SYSTEM AND METHOD FOR DELAY MEASUREMENT IN FRONTHAUL NETWORKS USING HARDWARE TIMESTAMPS - Patent application

Abstract

An open radio access network (O-RAN) includes an O-RAN radio unit (O-RU) configured to transmit radio signals to user equipment, an O-RAN distributed unit (O-DU) configured to perform baseband processing, and a fronthaul network, wherein the O-RU and the O-DU are nodes of the fronthaul network, and the O-RU and the O-DU are configured to communicate through the fronthaul network. The O-DU is configured to transmit a one-way delay measurement message to the O-RU of the fronthaul network, the one-way delay measurement message including a value based on a hardware timestamp inserted immediately before transmitting the one-way delay measurement message. The O-RU is configured to transmit a response to the one-way delay measurement message to the O-DU, the response including a second value based on a second hardware timestamp generated when the O-RU receives the one-way delay measurement message from the fronthaul network.

Description

[Technical Field]

[0001] This disclosure relates to measuring delay in a network, and more particularly, to measuring delay in a fronthaul network using hardware time stamping. [Background technology]

[0002] A network may include nodes interconnected by various network links. The nodes may transmit various data and messages between them. To meet certain requirements, the time delay for transmitting data and messages between different nodes may need to be maintained within a certain threshold. Therefore, it may be important to accurately measure the time delay in a network.

[0003] It should be noted that the above information on the background art is provided for a clear and complete description of the present disclosure and simply for ease of understanding by those skilled in the art, and it should not be inferred that any of the above information is known to those skilled in the art. Summary of the Invention [Means for solving the problem]

[0004] Currently, there is no deterministic method for measuring delay in a fronthaul network. According to a particular embodiment, an Open Radio Access Network (O-RAN) includes an O-RAN Radio Unit (O-RU) configured to transmit radio signals to user equipment, an O-RAN Distributed Unit (O-DU) configured to perform baseband processing, and a fronthaul network, where the O-RU and O-DU are nodes of the fronthaul network and the O-RU and O-DU are configured to communicate over the fronthaul network, the O-DU configured to transmit a one-way delay measurement message to the O-RU of the fronthaul network, the one-way delay measurement message including a value based on a hardware timestamp inserted immediately before transmission of the one-way delay measurement message, and the O-RU configured to transmit a response to the one-way delay measurement message to the O-DU, the response including a second value based on a second hardware timestamp generated when the O-RU receives the one-way delay measurement message from the fronthaul network.

[0005] According to a particular embodiment, a method for one-way delay measurement includes generating a one-way delay measurement message including a packet at an open radio access network (O-RAN) distributed unit (O-DU), inserting a timestamp into an application layer of the packet, inserting a hardware timestamp into a transport layer of the packet, transmitting the one-way delay measurement message from the O-DU to an O-RAN radio unit (O-RU) over a fronthaul network immediately after inserting the hardware timestamp, inserting a second hardware timestamp into the packet immediately after the O-RU receives the one-way delay measurement message, generating a response message to the one-way delay measurement message by the O-RU, the response message including the second packet, inserting the second timestamp and a value by the O-RU into the second packet, the value being a difference between the second timestamp and the second hardware timestamp, and transmitting the response message from the O-RU to the O-DU over the fronthaul network.

[0006] According to a particular embodiment, a communication system includes a node configured to generate a message including a packet, insert a timestamp at an application layer of the packet, insert a hardware timestamp at a transport layer of the packet, and transmit the message to a second node over a network immediately after inserting the hardware timestamp, and a second node configured to receive a message from the node over the network, insert a second hardware timestamp at the transport layer of the packet immediately after receiving the message, generate a response including the second packet, insert the second timestamp and a value in the second packet, where the value is the difference between the second timestamp and the second hardware timestamp, and transmit the response to the node over the network. [Brief explanation of the drawings]

[0007] These and other aspects, features, and advantages of particular embodiments of the present disclosure will become apparent from the following description taken in conjunction with the accompanying drawings.

[0008] In order to better understand the drawings referred to herein, a brief description of each drawing is provided.

[0009] [Figure 1A] 1 is a block diagram of a wireless communication system in accordance with certain embodiments of the present disclosure. [Figure 1B] FIG. 1 is a block diagram of a radio access network in accordance with certain embodiments of the present disclosure. [Figure 2] FIG. 1 is a block diagram of a fronthaul network in accordance with certain embodiments of the present disclosure. [Figure 3A] FIG. 2 is a block diagram illustrating downlink one-way delay measurement in accordance with certain embodiments of the present disclosure. [Figure 3B] FIG. 2 is a block diagram illustrating uplink one-way delay measurement in accordance with certain embodiments of the present disclosure. [Figure 4] FIG. 2 is a block diagram of a one-way delay measurement message in accordance with certain embodiments of the present disclosure. [Figure 5] FIG. 2 is a block diagram illustrating one-way delay measurement in accordance with certain embodiments of the present disclosure. [Figure 6] FIG. 1 is a block diagram of an Open Radio Access Network (O-RAN) Distributed Unit (O-DU) in accordance with certain embodiments of the present disclosure. [Figure 7] FIG. 1 is a block diagram of an O-RAN radio unit (O-RU) in accordance with certain embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present disclosure provides deterministic delay measurement in a fronthaul network by using hardware timestamps. The fronthaul network can form part of a wireless communication system. FIG. 1A discloses a wireless communication system. The fronthaul network can exist between a radio access network (RAN) of a base station involved in wireless communication with user equipment (UE) and a core network. More specifically, as shown in FIG. 1B, a base station of the RAN includes two logical entities: a radio unit (RU), such as an open radio access network (O-RAN) radio unit (O-RU), and a distributed unit (DU), such as an ORAN distributed unit (O-DU). The RU / O-RU is the last node that connects to the UE, while the DU / O-DU connects to the core network. The fronthaul network is between the RU / O-RU and the DU / O-DU, as disclosed in both FIG. 1B and FIG. 2.

[0011] Nodes in the fronthaul network (RU / O-RU and DU / O-DU) may operate with very narrow transmission and reception windows. Therefore, it may be important to routinely measure network delay. FIGS. 3A and 3B disclose a delay measurement procedure. The delay measurement procedure uses a correction value that accounts for the delay between the start of the delay measurement, the actual transmission of the one-way delay measurement message, and the actual reception and detection of the one-way delay measurement message. FIG. 4 shows packets used to communicate various times, including the correction value. In FIG. 5, the correction value is based on a hardware timestamp indicating the time the one-way delay measurement message is transmitted and received in the fronthaul network. FIGS. 6 and 7 describe an O-DU and an O-RU configured to perform the operations described herein.

[0012] The present disclosure is susceptible to various modifications and numerous examples, and specific embodiments are shown in the drawings and described in detail herein. However, it is not intended to limit the disclosure to any particular mode of implementation, and it is to be understood that the present disclosure encompasses all modifications, equivalents, and alternatives that do not depart from the spirit and scope of the present disclosure.

[0013] In the description of the embodiments, specific detailed descriptions of related technologies will be omitted if they are deemed to unnecessarily obscure the essence of the present disclosure. Also, numbers (e.g., first, second, etc.) used in the description of the embodiments are merely identifier codes for distinguishing one element from another.

[0014] It will also be understood that in this disclosure, when elements are "coupled" or "connected" to one another, the elements may be directly connected or coupled to one another, but may alternatively be connected or coupled to one another through intervening elements, unless otherwise specified.

[0015] In this specification, elements described as "units" or "modules" may be combined into one element, or one element may be divided into two or more elements, depending on the subdivided functions. Furthermore, each element described below may perform some or all of the functions performed by other elements in addition to its own main function, or some of the main functions of each element may be performed by other components.

[0016] Throughout this disclosure, the phrase "at least one of a, b, or c" refers to a only, b only, c only, both a and b, both a and c, both b and c, all of a, b, and c, or variations thereof.

[0017] Continuing, embodiments of the present disclosure will now be more fully described with reference to the accompanying drawings, in which:

[0018] 1A is a block diagram of a communication system 100 in which certain embodiments of the present disclosure may be implemented. The communication system 100 includes a user equipment (UE) 105, a radio access network (RAN) 110 of a base station 110′, and a core network 115.

[0019] The UE 105 may take various forms, such as a smartphone, a personal computer (PC), a user device, a smart watch, a laptop computer, a tablet computer, a personal digital assistant (PDA), a server, a CD / DVD player, an MP3 player, a Global Positioning System (GPS) device, a video player, a game console, a handheld communication device, a workstation, a router, an access point, and any combination thereof. In particular embodiments, the UE 105 may comprise an Internet of Things (IoT) device. Furthermore, in particular embodiments, the UE 105 may include, for example, a display, a power source, a speaker, a microphone, memory, a buffer, and a radio. Furthermore, the UE 105 may be capable of communicating with a wireless network, such as a 3G, 4G, or 5G NR network.

[0020] The UE 105 transmits wirelessly to and from a base station 110′ of the RAN 110. The base station 110′ can include, but is not limited to, a Node B (NB) as in LTE, an evolved Node B (eNB) as in LTE-A, a radio network controller (RNC) as in UMTS, a base station controller (BSC) as in GSM / GERAN, a New Radio evolved Node B (NR eNB) as in NR, a next generation Node B (gNB) as in NR, and any other device capable of controlling wireless communications and managing radio resources within a cell. The base station can be connected to serve one or more UEs via an air interface to the network.

[0021] The base station 110′ may be configured to provide communication services via at least one of the following radio access technologies (RATs): Worldwide Interoperability for Microwave Access (WiMAX), Global System for Mobile communications (GSM, often referred to as 2G), GSM EDGE radio access Network (GERAN), General Packet Radio Service (GPRS), Universal Mobile Telecommunications System (UMTS, often referred to as 3G) based on basic wideband-code division multiple access (W-CDMA), High Speed ​​Packet Access (HSPA), LTE, LTE-A, New Radio (NR, often referred to as 5G), and / or LTE-A Pro. However, the scope of this disclosure should not be limited to the aforementioned protocols.

[0022] The base station 110' is operable to provide wireless coverage to a particular geographic region using multiple cells forming the RAN 110. The base station 110' supports the operation of the cells. More specifically, each cell (often referred to as a serving cell) serves one or more UEs within its wireless range (e.g., each cell schedules downlink and optionally uplink resources for downlink and optionally uplink packet transmissions to at least one UE within its wireless range). The base station 110' can communicate with one or more UEs of the wireless communication system via the multiple cells.

[0023] The core network 115 may connect to the Internet, provider networks, land networks, and other networks, which in turn may facilitate communication with other UEs, servers, and landlines.

[0024] 1B, the base station 110 of the RAN 110′ may include a radio unit (RU) 111 and a distributed unit (DU) 112. The RU 111 may include a base station front end co-located with an antenna. The RU 111 receives uplink signals from the UE 105 and transmits downlink signals to the UE. The RU 111 may include a transceiver where radio frequency signals are transmitted, received, modulated, demodulated, amplified, and digitized. The RU 111 may host the PHY-Low layer.

[0025] The DU 112 performs real-time baseband processing functions and can be centralized or located near the cell site. The DU 112 cooperates with the lowest layers of the protocol stack, such as the Radio Link Control (RLC), Medium Access Control (MAC), and Physical (PHY) layers. The DU 112 aggregates and processes inbound traffic from multiple RUs 111, or processes, separates, and distributes traffic to multiple RUs. The DU 112 is connected to the core network 115 via a central unit (not shown).

[0026] The communication network between the RU 111 and the DU 112 is called a fronthaul (FH) network, whereas the communication network between the DU 112 and the core network 115 is called a backhaul network.

[0027] In certain embodiments, the RAN 110 may include an Open RAN (O-RAN) in accordance with the O-RAN Alliance. The O-RAN Alliance was established to promote openness and improve intelligence in the Radio Access Network (RAN) in the 5G era. Accordingly, the RU 111 may include an O-RU 111, and the DU 112 may include an O-DU 112. In O-RAN, the shared functionality between the O-RU 111 and the O-DU 112 is located at the physical layer (PHY), so strict timing accuracy is desirable. For this reason, FH delay management is performed, and transmit and receive windows are used. The following describes an embodiment using O-RAN, with the understanding that the present disclosure is not limited to O-RAN.

[0028] 2, there is a block diagram of a reference point for delay management in an O-RAN FH network 200, in accordance with a particular embodiment of the present disclosure. The FH network 200 includes an O-DU 112 and an O-RU 111 communicating through the FH network 200. The FH network 200 may have any number of intermediate nodes and switches, and transmissions from the O-DU 112 to the O-RU 111, and vice versa, may involve any number of hops. In the O-RAN FH network 200, it is desirable to keep the transport delay (uplink and downlink delay) within specified upper and lower bounds to respect the receive windows of the O-DU 112 and O-RU 111.

[0029] It should be understood that the present disclosure is not limited to the O-RAN FH interface 200. For example, particular embodiments may be used from various other nodes other than the O-RU 111 and the O-DU 112, including, but not limited to, Enhanced Common Public Radio Interface (eCPRI) radio equipment (eRE) or eCPRI radio equipment control (eREC). Furthermore, particular embodiments may use a network different from the FH network 200. Furthermore, embodiments are described in which the FH network 200 includes an optical fiber network, with the understanding that the present disclosure is not limited to an optical fiber network.

[0030] In the downlink, point R1 represents the port at which the O-DU 112 places a packet onto the optical fiber. Point R2 represents the port at which the O-RU 111 receives a packet from the optical fiber. Point Ra represents the antenna of the O-RU 111 that transmits the packet wirelessly to the UE 105. In the uplink, point R3 represents the port at which the O-RU 111 places a packet onto the optical fiber, and point R4 represents the port at which the O-DU 112 receives the packet from the optical fiber. In the downlink, time T12 is the time delay due to the optical fiber when a packet is transmitted from R1 of the O-DU 112 to R2 of the O-RU 111. In the uplink, time T34 is the time delay due to the optical fiber when a packet is transmitted from R3 of the O-RU 111 to R4 of the O-DU 112.

[0031] The Common Public Radio Interface: eCPRI Interface Specification V2.0 (now referred to as the "eCPRI Standard"), which is incorporated herein in its entirety for all purposes, defines delay model latency parameters T1a, T2a, Ta3, and Ta4. In the downlink, parameter T1a measures the total time delay of a packet from R1 of the O-DU 112 to the antenna (point Ra) of the O-RU 111 transmitting it over the air. Parameter T2a measures the time delay between receiving a packet at the O-RU 111 (point R2) and transmitting it over the air by the antenna (point Ra). In the uplink, parameter Ta4 measures the total time delay from receiving a packet from the antenna (point Ra) of the O-RU 111 to receiving the packet at R1 of the O-DU 112. Parameter Ta3 measures the time delay from receiving a packet from the antenna (point Ra) of the O-RU 111 to transmitting the packet at point R3 of the O-RU 111. The eCPRI standard defines minimum and maximum windows for the delay model latency parameters T1a, T2a, Ta3, and Ta4, e.g., T1amin, T1amax, T2amin, T2amax, Ta3min, Ta3max, Ta4min, and Ta4max.

[0032] To ensure compliance with the minimum and maximum windows of the delay model waiting time parameters, one of the O-RU 111 and O-DU 112 (the sender) can send a one-way delay measurement message to measure the time delay between the sender and the other of the O-RU 111 and O-DU 112 (the receiver).

[0033] 3A is a block diagram illustrating one-way delay measurement in the downlink in accordance with certain embodiments of the present disclosure. Again, while an O-RU 111 and an O-DU 112 are shown, it should be noted that the present disclosure is not limited thereto and other nodes may be used. At time t1, the O-DU 112 begins measuring T12 by generating a one-way delay measurement message 305. The message may include packets as described in more detail in FIG. 4.

[0034] There is a time lag between the generation and transmission of the message 305 at the application layer and the actual placement of the packet onto the optical fiber (point R1) of the FH network 200. For example, if the O-DU is virtualized, delays are introduced by the virtualization layer, the network interface card (NIC) processing time, and the Single Root Input / Output Virtualization (SRIOV) feature of the NIC. CV1 delay, i.e., time = t1 + t CV1 After that, message 305 is sent by the FH network 200 to the O-RU 111. Message 305 has timestamps t1 and t CV1 It may include a correction value for correcting the

[0035] Time t D , i.e., time = t1 + t CV1 +t D After time t has elapsed, O-RU 111 receives message 305. However, there is another delay t at O-RU 111 between the arrival of message 305 at time t and the detection of message 305 at the application layer. CV2 At time t2, the O-RU 111 places a timestamp t2 in the message. Then, the O-RU 111 calculates the received timestamps t2 and t CV1The O-RU 111 creates a response message 310 including a correction value for correcting t. The O-RU 111 transmits the response message to the O-DU 112. When the O-DU 112 receives the response message 310, the O-DU 112 D =(t2-t CV2 )-(t1+t CV1 ) to t D can be calculated.

[0036] 3B is a block diagram illustrating one-way delay measurement in the uplink according to certain embodiments of the present disclosure. The O-DU 112 sends a one-way delay measurement message along with a remote request 315. At time t1, the O-RU 111 initiates measurement of T34 by generating a one-way delay measurement message 320. The message may include packets described in more detail in FIG.

[0037] There is a time lag between the generation and transmission of message 320 at the application layer and the actual placement of the packet onto the optical fiber (point R3) of the FH network 200. For example, if the O-RU is virtualized, delays are introduced by the virtualization layer, the network interface card (NIC) processing time, and the single route input / output virtualization (SRIOV) feature of the NIC. CV1 delay, i.e., time = t1 + t CV1 After that, message 320 is sent by FH network 200 to O-RU 111. Message 320 includes timestamps t1 and t CV1 It may include a correction value for correcting the

[0038] Time t D , i.e., time = t1 + t CV1 +t D After time t has elapsed, O-RU 111 receives message 320. However, there is another delay t at O-RU 111 between the arrival of message 320 at time t and its detection at the application layer. CV2At time t2, the O-RU 111 places a timestamp t2 in the message. Then, the O-RU 111 calculates the received timestamps t2 and t CV1 The O-RU 111 creates a response message 325 including a correction value for correcting t. The O-RU 111 transmits the response message 325 to the O-DU 112. When the O-DU 112 receives the response message 325, the O-DU 112 D =(t2-t CV2 )-(t1+t CV1 ) to t D can be calculated.

[0039] FIG. 4 is a block diagram of a one-way delay measurement message according to an embodiment of the present disclosure. The one-way delay measurement message may include 20 bytes and L dummy bytes. Byte 0 may indicate a measurement identification (ID) to distinguish between other instances of the measurement. Messages associated with one one-way delay measurement may use the same measurement ID. For example, messages 305 and 310 in FIG. 3A may each carry the same measurement ID to indicate that messages 305 and 310 are related to the same instance of one-way delay measurement. Messages 315, 320, and 325 may carry the same measurement ID to indicate that messages 315, 320, and 325 are related to the same instance of one-way delay measurement.

[0040] Byte 1 may indicate whether the message is a request, a response, or a remote request. For example, byte 1 of message 315 may have an identifier indicating that the message is a remote request. Byte 1 of messages 305 and 320 may include an identifier indicating that the message is a one-way delay measurement message. Byte 1 of messages 310 and 325 may include an identifier indicating that the message is a response to a one-way delay measurement message.

[0041] Bytes 2-11 can be used to store a timestamp. For example, messages 305 and 320 can include a value indicating t1 in bytes 2-11. Messages 310 and 325 can include a value indicating t2 in bytes 2-11.

[0042] Bytes 12 to 19 are t CV1 or t CV2 For example, bytes 12-19 of messages 305 and 320 can be used to store the correction value of t CV1 Bytes 12-19 of messages 310 and 325 may contain a correction value of t CV2 It is possible to include a correction value for

[0043] t CV1 and t CV2 Note that an empirically determined estimate can be used for t. For example, an empirically determined estimate can be determined by averaging a large test sample. However, using an estimate is subject to error and does not provide a real-time deterministic measurement of FH delay. Furthermore, t CV1 and t CV2 remains constant, so the actual t CV1 and t CV2 It cannot handle a sudden spike.

[0044] Thus, in certain embodiments of the present disclosure, t CV1 and t CV2 The values ​​indicative of can be determined, for example, at points R1, R2, R3, and R4, based on hardware timestamps inserted immediately when the one-way delay measurement messages are transmitted in and received from the FH network 200.

[0045] For example, in the O-DU 112, the one-way delay measurement message is time-stamped at the L1 layer, e.g., t1 in FIG. 3A. Furthermore, the one-way delay measurement message also acquires a time stamp (HW Time Stamp1) by hardware just before the packet is placed in the FH network 200, e.g., at point R1. Therefore, t CV1 can be calculated as follows:

[0046] t CV1 =HW Time Stamp1-t1

[0047] The above more accurately represents the period from the start of the T12 measurement to the sending of the One-Way Delay Measurement Message 305.

[0048] At the O-RU 111, the one-way delay measurement message received from the O-DU 112 immediately acquires another hardware timestamp, for example at point R2, as well as timestamp t2. CV2 can be calculated as follows:

[0049] t CV2 =t2-HW Time Stamp2

[0050] The above more accurately represents the period between receipt of the One-Way Delay Measurement Message 305 and detection of receipt of the One-Way Delay Measurement Message 305 .

[0051] Therefore, the time delay t d T12, which is the temperature at which the temperature rises, continues to be measured by the following formula:

[0052] t D =(t2-t CV2 )-(t1+t CV1 )

[0053] Measurements are deterministic and real-time, CV1 and t CV2For example, the instantaneous change of the delay in each of O-DU112 and O-RU111 is t CV1 and t CV2 This results in a change in the value of

[0054] T1a can be measured as follows.

[0055] T1a=t2-t1+t CV1 +t CV2

[0056] On the uplink side (FIG. 3B), in the O-RU 111, the one-way delay measurement message 320 is time-stamped with the time t1 at which the measurement of T21 started (to avoid confusion, T 31 The one-way delay measurement message 320 is also time-stamped (T) by hardware just before being placed in the FH network 200. 32 ) and correspondingly, we obtain a new parameter T 3-内的遅延 represents the internal delay in the O-RU 111. The parameter T 3-内的遅延 is calculated as follows:

[0057] T 3-内的遅延 =T 32 -T 31

[0058] The one-way delay measurement message 320 is 3-内的遅延 and T 32 For example, the one-way delay measurement message 320 can be updated with T 3-内的遅延 It can include a hardware timestamp T 32 Field T 32-ネットワーク遅延 can be placed in

[0059] When the O-DU 112 receives the one-way delay measurement message 320, the one-way delay measurement message 320 is transmitted to the hardware (T 41 ) and the L1 layer, e.g., T 42 It is time-stamped.

[0060] Therefore, the parameter T 4-内的遅延 indicates the internal delay in the O-DU 112.

[0061] Parameter T 4-内的遅延 is calculated as follows:

[0062] T 4-内的遅延 =T 42 -T 41

[0063] Network latency, T 34-ネットワーク遅延 =T 41

[0064] The effective Ta4 parameter can be calculated as follows:

[0065] Ta4 delay = Ta3 + T 34-ネットワーク遅延 +T 4-内的遅延

[0066] Referring to FIG. 5, a signal flow diagram illustrating one-way delay measurement according to certain aspects of the present disclosure is shown. At 505, at the application level of the O-DU 112A, the O-DU 112 generates a one-way delay measurement message containing a packet and inserts a timestamp t1 into the application layer of the packet. At 510, the message containing the packet is sent for transmission through the NIC 112N in the O-DU (O-DU NIC). At 515, the O-DU NIC 112N inserts a hardware timestamp HW Time Stamp1 into the transport layer of the packet. In certain embodiments, the O-DU NIC 112N inserts a correction value t CV1 can be inserted and / or replaced, and t CV1 =HW Time Stamp1-t1.

[0067] Immediately after inserting the hardware timestamp, the O-DU transmits a one-way delay measurement request to the O-RU 111 at 520. It should be understood that in this case, HW Time Stamp1 follows "immediately" within a fixed period so as to substantially reflect the time when the O-DU transmitted the one-way delay measurement request. When the one-way delay measurement request is received by the NIC in the O-RU 111N, the O-RU NIC 111N immediately inserts a hardware timestamp, HW Time Stamp2, into the transport layer of the one-way delay measurement request packet at 523. It should be understood that in this case, HW Time Stamp2 follows "immediately" within a fixed period so as to substantially reflect the time when the O-RU NIC 111N received the one-way delay measurement request.

[0068] At 525, a one-way delay measurement request is received at the application level of the O-RU 111A. At 530, the O-RU 111A generates a response message that includes another packet. At 535, the O-RU 111A generates a response message that includes a timestamp t2 and a correction value t CV2 is inserted into the application layer of another packet. CV2 =t2-HW Time Stamp2. At 540, the O-RU sends a response to the O-DU.

[0069] In 545, the O-DU is d Determine where t d =t D =(t2-t CV2 )-(t1+t CV1 )

[0070] 6 is a block diagram of an O-DU 112 according to a specific embodiment of the present disclosure. The O-DU 112 can function as a baseband processing unit for processing the higher PHY layer, as well as the MAC and RLC layers with network function virtualization (NFV).

[0071] The O-DU 112 includes a transport NIC 605, CPU cores and memory 610, a data plane development kit (DPDK) 615, a Single Root Input / Output Virtualization (SRIOV) 620, a Field Programmable Gate Array (FPGA) / hardware accelerator 625, an IEEE 1588 Precision Time Protocol (PTP) module 630, a power supply 635, a Global Positioning Satellite (GPS) 640, and a second transport NIC 645.

[0072] CPU core and memory 610 may include one or more processors and store executable instructions that, when executed, cause the one or more processors to perform any of the operations described herein.

[0073] The transport NIC 605 transmits and receives packets to and from the FH network 200. The transport NIC 605 also inserts a hardware timestamp into packets received by or transmitted from the FH network 200.

[0074] FIG. 7 is a block diagram illustrating an O-RU 111 according to certain embodiments of the present disclosure. The O-RU 111 may be an electronic device including a processing subsystem 720 including at least one processor 724, 728 and at least one memory 722, 726 coupled to the at least one processor 724, 728. The at least one memory 722, 726 stores instructions executable by the at least one processor 724, 728 to perform the functions of the O-RU 111. The O-RU 111 also includes a local clock circuit 760 and a radio-frequency transceiver 750 for communicating with user equipment 105 via an antenna. The radio-frequency transceiver 750 may include one or more independently controllable transmitters and one or more receivers. In certain embodiments, one of the processors 724 may comprise a digital signal processor 724 that receives signals from the RF transceiver 750. A fronthaul link interface 740 couples the O-RU 111 to the FH network 200. In certain embodiments, the fronthaul link interface 740 may include a NIC.

[0075] In certain embodiments, the fronthaul link interface 740 via NIC inserts a hardware timestamp into packets transmitted over the FH network 200. For example, the NIC may selectively insert a hardware timestamp into the transport layer of a one-way delay measurement message. Additionally, in certain embodiments, the fronthaul interface 740 via NIC may update a correction value field with a value of the difference between the hardware timestamp and time t1.

[0076] It will be appreciated that in certain embodiments, the uplink delay and downlink delay may be separated and calculated at several layers rather than as a whole. The above provides a deterministic method for isolating modules or layers that are causing excessive delay and improving the FH network 200 in a more efficient manner. Furthermore, since existing FH networks generally include hardware timestamp functionality for PTP, it would be advantageous to extend the existing IEEE 1588 timestamp in the NIC for one-way delay measurement messages.

[0077] According to a particular embodiment, an open radio access network (O-RAN) 110 includes an O-RAN radio unit (O-RU) 111 configured to transmit radio signals to user equipment, an O-RAN distributed unit (O-DU) 112 configured to perform baseband processing, and a fronthaul network 200, where the O-RU and O-DU are nodes of the fronthaul network and are configured to communicate over the fronthaul network, the O-DU configured to transmit a one-way delay measurement message 305 to an O-RU of the fronthaul network, the one-way delay measurement message including a value based on a hardware timestamp (HW Time Stamp1) inserted immediately before transmitting the one-way delay measurement message, and the O-RU configured to transmit a response (310) to the one-way delay measurement message to the O-DU, the response including a second value based on a second hardware timestamp (HW Time Stamp2) generated when the O-RU receives the one-way delay measurement message from the fronthaul network.

[0078] According to a particular embodiment, the one-way delay measurement message includes a packet (FIG. 4), which includes a correction value field, which stores a value.

[0079] According to a particular embodiment, the response includes a second packet (FIG. 4), which includes a second correction value field, which stores a second value.

[0080] According to a particular embodiment, the O-DU determines the delay based at least in part on the value of the correction value field of the packet and the second value of the second correction value field of the second packet (FIG. 5, 545).

[0081] According to a particular embodiment, the O-DU comprises a network interface card (NIC) 605 that interfaces the O-DU with a fronthaul network, the NIC generating a hardware timestamp (515), and the O-RU comprises a second NIC 740 that interfaces the O-RU with the fronthaul network, the second NIC generating a second hardware timestamp (523).

[0082] According to a particular embodiment, a method for one-way delay measurement includes generating (505) a one-way delay measurement message including a packet at an open radio access network (O-RAN) distributed unit (O-DU), inserting (505) a timestamp into an application layer of the packet, inserting (515) a hardware timestamp into a transport layer of the packet, transmitting (520) the one-way delay measurement message from the O-DU to an O-RAN radio unit (O-RU) via a fronthaul network immediately after inserting the hardware timestamp, inserting (523) a second hardware timestamp into the packet immediately after the O-RU receives the one-way delay measurement message, generating (530) a response message to the one-way delay measurement message by the O-RU, the response message including the second packet, inserting (535) a second timestamp and a value into the second packet, the value being a difference between the second timestamp and the second hardware timestamp, and transmitting (540) the response message from the O-RU to the O-DU via the fronthaul network.

[0083] According to certain embodiments, the method further includes determining a delay based at least in part on the timestamp, the hardware timestamp, the second timestamp, and the correction value (545).

[0084] According to a particular embodiment, the method further includes inserting a second value into the packet by the O-DU, the second value being a difference between the hardware timestamp and the timestamp.

[0085] According to a particular embodiment, inserting the hardware timestamp includes inserting the hardware timestamp by a network interface card (NIC) that interfaces the O-DU with the fronthaul network (112N), and inserting the second hardware timestamp includes inserting the second hardware timestamp by a second NIC that interfaces the O-RU with the fronthaul network (111n).

[0086] According to certain embodiments, the communication system 100 includes a node 112 configured to generate a message (505) including a packet (FIG. 4), insert a timestamp t1 in the application layer of the packet (505), insert a hardware timestamp HW Time Stamp1 in the transport layer of the packet (515), and transmit the message (520) to a second node 111 over the network 200 immediately after inserting the hardware timestamp; and a second node configured to receive a message from the node over the network, insert a second hardware timestamp in the transport layer of the packet (523) immediately after receiving the message, generate a response (530) including the second packet (FIG. 4), insert a second timestamp t2, and transmit the second packet t3. CV2 and a value of (535) where the value is the difference between the second timestamp and the second hardware timestamp, and transmitting (540) a response to the node over the network.

[0087] According to a particular embodiment, the node may include a second value t in the application layer correction value field of the packet. CV1 (FIG. 4), where the second value is the difference between the hardware timestamp and the timestamp.

[0088] According to a particular embodiment, the node comprises an Open Radio Access Network (O-RAN) Distributed Unit (O-DU) 112 .

[0089] According to a particular embodiment, the second node comprises an O-RAN Radio Unit (O-RU) 111.

[0090] In a particular embodiment, the network includes a fronthaul network 200 .

[0091] According to a particular embodiment, the second node is configured to insert a value into a correction value field of the second packet.

[0092] According to a particular embodiment, the second node inserts a second timestamp in the application layer of the second packet and a value of the correction value field in the application layer of the second packet.

[0093] According to certain embodiments, the node is further configured to receive (540) a response from the second node over the network and determine (545) a delay based at least in part on the second timestamp, the value of the offset value field of the second packet, the hardware timestamp, and the timestamp.

[0094] According to a particular embodiment, the node includes a network interface card (NIC) 605 configured to generate a hardware timestamp.

[0095] According to a particular embodiment, the second node includes a second NIC 740 configured to generate a second hardware timestamp.

[0096] According to a particular embodiment, the message comprises a one-way delay measurement message.

[0097] The above-described embodiments may be stored as a program on a machine-readable storage medium. The machine-readable storage medium may be provided as a non-transitory storage medium. Here, the term "non-transitory storage medium" refers to a tangible device and does not include a signal (e.g., an electromagnetic wave), but this term does not distinguish whether data is stored semi-permanently or temporarily in the storage medium. For example, the "non-transitory storage medium" may include a buffer that temporarily stores data.

[0098] According to an embodiment, a method according to various disclosed embodiments of the present disclosure may be provided by being included in a computer program product. The computer program product may be traded as a commodity between a seller and a buyer. The computer program product may be distributed in the form of a machine-readable storage medium (e.g., a compact disc read-only memory (CD-ROM)), or may be distributed online (e.g., downloaded or uploaded) via an application store (e.g., Play Store™), or directly between two user devices (e.g., smartphones). When distributed online, at least a portion of the computer program product (e.g., a downloadable application) may be temporarily generated or at least temporarily stored in a machine-readable storage medium, such as the memory of a manufacturer's server, an application store's server, or an intermediary server.

[0099] Although one or more embodiments of the present disclosure have been described with reference to the drawings, it will be understood by those skilled in the art that various changes in form and detail can be made therein without departing from the spirit and scope as defined by the following claims.

Claims

1. An open radio access network (O-RAN), comprising: an O-RAN Radio Unit (O-RU) configured to transmit radio signals to user equipment; an O-RAN Distributed Unit (O-DU) configured to perform baseband processing; a fronthaul network, wherein the O-RU and the O-DU are nodes of the fronthaul network, and the O-RU and the O-DU are configured to communicate via the fronthaul network; the O-DU is configured to transmit a one-way delay measurement message to the O-RU of the fronthaul network, the one-way delay measurement message including a value based on a hardware timestamp inserted immediately before transmission of the one-way delay measurement message; The O-RAN is configured such that the O-RU transmits a response to the one-way delay measurement message to the O-DU, the response including a second value based on a second hardware timestamp generated when the O-RU receives the one-way delay measurement message from the fronthaul network.

2. The O-RAN of claim 1 , wherein the one-way delay measurement message comprises a packet, the packet comprising a correction value field, the correction value field storing the value.

3. The O-RAN of claim 2 , wherein the response includes a second packet, the second packet includes a second correction value field, and the second correction value field stores the second value.

4. 4. The O-RAN of claim 3, wherein the O-DU determines a delay based at least in part on the value of the correction value field of the packet and the second value of the second correction value field of the second packet.

5. the O-DU comprises a network interface card (NIC) that interfaces the O-DU with the fronthaul network, the NIC generating the hardware timestamp; The O-RAN of claim 1 , wherein the O-RU comprises a second NIC that interfaces the O-RU with the fronthaul network, the second NIC generating the second hardware timestamp.

6. 1. A method for one-way delay measurement, comprising: generating a one-way delay measurement message containing the packet in an open radio access network (O-RAN) distribution unit (O-DU); inserting a timestamp into an application layer of the packet; inserting a hardware timestamp into a transport layer of the packet; transmitting the one-way delay measurement message from the O-DU to an O-RAN Radio Unit (O-RU) via a fronthaul network immediately after inserting the hardware timestamp; inserting a second hardware timestamp into the packet immediately after the O-RU receives the one-way delay measurement message; generating, by the O-RU, a response message to the one-way delay measurement message, the response message including a second packet; the O-RU inserting a second timestamp and value into the second packet, the value being the difference between the second timestamp and the second hardware timestamp; transmitting the response message from the O-RU to the O-DU via the fronthaul network.

7. The method of claim 6 , further comprising determining a delay based at least in part on the timestamp, the hardware timestamp, the second timestamp, and the value.

8. 7. The method of claim 6, further comprising inserting a second value into the packet with the O-DU, the second value being the difference between the hardware timestamp and the timestamp.

9. Inserting the hardware timestamp includes inserting the hardware timestamp by a network interface card (NIC) that interfaces the O-DU with the fronthaul network; and 7. The method of claim 6, wherein inserting the second hardware timestamp comprises inserting the second hardware timestamp by a second NIC that interfaces the O-RU with the fronthaul network.

10. 1. A communication system comprising: A node, Generate a message containing the packet, inserting a timestamp into an application layer of said packet; Inserting a hardware timestamp into the transport layer of the packet; a node configured to transmit the message to a second node over a network immediately after inserting the hardware timestamp; the second node, receiving the message from the node via the network; inserting a second hardware timestamp at the transport layer of the packet immediately after receiving the message; generating a response including the second packet; inserting a second timestamp and a value of the second packet, where the value is the difference between the second timestamp and the second hardware timestamp; A communication system including a second node configured to transmit the response to the node over the network.

11. The node 11. The communication system of claim 10, further configured to: insert a second value into the application layer offset field of the packet, the second value being the difference between the hardware timestamp and the timestamp.

12. The communication system of claim 10, wherein the node comprises an Open Radio Access Network (O-RAN) Distribution Unit (O-DU).

13. The communication system of claim 12 , wherein the second node comprises an O-RAN Radio Unit (O-RU).

14. The communication system of claim 13 , wherein the network comprises a fronthaul network.

15. The communication system of claim 10 , wherein the second node is configured to insert the value into a correction value field of the second packet.

16. 16. The communication system of claim 15, wherein the second node inserts the second timestamp in an application layer of the second packet and the value in the correction value field of the application layer of the second packet.

17. the node receives the response from the second node via the network; 17. The communication system of claim 16, further configured to determine a delay based at least in part on the second timestamp, the value of the offset value field of the second packet, the hardware timestamp, and the timestamp.

18. The communication system of claim 10 , wherein the node comprises a network interface card (NIC) configured to generate the hardware timestamp.

19. 20. The communication system of claim 18, wherein the second node comprises a second NIC configured to generate the second hardware timestamp.

20. The communication system of claim 10 , wherein the message comprises a one-way delay measurement message.

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