparatuses.
In addition, by minimizing the number of OFDMA symbols in the communication area for performing direct communication between mobile station apparatuses, for example, the power consumption of the mobile station apparatus can be reduced by reducing power consumption during direct communication between mobile stations. Can be suppressed.

As one configuration example, the wireless communication system according to the present invention has the following configuration.
That is, the mobile station device that performs communication using the communication region (direct communication region between mobile stations) for performing direct communication between the mobile station devices described above, the synchronization signal transmitted from the base station device, Only the signal in the downlink control area and the signal in the direct communication area between the mobile stations are demodulated, and the other OFDMA symbols are not demodulated.
This prevents intersymbol interference and intercarrier interference while maintaining the time and frequency synchronization state with the base station apparatus while performing direct communication, and reduces the number of OFDMA symbols for modulation / demodulation processing. Power consumption in the station apparatus can be reduced.

Here, various numbers may be used as the number of base station apparatuses and the number of mobile station apparatuses included in the wireless communication system.
In the mobile station device, a request for performing direct communication between the mobile station devices is transmitted in response to an operation by an operator (person), for example.
Various radio frames may be used. For example, a radio frame obtained by adding the improvements according to the present invention to those generally used in the OFDMA-TDD communication scheme is used. .

  Also, in the base station apparatus, various methods may be used as a method for determining the case where all mobile station apparatuses communicate only with the base station apparatus. For example, the mobile station apparatus moves from any mobile station apparatus. A method for determining a case where a request for performing direct communication between station apparatuses is not received as a corresponding case, and even if such a request is received from one or more mobile station apparatuses, all requests are subsequently received. A method can be used in which a case where the mobile station apparatus is withdrawn (for example, all mobile station apparatuses that have issued a request have shifted to another mode) are applicable, or the base station apparatus is under the control of its own apparatus. It is also possible to use a method of storing and managing in a memory whether or not each mobile station apparatus is in a mode for performing direct communication between mobile station apparatuses, and determining based on the management contents.

Moreover, various aspects may be used as some aspects of the uplink data area allocated as a communication area for performing direct communication between mobile station apparatuses. Further, a part of the uplink data area may be set in advance in the base station apparatus and each mobile station apparatus and stored in the memory, or may be stored in the memory from the base station apparatus during operation or the like. May be notified.
Also, for example, all of the uplink data area is used for communication between the mobile station apparatus and the base station apparatus, or a part of the uplink data area is allocated as a communication area for direct communication between the mobile station apparatuses. For example, notification is made from the base station apparatus to the corresponding mobile station apparatus (for example, all mobile station apparatuses may always be notified).

  As described above, according to the wireless communication system according to the present invention, for example, direct communication between mobile stations can be effectively realized in the OFDMA-TDD communication system.

It is a figure which shows the example of a structure of the frame of the OFDMA-TDD communication system which concerns on one Example of this invention, and an example of transmission / reception timing. It is a figure which shows an example of the flow of a process of the direct communication between the mobile stations of the OFDMA-TDD communication system which concerns on one Example of this invention. It is a figure which shows an example of a frame structure of an OFDMA-TDD communication system, and an example of transmission / reception timing. It is a figure which shows the structural example of the flame | frame of the OFDMA-TDD communication system which concerns on background art. It is a figure which shows the structural example of a radio | wireless communications system.

Embodiments according to the present invention will be described with reference to the drawings.
FIG. 5 shows a configuration example of the wireless communication system.
Specifically, the base station apparatus 1 and its communication area 2 and a plurality of mobile station apparatuses 11 to 14 are shown.
The mobile station device 11 and the mobile station device 12 communicate with each other via the base station device 1 by wirelessly communicating with the base station device 1. In addition, the mobile station device 13 and the mobile station device 14 perform direct wireless communication (direct communication between mobile stations).

A first embodiment of the present invention will be described.
For example, when the duplex method is the TDD method, a part of the uplink channel is allocated for direct communication between mobile stations, so that the mobile station device and other mobile station devices can be connected without going through the base station device. It is possible to communicate directly between.

FIG. 3 shows an example of the frame configuration and transmission / reception timing of the OFDMA-TDD communication system. The horizontal direction represents the OFDM symbol direction (time direction), and the vertical direction represents the subcarrier direction (frequency direction).
The frame of this example is provided with the region of the synchronization signal 21, the downlink control region 22, and the downlink data region 23 as the downlink subframe region, and the uplink control region 24, the uplink data region 23 as the uplink subframe region. A data area 31 and a mobile station direct communication priority area 32 are provided.

In this example, for example, the direct communication priority area 32 between mobile stations is included in the uplink data area 31, and is handled in the same manner as the uplink data area 31 when not assigned as the direct communication priority area 32 between mobile stations. .
In this example, it is considered that the direct communication priority area 32 between mobile stations is included in the uplink data area 31, and as another way of understanding, these areas 31 and 32 are regarded as separate areas. However, in any way, it is substantially the same.

Here, for convenience of explanation, in FIG. 3, the same parts 21 to 24 as those shown in FIG.
In this example, the process (sequence) until the mobile station apparatus is connected to the base station apparatus is the same as that in the OFDMA-TDD communication system according to the conventional example described with reference to FIG. Since there is, explanation is omitted.

  In this example, for the transition process (sequence) between the base station communication mode and the direct communication mode between mobile stations, for example, the “direct communication priority symbol 26 between mobile stations” is changed to “direct communication priority between mobile stations”. If it is read as “region 32”, it is the same as the OFDMA-TDD communication system described with reference to FIG. 1 and FIG.

  As described above, in this example, in the communication frame in the OFDMA-TDD wireless communication system including the base station device and the mobile station device, the synchronization signal 21 for the mobile station device to synchronize the frame with the base station device. An area, a downlink control area 22 for transmitting a control signal from the base station apparatus to the mobile station apparatus, a downlink data area 23 for transmitting data from the base station apparatus to the mobile station apparatus, and a base station from the mobile station apparatus An uplink control area 24 for sending a control signal to the apparatus, an uplink data area 31 for sending data from the mobile station apparatus to the base station apparatus, and the mobile station apparatuses directly communicating with each other without going through the base station apparatus If there is a mobile station device to be used, it is used to transmit and receive data between the mobile station devices. With between mobile station direct communication priority area 32 which is used to send data to the service unit.

  Specifically, the wireless communication system of this example is an OFDMA-TDD communication system communication system including a base station device and a plurality of mobile station devices, and all mobile station devices communicate with only the base station device. When performing, the entire uplink data area 31 of the radio frame is used for communication with the base station device, whereas when performing direct communication between the mobile station devices without going through the base station device, the base station device moves In response to a request from the station apparatus, a part of the uplink data area 31 is allocated as a communication area for direct communication between mobile stations (direct communication priority area 32 between mobile stations), and the mobile station apparatus allocates the allocated communication area. To communicate directly. Thereby, in the mobile station apparatus, it is possible to prevent intersymbol interference and intercarrier interference while securing the time and frequency synchronization state with the base station apparatus while performing direct communication.

  Therefore, in the radio communication system of the OFDMA-TDD communication system of this example, a part of the uplink data area 31 is reserved exclusively for direct communication between mobile stations only when there is a mobile station apparatus that performs direct communication between mobile stations. In other cases, the entire uplink data area 31 is ensured for base station communication, thereby suppressing a decrease in transmission efficiency and maintaining the synchronization between the mobile station apparatus and the base station apparatus without moving the communication quality. Direct communication between stations can be realized.

  Thus, in this example, when all the mobile station devices perform transmission / reception with the base station device while maintaining synchronization between the mobile station device and the base station device, all of the uplink data area 31 is exchanged with the base station device. When there is a mobile station apparatus that secures communication and performs communication without going through the base station apparatus, a part of the uplink data area 31 is dedicated to the (other) mobile station apparatus from the mobile station apparatus. For example, even when a plurality of mobile station apparatuses have a function of performing direct communication without going through the base station apparatus, it is possible to prevent transmission efficiency and communication quality from being deteriorated.

A second embodiment of the present invention will be described.
(Description of the purpose of this embodiment)
The frame configuration according to this embodiment is a further improvement of the frame configuration shown in FIG.
For example, in the OFDMA-TDD communication method using the frame configuration shown in FIG. 3, the inter-mobile station direct communication priority area 32 is widely reserved in the time axis direction in the uplink subframe. As in the case of transmission / reception timing, many OFDM symbols must be modulated and demodulated during direct communication between mobile stations. In general, in OFDM, the amount of signal processing is large, and power consumption accompanying signal processing increases in proportion to the number of symbols to be processed. For this reason, in particular, there is a restriction on the continuous standby time like a handset. In some mobile station apparatuses, there is a problem that the continuous standby time is reduced to an impractical level.
Therefore, in this embodiment, an OFDMA-TDD communication method is realized in which the power consumption of the mobile station apparatus can be suppressed by reducing the power consumption during direct communication between mobile stations.

(Description of this example)
For example, when the duplex method is the TDD method, a part of the uplink channel is allocated for direct communication between mobile stations, so that the mobile station device and other mobile station devices can be connected without going through the base station device. It is possible to communicate directly between.

FIG. 1 shows an example of a frame configuration and an example of transmission / reception timing of an OFDMA-TDD communication system according to an embodiment of the present invention. The horizontal direction represents the OFDM symbol direction (time direction), and the vertical direction represents the subcarrier direction (frequency direction).
The frame of this example is provided with the region of the synchronization signal 21, the downlink control region 22, and the downlink data region 23 as the downlink subframe region, and the uplink control region 24, the uplink data region 23 as the uplink subframe region. A data area 25 and a direct communication priority symbol 26 between mobile stations are provided.

In this example, for example, the inter-mobile station direct communication priority symbol 26 is included in the uplink data area 25 and is handled in the same manner as the uplink data area 25 when not assigned as the inter-mobile station direct communication priority symbol 26. .
In this example, it is considered that the direct communication priority symbol 26 between mobile stations is included in the uplink data area 25. As another way of understanding, these areas 25 and 26 are regarded as separate areas. However, in any way, it is substantially the same.

Here, for convenience of explanation, in FIG. 1, the same parts 21 to 24 as those shown in FIG.
In this example, the process (sequence) until the mobile station apparatus is connected to the base station apparatus is the same as that in the OFDMA-TDD communication system according to the conventional example described with reference to FIG. Since there is, explanation is omitted.

In this example, as shown in FIG. 1, the inter-mobile station direct communication priority symbol 26 is allocated to the uplink subframe so that the number of OFDMA symbols used in the inter-mobile station direct communication is minimized. For this reason, it is not necessary to demodulate the OFDMA symbol belonging to the uplink data area 25. Therefore, in the frame configuration of this example, as in the transmission / reception timing shown in FIG. The modulation / demodulation process can be stopped in (except for), and the power consumption accompanying the signal processing can be reduced.
In this example, the direct communication priority symbol 26 between mobile stations is allocated to all subcarriers at the end position in the OFDM symbol direction of the uplink data region 25.

  Next, assuming that all the mobile station devices connected to the base station device are in communication with the base station device (hereinafter also referred to as base station communication) as an initial state, the mobile station device A and the mobile station device are in that state. After B shifts to the direct communication mode between mobile stations and performs direct communication between the mobile stations between the mobile station apparatus A and the mobile station apparatus B, the mobile station apparatus A and the mobile station apparatus B again return to normal base stations. A sequence for returning to the communication mode will be described.

FIG. 2 shows an example of such a sequence.
In the initial state, since there is no mobile station apparatus that performs direct communication between mobile stations in the communication area of the base station apparatus, the inter-mobile station direct communication priority symbol 26 is a part of the uplink data area 25. It is assigned to the user (that is, it is treated as the upstream data area 25). In this case, the frame configuration of this example is equivalent to the frame configuration according to the conventional example shown in FIG.

From this state, the mobile station apparatus A issues a direct inter-mobile station communication request to the base station apparatus using the uplink control area 24 in order to shift to the inter-mobile station direct communication mode (process T1).
Here, the direct communication request between mobile stations is a signal for notifying the base station apparatus from the mobile station apparatus that the mobile station direct communication mode is to be shifted. At this time, if a radio frame area used for direct communication between mobile stations is not secured, an area securing process is performed in response to this request.

  That is, the base station device receives the inter-mobile station direct communication request from the mobile station device A, secures the inter-mobile station direct communication priority symbol 26 exclusively for the inter-mobile station direct communication, and performs other base station communication. Only the uplink data area 25 (area not including the direct communication priority symbol 26 between mobile stations) is allocated to the apparatus. Further, the base station apparatus returns a direct communication request response between mobile stations to the mobile station apparatus A using the downlink control region 22 (process T2), and further permits direct communication between the mobile stations to the mobile station apparatus A in subsequent frames. Is output every frame (process T3, process T12), and the mobile station apparatus A can perform the direct communication between the mobile stations in the frame that has received the direct communication permission between the mobile stations.

Here, the direct communication request response between mobile stations is a signal for notifying the mobile station apparatus from the base station apparatus that the request from the mobile station apparatus has been correctly processed. With this notification, the mobile station apparatus shifts to the direct communication mode between mobile stations.
The mobile station direct communication permission is a signal for confirming that the mobile station apparatus can correctly receive the transmission signal from the base station apparatus (in a synchronized state). Sent.
In addition, the information regarding the area reserved for direct communication between mobile stations (for example, information on whether or not the area is reserved, or in which area is reserved) uses the downlink control area 22. Then, every frame is transmitted from the base station apparatus to the mobile station apparatus in the direct communication mode between mobile stations.

Next, the mobile station apparatus B also issues a direct inter-mobile station communication request to the base station apparatus using the uplink control area 24 in order to shift to the inter-mobile station direct communication mode (process T4).
The base station apparatus receives a request for direct communication between mobile stations from the mobile station apparatus B, but does not secure a new area because the mobile station direct communication priority symbol 26 is already reserved exclusively for direct communication between mobile stations. Then, the mobile station apparatus B is returned to the mobile station apparatus B using the downlink control area 22 (process T5), and the mobile station apparatus B is transmitted to the mobile station apparatus B using the downlink control area 22 in subsequent frames. The direct communication permission is output for each frame (process T6, process T9), so that the mobile station apparatus B can perform the direct communication between the mobile stations in the frame that has received the direct communication permission between the mobile stations.

At this stage, the mobile station apparatus A and the mobile station apparatus B share the inter-mobile station direct communication priority symbol 26 and perform, for example, voice communication or data communication by press talk without going through the base station apparatus. (Process T7, process T8).
After the direct communication between the mobile station device A and the mobile station device B is completed, for example, the mobile station device B uses the uplink control area 24 to transmit the base station device to the base station communication mode. A station communication request is issued (process T10).
The base station device receives the base station communication request from the mobile station device B, cancels the direct communication mode between the mobile stations of the mobile station device B, and communicates with the mobile station device B using the downlink control region 22. A request response is returned (process T11). Then, the mobile station apparatus B that has received this base station communication request response shifts to the base station communication mode, and in the subsequent frames, the uplink data area 25 (the area not including the inter-mobile station direct communication priority symbol 26 at this stage) ) Will be assigned.

Thereafter, for example, the mobile station apparatus A also issues a base station communication request to the base station apparatus using the uplink control region 24 in order to shift to the base station communication mode (process T13).
Upon receiving the base station communication request from the mobile station device A, the base station device cancels the direct communication mode between the mobile stations of the mobile station device A, and uses the downlink control area 22 to communicate with the mobile station device A through the base station communication. A request response is returned (process T14). In addition, since there is no mobile station apparatus that performs direct communication between mobile stations at this time, the base station apparatus reallocates the direct communication priority symbol 26 between mobile stations as a part of the uplink data area 25 (direct communication between mobile stations). Release of priority symbol 26).
Upon receiving the base station communication request response, the mobile station apparatus A shifts to the base station communication mode, and the uplink data area 25 (area including the direct communication priority symbol 26 between mobile stations) is assigned in the subsequent frames. become.

  Thus, in the frame configuration of this example, only when there is a mobile station apparatus that performs direct communication between mobile stations, a part of the uplink data area 25 is dedicated to the direct communication between mobile stations (direct communication priority symbol between mobile stations). 26), and by ensuring all of the uplink data area 25 in base station communication otherwise, direct communication between mobile stations can be realized while suppressing a decrease in transmission efficiency. In addition, since the mobile station device maintains synchronization by transmitting / receiving control signals to / from the base station device even in the direct communication mode between mobile stations, the mobile station device moves without causing intersymbol interference or intercarrier interference. Direct communication between stations can be realized.

Here, in this example, the one-to-one communication between the mobile station device A and the mobile station device B has been described as an example. However, for example, one-to-many communication may be performed, and the secured direct How to use the communication area may be variously used depending on the mode of the system.
As an example, a mode in which a certain terminal device (for example, a mobile station device or another communication device) communicates with all of the mobile station devices in the direct communication mode between mobile stations can be used in one-to-many manner. As an example, it is possible to use a mode in which a plurality of mobile station apparatuses are grouped in advance and communication is performed with a mobile station apparatus in a direct communication mode between mobile stations in a specific group.

In addition, for example, information that a certain mobile station device has shifted to the direct communication mode between mobile stations, or an area for direct communication between mobile stations (direct communication priority symbol 26 between mobile stations) is secured for a certain mobile station device. It is also possible to use a mode in which information such as information is notified from the base station apparatus to another mobile station apparatus. In this case, the mobile station apparatus that has received such notification performs, for example, a determination to shift to the direct communication mode between mobile stations based on the information.
In addition, since it is not always necessary for another mobile station device to grasp information that a certain mobile station device has already shifted to the direct communication mode between mobile stations, a mode in which such information is not reported is used. May be.

  As described above, in this example, in the communication frame in the OFDMA-TDD wireless communication system including the base station device and the mobile station device, the synchronization signal 21 for the mobile station device to synchronize the frame with the base station device. An area, a downlink control area 22 for transmitting a control signal from the base station apparatus to the mobile station apparatus, a downlink data area 23 for transmitting data from the base station apparatus to the mobile station apparatus, and a base station from the mobile station apparatus An uplink control area 24 for sending a control signal to the apparatus, an uplink data area 25 for sending data from the mobile station apparatus to the base station apparatus, and mobile station apparatuses directly communicating with each other without passing through the base station apparatus If there is a mobile station device to be used, it is used to transmit and receive data between the mobile station devices. With between mobile station direct communication priority symbol 26 that is used to send data to the service unit.

  Specifically, the wireless communication system of this example is an OFDMA-TDD communication system communication system including a base station device and a plurality of mobile station devices, and all mobile station devices communicate with only the base station device. When performing, the entire uplink data area 25 of the radio frame is used for communication with the base station device, whereas when performing direct communication between the mobile station devices without going through the base station device, the base station device moves In response to a request from the station apparatus, a part of the uplink data area 25 is allocated as a communication area for direct communication between mobile stations (direct communication priority symbol 26 between mobile stations), and the mobile station apparatus allocates the allocated communication area. To communicate directly. Thereby, in the mobile station apparatus, it is possible to prevent intersymbol interference and intercarrier interference while securing the time and frequency synchronization state with the base station apparatus while performing direct communication.

  Therefore, in the radio communication system of the OFDMA-TDD communication system of this example, a part of the uplink data area 25 is reserved exclusively for direct communication between mobile stations only when there is a mobile station device that performs direct communication between mobile stations. In other cases, the entire uplink data area 25 is ensured for base station communication, thereby suppressing a decrease in transmission efficiency and maintaining the synchronization between the mobile station apparatus and the base station apparatus without moving the communication quality. Direct communication between stations can be realized.

  Thus, in this example, when all the mobile station devices perform transmission / reception with the base station device while maintaining synchronization between the mobile station device and the base station device, all of the uplink data area 25 is exchanged with the base station device. When there is a mobile station device that secures communication and performs communication without going through the base station device, a part of the uplink data region 25 is dedicated to the (other) mobile station device from the mobile station device. For example, even when a plurality of mobile station apparatuses have a function of performing direct communication without going through the base station apparatus, it is possible to prevent transmission efficiency and communication quality from being deteriorated.

Further, in the base station apparatus of this example, a channel for performing direct communication between mobile stations (in this example, the communication area of the direct communication priority symbol 26 between mobile stations) is assigned so that the number of OFDMA symbols is minimized.
In this example, a mobile station device that performs direct communication between mobile stations using the direct communication region between mobile stations (in this example, the communication region of the direct communication priority symbol 26 between mobile stations) transmits from the base station device. Only the synchronization signal 21 and the downlink control region 22 signal and the direct communication region signal between the mobile stations are demodulated, and the other OFDMA symbols are not demodulated (the transmission / reception processing sequence shown in FIG. 1 is performed). reference.).

  Therefore, in the wireless communication system of this example, since the communication area used for direct communication between mobile stations is allocated so that the number of OFDMA symbols is minimized, the number of OFDMA symbols that require modulation / demodulation processing is reduced and the signal is reduced. Power consumption accompanying processing can be reduced. For example, in a mobile station apparatus, while performing direct communication, while maintaining a time / frequency synchronization state with a base station apparatus, inter-symbol interference and inter-carrier interference are prevented, and the number of OFDMA symbols subjected to modulation / demodulation processing is reduced. It is possible to reduce the power consumption in the own device (mobile station device).

  Thus, in this example, power consumption can be reduced by minimizing OFDM symbols that require modulation / demodulation during direct communication between mobile stations, and stopping signal processing in OFDM symbols that do not require modulation / demodulation. Direct communication between mobile stations with reduced power consumption of the mobile station apparatus can be realized. For example, in the OFDMA-TDD communication system, it is possible to suppress a decrease in continuous standby time of the mobile station device by reducing power consumption during direct communication between mobile stations.

  In the wireless communication system of this example, the mobile station device sends a request for direct communication between the mobile station devices without passing through the base station device (in this example, a direct communication request between mobile stations) to the base station device. The base station apparatus includes an uplink data area (uplink data area 25 in this example) included in a radio frame (in this example, shown in FIG. 1). When all mobile station apparatuses communicate only with the base station apparatus, the mobile station apparatus controls so that all of the uplink data area is used for communication between the mobile station apparatus and the base station apparatus. A part of the uplink data area so that the number of OFDMA symbols in the communication area for direct communication between mobile station apparatuses is minimized when a request for direct communication between mobile station apparatuses is received from (In this example, move Frame area control means for controlling the direct communication priority symbol 26) to be assigned as a communication area for direct communication between mobile station apparatuses, and the mobile station apparatus uses the mobile station apparatus by the base station apparatus. Direct communication means for performing direct communication between mobile station apparatuses using a communication area assigned as a communication area for performing direct communication between the mobile station apparatuses.

Here, the configuration of the system and apparatus according to the present invention is not necessarily limited to the configuration described above, and various configurations may be used. The present invention can also be provided as, for example, a method or method for executing the processing according to the present invention, a program for realizing such a method or method, or a recording medium for recording the program. It is also possible to provide various systems and devices.
The application field of the present invention is not necessarily limited to the above-described fields, and the present invention can be applied to various fields.
In addition, as various processes performed in the system and apparatus according to the present invention, for example, the processor executes a control program stored in a ROM (Read Only Memory) in hardware resources including a processor and a memory. A controlled configuration may be used, and for example, each functional unit for executing the processing may be configured as an independent hardware circuit.
The present invention can also be understood as a computer-readable recording medium such as a floppy (registered trademark) disk or a CD (Compact Disc) -ROM storing the control program, and the program (itself). The processing according to the present invention can be performed by inputting the program from the recording medium to the computer and causing the processor to execute the program.

  1 .... Base station device, 2 .... Communication area, 11-14..Mobile station device, 21..Synchronization signal, 22..Downlink control area, 23..Downlink data area, 24..Uplink control area, 25. 31, 41... Uplink data area 26.. Mobile station direct communication priority symbol 32 32 Mobile station direct communication priority area

Claims (1)

In a radio communication system of an OFDMA-TDD communication system having a base station apparatus and a plurality of mobile station apparatuses,
The mobile station apparatus includes request transmission means for transmitting a request for performing direct communication between mobile station apparatuses to the base station apparatus without going through the base station apparatus,
When all the mobile station devices communicate only with the base station device with respect to the uplink data region included in the radio frame, the base station device has all the uplink data regions with the mobile station device and the base station device. When a request for direct communication between mobile station apparatuses is received from the mobile station apparatus, the OFDMA symbol in the communication area for direct communication between the mobile station apparatuses is controlled. Frame area control means for controlling to allocate a part of the uplink data area as a communication area for direct communication between mobile station devices so that the number is minimized,
The mobile station device includes direct communication means for performing direct communication between mobile station devices using a communication region assigned as a communication region for performing direct communication between mobile station devices by the base station device,
A wireless communication system.

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