Inter-distributed unit (DU) flow control for carrier aggregation

Abstract

A method for an inter-distributed unit (DU) flow control for carrier aggregation (CA) is disclosed. The method includes receiving, by at least one secondary cell associated with a second Distributed Unit (DU) of a gNodeB (gNB), a secondary cell activation command from a primary cell associated with a first DU of the gNB. The method includes transmitting, by the at least one secondary cell, a secondary cell uplink configuration message to the primary cell. The secondary cell uplink configuration message comprises at least one of a Downlink Assignment Index (DAI), a Hybrid Automatic Repeat request (HARQ) size, and a Desired Transmission Block (DTB) size. The method further includes receiving, by the at least one secondary cell, a RLC PDU of an optimal size from the primary cell based on the received secondary cell uplink configuration message. The size of the RLC PDU is modified based on the DTB size.

Description

INTER-DISTRIBUTED UNIT (DU) FLOW CONTROL FOR CARRIER AGGREGATIONCROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of Indian Patent Application No. 202411081129 filed October 24, 2024, which is hereby incorporated by reference in its entirety.FIELD

[0002] The present disclosure relates to an inter-Distributed Unit (DU) flow control for Carrier Aggregation (CA).BACKGROUND

[0003] The information disclosed in this background section is only for the enhancement of understanding of the general background of the disclosure and should not be taken as an acknowledgment or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

[0004] The 3rd Generation Partnership Project (3GPP) has defined a disaggregated RAN architecture decomposing a gNodeB (gNB) into multiple logical entities. Further, for the gNB in 5thGeneration (5G) New Radio (NR) systems, such disaggregated entities include at least one Distributed Unit (DU) and a Centralized Unit (CU). The CU may be further split into a CU Control Plane (CP) part, also referred to as CU-C or CU-CP, and a CU User Plane (UP) part, also referred to as CU-U or CU-UP. The gNB-CU may be connected to a plurality of gNB-DUs. One of theplurality of gNB-DUs may be a primary gNB-DU that is currently transmitting data packets to a User Equipment (UE) and another one may be a secondary gNB-DU. In the case of inter-DU Carrier Aggregation (CA) operations, the DU peers (i.e., the primary gNB-DU and the secondary gNB-DU) communicate with each other in real-time for sending a Radio Link Control (RLC) data packets from a Primary Cell (PCELL) DU Media Access Control (MAC) to a Secondary Cell (SCELL) DU MAC for scheduling the RLC packets for the UE. However, there are certain challenges associated with the transmission of the RLC data packets from the PCELL DU MAC to the SCELL DU MAC.SUMMARY

[0005] This summary is provided to introduce a selection of concepts, in a simplified format, that are further described in the detailed description of the disclosure. This summary is neither intended to identify key or essential inventive concepts of the disclosure nor is it intended for determining the scope of the disclosure.

[0006] According to one embodiment of the present disclosure, a method is disclosed. The method includes receiving, by at least one secondary cell associated with a second Distributed Unit (DU) of a gNodeB (gNB), a secondary cell activation command from a primary cell associated with a first DU of the gNB. The secondary cell activation command comprises a small Radio Link Control (RLC) Protocol Data Unit (PDU). Further, the method includes transmitting, by the at least one secondary cell, a secondary cell uplink configuration message to the primary cell, in response to the received the secondary cell activation command. The secondary cell uplink configuration message comprises at least one of a Downlink Assignment Index (DAI), a HybridAutomatic Repeat request (HARQ) size, and a Desired Transmission Block (DTB) size. The method further includes receiving, by the at least one secondary cell, a RLC PDU of an optimal size from the primary cell based on the received secondary cell uplink configuration message. A size of the RLC PDU is reduced or increased based on the DTB size.

[0007] According to one embodiment of the present disclosure, a method is disclosed. The method includes transmitting, by a primary cell associated with a first Distributed Unit (DU) of a gNodeB (gNB), a secondary cell activation command to at least one secondary cell associated with a second DU of the gNB. The secondary cell activation command comprises a small Radio Link Control (RLC) Protocol Data Unit (PDU). The method further includes receiving, by the primary cell, a secondary cell uplink configuration message from the at least one secondary cell, in response to the transmitted secondary cell activation command. The secondary cell uplink configuration message comprises at least one of a Downlink Assignment Index (DAI), a Hybrid Automatic Repeat request (HARQ) size, and a Desired Transmission Block (DTB) size. Further, the method includes determining an optimal size of a RLC PDU based on the received secondary cell uplink configuration message, wherein a size of the RLC PDU is reduced or increased based on the DTB size. The method further includes transmitting, by the primary cell, the RLC PDU of the optimal size to the at least one secondary cell.

[0008] According to one embodiment of the present disclosure, an apparatus is disclosed. The apparatus is configured to receive, by at least one secondary cell associated with a second Distributed Unit (DU) of a gNodeB (gNB), a secondary cell activation command from a primary cell associated with a first DU of the gNB. The secondary cell activation command comprises a small Radio Link Control (RLC) Protocol Data Unit (PDU). The apparatus is further configuredto transmit, by the at least one secondary cell, a secondary cell uplink configuration message to the primary cell in response to the received the secondary cell activation command. The secondary cell uplink configuration message comprises at least one of a Downlink Assignment Index (DAI), a Hybrid Automatic Repeat request (HARQ) size, and a Desired Transmission Block (DTB) size. Further, the apparatus is configured to receive, by the at least one secondary cell, a RLC PDU of an optimal size from the primary cell based on the received secondary cell uplink configuration message, wherein a size of the RLC PDU is reduced or increased based on the DTB size.

[0009] According to one embodiment of the present disclosure, an apparatus is disclosed. The apparatus is configured to transmit, by a primary cell associated with a first Distributed Unit (DU) of a gNodeB (gNB), a secondary cell activation command to at least one secondary cell associated with a second DU of the gNB. The secondary cell activation command comprises a small Radio Link Control (RLC) Protocol Data Unit (PDU). The apparatus is further configured to receive, by the primary cell, a secondary cell uplink configuration message from the at least one secondary cell, in response to the transmitted secondary cell activation command. The secondary cell uplink configuration message comprises at least one of a Downlink Assignment Index (DAI), a Hybrid Automatic Repeat request (HARQ) size, and a Desired Transmission Block (DTB) size. Further the apparatus is configured to determine an optimal size of a RLC PDU based on the received secondary cell uplink configuration message. A size of the RLC PDU is reduced or increased based on the DTB size. Further, the apparatus is configured to transmit, by the primary cell, the RLC PDU of the optimal size to the at least one secondary cell.

[0010] According to one embodiment of the present disclosure, a non-transitory computer-readable medium is disclosed. The non-transitory computer-readable medium storing instructions,the instructions comprising: one or more instructions that, when executed by an apparatus, the apparatus comprising one or more processors, cause the one or more processors to receive, by at least one secondary cell associated with a second Distributed Unit (DU) of a gNodeB (gNB), a secondary cell activation command from a primary cell associated with a first DU of the gNB. The secondary cell activation command comprises a small Radio Link Control (RLC) Protocol Data Unit (PDU). The one or more processors to transmit, by the at least one secondary cell, a secondary cell uplink configuration message to the primary cell, in response to the received the secondary cell activation command. The secondary cell uplink configuration message comprises at least one of a Downlink Assignment Index (DAI), a Hybrid Automatic Repeat request (HARQ) size, and a Desired Transmission Block (DTB) size. The one or more processors to receive, by the at least one secondary cell, a RLC PDU of an optimal size from the primary cell based on the received secondary cell uplink configuration message, wherein a size of the RLC PDU is reduced or increased based on the DTB size.

[0011] To further clarify the advantages and features of the present disclosure, a more particular description of the disclosure will be rendered by reference to specific embodiments thereof, which are illustrated in the appended drawings. It is appreciated that these drawings depict only typical embodiments of the disclosure and are therefore not to be considered limiting of its scope. The disclosure will be described and explained with additional specificity and detail in the accompanying drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Features, aspects, and advantages of embodiments of the disclosure will be described below with reference to the accompanying drawings, in which like reference numerals denote like elements, and wherein:

[0013] FIG. 1 illustrates an architecture of a 5thgeneration (5G) communication network, according to related art;

[0014] FIG. 2 illustrates a block diagram of a 5G communication network, according to an embodiment of the present disclosure;

[0015] FIG.3 illustrates a sequence flow diagram that illustrates one or more operations involved in communication between the first gNB-DU and the second gNB-DU, according to an embodiment of the present disclosure;

[0016] FIGS. 4-5 illustrate flow diagrams depicting methods for communication between the first gNB-DU and the second gNB-DU, according to an embodiment of the present disclosure; and

[0017] FIG. 6 is a diagram of example components of a wireless communication device, according to an embodiment of the present disclosure.DETAILED DESCRIPTION

[0018] The following detailed description of example embodiments refers to the accompanying drawings. The present disclosure provides illustrations and descriptions, but is not intended to be exhaustive or to limit the implementations to the precise form disclosed. Modifications and variations are possible in light of the present disclosure or may be acquired from practice of the implementations. Further, one or more features or components of one embodiment may beincorporated into or combined with another embodiment (or one or more features of another embodiment). Additionally, the flowchart and description of operations provided below relate to at least one of the embodiments in the present disclosure. It should be noted that it is possible to make other embodiments that do not exactly match the flowchart and its description. It is understood that in other embodiments one or more operations may be omitted, one or more operations may be added, one or more operations may be performed simultaneously (at least in part).

[0019] It will be apparent that systems and / or methods, described herein, may be implemented in different forms of hardware, software, or a combination of hardware and software. The actual specialized control hardware or software code used to implement these systems and / or methods should not limit their implementations. Thus, the operation and behavior of the systems and / or methods are described herein without reference to specific software code. It is understood that software and hardware may be designed to implement the systems and / or methods based on the description herein.

[0020] Even though particular combinations of features are recited in the claims and / or disclosed in the specification, the particular combinations are not intended to limit the disclosure of implementations. In fact, many of these features may be combined in ways not specifically recited in the claims and / or disclosed in the specification. Even if a dependent claim directly depends on only one claim, the present disclosure may indicate that the dependent claim is dependent on other claims in the claim set.

[0021] No element, act, or instruction used herein should be construed as critical or essential unless explicitly described as such. Also, as used herein, the articles “a” and “an” (in other words,nouns not mentioned in the plural) are intended to include one or more items, and may be used interchangeably with “one or more.” Also, as used herein, the terms “has,” “have,” “having,” “include,” “including,” or the like are intended to be open-ended terms. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise. Furthermore, expressions such as “at least one of [A] and [B],” “[A] and / or [B],” or “at least one of [A] or [B]” are to be understood as including only A, only B, or both A and B.

[0022] The foregoing disclosure provides illustration and description but is not intended to be exhaustive or to limit the implementations to the precise form disclosed. Modifications and variations are possible in light of the above disclosure or may be acquired from practice of the implementations.

[0023] FIG. 1 illustrates an architecture of a 5thgeneration (5G) communication network 100, in accordance with prior art. As shown in FIG. 1, the communication network 100 includes a 5G Core entity 101 which is connected to a gNodeB (gNB) Centralized Unit (CU) 103, and a plurality of gNB -Distributed Units (DU) 105, 107. The communication network 100 further includes a UE 109 which receives data packets, such as Radio Link Control (RLC) data packets from the plurality of DU 105, 107 through a Media Access Control (MAC) layer. One of the plurality of DUs 105, 107 may be a primary DU, such as a gNB-DUl 105 that may be transmitting RLC data packets to the UE 109 in real time. The UE 107 may be connected to the primary DU1 105 via a primary cell. The UE 109 may also be connected to a secondary DU, i.e., a gNB-DU2 107107. The gNB-DU2 107 may include plurality of secondary cells (for example, a Scell 1 , a Scell2) to communicate with the UE 109. The gNB-DUl 105 includes a scheduler (i.e., scheduler P) to schedule data packets to the UE 109 through a radio link layer (RLC P) and a MAC P. The gNB-DUl 105 also includesa Data Plane Development Kit (DPDK) prioritizer to communicate with the gNB-DU2 107. Each of the secondary cells of the gNB-DU2107 includes a scheduler (i.e., scheduler SCELL1, SCELL2) to schedule RLC data packets to theUE 109 through corresponding MAC (i.e., MACS1, MACS2). The gNB-DU2 107 also includes a DPDK receiver to communicate with the gNB-DUl 105. The UE 109 may include plurality of MAC layer (i.e., MACP, MACS1, MACS2) to communicate with the primary cell and secondary cells. The UE 109 may receive RLC data packets by primary cell and secondary cells simultaneously through inter-DU Carrier Aggregation (CA). In the case of Inter- DU CA operations, the DU peers, i.e., the gNB-DUl 105, the gNB-DU2 107 may communicate with each other in real-time for sending the RLC data packets from a Primary Cell (PCELL) DU Media Access Control (MAC) to a Secondary Cell (SCELL) DU MAC for scheduling RLC data packets. However, there are certain challenges associated with the transmission of the RLC data packets from the PCELL DU MAC, i.e., gNB-DUl 105 to the SCELL DU MAC, i.e., gNB-DU2 107. For instance, real-time control signaling is for evaluating a scheduling capacity of the SCELL based on prevailing channel conditions, as well as for relaying Hybrid Automatic Repeat Request (HARQ) feedback for MAC retransmissions. Furthermore, if an excessive number of packets are sent to the SCELL DU 107 beyond its scheduling capacity, it may result in window stalls at the UE RLC layer and necessitate re-establishments. Conversely, transmitting fewer packets than the SCELL DU 107’ s capacity leads to diminished cell throughput.

[0024] The conventional techniques do not provide any mechanism for efficiently managing the packet transmission between the DUs.

[0025] The present disclosure solves one or more of the above-mentioned problems by effectively and efficiently identifying the buffer capacity of the primary DU and the desired transmission bits(DTB) of the secondary DU. The present disclosure provides a technique that can schedule the transmission of packets between the primary DU and secondary DU based on the identified buffer capacity and DTB to maximize the cell throughput.

[0026] Referring now to the drawings, and more particularly to FIGS. 2 to 6, where similar reference characters denote corresponding features consistently throughout the figures, there are shown preferred embodiments.

[0027] FIG. 2 illustrates a block diagram of a 5G communication network, according to an embodiment of the present disclosure. As shown, the 5G communication network 200 may include a gNB-CU 210 which is connected to a plurality of DUs, i.e., a first gNB-DU 230 and a second gNB-DU 220. The first gNB-DU 230 may include a primary cell that may communicate with the UE in real-time. The second gNB-DU 220 may consist of one or more secondary cells that can transmit data to the UE upon receiving instructions from the first gNB-DU 230. The second gNB-DU 220 may include an apparatus 240 configured to perform operations of the second gNB-DU 220. Accordingly, the apparatus 240240 may correspond to the second gNB-DU 220 (also referred to as a second Distributed Unit (DU) of a gNodeB (gNB)). In one embodiment, the apparatus 240 may be implemented within a network entity, for example, a base station.

[0028] The apparatus 240 may be configured to receive a secondary cell activation command from a primary cell associated with a first DU of the gNB (i.e., the first gNB-DU 230). In one nonlimiting embodiment, the secondary cell activation command may include a small Radio Link Control (RLC) Protocol Data Unit (PDU). For example, the size of the RLC PDU may be small, such as 10 bits in the secondary cell activation command. The size of the RLC PDU may increase if the first gNB-DU 230 keeps transmitting the RLC PDU to the second gNB-DU 220. In responseto receiving the secondary cell activation command, the apparatus 240 may be configured to determine a Desired Transmission Block (DTB) size based on parameters such as, but not limited to, a maximum of a Round-Trip Time (RTT), a Transmission Block Size (TBS), and a SCELL MAC queue depth (QMAC). In an embodiment, the RTT may be indicative of a time measure from a transmission of a data packet from the primary cell to a receipt of an acknowledgment from the at least one secondary cell. The RTT value may be rounded to a nearest slot number. In an embodiment, the RTT value may depend on a distance between the primary cell and the at least one secondary cell. For example, the RTT value may increase with the increase in the distance between the primary cell and the at least one secondary cell. In an embodiment, the apparatus 240 may determine the RTT value by transmitting some dummy packets before receiving the secondary cell activation command. In an embodiment, the TBS corresponds to a maximum number of bits transmitted in a given slot by the at least one secondary cell based on a number of physical resource blocks (PRB) allocated to the at least one secondary cell. The TBS may depend on the channel conditions. For example, if the channel conditions are good, a value of the TBS may be high as a higher number of the PRBs are allocated to the at least one secondary cell. However, the value of TBS decreases with a decrease in the channel conditions as a lesser number of the PRBs may be allocated to the at least one secondary cell. Further, the QMAC may be an indicative of a queue depth of each MAC entity per UE per Logical Channel (LC) associated with the at least one secondary cell. In an embodiment, the apparatus 240 may determine the DTB size based on the following Equation 1 for slot n:

[0029] DTBn= MAX(0, (RTTn*TBSn - QMAC,II ) / RTT„ + TBSn ) . (1)

[0030] The apparatus 240 may be further configured to transmit a secondary cell Uplink (UL) configuration message to the primary cell in response to the received the secondary cell activation command. The secondary cell UL configuration message may include information such as, but not limited to, a Downlink Assignment Index (DAI), a Hybrid Automatic Repeat request (HARQ) size, and the DTB size. The apparatus 240 may further be configured to receive a RLC PDU of an optimal size from the primary cell based on the transmitted secondary cell uplink configuration message. The size of the RLC PDU may be reduced or increased based on at least one DTB size. The apparatus 240 may also be configured to schedule the transmission of the RLC PDU to the UE based on a new QMAC.

[0031] In an embodiment, new QMAC may be determined as follows:

[0032] blew QMAC currentblew ^Rx PCZELL ILLC PDUs enqueued T^B Size scheduled or dequeued. However, the enqueue and dequeue operation happens on the Q directly, so QMAC changes on every scheduling or every packet arrival and becomes a New QMAC.

[0033] The apparatus 240 may include one or more processors 204 (hereinafter referred to as the processor 204), a memory 202, and one or more modules 206. In one embodiment, the processor 204 may include at least one data processor for executing processes in Virtual Storage Area Network. The processor 204 may include specialized processing units such as integrated system (bus) controllers, memory management control units, floating point units, graphics processing units, digital signal processing units, etc. In one embodiment, the processor 204 may include a Central Processing Unit (CPU), a Graphics Processing Unit (GPU), or both. The processor 204 may be one or more general processors, Digital Signal Processors (DSPs), application-specific integrated circuits, Field-Programmable Gate Arrays (FPGAs), servers, networks, digital circuits,analog circuits, combinations thereof, or other now known or later developed devices for analyzing and processing data. The processor 204 may execute a software program, such as code generated manually (i.e., programmed) to perform the desired operation. The processor 204 may implement various techniques such as, but not limited to, image processing, data extraction, Artificial Intelligence (Al), Machine Learning (ML), Deep Learning (DL), and so forth to achieve the desired objective.

[0034] In one embodiment, the processor 204 may be configured to perform the functions of the apparatus 240.

[0035] The memory 202 may be communicatively coupled to the processor 204. The memory 202 may be configured to store data and instructions executable by the processor 204. In one embodiment, the memory 202 may communicate via a bus within the apparatus 240. The memory 202 may include, but is not limited to, a non-transitory computer-readable storage media, such as various types of volatile and non-volatile storage media including, but not limited to, random access memory, read-only memory, programmable read-only memory, electrically programmable read-only memory, electrically erasable read-only memory, flash memory, magnetic tape or disk, optical media and the like. In one example, the memory 202 may include a cache or random-access memory for the processor 204. In alternative examples, the memory 202 is separate from the processor 204, such as a cache memory of a processor, the system memory, or other memory. The memory 202 may be an external storage device or database for storing data. The memory 202 may be operable to store instructions executable by the processor 204. The functions, acts or tasks illustrated in the figures or described may be performed by the programmed processor 204 for executing the instructions stored in the memory 202. The functions, acts or tasks are independentof the particular type of instructions set, storage media, processor or processing strategy and may be performed by software, hardware, integrated circuits, firmware, micro-code and the like, operating alone or in combination. Likewise, processing strategies may include multiprocessing, multitasking, parallel processing, and the like. The memory 202 may further include a database to store the data. Further, the memory 202 may include an operating system for performing one or more tasks of the apparatus 240, as performed by a generic operating system in the communications domain.

[0036] The modules 206, amongst other things, include routines, programs, objects, components, data structures, etc., which perform particular tasks or implement data types. The modules 206 may also be implemented as, signal processor(s), state machine(s), logic circuitries, and / or any other device or component that manipulates signals based on operational instructions. The modules 206 may be configured to one or more operations of the apparatus 240 and / or the processor 204.

[0037] Further, the modules 206 can be implemented in hardware, instructions executed by a processing unit, or by a combination thereof. The processing unit can comprise a computer, the processor 204, a state machine, a logic array, or any other suitable devices capable of processing instructions. The processing unit can be a general-purpose processor which executes instructions to cause the general-purpose processor to perform the required tasks, or the processing unit can be dedicated to performing the required functions. In another embodiment of the present disclosure, the modules 206 may be machine-readable instructions (software) which, when executed by a processor / processing unit, perform any of the described functionalities. Furthermore, the data serves, amongst other things, as a repository for storing data processed, received, and generatedby one or more of the modules. The modules 206 may include a transmitting module 208, a receiving module 212, and a determination module 214.

[0038] The receiving module 212 may be configured to receive a secondary cell activation command from a primary cell associated with a first DU of the gNB (i.e., the first gNB-DU 230). In an embodiment, the receiving module 212 may receive the secondary cell activation command when a buffer occupancy (BO) associated with a RLC buffer of the primary cell is greater than a predefined threshold of the buffer occupancy. For example, let us assume that each cell, i.e., the primary cell and two secondary cells can schedule 400 Mbps of data, i.e., the predefined threshold is 400. Accordingly, if BO>400, then one secondary cell is required. Accordingly, the secondary cell receives the secondary cell activation command. However, if the BO is lOOOgbps, then two secondary cells are required. Hence, the secondary cell activation command is received at two secondary cells of the second DU of gNB (i.e., the second gNB-DU 220). However, if BO is less than the predefined threshold, i.e., BO<400 then the receiving module 212 does not receive the secondary cell activation command from the primary cell. The at least one secondary cell may schedule the RLC PDU transmission to the UE based on original queue depth (QMAC) of the secondary cell. In an embodiment, the secondary cell activation command may comprise the small RLC PDU. As initially, QMAC of the second cell is low, only the small RLC PDU is received at the secondary cell to start the communication. For example, the size of the RLC PDU may be small, such as 10 bits in the secondary cell activation command. Accordingly, the RLD PDU is a single packet of fixed size and its size may be configured by the second gNB-DU 220. The size of the RLC PDU may increase if the first gNB-DU 230 keeps transmitting the RLC PDU to the second gNB-DU 220.

[0039] The transmitting module 208 may be configured to transmit the secondary cell uplink (UL) configuration message to the primary cell in response to receiving the secondary cell activation command. The secondary cell UL configuration message may include information such as, but not limited to, DAI, HARQ size, and DTB size. The HARQ size may depend on the number of layers and the number of TBS to be transmitted.

[0040] In an embodiment, the determination module 214 may be configured to determine the DTB size of the secondary cell based on parameters such as, but not limited to, a maximum of the RTT, TBS, and QMAC. In an embodiment, the determination module 214 may determine the DTB size using the equation (1).

[0041] The receiving module 212 may also be configured to receive the RLC PDU of an optimal size from the primary cell based on the transmitted secondary cell uplink configuration message. In an embodiment, the receiving module 212 may receive the RLC PDU when the DTB>0. However, if the DTB size reduces to zero implying that the channel condition is poor, the reception of the RLC PDU is paused. However, if the channel condition improves and DTB becomes greater than zero, then the receiving module 212 may start receiving the RLC PDU. Further, the size of the RLC PDU may be reduced or increased based on the at least one DTB size. For example, if the DTB size increases implying that the channel conditions are good, then the size of the RLC PDU also increases. However, if the DTB size decreases implying that the channel conditions are deteriorating, the size of the RLC PDU also decreases.

[0042] Referring back to FIG. 2, the first gNB-DU 230 may include an apparatus 250 configured to perform operations of the first gNB-DU 230. Accordingly, the apparatus 250 may correspond to the first gNB-DU 230 (also referred to as a first Distributed Unit (DU) of a gNodeB (gNB)). Inone embodiment, the apparatus 250 may be implemented within a network entity, for example a base station.

[0043] The apparatus 250 may be configured to transmit a secondary cell activation command to at least one secondary cell associated with a second DU of the gNB (i.e., the second gNB-DU 220). In one non-limiting embodiment, the secondary cell activation command may include the small RLC PDU. The small RLC PDU is similar to the RLC PDU as explained in reference to apparatus 240. The apparatus 250 may be further configured to receive the secondary cell UL configuration message in response to the transmitted secondary cell activation command. The secondary cell UL configuration message may include information such as, but not limited to, DAI, HARQ size, and the DTB size. The apparatus 250 may be further configured to determine an optimal size of a RLC PDU based on the received secondary cell uplink configuration message. In particular, the apparatus 250 may determine the optimal size of the RLC PDU based on at least one DTB size. For example, the size of the RLC PDU may be reduced or increased based on at least one the DTB size. The apparatus 250 may then be configured to transmit the RLC PDU of the optimal size to the at least one secondary cell.

[0044] The apparatus 250 may include one or more processors 218 (hereinafter referred to as the processor 218), a memory 216, and one or more modules 222. The architecture and functionalities of the processor 218 and the memory 216 are similar to the processor 204 and the memory 202 of the apparatus 240. Hence, the processor 218 and the memory 216 are not explained here again for the sake of brevity.

[0045] Further, the modules 222 can be implemented in hardware, instructions executed by a processing unit, or by a combination thereof. The processing unit can comprise a computer, theprocessor 218, a state machine, a logic array, or any other suitable devices capable of processing instructions. The processing unit can be a general-purpose processor which executes instructions to cause the general-purpose processor to perform the required tasks, or the processing unit can be dedicated to performing the required functions. In another embodiment of the present disclosure, the modules 222 may be machine-readable instructions (software) which, when executed by a processor / processing unit, perform any of the described functionalities. Furthermore, the data serves, amongst other things, as a repository for storing data processed, received, and generated by one or more of the modules. The modules 222 may include a transmitting module 224, a receiving module 226, and a determination module 228.

[0046] The transmitting module 224 may be configured to transmit the secondary cell activation command to at least one secondary cell associated with the second DU of the gNB (i.e., the second gNB-DU 220). In an embodiment, the transmitting module 224 may transmit the secondary cell activation command (SCELL1 ACT) when the buffer occupancy (BO) associated with the RLC buffer of the primary cell is greater than the predefined threshold. For example, let us assume that each cell, i.e., the primary cell and two secondary cells can schedule 400 Mbps of data, i.e., the predefined threshold is 400. Accordingly, if BO>400, then one secondary cell is required. Hence, the secondary cell receives the secondary cell activation command. However, if BO is below than the predefined threshold, i.e., BO<400 then the transmitting module 224 does not transmit the secondary cell activation command to the at least one secondary cell. In an embodiment, the secondary cell activation command may comprise the small RLC PDU. As initially, QMAC of the second cell is low, only the small RLC PDU is received at the secondary cell to start the communication. For example, the size of the RLC PDU may be small, such as 10 bits in thesecondary cell activation command. Accordingly, the RLD PDU is a single packet of fixed size and its size may be configured by the first gNB-DU 230. The size of the RLC PDU may increase if the first gNB-DU 230 keeps transmitting the RLC PDU to the second gNB-DU 220.

[0047] The receiving module 226 may be configured to receive the secondary cell UL configuration message from the at least one secondary cell in response to transmitting the secondary cell activation command. The secondary cell UL configuration message may include information such as, but not limited to, DAI, HARQ size, and DTB size. The HARQ size may depend on the number of layers and the number of TBS to be transmitted.

[0048] The determination module 228 may be configured to determine an optimal size of the RLC PDU based on the received secondary cell UL configuration message. In an embodiment, the determination module 228 may determine the optimal size of the RLD PDU based on at least one DTB size received in the secondary cell UL configuration message. For example, the size of the RLC PDU may be reduced or increased based on at least one the DTB size. For example, if the DTB size increases implying that the channel conditions are good, then the size of the RLC PDU also increases. However, if the DTB size decreases implying that the channel conditions are deteriorating, the size of the RLC PDU also decreases.

[0049] The transmitting module 224 may also be configured to transmit the RLC PDU of the optimal size to the at least one secondary cell. In a further embodiment, the transmitting module 224 may transmit the RLC PDU when the DTB>0. However, if the DTB size reduces to zero implying that the channel condition is poor, the transmission of the RLC PDU is paused. However, if the channel condition improves and DTB becomes greater than zero, then the transmitting module 224 may resume transmitting the RLC PDU.

[0050] Tn a further embodiment, if a buffer occupancy (BO) associated with a first secondary cell is greater than a first threshold, then the transmission module 224 may transmit the secondary cell activation command to a second secondary cell. For example, let us assume that each cell, i.e., the primary cell and two secondary cells can schedule 400 Mbps of data, i.e., the predefined threshold is 400. Accordingly, if BO>400, then one secondary cell is required. Hence, the secondary cell receives the secondary cell activation command. However, if a buffer occupancy (BOs) of the secondary cell is greater than the first threshold, BOs> 400, then two secondary cells are required. Accordingly, the secondary cell activation command is transmitted to a second secondary cell of the second DU of gNB. It should be noted that even though the transmission of the secondary cell command has been explained with reference to two secondary cells, the transmission module 224 may transmit the secondary cell command to more than two secondary cells based on the amount of data to be transmitted.

[0051] FIG.3 illustrates a sequence flow diagram that illustrates one or more operations involved in communication between the first gNB-DU 302 and the second gNB-DU 304, according to an embodiment of the present disclosure. At operation 301, the first gNB-DU (DU1) 302 may transmit a secondary cell activation command (SCELL ACT CMD) to a first second secondary cell (SCELL 1) 304a. The DU1 302 may include a primary cell (PCELL) 302a. The SCELL 1 304a may be associated with a second gNB-DU (DU2) 304. The DU1 302 may transmit the SCELL ACT CMD, if the BO associated with the primary cell 302a is greater than the predefined threshold. At operation 303, the SCELL1 304a may schedule data packet transmission to the UE based on QMAC. At operation 305, the SCELL1 304a may transmit the secondary cell UL configuration message to the primary cell 302a. The secondary cell UL configuration message may include, butnot limited to, a DAI, HARQ size, and DTB size. At operation 307, the PCELL 302a may transmit the RLC PDU of optimal size to the SCELL1 304a. The PCELL 302a may only transmit the RLC PDU of optimal size if the DTB associated with the SCELL1 304a is greater than zero (also referred to as a start phase). However, if the DTB is reduced to zero, then the PCELL 302a stops transmitting the RLC PDU (also referred to as a pause phase). The PCELL 302a may again resume transmitting the RLC PDU when the DTB becomes greater than zero (also referred to as a resume phase). At operation 309, the SCELL1 304a may schedule data packet transmission to the UE based on the new QMAC.

[0052] Further, if the BO associated with the SCELL1 304a is greater than the first predefined threshold, then at operation 311, the PCELL 302a may transmit the secondary cell activation command to a second secondary cell (SCELL2) 304b. At operation 313, the SCELL1 304a may schedule data packet transmission to the UE based on QMAC. At operation 315, the SCELL2304b may transmit the secondary cell UL configuration message to the primary cell 302a. The secondary cell UL configuration message may include but is not limited to, a DAI, HARQ size, and DTB size. At operation 317, the PCELL 302a may transmit the RLC PDU of optimal size to the SCELL2 304b. The PCELL 302a may only transmit the RLC PDU of optimal size if the DTB associated with the SCELL2 304b is greater than zero. At operation 319, the SCELL2 304b may schedule data packet transmission to the UE based on the new QM C.

[0053] FIG. 4 illustrates a flowchart depicting a method 400 for receiving RLC PDU from the first gNB-DU, according to an embodiment of the present disclosure. The method 400 may be performed by the apparatus 240.

[0054] At step 401 , the method 400 may include receiving the secondary cell activation command fromthe primary cell associated with the first DU of the gNB (i.e., first gNB-DU 230). The secondary cell activation command comprises the small RLC PDU. The secondary cell activation command may be received when the buffer occupancy associated with the primary cell is greater than the predefined threshold of the buffer occupancy.

[0055] At step 403, the method 400 may include transmitting the secondary cell UL configuration message to the primary cell in response to the received the secondary cell activation command. The secondary cell uplink configuration message may comprise but is not limited to a DAI, a HARQ size, and a DTB size. In a further embodiment, the method 400 may include determining the DTB size based on parameters such as, but not limited to, a maximum of RTT, TBS, and a Scell QMAC. In an embodiment, the RTT may be indicative of a time measure from a transmission of a data packet from the primary cell to a receipt of an acknowledgment from the at least one secondary cell. The RTT value may be rounded to a nearest slot number. In an embodiment, the TBS may correspond to a maximum number of bits transmitted in a given slot by the at least one secondary cell. The TBS may be based on a number of physical resource blocks allocated to the at least one secondary cell. In a further embodiment, the QMAC may be indicative of a queue depth of each MAC entity per UE per LC associated with the at least one secondary cell.

[0056] At step 405, the method 400 may include receiving the RLC PDU of an optimal size from the primary cell based on the transmitted secondary cell UL configuration message. The size of the RLC PDU may be reduced or increased based on at least one DTB size.

[0057] While the above-discussed steps in FIG. 4 are shown and described in a particular sequence, the steps may occur in variations to the sequence in accordance with variousembodiments. Further, a detailed description related to the various steps of FIG. 4 is already covered in the description related to FIGS. 2 and 3 and is omitted herein for the sake of brevity.

[0058] FIG. 5 illustrates a flowchart depicting a method 500 for receiving RLC PDU from a first gNB-DU, according to an embodiment of the present disclosure. The method 500 may be performed by the apparatus 250.

[0059] At step 501, the method 500 may include transmitting the secondary cell activation command to the at least one secondary cell associated with the second DU of the gNB (i.e., the second gNB-DU 220). The secondary cell activation command may comprise the small RLC PDU. The secondary cell activation command may be transmitted when a buffer occupancy associated with the primary cell is greater than a predefined threshold of the buffer occupancy. In a further embodiment, the secondary cell activation command may be transmitted when the buffer occupancy associated with the primary cell is greater than the predefined threshold and DTB size is greater than zero.

[0060] At step 503, the method 500 may include receiving the secondary cell UL configuration message to the primary cell in response to the transmitted secondary cell activation command. The secondary cell uplink configuration message may comprise but is not limited to, a DAI, a HARQ size, and a DTB size.

[0061] At step 505, the method 500 may include determining the optimal size of the RLC PDU based on the received secondary cell UL configuration message. The size of the RLC PDU may be reduced or increased based on at least one the DTB size.

[0062] At step 507, the method 500 may include transmitting the RLC PDU of the optimal size to the at least one secondary cell.

[0063] While the above-discussed steps in FIG. 5 are shown and described in a particular sequence, the steps may occur in variations to the sequence in accordance with various embodiments. Further, a detailed description related to the various steps of FIG. 5 is already covered in the description related to FIGS. 2 and 3 and is omitted herein for the sake of brevity.

[0064] FIG. 6 is a diagram of example components of a wireless communication device 600 (also referred to as the device / apparatus 600), in accordance with an embodiment of the present disclosure. In one or more embodiments, the wireless communication device 600 may correspond to a wireless server and / or the apparatus 240, 250. As shown in FIG. 6, the device 600 includes a processor 610, a memory 620, a storage component 630, an input component 640, an output component 650, a communication interface 660, and a bus 670.

[0065] The processor 610, as used herein, means any type of computational circuit that may comprise hardware elements and software elements. The processor 610 may be embodied as a multi-core processor, a single-core processor, or a combination of one or more multi-core processors and / or one or more single-core processors, a distributed processing system, or the like. The processor 610 may be a Central Processing Unit (CPU), a Graphics Processing Unit (GPU), an Accelerated Processing Unit (APU), an Application-Specific Integrated Circuit (ASIC), or another type of processing component.

[0066] The memory 620 includes a non-transitory computer-readable medium. The memory 620 includes a Random-Access Memory (RAM), a Read Only Memory (ROM), and / or another type of dynamic or static storage device (e.g., a flash memory, a magnetic memory, and / or an optical memory) that stores information and / or instructions for use by the processor 610. The memory 620 comprises machine-readable instructions which are executable by the processor 610. Thesemachine-readable instructions when executed by the processor 610 cause the processor 610 to perform one or more method steps of an embodiment described above.

[0067] The storage component 630 stores information and / or software related to the operation and use of the device 600. For example, the storage component 630 may include a hard disk (e.g., a magnetic disk, an optical disk, a magneto-optic disk, and / or a solid-state disk), a Compact Disc (CD), a Digital Versatile Disc (DVD), a floppy disk, a cartridge, a magnetic tape, and / or another type of non-transitory computer-readable medium, along with a corresponding drive.

[0068] The input component 640 is configured to receive information, such as user input. For example, the input component 640 may include, but not be limited to, a touch screen display, a keyboard, a keypad, a mouse, a button, a switch, and / or a microphone. Additionally, or alternatively, the input component 640 may include a sensor for sensing information (e.g., a Global Positioning System (GPS), an accelerometer, a gyroscope, and / or an actuator).

[0069] The output component 650 is configured to provide output information from the device 600. For example, the output component 650 maybe, but is not limited to, a display, a speaker, an instruction device to an external device, and / or one or more Light-Emitting Diodes (LEDs).

[0070] The communication interface 660 is an interface that provides a communication connection to other devices, such as external devices and internal devices. The connection by the communication interface 660 can be a wired connection, a wireless connection, or a combination of wired and wireless connections, and can be a direct connection or an indirect connection via a communication network that exists between the device 600 and other devices. In other words, the standard of the communication interface 660 is not limited.

[0071] The bus 670 acts as an interconnect between the processor 610, the memory 620, the storage component 630, the input component 640, the output component 650, and the communication interface 660 of the device 600. The bus 670 may include a wired interconnection or a wireless interconnection

[0072] The number and arrangement of components shown in FIG. 6 are provided as an example. In practice, the device 600 may include additional components, fewer components, different components, or differently arranged components than those shown in FIG. 6. Additionally, or alternatively, a set of components (e.g., one or more components) of the device 600 may perform one or more functions described as being performed by another set of components of the device 600. Further, one or more method steps described in any of the embodiments may be performed utilizing a plurality of devices 600 in communication with one another.

[0073] It is understood that terms including “unit” or “module” at the end may refer to the unit for processing at least one function or operation and may be implemented in hardware, software, or a combination of hardware and software.

[0074] In one embodiment, a method is described. The method includes receiving, by at least one secondary cell associated with a second Distributed Unit (DU) of a gNodeB (gNB), a secondary cell activation command from a primary cell associated with a first DU of the gNB, wherein the secondary cell activation command comprises a small Radio Link Control (RLC) Protocol Data Unit (PDU). The method includes in response to the received the secondary cell activation command, transmitting, by the at least one secondary cell, a secondary cell uplink configuration message to the primary cell, wherein the secondary cell uplink configuration message comprises at least one of a Downlink Assignment Index (DAI), a Hybrid Automatic Repeat request (HARQ)size, and a Desired Transmission Block (DTB) size. The method further includes receiving, by the at least one secondary cell, a RLC PDU of an optimal size from the primary cell based on the transmitted secondary cell uplink configuration message, wherein a size of the RLC PDU is reduced or increased based on at least one DTB size.

[0075] The method as described in

[0069] , wherein for transmitting the second cell uplink configuration message, the method comprises:

[0076] determining, by the at least one secondary cell, the DTB size based on at least one of a maximum of a Round-Trip Time (RTT), a Transmission Block Size (TBS), and a Scell MAC queue depth (QMAC).

[0077] The method as described in any one of

[0069] -

[0070] , wherein the RTT is indicative of a time measure from a transmission of a data packet from the primary cell to a receipt of an acknowledgment from the at least one secondary cell with an RTT value rounded to a nearest slot number.

[0078] The method as described in any one of

[0069] -

[0071] , wherein the TBS corresponds to a maximum number of bits transmitted in a given slot by the at least one secondary cell based on a number of physical resource blocks allocated to the at least one secondary cell.

[0079] The method as described in any one of

[0069] -

[0072] , wherein the QMAC is indicative of a queue depth of each Media Access Control (MAC) entity per user equipment (UE) per logical channel (LC) associated with the at least one secondary cell.

[0080] The method as described in any one of

[0069] -

[0073] , wherein receiving the secondary cell activation command comprises:

[0081] receiving the secondary cell activation command when a buffer occupancy associated with the primary cell is above greater than a predefined threshold of the buffer occupancy.

[0082] In another embodiment, a method is described. The method includes transmitting, by a primary cell associated with a first Distributed Unit (DU) of a gNodeB (gNB), a secondary cell activation command to at least one secondary cell associated with a second DU of the gNB, wherein the secondary cell activation command comprises a small Radio Link Control (RLC) Protocol Data Unit (PDU). The method includes in response to the transmitted secondary cell activation command, receiving, by the primary cell, a secondary cell uplink configuration message from the at least one secondary cell, wherein the secondary cell uplink configuration message comprises at least one of a Downlink Assignment Index (DAI), a Hybrid Automatic Repeat request (HARQ) size, and a Desired Transmission Block (DTB) size. The method further includes determining an optimal size of a RLC PDU based on the received secondary cell uplink configuration message, wherein a size of the RLC PDU is reduced or increased based on at least one the DTB size. The method also includes transmitting, by the primary cell, the RLC PDU of the optimal size to the at least one secondary cell.

[0083] The method as described in

[0075] , wherein for transmitting, by a primary cell, the secondary cell activation command to the at least one secondary cell, the method comprises:

[0084] determining whether a buffer occupancy associated with the primary cell is greater than a predefined threshold of the buffer occupancy; and

[0085] in response to determining that the buffer occupancy associated with the primary cell is greater than the predefined threshold, transmitting, by the primary cell, the secondary cell activation command to the at least one secondary cell.

[0086] The method as described in any one of

[0075] -

[0076] , comprising:

[0087] in response to the transmitted secondary cell activation command, receiving, by the primary cell, the secondary cell uplink configuration message from the at least one secondary cell when a buffer occupancy associated with the primary cell is greater than a predefined threshold and the DTB size is greater than zero.

[0088] In another embodiment, an apparatus is described. The apparatus is configured to receive a secondary cell activation command from a primary cell associated with a first DU of the gNB, wherein the secondary cell activation command comprises a small Radio Link Control (RLC) Protocol Data Unit (PDU). The apparatus is configured to, in response to the received the secondary cell activation command, transmitting a secondary cell uplink configuration message to the primary cell, wherein the secondary cell uplink configuration message comprises at least one of a Downlink Assignment Index (DAI), a Hybrid Automatic Repeat request (HARQ) size, and a Desired Transmission Block (DTB) size. The apparatus is further configured to receive a RLC PDU of an optimal size from the primary cell based on the received secondary cell uplink configuration message, wherein a size of the RLC PDU is reduced or increased based at least one the DTB size.

[0089] The apparatus as described in

[0078] , wherein for transmitting the second cell uplink configuration message, the apparatus is configured to:

[0090] determine the DTB size based on at least one of a maximum of a Round-Trip Time (RTT), a Transmission Block Size (TBS), and a Scell MAC queue depth (QMAC).

[0091] The apparatus as described in any one of

[0078] -

[0079] , wherein the RTT is indicative of a time measure from a transmission of a data packet from the primary cell to a receipt of anacknowledgment from the at least one secondary cell with an RTT value rounded to a nearest slot number.

[0092] The apparatus as described in any one of

[0078] -

[0080] , wherein the TBS corresponds to a maximum number of bits transmitted in a given slot by the at least one secondary cell based on a number of physical resource blocks allocated to the at least one secondary cell.

[0093] The apparatus as described in any one of

[0078] -

[0081] , wherein the QMAC is indicative of a queue depth of each Media Access Control (MAC) entity per user equipment (UE) per logical channel (LC) associated with the at least one secondary cell.

[0094] The apparatus as described in any one of

[0078] -

[0082] , wherein the apparatus is configured to receive the secondary cell activation command when a buffer occupancy associated with the primary cell is greater than a predefined threshold of the buffer occupancy.

[0095] The apparatus as described in any one of

[0078] -

[0083] , wherein the apparatus corresponds to a second DU.

[0096] In another embodiment, an apparatus is described. The apparatus is configured to transmit a secondary cell activation command to at least one secondary cell associated with a second DU of the gNB, wherein the secondary cell activation command comprises a small Radio Link Control (RLC) Protocol Data Unit (PDU). The apparatus is configured to, in response to the transmitted secondary cell activation command, receive a secondary cell uplink configuration message from the at least one secondary cell, wherein the secondary cell uplink configuration message comprises at least one of a Downlink Assignment Index (DAI), a Hybrid Automatic Repeat request (HARQ) size, and a Desired Transmission Block (DTB) size. The apparatus is further configured to determine an optimal size of a RLC PDU based on the received secondary cell uplink configurationmessage, wherein a size of the RLC PDU is reduced or increased based on at least one the DTB size. The apparatus is configured to transmit the RLC PDU of the optimal size to the at least one secondary cell.

[0097] The apparatus as described in

[0085] , wherein to transmit the secondary cell activation command to the at least one secondary cell, the apparatus is configured to:

[0098] determine whether a buffer occupancy associated with the primary cell is greater than a predefined threshold of a buffer occupancy; and

[0099] in response to determining that the buffer occupancy associated with the primary cell is greater than the predefined threshold, transmitting, by the primary cell, the secondary cell activation command to the at least one secondary cell.

[0100] The apparatus as described in any one of

[0085] -

[0086] , the apparatus is configured to:

[0101] in response to the transmitted secondary cell activation command, receive the secondary cell uplink configuration message from the at least one secondary cell when a secondary cell activation buffer occupancy associated with the at least one secondary cell is greater than a predefined threshold and the DTB size is greater than zero.

[0102] The apparatus as described in any one of

[0085] -

[0087] , wherein the apparatus corresponds to a first DU.

[0103] In one embodiment, a non-transitory computer-readable medium storing instructions is described. The instructions comprising one or more instructions that, when executed by an apparatus, the apparatus comprising one or more processors, cause the one or more processors to: receive a secondary cell activation command from a primary cell associated with a first DU of the gNB, wherein the secondary cell activation command comprises a small Radio Link Control (RLC)Protocol Data Unit (PDU). The instructions cause the one or more processor to, in response to the received the secondary cell activation command, transmit a secondary cell uplink configuration message to the primary cell, wherein the secondary cell uplink configuration message comprises at least one of a Downlink Assignment Index (DAI), a Hybrid Automatic Repeat request (HARQ) size, and a Desired Transmission Block (DTB) size. The instructions cause the one or more processors to receive a RLC PDU of an optimal size from the primary cell based on the received secondary cell uplink configuration message, wherein a size of the RLC PDU is reduced or increased based at least one the DTB size.

[0104] Accordingly, the present disclosure provide techniques for transmitting the RLD PDU by both the primary cell and at least one secondary, resulting in CA. Thus, the present disclosure provides techniques for inter-DU flow control for CA.

[0105] Embodiments of the present disclosure offer several significant commercial and technical advantages, for example:

[0106] Enhanced data processing speed: Data Plane Development Kit (DPDK) prioritized buffers facilitate faster data packet delivery and real-time processing, improving overall network performance and reducing latency.

[0107] Improved coordination between cells: Allowing Secondary Cells (SCELLs) to share the Desired Transmission Block (DTB) with the Primary Cell (PCELL) enables more effective coordination, ensuring that necessary Radio Link Control (RLC) packets are sent efficiently.

[0108] While specific language has been used to describe the disclosure, any limitations arising on account of the same are not intended. As would be apparent to a person in the art, variousworking modifications may be made to the method in order to implement the inventive concept as taught herein.

[0109] The drawings and the forgoing description give examples of embodiments. Those skilled in the art will appreciate that one or more of the described elements may well be combined into a single functional element. Alternatively, certain elements may be split into multiple functional elements. Elements from one embodiment may be added to another embodiment. For example, orders of processes described herein may be changed and are not limited to the manner described herein.

[0110] Moreover, the actions of any flow diagram need not be implemented in the order shown; nor do all of the acts necessarily need to be performed. Also, those acts that are not dependent on other acts may be performed in parallel with the other acts. The scope of embodiments is by no means limited by these specific examples. Numerous variations, whether explicitly given in the specification or not, such as differences in structure, dimension, and use of material, are possible. The scope of embodiments is at least as broad as given by the following claims.

[0111] Benefits, other advantages, and solutions to problems have been described above with regard to specific embodiments. However, the benefits, advantages, solutions to problems, and any component(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature or component of any or all the claims.

[0112] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and / or adapt for various applications such specific embodiments without departing from thegeneric concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of at least one embodiment, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.

Claims

CLAIMSWe Claim:1 A method comprising:receiving, by at least one secondary cell associated with a second Distributed Unit (DU) of a gNodeB (gNB), a secondary cell activation command from a primary cell associated with a first DU of the gNB, wherein the secondary cell activation command comprises a small Radio Link Control (RLC) Protocol Data Unit (PDU);in response to the received the secondary cell activation command, transmitting, by the at least one secondary cell, a secondary cell uplink configuration message to the primary cell, wherein the secondary cell uplink configuration message comprises at least one of a Downlink Assignment Index (DAI), a Hybrid Automatic Repeat request (HARQ) size, and a Desired Transmission Block (DTB) size; andreceiving, by the at least one secondary cell, a RLC PDU of an optimal size from the primary cell based on the transmitted secondary cell uplink configuration message, wherein a size of the RLC PDU is reduced or increased based on at least one DTB size.2 The method according to claim 1, wherein for transmitting the second cell uplink configuration message, the method comprises:determining, by the at least one secondary cell, the DTB size based on at least one of a maximum of a Round-Trip Time (RTT), a Transmission Block Size (TBS), and a Scell MAC queue depth (QMAC).

3. The method according to claim 2, wherein the RTT is indicative of a time measure from a transmission of a data packet from the primary cell to a receipt of an acknowledgment from the at least one secondary cell with an RTT value rounded to a nearest slot number.4 The method according to claim 2, wherein the TBS corresponds to a maximum number of bits transmitted in a given slot by the at least one secondary cell based on a number of physical resource blocks allocated to the at least one secondary cell.5 The method according to claim 2, wherein the QMAC is indicative of a queue depth of each Media Access Control (MAC) entity per user equipment (UE) per logical channel (LC) associated with the at least one secondary cell.6 The method as claimed in claim 1, wherein receiving the secondary cell activation command comprises:receiving the secondary cell activation command when a buffer occupancy associated with the primary cell is greater than a predefined threshold of the buffer occupancy.7 A method comprising:transmitting, by a primary cell associated with a first Distributed Unit (DU) of a gNodeB (gNB), a secondary cell activation command to at least one secondary cell associated with a second DU of the gNB, wherein the secondary cell activation command comprises a small Radio Link Control (RLC) Protocol Data Unit (PDU);in response to the transmitted secondary cell activation command, receiving, by the primary cell, a secondary cell uplink configuration message from the at least one secondary cell, wherein the secondary cell uplink configuration message comprises at least one of a Downlink Assignment Index (DAI), a Hybrid Automatic Repeat request (HARQ) size, and a Desired Transmission Block (DTB) size;determining an optimal size of a RLC PDU based on the received secondary cell uplink configuration message, wherein a size of the RLC PDU is reduced or increased based on at least one the DTB size; andtransmitting, by the primary cell, the RLC PDU of the optimal size to the at least one secondary cell.The method according to claim 6, wherein for transmitting, by a primary cell, the secondary cell activation command to the at least one secondary cell, the method comprises:determining whether a buffer occupancy associated with the primary cell is greater than a predefined threshold of the buffer occupancy; andin response to determining that the buffer occupancy associated with the primary cell is greater than the predefined threshold, transmitting, by the primary cell, the secondary cell activation command to the at least one secondary cell.The method according to claim 6, comprising:in response to the transmitted secondary cell activation command, receiving, by the primary cell, the secondary cell uplink configuration message from the at least one secondary cellwhen a buffer occupancy associated with the primary cell is greater than a predefined threshold and the DTB size is greater than zero.An apparatus, the apparatus being configured to:receive a secondary cell activation command from a primary cell associated with a first DU of the gNB, wherein the secondary cell activation command comprises a small Radio Link Control (RLC) Protocol Data Unit (PDU);in response to the received the secondary cell activation command, transmit a secondary cell uplink configuration message to the primary cell, wherein the secondary cell uplink configuration message comprises at least one of a Downlink Assignment Index (DAI), a Hybrid Automatic Repeat request (HARQ) size, and a Desired Transmission Block (DTB) size; and receive a RLC PDU of an optimal size from the primary cell based on the received secondary cell uplink configuration message, wherein a size of the RLC PDU is reduced or increased based at least one the DTB size.The apparatus according to claim 10, wherein for transmitting the second cell uplink configuration message, the apparatus is configured to:determine the DTB size based on at least one of a maximum of a Round-Trip Time (RTT), a Transmission Block Size (TBS), and a Scell MAC queue depth (QMAC).

12. The apparatus according to claim 11, wherein the RTT is indicative of a time measure from a transmission of a data packet from the primary cell to a receipt of an acknowledgment from the at least one secondary cell with an RTT value rounded to a nearest slot number.

13. The apparatus according to claim 11, wherein the TBS corresponds to a maximum number of bits transmitted in a given slot by the at least one secondary cell based on a number of physical resource blocks allocated to the at least one secondary cell and wherein the QMAC is indicative of a queue depth of each Media Access Control (MAC) entity associated with the at least one secondary cell.

14. The apparatus according to claim 10, wherein the apparatus is configured to receive the secondary cell activation command when a buffer occupancy associated with the primary cell is greater than a predefined threshold of the buffer occupancy.

15. The apparatus according to claim 10, wherein the apparatus corresponds to a second DU.

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