WO2011145474A1

WO2011145474A1 - Transmitter apparatus, retransmission control method, and computer program

Info

Publication number: WO2011145474A1
Application number: PCT/JP2011/060721
Authority: WO
Inventors: 雅弘小松
Original assignee: 日本電気株式会社
Priority date: 2010-05-20
Filing date: 2011-05-10
Publication date: 2011-11-24

Abstract

The transfer of information related to ARQ retransmission of AM can be ensured, thereby preventing the throughput from degrading without occurrence of stall. A stay/poll information managing unit (115) determines whether to perform polling and also determines whether to transmit control information that is used to control the transmission. When it is determined that the polling is to be performed or when it is determined that the control information is to be transmitted, an ARQ retransmission determination transmission scheduler unit (121) refers to the transfer status as transmission parameters used to decide a scheme of transmitting data that is to be used to perform the polling or data that includes the control information, thereby selecting a transmission parameter that allows the transfer to be accomplished via a single transmission. This invention is applicable to radio base stations or mobile stations used in mobile communications.

Description

Transmission apparatus, retransmission control method, and computer program

The present invention relates to a transmission device, a retransmission control method, and a computer program.

A radio access network (E-UTRAN: Evolved Universal Terrestrial RAN) in an LTE (Long Term Evolution) mobile communication system is composed of a mobile station UE (User Equipment) and a radio base station eNB (E-UTRAN NodeB). In addition, communication is performed between the mobile station UE and the radio base station eNB via a radio link (RL: Radio Link).

The mobile station UE and the radio base station eNB are respectively a PDCP (Packet Data Convergence Protocol) sublayer, an RLC (Radio Link Control) sublayer, a MAC (Medium Access Control) sublayer, and a physical (PHY: Physics) layer. It is comprised so that it may make.

The transmission side device of the mobile station UE or the radio base station eNB transmits a radio signal in the radio unit by sequentially performing PDCP processing, RLC processing, MAC processing, and PHY processing on the transmitted data.

The RLC sublayer and the MAC sublayer in the conventional mobile communication system will be described with reference to FIG.

Here, there are TM (Transparent Mode), UM (Unknown mode), and AM (Acknowledged Mode) in the processing of the RLC sublayer, but only AM will be described below.

The RLC sublayer 301 and the MAC sublayer 302 are provided in the radio base station eNB, and the MAC sublayer 303 and the RLC sublayer 304 are provided in the mobile station UE.

Further, the RLC sublayer 301 includes an RLC SDU receiving unit 311, a transmission buffer 312, a retransmission buffer 313, a transmission control information storage unit 314, a staying information management unit 315, an RLC PDU (Protocol Data Unit) creation unit 316, and an RLC PDU transmission. A portion 317 is provided. The MAC sublayer 302 is also provided with a transmission scheduler 321, a MAC SDU reception unit 322, a MAC PDU creation unit 323, and a MAC PDU transmission unit 324.

The RLC SDU receiving unit 311 receives RLC SDU (Service Data Unit) from the PDCP sublayer of the radio base station eNB and stores it in the transmission buffer 312. The retention amounts of the transmission buffer 312, the retransmission buffer 313, and the transmission control information storage unit 314 are managed by the retention information management unit 315 and notified to the transmission scheduler 321 of the MAC sublayer 302.

The transmission scheduler 321 notified of the staying amount from a plurality of RBs (Radio Bearer) transmits the transmission parameters such as the number of transmission antennas, the modulation method, the coding rate, the wireless allocation bandwidth amount and the RB from the staying amount and the wireless transmission state. Determine the data quota. Then, the transmission scheduler 321 notifies the RLC PDU creation unit 316 of the RLC sublayer 301 of the data allocation amount. The RLC PDU creation unit 316 obtains transmission data from the transmission control information storage unit 314, the retransmission buffer 313, or the transmission buffer 312 and creates an RLC PDU. The RLC PDU creation unit 316 adds an RLC SN (Sequence Number) to the RLC header when creating the RLC PDU from the transmission data of the retransmission buffer 313 or the transmission buffer 312. When creating the RLC PDU from the transmission data of the retransmission buffer 313, the RLC PDU creation unit 316 uses the RLC SN of the same value as when newly transmitting. The RLC SN is incremented every time an RLC PDU is created from transmission data in the transmission buffer 312. Also, polling bits are arranged in the RLC header, and by setting this, it is possible to request the mobile station UE to transmit delivery confirmation information.

The created RLC PDU is stored in the retransmission buffer 313 in preparation for ARQ (Automatic Repeat reQuest) retransmission, and is transmitted from the RLC PDU transmission unit 317 to the MAC sublayer 302. The RLC PDU transmitted to the MAC sublayer 302 is received by the MAC SDU receiving unit 322 as a MAC SDU. The MAC PDU creation unit 323 creates a MAC PDU by multiplexing a plurality of MAC SDUs according to the transmission scheduler 321, and sends the MAC PDU together with the transmission parameters from the MAC PDU transmission unit 324 to the physical layer. The MAC PDU is transmitted via a radio link. It is transmitted to the mobile station UE.

The MAC sublayer 303 includes a MAC PDU reception unit 331, a MAC SDU creation unit 332, and a MAC SDU transmission unit 333. The RLC sublayer 304 includes an RLC PDU reception unit 341, a reception control information storage unit 342, and a reception buffer 343. , An RLC SDU creation unit 344 and an RLC SDU transmission unit 345 are provided.

The MAC PDU receiving unit 331 receives a MAC PDU transmitted from the radio base station eNB via radio from the physical layer of the mobile station UE. The MAC SDU creation unit 332 breaks down the MAC PDU into MAC SDUs, and the MAC SDU transmission unit 333 sends the MAC SDUs to the RLC sublayer 304. The RLC PDU receiving unit 341 receives the MAC SDU sent from the MAC sublayer 303 as an RLC PDU. Among the RLC PDUs, transmission control information that is delivery confirmation information of the radio base station eNB is stored in the reception control information storage unit 342, and a portion other than the transmission control information in the RLC PDU is stored in the reception buffer 343. The RLC SDU creation unit 344 acquires the RLC PDU from the reception buffer 343 and creates the RLC SDU. The created RLC SDU is transmitted to the PDCP sublayer of the mobile station UE by the RLC SDU transmitter 45.

Further, the RLC sublayer 304 includes an RLC SDU receiving unit 351, a transmission buffer 352, a retransmission buffer 353, a transmission control information storage unit 354, a staying information management unit 355, an RLC PDU creation unit 356, and an RLC PDU transmission unit 357. The MAC sublayer 303 includes a transmission scheduler 361, a MAC SDU reception unit 362, a MAC PDU creation unit 363, and a MAC PDU transmission unit 364.

When there is a request to report the reception status of the received RLC PDU or when it is necessary to report a reception status upon detecting a reception failure, the transmission control information storage unit 354 prepares to create transmission control information. Perform transmission control information when creating RLC PDUs. In the transmission control information, delivery confirmation information for notifying whether or not the mobile station UE has received the RLC PDU as ACK (ACKnowledgement) / NACK (Negative ACKnowledgement) using the RLC SN is stored.

The operation of the RLC sublayer 304 in data transmission from the mobile station UE to the radio base station eNB is the same as the operation of the RLC sublayer 301 in data transmission from the radio base station eNB to the mobile station UE.

The RLC SDU receiving unit 351 receives the RLC SDU from the PDCP sublayer of the mobile station UE and stores it in the transmission buffer 352. Retention amounts of the transmission buffer 352, the retransmission buffer 353, and the transmission control information storage unit 354 are managed by the retention information management unit 355 and notified to the transmission scheduler 361 of the MAC sublayer 303. The transmission scheduler 361 notified of the staying amount from the plurality of RBs notifies the radio base station eNB of the staying amount and requests radio assignment. Then, the transmission scheduler 361 determines the data allocation amount of each RB according to the radio allocation result from the radio base station eNB, and notifies the RLC PDU creation unit 356 of the RLC sublayer 304 of the data allocation amount. The RLC PDU creation unit 356 acquires transmission data from the transmission control information storage unit 354, the retransmission buffer 353, or the transmission buffer 352, and creates an RLC PDU. The created RLC PDU is stored in the retransmission buffer 353 in preparation for ARQ retransmission, and transmitted to the MAC sublayer 303 by the RLC PDU transmission unit 57. The RLC PDU transmitted to the MAC sublayer 303 passes through the MAC SDU reception unit 362, the MAC PDU creation unit 363, and the MAC PDU transmission unit 364, and is then transmitted to the radio base station eNB through a radio link.

Further, the MAC sublayer 302 of the radio base station eNB is provided with a MAC PDU reception unit 371, a MAC SDU creation unit 372, and a MAC SDU transmission unit 373. The RLC sublayer 301 includes an RLC PDU reception unit 381, reception control information. A storage unit 382, a reception buffer 383, an RLC SDU creation unit 384, and an RLC SDU transmission unit 385 are provided.

The MAC PDU receiving unit 371 receives the MAC PDU transmitted from the mobile station UE via radio from the physical layer of the radio base station eNB. The MAC SDU creation unit 372 decomposes the MAC PDU into MAC SDUs, and the MAC SDU transmission unit 373 sends the MAC SDUs to the RLC sublayer 301. The RLC PDU receiving unit 381 receives the MAC SDU sent from the MAC sublayer 302 as an RLC PDU. Among the RLC PDUs, the transmission control information that is the delivery confirmation information of the mobile station UE is stored in the reception control information storage unit 382 as reception control information, and the part other than the transmission control information of the RLC PDU is stored in the reception buffer 383. The The RLC SDU creation unit 384 acquires the RLC PDU from the reception buffer 383 and creates the RLC SDU. The created RLC SDU is transmitted to the PDCP sublayer of the radio base station eNB by the RLC SDU transmission unit 385.

The data in the retransmission buffer 313 is managed according to the received reception control information. The reception control information stored in the reception control information storage unit 382 indicates whether or not the RLC PDU has been received by the mobile station UE using the RLC SN. The reported RLC PDU is deleted from the retransmission buffer 313, and retransmission of the RLC PDU that has been NACK-reported as not received has been prepared.

In this case, the RLC PDU creation unit 316 acquires transmission data from the retransmission buffer 313 and creates an RLC PDU to be retransmitted.

In the retransmission control in the

RLC sublayer

301 or 304, a request to transmit delivery confirmation information is transmitted by transmitting data in which a polling bit is set to the opposite side, and delivery indicating whether the RLC PDU has been received from the opposite side. This is control for receiving confirmation information and retransmitting data that is NACK (not received) in the delivery confirmation information. Even if data with polling bit set is not sent to the other side, there is a function to send delivery confirmation information when data is not available for a certain period of time by referring to the RLC SN, but has RLC PDU been received from the other side? It is the same in that the acknowledgment information indicating whether or not is received and data that is NACK in the acknowledgment information is retransmitted (see Non-Patent Documents 1 and 2).

However, since the range of RLC SN that can be transmitted without performing delivery confirmation is limited, if the delivery confirmation information cannot be received for a long time, Window Stalling occurs and new data cannot be transmitted. For this reason, if the wireless transmission state is poor, a window stalling occurs due to a delay in delivery of data in which a polling bit for requesting transmission of acknowledgment information is set and a delay in reception of acknowledgment information, resulting in an increase in data throughput. It will go down.

In particular, when the delivery confirmation information cannot be received, it is necessary to wait for the delivery confirmation information to be transmitted from the opposite side. However, if the minimum transmission interval of the delivery confirmation information may be set, the delivery confirmation information Since it takes time to receive this, the throughput may continue to decrease.

Therefore, the present invention solves the above-described problem, that is, by reliably transmitting information related to ARQ retransmission of AM, thereby preventing a reduction in throughput without stalling, and a retransmission control method, and An object is to provide a computer program.

In order to solve the above problems, one aspect of the transmission device of the present invention is a transmission device that is used for mobile communication and retransmits a transmission unit by a number sequentially assigned to a transmission unit, and whether or not to perform polling. And determining means for determining whether or not to transmit control information for controlling transmission, and if it is determined to poll or if it is determined to transmit control information, data or control information for polling is included. As a transmission parameter for determining a data transmission method, reference is made to a transmission state, and selection means for selecting a transmission parameter that can be delivered in one transmission is provided.

Another aspect of the retransmission control method of the present invention is a retransmission control method for retransmitting a transmission unit using a number sequentially assigned to a transmission unit, which is used for mobile communication, and controls whether or not to perform polling and transmission. A determination step for determining whether or not to transmit control information for transmission, and if it is determined to poll or if it is determined to transmit control information, data for polling or transmission of data including control information As a transmission parameter for determining a system, a selection step for selecting a transmission parameter that can be delivered in one transmission with reference to a transmission state is included.

Furthermore, one aspect of the computer program of the present invention is to control whether or not to poll a computer that controls a transmission device that is used for mobile communication and retransmits a transmission unit according to a number sequentially assigned to the transmission unit. A determination step for determining whether or not to transmit control information for transmission, and if it is determined to poll or if it is determined to transmit control information, data for polling or transmission of data including control information As a transmission parameter for determining a system, a process including a selection step of selecting a transmission parameter that can be delivered by one transmission with reference to a transmission state is performed.

According to one aspect of the present invention, it is possible to provide a transmission apparatus, a retransmission control method, and a computer program that can prevent a decrease in throughput without stalling by reliably delivering information related to ARQ retransmission of AM. Can do.

It is a block diagram which shows the structure of a mobile communication system. It is a block diagram which shows an example of a structure of a RLC sublayer and a MAC sublayer. It is a flowchart explaining the process of selection of a transmission parameter. It is a block diagram which shows the structural example of the hardware of the computer which performs a series of processes by a program. It is a block diagram explaining the conventional RLC sublayer and MAC sublayer.

Hereinafter, a transmission apparatus according to an embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a block diagram showing a configuration of a mobile communication system including a radio base station eNB11 that is an example of a transmission apparatus. A radio access network (E-UTRAN) as an LTE mobile communication system shown in FIG. 1 includes a radio base station eNB11 and a mobile station UE12. Communication is performed between the mobile station UE12 and the radio base station eNB11 via a radio link (RL).

The radio base station eNB11 is configured to form a PDCP sublayer 21, an RLC sublayer 22, a MAC sublayer 23, a physical layer 24, and a radio unit 25. The mobile station UE12 is configured to form a PDCP sublayer 31, an RLC sublayer 32, a MAC sublayer 33, a physical layer 34, and a radio unit 35.

The transmitting side of the mobile station UE12 or the radio base station eNB11 transmits C / U plane (Control Plane / User data Plane) data, PDCP processing in the PDCP sublayer 21 or PDCP sublayer 31, and RLC sublayer 22 or RLC sublayer 32. The RLC process, the MAC process in the MAC sublayer 23 or the MAC sublayer 33, and the PHY process in the physical layer 24 or the physical layer 34 are sequentially performed, and transmitted by a radio signal from the

radio unit

25 or 35.

Here, there are TM, UM, and AM in the processing of the

RLC sublayer

22 or 32. Hereinafter, only the AM according to the present invention will be described.

FIG. 2 is a block diagram illustrating an example of configurations of the RLC sublayer 22 and the MAC sublayer 23 of the radio base station eNB11, and the RLC sublayer 32 and the MAC sublayer 33 of the mobile station UE12.

The RLC sublayer 22 includes an RLC SDU receiving unit 111, a transmission buffer 112, a retransmission buffer 113, a transmission control information storage unit 114, a stay / Poll information management unit 115, an RLC PDU creation unit 116, and an RLC PDU transmission unit 117. . Further, the MAC sublayer 23 is provided with an ARQ retransmission determination transmission scheduler unit 121, a MAC SDU reception unit 122, a MAC PDU creation unit 123, and a MAC PDU transmission unit 124.

The RLC SDU receiving unit 111 receives the RLC SDU from the PDCP sublayer 21 and stores it in the transmission buffer 112 as new data. The staying amount and the presence / absence of polling in the transmission buffer 112, the retransmission buffer 113, or the transmission control information storage unit 114 are managed by the staying / Poll information management unit 115 to the ARQ retransmission determination transmission scheduler unit 121 of the MAC sublayer 23. Be notified.

Here, the trigger for performing polling is that when a predetermined number of new RLC PDUs have been transmitted since the last time Polling was performed, when a predetermined number of bytes of new data has been transmitted, and when a predetermined time has elapsed, There are four cases when there is no data to send. Therefore, when an RLC PDU is created from the transmission data stored in the transmission buffer 112, how many RLC PDUs will be created later, how many bytes will be used later, and how many bytes of data will be used after the specified time The stay / Poll information management unit 115 manages whether or not the time has passed as Poll information. The stay amount information and the poll information indicating the stay amount of each of the transmission buffer 112, the retransmission buffer 113, or the transmission control information storage unit 114 are sent from the stay / Poll information management unit 115 to the ARQ retransmission determination transmission scheduler unit 121 of the MAC sublayer 23. Provided.

The ARQ retransmission determination transmission scheduler unit 121 to which the retention amount information and the poll information are notified from a plurality of RBs is a transmission parameter that determines the transmission method of the radio base station eNB11 from the transmission state such as the retention amount and the wireless transmission state. Specifically, a transmission parameter that determines the number of transmission antennas, modulation scheme, coding rate, radio allocation band amount, and the like, and a data allocation amount of each RB are determined. In this case, when polling or transmitting transmission control information, the number of bits transmitted in one modulation (one symbol) is reduced or the coding rate is reduced, so that retransmission of the MAC sublayer 23 is performed. A transmission parameter that is delivered in one transmission without performing HARQ retransmission as control is selected. When determining transmission parameters such as a modulation scheme and a coding rate, the reception state of the opposite party (for example, the mobile station UE12) and the past HARQ retransmission state are referred to.

For example, when HARQ retransmissions occur frequently or when the opposite reception status fluctuates significantly, the number of bits transmitted in one modulation (one symbol) is greatly reduced or the coding rate is reduced. . The data allocation amount determined by the ARQ retransmission determination transmission scheduler unit 121 is notified to the RLC PDU creation unit 116 of the RLC sublayer 22. Whether to perform polling depends on whether a new RLC PDU reaches a predetermined number, a predetermined number of bytes, a predetermined time elapses, the transmission buffer 112, the retransmission buffer 113, or the transmission control information storage unit 114 Judgment is made based on whether the amount of staying is exhausted.

The RLC PDU creation unit 116 acquires transmission data from the transmission control information storage unit 114, the retransmission buffer 113, or the transmission buffer 112, and creates an RLC PDU. That is, the RLC PDU creation unit 116 acquires transmission data or transmission control information in the order of the transmission control information storage unit 114, the retransmission buffer 113, and the transmission buffer 112 until the data allocation amount requested from the MAC sublayer 23 is reached. Create a PDU.

More specifically, when creating an RLC PDU from the transmission control information in the transmission control information storage unit 114, the RLC PDU creation unit 116 recreates and uses the transmission control information from the state of the reception buffer 183 (described later). . When creating the RLC PDU from the transmission data of the retransmission buffer 113, the RLC PDU creation unit 116 attaches the RLC SN having the same value as that when newly transmitting to the RLC header. When creating the RLC PDU from the transmission data of the transmission buffer 112, the RLC PDU creation unit 116 adds the RLC SN to the RLC header. This RLC SN is incremented every time an RLC PDU is created from transmission data in the transmission buffer 112, and is used the next time an RLC PDU is created from transmission data in the transmission buffer 112.

Since there is a limit to the range of RLC SN that can be transmitted without performing delivery confirmation, if the delivery confirmation information cannot be received for a long time, Window Stalling will occur and transmission of data in the transmission buffer 112 will become impossible. For example, if the RLC SN of the youngest number (the youngest number: the newest number) of the RLC PDU that has not received an ACK / NACK notification after transmission or has not received a NACK notification and has not been retransmitted is 100, it is up to 611 Only RLC SN RLC PDUs can be transmitted. Therefore, when the RLC SN transmits 611 RLC PDUs, Window Stalling occurs. When the window stalling occurs, the staying amount of the transmission buffer 112 is treated as 0, and the transmission data of the transmission buffer 112 is not transmitted. This Windows Stalling is resolved by receiving an ACK notification to an RLC PDU with an RLC SN of 100. The created RLC PDU is stored in the retransmission buffer 113 in preparation for ARQ retransmission, and transmitted to the MAC sublayer 23 by the RLC PDU transmission unit 117. When it is necessary to perform polling, a polling bit is set in the RLC header of the RLC PDU created using the transmission data of the retransmission buffer 113 or the transmission buffer 112. By setting the polling bit, the mobile station UE12 is requested to transmit delivery confirmation information.

The RLC PDU transmitted to the MAC sublayer 23 is received by the MAC SDU receiving unit 122 as a MAC SDU. The MAC PDU creation unit 123 creates a MAC PDU by multiplexing a plurality of MAC SDUs according to the ARQ retransmission determination transmission scheduler unit 121. The MAC PDU is transmitted from the MAC PDU transmission unit 124 to the physical layer 24 together with the transmission parameters, and is transmitted to the mobile station UE12 by the radio unit 25 via the radio link.

The MAC sublayer 33 includes a MAC PDU receiver 131, a MAC SDU generator 132, and a MAC SDU transmitter 133. The RLC sublayer 32 includes an RLC PDU receiver 141, a reception control information storage 142, and a reception buffer 143. , An RLC SDU creation unit 144 and an RLC SDU transmission unit 145 are provided.

The MAC PDU receiving unit 131 receives the MAC PDU transmitted from the radio base station eNB11 via the radio link from the physical layer 34 of the mobile station UE12. The MAC SDU creation unit 132 disassembles the MAC PDU into MAC SDUs, and the MAC SDU transmission unit 133 sends the MAC SDUs to the RLC sublayer 32. The RLC PDU receiver 141 receives the MAC SDU sent from the MAC sublayer 33 as an RLC PDU.

Among the RLC PDUs, transmission control information, which is delivery confirmation information of the radio base station eNB11, is stored as reception control information in the reception control information storage unit 142. Among the RLC PDUs, parts other than the transmission control information are stored in the reception buffer 143. Stored.

When RLC PDUs are stored, if there are Poll RLC PDUs, the RLC PDU receiver 141 creates reception control information indicating the reception status of the RLC PDUs using the RLC SN, and stores the reception control information. Stored in the unit 142. The RLC SDU creation unit 144 obtains the previous RLC PDU from the reception buffer 143, and if there is an RLC PDU that has been continuously received from where the RLC SDU has been created, obtains the RLC PDU, and performs the RLC Create an SDU. The created RLC SDU is transmitted to the PDCP sublayer 31 by the RLC SDU transmission unit 145.

When there is a request for reporting the reception status of the received RLC PDU or when it is necessary to report a reception status upon detecting a reception failure, the transmission control information storage unit 154 (described later) stores the transmission control information. Prepare for creation and create transmission control information when creating RLC PDUs. In the transmission control information, delivery confirmation information for notifying whether or not the mobile station UE has received the RLC PDU as an ACK / NACK using the RLC SN is stored.

Further, the RLC sublayer 32 includes an RLC SDU receiving unit 151, a transmission buffer 152, a retransmission buffer 153, a transmission control information storage unit 154, a stay / Poll information management unit 155, an RLC PDU creation unit 156, and an RLC PDU transmission unit 157. The MAC sublayer 33 includes an ARQ retransmission determination transmission scheduler unit 161, a MAC SDU reception unit 162, a MAC PDU creation unit 163, and a MAC PDU transmission unit 164.

The operation of the RLC sublayer 32 in data transmission from the mobile station UE12 to the radio base station eNB11 is the same as the operation of the RLC sublayer 22 in data transmission from the radio base station eNB11 to the mobile station UE12.

The RLC SDU receiving unit 151 receives the RLC SDU from the PDCP sublayer 31 of the mobile station UE12 and stores it in the transmission buffer 152. The stay amount information and the poll information indicating the stay amount of each of the transmission buffer 152, the retransmission buffer 153, or the transmission control information storage unit 154 are managed by the stay / Poll information management unit 155, and the ARQ retransmission determination transmission of the MAC sublayer 33 is performed. This is notified to the scheduler unit 161.

The ARQ retransmission determination transmission scheduler unit 161 notified of the staying amount from a plurality of RBs notifies the radio base station eNB11 of the staying amount and requests radio assignment. Then, the ARQ retransmission determination transmission scheduler unit 161 determines the transmission parameter and the data allocation amount of each RB according to the radio allocation result from the radio base station eNB11. At this time, the ARQ retransmission determination transmission scheduler unit 161 determines a transmission parameter by reflecting whether or not to transmit the poll information and the transmission control information.

The data allocation amount of each RB is notified to the RLC PDU creation unit 156 of the RLC sublayer 32. The RLC PDU creation unit 156 obtains transmission data from the transmission control information storage unit 154, the retransmission buffer 153, or the transmission buffer 152, and creates an RLC PDU. The created RLC PDU is stored in the retransmission buffer 153 in preparation for ARQ retransmission and transmitted to the MAC sublayer 33 by the RLC PDU transmission unit 57. The RLC PDU transmitted to the MAC sublayer 33 passes through the MAC SDU reception unit 162, the MAC PDU creation unit 163, and the MAC PDU transmission unit 164, and then by the physical layer 34 and the radio unit 35 via the radio link via the radio base station eNB11 Sent to.

Further, the MAC sublayer 23 of the radio base station eNB11 is provided with a MAC PDU reception unit 171, a MAC SDU creation unit 172, and a MAC SDU transmission unit 173, and the RLC sublayer 22 includes an RLC PDU reception unit 181 and reception control information. A storage unit 182, a reception buffer 183, an RLC SDU creation unit 184, and an RLC SDU transmission unit 185 are provided.

The MAC PDU receiver 171 receives from the physical layer 25 the MAC PDU sent from the mobile station UE12 via the radio link. The MAC SDU creation unit 172 decomposes the MAC PDU into MAC SDUs, and the MAC SDU transmission unit 173 sends the MAC SDUs to the RLC sublayer 22. The RLC PDU receiver 181 receives the MAC SDU sent from the MAC sublayer 23 as an RLC PDU. Among the RLC PDUs, transmission control information that is delivery confirmation information of the mobile station UE12 is stored in the reception control information storage unit 182 as reception control information, and a portion other than the transmission control information of the RLC PDU is stored in the reception buffer 183. The The RLC SDU creation unit 184 acquires the RLC PDU from the reception buffer 183 and creates the RLC SDU. The created RLC SDU is transmitted to the PDCP sublayer 21 of the radio base station eNB11 by the RLC SDU transmission unit 185.

The data in the retransmission buffer 113 is managed according to the received reception control information. The reception control information stored in the reception control information storage unit 182 indicates whether or not the RLC PDU has been received by the mobile station UE12 using the RLC SN. The reported RLC PDU is deleted from the retransmission buffer 113, and retransmission of the RLC PDU that has been NACK-reported as not received has been prepared.

In this case, the RLC PDU creation unit 116 acquires transmission data from the retransmission buffer 113 and creates an RLC PDU to be retransmitted.

As described above, by setting a transmission parameter that can be reliably delivered without performing retransmission control in the

MAC sublayer

23 or 33 for the data in which the polling bit is set and the delivery confirmation information, generation of window stalling occurs. Therefore, it is possible to prevent a decrease in data throughput.

Next, transmission parameter selection processing in the radio base station eNB11 will be described with reference to the flowchart of FIG. In step S11, the stay / Poll information management unit 115 determines whether or not a predetermined number of new RLC PDUs have been transmitted since the last time Polling was performed, whether or not a predetermined number of bytes of new data have been transmitted. Whether or not polling is to be performed is determined based on whether or not the time elapses and whether or not there is no data to be transmitted.

If it is determined in step S11 that polling is not to be performed, the procedure proceeds to step S12, and the stay / Poll information management unit 115 determines whether or not to transmit transmission control information including delivery confirmation information. If it is determined in step S12 that transmission control information is to be transmitted, the procedure proceeds to step S13.

On the other hand, if it is determined in step S11 that polling is to be performed, the procedure proceeds to step S13.

In step S13, the ARQ retransmission determination transmission scheduler unit 121 acquires information on a transmission state such as a retention amount and a wireless transmission state from the retention / Poll information management unit 115 of each RB. In step S14, the ARQ retransmission determination transmission scheduler unit 121 refers to the acquired transmission state information, selects a transmission parameter that can be delivered in one transmission, and ends the transmission parameter selection processing. More specifically, in step S14, the ARQ retransmission determination transmission scheduler unit 121 refers to the transmission state information such as the staying amount and the wireless transmission state, and transmits the modulation method by one modulation (one symbol). A transmission parameter that determines the number of transmission antennas, the modulation scheme, the coding rate, the amount of radio allocated bandwidth, or the like is selected so as to reduce the number of bits or the coding rate.

If it is determined in step S12 that transmission control information is not transmitted, the transmission parameter selection process ends.

Since the process of selecting transmission parameters in the mobile station UE12 is the same as that in the radio base station eNB11, the description thereof is omitted.

In addition, instead of always selecting a transmission parameter to be delivered in one transmission without performing HARQ retransmission, which is retransmission control of the

MAC sublayer

23 or 33, for the RLC PDU to be polled, the Windows Stalling It is also possible to implement it only when or is likely to occur. In this case, transmission from the stay / Poll information management unit 115 or 155 of the

RLC sublayer

22 or 32 to the ARQ retransmission determination

transmission scheduler unit

121 or 161 of the

MAC sublayer

23 or 33 as a possibility of occurrence of Window Stalling before the Window Stalling is performed. The number of RLC PDUs that can be transmitted using the data in the

buffer

112 or 152 is notified. If the value obtained by subtracting the number of RLC PDUs to be transmitted from the number of RLC PDUs that can be transmitted is less than the threshold, the ARQ retransmission determination

transmission scheduler unit

121 or 161 is to perform delivery in one transmission without performing HARQ retransmission. The correct transmission parameters.

Also, when a window stalling occurs instead of always selecting a transmission parameter that is delivered in a single transmission without performing HARQ retransmission, which is retransmission control of the MAC sublayer, for delivery confirmation information. Or it can be done only when it is likely to occur. In this case, the most likely occurrence of window stalling from the reception buffer 143 or 183 of the

RLC sublayer

22 or 32 to the ARQ retransmission determination

transmission scheduler unit

121 or 161 of the

MAC sublayer

23 or 33 is the oldest among the received RLC PDUs. The difference between the RLC SN of the oldest number (the oldest number) and the youngest RLC SN among the RLC PDUs for which the delivery confirmation information has not been notified or has not been received is notified. When the difference exceeds the threshold, the ARQ retransmission determination

transmission scheduler unit

121 or 161 selects a transmission parameter to be delivered in one transmission without performing HARQ retransmission.

Furthermore, when a window stalling occurs or is likely to occur, it is also effective to create and transmit delivery confirmation information without waiting for polling from the opposite party.

In this way, when performing the data retransmission control process based on the delivery confirmation information from the opposite receiving device, the control signal related to the retransmission control is transmitted so that it can be delivered in a timely and reliable manner, thereby stalling and communicating. Can be prevented from stopping.

Transmission parameters that can be reliably delivered without performing retransmission control in the MAC sublayer are set for the data in which the polling bit is set and the delivery confirmation information. As a result, retransmission control in the RLC sublayer can be performed smoothly, so that a reduction in data throughput can be prevented.

The series of processes described above can be executed by hardware or software. When a series of processing is executed by software, a program constituting the software executes various functions by installing a computer incorporated in dedicated hardware or various programs. For example, it is installed from a program recording medium in a general-purpose personal computer or the like.

FIG. 4 is a block diagram showing an example of the hardware configuration of a computer that executes the above-described series of processing by a program.

In the computer, a CPU (Central Processing Unit) 201, a ROM (Read Only Memory) 202, and a RAM (Random Access Memory) 203 are connected to each other by a bus 204.

An input / output interface 205 is further connected to the bus 204. The input / output interface 205 includes an input unit 206 composed of a keyboard, mouse, microphone, etc., an output unit 207 composed of a display, a speaker, etc., a storage unit 208 composed of a hard disk or nonvolatile memory, and a communication unit 209 composed of a network interface. A drive 210 for driving a removable medium 211 such as a magnetic disk, an optical disk, a magneto-optical disk, or a semiconductor memory is connected.

In the computer configured as described above, the CPU 201 loads, for example, the program stored in the storage unit 208 to the RAM 203 via the input / output interface 205 and the bus 204 and executes the program, and the series described above. Is performed.

The program executed by the computer (CPU 201) is, for example, a magnetic disk (including a flexible disk), an optical disk (CD-ROM (Compact Disc-Read Only Memory), DVD (Digital Versatile Disc), etc.), a magneto-optical disk, or a semiconductor. The program is recorded on a removable medium 211 that is a package medium composed of a memory or the like, or provided via a wired or wireless transmission medium such as a local area network, the Internet, or digital satellite broadcasting.

The program can be installed in the computer by storing the removable medium 211 in the drive 210 and storing it in the storage unit 208 via the input / output interface 205. Further, the program can be installed in a computer by being received by the communication unit 209 via a wired or wireless transmission medium and stored in the storage unit 208. In addition, the program can be installed in the computer in advance by storing the program in the ROM 202 or the storage unit 208 in advance.

The program executed by the computer may be a program that is processed in time series in the order described in this specification, or in parallel or at a necessary timing such as when a call is made. It may be a program for processing.

The embodiments of the present invention are not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 11 ... Radio base station eNB, 12 ... Mobile station UE, 22 ... RLC sublayer, 23 ... MAC sublayer, 32 ... RLC sublayer, 33 ... MAC sublayer, 112 ... Transmission buffer, 113 ... Retransmission buffer, 114 ... Transmission control information storage part 115: Retention / Poll information management unit 116: RLC PDU creation unit 121 ... ARQ retransmission determination transmission scheduler unit 142 ... Reception control information storage unit 152 ... Transmission buffer 153 ... Retransmission buffer 154 ... Transmission control information storage 155 ... Retention / Poll information management part, 156 ... RLC PDU creation part, 161 ... ARQ retransmission discrimination transmission scheduler part, 182 ... Reception control information storage part, 201 ... CPU, 202 ... ROM, 203 ... RAM, 208 ... storage Part 209 ... communication part 211 ... removable media

Claims

In a transmission apparatus that is used for mobile communication and retransmits the transmission units by numbers sequentially assigned to the transmission units,
Determining means for determining whether to poll and whether to transmit control information for controlling transmission;
When it is determined to poll, or when it is determined to transmit the control information, referring to the transmission state as a transmission parameter for determining a method of transmitting data for polling or data including the control information, once And a selection means for selecting a transmission parameter that can be delivered by the transmission of the transmission device.
The transmission apparatus according to claim 1,
A transmitter characterized by conforming to LTE (Long Term Evolution).
The transmission apparatus according to claim 1,
The determination means is arranged in an RLC (Radio Link Control) sublayer,
The transmission device according to claim 1, wherein the selection unit is arranged in a MAC (Medium Access Control) sublayer.
The transmission apparatus according to claim 1,
The selecting means refers to the transmission state that is a staying amount or a wireless transmission state, and selects the transmission parameter that determines the number of transmission antennas, a modulation scheme, a coding rate, or a radio allocated bandwidth amount. A transmitting device.
The transmission apparatus according to claim 1,
The transmission device is characterized in that the selection means selects the transmission parameter in accordance with occurrence or prediction of occurrence of window stalling.
In a retransmission control method for retransmitting a transmission unit by a number used in mobile communication and sequentially assigned to the transmission unit,
A determination step of determining whether to poll and whether to transmit control information for controlling transmission;
When it is determined to poll, or when it is determined to transmit the control information, referring to the transmission state as a transmission parameter for determining a method of transmitting data for polling or data including the control information, once And a selection step of selecting a transmission parameter that can be delivered by the transmission of the retransmission control method.
A computer that controls a transmission device that is used for mobile communication and retransmits the transmission unit by a number sequentially assigned to the transmission unit.
A determination step of determining whether to poll and whether to transmit control information for controlling transmission;
When it is determined to poll, or when it is determined to transmit the control information, referring to the transmission state as a transmission parameter for determining a method of transmitting data for polling or data including the control information, once And a selection step of selecting a transmission parameter that can be delivered by the transmission of the computer program.