EP4662812A1

EP4662812A1 - Hybrid automatic repeat request with pre-configured redundancy versions

Info

Publication number: EP4662812A1
Application number: EP23704109.0A
Authority: EP
Inventors: Shaima ABIDRABBU; Hüseyin ARSLAN
Original assignee: Vestel Elektronik Sanayi ve Ticaret AS
Current assignee: Vestel Elektronik Sanayi ve Ticaret AS
Priority date: 2023-02-07
Filing date: 2023-02-07
Publication date: 2025-12-17
Also published as: WO2024165143A1

Abstract

The present disclosure relates to a transmitting method, a receiving method, a transmitting device and a receiving device that apply a hybrid automatic repeat request protocol, HARQ. A first transmission of a data block is generated, including a plurality of FEC code portions. The generating includes coding the data block with a forward error correcting, FEC, code and the generated first transmission is transmitted. Redundancy versions of the data block are then generated. Each redundancy version corresponds to a respective FEC code portion out of said plurality of FEC code portions. The redundancy versions differ from each other and are transmitted as retransmissions of the data block in accordance with the HARQ. Correspondingly, the receiver receives the first transmission and the retransmissions and combines them before FEC decoding to obtain the decoded data block.

Description

Hybrid automatic repeat request with pre-configured redundancy versions

The present disclosure relates generally to wireless communication, and in particular to a hybrid automatic repeat request (HARQ) protocol. The present disclosure relates to HARQ transmitter and receiver, as well as HARQ transmitting and receiving methods.

BACKGROUND

Automatic repeat request (ARQ) schemes, and in particular hybrid-ARQ (HARQ) schemes, which jointly adopt forward error correction (FEC) and ARQ, have been used to provide reliable data transmission in wireless communications systems. On the other hand, the feedback from the receiver to the transmitter and the retransmission process used in ARQ may incur some costs in terms of power efficiency, throughput, computational power (complexity), and end-to-end delay. Due to noise, interference, channel fading, and other impairments, data transferred between two communicating entities are prone to errors. Therefore, the underlying communications protocols should be designed to correct data errors to support a particular Quality of Service (QoS) class Packet Error Rate (PER). In general, wireless communications systems may utilize various protocols at different layers to correct data errors at the receiver. At the physical layer, error detection and/or correction are usually performed using FEC coding. At the radio link and the transport layers, error correction usually relies on retransmission-based methods such as ARQ. Also, at the application layer, retransmission methods can be applied to recover some lost or corrupted packets. Adopting one or more of the aforementioned methods depends on the system resources and the QoS requirements. Nevertheless, FEC and ARQ are essential building blocks for most popular standards including the fourth generation (4G) wireless standards, 5G, wireless fidelity (Wi-Fi, e.g. IEEE 802.11 based systems), and narrowband (NB)-loT.

There have been attempts to alleviate or reduce some of the above-mentioned costs of FEC and ARQ and to integrate the FEC and the ARQ efficiently into the layer processing structure including further functions. Such integration may be a challenging task. SUMMARY

Methods and techniques are described herein for facilitating transmission and reception of wireless signals using a HARQ which may lead to a more efficient processing at the transmitter and/or at the receiver side.

The invention is defined by the independent claims. Some exemplary implementations are provided by the dependent claims.

For example, a transmitting method is provided, comprising generating a first transmission of a data block including a plurality of FEC code portions, the generating including coding the data block with a forward error correcting, FEC, code; transmitting the first transmission; generating redundancy versions of the data block, wherein (i) each redundancy version corresponds to a respective FEC code portion out of said plurality of FEC code portions, and (ii) the redundancy versions differ from each other; and transmitting the redundancy versions as retransmissions of the data block in accordance with a hybrid automatic repeat request protocol, HARQ.

For example, a receiving method is provided, comprising receiving a first transmission of a data block including a plurality of FEC code portions; decoding said first transmission with a forward error correcting, FEC, code; in case the decoding of the first transmission is not successful: (i) receiving one or more redundancy versions as retransmissions of the data block in accordance with a hybrid automatic repeat request protocol, HARQ, wherein each redundancy version includes a respective FEC code portion out of said plurality of FEC code portions, (ii) combining corresponding FEC code portions of said received one or more redundancy versions and/or the first transmission, (iii) decoding the combined FEC codewords.

These and other features and characteristics of the presently disclosed subject matter, as well as the methods of operation and functions of the related elements of structures and the combination of parts and economies of manufacture, will become more apparent upon consideration of the following description and the appended claims with reference to the accompanying drawings, all of which form a part of this specification. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the disclosed subject matter. As used in the specification and the claims, the singular form of “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. BRIEF DESCRIPTION OF DRAWINGS

An understanding of the nature and advantages of various embodiments may be realized by reference to the following figures.

FIG. 1 is a block diagram illustrating a communication system with a transmitter and a receiver.

FIG. 2 is a block diagram illustrating a communication system architecture using infrastructure and involving communication between a base station and a user equipment.

FIG. 3 is a block diagram illustrating exemplary parts of a communication system processing chain at a data source and at a data destination.

FIG. 4 is a schematic drawing illustrating chase combining.

FIG. 5 is a schematic drawing illustrating a general incremental redundancy combining.

FIG. 6 is a schematic drawing illustrating processing of an (A)-MSDU by MAC layer and the physical layer.

FIG. 7 is a schematic drawing illustrating an incremental redundancy combining with a preplanned (pre-configured) redundancy version format.

FIG. 8 is a schematic drawing illustrating a HARQ protocol with first full-rate transmission and retransmissions including predefined parts of the first transmission.

FIG. 9 is a block diagram of a transmitting device suitable for implementing embodiments of the present disclosure.

FIG. 10 is a block diagram illustrating an exemplary implementation of memory 310 of the receiver of Fig. 9.

FIG. 11 is a schematic drawing illustrating a coded data block separated into four parts.

FIG. 12 is a schematic drawing illustrating an exemplary recursive concatenation of the transmitted data using polar code. FIG. 13 is a schematic drawing illustrating generating of redundancy versions out of the polar encoded data block.

FIG. 14 is a schematic drawing illustrating layer processing of a first transmission.

FIG. 15 is a schematic drawing illustrating layer processing of a first retransmission.

FIG. 16 is a schematic drawing illustrating layer processing of a second retransmission.

FIG. 17 is a schematic drawing illustrating layer processing of a third retransmission.

FIG. 18 is a schematic drawing illustrating layer processing of a fourth retransmission.

FIG. 19 is a block diagram of a receiving device suitable for implementing embodiments of the present disclosure.

FIG. 20 is a block diagram illustrating an exemplary implementation of memory 310 of the receiver of Fig. 19.

FIG. 21 is a flow diagram illustrating an exemplary transmission method;

FIG. 22 is a flow diagram illustrating an exemplary reception method.

Like reference numbers and symbols in the various figures indicate like elements, in accordance with certain example implementations.

DETAILED DESCRIPTION

For purposes of the description hereinafter, the terms “end,” “upper,” “lower,” “right,” “left,” “vertical,” “horizontal,” “top,” “bottom,” “lateral,” “longitudinal,” and derivatives thereof shall relate to the disclosed subject matter as it is oriented in the drawing figures. However, it is to be understood that the disclosed subject matter may assume various alternative variations and step sequences, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification, are simply exemplary embodiments or aspects of the disclosed subject matter. Hence, specific dimensions and other physical characteristics related to the embodiments or aspects disclosed herein are not to be considered as limiting unless otherwise indicated. No aspect, component, element, structure, act, step, function, instruction, and/or the like used herein should be construed as critical or essential unless explicitly described as such. Also, as used herein, the articles “a” and “an” are intended to include one or more items and may be used interchangeably with “one or more” and “at least one.” Furthermore, as used herein, the term “set” is intended to include one or more items (e.g., related items, unrelated items, a combination of related and unrelated items, and/or the like) and may be used interchangeably with “one or more” or “at least one.” Where only one item is intended, the term “one” or similar language is used. Also, as used herein, the terms “has,” “have,” “having,” or the like are intended to be open-ended terms. Further, the phrase “based on” is intended to mean “based at least partially on” unless explicitly stated otherwise.

Communication system

Fig. 1 illustrates an exemplary communication system CS in which Tx represents a transmitter and Rx represents a receiver. The transmitter Tx is capable of transmitting a signal to the receiver Rx over an interface Intf. The interface Intf may be, for instance, a wireless interface. The interface may be specified by means of resources, which can be used for the transmission and reception by the transmitter Tx and the receiver Rx. Such resources may be defined in one or more (or all) of the time domain, frequency domain, code domain, and space domain. It is noted that in general, the “transmitter” and “receiver” may be also both integrated in the same device. In other words, the devices Tx and Rx in Fig. 1 may respectively also include the functionality of the Rx and Tx.

The present disclosure is not limited to any particular transmitter Tx, receiver Rx and/or interface Intf implementation. However, it may be applied readily to some existing communication systems as well as to the extensions of such systems, or to new communication systems. Exemplary existing communication systems may be, for instance the 5G New Radio (NR) in its current or future releases, and/or the IEEE 802.11 based systems such as the recently studied IEEE 802.11 be or the like.

Fig. 2 shows an exemplary wireless communication system such as an IEEE 802.11 based system or a 3GPP system such as 4G/5G or the like employing infrastructure. Such system includes a base station BS and a user equipment UE. The BS can be an access point (AP) of the IEEE 802.11 based system or a NodeB of the 3GPP system, such as an eNB of the 4G (LTE) or gNB of the 5G (NR). The UE may be any device such as mobile phone, laptop or tablet with the access to the wireless system, or even loT machine-type devices or the like. The term UE is used mainly in the context of the 3GPP standards. However, in this disclosure, this term is also used for general user equipment in any system such as e.g. a STA in the IEEE 802.11 based systems. The present disclosure is not limited to any particular implementation of the BS and the UE.

As illustrated in Fig. 2, the communication between the BS and the UE may include downlink (DL) and uplink (UL). The DL communication is from the BS to the UE. Accordingly, in this case, the BS corresponds to the transmitter Tx of Fig. 1 and the UE corresponds to the receiver Rx of Fig. 1 . The UL communication is from the UE to the BS. Accordingly, in this case, the UE corresponds to the transmitter Tx of Fig. 1 and the BS corresponds to the receiver Rx of Fig. 1. The present disclosure is not limited to the infrastructure based communication and may be employed also in device to device communications (e.g. between two UEs or STAs), at sidelink.

A more detailed, yet still a simplified block diagram of a digital communication system is depicted in Fig. 3. Blocks 110-140 belong to a transmitter side and may be implemented by the transmitter Tx of Fig. 1. Blocks 160-190 belong to a receiver side and may be implemented by the receiver Rx of Fig. 1. The transmitter and the receiver communicate with each other via a channel 150, which may add to the signal transmitted by the transmitter some noise. Information source 110 provides source data to be communicated to the receiving side. This may be raw data such as sensor data that may be e.g. am audio signal, a video signal, image signal, text, measurement value(s) or the like. The source data may be compressed by the source encoder 120. The source encoder 120 may perform compression of the source data, such as lossy or lossless compression. The possibly compressed data are then passed to the channel encoder 130 that may perform various techniques such as FEC and ARQ or the like which facilitate robust transmission over the noisy channel 150. The channel coded data may then be modulated in a modulator 140 and transmitted over the channel 150, e.g. via one or more antennas. It is noted that the information source and the source encoder are typically not part of a communication system such as wireless communication interface. They are usually performed on the application layer and passed to the communication interface for transmission.

Correspondingly, the receiver side includes a demodulator 160 that demodulates the received signal (received e.g. over one or more antennas) and a channel decoder 170 which applies FEC decoding and/or implements receiver-side ARQ protocol and/or possibly other techniques. The source decoder 180 then de-compresses the source data, which are then used at the destination 190, e.g. displayed, used in further processing, played via loudspeaker, or the like.

The present disclosure mainly relates to the channel coder 130 and channel decoder 170. Channel coding 130 is performed on data, that are typically referred to as information data (or information bits if the data is coded in units of bits rather than symbols), in such a way as to mitigate the negative effects of noise and interference incurred in the communications channel 150. This is achieved by FEC by adding redundancy, where some extra bits are included into the data to be transmitted in addition to the information bits for future error correction or error detection 170 at the receiver side. The capability of the demodulator 160 to restore the transmitted signals may be hampered by different channel factors including noise, interference, Doppler shift, multipath fading, etc. These factors result in demodulation errors and may hinder reliable communication. The purpose of a channel encoder 130 is, therefore, to facilitate a way to combat these errors caused by unfavorable channel conditions. Today’s error correction codes can be generally classified into two major categories: (i) block codes and (ii) convolutional codes, where both can be used by HARQ.

Combining

A typical HARQ includes four main operations at the receiver side: (i) FEC decoding, (ii) error detection, (iii) combining, and, if necessary, (iv) retransmission.

FEC decoding uses the redundancy inserted at the FEC encoder and correlated with the information bits to correct some transmission errors. Error detection is typically performed by a cyclic redundancy code (CRC) that may be added to the encoded data before the transmission at the transmitter side and checked at the receiver side. Combining will be discussed in more detail in the following. Retransmissions are triggered in cases where even after the combining, the received data cannot be correctly decoded (still resulting in error detected by the CRC).

HARQ does not have to discard erroneous packets. They may be stored in a buffer and combined with retransmitted packets that may be received later. This is called HARQ with soft combining. Soft combining is an error correction technique in which the erroneous packets are not discarded but stored in a buffer. The basic idea is that two or more packets, received each with insufficient information, can be combined in such a way that the total signal can be decoded after all. In other words combines received data with their retransmission(s) to obtain a single, combined packet that is more reliable than its constituents. Decoding of the error-correction code operates on the combined signal. If the decoding fails (typically a CRC code is used to detect this event), a retransmission is requested. Retransmission in any HARQ scheme must, by definition, represent the same set of information bits as the original transmission. However, the set of coded bits transmitted in each retransmission may be selected differently as long as they represent the same set of information bits. HARQ with soft combining is therefore usually categorized into Chase combining also known as type 1 HARQ, and incremental redundancy (IR) also known as type 2 HARQ., depending on whether the retransmitted bits are required to be identical to the original transmission or not.

Chase combining is illustrated in Fig. 4. In the chase combining, the combining approach uses the data (e.g. information bits), error detection bits (e.g. CRC), and FEC bits (redundancy produced by the FEC) and added to the information bits before transmission. If the channel quality is good, errors are detected and corrected. If the channel quality is bad, not all errors may be corrected, and the receiver asks for re-transmission (within an ARQ protocol) which is basically a repetition of the previously transmitted (encoded) data.

In the chase combining, the retransmissions consist of the same set of coded bits as the original transmission. After each retransmission, the receiver uses e.g. a maximum-ratio combining to combine each received channel bit with any previous transmissions of the same bit, and the combined signal is fed to the decoder. As each retransmission is an identical copy of the original transmission (at least at the transmitter side), retransmissions with Chase combining can be seen as an additional repetition coding. Therefore, as no new redundancy is transmitted, Chase combining does not give any additional coding gain but only increases the accumulated received Eb/NO for each retransmission as illustrated in Fig. 4.

As can be seen in Fig. 4, the coded bits in this example consist of information bits (diagonally meshed) and parity bits (without pattern). In this example, the code rate is 1 , meaning that the parity portion has the same length as the information bit portion. At initial transmission (also sometimes referred to as new data transmission or first transmission), the coded bits are transmitted. At a first retransmission, the same coded bits are retransmitted again, which is illustrated in the figure by two replicas of the received coded bits. At a second retransmission, the same coded bits are retransmitted again, which is illustrated in the figure by now three replicas of the received coded bits, etc. It is noted that chase combining may also combine coded data (coded bits) coded with a non-systematic code.

Several variants of Chase combining exist. For example, only a subset of the bits transmitted in the original transmission might be retransmitted, so-called partial Chase combining. Furthermore, although the combination is often done after demodulation before channel decoding, the combination can also be carried out at the modulation symbol level before demodulation, as long as the modulation scheme is unchanged between transmission and retransmission.

In the case of incremental redundancy, the combining approach also uses data, error detection bits, and FEC bits. But a different subset of data, a different subset of error detection, and a different subset of FEC may be sent on each re-transmission. For example, in the first transmission, a subset of information and the redundancy is sent. Re-transmissions are made with a different set of data, error detection, and/or FEC. It is noted that for non-systematic FEC encoders, the information bits and the redundancy may be indistinguishable from each other. In other words, with incremental redundancy, retransmitted packets are related to the same information bits although each packet carries a different subset of information and parity bits

IR transmits “increments” (different redundancy versions) of information and/or redundant bits after errors are observed at the receiver and a request for retransmission is fed back to the transmitter. In this way, the IR may adaptively change an effective data rate based on the results of actual transmissions. On the other hand, link adaptation (such as changing modulation and coding scheme) relies on channel estimation to determine a suitable rate, which may not be always a suitable choice when transmission occurs because of measurement errors or latency. Therefore, IR may achieve better aggregate throughput, possibly at the expense of extra delay and higher memory requirements in implementation.

Whenever retransmission is required, the retransmission typically uses a different set of coded bits than the previous transmission. The receiver combines the retransmission with previous transmission attempts of the same packet. As the retransmission may contain additional parity bits not included in the previous transmission attempts, the resulting code rate is generally lowered by retransmission. Furthermore, each retransmission does not necessarily have to consist of the same number of coded bits as the original and, in general, the modulation scheme can also be different for different retransmissions.

Typically, incremental redundancy is based on a low-rate code and the different redundancy versions are generated by puncturing the output of the encoder as is also illustrated in Fig. 5. In the first transmission, only a limited number of coded bits are transmitted, effectively leading to a high-rate code. In the retransmissions, additional coded bits are transmitted. As an example, let us assume a basic rate 1/4 code (1/4 information bits and 3/4 redundancy bits). In the first transmission, only every third coded bit is transmitted, effectively giving a rate of 3/4 code. In the case of a decoding error and a subsequent request for retransmission, additional bits are transmitted, effectively leading to a rate of e.g. 3/8 code. After the second retransmission the code rate may be 1/4 caused by transmission of further bits. In the case of more than two retransmissions, transmitted coded bits may be repeated - they may repeat again the bits transmitted in the initial transmission, then the bits transmitted by the first retransmission and then the bits of the second retransmission. However, such repetition is not necessary and another, different subset of bits may be transmitted. In addition to a gain in accumulated received Eb/NO, incremental redundancy also results in a coding gain for each retransmission. The gain with IR compared to chase combining is thus larger for high initial code rates, while at lower initial coding rates chase combining is almost as good as IR. It is noted that the performance gain of incremental redundancy compared to chase combining can also depend on the relative power difference between the transmission attempts or further factors.

In summary, HARQ with soft combining, regardless of whether chase or incremental redundancy is used, may lead to an implicit reduction of the data rate utilizing retransmissions and can thus be seen as an implicit link adaptation. However, in contrast to link adaptation based on explicit estimates of the instantaneous channel conditions, HARQ with soft combining implicitly adjusts the coding rate based on the result of the decoding. In terms of overall throughput, this kind of implicit link adaptation can be superior to explicit link adaptation, since additional redundancy is only added when needed - that is when previous higher-rate transmissions were not possible to decode correctly. Furthermore, as it does not try to predict any channel variations, it works equally well, regardless of the speed at which the terminal is moving. One possible reason for having explicit link adaptation is the reduced delay. Although relying on implicit link adaptation alone may be sufficient from a system throughput perspective, the end-user service quality may not be acceptable from a delay perspective for some applications. On the other hand, for some services, the implicit link adaptation may be more beneficial.

HARQ within the layer model

The HARQ can be performed at different processing layers of the communication interface. Correspondingly, protocol data units (PDUs) of different processing layers may be the retransmission units of the HARQ.

Two exemplary HARQ units which have been considered so far for HARQ are: MPDU (Medium Access Layer, MAC, PDU) and a codeword (CWs of FEC on physical, PHY, layer). Several contributions in the standardization of IEEE 802.11 have raised concerns that an MPDU cannot be considered as a HARQ unit, for the following reasons: different payload between retransmissions (e.g., due to changes in MPDU header) and misalignment between MPDUs and codewords on physical layer which makes it difficult to properly apply combining.

Misalignment between MPDUs and CWs may come from using not matching data to perform retransmission, so that combining between several copies of the data may not be possible. On the other hand, the 802.11 specifications (and hence respective implementations) so far assume the following:

1 . The physical layer (PHY) receives a PSDU (Physical Service Data Unit) from the MAC layer and is not aware of the MPDU boundaries, their length, delimiters, etc.

2. The FEC (e.g. LDPC) operates on blocks of information bits, regardless of MPDU boundaries.

3. A Block ACK (BA) indicates which MPDUs (within an aggregated MPDU, A-MPDU) were decoded correctly, so that the retransmission occurs only for incorrectly decoded MPDUs.

A retransmission of the failed MPDUs may in general include different coded bits due to a different set of the FEC, as illustrated in Fig. 6. Fig. 6 shows an exemplary frame format on physical layer and MAC, compliant with some IEEE 802.11 versions. In particular, a MAC Service Data Unit (MSDU) which may be an aggregated (A)-MSDU is received from a higher layer (layer above MAC) in the transmitter side processing stack. MAC layer processes the (A)-MSDU to obtain one or more MPDUs, which results in adding MAC layer overhead. In this example, the overhead includes the MAC Header and Frame Check Sequence (FCS). The FCS may be a CRC or the like for detecting whether or not the MPDU contains an error at the receiver. In this example, the data of the (A)-MSDU are encrypted, resulting in encrypted data, and additional overhead of encryption header and encryption tail. However, it is noted that in general, the encryption does not have to be performed on MAC layer and that the overhead structure may look differently. For the purpose of the present disclosure, the particular content of the overhead is immaterial. One or more such MPDUs may then be concatenated and provided to the physical layer for further processing. As can be seen in Fig. 6, the concatenation may involve further overhead such as various delimiters that serve as separation between the MPDUs and some padding, such as the end of the frame (EOF) padding shown herein. The physical layer receives the frame with concatenated three MPDUs padded to match the desired frame size constraint (e.g. multiples of bytes or the like) as the physical layer SDU (PSDU). The physical layer processes the PSDU further e.g. by applying FEC coding and adding some more overhead. The overhead may include the FEC redundancy and the some further control elements such as a service field shown in Fig. 6 and post- and/or pre- FEC padding if necessary (e.g. to match the physical layer frame size or constraints and/or to match the input size of the FEC encoder.). After applying the FEC coding to the PSDU, one or more codewords (CWs) are generated- in this example, seven CWs are shown.

As can be seen in Fig. 6, the boundaries between the MPDUs #1 , #2, and #3 do not match the boundaries between the seven codewords CW#1-CW#7. In case of a retransmission of an MPDU, the added overhead may look differently from the overhead of the previous (e.g. initial) transmission. Moreover, the FEC coding would generate different codewords because of incremental redundancy, in order to provide a different redundancy version. In general, incremental redundancy may be generated from the coded bits by puncturing in a way different from retransmission to retransmission. Different MPDUs with different CWs between the multiple copies obtained by multiple transmissions that are collected on the UE side may cause the misalignment problem.

In other words, the codewords of the initial transmission may not match the codewords of the retransmission(s). This may pose problems for combining on the physical layer at the receiver before applying the FEC decoding.

This may be a problem that leads to a reduced efficiency because the combining cannot be applied as it was possible with physical layer retransmissions. Reusing the existing (retransmission) mechanism, the Log-Likelihood Ratios (LLRs) respective to retransmitted coded bits cannot simply be combined with old (previously received) LLRs, as there is the misalignment between old and new codewords.

On the other hand, the problem in the codeword retransmission is how the transmitter regenerates the same CWs upon the retransmission. Some disadvantages of this solution have been identified. For example, a large amount of memory may be necessary on the transmitter side (since the encoded data are to be stored stored). It may need a new (codeword) block-ACK design, which may mean more overhead and also more time needed for specification design. It is unclear whether it yields better performance (e.g., throughput increase) than the MPDU retransmissions. The MPDU retransmissions also have further disadvantages if the solution should work properly: It needs memory to save the MPDUs/delimiters for future retransmissions (alternatively it would need a complicated state machine to re-generate the same MPDUs and delimiters). HARQ has to be managed in both PHY & MAC if the misalignment problem needs to be addressed.

Pre-configured redundancy versions

In order to improve the situation described above, the redundancy versions may be preconfigured, rather than freely obtainable by means of a cyclic buffer pointer or by various puncturing schemes.

Inspired by the rate splitting, a pre-planned IR HARQ approach may be applied e.g. to Wi-Fi networks or other wireless communication networks. By adopting this approach, the data of both MPDU and CWs layers may be combined and thus, boost the data throughput to the networks. This is illustrated in Fig. 7 and applicable to any type of channel coding such as block codes, convolutional codes, and turbo codes.

As can be seen in Fig. 7, the coded bits are separated into four disjoint redundancy versions which are then used respectively for the initial transmission, first retransmission, second retransmission, and third retransmission. The approach may be repeated cyclically, so that the fourth retransmission correspond to (has same data as) the initial transmission, the fifth retransmission corresponds to the first retransmission, etc. If the redundancy versions are disjoint (nonoverlapping), they can be merely added to the already buffered previous transmissions and used together with the buffered previous transmissions as an input to the FEC decoder. In principle, the redundancy versions do not need to be disjoint, but it is helpful if they are pre-configured so that the physical layer at the receiver can combine them more easily.

For example, the approach of Fig. 7 may be used for communication between a base station (BS) and the user equipment (UE) as described with reference to Fig. 2.

The BS transmits a first packet to the UE. The UE receives the packet and performs FEC decoding and error detection (e.g. by checking a CRC). The UE stores the packet even if an error is detected in which case it also asks the BS for retransmission of the same packet by sending a feedback such as a negative acknowledgment (NACK) to the BS. The BS performs the retransmission according to the HARQ protocol. For example, the BS transmits the first part of the data (“redundancy part 1” in Fig. 7). If the first part is detected as erroneous, the BS will perform a first retransmission, in which the BS transmits the “redundancy part 2”. The UE checks for errors in the received data and estimated reliability of the data received so far and combining may be performed for that. On the other hand, if still the reliability is under the acceptable level, the UE may ask for another retransmission by sending the negative feedback NACK to the BS. Here, the BS will send the third part (“redundancy part 3”) to the UE. After that the UE again checks for errors. If the error level is still not acceptable, the UE will send a NACK to the BS. In this case, the BS will resend the remaining data (“redundancy part 4”).

In Fig. 7, the redundancy parts are non-overlapping portions of the coded bits (that may be one or more FEC codewords) which are transmitted according to a predefined order. After the redundancy part 4, if further retransmissions are necessary, the redundancy parts are transmitted cyclically again, starting from redundancy part 1 , 2, etc. At the receiver, the redundancy part may be concatenated thus resulting in reducing the coding rate. The concatenation is a simple operation and facilitates matching I aligning the (re)transmissions. However, latency is introduced especially in case of bad channel conditions, as it may take several HARQ rounds in order to achieve the possibly necessary full coding rate.

In view of this, Fig. 8 shows an approach in which the first transmission includes the entire data 200 to be transmitted with a full (lowest) code rate. The receiver receives a possibly deteriorated version 201 of the data 200. If the received data 201 can be decoded successfully (e.g. with a sufficient reliability), no further retransmissions are necessary. Since the Data 200 are transmitted with the full code rate, the first transmission may be considered as having a high probability of being decoded successfully.

If, however, the reliability of the data is not considered as sufficient enough, “Part 1” 210 of the data is transmitted, e.g. in response to a NACK received from the receiver or derived in another way (e.g. by absence of a positive acknowledgement, ACK). The “Part 1” is received at the receiver as possibly deteriorated data portion 211 . Received portion 211 may thus be combined with the corresponding parts of Data 201 . If further retransmission is deemed necessary to achieve the desired reliability, “Part 2” 220 of the data 200 is transmitted and received as data portion 221 , possibly deteriorated due to transmission errors that may result from changing channel conditions. Again, combining may be applied to the received parts 201 , 211 , and/or 221 . If the reliability is still not sufficient, “Part 3” 230 of the data may be transmitted and received as data portion 231 , which may be further combined with the other portions received so far, namely 201 , 211 , and/or 221. If further retransmissions are necessary, in one exemplary implementation, parts 210, 220, and 230 are retransmitted in this order cyclically as respective further retransmissions. In another exemplary implementation, Data 200 and then parts 210, 220, and 230 are retransmitted in this order cyclically as respective further retransmissions. These, however, are merely examples and the order may be different, there may be more or less parts than 3, or the like.

Reliability or success or the decoding may be determined by any manner known from the state of the art. For example, CRC check may be used to check the correctness of the decoding. Alternatively, or in addition, results of the soft decoding and/or demodulation may be used to indicate reliability of the decoding and/or demodulation. Alternatively, or in addition, estimated signal to noise ratio may be used as an indicator of reliability.

It is noted that in this example, the data 200 are separated to Part 1 210, Part 2 220 and Part 3 230. These parts 210, 220, and 230 when concatenated, result in the data 200. As in Fig. 7, parts 1-3 are non-overlapping. However, unlike in Fig. 7, in this example, the first transmission does not include merely one of the parts forming the data 200, but the entire data 200.

Fig. 8 illustrates that the first transmission is performed over the entire encoded data block. Then, the parts of the encoded data block are retransmitted. The present disclosure is not limited to any particular buffering. For example, the encoded data block may be stored after transmission and deleted if a positive acknowledgement is received or derived. If a negative acknowledgement is received or derived, the stored encoded data block is split into redundancy versions that are transmitted as retransmissions according to the predefined order. However, the encoded data block does not necessarily need to be stored. In some implementations, it is possible to store, after the transmission of the encoded data block as the first transmission, the data block and to encode it on demand, i.e. when a retransmission is necessary. This approach may be beneficial for the cases in which the HARQ is performed in a protocol layer higher than the protocol layer in which the FEC coding is performed.

Fig. 9 illustrates a transmitting device 300 according to some exemplary embodiments. The transmitting device 300 may be a part of any wireless communication device such as STA or AP, or, in general base station BS or terminal UE. The transmitting device 300 comprises memory 310, processing circuitry 320, and a wireless transceiver 330 (or a wireless transmitter 330), which may be capable of communicating with each other via a bus 301 . The transmitting device 300 may further include a user interface 340. However, for some applications, the user interface 340 is not necessary (for instance some devices for machine-to-machine communications or the like). The memory 310 may store one or more of firmware or software modules, which implement one or more embodiments of the present disclosure. The memory 310 may be read from by the processing circuitry 320. Thereby, the processing circuitry 320 may be configured to carry out the firmware/software implementing the embodiments. The processing circuitry 320 may include one or more processors and/or other kind of hardware (FPGAs, controllers, specialized hardware, or the like). The processing circuitry may be configured to generate a first transmission of a data block including a plurality of FEC code portions. The generating includes coding the data block with a forward error correcting, FEC, code. The wireless transceiver 330 may be configured to transmit the generated first transmission. The processing circuitry 320 may be further configured to generate redundancy versions of the data block. Each redundancy version corresponds to a respective FEC code portion out of said plurality of FEC code portions, and the redundancy versions differ from each other. The wireless transceiver 330 may be further configured to transmit the redundancy versions as retransmissions of the data block in accordance with a hybrid automatic repeat request protocol, HARQ.

The first transmission may be obtained by concatenating all different redundancy versions. Concatenation means that the two or more redundancy versions are ordered in a sequence one following the other according to a predefined order. The redundancy versions may be nonoverlapping (disjoint) as shown above with reference to Fig. 8, but does not have to be. In other words, two or more of the redundancy versions may include one or more same code portions.

It is noted that the processing circuitry may be also configured to control the transceiver to transmit the first transmission and/or the one or more redundancy version(s).

Fig. 10 illustrates functional modules that may be implemented by the device 300. In particular, software modules may be stored in the memory 310 and include a FEC module 360 configured to perform the FEC coding and a HARQ module 380 configured to perform the generation of the redundancy version and controlling the transmitter to transmit them in accordance with a HARQ protocol. The present disclosure is not limited to any particular HARQ protocol. Any of the known protocols may be used, such as a stop and go with one or a multiple parallel processes, go back N, or the like. Moreover, the HARQ may include sending positive acknowledgements only or negative acknowledgements only or both. When referring herein to a redundancy version, what is means is a portion of FEC coded data correlated with at least a portion of the data block. One of possible implementations of the FEC code may be a polar code. A polar code is a linear block error-correcting code. The code construction is based on a multiple recursive concatenations of a short kernel code which transforms the physical channel into virtual outer channels.

The kernel can be called a transform matrix. A transform matrix that may be used in an exemplary implementation is as follows:

1 0 0 0-

_T _ 1 1 0 0

¹ 1 0 1 0

.1 1 1 1.

This transform matrix comes from using a basic kernel which is [1 0; 1 1], where the semicolon is used to denote a new row. A transform matrix T is then obtained by multiplying (by a Kronecker product) two same basic kernels together. This results to four parts to be the inputs to the polar code. However, there may be more than four parts, if more than one Kronecker multiplication is applied or the basic kernel size is varied. The output of the polar code is represented by multiplying the inputs of the data with the transform matrix. Therefore, D1 +D2+D3+D4 is the first output corresponding to the first column of the matrix, and so on. Consequently, two parameters are configurable: how many parts of split data we have and the size of the transform matrix. In the above example, the same basic kernel has been multiplied by Kronecker product. However, two mutually different basic kernels may be used. It is noted that the above example is not to limit the present disclosure. In general, there may be binary or non-binary kernels; or the kernels can be mixed between the binary and the non-binary.

Fig. 11 illustrates an exemplary implementation showing a FEC code portion 400. The FEC code portion 400 includes four parts D1 , D2, D3, and D4. A particular example of a Polar code based on these four parts is schematically illustrated in Fig. 12. Fig. 12 shows the four parts D1 , D2, D3, and D4. These four parts are input to the outer polar encoder and concatenated as illustrated. An exemplary kernel of the outer polar code has been shown above. In the first stage of the recursion, D1 and D2 are concatenated to generate two parts O1 = [D1+D2, D2] and D3 and D4 are concatenated to generate two parts 02 = [D3+D4, D4], In the second stage, the first stage parts O1 and 02 are concatenated to finally obtain the parts 03 = [D1+D2+D3+D4, D2+D4, D3+D4, D4] corresponding to the FEC code portions mentioned above. These FEC code portions that form the respective redundancy versions are used in the first to fourth retransmissions, as is illustrated in Fig. 13. In particular, the first retransmission may include or consist of all data parts concatenated, forming the FEC code portion D1+D2+D3+D4, the second retransmission may include or consist of FEC code portion D2+D4, the third retransmission may include or consist of FEC code portion D3+D4, and the fourth retransmission may include or consist of FEC code portion D4.

Fig. 14 illustrates layer processing of a first transmission of the entire data block. Here, it is assumed that Part 1 corresponds to D1 , Part 2 corresponds to D2, Part 3 corresponds to D3, and Part 4 corresponds to D4. As can be seen, the first transmission in this example corresponds to concatenated all components of portion 03, namely D1+D2+D3+D4+D2+D4+D3+D4+D4. Here, “+” expresses concatenation rather than summation. Thus, the first transmission of the data block corresponds to the concatenation of all redundancy versions that differ from each other (subblocks of the data block). The term first transmission herein is used synonymously to the term new transmission.

In other words, the data block D1+D2+D3+D4+D2+D4+D3+D4+D4 consists of four FEC data portions D1+D2+D3+D4, D2+D4, D3+D4, and D4 that are the first to fourth respective redundancy versions in this example. In general, the data block may consist of concatenated all FEC code portions out of the plurality of FEC code portions. The redundancy versions differ from each other.

Fig. 14 shows that the first transmission (the data block 1400) is generated in or above MAC layer and encapsulated into a MAC frame. It is noted that the encryption does not have to be present on MAC and that this protocol stack is merely exemplary. The encryption may be already applied in higher layers (layers above MAC), such as the presentation layer, so that the data block already comprises encrypted data. The present disclosure is not limited to any particular encryption mechanism. Thus, the encryption header and/or tail may also be omitted on the MAC layer.

The MAC frames (MAC PDUs) may be further aggregated before they are provided to the physical layer as physical layer SDU (PSDU). However, MPDU aggregation does not have to be applied. Physical layer processing may include some further coding which is indicated by the codewords CW in Fig. 14. However, a further FEC coding does not need to be applied in the physical layer. The physical layer may further include modulation and mapping onto the wireless resources (not shown). Fig. 15 illustrates layer processing of a first retransmission. The first retransmission carries the first redundancy version 1410 which is the FEC code portion D1+D2+D3+D4. The remaining processing is similar as in case of the first transmission described with reference to Fig. 14.

Fig. 16 illustrates layer processing of a second retransmission. The second retransmission carries the second redundancy version 1420 which is the FEC code portion D2+D4. The remaining processing is similar as in case of the first transmission described with reference to Fig. 14.

Fig. 17 illustrates layer processing of a third retransmission. The third retransmission carries the third redundancy version 1430 which is the FEC code portion D3+D4. The remaining processing is similar as in case of the first transmission described with reference to Fig. 14.

Fig. 18 illustrates layer processing of a fourth retransmission. The fourth retransmission carries the fourth redundancy version 1440 which is the FEC code portion D4. The remaining processing is similar as in case of the first transmission described with reference to Fig. 14.

In general each FEC code portion may comprise one or more of a predefined parts (such as D1 - D4). Two or more (or all) FEC code portions of the same data block may include the same part. In the above example, there have been four parts and four FEC code portions. However, it is noted that the number of FEC code portions and the parts is not necessarily the same. Moreover the number of FEC code portions and/or the number of parts is not limited to four any may be less (e.g. 2) or more (e.g. 5, 6, or the like).

As is illustrated in Figs. 14-18, the redundancy versions are transmitted in a predefined order as the retransmissions of the data block. The predefined order here is the order of redundancy version (RV)1 , RV2, RV3, RV4. The predefined order may be cyclically repeated. For example, if after the fourth retransmission, a fifth or further retransmission is necessary, the fifth retransmission may again be the entire data block (as in the first transmission), the sixth retransmission may again be the first redundancy version, etc. In another example, the fifth retransmission may again be RV1 , without repeating the first transmission. The sixth retransmission may then be RV2, etc.

There may be a maximum number of retransmissions defined (e.g. in standard, or configured by signaling), after which the retransmission process ends for a data block even if it still not possible to decode the transmitted data successfully. In the example above, the redundancy versions (as well as the first transmission) were generated by separating first transmission data into parts and generating RVs out of these parts. Such separation and generating of RVs may already alone be considered as a FEC because the RVs include redundancy compared to the first transmission. The generation of the first transmission may be performed by separating data block into parts, or by receiving a plurality of the parts from the higher layer and using them or further concatenating them.

The above-described approach thus allows for pre-planned retransmissions which makes the receiver processing more efficient. It is noted that the four parts D1-D4 in the above examples may be different data portions of the SDU provided from the layer above. Thus, the four parts D1- D4 may carry disjoint data. By forming the first transmission so that in the first transmission, all parts are included at least once, the probability of the first transmission to be successful is increased. Various combinations of one or more of the four parts may then form redundancy versions.

In order to detect or estimate whether or not the decoding was successful, various approaches may be used. For example, if FEC decoding is a soft decoding working with soft values representing likelihoods of each the respective bits rather than only 0 or 2, the likelihoods may be used to estimate the reliability of the decoding. Based on the reliability a decision may be made at the receiver, whether or not a retransmission is to be performed.

In addition or alternatively to estimating the reliability (or success in decoding), in some implementations, the data block includes a cyclic redundancy check, CRC, calculated for the content of the data block; and/or the each of the plurality of FEC code portions comprises a CRC calculated over said FEC code portion.

For example, the decoder at the receiver may estimate the reliability of a retransmission based on the soft values decoded (likelihoods of the decoded bits) and decide to request retransmission without attempting the decoding of the combined data. The estimation of the reliability may be based on estimated signal to noise ratio or based on another reception quality indicator or metric.

As mentioned above, the CRC may be added to the FEC coded data. For example, instead of adding the CRC to the data block, the CRC may be added to the FEC coded data block and/or to the FEC code portions. This may be performed in the same layer as the FEC coding or in a layer below. The present disclosure is not limited to any particular protocol layer. Nevertheless, it may be advantageous to perform the coding of the data block in a protocol layer higher than a physical layer. Then, the HARQ may also be performed in the protocol layer higher than the physical layer. However, the present disclosure is not limited to such embodiments and it is also applicable to HARQ in the physical layer.

Still, the combining at the receiver may be performed at the physical layer even if the HARQ is performed higher. This may be possible e.g. by configuring the HARQ in a higher layer and the physical layer in such a manner that parts (e.g. D1-D4) of the data block are still recognizable (e.g. by matching for instance by correlation or other similarity metric) in the physical layer in the first transmission and the retransmissions. Such configuration may include for example dividing the parts into integer multiple of codewords CW of a FEC coding (if applied at all). Such configuration may be possible within an initial handshake or any configuration or reconfiguration of the protocol stack parameters or specified in a standard.

For example, the HARQ is performed in a medium access control, MAC, layer. In addition, or alternatively, the coding of the data block is performed in the MAC (as was illustrated above with reference to Figs. 14 to 18) or in a layer higher than the MAC.

In some embodiments, the layer higher than the MAC is a presentation layer. Accordingly, the data can be split and FEC coded to make the retransmissions more efficient (easier). Furthermore, the presentation layer may handle all issues related to data presentation and transport, including translation, encryption, and compression of the data.

As mentioned above, the FEC coding may be Polar coding. However, the present disclosure is not limited to Polar codes or any other FEC codes. The determining of the parts of the data block and their usage in the RVs may be performed in any way.

It is noted that the FEC coding used for the generation of the RVs is not necessarily the only FEC code applied (see e.g. codewords CW in previous examples). In general block codes or codes with memory such as convolutional or turbo codes may be used. The codes may be systematic or non-systematic. Such codes may be used on the same layer or below the layer of the FEC generating the RVs.

It may be advantageous to provide the additional FEC coding such that said coding of the data block comprises coding of the data block with a first code into two or more codewords and each of the FEC code portions consists of one or more of the two or more codewords. Providing such structure enabled using of any kind of codewords irrespectively of the code used. In the above mentioned example, the four parts D1-D4 can be codewords of a FEC code.

It is noted that even though the FEC coding described above for generating the redundancy versions may be on a higher layer than the physical layer, still, the physical layer can perform any additional method such as scrambling/interleaving or even applying another coding approach such as LDPC or the like. The combining may still be performed on physical layer if the matching of the first transmission and the retransmissions can be performed before decoding. However, it is also possible to perform the combining in the MAC layer or higher.

On the other hand, if no additional FEC or other processing that would result in an interleaving (different for the FEC code portions within the first transmission and the retransmissions) is applied at the PHY layer, combining can be performed directly in the physical layer. It is noted that with additional FEC or other processing, still combining on the physical layer may be possible, e.g. if it is ensured that the FEC coded portions included in the first transmission and in the retransmissions remain the same or similar so that they can be matched at the receiver.

An exemplary receiving device 500 is illustrated in Fig. 19, comprising a wireless transceiver 530 and a processing circuitry 520. The transceiver 530 is configured to receive a first transmission of a data block including a plurality of FEC code portions. The processing circuitry 520 is configured to decode said first transmission with a forward error correcting, FEC, code. The transceiver 530 is further configured to receive one or more redundancy versions as retransmissions of the data block in accordance with a hybrid automatic repeat request protocol, HARQ. Each redundancy version includes a respective FEC code portion out of said plurality of FEC code portions. The processing circuitry 520 is further configured to combine corresponding FEC code portions of said received one or more redundancy versions and/or the first transmission, and to decode the combined FEC codewords.

The receiving device 500 may further include a memory 510. The memory may store a program code, which when executed by the processing circuitry 520, configures the processing circuitry to perform the above mentioned steps. An exemplary functional memory content is illustrated in Fig. 20. In particular, the memory 510 includes a FEC module 560 and a HARQ module 580. The FEC module 560 may perform the segmentation and/or concatenation of the data to form the FEC portions to decode the first transmission and the retransmissions. The HARQ module then performed the retransmissions. The processing circuitry 520 may communicate with the memory 510 and/or the wireless transceiver 530 via a bus (or a system of buses) 501 . The wireless device 500 may further include a user interface 540, over which a user may control the receiving device. The processing circuitry 520 may comprise one or more processors and/or specialized or programmable hardware pieces. The present disclosure is not limited to any particular type of memory or wireless transceiver or user interface.

In an exemplary implementation, the combining is performed on the physical layer by matching the first transmission with the corresponding portions of the received one or more redundancy versions. It is noted that the combining may be a soft combining. The soft values may be used to estimate reliability of the combined data.

The receiver and the transmitter may use signaling to specify the FEC coding I HARQ parameters, such as the size of the data block, the FEC code, a maximum number of retransmission or the like. In an exemplary implementation, the redundancy versions are generated to correspond to one or more non-overlapping parts of the data block. Since the redundancy versions are predefined segments of the first transmission (data block), there is no need for additional indicators/updating the frame structure. There is also no need for using special kinds of buffers such as cyclic buffer. It is easy to perform the retransmission by resending data in a systematic approach.

Correspondingly to the transmitter side, the redundancy versions are received sequentially in a predefined order. For example, the data block includes a cyclic redundancy check, CRC, calculated for the content of the data block; and the method further comprises determining whether or not the decoding of the data block has been successful based on the CRC.

In some implementations, the decoding of the data block based on the first transmission and/or the received one or more redundancy versions is performed in a protocol layer higher than the physical layer, and the HARQ is performed in the protocol layer higher than the physical layer.

HARQ with soft combining, regardless of whether chase or incremental redundancy is used, may lead to an implicit reduction of the data rate employing retransmissions and can thus be seen as implicit link adaptation. However, in contrast to link adaptation based on explicit estimates of the instantaneous channel conditions, HARQ with soft combining implicitly adjusts the coding rate based on the result of the decoding. In terms of overall throughput, this kind of implicit link adaptation can be superior to explicit link adaptation, as additional redundancy is only added when needed which is when it is not possible to correctly decode previous higher-rate transmissions. Furthermore, as HARQ does not try to predict any channel variations, it works equally well, regardless of the speed at which the terminal is moving. Such an approach may facilitate to address the misalignment problem in a WLAN network, latency may be reduced, and the throughput may be increased. Furthermore, the number of retransmissions may be reduced, depending on how many redundancy parts there are.

Inspired by the rate splitting, the above described pre-planned IR HARQ approach by implicitly splitting the data to be transmitted into several parts has been designed. At the first transmission, the BS will send the whole data which is implicitly split into several parts. When the user asks for retransmission, the BS will send the first part of the split data. Where this part is aligned with what has been sent first. If both copies have the same data and then MPDUs and CWs, the misalignment may be avoided. The correspondence between the IR transmissions may be achieved by configuring the protocol stack accordingly (e.g. by handshaking signaling before the first data transmission). Now, if the UE asks for second retransmission, the BS will send the second part of the split data and so on.

However, the combining is not necessarily performed at the physical layer. It may be performed in higher layers, e.g. on MAC, if the HARQ is performed on MAC.

Fig. 21 is a flow diagram showing a transmitting method. The transmitting method comprises step 2110 of generating a first transmission of a data block including a plurality of FEC code portions, the generating including coding the data block with a forward error correcting, FEC, code. Furthermore, the method comprises step 2120 of transmitting the first transmission and step 2130 of testing whether or not the reception of the data block was successful.

If the reception is successful in step 2130, the transmission of the data block ends, i.e. the buffer including the data block portions may be flushed. Otherwise, step 2140 comprises generating redundancy version(s) of the data block, wherein each redundancy version corresponds to a respective FEC code portion out of said plurality of FEC code portions, and the redundancy versions differ from each other. Step 2150 then includes transmitting the redundancy versions as retransmissions of the data block in accordance with a hybrid automatic repeat request protocol, HARQ. It is noted that the test in step 2130 may be based on a feedback (e.g. ACK or NACK) from the data receiving device. The test is repeated after each retransmission 2150. Fig. 22 illustrates a receiving method. The receiving method comprises step 2210 of receiving a first transmission of a data block including a plurality of FEC code portions. Moreover the method includes step 2220 of decoding said first transmission with a forward error correcting, FEC, code.

Step 2230 is a test of whether or not the decoding was successful. In case the decoding of the first transmission is successful, the transmission of the data block finishes. In case the decoding of the first transmission is not successful, the method included step 2240 of receiving one or more redundancy versions as retransmissions of the data block in accordance with a hybrid automatic repeat request protocol, HARQ, wherein each redundancy version includes a respective FEC code portion out of said plurality of FEC code portions. Step 2250 comprises combining corresponding FEC code portions of said received one or more redundancy versions and/orthe first transmission, and decoding the combined FEC codewords.

It is noted that some exemplary implementations of the methods for transmitting and receiving include features that have been described above with reference to the respective transmitting and receiving devices (e.g. steps performed by the processing circuitry and/or the transceiver.

Implementations in software and hardware

It is noted that although embodiments and examples of the present disclosure were provided in terms of a method above, the corresponding devices providing the functionality described by the methods are also provided. Moreover, it is noted that any of the steps described above may be included as code instructions in a program, which may be executed by one or more processors.

The methodologies described herein may be implemented by various means depending upon the application. For example, these methodologies may be implemented in hardware, operation system, firmware, software, or any combination of two or all of them. For a hardware implementation, any processing circuitry may be used, which may include one or more processors. For example, the hardware may include one or more of application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, any electronic devices, or other electronic circuitry units or elements designed to perform the functions described above. If implemented as program code, the functions performed by the transmitting apparatus (device) may be stored as one or more instructions or code on a non-transitory computer readable storage medium. The computer-readable media includes physical computer storage media, which may be any available medium that can be accessed by the computer, or, in general by the processing circuitry. Such computer-readable media may comprise RAM, ROM, EEPROM, optical disk storage, magnetic disk storage, semiconductor storage, or other storage devices. Some particular and non-limiting examples include compact disc (CD), CD-ROM, laser disc, optical disc, digital versatile disc (DVD), Blu-ray (BD) disc or the like. Combinations of different storage media are also possible - in other words, distributed and heterogeneous storage may be employed.

The above examples are not to limit the present disclosure. There are many modifications and configurations, which may be used in addition or alternatively. This present disclosure can be used in any kind of device that is receiving signals over a wireless channel. The embodiments and exemplary implementations mentioned above show some non-limiting examples. It is understood that various modifications may be made without departing from the claimed subject matter. For example, modifications may be made to adapt the examples to new systems and scenarios without departing from the central concept described herein.

Selected embodiments and examples

Summarizing, methods and techniques are described for performing HARQ in a pre-planned manner by transmitting an entire data block at first and then retransmitting, if necessary, predefined portions of the data block.

In particular, according to a first aspect, a transmitting method is provided, comprising: generating a first transmission of a data block including a plurality of FEC code portions, the generating including coding the data block with a forward error correcting, FEC, code; transmitting the first transmission; generating redundancy versions of the data block, wherein (i) each redundancy version corresponds to a respective FEC code portion out of said plurality of FEC code portions, and (ii) the redundancy versions differ from each other; and transmitting the redundancy versions as retransmissions of the data block in accordance with a hybrid automatic repeat request protocol, HARQ.

According to a second aspect, further to the first aspect, the redundancy versions are transmitted in a predefined order as the retransmissions of the data block. According to a third aspect, further to the first or the second aspect, the data block includes a cyclic redundancy check, CRC, calculated for the content of the data block; and/or the each of the plurality of FEC code portions comprises a CRC calculated over said FEC code portion.

According to a fourth aspect, further to any of the first to the third aspect, the coding of the data block is performed in a protocol layer higher than a physical layer, and/or the HARQ is performed in the protocol layer higher than the physical layer.

According to a fifth aspect, further to the fourth aspect, the HARQ is performed in a medium access control, MAC, layer.

According to a sixth aspect, further to the fourth or the fifth aspect, the coding of the data block is performed in the MAC or in a layer higher than the MAC.

According to a seventh aspect, further to the sixth aspect, the layer higher than the MAC is a presentation layer.

According to an eighth aspect, further to any of the first to the seventh aspect, said coding of the data block comprises coding of the data block with a first code into two or more codewords; and each of the FEC code portions consists of one or more of the two or more codewords.

According to a ninth aspect, further to any of the first to the eight aspect, the FEC code is a Polar code.

According to a tenth aspect, a receiving method is provided, comprising: receiving a first transmission of a data block including a plurality of FEC code portions; decoding said first transmission with a forward error correcting, FEC, code; in case the decoding of the first transmission is not successful: (i) receiving one or more redundancy versions as retransmissions of the data block in accordance with a hybrid automatic repeat request protocol, HARQ, wherein each redundancy version includes a respective FEC code portion out of said plurality of FEC code portions, (ii) combining corresponding FEC code portions of said received one or more redundancy versions and/or the first transmission, (iii) decoding the combined FEC codewords.

According to an eleventh aspect, further to the tenth aspect, the combining is performed on physical layer by matching the first transmission with the corresponding portions of the received one or more redundancy versions. According to a twelfth aspect, further to the tenth or eleventh aspect, the combining is a soft combining.

According to a thirteenth aspect, further to any of the tenth to twelfth aspect, the redundancy versions are received sequentially in a predefined order.

According to a fourteenth aspect, further to any of the tenth to the thirteenth aspect, the data block includes a cyclic redundancy check, CRC, calculated for the content of the data block; and the method further comprises determining whether or not the decoding of the data block has been successful based on the CRC.

According to a fifteenth aspect, further to any of the tenth to the fourteenth aspect, the decoding of the data block based on the first transmission and/or the received one or more redundancy versions is performed in a protocol layer higher than the physical layer, and the HARQ is performed in the protocol layer higher than the physical layer.

According to a sixteenth aspect, further to the fifteenth aspect, the HARQ is performed in a medium access control, MAC, layer.

According to a seventeenth aspect, further to fifteenth or sixteenth aspect, the decoding of the data block is performed in the MAC or in a layer higher than the MAC.

According to an eighteenth aspect, further to the seventeenth aspect, the layer higher than the MAC is a presentation layer.

According to a nineteenth aspect, further to any of the tenth to the eighteenth aspect, each of the FEC code portions consists of one or more codewords; and said decoding of the data block comprises decoding of the data block with a first code from the one or more codewords of each of the plurality of the FEC code portions.

According to a twentieth aspect, further to any of the tenth to the nineteenth aspect, the FEC code is a Polar code.

According to a twenty-first aspect, a transmitting device is provided, comprising: processing circuitry configured to generate a first transmission of a data block including a plurality of FEC code portions, the generating including coding the data block with a forward error correcting, FEC, code; and generate redundancy versions of the data block, wherein (i) each redundancy version corresponds to a respective FEC code portion out of said plurality of FEC code portions, and (ii) the redundancy versions differ from each other; and (iii) a transceiver configured to transmit the first transmission and to transmit the redundancy versions as retransmissions of the data block in accordance with a hybrid automatic repeat request protocol, HARQ.

According to a twenty-second aspect, a receiving device is provided, comprising a transceiver configured to receive a first transmission of a data block including a plurality of FEC code portions; and processing circuitry configured to decode said first transmission with a forward error correcting, FEC, code, wherein the transceiver is further configured to receive one or more redundancy versions as retransmissions of the data block in accordance with a hybrid automatic repeat request protocol, HARQ, and each redundancy version includes a respective FEC code portion out of said plurality of FEC code portions; and the processing circuitry is further configured to: (i) combine corresponding FEC code portions of said received one or more redundancy versions and/or the first transmission, and (ii) decode the combined FEC codewords.

Claims

1 . A transmitting method comprising: generating a first transmission of a data block including a plurality of FEC code portions, the generating including coding the data block with a forward error correcting, FEC, code; transmitting the first transmission; generating redundancy versions of the data block, wherein

- each redundancy version corresponds to a respective FEC code portion out of said plurality of FEC code portions, and

- the redundancy versions differ from each other; and transmitting the redundancy versions as retransmissions of the data block in accordance with a hybrid automatic repeat request protocol, HARQ.

2. The transmitting method according to claim 1 , wherein the redundancy versions are transmitted in a predefined order as the retransmissions of the data block.

3. The transmitting method according to claim 1 or 2, wherein the data block includes a cyclic redundancy check, CRC, calculated for the content of the data block; and/or the each of the plurality of FEC code portions comprises a CRC calculated over said FEC code portion.

4. The transmitting method according to any of claims 1 to 3, wherein the coding of the data block is performed in a protocol layer higher than a physical layer, and/or the HARQ is performed in the protocol layer higher than the physical layer.

5. The transmitting method according to claim 4, wherein the HARQ is performed in a medium access control, MAC, layer.

6. The transmitting method according to claim 4 or 5, wherein the coding of the data block is performed in the MAC or in a layer higher than the MAC.

7. The transmitting method according to claim 6, wherein the layer higher than the MAC is a presentation layer.

8. The transmitting method according to any of claims 1 to 7, wherein said coding of the data block comprises coding of the data block with a first code into two or more codewords; each of the FEC code portions consists of one or more of the two or more codewords.

9. The transmitting method according to any of claims 1 to 8, wherein the FEC code is a Polar code.

10. A receiving method comprising: receiving a first transmission of a data block including a plurality of FEC code portions; decoding said first transmission with a forward error correcting, FEC, code; in case the decoding of the first transmission is not successful:

- receiving one or more redundancy versions as retransmissions of the data block in accordance with a hybrid automatic repeat request protocol, HARQ, wherein each redundancy version includes a respective FEC code portion out of said plurality of FEC code portions,

- combining corresponding FEC code portions of said received one or more redundancy versions and/or the first transmission,

- decoding the combined FEC codewords.

11 . The receiving method according to claim 10, wherein the combining is performed on physical layer by matching the first transmission with the corresponding portions of the received one or more redundancy versions.

12. The receiving method according to claim 10 or 11 , wherein the combining is a soft combining.

13. The receiving method according to any of claims 10 to 12, wherein the redundancy versions are received sequentially in a predefined order.

14. The receiving method according to any of claims 10 to 13, wherein the data block includes a cyclic redundancy check, CRC, calculated for the content of the data block; and the method further comprises determining whether or not the decoding of the data block has been successful based on the CRC.

15. The receiving method according to any of claims 10 to 14, wherein the decoding of the data block based on the first transmission and/or the received one or more redundancy versions is performed in a protocol layer higher than the physical layer, and the HARQ is performed in the protocol layer higher than the physical layer.

16. The receiving method according to claim 15, wherein the HARQ is performed in a medium access control, MAC, layer.

17. The receiving method according to claim 15 or 16, wherein the decoding of the data block is performed in the MAC or in a layer higher than the MAC.

18. The receiving method according to claim 17, wherein the layer higher than the MAC is a presentation layer.

19. The receiving method according to any of claims 10 to 18, wherein each of the FEC code portions consists of one or more codewords; and said decoding of the data block comprises decoding of the data block with a first code from the one or more codewords of each of the plurality of the FEC code portions.

20. The receiving method according to any of claims 10 to 19, wherein the FEC code is a Polar code.

21 . A transmitting device comprising: processing circuitry configured to: generate a first transmission of a data block including a plurality of FEC code portions, the generating including coding the data block with a forward error correcting, FEC, code; and generate redundancy versions of the data block, wherein

- the redundancy versions differ from each other; and a transceiver configured to transmit the first transmission and to transmit the redundancy versions as retransmissions of the data block in accordance with a hybrid automatic repeat request protocol, HARQ.

22. A receiving device comprising a transceiver configured to receive a first transmission of a data block including a plurality of FEC code portions; and processing circuitry configured to decode said first transmission with a forward error correcting, FEC, code, wherein the transceiver is further configured to receive one or more redundancy versions as retransmissions of the data block in accordance with a hybrid automatic repeat request protocol, HARQ, and each redundancy version includes a respective FEC code portion out of said plurality of FEC code portions; and the processing circuitry is further configured to:

- combine corresponding FEC code portions of said received one or more redundancy versions and/or the first transmission, and

- decode the combined FEC codewords.