Patent Description:
To meet the increased demand for wireless data traffic since the deployment of <NUM> communication systems, efforts have been made to develop an improved <NUM> or pre-<NUM> communication system. Therefore, the <NUM> or pre-<NUM> communication system is also called a "Beyond <NUM> Network" or a "Post LTE System".

Implementation of the <NUM> communication system in higher frequency (mmWave) bands, e.g., <NUM> bands, is being considered in order to accomplish higher data rates. To decrease propagation loss of radio waves and increase the transmission distance, beamforming, massive multiple-input multiple-output (MIMO), Full Dimensional MIMO (FD-MIMO), array antenna, analog beam forming, and large scale antenna techniques are being discussed for the <NUM> communication system.

In addition, in the <NUM> communication system, there are developments under way for system network improvement based on advanced small cells, cloud Radio Access Networks (RANs), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, moving network, cooperative communication, Coordinated Multi-Points (CoMP), reception-end interference cancellation, and the like.

In the <NUM> system, Hybrid FSK and QAM Modulation (FQAM) and sliding window superposition coding (SWSC) as advanced coding modulation (ACM) and filter bank multi carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA) as advanced access technology have been developed.

The Internet, which is a human centered connectivity network where humans generate and consume information, is now evolving into the Internet of Things (IoT) where distributed entities, such as things, exchange and process information without human intervention. The Internet of Everything (IoE), which is a combination of IoT technology and Big Data processing technology through connection with a cloud server, has emerged. As technology elements, such as "sensing technology", "wired/wireless communication and network infrastructure", "service interface technology", and "security technology" have been demanded for IoT implementation, recently there has been research into a sensor network, Machine-to-Machine (M2M) communication, Machine Type Communication (MTC), and so forth. Such an IoT environment may provide intelligent Internet technology services that create new values for human life by collecting and analyzing data generated among connected things. The IoT may be applied to a variety of fields including smart home, smart building, smart city, smart car or connected car, smart grid, health care, smart appliances, and advanced medical services through convergence and combination between existing Information Technology (IT) and various industrial applications.

In line with these developments, various attempts have been made to apply the <NUM> communication system to IoT networks. Application of a cloud Radio Access Network (RAN) as the above-described Big Data processing technology may also be considered to be an example of convergence between the <NUM> technology and the IoT technology.

Meanwhile, as communication systems evolve, there is increasing growth in demand for splitting base station.

The following publications are related to distributed processing in a wireless network:.

In legacy LTE systems, a radio interface protocol stack involves a physical (PHY) layer, a medium access control (MAC) layer, a radio link control (RLC) layer, a packet data convergence protocol (PDCP) layer, and a radio resource control (RRC) layer. Among them, the PHY layer is responsible for mapping transport channels onto physical channels. In detail, the PHY layer is in charge of the procedure of generating and transmitting a radio frequency signal through various operations such as coding/decoding on information bits, modulation/demodulation, hybrid automatic request (HARQ) processing, and time-frequency resource mapping.

However, the hierarchical protocol structure of the legacy LTE system cannot handle efficiently a rapidly increasing number of antennas and a growing channel bandwidth in line with the advance of communication systems, which necessitates an improvement method.

The technical goals to be achieved through the disclosure are not limited to just solving the aforementioned problems, and other unmentioned technical problems will become apparent from the disclosed embodiments to those of ordinary skill in the art.

The method proposed in the disclosure is advantageous in terms of improving communication efficiency and facilitating management of a base station while reducing implementation complexity of the base station in such a way of splitting functions of the base station.

Exemplary embodiments of the disclosure are described in detail with reference to the accompanying drawings. The same reference numbers are used throughout the drawings to refer to the same or like parts. Detailed descriptions of well-known functions and structures incorporated herein may be omitted to avoid obscuring the subject matter of the disclosure.

Detailed descriptions of technical specifications well-known in the art and unrelated directly to the disclosure may be omitted to avoid obscuring the subject matter of the disclosure. This aims to omit unnecessary description so as to make the subject matter of the disclosure clear.

For the same reason, some elements are exaggerated, omitted, or simplified in the drawings and, in practice, the elements may have sizes and/or shapes different from those shown in the drawings. Throughout the drawings, the same or equivalent parts are indicated by the same reference numbers.

Advantages and features of the disclosure and methods of accomplishing the same may be understood more readily by reference to the following detailed descriptions of exemplary embodiments and the accompanying drawings. The disclosure may, however, be embodied in many different forms and should not be construed as being limited to the exemplary embodiments set forth herein; rather, these exemplary embodiments are provided so that this disclosure will be thorough and complete and will fully convey the concept of the disclosure to those skilled in the art, and the disclosure will only be defined by the appended claims. Like reference numerals refer to like elements throughout the specification.

It will be understood that each block of the flowcharts and/or block diagrams, and combinations of blocks in the flowcharts and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general-purpose computer, special purpose computer, or other programmable data processing apparatus, such that the instructions that are executed via the processor of the computer or other programmable data processing apparatus create means for implementing the functions/acts specified in the flowcharts and/or block diagrams. These computer program instructions may also be stored in a non-transitory computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the non-transitory computer-readable memory produce articles of manufacture embedding instruction means that implement the function/act specified in the flowcharts and/or block diagrams. The computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions that are executed on the computer or other programmable apparatus provide steps for implementing the functions/acts specified in the flowcharts and/or block diagrams.

Furthermore, the respective block diagrams may illustrate parts of modules, segments, or codes including at least one or more executable instructions for performing specific logic function(s). Moreover, it should be noted that the functions of the blocks may be performed in a different order in several modifications. For example, two successive blocks may be performed substantially at the same time, or they may be performed in reverse order according to their functions.

According to various embodiments of the disclosure, the term "module" means, but is not limited to, a software or hardware component, such as a Field Programmable Gate Array (FPGA) or Application Specific Integrated Circuit (ASIC), which performs certain tasks. A module may advantageously be configured to reside on the addressable storage medium and configured to be executed on one or more processors. Thus, a module may include, by way of example, components, such as software components, object-oriented software components, class components and task components, processes, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays, and variables. The functionalities of the components and modules may be combined into fewer components and modules or further separated into more components and modules. In addition, the components and modules may be implemented such that they execute one or more CPUs in a device or a secure multimedia card.

It may be advantageous to set forth definitions of certain words and phrases used through the disclosure.

Preferred embodiments are described hereinafter with reference to the accompanying drawings.

<FIG> is a diagram illustrating a wireless network architecture according to a disclosed embodiment.

<FIG> shows an exemplary wireless network <NUM> according to a disclosed embodiment. Although the following description is made of the exemplary deployment of the wireless network <NUM> as shown in <FIG>, the disclosure may be applicable to other network deployments.

In <FIG>, the wireless network <NUM> includes base stations <NUM>, <NUM>, and <NUM>. The base station <NUM> communicates with the base stations <NUM> and <NUM> via at least one network <NUM>. The base stations <NUM> and <NUM> may provide a radio access service to terminals <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> located within their coverages <NUM> and <NUM>. In <FIG>, the base stations <NUM>, <NUM>, and <NUM> may communicate with the terminals <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> via various radio access technologies (RATs) including <NUM> new radio (NR), LTE, LTE-A, high speed packet access (HSPA), WiMAX, and Wi-Fi.

In the following description, the term "base station" may mean an entity such as a transmission point (TP), a transmission and reception point (TRP), an enhanced node B (eNB), a gNB, a macro-cell, a femto-cell, and a Wi-Fi access point (AP); the term "terminal" may mean an entity such as user equipment (UE), a mobile station, a subscriber station, a wireless transmission reception unit (WTRU), and a user device.

It is obvious that the deployment of the wireless network <NUM> can be changed in various manners as described with reference to <FIG>. For example, the wireless network <NUM> may include arbitrary numbers of base stations and terminals, and each base station may communicate with one or more terminals to connect the terminals to the network <NUM>.

<FIG> is a block diagram illustrating a configuration of a base station according to a disclosed embodiment. Although the description is made of the exemplary configuration of the base station <NUM> as shown in <FIG>, the base station may also be configured to include other components in addition to the components depicted in <FIG> or exclude some of the components depicted in <FIG>. The components constituting the base station <NUM> as shown in <FIG> may be integrated among each other or each subdivided into separate smaller parts.

In the embodiment of <FIG>, the base station <NUM> includes a plurality of antennas 205a to 205n, a plurality of RF transceivers 210a to 210n, a transmission (TX) processing circuit <NUM>, and a reception (RX) processing circuit <NUM>. The base station <NUM> may include a controller/processor <NUM>, a memory <NUM>, and backhaul/network interface <NUM>.

The RF transceivers 210a to 210n receive an RF signal transmitted by another device (e.g., terminal and another base station) by means of the antennas 205a to 205n. The RF transceivers 210a to 210n perform down-conversion on the RF signal to produce a baseband signal. The down-converted signal is send to the RX processing circuit <NUM>, which performs filtering, decoding, and/or digitalization on the downlink signal to produce a baseband signal. The RX processing circuit <NUM> sends the produced baseband signal to the controller/processor <NUM>, which performs an additional process on the baseband signal.

The TX processing circuit <NUM> may receive analog or digital data from the controller/processor <NUM>. The TX processing circuit <NUM> performs encoding, multiplexing, and/or digitalization on the baseband data to produce a baseband signal. The RF transceivers 210a to 210n receive the baseband signal processed by the TX processing circuit <NUM> and perform up-conversion on the baseband signal to generate an RF signal to be transmitted via the antennas 205a to 205n.

The RF transceivers 210a to 210n may also be referred to, along with at least one of the TX processing circuit <NUM> and the RX processing circuit <NUM>, as a transceiver.

The controller/processor <NUM> may include one or more processors for controlling overall operations of the base station <NUM>. For example, the controller/processor <NUM> may control the RF transceivers 210a to 210n, the RX processing circuit <NUM>, and the TX processing circuit <NUM> to receive a forward channel signal and transmit a reverse channel signal. The controller/processor <NUM> may include one or a combination of a circuit and a program for processing an uplink (UL) channel and/or a downlink (DL) channel. For example, the controller/processor <NUM> may be configured to execute one or more instructions stored in the memory <NUM>.

The controller/processor <NUM> may be connected to the backhaul/network interface <NUM>. The backhaul/network interface <NUM> enables the base station <NUM> to communicate with another device or system via a backhaul link or network. The backhaul/network interface <NUM> may support wireline or wireless communication.

The memory <NUM> is connected with the controller/processor <NUM>. The memory <NUM> may store various types of information or data being processed by the base station <NUM>.

<FIG> is a block diagram illustrating a configuration of a terminal according to a disclosed embodiment. Although the description is made of the exemplary configuration of the terminal <NUM> as shown in <FIG>, the terminal <NUM> may also be configured to include other components in addition to the components depicted in <FIG> or exclude some of the components depicted in <FIG>. The components constituting the terminal 11b as shown in <FIG> may be integrated among each other or each subdivided into separated smaller parts.

In the embodiment of <FIG>, the terminal <NUM> includes one or more antennas 305a to 305n , one or more RF transceivers 310a to 310n, a TX processing circuit <NUM>, and an RX processing circuit <NUM>. The terminal <NUM> also includes a microphone <NUM>, a speaker <NUM>, an input/output interface (I/O IF) <NUM>, a processor <NUM>, a touchscreen <NUM>, a display <NUM>, and a memory <NUM>, which stores an operating system (OS) <NUM> and at least one application <NUM>.

The RF transceivers 310a to 310n receive an RF signal transmitted by a base station of a network by means of the antennas 305a to 305n. The RF transceivers 310a to 310n perform down-conversion on the RF signal to produce a baseband signal. The down-converted signal is sent to the RX processing circuit <NUM>, which produces a baseband signal by performing filtering, decoding, and/or digitalization on the down-converted signal. The RX processing circuit <NUM> may send the processed baseband signal to the processor <NUM> that performs an additional process on the baseband signal or to the speaker <NUM> that outputs a sound signal.

The TX processing circuit <NUM> may receive analog or digital data from the processor <NUM> or analog or sound data input via the microphone <NUM>. The TX processing circuit <NUM> performs encoding, multiplexing, and/or digitalization on the baseband data to produce a baseband signal. The RF transceivers 310a to 310n receive the baseband signal from the TX processing circuit and perform up-conversion on the baseband signal to produce an RF signal to be transmitted by the antennas 305a to 305n.

Two or more of the RF transceivers 310a to 310n, the TX processing circuit <NUM>, and the RX processing circuit <NUM> may be integrated into a component, which may be referred to as a transceiver.

The processor <NUM> may include one or more processors for controlling overall operations of the terminal <NUM>. For example, the processor <NUM> may control the RF transceivers 310a to 310n, the RX processing circuit <NUM>, and the TX processing circuit <NUM> to receive a forward channel signal and transmit a reverse channel signal. The processor <NUM> may include one or a combination of a circuit and a program for processing a UL channel and/or a DL channel. For example, the processor <NUM> may be configured to execute one or more instructions stored in the memory <NUM>.

The processor <NUM> may execute other processes and programs stored in the memory and write data in the memory <NUM> or read the data out from the memory <NUM>. The processor <NUM> may execute the application <NUM> on the OS <NUM>. The processor <NUM> may be connected to the I/O IF <NUM> that allows another device to connect to the terminal <NUM>. The I/O IF <NUM> provides the processor <NUM> with a communication pathway to other devices.

The processor <NUM> is connected with the touchscreen <NUM> and the display <NUM>. A user may input data to the terminal <NUM> via the touchscreen <NUM>. The display <NUM> may perform text processing or graphic processing on information and data processed in the terminal <NUM> to display the information and data in a visualized manner.

The memory <NUM> is connected with the processor <NUM>. The memory <NUM> may store various types of information and data processed in the terminal <NUM>.

<FIG> is a diagram illustrating a physical layer of a base station according to a disclosed embodiment. The upper part of <FIG> shows a physical layer procedure of the base station for transmitting a downlink signal, and the lower part of <FIG> shows a physical layer procedure of the base station for processing a received uplink signal.

In <FIG>, the physical layer of the base station includes an RF unit (RU) in charge of an RF function and a digital unit (DU) in charge of other functions of the physical layer with the exception of the RF function.

In <FIG>, the DU of the base station performs channel coding on data channels, control channels, and a physical broadcast channel (PBCH) for DL signal transmission, generates a UE-specific demodulation reference signal (DMRS), and performs layer mapping. The DU performs resource element (RE) mapping per layer, precoding & digital beamforming (BF), and inverse fast Fourier transform/cyclic prefix addition (IFFT/CP addition), and the RU generates an RF signal based on a processing result received from the DU and transmits the RF signal in downlink by means of an antenna.

In <FIG>, the RU of the base station receives an uplink signal from a terminal, processes the received signal, and sends the processed signal to the DU. The DU performs FFT/CP removal, BF, RE de-mapping, channel estimation/equalization, inverse discrete Fourier transform (IDFT), demodulation, and decoding on the received signal to acquire the data and control channels, or performs uplink channel estimation based on a sounding reference signal (SRS) acquired from the FFT/CP removed data, or performs physical random access channel (PRACH) detection through PRACH filtering and pre-filtering on the signal received from the RU.

With the evolvement of the 3GPP standard, a massive MIMO antenna structure is considered as a promising technology for NR communication systems operating in an ultra-high frequency band above <NUM> to meet the requirements of increased radio communication channel bandwidth. In this regard, on the basis of the above-described RU-DU configuration in the physical layer of the base station, a fronthaul bandwidth between the RU and DU increases abruptly. Services being provided in such a next generation communication system are characterized by exponentially increasing the amount and diversified types of information to be processed and requirements for communication responsiveness and high speed signal processing. There is therefore a need of a new proposal on the physical layer of the base station for efficient communication by reflecting characteristics of such a communication environment.

<FIG> is a block diagram illustrating a configuration of a split physical layer according to a disclosed embodiment. In the embodiment of <FIG>, the physical layer <NUM> of the base station is configured to have two separate entities through a functional split.

The various functions of the physical layer <NUM> that have been described with reference to <FIG> may be functionally split in various manners. The physical layer <NUM> may be configured to have a first PHY entity <NUM> including at least one of the functions of the physical layer <NUM> and a second PHY entity <NUM> including at least one of the remaining functions, and the first and second PHY entities are connected via a fronthaul interface <NUM> formed therebetween.

As shown in <FIG>, the first PHY entity <NUM> is connected with an antenna and responsible for RF functions and it may be referred to as low PHY layer. The second PHY entity <NUM> is responsible for the remaining functions with the exception of the function of the first PHY entity <NUM> and it may be referred to as high PHY layer.

Descriptions are made hereinafter in detail of the configurations of the first and second PHY entities <NUM> and <NUM>.

<FIG> is a block diagram illustrating a configuration of a split physical layer according to another disclosed embodiment, and <FIG> is a block diagram illustrating a configuration of a split physical layer according to another disclosed embodiment.

<FIG> shows a detailed configuration of the first PHY entity <NUM> described with reference to <FIG>. The first PHY entity in charge of one or more functions including the RF function among the physical layer functions of the base station, which may also be referred to as a massive MIMO unit (MMU) <NUM>, includes an RF processing block <NUM> connected to an antenna <NUM> and performing RF processing, a PHY-L processing block <NUM> for performing some functions (i.e., lower physical layer functions) of the physical layer, and a fronthaul interface block <NUM> for communication with a second PHY entity.

The operations being performed by the RF processing block <NUM> and the PHY-L processing block <NUM> have been already described with reference to <FIG> and <FIG>. For example, the RF processing block <NUM> performs RF frontend operations such as power amplification, low noise amplification (LNA), ADC/DAC conversion, and uplink/downlink switching. For example, the first PHY entity <NUM> may perform FFT/IFFT, precoding, digital beamforming, and PRACH filtering by means of the PHY-L processing block <NUM>.

Meanwhile, the first PHY entity (or MMU) <NUM> communicates messages with the second PHY entity (or LDU that is described later) by means of the fronthaul interface <NUM>. The fronthaul interface block <NUM> may send the second PHY entity a signal produced by processing an RF signal in the first PHY entity <NUM> and process a signal from the second PHY entity and send the processed signal to the RF processing block <NUM> in order for the RF processing block <NUM> to produce an RF signal. For example, the fronthaul interface block <NUM> of the first PHY entity <NUM> may perform packetization/depacketization on the messages being exchanged with the second PHY entity <NUM> for communication via an Ethernet protocol.

<FIG> shows a detailed configuration of the second PHY entity described with reference to <FIG>. The second entity in charge of one or more functions with the exception of the RF function among the physical layer functions of the base station, which may also be referred to as a light digital unit (LDU) <NUM>, includes a fronthaul interface block <NUM> for communication with the first PHY entity (or MMU) and a PHY-H processing block <NUM> for performing some functions (i.e., higher physical layer functions) of the physical layer. The operations being performed by the PHY-H processing block <NUM> have been already described with reference to <FIG> and <FIG>. For example, the second PHY entity <NUM> may perform channel coding/decoding, modulation/demodulation, channel estimation/equalization, RE mapping/de-mapping, and layer mapping by means of the PHY-H processing block <NUM>.

Meanwhile, the second PHY entity (or LDU) <NUM> communicates messages with the first PHY entity (or MMU) by means of the fronthaul interface block <NUM>. The fronthaul interface block <NUM> may process a signal received from the first PHY entity <NUM> or send a signal to be transmitted to the first PHY entity <NUM>. For example, the fronthaul interface block <NUM> of the second PHY entity <NUM> may perform packetization/depacketization on the messages being exchanged with the first PHY entity <NUM> for communication via an Ethernet protocol.

As described with reference to <FIG> and <FIG>, by splitting the physical layer functions into the first PHY entity (or MMU) and the second PHY entity (or LDU), it is possible to reduce a burden of the fronthaul bandwidth between the first and second PHY entities in comparison with the RU-DU configuration described with reference to <FIG>. Furthermore, because the MMU is responsible for some physical layer functions, it may be possible to reduce a burden caused by frequent replacement of the MMU as is necessary for compliance with the evolving standard, especially when it has been deployed on the rooftop of a building or a telephone pole.

As described with reference to <FIG> and <FIG>, the first PHY entity (i.e., MMU) and the second PHY entity (i.e., LDU) may be established as physically separate devices responsible for some physical layer functions of their own. That is, the first and second PHY entities may be established as separate hardware devices communicating with each other through a wireline or wireless link via a fronthaul interface. It may also be possible to establish first and second PHY entities that are logically separated in a hardware device.

<FIG>, <FIG>, and <FIG> are diagrams illustrating split physical layer architectures according to a disclosed embodiment. <FIG> and <FIG> each show exemplary architectures of the split physical layer for downlink transmission, and <FIG> shows an exemplary architecture of the split physical layer for uplink transmission.

<FIG> shows an exemplary split physical layer architecture for applying the split physical layer described with reference to <FIG> and <FIG> to an LTE/LTE-A communication system. That is, the split physical layer architecture <NUM> of <FIG> shows the split physical layer implemented in an eNB as a base station of the LTE/LTE-A communication system. In <FIG>, the physical layer of the eNB may be split into a first PHY entity (or MMU) <NUM> and a second PHY entity (or LDU) <NUM>, which are connected to each other via a fronthaul <NUM>. The fronthaul <NUM> may also be referred to as xRAN fronthaul (FH).

<FIG> shows an exemplary split physical layer architecture for applying the split physical layer described with reference to <FIG> and <FIG> to an NR communication system. That is, the split physical layer architecture <NUM> of <FIG> shows the split physical layer implemented in a gNB as a base station of the NR communication system. In <FIG>, the physical layer of the gNB may be split into a first PHY entity (or MMU) <NUM> and a second PHY entity (or LDU) <NUM>, which are connected to each other via a fronthaul <NUM> similar to that in <FIG>.

<FIG> shows detailed physical layer operations along with signaling between a first PHY entity (or MMU) <NUM> and a second PHY entity (or LDU) <NUM> configured as described with reference to <FIG> and <FIG> via a fronthaul <NUM>.

The first PHY entity responsible for some functions including the RF function among the physical layer functions and the second PHY entity responsible for remaining physical layer functions have been described above. Although the description has been that the first and second PHY entities may be respectively referred to as MMU and LDU, other names can be used to specify the entities. For example, in association with a central unit-distributed unit (CU-DU) split in which all of the layers of the base station are split, the first and second PHY entities may be referred to as distributed unit lower layer part (DU-L) and distributed unit higher layer part (DU-H), respectively. As another example, in association with the RU-DU split of physical layer functions, the first and second PHY entities may be referred to as radio unit (RU) and lower layer split-central unit (LLS-CU), respectively. It is obvious that the first and second PHY entities can be called by other names.

Hereinabove, the description has been made in detail of the split of the physical layer functions of the base station. Descriptions are made hereinafter in detail of the messages being exchanged and signaling procedure between the first and second PHY entities.

<FIG> is a diagram illustrating message flows between two PHY entities according to a disclosed embodiment. Messages being exchanged between a first PHY entity (or MMU) <NUM> and a second PHY entity (or LDU) <NUM> may be sorted into user plane messages and radio-specific control plane messages.

The user plane messages being communicated between the first and second PHY entities <NUM> and <NUM> carry data to be transmitted to a terminal or data received from the terminal. According to an embodiment, the user plane messages may include an in-phase/quadrature (IQ) message <NUM>, an uplink IQ message <NUM>, a sounding reference signal (SRS) message <NUM>, and a physical random access channel (PRACH) message <NUM>. According to an embodiment, the control plane messages may include an RE bitmap message <NUM>, a physical resource block (PRB) bitmap message <NUM>, a scheduling information message <NUM>, and a UE channel information message <NUM>.

The aforementioned messages are described in detail hereinafter.

The user plane messages abide by a message format defined in the IEEE standard <NUM>. The type of a user plane message is indicated by a subtype field value in a radio-over-Ethernet (ROE) header. Table <NUM> shows subtype field values and types of user plane messages.

In Table <NUM>, the subtype field values 00010001b, 00010010b, and 00010011b may indicate the IQ, PRACH, and SRS messages, respectively.

The control plane messages also abide by a message format defined in the IEEE standard <NUM>. The type of a control plane message may be indicated by a combination of the subtype field value in the ROE header and a radio-specific (RS) control header field value in an RS control header of the data. For example, in Table <NUM>, the subtype field value 00011000b may indicate a control plane message, and the subtype of the control message may be indicated by an RS control type field value as shown in Table <NUM>.

Tables <NUM> and <NUM> are illustrative of exemplary embodiments of the tables for use in indicating the type of a message between the first and second PHY entities. That is, the type of a message being exchanged between the first and second PHY entities may be indicated in a different manner, by a different field, or with a different value.

Hereinafter, detailed descriptions are made of the message structures with reference to <FIG>.

<FIG> is a diagram illustrating a structure of a user plane message according to a disclosed embodiment. In the message structure shown in <FIG>, the subtype field <NUM> in the ROE header may be set to a value indicative of inclusion of a user plane message in the data field <NUM> of the message. The value of the subtype field <NUM> may also indicate the type of the user plane message.

In the embodiment of <FIG>, the subtype field <NUM> may be set to <NUM> (00010001b in Table <NUM>) indicative of inclusion of an IQ message <NUM> in the data field <NUM>, <NUM> (00010010b in Table <NUM>) indicative of inclusion of a PRAC message <NUM> in the data field <NUM>, or <NUM> (00010011b in Table <NUM>) indicative of inclusion of an SRS message <NUM>) in the data field <NUM>.

<FIG> is a diagram illustrating a structure of a control plane message according to a disclosed embodiment. In the message structure shown in <FIG>, the subtype field <NUM> of the ROE header may be set to a predetermined value to indicate inclusion of a control plane message in the data field <NUM>. The subtype field <NUM> is set to a value (e.g., 00011000b in Table <NUM>) indicative of the inclusion of a control plane message, the RS control type field <NUM> in the data field <NUM> may be set to a value indicative of the type of data included in the payload <NUM>.

For example, the RS control type field <NUM> may be set to one of the values listed in Table <NUM> to indicate inclusion of an RE bitmap message <NUM>, a PRB bitmap message <NUM>, a scheduling information message <NUM>, or a UE channel information message <NUM> in the payload <NUM>.

<FIG> is a diagram illustrating a detailed format of an IQ message. The IQ message <NUM> may be used to convey frequency domain IQ samples in uplink or downlink. The data field <NUM> of the IQ message <NUM> may contain IQ values for the first subcarrier of the first RB to the <NUM>th subcarrier of the Nth RB, the IQ values being packetized in order; each IQ value may be represented by less than <NUM> bits. The number of bits for representing an IQ value may be preconfigured between the first and second PHY entities during a cell setup phase.

<FIG> is a diagram illustrating a detailed format of a PRACH message. The PRACH message <NUM> may be used to convey time domain (or frequency domain) PRACH IQ samples in uplink. The data field <NUM> of the PRACH message <NUM> may contain IQ samples packetized in a time domain sampling order; each IQ value may be represented by less than <NUM> bits. The number of bits for representing an IQ value may be preconfigured between the first and second PHY entities during a cell setup phase.

<FIG> is a diagram illustrating a detailed format of an SRS message. The SRS message <NUM> may be used to convey frequency domain SRS IQ samples in uplink. The data field <NUM> of the SRS message <NUM> may contain IQ values for the first subcarrier of the first RB to the <NUM>th subcarrier of the Nth RB, the IQ values being packetized in order; each IQ value may be represented by less than <NUM> bits. The number of bits for representing an IQ value may be preconfigured between the first and second PHY entities during a cell setup phase.

<FIG> is a diagram illustrating a detailed format of an RE bitmap message. The RE bitmap message <NUM> may include weight indices indicating types of beam weights to be applied to individual REs. The payload <NUM> in the data field of the RE bitmap message <NUM> may contain weight indices for the first RE of the first symbol of the first RB to the <NUM>th RE of the <NUM>th symbol of the Nth RB, the weight indices being packetized in order; the RB size N may be preconfigured between the first and second PHY entities during a cell setup phase.

<FIG> is a diagram illustrating a detailed format of a PRB bitmap message. The PRB bitmap message <NUM> may include information indicating whether each RB is used for cell-specific beamforming or UE-specific beamforming. The payload <NUM> in the data field <NUM> of the PRB bitmap message <NUM> may contain from cell-specific beamforming indicator for the first RB to cell-specific beamforming indicator for the Nth RB, the cell-specific beamforming indicators being packetized in order. A cell-specific indicator has a length of <NUM> bit, which is set to 0b to indicate UE-specific beamforming and 1b to indicate cell-specific beamforming. The RB size N may be preconfigured between the first and second PHY entities during a cell setup phase.

<FIG> is a diagram illustrating a detailed format of a scheduling information message. The scheduling information message <NUM> may include information indicating a terminal to which each RB is allocated. The payload <NUM> in the data field <NUM> of the scheduling information message <NUM> starts by encapsulating an uplink/downlink indicator that is set to <NUM> for downlink and <NUM> for uplink. The uplink/downlink indicator is followed by UE IDs of the terminal to which the first RB is allocated on the first layer to the terminal to which the Nth RB is allocated on the Lth layer, UE IDs being arranged in order in the payload <NUM>. The RB size N may be preconfigured between the first and second PHY entities during a cell setup phase.

<FIG> is a diagram illustrating a detailed format of a UE channel information message. The UE channel information message <NUM> may include channel information of a specific terminal. The payload <NUM> in the data field <NUM> of the UE channel information message <NUM> encapsulates a UE ID having a length of <NUM> bits indicative of a specific terminal, an RB location having a length of <NUM> bits indicative of an SRS RB location for the specific terminal, and an RB size having a length of <NUM> bits indicative of an SRS RB size for the specific terminal in order. The UE ID, RB location, and RB size are followed by IQ values for the RB location for the first antenna to the RB size+RB location for the Mth antenna, IQ values being arranged in order in the payload <NUM>. Each IQ value may be represented by less than <NUM> bits, and the number of bits for representing an IQ value and the number of antennas M may be preconfigured between the first and second PHY entities during a cell setup phase.

Hereinafter, descriptions are made of the procedures for communicating the messages formatted as shown in <FIG> between the first and second PHY entities.

<FIG> is a message flow diagram illustrating physical layer message flows in a PRACH transmission procedure according to a disclosed embodiment. <FIG> shows message flows between a terminal <NUM> and a base station <NUM> and among a first PHY entity (i.e., MMU) <NUM>, a second PHY entity (i.e., LDU) <NUM>, and a CU <NUM> constituting the base station <NUM>. The CU <NUM> may be an entity operating on at least one layer excluding the physical layer in the base station, e.g., an entity operating on at least one of MAC, RLC, PDCP, and RRC layers. In <FIG>, the first and second entities <NUM> and <NUM> may each be responsible for at least some of physical layer functions of the base station <NUM> and may be established to be responsible for all of the physical layer functions. The first and second PHY entities <NUM> and <NUM> and the CU <NUM> may be connected to each other to be responsible for all layer functions of the base station <NUM>.

In <FIG>, the terminal <NUM> transmits, at operation <NUM>, a random access preamble to the base station <NUM> for initial access to the base station <NUM>. The terminal <NUM> may transmit the random access preamble to the base station <NUM> through a PRACH selected according to a predetermined rule. The first PHY entity <NUM> responsible for the RF function of the base station <NUM> receives the random access preamble transmitted by the terminal <NUM>, and the PHY-L processing block <NUM> described with reference to <FIG> performs PRACH filtering on a signal transmitted by the terminal to extract the random access preamble. Next, the first PHY entity <NUM> sends a PHRACH message to the second PHY entity <NUM> at operation <NUM>. The PRACH message <NUM> transmitted by the first PHY entity <NUM> may have the format described with reference to <FIG>.

The second PHY entity <NUM> processes the received PRACH message <NUM> to determine whether to allow the initial access of the terminal <NUM> at operation <NUM> and, if it is determined to allow the initial access of the terminal <NUM>, sends a random access response (RAR) message <NUM> to the first PHY entity <NUM> at operation <NUM>. Next, the first PHY entity <NUM> may transmit an RAR to the terminal <NUM> at operation <NUM>.

<FIG> is a message flow diagram illustrating physical layer message flows in an SRS message transmission procedure according to a disclosed embodiment. <FIG> shows message flows between a terminal <NUM> and a base station <NUM> and among a first PHY entity (i.e., MMU) <NUM>, a second PHY entity (i.e., LDU) <NUM>, and a CU <NUM> constituting the base station <NUM>. The CU <NUM> may be an entity operating on at least one layer excluding the physical layer in the base station, e.g., an entity operating on at least one of MAC, RLC, PDCP, and RRC layers. In <FIG>, the first and second entities <NUM> and <NUM> may each be responsible for at least some of physical layer functions of the base station <NUM> and may be established to be responsible for all of the physical layer functions. The first and second PHY entities <NUM> and <NUM> and the CU <NUM> may be connected to each other to be responsible for all layer functions of the base station <NUM>.

In <FIG>, the terminal <NUM> may transmit an SRS to the base station <NUM> at operation <NUM> in order for the base station <NUM> to estimate an uplink channel. The first PHY entity <NUM> receives the SRS transmitted by the terminal <NUM> and sends the received SRS to the second PHY entity <NUM> because the SRS is processed by the PHY-H processing block <NUM> of the second PHY entity <NUM> as described with reference to <FIG>. That is, the first PHY entity <NUM> sends the SRS message to the second PHY entity <NUM> at operation <NUM>. The SRS message sent by the first PHY entity may have the format described with reference to <FIG>.

The second PHY entity <NUM> may process the message received at operation <NUM> to estimate the uplink channel at operation <NUM> by means of the PHY-H processing block <NUM> of the second PHY entity <NUM> as described with reference to <FIG>.

<FIG> is a message flow diagram illustrating physical layer message flows for making a beamforming/precoding weight determination by transmitting an RE bitmap message, a PRB bitmap message, a scheduling information message, and a UE channel information message according to a disclosed embodiment. <FIG> shows message flows between a terminal <NUM> and a base station <NUM> and among a first PHY entity (i.e., MMU) <NUM>, a second PHY entity (i.e., LDU) <NUM>, and a CU <NUM> constituting the base station <NUM>. The CU <NUM> may be an entity operating on at least one layer excluding the physical layer in the base station, e.g., an entity operating on at least one of MAC, RLC, PDCP, and RRC layers. In <FIG>, the first and second entities <NUM> and <NUM> may each be responsible for at least some of physical layer functions of the base station <NUM> and may be established to be responsible for all of the physical layer functions. The first and second PHY entities <NUM> and <NUM> and the CU <NUM> may be connected to each other to be responsible for all layer functions of the of the base station <NUM>.

In <FIG>, the second PHY entity <NUM> may send the first PHY entity <NUM> an RE bitmap message at operation <NUM>, a PRB message at operation <NUM>, a scheduling information message at operation <NUM>, and a UE channel information message at operation <NUM>. The second PHY entity <NUM> may transmit the above messages to the first PHY entity all together or independently of each other at different time points as shown in <FIG>. The second PHY entity <NUM> may first send two or more messages among the messages shown in <FIG> and proceed to send remaining messages in such an exemplary way of sending the RE bitmap message <NUM> and the PRB bitmap message <NUM> to the first PHY entity <NUM> first and proceeding to send the scheduling information message <NUM> and the UE channel information message <NUM> to the first PHY entity <NUM>.

Meanwhile, the first PHY entity <NUM> may determine, at operation <NUM>, beamforming/precoding weights for transmitting a signal to the terminal based on at least one of the messages received from the second PHY entity <NUM>. The first PHY entity <NUM> may determine the beamforming/precoding weights based on some of the messages received from the second PHY entity <NUM>, referencing radio resources to be allocated and a terminal to which the radio resources are allocated that are indicated in the scheduling information message. The first PHY entity <NUM> may also take the channel information of the terminal into consideration for determining the beamforming/precoding weights.

In the embodiment of <FIG>, the RE bitmap message, the PRB bitmap message, the scheduling information message, and the UE channel information message may have the formats that have been respectively described with reference to <FIG>.

<FIG> is a message flow diagram illustrating physical layer message flows in a downlink IQ message transmission procedure according to a disclosed embodiment. <FIG> shows message flows between a terminal <NUM> and a base station <NUM> and among a first PHY entity (i.e., MMU) <NUM>, a second PHY entity (i.e., LDU) <NUM>, and a CU <NUM> constituting the base station <NUM>. The CU <NUM> may be an entity operating on at least one layer excluding the physical layer in the base station, e.g., an entity operating on at least one of MAC, RLC, PDCP, and RRC layers. In <FIG>, the first and second entities <NUM> and <NUM> may each be responsible for at least some of physical layer functions of the base station <NUM> and may be established to be responsible for all of the physical layer functions. The first and second PHY entities <NUM> and <NUM> and the CU <NUM> may be connected to each other to be responsible for all layer functions of the of the base station <NUM>.

In <FIG>, the CU <NUM> may send downlink user data processed by a higher layer to the second PHY entity <NUM> at operation <NUM> via an interface established between the CU <NUM> as an entity responsible for higher layer functions and the second PHY entity <NUM>. The interface may be referred to as F1 interface, by way of example, or mid-haul interface considering that the interface between the first and second PHY entities has been named fronthaul interface.

The second PHY entity <NUM> may convert the received downlink user data to IQ data and send a downlink IQ message including the converted IQ data to the first PHY entity <NUM> at operation <NUM>. The IQ message being sent by the second PHY entity <NUM> may have the format described with reference to <FIG>, and the first PHY entity <NUM> generates an RF signal based on the received IQ data and transmits the RF signal to the terminal <NUM> in downlink at operation <NUM>. Here, the first PHY entity <NUM> may generate the signal by applying a beamforming/precoding weight determined according to the procedure described with reference to <FIG> and transmitting the generated signal.

<FIG> is a message flow diagram illustrating physical layer message flows in an uplink IQ message transmission procedure according to a disclosed embodiment. <FIG> shows message flows between a terminal <NUM> and a base station <NUM> and among a first PHY entity (i.e., MMU) <NUM>, a second PHY entity (i.e., LDU) <NUM>, and a CU <NUM> constituting the base station <NUM>. The CU <NUM> may be an entity operating on at least one layer excluding the physical layer in the base station, e.g., an entity operating on at least one of MAC, RLC, PDCP, and RRC layers. In <FIG>, the first and second entities <NUM> and <NUM> may each be responsible for at least some of physical layer functions of the base station <NUM> and may be established to be responsible for all of the physical layer functions. The first and second PHY entities <NUM> and <NUM> and the CU <NUM> may be connected to each other to be responsible for all layer functions of the base station <NUM>.

In <FIG>, the terminal <NUM> generates and transmits an uplink signal to the base station <NUM> at operation <NUM>, and the first PHY entity <NUM> of the base station <NUM> converts the received signal to IQ data and sends the IQ data to the second PHY entity <NUM>. The first PHY entity <NUM> may send the second PHY entity <NUM> an uplink IQ message including the IQ data at operation <NUM>, the uplink IQ message having the format described with reference to <FIG>. The first PHY entity <NUM> may apply a beamforming/precoding weight determined according to the procedure described with reference to <FIG> in the procedure of converting the signal received from the terminal <NUM> to the IQ data.

The second PHY entity <NUM> processes the received IQ data to send uplink user data to the CU <NUM> at operation <NUM> via an interface established between the CU <NUM> as an entity responsible for higher layer functions and the second PHY entity <NUM>. This interface may be referred to as F1 interface, by way of example, or mid-haul interface considering that the interface between the first and second PHY entities has been named fronthaul interface.

Claim 1:
A method performed by a first entity (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) performing high physical layer functions of a base station in a wireless communication system, the method comprising:
identifying a fronthaul interface (<NUM>, <NUM>, <NUM>, <NUM>) between the first entity and a second entity (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) performing low physical layer functions of the base station; and
exchanging a control plane message or a user plane message with the second entity via the fronthaul interface,
wherein the low physical layer functions include a precoding and a digital beamforming for a downlink and a digital beamforming for an uplink,
wherein the high physical layer functions include a modulation and a resource element, RE, mapping for the downlink and a demodulation and a RE demapping for the uplink, and
wherein the control plane message and the user plane message are identified based on a subtype field of radio over ethernet, ROE.