JP2008244871A - Communication apparatus and communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To avoid communication quality from being deteriorated, by enabling a communication destination device to more surely receive user data retransmitted by a communication apparatus in a radio communication system wherein the device of a communication destination periodically receives notification information notified by the communication apparatus. <P>SOLUTION: A radio base station 4A according to the present invention transmits, to a radio communication terminal, notification information to be notified within a control area and user data of a specified transmission destination in a radio communication system to which an automatic retransmission control (ARQ) is applied. The radio base station 4A comprises: a synchronization error detection section 15 for detecting a notification information period that is a period during which the radio communication terminal receives the notification information; and a transmission processing section 13 for transmitting the user data to the radio communication terminal during a period different from the notification information period. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a communication apparatus and a communication method for transmitting broadcast information to be notified in a control area and user data whose transmission destination is specified to a communication destination apparatus in a wireless communication system to which automatic retransmission control is applied.

  As one of the wireless communication systems, a time division multiple access / time division duplex (TDMA-TDD) system used in PHS and iBurst (registered trademark) is known (for example, see Non-Patent Documents 1 and 2). ).

  In such a TDMA-TDD scheme, a radio base station broadcasts notification information used for establishing communication with a wireless communication terminal in a cover area. The wireless communication terminal performs “base station monitoring”, which is an operation of periodically receiving broadcast information from a wireless base station that is a candidate for the next connection destination.

  Further, since the environment of the wireless propagation path between the wireless communication terminal and the wireless base station is likely to fluctuate, packets storing user data in the wireless propagation path may be lost. For this reason, in a wireless communication system, automatic retransmission control for retransmitting a packet lost in a wireless propagation path is widely used.

  In SRL-ARQ (Selective Repeat-Automatic Repeat reQuest), which is one of automatic retransmission controls, when a wireless communication terminal detects a loss of a packet, the wireless communication terminal requests the wireless base station to retransmit the lost packet (for example, Patent Literature 1). 1). When receiving the retransmission request for the lost packet, the wireless base station transmits the packet to the wireless communication terminal. Thereby, the lost packet is immediately retransmitted to the wireless communication terminal.

The wireless communication terminal accumulates each received packet after requesting retransmission of the lost packet until receiving the retransmitted packet. Further, when the wireless communication terminal succeeds in receiving the retransmitted packet, the wireless communication terminal collectively sends the retransmitted packet and the accumulated packet to the upper application.
“Second-generation cordless telephone system”, ARIB STD-28, The Japan Radio Industry Association, December 2003 “High Capacity-Spatial Division Multiple Access (HC-SDMA)”, WTSC-2005-032, ATIS / ANSI Japanese Patent Laying-Open No. 2005-295190 (page 8, FIG. 3)

  By the way, since a wireless communication terminal normally includes only one receiving device, it cannot receive a plurality of logical channels simultaneously. However, a logical channel that transmits user data is different from a logical channel that transmits broadcast information.

  Therefore, the wireless communication terminal cannot receive user data and broadcast information at the same time. For this reason, a wireless communication terminal including only one receiving apparatus generally receives broadcast information with priority over user data.

  That is, even if the packet is retransmitted by the radio base station, if the reception timing of the retransmitted packet overlaps with the base station monitoring timing, the radio communication terminal cannot receive the retransmitted packet.

  Since the base station monitoring is periodically performed, if the reception period of the retransmitted packet matches the period of the base station monitoring, the wireless communication terminal cannot receive the retransmitted packet for a long time. Become. For this reason, there is a problem that packets continue to be accumulated in a lower layer (wireless layer) in the wireless communication terminal.

  In particular, when a wireless communication terminal is executing an application with a high real-time property such as VoIP (Voice over Internet Protocol), if a large number of packets stagnate in a lower layer, audio reproduction is delayed. Furthermore, since a packet held for a certain time or more is discarded in a lower layer, the voice quality (communication quality) is significantly deteriorated.

  In view of the above problems, the present invention more reliably receives user data retransmitted by the communication destination device in the wireless communication system in which the communication destination device periodically receives broadcast information notified by the communication device. It is an object of the present invention to provide a communication device and a communication method that can be used and that can avoid deterioration in communication quality.

  In order to achieve the above object, according to a first aspect of the present invention, in a wireless communication system to which automatic retransmission control (ARQ) is applied, broadcast information to be broadcast in a control area (cell) and a transmission destination are specified. A communication device (wireless base station 4A) that transmits the user data to the communication destination device (wireless communication terminal 1), and detects a broadcast information period that is a period during which the communication destination device receives the broadcast information. (Synchronization error detection unit 15 or negotiation execution unit 150) and a transmission unit (transmission processing unit 13, transmission timing) that transmits user data to the communication destination device in a period different from the broadcast information period detected by the detection unit. And a control unit 16).

  According to such a feature, the transmission unit transmits user data to the communication destination device in a period different from the broadcast information period, so that the communication destination device can receive the user data more reliably and communication quality is deteriorated. Avoided.

  A second feature of the present invention relates to the first feature of the present invention, and is summarized in that the detection unit detects a period in which a radio signal from the communication destination device is interrupted as the notification information period.

  A third feature of the present invention relates to the second feature of the present invention, wherein a period during which user data is transmitted to the communication destination apparatus is longer than a period during which user data is received from the communication destination apparatus in one frame period. Later, when the broadcast information period is detected in a predetermined frame period, the transmission unit stops transmitting user data in the predetermined frame period, and in a frame period later than the predetermined frame period The gist is to transmit the user data whose transmission has been stopped to the communication destination device.

  A fourth feature of the present invention relates to the first feature of the present invention, wherein the detection unit transmits information indicating the notification information period by the negotiation, which is an operation of establishing a connection with the communication destination device. The main point is to obtain from the previous device.

  A fifth feature of the present invention relates to the fourth feature of the present invention, wherein the transmitting unit stops transmitting user data in a frame period corresponding to the broadcast information period, and a frame corresponding to the broadcast information period. The gist is to transmit the user data whose transmission has been stopped to the communication destination apparatus in a frame period after the period.

  A sixth feature of the present invention is a communication method for transmitting notification information to be notified in a control area and user data whose transmission destination is specified to a communication destination device in a wireless communication system to which automatic retransmission control is applied. The communication destination device receives user data in a step different from the notification information period detected in the step of detecting the notification information period, which is a period in which the communication destination device receives the notification information, and in the detecting step. And a step of transmitting.

  Advantageous Effects of Invention According to the present invention, in a wireless communication system in which a communication destination device periodically receives notification information notified by a communication device, the communication destination device can more reliably receive user data retransmitted by the communication device. It is possible to provide a communication device and a communication method capable of avoiding quality degradation.

  Next, an embodiment of the present invention will be described with reference to the drawings. In the description of the drawings in the following embodiments, the same or similar parts are denoted by the same or similar reference numerals.

(1) Schematic Configuration of Radio Communication System First, the schematic configuration of the radio communication system according to the present embodiment will be described. In this embodiment, a radio communication system applied to VoIP will be described.

  FIG. 1 is a schematic configuration diagram of a wireless communication system according to the present embodiment. As shown in FIG. 1, the wireless communication system includes a wireless communication terminal 1, a client PC 2, a user interface device 3, wireless base stations 4A to 4H, a PDSN (Packet Data Serving Node) 5, the Internet 6, and a SIP (Session Initiation Protocol). A telephone 7 and a SIP server 8 are provided.

  The wireless communication terminal 1 is connected to the wireless base station 4A and performs wireless communication with the wireless base station 4A. The radio base stations 4 </ b> B to 4 </ b> H are connection destination candidate base stations for the radio communication terminal 1.

  The radio communication terminal 1 monitors broadcast information broadcast by the radio base stations 4A to 4H (hereinafter, “base station monitoring”) while communicating with the radio base station 4A. By performing base station monitoring, the wireless communication terminal 1 maintains a synchronization state with the wireless base stations 4A to 4H, or searches for a wireless base station with better conditions (for example, a radio wave state).

  The radio communication terminal 1 receives the broadcast information from the radio base stations 4A to 4H with priority over the reception of audio data from the radio base station 4A. That is, the radio communication terminal 1 cannot receive the audio data from the radio base station 4A in the frame period for receiving the broadcast information.

  In the present embodiment, wireless communication between the wireless communication terminal 1 and the wireless base stations 4A to 4H is executed according to the iBurst standard. That is, the wireless communication terminal 1 and the wireless base stations 4A to 4H have a configuration corresponding to the iBurst standard. In the present embodiment, the wireless communication terminal 1 is a fixed wireless communication terminal.

  The client PC 2 is a host device of the wireless communication terminal 1 and executes a VoIP application. The user interface device 3 includes a microphone, a speaker, a keypad, and the like, and functions as an interface with the user.

  The radio base stations 4A to 4H transmit or receive user data with a connected radio communication terminal. In addition, the radio base stations 4A to 4H periodically broadcast the broadcast information in the own cell (control area) at different timings (frames).

  The PDSN 5 has a function of terminating an IP packet. The SIP telephone 7 performs voice communication with the client PC 2 via the Internet 6. The SIP server 8 executes call control of the SIP telephone 7 and the client PC 2 according to SIP (RFC3261 etc.).

(2) Configuration of Radio Base Station Next, the configuration of the radio base station 4A will be described. FIG. 2 is a functional block diagram of the radio base station 4A. Hereinafter, portions related to the present invention will be mainly described.

  As shown in FIG. 2, the radio base station 4A includes an antenna 10, a radio communication unit 11, a reception processing unit 12, a transmission processing unit 13, a retransmission control unit 14, a sync error detection unit 15, and a transmission timing control unit 16. .

  The wireless communication unit 11 transmits and receives wireless signals via the antenna 10. The wireless communication unit 11 includes an LNA, a power amplifier, an up converter, a down converter, and the like.

  The reception processing unit 12 performs demodulation and error detection on the broadcast information or audio data received by the wireless communication unit 11. Further, the reception processing unit 12 notifies the retransmission control unit 14 whether or not an error has been detected in the audio data.

  If an error is detected in the audio data, the retransmission control unit 14 generates a retransmission request for requesting retransmission of the audio data. In addition, the retransmission control unit 14 adds a sequence number to the audio data to be transmitted to the wireless communication terminal 1. In response to a retransmission request from the wireless communication terminal 1, the retransmission control unit 14 retransmits the audio data requested for retransmission to the wireless communication terminal 1.

  The sync error detection unit 15 detects that the radio signal from the radio communication terminal 1 has been interrupted (hereinafter, “sync error”). A sync error means that the connection is disconnected in the physical layer, but the connection is maintained in a layer higher than the physical layer.

  The transmission timing control unit 16 controls the timing for transmitting audio data to the wireless communication terminal 1 in accordance with the detection result of the sync error by the sync error detection unit 15. In the present embodiment, the transmission timing control unit 16 determines that the wireless communication terminal 1 is performing base station monitoring in the frame period in which the sync error is detected.

  The transmission processing unit 13 converts audio data to be transmitted to the wireless communication terminal 1 into a predetermined packet format, and transmits the audio data to the wireless communication terminal 1 under the control of the transmission timing control unit 16.

(3) Frame Configuration (3.1) Super Frame Configuration FIG. 3 is a diagram illustrating a configuration of a super frame used for communication between the radio communication terminal 1 and the radio base stations 4A to 4H according to the present embodiment. . As shown in FIG. 3, the super frame is composed of 20 frames.

  The notification information T is information for notifying the wireless communication terminal 1 of timing information, and is notified by all of the wireless base stations 4A to 4H. By receiving the notification information T, the wireless communication terminal 1 performs resynchronization of synchronization shifted due to movement or clock error.

  On the other hand, the broadcast information B0 to B7 is used for determining a connection destination base station in the wireless communication terminal 1. Specifically, the broadcast information B0 is broadcast by the radio base station 4A and includes information on the radio base station 4A. The broadcast information B1 is broadcast by the radio base station 4B and includes information on the radio base station 4B. Similarly, the radio base stations 4C to 4H individually notify the notification information B2 to B7.

  The wireless communication terminal 1 receives the notification information B0 to B7, collects and compares the wireless quality and contents, and switches the connection destination base station or maintains the connection with the currently connected wireless base station 4A. Determine what to do. In the period of the notification information T to B7, the notification information is notified at a rate of once every two frames.

(3.2) Frame Configuration FIG. 4 is a diagram showing a frame configuration in the superframe shown in FIG.

  As shown in FIG. 4, the frame is logically divided and constitutes three TDMA-TDD slots each for uplink and downlink.

  Uplink slot 0 and downlink slot 0 are paired and used for one application (terminal). Similarly, uplink slot 1 and downlink slot 1 are paired, and uplink slot 2 and downlink slot 2 are paired.

  In the minimum configuration of the iBurst system, eight frequency bands are used as physical channels. Therefore, when viewed from the wireless communication terminal 1, 8 physical channels × 3 slots = 24 logical channels are recognized.

  The wireless communication terminal 1 performs base station monitoring by performing reception on an arbitrarily defined logical channel (for example, downlink slot 0 of a certain physical channel) at the above-described timings T and B0 to B7.

(4) Operation of Radio Communication System Next, operations of the radio communication terminal 1 and the radio base station 4A described above will be described.

(4.1) Operation of Radio Base Station FIG. 5 is a flowchart showing the operation of the radio base station 4A.

  FIG. 5 shows the operation of the radio base station 4A in one frame period. Here, a case will be described in which the radio communication terminal 1 and the radio base station 4A communicate using the uplink slot 1 and the downlink slot 1 shown in FIG.

  In step S101, the reception processing unit 12 performs a reception process. Specifically, a radio signal from the radio communication terminal 1 is received during the period of the uplink slot 1 in FIG. Here, the sync error detection unit 15 determines that a sync error has been detected when a radio signal cannot be received from the radio communication terminal 1.

  In step S102, the transmission timing control unit 16 determines whether or not a sync error has been detected in step S101. If a sync error is detected in step S101, the process proceeds to step S103. If no sync error has occurred in step S101, the process proceeds to step S104.

  In step S103, the transmission processing unit 13 stores the sequence number of the audio data to be transmitted. Then, the transmission processing unit 13 stops the voice data transmission processing in the period of the downlink slot 1 of FIG.

  On the other hand, in step S104, the transmission processing unit 13 determines whether or not a sync error has been detected in the previous (immediately preceding) frame period. If a sync error is detected in the previous frame period, the process proceeds to step S105. If no sync error is detected in the previous frame period, the process proceeds to step S106.

  In step S105, the transmission processing unit 13 acquires audio data corresponding to the sequence number saved in the previous frame period as audio data to be transmitted.

  In step S106, the transmission processing unit 13 transmits the audio data to be transmitted in the period of the downlink slot 1 in FIG.

(4.2) Operations of Radio Communication Terminal and Radio Base Station FIG. 6 is a sequence diagram showing operations of the radio communication terminal 1 and the radio base station 4A.

  In FIG. 6, it is assumed that the wireless communication terminal 1 receives audio data in a frame period in which broadcast information is not received. In addition, loss of voice data does not occur in the wireless propagation path between the wireless communication terminal 1 and the wireless base station 4A.

 At a time prior to step S211, the radio base station 4A transmits the audio data # 0 to # 3 to the radio communication terminal 1.

  In step S221, the radio communication terminal 1 performs base station monitoring. In order to execute the base station monitoring, the radio communication terminal 1 cannot receive the voice data # 2 transmitted by the radio base station 4A in the frame period corresponding to step S221.

  In step S222, the radio communication terminal 1 receives the audio data # 3 transmitted from the radio base station 4A. At this time, since the wireless communication terminal 1 has not received the audio data # 2, the received audio data # 3 is stored in a buffer in the wireless communication terminal 1. In step S223, the radio communication terminal 1 performs base station monitoring.

  In step S224, the radio communication terminal 1 receives the audio data # 4 transmitted from the radio base station 4A. Since the wireless communication terminal 1 cannot receive the audio data # 2, the received audio data # 4 is stored in a buffer in the wireless communication terminal 1.

  In step S211, the radio base station 4A detects a sync error due to the base station monitoring being performed by the radio communication terminal 1 in step S221. When detecting the sync error, the radio base station 4A delays the retransmission of the audio data # 2 until the frame period next to the frame period in which the sync error is detected.

  In step S212, the radio base station 4A retransmits the voice data # 2 that has been retransmitted in step S211 to the radio communication terminal 1.

  In step S213, the radio base station 4A detects a sync error caused by the radio communication terminal 1 performing base station monitoring in step S223. When detecting the sync error, the radio base station 4A delays the transmission of the audio data # 5 until the frame period next to the frame period in which the sync error is detected.

  In step S214, the radio base station 4A retransmits the audio data # 5 whose transmission has been stopped in step S213 to the radio communication terminal 1.

  In step S226, the radio communication terminal 1 receives the audio data # 2 retransmitted by the radio base station 4A in step S212. As a result, in the wireless communication terminal 1, the order arrangement of the audio data # 2 to # 4 is completed, and the audio data # 2 to # 4 are collectively delivered to the upper application (client PC 2).

  In step S227, the radio communication terminal 1 performs base station monitoring.

  In step S228, the wireless communication terminal 1 receives the audio data # 5 transmitted by the wireless base station 4A in step S214. Further, the wireless communication terminal 1 passes the received audio data # 5 to the upper application.

(5) Comparative example Next, a comparative example is given and the effect acquired by the radio | wireless communication method which concerns on this embodiment is clarified. FIG. 7 is a diagram for explaining the timing of base station monitoring in this comparative example.

  As shown in FIG. 7, every other audio data transmitted from the radio base station to the radio communication terminal is missing. The radio base station retransmits the audio data that could not receive Ack from the radio communication terminal, but the retransmitted packet is further missing. As a result, the audio data # 2 is retransmitted three times, and the audio data # 4 is retransmitted twice.

  Eventually, the retransmission of the audio data # 2 and the audio data # 4 is completed, but the order alignment is not completed in the wireless communication terminal until the retransmission of the audio data # 2 is successful. For this reason, when each voice data (# 3, # 4, # 5, # 6, # 7, # 8, # 9) that has arrived at the wireless communication terminal first is stagnant and voice data # 2 arrives. Then, the audio data # 2 to # 9 are collectively delivered to the upper application. When such a large number of packets are delayed in the lower layer, the audio reproduction is delayed in the upper application.

(6) Operation / Effect According to the present embodiment, the radio base station 4A performs radio communication in a frame period in which a sync error is detected, that is, in a frame period different from the frame period in which the radio communication terminal 1 executes base station monitoring. Audio data is transmitted to the communication terminal 1. Therefore, the radio communication terminal 1 can receive the audio data more reliably, and the deterioration of the audio quality is avoided.

  In addition, when a sync error is detected in a certain frame period, the radio base station 4A stops the transmission of the audio data in the frame period, and the audio data in which the transmission is stopped in the next frame period of the frame period Is transmitted to the wireless communication terminal 1.

  The cycle in which the wireless communication terminal 1 performs base station monitoring is once every two frames. For this reason, the radio communication terminal 1 can receive the audio data more reliably by transmitting the audio data with a delay of one frame period from the frame period in which the radio base station 4A executes the base station monitoring.

  Further, since the radio base station 4A does not transmit voice data to the radio communication terminal 1 during the frame period in which the radio communication terminal 1 executes base station monitoring, the processing load and power consumption required for data transmission of the radio base station 4A are reduced. Reduction is possible, and waste of radio resources is avoided.

[Example of change]
In the above-described embodiment, the configuration in which the radio base station 4A determines that the radio communication terminal 1 is performing base station monitoring in the frame period in which the sync error is detected has been described.

  In this modified example, the radio base station 4A determines a period during which the radio communication terminal 1 executes base station monitoring by negotiation, which is an operation for establishing a connection with the radio communication terminal 1, without detecting a sync error. .

(1) Configuration of Radio Base Station FIG. 8 is a functional block diagram of the radio base station 4A according to this modification. As shown in FIG. 8, the radio base station 4A includes a negotiation execution unit 150 instead of the sync error detection unit 15 of FIG. Other configurations are the same as those in FIG.

  The negotiation execution unit 150 executes negotiation with the wireless communication terminal 1 at the time of initial connection such as when the wireless communication terminal 1 is powered on or at the time of handover when the wireless communication terminal 1 switches the connection destination wireless base station.

  Through the negotiation, a communication method (for example, a modulation method) used for communication between the wireless communication terminal 1 and the wireless base station 4A, a channel assigned to the wireless communication terminal 1, and the like are determined.

  In the present modification example, the negotiation executing unit 150 acquires information (hereinafter, “monitor timing information”) related to the timing at which the wireless communication terminal 1 executes base station monitoring from the wireless communication terminal 1 when executing the negotiation.

  As such monitor timing information, information on the frame number at which the wireless communication terminal 1 executes base station monitoring is used. Alternatively, information on a frame number to be executed first, information on a cycle in which the wireless communication terminal 1 executes base station monitoring, and the like are used.

  The transmission timing control unit 16 controls the transmission timing of data to be transmitted to the wireless communication terminal 1 according to the monitor timing information acquired by the negotiation execution unit 150.

  Specifically, the transmission timing control unit 16 determines whether or not the wireless communication terminal 1 performs base station monitoring in a certain frame period, as in the flowchart of FIG. Then, the transmission timing control unit 16 transmits the audio data to be transmitted with a delay until the next and subsequent frame periods in the frame period in which the wireless communication terminal 1 performs base station monitoring.

(2) Operation of Radio Communication System Next, operations of the radio communication terminal 1 and the radio base station 4A according to this modification will be described. FIG. 9 is a sequence diagram showing operations of the radio communication terminal 1 and the radio base station 4A according to this modification.

  In step S301, the radio communication terminal 1 transmits a channel allocation request for requesting channel allocation to the radio base station 4A.

  In step S302, the radio base station 4A notifies the assigned channel to the radio communication terminal 1 in response to the channel assignment request received in step S301.

  In step S303, the radio base station 4A transmits a monitor timing notification request for requesting notification of monitor timing information to the radio communication terminal 1.

  In step S304, the radio communication terminal 1 notifies the radio base station 4A of monitor timing information in response to the monitor timing notification request received in step S303.

(3) Action / Effect According to this modification, it is possible to obtain the same effect as that of the above-described embodiment. Further, since the radio base station 4A according to the present modification example can acquire in advance a frame period during which the radio communication terminal 1 executes base station monitoring, even in the first monitor timing period (see step S221 in FIG. 6). The transmission of voice data can be delayed.

[Other embodiments]
As mentioned above, although this invention was described by embodiment, it should not be understood that the description and drawing which form a part of this indication limit this invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  In the embodiment described above, the wireless communication system applied to voice communication by VoIP has been described. However, not only voice communication by VoIP but also an application using TCP / IP as a higher-level protocol is provided. The

  In the embodiment described above, the wireless communication terminal 1 is a fixed type. However, the wireless communication terminal 1 is not limited to a fixed type, and may be a portable wireless communication terminal.

  In the above-described embodiment, the wireless communication system conforming to the iBurst standard has been described. However, the wireless communication system is not limited to the iBurst standard, and may be a wireless communication system of another method using TDMA-TDD. Furthermore, as long as the wireless communication system is such that the wireless communication terminal periodically performs base station monitoring, the wireless communication system can be applied to other types of wireless communication systems that do not use TDMA-TDD.

  Thus, it should be understood that the present invention includes various embodiments and the like not described herein. Therefore, the present invention is limited only by the invention specifying matters in the scope of claims reasonable from this disclosure.

1 is a schematic configuration diagram of a radio communication system according to an embodiment of the present invention. It is a functional block diagram which shows the structure of the wireless base station which concerns on embodiment of this invention. It is a figure which shows the structure of the super frame which a radio | wireless communication terminal and radio base station which concern on embodiment of this invention use for communication. It is a figure which shows the structure of the flame | frame in the super frame shown in FIG. It is a flowchart which shows the operation | movement of the wireless base station which concerns on embodiment of this invention. It is a sequence diagram which shows operation | movement of the radio | wireless communication terminal and radio | wireless base station which concern on embodiment of this invention. It is a sequence diagram which shows operation | movement of the radio base station and radio | wireless communication terminal of the comparative example of embodiment of this invention. It is a functional block diagram which shows the structure of the wireless base station which concerns on the modification of embodiment of this invention. It is a sequence diagram which shows operation | movement of the radio | wireless communication terminal and radio | wireless base station which concern on the modification of embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Wireless communication terminal, 2 ... Client PC, 3 ... User interface apparatus, 4A-4H ... Wireless base station, 5 ... PDSN, 6 ... Internet, 7 ... SIP telephone, 8 ... SIP server, 10 ... Antenna, 11 ... Wireless Communication unit, 12 ... reception processing unit, 13 ... transmission processing unit, 14 ... retransmission control unit, 15 ... sync error detection unit, 16 ... transmission timing control unit, 150 ... negotiation execution unit

Claims (6)

In a wireless communication system to which automatic retransmission control is applied, it is a communication device that transmits notification information to be notified in a control area and user data with a specified transmission destination to a communication destination device,
A detection unit that detects a notification information period, which is a period during which the communication destination device receives the notification information;
A communication device comprising: a transmission unit that transmits user data to the communication destination device in a period different from the notification information period detected by the detection unit.   The communication device according to claim 1, wherein the detection unit detects a period in which a radio signal from the communication destination apparatus is interrupted as the notification information period. The period during which user data is transmitted to the communication destination apparatus is later than the period during which user data is received from the communication destination apparatus in one frame period.
The transmitter is
When the broadcast information period is detected in a predetermined frame period, transmission of user data is stopped in the predetermined frame period,
The communication apparatus according to claim 2, wherein the user data whose transmission has been stopped is transmitted to the communication destination apparatus in a frame period after the predetermined frame period.   The communication device according to claim 1, wherein the detection unit acquires information indicating the notification information period from the communication destination device by negotiation that is an operation of establishing a connection with the communication destination device. The transmitter is
Stop transmitting user data in a frame period corresponding to the broadcast information period,
The communication apparatus according to claim 4, wherein user data whose transmission has been stopped is transmitted to the communication destination apparatus in a frame period after a frame period corresponding to the broadcast information period. In a wireless communication system to which automatic retransmission control is applied, a communication method for transmitting notification information to be notified in a control area and user data for which a transmission destination is specified to a communication destination device,
Detecting a broadcast information period which is a period in which the communication destination device receives the broadcast information;
And a step of transmitting user data to the communication destination device in a period different from the notification information period detected in the detecting step.