Transmission of channel state information reference signal

Abstract

Generally, the subject matter of this disclosure relates to transmission of a channel state information reference signal (CSI RS). In some implementations, a message can be received at a wireless unit (RU) of a base station in a wireless communication system. The message can include CSI RS configuration information that the RU is configured to use in generating a channel state information reference signal (CSI RS) for transmission to a user equipment (UE). The CSI RS configuration information can include multiple parameters, including bandwidth, amplitude scaling, and scrambling identification (ID) for the CSI RS transmission.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to Indian Patent Application No. 202241063907 to Raghavendra Ramakrishna et al., entitled "Transmission of Channel State Information Reference Signals," filed on November 9, 2022, the disclosure of which is incorporated herein by reference in its entirety.

[0002] In some implementations, the subject matter of this disclosure relates to telecommunications systems, and in particular to the transmission of channel state information reference signals (CSI RS). [Background technology]

[0003] In today's world, cellular networks provide on-demand communication capabilities to individuals and businesses. Typically, cellular networks are wireless networks that can be distributed over land areas called cells. Each such cell is served by at least one fixed-location transceiver called a cell site or base station. Each cell can use a different set of frequencies from its neighboring cells to avoid interference and provide improved service within each cell. When combined, multiple cells provide wireless coverage over a wide geographic area, allowing numerous mobile phones and / or other wireless devices or portable transceivers to communicate with each other and with fixed transceivers and phones elsewhere in the network. Such communication is performed through base stations and is achieved even when mobile transceivers are traveling through two or more cells during transmission. Major wireless communication providers have deployed such cell sites worldwide, allowing mobile phones and mobile computing devices to connect to the public switched telephone network and the public Internet.

[0004] A mobile phone is a portable telephone that can receive and / or make calls and / or data communications through a cell site or transmission tower by using radio waves to transmit and receive signals from the device (mobile phone). Given the large number of mobile phone users, current mobile phone networks offer limited shared resources. In that regard, cell sites and handsets can change frequencies and use low-power transmitters to allow simultaneous use of the network by many callers with less interference. Cell site coverage can depend on a particular geographic location and / or the number of users that can potentially use the network. For example, in urban areas, a cell site may have a range of up to about 1 / 2 mile (1 mile = 1609 meters), while in rural areas, the range may be as long as 5 miles. In some areas, users can receive signals from cell sites as far away as 25 miles.

[0005] The following are some examples of digital cellular technologies used by communication providers: Global System for Mobile Communications (GSM), General Packet Radio Service (GPRS), cdmaOne, CDMA2000, Evolution-Data Optimized (EV-DO), Enhanced Data Rates for GSM Evolution (EDGE), Universal Mobile Telecommunications System (UMTS), Digital Enhanced Cordless Telecommunications (DECT), Digital AMPS (IS-136 / TDMA), and Integrated Digital Enhanced Network (iDEN). Developed by the Third Generation Partnership Project (3GPP®) standards organization, Long Term Evolution, or 4G LTE, is a standard for high-speed data wireless communications for mobile phones and data terminals. 5G standards are currently being developed and deployed. 3GPP cellular technologies such as LTE and 5G NR are an evolution of earlier generations of 3GPP technologies such as GSM / EDGE and UMTS / HSPA digital cellular technologies, allowing for increased capacity and speeds by using a different air interface along with improvements to the core network.

[0006] A cellular network can be divided into a radio access network and a core network. The radio access network (RAN) can include network functions capable of handling radio layer communication processing. The core network can include network functions capable of handling higher layer communications, such as internet protocol (IP), transport layers, and application layers. In some cases, the RAN functions can also be divided into baseband unit functions and radio unit functions; for example, a radio unit connected to a baseband unit via a fronthaul network can be responsible for lower layer processing of the radio physical layer, and the baseband unit can be responsible for higher layer radio protocols, such as MAC, RLC, etc.

[0007] Various data can be transmitted over the fronthaul network. However, the fronthaul network has a limited amount of bandwidth. If data traffic becomes too high over the fronthaul network, data packets may be dropped, thereby adversely affecting service on the cellular network. Summary of the Invention

[0008] In some implementations, the subject matter of this disclosure relates to a computer-implemented method that can include receiving, at a radio unit (RU) of a base station in a wireless communication system, a message including channel state information reference signals (CSI RS) configuration information configured for use by the RU in generating CSI RSs for transmission to user equipment (UE). The CSI RS configuration information can include multiple parameters including bandwidth, amplitude scaling, and scrambling identification (ID) for the CSI RS transmission.

[0009] The method may enable an RU to generate a CSI RS and receive all parameters necessary to map the CSI RS to resource elements (REs). Thus, for multi-port CSI transmission, in which multiple CSI RS ports are used for signal transmission, the CSI RS may be generated by the RU with less traffic on the fronthaul network between the RU and a base station distributed unit (DU) than is traditionally required for multi-port CSI RS transmission. Thus, data packets may be less likely to be dropped on the fronthaul network due to bandwidth issues.

[0010] In some implementations, the subject matter of this disclosure can include one or more of the following optional features.

[0011] In some implementations, the message may be a control plane (C-plane) message. Further, the message may be of a section or section extension type that defines multiple parameters included in the CSI RS configuration information, and / or the message may be sent from a DU of a base station to an RU, and the message may provide real-time C-plane control to the RU.

[0012] In some implementations, the message may be a management plane (M-plane) message. Additionally, the RU may indicate support for CSI RS configuration information in a feature within the YANG model.

[0013] In some implementations, the parameters may also include a port, a density, a code division multiplexing type, an orthogonal frequency-division multiplexing (OFDM) symbol number within a slot, a slot number within a radio frame, and a number of OFDM symbols per slot.

[0014] In some implementations, the multiple parameters may include all parameters necessary for the RU to generate a CSI RS for transmission to the UE.

[0015] In some implementations, the CSI RS may be generated at the RU using CSI RS configuration information, and the generated CSI RS may be transmitted from the RU to the UE. Furthermore, after transmitting the generated CSI RS, the CSI may be received from the UE at the RU, and the RU may transmit the CSI to the DU for decoding.

[0016] In some implementations, the wireless communication system may be an LTE communication system or a 5G communication system.

[0017] In some implementations, the base station may be an eNodeB or a gNodeB.

[0018] Non-transitory computer program products (i.e., physically embodied computer program products) that store instructions that, when executed by one or more data processors in one or more computing systems, cause at least one data processor to perform the process operations described herein are also described. Similarly, computer systems that may include one or more data processors and memory coupled to the one or more data processors are also described. The memory may store, on a temporary or permanent basis, instructions that cause at least one processor to perform one or more of the operations described herein. In addition, the methods may be implemented by one or more data processors within a single computing system or distributed across two or more computing systems. Such computing systems may be connected via one or more connections, including, but not limited to, connections via a network (e.g., the Internet, a wireless wide area network, a local area network, a wide area network, a wired network, etc.), direct connections between one or more of the computing systems, etc., and may exchange data and / or commands or other instructions.

[0019] The details of one or more variations of the subject matter described herein are set forth in the accompanying drawings and the description below. Other features and advantages of the subject matter described herein will become apparent from the following description and accompanying drawings, and from the claims. [Brief explanation of the drawings]

[0020] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate certain aspects of the subject matter disclosed herein and, together with the description, help to explain some of the principles associated with the disclosed implementations.

[0021] [Figure 1a] FIG. 1 illustrates an exemplary conventional Long Term Evolution (LTE) communication system.

[0022] [Figure 1b] FIG. 1b illustrates further details of the exemplary LTE system shown in FIG. 1a.

[0023] [Figure 1c] FIG. 1B illustrates further details of the evolved packet core of the exemplary LTE system shown in FIG. 1A.

[0024] [Figure 1d] FIG. 1B illustrates an exemplary evolved Node B of the exemplary LTE system shown in FIG. 1a.

[0025] [Figure 2] FIG. 2 shows further details of the evolved Node B shown in FIGS. 1a to 1d.

[0026] [Figure 3] FIG. 1 illustrates an example virtual radio access network in accordance with some implementations of the subject matter of this disclosure.

[0027] [Figure 4] FIG. 1 illustrates an exemplary 3GPP split architecture for providing use of higher frequency bands to its users.

[0028] [Figure 5a] FIG. 1 illustrates an exemplary 5G wireless communication system.

[0029] [Figure 5b] A diagram illustrating an example layer architecture of a split gNB and / or a split ng-eNB (e.g., a next-generation eNB that may be connected to 5GC).

[0030] [Figure 5c] A diagram illustrating an exemplary functional division in the gNB architecture shown in Figures 5a-5b.

[0031] [Figure 6] FIG. 1 illustrates an exemplary method according to some implementations of the subject matter of this disclosure.

[0032] [Figure 7] A diagram showing an example C-plane frame format in accordance with some implementations of the subject matter of this disclosure.

[0033] [Figure 8] FIG. 1 illustrates an exemplary system in accordance with some implementations of the subject matter of this disclosure.

[0034] [Figure 9] FIG. 10 illustrates another exemplary method according to some implementations of the subject matter of this disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0035] The subject matter of the present disclosure can provide systems and methods that can be implemented in wireless communication systems, including 5G New Radio communication systems, Long Term Evolution communication systems, and the like.

[0036] Generally, the subject matter of this disclosure relates to transmission of channel state information reference signals (CSI RS).

[0037] In some implementations of the subject matter of this disclosure, a radio unit (RU) of a base station in a wireless communication system can be configured to generate a CSI RS using configuration information provided to the RU. The configuration information can include all parameters necessary for the RU to generate a CSI RS and map the CSI RS to resource elements (REs). Thus, in the case of multi-port CSI transmission in which multiple CSI RS ports are used for signal transmission, the CSI RS can be generated by the RU with less traffic on the fronthaul network between the RU and the distributed unit (DU) of the base station than traditionally required for multi-port CSI RS transmission. Thus, data packets may be less likely to be dropped on the fronthaul network due to bandwidth issues. Traditionally, CSI RS signals can generate instantaneous peak traffic that can adjust the bandwidth limitations of the fronthaul network because each port of the CSI RS is transmitted over the entire bandwidth using control plane (C-plane) and user plane (U-plane) data packets.

[0038] The RU may also be configured to transmit the generated CSI RS to a user equipment (UE) and receive CSI from the UE in response. Generally, the CSI measures the quality of the downlink channel between the UE and the base station in accordance with 3GPP standards and includes, for example, parameters such as a Channel Quality Indicator (CQI), a Precoding Type Indicator (PTI), a Precoding Matrix Indicator (PMI), a Rank Indicator (RI), and a Layer Indicator (LI). The base station may use the CSI received from the UE in various ways in accordance with 3GPP standards, such as in scheduling and resource allocation, to improve service to the UE.

[0039] 3GPP standards that define one or more aspects that may be related to the subject matter of this disclosure include 3GPP TS 38.211 "NR; Physical channels and modulation" and 3GPP TS 38.214 "NR; Physical layer procedures for data." O-RAN Alliance standards, such as the O-RAN Working Group 4 "Control, User and Synchronization Plane Specification" and the O-RAN Working Group 4 "Management Plane Specification," may also be related to one or more aspects of the subject matter of this disclosure.

[0040] One or more aspects of the subject matter of this disclosure may be incorporated into transmitter and / or receiver components of a base station (e.g., gNodeB, eNodeB, etc.) within such a communication system. The following is a general discussion of Long Term Evolution and 5G New Radio communication systems.

[0041] I. Long Term Evolution Communication System 1a-1c and 2 illustrate an exemplary conventional Long Term Evolution (LTE) communication system 100 along with its various components. The LTE system, or 4G LTE, as it is commercially known, is governed by a standard for high-speed data wireless communication for mobile phones and data terminals. The standard is an evolution of GSM / EDGE (Global System for Mobile Communications / Enhanced Data Rates for GSM Evolution) and UMTS / HSPA (Universal Mobile Telecommunications System / High-Speed ​​Packet Access) network technologies. The standard was developed by 3GPP (Third Generation Partnership Project).

[0042] As shown in FIG. 1a, system 100 may include an evolved universal terrestrial radio access network (EUTRAN) 102, an evolved packet core (EPC) 108, and a packet data network (PDN) 101, where EUTRAN 102 and EPC 108 provide communications between user equipment 104 and PDN 101. EUTRAN 102 may include multiple evolved Node Bs (“eNodeB” or “ENODEB” or “enodeb” or “eNB”) or base stations 106(a, b, c) (as shown in FIG. 1b) that provide communications capabilities to multiple user equipment 104(a, b, c). User equipment 104 may be a mobile phone, a smartphone, a tablet, a personal computer, a personal digital assistant (PDA), a server, a data terminal, and / or any other type of user equipment, and / or any combination thereof. User equipment 104 can connect to the EPC 108 and ultimately to the PDN 101 via any eNodeB 106. Typically, user equipment 104 can connect to the nearest eNodeB 106 in terms of distance. In the LTE system 100, the EUTRAN 102 and the EPC 108 cooperate to provide connectivity, mobility, and services to user equipment 104.

[0043] Figure 1b shows further details of the network 100 shown in Figure 1a. As mentioned above, the EUTRAN 102 includes multiple eNodeBs 106, also known as cell sites. The eNodeBs 106 provide radio functionality and perform important control functions, including scheduling or radio resource management of air link resources, active mode mobility or handover, and admission control for services. The eNodeBs 106 are responsible for selecting which mobility management entity (MME, as shown in Figure 1c) serves the user equipment 104 and for protocol functions such as header compression and encryption. The eNodeBs 106 that make up the EUTRAN 102 coordinate with each other for radio resource management and handover.

[0044] Communication between the user equipment 104 and the eNodeB 106 occurs over an air interface 122 (also known as the "LTE-Uu" interface). As shown in FIG. 1b, the air interface 122 provides communication between the user equipment 104b and the eNodeB 106a. The air interface 122 uses Orthogonal Frequency Division Multiple Access (OFDMA) and Single-Carrier Frequency Division Multiple Access (SC-FDMA), an OFDMA variant, on the downlink and uplink, respectively. OFDMA allows the use of multiple known antenna technologies, such as Multiple Input Multiple Output (MIMO).

[0045] The air interface 122 uses various protocols, including radio resource control (RRC) for signaling between the user equipment 104 and the eNodeB 106 and non-access stratum (NAS) for signaling between the user equipment 104 and the MME (as shown in FIG. 1c). In addition to signaling, user traffic is transferred between the user equipment 104 and the eNodeB 106. Both signaling and traffic in the system 100 are carried by physical layer (PHY) channels.

[0046] Multiple eNodeBs 106 can be interconnected with each other using X2 interfaces 130(a, b, c). As shown in FIG. 1b, the X2 interface 130a provides interconnection between the eNodeBs 106a and 106b, the X2 interface 130b provides interconnection between the eNodeBs 106a and 106c, and the X2 interface 130c provides interconnection between the eNodeBs 106b and 106c. The X2 interfaces can be established between two eNodeBs to provide for the exchange of signals, which may include load-related or interference-related information as well as handover-related information. The eNodeBs 106 communicate with the evolved packet core 108 via S1 interfaces 124(a, b, c). The S1 interface 124 can be split into two interfaces, one for the control plane (shown in Figure 1c as control plane interface (S1-MME interface) 128) and the other for the user plane (shown in Figure 1c as user plane interface (S1-U interface) 125).

[0047] The EPC 108 establishes and enforces Quality of Service (QoS) for user services and enables the user equipment 104 to maintain a consistent Internet Protocol (IP) address while moving. Note that each node in the network 100 has its own IP address. The EPC 108 is designed to interwork with legacy wireless networks. The EPC 108 is also designed to separate the control plane (i.e., signaling) and user plane (i.e., traffic) in the core network architecture, which allows for more implementation flexibility and independent scalability of control data and user data functions.

[0048] The EPC 108 architecture is dedicated to packet data and is shown in more detail in Figure 1c. The EPC 108 includes a serving gateway (S-GW) 110, a PDN gateway (P-GW) 112, a mobility management entity (MME) 114, a home subscriber server (HSS) 116 (a subscriber database for the EPC 108), and a policy control and charging rules function (PCRF) 118. Some of these (e.g., S-GW, P-GW, MME, HSS) are often combined into nodes according to manufacturer implementations.

[0049] The S-GW 110 functions as an IP packet data router and is the bearer path anchor for user equipment within the EPC 108. Thus, when a user equipment moves from one eNodeB 106 to another during mobility operation, the S-GW 110 remains the same and the bearer path towards the EUTRAN 102 is switched to communicate with the new eNodeB 106 serving the user equipment 104. When the user equipment 104 moves to the domain of a different S-GW 110, the MME 114 transfers all bearer paths for the user equipment to the new S-GW. The S-GW 110 establishes a bearer path for the user equipment to one or more P-GWs 112. When downstream data is received for an idle user equipment, the S-GW 110 buffers the downstream packets and requests the MME 114 to locate and re-establish the bearer path to and through the EUTRAN 102.

[0050] The P-GW 112 is a gateway between the EPC 108 (and user equipment 104 and EUTRAN 102) and the PDN 101 (shown in FIG. 1a). The P-GW 112 acts as a router for user traffic and performs functions on behalf of the user equipment. These functions include IP address allocation for the user equipment, packet filtering of downstream user traffic to ensure that it is placed on the appropriate bearer path, and enforcement of downstream QoS, including data rate. Depending on the services a subscriber is using, there may be multiple user data bearer paths between the user equipment 104 and the P-GW 112. A subscriber may use services on PDNs served by different P-GWs, in which case the user equipment has at least one bearer path established to each P-GW 112. During handover of a user equipment from one eNodeB to another, if the S-GW 110 is also changing, the bearer path from the P-GW 112 is switched to the new S-GW.

[0051] The MME 114 manages the user equipment 104 in the EPC 108, including managing subscriber authentication, maintaining context for authenticated user equipment 104, establishing a data bearer path within the network for user traffic, and tracking the location of idle mobiles that have not detached from the network. For an idle user equipment 104 that needs to reconnect to the access network to receive downstream data, the MME 114 initiates paging to locate the user equipment and reestablishes a bearer path to and through the EUTRAN 102. The MME 114 for a particular user equipment 104 is selected by the eNodeB 106 through which the user equipment 104 initiates system access. The MME is typically part of a collection of MMEs in the EPC 108 for load sharing and redundancy purposes. In establishing a user's data bearer path, the MME 114 is responsible for selecting the P-GW 112 and S-GW 110 that constitute the termination of the data path through the EPC 108.

[0052] The PCRF 118 is responsible for policy control decision-making and control of flow-based charging functionality within the policy control enforcement function (PCEF) residing in the P-GW 110. The PCRF 118 provides QoS authorization (QoS class identifier (QCI) and bitrate) that determines how a particular data flow is treated in the PCEF and ensures that this is in accordance with the user's subscription profile.

[0053] As mentioned above, IP services 119 are provided by PDN 101 (as shown in FIG. 1a).

[0054] 1d shows an example structure of an eNodeB 106. The eNodeB 106 can include at least one remote radio head (RRH) 132 (typically, there may be three RRHs 132) and a baseband unit (BBU) 134. The RRHs 132 can be connected to an antenna 136. The RRHs 132 and BBU 134 can be connected using an optical interface compliant with the common public radio interface (CPRI) / enhanced CPRI (eCPRI) 142 standard specification, either using an RRH-specific custom control and user plane framing method or using an O-RAN Alliance-compliant control and user plane framing method. The operation of the eNodeB 106 can be characterized using the following standard parameters (and specifications): The "following standard parameters" include the radio frequency band (Band 4, Band 9, Band 17, etc.), bandwidth (5, 10, 15, 20 MHz), access method (downlink: OFDMA, uplink: SC-OFDMA), antenna technology (single-user and multi-user MIMO, uplink: single-user and multi-user MIMO), number of sectors (up to six), maximum transmission speed (downlink: 150 Mb / s, uplink: 50 Mb / s), S1 / X2 interface (1000Base-SX, 1000Base-T), and mobile environment (up to 350 km / h). The BBU 134 can handle digital baseband signal processing, S1 line termination, X2 line termination, call processing, and monitoring and control processing. IP packets received from the EPC 108 (not shown in Figure 1d) can be modulated into digital baseband signals and transmitted to the RRH 132. Conversely, digital baseband signals received from the RRH 132 can be demodulated into IP packets for transmission to the EPC 108.

[0055] The RRH 132 can transmit and receive wireless signals using an antenna 136. The RRH 132 can convert (using a converter (CONV) 140) digital baseband signals from the BBU 134 to radio frequency (RF) signals and power amplify those signals (using an amplifier (AMP) 138) for transmission to the user equipment 104 (not shown in FIG. 1d). Conversely, RF signals received from the user equipment 104 are amplified (using AMP 138) and converted (using CONV 140) to digital baseband signals for transmission to the BBU 134.

[0056] Figure 2 shows additional details of an exemplary eNodeB 106. The eNodeB 106 includes multiple layers: LTE Layer 1 (reference numeral 202), LTE Layer 2 (reference numeral 204), and LTE Layer 3 (reference numeral 206). LTE Layer 1 includes the physical layer (PHY). LTE Layer 2 includes medium access control (MAC), radio link control (RLC), and packet data convergence protocol (PDCP). LTE Layer 3 includes various functions and protocols, including radio resource control (RRC), dynamic resource allocation, eNodeB measurement configuration and provisioning, radio admission control, connection mobility control, and radio resource management (RRM). The RLC protocol is an automatic repeat request (ARQ) fragmentation protocol used over the cellular air interface. The RRC protocol handles LTE Layer 3 control plane signaling between user equipment and EUTRAN. RRC includes functions for connection establishment and release, system information broadcast, radio bearer establishment / reconfiguration and release, RRC connection mobility procedures, paging notification and release, and outer loop power control. PDCP performs IP header compression and decompression, user data transfer, and radio bearer sequence number maintenance. The BBU 134 shown in FIG. 1d may include LTE layers L1 to L3.

[0057] One of the primary functions of the eNodeB 106 is radio resource management, which includes scheduling of both uplink and downlink air interface resources for the user equipment 104, control of bearer resources, and admission control. As an agent for the EPC 108, the eNodeB 106 is responsible for forwarding paging messages used to locate mobiles when they are idle. The eNodeB 106 also communicates common control channel information over the air, performs header compression, encryption and decryption of user data sent over the air, and establishes handover reporting and trigger criteria. As mentioned above, the eNodeB 106 can coordinate with other eNodeBs 106 via the X2 interface for handover and interference management purposes. The eNodeB 106 communicates with the MME of the EPC via the S1-MME interface and with the S-GW using the S1-U interface. Additionally, the eNodeB 106 exchanges user data with the S-GW via the S1-U interface. The eNodeBs 106 and the EPC 108 have a many-to-many relationship to support load balancing and redundancy between the MMEs and the S-GWs. The eNodeB 106 selects an MME from a group of MMEs so that the load can be shared by multiple MMEs to avoid congestion.

[0058] II. 5G NR Wireless Communication Network In some implementations, the subject matter of the present disclosure relates to a 5G New Radio (NR) communication system. 5G NR is the next telecommunications standard that will surpass the 4G / IMT-Advanced standard. 5G networks offer higher capacity than current 4G, allowing for more mobile broadband users per unit area, and consuming more data in gigabytes per month and per user and / or unlimited data. This can enable users to stream high-definition media for hours per day using their mobile devices, even when Wi-Fi networks are unable to do so. 5G networks have improved support for device-to-device communications, lower costs, lower latency and lower battery consumption than 4G devices, etc. Such networks have data rates of tens of megabits per second for many users, data rates of 100 Mb / s for metropolitan areas, 1 Gb / s simultaneously to users within a limited area (e.g., an office floor), many simultaneous connections for wireless sensor networks, increased spectral efficiency, improved coverage, increased signaling efficiency, and latencies of 1-10 ms, reduced latency compared to existing systems.

[0059] 3 illustrates an exemplary virtual radio access network 300. The network 300 can provide communication between various components, including a base station (e.g., eNodeB, gNodeB) 301, radio equipment 303, a centralized unit 302, a digital unit 304, and a wireless device 306. The components in the system 300 can be communicatively coupled to a core using a backhaul link 305. The centralized unit (CU) 302 can be communicatively coupled to a distributed unit (DU) 304 using a midhaul connection 308. The radio frequency (RU) component 306 can be communicatively coupled to the DU 304 using a fronthaul connection 310.

[0060] In some implementations, the CU 302 can provide intelligent communication capabilities to one or more DU units 304. The units 302, 304 can include one or more base stations, macro base stations, micro base stations, remote radio heads, etc., and / or any combination thereof.

[0061] In a lower layer split architecture environment, the CPRI bandwidth requirement for NR can be several hundred Gb / s. CPRI compression can be implemented in the DU and RU (as shown in Figure 3). In 5G communication systems, compressed CPRI over Ethernet frames, called eCPRI, is the recommended fronthaul network. This architecture can enable standardization of fronthaul / midhaul, which can include upper layer splitting (e.g., Option 2 or Option 3-1 (upper / lower RLC split architecture)) and fronthaul using L1 split architecture (Option 7).

[0062] In some implementations, the lower layer split architecture (e.g., Option 7) can include a receiver in the uplink, joint processing across multiple transmission points (TPs) for both DL / UL, and transport bandwidth and latency requirements to facilitate deployment. Additionally, the lower layer split architecture of the presently disclosed subject matter can include splitting between cell-level processing and user-level processing, which can include cell-level processing in a remote unit (RU) and user-level processing in a DU. Additionally, using the lower layer split architecture of the presently disclosed subject matter, frequency-domain samples can be transported over the Ethernet fronthaul, and the frequency-domain samples can be compressed for reduced fronthaul bandwidth.

[0063] 4 illustrates an example communication system 400 that may implement 5G technology and provide its users with use of higher frequency bands (e.g., greater than 10 GHz). The system 400 may include a macro cell 402 and small cells 404, 406.

[0064] The mobile device 408 can be configured to communicate with one or more of the small cells 404, 406. The system 400 can enable a split of the control plane (C-plane) and user plane (U-plane) between the macrocell 402 and the small cells 404, 406, with the C-plane and U-plane utilizing different frequency bands. In particular, the small cells 404, 406 can be configured to utilize higher frequency bands when communicating with the mobile device 408. The macrocell 402 can utilize existing cellular bands for C-plane communications. The mobile device 408 can be communicatively coupled via the U-plane 412, and the small cells (e.g., the small cell 406) can provide higher data rates and more flexible, cost-efficient operation. The macrocell 402 can maintain good connectivity and mobility via the C-plane 410. Furthermore, in some cases, LTE and NR can be transmitted on the same frequency.

[0065] FIG. 5a illustrates an exemplary 5G wireless communication system 500 according to some implementations of the subject matter of this disclosure. The system 500 may be configured to have a lower layer split architecture according to Option 7-2. The system 500 may include a core network 502 (e.g., 5G Core) and one or more gNodeBs (or gNBs), where the gNBs may have a centralized unit (gNB-CU). The gNB-CU may be logically divided into a control plane portion (gNB-CU-CP) 504 and one or more user plane portions (gNB-CU-UP) 506. The control plane portion 504 and the user plane portion 506 may be configured to be communicatively coupled using an E1 communication interface 514 (as specified in the 3GPP standard). The control plane portion 504 may be configured to be responsible for executing the RRC and PDCP protocols of the radio stack.

[0066] The control plane portion 504 and user plane portion 506 of the centralized unit of the gNB can be configured to be communicatively coupled to one or more distributed units (DUs) 508, 510 according to an upper layer split architecture. The distributed units 508, 510 can be configured to execute upper portions of the RLC, MAC, and PHY layer protocols of the radio stack. The control plane portion 504 can be configured to be communicatively coupled to the distributed units 508, 510 using an F1-C communication interface 516, and the user plane portion 506 can be configured to be communicatively coupled to the distributed units 508, 510 using an F1-U communication interface 518. The distributed units 508, 510 can be coupled to one or more remote radio units (RUs) 512 via a fronthaul network 520 (which may include one or more switches, links, etc.), which further communicate with one or more user equipment (not shown in FIG. 5a). The remote radio unit 512 may be configured to execute lower portions of the PHY layer protocol and provide antenna capabilities to the remote unit for communication with user equipment (similar to the discussion above in connection with Figures 1a-2).

[0067] Figure 5b shows an example layer architecture 530 for a split gNB. The architecture 530 can be implemented within the communication system 500 shown in Figure 5a, which can be configured as a virtualized disaggregated radio access network (RAN) architecture, whereby layer L1, layer L2, layer L3, and radio processing can be virtualized and de-aggregated in centralized unit(s), distributed unit(s), and radio unit(s). As shown in Figure 5b, the gNB-DU 508 can be communicatively coupled to the gNB-CU-CP control plane portion 504 (also shown in Figure 5a) and the gNB-CU-UP user plane portion 506. Each of the components 504, 506, 508 can be configured to include one or more layers.

[0068] The gNB-DU 508 may include an RLC layer, a MAC layer, and a PHY layer, as well as various communication sublayers. These may include an F1 application protocol (F1-AP) sublayer, a GPRS tunneling protocol (GTPU) sublayer, a stream control transmission protocol (SCTP) sublayer, a user datagram protocol (UDP) sublayer, and an Internet Protocol (IP) sublayer. As mentioned above, the distribution unit 508 may be communicatively coupled to the control plane portion 504 of the centralized unit, which may also include the F1-AP sublayer, the SCTP sublayer, and the IP sublayer, as well as a radio resource control and PDCP control (PDCP-C) sublayer. Furthermore, the distribution unit 508 may also be communicatively coupled to the user plane portion 506 of the centralized unit of the gNB. The user plane portion 506 may include a service data adaptation protocol (SDAP) sublayer, a PDCP User (PDCP-U) sublayer, a GTPU sublayer, a UDP sublayer, and an IP sublayer.

[0069] Figure 5c shows an example functional division in the gNB architecture shown in Figures 5a-5b. As shown in Figure 5c, the gNB-DU 508 may be communicatively coupled to the gNB-CU-CP 504 and the gNB-CU-UP 506 using an F1-C communication interface. The gNB-CU-CP 504 and the gNB-CU-UP 506 may be communicatively coupled using an E1 communication interface. The upper portion of the PHY layer (or Layer 1) may be performed by the gNB-DU 508, and the lower portion of the PHY layer may be performed by the RU (not shown in Figure 5c). As shown in Figure 5c, the RRC portion and the PDCP-C portion may be performed by the control plane portion 504, and the SDAP portion and the PDCP-U portion may be performed by the user plane portion 506.

[0070] Some of the functions of the PHY layer in a 5G communication network include error detection on transport channels and indication to higher layers, FEC encoding / decoding of transport channels, hybrid ARQ soft combining, rate matching of coded transport channels to physical channels, mapping of coded transport channels to physical channels, power weighting of physical channels, modulation and demodulation of physical channels, frequency and time synchronization, radio characteristic measurements and indication to higher layers, MIMO antenna processing, digital and analog beamforming, RF processing, and other functions.

[0071] The MAC sublayer of Layer 2 performs beam management, random access procedures, mapping between logical channels and transport channels, concatenation of multiple MAC service data units (SDUs) belonging to one logical channel into transport blocks (TBs), multiplexing / demultiplexing of SDUs belonging to logical channels to / from TBs passed to / from the physical layer on transport channels, scheduling information reporting, error correction via HARQ, priority handling between logical channels for one UE, priority handling between UEs via dynamic scheduling, transport format selection, and other functions. The RLC sublayer's functions may include forwarding upper-layer packet data units (PDUs), error correction via ARQ, reordering of data PDUs, duplication and protocol error detection, reestablishment, etc. The PDCP sublayer is responsible for forwarding user data, various functions during reestablishment procedures, retransmission of SDUs, discarding SDUs in the uplink, forwarding of control plane data, etc.

[0072] The RRC sublayer of Layer 3 may perform the broadcasting of system information to the NAS and AS, establishment, maintenance, and release of RRC connections, security, establishment, configuration, maintenance, and release of point-to-point radio bearers, mobility functions, reporting, and other functions.

[0073] III. Transmission of Channel State Information Reference Signals In some implementations of the subject matter of this disclosure, an RU (e.g., RU 306 in FIG. 3, RU 512 in FIG. 5a, etc.) of a base station (e.g., eNodeB 106(a, b, c) in FIGS. 1b-2, gNodeB in FIG. 5a, etc.) in a wireless communication system (e.g., 5G, 6G, or other generations after 5G, LTE, etc.) can be configured to generate a CSI RS using configuration information provided to the RU. The configuration information can include all parameters necessary for the RU to generate a CSI RS and map the CSI RS to resource elements (REs).

[0074] 6 shows an example implementation of a method 600 for transmitting a CSI RS according to some implementations of the subject matter of this disclosure. The method 600 includes a DU (such as the DU 304 in FIG. 3 or the DUs 508 and 510 in FIGS. 5a-5c) of a base station (such as the eNodeB 106(a, b, and c) in FIGS. 1b-2 or the gNodeB in FIG. 5a) transmitting a message 602 to an RU (such as the RU 306 in FIG. 3 or the RU 512 in FIG. 5a) of the base station. The message includes configuration information for the CSI RS.

[0075] The configuration information may include parameters necessary for the RU to generate 604 a channel state information reference signal and map the CSI RS to resource elements (REs). The parameters may include information defined by the 3GPP standard for the CSI RS, such as information in Table 7.4.1.5.3-1 (CSI-RS position within a slot) of 3GPP TS 38.211 "NR; Physical channels and modulation," including port, density, code division multiplexing type, orthogonal frequency division multiplexing (OFDM) symbol number within a slot, slot number within a radio frame, and number of OFDM symbols per slot. The parameters may also include one or more additional parameters, including one or more of a bandwidth for the CSI RS transmission, amplitude scaling, scrambling identification (ID), orthogonal frequency division multiplexing (OFDM) symbol number within a slot, slot number within a radio frame, and number of OFDM symbols per slot. Thus, all information required for the RU to generate the CSI RS (604) may be included in the configuration information so that traffic on the fronthaul network may be reduced due to less traffic required to receive the information the RU needs to generate the CSI RS.

[0076] Table 1 shows the types of messages, along with the transmission direction, that may be transmitted over a fronthaul communication link between a DU and an RU (e.g., the fronthaul connection 310 between the DU 304 and the RU 306 in FIG. 3 , the fronthaul connection over the fronthaul network 520 between the DU 508 and one of the RUs 512 in FIG. 5 a, the fronthaul connection over the fronthaul network 520 between the DU 510 and one of the RUs 512 in FIG. 5 a, etc.). Messages may be transmitted in the control plane (C-plane), user plane (U-plane), synchronization plane (S-plane), and management plane (M-plane). The C-plane may include uplink and downlink messages (both from the DU to the RU). The U-plane may also include uplink (from the RU to the DU) and downlink (from the DU to the RU) messages and may transmit IQ samples to / from the user equipment. The uplink / downlink direction does not apply to the transmission of messages in the synchronization and management planes. The S-plane includes messages that carry timing information relative to a timing grandmaster. The M-plane carries messages related to configuration (DU to RU) and notification / measurement (RU to DU). [Table 1]

[0077] As mentioned above, a lower layer split (LLS) architecture may include a split between cell-level processing and user-level processing, which may include cell-level processing in the RU and user-level processing in the DU. In an O-RAN architecture, an LLS control plane (LLS-C) logical interface between the RU (O-RU) and the DU (O-DU) may be used for C-plane communication between the RU (O-RU) and the DU (O-DU).

[0078] The O-RAN Working Group 4 (Open Fronthaul Interfaces WG), "Control, User and Synchronization Plane Specification," specifies the C-plane protocol, U-plane protocol, and S-plane protocol used on the fronthaul connection for DUs (O-DUs) and RUs (O-RUs) with an LLS architecture. The O-RAN Working Group 4 (Open Fronthaul Interfaces WG), "Management Plane Specification," specifies the M-plane protocol used on the fronthaul connection for DUs (O-DUs) and RUs (O-RUs) with an LLS architecture.

[0079] In some implementations of the subject matter of this disclosure, the configuration information can be sent to the RU in a C-plane message from the DU transmitted from the DU to the RU on the C-plane (602). The C-plane message can be of a section type (or a section extension type) that defines parameters included in the CSI RS configuration information. As described above, the parameters can include information defined by the 3GPP standard for the CSI RS, for example, information in Table 7.4.1.5.3-1 of 3GPP TS 38.211 “NR; Physical channels and modulation” (CSI-RS locations within a slot), in addition to one or more additional parameters. Thus, all information required for the RU to generate the CSI RS can be included in the configuration information, so that traffic on the fronthaul network can be reduced due to less C-plane traffic required to receive the information the RU needs to generate the CSI RS. Thus, the C-plane message can also carry beamforming weights for each of the CSI-RS ports.

[0080] The O-RAN Working Group 4 "Control, User, and Synchronization Plane Specification" defines a common frame format for C-plane messages, where parameters within the frame are specific to the section type being used. Several section types (e.g., 0-7) are defined, and other section types (e.g., 8-255) are reserved for future use. The section type of a C-plane message containing configuration information described herein may be provided as a predefined section type, e.g., one of the section types currently reserved for future use, rather than as a currently defined section type. Thus, configuration information may be shared in a standard manner across the RAN.

[0081] Generally, a common frame format, as defined by the O-RAN Alliance, shall be used for C-plane messages. C-plane messages have a first layer containing an eCPRI common header or an IEEE 1914.3 common header, and a second layer containing an application layer containing fields necessary for control and synchronization. A "section" within the application layer defines the characteristics of U-plane data to be transmitted or received from a beam with a pattern ID. Within the data description section, the section header may contain an "extension flag" that indicates parameters that apply to sections beyond the section header.

[0082] 7 shows an example implementation of a section-type C-plane frame format 700 for transmitting 602 CSI RS configuration information in a C-plane message. Thus, the C-plane message may be of a section type that defines multiple parameters to be included in the CSI RS configuration information.

[0083] 7, the C-plane frame format 700 includes an extension flag (ef). Within the extension flag is another extension flag, a type field (extType), which is a 7-bit field that describes the section extension type, and a length field (extLen), which details how many 4-byte words are in the extension.

[0084] Also, as shown in FIG. 7, the parameters in the extension include several parameters defined by 3GPP (e.g., Table 7.4.1.5.3-1 (CSI-RS position within a slot) of 3GPP TS 38.211 “NR; Physical channels and modulation”), namely, row, port, density, (k,l) (the resource element position, where “k” is the index in the frequency domain and “l” refers to the symbol position in the time domain relative to some reference point), CDM group index, k (subcarrier offset), and l (OFDM symbol number within a slot). The parameters in this extension also include several additional parameters, namely, csirs-bandwidth (bandwidth for CSI RS transmission), amplitude scaling (β CSIRS ), and scrambling identification (ID). The parameters csi-rs-bandwidth, amplitude scaling, and scrambling ID are used by the UE to decode the CSi-RS data transmitted from the base station to the UE.

[0085] 6, in some implementations of the subject matter of this disclosure, configuration information can be sent from the DU to the RU in an M-plane message 602. The RU can be configured to indicate support for CSI RS configuration information in a feature within a YANG model, such as the o-ran-module-cap.yang module, e.g., the RU can be configured to advertise support for its CSI RS configuration information in a feature of the YANG model. Thus, the M-plane message can carry beamforming weights for each of the CSI-RS ports.

[0086] The NETCONF / YANG protocol (or application layer communication mode) can be used to operate and / or manage network functions. NETCONF / YANG is a network management protocol developed and standardized by the Internet Engineering Task Force (IETF) under the RFC4741 and RFC6241 standards. The NETCONF / YANG protocol provides mechanisms for installing, manipulating, and deleting the configuration of network devices.

[0087] The O-RAN Working Group 4 "Management Plane Specification" specifies that a NETCONF / YANG-based M-Plane is used to support management functions, and therefore, O-RAN Alliance compliant YANG models may be used in connection with providing CSI RS configuration information to the RU.

[0088] An example implementation of a YANG model for use in connection with providing CSI RS configuration information to an RU is provided below. +--rw semi-static-csi-rs-configuration?-> / user-plane-configuration / semi-static-csi-rs-configurations / semi-static-csi-rs-config-id {mcap:CSI-RS-SEMI-STATIC-CONFIGURATION-SUPPORTED}? +--rw static-csi-rs-configurations* [static-csi-rs-config-id] {mcap:CSI-RS-SEMI-STATIC-CONFIGURATION-SUPPORTED}? |+--Row-TS38211-Table 7.4.1.5.3-1 uint16 |+--Port-TS38211-Table 7.4.1.5.3-1 uint16 |+--Density-TS38211-Table 7.4.1.5.3-1 uint16 |+--(k,l)-TS38211-Table 7.4.1.5.3-1 uint16 |+--cdm group index-TS38211-Table 7.4.1.5.3-1 uint16 |+--k-TS38211-Table 7.4.1.5.3-1 uint16 |+--csi-rs-bandwidth uint16 |+--Scaling(beta-csirs)uint16 |+--Scrambling id uint16

[0089] In this YANG model, an RU exposes its ability to support semi-static CSI-RS configuration by supporting the function CSI-RS-SEMI-STATIC-CONFIGURATION-SUPPORTED in the o-ran-module-cap.yang module. The presence of this function implies that at least one of the static-low-level-rx-endpoints provided by the RU supports semi-static configuration for raw CSI-RS reception. When parameters related to semi-static CSI-RS configuration are configured by a NETCONF client, for example, as described above with respect to C-plane messages containing CSI-RS configuration information, real-time C-plane control for CSI-RS shall not be provided to the RU, thereby allowing static configuration to be utilized instead.

[0090] Regardless of how the message containing the CSI RS configuration information is transmitted to the RU (602), the RU can generate the CSI RS using the received configuration information (604). The generation of the CSI RS (604) can conform to 3GPP standards, e.g., 3GPP TS 38.211, "NR; Physical channels and modulation." The RU can then transmit the CSI RS (606) to the UE. The UE receives the CSI RS and, in response, transmits CSI, e.g., a CSI report, to the RU, which receives the CSI (608). The UE can create and transmit a CSI report in accordance with 3GPP standards, e.g., 3GPP TS 38.214, "NR; Physical layer procedures for data." The CSI received at the base station, e.g., at the RU (608), can then be used by the base station (610) in accordance with 3GPP standards to improve service to the UE.

[0091] In some implementations, the subject matter of the present disclosure can be configured to be implemented in a system 800, as shown in FIG. 8. The system 800 can include one or more of a processor 810, a memory 820, a storage device 830, and an input / output device 840. Each of the components 810, 820, 830, and 840 can be interconnected using a system bus 850. The processor 810 can be configured to process instructions for execution within the system 600. In some implementations, the processor 810 can be a single-threaded processor. In alternative implementations, the processor 810 can be a multi-threaded processor. The processor 810 can be further configured to process instructions stored in the memory 820 or the storage device 830, including receiving or transmitting information via the input / output device 840. The memory 820 can store information within the system 800. In some implementations, the memory 820 can be a computer-readable medium. In alternative implementations, the memory 820 can be a volatile memory unit. Further, in some implementations, memory 820 may be a non-volatile memory unit. Storage device 830 may be capable of providing mass storage for system 800. In some implementations, storage device 830 may be a computer-readable medium. In alternative implementations, storage device 830 may be a floppy disk device, a hard disk device, an optical disk device, a tape device, a non-volatile solid-state memory, or any other type of storage device. Input / output device 840 may be configured to provide input / output operations to system 800. In some implementations, input / output device 840 may include a keyboard and / or a pointing device. In alternative implementations, input / output device 840 may include a display unit for displaying a graphical user interface.

[0092] 9 illustrates an example method 900 for transmitting a channel state information reference signal in accordance with some implementations of the subject matter of this disclosure. Method 900 may be performed, for example, using the implementations shown in and described with respect to FIGS.

[0093] The method 900 includes receiving, at an RU (e.g., the RU 306 in FIG. 3 or the RU 512 in FIG. 5 a) of a base station (e.g., the eNodeB 106(a, b, c) in FIGS. 1 b-2 or the gNodeB in FIG. 5 a) in a wireless communication system (e.g., 5G, 6G, or other generations after 5G, LTE, etc.), a message including CSI RS configuration information configured for use by the RU in generating a channel state information reference signal (CSI RS) for transmission to a user equipment (UE) (902). The CSI RS configuration information includes a plurality of parameters including a bandwidth, amplitude scaling, and scrambling identification (ID) for the CSI RS transmission.

[0094] In some implementations, the subject matter of this disclosure can include one or more of the following optional features.

[0095] In some implementations, the message may be a control plane (C-plane) message. Further, the message may be of a section type or a section extension type that defines multiple parameters included in the CSI RS configuration information, and / or the message may be sent from a DU (such as the DU 304 in FIG. 3 or the DUs 508, 510 in FIGS. 5a-5c) of a base station to an RU, and the message may provide real-time C-plane control to the RU.

[0096] In some implementations, the message may be a management plane (M-plane) message. Further, the RU may indicate support for CSI RS configuration information in a capability within a YANG model (e.g., the o-ran-module-cap.yang module).

[0097] In some implementations, the parameters may also include a port, a density, a code division multiplexing type, an orthogonal frequency division multiplexing (OFDM) symbol number within a slot, a slot number within a radio frame, and a number of OFDM symbols per slot.

[0098] In some implementations, the multiple parameters may include all parameters necessary for the RU to generate a CSI RS for transmission to the UE.

[0099] In some implementations, the CSI RS may be generated at the RU using CSI RS configuration information, and the generated CSI RS may be transmitted from the RU to the UE. Furthermore, after transmitting the generated CSI RS, the CSI may be received from the UE at the RU, and the RU may transmit the CSI to the DU for decoding.

[0100] In some implementations, the wireless communication system may be an LTE communication system or a 5G communication system.

[0101] In some implementations, the base station may be an eNodeB or a gNodeB.

[0102] The systems and methods disclosed herein may be embodied in various forms, including, for example, data processors such as computers that include databases, digital electronic circuitry, firmware, software, or any combination thereof. Furthermore, the above-described features and other aspects and principles of implementations of the present disclosure may be implemented in a variety of environments. Such environments and related applications may be specially constructed to perform the various processes and operations in accordance with the disclosed implementations, or they may include general-purpose computers or computing platforms selectively activated or reconfigured by code to provide the required functionality. The processes disclosed herein are not inherently related to any particular computer, network, architecture, environment, or other apparatus, but may be implemented by any suitable combination of hardware, software, and / or firmware. For example, various general-purpose machines may be used with programs written in accordance with the teachings of the disclosed implementations, or it may be more convenient to construct specialized apparatus or systems to perform the required methods and techniques.

[0103] The systems and methods disclosed herein can be implemented as a computer program product, i.e., a computer program tangibly embodied in an information carrier, e.g., in a machine-readable storage device, or in a propagated signal, for execution by or to control the operation of a data processing apparatus, e.g., a programmable processor, computer, or multiple computers. The computer program can be written in any form of programming language, including compiled or interpreted languages, and can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. The computer program can be deployed to be executed on one computer or on multiple computers at one site or distributed across multiple sites and interconnected by a communications network.

[0104] As used herein, the term "user" can refer to any entity, including a person or a computer.

[0105] Although ordinal numbers such as first, second, etc. may relate to order in some contexts, as used in this document, ordinal numbers do not necessarily imply order. For example, ordinal numbers may be used simply to distinguish one item from another. For example, distinguishing a first event from a second event does not necessarily imply any chronological order or fixed frame of reference (just as a first event in one paragraph of a description may differ from a first event in another paragraph of the description).

[0106] The foregoing description is intended to illustrate, but not limit, the scope of the invention, which is defined by the appended claims. Other implementations are within the scope of the following claims.

[0107] These computer programs, which may also be referred to as programs, software, software applications, applications, components, or code, contain machine instructions for a programmable processor and may be implemented in a high-level procedural and / or object-oriented programming language and / or in assembly / machine code. As used herein, the term “machine-readable medium” refers to any computer program product, apparatus, and / or device used to provide machine instructions and / or data to a programmable processor, such as, for example, magnetic disks, optical disks, memories, and programmable logic devices (PLDs), including machine-readable media that receive machine instructions as machine-readable signals. The term “machine-readable signal” refers to any signal used to provide machine instructions and / or data to a programmable processor. A machine-readable medium may non-transitory store such machine instructions, such as, for example, a non-transitory solid-state memory, a magnetic hard drive, or any equivalent storage medium. Alternatively or additionally, a machine-readable medium may also temporarily store such machine instructions, such as, for example, a processor cache or other random access memory associated with one or more physical processor cores.

[0108] To provide for user interaction, the subject matter described herein can be implemented on a computer having a display device, such as a cathode ray tube (CRT) or liquid crystal display (LCD) monitor, for displaying information to the user, and a keyboard and pointing device, such as a mouse or trackball, for allowing the user to provide input to the computer. Other types of devices can also be used to provide for user interaction. For example, feedback provided to the user can be any form of sensory feedback, such as visual feedback, auditory feedback, or tactile feedback, and input from the user can be received in any form, including, but not limited to, acoustic, speech, or tactile input.

[0109] The subject matter described herein can be implemented in a computing system that includes back-end components such as, for example, one or more data servers, or includes middleware components such as, for example, one or more application servers, or includes front-end components such as, for example, one or more client computers having a graphical user interface or web browser through which a user can interact with an implementation of the subject matter described herein, or any combination of such back-end, middleware, or front-end components. The components of the system can be interconnected by any form or medium of digital data communication, such as, for example, a communication network. Examples of communication networks include, but are not limited to, a local area network (LAN), a wide area network (WAN), and the Internet.

[0110] A computing system may include clients and servers. Clients and servers are generally, though not exclusively, remote from each other and typically interact through a communication network. The relationship of client and server arises by virtue of computer programs running on the respective computers and having a client-server relationship to each other.

[0111] The implementations described in the foregoing description do not represent all implementations consistent with the subject matter described herein. Rather, these implementations are merely some examples consistent with aspects related to the described subject matter. While several variations have been described in detail above, other modifications or additions are possible. In particular, further features and / or variations may be provided in addition to those described herein. For example, the implementations described above may be directed to various combinations and subcombinations of the disclosed features and / or combinations and subcombinations of certain additional features disclosed above. In addition, the logic flow illustrated in the accompanying figures and / or described herein does not necessarily require the particular order illustrated, or sequential order, to achieve desirable results. Other implementations may be within the scope of the following claims.

Claims

1. at least one processor; at least one non-transitory storage medium having instructions stored thereon, The instructions, when executed by the at least one processor, cause the at least one processor to perform operations, the operations including: receiving, at a radio unit (RU) of a base station in a wireless communication system, a message including channel state information reference signal (CSI RS) configuration information configured for use by the RU in generating a CSI RS for transmission to a user equipment (UE); The apparatus, wherein the CSI RS configuration information includes a plurality of parameters including bandwidth, amplitude scaling, and scrambling identification (ID) for CSI RS transmission.

2. The apparatus of claim 1 , wherein the message is a control plane (C-plane) message.

3. The apparatus of claim 2 , wherein the message is of a section type or a section extension type that defines the plurality of parameters included in the CSI-RS configuration information.

4. The operations further include transmitting the message from a distributed unit (DU) of the base station to the RU; The apparatus of claim 2 , wherein the message provides real-time C-plane control to the RU.

5. The apparatus of claim 1 , wherein the message is a management plane (M-plane) message.

6. The apparatus of claim 5 , wherein the operations further include the RU indicating support of the CSI-RS configuration information in a feature within a YANG model.

7. 10. The apparatus of claim 1, wherein the plurality of parameters further comprises a port, a density, a code division multiplexing type, an orthogonal frequency division multiplexing (OFDM) symbol number within a slot, a slot number within a radio frame, and a number of OFDM symbols per slot.

8. The apparatus of claim 1 , wherein the plurality of parameters includes all the parameters necessary for the RU to generate the CSI RS for transmission to the UE.

9. The operations include generating, at the RU, the CSI RS using the CSI RS configuration information; transmitting the generated CSI RS from the RU to the UE; The apparatus of claim 1 further comprising:

10. 10. The apparatus of claim 9, wherein the operations further include, after transmitting the generated CSI RS, receiving CSI from the UE at the RU, and the RU transmitting the CSI to the DU for decoding.

11. The apparatus of claim 1 , wherein the wireless communication system is a Long Term Evolution (LTE) communication system or a 5G communication system.

12. The apparatus of claim 1 , wherein the base station is an eNodeB or a gNodeB.

13. 1. A computer-implemented method, the computer-implemented method comprising: receiving, at a radio unit (RU) of a base station in a wireless communication system, a message including channel state information reference signal (CSI RS) configuration information configured for use by the RU in generating a CSI RS for transmission to a user equipment (UE); The computer-implemented method, wherein the CSI RS configuration information includes a plurality of parameters including bandwidth, amplitude scaling, and scrambling identification (ID) for CSI RS transmission.

14. The method of claim 13 , wherein the message is a control plane (C-plane) message.

15. The method of claim 13 , wherein the message is a management plane (M-plane) message.

16. The method of claim 13 , wherein the plurality of parameters includes all the parameters necessary for the RU to generate the CSI RS for transmission to the UE.

17. at least one non-transitory storage medium having instructions stored thereon; The instructions, when executed by at least one processor, cause the at least one processor to perform operations, the operations including: receiving, at a radio unit (RU) of a base station in a wireless communication system, a message including channel state information reference signal (CSI RS) configuration information configured for use by the RU in generating a CSI RS for transmission to a user equipment (UE); At least one non-transitory storage medium, wherein the CSI RS configuration information includes a plurality of parameters including bandwidth, amplitude scaling, and scrambling identification (ID) for CSI RS transmission.

18. 20. The storage medium of claim 17, wherein the message is a control plane (C-plane) message.

19. 20. The storage medium of claim 17, wherein the message is a management plane (M-plane) message.

20. The storage medium of claim 17 , wherein the plurality of parameters includes all the parameters necessary for the RU to generate the CSI RS for transmission to the UE.

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