Patent Publication Number: US-2022225219-A1

Title: Enhanced admission control in integrated access and backhaul (iab)

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application claims benefit of and priority to U.S. Provisional Application No. 63/135,234, filed Jan. 8, 2021 which is hereby assigned to the assignee hereof and hereby expressly incorporated by reference herein in its entirety as if fully set forth below and for all applicable purposes. 
    
    
     INTRODUCTION 
     Aspects of the present disclosure relate to wireless communications, and more particularly, to techniques for admission control in an Integrated Access and Backhaul (IAB) network or other type of network. 
     Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, broadcasts, etc. These wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, etc.). Examples of such multiple-access systems include 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) systems, LTE Advanced (LTE-A) systems, code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems, to name a few. 
     In some examples, a wireless multiple-access communication system may include a number of base stations (BSs), which are each capable of simultaneously supporting communication for multiple communication devices, otherwise known as user equipments (UEs). In an LTE or LTE-A network, a set of one or more base stations may define an eNodeB (eNB). In other examples (e.g., in a next generation, a new radio (NR), or 5G network), a wireless multiple access communication system may include a number of distributed units (DUs) (e.g., edge units (EUs), edge nodes (ENs), radio heads (RHs), smart radio heads (SRHs), transmission reception points (TRPs), etc.) in communication with a number of central units (CUs) (e.g., central nodes (CNs), access node controllers (ANCs), etc.), where a set of one or more DUs, in communication with a CU, may define an access node (e.g., which may be referred to as a BS, next generation NodeB (gNB or gNodeB), TRP, etc.). A BS or DU may communicate with a set of UEs on downlink (DL) channels (e.g., for transmissions from a BS or DU to a UE) and uplink (UL) channels (e.g., for transmissions from a UE to a BS or DU). 
     These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level. New radio (e.g., 5G NR) is an example of an emerging telecommunication standard. NR is a set of enhancements to the LTE mobile standard promulgated by 3GPP. NR is designed to better support mobile broadband Internet access by improving spectral efficiency, lowering costs, improving services, making use of new spectrum, and better integrating with other open standards using OFDMA with a cyclic prefix (CP) on the DL and on the UL. To these ends, NR supports beamforming, multiple-input multiple-output (MIMO) antenna technology, and carrier aggregation. 
     As the demand for mobile broadband access continues to increase, there exists a need for further improvements in NR and LTE technology. These improvements should be applicable to other multi-access technologies and the telecommunication standards that employ these technologies. 
     SUMMARY 
     The systems, methods, and devices of the disclosure each have several aspects, no single one of which is solely responsible for its desirable attributes. After considering this discussion, and particularly after reading the section entitled “Detailed Description” one will understand how the features of this disclosure provide advantages that include improved communications between wireless communication devices. Aspects of the present disclosure provide techniques for admission control in a network (e.g., an Integrated Access and Backhaul (IAB) network). 
     Certain aspects of the subject matter described in this disclosure can be implemented in a method for wireless communication by a first base station (BS). The method generally includes sending, to an IAB-node, a request message requesting to setup or modify a context for a child node of a first logical IAB-DU of the IAB-node, wherein the first logical IAB-DU is associated with the first BS, sending an indication to the IAB-node that the child node is currently served by the IAB-node at a second logical IAB-DU of the IAB-node, wherein the second logical IAB-DU is associated with a second BS, and receiving an acknowledgment message from the IAB-node based at least in part on the indication to the IAB-node. 
     Certain aspects of the subject matter described in this disclosure can be implemented in a method for wireless communication by an IAB node. The method generally includes receiving, from a first BS, a request message to setup or modify a context for a child node of a first logical IAB-DU of the IAB-node, wherein the first logical IAB-DU is associated with the first BS, receiving, from the first BS, an indication that the child node is currently served by the IAB-node at a second logical IAB-DU of the IAB-node, wherein the second logical IAB-DU is associated with a second BS, performing admission control based at least in part on the indication, and sending an acknowledgment message to the first BS based on the admission control. 
     Certain aspects of the subject matter described in this disclosure can be implemented in an apparatus for wireless communication by a first BS. The apparatus generally includes: a memory; and one or more processors coupled to the memory, the memory and the one or more processors being configured to: send, to an IAB-node, a request message requesting to setup or modify a context for a child node of a first logical IAB-DU of the IAB-node, wherein the first logical IAB-DU is associated with the first BS, send an indication to the IAB-node that the child node is currently served by the IAB-node at a second logical IAB-DU of the IAB-node, wherein the second logical IAB-DU is associated with a second BS, and receive an acknowledgment message from the IAB-node based at least in part on the indication to the IAB-node. 
     Certain aspects of the subject matter described in this disclosure can be implemented in an apparatus for wireless communication by an IAB node. The apparatus generally includes: a memory; and one or more processors coupled to the memory, the memory and the one or more processors being configured to: receive, from a first BS, a request message to setup or modify a context for a child node of a first logical IAB-DU of the IAB-node, wherein the first logical IAB-DU is associated with the first BS, receive, from the first BS, an indication that the child node is currently served by the IAB-node at a second logical IAB-DU of the IAB-node, wherein the second logical IAB-DU is associated with a second BS, perform admission control based at least in part on the indication, and send an acknowledgment message to the first BS based on the admission control. 
     Certain aspects of the subject matter described in this disclosure can be implemented in an apparatus for wireless communication by a first BS. The apparatus generally includes: means for sending, to an IAB-node, a request message requesting to setup or modify a context for a child node of a first logical IAB-DU of the IAB-node, wherein the first logical IAB-DU is associated with the first BS, means for sending an indication to the IAB-node that the child node is currently served by the IAB-node at a second logical IAB-DU of the IAB-node, wherein the second logical IAB-DU is associated with a second BS, and means for receiving an acknowledgment message from the IAB-node based at least in part on the indication to the IAB-node. 
     Certain aspects of the subject matter described in this disclosure can be implemented in an apparatus for wireless communication by an IAB node. The apparatus generally includes: means for receiving, from a first BS, a request message to setup or modify a context for a child node of a first logical IAB-DU of the IAB-node, wherein the first logical IAB-DU is associated with the first BS, means for receiving, from the first BS, an indication that the child node is currently served by the IAB-node at a second logical IAB-DU of the IAB-node, wherein the second logical IAB-DU is associated with a second BS, means for performing admission control based at least in part on the indication, and means for sending an acknowledgment message to the first BS based on the admission control. 
     Certain aspects of the subject matter described in this disclosure can be implemented in a computer-readable medium having instructions stored thereon to cause a first BS to: send, to an IAB-node, a request message requesting to setup or modify a context for a child node of a first logical IAB-DU of the IAB-node, wherein the first logical IAB-DU is associated with the first BS, send an indication to the IAB-node that the child node is currently served by the IAB-node at a second logical IAB-DU of the IAB-node, wherein the second logical IAB-DU is associated with a second BS, and receive an acknowledgment message from the IAB-node based at least in part on the indication to the IAB-node. 
     Certain aspects of the subject matter described in this disclosure can be implemented in a computer-readable medium having instructions stored thereon to cause an IAB node to: receive, from a first BS, a request message to setup or modify a context for a child node of a first logical IAB-DU of the IAB-node, wherein the first logical IAB-DU is associated with the first BS, receive, from the first BS, an indication that the child node is currently served by the IAB-node at a second logical IAB-DU of the IAB-node, wherein the second logical IAB-DU is associated with a second BS, perform admission control based at least in part on the indication, and send an acknowledgment message to the first BS based on the admission control. 
     To the accomplishment of the foregoing and related ends, the one or more aspects comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the appended drawings set forth in detail certain illustrative features of the one or more aspects. These features are indicative, however, of but a few of the various ways in which the principles of various aspects may be employed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       So that the manner in which the above-recited features of the present disclosure can be understood in detail, a more particular description, briefly summarized above, may be had by reference to aspects, some of which are illustrated in the drawings. It is to be noted, however, that the appended drawings illustrate only certain typical aspects of this disclosure, and the description may admit to other equally effective aspects. 
         FIG. 1  is a block diagram conceptually illustrating an example telecommunications system, in accordance with certain aspects of the present disclosure. 
         FIG. 2  is a block diagram conceptually illustrating a design of an example a base station (BS) and user equipment (UE), in accordance with certain aspects of the present disclosure. 
         FIG. 3  is a diagram illustrating examples of radio access networks, in accordance with certain aspects of the present disclosure. 
         FIG. 4  is a diagram illustrating an example of an integrated access and backhaul (IAB) network architecture, in accordance with various aspects of the disclosure. 
         FIGS. 5A, 5B, and 5C  illustrate example operations for handover of a UE from a source BS to a target BS, in accordance with certain aspects of the present disclosure. 
         FIG. 6  illustrates example operations for migration between central units (CUs), in accordance with certain aspects of the present disclosure. 
         FIG. 7  is a flow diagram illustrating example operations for wireless communication by a BS, in accordance with certain aspects of the disclosure. 
         FIG. 8  is a flow diagram illustrating example operations for wireless communication by an IAB node, in accordance with various aspects of the disclosure. 
         FIG. 9  is a call flow diagram illustrating example operations for handover, in accordance with certain aspects of the present disclosure. 
         FIG. 10  illustrates a communications device that may include various components configured to perform operations for the techniques disclosed herein in accordance with aspects of the present disclosure. 
         FIG. 11  illustrates a communications device that may include various components configured to perform operations for the techniques disclosed herein in accordance with aspects of the present disclosure. 
     
    
    
     To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one aspect may be beneficially utilized on other aspects without specific recitation. 
     DETAILED DESCRIPTION 
     Aspects of the present disclosure provide techniques for admission control for an Integrated Access and Backhaul (IAB) network. For example, a child node (e.g., a user equipment (UE)) may be handed over from a source base station (BS) to a target BS. To do so, an IAB-node may have to determine whether to admit the child node. In some scenarios, the child node may be served by the same IAB-node prior to and after the handover occurs. In some aspects, a target BS may indicate to the IAB-node that the child node is being served by the IAB-node itself, in effect indicating that admission of the child node should not require any additional resources to be allocated for the child node. As a result, the IAB-node may admit the child node and provide an acknowledgement to the target BS accordingly. 
     The following description provides examples, and is not limiting of the scope, applicability, or examples set forth in the claims. Changes may be made in the function and arrangement of elements discussed without departing from the scope of the disclosure. Various examples may omit, substitute, or add various procedures or components as appropriate. For instance, the methods described may be performed in an order different from that described, and various steps may be added, omitted, or combined. Also, features described with respect to some examples may be combined in some other examples. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. In addition, the scope of the disclosure is intended to cover such an apparatus or method which is practiced using other structure, functionality, or structure and functionality in addition to, or other than, the various aspects of the disclosure set forth herein. It should be understood that any aspect of the disclosure disclosed herein may be embodied by one or more elements of a claim. The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any aspect described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects. 
     In general, any number of wireless networks may be deployed in a given geographic area. Each wireless network may support a particular radio access technology (RAT) and may operate on one or more frequencies. A RAT may also be referred to as a radio technology, an air interface, etc. A frequency may also be referred to as a carrier, a subcarrier, a frequency channel, a tone, a subband, etc. Each frequency may support a single RAT in a given geographic area in order to avoid interference between wireless networks of different RATs. In some cases, a 5G NR RAT network may be deployed. 
     Example Wireless Communication Network 
       FIG. 1  illustrates an example wireless communication network  100  in which aspects of the present disclosure may be performed. For example, wireless communication network  100  may include a base station (BS)  110  configured to perform operations  700  of  FIG. 7  and a network entity (e.g., an Integrated Access and Backhaul (IAB)-node) configured to perform operations  800  of  FIG. 8 . 
     As illustrated in  FIG. 1 , wireless communication network  100  may include a number of BSs  110   a - z  (each also individually referred to herein as BS  110  or collectively as BSs  110 ) and other network entities. A BS  110  may provide communication coverage for a particular geographic area, sometimes referred to as a “cell”, which may be stationary or may move according to the location of a mobile BS  110 . In some examples, BSs  110  may be interconnected to one another and/or to one or more other BSs or network nodes (not shown) in wireless communication network  100  through various types of backhaul interfaces (e.g., a direct physical connection, a wireless connection, a virtual network, or the like) using any suitable transport network. In the example shown in  FIG. 1 , BSs  110   a ,  110   b  and  110   c  may be macro BSs for the macro cells  102   a ,  102   b  and  102   c , respectively. BS  110   x  may be a pico BS for a pico cell  102   x . BSs  110   y  and  110   z  may be femto BSs for the femto cells  102   y  and  102   z , respectively. A BS  110  may support one or multiple cells. BSs  110  communicate with UEs  120   a - y  (each also individually referred to herein as UE  120  or collectively as UEs  120 ) in wireless communication network  100 . The UEs  120  (e.g.,  20   x ,  120   y , etc.) may be dispersed throughout wireless communication network  100 , and each UE  120  may be stationary or mobile. 
     Wireless communication network  100  may also include relay stations (e.g., relay station  110   r ), also referred to as relays or the like, that receive a transmission of data and/or other information from an upstream station (e.g., a BS  110   a  or a UE  120   r ) and sends a transmission of the data and/or other information to a downstream station (e.g., a UE  120  or a BS  110 ), or that relays transmissions between UEs  120 , to facilitate communication between devices. 
     A network controller  130  may couple to a set of BSs  110  and provide coordination and control for these BSs  110 . Network controller  130  may communicate with BSs  110  via a backhaul. BSs  110  may also communicate with one another (e.g., directly or indirectly) via wireless or wireline backhaul. 
       FIG. 2  illustrates example components  200  of BS  110  and UE  120  (e.g., in wireless communication network  100  of  FIG. 1 ), which may be used to implement aspects of the present disclosure. For example, antennas  252 , processors  266 ,  258 ,  264 , and/or controller/processor  280  of UE  120  and/or antennas  234 , processors  220 ,  230 ,  238 , and/or controller/processor  240  of the BS  110  may be used to perform the various techniques and methods described herein. 
     It should be noted that although  FIG. 2  illustrates UE  120  communicating with a BS  110 , an IAB-node may similarly communicate with a BS (e.g., donor-CU) and each may (e.g., respectively) have similar components as discussed with respect to  FIG. 2 . In other words, an IAB-node may have similar components as UE  120 . The BS may be configured to perform operations  700  of  FIG. 7 , while an IAB-node (or other network entity) may have similar components as UE  120  and may be configured to perform operations  800  of  FIG. 8 . 
     At BS  110 , a transmit processor  220  may receive data from a data source  212  and control information from a controller/processor  240 . The control information may be for the physical broadcast channel (PBCH), physical control format indicator channel (PCFICH), physical hybrid automatic repeat request (HARQ) indicator channel (PHICH), physical downlink control channel (PDCCH), group common PDCCH (GC PDCCH), etc. The data may be for the physical downlink shared channel (PDSCH), etc. Processor  220  may process (e.g., encode and symbol map) the data and control information to obtain data symbols and control symbols, respectively. Transmit processor  220  may also generate reference symbols, such as for the primary synchronization signal (PSS), secondary synchronization signal (SSS), and cell-specific reference signal (CRS). A transmit (TX) multiple-input multiple-output (MIMO) processor  230  may perform spatial processing (e.g., precoding) on the data symbols, the control symbols, and/or the reference symbols, if applicable, and may provide output symbol streams to the modulators (MODs)  232   a - 232   t . Each modulator/demodulator  232  may process a respective output symbol stream (e.g., for orthogonal frequency division multiplexing (OFDM), etc.) to obtain an output sample stream. Each modulator may further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink (DL) signal. DL signals from modulators  232   a - 232   t  may be transmitted via the antennas  234   a - 234   t , respectively. 
     At UE  120 , antennas  252   a - 252   r  may receive DL signals from BS  110  or a parent IAB-node, or a child IAB-node may receive DL signals from a parent IAB-node, and may provide received signals to the demodulators (DEMODs) in transceivers  254   a - 254   r , respectively. Each demodulator may condition (e.g., filter, amplify, downconvert, and digitize) a respective received signal to obtain input samples. Each demodulator may further process the input samples (e.g., for OFDM, etc.) to obtain received symbols. A MIMO detector  256  may obtain received symbols from all the demodulators in transceivers  254   a - 254   r , perform MIMO detection on the received symbols if applicable, and provide detected symbols. A receive processor  258  may process (e.g., demodulate, deinterleave, and decode) the detected symbols, provide decoded data for UE  120  to a data sink  260 , and provide decoded control information to controller/processor  280 . One or more of antennas  252 , demodulators in transceivers  254 , MIMO detector  256 , receive processor  258 , transmit processor  264 , TX MIMO processor  266 , and/or the like may be components within a transceiver of UE  120 . 
     On the UL, at UE  120  or a child IAB-node, a transmit processor  264  may receive and process data (e.g., for the physical uplink shared channel (PUSCH) or the physical sidelink shared channel (PSSCH)) from a data source  262  and control information (e.g., for the physical uplink control channel (PUCCH) or the physical sidelink control channel (PSCCH)) from controller/processor  280 . Transmit processor  264  may also generate reference symbols for a reference signal (RS) (e.g., for the sounding reference signal (SRS)). The symbols from transmit processor  264  may be precoded by a TX MIMO processor  266  if applicable, further processed by the demodulators in transceivers  254   a - 254   r  (e.g., for single carrier-frequency division multiplexing (SC-FDM), etc.), and transmitted to BS  110  or a parent IAB-node. 
     At BS  110  or a parent IAB-node, the UL signals from UE  120  may be received by antennas  234 , processed by modulators  232 , detected by MIMO detector  236  if applicable, and further processed by receive processor  238  to obtain decoded data and control information sent by UE  120 . Receive processor  238  may provide the decoded data to a data sink  239  and the decoded control information to controller/processor  240 . One or more of antennas  234 , demodulators  232 , TX MIMO processor  230 , transmit processor  220 , MIMO detector  236 , receive processor  238 , and/or the like may be components within a transceiver of BS  110 . 
     Controllers/processors  240  and  280  may direct the operation at BS  110  and UE  120 , respectively. Controller/processor  240  and/or other processors and modules at BS  110  may perform or direct the execution of processes for the techniques described herein. Controller/processor  280  and/or other processors and modules at UE  120  may perform or direct the execution of processes for the techniques described herein. Memories  242 ,  282  may store data and program codes for BS  110  and UE  120 , respectively. A scheduler  244  may schedule UEs  120  for data transmission on the DL and/or UL. 
       FIG. 3  is a diagram  300  illustrating examples of radio access networks (RANs), in accordance with certain aspects of the disclosure. 
     As shown by reference number  305 , a traditional (for example, 3G, 4G, LTE) RAN may include multiple BS  310  (for example, access nodes (ANs)), where each BS  310  communicates with a core network via a wired backhaul link  315 , such as a fiber connection. A BS  310  may communicate with a UE  320  via an access link  325 , which may be a wireless link. In certain aspects, a BS  310  shown in  FIG. 3  may correspond to a BS  110  shown in  FIG. 1 . Similarly, a UE  320  shown in  FIG. 3  may correspond to a UE  120  shown in  FIG. 1 . 
     As shown by reference number  330 , a RAN may include a wireless backhaul network. In some aspects or scenarios, a wireless backhaul network may sometimes be referred to as an IAB network. An IAB network may include multiple BS and the BSs may be of differing types or have differing operational characteristics. For example, in certain aspects, an JAB network may have at least one BS that is an anchor BS  335 . Anchor BS  335  may communicates with a core network via a wired backhaul link  340 , such as a fiber connection. Anchor BS  335  may also be referred to as an JAB donor. An IAB donor is an AN with wireline connection to a core network. An IAB node is an AN that relays traffic from/to anchor BS  335  through one or multiple hops. Anchor BSs  335  can be configured to communicate with other types of base stations or other communication devices (e.g. in a radio network or IAB network). 
     The IAB network may also include one or more non-anchor BSs  345 . Non-anchor BSs  345  may be referred to as relay BSs or IAB nodes. Bon-anchor BS  345  may communicate directly with or indirectly with (for example, via one or more other non-anchor BSs  345 ) anchor BS  335  via one or more backhaul links  350  to form a backhaul path to the core network for carrying backhaul traffic. Backhaul link  350  may be a wireless link. Anchor BS(s)  335  or non-anchor BS(s)  345  may communicate with one or more UEs  355  via access links  360 , which may be wireless links for carrying access traffic. In certain aspects, an anchor BS  335  or a non-anchor BS  345  shown in  FIG. 3  may correspond to a BS  110  shown in  FIG. 1 . Similarly, a UE  355  shown in  FIG. 3  may correspond to a UE  120  shown in  FIG. 1 . 
     As shown by reference number  365 , in some aspects, a RAN that includes an IAB network may utilize a variety of spectrum types. For example, an IAB network may utilize a variety of differing radio frequency bands. In a few particular examples and according to certain aspects, millimeter wave (mmW) technology or directional communications can be utilized (for example, beamforming, precoding) for communications between BSs or UEs (for example, between two BSs, between two UEs, or between a BS and a UE). In additional or alternative aspects or examples, wireless backhaul links  370  between BSs may use millimeter waves to carry information or may be directed toward a target BS using beamforming, precoding. Similarly, the wireless access links  375  between a UE and a BS may use millimeter waves or may be directed toward a target wireless node (for example, a UE or a BS). In this way, inter-link interference may be reduced. 
     In some aspects, an IAB network may support a multi-hop network or a multi-hop wireless backhaul. Additionally, or alternatively, each node of an IAB network may use the same radio access technology (for example, 5G/NR). Additionally, or alternatively, nodes of an IAB network may share resources for access links and backhaul links, such as time resources, frequency resources, and spatial resources. Furthermore, various architectures of IAB-nodes or IAB-donors may be supported. 
     In some aspects, an IAB-donor may include a central unit (CU) that configures IAB-nodes that access a core network via the IAB-donor and may include a distributed unit (DU) that schedules and communicates with child nodes of the IAB-donor. 
     In some aspects, an IAB-node may include a mobile termination component (MT) that is scheduled by and communicates with a DU of a parent node, and may include a DU that schedules and communicates with child nodes of the IAB-node. A DU of an IAB-node may perform functions described in connection with BS  110  for that IAB-node, and an MT of an IAB-node may perform functions described in connection with UE  120  for that IAB-node. 
       FIG. 4  is a diagram  400  illustrating an example of an IAB network architecture, in accordance with certain aspects of the present disclosure. As shown in  FIG. 4 , an IAB network may include an IAB-donor  405  that connects to a core network via a wired connection (for example, as a wireline fiber). For example, an Ng interface of an IAB-donor  405  may terminate at a core network. Additionally, or alternatively, IAB donor- 405  may connect to one or more devices of the core network that provide a core access and mobility management function (AMF). In certain aspects, IAB donor- 405  may include a BS  110 , such as an anchor BS  335 , as described above in connection with  FIG. 3 . As shown, IAB-donor  405  may include a CU, which may perform access note controller (ANC) functions or AMF functions. The CU may configure a DU of IAB-donor  405  or may configure one or more IAB nodes  410  (for example, an MT or a DU of IAB node  410 ) that connect to the core network via IAB donor  405 . Thus, a CU of IAB donor  405  may control or configure the entire IAB network that connects to the core network via IAB-donor  405 , such as by using control messages or configuration messages (for example, a radio resource control (RRC) configuration message, an F1 application protocol (F1AP) message). 
     As described above, the IAB network may include IAB-nodes  410  (shown as IAB-nodes  1  through  4 ) that connect to the core network via IAB-donor  405 . As shown, IAB-node  410  may include an MT and may include a DU. The MT of an IAB-node  410  (for example, a child node) may be controlled or scheduled by another IAB-node  410  (for example, a parent node) or by an IAB-donor  405 . The DU of an IAB-node  410  (for example, a parent node) may control or schedule other IAB-nodes  410  (for example, child nodes of the parent node) or UEs  120 . Thus, a DU may be referred to as a scheduling node or a scheduling component, and an MT may be referred to as a scheduled node or a scheduled component. In certain aspects, IAB-donor  405  may include a DU and not an MT. That is, IAB-donor  405  may configure, control, or schedule communications of IAB-nodes  410  or UEs  120 . A UE  120  may include only an MT, and not a DU. That is, communications of a UE  120  may be controlled or scheduled by IAB-donor  405  or an IAB-node  410  (for example, a parent node of UE  120 ). 
     According to certain aspects, certain nodes may be configured to participate in control/scheduling processes. For example in certain aspects, when a first node controls or schedules communications for a second node (for example, when the first node provides DU functions for the second node&#39;s MT), the first node may be referred to as a parent node of the second node, and the second node may be referred to as a child node of the first node. A child node of the second node may be referred to as a grandchild node of the first node. Thus, a DU of a parent node may control or schedule communications for child nodes of the parent node. A parent node may be an IAB-donor  405  or an IAB-node  410 , and a child node may be an IAB-node  410  or a UE  120 . Communications of an MT of a child node may be controlled or scheduled by a parent node of the child node. 
     As further shown in  FIG. 4 , a link between UE  120  and IAB-donor  405 , or between UE  120  and IAB-node  410 , may be referred to as an access link  415 . Each access link  415  may be a wireless access link that provides UE  120  with radio access to a core network via IAB-donor  405 , and potentially via one or more IAB nodes  410 . 
     As further shown in  FIG. 4 , a link between IAB-donor  405  and IAB-node  410 , or between two IAB-nodes  410 , may be referred to as a backhaul link  420 . Each backhaul link  420  may be a wireless backhaul link that provides IAB-node  410  with radio access to a core network via IAB-donor  405 , and potentially via one or more other intermediate IAB-nodes  410 . 
     In certain aspects, a backhaul link  420  may be a primary backhaul link or a secondary backhaul link (for example, a backup backhaul link). In certain aspects, a secondary backhaul link may be used if a primary backhaul link fails, becomes congested, or becomes overloaded. In an IAB network, network resources for wireless communications (for example, time resources, frequency resources, spatial resources) may be shared between access links  415  and backhaul links  420 . 
     As described above, in a typical IAB network, IAB-nodes (for example, non-anchor BSs) are stationary (that is, non-moving). Next generation (5G) wireless networks have stated objectives to provide ultra-high data rate and support wide scope of application scenarios. IAB systems have been studied in 3GPP as one possible solution to help support these objectives. 
     As noted above, in an IAB network, a wireless backhaul solution is adopted to connect cells (e.g., IAB-nodes) to the core network (which uses a wired backhaul). Some attractive characteristics of an IAB network are support for multi-hop wireless backhaul, sharing of the same technology (e.g., NR) and resources (e.g., frequency bands) for both access and backhaul links. 
     There are various possible architectures for IAB-nodes, including layer-2 (L2) and layer-3 (L3) solutions and a particular architecture deployed may depend on what layers of a protocol stack are implemented in the intermediate nodes (e.g., IAB-nodes), for example, L2 relays may implement physical (PHY)/medium access control (MAC)/radio link control (RLC) layers. 
     As described herein, an IAB donor may be an enhanced gNB node with functions to control an IAB-network. A CU may refer to the central entity that controls the entire IAB-network through configuration. The CU holds RRC/packet data convergence protocol (PDCP) layer functions. A DU may be a scheduling node that schedules child nodes of this IAB-donor. The DU holds RLC/MAC/PHY layer functions. 
     An IAB-node is an L2 relay node consisting of MT and DU functions, as described herein. MT is a scheduled node similar to a UE scheduled by its parent IAB-node or IAB-donor. A DU is a scheduling node that schedules child nodes of this IAB-node. 
     Example Admission Control Techniques in an Integrated Access and Backhaul (IAB) Network 
     Certain aspects of the present disclosure are directed to techniques for admission control for an Integrated Access and Backhaul (IAB) network. For example, an IAB-node may determine whether to admit a child node being handed over from a source base station (BS) to a target BS (e.g., in some cases, a source IAB-donor central unit (CU) to a target IAB-donor CU). In some scenarios, the child node may be served by the same IAB-node prior to and after the handover occurs. In some aspects, a target BS may indicate to the IAB-node that the child node is being served by the IAB-node itself. Thus, the IAB-node may know that admission of the child node should not require any additional resources to be allocated for the child node. As a result, the IAB-node may admit the child node and provide an acknowledgement to the target BS accordingly. 
       FIG. 5A  illustrates example operations  500 A for handover of a UE from a source BS to a target BS, in accordance with certain aspects of the present disclosure. Although not shown, there may be some trigger for handover from the source BS to the target BS, such as a measurement report from the UE. As illustrated, the source BS may initiate handover by sending a handover request  502  (e.g., via an Xn interface) to the target BS. 
     The target BS may perform admission control operations at block  504 . For admission control, the target BS may determine whether there are sufficient resources to admit the UE. If so, the target BS may then provide a radio resource control (RRC) configuration to the source BS as part of a handover request acknowledgement  506  (e.g. including a RRC reconfiguration message). 
     The source BS may then provide the RRC configuration  508  to the UE by forwarding the RRC reconfiguration message received in the handover request acknowledgement. The UE may then, at block  510 , switch the RRC connection to the target BS and reply with an RRC reconfiguration complete message  512  to the target BS, as illustrated. The target BS may then send a UE context release message  514  to the source BS to inform the source BS about the success of the handover, allowing the source BS to release the resources reserved for the UE. 
     Certain aspects of the present disclosure are directed to techniques for performing the admission control operations at block  504  (e.g., operations to determine whether there are sufficient resources to serve the UE). In some aspects, each BS may include a CU and a distributed unit (DU), as described with respect to  FIG. 4 . 
       FIGS. 5B and 5C  illustrate example operations  500 B and  500 C, respectively, for performing admission control operations at a target BS, in accordance with certain aspects of the present disclosure. The CU may receive the handover request from the source BS. The CU may then check with the DU to see if there are sufficient resources to serve the UE. To do so, either a context setup procedure may be used, as illustrated in  FIG. 5B , or a context modification procedure may be used, as illustrated in  FIG. 5C . The context setup procedure may be used for an initial UE context setup with the DU, and any subsequent modification to the context for the UE may be performed via the context modification procedure. 
     The context setup or modification request may be used to determine whether the DU is able to provide a particular service for the UE. In other words, the purpose of the UE context setup/modification procedure is to establish/modify the UE context including, among others a signalling radio bearer (SRB), a data radio bearer (DRB), a backhaul (BH) radio link control (RLC) channel, and/or a sidelink (SL) DRB configuration (e.g., for SL communication between UEs). In some aspects, a context for a child node may include a BH RLC channel if the child node is a child IAB-MT or an IAB-node. In some implementations, the UE context setup/modification procedure may use UE-associated signalling. 
     As illustrated in  FIGS. 5B and 5C , the CU may send a UE context setup/modification request  550  to the DU. The DU may then report back to the CU indicating whether the DU is capable of providing services for the UE via a UE context setup/modification response  552 . For example, the DU may report to the CU a list of DRBs/SRBs/SL DRBs successfully established/modified, a list of DRBs/SRBs/SL DRBs that failed to be established/modified, a list of BH RLC CHs successfully established/modified, and a list of BH RLC CHs that failed to be established/modified. In some scenarios, the DU may indicate that the UE context setup/modification has failed. 
       FIG. 6  illustrates example operations  600  for migration between CUs, in accordance with certain aspects of the present disclosure As illustrated in  FIG. 6 , an IAB-node  602  may be serving one or more child nodes, such as, the UE  604  (or another IAB-node in some implementations). While  FIG. 6  illustrates a UE as the child node of IAB-node  602  to facilitate understanding, the child node of IAB-node  602  may be another IAB-node in some implementations. 
     As illustrated, the IAB-node  602  may include an IAB-MT (hereinafter referred to as “MT 1 ”) and an IAB-DU. In some implementations, the IAB-DU of IAB-node  602  may be implemented using multiple logical IAB-DUs, each associated with a different CU. For example, a first logical IAB-DU (hereinafter referred to as “DU 1   a ”) of IAB-node  602  may be associated with and mange communications for a first donor CU (hereinafter referred to as “CUa”), and a second logic IAB-DU (hereinafter referred to as “DU 1   b ”) may be associated with and manage communications for a second donor CU (hereinafter referred to as “Cub”). As used herein, a logical IAB-DU refers to a DU that has its own F1 connection (e.g., DU 1   a  has an F1 connection with CUa while DU 1   b  has an F1 connection with Cub). Logical IAB-DUs may be implemented on the same physical components (e.g., with different software components) or on different physical components. 
     As illustrated, MT 1  may be connected to CUa through a parent DU (hereinafter referred to as “parent DUa”) and connected to CUb through another parent DU (hereinafter referred to as “parent DUb”). While  FIG. 6  shows parent DUa having a direct connection to CUa to facilitate understanding, there may be one or more other IAB-nodes in the link between parent DUa and CUa in some implementations. Similarly, there may be one or more other IAB-nodes in the link between parent DUb and CUb in some implementations. Moreover, while parent DUa and parent DUb are shown as two separate nodes, parent DUa and parent DUb may be two logical DUs of the same node in some implementations, each associated with one of the CUs (e.g., in a case where there are multiple descendant nodes). 
     As illustrated, MT 1  of IAB-node  602  may migrate from CUa to CUb. In some cases, an IAB node (e.g., IAB-node  602 ) may have simultaneous F1 interfaces to two donor-CUs (e.g., CUa and CUb) using separate logical IAB-DUs (e.g., DU 1   a  and DU 1   b ) in the same physical node, as described. CUa may also be referred to as the source CU (e.g., the CU of a source BS), and CUb may also be referred to as the target CU (e.g., the CU of a target BS). F1 connections may use a source or target path depending on path availability. In one example, the IAB-node may have simultaneous connectivity with parent DUa and parent DUb (e.g. via new radio (NR)-dual connectivity (DC), multi-RAT (MR)-DC, dual access protocol stacks (DAPS), or multi-MT), and the UE may have to be migrated from DU 1   a  to DU 1   b.    
     UE  604  may migrate from CUa to CUb (e.g., from a source BS to a target BS). Thus, UE  604  may switch from DU 1   a  to DU 1   b . For instance, CUb may perform a UE context setup procedure with DU 1   b  of the target BS. In other words, DU 1   b  may perform admission control operations as described with respect to  FIG. 5A . In order for DU 1   b  to determine whether to admit UE  604  for the handover, DU 1   b  may be made aware that the incoming UE (e.g., UE  604 ) is presently connected to DU 1   a , and as a result, consume no additional resources at IAB-node  602  since the same physical link will be used after handover. In other words, DU 1   b  may be unaware of UE  604 , and without any signalling to identify UE  604  as a UE that is being currently served by DU 1   a , DU 1   b  might reject the admission of UE  604  (e.g., fail to setup at least part of the UE context). Thus, in some aspects of the present disclosure, CU 1   b  may inform DU 1   b  that UE  604  is currently served by DU 1   a  and that admission of UE  604  consumes no additional resources at the IAB-node  602  since DU 1   a  and DU 1   b  use the same physical resources, and therefore, UE  604  should be admitted for service via DU 1   b  with the new connection to CUb. Descendant IAB-MTs and UEs may have to migrate to donor-CUb in a similar manner. The same operations may apply for migration of a UE of a dual-connected IAB-node. 
     In a first example, DU 1   a  and DU 1   b  may serve different cells with different NR cell global identity (NCGI) or NR cell identity (NCI). A first cell of DU 1   a  and a second cell of DU 1   b  may have the same or different physical cell IDs (PCIs) and frequencies. In the latter case, IAB-node  602  may use different physical resources to serve a child on DU 1   a  versus DU 1   b.    
     In a second example, DU 1   a  and DU 1   b  of IAB-node  602  may not be physically collocated. Serving UE  604  on DUb may consume different resources than serving UE  604  on DUa. Thus, the physical implementation/proximity of DUa and DUb is an additional factor for admission control at DU 1   b . This may have to be shared with CUb by the IAB-node, CUa, or the core network. 
       FIG. 7  is a flow diagram illustrating example operations  700  for wireless communication by a base station (BS), in accordance with certain aspects of the present disclosure. For example, operations  700  may be performed by a first BS, such as a first IAB-donor-CU (e.g., CUb described with respect to  FIG. 6 ). 
     Operations  700  may be implemented as software components that are executed and run on one or more processors (e.g., controller/processor  240  of  FIG. 2 ). Further, the transmission and reception of signals by the BS (e.g., IAB-donor-CU) in operations  700  may be enabled, for example, by one or more antennas (e.g., antennas  234  of  FIG. 2 ). In certain aspects, the transmission and/or reception of signals by the BS may be implemented via a bus interface of one or more processors (e.g., controller/processor  230 ,  220 ,  238 ,  240 , and  244 ) obtaining and/or outputting signals. 
     Operations  700  begin, at  705 , with first BS sending, to an IAB-node, a request message (e.g., a setup request message or context modification request message) requesting to setup or modify a context for a child node (e.g., UE  604  illustrated in  FIG. 6  or another IAB-node) of a first logical IAB-DU (e.g., DU 1   b  illustrated in  FIG. 6 ) of the IAB-node. The first logical IAB-DU may be associated with the first BS (e.g., Cub illustrated in  FIG. 6 ). For instance, the first logical IAB DU may be configured to manage a connection (e.g., F1 connection) established between the IAB-node and the first BS. 
     At  710 , the first BS sends an indication to the IAB-node that the child node (e.g., UE  604  or another IAB-node) is currently served by the IAB-node at a second logical IAB-DU (e.g., DU 1   a  illustrated in  FIG. 6 ) of the IAB-node. The second logical IAB-DU may be associated with a second BS (e.g., CUa illustrated in  FIG. 6 ). For instance, the second logic IAB-DU may be configured to manage a connection (e.g., F1 connection) established between the IAB-node and the second BS. 
     The request message may be for handover of the child node from the second BS (e.g., a source BS) to the first BS (e.g., target BS). In certain aspects, the request message may include the indication that the child node is currently served by the IAB-node, as described herein. 
     In some aspects, the indication to the IAB-node may include an indication identifying the child node. The identification of the child node may be performed in any suitable manner. For example, the indication identifying the child node may include an indication of a mapping between a radio bearer (RB) (e.g., an SRB or a DRB or an SL DRB), BH RLC CH or quality of service (QoS) flow configured at the second logical IAB-DU to another RB, another BH RLC CH, or another QoS flow, respectively, to be configured at the first logical IAB-DU for the child node. In other words, a request message may configure a RB, BH RLC CH or QoS flow at the first logical IAB-DU of the IAB-node. The indication sent by the first BS at  710  may include a mapping of the RB, BH RLC CH or QoS flow configured at the first logic IAB-DU to a corresponding RB, BH RLC CH or QoS flow configured at the second logical IAB-DU. The indication may also include QoS information of a corresponding RB, BH RLC CH or QoS flow at the second logical IAB-DU. 
     In certain aspects, the indication identifying the child node at  710  may include an identifier of the second BS associated with the second logical IAB-DU of the IAB-node. For example, the indication identifying the child node may include an identifier of a cell served by the second logical IAB-DU of the IAB-node. In some aspects, the identifier may uniquely identify the cell using, e.g., an NCGI or NC. In certain aspects, the identifier may include a PCI. 
     At  715 , the first BS receives an acknowledgment message (e.g., a context setup response message or context modification response message) from the IAB-node based at least in part on the indication to the IAB-node. 
       FIG. 8  is a flow diagram illustrating example operations  800  for wireless communication by an IAB-node, in accordance with certain aspects of the present disclosure. For example, operations  800  may be performed by IAB-node  602  illustrated in  FIG. 6 . 
     Operations  800  may be implemented as software components that are executed and run on one or more processors (e.g., controller/processor  240  of  FIG. 2 ). Further, the transmission and reception of signals by the IAB-node in operations  800  may be enabled, for example, by one or more antennas (e.g., antennas  234  of  FIG. 2 ). In certain aspects, the transmission and/or reception of signals by the IAB-node may be implemented via a bus interface of one or more processors (e.g., controller/processor  230 ,  220 ,  238 ,  240 , and  244 ) obtaining and/or outputting signals. 
     Operations  800  begin, at  805 , with the IAB-node receiving, from a first BS (e.g., Cub illustrated in  FIG. 6 ), a request message to setup or modify a context for a child node of a first logical IAB-DU of the IAB-node. The first logical IAB-DU may be associated with the first BS. 
     At  810 , the IAB-node receives, from the first BS, an indication that the child node is currently served by the IAB-node at a second logical IAB-DU of the IAB-node. The second logical IAB-DU may be associated with a second BS. 
     At  815 , the IAB-node may perform admission control (e.g., reserve resources) based at least in part on the indication, and at block  820 , send an acknowledgment message to the first BS based on the admission control. 
       FIG. 9  is a call flow diagram  900  illustrating example operations for handover, in accordance with certain aspects of the present disclosure. As illustrated, an IAB-donor-CU (e.g., CUa of a source BS, referred to as the second IAB-donor-CU in operations  700  of  FIG. 7 ) may send a handover request  502  to another IAB-donor-CU (e.g., CUb of a target BS, referred to as the first IAB-donor-CU in operations  700  of  FIG. 7 ). CUb (e.g., the first IAB-donor-CU) may send a request  902  (e.g., the UE context setup request or the UE context modification request, as described with respect to  FIGS. 5B and 5C ) to an IAB-node to setup or modify a context for a prospective child (e.g., child node such as UE  604  or other IAB-node) of a first logical IAB-DU (e.g., DU 1   b  illustrated in  FIG. 6 ) of the IAB-node associated with CUb (e.g., the first IAB-donor-CU). CUb may indicate (e.g., via request  902 ) to IAB-node that the prospective child is currently served by the IAB-node at a second logical IAB-DU (e.g., DU 1   a  illustrated in  FIG. 6 ) of the IAB-node. The indication may include an identifier of the prospective child at the second logical IAB-DU of the IAB-node. For example, the CUb may identify a UE (e.g., UE  604 ), a radio bearer, or BH RLC CH. That is, a request message may configure a radio bearer (SRB or DRB or SL DRB) or BH RLC CH or QoS flow at the first logical IAB-DU of the IAB-node. The indication may include a mapping to a corresponding RB, BH RLC CH, or QoS flow configured at the second logical IAB-DU, as described herein. In some cases, the indication may include QoS information of corresponding RB or BH RLC CH or QoS flow configured at the second logical IAB-DU. 
     A radio bearer may be identified by an F1-U tunnel that transports the bearer. The F1-U tunnel is further identified by a tunnel endpoint ID (TEID). The identification of the child node may also include UE IDs on F1 interface (e.g. gNB-CU UE F1 application protocol (AP) ID and gNB-DU UE F1 AP ID). These may be used by CUb to identify the UE initially served on DUa and migrated to DUb. CUa and CUb may share these IDs. 
     In some aspects, the indication may include an identifier of CUa (e.g., the second IAB-donor-CU) associated with the second logical IAB-DU (DU 1   a ) of the IAB-node. For example, the indication may include an identifier of a source cell served by the second logical IAB-DU of the IAB-node. The cell identifier may be NCGI/NCI or PCI, as described herein. As illustrated, the IAB-node may then reserve resources for the child node at block  904 , and send an acknowledgement  906  to CUb. CUb may then send a handover request acknowledgement  506  to CUa. At block  908 , the switch from the source BS to the target BS may occur, as described with respect to  FIG. 5A . 
     Referring back to  FIG. 6 , in some implementations, the handover of a UE from CUa to CUb may be triggered by a measurement report from the UE  604  to CUa. The measurement report may also be sent from CUa to DU 1   b  indicating that UE  604  may be migrating from CUa to CUb. In other words, DU 1   b  may be informed that UE  604  has measured the link towards IAB-node  602 , DU 1   a , or DU 1   b , facilitating the setup of the connection by DU 1   b  with UE  604 . 
     In other words, CUa may include in the UE context setup/modification request message to DU 1   b , RRC information having the measurement report that triggered the handover of UE  604 . This measurement report may include measurement of the serving cell in an information element (IE) (e.g., measResultServingMOList IE). The IE may contain the serving cell identifier, which may be a gNB-local ID, as well as a PCI which may not uniquely identify the serving cell. Thus, the measurement report may not indicate to IAB-node  602  that the UE is currently being served by IAB-node  602  itself. In certain implementations, the UE/descendant IAB-MT may switch logical IAB-DUs of an IAB-node without submitting a measurement report since this may be triggered by the migration of an upstream node (e.g., if the signal quality of the link between UE  604  and IAB-node  602  is not the cause for the handover). Therefore, certain aspects of the present disclosure provide additional signalling to IAB-node  602  that identifies that UE  604  is being admitted for handover as a UE being currently served by IAB-node  602 . The aspects described herein also provide admission control techniques at a finer level, e.g. bearer or BH RLC CH. 
     Wireless Communications Devices 
       FIG. 10  illustrates a communications device  1000  that may include various components (e.g., corresponding to means-plus-function components) operable, configured, or adapted to perform operations for the techniques disclosed herein, such as the operations illustrated in  FIG. 7 . In some examples, communications device  1000  may be a station (BS), and more specifically, an Integrated Access and Backhaul (IAB)-donor-central unit (CU) (e.g., Donor CUb described with respect to  FIG. 6 ). 
     Communications device  1000  includes a processing system  1002  coupled to a transceiver  1008  (e.g., a transmitter and/or a receiver). Transceiver  1008  is configured to transmit and receive signals for communications device  1000  via an antenna  1010 , such as the various signals as described herein. Transceiver  1008  can, for example, include one or more components of BS  110  with reference to  FIG. 2 , including, for example, demodulators  232 , transmit (TX) multiple-input multiple-output (MIMO) processor  230 , transmit processor  220 , MIMO detector  236 , receive processor  238 , and/or the like. Processing system  1002  may be configured to perform processing functions for communications device  1000 , including processing signals received and/or to be transmitted by communications device  1000 . 
     Processing system  1002  includes a processor  1004  coupled to a computer-readable medium/memory  1012  via a bus  1006 . In certain aspects, computer-readable medium/memory  1012  is configured to store instructions (e.g., computer-executable code) that when executed by processor  1004 , cause the processor  1004  to perform the operations illustrated in  FIG. 7 , or other operations for performing the various techniques discussed herein for admission control, for example, in an IAB network. 
     In certain aspects, computer-readable medium/memory  1012  stores code  1014  (e.g., an example means for) for sending and; code  1016  (e.g., an example means for) for receiving. 
     In certain aspects, code  1014  for sending may include code for sending, to an IAB-node, a request message requesting to setup or modify a context for a child node of a first logical IAB-distributed unit (DU) of the IAB-node, wherein the first logical IAB-DU is associated with the first BS. In certain aspects, code  1014  for sending may include code for sending an indication to the IAB-node that the child node is currently served by the IAB-node at a second logical IAB-DU of the IAB-node, wherein the second logical IAB-DU is associated with a second BS. 
     In certain aspects, code  1016  for receiving may include code for receiving an acknowledgment message from the IAB-node based at least in part on the indication to the IAB-node. 
     In certain aspects, processor  1004  has circuitry configured to implement the code stored in computer-readable medium/memory  1012 . Processor  1004  includes circuitry  1024  (e.g., an example means for) for sending; and circuitry  1026  (e.g., an example means for) for receiving. 
     In certain aspects, circuitry  1024  for sending may include circuitry for sending, to an IAB-node, a request message requesting to setup or modify a context for a child node of a first logical IAB-DU of the IAB-node, wherein the first logical IAB-DU is associated with the first BS. In certain aspects, circuitry  1024  for sending may include circuitry for sending an indication to the IAB-node that the child node is currently served by the IAB-node at a second logical IAB-DU of the IAB-node, wherein the second logical IAB-DU is associated with a second BS. 
     In certain aspects, circuitry  1026  for receiving may include circuitry for receiving an acknowledgment message from the IAB-node based at least in part on the indication to the IAB-node. 
     Means for transmitting or sending (or means for outputting for transmission) may include a transmitter and/or an antenna(s)  234  of the BS  110  illustrated in  FIG. 2  and/or circuitry  1024  and/or transceiver  1008  of communication device  1000  in  FIG. 10 . Means for receiving (or means for obtaining) may include a receiver and/or an antenna(s)  234  of the BS  110  illustrated in  FIG. 2  and/or circuitry  1026  and/or transceiver  1008  of communication device  1000  in  FIG. 10 . 
     Notably,  FIG. 10  is just one example, and many other examples and configurations of communications device  1000  are possible. 
       FIG. 11  illustrates a communications device  1100  that may include various components (e.g., corresponding to means-plus-function components) operable, configured, or adapted to perform operations for the techniques disclosed herein, such as the operations illustrated in  FIG. 8 . In some examples, communications device  1100  may be a network entity, and more specifically, an IAB-node (e.g., IAB-node  602  described with respect to  FIG. 6 ). 
     Communications device  1100  includes a processing system  1102  coupled to a transceiver  1108  (e.g., a transmitter and/or a receiver). Transceiver  1108  is configured to transmit and receive signals for communications device  1100  via an antenna  1110 , such as the various signals as described herein. Transceiver  1108  can, for example, include one or more components of BS  110  with reference to  FIG. 2 , including, for example, demodulators  232 , TX MIMO processor  230 , transmit processor  220 , MIMO detector  236 , receive processor  238 , and/or the like. Processing system  1102  may be configured to perform processing functions for communications device  1100 , including processing signals received and/or to be transmitted by communications device  1100 . 
     Processing system  1102  includes a processor  1104  coupled to a computer-readable medium/memory  1112  via a bus  1106 . In certain aspects, computer-readable medium/memory  1112  is configured to store instructions (e.g., computer-executable code) that when executed by processor  1104 , cause processor  1104  to perform the operations illustrated in  FIG. 8 , or other operations for performing the various techniques discussed herein for admission control, for example, in an IAB network. 
     In certain aspects, computer-readable medium/memory  1112  stores code  1114  (e.g., an example means for) for receiving; code  1116  (e.g., an example means for) for performing admission control; and code  1118  (e.g., an example means for) for sending. 
     In certain aspects, code  1114  for receiving may include code for receiving, from a first BS, a request message to setup or modify a context for a child node of a first logical IAB-DU of the IAB-node, wherein the first logical IAB-DU is associated with the first BS. In certain aspects, code  1114  for receiving may include code for receiving, from the first BS, an indication that the child node is currently served by the IAB-node at a second logical IAB-DU of the IAB-node, wherein the second logical IAB-DU is associated with a second BS. 
     In certain aspects, code  1116  for performing admission control may include code for performing admission control based at least in part on the indication. 
     In certain aspects, code  1118  for sending may include code for sending an acknowledgment message to the first BS based the admission control. 
     In certain aspects, processor  1104  has circuitry configured to implement the code stored in computer-readable medium/memory  1112 . Processor  1104  includes circuitry  1124  (e.g., an example means for) for receiving; circuitry  1126  (e.g., an example means for) for performing admission control; and circuitry  1128  (e.g., an example means for) for sending. 
     In certain aspects, circuitry  1124  for receiving may include circuitry for receiving, from a first BS, a request message to setup or modify a context for a child node of a first logical IAB-DU of the IAB-node, wherein the first logical IAB-DU is associated with the first BS. In certain aspects, circuitry  1124  for receiving may include circuitry for receiving, from the first BS, an indication that the child node is currently served by the IAB-node at a second logical IAB-DU of the IAB-node, wherein the second logical IAB-DU is associated with a second BS. 
     In certain aspects, circuitry  1126  for performing admission control may include circuitry for performing admission control based at least in part on the indication. 
     In certain aspects, circuitry  1128  for sending may include circuitry for sending an acknowledgment message to the first BS based the admission control. 
     Means for transmitting or sending (or means for outputting for transmission) may include a transmitter and/or an antenna(s)  234  of the BS  110  illustrated in  FIG. 2  and/or circuitry  1128  and/or transceiver  1008  of communication device  1100  in  FIG. 11 . Means for receiving (or means for obtaining) may include a receiver and/or an antenna(s)  234  of the BS  110  illustrated in  FIG. 2  and/or circuitry  1124  and/or transceiver  1108  of communication device  1100  in  FIG. 11 . 
     Means for performing admission control may include a processing system, which may include one or more processors, such as the transmit processor  220 , the TX MIMO processor  230 , the receive processor  238 , and/or the controller/processor  240  of BS  110  illustrated in  FIG. 2  and/or processing system  1102  of communication device  1100  in  FIG. 11 . 
     Notably,  FIG. 11  is just one example, and many other examples and configurations of communications device  1100  are possible. 
     Example Aspects 
     Implementation examples are described in the following numbered aspects: 
     Aspect 1. A method for wireless communication by a first base station (BS), comprising: sending, to an Integrated Access and Backhaul (IAB)-node, a request message requesting to setup or modify a context for a child node of a first logical IAB-distributed unit (DU) of the IAB-node, wherein the first logical IAB-DU is associated with the first BS; sending an indication to the IAB-node that the child node is currently served by the IAB-node at a second logical IAB-DU of the IAB-node, wherein the second logical IAB-DU is associated with a second BS; and receiving an acknowledgment message from the IAB-node based at least in part on the indication to the IAB-node. 
     Aspect 2. The method of aspect 1, wherein the request message is for handover of the child node from the second BS to the first BS. 
     Aspect 3. The method of any one of aspects 1-2, wherein the request message comprises the indication that the child node is currently served by the IAB-node. 
     Aspect 4. The method of any one of aspects 1-3, wherein the first BS comprises a first Integrated Access and Backhaul (IAB) donor central unit (CU), and wherein the second BS comprises a second IAB donor CU. 
     Aspect 5. The method of any one of aspects 1-4, wherein the first logical IAB DU is configured to manage a connection established between the IAB-node and the first BS, and wherein the second logic IAB-DU is configured to manage a connection established between the IAB-node and the second BS. 
     Aspect 6. The method of any one of aspects 1-5, wherein the request message comprises a context setup request message or context modification request message. 
     Aspect 7. The method of any one of aspects 1-6, wherein the acknowledgment message is a context setup response message or context modification response message. 
     Aspect 8. The method of any one of aspects 1-7, wherein the child node comprises user equipment (UE) or another IAB-node. 
     Aspect 9. The method of any one of aspects 1-8, wherein the indication to the IAB-node comprises an indication identifying the child node. 
     Aspect 10. The method of aspect 9, wherein the indication identifying the child node comprises an indication of a mapping between a radio bearer (RB), backhaul (BH) radio link control (RLC) channel (CH) or quality of service (QoS) flow configured at the second logical IAB-DU to another RB, another BH RLC CH, or another QoS flow, respectively, to be configured at the first logical IAB-DU for the child node. 
     Aspect 11. The method of aspect 10, wherein the RB comprise a signaling RB (SRB) or a data RB (DRB) or a sidelink (SL) DRB. 
     Aspect 12. The method of any one of aspects 9-11, wherein the indication identifying the child node comprises QoS information of a RB, BH RLC CH, or QoS flow configured at the second logical IAB-DU for the child node. 
     Aspect 13. The method of any one of aspects 9-12, wherein the indication identifying the child node comprises an identifier of the second BS associated with the second logical IAB-DU of the IAB-node. 
     Aspect 14. The method of any one of aspects 9-13, wherein the indication identifying the child node comprises an identifier of a cell served by the second logical IAB-DU of the IAB-node. 
     Aspect 15. The method of aspect 14, wherein the identifier uniquely identifies the cell. 
     Aspect 16. The method of aspect 15, wherein the identifier comprises a new radio (NR) cell global identity (NCGI) or NR cell identity (NCI). 
     Aspect 17. The method of any one of aspects 14-16, wherein the identifier comprises physical cell identifier (PCI). 
     Aspect 18. A method for wireless communication by an Integrated Access and Backhaul (IAB) node, comprising: receiving, from a first base station (BS), a request message to setup or modify a context for a child node of a first logical IAB-DU of the IAB-node, wherein the first logical IAB-DU is associated with the first BS; receiving, from the first BS, an indication that the child node is currently served by the IAB-node at a second logical IAB-DU of the IAB-node, wherein the second logical IAB-DU is associated with a second BS; performing admission control based at least in part on the indication; and sending an acknowledgment message to the first BS based the admission control. 
     Aspect 19. The method of aspect 17, wherein the request message is for handover of the child node from the second BS to the first BS. 
     Aspect 20. The method of aspect 18, wherein the request message comprises the indication that the child node is currently served by the IAB-node. 
     Aspect 21. The method of any one of aspects 18-20, wherein performing the admission control comprises reserving resources for serving the child node. 
     Aspect 22. The method of any one of aspects 18-21, wherein the first BS comprises a first Integrated Access and Backhaul (IAB) donor central unit (CU), and wherein the second BS comprises a second IAB donor CU. 
     Aspect 23. The method of any one of aspects 18-22, wherein the first logical IAB-DU is configured to manage a connection established between the IAB-node and the first BS, and wherein the second logic IAB-DU is configured to manage a connection established between the IAB-node and the second BS. 
     Aspect 24. The method of any one of aspects 18-23, wherein the request message comprises a context setup request message or a context modification request message. 
     Aspect 25. The method of any one of aspects 18-24, wherein the acknowledgment message is a context setup response message or a context modification response message. 
     Aspect 26. The method of any one of aspects 18-25, wherein the child node comprises user equipment (UE) or a second IAB-node. 
     Aspect 27. The method of any one of aspects 18-26, wherein the indication to the IAB-node comprises an indication identifying the child node. 
     Aspect 28. The method of aspect 27, wherein the indication identifying the child node comprises an indication of a mapping between a radio bearer (RB), backhaul (BH) radio link control (RLC) channel (CH) or quality of service (QoS) flow configured at the second logical IAB-DU to another RB, another BH RLC CH, or another QoS flow, respectively, to be configured at the first logical IAB-DU for the child node. 
     Aspect 29. The method of aspect 28, wherein the radio bearer comprise a signaling RB (SRB) or a data RB (DRB) or a sidelink (SL) DRB. 
     Aspect 30. The method of any one of aspects 27-29, wherein the indication identifying the child node comprises QoS information of a radio bearer, BH RLC CH, or QoS flow configured at the second logical IAB-DU for the child node. 
     Aspect 31. The method of any one of aspects 27-30, wherein the indication identifying the child node comprises an identifier of the second BS associated with the second logical IAB-DU of the IAB-node. 
     Aspect 32. The method of any one of aspects 27-31, wherein the indication identifying the child node comprises an identifier of a cell served by the second logical IAB-DU of the IAB-node. 
     Aspect 33. The method of aspect 32, wherein the identifier uniquely identifies the cell. 
     Aspect 34. The method of aspect 33, wherein the identifier comprises a new radio (NR) cell global identity (NCGI) or NR cell identity (NCI). 
     Aspect 35. The method of any one of aspects 32-34, wherein the identifier comprises physical cell identifier (PCI). 
     Aspect 36. An apparatus comprising means for performing the method of any of aspects 1 through 35. 
     Aspect 37. An apparatus comprising at least one processor and a memory coupled to the at least one processor, the memory comprising code executable by the at least one processor to cause the apparatus to perform the method of any of aspects 1 through 35. 
     Aspect 38. A non-transitory computer-readable medium storing computer executable code thereon for wireless communications that, when executed by at least one processor, cause an apparatus to perform the method of any of aspects 1 through 35. 
     Additional Considerations 
     The techniques described herein may be used for various wireless communication technologies, such as 3GPP Long Term Evolution (LTE), LTE-Advanced (LTE-A), code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal frequency division multiple access (OFDMA), single-carrier frequency division multiple access (SC-FDMA), time division synchronous code division multiple access (TD-SCDMA), and other networks. The terms “network” and “system” are often used interchangeably. 
     A CDMA network may implement a radio technology such as Universal Terrestrial Radio Access (UTRA), cdma2000, etc. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. cdma2000 covers IS-2000, IS-95 and IS-856 standards. A TDMA network may implement a radio technology such as Global System for Mobile Communications (GSM). An OFDMA network may implement a radio technology such as NR (e.g. 5G RA), Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDMA, etc. UTRA and E-UTRA are part of Universal Mobile Telecommunication System (UMTS). LTE and LTE-A are releases of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A and GSM are described in documents from an organization named “3rd Generation Partnership Project” (3GPP). cdma2000 and UMB are described in documents from an organization named “3rd Generation Partnership Project 2” (3GPP2). 
     The techniques described herein may be used for the wireless networks and radio technologies mentioned above as well as other wireless networks and radio technologies. For clarity, while aspects may be described herein using terminology commonly associated with 3G, 4G, and/or 5G wireless technologies, aspects of the present disclosure can be applied in other generation-based communication systems. 
     New Radio (NR) is an emerging wireless communications technology under development in conjunction with the 5G Technology Forum (5GTF). NR access (e.g., 5G NR) may support various wireless communication services, such as enhanced mobile broadband (eMBB) targeting wide bandwidth (e.g., 80 megahertz (MHz) or beyond), millimeter wave (mmW) targeting high carrier frequency (e.g., 25 gigahertz (GHz) or beyond), massive machine type communications MTC (mMTC) targeting non-backward compatible MTC techniques, and/or mission critical targeting ultra-reliable low-latency communications (URLLC). These services may include latency and reliability requirements. These services may also have different transmission time intervals (TTIs) to meet respective quality of service (QoS) requirements. In addition, these services may co-exist in the same subframe. 
     In 3GPP, the term “cell” can refer to a coverage area of a Node B (NB) and/or a NB subsystem serving this coverage area, depending on the context in which the term is used. In NR systems, the term “cell” and BS, next generation NodeB (gNB or gNodeB), access point (AP), distributed unit (DU), carrier, or transmission reception point (TRP) may be used interchangeably. A BS may provide communication coverage for a macro cell, a pico cell, a femto cell, and/or other types of cells. A macro cell may cover a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs with service subscription. A pico cell may cover a relatively small geographic area and may allow unrestricted access by UEs with service subscription. A femto cell may cover a relatively small geographic area (e.g., a home) and may allow restricted access by UEs having an association with the femto cell (e.g., UEs in a Closed Subscriber Group (CSG), UEs for users in the home, etc.). A BS for a macro cell may be referred to as a macro BS. A BS for a pico cell may be referred to as a pico BS. A BS for a femto cell may be referred to as a femto BS or a home BS. 
     A UE may also be referred to as a mobile station, a terminal, an access terminal, a subscriber unit, a station, a Customer Premises Equipment (CPE), a cellular phone, a smart phone, a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a tablet computer, a camera, a gaming device, a netbook, a smartbook, an ultrabook, an appliance, a medical device or medical equipment, a biometric sensor/device, a wearable device such as a smart watch, smart clothing, smart glasses, a smart wrist band, smart jewelry (e.g., a smart ring, a smart bracelet, etc.), an entertainment device (e.g., a music device, a video device, a satellite radio, etc.), a vehicular component or sensor, a smart meter/sensor, industrial manufacturing equipment, a global positioning system device, or any other suitable device that is configured to communicate via a wireless or wired medium. Some UEs may be considered machine-type communication (MTC) devices or evolved MTC (eMTC) devices. MTC and eMTC UEs include, for example, robots, drones, remote devices, sensors, meters, monitors, location tags, etc., that may communicate with a BS, another device (e.g., remote device), or some other entity. A wireless node may provide, for example, connectivity for or to a network (e.g., a wide area network such as Internet or a cellular network) via a wired or wireless communication link. Some UEs may be considered Internet-of-Things (IoT) devices, which may be narrowband IoT (NB-IoT) devices. 
     Certain wireless networks (e.g., LTE) utilize orthogonal frequency division multiplexing (OFDM) on the downlink (DL) and single-carrier frequency division multiplexing (SC-FDM) on the uplink (UL). OFDM and SC-FDM partition the system bandwidth into multiple (K) orthogonal subcarriers, which are also commonly referred to as tones, bins, etc. Each subcarrier may be modulated with data. In general, modulation symbols are sent in the frequency domain with OFDM and in the time domain with SC-FDM. The spacing between adjacent subcarriers may be fixed, and the total number of subcarriers (K) may be dependent on the system bandwidth. For example, the spacing of the subcarriers may be 15 kilohertz (kHz) and the minimum resource allocation (called a “resource block” (RB)) may be 12 subcarriers (or 180 kHz). Consequently, the nominal Fast Fourier Transfer (FFT) size may be equal to 128, 256, 512, 1024 or 2048 for system bandwidth of 1.25, 2.5, 5, 10, or 20 megahertz (MHz), respectively. The system bandwidth may also be partitioned into subbands. For example, a subband may cover 1.8 MHz (e.g., 6 RBs), and there may be 1, 2, 4, 8, or 16 subbands for system bandwidth of 1.25, 2.5, 5, 10 or 20 MHz, respectively. In LTE, the basic TTI or packet duration is the 1 ms subframe. 
     NR may utilize OFDM with a CP on the UL and DL and include support for half-duplex operation using time division duplexing (TDD). In NR, a subframe is still 1 millisecond (ms), but the basic TTI is referred to as a slot. A subframe contains a variable number of slots (e.g., 1, 2, 4, 8, 16, . . . slots) depending on the subcarrier spacing (SCS). The NR RB is 12 consecutive frequency subcarriers. NR may support a base SCS of 15 KHz and other SCS may be defined with respect to the base SCS, for example, 30 kHz, 60 kHz, 120 kHz, 240 kHz, etc. The symbol and slot lengths scale with the subcarrier spacing. The CP length also depends on the subcarrier spacing. Beamforming may be supported and beam direction may be dynamically configured. MIMO transmissions with precoding may also be supported. In some examples, MIMO configurations in the DL may support up to 8 transmit antennas with multi-layer DL transmissions up to 8 streams and up to 2 streams per UE. In some examples, multi-layer transmissions with up to 2 streams per UE may be supported. Aggregation of multiple cells may be supported with up to 8 serving cells. 
     In some examples, access to the air interface may be scheduled. A scheduling entity (e.g., a BS) allocates resources for communication among some or all devices and equipment within its service area or cell. The scheduling entity may be responsible for scheduling, assigning, reconfiguring, and releasing resources for one or more subordinate entities. That is, for scheduled communication, subordinate entities utilize resources allocated by the scheduling entity. BSs are not the only entities that may function as a scheduling entity. In some examples, a UE may function as a scheduling entity and may schedule resources for one or more subordinate entities (e.g., one or more other UEs), and the other UEs may utilize the resources scheduled by the UE for wireless communication. In some examples, a UE may function as a scheduling entity in a peer-to-peer (P2P) network, and/or in a mesh network. In a mesh network example, UEs may communicate directly with one another in addition to communicating with a scheduling entity. 
     In some examples, two or more subordinate entities (e.g., UEs) may communicate with each other using sidelink signals. Real-world applications of such sidelink communications may include public safety, proximity services, UE-to-network relaying, vehicle-to-vehicle (V2V) communications, Internet of Everything (IoE) communications, IoT communications, mission-critical mesh, and/or various other suitable applications. Generally, a sidelink signal may refer to a signal communicated from one subordinate entity (e.g., UE1) to another subordinate entity (e.g., UE2) without relaying that communication through the scheduling entity (e.g., UE or BS), even though the scheduling entity may be utilized for scheduling and/or control purposes. In some examples, the sidelink signals may be communicated using a licensed spectrum (unlike wireless local area networks, which typically use an unlicensed spectrum). 
     The methods disclosed herein comprise one or more steps or actions for achieving the methods. The method steps and/or actions may be interchanged with one another without departing from the scope of the claims. In other words, unless a specific order of steps or actions is specified, the order and/or use of specific steps and/or actions may be modified without departing from the scope of the claims. 
     As used herein, a phrase referring to “at least one of” a list of items refers to any combination of those items, including single members. As an example, “at least one of: a, b, or c” is intended to cover a, b, c, a-b, a-c, b-c, and a-b-c, as well as any combination with multiples of the same element (e.g., a-a, a-a-a, a-a-b, a-a-c, a-b-b, a-c-c, b-b, b-b-b, b-b-c, c-c, and c-c-c or any other ordering of a, b, and c). 
     As used herein, the term “determining” encompasses a wide variety of actions. For example, “determining” may include calculating, computing, processing, deriving, investigating, looking up (e.g., looking up in a table, a database or another data structure), ascertaining and the like. Also, “determining” may include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory) and the like. Also, “determining” may include resolving, selecting, choosing, establishing and the like. 
     The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language of the claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more.” Unless specifically stated otherwise, the term “some” refers to one or more. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed under the provisions of 35 U.S.C. § 112(f) unless the element is expressly recited using the phrase “means for” or, in the case of a method claim, the element is recited using the phrase “step for.” 
     The various operations of methods described above may be performed by any suitable means capable of performing the corresponding functions. The means may include various hardware and/or software component(s) and/or module(s), including, but not limited to a circuit, an application specific integrated circuit (ASIC), or processor. Generally, where there are operations illustrated in figures, those operations may have corresponding counterpart means-plus-function components. 
     The various illustrative logical blocks, modules and circuits described in connection with the present disclosure may be implemented or performed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device (PLD), discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any commercially available processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. 
     If implemented in hardware, an example hardware configuration may comprise a processing system in a wireless node. The processing system may be implemented with a bus architecture. The bus may include any number of interconnecting buses and bridges depending on the specific application of the processing system and the overall design constraints. The bus may link together various circuits including a processor, machine-readable media, and a bus interface. The bus interface may be used to connect a network adapter, among other things, to the processing system via the bus. The network adapter may be used to implement the signal processing functions of the physical (PHY) layer. In the case of a user terminal (see  FIG. 1 ), a user interface (e.g., keypad, display, mouse, joystick, etc.) may also be connected to the bus. The bus may also link various other circuits such as timing sources, peripherals, voltage regulators, power management circuits, and the like, which are well known in the art, and therefore, will not be described any further. The processor may be implemented with one or more general-purpose and/or special-purpose processors. Examples include microprocessors, microcontrollers, DSP processors, and other circuitry that can execute software. Those skilled in the art will recognize how best to implement the described functionality for the processing system depending on the particular application and the overall design constraints imposed on the overall system. For example, in some cases, processors such as those shown in  FIG. 2  may be configured to perform operations  700  of  FIG. 7 , and/or operations  800  of  FIG. 8 . 
     If implemented in software, the functions may be stored or transmitted over as one or more instructions or code on a computer readable medium. Software shall be construed broadly to mean instructions, data, or any combination thereof, whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. Computer-readable media include both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. The processor may be responsible for managing the bus and general processing, including the execution of software modules stored on the machine-readable storage media. A computer-readable storage medium may be coupled to a processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. By way of example, the machine-readable media may include a transmission line, a carrier wave modulated by data, and/or a computer readable storage medium with instructions stored thereon separate from the wireless node, all of which may be accessed by the processor through the bus interface. Alternatively, or in addition, the machine-readable media, or any portion thereof, may be integrated into the processor, such as the case may be with cache and/or general register files. Examples of machine-readable storage media may include, by way of example, RAM (Random Access Memory), flash memory, ROM (Read Only Memory), PROM (Programmable Read-Only Memory), EPROM (Erasable Programmable Read-Only Memory), EEPROM (Electrically Erasable Programmable Read-Only Memory), registers, magnetic disks, optical disks, hard drives, or any other suitable storage medium, or any combination thereof. The machine-readable media may be embodied in a computer-program product. 
     A software module may comprise a single instruction, or many instructions, and may be distributed over several different code segments, among different programs, and across multiple storage media. The computer-readable media may comprise a number of software modules. The software modules include instructions that, when executed by an apparatus such as a processor, cause the processing system to perform various functions. The software modules may include a transmission module and a receiving module. Each software module may reside in a single storage device or be distributed across multiple storage devices. By way of example, a software module may be loaded into RAM from a hard drive when a triggering event occurs. During execution of the software module, the processor may load some of the instructions into cache to increase access speed. One or more cache lines may then be loaded into a general register file for execution by the processor. When referring to the functionality of a software module below, it will be understood that such functionality is implemented by the processor when executing instructions from that software module. 
     Also, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared (IR), radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk and disc, as used herein, include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk, and Blu-ray® disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Thus, in some aspects computer-readable media may comprise non-transitory computer-readable media (e.g., tangible media). In addition, for other aspects computer-readable media may comprise transitory computer-readable media (e.g., a signal). Combinations of the above should also be included within the scope of computer-readable media. 
     Thus, certain aspects may comprise a computer program product for performing the operations presented herein. For example, such a computer program product may comprise a computer-readable medium having instructions stored (and/or encoded) thereon, the instructions being executable by one or more processors to perform the operations described herein. For example, instructions for performing the operations described herein and illustrated in  FIGS. 7-8 . 
     Further, it should be appreciated that modules and/or other appropriate means for performing the methods and techniques described herein can be downloaded and/or otherwise obtained by a user terminal and/or base station as applicable. For example, such a device can be coupled to a server to facilitate the transfer of means for performing the methods described herein. Alternatively, various methods described herein can be provided via storage means (e.g., RAM, ROM, a physical storage medium such as a compact disc (CD) or floppy disk, etc.), such that a user terminal and/or BS can obtain the various methods upon coupling or providing the storage means to the device. Moreover, any other suitable technique for providing the methods and techniques described herein to a device can be utilized. 
     It is to be understood that the claims are not limited to the precise configuration and components illustrated above. Various modifications, changes and variations may be made in the arrangement, operation and details of the methods and apparatus described above without departing from the scope of the claims.