Communication device and method

Abstract

The present disclosure presents an efficient backhaul operation that minimizes the data rate requirements of the backhaul. Backhaul information is transmitted from a master AP to one or more slave APs for joint transmission from the one or more slave APs to a STA in coordination with the transmission from the master AP to the STA.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to communication devices and methods, in particular, for use in a multi-access point (multi-AP) communication system. BACKGROUND

[0002] Up to now, in a wireless local area network (WLAN), an access point (AP) transmits one or more physical layer protocol data units (PPDUs) to one or more stations (STAs). Therefore, only one AP should be transmitting at a point in time. Transmissions of other APs or STAs interfere with the transmission, which is therefore not desirable. The next generation of wireless local area networks considers multiple APs (MAP) to simultaneously perform joint transmission (JTX) of PPDUs. The advantage is that coverage and / or reception quality can be improved.

[0003] The background description provided herein is for the purpose of generally presenting the context of the disclosure. The work of the presently named inventors, to the extent the work is described in this background section, as well as aspects of the description that can not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure. SUMMARY

[0004] It is an object of the present invention to provide a communication device and method that enable an efficient multi-AP operation. It is a further object to provide a corresponding computer program and a non-transitory computer-readable recording medium for implementing the method.

[0005] According to one aspect, a first communication device is provided, comprising:

[0006] a MAC layer circuit configured to:

[0007] generate MAC output data units by performing medium access control (MAC) layer processing on MAC input data units to be transmitted to a second communication device, and

[0008] generate control information for one or more selected MAC output data units, the control information indicating that the one or more selected MAC output data units are to be processed by a third communication device at a physical (PHY) layer and that the one or more selected MAC output data units are to be transmitted from the third communication device and from the first communication device to the second communication device; and

[0009] - PHY layer circuitry configured to generate PHY output data units by performing PHY layer processing on the MAC output data units, wherein the selected PHY output data units are generated from the selected MAC output data units for transmission from the first communication device to the second communication device in coordination with transmission of the selected PHY output data units generated from the selected MAC output data units by the third communication device,

[0010] wherein the first communication device is configured to provide the one or more selected MAC output data units and associated control information to the third communication device.

[0011] According to another aspect, there is provided a third communication device comprising:

[0012] - MAC layer circuitry configured to obtain one or more selected medium access control (MAC) output data units and associated control information from a first communication device, the control information indicating that the one or more selected MAC output data units are to be processed by the third communication device at a physical (PHY) layer and that the one or more selected MAC output data units are to be transmitted from the third communication device and from the first communication device to a second communication device; and

[0013] - PHY layer circuitry configured to generate selected PHY output data units by performing PHY layer processing on the selected MAC output data units for transmission from the third communication device to the second communication device in coordination with transmission of the selected PHY output data units generated from the selected MAC output data units by the first communication device.

[0014] According to yet another aspect of the respective methods, there is provided a computer program comprising program means for causing a computer to carry out the steps of the methods disclosed herein when the computer program is executed on a computer, and a non-transitory computer-readable recording medium storing the computer program product which, when executed by a processor, causes the execution of the methods disclosed herein.

[0015] Embodiments are defined in the dependent claims. It should be understood that the disclosed communication devices and methods, the disclosed computer program and the disclosed computer-readable recording medium have similar and / or identical embodiments as the claimed first communication device and as defined in the dependent claims and / or as disclosed herein.

[0016] One aspect of the present disclosure is that in a multi-AP communication setup, the access points (often referred to as AP STAs or simply APs) need to be aware of the data to be transmitted to the stations (often referred to as non-AP STAs or simply STAs; also referred to herein as "second communication devices"). Therefore, a backhaul link is provided to convey the necessary information to the APs participating in the joint transmission before the actual joint transmission takes place. According to the present disclosure, an efficient backhaul operation is proposed which minimizes the data rate requirement of the backhaul. Specifically, the concept of conveying backhaul information from a master AP (also referred to herein as "first communication device") to one or more slave APs (also referred to herein as "third communication devices") is disclosed in one embodiment. Furthermore, two concepts of transmit signal construction at the master AP providing the information and at the slave APs receiving the information are disclosed in embodiments of the present disclosure. The proposed solution outperforms known concepts in terms of required backhaul data rate and provides seamless integration into IEEE 802.11 compliant communication systems.

[0017] The above paragraph is provided as a general overview of the disclosure and is not intended to limit the scope of the claims that follow. The described embodiments, together with further advantages, will be best understood from the following detailed description taken in connection with the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0018] A more complete understanding of the present disclosure and the many attendant advantages thereof will be readily understood by referring to the following detailed description when considered in connection with the accompanying drawings, wherein:

[0019] Figure 1 A schematic diagram illustrating a conventional communication system is shown.

[0020] Figure 2 A schematic diagram illustrating another conventional communication system is shown.

[0021] Figure 3 A general layout of a communication device operating as an AP and a communication device operating as a STA is shown.

[0022] Figure 4 A schematic diagram illustrating an embodiment of a PHY unit of an AP is shown.

[0023] Figure 5 A diagram illustrating MAC operations for transmission and reception is shown.

[0024] Figure 6 A diagram illustrating the relationship between MSDU, A-MSDU, MPDU, A-MPDU, PSDU and PPDU is shown.

[0025] Figure 7 A schematic diagram illustrating a first communication device according to the present disclosure to illustrate its operation as a master AP is shown.

[0026] Figure 8 Flow chart showing the operation of the MAC unit of the master AP.

[0027] Figure 9 Diagram illustrating MAP-MSDU.

[0028] Figure 10 Schematic diagram showing a first embodiment of the third communication device to illustrate its operation as a slave AP.

[0029] Figure 11 Schematic diagram showing a second embodiment of the third communication device to illustrate its operation as a slave AP.

[0030] Figure 12 Flow chart showing the operation of the MAC unit of the slave AP.

[0031] Figure 13 Diagram illustrating the time operation of the master and slave APs.

[0032] Figure 14 Schematic diagram showing the master and slave APs to illustrate the order of their operation steps and the information flow for the wireless backhaul case.

[0033] Figure 15 Schematic diagram showing the master and slave APs to illustrate the order of their operation steps and the information flow for the DS / wired backhaul case.

[0034] Figure 16 Schematic diagram showing an embodiment of the PHY unit of an AP (master or slave) in non-MAP mode.

[0035] Figure 17 Schematic diagram showing a first embodiment of the PHY unit of the master AP 100 in MAP mode.

[0036] Figure 18 Schematic diagram showing a first embodiment of the PHY unit of the slave AP in MAP mode.

[0037] Figure 19 Schematic diagram showing a second embodiment of the PHY unit of the master AP 100 in MAP mode.

[0038] Figure 20 Schematic diagram showing a second embodiment of the PHY unit of the slave AP in MAP mode.

[0039] Figure 21 Diagram illustrating the main concepts of a known communication scheme.

[0040] Figure 22 Diagram illustrating the main concepts of a communication scheme according to the present disclosure. DETAILED DESCRIPTION

[0041] Up to now, in any wireless LAN, an access point (AP) transmits one or more PPDU (physical layer protocol data unit) to one or more stations (STA). Thus, only one AP is transmitting at a point in time. Transmissions of other APs or STAs interfere with this transmission and are thus unwanted.

[0042] In contrast, the next generation of wireless local area networks considers multiple APs (MAP) to simultaneously jointly transmit (JTX) a PPDU. The advantage is to improve coverage and / or reception quality. The disadvantage is that synchronization is needed between the APs and the advanced channel sounding.

[0043] Another important aspect of a MAP is that information needs to be shared between the APs that simultaneously transmit in the MAP setup. The exchange of this information is one of the goals of the present disclosure.

[0044] In the following, a brief overview of the system model will be given. Figure 1 A system using MAP data transmission from two APs to one STA is shown, i.e. the setup is similar to a downlink scenario. Each AP as well as each STA can have multiple transmit or receive antennas, respectively. The channel transfer function from AP1 to STA1 is H1, while H2 is the channel transfer function from AP2 to STA1. Note that both H1 and H2 are matrices, in the most general case a function of the carrier or tone index, i.e. the channel can be modeled by a set of matrices. Moreover, both matrices can vary over time, but this is not considered here as it is assumed that the channel matrices are known to the respective APs with good accuracy.

[0045] The received signal r at STA1 (for a specific carrier or tone) is where t1 and t2 denote the actual transmit signals of the respective APs. Each AP can perform precoding with a matrix Q1 or Q2, respectively. Thus, the received signal r is

[0046] r = [H1Q1 H2Q2] · s

[0047] where, is the overall precoding matrix and s is the baseband transmit signal before precoding. In the above model, the transmit signal, the received signal, the channel matrix and the precoding matrix are carrier-based. An OFDM system is assumed, where each OFDM symbol conveys information to be transmitted on one or more subcarriers or tones. The transmit signal can consist of one or more OFDM symbols.

[0048] In the most general case, the dimension of the vector s is N ss x 1, where N ssdenotes the number of spatial streams in JTX. Q has dimension N TX,i x N ss where N TX,i denotes the number of transmit chains or transmit antennas of AP i. H i has dimension N RX x N TX,i where N RX denotes the number of receive antennas of STA 1. The model presented here assumes a single receiver; however, it can easily be extended to a multi-user (MU) scenario. In the MU context, MAP serves multiple STAs simultaneously.

[0049] In the following, it is assumed that data traffic enters at a single AP, as Figure 2 illustrated, Figure 2 a communication system with a master AP (AP1; here also generally referred to as a first communication device) serving a station (STA1; generally a second communication device) and a slave AP (AP2; here also generally referred to as a third communication device; possibly also other slave APs) is shown. Thus, the (user) data to be transmitted to the STA enters only one AP (the master AP). All other APs participating in the JTX are referred to as slave APs. As will be explained in more detail below, backhaul information is transmitted from the master AP to one or more slave APs for jointly transmitting from the one or more slave APs to the STA in coordination with the transmission from the master AP to the STA.

[0050] A distributed system (DS) can be an external entity, e.g. a router, a server, a network, etc., which is a connection to higher layers, providing the source of ingress traffic and the sink of egress traffic from the perspective of the slave APs. The goal of the DS is to deliver MAC service data units (MSDUs) to the intended destination. The DS can contain wired and / or even further wireless links. It should be noted that the master AP and the slave APs also provide egress traffic to the DS, but this is not primarily discussed in the present disclosure.

[0051] As can be seen from the above equations, the master AP (e.g. AP1) can generate s based on the ingress traffic, but AP2 cannot generate s because this AP2 does not know the data to be transmitted to STA1. It is the purpose of the present disclosure to provide for transferring the necessary information from the master AP to one or more slave APs so that the one or more slave APs can generate s.

[0052] According to embodiments, two ways of providing one or more selected MAC output data units and associated control information to the slave AP are provided, i.e. via wireless backhaul or via DS backhaul, i.e. the slave AP is connected to the master AP via a (e.g. wired) link or via wireless backhaul (i.e. the slave AP is wirelessly connected to the master AP). The wireless connection can use the same frequency band as the continuous JTX or a different frequency band. Furthermore, embodiments are presented how to initiate or trigger the JTX after the necessary information has been transferred to the slave AP. Generally, embodiments of the presented solution are very efficient in terms of the required bit rate of the backhaul, as they only provide the MAC layer information to the slave AP, but not the complete PHY layer information.

[0053] Before turning to the details of the MAP, the overall operation of the WLAN shall be briefly described by referring to the overall layout of the communication device 10 operating as an AP and the communication device 20 operating as a STA. The communication device 10 comprises a MAC (Medium Access Control) unit 11 (also referred to as MAC layer unit or MAC layer circuit or simply MAC layer) and a physical (PHY) unit 12 (also referred to as PHY layer unit or PHY layer circuit or simply PHY layer). The communication device 20 also comprises a MAC unit 21 and a PHY unit 22. For example, all these units can be implemented by respective circuits, processors or computers.

[0054] Generally, the MAC unit 11 processes any incoming MSDU (also referred to as MAC input data unit here) in several steps. The main steps can be as follows. First, the MAC unit 11 buffers the incoming MSDU in one or more queues according to its priority. Once the wireless channel is idle for a while, the MAC unit 11 starts processing one or more MSDUs: the MAC unit 11 encrypts the user data (i.e. one or more MSDUs), prepends a MAC header (hdr) and appends a frame check sequence (FCS). This forms an MPDU (also referred to as MAC output data unit here). The MAC header contains control information for the MAC unit of the peer STA 20 (e.g. frame type, duration, source and destination (MAC) addresses and sequence number). The FCS is used by the MAC unit 21 of the peer STA 20 to detect whether the MSDU or the MAC header has been received with errors (and potentially requests a retransmission).

[0055] In a next step, one MPDU or multiple MPDUs are aggregated into an A-MPDU, which forms a physical layer service data unit (PSDU; also referred to as PHY input data unit here). The MAC unit 11 forwards the PSDU to the PHY unit 12, which encodes, modulates and transmits the MAC message (MPDU or A-MPDU), i.e. the PSDU. In order to enable the PHY unit 22 of the peer STA 20 to demodulate the received PHY output data unit, the PHY unit 12 prepares a PHY preamble reserving a PHY configuration and a channel estimation sequence in advance. The finally obtained PHY output data unit (PPDU) is transmitted to the STA 20.

[0056] The PHY unit 22 of the STA 20 receives the PPDU and performs the inverse PHY layer processing, followed by the inverse MAC layer processing by the MAC unit 21, to obtain the MSDU, i.e. the original data provided to the AP for transmission to the STA.

[0057] The PHY unit 12 can combine MPDUs with different destination / receiver addresses in a (multi-user) MU-PPDU. In this case, orthogonal PHY layer resources like OFDMA or MU-MIMO perform the separation of the PSDUs with different destination / receiver addresses.

[0058] Figure 4 A schematic diagram showing an embodiment of the PHY unit 11 of the AP 10. It comprises a scrambling unit 110, a forward error correction (FEC) encoder 111, a stream parser 112, N ss The spatial stream processing unit 113 comprises an interleaver 1131, a constellation mapper 1132 and a cyclic shift delay (CSD) unit 1133 (except for the first stream), a spatial mapper 114 and a NTXtransmit chain 115 (each comprising an inverse discrete Fourier transform (IDFT) unit 1151, an insertion unit 1152 for inserting a guard interval (GI) and a window, and an analog and RF processing unit 1153). It should be noted that the PHY unit 22 of the STA 20 can typically be configured in the same way. ss The spatial stream processing unit 113 comprises an interleaver 1131, a constellation mapper 1132 and a cyclic shift delay (CSD) unit 1133 (except for the first stream), a spatial mapper 114 and a NTXtransmit chain 115 (each comprising an inverse discrete Fourier transform (IDFT) unit 1151, an insertion unit 1152 for inserting a guard interval (GI) and a window, and an analog and RF processing unit 1153). It should be noted that the PHY unit 22 of the STA 20 can typically be configured in the same way.

[0059] Figure 5 A diagram illustrating MAC operations for transmission and reception is shown. Figure 6 A diagram illustrating the relationship between MSDU, A-MSDU, MPDU, A-MPDU, PSDU and PPDU is shown. Further details of these relationships as well as the overall configuration and operation of the MAC and PHY circuitry can be found, for example, in the IEEE 802.11 standard.

[0060] According to the present disclosure, the processing of MSDUs is different for the MAP for both the master AP and the slave AP, which will be explained in detail below.

[0061] Figure 7 A schematic diagram of a first communication device 100 according to the present disclosure is shown to illustrate its operation as a master AP. The master AP 100 comprises a MAC unit 101 and a PHY unit 102. Once the master AP 100 receives an MSDU, it checks whether this MSDU is MAP eligible, i.e. whether it can be transmitted by the master AP and the slave AP in coordination, i.e. in a joint transmission (JTX), to a specific station. Thus, a MAP eligible MSDU (also referred to as selected MSDU) is the MSDU which is part of a PPDU transmitted by the slave AP in a JTX. This check (or selection) can be done, for example, by evaluating the destination and / or receiver address and / or user priority provided with the MSDU. The classification of the MSDU as MAP or non-MAP eligible can be done by an optional (internal or external) control unit 103 (e.g. station management entity, SME) or by any other entity of the master AP. The classification can be done before or after the MAC processing of the MSDU. If the MSDU is not MAP eligible, the regular MAC and PHY processing is performed.

[0062] It should be noted that in an embodiment, at an earlier stage, the master AP can determine that a joint transmission should be used (e.g. for transmission to one or more or all STAs) and that a MAP mode should be entered (e.g. because the joint transmission is beneficial for improving the data rate or reliability). If the master AP is in this MAP mode, the eligibility check as described above can thus comprise or represent the step of selecting the MSU to be used in the JTX. In another embodiment, the eligibility check step and the selection step can be separate steps performed subsequently.

[0063] If the MSDU is MAP eligible, the MAC unit 101 can perform Figure 8 the following steps shown in the flowchart shown.

[0064] First, a MAC output data unit is generated by performing MAC layer processing on a MAC input data unit to be transmitted to a STA. Specifically, in a first step S101, the MAC unit 100 (this is indicated by block 104 in Figure 7 periodically processes MSDUs (MAC input data units), i.e. the MAC unit 100 performs steps such as encryption, MAC header and FCS addition and aggregation of A-MPDUs. The output is a MPDU or A-MPDU (MAC output data unit). This MAC processing can be performed for MSDUs eligible for MAP, although the channel is busy.

[0065] The master AP 100 stores (step S102) in the memory 105 the MAC output data units (also referred to as "selected MAC output data units") that are to be selected for later transmission in a joint transmission (these are later PSDUs or at least parts thereof).

[0066] Subsequently, control information is generated for the one or more selected MAC output data units. The control information indicates that the one or more selected MAC output data units are to be processed at the PHY layer by the slave AP and that the one or more selected MAC output data units are to be transmitted from the slave AP and the master AP to the STA.

[0067] In particular, in step S103, the MAC unit 101 interprets the selected MAC output data units (i.e. MPDUs or A-MPDUs) as new MSDUs (referred to as MAP-MSDUs in the following), but sets the source and destination addresses differently: the new source address is the master AP address (i.e. the address of the master AP 100) and the new destination address is the slave AP address (i.e. the addresses 200 and 300 of the slave APs; see Figure 10 and Figure 11 ).

[0068] Furthermore, in step S104, the MAC unit 101 adds further control information to the MAP-MSDU, e.g. a unique identifier. This can be another header, a MAP header or a MAP (control) frame, for example. Details will be explained in more detail below. In Steps 103 and 104 are performed in block 106 in Figure 7 . The MAP information ("control information") can be provided by a control unit (e.g. the SME 103). In another embodiment, S103 and S104 can be combined, i.e. the addresses can be set in the control information.

[0069] Subsequently, the one or more selected MAC output data units and the associated control information are provided to the slave AP. In embodiments using a wireless backhaul, the MAC unit 101 processes the MAP-MSDUs periodically as soon as the channel is free, but takes into account source-destination (e.g. master AP - slave AP) specific parameters, e.g. MAC (e.g. encryption) and PHY (e.g. coding, modulation) parameters, and triggers the PHY unit 102 to process them to generate selected PHY output data units for transmission, as provided in step S105. Since the source and destination addresses have been changed, the selected PHY output data units (i.e. the corresponding MSDUs) are transmitted to the slave AP (third communication device) instead of the intended STA (second communication device).

[0070] In another embodiment for providing one or more selected MAC output data units and associated control information to the slave APs using DS or wired backhaul, as provided in step S106, the MAC unit 101 provides the MAP-MSDU to the higher layer (DS) together with destination address (DA), source address (SA) and length information. Thus, the DA is set to the slave APs and the SA is set to the master AP. The purpose of the DS is to transfer this information (i.e. the selected MAC output data units and control information) to the slave APs.

[0071] The master AP 100 can wait for an acknowledgement (ACK) indicating that one or more MAP-MSDU has been successfully received (step S107) and can even retransmit the MAP-MSDU if needed.

[0072] Once the master AP has transferred all MAP-MSDU to all slave APs required for the JTX, acknowledgements can have been received, the master AP 100 can decide to initiate the JTX in step S108. Thus, the master AP 100 sends an announcement information (announcement frame) to all slave APs, which announcement information comprises at least a unique identifier of the MAP-MSDU to be jointly transmitted in the following. In addition, PHY layer configuration data can be added and a spatial mapping matrix Q can be indicated (details will be explained below).

[0073] Then, in step S109, the master AP 100 sends the PPDU with the PSDU saved in step 102 after a predetermined time after the announcement information (frame) sent in step S107 has been sent, or after a trigger sent by the master AP 100 to the slave APs. This is illustrated in Figure 7 by the JTX trigger which can be provided by a control unit (e.g. SME 103). It is to be noted that this announcement and JTX can be transmitted separately or the information can be combined into a combined trigger.

[0074] It is to be noted that there can be MSDUs which are to be transmitted by the master AP in the JTX and which do not comply with the MAP. These MSDUs can be stored in a memory of the master AP until the JTX is initiated. Conceptually, these can be stored in the memory 105 or in a memory which is anyhow comprised in the MAC unit 101, e.g. in a transmission queue.

[0075] Figure 9 A diagram illustrating a MAP-MSDU is shown, which comprises a MAP header (MAP hdr) and a data part comprising MPDUs or A-MPDUs.

[0076] Figure 10 and Figure 11A schematic diagram showing different embodiments of the third communication device 200 and 210, each having a MAC unit 201 and a PHY unit 202, to illustrate its operation as a slave AP in a JTX according to the present disclosure. Once the slave AP receives a MAP-MSDU via a received PPDU for wireless backhaul Figure 10 ) or via a higher layer interface for wired backhaul Figure 11 ) it performs the following steps shown in the flowchart. Figure 12

[0077] First, the slave AP obtains one or more selected MAC output data units and associated control information from the master AP. Specifically, in a first step S201 the MAC unit 201 extracts the MPDUs or A-MPDUs and the identifiers present in the MAP-MSDU (indicated by block 204). In case of wireless backhaul, this can contain multiple steps: the PPDUs holding the MAP-MSDU are demodulated, decoded, analyzed, defragmented and decrypted, just like a regular PPDU. In step S202 an acknowledgement can be sent depending on the settings in the received PPDU.

[0078] In step S203 additional control information (indicated by block 206) reserved in the MAP-MSDU is extracted and in step S204 the MPDUs or A-MPDUs are stored in memory 205 together with the identifiers. In step S203 the source address can be set to the master AP 100 and the destination address can be set to the station receiving the data in the JTX.

[0079] Subsequently, the slave AP generates selected PHY output data units by performing PHY layer processing on the selected MAC output data units for transmission from the slave AP to the STA in coordination with the transmission of the selected PHY output data units generated by the master AP from the selected MAC output data units. Specifically, once the slave AP 200 / 210 receives the announcement information (frame) it configures its PHY unit 202 and spatial mapping matrix as instructed in the announcement and forwards the PSDU content, i.e. one or more MPDUs or A-MPDUs to the PHY unit 202 (step S205). The PHY unit 202 sends a PPDU with the PSDU after a predefined time after the announcement information (frame) or after a trigger received from the master AP (step S206), in Figure 10 and Figure 11 are shown by the JTX trigger triggering the memory 205.

[0080] Figure 13 A diagram showing the temporal operation of the master AP 200 and the slave AP 200 / 210 illustrating the dependencies between the master AP and the slave AP. ​

[0081] Figure 14 A schematic diagram showing the master AP 100 (as Figure 7 indicated) and the slave AP 200 (as Figure 10 indicated) is shown for the wireless backhaul case, showing the order of their operation steps and the information flow through the master AP 100 and the slave AP 200, indicated by the circle numbers from 1 to 11.

[0082] As Figure 14 indicated, after the backhaul operation, the same MAC output data units remain in the memory of the master AP and the slave AP (assuming only MSDUs are transmitted from both APs; otherwise, the memory content is a subset of each other). The dashed lines show the transmit and receive PHY MAC operations. Both cancel each other out (if there are no transmission errors; since this is a regular link, all functionalities can be applied, like acknowledgements, retransmissions, etc.). This is a regular wireless link. The PHY configuration of this link is different from the PHY configuration in the JTX. For the JTX, both APs transmit the MAC output data units as PHY output data units through the PHY layer processing at the same time.

[0083] Figure 15 A schematic diagram showing the master AP 100 (as Figure 7 indicated) and the slave AP 210 (as Figure 11 indicated) is shown for the DS / wired backhaul case, showing the order of their operation steps and the information flow through the master AP 100 and the slave AP 210, indicated by the circle numbers from 1 to 7.

[0084] As Figure 15 indicated, after the backhaul operation, the same MAC output data units remain in the memory of the master AP and the slave AP. For the JTX, both APs transmit these MAC output data units as PHY output data units through the PHY layer processing at the same time.

[0085] In some embodiments, the slave AP can actually comprise an AP and a STA. The STA is collocated with the AP and both exchange data internally (e.g., via a station management entity, SME). This is to always enable data exchange between the AP and the STA, since there is no AP-to-AP communication defined for WLAN devices. In this regard, the master AP transmits the wireless backhaul information to the STA collocated with the slave AP. This STA is configuring the slave AP via the internal data exchange as described above.

[0086] The MAP-MSDU contains the MPDUs or A-MPDUs to be transmitted by the slave AP during the JTX. In addition, it holds control information. The control information can be kept in frames aggregated to the MPDUs or A-MPDUs or in frames that can be added in the form of a MAP header.

[0087] The control information can contain at least an identifier of the MAP-MSDU. This identifier is needed by the master AP to indicate to the slave AP in the JTX which MPDU or A-MPDU in the MAP-MSDU it should transmit. The slave AP can transmit multiple MPDUs or A-MPDUs of a MAP-MSDU in the JTX. Thus, the set of identifiers can arrange the order of the MPDUs or A-MPDUs of the MAP-MSDU to be transmitted.

[0088] To make the JTX successful, the master AP can provide more control information to the slave AP. This information can be kept in the above mentioned control information, or in an announcement frame, or in a trigger before the JTX. This information can include one or more of the following:

[0089] - the configuration of the PHY layer of the slave AP;

[0090] - the (optional related to the slave AP) spatial mapping matrix (i.e. at least Q2 in the example above);

[0091] - the spatial stream index or index that the slave AP will serve.

[0092] The announcement or trigger frame can include one or more identifiers of the MPDUs or A-MPDUs within a MAP-MSDU that will be transmitted by the slave AP in the upcoming JTX.

[0093] There are multiple options for the PHY operation. They differ in the tasks each AP needs to perform in the JTX. It is assumed that each AP has two transmit antennas and four transmit antennas are used in the joint transmission of the two APs.

[0094] First, in Figure 16 a schematic diagram of an embodiment of the PHY unit 102 of the AP 100 (here denoted 102a) in non-MAP mode, i.e. regular mode without JTX, but with all MSDUs transmitted from the master AP to the STA is shown. It should be noted that the PHY units of the slave APs 200 and 210 are correspondingly configured in non-MAP mode.

[0095] Figure 17 a schematic diagram of a first embodiment of the PHY unit 102 of the AP 100 (here denoted 102b) in MAP mode is shown. Figure 18 a schematic diagram of a first embodiment of the PHY unit 202 of the AP 200 (here denoted 202b) in MAP mode is shown. In an alternative embodiment, Figure 17 the shown embodiment can be used in the slave AP 200 and Figure 18 the shown embodiment can be used in the master AP 100.

[0096] Figure 17 and Figure 18 The first embodiment shown uses the most general approach. It is more complex, but provides the most MAP gain. Each PHY unit 102b, 202b performs scrambling, FEC encoding, stream parsing, interleaving (optionally), constellation mapping, and CSD on all N ss space streams in the MAP. These operations are performed simultaneously in each AP. After the CSD operation, each PHY unit 102b, 202b multiplies with its Q matrix, which maps the N ss space streams to N TX,i transmission streams. N TX,i corresponds to the number of active transmit chains or transmit antennas used. After that, each PHY unit 102b, 202b performs an IDFT operation, insertion of GI, windowing, and analog and RF processing on its own N TX,i active transmit chains. If N ss >N TX,i , then the processing capability required of the PHY unit before spatial mapping is greater than the processing capability required of the PHY unit after spatial mapping.

[0097] Figure 19 A schematic diagram showing a second embodiment of a PHY unit 102 (here denoted 102c) of the AP 100 in MAP mode. Figure 20 A schematic diagram showing a second embodiment of a PHY unit 212 (here denoted 212c) of the AP 210 in MAP mode. In alternative embodiments, Figure 19 the embodiment shown can be used in the slave AP 210, and Figure 20 the embodiment shown can be used in the master AP 100.

[0098] Figure 19 and Figure 20 The second embodiment shown uses a less general approach. It is less complex, but provides a smaller MAP gain. Each PHY unit 102c, 212c performs scrambling, FEC encoding, and stream parsing. These operations are performed simultaneously in each AP. After the stream parser operation, each PHY unit 102c, 212c performs interleaving (optionally), constellation mapping, CSD (optionally), spatial mapping using its Q i matrix, an IDFT operation, insertion of GI, windowing, and analog and RF processing for its own N TX,i active transmit chains. If N ss >N TX,i , then the processing capability required of the PHY unit is significantly reduced compared to the first embodiment.

[0099] Q i The matrix has a different size compared to the first embodiment. In the first embodiment, Q i has a size of N TX,i x N ss while in the second embodiment, the size is N TX,i x N TX,i . When N ss > N TX,i , for the first embodiment, the overall Q is while for the second embodiment, Q is Thus, the second embodiment assumes the presence of zero terms on the anti-diagonal in the overall Q matrix.

[0100] For the first embodiment, the stream parser operates as usual. It allocates consecutive bits to the first spatial stream in a circular fashion. Next, it further allocates subsequent consecutive bits to the second spatial stream, and so on. When bits are allocated to the last spatial stream, it continues with the first spatial stream. However, for the second embodiment, only the relevant output of the stream parser is further processed, and the non-relevant spatial streams of a particular AP are not further considered. This means that the AP discards some of the output of the stream parser.

[0101] In principle, the first and second embodiment can be combined, for example, in the sense that the master AP operates according to the first embodiment while the slave AP operates according to the second embodiment.

[0102] All PHY components in all APs preferably use the same settings. These settings can be shared by the master AP with the slave APs and include all or a subset of the TXVECTOR parameters. The TXVECTOR parameters are configuring the PHY for transmission. A compression scheme for the TXVECTOR can be applicable. One approach includes sending the PHY header for JTX as they contain all relevant TXVECTOR information for the receiver to process the incoming PPDU.

[0103] For the preamble and for the second embodiment, the AP should know what spatial streams it should serve in the JTX. This is indicated by the spatial stream index number. For the example in Figure 19 and Figure 20 , the master AP transmits spatial streams 1 and 2 while the slave AP serves spatial streams 3 and 4.

[0104] The master AP can compute the overall spatial mapping matrix Q or each AP can compute its own spatial mapping matrix. In the first case, at least the part of the Q matrix that is relevant to the slave APs is signaled, while in the second case, the Q matrix does not need to be signaled.

[0105] Embodiments of the present disclosure have been explained in detail. In the following, a short summary of the basic aspects of the present disclosure will be provided.

[0106] The present disclosure seeks to provide enhancements in reliability, latency, and throughput of wireless communication, which are recently required for applications such as UHD video transmission including AR / VR. Multiple APs (multi-AP) are assumed to jointly transmit to one or more STAs simultaneously (also referred to as network MIMO). The transmitted signal of each AP in the joint transmission originates from (at least partially) the same data. The multiple APs are classified into one master AP and one or more slave APs. The STAs are (at least) logically associated with the master AP.

[0107] Since the PHY waveform is an analog signal and has PHY redundancy, the backhaul transmission efficiency of the PHY waveform is very low. Therefore, the required backhaul bit rate requirement is very high, which is undesirable as it limits the throughput and applicability of multi-AP. The goal is to minimize the rate requirement of the backhaul. Therefore, the proposed solution can be seen as backhaul compression. Furthermore, very simple compression and decompression of the backhaul data should be enabled for the master and slave APs, respectively.

[0108] Figure 21 The main concept of the known communication scheme is illustrated in Fig. 1. The master AP generates a PPDU (waveform) for the slave APs and sends the digitized PPDU waveform to the slave APs via the backhaul (step 1). The slave APs transmit the received waveform upon receiving a trigger for the joint transmission (step 3) (step 2). Thus, the backhaul conveys the PPDU waveform.

[0109] Figure 22 The main concept of the communication scheme according to the present disclosure is illustrated in Fig. 2. The master AP sends (step 1) the MDPU or A-MPDU together with the PHY configuration (Config) that should be applied for the JTX. The slave APs process the received MPDU or A-MPDU in their PHY layer according to the received PHY configuration and generate a PPDU waveform, which they transmit upon receiving a trigger for the JTX (step 3) (step 2).

[0110] In more detail, and as Figures 7 to 12As shown, according to the present disclosure, the master AP generates the A-MPDU stored in memory for later joint transmission, and adds the M-AP information (e.g. PHY configuration, identifier). The A-MPDU and M-AP information form a MAP-MSDU, which can reach the DS or be interpreted as a regular MSDU for wireless transmission. After the JTX trigger, the master AP PHY processes the A-MPDU in memory and sends a PPDU. In one embodiment, the slave AP (DS) receives the MAP-MSDU from the DS and extracts the M-AP information. The A-MPDU is then stored in memory for later joint transmission. When the JTX trigger is received, the slave AP PHY processes the A-MPDU according to the PHY configuration in the M-AP information, and sends a PPDU. In another embodiment, the slave AP (wireless) receives the PPDU containing the MAP-MSDU from the master AP. The MAP-MSDU is extracted from the backhaul PPDU. The following processing is the same as in the first embodiment. It is noted that the PHY configuration of the backhaul and JTX PPDU are different.

[0111] Thus, to summarize the present disclosure, the backhaul consists of data units (MPDU / A-MPDU or PSDU) to be transmitted by the slave AP plus configuration data. In known systems, the master AP generates the transmit signal for the slave AP, and the backhaul carries the PPDU of the slave AP. According to the present disclosure, the backhaul consists of data units (MPDU / A-MPDU or PSDU) to be transmitted by the slave AP plus configuration data.

[0112] Implementing the backhaul at the MPDU / A-MPDU level is much more efficient than performing it at the PPDU level, which requires quantization of the I and Q components of each sample, and produces redundancy due to channel coding. Assuming 8-bit quantization of each I and Q component, and a channel code rate of 1 / 2, the overhead in terms of backhaul bitrate requirement is reduced by a factor of (8*2*2 = 32).

[0113] The proposed backhaul scheme can further be seamlessly integrated into regular 802.11 links, so that all MAC features such as BAck or Ack can be used.

[0114] Thus, the foregoing merely illustrates exemplary embodiments of the present disclosure. As will be appreciated by those skilled in the art, the present disclosure can be embodied in other specific forms without departing from the spirit or essential characteristics thereof. Accordingly, the disclosure is intended to be illustrative, but not limiting of the scope of the disclosure or other claims. The disclosure, including any readily

[0115] In the claims, the term "comprising" does not exclude other elements or steps, the term "a" or "an" does not exclude a plurality, and the term "one" or "said one" do not exclude a plurality. A single unit can fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0116] To the extent embodiments of the disclosure have been described as being implemented by data processing apparatus that is at least partially controlled by software, it is understood that non-transitory machine readable media (for example, optical, magnetic or semiconductor memories) carrying such software are also considered to represent embodiments of the disclosure. Further, such software can also be distributed over networks or other telecommunication systems in other forms, such as via the Internet or other wired or wireless telecommunications systems.

[0117] Elements of the disclosed devices, apparatuses, and systems can be implemented by corresponding hardware and / or software elements, such as application specific circuits. A circuit is a structural combination of electronic components, including conventional circuit elements, integrated circuits comprising custom integrated circuits, standard integrated circuits, application specific standard products, and field programmable gate arrays. Further, a circuit includes central processing units, graphics processing units, and microprocessors, which are programmed or configured according to software code. A circuit does not include pure software, although a circuit includes hardware executing software as described above.

[0118] The following is a list of further embodiments of the disclosed subject matter:

[0119] 1. A first communication device, comprising:

[0120] - MAC layer circuitry configured to:

[0121] - generate MAC output data units by performing medium access control (MAC) layer processing on MAC input data units to be transmitted to a second communication device, and

[0122] - generate control information for one or more selected MAC output data units, the control information indicating that the one or more selected MAC output data units are to be subjected to physical (PHY) layer processing by a third communication device and that the one or more selected MAC output data units are to be transmitted from the third communication device and from the first communication device to the second communication device; and

[0123] - PHY layer circuitry configured to generate PHY output data units by performing PHY layer processing on the MAC output data units, wherein selected PHY output data units are generated from selected MAC output data units for transmission from the first communication device to the second communication device in coordination with transmission of selected PHY output data units generated by the third communication device from the selected MAC output data units,

[0124] The first communication device is configured to provide one or more selected MAC output data units and associated control information to the third communication device.

[0125] 2. The first communication device as defined in any of the foregoing embodiments,

[0126] The MAC layer circuit is configured to select one or more MAC input data units based on one or more of the following: the destination address of the MAC input data unit, the location of the second communication unit, the channel state information between the first and second communication devices, the channel state information between the third and second communication devices, and the priority of the MAC input data unit, in order to generate the selected MAC output data unit.

[0127] 3. The first communication device as defined in any of the foregoing embodiments,

[0128] The control information includes: source address information, indicating that the first communication device is the source of the selected MAC output data unit; and destination address information, indicating that the third communication device is the destination of the selected MAC output data unit.

[0129] 4. The first communication device as defined in any of the foregoing embodiments,

[0130] The control information includes an identifier that identifies the selected MAC output data unit.

[0131] 5. The first communication device as defined in any of the foregoing embodiments,

[0132] The first communication device is configured to notify the third communication device of the coordinated transmission of selected PHY output data units by the first communication device and the third communication device.

[0133] 6. The first communication device as defined in Example 5,

[0134] The first communication device is configured to notify the third communication device by sending a trigger and / or announcement including one or more of the following:

[0135] - Identifiers for one or more selected MAC output data units, used to generate selected PHY output data units for transmission by the third communication device to the second communication device in a coordinated transmission.

[0136] - PHY layer configuration information, indicating the configuration of the PHY layer circuitry of the third communication device used to generate the selected PHY output data unit.

[0137] - Spatial mapping information, indicating the spatial mapping performed by a third communication device used in the coordinated transmission, and

[0138] - stream index information indicating one or more streams served by the third communication device used in the coordinated transmission.

[0139] 7. The first communication device as defined in any one of the preceding embodiments,

[0140] wherein the control information is comprised in or associated with the respective selected MAC output data unit.

[0141] 8. The first communication device as defined in embodiment 7,

[0142] wherein the control information is comprised in a preamble of the respective selected MAC output data unit or in a control frame.

[0143] 9. The first communication device as defined in any one of the preceding embodiments,

[0144] wherein the MAC layer circuitry is configured to perform, after generating the control information, MAC layer processing on the one or more selected MAC output data units that are selected MAC input data units to generate one or more selected new MAC output data units, and

[0145] wherein the PHY layer circuitry is configured to perform, on the one or more selected new MAC output data units, PHY layer processing to generate one or more selected new PHY output data units for transmission to the third communication device according to the address information comprised in the control information.

[0146] 10. The first communication device as defined in any one of the preceding embodiments,

[0147] wherein the first communication device is configured to provide the one or more selected MAC output data units and the control information to an external entity different from the third communication device to enable the external entity to provide the one or more selected MAC output data units to the third communication device according to the control information.

[0148] 11. The first communication device as defined in any one of the preceding embodiments,

[0149] wherein the first communication device and the third communication device are configured to operate as access points and the second communication device is configured to operate as a station.

[0150] 12. The first communication device as defined in any one of the preceding embodiments,

[0151] wherein the MAC input data units are MAC service data units (MSDUs) or aggregated MSDUs (A-MSDUs), the MAC output data units are MAC protocol data units (MPDUs) or aggregated MPDUs (A-MPDUs), and the PHY output data units are physical protocol data units (PPDUs).

[0152] 13. The first communication device as defined in any one of the preceding embodiments,

[0153] wherein the PHY layer circuitry is configured to:

[0154] - divide the MAC output data units into N spatial streams,

[0155] - perform interleaving and / or constellation mapping processing in parallel for each spatial stream,

[0156] - perform spatial stream mapping to map the processed N spatial streams onto M transmit streams, and

[0157] - perform inverse Fourier transform, and analog and RF processing on the M transmit streams to generate M transmit signals, M corresponding to a number of active transmit chains of the first communication device.

[0158] 14. The first communication device as defined in any one of the preceding embodiments,

[0159] wherein the PHY layer circuitry is configured to:

[0160] - divide the MAC output data units into N spatial streams, and

[0161] - for M of the N spatial streams, perform interleaving and / or constellation mapping, spatial stream mapping, inverse Fourier transform, and analog and RF processing in parallel for each spatial stream to generate M transmit signals, M corresponding to a number of active transmit chains of the first communication device.

[0162] 15. A third communication device, comprising:

[0163] - MAC layer circuitry configured to obtain, from a first communication device, one or more selected medium access control (MAC) output data units and associated control information, the control information indicating that the one or more selected MAC output data units are to be processed at a physical (PHY) layer by the third communication device and that the one or more selected MAC output data are to be transmitted from the third communication device and from the first communication device to a second communication device; and

[0164] - PHY layer circuitry configured to generate selected PHY output data units from the selected MAC output data units by performing PHY layer processing on the selected MAC output data units, for transmission from the third communication device to the second communication device in coordination with transmission of the selected PHY output data units generated by the first communication device from the selected MAC output data units.

[0165] 16. The third communication device as defined in embodiment 15,

[0166] wherein the PHY layer circuitry is configured to receive one or more selected MAC output data units from the first communication device and perform inverse PHY layer processing on the one or more selected MAC output data units to generate inverse PHY layer output data units,

[0167] wherein the MAC layer circuitry is configured to perform inverse MAC layer processing on the inverse PHY layer output data units to obtain the associated control information and the selected MAC output data units, and

[0168] wherein the PHY layer circuitry is configured to generate the selected PHY output data units from the selected MAC output data units.

[0169] 17. The third communication device as defined in any one of embodiments 15 to 16,

[0170] wherein the MAC layer circuitry is configured to receive the one or more selected MAC output data units and the associated control information from an external entity different from the first communication device.

[0171] 18. The third communication device as defined in any one of embodiments 15 to 17,

[0172] wherein the MAC layer circuitry is configured to process control information comprising an identifier identifying the selected MAC output data units.

[0173] 19. The third communication device as defined in any one of embodiments 15 to 18,

[0174] wherein the third communication device is configured to receive a notification from the first communication device informing the third communication device about coordination of the first communication device and the third communication device for transmission of the PHY output data units.

[0175] 20. The third communication device as defined in any one of embodiments 15 to 19,

[0176] wherein the third communication device is configured to:

[0177] receive a trigger and / or an announcement comprising one or more of:

[0178] - an identifier of one or more selected MAC output data units for generating selected PHY output data units for transmission by the third communication device to the second communication device in a coordinated transmission,

[0179] - PHY layer configuration information indicating a configuration of PHY layer circuitry of the third communication device for generating the selected PHY output data units,

[0180] - spatial mapping information indicating a spatial mapping performed by the third communication device for use in the coordinated transmission, and

[0181] - stream index information indicating one or more streams served by the third communication device for use in the coordinated transmission, and

[0182] using the information comprised in the trigger and / or announcement for determining the selected MAC output data units and / or for setting the PHY layer configuration, the spatial mapping and / or the stream transmission of the one or more streams.

[0183] 21. A communication method of a first communication device, the first communication method comprising:

[0184] - generating MAC output data units by performing medium access control (MAC) layer processing on MAC input data units to be transmitted to a second communication device,

[0185] - generating control information for one or more selected MAC output data units, the control information indicating that the one or more selected MAC output data units are to be subjected to physical (PHY) layer processing by a third communication device and that the one or more selected MAC output data units are to be transmitted from the third communication device and from the first communication device to the second communication device,

[0186] - providing the one or more selected MAC output data units and the associated control information to the third communication device, and

[0187] - generating PHY output data units by performing PHY layer processing on the MAC output data units, wherein selected PHY output data units are generated from the selected MAC output data units for transmission from the first communication device to the second communication device in coordination with the transmission of selected PHY output data units generated by the third communication device from the selected MAC output data units.

[0188] 22. A communication method of a third communication device, the third communication method comprising:

[0189] - obtaining, from the first communication device, one or more selected medium access control (MAC) output data units and associated control information, the control information indicating that the one or more selected MAC output data units are to be subjected to physical (PHY) layer processing by the third communication device and that the one or more selected MAC output data units are to be transmitted from the third communication device and from the first communication device to the second communication device, and

[0190] - generating selected PHY output data units by performing the PHY layer processing on the selected MAC output data units for transmission from the third communication device to the second communication device in coordination with the transmission of the selected PHY output data units generated by the first communication device from the selected MAC output data units.

[0191] 23. A non-transitory computer-readable recording medium storing a computer program product that, when executed by a processor, causes the method of clause 21 or 22 to be performed.

[0192] 24. A computer program comprising program code means which, when said computer program is executed on a computer, causes the computer to carry out the steps of the method according to embodiment 21 or 22.

Claims

1. A first communication device, comprising: - The Media Access Control (MAC) layer circuitry is configured as follows: - A MAC output data unit is generated by performing MAC layer processing on the MAC input data unit to be sent to the second communication device, and - Generate control information for one or more selected MAC output data units, the control information indicating that one or more selected MAC output data units will be processed by the third communication device at the physical (PHY) layer, and that one or more selected MAC output data units will be transmitted from the third communication device and from the first communication device to the second communication device; as well as - A PHY layer circuit is configured to generate a PHY output data unit by performing PHY layer processing on the MAC output data unit, wherein a selected PHY output data unit is generated from a selected MAC output data unit to be transmitted from the first communication device to the second communication device in coordination with the transmission of a selected PHY output data unit generated by the third communication device from the selected MAC output data unit. The first communication device is configured to provide the third communication device with one or more selected MAC output data units and the associated control information. The PHY layer circuit is characterized in that it is further configured to divide the MAC output data unit into N spatial streams and perform any of the following: i) Perform interleaving and / or constellation mapping processing in parallel for each spatial stream, perform spatial stream mapping to map the processed N spatial streams to M transmit streams, and perform inverse Fourier transform, as well as analog and RF processing on the M transmit streams to generate M transmit signals; ii) For M of the N spatial streams, perform interleaving and / or constellation mapping, spatial stream mapping, inverse Fourier transform, and analog and RF processing in parallel for each spatial stream to generate M transmitted signals. Where M corresponds to the number of active transmission chains of the first communication device and is less than N.

2. The first communication device as described in claim 1, in, The MAC layer circuit is configured to select one or more of the MAC input data units based on one or more of the following: the destination address of the MAC input data unit, the location of the second communication unit, the channel state information between the first communication device and the second communication device, the channel state information between the third communication device and the second communication device, and the priority of the MAC input data unit, in order to generate the selected MAC output data unit.

3. The first communication device as described in claim 1, in, The control information includes: source address information, indicating that the first communication device is the source of the selected MAC output data unit; and destination address information, indicating that the third communication device is the destination of the selected MAC output data unit.

4. The first communication device as described in claim 1, in, The control information includes an identifier that identifies the selected MAC output data unit.

5. The first communication device as described in claim 1, in, The first communication device is configured to notify the third communication device of the coordinated transmission of selected PHY output data units by the first communication device and the third communication device.

6. The first communication device as described in claim 5, in, The first communication device is configured to notify the third communication device by sending a trigger and / or announcement including one or more of the following: - Identifiers for one or more selected MAC output data units, used to generate selected PHY output data units for transmission by the third communication device to the second communication device in the coordinated transmission. - PHY layer configuration information, indicating the configuration of the PHY layer circuitry of the third communication device used to generate the selected PHY output data unit. - Spatial mapping information, indicating the spatial mapping performed by the third communication device used in the coordinated transmission, and - Stream index information, indicating one or more streams served by the third communication device used in the coordinated transmission.

7. The first communication device as described in claim 1, in, The control information is included in or associated with the corresponding selected MAC output data unit.

8. The first communication device as described in claim 7, in, The control information is included in the header of the corresponding selected MAC output data unit or in the control frame.

9. The first communication device as described in claim 1, in, The MAC layer circuitry is configured to, after generating the control information, perform the MAC layer processing on one or more selected MAC output data units that are selected MAC input data units, to generate one or more selected new MAC output data units, and The PHY layer circuitry is configured to perform the PHY layer processing on one or more selected new MAC output data units to generate one or more selected new PHY output data units for transmission to the third communication device based on address information included in the control information.

10. The first communication device as described in claim 1, in, The first communication device is configured to provide one or more selected MAC output data units and the control information to an external entity different from the third communication device, so that the external entity can provide one or more selected MAC output data units to the third communication device according to the control information.

11. The first communication device as described in claim 1, in, The first communication device and the third communication device are configured to operate as access points, and the second communication device is configured to operate as a station.

12. The first communication device as described in claim 1, in, The MAC input data unit is a MAC Service Data Unit (MSDU) or an Aggregated MSDU (A-MSDU), the MAC output data unit is a MAC Protocol Data Unit (MPDU) or an Aggregated MPDU (A-MPDU), and the PHY output data unit is a Physical Protocol Data Unit (PPDU).

13. A third communication device, including: - A Media Access Control (MAC) layer circuit is configured to obtain one or more selected MAC output data units and associated control information from a first communication device, the control information indicating that one or more selected MAC output data units will be physically (PHY) processed by the third communication device, and one or more selected MAC output data units will be transmitted from the third communication device and from the first communication device to a second communication device. as well as - A PHY layer circuit is configured to generate a selected PHY output data unit by performing PHY layer processing on the selected MAC output data unit, so as to transmit the selected PHY output data unit generated by the first communication device from the selected MAC output data unit to the second communication device in coordination with the transmission of the selected PHY output data unit generated by the first communication device from the selected MAC output data unit. The PHY layer circuit is characterized in that it is further configured to divide the MAC output data unit into N spatial streams and perform any of the following: i) Perform interleaving and / or constellation mapping processing in parallel for each spatial stream, perform spatial stream mapping to map the processed N spatial streams to M transmit streams, and perform inverse Fourier transform, as well as analog and RF processing on the M transmit streams to generate M transmit signals; ii) For M of the N spatial streams, perform interleaving and / or constellation mapping, spatial stream mapping, inverse Fourier transform, and analog and RF processing in parallel for each spatial stream to generate M transmitted signals. Where M corresponds to the number of active transmission chains of the first communication device and is less than N.

14. The third communication device as described in claim 13, in, The PHY layer circuitry is configured to receive one or more selected MAC output data units from the first communication device, and to perform inverse PHY layer processing on the one or more selected MAC output data units to generate inverse PHY layer output data units. The MAC layer circuit is configured to perform inverse MAC layer processing on the inverse PHY layer output data unit to obtain the associated control information and the selected MAC output data unit. The PHY layer circuit is configured to generate a selected PHY output data unit from a selected MAC output data unit.

15. The third communication device as described in claim 13, in, The MAC layer circuitry is configured to receive one or more selected MAC output data units and the associated control information from an external entity different from the first communication device.

16. A communication method for a first communication device, the first communication method comprising: - A MAC output data unit is generated by performing MAC layer processing on the Media Access Control (MAC) input data unit to be sent to the second communication device. - Control information is generated for one or more selected MAC output data units, the control information instructing one or more selected MAC output data units to be physically (PHY) processed by a third communication device, and one or more selected MAC output data units to be transmitted from the third communication device and from the first communication device to the second communication device. - Provide the third communication device with one or more selected MAC output data units and the associated control information, and - A PHY output data unit is generated by performing PHY layer processing on the MAC output data unit, wherein the selected PHY output data unit is generated from the selected MAC output data unit to be transmitted from the first communication device to the second communication device in coordination with the transmission of the selected PHY output data unit generated by the third communication device from the selected MAC output data unit. The PHY layer circuit is characterized in that it is further configured to divide the MAC output data unit into N spatial streams and perform any of the following: i) Perform interleaving and / or constellation mapping processing in parallel for each spatial stream, perform spatial stream mapping to map the processed N spatial streams to M transmit streams, and perform inverse Fourier transform, as well as analog and RF processing on the M transmit streams to generate M transmit signals; ii) For M of the N spatial streams, perform interleaving and / or constellation mapping, spatial stream mapping, inverse Fourier transform, and analog and RF processing in parallel for each spatial stream to generate M transmitted signals. Where M corresponds to the number of active transmission chains of the first communication device and is less than 1.

17. A communication method of a third communication device, the third communication method including: - Obtain one or more selected Media Access Control (MAC) output data units and associated control information from the first communication device, the control information indicating that the one or more selected MAC output data units will be physically (PHY) processed by the third communication device, and that the one or more selected MAC output data units will be transmitted from the third communication device and from the first communication device to the second communication device, and - A selected PHY output data unit is generated by performing PHY layer processing on the selected MAC output data unit, so as to be transmitted from the third communication device to the second communication device in coordination with the transmission of the selected PHY output data unit generated by the first communication device from the selected MAC output data unit. The PHY layer circuit is characterized in that it is further configured to divide the MAC output data unit into N spatial streams and perform any of the following: i) Perform interleaving and / or constellation mapping processing in parallel for each spatial stream, perform spatial stream mapping to map the processed N spatial streams to M transmit streams, and perform inverse Fourier transform, as well as analog and RF processing on the M transmit streams to generate M transmit signals; ii) For M of the N spatial streams, perform interleaving and / or constellation mapping, spatial stream mapping, inverse Fourier transform, and analog and RF processing in parallel for each spatial stream to generate M transmitted signals. Where M corresponds to the number of active transmission chains of the first communication device and is less than 1.

18. A non-transitory computer-readable recording medium storing a computer program product, which, when executed by a processor, causes to perform the method according to claim 16 or 17.

Images