WO2016139027A1

WO2016139027A1 - Radio communication system with multiple radio access technologies applying network coding

Info

Publication number: WO2016139027A1
Application number: PCT/EP2016/052507
Authority: WO
Inventors: Markus Dominik Mueck; Christian Drewes; Abhijeet Bhorkar; Konstantinos Dimou; Gwenael Kosider
Original assignee: Intel IP Corporation
Priority date: 2015-03-05
Filing date: 2016-02-05
Publication date: 2016-09-09
Also published as: DE102015103248B4; DE102015103248A1

Abstract

A method of processing a message to be transmitted in a radio communication network is described. The method includes channel encoding a first bit stream representing a message. A combined bit stream is generated by combining at least a portion of the channel encoded first bit stream with at least a portion of a second bit stream, wherein the second bit stream representing at least partly the message. The channel encoded first bit stream is configured to be transmitted over a first radio link of the radio communication network and the combined bit stream is configured to be transmitted over a second radio link of the radio communication network.

Description

RADIO COMMUNICATION SYSTEM APPLYING NETWORK CODING

TECHNICAL FIELD

[ 0001 ] Embodiments described herein generally relate to the field of radio communications, and more particularly to the techniques of encoding and/or decoding signals transmitted over at least two radio links.

BACKGROUND

[ 0002 ] Radio communication networks use channel coding to improve integrity and quality of the received information. Various channel coding techniques are known, among them forward error correction (FEC) using, e.g., convolutional codes and/or block codes. In general, channel coding adds extra bits (socalled parity bits) to a bitstream to be transmitted and uses these extra bits to recover the transmitted information at the receiver even in case some of the transmitted bits are lost or erroneously detected at the receiver.

[ 0003 ] Bit-level transmission between different devices is based on Physical Layer (PHY) functionality. PHY functionality includes, among others, channel coding and interleaving. Various channel coding schemes may be available and are defined in existing mobile communication standards. Typically, existing channel coding schemes of a standard should be preserved in advanced PHY channel coding definitions in order keep the transmission compatible with standard or legacy devices, i.e. devices which do not support any modified coding schemes to be implemented in the advanced standard. This imposes restrictions on extending channel coding in a standard.

[ 0004 ] For these and other reasons, it is an object to modify available Physical Layer Coding schemes of existing standards to improve the performance of the mobile communication network while keeping the transmission compatible with standard devices .

BRIEF DESCRIPTION OF THE DRAWINGS

[ 0005 ] The accompanying drawings are included to provide a further understanding of examples of the disclosure and are incorporated in and constitute a part of this specification. The drawings illustrate examples and together with the description serve to explain principles of examples. Other examples and many of the intended advantages of examples will be readily appreciated as they will become better understood by reference to the following detailed description. [ 0006] Figure 1 is a schematic illustration of an exemplary radio communication network.

Figure 2 is a directed graph illustrating a classical butterfly

[ 0008] Figure 3 is a model illustrating an exemplary application of the classical butterfly network of Figure 2 to a radio communication network.

[ 0009] Figure 4 is a block diagram illustrating a general model of a radio communication network as obtained by the application of the model of Figure 3 to an exemplary heterogeneous radio communication network.

[ 0010] Figure 5 is a block diagram illustrating a restricted model of an exemplary radio communication network.

[ 0011] Figure 6 is an illustration of a radio communication network indicating radio links available for legacy receivers and radio links non-available for legacy receivers.

[ 0012 ] Figure 7 illustrates a plurality of directional radio links and a shared radio link for data transmission in a radio communication network.

[ 0013] Figure 8A is a block diagram illustrating channel encoders and a channel decoder as used for transmitting and receiving data over two radio links in a radio communication network.

[ 0014 ] Figure 8B is a block diagram illustrating channel encoders and channel decoders as used for transmitting and receiving data over three radio links in a radio communication network.

[ 0015] Figure 9 illustrates an exemplary error correction approach for a bit stream received over a first radio link by a network coded bit stream received over a second radio link.

[ 0016] Figure 10 is an exemplary illustration of a convolutional channel encoder .

[ 0017 ] Figure 11 illustrates an exemplary data transmission approach using three radio links to obtain more flexibility and/or less errors. [ 0018] Figure 12 is a block diagram illustrating a plurality of possible receiver architectures as may be used in a radio communication network.

[ 0019] Figure 13 is an illustration of a radio communication network indicating the approach of network coding for a mobile station-to-mobile station connection.

[ 0020] Figure 14 is a block diagram illustrating an exemplary implementation of two convolutional channel encoders and an exemplary implementation of a combiner for network encoding.

[ 0021] Figure 15 is a graph illustrating the bit error rate (BER) versus the Eb/No of two radio links with and without network coding.

DESCRIPTION OF EMBODIMENTS

[ 0022 ] In the following detailed description, reference is made to the accompanying drawings, which form a part thereof, and in which is shown by way of illustration embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims.

[ 0023] It is to be understood that the features of the various exemplary embodiments described herein may be combined with each other, unless specifically noted otherwise. Further, like reference numerals designate corresponding identical or similar parts.

[ 0024 ] As employed in this specification, the terms "coupled" and/or "connected" are not meant to mean in general that the elements must be directly coupled or connected together; intervening functional elements may be provided between the "coupled" or "connected" elements. However, although not restricted to that meaning, the terms "coupled" and/or "connected" may also be understood to optionally disclose an implementation in which the elements are directly coupled or connected together without intervening elements provided between the "coupled" or "connected" elements .

[ 0025] It should be understood that embodiments may be implemented in discrete circuits, partially integrated circuits or fully integrated circuits. Further, embodiments may be implemented on a single semiconductor chip or on multiple semiconductor chips connected to each other. Furthermore, it should be understood that embodiments may be implemented in software or in dedicated hardware or partially in software and partially in dedicated hardware.

[ 0026] Methods and devices described herein may be implemented in a base station (NodeB, eNodeB) or a mobile device (or mobile station or User Equipment

(UE) ) . The described devices may include integrated circuits and/or passives and may be manufactured according to various technologies. For example, the circuits may be designed as logic integrated circuits, analog integrated circuits, mixed signal integrated circuits, optical circuits, memory circuits, integrated passives, etc.

[ 0027 ] The transmitters, channel encoders and channel decoders and receivers described herein may be used for various wireless communication networks. The terms "network", „system" and "radio communications system" may be used synonymously herein.

[ 0028 ] A radio communication network as described herein may be a heterogeneous radio communication network. A heterogeneous radio communication network may be a network in which different radio access technologies (RATs) are integrated and may be jointly managed. For example, 5G (5^th Generation) communication systems will support various RATs.

[ 0029] Different RATs use different radio access technologies, which are recorded in corresponding mobile communication standards. By way of example, a RAT implementing Code Division Multiple Access (CDMA) technology may be considered herein. By way of example, a WCDMA (Wideband CDMA) system defined by the 3GPP (3^rd Generation Partnership Project) is a system using CDMA technology. Further networks implementing CDMA are Universal Terrestrial Radio Access (UTRA) , cdma2000, etc. UTRA includes Wideband-CDMA (W-CDMA) and other CDMA variants . cdma2000 covers IS-2000, IS- 95 and IS-856 standards. Further, RATs considered herein may implement TDMA (Time Division Multiple Access) and/or FDMA (Frequency Division Multiple Access) technologies such as, e.g., Global System for Mobile Communications (GSM) networks and derivatives thereof, for example Enhanced Data Rate for GSM Evolution (EDGE) , Enhanced General Packet Radio Service (EGPRS) , including, e.g., developments such as, e.g., HSPA

(High-Speed Packet Access) and/or HSDPA (High-Speed Downlink Packet Access) . Moreover, RATs considered herein may use orthogonal frequency-division multiplexing (OFDM) technology, for example Long Term Evolution (LTE) networks or networks based on Evolved UTRA (E-UTRA) , Ultra Mobile Broadband (UMB) , IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX) , IEEE 802.20, or Flash-OFDM . RTM . Still further, RATs implementing millimeter wave (mmWave) technologies may be considered herein. By way of example, 5G communication systems will support a mmWave RA .

[ 0030 ] Whilst examples are disclosed herein in terms of LTE and LTE-A wireless networks, example and the teachings herein may equally be applied to other wireless network standards such as, but not limited to: cellular wide area radio communication technology (which may include e.g. a Global System for Mobile Communications (GSM) radio communication technology, a General Packet Radio Service (GPRS) radio communication technology, an Enhanced Data Rates for GSM Evolution (EDGE) radio communication technology, and/or a Third Generation Partnership Project (3GPP) radio communication technology (e.g. UMTS (Universal Mobile Telecommunications System) , FOMA (Freedom of Multimedia Access) , 3GPP LTE (Long Term Evolution) , 3GPP LTE Advanced (Long Term Evolution Advanced)), CDMA2000 (Code division multiple access 2000), CDPD (Cellular Digital Packet Data) , Mobitex, 3G (Third Generation) , CSD (Circuit Switched Data), HSCSD (High-Speed Circuit-Switched Data) , UMTS (3G) (Universal Mobile Telecommunications System (Third Generation) ) , W-CDMA (UMTS) (Wideband Code Division Multiple Access (Universal Mobile Telecommunications System) ) , HSPA (High Speed Packet Access) , HSDPA (High-Speed Downlink Packet Access) , HSUPA (High-Speed Uplink Packet Access), HSPA+ (High Speed Packet Access Plus), UMTS-TDD (Universal Mobile Telecommunications System - Time-Division Duplex) , TD-CDMA (Time Division - Code Division Multiple Access) , TD-CDMA (Time Division - Synchronous Code Division Multiple Access), 3GPP Rel . 8 (Pre-4G) (3rd Generation Partnership Project Release 8 (Pre-4th Generation)), 3GPP Rel. 9 (3rd Generation Partnership Project Release 9), 3GPP Rel. 10 (3rd Generation Partnership Project Release 10), 3GPP Rel. 11 (3rd Generation Partnership Project Release 11), 3GPP Rel. 12 (3rd Generation Partnership Project Release 12), 3GPP Rel. 13 (3rd Generation Partnership Project Release 13), 3GPP Rel. 14 (3rd Generation Partnership Project Release 14), UTRA (UMTS Terrestrial Radio Access) , E-UTRA (Evolved UMTS Terrestrial Radio Access) , LTE Advanced (4G) (Long Term Evolution Advanced ( 4th Generation) ) , cdmaOne (2G) , CDMA2000 (3G) (Code division multiple access 2000 (Third generation)), EV-DO

(Evolution-Data Optimized or Evolution-Data Only), AMPS (1G) (Advanced Mobile Phone System (1st Generation)), TACS/ETACS (Total Access Communication System/Extended Total Access Communication System) , D-AMPS (2G) (Digital AMPS (2nd Generation) ) , PTT (Push-to-talk) , MTS (Mobile Telephone System) , IMTS (Improved Mobile Telephone System), AMTS (Advanced Mobile Telephone System), OLT (Norwegian for Offentlig Landmobil Telefoni, Public Land Mobile Telephony) , MTD (Swedish abbreviation for Mobiltelefonisystem D, or Mobile telephony system D) , Autotel/PALM (Public Automated Land Mobile) , ARP (Finnish for

Autoradiopuhelin, "car radio phone"), NMT (Nordic Mobile Telephony), Hicap

(High capacity version of NTT (Nippon Telegraph and Telephone) ) , CDPD (Cellular Digital Packet Data), Mobitex, DataTAC, iDEN (Integrated Digital Enhanced Network) , PDC (Personal Digital Cellular) , CSD (Circuit Switched Data) , PHS

(Personal Handy-phone System), WiDEN (Wideband Integrated Digital Enhanced Network) , iBurst, Unlicensed Mobile Access (UMA, also referred to as also referred to as 3GPP Generic Access Network, or GAN standard) ) , Wireless Gigabit Alliance (WiGig) standard, mmWave standards in general (wireless systems operating at 10-70 GHz and above), WiFi (IEEE 802.1 la/b/g/n/ac/ad/af/etc . ) , WiMAX (IEEE 802.16a/e), etc.

[ 0031] It is to be noted that the mobile communication standards referred to herein shall include all existing and future releases of the standard (e.g. IEEE 802.11/a/b/g/ac/ad/n/af/etc... for Wi-Fi based on IEEE 802.11).

[ 0032 ] While some RATs provide for non-directional or quasi-omnidirectional transmission, other RATs, such as, e.g., a mmWave RAT may provide for transmissions which are typically (highly) directive, e.g. by applying highly directive patch antennas, etc. By way of example, LTE and/or Wi-Fi may provide for quasi-omnidirectional transmission, while mmWave technology provides for

(highly) directional transmission.

[ 0033] The term (quasi) omnidirectional (or (quasi) isotropic) as used for a technology or a radio link in this disclosure may, e.g., mean technologies using a radio link frequency range of less than, e.g., 6 GHz, whereas the term directional used herein for a technology or a radio link may, e.g., mean mmWave technologies using a radio link frequency range of, e.g., above 6 GHz. It is to be noted that within this meaning, some technologies having „weaker" directional properties, such as, for example, LTE may, may nevertheless be considered as (quasi) omnidirectional technologies rather than as directional technologies herein.

[ 0034 ] More specifically, in case that a sector based transmission is performed, as it is typically the case for cellular base stations, the proposed new techniques can be applied to a single sector or to all sectors or to any combination of sectors. Other sectors would then rely on the traditional encoding schemes. Also, in case that beam-forming is performed (and thus not the entire space is covered by a directional transmission) , the proposed scheme can be applied to the channel codes in the beam-forming based system or sub-system (in case that several transmissions are combined in which some are applying beam-forming or any other form of directional transmission and others are applying (quasi- ) isotropic or (quasi- ) omnidirectional transmission. Typical single-antenna transmissions (such as monopol or dipol antenna based transmissions) are considered to be (quasi- ) isotropic or

(quasi-) omnidirectional .

[ 0035 ] Figure 1 illustrates a schematic illustration of an exemplary radio communication network 100, of which a mobile station and two base stations BS1, BS2 are depicted. By way of example, the radio communication network 100 may be a 5G network. The radio communication network 100 may comprise a shared radio link 110 of, e.g., a carrier frequency of less than 6 GHz connecting the mobile station MS with the two (or more) remote base stations BS1, BS2. The shared radio link 110 may be a quasi-isotropic radio link. Further, the mobile station MS may be connected via a first directional radio link 120 1 to the first base station BS1 and may be connected via a second directional radio link 120 2 to the second base station BS2. It is to be noted that the mobile station MS may be a handheld radio device, a mobile phone, a smartphone, or any similar device. A mobile station MS may also be referred to as "user equipment" (UE) herein. The base stations BS1, BS2 may comprise any base stations deployed in radio communication networks, e.g. base stations of macrocells, picocells, femtocells, target-cells, etc. By way of example, base stations of different capabilities, e.g. different TX-power classes, maybe involved. Thus, the term eNodeB as occasionally used for base stations described herein shall be interpreted to comprise various specific terms such as MeNB (macro eNodeB) , PeNB (pico eNodeB) and HeNB (femto/home eNodeB), etc. The base stations BS1, BS2 may be capable of transmitting and/or receiving mmWave transmissions of, e.g., a carrier frequency of equal to or greater than 6 GHz.

[ 0036] In the following, the question is addressed on how to modify available Physical Layer (PHY) channel coding schemes of existing standards such that a joint transmission on at least two RATs may be achieved. By way of example, the existing standards may, e.g., be LTE, Wi-Fi, etc., or derivatives thereof. The existing standard(s) may, e.g., use the shared radio link 110. The future standard may be an implementation of any RAT using, e.g., the (highly) directive radio links 120 1, 120 2. [ 0037 ] Embodiments described in the following aim to improve the performance of the radio communication network 100 while leaving the PHY layer channel coding schemes used over the shared radio link 110 essentially unchanged. Thus, the transmissions in the radio communication network 100 remain compatible with standard (or legacy) mobile stations MS only supporting the channel coding schemes used for the shared radio link 110, e.g. the PHY channel coding schemes stipulated, e.g., in LTE or Wi-Fi, etc., and derivatives thereof. Furthermore, embodiments described herein may allow to implement proprietary devices (i.e. extensions not defined in any underlying standard) supporting the method of transmission in a heterogeneous radio communication network 100 as described herein. These devices (transmitters, channel encoders, receivers, channel decoders) may remain compatible with legacy devices as existing channel coding schemes used for one of the shared radio link 110 and the first and/or second directional radio links 120 1/120 2 are not changed while the modifications implemented in channel decoding are applied to the other of the shared radio link 110 and the first and/or second directional radio links 120 1/120 2.

[ 0038 ] Thus, embodiments described herein use a modification of existing PHY channel coding schemes in a context of a (heterogeneous) radio communication network 100 having a shared radio link 110 and (highly) directional radio links 120 1, 120 2 to be operated simultaneously. As already mentioned, the shared radio link 110 may be a quasi-omnidirectional (quasi-isotropic) radio link and/or may typically operate in a frequency range of less than 6 GHz, and the (highly) directional radio links 120 1, 120 2 may typically be mmWave radio links and/or be operated in a frequency range greater than, e.g., 6 GHz (note that while in the art the mmWave spectrum is sometimes defined to only start at 30 GHz herein, however, the term mmWave is used for a frequency range from, e.g., about 3 or 6 GHz until, e.g., about 300 GHz) . This approach allows to leave a first transmission bit stream essentially unchanged (e.g. transmitted over the shared link 110 operated at, e.g., less than 6 GHz) while modifying at least a second transmission bit stream to produce a socalled combined bit stream. This combined bit stream is then to be transmitter over another radio link (e.g. over one of the first and second directional radio links 120 1, 120 2) . The combined bit stream may be generated by combining encoded bits of the first transmission bit stream with bits of the second transmission bit stream .

[ 0039] At the receiver side a standard (legacy) receiver will still be able to decode the first transmission bit stream (encoded using an existing RAT) and a proprietary receiver will be able to fully decode the first transmission bit stream and the combined bit stream which are jointly transmitted in the (heterogeneous) radio communication network 100. Note that it is also possible to transmit the first bit stream over one of the first and second directional radio links 120 1, 120 2 and to transmit the combined bit stream over the shared radio link 110.

[ 0040 ] Embodiments described herein may use features of a so-called butterfly network known in network coding theory. Figure 2 illustrates a classical butterfly network 200 configuration. The butterfly network 200 is a network coding example that can be modeled by the directed graph of Figure 2. It includes a single message source S which has information A and B to be sent to two distinct recipients (destinations) X and Y. Information A and B may, e.g., be encoded one bit A = 0 or 1 and one bit B = 0 or 1, respectively

(this example may be generalized to bit packets A and B wherein each bit packet may include n bits, n = 1, 2, ... ) . Each recipient X and Y wants to have both information A and B. Each of the nine channels illustrated in Figure 2 can carry only a single value, e.g. one single bit (or bit packet) is transmitted in each time slot. Each channel as represented by the directed edges in Figure 2 is assumed to be error-free, and the single source S wants to send the bits A and B with the highest rate possible to the two recipients X and Y.

[ 0041 ] By simply replicating information (i.e. bits A or B) at every node T, U, V, W, the maximum multicast rate would be 1.5 bits per unit time. This is the maximum achievable rate by any "routing solution", when the intermediate node V is only capable of performing bit replication. In this case, the central channel between the intermediate node V and the node W would only be able to carry bit A (of information A) or bits B (of information B) , but not both. If information A would be transported, the recipient X would receive information A twice and not receive information B at all . Electing information B to be sent by intermediate node V would result in the same problem of receiving only one information, namely information B, for recipient Y. That is, routing is insufficient because no routing scheme can transmit both information A and B simultaneously to both recipients X and Y.

[ 0042 ] As it is apparent from Figure 2, the „network coding solution" can achieve a throughput of two bit packets per time slot since the intermediate node V no longer blocks one bit packet A or B but transmits their modulo two sum A Θ B through the shared channel between intermediate node V and intermediate node W. Modulo two sum corresponds to XOR (exclusive or) and yields 0 Θ 0 = 0, 1 Θ 0 = 1, 0 Θ 1 = 1, 1 Θ 1 = 0. That way, to provide recipient X and recipient Y both with information A and B within each time slot, all nine channels are only used once, whereas at least one channel would have been used twice without network coding, i.e. if the routing solution were applied. That is, in this configuration network coding not only offers better throughput than what can be achieved by rooting alone, but offers maximum multicast throughput which makes it optimal .

[ 0043 ] In embodiments described below, network coding, as explained in conjunction with Figure 2, will be applied to (heterogeneous) radio communication networks 100 with the potential to maximize throughput (i.e. bit rate) and to reduce latency and energy consumption. As will be described in more detail below, a proprietary receiver (e.g. implemented in a mobile station MS or a base station BS1, BS2) would be able to fully decode both information A and B while a legacy receiver (e.g. recipient X) would only be able to decode the left hand direct communication channel (node T to recipient X) and/or a legacy receiver (recipient Y) would only be able to decode the right hand direct communication channel (node U to recipient Y) . Thus, while (proprietary) receivers in accordance with embodiments described herein are able to exploit the middle path channel (node V to node W) , legacy receivers would not be able to use the combined information transmitted over this channel.

[ 0044 ] By way of example, the single source S may be implemented in a mobile station MS while the two recipients X and Y may be implemented as receivers in base stations BS1 and BS2, respectively. As will be described in greater detail further below, it is also possible to use joint reception (i.e. a single receiver) for processing the information A, B and A Θ B received by the recipients X and Y for the sake of, e.g., improved error correction, flexibility, etc.

[ 0045 ] Figure 3 illustrates an exemplary application of the classical butterfly network 200 shown in Figure 2 on the (heterogeneous) radio communication network 100 as illustrated in Figure 1. The features described above in conjunction with the classical butterfly network 200 may equally apply to the radio communication network 100, and reiteration of these features is omitted for the sake of brevity.

[ 0044 ] A single message source S, e.g. a mobile station MS, outputs information A and B (here, again, encoded by bits A and B) relating, e.g., to the same message to a first message source SI and a second message source S2. These message sources SI and S2 may be "virtual" message sources implemented in the same device as the "real" single message source S. The first message source SI then transmits the information A over the first directional radio link 120 1 and the second message source S2 transmits information B over the second directional radio link 120 2. Both message sources SI and S2 transmit information A and information B to a combiner C. The combiner C is configured to combine a first bit stream encoding information A (and thus containing bit A or bit packet A) received from message source SI and a second bit stream encoding information B (and thus containing bit B or bit packet B) received from message source S2. The combiner C outputs combined information which is transmitted over the shared radio link 110. On the other hand, the first bit stream output by message source SI is transmitted over the first directional radio link 120 1 and the second bit stream output by the second message source S2 is transmitted over the second directional radio link 120 2.

[ 0047 ] A first receiver, e.g. a base station BS1, receives the transmitted first bit stream and the transmitted combined bit stream, performs an operation OP1 on these two bit streams and is capable to decode the first bit stream carrying information A and the second bit stream carrying information B. Similarly a second recipient, e.g. a second base station BS2, receives the transmitted second bit stream and the transmitted combined bit stream performs an operation OP2 thereon and is capable to decode the first bit stream carrying information A and the second bit stream carrying information B.

[ 0048 ] It is to be noted that the characters A and B as used in Figures 2 and 3 may relate to information A and B or to bit packets A and B encoding this information A and B, respectively.

[ 0049] Figure 4 is an illustration showing an application of the general model of Figures 2 and 3 to an exemplary heterogeneous radio communication network 100 using an existing RAT providing for quasi-omnidirectional transmission and a RAT providing for highly directional mmWave transmission. Message source SI relates to SI of Figure 3 and message source S2 relates to S2 of Figure 3. The first bit stream output by message source SI may be channel encoded in channel encoder 401 using a first channel code 1 and the second bit stream output by message source S2 may be channel encoded by (optional) channel encoder 402 using a second channel code 2. Channel encoder 401 performs a channel encoding corresponding to RATI (e.g. a RAT providing for omnidirectional transmission) and channel encoder 402 performs a channel encoding according to RAT2 (e.g. a RAT providing for directional transmission) . [ 0050] The channel encoded bit streams output by the first channel encoder 401 and the second channel encoder 402 may then be input to a combiner 430 which may correspond to combiner C of Figure 3. The combiner 430 may provide for a first combined bit stream 431 and a second combined bit stream 432.

[ 0051] These two bit streams 431 and 432 may further be encoded (e.g. interleaved, punctured, etc.) in accordance with the PHY of RATI and RAT2, respectively. The optional further channel encoding performed by (optional) further channel encoder 411 is adapted to and, e.g., optimized for a RATI transmission and the (optional) further channel encoding performed by (optional) further channel encoder 412 is adapted to and, e.g., optimized for a RAT2 transmission.

[ 0052 ] Herein, the combining or network coding operation is applied after the respective e.g. two channel coding operations (of, e.g., channel encoders 401, 402) . This approach can be straightforwardly extended to any number of RATs to be combined and thus any number of channel codes to be combined. For example, this can be achieved through a hierarchy, i.e. in the first stage a combining or network coding operation is applied to first stage channel encoders (e.g. channel encoders 401, 402), another such network coding operation is applied to second stage channel encoders (e.g. channel encoders 411, 412) , etc. Then, the respective output pairs are again combined by a network coding operation in a second stage, this is possibly (if required) done for a third stage where again the output pairs of previous network coding operations are combined in a new network coding operation, etc. Also, the order of the channel encoder outputs to be combined by, e.g., a network coding operation can be chosen as required, any possibility can be envisaged. I.e., instead of combining encoder outputs 401 and 402 as well as, e.g., encoder outputs 411 and 412, one could combine the encoder outputs 401 and 412 and/or 402 and 411, or any other permutation across all stages. Also, it is possible that the outputs of the network encoding operation of a certain stage (for example the second stage) may be combined through, e.g., a network coding operation with the outputs of a previous stage (for example the first stage) or the direct outputs of the original channel encoder. Then, the outputs of the encoding stage consist of any suitable combination of the outputs of the original channel encoders and/or the outputs of the network coding operations of any of the stages.

[ 0053] Also, it is possible that the proposed combining or network coding operation (or similar operation) may not be applied at the outputs of the concerned channel encoders, but elsewhere in the communication chain, e.g. at the inputs of the channel encoders, e.g. in the MIMO/SIMO/MISO (Multiple Input Multiple Output/Single Input Multiple Output/Multiple Input Single Output) encoding stages, etc. Also, it may be applied in the Medium-Access-Control layer or in any other ISO Layer.

[ 0054 ] Figure 4 illustrates a propagation channel 110 1 and a propagation channel 110 2 of the shared radio link 110 corresponding to, e.g., RATI and, further, the first directional radio link 120 1 corresponding to a first propagation channel of RAT2 and the second directional radio link 120 2 corresponding to a second propagation channel of RAT2. By way of example, the propagation channel 110 1 may be a channel having a frequency < 6 GHz of the (quasi-) omnidirectional radio link, the propagation channel 110 2 may be a channel having a frequency < 6 GHz of the (quasi-) omnidirectional radio link, the first propagation channel may be a mmWave channel of the first directional radio link 120 1 and the second propagation channel may be a mmWave channel of the second directional radio link 120 2.

[ 0055 ] In the general model of a radio communication network 400 depicted in Figure 4, a first receiver Rl and a second receiver R2 are illustrated. The first receiver Rl receives the output of the first propagation channel 110 1 of RATI and the output of the first propagation channel 120 1 of RAT2. Given the first receiver Rl is a legacy RATI receiver, the first receiver Rl may decode the output of propagation channel 110 1 to obtain the message sent by message source SI . In case the first receiver Rl is an extended RATI receiver which is capable of decoding information received over the directional RAT2 propagation channel 120 1, the first receiver Rl will be able to decode information from message source SI and information from message source S2. The same holds analogously true for the second receiver R2, which receives the output of the second RATI propagation channel 110 2 and the output of the second RAT2 directional propagation channel 120 2.

[ 0056] Figure 5 illustrates a model of an exemplary radio communication network 500. The model may represent a restricted model of the general model of the radio communication network 400 shown in Figure 4. The restrictions may relate to self-imposed bounds to comply with a given standard, e.g., a RATI standard .

[ 0057 ] Similar to the radio communication network 400, the radio communication network 500 may comprise an message source SI and an message source S2. Message source SI and message source S2 may also be referred to as message sources SI and S2. Further, the radio communication network 500 (or, more precisely, a transmitter implemented in the radio communication network 500) comprises a first channel encoder 501 and an (optional) second channel encoder 502. The first channel encoder 501 may correspond to first channel encoder 401 and the second channel encoder 502 may correspond to second channel encoder 402 of Figure 4.

[ 0058] The radio communication network 500 (or, more precisely, a transmitter implemented in the radio communication network 500) further comprises a combiner 530. The combiner 530 may correspond to combiner 430 of radio communication network 400. The combiner 530 has a first input receiving an encoded first bit stream from first channel encoder 501 and may have a second input receiving an encoded second bit stream from channel encoder 502. Note that second channel encoder 502 may be optional. If channel encoder 502 is absent, the combiner 530 receives, at its second input, the (not channel encoded) second bit stream from the second message source.

[ 0059] The combiner 530, in this example, performs a low complexity zero-delay encoding of the input bit streams. The low complexity zero-delay encoding may use an XOR processing on the input bit streams of the combiner 530. As will be described in more detail further below, various different operations using XOR processing on the incoming bit streams may be available for low complexity zero-delay encoding in combiner 530.

[ 0060] Combiner 530 may use rateless encoding of the incoming bit streams. Rateless encoding uses a code rate of 1.

[ 0061] The combiner 530 may use Raptor encoding of the incoming bit streams. Raptor encoding means that a Raptor (rapid tornado) code is applied. Raptor codes encode a given message consisting of a number k of bits into a potentially limitless sequence of encoded bits such that knowledge of any k or more encoded bits allows the message to be recovered with some non-zero probability.

[ 0062 ] Besides the upper code examples, any other code - rateless or not - can be used instead. It is also possible to use a Convolutional Code, a Turbo Code, a Low-Density-Parity-Check Code, a Reed-Solomon Code, any Block-Code, etc., for the combining operation. Also, it is typically possible to combine one or multiple of the "original" channel codes together with the new coding operation to a new resulting code (replacing both, the original code and the new coding operation) . [ 0063 ] The encoded first bit stream output by first encoder 501 is transmitted over a first propagation channel 510. The first propagation channel 510 may correspond to first propagation channel 110 1 or 110 2 of RATI as illustrated in Figure 4. The transmitted first bit stream is directed to a first message sink 540 1 and to a second message sink 540 2. The first and second message sinks 540 1, 540 2 may be implemented by the first and second receivers Rl and R2 of Figure 4, respectively. That is, if the first message sink 540 1 is implemented by a RATI legacy receiver and if the second message sink 540 2 is implemented by another RATI legacy receiver both receivers are capable of recovering the information (message) transmitted from the first message source via the shared first propagation channel 510.

[ 0064 ] The output of the combiner 530 is transmitted over a first directive radio link 520 1 and a second directive radio link 520 2. According to one aspect, the combined bit stream transmitted over the first directive propagation channel 520 1 may be the same combined bit stream as transmitted over the second directive propagation channel 520 2.

[ 0065 ] The first message sink 540 1 receives the transmitted bit stream output from the shared propagation channel 510 and the combined bit stream output from the first directive propagation channel 520 1. If the first message sink 540 1 is implemented by an extended receiver operating on RATI and RAT2, the first message sink 540 1 is capable of decoding the message output by the first message source SI as well as the message output by the second message source S2.

[ 0066] The second message sink 540 2 receives the bit stream transmitted over the shared propagation channel 510 and the combined bit stream transmitted over the second directive propagation channel 520 2. Thus, if the second message sink 540 2 is implemented by an extended receiver operating on RATI and RAT2, the second message sink 540 2 may be capable of decoding the message output by the first message source SI and the message output by the second message source S2.

[ 0067 ] It is to be noted that the messages transmitted by the first and second message sources SI, S2 may depend from each other. By way of example, the second bit stream output by the second message source S2 may be derived from either a bit stream output from a single message source S representing the message (see Figures 2, 3) or from the first bit stream output by the first message source SI . By way of example, the bits contained in the second bit stream output by the second message source S2 may be redundant bits of the bits contained in the first bit stream output by the first message source SI. In this case, the "network coding" concept implemented in the radio communication networks 400, 500 may not provide for decoding two distinct messages in each of the receivers Rl, R2 (Figure 4) or each of the message sinks 540 1, 540 2 (Figure 5) but may be used for improving the performance of the network in view of throughput, decoding quality and, as a result, latency, if an ARQ (automatic repeat request) or Hybrid ARQ (HARQ) method - in particular a HARQ method with soft combining - is used for channel coding in the radio communication networks 400, 500, in particular in RATI . The, e.g., single message source S (not depicted in Figures 4, 5, 6, 8A, 8B, 14), from which the single bitstream (from which the first and second bit streams are derived) originates, may, e.g., a single source coder such as, e.g., a video encoder, an audio (or speech) codec, etc. This single bit stream may, e.g., already contain redundancy as it could be source coded as known in the art. The single bit stream (and/or the first and second bit streams) may be user data of these message sources. Thus, the single message source SI may also be termed single data source SI and the first and second message sources SI, S2 may also be termed data sources SI and S2, respectively. In all these cases, the combiner C combines at least some of the bits of the user data first bit stream and the user data second bit stream, e.g. each bit or each second bit or each third bit, etc... of the user data first bit stream and/or the user data second bit stream. "At least some of the bits" of a bitstream is also referred herein as "at least a portion" or "at least a subset" of a bitstream.

[ 0068 ] It is to be noted that the underlying concept of „network coding" as explained above may be considered as an alternative solution to the „brute force" approach of substantially modifying the Physical Layer (PHY) by defining an overall optimal channel code for a heterogeneous radio communication network. This approach (of defining an overall optimal channel code for a radio communication network supporting a plurality of RATs) would possibly lead to a (slightly) better system performance compared to the solution presented herein. However, a substantial change of the PHY encoding would only be compatible with a new device generation and would require the inclusion of the new PHY encoding into the related standards or system specifications. Usually, such inclusion would involve a large amount of time, expenditure and standardization work. Moreover, a substantial change in the PHY encoding scheme is hard to include in a standard and any overall optimal code would, in any case, increase the overall complexity in a transmitter and/or a receiver considerably .

[ 0069] Hence, in all it is questionable whether any „brute force" approach of substantially changing the channel encoding scheme into an optimal coding algorithm would be worth the additional complexity and effort for

standardization and for elaborating and defining such optimal coding scheme.

[ 0070 ] Quite in contrast to the brute force approach, the concept disclosed herein leaves a first transmission bit stream unchanged (e.g. the bit stream transmitted over the shared and/or the (quasi) omnidirectional radio link) . A second transmission stream is modified by combining a channel encoded bit stream of the first (original) channel encoder 501 and a second bit stream optionally channel encoded by a second (original) channel encoder 502. This modification may be achieved by no noticeable complexity increased in the transmitter, as the combiner 430, 530 may just add, e.g., an XOR operation to the transmitter functionality (the combiner 430, 530, and, in particular, an XOR operation used in the combiner 430, 530, may be implemented in hardware or in software) .

[ 0071 ] As to the receivers Rl , R2 (comprising, e.g., the message sinks 540 1, 540 2) the designer has the choice for a performance/power consumption trade-off. The designer may choose to still apply traditional decoding approaches without noticeable performance increase. Alternatively, the designer may decide to spend more power for a more complex decoding scheme (e.g. a joint trellis for joint decoding of both received bit streams) as will be described in more detail further below.

[ 0072 ] Figure 6 illustrates an embodiment of a radio communication network 600. The radio communication network 600 supports legacy receivers. The illustration of Figure 6 corresponds to the radio communication network 100 as shown in Figure 3. All functionality enclosed by the dotted line, i.e. the functionality of the combiner C, the shared radio link 110, the decoding operation 1 and the decoding operation 2 at, e.g., one or a plurality of receivers and the reconstruction of information B by the decoding operation 1 (corresponding to OP1 of Figure 3) and the reconstruction of information A by the decoding operation 2 (corresponding to OP2 of Figure 3) are not available to legacy receivers. This functionality may only be implemented in extended

(proprietary) equipment, i.e. extended transmitters and/or extended receiver (s) as disclosed herein. [ 0073 ] Figure 7 illustrates a plurality of directional radio links and a shared radio link for data uplink transmission in a radio communication network, in which a mobile station MS (transmitter) is connected to two base stations BS1, BS2 via a shared link 110 and two directional links 120 1 and 120 2. As mentioned above, the shared link 110 and the directional links 120 1, 120 2 could, e.g., be LTE and mmWave radio links, respectively, but any other suitable standard such as, e.g., Wi-Fi (III 802.1 la/b/g/ac/ad/n/af/etc . ) , Bluetooth, WiMAX, etc., could also be used with various coding schemes. The description above relating to radio communication networks 100, 400, 500 and the concept of „network coding" also apply to the uplink radio link configuration of Figure 7, and reiteration is omitted for the sake of brevity.

[ 0074 ] The configuration shown in Figure 7 resembles the one of the classical "butterfly network" of Figure 2 particular adapted to network coding. According to one embodiment, the transmitted bit streams received at the base stations BS1, BS2 may be channel-decoded at each base station BS1 and BS2. In this case, the bit stream transmitted via the shared radio link 110 and the bit stream transmitted via the first directional radio link 120 1 are channel decoded in base station BS1, and the bit stream transmitted via the shared radio link 110 and the bit stream transmitted via the second directional radio link 120 2 are channel decoded at the second base station BS2.

[ 0075 ] According to another embodiment, a central processing such as, e.g., coordinated multi-point (CoMP) processing may optionally be applied in order to combine the signals received at both base stations BS1, BS2. In this case, a joint decoding based at least on one bit stream received at the first base station BS1 and at least one bit stream received at the second base station BS2 is performed. Typically, joint decoding may be performed on at least three received bit streams or on all received bit streams depicted in Figure 7.

[ 0076] Figure 8A illustrates, by way of example, an exemplary radio communication network 800 as well as a transmitter and/or a receiver or channel decoder used therein. The transmitter, e.g., a mobile station MS transmitter provides, within the context described above, for two message sources SI, S2. Message source SI outputs the first bit stream a of bits a_± and the message source S2 outputs the second bit stream b of bits b_± . Channel encoder 801, which may correspond to channel encoder 501 of Figure 5, encodes the first bit stream a into a channel encoded first bit stream A. Optional channel encoder 802, which may correspond to channel encoder 502 of Figure 5, may channel encode the second bit stream b into the second channel encoded bit stream B.

[ 0077 ] The e.g. channel encoded second bit stream B is then modified in combiner C by applying an operation such as, e.g., an XOR operation on the second

(e.g. channel encoded) bit stream B and the first channel encoded bit stream A.

[ 0078 ] The first channel encoded bit stream A is then transmitted via a first propagation channel 810, which may correspond to the shared radio link 110 and the RATI propagation channel 510 of Figure 5, to one or both base stations BS1 and BS2. Further, the combined bit stream is transmitted via a second propagation channel 820, which may, e.g., correspond to either the first directional radio link 120 1 and the RAT2 propagation channel 520 1 of Figure 5 or to the second directional radio link 120 2 and the RAT2 propagation channel 520 2 of Figure 5 to a joint channel decoder 850. The joint channel decoder 850 may either be located in or associated with the first base station BS1 (and then jointly operates on the transmitted first bit stream received via the shared radio link 110 and on the transmitted second bit stream received over the first directional radio link 120 1) or may be located in or associated with the second base station BS2 (and then jointly operates on the transmitted first bit stream received over the shared radio link 110 and on the transmitted combined bit stream received over the second directional radio link 120 2) or may be located in or associated with a central location in order to perform a central processing including, e.g., a central channel decoding, e.g. a CoMP processing. In this case, the joint decoder 850 may jointly operate on at least two or three or all transmitted bit streams received via the shared radio link 110 (first propagation channel 810), the first directional radio link 120 1

(second propagation channel) and the second directional radio link 120 2 (not shown in Figure 8A) as depicted in Figure 7. In all cases, the joint channel decoder 850 may output a first bit stream which is a reconstruction of the first bit stream a of message source SI and may output a second bit stream b which is a reconstruction of the second bit stream b of message source S2. These bit streams a, b are directed to a single message sink 860 of a receiver, which may be located either in one of the base stations BS1 or BS2 or, in the CoMP case, at a central location.

[ 0079] Generally, as exemplified in Figure 8A, it may optionally be possible to cross switch the transmission of the encoded first bit stream and the combined bit stream so that the encoded first bit stream is first transmitted over the first propagation channel 810 and then over the second propagation channel 820 and the combined bit stream is first transmitted over the second propagation channel 820 and then over the first propagation channel 810, and vice versa. By way of example, the transmitter may optionally comprise a channel quality evaluation unit CQ configured to evaluate the channel qualities of the propagation channels 810, 820 and may optionally comprise a selector or cross switch SW configured to elect as the first propagation channel the propagation channel having the worse channel quality and to elect as the second propagation channel the propagation channel having the better channel quality.

[ 0080 ] In the following the two cases referred to above (local

channel-decoding/processing referred herein as "no CoMP"; central

channel-decoding/processing referred herein as "CoMP") are considered in detail. In the first case (i.e. no CoMP), independent channel decoders may be provided in the receivers (e.g. base stations BSl, BS2) , and in the second case where the bit streams received at the multiple receivers (e.g. base station BSl, BS2) are sent to a central location to be jointly channel decoded and processed further (i.e. CoMP), a common channel decoder may be provided to provide for overall joint decoding.

[ 0081 ] Independent Channel Decoders (no CoMP)

The classical butterfly scheme, as illustrated in Figures 2 and 3, may be particularly adapted to a lossless or error-prone scenario since it already shows important gains when both recipients want the same information A, B. That is, referring, e.g., to Figures 7 and 8A, when both base stations BSl, BS2 are requesting the same information from the mobile station MS via both a directional radio link 120 1 or 120 2 (e.g. mmWave) and a shared radio link 110 (e.g. LTE or Wi-Fi), a typical butterfly scenario is provided. By way of example, a scenario in which the mobile station MS wants to send the same information to two different base stations BSl, BS2 occurs while roaming between those two base stations BSl, BS2 during handover. In such scenario the first bit stream A and the second bit stream B may be send to the two directional links 120 l and 120 2, respectively, while the combined bit stream (using, e.g., an XOR operation A Θ B) is transmitted via the shared radio link 110. That way, the mobile station MS does not need to directly handle which base station BSl, BS2 receives what information during a handover, but simply sends the information (e.g. first bit stream A) to one base station on a directional radio link 120 1 and then suddenly switches to base station BS2 by transmitting the second bit stream B on the other directional radio link 120 2. In case the base stations BSl and BS2 do not exactly follow this procedure during the handover, they can still get the remaining information by exploiting the shared radio link 110 which transmits the combined bit stream, e.g., A Θ B. That way, robustness of the handover is increased and the error-probability during a handover is decreased by sending the information required to be sent for a handover in RATI via the directional radio links 120 1, 120 2 and using the shared radio link 110 for backup and error-correction if necessary.

[ 0082 ] Figure 8B is a block diagram illustrating a transmitter and receiver implementation configured for no CoMP operation. Briefly, the transmitter comprises message sources SI and S2 and channel encoders 801 and 802 as already shown in Figure 8A . In Figure 8B, two receivers (e.g. two base stations BS1, BS2) are provided, and each receiver comprises an individual channel decoder 850 1 and 850 2 and an individual message sink 860 1 and 860 2, respectively.

[ 0083 ] While the first channel encoded bit stream A is transmitted via the first propagation channel 810 and the combined bit stream is transmitted via the second propagation channel 820 as explained above in conjunction with Figure 8A, the third channel encoded bit stream B is transmitted via a third propagation channel 830 which may, e.g., correspond to the second directional radio link 120 2 and the RAT2 propagation channel 520 2 of Figure 5.

[ 0084 ] In this example, the channel decoders 850 1 and 850 2 may both be configured to contain two independent channel decoders, one for decoding the received bit stream A and one for decoding the received bit stream B. In legacy equipment, only one of these two channel decoders will be available (e.g. in channel decoder 850 1, only the channel decoder for the received bit stream A will operate and in channel decoder 850 2, only the decoder for received bit stream B will operate) . However, in extended receivers (e.g. proprietary equipment) , the channel decoder 850 1 is able to generate the received second bit stream B by applying, e.g., the XOR operation and then to channel decode also this bit stream to additionally obtain the reconstructed second bit stream b, and the channel decoder 850 2 is able to generate the received first bit stream A by applying, e.g., the XOR operation and then to channel decode also this bit stream to additionally obtain the reconstructed second bit stream b. In this case, the individual message sinks 860 1 and 860 2 (which may be located in different remote receivers such as, e.g., in different base stations BS1, BS2) will each receive the full information output by both message sources SI and S2. [ 0085 ] It is to be noted that each channel decoder 850_1, 850_2 may also be implemented by a single channel decoder using joint decoding based on, e.g., a joint trellis decoding scheme.

[ 0086] Figure 9 illustrates an example for error correction in a base station, e.g. base station BS2 (comprising the message sink 860 2) for the scenario mentioned above. Channel encoded transmitted bits B_±__!, B_±, B₁₊₁ are received via the second directional radio link 120 2 associated, e.g., with the third propagation channel 830 of Figure 8B. Further, the channel encoded transmitted combined bits Ai_iSBi_i , Α_±θΒ_±, Α₁₊₁θΒ₁₊₁ are received via the shared radio link 110 associated, e.g., with the second propagation channel 820 in Figure 8B. It is assumed that an error occurs on bit B_± . In this case, the base station BS2 may use the combined bit Α_±θΒ_± instead of B_± in order to obtain information on erroneous bit B_± . That is, the shared radio link 110 is used for error correction, thereby increasing the performance of radio communication network in view of throughput and latency.

[ 0087 ] Common Channel Decoder (CoMP)

The error correction process illustrated, by way of example, in Figure 9 may also be applied to the case where the information received by the two base stations BS1, BS2 is channel decoded at a single central location, i.e. the CoMP case. When the first and second transmitted bit streams A, B as received by base stations BS1 and BS2, respectively, are sent to a central location for channel decoding (as in CoMP processing), both base stations BS1, BS2 do not need to process the whole information anymore. In this case, in a lossless scenario, half of the information would even be enough. However, in a realistic and lossy scenario, this same configuration with the combined bit stream (e.g. ΑθΒ) transmitted via the shared radio link 110 can still be used for error correction. For instance, again referring to Figure 9, an error on B_± may be corrected with the knowledge of A_± and the knowledge of the combined bit (e.g. AiSBi)to obtain B_± = AiS iAj SBi ) . That is, most of the time the whole shared information (i.e. the combined bit stream) transmitted via the shared radio link 110 does not need to be channel decoded, but only when an error occurs on the transmitted bit streams A or B transmitted via, e.g., the directional radio links 120 1, 120 2, the shared information (i.e. the bits of the combined bit stream) may be exploited for error correction.

[ 0088 ] In general, referring to both scenarios described above (no CoMP and CoMP), the shared radio link 110, the first directional radio link 120 1 and the second directional radio link 120 2 need not to be of identical throughput levels (although identical throughput levels may be used as explained earlier in relation to the classical butterfly network configuration of Figures 2 and 3) . In case that, e.g., the directional radio links 120 1, 120 2 and the shared radio link are of asymmetric (i.e. different) throughput levels, the proposed combination of the encoded first bit stream A with the second bit stream b or B, e.g., using an XOR operation (or any other suitable operation) can be applied to the full or partial bit stream to be transmitted over the lower throughput radio link and to a part of the bit stream to be transmitted over the higher throughput radio link while the remaining part of the bit stream to be transmitted over the higher throughput radio link will be transmitted without modification. That way, for example, it is possible to protect a limited number of, e.g., latency-critical portions of the bit stream to be transmitted over the higher throughput radio link.

[ 0089] By way of example, the first and second directional radio links 120 1, 120 2 may provide for a higher throughput level than the shared radio link 110. In this case, if the combined bit stream is transmitted via the shared radio link 110, referring to the example of Figure 9, it would be possible to only transmit combined bit Α_±θΒ_± to protect bit B_±, while not transmitting the combined bits Ai_iSBi_i and Α₁₊₁θΒ₁₊₁.

[ 0090 ] Moreover, the first and second directional radio links 120 1, 120 2 and the shared radio link 110 do not even have to have the same capacity. That is, for example, the shared radio link 110 may have a lower capacity than each of the first and second directional radio links 120 1, 120 2. The above disclosure to different throughput levels of these radio links identically applies to radio links of different capacities, where it is also possible to still protect the most important portions of the bit stream transmitted over the higher capacity radio link by a combined bit stream transmitted over the lower capacity radio link.

[ 0091 ] Alternatively, it is also possible to combine more bits of the bit stream transmitted over the higher throughput level radio link than the number of bits that are to be transmitted over the lower throughput level radio link. This could be achieved by combining the bits of the bit stream to be transmitted over the higher throughput level radio link with repeated bits of the bit stream to be transmitted over the lower throughput level radio link. In this case, the repeated bits are preferably interleaved (i.e. the sequence order is changed following a predetermined, e.g., quasi-random interleaving scheme) in order to create, e.g., different interleaving patterns. Generally, in case of unbalanced data rates, the bit stream of the lower data rate radio link may be combined only with a part of the bit stream of the higher data rate radio link.

[ 0092 ] As mentioned above, the first and second bit streams a, b, of the two message sources SI, S2 (see Figure 8) relate, at least partly, to the same message sent from a common message source S, see Figures 2, 3. In the following, it is considered how to minimize the probability of errors while sending the message data via at least two radio links to same recipient, e.g. base station BS1 or base station BS2 or a central location in which the message data sent via the at least three radio links 100, 120 1 and 120 2 is decoded. Minimizing the probability of errors will result in that less message data has to be resent by, e.g., a data retransmission scheme such as, e.g., ARQ or HARQ, thus improving both the throughput and the latency in the radio communication network.

[ 0093 ] One simple way of deriving the two bit streams a, b from an initial bit stream representing the message to be transmitted is to simply split the information encoded by the initial bit stream in half so that the first bit stream a and the second bit stream b have an equally number of bits a_± and b_± .

[ 0094 ] For the example set out below, it may be assumed that a standard channel encoder is used both to channel encode the bit stream a and the bit stream b. Thus, referring to Figures 4, 5 and 8A, 8B, channel encoders 401, 501, 801 and channel encoders 402, 502, 802 may be exemplified by the channel encoder description below. However, it is to be noted that other types of channel encoders may be used, including any type of channel encoders using convolutional codes, block codes, turbo codes, low-density-parity-check (LDPC) codes, Reed-SOLOMON codes, etc.

[ 0095 ] Figure 10 illustrates an exemplary convolutional channel encoder 1000. Channel encoder 1000 may provide for a code rate of 1/2 meaning that for every bit a_±, two bits Al_± and A2_± are output to form the encoded bit stream A. If channel encoder 1000 is used for channel encoding the second bit stream b, analogously for every bit b_±, two bits Bl_± and Bl_± are output . These two encoded bit streams A and B (i.e. (A1,A2) and (B1,B2)) are then transmitted over two radio links and channel decoding is performed on the received bit streams to obtain an estimated or reconstructed bit stream a and an estimated or reconstructed bit stream b. Channel decoding may, for instance, be performed by using Viterbi decoding as found, e.g., in the WLAN devices that are based on the EEE 802.11 standards also known as Wi-Fi.

[ 0096] As it is apparent for a person skilled in the art, the channel encoder shown in Figure 10 is the (2,1,7) [ 133 , 171 ] ₈ convolutional channel encoder used in Wi-Fi .

[ 0097 ] According to various embodiments described herein, however, the channel encoded bit streams A and B are not transmitted as such, but a kind of, e.g., network coding is used to transmit at least a part of the encoded information by combining the channel encoded bit streams A and B and by replacing at least a part of the encoded bit streams A, B by a combined bit stream to be transmitted. For instance, instead of transmitting (A1,A2) and (B1,B2), the same radio links and bandwidths could be used to transmit (A1,A2) and, e.g., (ΒΙΘΑΙ, Β2ΘΑ2) . That is, the encoded bit stream (B1,B2) is replaced by the combined bit stream of, e.g., (ΒΙθΑΙ , Β2ΘΑ2 ) . That way, if, for example, the second radio link over which the combined bit stream is transmitted is less prone to errors, channel decoding will exploit the fact that the combined bit stream contains information about the encoded first bit stream A to correct some of the errors occurring on decoding the encoded first bit stream (A1,A2) .

[ 0098 ] In the above example, the combined bit stream was exemplified by (ΒΙΘΑΙ, Β2ΘΑ2) . However, any other combination like (A1,A2) and (Β1,Β2θΑ2) or (ΒΙ,ΒΙΘΑΙ) or (Β1,Β1θΑ2) or (Β1,Β2θΑ1) or (Β2,Β1θΑ1) or (Β2,Β1θΑ2) or (Β2,Β2θΑ1) or (B2, Β2ΘΑ2) may be used. A further possible combination of encoded bit streams A and B would, e.g., be to use (A1,A2) for the encoded first bit stream to be transmitted over the first radio link and to use, e.g., (B1,A2) for the combined bit stream to be sent over the second radio link. In this case, B2 is omitted but it can be recovered from channel decoding since B2 is redundant because of its generation by a channel encoder, e.g. channel encoder 1000 of Figure 10.

[ 0099] In the above examples the channel encoded first bit stream (A1,A2) is transmitted over the first radio link (which, e.g., might be one of the directional radio links 120 1, 120 2) while the combined bit stream is transmitted via the second radio link (which might be the shared radio link 110) . Obviously, however, the encoded bit streams A and B are interchangeable in the above scheme, i.e. „A" may be replaced by„B" (that is, Al may be replaced by Bl and A2 may be replaced by B2) , and „B" may be replaced by „A" (that is, Bl may be replaced by Al and B2 may be replaced by A2) .

[ 0100] Further, it is proposed to evaluate the channel qualities of the at least two radio links (e.g. of the shared radio link 110 and at least one of the first and second directional radio links 120 1, 120 2) and to elect as the radio link over which the encoded bit stream is transmitted (i.e. (A1,A2) or (B1,B2) the radio link having the worse channel quality and to elect as the radio link over which the combined bit stream is transmitted the radio link having the better channel quality. That is, by way of example, if the second radio link (e.g. the shared radio link 110) is better than the first radio link (e.g. one of the first or second directional radio links 120 1, 120 2), the combination of (A1,A2) transmitted over the first radio link and, e.g., (Β1,Β2θΑ2) transmitted over the second radio link leads to a better decoding result than the reverse radio link election. In this context, a „better" radio link or radio link having the better quality may mean that this radio link has a higher SNR (signal-to-noise ratio) or a higher SINR

(signal-to-interference-plus-noise ratio) or is less noisy.

[ 0101] In the case that the channel quality is better on the first radio link (e.g. on one of the directional radio links 120 1, 120 2) as compared to the second radio link (e.g. the shared radio link 110), referring to the example given above, the encoded first bit stream (A1,A2) may then be transmitted over the second radio link and, e.g., (Β1,Β2θΑ2) may then be transmitted over the first radio link. In both cases the radio link having the better quality drives the number of errors from the radio link having the worse quality down. Generally, as already exemplified in Figure 8A, it may be possible to cross switch the transmission of the encoded first bit stream and the combined bit stream so that the encoded first bit stream is first transmitted over the first radio link and then over the second radio link and the combined bit stream is first transmitted over the second radio link and then over the first radio link, and vice versa. By way of example, the transmitter may comprise a channel quality evaluation unit configured to evaluate the channel qualities of the radio links and a selector or cross switch configured to elect as the first radio link the one having the worse channel quality and to elect as the second radio link the one having the better channel quality.

[ 0102 ] As mentioned, at least a portion of the first bit stream (i.e. the first bit stream or parts of it such as, e.g., a subset of the bits of the first bit stream) are combined with at least a portion of the second bit stream (i.e. the second bit stream or parts of it such as, e.g., a subset of the bits of the second bit stream) . Some of the proposed mapping approaches of the first bit stream A n 3 ( 0 , 1 ) , n = 0 , 1 , ... and the second bit stream B n 3 ( 0 , 1 ) , n = 0,1,... are summarized in Table 1 (note that in Table 1 the notation slightly changes from A_± to A n and from B_± to B n) . As it is apparent from Table 1, this novel link mapping (or to say novel bit stream combining) distinguishes from the classical scheme of transmitting A n on one radio link and B n on another radio link. As mentioned before, A n and B n may represent the outputs of the PHY channel coding (e.g. of channel encoders 401, 501, 801 and 402, 502, 802, respectively, possibly further processed by a bit interleaver for, e.g. quasi-randomizing the order of the bits and/or a puncturing stage configured to delete some of the encoded bits in order to modify the code rate) .

Table 1

Number of Radio link 1 (e.g., directional Radio link 2 (e.g., (quasi-) proposed mmWave link sent e.g. by two omnidirectional link such as, novel antennas to different e.g., an LTE link)

mapping directions )

approach

1 A_n, n=0,l,... (B_n0A_f (n) ) , n=0 , 1 , f (n) is any suitable interleaving function modifying the order to the A n bits .

2 (A_(2n) ,A_(2n+l) ) , n=0,l,... (B (2n),B (2n+l) ΘΑ f (2n+l) ) , n=0 , 1 , f (n) is any suitable interleaving function modifying the order to the A n bits .

3 (A_(2n) ,A_(2n+l) ) , n=0,l,... (B_(2n) ,A_f (2n) ) , n=0 , 1 , f (n) is any suitable interleaving function modifying the order to the A n bits .

4 (A_(2n) ,A_(2n+l) ) , n=0,l,... (B_(2n) ,B_(2n)8A_f (2n) ) ,

n=0 , 1 , f (n) is any suitable interleaving function modifying the order to the A n bits .

5 (A_(2n) ,A_(2n+l) ) , n=0,l,... (B (2n+l),B (2n+l) ΘΑ f (2n+l) ) , n=0 , 1 , f (n) is any suitable interleaving function modifying the order to the A n bits .

6 (A_(2n) ,A_(2n+l) ) , n=0,l,... (B (2n+l) ,B (2n) ΘΑ f (2n) ) , n=0 , 1 , f (n) is any suitable interleaving function modifying the order to the A n bits .

(B ηθΑ n) , n=0, 1, ... A n, n=0, 1, ...

(B (2n),B (2η+1)θΑ f (2n+l) ) , (A_(2n) ,A_(2n+l) ) , n=0,l,-. n= 0,l,...,f(n) is any suitable

interleaving function modifying

the order to the A n bits .

(B_(2n) ,A_f (2n) ) , n=0 , 1 , f (n) (A_(2n) ,A_(2n+l) ) , n=0,l,-. is any suitable interleaving

function modifying the order to

the A n bits .

(B_(2n) ,B_(2n)8A_f (2n) ) , (A_(2n) ,A_(2n+l) ) , n=0, 1 , ... n=0 , 1 , f (n) is any suitable

interleaving function modifying

the order to the A n bits .

(B (2n+l),B (2n+l) ΘΑ f (2n+l) ) (A_(2n) ,A_(2n+l) ) , n=0,l,-. , n=0 , 1 , f (n) is any suitable

interleaving function modifying

the order to the A n bits .

(B (2n+l) ,B (2η)θΑ f (2n) ) , (A_(2n) ,A_(2n+l) ) , n=0,l,-. n=0 , 1 , f (n) is any suitable

interleaving function modifying

the order to the A n bits .

(A_(2n) ,A_(2n+l) ) , n=0,l,-. (B_(n) ,A_f (n) ) , n=0 , 1 , f (n) is any suitable interleaving function modifying the order to the A n bits .

(A_(2n) ,A_(2n+l) ) , n=0,l,-. (B_(n) ,B_(n)®A_f (n) ) ,

function modifying the order to

the A n bits .

(B_(n) ,B_(n)®A_f (n) ) , (A_(2n) ,A_(2n+l) ) , n=0,l,-. n=0 , 1 , f (n) is any suitable

interleaving function modifying

the order to the A n bits . [ 0103] To summarize, an approach is disclosed herein to channel encode data transmitted over two separate radio links using, e.g., network coding techniques and to decode them, e.g. to decode them jointly, which can reduce the number of errors without adding any data overhead compared to a scenario where the data transmitted over the two separate radio links would be decoded independently. This approach may be used to minimize the amount of errors when the channel decoder has only access to two of the radio links while concurrently being able to recover the entire received information from any two radio links. This way, not only errors could be ignored from any radio link (as each radio link could be regarded as redundant) , but it is also possible to only use two radio links available at, e.g., a single base station to have the whole information with typically less errors than in the classical case. Further, it is to be noted from the bit stream mapping examples of Table 1 that either the XOR coding operation can be applied to the entire channel encoded first bit stream or only to a part of the channel encoded first bit stream. Similarly, the XOR coding operation can be applied to the entire (e.g. channel encoded) second bit stream or only to a part of the (e.g. channel encoded) second bit stream .

[ 0104 ] So, if the message output by the single source S is not intended to be transmitted to a central location for channel decoding but should be decoded at each base station BS1 or BS2 (i.e. the recovered source bit streams a and b are needed to be recovered at each single base station BS1 or BS2) , the hybrid configuration as described above should be the most adapted one. That is, by way of example, the encoded first bit stream (A1,A2) may be transmitted over the weaker shared radio link 110 (e.g. Wi-Fi, LTE, etc.) and first and second combined bit streams, e.g. (Β1,Β2θΑ2) and (Β1θΑ1,Β2) may be transmitted over the better directional radio links 120 1 and 120 2, respectively. Note that the directional radio links 120 1 and 120 2 are typically the radio links having the higher throughput than the shared radio link 110 1. This hybrid butterfly scenario is illustrated, by way of example, in Figure 11. Note that Figure 11 is a specific example of the general scenario illustrated in Figure 7.

[ 0105] According to a further possibility, the radio link having the higher throughput (e.g. one or both of the directional radio links 120 1, 120 2) could also be used to transmit a bit stream which is partly or entirely channel non-encoded, and delay-critical sections would be protected, e.g., by the lower throughput shared radio link (e.g. the shared radio link 110 such as, e.g. Wi-Fi, LTE, etc. ) .

[ 0106] According to still another possibility, even a transmission without any network coding may be possible, such as: (i) transmitting the encoded first bit stream (A1,A2) over the first radio link and transmitting the (non-encoded) second bit stream (b n,b n) over the second radio link, wherein b n corresponds to the inputs of the second channel encoder 402, 502, 802 (note that in this case the second radio link does not use channel coding nor network coding) ; or

(ii) transmitting the encoded first bit stream (A1,A2) over the first radio link and transmitting the (non-encoded) first bit stream (a n,b n) over the second radio link, where a n and b n correspond to the inputs of the respective first and second channel encoders 401, 501, 801 and 402, 502, 802 (note that in this case the second radio link does not use channel coding nor network coding) .

[ 0107 ] Similarly, the above transmission schemes without network coding could also be applied to the first radio link and several different combinations among those can then be applied on both radio links (that is, "A" can be replaced by "B" and "B" can be replaced by "A" in the upper transmission schemes.

[ 0108] Various receiver architectures are possible for operating in a radio communication network as described herein. The receiver architecture can be chosen depending on, e.g., what information has been transmitted, what information is wanted and on the quality of the radio links over which the information is transmitted. Always, at least two bit streams, i.e. at least a first bit stream and a second bit stream are received by one base station BS1 or by two or more base stations BS1, BS2, ... etc.

[ 0109] In all cases a receiver configured to operate in a radio communication network as described herein may comprise a channel decoder equipment. The receiver may comprise a first receiver branch configured to receive a first bit stream, wherein the received first bit stream is a reconstruction of the channel encoded first bit stream transmitted over the first radio link of the radio communication network. The receiver may further comprise a second receiver branch configured to receive a combined bit stream, wherein the received combined bit stream is a reconstruction of the combined bit stream transmitted over the second radio link of the radio communication network, wherein the transmitted combined bit stream is a combination of the channel encoded first bit stream with a the second bit stream, wherein the first bit stream and the second bit stream represent a message.

[ 0110] Further, the receiver may comprise a channel decoder configured for channel decoding the received first bit stream and the received combined bit stream. According to a first possibility, the received first bit stream and the received combined bit stream are channel decoded at each base station, i.e. the full information of the message is intended to be recovered at each base station (local processing, i.e. no CoMP) . In this case an individual channel decoder for decoding the received first bit stream and the received combined bit stream is implemented at each base station BS1, BS2, as already explained above. This individual channel decoder may perform joint trellis channel decoding of the received first bit stream and the received combined bit stream.

[0111] This case of base station located channel decoding (i.e. "local processing") is illustrated in the middle part of Figure 12. Generally, each base station BS1, BS2 comprises an RF stage 1201, 1202 configured for receiving, down-converting and digitizing the signals received over the at least two radio links to produce the first received bit stream 1211 and 1212, respectively, and the received combined bit stream 1221 and 1222, respectively. The two received bit streams 1211, 1221 are jointly channel decoded by a first channel decoder 1231 located at the first base station BS1 and the two received bit streams 1212, 1222 are jointly channel decoded by a second channel decoder 1232 located at the second base station BS2.

[0112] If the received bit streams 1211, 1221 and 1212, 1222 are ought to be channel decoded in a single location („central processing" or CoMP) , several possibilities for a receiver and channel decoder architecture are feasible. By way of example, as illustrated in the top part of Figure 12, a common receiver 1240 may be provided at a single location and, e.g., CoMP may be used . The common receiver 1240 may, e.g., be provided with a first and a second network coding determination stage 1241 and 1242, a first and a second buffer 1243 and 1244, a first and a second decoder 1245 and 1246, and a joint channel decoder 1247.

[0113] The network coding determination stages 1241, 1242 determine whether or not the received first bit stream 1211 or 1212, respectively, and the received second bit stream 1221 or 1222, respectively, are network coded. If the second received bit stream 1221 or 1222 is a received combined bit stream, as explained above, the respective network coding determination stage 1241 or 1242 determines network coding. In this case, the received combined bit stream 1221 or 1222 may be stored in the respective buffer 1243 or 1244, and the first received bit stream 1211 or 1212 may be channel decoded in the respective channel decoder 1245 or 1246. Only in case of an error occurring during decoding of the received first bit stream 1211 or 1212, the received combined bit stream 1221 or 1222 - or the respective parts thereof where the error occurred - are used for error correction. In this case, the common channel decoder 1247 may be used to channel decode the needed parts of the received combined bit streams 1221, 1222 in order to correct for the errors of the received first bit stream 1211 or 1212, respectively. [ 0114 ] According to another receiver architecture, the common receiver 1240, as illustrated above, is not located at a single location but is duplicated at each base station BS1, BS2. Thus, it is also possible to apply the above-described scheme of using a buffer 1243, 1244 for temporary storing redundant information (e.g. parity bits) from the received combined bit stream for local processing at each base station BS1, BS2. In this case, the first base station BS1 includes the network coding determination stage 1241, the buffer 1243, the channel decoder 1245 and the channel decoder 1247 for joint channel decoding in case of an error occurring in channel decoder 1245 (note that channel decoder 1247 then is no longer a common channel decoder but an individual, local channel decoder) . The second base station BS2 may then include the network coding determination stage 1242, the buffer 1244, the channel decoder 1246 and a replica of the channel decoder 1247 configured to operate in case of an error occurring in channel decoder 1246.

[ 0115] In other words, the top part of Figure 12 illustrates a receiver architecture suitable for central processing, e.g., CoMP but can also be interpreted (by replacing the common channel decoder 1247 by two local channel decoders 1247) to illustrate and a receiver architecture suitable for local processing, e.g. non-CoMP.

[ 0116] The bottom part of Figure 12 illustrates still another possibility for implementing a receiver 1260. In this case, the receiver 1260 is provided in a single location which is not associated with either of the first and second base stations BS1 or BS2. The receiver 1260 may comprise a joint channel decoder 1261. The joint channel decoder 1261 may operate on the received first bit stream 1211 and the received combined bit stream 1221 of the first base station BS1 and on the received first bit stream 1212 and the received combined bit stream 1222 of the second base station BS2. The channel decoder 1261 may, e.g., perform joint decoding with the at least two best radio links. That is, channel decoding may be performed on data received via the shared link and at least one of the directional radio links 120 1 or 120 2. For legacy transmitters and/or receivers the joint channel decoder 1261 may, e.g., channel decode the bit streams received over the first and second directional radio links 120 1, 120 2, if these bit streams were channel encoded according to the standard channel encoding scheme (e.g. of RATI) .

[ 0117 ] It is to be noted that the joint channel decoding approach, as illustrated in the bottom part of Figure 12, allows to completely disregard all but two received bit streams to decode the full information jointly (or, alternatively, to use a third or more of the received bit streams to drive the amount of errors further down) .

[ 0118] Figure 13 is an illustration of a radio communication network indicating the approach of network coding for a mobile station-to-mobile station connection. Figure 13 illustrates an exemplary radio communication network 1300. A network coding solution in a UE-to-UE configuration is considered. More specifically, a first mobile station UEl transmits an encoded first bit stream on the uplink via a first directional radio link 120 1. On the other hand, UE2 transmits a first encoded bit sequence on the uplink via a second directional radio link 120 2. The base station BS (eNodeB) receives the respective encoded first bit stream and transmits, on the downlink, a combined bit stream via the shared radio link 110 (e.g. LTE, Wi-Fi, etc.) . Then, each mobile station UEl, UE2 can decode the message sent from the other UE by jointly decoding the first bit stream received from the other UE a with the data of the combined bit stream broadcasted by the other UE over the shared radio link. The first and second directional radio links 120 1, 120 2 can thus be used for next transmissions while the shared radio link 110 (e.g. LTE, Wi-Fi, etc.) is broadcasting the combined bit stream, e.g. the XOR data as illustrated in Figure 13.

[ 0119] Simulations for performance evaluation were performed to verify the feasibility of the use of network coding in a multi-radio link scenario as described herein. Figure 14 illustrates an exemplary implementation of two convolutional channel encoders 1401, 1402 configured to channel encode the first bit sequence a output of the first message source SI and the second bit sequence b output by the second message source S2. Here, by way of example, the first and second bit streams a and b are simply derived by splitting the information of the message (i.e. the bit stream output by the single message source S) in half so that one ends up with the equally numerous bits a_± and bits bi of the first bit stream a and the second bit stream b, respectively. Note that the channel encoders 1401, 1402 are exemplary, specific implementations of channel encoders 401, 402; 501, 502; 801, 802 as described herein .

[ 0120] Each channel encoder 1401, 1402, has, e.g., a constraint length of 7 and is the channel encoder found WLAN products that are based on IEEE 802.11 standards, here used with a rate R = k/n = 1/2. To improve error protection, a (7, [133,171]₈) convolutional code (i.e. a constraint length of 7 with generator polynomials 133₈ and 171₈) , which e.g. maximize the minimum distance between codewords, has been chosen. [133,171] in octal numbers corresponds to [1011011,1111001] in binary numbers, as can be observed in Figure 14 showing the convolutional encoders 1401, 1402.

[ 0121] The exemplary combiner as illustrated in Figure 14 uses the network coding scheme number 2 in Table 1. That is, if applied to the block diagram of Figure 8B, (A (2n),A (2n+l)), n=0,l,... is transmitted over the first radio link 810 and (B_ (2n) , B_ (2n+l ) ΘΑ_ (2n+l ) ) , n=0,l,..., is transmitted over the second radio link 820. Note that the network coding scheme number 2 is one representative of the group of network coding schemes in which at most (or, e.g., exactly) each second bit of the combined bit stream is generated by using XOR processing on the channel encoded first bit stream and the second bit stream, while the residual bits of the combined bit stream are not generated by using a XOR operation. As mentioned before, these residual bits may, e.g., be uncombined encoded bits Bl_± or B2_± or, e.g., even be uncombined uncoded bits b_±.

[ 0122 ] The decoding of the bit streams received over both radio links 810, 820 has been performed with a joint trellis in which both links are decoded simultaneously. For this purpose, the number of memory elements of both encoders 1401, 1402 were assumed to be added and for each trellis transition two input information bits were assumed. The decoding is performed by a (2,1,7) Viterbi decoder .

[ 0123] Figure 15 illustrates the bit error rate (BER) versus Eb/No of the second radio link 820 (over which the combined bit stream is transmitted) . The BER is obtained in the simulations based on the specific channel encoder 1401, 1402 and combiner C implementation of Figure 14. The simulations were performed on an AWGN (Additive White Gaussian Noise) channel using BPSK (Binary Pulse Shift Keying) modulation and Eb/No = ldB of the first radio link 810.

[ 0124 ] As apparent from Figure 15, the BER of averaged uncoded radio link 1 (refers here to radio link 810) and uncoded radio link 2 (refers here to radio link 830) as well as the BER of averaged convolutional encoded radio link 1 (refers here to radio link 810) and convolutional encoded radio link 2 (refers here to radio link 830) is significantly worse than the BER of convolutional encoded radio link 1 (refers here to radio link 810) and network encoded radio link 2 (refers here to radio link 820) . More specifically, the simulations show that the channel decoding is as good as if the weaker radio link had the same capacity as the better radio link. This could arguably not be better than this, which is the best possible achievable performance with good convolutional encoded radio links. EXAMPLES

[ 0125] The following examples pertain further includeto further embodiments .

[ 0126] Example 1 is a method of processing a message to be transmitted in a radio communication network, the method comprising channel encoding a first bit stream representing a message; combining at least a portion of the channel encoded first bit stream with at least a portion of a second bit stream it to generate a combined bit stream, wherein the second bit stream representing at least partly the message; wherein the channel encoded first bit stream is configured to be transmitted over a first radio link of the radio communication network and the combined bit stream is configured to be transmitted over a second radio link of the radio communication network.

[ 0127 ] In Example 2, the subject matter of Example 1 can optionally include wherein the radio communication network is a heterogeneous wireless network including a first radio access technology and a second radio access technology, and wherein the first radio link is a radio link of the first radio access technology and the second radio link is a radio link of the second radio access technology .

[ 0128] In Example 3, the subject matter of any of Examples 1-2 can optionally include wherein one of the first radio link and the second radio link is a quasi-omnidirectional radio link and the other radio link is a directional radio link.

[ 0129] In Example 4, the subject matter of any of Examples 1-3 can optionally include evaluating the channel qualities of two radio links; and electing as the first radio link the one having the worse channel quality and electing as the second radio link the one having the better channel quality.

[ 0130] In Example 5, the subject matter of any of Examples 1-4 can optionally include cross switching the transmission of the encoded first bit stream and the combined bit stream so that the encoded first bit stream is configured to be transmitted over the second radio link and the combined bit stream is configured to be transmitted over the first radio link.

[ 0131] In Example 6, the subject matter of any of Examples 1-5 can optionally include wherein the second bit stream is channel encoded. [ 0132 ] In Example 7, the subject matter of any of Examples 1-6 can optionally include wherein combining uses XOR processing on the at least portion of the channel encoded first bit stream and the at least portion of the second bit stream .

[ 0133] In Example 8, the subject matter of Example 7 can optionally include wherein at most each second bit of the combined bit stream is generated by using XOR processing on the channel encoded first bit stream and the second bit stream.

[ 0134 ] In Example 9, the subject matter of any of Examples 1-8 can optionally include wherein combining uses rateless coding of the channel encoded first bit stream and the second bit stream.

[ 0135] In Example 10, the subject matter of any of Examples 1-9 can optionally include wherein combining uses Raptor coding of the channel encoded first bit stream and the second bit stream.

[ 0136] In Example 11, the subject matter of any of Examples 1-10 can optionally include wherein the first bit stream and the second bit stream are derived from a single bit stream representing the message.

[ 0137 ] In Example 12, the subject matter of Example 11 can optionally include wherein the bits contained in the second bit stream are redundant bits of the bits contained in the first bit stream.

[ 0138] Example 13 is a method of encoding data in a radio communication network, the method comprising channel encoding a first bit stream representing a message; modifying a second bit stream representing at least partly the message by combining bits thereof with bits of the channel encoded first bit stream; wherein the channel encoded first bit stream is configured to be transmitted over a first radio link of the radio communication network and the combined bit stream is configured to be transmitted over a second radio link of the radio communication network.

[ 0139] In Example 14, the subject matter of Example 13 can optionally include wherein the radio communication network is a heterogeneous wireless network including a first radio access technology and a second radio access technology, and wherein the first radio link is a radio link of the first radio access technology and the second radio link is a radio link of the second radio access technology . [ 0140] Example 15 is a method of channel decoding in a radio communication network, wherein the method comprises receiving a first bit stream, wherein the received first bit stream is a reconstruction of a channel encoded first bit stream transmitted over a first radio link of the radio communication network; receiving a combined bit stream, wherein the received combined bit stream is a reconstruction of a combined bit stream transmitted over a second radio link of the radio communication network, wherein the transmitted combined bit stream is a combination of at least a portion of the channel encoded first bit stream with at least a portion of a second bit stream, wherein the first bit stream and the second bit stream represent a message; and channel decoding the received first bit stream and the received combined bit stream.

[ 0141] In Example 16, the subject matter of Example 15 can optionally include wherein a joint trellis channel decoding of the received first bit stream and the received combined bit stream is performed.

[ 0142 ] In Example 17, the subject matter of Examples 15-16 can optionally include buffering the received combined bit stream; and using the buffered combined bit stream for channel decoding only in case of a decoding error occurring in channel decoding of the received first bit stream.

[ 0143] In Example 18, the subject matter of Examples 15-17 can optionally include wherein at least one of the received first bit stream and the received combined bit stream is transmitted over a shared radio link and is received both at a first base station and at a second base station, the other of the received first bit stream and the received combined bit stream is transmitted over a first directional radio link and is received only at the first base station; and channel decoding is performed in a central location on the basis of the bit streams received over the shared radio link and the bit stream received over the first directional radio link.

[ 0144 ] In Example 19, the subject matter of Example 18 can optionally include wherein a third bit stream is transmitted over a second directional radio link and is received only at the second base station; and channel decoding in the central location is performed further on the basis of the bit streams received over second directional radio link.

[ 0145] Example 20 is a transmitter of a radio communication network comprising a first channel encoder configured to channel encode a first bit stream representing a message; a combiner configured to combine at least a portion of the channel encoded first bit stream with at least a portion of a second bit stream, the second bit stream representing at least partly the message, the combiner generating a combined bit stream; a first transmitter branch transmitting the channel encoded first bit stream over a first radio link of the radio communication network; and a second transmitter branch transmitting the combined bit stream over a second radio link of the radio communication network.

[ 0146] In Example 21, the subject matter of Example 20 can optionally include wherein the radio communication network is a heterogeneous wireless network including a first radio access technology and a second radio access technology, and wherein the first radio link is a radio link of the first radio access technology and the second radio link is a radio link of the second radio access technology .

[ 0147 ] In Example 22, the subject matter of Examples 20-21 can optionally include wherein one of the first radio link and the second radio link is a quasi-omnidirectional radio link and the other radio link is a directional radio link.

[ 0148] In Example 23, the subject matter of Examples 20-22 can optionally further include a channel quality evaluation unit configured to evaluate the channel qualities of two radio links; and a selector configured to elect as the first radio link the one having the worse channel quality and electing as the second radio link the one having the better quality.

[ 0149] In Example 24, the subject matter of Examples 20-23 can optionally include wherein the selector is configured to cross switch the transmission of the encoded first bit stream and the combined bit stream so that the encoded first bit stream is transmitted over the second radio link and the combined bit stream is transmitted over the first radio link.

[ 0150] In Example 25, the subject matter of Examples 20-24 can optionally further comprise a second channel encoder configured to channel encode the second bit stream.

[ 0151] In Example 26, the subject matter of Examples 20-25 can optionally include wherein the combiner comprises an XOR stage included in the combiner, the XOR stage is configured to process the at least portion of the channel encoded first bit stream and the at least portion of the second bit stream.

[ 0152 ] Example 27 is a channel encoder equipment for operation in a radio communication network, comprising a first channel encoder configured to channel encode a first bit stream representing a message; a combiner configured to modify a second bit stream representing at least partly the message by combining bits of the second bit stream with bits of the channel encoded first bit stream; wherein the channel encoded first bit stream is configured to be transmitted over a first radio link of the radio communication network and the combined bit stream is configured to be transmitted over a second radio link of the radio communication network.

[ 0153] In Example 28, the subject matter of Example 27 can optionally include wherein the radio communication network is a heterogeneous wireless network including a first radio access technology and a second radio access technology, and wherein the first radio link is a radio link of the first radio access technology and the second radio link is a radio link of the second radio access technology .

[ 0154 ] In Example 29, the subject matter of Example 27 can optionally include wherein the combiner comprises an XOR stage configured to process at least a portion of the channel encoded first bit stream and at least a portion of the second bit stream.

[ 0155] Example 30 is a channel decoder equipment for operation in a radio communication network, comprising a first receiver branch configured to receive a first bit stream, wherein the received first bit stream is a reconstruction of a channel encoded first bit stream transmitted over a first radio link of the radio communication network; a second receiver branch configured to receive a combined bit stream, wherein the received combined bit stream is a reconstruction of a combined bit stream transmitted over a second radio link of the radio communication network, wherein the transmitted combined bit stream is a combination of at least a portion of the channel encoded first bit stream with at least a portion of a second bit stream, wherein the first bit stream and the second bit stream represent a message; and a channel decoder configured for channel decoding the received first bit stream and the received combined bit stream. [ 0156] In Example 31, the subject matter of Example 30 can optionally include wherein the channel decoder is configured to perform joint trellis channel decoding of the received first bit stream and the received combined bit stream.

[ 0157 ] In Example 32, the subject matter of Examples 30-31 can optionally further include a buffer configured to buffer the received combined bit stream; wherein the channel decoder is configured to use the buffered combined bit stream for channel decoding in case of a decoding error occurring in channel decoding of the received first bit stream.

[ 0158] In Example 33, the subject matter of Examples 30-32 can optionally include wherein at least one of the received first bit stream and the received combined bit stream is transmitted over a shared radio link and is received both at a first base station and at a second base station, the other of the received first bit stream and the received combined bit stream is transmitted over a first directional radio link and is received only at the first base station; and wherein the channel decoder is located in a central location and configured to perform channel decoding on the basis of the bit streams received over the shared radio link and the bit stream received over the first directional radio link.

[ 0159] In Example 34, the subject matter of Example 33 can optionally include wherein a third bit stream is transmitted over a second directional radio link and is received only at the second base station; and wherein channel decoding in the central location is performed further on the basis of the bit streams received over the second directional radio link.

[ 0160] Although specific embodiments and examples have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations may be substituted for the specific embodiments shown and described without departing from the scope of the present invention. This application is intended to cover any adaptations or variations of embodiments and examples described herein. Therefore, it is intended that this invention is limited only by the claims and the equivalents thereof.

Claims

1. A method of processing a message to be transmitted in a radio communication network, the method comprising:

channel encoding a first bit stream representing a message;

combining at least a portion of the channel encoded first bit stream with at least a portion of a second bit stream to generate a combined bit stream, the second bit stream representing at least partly the message; wherein the channel encoded first bit stream is configured to be transmitted over a first radio link of the radio communication network and the combined bit stream is configured to be transmitted over a second radio link of the radio communication network.

2. The method of claim 1, wherein the radio communication network is a heterogeneous wireless network including a first radio access technology and a second radio access technology, and wherein the first radio link is a radio link of the first radio access technology and the second radio link is a radio link of the second radio access technology.

3. The method of claim 1 or 2, wherein one of the first radio link and the second radio link is a quasi-omnidirectional radio link and the other radio link is a directional radio link.

4. The method of claim 1 or 2, further comprising:

evaluating the channel qualities of two radio links; and electing as the first radio link the one having the worse channel quality and electing as the second radio link the one having the better channel quality .

5. The method of claim 1 or 2, further comprising:

cross switching the transmission of the encoded first bit stream and the combined bit stream so that the encoded first bit stream is configured to be transmitted over the second radio link and the combined bit stream is configured to be transmitted over the first radio link.

6. The method of claim 1 or 2, wherein the second bit stream is channel encoded .

7. The method of claim 1 or 2, wherein combining uses XOR processing on the at least portion of the channel encoded first bit stream and the at least a portion of the second bit stream.

8. The method of claim 7, wherein at most each second bit of the combined bit stream is generated by using XOR processing on the channel encoded first bit stream and the second bit stream.

9. The method of claim 1 or 2, wherein the first bit stream and the second bit stream are derived from a single bit stream representing the message.

10. The method of claim 9, wherein the bits contained in the second bit stream are redundant bits of the bits contained in the first bit stream.

11. A method of encoding data in a radio communication network, the method comprising :

channel encoding a first bit stream representing a message;

modifying a second bit stream representing at least partly the message by combining bits thereof with bits of the channel encoded first bit stream; wherein

the channel encoded first bit stream is configured to be transmitted over a first radio link of the radio communication network and the combined bit stream is configured to be transmitted over a second radio link of the radio communication network.

12. The method of claim 11, wherein the radio communication network is a heterogeneous wireless network including a first radio access technology and a second radio access technology, and wherein the first radio link is a radio link of the of the first radio access technology and the second radio link is a radio link of the second radio access technology.

13. A method of channel decoding in a radio communication network, wherein the method comprises:

receiving a first bit stream, wherein the received first bit stream is a reconstruction of a channel encoded first bit stream transmitted over a first radio link of the radio communication network;

receiving a combined bit stream, wherein the received combined bit stream is a reconstruction of a combined bit stream transmitted over a second radio link of the radio communication network, wherein the transmitted combined bit stream is a combination of at least a portion of the channel encoded first bit stream with at least a portion of a second bit stream, wherein the first bit stream and the second bit stream represent a message; and

channel decoding the received first bit stream and the received combined bit stream.

14. The method of claim 13, wherein a joint trellis channel decoding of the received first bit stream and the received combined bit stream is performed.

15. The method of claim 13 or 14, further comprising:

buffering the received combined bit stream; and

using the buffered combined bit stream for channel decoding in case of a decoding error occurring in channel decoding of the received first bit stream .

16. The method of one of claim 13 or 14, wherein

at least one of the received first bit stream and the received combined bit stream is transmitted over a shared radio link and is received both at a first base station and at a second base station;

the other of the received first bit stream and the received combined bit stream is transmitted over a first directional radio link and is received only at the first base station; and

channel decoding is performed in a central location on the basis of the bit streams received over the shared radio link and the bit stream received over the first directional radio link.

17. The method of claim 16, wherein

a third bit stream is transmitted over a second directional radio link and is received at the second base station; and

channel decoding in the central location is performed further on the basis of the bit streams received over second directional radio link.

18. A transmitter of a radio communication network, comprising:

a first channel encoder configured to channel encode a first bit stream representing a message;

a combiner configured to combine at least a portion of the channel encoded first bit stream with at least a portion of a second bit stream, the second bit stream representing at least partly the message, the combiner generating a combined bit stream;

a first transmitter branch transmitting the channel encoded first bit stream over a first radio link of the radio communication network; and a second transmitter branch transmitting the combined bit stream over a second radio link of the radio communication network.

19. The transmitter of claim 18, further comprising:

a channel quality evaluation unit configured to evaluate the channel qualities of two radio links; and

a selector configured to elect as the first radio link the one having the worse channel quality and electing as the second radio link the one having the better quality.

20. The transmitter of one of claim 18 or 19, wherein the combiner comprises :

an XOR stage included in the combiner, the XOR stage is configured to process the at least portion of the channel encoded first bit stream and the at least portion of the second bit stream.

21. A channel encoder equipment for operation in a radio communication network, comprising:

a combiner configured to modify a second bit stream representing at least partly the message by combining bits of the second bit stream with bits of the channel encoded first bit stream; wherein

22. The channel encoder equipment of claim 21, wherein the combiner comprises an XOR stage configured to process at least a portion of the channel encoded first bit stream and at least a portion of the second bit stream.

23. A channel decoder equipment for operation in a radio communication network, comprising:

a first receiver branch configured to receive a first bit stream, wherein the received first bit stream is a reconstruction of a channel encoded first bit stream transmitted over a first radio link of the radio communication network;

a second receiver branch configured to receive a combined bit stream, wherein the received combined bit stream is a reconstruction of a combined bit stream transmitted over a second radio link of the radio communication network, wherein the transmitted combined bit stream is a combination of at least a portion of the channel encoded first bit stream with at least a portion of a second bit stream, wherein the first bit stream and the second bit stream represent a message; and

a channel decoder configured for channel decoding the received first bit stream and the received combined bit stream.

24. The channel decoder equipment of claim 23, wherein the channel decoder is configured to perform joint trellis channel decoding of the received first bit stream and the received combined bit stream.

25. The channel decoder equipment of claim 23 or 24, further comprising:

a buffer configured to buffer the received combined bit stream; wherein

the channel decoder is configured to use the buffered combined bit stream for channel decoding in case of a decoding error occurring in channel decoding of the received first bit stream.