Patent Publication Number: US-2021195618-A1

Title: Sdm iab transmission

Description:
FIELD 
     Embodiments of the present disclosure generally relate to wireless communication, and in particular, to a method, a device and a computer readable medium for Space Division Multiplexing (SDM) Integrated Access and Backhaul (IAB) transmission. 
     BACKGROUND 
     The latest developments of the 3GPP standards are referred to as Long Term Evolution (LTE) of Evolved Packet Core (EPC) network and Evolved UMTS Terrestrial Radio Access Network (E-UTRAN), also commonly termed as ‘4G’. In addition, the term ‘5G New Radio (NR)’ refers to an evolving communication technology that is expected to support a variety of applications and services. 5G NR is part of a continuous mobile broadband evolution promulgated by Third Generation Partnership Project (3GPP) to meet new requirements associated with latency, reliability, security, scalability (e.g., with Internet of Things (IoTz)), and other requirements. Some aspects of 5G NR may be based on the 4G Long Term Evolution (LTE) standard. 
     Recently, regarding IAB deployment scenarios, it is agreed that in-band IAB scenarios including TDM/FDM/SDM of an access link and a backhaul link subject to half-duplex constraint at an IAB node should be supported. In particular, it is agreed that downlink IAB transmission (transmission from an IAB node to a child IAB node or a UE directly communicating with the IAB node) should be scheduled by the IAB node itself, and uplink IAB transmission (transmission from an IAB node to its parent node) should be scheduled by the parent node. However, MIMO operations for an SDM IAB node are still not clear and need to be studied. 
     SUMMARY 
     In general, example embodiments of the present disclosure provide methods, devices and computer readable media for SDM IAB transmission. 
     In a first aspect, there is provided a method for communication. The method comprises determining, at a first device, a first set of transmission resources related to first data transmission between the first device and a second device operating in a half-duplex manner as a relay between the first device and a third device. The method also comprises transmitting to the second device scheduling information indicating the first set of transmission resources, such that the second device determines, based on the first set of transmission resources, a second set of transmission resources to be used for second data transmission between the second device and the third device. 
     In a second aspect, there is provided a method for communication. The method comprises receiving from a first device, by a second device operating in a half-duplex manner as a relay between the first device and a third device, first scheduling information indicating a first set of transmission resources related to first data transmission between the first device and the second device. The method also comprises determining, based on the first set of transmission resources, a second set of transmission resources to be used for second data transmission between the second device and the third device. The method further comprises transmitting to the third device second scheduling information indicating the second set of transmission resources. 
     In a third aspect, there is provided a device. The device comprises a processor and a memory storing instructions. The memory and the instructions are configured, with the processor, to cause the device to perform the method according to the first aspect. 
     In a fourth aspect, there is provided a device. The device comprises a processor and a memory storing instructions. The memory and the instructions are configured, with the processor, to cause the device to perform the method according to the second aspect. 
     In a fifth aspect, there is provided a computer readable medium having instructions stored thereon. The instructions, when executed on at least one processor of a device, cause the device to carry out the method according to the first aspect. 
     In a sixth aspect, there is provided a computer readable medium having instructions stored thereon. The instructions, when executed on at least one processor of a device, cause the device to carry out the method according to the second aspect. 
     It is to be understood that the summary section is not intended to identify key or essential features of embodiments of the present disclosure, nor is it intended to be used to limit the scope of the present disclosure. Other features of the present disclosure will become easily comprehensible through the following description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Through the more detailed description of some embodiments of the present disclosure in the accompanying drawings, the above and other objects, features and advantages of the present disclosure will become more apparent, wherein: 
         FIG. 1  is a schematic diagram of a communication environment in which some embodiments of the present disclosure can be implemented; 
         FIG. 2  shows an example process of communication among a first device, a second device, and a third device in accordance with some embodiments of the present disclosure; 
         FIG. 3  shows an example relation between a first set of transmission resources and a second set of transmission resources in accordance with some embodiments of the present disclosure; 
         FIG. 4A  shows an example process of communication between the first device and the second device for implementing SDM transmission of the second device in a transmitting mode in accordance with some embodiments of the present disclosure; 
         FIG. 4B  shows another example process of communication between the first device and the second device for implementing SDM transmission of the second device in a transmitting mode in accordance with some embodiments of the present disclosure; 
         FIG. 5  shows an example process of communication between the first device and the second device for the second device requesting the first device to transmit scheduling information in accordance with some embodiments of the present disclosure; 
         FIG. 6  shows an example process of communication among the first device, the second device, and the third device for power control in accordance with some embodiments of the present disclosure; 
         FIG. 7  shows another example process of communication among the first device, the second device, and the third device for power control in accordance with some embodiments of the present disclosure; 
         FIG. 8  shows an example process of communication among the first device, the second device, and the third device with a confirmation mechanism in accordance with some embodiments of the present disclosure; 
         FIG. 9A  shows an example of activation and deactivation of special scheduling with specific signaling in accordance with some embodiments of the present disclosure; 
         FIG. 9B  shows another example of activation and deactivation of special scheduling with specific signaling in accordance with some embodiments of the present disclosure; 
         FIG. 10  shows a flowchart of an example method in accordance with some embodiments of the present disclosure; 
         FIG. 11  shows a flowchart of another example method in accordance with some embodiments of the present disclosure; and 
         FIG. 12  is a simplified block diagram of a device that is suitable for implementing some embodiments of the present disclosure. 
     
    
    
     Throughout the drawings, the same or similar reference numerals represent the same or similar elements. 
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Principle of the present disclosure will now be described with reference to some example embodiments. It is to be understood that these embodiments are described only for the purpose of illustration and help those skilled in the art to understand and implement the present disclosure, without suggesting any limitations as to the scope of the disclosure. The disclosure described herein can be implemented in various manners other than the ones described below. 
     In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skills in the art to which this disclosure belongs. 
     As used herein, the term “network device” or “base station” (BS) refers to a device which is capable of providing or hosting a cell or coverage where terminal devices can communicate. Examples of a network device include, but not limited to, a Node B (NodeB or NB), an Evolved NodeB (eNodeB or eNB), a next generation NodeB (gNB), a Transmission/Reception Point (TRP), a Remote Radio Unit (RRU), a radio head (RH), a remote radio head (RRH), a low power node such as a femto node, a pico node, and the like. 
     As used herein, the term “terminal device” refers to any device having wireless or wired communication capabilities. Examples of the terminal device include, but not limited to, user equipment (UE), personal computers, desktops, mobile phones, cellular phones, smart phones, personal digital assistants (PDAs), portable computers, image capture devices such as digital cameras, gaming devices, music storage and playback appliances, or Internet appliances enabling wireless or wired Internet access and browsing and the like. For the purpose of discussion, in the following, some embodiments will be described with reference to UEs as examples of terminal devices and the terms “terminal device” and “user equipment” (UE) may be used interchangeably in the context of the present disclosure. 
     As used herein, the term “transmission/reception point” may generally indicate a station communicating with the user equipment. However, the transmission/reception point may be referred to as different terms such as a base station (BS), a cell, a Node-B, an evolved Node-B (eNB), a next generation NodeB (gNB), a Transmission Reception Point (TRP), a sector, a site, a base transceiver system (BTS), an access point (AP), a relay node (RN), a remote radio head (RRH), a radio unit (RU), an antenna, and the like. 
     That is, in the context of the present disclosure, the transmission/reception point, the base station (BS), or the cell may be construed as an inclusive concept indicating a portion of an area or a function covered by a base station controller (BSC) in code division multiple access (CDMA), a Node-B in WCDMA, an eNB or a sector (a site) in LTE, a gNB or a TRP in NR, and the like. Accordingly, a concept of the transmission/reception point, the base station (BS), and/or the cell may include a variety of coverage areas such as a megacell, a macrocell, a microcell, a picocell, a femtocell, and the like. Furthermore, such concept may include a communication range of the relay node (RN), the remote radio head (RRH), or the radio unit (RU). 
     In the context of the present disclosure, the user equipment and the transmission/reception point may be two transmission/reception subjects, having an inclusive meaning, which are used to embody the technology and the technical concept disclosed herein, and may not be limited to a specific term or word. Furthermore, the user equipment and the transmission/reception point may be uplink or downlink transmission/reception subjects, having an inclusive meaning, which are used to embody the technology and the technical concept disclosed in connection with the present embodiment, and may not be limited to a specific term or word. Herein, an uplink (UL) transmission/reception is a scheme in which data is transmitted from user equipment to a base station. Alternatively, a downlink (DL) transmission/reception is a scheme in which data is transmitted from the base station to the user equipment. 
     As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. The term “includes” and its variants are to be read as open terms that mean “includes, but is not limited to.” The term “based on” is to be read as “based at least in part on.” The term “one embodiment” and “an embodiment” are to be read as “at least one embodiment.” The term “another embodiment” is to be read as “at least one other embodiment.” The terms “first,” “second,” and the like may refer to different or same objects. Other definitions, explicit and implicit, may be included below. 
     In some examples, values, procedures, or apparatus are referred to as “best,” “lowest,” “highest,” “minimum,” “maximum,” or the like. It will be appreciated that such descriptions are intended to indicate that a selection among many used functional alternatives can be made, and such selections need not be better, smaller, higher, or otherwise preferable to other selections. 
       FIG. 1  is a schematic diagram of a communication environment  100  in which some embodiments of the present disclosure can be implemented. As shown in  FIG. 1 , the communication environment  100  may include a first device  110 , a second device  120 , and a third device  130 . In some embodiments, the second device  120  may operate in a half-duplex manner as a relay between the first device  110  and the third device  130 . This means that the first device  110  and the third device  130  may indirectly communicate with each other through the second device  120 . 
     In particular, the first device  110  may transmit signals to the second device  120  via a communication link  112  and receive signals from the second device  120  via a communication link  114 , and the third device  130  may transmit signals to the second device  120  via a communication link  124  and receive signals from the second device  120  via a communication link  122 . As mentioned, the second device  120  may operate in a half-duplex manner. That is, the second device  120  may not perform transmitting and receiving simultaneously. 
     For example, the second device  120  may receive signals from the first device  110  via the communication link  112  and from the third device  130  via the communication link  124  simultaneously, and may transmit signals to the first device  110  via the communication link  114  and to the third device  130  via the communication link  122  simultaneously. However, the second device  120  may not transmit signals to the first device  110  via the communication link  114  and receive signals from the third device  130  via the communication link  124  simultaneously, or receive signals from the first device  110  via the communication link  112  and transmit signals to the third device  130  via the communication link  122  simultaneously. 
     In some scenarios, the first device  110  may be a gNB, the third device  130  may be a terminal device (such as a UE), and the second device  120  may be a relay node between the gNB and the UE. In such scenarios, the first device  110  may also be referred to as an IAB donor, and the second device  120  may also be referred to as an IAB node. In some scenarios, the second device  120  may be an IAB node, the first device  110  may be another IAB node which is a parent node of the second device  120 , and the third device  130  may be a terminal device (such as a UE) or a further IAB node which is a child node of the second device  120 . The communication links  112  and  114  may be referred to as a backhaul downlink and a backhaul uplink, respectively, and may be referred to as backhaul links or parent links, collectively. The communication links  122  and  124  may be referred to as an access downlink and an access uplink, respectively, and may be referred to as access links or child links, collectively. 
     In some other scenarios, either or both of the first device  110  and the third device  130  may also be a relay, such as an IAB node. For example, this may be the case in a multi-hop backhauling scenario. If the third device  130  is a relay, the communication links  122  and  124  may also be backhaul links, rather than access links. In the case of the second and third devices  120  and  130  are both relays, the communication links  122  and  124  may be also referred to as child backhaul links. Accordingly, various embodiments described herein with respect to a backhaul link and an access link may also be applicable to these scenarios, in which the access link is replaced by another backhaul link. 
     The communications in the communication environment  100  may conform to any suitable standards including, but not limited to, Global System for Mobile Communications (GSM), Extended Coverage Global System for Mobile Internet of Things (EC-GSM-IoT), Long Term Evolution (LTE), LTE-Evolution, LTE-Advanced (LTE-A), Wideband Code Division Multiple Access (WCDMA), Code Division Multiple Access (CDMA), GSM EDGE Radio Access Network (GERAN), and the like. Furthermore, the communications may be performed according to any generation communication protocols either currently known or to be developed in the future. Examples of the communication protocols include, but not limited to, the first generation (1G), the second generation (2G), 2.5G, 2.75G, the third generation (3G), the fourth generation (4G), 4.5G, the fifth generation (5G) communication protocols. 
     It is to be understood that the number of devices as shown in  FIG. 1  are only for the purpose of illustration without suggesting any limitations. Actually, the communication environment  100  may include any suitable number of devices adapted for implementing embodiments of the present disclosure. It is also to be understood that the term “device” as used herein may be a network device or a terminal device in different communication scenarios. 
     In recent development of 5G NR, it is agreed that mechanisms for efficient TDM/FDM/SDM multiplexing of access/backhaul traffic across multiple hops considering an IAB node half-duplex constraint should be studied. There are several solutions for different multiplexing options which can be further studied. The first solution may be mechanisms for orthogonal partitioning of time slots or frequency resources between access and backhaul links across one or multiple hops. 
     The second solution may be utilization of different DL/UL slot configurations for access and backhaul links. The third solution may be DL and UL power control enhancements and timing requirements to allow for intra-panel FDM and SDM of backhaul and access links. The fourth solution may be interference management including cross-link interference. However, as indicated above, MIMO operations for an SDM IAB node are still not clear and also need to be studied. 
     In order to solve the above technical problems and potentially other technical problems in conventional solutions, embodiments of the present disclosure provide methods, devices and computer readable media for SDM IAB transmission. The embodiments of the present disclosure support backhaul transmission from an IAB node to an IAB donor, and thus support SDM for IAB transmission of the IAB node. Principles and implementations of the present disclosure will be described in detail below with reference to the figures. 
       FIG. 2  shows an example process  200  of communication among a first device, a second device, and a third device in accordance with some embodiments of the present disclosure. For the purpose of discussion, the example process  200  will be described with reference to  FIG. 1 . In some embodiments, the example process  200  may involve the first, second, and third devices  110 ,  120 , and  130  in  FIG. 1 . 
     As shown in  FIG. 2 , the first device  110  determines  205  a first set of transmission resources related to first data transmission between the first device  110  and the second device  120 . As will be detailed later, the first set of transmission resources are used for the second device  120  to determine transmission resources used for second data transmission between the second device  120  and the third device  130 . The purpose is to eliminate or reduce interference between the first data transmission and the second data transmission. In the following, the first data transmission and the second data transmission may also be referred to as S1 and S2 respectively for short. 
     In some embodiments, the first device  110  may determine a set of transmission resources to be used for the first data transmission as the first set of transmission resources. Alternatively, the first device  110  may determine a set of transmission resources not to be used for the first data transmission as the first set of transmission resources. In this way, the first device  110  may inform to the second device  120  some explicit information regarding the transmission resources associated with the first data transmission. 
     The first device  110  transmits  210  to the second device  120  first scheduling information, which indicates the first set of transmission resources. Correspondingly, the second device  120  receives  210  the first scheduling information from the first device  110 . In the following, the scheduling related to the first scheduling information may also be referred to as special scheduling, because normal scheduling information transmitted by the first device  110  to the second device  120  is used for scheduling data transmission between them, whereas the intention of the first scheduling information is to coordinate the scheduling of data transmission between the second device  120  and the third device  130 , which data transmission may also be referred to as special transmission herein. 
     The second device  120  determines  215  a second set of transmission resources based on the first set of transmission resources, which is to be used for second data transmission between the second device  120  and the third device  130 . As mentioned, the second set of transmission resources may be determined such that the second data transmission is not to be or less interfered by the first data transmission. That is, time/frequency/spatial resource allocations for the second data transmission are confined by the special transmission. 
     For example, if the first set of transmission resources is a set of transmission resources to be used for the first data transmission, the second device  120  may determine a complementary set of the first set of transmission resources with respect to a universal set of all available transmission resources. In other words, the second device  120  determines the complementary set as the second set of transmission resources, so that the first data transmission and the second data transmission may be performed using different transmission resources. Thus, the interference between them may be reduced or even eliminated. 
     Alternatively, if the first set of transmission resources is a set of transmission resources not to be used for the first data transmission, the second device  120  may determine a subset of the first set of transmission resources as the second set of transmission resources. In other words, the second device  120  determines the subset as the second set of transmission resources, so that the transmission resources used for the second data transmission are not to be used for the first data transmission. Thus, the interference between them may be reduced or even eliminated. 
       FIG. 3  shows an example relation  300  between the first set of transmission resources and the second set of transmission resources in accordance with some embodiments of the present disclosure. In the example relation  300  as shown in  FIG. 3 , the second set of transmission resources is a subset of the first set of transmission resources. 
     In particular, the control resource set (CORSET) as defined in 3GPP new radio (NR) systems may be denoted as  310  and may be optionally configured. The first device  110  may determine the first set of transmission resources including a DMRS set  320  and time/frequency resources  330  for the first data transmission, such as in the uplink of backhaul link. Accordingly, based on the DMRS set  320  and the time/frequency resources  330 , the second device  120  may determine the second set of transmission resources including a DMRS set  325  and time/frequency resources  335  for the second data transmission, such as in the downlink of access link. As shown, the DMRS set  325  and the time/frequency resources  335  are subsets of the DMRS set  320  and the time/frequency resources  330 , respectively. 
     Referring back to  FIG. 2 , after determining the second set of transmission resources for second data transmission between the second device  120  and the third device  130 , the second device  120  transmits  220  to the third device  130  second scheduling information, which indicates the second set of transmission resources. Therefore, the second device  120  may communicate with the third device  130  using the second set of transmission resources. 
     For example, the second device  120  may transmit  225  signals to the third device  130 , and may receive  230  signals from the third device  130 . It is noted that since the second set of transmission resources are selected based on the first set of transmission resources related to the first data transmission, the second data transmission may not be or less interfered by the first data transmission. 
     In addition, the scheduling indicated by the second scheduling information may need not to be exchanged to the first device  110 . However, the first device  110  may be aware of active resources in the communication links  122  and  124 , and thus controllable interference from the communication links  122  and  124  to the communication links  112  and  114  may be also available for the first device  110 . 
       FIG. 4A  shows an example process  400  of communication between the first device  110  and the second device  120  for implementing SDM transmission of the second device  120  in a transmitting mode in accordance with some embodiments of the present disclosure. In other words, the example process  400  may be used to schedule simultaneous transmissions from the second device  120  to the first device  110  and to the third device  130 . In this way, the two transmissions may be multiplexed, for example, by spatial division. 
     As shown in  FIG. 4A  and described with reference to  FIG. 2 , the first device  110  transmits  210  the first scheduling information to the second device  120 . In addition to the first scheduling information, the first device  110  may transmit  410  to the second device  120  third scheduling information, which indicates a third set of transmission resources, that is to be used for transmission from the second device  120  to the first device  110 , such as a PUSCH transmission. The third set of transmission resources includes the same time and frequency resources as the second set of transmission resources, but includes a different spatial resource from the second set of transmission resources. Thus, the transmission from the second device  120  to the first device  110  is separated from the second data transmission in spatial domain. 
     Upon receiving  410  the third scheduling information from the first device  110 , the second device  120  determines  415  the third set of transmission resources from the third scheduling information. Then, the second device  120  may transmit  420  signals to the first device  110  using the third set of transmission resources and also transmit  225  signals to the third device  130  using the second set of transmission resources, as described above with reference to  FIG. 2 . In this scenario, the second device  120  may be regarded as a virtual UE with disabled data transmission for the first device  110 . Thus, the first device  110  may be considered to have two UEs, the first UE corresponds to the data transmission S1, and the second UE corresponds to the data transmission S2 but which is regarded as disabled from a view of the first device  110 . In some embodiments, a DMRS for S2 transmitted in the access link may be estimated at the first device  110  in the backhaul link for interference cancellation. 
     In some embodiments, the scheduling indicated by the first scheduling information may be semi-persistent scheduling, for example, which may be scheduled by a DCI scrambled by an identifier of CS-RNTI in NR. Thus, the first device  110  may transmit  430  new semi-persistent scheduling information to the second device  120 , to reschedule the first set of transmission resources including time resources, frequency resources (in terms of RBs), antenna ports or the like. In contrast, the scheduling indicated by the third scheduling information may be dynamic scheduling, which can be an addition to the scheduling indicated by the first scheduling information, rather than colliding or overwriting the first scheduling. 
       FIG. 4B  shows another example process  405  of communication between the first device  110  and the second device  120  for implementing SDM transmission of the second device  120  in a transmitting mode in accordance with some embodiments of the present disclosure. In other words, the example process  405  may also be used to schedule simultaneous transmissions from the second device  120  to the first device  110  and to the third device  130 . In this way, the two transmissions may be multiplexed, for example, by spatial division. 
     As shown in  FIG. 4B , the first device  110  transmits  440  the first scheduling information including both the first set of transmission resources and the third set of transmission resources. In other words, the first device  110  indicates the third set of transmission resources in the first scheduling information, instead of transmitting separate scheduling information. 
     In this event, the second device  120  determines  445  the third set of transmission resources along with the first set of transmission resources from the first scheduling information. Accordingly, the second device  120  transmits  450  to the first device  110  using the third set of transmission resources and transmits  225  to the third device using the second set of transmission resources, as described above with reference to  FIG. 2 . Again, the two transmissions from the second device  120  to the first device  110  and to the third device  130  may be spatial division multiplexed. 
       FIG. 5  shows an example process  500  of communication between the first device  110  and the second device  120  for the second device  120  requesting the first device  110  to transmit scheduling information in accordance with some embodiments of the present disclosure. In other words, in the example process  500 , the first device  110  may perform the special scheduling based on a request from the second device  120 . In this way, the second device  120  may be more active in the special scheduling and transmission, instead of being completely passive. 
     As shown in  FIG. 5 , the second device  120  may transmit  510  to the first device  110  a scheduling request, which requests the first device  110  to schedule transmission resources for the second data transmission. For example, this may be the case where the first device  110  has not performed the special scheduling currently. In some embodiments, the scheduling request may carry only one indication bit. 
     After receiving  510  the scheduling request from the second device  120 , the first device  110  may determine the first set of transmission resources related to the first data transmission, as described with reference to  FIG. 2 . 
     In some embodiments, the second device  120  may determine  515  that the second set of transmission resources is insufficient for the second data transmission. In such a case, the second device  120  transmits  520  to the first device  110 , information indicates that the second set of transmission resources is insufficient. As an example, the information may be dedicated buffer status report (BSR), which reports traffic load information between the second device  120  and the third device  130  in access link to the first device  110 . In other examples, the information may be any other suitable signaling. 
     After receiving  520  the information from the second device  120 , the first device  110  may transmit  210 ′ updated first scheduling information to the second device  120 . The updated first scheduling information may indicate an updated first set of transmission resources, which may result in an updated second set of transmission resources comprising more transmission resources than the second set of transmission resources. 
       FIG. 6  shows an example process  600  of communication among the first device  110 , the second device  120 , and the third device  130  for power coordination in accordance with some embodiments of the present disclosure. In some embodiments, the example process  600  may be used to coordinate transmission power of transmission from the second device  120  to the third device  130 . In this way, the power control of the communication link (for example, the access link) between the second device  120  and the third device  130  may be performed taking into account the communication link (for example, the backhaul link) between the first device  110  and the second device  120 . 
     As shown in  FIG. 6 , the first device  110  obtains  605  a first path loss estimate of a first communication link  112  or  114  between the first device  110  and the second device  120 , for example, the backhaul link. Additionally, the first device  110  may request  610  from the second device  120  a second path loss estimate of a second communication link  122  or  124  between the second device  120  and the third device  130 , for example, the access link. 
     Upon receiving  610  the request from the first device  110 , the second device  120  may transmit  615  to the first device  110  the path loss estimate of the second communication link  122  or  124  between the second device  120  and the third device  130 . Correspondingly, the first device  110  receives  615  the second path loss estimate from the second device  120 . 
     The first device  110  then determines  620  a power control based on any one or a combination of the first and second path loss estimates. The power control is used for transmission from the second communication  120  to the third device  130 . The first device  110  transmits  210  to the second device  120  the first scheduling information including the determined power control. That is, the first device  110  may indicate the determined power control in the first scheduling information. 
     After receiving  210  the first scheduling information from the first device  110 , the second device  120  obtains  630  the power control from the first scheduling information. Then, the second device  120  may apply  635  the power control to the transmission from the second device  120  to the third device  130 . As an example, this power control may be expressed by equations as below. 
     
       
         
           
             
               
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       FIG. 7  shows another example process  700  of communication among the first device  110 , the second device  120 , and the third device  130  for power coordination in accordance with some embodiments of the present disclosure. In some embodiments, the example process  700  may be used to coordinate the transmission power of transmission from the first device  110  to the second device  120  (for example, in the backhaul link), so as to reduce interference with the transmission from the third device  130  to the second device  120 . In this way, the transmission from the third device  130  (for example, a UE) may not be severely interfered by the transmission from the first device  110 , for example, a gNB which may have much higher transmission power than a UE. 
     As shown in  FIG. 7 , the second device  120  transmits  705  to the first device  110  a power coordination request for requesting the first device  110  to adjust transmission power of transmission from the first device  110  to the second device  120  in the backhaul link. Correspondingly, the first device  110  receives  705  the power coordination request from the second device  120 . 
     If the first device  110  determines that the transmission power is to be adjusted, the first device  110  may transmit  710  to the second device  120  confirmation for the power coordination request. Accordingly, the first device  110  may transmit  725  to the second device  120  with the adjusted power in the backhaul link. 
     After the second device  120  receives  710  from the first device  110  confirmation for the power coordination request, the second device  120  may transmit  220  to the third device  130  the second scheduling information including power control information for controlling transmission power of transmission from the third device  130  to the second device  120 . In other words, the second device  120  may indicate this power control in the second scheduling information. Then, the second device  120  may receive  725  from the first device  110  with the adjusted power in the backhaul link and also receive  735  from the third device  130  with power under the power control indicated by the second device  120  in the access link. 
       FIG. 8  shows an example process  800  of communication among the first device  110 , the second device  120 , and the third device  130  with a confirmation mechanism in accordance with some embodiments of the present disclosure. In other words, in the example process  800 , the second device  120  may transmit confirmation information to the first device  110  when receiving special scheduling information. In this way, reliability of the special scheduling and transmission may be improved. 
     As shown in  FIG. 8 , upon receiving  210  the first scheduling information, the second device may transmit  805  to the first device  110  confirmation for the first scheduling information. Correspondingly, the first device  110  may receive  805  the confirmation from the second device  120 . 
     In some embodiments, the first device  110  may transmit  810  to the second device  120  a deactivation indication for deactivating the scheduling information. Correspondingly, the second device  120  may receive  810  the deactivation indication from the first device  110 . In response, the second device  120  may transmit  815  to the first device  110  confirmation for the deactivation indication. Correspondingly, the first device  110  receives  815  the confirmation for the deactivation indication from the second device  120 . 
     In some embodiments, the above-mentioned confirmation may also be referred to as grant confirmation. If the special scheduling is activated/deactivated by a DL DCI, the second device  120  (such as an IAB node) may transmit the grant confirmation (such as ACK/NACK) on a PUCCH in the backhaul link indicated by a PUCCH resource indicator in the activation DCI. If the special scheduling is activated/deactivated by a UL DCI, the second device  120  (such as an IAB node) may transmit the grant confirmation on a MAC-CE or a dedicated PUCCH via ACK/NACK in the backhaul link. 
     There may be various ways for the first device  110  to indicate the special scheduling information to the second device  120 . Table 1 as below shows different methods for the special scheduling signaling. These various methods will be described with further details with reference to following Tables 2-10. It is noted that the terms and abbreviations used in these tables may have the same meanings as that defined in 3GPP specifications. 
     
       
         
           
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                 Methods 
                 Content 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
            
               
                 All RRC configured 
                 Resource allocation (SLIV, or RB, or port) 
               
            
           
           
               
               
               
            
               
                   
                   
                 Periodicity (including slot format) 
               
               
                 RRC + 
                 RRC 
                 Resource allocation set (SLIV or RB, or port) 
               
               
                 MAC-CE or 
                   
                 Periodicities (including slot format) 
               
               
                 DCI 
                 MAC-CE or  
                 Activation/Deactivation and resource  
               
               
                   
                 GC DCI 
                 selection (bitmap) 
               
               
                 RRC + DCI 
                 RRC 
                 Periodicity (including slot format) 
               
               
                   
                 CS-RNTI  
                 Activation/Deactivation and resource  
               
               
                   
                 DCI 
                 allocation (SLIV, RB or port by  
               
               
                   
                   
                 DCI0_0, 0_1, 1_0, 1_1) 
               
            
           
           
               
               
            
               
                 C-RNTI DCI 
                 resource allocation (RB, or port,  
               
            
           
           
               
               
               
            
               
                   
                   
                 SLIV by DCI0_0, 0_1, 1_0, 1_1) 
               
               
                   
               
            
           
         
       
     
     As illustrated in Table 1, the first device  110  may indicate the special scheduling information in a radio resource control (RRC) message, a medium access control-control element (MAC-CE), downlink control information (DCI), dedicated DCI or the like. Correspondingly, the second device  120  may obtain the special scheduling information from these signaling messages. As similar to the NR system, resource allocation is used to indicate any of time domain resources such as the starting and duration of allocated symbols in a slot (SLIV), frequency domain resources such as a number of resource blocks (RB), and spatial domain resources such as a number of antenna ports. Periodicity indication is to configure a period where a slot format pattern is indicated for available downlink/uplink transmission for backhaul/access links. The time domain granularity of slot format pattern can be slot-based or non-slot based in NR system. In this way, the special scheduling may be flexibly performed according to practical implementation and design requirements. Two example embodiments of these methods will be first described with reference to  FIGS. 9A and 9B . 
       FIG. 9A  shows an example of activation and deactivation of special scheduling with specific signaling in accordance with some embodiments of the present disclosure. As shown, the special transmission may be activated at  905  by a first CS-RNTI DCI  910 . The specific transmission resources for the special transmission may be indicated in the first CS-RNTI DCI  910  and may be valid in the time period between  905  and  915 . 
     At  915 , the specific transmission resources for the special transmission may be reconfigured by a second CS-RNTI DCI  920 . For example, more RBs may be configured for the special transmission. The configuration indicated by the second CS-RNTI DCI  920  may be valid in the time period between  915  and  925 . 
     At  925 , the specific transmission resources for the special transmission may be reconfigured by a third CS-RNTI DCI  930 . For example, different antenna ports may be configured for the special transmission. The configuration indicated by the third CS-RNTI DCI  930  may be valid in the time period between  925  and  935 . At  935 , the special transmission may be deactivated, for example, as instructed in the third CS-RNTI DCI  930  or in a further CS-RNTI DCI. 
       FIG. 9B  shows another example of activation and deactivation of special scheduling with specific signaling in accordance with some embodiments of the present disclosure.  FIG. 9B  is similar to  FIG. 9A , with the difference in that the specific transmission resources are configured through MAC-CEs or group-common (GC) DCIs such as INT-DCIs instead of CS-RNTI DCIs. 
     As shown, a first MAC-CE or GC DCI  940 , a second MAC-CE or GC DCI  950 , and a third MAC-CE or GC DCI  960  are transmitted at  945 ,  955 , and  965 , respectively, each selecting one resource allocation from a set of more than one resource allocations configured by the RRC. The special transmission is activated at  945  and deactivated at  975 . The configurations of transmission resources for the special transmission indicated by the first MAC-CE or GC DCI  940 , the second MAC-CE or GC DCI  950 , and the third MAC-CE or GC DCI  960  are valid in the time period between  945  and  955 , the time period between  955  and  965 , and the time period between  955  and  965 , respectively. 
     As an example of the “All RRC configured” method in Table 1, a semi-static configuration can be configured for special transmission. This can be achieved by an RRC configured grant field in an RRC message, as shown in below Table 2. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 2 
               
               
                   
                   
               
               
                   
                 RRC configured grant Field 
                 Usage in special scheduling 
               
               
                   
                   
               
             
            
               
                   
                 cg-DMRS-Configuration 
                 DMRS pattern configuration 
               
               
                   
                 periodicity 
                 A period with indicated slot 
               
               
                   
                   
                 format 
               
               
                   
                 timeDomainOffset 
                 Offset of a resource with 
               
               
                   
                   
                 respect to SFN = 0 in time 
               
               
                   
                   
                 domain 
               
               
                   
                 timeDomainAllocation 
                 startSymbolAndLength in a 
               
               
                   
                   
                 slot (SLIV) 
               
               
                   
                 frequencyDomainAllocation 
                 Frequency resource 
               
               
                   
                   
                 allocation (RB) 
               
               
                   
                 antennaPort 
                 Antenna ports allocation 
               
               
                   
                 dmrs-SeqInitialization 
                 For the seed of DMRS-RS 
               
               
                   
                   
               
            
           
         
       
     
     As an example of the “RRC+MAC-CE or DCI” method in Table 1, the GC DCI and the MAC-CE may be used together with a RRC message to indicate the special scheduling information. An example of the GC DCI for this purpose is shown in below Table 3. 
     
       
         
           
               
             
               
                 TABLE 3 
               
             
            
               
                   
               
               
                 GC DCI 
               
            
           
           
               
               
               
            
               
                 DCI format 
                 Field 
                 Usage in special scheduling 
               
               
                   
               
               
                 DCI 2_1 
                 Indicator for access link 
                 “0” = backhaul link;  
               
               
                   
                   
                 “1” = access link 
               
               
                   
                 bitmap 
                 all “0” = deactivation 
               
               
                   
                   
                 any of “1” = activation or 
               
               
                   
                   
                 selection 
               
               
                   
               
            
           
         
       
     
     An example of the MAC-CE for this purpose is shown in below Table 4. 
     
       
         
           
               
             
               
                 TABLE 4 
               
             
            
               
                   
               
               
                 MAC-CE 
               
            
           
           
               
               
               
            
               
                   
                 field 
                 Usage in special scheduling 
               
               
                   
                   
               
               
                   
                 LGID 
                 Logical channel ID 
               
               
                   
                 bitmap 
                 all “0” = deactivation 
               
               
                   
                   
                 any of “1” = activation or 
               
               
                   
                   
                 selection 
               
               
                   
                   
               
            
           
         
       
     
     As an example of “RRC+DCI” or “C-RNTI/CS-RNTI DCI” method in Table 1, below Table 5 shows an example of special scheduling by DL-DCI. 
     
       
         
           
               
               
             
               
                 TABLE 5 
               
             
            
               
                   
               
               
                   
                 Usage in  
               
               
                   
                 special scheduling 
               
            
           
           
               
               
               
            
               
                   
                   
                 Special value  
               
            
           
           
               
               
            
               
                 BL DL-DCI Field 
                 reserved for 
               
               
                 (C-RNTI, CS-RNTI) 
                 indicating activation  
               
            
           
           
               
               
               
            
               
                 Indicator 
                 NDI, MCS, RV,  
                 and deactivation of  
               
               
                 for special transmission 
                 HARQ, DAT 
                 special transmission 
               
               
                   
               
               
                 DCI1_0 
                 Frequency domain  
                 Frequency domain  
               
               
                 (RB-level RA) 
                 resource assignment 
                 resource assignment 
               
               
                   
                 Time domain  
                 Time domain resource 
               
               
                   
                 resource assignment 
                   
               
               
                   
                 TPC command for  
                 Power coordination  
               
               
                   
                 PUCCH 
                 between backhaul and  
               
               
                   
                   
                 access links 
               
               
                 DCI1_1 
                 Carrier indicator 
                 Carrier indicator 
               
               
                 (RB and port-level RA) 
                 Bandwidth part  
                 Bandwidth part  
               
               
                   
                 indicator 
                 indicator 
               
               
                   
                 Frequency domain  
                 Frequency domain  
               
               
                   
                 resource assignment 
                 resource assignment 
               
               
                   
                 Time domain 
                 Time domain resource 
               
               
                   
                 resource assignment 
                 assignment 
               
               
                   
                 TPC command for  
                 Power coordination  
               
               
                   
                 PUCCH 
                 between backhaul  
               
               
                   
                   
                 and access links 
               
               
                   
                 Antenna ports 
                 Antenna ports 
               
               
                   
                 DMRS sequence 
                 DMRS sequence 
               
               
                   
                 initialization 
                 initialization 
               
               
                   
                 VRB to PRB 
                 VRB to PRB 
               
               
                   
               
            
           
         
       
     
     In Table 5, an example of indicator for activation of the special transmission in the DCI may be NDI=0; DAI=0; and MCS=26; RV=01. An example of indicator for deactivation of the special transmission in the DCI may be NDI=0; DAI=0; and MCS=26; RV=01; HARQ=0000. It is understood that the specific values for these fields are merely examples, without any limitation on the present disclosure. Other examples are also possible. Also, it is noted that, regarding the field of “Antenna ports” as shown in Table 5, the maximum rank is 8 and possible non-transparent SU scheduling may use up to 12 DMRS ports. 
     Below Table 6 shows an example of the RRC configured Field, which may be used together with the example of DL-DCI for special scheduling as shown in Table 5. 
     
       
         
           
               
             
               
                 TABLE 6 
               
               
                   
               
               
                 RRC configured Field 
               
               
                   
               
             
            
               
                 cg-DMRS-Configuration 
               
               
                 Periodicity if for CS-RNTI 
               
               
                   
               
            
           
         
       
     
     As another example of “RRC+DCI” method in Table 1, below Table 7 shows an example of special scheduling by UL-DCI. 
     
       
         
           
               
               
             
               
                 TABLE 7 
               
             
            
               
                   
               
               
                   
               
               
                 BL UL-DCI Field 
                   
               
               
                 (C-RNTI, CS-RNTI) 
                 Usage in special scheduling 
               
            
           
           
               
               
               
            
               
                 Indicator 
                   
                 Special value for activation 
               
               
                 for special  
                 NDI, MCS, RV,  
                 and deactivation of special 
               
               
                 transmission 
                 HARQ, DAT 
                 transmission 
               
               
                   
               
               
                 DCI0_0 
                 Frequency domain  
                 Frequency domain resource 
               
               
                 (RB-level RA) 
                 resource assignment 
                 assignment 
               
               
                   
                 Time domain resource 
                 Time domain resource 
               
               
                   
                 assignment 
                 assignment 
               
               
                   
                 TPC command for 
                 Power coordination between 
               
               
                   
                 scheduled PUSCH 
                 backhaul and access links 
               
               
                 DCI0_1 
                 Carrier indicator 
                 Carrier indicator 
               
               
                 (RB and port  
                 Bandwidth part indicator 
                 Bandwidth part indicator 
               
               
                 level RA) 
                 Frequency domain  
                 Frequency domain resource 
               
               
                   
                 resource assignment 
                 assignment 
               
               
                   
                 Time domain resource 
                 Time domain resource 
               
               
                   
                 assignment 
                 assignment 
               
               
                   
                 TPC command for 
                 Power coordination between 
               
               
                   
                 scheduled PUSCH 
                 backhaul and access links 
               
               
                   
                 SRS resource 
                 DL/UL DMRS association 
               
               
                   
                 indicator/TMPI 
                   
               
               
                   
                 Antenna ports 
                   
               
               
                   
                 DMRS sequence 
                 DMRS sequence 
               
               
                   
                 initialization 
                 initialization 
               
               
                   
                 VRB to PRB 
                 VRB to PRB 
               
               
                   
               
            
           
         
       
     
     In Table 7, the indicator for special transmission may be the same as that in Table 5. As shown in Table 7, the available antenna ports indicated by the field of “Antenna ports” and “SRS resource indicator/TMPI” may be different from that can be indicated in the DL-DCI as shown in Table 5. Thus, when a UL-DCI for a backhaul link is reused to be as a DL-DCI indication for an access link, the DMRS indications in the “Antenna ports” field in the UL-DCI for the backhaul link may need to be converted to be DMRS indications in the “Antenna ports” field in the DL-DCI for the access link. This conversion may also be called as a DL/UL DMRS association in the context of the present disclosure. 
     Below Table 8 shows an example of a DL/UL DMRS association. In this example, the left part of the table is from DCI format 1_1 as specified in 3GPP specifications TS38.212V15.0.2, and the right part of the table is from DCI format 0_1 as specified in 3GPP specifications TS38.212V15.0.2. It is to be understood that this combined Table 8 is merely an example without any limitation on the present disclosure. In other embodiments, the DL/UL DMRS association may involve any other suitable DCI formats 
     
       
         
           
               
             
               
                 TABLE 8 
               
             
            
               
                   
               
               
                 ▪Antenna port(s) (1000 + DMRS port), dmrs-Type = 1, maxLength = 2     
               
               
                      
               
            
           
           
               
               
            
               
                 ▪PDSCH 
                 PUSCH 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                   
                 Number of 
                   
                   
                   
                 Number of 
                   
                   
                   
               
               
                   
                 DMRS CDM 
                   
                 Number of 
                   
                 DMRS CDM 
                   
                 Number of 
                   
               
               
                   
                 group(s) 
                 DMRS 
                 front-load 
                   
                 group(s) 
                 DMRS 
                 front-load 
                      
               
               
                 ▪Value     
                 without data     
                 port(s)     
                 symbols     
                 Value     
                 without data     
                 port(s)     
                 symbols     
                      
               
               
                   
               
               
                  ▪ 0     
                 1     
                 0     
                 1     
                 0     
                 1     
                 0, 1     
                 1     
                      
               
               
                  ▪ 1     
                 1     
                 1     
                 1     
                 1     
                 2     
                 0, 1     
                 1     
                      
               
               
                  ▪ 2     
                 1     
                 0, 1     
                 1     
                 2     
                 2     
                 2, 3     
                 1     
                      
               
               
                  ▪ 3     
                 2     
                 0     
                 1     
                 3     
                 2     
                 0, 2     
                 1     
                      
               
               
                  ▪ 4     
                 2     
                 1     
                 1     
                 4     
                 2     
                 0, 1     
                 2     
                      
               
               
                  ▪ 5     
                 2     
                 2     
                 1     
                 5     
                 2     
                 2, 3     
                 2     
                      
               
               
                  ▪ 6     
                 2     
                 3     
                 1     
                 6     
                 2     
                 4, 5     
                 2     
                      
               
               
                  ▪ 7     
                 2     
                 0, 1     
                 1     
                 7     
                 2     
                 6, 7     
                 2     
                      
               
               
                  ▪ 8     
                 2     
                 2, 3     
                 1     
                 8     
                 2     
                 0, 4     
                 2     
                      
               
               
                  ▪ 9     
                 2     
                 0-2     
                 1     
                 9     
                 2     
                 2, 6     
                 2     
                      
               
               
                 ▪ 10     
                 2     
                 0-3     
                 1     
                 10-15     
                 Reserved     
                 Reserved     
                 Reserved     
                      
               
               
                 ▪ 11     
                 2     
                 0, 2     
                 1     
                      
                      
                      
                      
                      
               
               
                 ▪ 20     
                 2     
                 0, 1     
                 2     
                      
                      
                      
                      
                      
               
               
                 ▪ 21     
                 2     
                 2, 3     
                 2     
                      
                      
                      
                      
                      
               
               
                 ▪ 22     
                 2     
                 4, 5     
                 2     
                      
                      
                      
                      
                      
               
               
                 ▪ 23     
                 2     
                 8, 7     
                 2     
                      
                      
                      
                      
                      
               
               
                 ▪ 24     
                 2     
                 0, 4     
                 2     
                      
                      
                      
                      
                      
               
               
                 ▪ 25     
                 2     
                 2, 6     
                 2     
                      
                      
                      
                      
                      
               
               
                   
               
               
                      
               
            
           
         
       
     
     As shown in Table 8, each UL DMRS indication for the backhaul link may be mapped to a DL DMRS indication for the access link in a one-to-one manner. For example, the first row of the “PUSCH” on the right, that is, value 0 indicating “1, (0,1), 1” may be mapped to the third row of the “PDSCH” on the left, that is, value 2 indicating the same “1, (0,1), 1.” Similarly, other values in the “PUSCH” on the right can be mapped to the values in the “PDSCH” on the left in a one-to-one manner. 
     As an example of “C-RNTI/CS-RNTI DCI” method in Table 1, a new DCI format may be designed for both of the first data transmission (denoted as S1) and the second data transmission (denoted as S2). An example of this kind of new DCI format is shown in Table 9 as below. It is noted that two sets of DMRS ports are indicated and there are at least two transmission blocks (TBs) in a PUSCH. 
     
       
         
           
               
               
               
               
               
             
               
                 TABLE 9 
               
             
            
               
                   
               
               
                   
                   
                   
                   
                 Usage in 
               
            
           
           
               
               
            
               
                 BL DCI Field 
                 special 
               
               
                 (C-RNTI, CS-RNTI) 
                 scheduling 
               
               
                   
               
            
           
           
               
               
               
            
               
                 RB and 
                 Carrier indicator 
                 Both for S1 
               
            
           
           
               
               
               
               
               
            
               
                 port-level  
                   
                   
                   
                 and S2 
               
            
           
           
               
               
               
            
               
                 RA 
                 Bandwidth part indicator 
                 Both for S1 
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                   
                   
                 and S2 
               
            
           
           
               
               
               
            
               
                   
                 Frequency domain resource assignment 
                 Both for S1 
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                   
                   
                 and S2 
               
            
           
           
               
               
               
            
               
                   
                 Time domain resource assignment 
                 Both for S1 
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                   
                   
                 and S2 
               
            
           
           
               
               
               
            
               
                   
                 TPC command for scheduled PUSCH 
                 Both for S1 
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                   
                   
                 and S2 
               
            
           
           
               
               
               
               
            
               
                   
                 DMRS set 1 
                 SRS resource indicator/TMPI 
                 For S1 if 
               
               
                   
                   
                 Antenna ports 
                 configured 
               
               
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                 Option 1 
                 Option 2 
                   
               
               
                   
               
               
                   
                 DMRS set 2 
                 SRS resource 
                 Or DL 
                 For S2 if 
               
               
                   
                   
                 indicator/TMPI 
                 DMRS 
                 configured 
               
               
                   
                   
                 Antenna ports 
                 Antenna 
                   
               
               
                   
                   
                   
                 ports 
               
               
                   
               
            
           
           
               
               
               
            
               
                   
                 DMRS sequence initialization 
                 Both for S1 
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                   
                   
                 and S2 
               
            
           
           
               
               
               
            
               
                   
                 VRB to PRB 
                 Both for S1 
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                   
                   
                 and S2 
               
            
           
           
               
               
               
            
               
                   
                 Others 
                 For S1 
               
               
                   
               
            
           
         
       
     
     In some embodiments, the special scheduling information may be transmitted with a compact DCI, which may be specially designed for the special scheduling. An example of such a compact DCI is shown as below in Table 10. In can be seen that, the compact DCI may only include several necessary fields for the special scheduling, and may not include other fields which are included in existing DCI formats but are unnecessary for the special scheduling. 
     
       
         
           
               
             
               
                 TABLE 10 
               
               
                   
               
               
                 Special Scheduling 
               
               
                 (C-RNTI, CS-RNTI DCI based DCI Field) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 Field 
                 Indication for special transmission 
               
               
                   
                   
                 Frequency domain resource assignment 
               
               
                   
                   
                 Time domain resource assignment 
               
            
           
           
               
               
               
               
            
               
                   
                   
                 Others 
                 Antenna Ports 
               
               
                   
                   
                   
                 TPC commands 
               
               
                   
                   
                   
                 TCI states 
               
               
                   
                   
               
            
           
         
       
     
     In some embodiments, the special scheduling may be based on a slot level. In this event, there may be a scheduling period, for example, specified by a RRC message. The scheduling period may be divided into slots, each of which may be allocated to a backhaul link or an access link and may be used for uplink transmission or downlink transmission. 
     In such embodiments, the special scheduling information may have a first field to indicate whether a particular slot is to be used for a backhaul link or an access link. Additionally, the special scheduling information may have a second field to indicate a DL/UL slot bitmap if the particular slot is allocated to the access link. In contrast, if the particular slot is allocated to the backhaul link, the second field may be omitted, and thus the signaling overhead may be reduced. Table 11 as below shows an example of such slot-level special scheduling signaling. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 11 
               
               
                   
                   
               
               
                   
                 BL Special Scheduling 
                   
               
               
                   
                 (GC DCI Field) 
                 Value 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                   
                 Field 
                 Indication for special transmission 
                 “0” = backhaul link;  
               
               
                   
                   
                   
                 “1” = access link 
               
               
                   
                   
                 Access link DL/UL slot format 
                 bitmap 
               
               
                   
                   
               
            
           
         
       
     
       FIG. 10  shows a flowchart of an example method  1000  in accordance with some embodiments of the present disclosure. The method  1000  can be implemented by a device, such as the first device  110  as shown in  FIG. 1 . For ease of illustration, example embodiments of the method  1000  will be described with reference to  FIG. 1 . 
     At  1010 , the first device  110  determines a first set of transmission resources related to first data transmission between the first device  110  and a second device operating in a half-duplex manner as a relay between the first device  110  and a third device. 
     At  1020 , the first device  110  transmits to the second device scheduling information indicating the first set of transmission resources, such that the second device determines, based on the first set of transmission resources, a second set of transmission resources to be used for second data transmission between the second device and the third device. 
     In some embodiments, determining the first set of transmission resources may comprise: determining a set of transmission resources to be used for the first data transmission as the first set of transmission resources; or determining a set of transmission resources not to be used for the first data transmission as the first set of transmission resources. 
     In some embodiments, the method  1000  may further comprise: in response to the second data transmission being transmission from the second device to the third device, transmitting to the second device further scheduling information indicating a third set of transmission resources to be used for transmission from the second device to the first device, the third set of transmission resources comprising same time and frequency resources as and a different spatial resource from the second set of transmission resources; or indicating the third set of transmission resources in the scheduling information. 
     In some embodiments, the method  1000  may further comprise at least one of: in response to receiving from the second device a scheduling request for requesting the first device to schedule the first set of transmission resources, determining the first set of transmission resources; and in response to receiving from the second device information indicating that the second set of transmission resources is insufficient for the second data transmission, transmitting to the second device updated first scheduling information indicating an updated first set of transmission resources, which results in an updated second set of transmission resources comprising more transmission resources than the second set of transmission resources. 
     In some embodiments, the method  1000  may further comprise: obtaining a first path loss estimate of a first communication link between the first device and the second device; requesting, from the second device, a second path loss estimate of a second communication link between the second device and the third device; receiving the second path loss estimate from the second device; determining, based on at least one of the first and second path loss estimates, a power control for transmission from the second communication to the third device; and indicating the determined power control in the scheduling information. 
     In some embodiments, the method  1000  may further comprise: receiving from the second device a power coordination request for requesting the first device to adjust transmission power of transmission from the first device to the second device; in response to determining that the transmission power is to be adjusted, transmitting to the second device confirmation for the power coordination request; and transmitting to the second device with the adjusted power. 
     In some embodiments, the method  1000  may further comprise: receiving from the second device confirmation for the scheduling information. 
     In some embodiments, the method  1000  may further comprise: transmitting to the second device a deactivation indication for deactivating the scheduling information; and receiving from the second device confirmation for the deactivation indication. 
     In some embodiments, transmitting the scheduling information may comprise: indicating the scheduling information in at least one of a radio resource control (RRC) message, a medium access control-control element (MAC-CE), downlink control information (DCI), and dedicated DCI. 
       FIG. 11  shows a flowchart of another example method  1100  in accordance with some embodiments of the present disclosure. The method  1100  can be implemented by a device, such as the second device  120  as shown in  FIG. 1 . For ease of illustration, example embodiments of the method  1100  will be described with reference to  FIG. 1 . 
     At  1110 , the second device  120 , which operates in a half-duplex manner as a relay between a first device and a third device, receives from the first device first scheduling information indicating a first set of transmission resources related to first data transmission between the first device and the second device  120 . 
     At  1120 , the second device  120  determines, based on the first set of transmission resources, a second set of transmission resources to be used for second data transmission between the second device  120  and the third device. 
     At  1130 , the second device  120  transmits to the third device second scheduling information indicating the second set of transmission resources. 
     In some embodiments, determining the second set of transmission resources may comprise: in response to the first set of transmission resources being a set of transmission resources to be used for the first data transmission, determining a complementary set of the first set of transmission resources with respect to a universal set of all available transmission resources; or in response to the first set of transmission resources being a set of transmission resources not to be used for the first data transmission, determining a subset of the first set of transmission resources. 
     In some embodiments, the method  1100  may further comprise: determining, from the first scheduling information or further scheduling information from the first device, a third set of transmission resources to be used for transmission from the second device to the first device, the third set of transmission resources comprising same time and frequency resources as and a different spatial resource from the second set of transmission resources; and transmitting to the first device using the third set of transmission resources and to the third device using the second set of transmission resources. 
     In some embodiments, the method  1100  may further comprise at least one of: transmitting to the first device a scheduling request for requesting the first device to schedule the first set of transmission resources; and in response to determining that the second set of transmission resources is insufficient for the second data transmission, transmitting to the first device information indicating that the second set of transmission resources is insufficient. 
     In some embodiments, the method  1100  may further comprise: in response to receiving from the first device a request for requesting a path loss estimate of a communication link between the second device and the third device, transmitting the path loss estimate to the first device; obtaining, from the scheduling information, a first power control for transmission from the second communication to the third device; and applying the first power control to the transmission from the second communication to the third device. 
     In some embodiments, the method  1100  may further comprise: transmitting to the first device a power coordination request for requesting the first device to adjust transmission power of transmission from the first device to the second device; in response to receiving from the first device confirmation for the power coordination request, indicating a second power control in the second scheduling information; and receiving from the first device with the adjusted power and from the third device with power under the second power control. 
     In some embodiments, the method  1100  may further comprise: in response to receiving the first scheduling information, transmitting to the first device confirmation for the first scheduling information. 
     In some embodiments, the method  1100  may further comprise: receiving from the first device a deactivation indication for deactivating the first scheduling information; and transmitting to the first device confirmation for the deactivation indication. 
     In some embodiments, receiving the first scheduling information may comprise: obtaining the first scheduling information from at least one of a radio resource control (RRC) message, a medium access control-control element (MAC-CE), downlink control information (DCI), and dedicated DCI. 
       FIG. 12  is a simplified block diagram of a device  1200  that is suitable for implementing some embodiments of the present disclosure. The device  1200  can be considered as a further example embodiment of the first, second, and third devices  110 ,  120 , and  130  as shown in  FIG. 1 . Accordingly, the device  1200  can be implemented at or as at least a part of the first, second, and third devices  110 ,  120 , and  130 . 
     As shown, the device  1200  includes a processor  1210 , a memory  1220  coupled to the processor  1210 , a suitable transmitter (TX) and receiver (RX)  1240  coupled to the processor  1210 , and a communication interface coupled to the TX/RX  1240 . The memory  1220  stores at least a part of a program  1230 . The TX/RX  1240  is for bidirectional communications. The TX/RX  1240  has at least one antenna to facilitate communication, though in practice an Access Node mentioned in this application may have several ones. The communication interface may represent any interface that is necessary for communication with other network elements, such as X2 interface for bidirectional communications between eNBs, S1 interface for communication between a Mobility Management Entity (MME)/Serving Gateway (S-GW) and the eNB, Un interface for communication between the eNB and a relay node (RN), or Uu interface for communication between the eNB and a terminal device. 
     The program  1230  is assumed to include program instructions that, when executed by the associated processor  1210 , enable the device  1200  to operate in accordance with the embodiments of the present disclosure, as discussed herein with reference to  FIG. 10 or 11 . The embodiments herein may be implemented by computer software executable by the processor  1210  of the device  1200 , or by hardware, or by a combination of software and hardware. The processor  1210  may be configured to implement various embodiments of the present disclosure. Furthermore, a combination of the processor  1210  and memory  1220  may form processing means  1250  adapted to implement various embodiments of the present disclosure. 
     The memory  1220  may be of any type suitable to the local technical network and may be implemented using any suitable data storage technology, such as a non-transitory computer readable storage medium, semiconductor based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory, as non-limiting examples. While only one memory  1220  is shown in the device  1200 , there may be several physically distinct memory modules in the device  1200 . The processor  1210  may be of any type suitable to the local technical network, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on multicore processor architecture, as non-limiting examples. The device  1200  may have multiple processors, such as an application specific integrated circuit chip that is slaved in time to a clock which synchronizes the main processor. 
     The components included in the apparatuses and/or devices of the present disclosure may be implemented in various manners, including software, hardware, firmware, or any combination thereof. In one embodiment, one or more units may be implemented using software and/or firmware, for example, machine-executable instructions stored on the storage medium. In addition to or instead of machine-executable instructions, parts or all of the units in the apparatuses and/or devices may be implemented, at least in part, by one or more hardware logic components. For example, and without limitation, illustrative types of hardware logic components that can be used include Field-programmable Gate Arrays (FPGAs), Application-specific Integrated Circuits (ASICs), Application-specific Standard Products (ASSPs), System-on-a-chip systems (SOCs), Complex Programmable Logic Devices (CPLDs), and the like. 
     Generally, various embodiments of the present disclosure may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device. While various aspects of embodiments of the present disclosure are illustrated and described as block diagrams, flowcharts, or using some other pictorial representation, it will be appreciated that the blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof. 
     The present disclosure also provides at least one computer program product tangibly stored on a non-transitory computer readable storage medium. The computer program product includes computer-executable instructions, such as those included in program modules, being executed in a device on a target real or virtual processor, to carry out the process or method as described above with reference to any of  FIGS. 5 and 6 . Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, or the like that perform particular tasks or implement particular abstract data types. The functionality of the program modules may be combined or split between program modules as desired in various embodiments. Machine-executable instructions for program modules may be executed within a local or distributed device. In a distributed device, program modules may be located in both local and remote storage media. 
     Program code for carrying out methods of the present disclosure may be written in any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the program codes, when executed by the processor or controller, cause the functions/operations specified in the flowcharts and/or block diagrams to be implemented. The program code may execute entirely on a machine, partly on the machine, as a stand-alone software package, partly on the machine and partly on a remote machine or entirely on the remote machine or server. 
     The above program code may be embodied on a machine readable medium, which may be any tangible medium that may contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. The machine readable medium may be a machine readable signal medium or a machine readable storage medium. A machine readable medium may include but not limited to an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the machine readable storage medium would include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. 
     Further, while operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Likewise, while several specific embodiment details are contained in the above discussions, these should not be construed as limitations on the scope of the present disclosure, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable sub-combination. 
     Although the present disclosure has been described in language specific to structural features and/or methodological acts, it is to be understood that the present disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.