Mac subheader and mac SDU pairs encoded with error detection codes

Abstract

Embodiments of the invention relate to a MAC PDU comprising MAC subheader and MAC SDU pairs encoded with error detection codes. More specifically, a first communication device (100) transmits a MAC PDU to a second communication device (300). The MAC PDU comprises at least one MAC subheader and MAC SDU pair. The at least one MAC subheader and MAC SDU pair comprises a plurality of data fields appended to the MAC subheader and being encoded with a first error detection code, and the plurality of data fields comprising a first data field indicating a length of a pay load of the MAC SDU and a second data field indicating a length of at least the MAC subheader and a header stack of the MAC SDU, and the MAC subheader and the header stack are encoded with a second error detection code. Furthermore, embodiments of the invention also relate to a first and a second communication device, corresponding methods and a computer program.

Description

[0001] MAC SUBHEADER AND MAC SDU PAIRS ENCODED WITH ERROR DETECTION CODES

[0002] TECHNICAL FIELD

[0003] Embodiments of the invention relate to a MAC PDU comprising one or more MAC subheader and MAC SDU pairs encoded with error detection codes. Furthermore, embodiments of the invention also relate to a first and a second communication device, corresponding methods and a computer program.

[0004] BACKGROUND

[0005] The 3rd Generation Partnership Project (3GPP) is a collaboration between groups of telecommunications standards associations. The project’s mission is to establish cellular telecommunications network standards and maintain them. As we move towards the communication networks in the future, the complexity of these networks is expected to increase significantly.

[0006] Artificial Intelligence (Al) and Machine Learning (ML) are being seen as solutions to many of these challenges, providing pragmatic solutions that can entirely change the future of wireless network technologies. Al has emerged as a powerful technology that improves system performance and enables new features in 5G and beyond.

[0007] One of the key challenges in future communication networks is error correction at the application level. For some types of services, like video, error correction at the application level can be capable of dealing with bit level transmission errors. However, in the current 3GPP new radio (NR) 5G standard the radio bearer, in the link layer, hides bit errors via retransmission to the price of increased transmission latency.

[0008] SUMMARY

[0009] An objective of embodiments of the invention is to provide a solution which mitigates or solves the drawbacks and problems of conventional solutions.

[0010] Another objective of embodiments of the invention is to provide a MAC PDU with improved error detection capabilities compared to a conventional MAC PDU.

[0011] The above and further objectives are solved by the subject matter of the independent claims.

[0012] Further embodiments of the invention can be found in the dependent claims.

[0013] According to a first aspect of the invention, the above mentioned and other objectives are achieved with a first communication device configured to: transmit a medium access control, MAC, packet data unit, PDU, to a second communication device, the MAC PDU comprising at least one MAC subheader and MAC service data unit, SDU, pair, wherein the at least one MAC subheader and MAC SDU pair comprises a plurality of data fields appended to the MAC subheader and being encoded with a first error detection code, the plurality of data fields comprising a first data field indicating a length of a pay load of the MAC SDU and a second data field indicating a length of at least the MAC subheader and a header stack of the MAC SDU, wherein the MAC subheader and the header stack are encoded with a second error detection code.

[0014] An advantage of the first communication device according to the first aspect is that the MAC PDU can be forwarded to the MAC demultiplexing function even if a transport block carrying the MAC PDU has an error detection code error since the MAC subheader and the header stack are protected against bit errors that may have gone uncorrected through a channel decoding process. In an implementation form of a first communication device according to the first aspect, the plurality of data fields is preappended to the MAC subheader.

[0015] An advantage with this implementation form is that when the data fields are located before the MAC subheader in the MAC PDU, the data fields can be found even if the MAC subheader has bit error such that its size could not be detected. Since the size of the MAC subheader and the MAC SDU can be derived from the plurality of data fields it is possible find a next MAC subheader and MAC SDU pair also in the case when the current MAC subheader is corrupted.

[0016] In an implementation form of a first communication device according to the first aspect, the first error detection code is arranged: between the plurality of data fields and the MAC subheader; or before the plurality of data fields; or between two data fields of the plurality of data fields.

[0017] An advantage with this implementation form is that different locations of the first error detection code is possible.

[0018] In an implementation form of a first communication device according to the first aspect, the plurality of data fields and the first error detection code are encoded with a first error correction code.

[0019] An advantage with this implementation form is that it is possible to correct transmission errors and find the length of the MAC subheader and MAC SDU even if the MAC subheader and part of the MAC SDU have bit errors.

[0020] In an implementation form of a first communication device according to the first aspect, the header stack is arranged between the MAC subheader and the pay load of the MAC SDU.

[0021] An advantage with this implementation is that it follows the pattern in which the MAC subheader and header stack normally is arranged.

[0022] In an implementation form of a first communication device according to the first aspect, the second error detection code is arranged: between the header stack and the pay load of the MAC SDU; or between the header stack and the MAC subheader; or before the MAC subheader.

[0023] An advantage with this implementation form is that different locations of the second error detection code is possible.

[0024] In an implementation form of a first communication device according to the first aspect, the second data field indicates a length of the MAC subheader, the header stack and the second error detection code.

[0025] An advantage with this implementation form is about layering information since the function that calculates the location of the next MAC subheader does not need to know about the size of the second error detection code.

[0026] In an implementation form of a first communication device according to the first aspect, the second error detection code is computed over the MAC subheader and the header stack. An advantage with this implementation form is that bit errors can be detected in the MAC subheader and the header stack.

[0027] In an implementation form of a first communication device according to the first aspect, the MAC subheader, the header stack and the second error detection code are encoded with a second error correction code.

[0028] An advantage with this implementation form is that errors in the MAC subheader, the header stack and the second error detection code can be corrected.

[0029] In an implementation form of a first communication device according to the first aspect, the second data field indicates a length of the MAC subheader, the header stack and the second error detection code encoded with the second error correction code.

[0030] An advantage with this implementation form is that the location of the next MAC subheader and MAC SDU can be computed without first decoding the MAC subheader and header stack.

[0031] In an implementation form of a first communication device according to the first aspect, the plurality of data fields comprises a third data field indicating the error correction encoding of the MAC subheader, the header stack and the second error detection code.

[0032] An advantage with this implementation form is that it allows the transmitter to select which MAC SDUs are more important by selectively applying protection to these MAC SDUs. Another advantage is that the type of error detection encoding can be set for each MAC subheader and MAC SDU pair.

[0033] In an implementation form of a first communication device according to the first aspect, the third data field comprises a bit flag.

[0034] In an implementation form of a first communication device according to the first aspect, the header stack comprises one or more headers in a group comprising: a RLC header, a PDCP header, a SDAP header, an IP header, a UDP Lite header, and an RTP header.

[0035] An advantage with this implementation form is that it e.g., can be used for multimedia applications where often latency is an important issue.

[0036] In an implementation form of a first communication device according to the first aspect, the first error detection code is a first cyclical redundancy check, CRC, code and the second error detection code is a second CRC code.

[0037] In an implementation form of a first communication device according to the first aspect, the first communication device is configured to: transmit a control message to the second communication device, the control message indicating the transmission of the MAC PDU comprising the at least one MAC subheader and MAC SDU pair.

[0038] An advantage with this implementation form is that the second communication device is informed about the format of the MAC PDU. In an implementation form of a first communication device according to the first aspect, the indication of the transmission of the MAC PDU is given by a RNTI value.

[0039] In an implementation form of a first communication device according to the first aspect, the MAC PDU comprises a plurality of MAC subheader and MAC SDU pairs appended to each other in the MAC PDU.

[0040] An advantage with this implementation form is that the MAC PDU processing can continue on to the next MAC subheader and MAC SDU pair independent of the result of the second error detection in the current MAC subheader and MAC SDU pair.

[0041] According to a second aspect of the invention, the above mentioned and other objectives are achieved with a second communication device configured to: receive a MAC PDU from a first communication device, the MAC PDU comprising at least one MAC subheader and MAC SDU pair, wherein the at least one MAC subheader and MAC SDU pair comprises a plurality of data fields appended to the MAC subheader and being encoded with a first error detection code, the plurality of data fields comprising a first data field indicating a length of a pay load of the MAC SDU and a second data field indicating a length of at least the MAC subheader and a header stack of the MAC SDU, wherein the MAC subheader and the header stack are encoded with a second error detection code; check the first error detection code over the plurality of data fields to produce a first error detection outcome; check the second error detection code over the MAC subheader and the header stack based on the second data field when the first error detection outcome is valid to produce a second error detection outcome; and demultiplex the MAC subheader and MAC SDU pair according to a MAC protocol when the second error detection outcome is valid.

[0042] An advantage of the second communication device according to the second aspect is that

[0043] In an implementation form of a second communication device according to the second aspect, the second communication device is configured to: discard the remaining MAC subheader and MAC SDU pairs of the MAC PDU when the first error detection outcome is invalid.

[0044] An advantage with this implementation form is that the MAC PDU can be forwarded to the MAC demultiplexing function even if a transport block carrying the MAC PDU has an error detection code error since the MAC subheader and the header stack are protected against bit errors that may have gone uncorrected through a channel decoding process.

[0045] In an implementation form of a second communication device according to the second aspect, the second communication device is configured to: compute a position of a next MAC subheader and MAC SDU pair based on the first data field when the first error detection outcome is valid.

[0046] An advantage with this implementation form is that the next MAC subheader and MAC SDU pair in the MAC PDU can be found independent of the result, i.e., also when there are bit errors according to the second error detection, of the second error detection outcome in the current MAC subheader and MAC SDU pair.

[0047] In an implementation form of a second communication device according to the second aspect, the plurality of data fields is preappended to the MAC subheader. An advantage with this implementation form is that when the data fields are located before the MAC subheader in the MAC PDU, the data fields can be found even if the MAC subheader has bit error such that its size could not be detected. Since the size of the MAC subheader and the MAC SDU can be derived from the plurality of data fields it is possible find a next MAC subheader and MAC SDU pair also in the case when the current MAC subheader is corrupted.

[0048] In an implementation form of a second communication device according to the second aspect, the first error detection code is arranged: between the plurality of data fields and the MAC subheader; or before the plurality of data fields; or between two data fields of the plurality of data fields.

[0049] An advantage with this implementation form is that different locations of the first error detection code is possible.

[0050] In an implementation form of a second communication device according to the second aspect, the plurality of data fields and the first error detection code are encoded with a first error correction code, and wherein the second communication device is configured to: decode the plurality of data fields and the first error detection code based on the first error correction code.

[0051] An advantage with this implementation form is that it is possible to correct transmission errors and find the length of the MAC subheader and MAC SDU even if the MAC subheader and part of the MAC SDU have bit errors.

[0052] In an implementation form of a second communication device according to the second aspect, the header stack is arranged between the MAC subheader and the payload of the MAC SDU.

[0053] An advantage with this implementation is that it follows the pattern in which the MAC subheader and header stack normally is arranged.

[0054] In an implementation form of a second communication device according to the second aspect, the second error detection code is arranged: between the header stack and the pay load of the MAC SDU; or between the header stack and the MAC subheader; or before the MAC subheader.

[0055] An advantage with this implementation form is that different locations of the second error detection code is possible.

[0056] In an implementation form of a second communication device according to the second aspect, the second data field indicates a length of the MAC subheader, the header stack and the second error detection code.

[0057] An advantage with this implementation form is about layering information since the function that calculates the location of the next MAC subheader does not need to know about the size of the second error detection code.

[0058] In an implementation form of a second communication device according to the second aspect, the second error detection code is computed over the MAC subheader and the header stack. An advantage with this implementation form is that bit errors can be detected in the MAC subheader and the header stack.

[0059] In an implementation form of a second communication device according to the second aspect, the MAC subheader, the header stack and the second error detection code are encoded with a second error correction code, and wherein the second communication device is configured to: decode the MAC subheader, the header stack and the second error detection code based on the second error correction code.

[0060] An advantage with this implementation form is that errors in the MAC subheader, the header stack and the second error detection code can be corrected.

[0061] In an implementation form of a second communication device according to the second aspect, the second data field indicates a length of the MAC subheader, the header stack and the second error detection code encoded with the second error correction code.

[0062] An advantage with this implementation form is that the location of the next MAC subheader and MAC SDU can be computed without first decoding the MAC subheader and header stack.

[0063] In an implementation form of a second communication device according to the second aspect, the plurality of data fields comprises a third data field indicating the error correction encoding of the MAC subheader, the header stack and the second error detection code.

[0064] An advantage with this implementation form is that it allows the transmitter to select which MAC SDUs are more important by selectively applying protection to these MAC SDUs. Another advantage is that the type of error detection encoding can be set for each MAC subheader and MAC SDU pair.

[0065] In an implementation form of a second communication device according to the second aspect, the third data field comprises a bit flag.

[0066] In an implementation form of a second communication device according to the second aspect, the header stack comprises one or more headers in a group comprising: an RLC header, a PDCP header, a SDAP header, an IP header, a UDP Lite header, and an RTP header.

[0067] An advantage with this implementation form is that it e.g., can be used for multimedia applications where often latency is an important issue.

[0068] In an implementation form of a second communication device according to the second aspect, the first error detection code is a first cyclical redundancy check, CRC, code and the second error detection code is a second CRC code.

[0069] In an implementation form of a second communication device according to the second aspect, the second communication device is configured to: receive a control message from the first communication device, the control message indicating the transmission of the MAC PDU comprising the at least one MAC subheader and MAC SDU pair. An advantage with this implementation form is that the second communication device is informed about the format of the MAC PDU.

[0070] In an implementation form of a second communication device according to the second aspect, the indication of the transmission of the MAC PDU is given by a RNTI value.

[0071] In an implementation form of a second communication device according to the second aspect, the MAC PDU comprises a plurality of MAC subheader and MAC SDU pairs appended to each other in the MAC PDU.

[0072] An advantage with this implementation form is that the MAC PDU processing can continue on to the next MAC subheader and MAC SDU pair independent of the result of the second error detection in the current MAC subheader and MAC SDU pair.

[0073] According to a third aspect of the invention, the above mentioned and other objectives are achieved with a method for a first communication device, the method comprises: transmitting a MAC PDU to a second communication device (300), the MAC PDU comprising at least one MAC subheader and MAC SDU pair, wherein the at least one MAC subheader and MAC SDU pair comprises a plurality of data fields appended to the MAC subheader and being encoded with a first error detection code, the plurality of data fields comprising a first data field indicating a length of a pay load of the MAC SDU and a second data field indicating a length of at least the MAC subheader and a header stack of the MAC SDU, wherein the MAC subheader and the header stack are encoded with a second error detection code.

[0074] The method according to the third aspect can be extended into implementation forms corresponding to the implementation forms of the first communication device according to the first aspect. Hence, an implementation form of the method comprises the feature(s) of the corresponding implementation form of the first communication device.

[0075] The advantages of the methods according to the third aspect are the same as those for the corresponding implementation forms of the first communication device according to the first aspect.

[0076] According to a fourth aspect of the invention, the above mentioned and other objectives are achieved with a method for a second communication device, the method comprises: receiving a MAC PDU from a first communication device, the MAC PDU comprising at least one MAC subheader and MAC SDU pair, wherein the at least one MAC subheader and MAC SDU pair comprises a plurality of data fields appended to the MAC subheader and being encoded with a first error detection code, the plurality of data fields comprising a first data field indicating a length of a pay load of the MAC SDU and a second data field indicating a length of at least the MAC subheader and a header stack of the MAC SDU, wherein the MAC subheader and the header stack are encoded with a second error detection code; checking the first error detection code over the plurality of data fields to produce a first error detection outcome; checking the second error detection code over the MAC subheader and the header stack based on the second data field when the first error detection outcome is valid to produce a second error detection outcome; and demultiplexing the MAC subheader and MAC SDU pair according to a MAC protocol when the second error detection outcome is valid.

[0077] The method according to the fourth aspect can be extended into implementation forms corresponding to the implementation forms of the second communication device according to the second aspect. Hence, an implementation form of the method comprises the feature(s) of the corresponding implementation form of the second communication device. The advantages of the methods according to the fourth aspect are the same as those for the corresponding implementation forms of the second communication device according to the second aspect.

[0078] Embodiments of the invention also relate to a computer program, characterized in program code, which when run by at least one processor causes the at least one processor to execute any method according to embodiments of the invention. Further, embodiments of the invention also relate to a computer program product comprising a computer readable medium and the mentioned computer program, wherein the computer program is included in the computer readable medium, and may comprises one or more from the group of: read-only memory (ROM), programmable ROM (PROM), erasable PROM (EPROM), flash memory, electrically erasable PROM (EEPROM), hard disk drive, etc.

[0079] Further applications and advantages of embodiments of the invention will be apparent from the following detailed description.

[0080] BRIEF DESCRIPTION OF THE DRAWINGS

[0081] The appended drawings are intended to clarify and explain different embodiments of the invention, in which:

[0082] - Fig. 1 shows a first communication device according to embodiments of the invention;

[0083] - Fig. 2 shows a flow chart of a method for a first communication device according to embodiments of the invention;

[0084] - Fig. 3 shows a second communication device according to embodiments of the invention;

[0085] - Fig . 4 shows a flow chart of a method for a second communication device according to embodiments of the invention;

[0086] - Fig. 5 shows a communication system according to embodiments of the invention;

[0087] - Fig. 6-8 shows a MAC PDU according to embodiments of the invention;

[0088] - Fig. 9-11 shows MAC subheader and MAC SDU pairs encoded with error detection codes according to embodiments of the invention;

[0089] - Fig. 12-14 shows MAC subheader and MAC SDU pairs further encoded with error correct codes according to embodiments of the invention;

[0090] - Fig. 15 shows a MAC PDU comprising a plurality of MAC subheader and MAC SDU pairs according to embodiments of the invention; and

[0091] - Fig. 16 and 17 shows algorithms for processing a MAC PDU according to embodiments of the invention.

[0092] DETAILED DESCRIPTION

[0093] In current 3GPP NR standard Release 18 a transport block (TB) is sent on the downlink (DL) shared channel or uplink (UL) shared channel using a hybrid automatic repeat request (HARQ)-process. When the TB has been successfully received, the processing continues in the MAC disassembly and demultiplexing entity of the receiver. Successfully received means that the TB has passed a cyclic redundancy check (CRC) check procedure, and a TB may be re-transmitted multiple times by the HARQ-process if an error is detected in the CRC check procedure, thus increasing the transfer time of the TB. If the TB does not pass the CRC check, the MAC protocol and other protocols above cannot reliably process their respective headers.

[0094] In “Congestion control in wireless links based on selective delivery of erroneous packets”, the concept of selective link layer partial check summing is used to allow bit errors in less sensitive parts of data. In conventional solutions, since only parts of the packet are covered by checksum, bit errors are allowed in less important parts of packets. The selecting link layer partial checksum is used on video streams in a dynamic manner to allow more faulty packages when the network is too heavily loaded to reduce the router queues.

[0095] However, there is a need for improved error detection capabilities of MAC PDUs. Thus, it is herein disclosed a first communication device, a second communication device and methods thereof providing such error detection capabilities. Fig. 1 shows a first communication device 100 according to an embodiment of the invention. In the embodiment shown in Fig. 1, the first communication device 100 comprises a processor 102, a transceiver 104 and a memory 106. The processor 102 is coupled to the transceiver 104 and the memory 106 by communication means 108 known in the art. The first communication device 100 may be configured for wireless and / or wired communications in a communication system. The wireless communication capability may be provided with an antenna or antenna array 110 coupled to the transceiver 104, while the wired communication capability may be provided with a wired communication interface 112 e.g., coupled to the transceiver 104.

[0096] The processor 102 may be referred to as one or more general-purpose central processing units (CPUs), one or more digital signal processors (DSPs), one or more application-specific integrated circuits (ASICs), one or more field programmable gate arrays (FPGAs), one or more programmable logic devices, one or more discrete gates, one or more transistor logic devices, one or more discrete hardware components, or one or more chipsets. The memory 106 may be a read-only memory, a random access memory (RAM), or a non-volatile RAM (NVRAM). The transceiver 104 may be a transceiver circuit, a power controller, or an interface providing capability to communicate with other communication modules or communication devices, such as network nodes and network servers. The transceiver 104, memory 106 and / or processor 102 may be implemented in separate chipsets or may be implemented in a common chipset.

[0097] That the first communication device 100 is configured to perform certain actions can in this disclosure be understood to mean that the first communication device 100 comprises suitable means and devices, such as e.g., the processor 102 and the transceiver 104, configured to perform the actions.

[0098] According to embodiments of the invention the first communication device 100 is configured to: transmit a MAC PDU to a second communication device 300, the MAC PDU comprising at least one MAC subheader and MAC service data unit, SDU, pair, wherein the at least one MAC subheader and MAC SDU pair comprises a plurality of data fields appended to the MAC subheader and being encoded with a first error detection code, the plurality of data fields comprising a first data field indicating a length of a pay load of the MAC SDU and a second data field indicating a length of at least the MAC subheader and a header stack of the MAC SDU, wherein the MAC subheader and the header stack are encoded with a second error detection code.

[0099] Furthermore, in an embodiment of the invention, the first communication device 100 comprises a transceiver configured to: transmit a MAC PDU to a second communication device 300, the MAC PDU comprising at least one MAC subheader and MAC service data unit, SDU, pair, wherein the at least one MAC subheader and MAC SDU pair comprises a plurality of data fields appended to the MAC subheader and being encoded with a first error detection code, the plurality of data fields comprising a first data field indicating a length of a pay load of the MAC SDU and a second data field indicating a length of at least the MAC subheader and a header stack of the MAC SDU, wherein the MAC subheader and the header stack are encoded with a second error detection code.

[0100] Moreover, in yet another embodiment of the invention, the first communication device 100 for a communication system 500 comprises a processor and a memory having computer readable instructions stored thereon which, when executed by the processor, cause the processor to: transmit a MAC PDU to a second communication device 300, the MAC PDU comprising at least one MAC subheader and MAC service data unit, SDU, pair, wherein the at least one MAC subheader and MAC SDU pair comprises a plurality of data fields appended to the MAC subheader and being encoded with a first error detection code, the plurality of data fields comprising a first data field indicating a length of a pay load of the MAC SDU and a second data field indicating a length of at least the MAC subheader and a header stack of the MAC SDU, wherein the MAC subheader and the header stack are encoded with a second error detection code. Fig. 2 shows a flow chart of a corresponding method 200 which may be executed in a first communication device 100, such as the one shown in Fig. 1. The method 200 comprises: transmitting 202 a MAC PDU to a second communication device 300, the MAC PDU comprising at least one MAC subheader and MAC service data unit, SDU, pair, wherein the at least one MAC subheader and MAC SDU pair comprises a plurality of data fields appended to the MAC subheader and being encoded with a first error detection code, the plurality of data fields comprising a first data field indicating a length of a pay load of the MAC SDU and a second data field indicating a length of at least the MAC subheader and a header stack of the MAC SDU, wherein the MAC subheader and the header stack are encoded with a second error detection code.

[0101] Fig. 3 shows a second communication device 300 according to an embodiment of the invention. In the embodiment shown in Fig. 3, the second communication device 300 comprises a processor 302, a transceiver 304 and a memory 306. The processor 302 is coupled to the transceiver 304 and the memory 306 by communication means 308 known in the art. The second communication device 300 may be configured for wireless and / or wired communications in a communication system. The wireless communication capability may be provided with an antenna or antenna array 310 coupled to the transceiver 304, while the wired communication capability may be provided with a wired communication interface 312 e.g., coupled to the transceiver 304.

[0102] The processor 302 may be referred to as one or more general-purpose CPUs, one or more DSPs, one or more ASICs, one or more FPGAs, one or more programmable logic devices, one or more discrete gates, one or more transistor logic devices, one or more discrete hardware components, one or more chipsets. The memory 306 may be a read-only memory, a RAM, or a NVRAM. The transceiver 304 may be a transceiver circuit, a power controller, or an interface providing capability to communicate with other communication modules or communication devices. The transceiver 304, the memory 306 and / or the processor 302 may be implemented in separate chipsets or may be implemented in a common chipset.

[0103] That the second communication device 300 is configured to perform certain actions can in this disclosure be understood to mean that the second communication device 300 comprises suitable means and devices, such as e.g., the processor 302 and the transceiver 304, configured to perform the actions.

[0104] According to embodiments of the invention the second communication device 300 is configured to: receive a MAC PDU from a first communication device 100, the MAC PDU comprising at least one MAC subheader and MAC SDU pair, wherein the at least one MAC subheader and MAC SDU pair comprises a plurality of data fields appended to the MAC subheader and being encoded with a first error detection code, the plurality of data fields comprising a first data field indicating a length of a payload of the MAC SDU and a second data field indicating a length of at least the MAC subheader and a header stack of the MAC SDU, wherein the MAC subheader and the header stack are encoded with a second error detection code; check the first error detection code over the plurality of data fields to produce a first error detection outcome; check the second error detection code over the MAC subheader and the header stack based on the second data field when the first error detection outcome is valid to produce a second error detection outcome; and demultiplex the MAC subheader and MAC SDU pair according to a MAC protocol when the second error detection outcome is valid.

[0105] Furthermore, in an embodiment of the invention, the second communication device 300 comprises a transceiver configured to: receive a MAC PDU from a first communication device 100, the MAC PDU comprising at least one MAC subheader and MAC SDU pair, wherein the at least one MAC subheader and MAC SDU pair comprises a plurality of data fields appended to the MAC subheader and being encoded with a first error detection code, the plurality of data fields comprising a first data field indicating a length of a pay load of the MAC SDU and a second data field indicating a length of at least the MAC subheader and a header stack of the MAC SDU, wherein the MAC subheader and the header stack are encoded with a second error detection code. The second communication device 300 comprises a processor configured to: check the first error detection code over the plurality of data fields to produce a first error detection outcome; check the second error detection code over the MAC subheader and the header stack based on the second data field when the first error detection outcome is valid to produce a second error detection outcome; and demultiplex the MAC subheader and MAC SDU pair according to a MAC protocol when the second error detection outcome is valid.

[0106] Moreover, in yet another embodiment of the invention, the second communication device 300 for a communication system 500 comprises a processor and a memory having computer readable instructions stored thereon which, when executed by the processor, cause the processor to: receive a MAC PDU from a first communication device 100, the MAC PDU comprising at least one MAC subheader and MAC SDU pair, wherein the at least one MAC subheader and MAC SDU pair comprises a plurality of data fields appended to the MAC subheader and being encoded with a first error detection code, the plurality of data fields comprising a first data field indicating a length of a pay load of the MAC SDU and a second data field indicating a length of at least the MAC subheader and a header stack of the MAC SDU, wherein the MAC subheader and the header stack are encoded with a second error detection code; check the first error detection code over the plurality of data fields to produce a first error detection outcome; check the second error detection code over the MAC subheader and the header stack based on the second data field when the first error detection outcome is valid to produce a second error detection outcome; and demultiplex the MAC subheader and MAC SDU pair according to a MAC protocol when the second error detection outcome is valid.

[0107] Fig. 4 shows a flow chart of a corresponding method 400 which may be executed in a second communication device 300, such as the one shown in Fig. 3. The method 400 comprises: receiving 402 a MAC PDU from a first communication device 100, the MAC PDU comprising at least one MAC subheader and MAC SDU pair, wherein the at least one MAC subheader and MAC SDU pair comprises a plurality of data fields appended to the MAC subheader and being encoded with a first error detection code, the plurality of data fields comprising a first data field indicating a length of a pay load of the MAC SDU and a second data field indicating a length of at least the MAC subheader and a header stack of the MAC SDU, wherein the MAC subheader and the header stack are encoded with a second error detection code; checking 404 the first error detection code over the plurality of data fields to produce a first error detection outcome; checking 406 the second error detection code over the MAC subheader and the header stack based on the second data field when the first error detection outcome is valid to produce a second error detection outcome; and demultiplexing 408 the MAC subheader and MAC SDU pair according to a MAC protocol when the second error detection outcome is valid.

[0108] Fig. 5 shows a communication system 500 according to an embodiment of the invention. The communication system 500 in the disclosed embodiment comprises a first communication device 100 and a second communication device 300 configured to communicate and operate in the communication system 500. For simplicity, the shown communication system 500 only comprises one first communication device 100 and one second communication device 300. However, the communication system 500 may comprise any number of first communication devices 100 and any number of second communication devices 300 without deviating from the scope of the invention.

[0109] In this particular example, the first communication device 100 is configured as a client device, such as a user equipment (UE), while the second communication device 300 is configured as a network access node, such as a base station (BS). The network access node may be part of a radio access network (RAN) and can include a communication interface for communication with a network (NW) such as a core network (CN). The communication between the first communication device 100 and the second communication device 300 may be performed using channels in the DL and UL. However, in other examples, the first communication device 100 may be configured as a network access node while the second communication device 300 is configured as a client device. In Fig. 5, the first communication device 100 performs an DL transmission to the second communication device 300. The transmission comprises at least one MAC PDU according to embodiments of the invention. For the receiver of the second communication device 300 to know the format of the MAC PDU according to embodiments of the invention, control signaling may be involved between the first communication device 100 and the second communication device 300. Thus, in embodiments of the invention, the first communication device 100 is also configured to transmit a control message 510 to the second communication device 300. The control message 510 indicates the transmission of the MAC PDU comprising the at least one MAC subheader and MAC SDU pair. This means that the receiver of the second communication device 300 is informed about the format of the MAC PDU so that the MAC PDU can be processed properly by the second communication device 300.

[0110] The control message 510 may be a radio network temporary identifier (RNTI) value which is detected in a control channel such as physical downlink control channel (PDCCH) where it is used to scramble the PDCCH CRC value. Also, other suitable channels may be used.

[0111] Thus, in embodiments of the invention, the indication of the transmission of the MAC PDU format may be given by a RNTI value. This means that receiver of the second communication device 300 may detect the TB comprising the MAC PDU by successfully detecting the RNTI value in the PDCCH.

[0112] Embodiments of the invention provide, among other things, a solution on how to let the application or the application level having the capability to correct bit level errors in exchange for lower transmission latency over a 3GPP NR or beyond radio bearer. In principle this may be achieved by correcting bit errors at application level instead of e.g., correcting the bit errors at the HARQ-level. For some cases the application layer can have a better capability of handling transmission errors. In the current 3GPP NR standard the HARQ process will practically hide all transmission errors from higher layers. Thus, it is also herein considered the case when HARQ process delivers data when the received TB do not pass a CRC check. Embodiments of the invention thus provide a solution for how to receive TB with bit errors over the 3GPP NR and beyond L2 protocols, among other things.

[0113] In short, embodiments of the invention provide protection for all header information in the MAC PDU. The term “header stack” herein used relates to all protocol layers in the MAC PDU, which also includes protocols in the Service Data Adaption Protocol (SDAP) SDU (i.e. IP header and beyond). Embodiments of the invention adds functionality to allow extraction of parts of the MAC PDU in case some header data has unrecoverable errors.

[0114] The proposed solution disclosed herein is e.g., applicable for transmission of MAC PDUs over the wireless- interface between the base station and UE where the interface is called NR-Uu. The solution is applicable for both directions, i.e., UL and DL. The proposed solution may be used in links with good quality but is not limited thereto and can be used for Non-Terrestrial Networks (NTN) and V2X / sidelink applications in 3GPP 5G and beyond.

[0115] On the transmitting side, the novel protection of the MAC PDU according to embodiments of the invention may be applied after multiplexing, and before initiating transmission of the MAC PDU / TB. There may be exactly one MAC PDU in each TB in embodiments of the invention. On the receiving side, the error detection and correction may be applied after receiving the TB / MAC PDU from the HARQ and before demultiplexing. The solution is at least applicable for 3GPP NR (5G) and beyond Layer 2 protocols. Figs. 6-8 illustrate a MAC PDU format according to embodiments of the invention. With reference to Fig. 6, the MAC PDU comprises one or more MAC subheader and MAC SDU pairs. The MAC subheader is pre-appended to the MAC SDU which in turn comprises a header stack and a SDU pay load. The header stack is arranged between the MAC subheader and the payload.

[0116] In embodiments of the invention, the herein mentioned header stack comprises one or more headers in a group comprising: a Radio Link Control (RLC) header, a Packet Data Convergence Protocol (PDCP) header, a Service Data Adaption Protocol (SDAP) header, an Internet Protocol (IP) header, a User Data Protocol (UDP) Lite header, and a Real-time Transport Protocol (RTP) header.

[0117] Fig. 7 shows a MAC subheader and MAC SDU pair comprising a plurality of data fields (DFs). According to embodiments of the invention the plurality of data fields comprises at least a first data field (DF1) and a second field (DF2) as shown in Fig. 8. The plurality of data fields may be pre-appended to the MAC subheader as also shown in Fig. 7 and 8.

[0118] Figs. 9 and 10 shows a MAC PDU format encoded with a first error detection code (EDC1). As previously mentioned, the present MAC PDU comprises at least one MAC subheader and MAC SDU pair. A plurality of data fields is appended to the MAC subheader and are encoded with a first CRC.

[0119] Moreover, the location of the first error detection code may vary such that the first error detection code is arranged: between the plurality of data fields and the MAC subheader; or before the plurality of data fields; or between two data fields of the plurality of data fields.

[0120] One example is given in Fig. 9 and 10 in which the first error detection code is arranged between the plurality of data fields and the MAC subheader. It is also shown in Fig. 10 when the header stack is arranged between the MAC subheader and the pay load of the MAC SDU.

[0121] Fig. 11 shows a MAC PDU format encoded with a first detection code and second error detection code according to embodiments of the invention. The first error detection code may be a first cyclical redundancy check (CRC1) code, and the second error detection code may be a second CRC code (CRC2) in embodiments of the invention. Thus, in the following disclosure the terminology first CRC and second CRC will be used instead of first and second error detection codes, but it is to be noted that any suitable error detection codes may be applied such as parity codes or Hamming codes.

[0122] Furthermore, the location of the second CRC may also vary such that the second CRC is arranged: between the header stack and the pay load of the MAC SDU; or between the header stack and the MAC subheader; or before the MAC subheader. In such cases, the second data field indicates a length of the MAC subheader, the header stack and the second CRC.

[0123] The second CRC may be computed over the MAC subheader and the header stack which means that contents of the MAC subheader and the contents of the header stack are passed through a CRC generation function that outputs a CRC value.

[0124] In embodiments of the invention, error correction encoding of the MAC subheader and MAC SDU pair is also employed. By encoding with an error correction code, the transmitter adds redundancy to the transmitted data and this means that the receiving side can be able to correct bit errors introduced during the transmission of the MAC PDU. The error correction code may be any suitable error correction code known in the art. For example, a forward error correction (FEC) code such as low-density parity-check (LDPC) codes, Hamming codes or any other codes used in current and future communication standards. Fig. 12 shows a MAC PDU format encoded with a first error correction code (ECC1) according to embodiments of the invention. In this case the plurality of data fields and the first CRC are encoded with the first error correction code.

[0125] Fig. 13 shows a MAC PDU format encoded with both the first error correction code and a second error correction code (ECC2) according to embodiments of the invention. As noted from Fig. 13, the MAC subheader, the header stack and the second CRC are encoded with the second error correction code. Hence, in such cases the second data field indicates a length of the MAC subheader, the header stack and the second CRC encoded with the second error correction code. This means that second data field indicates the size of the encoded data fields and this size is used by the decoder to know how many bytes to decode to produce the original MAC subheader, the header stack and the second CRC. This also means that it is possible to find the location of the next MAC subheader and MAC SDU pair prior to decoding the encoded data fields of the current MAC subheader and MAC SDU pair and, thus, it enables decoding of multiple encoded data fields in parallel.

[0126] The plurality of data fields may also comprise a third data field (DF3) indicating the error correction encoding of the MAC subheader, the header stack and the second CRC2. This is shown in Fig. 14. The third data field may indicate the error correction encoding by using a bit flag where a “1” indicates error correction encoding while a “0” indicates no error correction encoding, or vice versa. Thus, the receiver of the second communication device 300 knows when error correct encoding has been applied by checking the third data field so that the receiver will know how to process the received MAC PDU.

[0127] Furthermore, in embodiments of the invention, the MAC PDU may comprise a plurality of MAC subheader and MAC SDU pairs appended to each other in the same MAC PDU as shown in Fig. 15. Thus, by using the information of the first data field and the second data field in a first MAC subheader and MAC SDU pair a second MAC subheader and MAC SDU pair appended after the first MAC subheader and MAC SDU pair can be found. The second MAC subheader and MAC SDU pair may also be referred to as the next or subsequent MAC subheader and MAC SDU pair in the MAC PDU.

[0128] Fig. 16 shows a flow diagram for processing a MAC PDU format encoded with a first and second error detection code at the receiver of the second communication device 300. In this example, MAC PDU comprises multiple MAC subheader and MAC SDU pairs appended to each other.

[0129] Hence, for each MAC subheader and MAC SDU pair, and by using the notation {MAC subheader, MAC SDU} -pair, the following may be performed by the receiver of the second communication device 300. The HARQ block 340 forwards a MAC PDU comprising multiple {MAC subheader, MAC SDU} -pairs to an error detection and correction module (EDCM) 340 of the receiver. The EDCM 340 comprises:

[0130] 1 ) Check a first CRC over the plurality of data fields to produce a first error detection outcome being VALID or INVALID by feeding the plurality of data fields through a generator function of the first CRC to produce a first CRC value.

[0131] 2) IF the first error detection outcome is VALID, which indicates that the plurality of data fields is free of bit errors: a. Check a second CRC over the MAC subheader and the header stack in the MAC SDU to produce a second error detection outcome being VALID or INVALID by feeding MAC subheader and the header stack through a generator function of the second CRC to produce a second CRC value. The size of the MAC subheader and the header stack is given by the value of the second data field. b. IF the second error detection outcome is VALID, which indicates that the MAC subheader and the header stack are free of bit errors, then continue processing of the {MAC subheader, MAC SDU} -pair as normal in MAC demultiplexing block 350. That is, as if the {MAC subheader, MAC SDU} -pair was received in a transport block (TB) without CRC error and not using the error detection mechanism described herein.

[0132] 3) ELSE IF the first error detection outcome is INVALID, then the plurality of data fields cannot be trusted and the processing of the {MAC subheader, MAC SDU}-pair ends here. An option in such cases is to discard the remaining {MAC subheader, MAC SDU} -pairs of the MAC PDU when the first error detection outcome is INVALID in step 3).

[0133] 4) Locate the next {MAC subheader, MAC SDU}-pair to come in the MAC PDU after the current {MAC subheader, MAC SDU} -pair when the first error detection outcome is VALID and continue the processing from step 1) for the next {MAC subheader, MAC SDU} -pair in the MAC PDU. The size of the {MAC subheader, MAC SDU} -pair is given by the first and second data fields. The next {MAC subheader, MAC SDU} -pair follows after the current {MAC subheader, MAC SDU} -pair in the MAC PDU since the plurality of {MAC subheader, MAC SDU} -pairs are appended after each other in the MAC PDU. By using the location of the current {MAC subheader, MAC SDU} -pair and the size of the current MAC subheader and MAC SDU the next {MAC subheader, MAC SDU} -pair can be located.

[0134] Fig. 17 shows a flow diagram for processing a MAC PDU format encoded with an error correction code at the receiver of the second communication device 300. In these cases, the second communication device 300 is configured to decode the plurality of data fields and the first error detection code based on the first error correction code. With reference to Fig. 17:

[0135] 1 ) Decode the plurality of data fields and the first CRC using the first error correcting code. Check a first CRC over the decoded plurality of data fields to produce a first error detection outcome being VALID or INVALID.

[0136] 2) IF the first error detection outcome is VALID, which indicates that the plurality of data fields is free of bit errors: a. IF the third data field indicates that the MAC subheader and headers stack are coded with a second error correction code: i. Obtain a MAC subheader, header stack and second CRC by decoding the encoded MAC subheader, header stack and the second CRC using the second error correcting code. b. Check a second CRC over the MAC subheader and the header stack in the MAC SDU to obtain a second error detection outcome. The size of the information constituted of the MAC subheader and the header stack is given by the value in the second data field or known from the error correction in step 2.a.i. c. IF the second error detection outcome is VALID, which indicates that the MAC subheader and the header stack are free of bit errors, then continue processing of the current {MAC subheader, MAC SDU} -pair as normal. That is, as if the {MAC subheader, MAC SDU} -pair was received in a transport block (TB) without CRC error and not using the error detection and correction mechanism described herein.

[0137] 3) ELSE IF the first error detection outcome is INVALID, the plurality of data fields cannot be trusted and the processing of the {MAC subheader, MAC SDU} -pair ends here. An option in these cases is to discard the remaining {MAC subheader, MAC SDU} -pairs of the MAC PDU when the first error detection outcome is INVALID in step 3).

[0138] 4) Locate the next {MAC subheader, MAC SDU}-pairto come in the MAC PDU when the first error detection outcome is VALID and continue the processing from step 1) for the next {MAC subheader, MAC SDU}- pair in the MAC PDU. The size of the {MAC subheader, MAC SDU} -pair is described by the first and second data fields or by the first data field and the output from error correction in step 2.a.i. The next {MAC subheader, MAC SDU} -pair follows after the current {MAC subheader, MAC SDU} -pair in the MAC PDU. By using the location of the current {MAC subheader, MAC SDU}-pair and the size of the current MAC subheader and MAC SDU the next {MAC subheader, MAC SDU}-pair can be located.

[0139] A network access node herein may also be denoted as a radio network access node, an access network access node, an access point (AP), or a base station (BS), e.g., a radio base station (RBS), which in some networks may be referred to as transmitter, “gNB”, “gNodeB”, “eNB”, “eNodeB”, “NodeB” or “B node”, depending on the standard, technology and terminology used. The radio network access node may be of different classes or types such as e.g., macro eNodeB, home eNodeB or pico base station, based on transmission power and thereby the cell size. The radio network access node may further be a station, which is any device that contains an IEEE 802.11-conformant media access control (MAC) and physical layer (PHY) interface to the wireless medium (WM). The radio network access node may be configured for communication in 3GPP related long term evolution (LTE), LTE-advanced, fifth generation (5G) wireless systems, such as new radio (NR) and their evolutions, as well as in IEEE related Wi-Fi, worldwide interoperability for microwave access (WiMAX) and their evolutions.

[0140] A client device herein may be denoted as a user device, a user equipment (UE), a mobile station, an internet of things (loT) device, a sensor device, a wireless terminal and / or a mobile terminal, or any communication apparatus (e.g. chip or chipset) that is configured to and / or is enabled to communicate wirelessly in a wireless communication system, sometimes also referred to as a cellular radio system. The UEs may further be referred to as mobile telephones, cellular telephones, computer tablets or laptops with wireless capability. The UEs in this context may be, for example, portable, pocket-storable, hand-held, computer- comprised, or vehicle-mounted mobile devices, enabled to communicate voice and / or data, via a RAN, with another communication entity, such as another receiver or a server. The UE may further be a station, which is any device that contains an IEEE 802.11 -conformant MAC and PHY interface to the WM. The UE may be configured for communication in 3GPP related LTE, LTE-advanced, 5G wireless systems, such as NR, and their evolutions, as well as in IEEE related Wi-Fi, WiMAX and their evolutions.

[0141] Furthermore, any method according to embodiments of the invention may be implemented in a computer program, having code means, which when run by processing means causes the processing means to execute the steps of the method. The computer program is included in a computer readable medium of a computer program product. The computer readable medium may comprise essentially any memory, such as previously mentioned a ROM, a PROM, an EPROM, a flash memory, an EEPROM, or a hard disk drive.

[0142] Moreover, it should be realized that the first communication device 100 and the second communication device 300 comprise the necessary communication capabilities in the form of e.g., functions, means, units, elements, etc., for performing or implementing embodiments of the invention. Examples of other such means, units, elements and functions are: processors, memory, buffers, control logic, encoders, decoders, rate matchers, de-rate matchers, mapping units, multipliers, decision units, selecting units, switches, interleavers, de-interleavers, modulators, demodulators, inputs, outputs, antennas, amplifiers, receiver units, transmitter units, DSPs, TCM encoder, TCM decoder, power supply units, power feeders, communication interfaces, communication protocols, etc. which are suitably arranged together for performing the solution.

[0143] Therefore, the processors) of the first communication device 100 and the second communication device 300 may comprise, e.g., one or more instances of a CPU, a processing unit, a processing circuit, a processor, an ASIC, a microprocessor, or other processing logic that may interpret and execute instructions. The expression “processor” may thus represent a processing circuitry comprising aplurality of processing circuits, such as e.g., any, some or all ofthe ones mentioned above. The processing circuitry may further perform data processing functions for inputting, outputting, and processing of data comprising data buffering and device control functions, such as call processing control, user interface control, or the like. Finally, it should be understood that the invention is not limited to the embodiments described above, but also relates to and incorporates all embodiments within the scope of the appended independent claims.

Claims

CLAIMS1. A first communication device (100) configured to: transmit a medium access control, MAC, packet data unit, PDU, to a second communication device (300), the MAC PDU comprising at least one MAC subheader and MAC service data unit, SDU, pair, wherein the at least one MAC subheader and MAC SDU pair comprises a plurality of data fields appended to the MAC subheader and being encoded with a first error detection code, the plurality of data fields comprising a first data field indicating a length of a payload of the MAC SDU and a second data field indicating a length of at least the MAC subheader and a header stack of the MAC SDU, wherein the MAC subheader and the header stack are encoded with a second error detection code.

2. The first communication device (100) according to claim 1, wherein the plurality of data fields is pre-appended to the MAC subheader.

3. The first communication device (100) according to claim 1 or 2, wherein the first error detection code is arranged: between the plurality of data fields and the MAC subheader; or before the plurality of data fields; or between two data fields of the plurality of data fields.

4. The first communication device (100) according to any one of the preceding claims, wherein the plurality of data fields and the first error detection code are encoded with a first error correction code.

5. The first communication device (100) according to any one of the preceding claims, wherein the header stack is arranged between the MAC subheader and the payload of the MAC SDU.

6. The first communication device (100) according to any one of the preceding claims, wherein the second error detection code is arranged: between the header stack and the pay load of the MAC SDU; or between the header stack and the MAC subheader; or before the MAC subheader.

7. The first communication device (100) according to claim 6, wherein the second data field indicates a length of the MAC subheader, the header stack and the second error detection code.

8. The first communication device (100) according to claim 7, wherein the second error detection code is computed over the MAC subheader and the header stack.

9. The first communication device (100) according to claim 7 or 8, wherein the MAC subheader, the header stack and the second error detection code are encoded with a second error correction code.

10. The first communication device (100) according to claim 9, wherein the second data field indicates a length of the MAC subheader, the header stack and the second error detection code encoded with the second error correction code.

11. The first communication device (100) according to claim 9 or 10, wherein the plurality of data fields comprises a third data field indicating the error correction encoding of the MAC subheader, the header stack and the second error detection code.

12. The first communication device (100) according to claim 10, wherein the third data field comprises a bit flag.

13. The first communication device (100) according to any one of the preceding claims, wherein the header stack comprises one or more headers in a group comprising: a RLC header, a PDCP header, a SDAP header, an IP header, a UDP Lite header, and an RTP header.

14. The first communication device (100) according to any one of the preceding claims, wherein the first error detection code is a first cyclical redundancy check, CRC, code and the second error detection code is a second CRC code.

15. The first communication device (100) according to any one of the preceding claims, configured to: transmit a control message (510) to the second communication device (300), the control message (510) indicating the transmission of the MAC PDU comprising the at least one MAC subheader and MAC SDU pair.

16. The first communication device (100) according to claim 15, wherein the indication of the transmission of the MAC PDU is given by a RNTI value.

17. The first communication device (100) according to any one of the preceding claims, wherein the MAC PDU comprises a plurality of MAC subheader and MAC SDU pairs appended to each other in the MAC PDU.

18. A second communication device (300) configured to: receive a MAC PDU from a first communication device (100), the MAC PDU comprising at least one MAC subheader and MAC SDU pair, wherein the at least one MAC subheader and MAC SDU pair comprises a plurality of data fields appended to the MAC subheader and being encoded with a first error detection code, the plurality of data fields comprising a first data field indicating a length of a pay load of the MAC SDU and a second data field indicating a length of at least the MAC subheader and a header stack of the MAC SDU, wherein the MAC subheader and the header stack are encoded with a second error detection code; check the first error detection code over the plurality of data fields to produce a first error detection outcome; check the second error detection code over the MAC subheader and the header stack based on the second data field when the first error detection outcome is valid to produce a second error detection outcome; and demultiplex the MAC subheader and MAC SDU pair according to a MAC protocol when the second error detection outcome is valid.

19. The second communication device (300) according to claim 18, configured to: discard the remaining MAC subheader and MAC SDU pairs of the MAC PDU when the first error detection outcome is invalid.

20. The second communication device (300) according to claim 18 or 19, configured to: compute a position of a next MAC subheader and MAC SDU pair based on the first data field when the first error detection outcome is valid.

21. The second communication device (300) according to any one of claims 18 to 20, wherein the plurality of data fields is preappended to the MAC subheader.

22. The second communication device (300) according to any one of claims 18 to 21, wherein the first error detection code is arranged: between the plurality of data fields and the MAC subheader; orbefore the plurality of data fields; or between two data fields of the plurality of data fields.

23. The second communication device (300) according to any one of claims 18 to 22, wherein the plurality of data fields and the first error detection code are encoded with a first error correction code, and wherein the second communication device (300) is configured to: decode the plurality of data fields and the first error detection code based on the first error correction code.

24. The second communication device (300) according to any one of claims 18 to 23, wherein the header stack is arranged between the MAC subheader and the payload of the MAC SDU.

25. The second communication device (300) according to any one of claims 18 to 24, wherein the second error detection code is arranged: between the header stack and the pay load of the MAC SDU; or between the header stack and the MAC subheader; or before the MAC subheader.

26. The second communication device (300) according to claim 25, wherein the second data field indicates a length of the MAC subheader, the header stack and the second error detection code.

27. The second communication device (300) according to claim 26, wherein the second error detection code is computed over the MAC subheader and the header stack.

28. The second communication device (300) according to claim 26 or 27, wherein the MAC subheader, the header stack and the second error detection code are encoded with a second error correction code, and wherein the second communication device (300) is configured to: decode the MAC subheader, the header stack and the second error detection code based on the second error correction code.

29. The second communication device (300) according to claim 28, wherein the second data field indicates a length of the MAC subheader, the header stack and the second error detection code encoded with the second error correction code.

30. The second communication device (300) according to claim 28 or 29, wherein the plurality of data fields comprises a third data field indicating the error correction encoding of the MAC subheader, the header stack and the second error detection code.

31. The second communication device (300) according to claim 30, wherein the third data field comprises a bit flag.

32. The second communication device (300) according to any one of claims 18 to 31, wherein the header stack comprises one or more headers in a group comprising: a RLC header, a PDCP header, a SDAP header, an IP header, a UDP Lite header, and an RTP header.

33. The second communication device (300) according to any one of claims 18 to 32, wherein the first error detection code is a first cyclical redundancy check, CRC, code and the second error detection code is a second CRC code.

34. The second communication device (300) according to any one of claims 18 to 33, configured to: receive a control message (510) from the first communication device (100), the control message (510) indicating the transmission of the MAC PDU comprising the at least one MAC subheader and MAC SDU pair.

35. The second communication device (300) according to claim 34, wherein the indication of the transmission of the MAC PDU is given by a RNTI value.

36. The second communication device (300) according to any one of claims 18 to 35, wherein the MAC PDU comprises a plurality of MAC subheader and MAC SDU pairs appended to each other in the MAC PDU.

37. A method (200) for a first communication device (100), the method (200) comprising: transmitting (202) a MAC PDU to a second communication device (300), the MAC PDU comprising at least one MAC subheader and MAC SDU pair, wherein the at least one MAC subheader and MAC SDU pair comprises a plurality of data fields appended to the MAC subheader and being encoded with a first error detection code, the plurality of data fields comprising a first data field indicating a length of a pay load of the MAC SDU and a second data field indicating a length of at least the MAC subheader and a header stack of the MAC SDU, wherein the MAC subheader and the header stack are encoded with a second error detection code.

38. A method (400) for a second communication device (300), the method (400) comprising: receiving (402) a MAC PDU from a first communication device (100), the MAC PDU comprising at least one MAC subheader and MAC SDU pair, wherein the at least one MAC subheader and MAC SDU pair comprises a plurality of data fields appended to the MAC subheader and being encoded with a first error detection code, the plurality of data fields comprising a first data field indicating a length of a pay load of the MAC SDU and a second data field indicating a length of at least the MAC subheader and a header stack of the MAC SDU, wherein the MAC subheader and the header stack are encoded with a second error detection code; checking (404) the first error detection code over the plurality of data fields to produce a first error detection outcome; checking (406) the second error detection code over the MAC subheader and the header stack based on the second data field when the first error detection outcome is valid to produce a second error detection outcome; and demultiplexing (408) the MAC subheader and MAC SDU pair according to a MAC protocol when the second error detection outcome is valid.

39. A computer program with a program code for performing amethod according to claim 37 or 38 when the computer program runs on a computer.21

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