Communication system, method of operating a communication system, and method of operating a communication device

Abstract

A communication system, a method for operating a communication system, and a method for operating a communication device are provided. The communication system includes: a transmitter configured to send a data packet to a receiver; and a receiver configured to receive a data packet from the transmitter, wherein the receiver is configured to: receive at least one first packet from the transmitter, determine whether there is a first failed packet with an error among the at least one first packet, send a first status report requesting retransmission of the first failed packet, and send a second status report requesting retransmission of the first failed packet within a predetermined status report processing period from the sending of the first status report, wherein the first status report includes first time information corresponding to the sending time of the first status report from the receiver to the transmitter, and the second status report includes second time information corresponding to the sending time of the second status report from the receiver to the transmitter.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the priority of Korean Patent Application No. 10-2019-0098345 filed on August 12, 2019, in the Korean Intellectual Property Office, the entire contents of which are incorporated herein by reference. Technical Field

[0003] Exemplary embodiments of the inventive concept relate to a communication system, a method of operating a communication system, and a method of operating a communication device. Background Art

[0004] Automatic Repeat reQuest (ARQ) refers to a set of error control protocols for data transmission that typically use acknowledgments and timeouts to achieve reliable data transmission over unreliable services, where an acknowledgment is a message sent by a receiver indicating that it has correctly received a data packet and a timeout is a specified period of time allowed to pass before an acknowledgment is expected to be received.

[0005] Common types of ARQ protocols include Stop-and-wait ARQ, Go-Back-N ARQ, and Selective Repeat ARQ / Selective Reject ARQ. Such ARQ protocol types are used to detect and retransmit failed packets. Using ARQ in this way, when a failed packet is detected, information about the erroneous packet is output to the transmitter through a status report. Based on the status report, the transmitter checks the erroneous packet and retransmits the erroneous packet to the receiver. After each status report is sent, a status report prohibition period is executed, during which the receiver is prohibited from sending the next status report even if another failed packet is detected.

[0006] Hybrid Automatic Repeat reQuest (HARQ) represents a combination of high-speed forward error correction coding and ARQ error control. HARQ can reduce the time delay of the upper layer by adding channel coding to ARQ. HARQ is used in various mobile communication standards, such as high-speed packet access (HSPA) and long-term evolution (LTE). Summary of the invention

[0007] Exemplary embodiments of the present inventive concept provide a communication device, system, and method for sending a subsequent status report regarding a subsequently detected failed packet, wherein the subsequently detected failed packet is detected during a previous status report processing period after a receiver sent a previous status report.

[0008] According to an exemplary embodiment of the present invention, a method for operating a communication system is provided, the communication system having a receiver, the method comprising: receiving at least one first packet by the receiver; sending a first status report by the receiver requesting retransmission of a first failed packet among the at least one first packet, and starting a first processing period for the first status report; receiving at least one second packet by the receiver during the first processing period; and sending a second status report by the receiver requesting retransmission of a second failed packet among the at least one second packet during the first processing period, wherein the first processing period comprises a historical or expected processing period based on a difference between reception of the at least one first packet and reception of the at least one second packet, wherein the first processing period ends according to the earlier of: completion of the expected processing period of retransmission of the first failed packet to the receiver, or actual reception of the retransmitted first failed packet by the receiver.

[0009] According to an exemplary embodiment of the present invention, a method for operating a communication device is provided, the method comprising: a first packet data unit and a second packet data unit are sequentially sent by a transmitter; a first status report is received by the transmitter requesting retransmission of a first failed packet having an error among at least one first packet included in the first packet data unit; a second status report is received by the transmitter requesting retransmission of a second failed packet having an error among at least one second packet included in the second packet data unit; and based on first time information included in the first status report and second time information included in the second status report, the transmitter retransmits the first failed packet and the second failed packet.

[0010] According to an exemplary embodiment of the present invention, a communication system is provided, comprising: a transmitter, configured to send data packets to a receiver; and a receiver, configured to receive data packets from the transmitter, wherein the receiver is configured to: receive at least one first packet from the transmitter, determine whether there is a first failed packet with an error among the at least one first packet, send a first status report requesting retransmission of the first failed packet, and send a second status report requesting retransmission of the first failed packet within a predetermined status report processing period from the sending of the first status report, wherein the first status report includes first time information corresponding to the sending time of the first status report from the receiver to the transmitter, and the second status report includes second time information corresponding to the sending time of the second status report from the receiver to the transmitter. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Exemplary embodiments of the inventive concept will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0012] Figure 1 is a schematic block diagram illustrating a communication system according to an exemplary embodiment;

[0013] Figure 2 is a flow chart illustrating a method of operating a communication device according to an exemplary embodiment;

[0014] Figure 3 is a flow chart illustrating a method of operating a communication device according to an exemplary embodiment;

[0015] Figure 4 is a hybrid timing diagram illustrating a method of operating a communication system according to an exemplary embodiment;

[0016] Figure 5 is a flow chart illustrating a method of operating a communication device according to an exemplary embodiment;

[0017] Figure 6 is a hybrid timing diagram illustrating a method of operating a communication system according to an exemplary embodiment;

[0018] Figures 7A to 7F is a hybrid data flow diagram illustrating a method of detecting retransmitted packets in various failed packet scenarios according to an exemplary embodiment;

[0019] Figure 8 is a data structure diagram showing the format of a status report according to an exemplary embodiment;

[0020] Fig. 9 is a flow chart illustrating a method of operating a communication device according to an exemplary embodiment;

[0021] Fig.10 is a flow chart illustrating a method of operating a communication device according to an exemplary embodiment;

[0022] Fig.11 is a hybrid timing diagram illustrating a method of operating a communication system according to an exemplary embodiment;

[0023] Fig.12 is a hybrid timing diagram illustrating a method of operating a communication system according to an exemplary embodiment;

[0024] Fig.13 is a flowchart illustrating the operation of a communication device according to an exemplary embodiment; and

[0025] Fig.14 is a schematic block diagram illustrating a communication device according to an exemplary embodiment. DETAILED DESCRIPTION

[0026] Exemplary embodiments of the inventive concept relate to devices, systems and methods that can be used with a modified ARQ type protocol, wherein information about subsequently failed packets from a transmitter to a receiver is output by the receiver in a subsequent status report during the pendency of a previous status report processing period, wherein the previous status report processing period may have been previously referred to in the art as a status report prohibited period. Although wireless exemplary embodiments are shown and described, the inventive concept is not limited thereto and may be similarly applied to congested or noisy wired (e.g., telegraph) and / or hybrid communication networks in addition to the wireless communication network examples described herein. In the present disclosure, singular forms such as "a", "an", and "the" are intended to include plural forms.

[0027] Figure 1 A wireless communication system 1 according to an exemplary embodiment is shown.

[0028] As a non-limiting example, the communication system 1 may include a fifth generation (5 th The communication system 1 may be a 5G generation (5G) wireless system, a long term evolution (LTE) system, an advanced LTE (LTE-Advanced) system, a code division multiple access (CDMA) system, a global system for mobile communications (GSM), a wireless local area network (WLAN) system, or any other communication system. Although the communication system 1 is described below mainly with reference to a 5G system and / or a LTE system, it should be understood that the embodiments are not limited thereto.

[0029] The communication system 1 may include a base station (BS) 10 and a user equipment (UE) 20. The BS 10 may generally refer to a fixed, fixed track or reference area station for communicating with the user equipment and / or another BS, and may exchange data and control information by communicating with the user equipment and / or another BS. For example, the BS 10 may be referred to as a node B, an evolved-Node B (eNB), a sector, a site, a base transceiver system (BTS), an access point (AP), a relay node, a remote radio head (RRH), a radio unit (RU), a small cell, a predominant transmitter, etc. The BS10 or cell described in this article can be interpreted as having a general meaning indicating some areas or functions covered by a base station controller (BSC) in CDMA, a node B in wideband code division multiple access (WCDMA), an eNB or sector (site) in LTE, etc., and can cover all kinds of coverage areas, such as a megacell, a macrocell, a microcell, a picocell, a femtocell, a relay node, an RRH, a RU and a small cell communication range.

[0030] The UE 20 as a communication device may be fixed or mobile, and may refer to various types of devices capable of transmitting and receiving data and / or control information by communicating with the BS 10. For example, the UE 20 may be referred to as a terminal device, a mobile station (MS), a mobile terminal (MT), a user terminal (UT), a subscriber station (SS), a wireless device, a handheld device, a predominant receiver, etc.

[0031] The communication network between UE 20 and BS 10 can support communication between multiple users by sharing available network resources. For example, in a wireless communication network, information can be transmitted through various multiple access methods (such as CDMA, frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), single carrier frequency division multiple access (SC-FDMA), OFDM-FDMA, OFDM-TDMA, OFDM-CDMA, etc.).

[0032] like Figure 1 As shown, UE 20 and BS 10 can communicate with each other via uplink (UL) 4 and downlink (DL) 2. In a communication system such as an LTE system or an advanced LTE system, UL 4 and DL 2 can transmit control information via control channels (such as a physical downlink control channel (PDCCH), a physical control format indicator channel (PCFICH), a physical hybrid automatic repeat request (ARQ) indicator channel (PHICH), a physical uplink control channel (PUCCH), an enhanced physical downlink control channel (EPDCCH), etc.), and can transmit data via data channels (such as a physical downlink shared channel (PDSCH), a physical uplink shared channel (PUSCH), etc.). In some embodiments, enhanced PDCCH or extended PDCCH (EPDCCH) may be used to send control information.

[0033] refer to Figure 1, the BS 10 may include a signal processor 100, a transceiver 210 connected to the signal processor, and an antenna 220 connected to the transceiver. In an exemplary embodiment, the transceiver 210 may include a filter, a mixer connected to the filter, a power amplifier (PA) connected to the mixer, and a low noise amplifier (LNA) connected to the PA. The transceiver 210 may send a signal via 220 and DL 2. For example, the transceiver 210 may shift a signal provided from the signal processor 100 from a baseband to a radio frequency (RF) band, for example, via a mixer, and may amplify the shifted signal, for example, via the PA, and provide the amplified signal to the antenna 220. In addition, the transceiver 210 may process a signal received via the UL 4 and the antenna 220, and may provide the processed signal to the signal processor 100. For example, the transceiver 210 may amplify a signal received via the antenna 220 (such as via an LNA), may shift the amplified signal from an RF band to a baseband (such as via a mixer), and may provide the shifted signal to the signal processor 100 .

[0034] The signal processor 100 may include a radio link control (RLC) block 110, a medium access control (MAC) block 120 connected to the RLC block 110, a physical (PHY) block 130 connected to the MAC block 120, an ARQ manager 140 connected to the RLC block 110, and a hybrid automatic repeat request (HARQ) manager 150 connected to the MAC block 120 and the PHY block 130. The RLC block 110, the MAC block 120, and the PHY block 130 may respectively perform operations corresponding to the RLC layer, the MAC layer, and the physical or PHY layer of the communication system 1. The RLC block 110 may perform ARQ retransmission. For example, the RLC block 110 may perform ARQ operations, etc. by reconstructing a packet data convergence protocol (PDCP) packet data unit (PDU) into an appropriate size, and may rearrange the order of the RLC PDUs reversed during the HARQ process performed by the MAC block 120.

[0035] The MAC block 120 may perform logical channel multiplexing, HARQ retransmission, scheduling of UL 4 and DL 2, carrier aggregation (CA) control, etc. For DL ​​2, the PHY block 130 may receive a transport block from the MAC block 120 and may perform cyclic redundancy correction (CRC) insertion, encoding, rate matching, scrambling, modulation, antenna mapping, etc. Although in Figure 1 1 and 120. In the example of FIG. 1 , at least two of the RLC block 110, the MAC block 120, and the PHY block 130 may be implemented as a single unit. Figure 1 Although not specifically described in the specification, the signal processor 100 may further include a PDCP block, wherein the PDCP block may perform operations such as Internet Protocol (IP) header compression / recovery, encryption / decryption, etc.

[0036] The ARQ manager 140 may perform an ARQ operation by controlling the RLC block 110. For example, when the BS 10 operates as a receiver of packets, the ARQ manager 140 may detect a failed packet among received packets by controlling the RLC block 110, and may generate information about the detected failed packet in the form of a status report. The ARQ manager 140 may output the generated status report to the UE 20 by controlling the RLC block 110, the MAC block 120, and the PHY block 130. Based on the status report, the UE 20 may perform retransmission about the failed packet.

[0037] When the BS 10 operates as a transmitter of packets, the ARQ manager 140 may retransmit failed packets by controlling the RLC block 110 based on the received status report.

[0038] The HARQ manager 150 may perform a HARQ operation by controlling the MAC block 120 and the PHY block 130. For example, the HARQ manager 150 may repeatedly transmit an Acknowledged (ACK) / Not Acknowledged (NACK) signal for a packet received using a data channel.

[0039] When the signal processor 100 requests retransmission of a failed packet based on a status report, the signal processor 100 may not send a status report without time information even if the signal processor 100 detects a failed packet during a status report processing period in which a status report is not generated within a specific period to prevent repeated retransmissions.

[0040] When the signal processor 100 according to an exemplary embodiment operates as a receiver of a packet, when the signal processor 100 detects a failed packet, the signal processor 100 may send a status report regardless of the status report processing period. In an exemplary embodiment, the signal processor 100 may send a status report including time information corresponding to the system time of sending the status report.

[0041] In an exemplary embodiment, when the signal processor 100 operates as a transmitter of packets, when the signal processor 100 receives a status report, the signal processor 100 may merge the previously received status report with the most recently received status report based on time information, and may retransmit the failed packet based on the merged status report, thereby preventing repeated transmission of the failed packet.

[0042] like Figure 1 As shown, UE 20 may include signal processor 300, transceiver 410, and antenna 420. Transceiver 410 may receive signals via DL 2 and antenna 420, and may transmit signals via antenna 420 and UL 4.

[0043] Similar to the BS 10, the signal processor 300 of the UE 20 may include an RLC block 310, a MAC block 320 connected to the RLC block 310, a PHY block 330 connected to the MAC block 320, an ARQ manager 340 connected to the RLC block 310, and a HARQ manager 350 connected to the MAC block 320 and the PHY block 330; and the RLC block 310, the MAC block 320, and the PHY block 330 may respectively perform operations corresponding to the RLC layer, the MAC layer, and the PHY layer of the communication system 1. The ARQ manager 340 may perform an ARQ operation by controlling the RLC block 310.

[0044] For example, when the UE 20 operates as a receiver of packets, the ARQ manager 340 can detect a failed packet among received packets by controlling the RLC block 310, and can generate information about the detected failed packet in the form of a status report. The ARQ manager 340 can output the generated status report to the BS 10 by controlling the RLC block 310, the MAC block 320, and the PHY block 330, and based on the status report, the BS 10 can perform retransmission about the failed packet. When the UE 20 operates as a transmitter of packets, the ARQ manager 340 can retransmit the failed packet by controlling the RLC block 310 based on the received status report.

[0045] The operation of the ARQ manager 340 may be the same as or similar to that of the ARQ manager 140 included in the BS 10, and thus a repeated description thereof is omitted.

[0046] Figure 2 A method of operating a communication device according to an exemplary embodiment is shown. Specifically, Figure 2 is a diagram showing an ARQ operation in a case where a communication device acts as a receiver of a packet.

[0047] refer to Figure 2 In operation S110, a communication device (eg, Figure 1 The BS 10 or UE 20 of the present invention may receive a first packet data unit from a transmitter. The packet data unit described herein may include a plurality of packets. In operation S120, the communication device may determine whether there is a failed packet among the packets included in the first packet data unit. The failed packet described herein may refer to a packet that has failed to be received, a packet that has failed to be corrected using error correction (e.g., an error correcting code (ECC)), etc. The failed packet may alternatively be referred to as an erroneous packet,

[0048] When there is a failed packet in the first packet data unit, in operation S130, the communication device may send a first status report requesting retransmission of the failed packet included in the first packet data unit to the transmitter. In an exemplary embodiment, the communication device may merge time information corresponding to the time of sending the first status report and information about the failed packet into the first status report. When there is no failed packet in the first packet data unit, the communication device may receive a new packet data unit.

[0049] When the communication device receives the second packet data unit within the status report processing period at operation S140, it can be determined whether there is a failed packet among the packets included in the second packet data unit at operation S150, wherein the status report processing period may be previously referred to as the status report prohibition time or the status report prohibition period. In an example, the status report processing period may be determined as a time period from sending the first status report until a predetermined time has passed.

[0050] When there is a failed packet among the packets included in the second packet data unit, in operation S160, the communication device may send a second status report requesting retransmission of the failed packet included in the second packet data unit to the transmitter even within the status report processing period. In an exemplary embodiment, the communication device may merge time information corresponding to the time of sending the second status report and information about the failed packet into the second status report.

[0051] When a communication device according to the present invention detects a failed packet, the communication device can quickly re-receive the failed packet by sending a status report requesting retransmission of the failed packet regardless of the status report processing period, and signal transmission and reception delays can be reduced.

[0052] Figure 3 A method of operating a communication device according to an exemplary embodiment is shown. Specifically, Figure 3 is a diagram showing an operation of retransmitting a failed packet based on a status report in a case where a communication device acts as a transmitter of a packet.

[0053] refer to Figure 3 In operation S210, a communication device (such as Figure 1 The BS 10 or UE 20 of the communication device may receive a first status report including the first time information. In response to the first status report, at operation S220, the communication device may retransmit a first failed packet corresponding to the first time information. In operation S230, the communication device may receive a second status report including the second time information. In response to the second status report, at operation S240, the communication device may retransmit a second failed packet corresponding to the second time information.

[0054] In an example, the communication device can determine whether the second status report has occurred within the status report processing period starting from the first status report based on the first time information and the second time information. When the second status report has occurred within the status report processing period, the communication device can generate a new status report after excluding duplicate requests between the first status report and the second status report.

[0055] In the example, the communication device can determine whether a failed packet retransmission according to a second status report has been performed based on the first time information and the second time information, and when a failed packet retransmission according to the second status report has not been performed, the communication device can generate a new status report after excluding duplicate requests from the first status report and the second status report.

[0056] The communication system according to the exemplary embodiment can incorporate the corresponding time information into the status report, and can retransmit the failed packet based on the time information. Therefore, even if the status report is sent regardless of the status report processing period, the communication device receiving the status report can schedule the failed packet to be sent based on the time information, and as a result, the repeated transmission of the failed packet can be prevented, and the delay in signal transmission and reception can be reduced.

[0057] Figure 4 A method of operating a communication system according to an exemplary embodiment is shown. Specifically, Figure 41 is a diagram showing a method in which a transmitter 11 and a receiver 21 included in a communication system perform an ARQ operation according to a time sequence. Figure 2 and 3 Repeated description of .

[0058] refer to Figure 4 , at a first system time t1, the transmitter 11 may send a first packet data unit PDU1 to the receiver 21 at a processing time T110. The first packet data unit PDU1 may include a first packet P0 to an eighth packet P7. At a second system time t2, the receiver 21 may receive the first packet data unit PDU1, and may detect an error in a fourth packet P3 of the received first packet data unit PDU1 at a processing time T120. The receiver 21 may send a first status report SR1 requesting retransmission of the fourth packet P3 to the transmitter 11, and the first status report SR1 may include information about a second system time t2 corresponding to the system time at which the first status report SR1 was sent.

[0059] At the third system time t3, the transmitter 11 may transmit the second packet data unit PDU2 to the receiver 21 at the processing time T130. The second packet data unit PDU2 may include the ninth packet P8 to the sixteenth packet P15. At the fourth system time t4, the transmitter 11 may receive the first status report SR1, and in response to the first status report SR1, may retransmit the fourth packet P3 required for retransmission to the receiver 21 at the processing time T140 by merging the fourth packet P3 required for retransmission into the third packet data unit PDU3.

[0060] At the fifth system time t5, the receiver 21 may receive the second packet data unit PDU2, and may detect errors in the tenth packet P9 and the twelfth packet P11 of the received second packet data unit PDU2 at the processing time T150. The fifth system time t5 may be included in the status report processing period T_sp, wherein the status report processing period T_sp is determined as a predetermined period starting from the second system time t2 at which the first status report SR1 is output. Although the fifth system time t5 is included in the status report processing period T_sp, the receiver 21 may send the second status report SR2 requesting retransmission of the tenth packet P9 and the twelfth packet P11 to the transmitter 11, and the second status report SR2 may include information about the fifth system time t5 corresponding to the system time at which the second status report SR2 is sent.

[0061] At the sixth system time t6, the transmitter 11 may receive a second status report SR2, and in response to the second status report SR2, may retransmit the tenth packet P9 and the twelfth packet P11 required for retransmission to the receiver 21 at a processing time T160 by merging the tenth packet P9 and the twelfth packet P11 into the fourth packet data unit PDU4.

[0062] Figure 5 A method of operating a communication device according to an exemplary embodiment is shown. Specifically, Figure 5 is a diagram showing an operation of retransmitting a failed packet based on a status report in a case where a communication device acts as a transmitter of a packet.

[0063] refer to Figure 5 In operation S310, a communication device (such as, for example Figure 1 The BS 10 or UE 20 of the communication device may receive a first status report including the first time information. In response to the first status report, at operation S320, the communication device may retransmit the first failed packet corresponding to the first time information. In operation S330, the communication device may receive a second status report including the first time information and the second time information. Because the failed packet corresponding to the first time information has been retransmitted, in response to the second status report, at operation S340, the communication device may only retransmit the second failed packet corresponding to the second time information.

[0064] Figure 6 A method of operating a communication system according to an exemplary embodiment is shown. Specifically, Figure 6 1 is a diagram showing a method in which a transmitter 11 and a receiver 21 included in a communication system perform an ARQ operation according to a time sequence. Figure 4 and 5 Repeated description of .

[0065] Reference Figure 6, at the first system time t1, the transmitter 11 may send the first packet data unit PDU1 to the receiver 21 at the processing time T210. The first packet data unit PDU1 may include the first packet P0 to the eighth packet P7. At the second system time t2, the receiver 21 may receive the first packet data unit PDU1, and may detect an error in the fourth packet P3 of the received first packet data unit PDU1 at the processing time T220. The receiver 21 may send a first status report SR1 requesting retransmission of the fourth packet P3 to the transmitter 11, and the first status report SR1 may include information about the second system time t2 corresponding to the system time of sending the first status report SR1. At the third system time t3, the transmitter 11 may send the second packet data unit PDU2 to the receiver 21 at the processing time T230. The second packet data unit PDU2 may include the ninth packet P8 to the sixteenth packet P15.

[0066] At a fourth system time t4, the transmitter 11 may receive the first status report SR1, and in response to the first status report SR1, may retransmit the fourth packet P3 required for retransmission to the receiver 21 at a processing time T240 by merging the fourth packet P3 required for retransmission into the third packet data unit PDU3.

[0067] At the fifth system time t5, the receiver 21 may receive the second packet data unit PDU2, and may detect errors in the tenth packet P9 and the twelfth packet P11 of the received second packet data unit PDU2 at the processing time T250. The fifth system time t5 may be included in the status report processing period T_sp, wherein the status report processing period T_sp is determined as a predetermined period starting from the second system time t2 at which the first status report SR1 is output. Although the fifth system time t5 is included in the status report processing period T_sp, the receiver 21 may send the second status report SR2 requesting retransmission of the tenth packet P9 and the twelfth packet P11 to the transmitter 11, and the second status report SR2 may include not only information about the tenth packet P9 and the twelfth packet P11 that have appeared at the fifth system time t5, but also information about the fourth packet P3 that has appeared at the second system time t2.

[0068] At the sixth system time t6, the transmitter 11 may receive the second status report SR2, and in response to the second status report SR2, may determine the packets needed for retransmission based on the time information. Because the fourth packet P3 has been retransmitted, the transmitter 11 may retransmit the tenth packet P9 and the twelfth packet P11 needed for retransmission to the receiver 21 at the processing time T260 by merging the tenth packet P9 and the twelfth packet P11 into the fourth packet data unit PDU4.

[0069] Figures 7A to 7F A method of detecting retransmitted packets in various failed packet scenarios according to an exemplary embodiment is shown.

[0070] refer to Figure 4 and 7A , Figure 4 The transmitter 11 can be Figure 4 The receiver 21 receives a first status report SR1 including a fourth packet P3 corresponding to a second system time t2, and in response to the first status report SR1, the fourth packet P3 may be retransmitted by merging the fourth packet P3 into a third packet data unit PDU3. In addition, the transmitter may receive a second status report SR2 including a tenth packet P9 and a twelfth packet P11 corresponding to a fifth system time t5 from the receiver, and in response to the second status report SR2, the tenth packet P9 and the twelfth packet P11 may be retransmitted by merging the tenth packet P9 and the twelfth packet P11 into a fourth packet data unit PDU4.

[0071] refer to Figure 7B , the transmitter may receive a first status report SR1 including a fourth packet P3 corresponding to the first number n1 from the receiver, and in response to the first status report SR1, the fourth packet P3 may be retransmitted by merging the fourth packet P3 into the third packet data unit PDU3. In addition, the transmitter may receive a second status report SR2 including a tenth packet P9 and a twelfth packet P11 corresponding to the second number n2 from the receiver, and in response to the second status report SR2, the tenth packet P9 and the twelfth packet P11 may be retransmitted by merging the tenth packet P9 and the twelfth packet P11 into the fourth packet data unit PDU4.

[0072] refer to Figure 7C , the transmitter may receive a first status report SR1 including a fourth packet P3 corresponding to the second system time t2 from the receiver, and in response to the first status report SR1, the fourth packet P3 may be retransmitted by merging the fourth packet P3 into the third packet data unit PDU3. The transmitter may receive a second status report SR2 including the fourth packet P3 corresponding to the second system time t2 and the tenth packet P9 and the twelfth packet P11 corresponding to the fifth system time t5. Based on the second system time t2 and the fifth system time t5, the transmitter may determine that the fourth packet P3 has been retransmitted, and may retransmit the tenth packet P9 and the twelfth packet P11 by merging the tenth packet P9 and the twelfth packet P11 into the fourth packet data unit PDU4.

[0073] refer to Fig.7DDue to the influence of the communication network, the transmitter may not be able to receive the first status report SR1 including the fourth packet P3 corresponding to the second system time t2 from the receiver, and may receive the second status report SR2 including the fourth packet P3 corresponding to the second system time t2 and the tenth packet P9 and the twelfth packet P11 corresponding to the fifth system time t5. Based on the second system time t2 and the fifth system time t5, the transmitter may determine that the fourth packet P3 has not been retransmitted, and may retransmit the fourth packet P3, the tenth packet P9 and the twelfth packet P11 by merging the fourth packet P3, the tenth packet P9 and the twelfth packet P11 into the fourth packet data unit PDU4.

[0074] refer to Fig. 7E , the transmitter may receive a first status report SR1 including a fourth packet P3 corresponding to a second system time t2 from the receiver, and in response to the first status report SR1, the fourth packet P3 may be retransmitted by merging the fourth packet P3 into the third packet data unit PDU3. In addition, the transmitter may receive a second status report SR2 including a fourth packet P3, a tenth packet P9, and a twelfth packet P11 corresponding to a fifth system time t5 from the receiver. Although the fourth packet P3 has been merged into the third packet data unit PDU3 and has been retransmitted, the time corresponding to the fourth packet P3 included in the second status report SR2 is the fifth system time t5 and is different from the time corresponding to the first status report SR1, and therefore, in response to the second status report SR2, the transmitter may retransmit the fourth packet P3, the tenth packet P9, and the twelfth packet P11 by merging the fourth packet P3, the tenth packet P9, and the twelfth packet P11 into the fourth packet data unit PDU4.

[0075] refer to Figure 7F , the transmitter may receive a first status report SR1 including a fourth packet P3 corresponding to a second system time t2 from the receiver, and in response to the first status report SR1, the fourth packet P3 may be retransmitted by merging the fourth packet P3 into a third packet data unit PDU3. In addition, the transmitter may receive a second status report SR2 including a fourth packet P3 and a twelfth packet P11 corresponding to a seventh system time t7 from the receiver. In the example, the seventh system time t7 is a time after the status report processing period, and therefore, in response to the second status report SR2, the transmitter may retransmit the fourth packet P3 and the twelfth packet P11 by merging the fourth packet P3 and the twelfth packet P11 into a fourth packet data unit PDU4.

[0076] Figure 8 The format of a status report SR according to an exemplary embodiment is shown.

[0077] refer to Figure 8 , the status report SR may have a data form of a protocol data unit (PDU) for transmission in the corresponding layer. For example, the status report SR may include one or more bytes (e.g., Oct1, Oct2, ..., Octs14). The receiver may merge the sequence number of the successfully received data into the ACK_SN field F1 of the status report SR. When the receiver fails to receive the data, the receiver may insert the sequence number of the data into the NACK_SN field F2 of the status report SR and send the result to the transmitter. The status report may also include a segment offset (SO) field F3, wherein the segment offset field F3 may indicate the position of the PDU segment within the original PDU, such as in bytes. The SO field F3 may include SO start information (SOstart field), SO end information (SOend field) and NACK_SN field for each failed packet. Refer again to Figure 8 For example, the status report SR may also include a D / C field, an E1 field in Oct 3, and an E1 field and an E2 field in Oct 8. The meanings of these fields may refer to the existing format of the status report, or may be defined differently depending on the specific implementation.

[0078] The status report SR may include a control PDU type (CPT) field F_CPT, and the CPT field F_CPT may indicate the type of the control PDU. According to an exemplary embodiment, time information Info_t corresponding to the status report SR may be incorporated into the CPT field F_CPT. Although not shown, the CPT field F_CPT may include number information indicating a sequence number of the status report SR instead of or in addition to the time information Info_t.

[0079] Fig. 9 A method of operating a communication device according to an exemplary embodiment is shown. Specifically, Fig. 9 is a diagram showing a status report retransmission operation in a case where a communication device acts as a receiver of a packet.

[0080] refer to Fig. 9 In operation S410, a communication device (such as, for example Figure 1 The BS 10 or the UE 20 of the communication device may receive the first packet data unit from the transmitter. In operation S420, the communication device may determine whether there is a failed packet among the packets included in the first packet data unit.

[0081] When there is a failed packet in the first packet data unit, in operation S430, the communication device may send a first status report requesting retransmission of the failed packet included in the first packet data unit to the transmitter. In an exemplary embodiment, the communication device may merge time information corresponding to the time of sending the first status report and information about the failed packet into the first status report. When there is no failed packet in the first packet data unit, the communication device may receive a new packet data unit.

[0082] In operation S440, a predetermined retransmission time may pass, and in operation S450, the communication device may determine whether the failed packet has been re-received in response to the first status report. When the failed packet has not been re-received, in operation S460, the communication device may retransmit the first status report requesting retransmission of the failed packet. In an exemplary embodiment, the communication device may merge time information corresponding to the retransmission time of the first status report and information about the failed packet into the first status report to be retransmitted.

[0083] According to operation S440, a predetermined retransmission time may pass, and according to operation S450 the communication device may determine whether the failed packet has been re-received in response to the first status report, and thus, when the failed packet has been re-received, the communication device may complete the status report retransmission operation.

[0084] The communication device according to the exemplary embodiment may complete reception of a failed packet by repeatedly retransmitting a status report requesting retransmission on the failed packet at intervals of a predetermined retransmission time.

[0085] Fig.10 A method of operating a communication device according to an exemplary embodiment is shown. Specifically, Fig.10 is a diagram illustrating an exemplary embodiment of retransmitting a failed packet in response to a status report retransmission operation when a communication device acts as a transmitter of the packet.

[0086] refer to Fig.10 In operation S510, a communication device (such as, for example Figure 1 The BS 10 or the UE 20) may receive a first status report including the first time information and requesting retransmission of the first packet. In operation S520, in response to the first status report, the communication device may retransmit the first packet.

[0087] In operation S530, the communication device may receive a second status report including the second time information and requesting retransmission of the first packet. In operation S540, based on the first time information and the second time information, the communication device may determine whether the second status report is included in the status report processing period according to the first status report. In an example, the communication device may determine whether the transmission time of the second status report according to the second time information is included in a predetermined time period starting from the transmission time of the first status report according to the first time information.

[0088] When the second status report is not included in the status report processing period according to the first status report, the second status report is likely to be sent after the first packet is sent to the receiver according to operation S520, and this means that the receiver is likely to fail to receive the first packet sent according to operation S520. Therefore, in operation S550, the communication device may retransmit the first packet in response to the second status report.

[0089] When the second status report is included in the status report processing period according to the first status report, the second status report is likely to be sent before the first packet is sent to the receiver according to operation S520, and this means that the first packet is likely to be sent to the receiver according to operation S520. Therefore, the communication device may not retransmit the first packet in response to the second status report.

[0090] Fig.11 A method of operating a communication system according to an exemplary embodiment is shown. Specifically, Fig.11 1 is a diagram showing a method in which a transmitter 11 and a receiver 21 included in a communication system perform a status report retransmission operation according to a time sequence. Figure 4 , 9 and 10 are repeated descriptions.

[0091] Reference Fig.11 , at a first system time t1, the transmitter 11 may send a first packet data unit PDU1 to the receiver 21 at a processing time T310. The first packet data unit PDU1 may include a first packet P0 to an eighth packet P7. At a second system time t2, the receiver 21 may receive the first packet data unit PDU1, and may detect an error in a fourth packet P3 of the received first packet data unit PDU1 at a processing time T320. The receiver 21 may send a first status report SR1 requesting retransmission of the fourth packet P3 to the transmitter 11, and the first status report SR1 may include information about a second system time t2 corresponding to the system time at which the first status report SR1 was sent.

[0092] At the third system time t3, in response to the first status report SR1, the transmitter 11 may transmit a second packet data unit PDU2 including the fourth packet P3 in which an error has occurred to the receiver 21 at processing time T330. The second packet data unit PDU2 may include the ninth packet P8 to the fifteenth packet P14 and the fourth packet P3 requested to be retransmitted.

[0093] At the fourth system time t4, the receiver 21 may transmit the second status report SR2 including the information about the fourth packet P3 to the transmitter 11 at the processing time T340 to ensure the retransmission about the fourth packet P3 after a predetermined time has passed from the second system time t2. The receiver 21 may incorporate the information about the fourth system time t4 corresponding to the system time at which the second status report SR2 is transmitted into the second status report SR2.

[0094] At the fifth system time t5, in response to the second status report SR2, the transmitter 11 can determine whether the second status report SR2 is included in the status report processing period T_sp at the processing time T350 based on the second system time t2 and the fourth system time t4. Because the fourth system time t4 at which the second status report SR2 is transmitted is included in the status report processing period T_sp starting from the second system time t2, the transmitter 11 may not retransmit the fourth packet P3 despite the second status report SR2.

[0095] According to an exemplary embodiment, when the second status report SR2 is included in the status report processing period T_sp corresponding to the first status report SR1, due to the second packet data unit PDU2, the receiver 21 is likely to receive a retransmission of the fourth packet P3, and therefore, despite the presence of the second status report SR2, the transmitter 11 may not retransmit the fourth packet P3 to prevent repeated retransmission of the signal.

[0096] Fig.12 A method of operating a communication system according to an exemplary embodiment is shown. Specifically, Fig.12 1 is a diagram showing a method in which the transmitter 11 and the receiver 21 included in the communication system perform a status report retransmission operation according to a time sequence. Fig.12 Relative to Fig.11 Repeated description of .

[0097] refer to Fig.12, at a first system time t1, the transmitter 11 may send a first packet data unit PDU1 to the receiver 21 at a processing time T410. The first packet data unit PDU1 may include a first packet P0 to an eighth packet P7. At a second system time t2, the receiver 21 may receive the first packet data unit PDU1, and may detect an error in a fourth packet P3 of the received first packet data unit PDU1 at a processing time T420. The receiver 21 may send a first status report SR1 requesting retransmission of the fourth packet P3 to the transmitter 11, and the first status report SR1 may include information about a second system time t2 corresponding to the system time at which the first status report SR1 was sent.

[0098] At the third system time t3, in response to the first status report SR1, the transmitter 11 may transmit a second packet data unit PDU2 including the fourth packet P3 in which an error has occurred to the receiver 21 at processing time T430. The second packet data unit PDU2 may include the ninth packet P8 to the fifteenth packet P14 and the fourth packet P3 requested to be retransmitted.

[0099] At the fourth system time t4, the receiver 21 may transmit the second status report SR2 including the information about the fourth packet P3 to the transmitter 11 at the processing time T440 to ensure the retransmission about the fourth packet P3 after a predetermined time has passed from the second system time t2. The receiver 21 may incorporate the information about the fourth system time t4 corresponding to the system time at which the second status report SR2 is transmitted into the second status report SR2.

[0100] At the fifth system time t5, in response to the second status report SR2, the transmitter 11 may determine whether the second status report SR2 is included in the status report processing period T_sp based on the second system time t2 and the fourth system time t4 at the processing time T450. Since the fourth system time t4 at which the second status report SR2 is transmitted is not included in the status report processing period T_sp starting from the second system time t2, the transmitter 11 may transmit the third packet data unit PDU3 including the fourth packet P3 in which an error has occurred to the receiver 21 in response to the second status report SR2. The third packet data unit PDU3 may include the sixteenth packet P15 to the twenty-second packet P21 and the fourth packet P3 requested to be retransmitted.

[0101] According to an exemplary embodiment, when the second status report SR2 is not included in the status report processing period T_sp corresponding to the first status report SR1, the receiver 21 is likely to fail to receive the retransmission of the fourth packet P3 due to the second packet data unit PDU2, and therefore, the transmitter 11 can retransmit the fourth packet P3 in response to the second status report SR2 to prevent a reduction in the reliability of signal transmission.

[0102] In a similar way to the above Fig.12 In the described alternative embodiment, the sequential status report number may be used instead of the processing time and the system time. The repeated description may be omitted.

[0103] Here, the transmitter 11 may send a first packet data unit PDU1 to the receiver 21, wherein the first packet data unit PDU1 may include a first packet P0 to an eighth packet P7. Next, the receiver 21 may receive the first packet data unit PDU1, and may detect an error in a fourth packet P3 in the received first packet data unit PDU1. The receiver 21 may then send a first status report SR1 requesting retransmission of the fourth packet P3 to the transmitter 11, wherein the first status report SR1 includes information about a sequential status report number of the first status report SR1.

[0104] In response to receiving the first status report SR1, the transmitter 11 may transmit a second packet data unit PDU2 including the fourth packet P3 in which an error has previously occurred to the receiver 21. The second packet data unit PDU2 may include ninth to fifteenth packets P8 to P14 and the fourth packet P3 requested to be retransmitted.

[0105] Next, the receiver 21 may send a second status report SR2 including information about the fourth packet P3 to the transmitter 11 to ensure retransmission about the fourth packet P3. The receiver 21 may incorporate information about the sequential status report number of the second status report SR2.

[0106] In response to the second status report SR2, the transmitter 11 may determine whether one or more failed packets in the second status report have been recently retransmitted based on a consideration of the received status report sequence number and the previously retransmitted failed packets. Because the sequence number of the second status report SR2 is greater than the sequence number of the first status report SR1, the transmitter 11 may send a third packet data unit PDU3 including the fourth packet P3 in which an error has occurred to the receiver 21 in response to the second status report SR2. The third packet data unit PDU3 may include the sixteenth packet P15 to the twenty-second packet P21 and the fourth packet P3 requested to be retransmitted.

[0107] In a further alternative embodiment, in addition to the received sequence status report number, the transmitter's determination as to whether a previously retransmitted failed packet should be retransmitted again is also based on a first time between the time the transmitter sent the first failed packet and the time the transmitter received the first status report indicating the first failed packet, such that if the first time is less than a second time between the time the transmitter retransmitted the first failed packet and the time the transmitter received the next sequence numbered status report indicating that the packet has failed again, the transmitter retransmits the failed packet again without regard to any timing information from the receiver.

[0108] Therefore, according to these alternative embodiments, when the failed packet indicated by the second status report SR2 is not included in the status report SR1 or has not been retransmitted by the transmitter, the receiver 21 is unlikely to receive the retransmission of the fourth packet P3 due to the second packet data unit PDU2, and accordingly, the transmitter 11 will retransmit the fourth packet P3 in response to the second status report SR2 to enhance communication reliability.

[0109] Fig.13 The operation of the communication device according to the exemplary embodiment is shown. Specifically, Fig.13 FIG. 4 shows the operation of a communication device for adaptively determining a retransmission time. Figures 9 to 12 Repeated description of .

[0110] refer to Fig.13 In operation S610, a communication device (such as, for example Figure 1 The BS 10 or UE 20 of the communication device can evaluate the surrounding communication environment of the communication device. In an example, the communication device can evaluate the communication environment by measuring the data throughput of the device for sending data.

[0111] In operation S620, based on the communication environment, the communication device may determine a retransmission time. In an example, when the data throughput is high, the communication device may shorten the retransmission time. For example, when the data throughput is higher than a predetermined value, the communication device may shorten the retransmission time.

[0112] In operation S630, based on the determined retransmission time, the communication device may retransmit a status report requesting retransmission of the failed packet. In an example, the communication device may determine whether a failed packet has been received when the retransmission time has passed since the previously sent status report was sent, and when the failed packet is not received during the retransmission time, the status report requesting retransmission of the failed packet may be retransmitted.

[0113] Fig.14 A communication device 1000 according to an example embodiment is shown.

[0114] refer to Fig.14 , the communication device 1000 may include: an application specific integrated circuit (ASIC) 1010, an application specific instruction set processor (ASIP) 1030 connected to the ASIC, a memory 1050 connected to the ASIP, a main processor 1070 connected to the ASIC and the ASIP, and a main memory 1090 connected to the main processor. Two or more of the ASIC 1010, the ASIP 1030, and the main processor 1070 may communicate with each other. In addition, at least two of the ASIC 1010, the ASIP 1030, the memory 1050, the main processor 1070, and the main memory 1090 may be embedded in one chip.

[0115] ASIP 1030 is an integrated circuit customized for a specific purpose, which can support a dedicated instruction set for a specific application and can run the instructions contained in the instruction set. Memory 1050 can communicate with ASIP 1030 and, as a non-temporary storage device, can store multiple instructions run by ASIP 1030. For example, memory 1050 can include any type of memory accessible by ASIP 1030, such as random-access memory (RAM), read-only memory (ROM), tape, disk, optical disk, volatile memory, non-volatile memory, or a combination thereof, which are non-limiting examples.

[0116] The main processor 1070 may control the communication device 1000 by executing a plurality of instructions. For example, the main processor 1070 may control the ASIC 1010 and the ASIP 1030, and may process data received via a communication network or process a user's input to the communication device 1000. The main memory 1090 may communicate with the main processor 1070, and as a non-transitory storage device, may store a plurality of instructions executed by the main processor 1070. For example, the main memory 1090 may include any type of memory accessible by the main processor 1070, such as RAM, ROM, tape, disk, optical disk, volatile memory, non-volatile memory, or a combination thereof, which are non-limiting examples.

[0117] The communication method according to one or more of the above exemplary embodiments may be performed by Fig.14 In some embodiments, the communication method and Figure 1At least one operation among the operations of the signal processors 100 and 300 may be implemented as a plurality of instructions stored in the memory 1050. The ASIP 1030 may execute the operations and Figure 1 At least one operation among at least some of the operations of the signal processors 100 and 300. In some embodiments, from the communication method and Figure 1 At least one of the operations of the signal processors 100 and 300 may be implemented as a hardware block designed by logic synthesis, etc., and may be included in the ASIC 1010. In some embodiments, the communication method and Figure 1 At least one of the operations of the signal processors 100 and 300 may be implemented as a plurality of instructions stored in the main memory 1090, and the main processor 1070 may execute the operations and Figure 1 At least one operation among at least some of the operations of the signal processors 100 and 300.

[0118] While the inventive concept has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the relevant art that various changes in form and details may be made without departing from the scope of the inventive concept as more particularly defined by the appended claims and their equivalents.

Claims

1. A method of operating a communication system, the communication system comprising a receiver, the method comprising: receiving, by the receiver, at least one first packet; sending, by the receiver, a first status report requesting retransmission of a first failed packet among the at least one first packet, and initiating a first processing period for the first status report; receiving, by the receiver during the first processing period, at least one second packet; as well as sending, by the receiver during the first processing period, a second status report requesting retransmission of a second failed packet among the at least one second packet, wherein the first processing period comprises an expected processing period based on a difference between reception of the at least one first packet and reception of the at least one second packet, Wherein, the first processing period ends according to the earlier of: completion of the expected processing period of retransmission of the first failed packet to the receiver, or actual reception of the retransmitted first failed packet by the receiver.

2. The method according to claim 1, wherein: The first status report includes at least one of first time information corresponding to a reception time of the first failed packet or a transmission time of the first status report, or first number information indicating a sequence number of the first status report, and The second status report includes at least one of second time information corresponding to a reception time of the second failed packet or a transmission time of the second status report, or second number information indicating a sequence number of the second status report.

3. The method according to claim 2, wherein: The first time information is included in a control protocol data unit type (CPT) field of a header area of ​​the first status report, and The second time information is included in a CPT field of a header area of ​​the second status report.

4. The method according to claim 2, further comprising: The retransmitted first failed packet and the retransmitted second failed packet are received by the receiver based on the first status report and the second status report, respectively.

5. The method according to claim 2, wherein: The second status report includes information about the first failed packet and information about the second failed packet, and the method further includes: Determining, by the transmitter, a failed packet to be retransmitted based on the first time information and the second time information; as well as Based on a result of the determination, the first failed packet and the second failed packet are retransmitted by the transmitter.

6. The method according to claim 5, wherein: The second status report also includes the first time information corresponding to the first failed packet and the second time information corresponding to the second failed packet.

7. The method according to claim 1, wherein: The first status report includes a first number corresponding to an output order of the first status report, and the second status report includes a second number corresponding to an output order of the second status report, and the method further includes: Based on the first number and the second number, the first failed packet and the second failed packet are retransmitted by the transmitter.

8. The method according to claim 1, further comprising: retransmitting, by the receiver within a status report processing period subsequent to the sending of the first status report, a third status report requesting retransmission of the first failed packet, in, The third status report includes third time information corresponding to a sending time of the third status report.

9. The method according to claim 8, wherein: The first status report includes first time information corresponding to a sending time of the first status report, and the method further includes: In response to the first status report, sending, by a transmitter, the first failed packet; receiving, by the transmitter, the third status report; determining, by the transmitter, whether the third status report is included in the status report processing period based on the first time information and the third time information; as well as The first failed packet is retransmitted by the transmitter in response to the third status report based on whether the third status report is included in the status report processing period.

10. The method according to claim 9, wherein: The retransmission of the first failed packet includes: When the third status report is not included in the status report processing period, the first failed packet is retransmitted by the transmitter in response to the third status report.

11. The method according to claim 8, further comprising: evaluating, by the receiver, a communication environment; determining, by the receiver, a retransmission time based on an evaluated communication environment; determining, by the receiver, whether the first failed packet has been received when the retransmission time has elapsed from the sending of the third status report; as well as When the first failed packet has not been received, a fourth status report is sent by the receiver requesting a retransmission of the first failed packet.

12. The method according to claim 11, wherein: The communication environment includes data throughput, and the determining includes: When the data throughput is higher than a predetermined value, the retransmission time is shortened.

13. A method of operating a communication device, the method comprising: Sending, by a transmitter, a first packet data unit; A first status report requesting retransmission of a first failed packet having an error among at least one first packet included in the first packet data unit is received by the transmitter, wherein: The first status report includes first time information indicating a time when the first status report is sent and first packet information indicating a first failed packet; retransmitting, by the transmitter, a first failed packet indicated in the first status report by merging the first failed packet into a second packet data unit; receiving, by the transmitter, a second status report requesting retransmission of a first failed packet, wherein the second status report includes second time information indicating a time when the second status report is sent and first packet information indicating the first failed packet; as well as Based on determining whether the second time information is included in a status report processing period starting from the first time information, it is determined whether to retransmit the first failed packet indicated in the second status report.

14. The method according to claim 13, further comprising: If the second time information is not included in the status report processing period, the first failed packet indicated in the second status report is retransmitted by the transmitter by merging the first failed packet into a third packet data unit.

15. The method according to claim 14, further comprising: If the second time information is included in the status report processing period, the first failed packet indicated in the second status report is not retransmitted.

16. A communication system comprising: a transmitter configured to transmit the first packet data unit and the second packet data unit to the receiver; and The receiver is configured to receive the first packet data unit and the second packet data unit from the transmitter, wherein: The receiver is further configured to: determining whether there is a first failed packet with an error among the first packet data units, sending a first status report requesting retransmission of the first failed packet at a first time, the first status report comprising first time information indicating the first time and first packet information indicating the first failed packet, and sending a second status report requesting retransmission of the first failed packet at a second time, the second status report comprising second time information indicating the second time and first packet information indicating the first failed packet, in, The transmitter is also configured to: in response to receiving the first status report, retransmitting the first failed packet by merging the first failed packet into a second packet data unit, receiving the second status report, and Based on determining whether the second time information is included in a status report processing period starting from the first time information, it is determined whether to retransmit the first failed packet indicated in the second status report.

17. The communication system according to claim 16, wherein the transmitter is further configured to: If the second time information is not included in the status report processing period, the first failed packet indicated in the second status report is retransmitted by merging the first failed packet into a third packet data unit.

18. The communication system according to claim 17, wherein: The transmitter is also configured to: If the second time information is included in the status report processing period, the second failed packet indicated in the second status report is not retransmitted.

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