Master unit, slave unit and methods for handling synchronization communication

Abstract

Embodiments herein relate to, e.g., a method performed by a master unit (12) for handling communication in a communication network. The Master unit (12) transmits to a slave unit (13), a first PTP indication comprising a first time stamp of a first internal clock of the master unit; and receives from the slave unit (13), a second PTP indication comprising a second time stamp of a second internal clock of the slave unit (13). The master unit (12) estimates a time error indication between the first and second internal clocks based on the first and second PTP indications.

Description

[0001] MASTER UNIT, SLAVE UNIT AND METHODS FOR HANDLING SYNCHRONIZATION COMMUNICATION

[0002] TECHNICAL FIELD

[0003] Embodiments herein relate to a master unit, a slave unit, and methods performed therein regarding wireless communication. Furthermore, a computer program product and a computer readable storage medium are also provided herein. In particular, embodiments herein relate to handling communication, such as synchronization, in a communication network.

[0004] BACKGROUND

[0005] In a typical communication network, user equipments (UE), also known as wireless communication devices, mobile stations, stations (ST A) and / or wireless devices, communicate via a Radio Access Network (RAN) with one or more core networks (CN). The RAN covers a geographical area which is divided into service areas or cells, with each service area or cell being served by a radio network node such as an access node e.g. a Wi-Fi access point (AP) or a radio base station (RBS), which in some networks may also be called, for example, a NodeB, a gNodeB, or an eNodeB. The service area or cell is a geographical area where radio coverage is provided by the radio network node. The radio network node operates on radio frequencies to communicate over an air interface with the UEs within range of the radio network node. The radio network node communicates over a downlink (DL) to the UE and the UE communicates over an uplink (UL) to the radio network node.

[0006] A Universal Mobile Telecommunications System (UMTS) is a third generation (3G) telecommunication network, which evolved from the second generation (2G) Global System for Mobile Communications (GSM). The UMTS terrestrial radio access network (UTRAN) is essentially a RAN using wideband code division multiple access (WCDMA) and / or High-Speed Packet Access (HSPA) for communication with user equipment. In a forum known as the Third Generation Partnership Project (3GPP), telecommunications suppliers propose and agree upon standards for present and future generation networks and investigate e.g. enhanced data rate and radio capacity. In some RANs, e.g. as in UMTS, several radio network nodes may be connected, e.g., by landlines or microwave, to a controller node, such as a radio network controller (RNC) or a base station controller (BSC), which supervises and coordinates various activities of the plural radio network nodes connected thereto. The RNCs are typically connected to one or more core networks.

[0007] Specifications for the Evolved Packet System (EPS) have been completed within the 3GPP and coming 3GPP releases, such as New Radio (NR), are worked on. The EPS comprises the Evolved Universal Terrestrial Radio Access Network (E-UTRAN), also known as the Long-TermEvolution (LTE) radio access network, and the Evolved Packet Core (EPC), also known as System Architecture Evolution (SAE) core network. E-UTRAN / LTE is a 3GPP radio access technology wherein the radio network nodes are directly connected to the EPC core network. As such, the Radio Access Network (RAN) of an EPS has an architecture comprising radio network nodes connected directly to one or more core networks.

[0008] With the emerging 5G technologies such as NR, the use of very many transmit- and receive-antenna elements may be of great interest as it makes it possible to utilize beamforming, such as transmit-side and receive-side beamforming. Transmit-side beamforming means that the transmitter can amplify the transmitted signals in a selected direction or directions, while suppressing the transmitted signals in other directions. Similarly, on the receive-side, a receiver can amplify signals from a selected direction or directions, while suppressing unwanted signals from other directions. NR is connected to the 5G Core Network (5GC) which comprises a number of Network Functions (NF) such as Session Management Function (SMF), Access Management Function (AMF), Authentication Service Function (AUSF), Policy Control Function (PCF), Unified Data Manager (UDM), Network Repository Function (NRF), Network Exposure Function (NEF), just to mention some. In the 5GC, NFs can discover other NFs by using a discovery service provided by the NRF.

[0009] This disclosure lies in the field of telecommunications, specifically clock synchronization in network infrastructure. The Precision Time Protocol (PTP), as defined in IEEE1588 standard, is widely implemented for clock synchronization in networks, requiring nano second accuracy in many applications. In conventional setups, third-party devices are commonly used to test the synchronization functionality of network devices like Basebands or Radios. However, these solutions are typically limited to laboratory environments due to their high cost, complexity, and lack of scalability, making them unsuitable for live production environments or automated testing.

[0010] Industry trends show an increasing demand for precise time synchronization in various applications, including 5G networks, smart grids, and so on. Publications such as 'Timing Challenges in the Smart Grid' by Jason Allnutt et al NIST Special Publication 1500-08 highlight the critical need for nanosecond-level synchronization in modern power systems. Similarly, Network Time Synchronization: the Network Time Protocol on Earth and in Space, Second Edition, Mills, David L. Computer Network Time Synchronization: the Network Time Protocol on Earth and in Space, Second Edition, CRC Press 2011, 466 pp, ISBN 978-1-4398-1463-5 discusses the broader implications of precise timing in network operations.

[0011] Despite these advancements and recognized needs, current literature and standards do not adequately address the challenges of testing clock synchronization in live production environments or discuss the integration of testing functionality within the network devices themselves. This gap in existing solutions presents a significant challenge for network operators and equipmentmanufacturers, particularly as networks become more complex and demanding in terms of timing precision.

[0012] In traditional RAN, the Baseband Unit (BBU) or distributed unit (DU) in 5G RAN functions as a master clock, providing a timing reference to downstream Radio Units (RU) which act as slave clocks. Upon successful synchronization of the slave clock to the master, the BBU receives a notification message from the RU indicating synchronization. However, this setup lacks the capability to quantify the quality of synchronization or determine if the time error meets specified requirements, leaving both master and slave unaware of the actual synchronization performance.

[0013] Fig. 1a illustrates this basic setup between a DU and an RU.

[0014] SUMMARY

[0015] As part of developing embodiments herein one or more issues have been identified. To evaluate clock synchronization performance through time error measurement, conventional methods necessitate the introduction of third-party testing equipment. In this configuration, the testing device replaces the BBU, utilizing one link to provide a time reference and another to receive timing information, such as PTP messages, from a Device Under Test (DUT). The testing equipment then calculates the time error between the DUT and itself by comparing the received timing information against its internal clock. However, this setup, lacking BBU participation, is confined to laboratory environments. Fig. 1b depicts this conventional testing arrangement.

[0016] In existing methodologies for clock synchronization testing in telecommunications networks, particularly in RAN, face several critical practical challenges that are prevalent throughout the telecommunications industry:

[0017] Limited Environmental Flexibility: Traditional testing methods typically rely on third-party equipment designed for laboratory environments but ill-suited for deployment in live production networks. This limitation severely constrains the ability to conduct real-time testing and monitoring of clock synchronization under actual network conditions. Consequently, network operators face an increased risk of undetected synchronization issues, potentially leading to service quality degradation or interruptions, which in turn adversely affect user experience and company revenue.

[0018] Automation Difficulties: The setup of third-party testing devices often involves complex manual configurations, presenting significant challenges in integration with equipment manufacturers' automated testing processes. This substantially limits the potential for test automation, thereby impacting the efficiency of continuous integration and product development cycles. While automated testing in other areas of network management has shown to significantly reduce testing time and improve accuracy, these benefits are not yet fully realized in clock synchronization testing.

[0019] Space and Connectivity Constraints: Deploying third-party devices in live environments necessitates additional physical space and dedicated ports on the devices under test. In productionenvironments, both space and port resources are at a premium, posing a significant challenge. For instance, on some small radio devices with only two ports, if these are completely occupied by third-party testing equipment, it becomes impossible to connect baseband devices for testing real traffic. This limitation not only increases deployment costs but may also affect overall network performance and scalability.

[0020] Cost Implications: The introduction of third-party testing equipment not only escalates research and development costs in laboratory environments but also substantially limits the feasibility of deployment in actual production networks. This cost factor presents a significant barrier to comprehensive and continuous synchronization testing across the network infrastructure.

[0021] These challenges highlight the urgent need for a more integrated, flexible, and cost-effective approach to clock synchronization testing in telecommunications networks. The industry requires a solution that can provide accurate, real-time synchronization testing capabilities without the limitations imposed by current third-party testing methodologies. Such a solution would need to address the issues of environmental adaptability, automation integration, resource efficiency, and / or cost-effectiveness, while maintaining or improving the accuracy and reliability of synchronization testing.

[0022] An object of embodiments herein is to handle communication, such as monitoring synchronization, in a communication network in an efficient manner.

[0023] According to an aspect the object is achieved, according to some embodiments herein, by providing a method performed by a master unit for handling communication in a communication network. The master unit transmits to a slave unit, a first PTP indication comprising a first time stamp of a first internal clock of the master unit. The master unit receives from the slave unit, a second PTP indication comprising a second time stamp of a second internal clock of the slave unit; and estimates a time error indication between the first and second internal clocks based on the first and second PTP indications.

[0024] According to another aspect the object is achieved, according to some embodiments herein, by providing a method performed by a slave unit for handling communication in a communication network. The slave unit receives from a master unit, a first PTP indication comprising a first time stamp of a first internal clock of the master unit. The slave unit transmits to the master unit, a second PTP indication comprising a second time stamp of a second internal clock of the slave unit using a second connection to the master unit to transmit the second PTP indication, wherein the second connection is set up between a second port at the master unit and a second port of the slave unit and wherein the second port at the master unit is set to an uncalibrated state.

[0025] It is furthermore provided herein a computer program product comprising instructions, which, when executed on at least one processor, cause the at least one processor to carry out the methods herein, as performed by the master unit, and the slave unit, respectively. It is additionallyprovided herein a computer-readable storage medium, having stored thereon a computer program product comprising instructions which, when executed on at least one processor, cause the at least one processor to carry out the method according to the methods herein, as performed by the master unit, and the slave unit, respectively.

[0026] According to yet another aspect the object is achieved, according to some embodiments herein, by providing the master unit, and the slave unit configured to perform the methods herein, respectively.

[0027] Thus, according to an aspect the object is achieved, according to some embodiments herein, by providing a master unit for handling communication in a communication network. The master unit is configured to transmit to a slave unit, a first PTP indication comprising a first time stamp of a first internal clock of the master unit. The master unit is configured to receive from the slave unit, a second PTP indication comprising a second time stamp of a second internal clock of the slave unit; and to estimate a time error indication between the first and second internal clocks based on the first and second PTP indications.

[0028] According to another aspect the object is achieved, according to some embodiments herein, by providing a slave unit for handling communication in a communication network. The slave unit is configured to receive from a master unit, a first PTP indication comprising a first time stamp of a first internal clock of the master unit. The slave unit is configured to transmit to the master unit or another slave unit, a second PTP indication comprising a second time stamp of a second internal clock of the slave unit using a second connection to the master unit or the other slave unit, to transmit the second PTP indication, wherein the second connection is set up between a second port at the master unit and a second port of the slave unit and wherein the second port at the master unit is set to an uncalibrated state.

[0029] Embodiments herein concern the integration of a clock performance testing functionality for downstream devices, i.e., the slave unit such as a Rll, as a module within a Distributed Unit (DU) software system, which DU, being an example of the mater unit, also serves as the clock reference provider in a PTP domain. The key challenge addressed is how to effectively utilize existing hardware and software resources of the master unit to enable monitoring of the synchronization performance of slave units without altering existing synchronization functions and testing processes.

[0030] Furthermore, embodiments herein may offer one or more significant advantages over existing methods such as:

[0031] 1. Enhanced deployability in production environments: As no additional testing equipment is required, it is more conducive to provide results closer to real-world environments compared to laboratory testing. This approach better captures real-world network dynamics, including varying traffic loads and environmental factors, thereby significantlyimproving overall network reliability. Furthermore, it enables continuous, non-intrusive testing, potentially detecting issues that might be missed in laboratory testing.

[0032] 2. Streamlined and efficient testing process: Being integrated into the company's network equipment, it supports proprietary automated testing protocols. Compared to manual methods, this can significantly reduce testing time.

[0033] 3. Significant cost and resource optimization: It reduces the need for external testing equipment and saves valuable physical space in the testing environment. This is particularly crucial in space-constrained scenarios such as small cell deployments or edge computing nodes.

[0034] 4. Enhanced deployment flexibility and scalability: The integrated testing functionality can be deployed in any environment utilizing enhanced common public radio interface (eCPRI)- supported baseband units, ensuring broad compatibility across various network infrastructures. It also facilitates smoother upgrades and transitions to emerging network technologies, for example, from 5G to 6G architectures, or bandwidth upgrades from 10Gb to 100Gb.

[0035] 5. Long-term strategic benefits: As the testing functionality is integrated as a module in existing equipment, the solution may be inherently designed for future compatibility, particularly for deployment in Open-RAN and Cloud-RAN network architectures. This facilitates cloud-based real-time detection capabilities. Moreover, it lays a solid foundation for artificial intelligence (Al)-driven network optimization by generating continuous, high- quality synchronization data.

[0036] Compared to traditional external testing methods, this integrated approach offers a more scalable, cost-effective, and operationally efficient solution for clock synchronization testing. By addressing one or more of the key pain points in current network testing practices, embodiments herein provide a value-added product in the telecommunications sector, particularly in the critical area of network infrastructure timing synchronization. Its ability to provide more accurate, frequent, and / or cost-effective testing may significantly contribute to an overall reliability and performance of modern and future telecommunication networks. Hence, embodiments herein handle communication, such as monitoring synchronization, in a communication network in an efficient manner.

[0037] BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Embodiments will now be described in more detail in relation to the enclosed drawings, in which:

[0039] Fig. 1a is a schematic overview depicting a basic setup for Baseband Unit and Radio Unit according to prior art;

[0040] Fig. 1 b shows a time error test with 3rd party test device according to prior art;Fig. 2 shows an overview depicting a communication network according to embodiments herein;

[0041] Fig. 3 shows a combined flowchart and signalling scheme according to some embodiments herein;

[0042] Fig. 4 shows a schematic flowchart depicting a method performed by a master unit according to embodiments herein;

[0043] Fig. 5 shows a schematic flowchart depicting a method performed by a slave unit according to some embodiments herein;

[0044] Fig. 6 shows a schematic overview time error test with BBU according to some embodiments herein;

[0045] Fig. 7 shows how a port state may shift to UNCALIBRATED according to some embodiments herein;

[0046] Fig. 8 shows a PTP Message Exchange and Timestamp Flow according to some embodiments herein;

[0047] Fig. 9 shows a timestamp processing in linuxptp;

[0048] Fig. 10 illustrates the architecture of the TCP server implementation;

[0049] Fig. 11 illustrates the experimental configuration for a verification process;

[0050] Fig. 12 shows comparative analysis of the 2-way time error and the 1PPS time error;

[0051] Fig. 13 shows comparative analysis of the 2-way time error and the 1PPS time error;

[0052] Fig. 14 illustrates the experimental setup for both the master unit 12 and the industrystandard testing equipment connections;

[0053] Fig. 15 presents a comparative analysis of the 2-way time error measurements obtained from embodiments herein and the industry-standard testing equipment system;

[0054] Fig. 16 is a block diagram depicting a master unit according to embodiments herein; and Fig. 17 is a block diagram depicting a slave unit according to embodiments herein;

[0055] DETAILED DESCRIPTION

[0056] Embodiments herein relate to communication networks in general. Fig. 2 is a schematic overview depicting a communication network 1. The communication network 1 comprises one or more RANs and one or more CNs. The communication network 1 may use one or a number of different technologies. Embodiments herein relate to recent technology trends that are of particular interest in a NR context, however, embodiments are also applicable in existing wireless communications systems such as e.g. LTE or WCDMA, and developments thereof.

[0057] In the communication network 1, a UE 10, exemplified herein as a wireless device such as a mobile station, a non-access point (non-AP) station (STA), a STA and / or a wireless terminal, is comprised communicating via, e.g., one or more Access Networks (AN), e.g. RAN, to one or more CN. It should be understood by the skilled in the art that “UE” is a non-limiting term which meansany terminal, wireless communications terminal, user equipment, NarrowBand Internet of Things (NB-IoT) device, Machine Type Communication (MTC) device, Device to Device (D2D) terminal, or node e.g. smart phone, laptop, mobile phone, sensor, relay, mobile tablets or even a small base station capable of communicating using radio communication with a radio network node within an area served by the radio network node.

[0058] The communication network 1 comprises a radio network node providing radio coverage over a geographical area, a first service area 11 or first cell of a first Radio Access Technology (RAT), such as 6G, NR, LTE, or similar. The radio network node may be a transmission and reception point such as an access node, an access controller, a base station, e.g. a radio base station such as a gNodeB (gNB), an evolved Node B (eNB, eNode B), a NodeB, a base transceiver station, a radio remote unit, an Access Point Base Station, a base station router, a Wireless Local Area Network (WLAN) access point or an Access Point Station (AP STA), a transmission arrangement of a radio base station, a stand-alone access point or any other network unit or node capable of communicating with a wireless device within the area served by the radio network node depending e.g. on the first radio access technology and terminology used. The radio network node comprises a master unit 12 such as a BBU, a DU or similar, and a slave unit 13 such as a RU or a remote RU or similar.

[0059] It should be noted that a service area may be denoted as cell, beam, beam group or similar to define an area of radio coverage.

[0060] The proposed embodiments herein integrate PTP-based clock synchronization testing functionality directly into the master unit 12 such as DU in RAN. Embodiments herein distinguish themselves from existing methodologies by eliminating the need for external third-party testing equipment. Instead, it not only provides the master clock to downstream slave units 13 such as RUs but may also simultaneously measure the time difference between the RU (functioning as a slave device 13) and the DU (master unit 12), enabling evaluation of clock synchronization performance.

[0061] Embodiments herein are designed for deployment within RANs, specifically in networks utilizing eCPRI connections and PTP for clock synchronization functionality. In a typical RAN configuration, the master unit 12, such as BBU or Distributed Unit (DU), serves as the clock reference provider for the slave unit 13, such as a RU.

[0062] Thus, embodiments herein integrate a clock synchronization performance testing functionality, e.g., such as a Characteristic Requirement Specification (CRS), into the master unit 12, such as a clock reference provider. This approach fundamentally differs from current methods by obviating the need for external third-party testing devices. The master unit 12 maintains its primary function of providing the master clock to downstream slave units while concurrently assessing the time difference between the slave unit 13 and the master unit 12, enabling real-time evaluation of clock synchronization performance.Deployment Context: Embodiments herein may be implemented in a standard RAN network where DU, being the master unit 12, and RU, being the slave unit 13, are connected via eCPRI and utilize PTP for clock synchronization. The master unit 12 acts as the master clock providing time reference, while slave unit 13 functions as the slave clock.

[0063] One or more of the function aspects:

[0064] 1. Dual-Role PTP Implementation: The master unit 12 may simultaneously function as both a master (providing time reference to slave units) and a slave (verifying and monitoring slave clock synchronization performance) towards the same device within the same PTP network. This dual functionality deviates significantly from traditional single-role implementations, enabling comprehensive synchronization management without additional external equipment.

[0065] 2. Integrated Time Difference Calculation: The master unit 12 may receive and analyze complete PTP messages from the slave unit 13, including embedded timestamps and calculate time difference between master and slave, providing real-time, high-precision synchronization accuracy measurements.

[0066] 3. Non-lntrusive Testing Methodology: Utilizes an additional link between the master unit 12 and the slave unit 13 fortesting purposes. Enables synchronization testing and monitoring in live network environments without disrupting the normal master-slave relationship.

[0067] 4. Software Integration and Resource Optimization: Leverages existing software and hardware resources in the master unit 12 and / or the slave unit 13 to achieve enhanced functionality without significant additional hardware requirements or system modifications. Embodiments herein may be designed to be compatible with existing PTP standards. Meanwhile represents an advancement in clock synchronization testing for telecommunications networks, particularly in RANs. By integrating testing capabilities directly into the master unit 12, it offers a more efficient, flexible, and cost-effective approach to ensure network synchronization quality, addressing key challenges in current testing methodologies.

[0068] Fig. 3 shows a combined signaling scheme and flowchart according to some embodiments herein.

[0069] Action 301. The master unit 12 may transit a port to a state, such as port B to uncalibrated state. In accordance with the PTP protocol specifications, when a port enters the uncalibrated state, it prompts the corresponding port on the connected device such as slave unit 13 to assume the role of a master port. This may be performed for setting up an additional link between the master unit 12 and the slave unit 13 for testing purposes.

[0070] Action 302. The master unit 12 may announce (inform) the slave unit 13 of the state of one or more ports. The state may be indicated in an announce message.Action 303. The master unit 12 transmits to the slave unit 13, the first PTP indication comprising the first time stamp of the first internal clock of the master unit 12. This may be sent over a first connection between a first port at the master unit 12 and a first port at the slave unit 13. The first PTP indication may comprise a time stamp value, a real value, an index value, a relative value or similar. The first PTP indication may be transmitted over an eCPRI connection.

[0071] Action 304. The slave unit 13 may transmit to the master unit 12, the second PTP indication comprising the second time stamp of the second internal clock of the slave unit 13. This may be sent over a second connection between a second port at the slave unit 13 and a second port at the master unit 12, see action 301. The second PTP indication may comprise a time stamp value, a real value, an index value, a relative value or similar. The second PTP indication may be transmitted over an additional eCPRI connection. The first and / or second PTP indication may be received / transmitted in a synchronization message, a follow-up message, a delay request and / or a delay response message.

[0072] Action 305. The master unit 12 estimates the time error indication between the first and second internal clocks based on the first and second PTP indications.

[0073] The method actions performed by the master unit 12 for handling communication in the communication network 1 according to embodiments will now be described with reference to a flowchart depicted in Fig. 4. The actions do not have to be taken in the order stated below but may be taken in any suitable order. Dashed boxes indicate optional features.

[0074] Action 401. The master unit 12 may setup the second connection to the slave unit 13 to receive the second PTP indication, wherein the second connection is set-up between a second port at the master unit and a second port of the slave unit and wherein the second port at the master unit is set to an uncalibrated state. The first connection may be setup between a first port at the master unit 12and a first port at the slave unit 13.

[0075] Action 402. The master unit 12 transmits to the slave unit 13, the first PTP indication comprising the first time stamp of the first internal clock of the master unit 12. This may be transmitted over the first connection.

[0076] Action 403. The master unit 12 receives from the slave unit 13, the second PTP indication comprising the second time stamp of the second internal clock of the slave unit 13. The master unit may be a BBU and the slave unit may be a Rll that are connected via an eCPRI connection and utilize PTP for clock synchronization. The second PTP indication may be received over an additional eCPRI, being an example of the second connection, between the master unit 12 and the slave unit 13 for testing purposes.

[0077] Action 404. The master unit 12 estimates the time error indication between the first and second internal clocks based on the first and second PTP indications.

[0078] Action 405. The master unit 12 mayuse this time error indication to monitor the synchronization performance of the slave unit 13.

[0079] The method actions performed by the slave unit 13 for handling communication in the communication network 1 according to some embodiments will now be described with reference to a flowchart depicted in Fig. 5. The actions do not have to be taken in the order stated below but may be taken in any suitable order. Dashed boxes indicate optional features.

[0080] Action 501. The slave unit 13 may setup the second connection to the master unit 12 to transmit the second PTP indication, wherein the second connection is set-up between the second port at the master unit 12 and the second port of the slave unit 13 and wherein the second port at the master unit 12 is set to an uncalibrated state. The first connection may be setup between the first port at the slave unit 13 and the first port at the master unit 12.

[0081] Action 502. The slave unit 13 receives from the master unit 12 or another slave unit, the first PTP indication comprising the first time stamp of the first internal clock of the master unit 12.

[0082] Action 503. The slave unit 13 may apply one or more (second) time stamps upon reception of the first PTP indication and / or transmission of the second PTP indication.

[0083] Action 504. The slave unit 13 transmits to the master unit 12 or the other slave unit, the second PTP indication comprising the second time stamp of the second internal clock of the slave unit using the second connection to the master unit 12 to transmit the second PTP indication, wherein the second connection is set up between the second port at the master unit 12 and the second port of the slave unit 13 and wherein the second port at the master unit 12 is set to the uncalibrated state.

[0084] Embodiments herein improve capabilities of the master unit 12. The proposed solution enables the master unit 12 to not only provide time reference in real-world environments but also simultaneously measure or estimate the time error between the first and the second internal clocks. This enables a real-time monitoring of the slave unit's synchronization performance. Fig. 6 illustrates the improved setup incorporating this approach.

[0085] Thus, embodiments herein offer a significant improvement over existing methods by integrating testing capabilities directly into the master unit 12, eliminating the need for separate testing equipment and enabling synchronization performance evaluation in live network environments.

[0086] In Fig. 6 master unit 12 is represented by a DU, which is connected to slave unit 13, represented by any form of RU. The DU may provide baseband functionality to the RU while simultaneously serving as its time reference. In this configuration, the DU acts as the master clock for the RU, while the RU functions as the slave clock to the DU.Connectivity: The DU and RU may be interconnected via two eCPRI connections: 1. Link 1: A standard connection between DU.portA and RU.portl, facilitating all standard RAN functionalities between the DU and RU.

[0087] 2. Link 2: An additional connection between DU.portB and RU.port2, specifically implemented for measuring the time error between RU and DU.

[0088] To enable time error testing via Link 2, three key modifications to the existing system may be implemented:

[0089] 1. Role Reversal: Maintaining the master-slave relationship between DU and RU in the RAN network while simultaneously inverting the roles of DU.portB and RU.port2, enabling RU.port2 to function as a master port, transmitting timestamp information to DU.portB. 2. Time Error Calculation: Implementing a mechanism within DU to calculate the time error between DU and RU based on the timestamps received from RU.

[0090] 3. Client-side Retrieval: Developing a method to retrieve the calculated time error from the client, thereby completing the testing process.

[0091] Detailed descriptions of these three modifications will be provided in subsequent sections. It is noteworthy that the design and development process extensively leveraged the PTP stack — specifically Linuxptp — implemented in the BBU and RU system. Linuxptp, an open-source project, may be used in a clock synchronization functionality. It executes the Best Master Clock Algorithm (BMCA) to determine the master and slave within a PTP domain while simultaneously providing PTP message timestamps to upper-layer applications.

[0092] Embodiments herein may use this existing infrastructure, introducing one or more modifications to enable simultaneous master and slave functionality within the master unit 12, thereby facilitating real-time synchronization performance monitoring in live network environments.

[0093] Embodiments herein may designate a port on the master unit 12 as a slave port.

[0094] The primary challenge in implementing the aforementioned functionality is to maintain the roles of the master unit 12 and the slave unit 13 within the PTP domain while simultaneously designating an additional port on the master unit 12 as a slave port to the slave unit 13. This configuration is not feasible in current systems due to PTP protocol constraints, which dictate that if master unit 12 acts as the master to slave unit 13, all ports on the master unit 12 function as master ports to slave unit 13. The Linuxptp implementation adheres to this principle. Therefore, embodiments herein may modify this limitation.

[0095] Embodiments herein may, for example, modify the application of the BMCA in PTP. The BMCA is utilized for selecting a Grandmaster (GM) in a PTP domain. Each PTP clock cyclically executes this algorithm to determine the clock with the highest precision. The clock identified as having the best precision is designated as the grandmaster and serves as the synchronization source for all other PTP clocks in the network.In accordance with IEEE 1588-2008, the BMCA employs a hierarchical selection algorithm based on the following ordered properties:

[0096] 1. Priority 1: User-assignable specific static-designed priority to each clock, preemptively defining a priority among them. Lower numerical values indicate higher priority.

[0097] 2. Class: Each clock belongs to a given class, with each class assigned its own priority. 3. Accuracy: Precision between clock and Coordinated Universal Time (UTC), measured in nanoseconds (ns).

[0098] 4. Variance: Variability of the clock.

[0099] 5. Priority 2: Final-defined priority, establishing a backup order in case one or more other criteria prove insufficient. Lower numerical values indicate higher priority.

[0100] 6. Unique identifier: Medium access control (MAC) address-based selection serves as a tiebreaker when all other properties are equal.

[0101] The Linuxptp implementation incorporates modules to execute the BMCA protocol through finite state machines (fsm). Specifically, two types of finite state machines are utilized: master_fsm and slave_fsm. Embodiments here may be based on modifications to the slave_fsm, which is specifically designed for slave clocks within a PTP domain. Consequently, it lacks master states, resulting in a simpler state configuration.

[0102] The various port states are described as follows:

[0103] • PS_INITIALIZING: Initial startup phase, setting up internal data structures.

[0104] • PS_FAULTY: Fault condition detected, rendering the port inoperable.

[0105] • PS_DISABLED: Administratively disabled state.

[0106] • PS_LISTENING: Actively listening to PTP messages, determining role in synchronization topology.

[0107] • PS_PASSIVE: Standby state, neither master nor slave.

[0108] • PS_UNCALIBRATED: Selected a master clock, but not yet achieved stable synchronization.

[0109] • PS_SLAVE: Fully operational as a slave clock, actively synchronizing to the selected master clock.

[0110] Typically, upon reaching a stable state, ports on master clocks are in the PS_MASTER state, while ports on slave clocks are in either PS_SLAVE or PS_PASSIVE states.

[0111] The original slave finite state machine (FSM) lacks the capability to designate a specific port on a master clock as a slave port when connected to the same slave clock. This limitation is inherent to the characteristics of the PTP. According to the PTP protocol, ports have only a few low priorities compared to the overall PTP priority of the device. In most cases, a port's priority is inherited from the PTP node it belongs to.

[0112] Consequently, when two units determine their master and slave roles through the BMCA, as illustrated in Fig. 6 where the DU is the master and RU is the slave, all ports on A are typicallydesignated as Master ports relative to RU, while all ports on the slave unit 13 become slave ports when connected to master unit 12. This is because, within a PTP domain, a single node cannot simultaneously function as both master and slave to another specific node.

[0113] However, for the master unit 12 to measure the time error between itself and the slave unit 13, it must receive PTP messages containing timestamp information from the slave unit 13. The most straightforward method for the master unit 12 to receive these PTP messages with timestamp is to designate a specific port on the master unit 12 as a slave port relative to the slave unit 13, while slave unit 13 acts as a master for this particular connection. This may require modifications to the slave_fsm.

[0114] The slave_fsm may be modified to allow such a configuration. Specifically, a new attribute, 'test_port', may be introduced to the port structure in Linuxptp. This attribute serves as a flag to indicate whether a given port is designated as a test port. The modification in the code is as below:

[0115] struct port {

[0116] LIST_ENTRY(port) list;

[0117] const char ‘name;

[0118] unsigned int entity_id;

[0119] struct interface *iface;

[0120] / / ...

[0121] / * a flag to describe if the port is configured as test port * /

[0122] int test_port;

[0123] };

[0124] Implementation Details of the Test Port Functionality:

[0125] Embodiments herein may involve one or more of the following:

[0126] 1. Initialization of Test Port Attribute: A 'test_port' attribute in the 'struct port' is initialized to 0 by default. This default value signifies that the port is a standard port within a PTP domain, inheriting its priority and BMCA protocol behavior from its associated clock node.

[0127] 2. Test Port Activation: When a test engineer sets the 'test_port' attribute to 1, it triggers a specific sequence of state transitions for the port.

[0128] 3. State Transition Sequence: Upon activation, the port undergoes a controlled state transition from PS_INITIALIZING to PS_UNCALIBRATED. This transition sequence is crucial for establishing the desired testing configuration.

[0129] 4. PTP Protocol Behavior: In accordance with the PTP protocol specifications, when a port enters the PS_UNCALIBRATED state, it prompts the corresponding port on the connected device (slave unit 13) to assume the role of a master port.5. Timestamp Exchange: Following this state transition, the slave unit 13 begins to continuously transmit its internal clock information to the designated port on the master unit 12. This information is encapsulated within PTP messages in the form of timestamps. 6. Time Error Calculation: The master unit 12 processes the incoming PTP messages from the slave unit 13, extracting the timestamp information. By analyzing these timestamps, the master unit 12 may determine the precise time at the slave unit 13.

[0130] 7. Comparative Analysis: The master unit 12 then compares the derived time of the slave unit 13 with its own internal clock, enabling the calculation of the time difference between the master unit 12 and the slave unit 13.

[0131] Fig. 7 describes how a port state may shift to UNCALIBRATED with test_port.

[0132] Referring to Fig. 6, the system behavior both in its initial default state and after the implementation of the proposed modification may be explained.

[0133] Initial Default State: In the initial configuration, a 'test_port' attribute for both DU.portA, also referred to as A.portA, and DU.portB, also referred to as A.portB, is set to 0. RU.portl may be referred to as B.portl, and RU.port2 may be referred to as B.port2. Under these conditions, the system behavior is as follows:

[0134] 1. Node A (Master Unit):

[0135] o A.portA: Port State = MASTER

[0136] o A.portB: Port State = MASTER

[0137] 2. Node B (Slave Unit):

[0138] o B.portl: Port State = SLAVE

[0139] o B.port2: Port State = PASSIVE

[0140] This initial state aligns with the standard PTP protocol behavior, where all ports on the master unit 12 maintain a MASTER state, while the slave device's ports are in either SLAVE or PASSIVE states.

[0141] Modified State (Test Port Activated): When the 'test_port' attribute is set to 1 for a specific port on the master unit 12, e.g., A.portB, the system behavior changes as follows:

[0142] 1. Node A (Master unit 12):

[0143] o A.portA: Port State = MASTER (unchanged)

[0144] o A.portB: Port State = UNCALIBRATED

[0145] 2. Node B (Slave unit 13):

[0146] o B.portl: Port State = SLAVE (unchanged)

[0147] o B.port2: Port State = MASTER

[0148] It should be noted:

[0149] 1. The activation of the test port (A.portB) triggers a state change from MASTER to UNCALIBRATED on the master unit 12.2. Correspondingly, the connected port on slave unit 13 (B.port2) transitions from a PASSIVE (or SLAVE) to a MASTER state.

[0150] 3. The primary master-slave relationship between the master unit 12 and the slave unit 13 remains intact, as evidenced by the unchanged states of A.portA and B.portl.

[0151] Experimental Validation of some of embodiments herein:

[0152] To validate the effectiveness of the proposed modifications, experiments were conducted using a BBU and a RU. The experimental results corroborate the successful implementation of the aforementioned modifications. The result illustrated the port states of both the BBU and RU after the activation of a test port functionality. The observed port states aligned precisely with the expected behavior as described in the previous section.

[0153] Thus;

[0154] 1. Node A maintains its primary master role while simultaneously having a port in the UNCALIBRATED state.

[0155] 2. Node B exhibits a port in the MASTER state, specifically corresponding to the test port connection with Node A.

[0156] Further validation was obtained through an examination of the system logs on Node A. The logs revealed the successful reception of PTP messages from Node B,

[0157] The system log entries showed the reception and processing of PTP messages originating from Node B, confirming the establishment of the desired communication channel for timestamp information exchange, i.e., the second PTP indication.

[0158] Embodiments herein demonstrate a successful implementation of maintaining the masterslave relationship between the master unit 12 and the slave unit 13 in the RAN network while simultaneously inverting the roles of A.portB and B.port2, enabling B.port2 to function as a master port, transmitting timestamp information to A.portB, i.e., the second PTP indication.

[0159] Embodiments herein also disclose a time error calculation based on one or more timestamps received from the slave unit 13. The calculation of time error leverages the timestamp information exchanged through PTP messages between the master unit 12 and the slave unit 13.

[0160] As per the PTP protocol specifications, four timestamps may be obtained from the PTP message exchange procedure:

[0161] T1: Extracted from the payload of the Follow_Up message

[0162] T2: Hardware timestamp generated when the Sync message arrives at the slave port T3: Hardware timestamp generated when Linuxptp sends the Delay_Req message T4: Extracted from the payload of the Delay_Resp message

[0163] Fig. 8 shows a PTP Message Exchange and Timestamp FlowFig. 8 illustrates the flow of PTP messages and the corresponding timestamp generation points between the master and slave units or nodes.

[0164] Time Error Calculation: Utilizing these four timestamps, the time error is calculated using the following formula:

[0165] time error = ((T1 - T2) + (T4 - T3)) / 2

[0166] Implementation in Linuxptp: Upon reception of PTP messages through Port B on the master unit 12, the Linuxptp module processes the received timestamps (T1, T2, T3, T4). The module then performs the time error calculation using the aforementioned formula.

[0167] The process of obtaining timestamps T1, T2, T3, and T4, as well as the subsequent calculation of time error within the Linuxptp framework, is illustrated in Fig. 9. Fig. 9 shows timestamp processing in linuxptp.

[0168] Continuous Monitoring and Data Collection: The PTP message exchange between master and slave units occurs continuously, resulting in the generation of a series of time error values. This continuous stream of data may be visualized as:

[0169] . "2...

[0170] (iim - -r mi)

[0171] error: 1-::::. -’l-.r..

[0172] — 41 ^ 4 /

[0173] (riiai -- mi) 4 Mpi - mn

[0174] ilatse em>r[31 -•••••

[0175]

[0176] Implementation Verification: To confirm the correct implementation and operation of this system, system log entries were checked. These system log entries provide real-time visibility into the calculated offset values, as shown in the following excerpt> so -sui Mpts r ws^i.rwy&'.iink, <a»nesM<s?a35$9w, rti: iwwsssmassssta >

[0177] >

[0178]

[0179] To facilitate the collection and utilization of the calculated time error values, some embodiments herein may use a TCP server within the ptp4l module. This method significantly enhances the practicality and accessibility of the testing module.

[0180] TCP Server Implementation:

[0181] Fig. 10 illustrates the architecture of the TCP server implementation within the ptp4l module.

[0182] The TCP server acts as an interface between the Linuxptp core functionality and external client applications, allowing for real-time retrieval of time error data.

[0183] Client-Side Interaction: On the client side, a Python script has been developed to establish a connection with the TCP server. This script utilizes a set of predefined, simple commands to request and receive the stored time error values from Linuxptp.

[0184] Command Set: The current implementation supports the following commands for

[0185] interaction with the TCP server:

[0186] received from client | action

[0187]

[0188] info send: "port 1 [ri_d], state: MASTER, test_port: 0; port 2 [ri_c], state: UNCALIBRA TED,

[0189] test_port: 1;"

[0190] test ri_a set: ri_a as test port

[0191] send: "config ri_c as slave port succeed!"

[0192] measure send: "[2000301114103334}"

[0193] start set: test start, record time

[0194] end set: indicate test end, clear test data

[0195] send:" test start at 2024-01-0509:34:06;

[0196] test end at 2024-02-0510:35:57;

[0197] recorded offset value 59312 times:

[0198] delay request time out 0 times;"

[0199] Commands in TCP server

[0200] This command set allows for flexible and efficient retrieval of time error data, enabling various testing and monitoring scenarios.

[0201] Functionality and Result Accuracy Verification

[0202] To ensure the accuracy and reliability of the collected time error test results, a comprehensive verification process were implemented. Given that the collected results exist as aseries of values, it is essential to employ validated testing methodologies as reference points for comparison.

[0203] In this verification process, two widely recognized and established methods for testing time error are utilized as benchmarks:

[0204] 1. Comparison with Time Error Values Derived from 1 PPS Signals: The first verification method involves comparing the collected time error values against those obtained using 1 Pulse Per Second (1PPS) signals. 1PPS is a precision time protocol that provides a highly accurate reference point for time synchronization.

[0205] 2. Comparison with PTP-based 2-way Time Error Measurements from Paragon: The second verification method employs a comparison with 2-way time error measurements obtained using the Paragon system, which is based on the PTP. This method provides a direct comparison with an industry-standard testing tool.

[0206] Comparative Analysis of 2-way Time Error and 1 PPS Time Error on a Single spanning tree protocol (STP) Setup.

[0207] The primary verification approach involves a comparative analysis of two distinct time error measurement methods: the 2-way time error and the 1PPS time error. This comparison is conducted on a single set of equipment, utilizing an external oscilloscope to measure the time difference between the 1PPS signals output from both the master unit 12 and the slave unit 13.

[0208] Experimental Setup:

[0209] Fig. 11 illustrates the experimental configuration for this verification process.

[0210] Fig. 11 shows a STP for time error test with 1 pps and PTP output

[0211] In this setup, both the DU and RU are configured to output 1PPS signals to the oscilloscope. The time difference between these signals, as measured by the oscilloscope, is defined as the 1PPS time error.

[0212] Results and Analysis: Fig. 12 and Fig. 13 present comparative analysis of the 2-way time error and the 1 PPS time error.

[0213] Baseline Comparison from the Figs 12-13: To enhance the visibility of the test results, an additional 20ns time difference was intentionally introduced to the 1PPS test results.

[0214] Noise Introduction: To validate the accuracy of both methods under extreme conditions, artificial noise was deliberately introduced during the testing process.

[0215] Correlation Analysis: a. Stable Conditions: During periods of stability, the measurements from both the 1 PPS and 2-way methods show a high degree of correlation, b. Noisy Conditions: Even under artificially introduced noise, both methods demonstrate remarkably similar responses, maintaining a close correlation in their time error measurements.

[0216] Conclusion:Accuracy Validation: The close alignment between the 1PPS and 2-way time error measurements, both under stable and artificially noisy conditions, strongly supports the accuracy of the 2-way time error calculation method.

[0217] Reliability: The ability of the 2-way method to closely track the industry-standard 1PPS method across various conditions validates its reliability as a time error measurement technique.

[0218] Applicability: This verification process confirms the applicability of the 2-way time error measurement method in real-world scenarios, including those with potential signal disturbances.

[0219] Experimental Setup:

[0220] In this second set of experiments, an industry-standard testing equipment for PTP-based 2-way time error measurements was used. Due to equipment limitations, it was not feasible to simultaneously connect both the master unit 12 and the industry-standard testing equipment to the same slave unit 13. Consequently, a sequential testing approach was used, connecting the master unit 12 and the industry-standard testing equipment to the slave unit 13 in separate time intervals. This approach is validated by the assumption of stable clock output from the slave unit 13 over time.

[0221] Fig. 14 illustrates the experimental setup for both the master unit 12 and the industrystandard testing equipment connections.

[0222] While the measurements were not taken simultaneously, the reliability of the comparison is maintained due to the following factors:

[0223] 1. Stable RU Clock Output: The RU's clock outputs were considered stable over the testing period.

[0224] 2. Consistent Environmental Conditions: consistent testing conditions were maintained across both measurement sessions.

[0225] Results and Analysis:

[0226] Fig. 15 presents a comparative analysis of the 2-way time error measurements obtained from embodiments herein and the industry-standard testing equipment system.

[0227] From Fig. 15, the shapes and trends of both graphs demonstrate a high degree of correlation, indicating consistent behavior in time error measurements between the two systems.

[0228] Statistical Comparison: The table in the upper right corner of the graphs presents the maximum and minimum statistical values of the data. There are small differences in the table. Given the different precision levels and not tested simultaneously, the observed deviations are both reasonable and acceptable.

[0229] Embodiments herein relate to, e.g., a method performed by the master unit 12 for handling communication in the communication network. The master unit 12 transmits to the slave unit 13,the first PTP indication comprising the first time stamp of the first internal clock of the master unit; and receives from the slave unit 13, the second PTP indication comprising the second time stamp of a second internal clock of the slave unit 13. The master unit 12 estimates the time error indication between the first and second internal clocks based on the first and second PTP indications.

[0230] Embodiments herein may be used in Network self-diagnostics and self-optimization capabilities, and / or Integrated performance monitoring and reporting mechanisms in telecommunications infrastructure.

[0231] Fig. 16 is a block diagram depicting the master unit 12 such as a time reference unit, e.g., a DU or BBU, for handling communication in the communication network 1 according to embodiments herein.

[0232] The master unit 12 may comprise processing circuitry 1601, e.g. one or more processors, configured to perform the methods herein.

[0233] The master unit 12 and / or the processing circuitry 1601 may be configured to setup the second connection to the slave unit 13 to receive the second PTP indication, wherein the second connection is set-up between the first port at the master unit 12 and the second port of the slave unit 13 and wherein the first port is set to an uncalibrated state. The second connection may be setup between the second port at the slave unit 13 and the second port at the master unit 12.

[0234] The master unit 12 and / or the processing circuitry 1601 is configured to transmit to the slave unit 13, the first PTP indication comprising the first time stamp of the first internal clock of the master unit 12.

[0235] The master unit 12 and / or the processing circuitry 1601 is configured to receive from the slave unit 13, the second PTP indication comprising the second time stamp of the second internal clock of the slave unit 13. The master unit may be a BBU and the slave unit may be a RU that are connected via an eCPRI connection and utilize PTP for clock synchronization. The second PTP indication may be received over an additional eCPRI, being an example of the second connection, between the master unit 12 and the slave unit 13 for testing purposes.

[0236] The master unit 12 and / or the processing circuitry 1601 is configured to estimate the time error indication between the first and second internal clocks based on the first and second PTP indications.

[0237] The master unit 12 and / or the processing circuitry 1601 may be configured to use this time error indication to monitor the synchronization performance of the slave unit 13.

[0238] The master unit 12 may comprise a memory 1605. The memory 1605 comprises one or more units to be used to store data on, such as data packets, PTP indications, time error, synchronization data, reports, reports, measurements, events and applications to perform the methods disclosed herein when being executed, and similar. Furthermore, the master unit 12 maycomprise a communication interface 1606 such as comprising a transmitter, a receiver, a transceiver and / or one or more antennas.

[0239] The methods according to the embodiments described herein for the master unit 12 are respectively implemented by means of e.g. a computer program product 1607 or a computer program, comprising instructions, i.e., software code portions, which, when executed on at least one processor, cause the at least one processor to carry out the actions described herein, as performed by the master unit 12. The computer program product 1607 may be stored on a computer-readable storage medium 1608, e g., a disc, a USB stick or similar. The computer-readable storage medium 1608, having stored thereon the computer program product, may comprise the instructions which, when executed on at least one processor, cause the at least one processor to carry out the actions described herein, as performed by the master unit 12. In some embodiments, the computer-readable storage medium may be a transitory or a non-transitory computer-readable storage medium. Thus, embodiments herein may disclose the master unit 12 for handling communication of the master unit 12 in a communication network, wherein the master unit 12 comprises processing circuitry and a memory, said memory comprising instructions executable by said processing circuitry whereby said master unit 12 is operative to perform any of the methods herein.

[0240] Fig. 17 is a block diagram depicting the slave unit 13 such as a RU, for handling communication in the communication network 1 according to embodiments herein.

[0241] The slave unit 13 may comprise processing circuitry 1701, e.g. one or more processors, configured to perform the methods herein.

[0242] The slave unit 13 and / or the processing circuitry 1701 may be configured to setup the second connection to the master unit 12 to transmit the second PTP indication, wherein the second connection is set-up between the first port at the master unit 12 and the second port of the slave unit 13 and wherein the first port is set to an uncalibrated state. The second connection may be setup between the second port at the slave unit 13 and the second port at the master unit 12.

[0243] The slave unit 13 and / or the processing circuitry 1701 is configured to receive from the master unit 12 or another slave unit, the first PTP indication comprising the first time stamp of the first internal clock of the master unit 12. The other slave unit may forward the first PTP from the master unit 12.

[0244] The slave unit 13 and / or the processing circuitry 1701 may be configured to apply one or more (second) time stamps upon reception of the first PTP indication and / or transmission of the second PTP indication.

[0245] The slave unit 13 and / or the processing circuitry 1701 is configured to transmit to the master unit 12 or the other slave unit, the second PTP indication comprising the second time stamp of the second internal clock of the slave unit using the second connection to the master unit12 to transmit the second PTP indication, wherein the second connection is set up between the first port at the master unit 12 and the second port of the slave unit 13 and wherein the first port is set to the uncalibrated state.

[0246] The slave unit 13 may comprise a memory 1705. The memory 1705 comprises one or more units to be used to store data on, such as data packets, PTP indications, time error, synchronization data, reports, reports, measurements, events and applications to perform the methods disclosed herein when being executed, and similar. Furthermore, the slave unit 13 may comprise a communication interface 1706 such as comprising a transmitter, a receiver, a transceiver and / or one or more antennas.

[0247] The methods according to the embodiments described herein for the slave unit 13 are respectively implemented by means of e.g. a computer program product 1707 or a computer program, comprising instructions, i.e., software code portions, which, when executed on at least one processor, cause the at least one processor to carry out the actions described herein, as performed by the slave unit 13. The computer program product 1707 may be stored on a computer-readable storage medium 1708, e g., a disc, a USB stick or similar. The computer-readable storage medium 1708, having stored thereon the computer program product, may comprise the instructions which, when executed on at least one processor, cause the at least one processor to carry out the actions described herein, as performed by the slave unit 13. In some embodiments, the computer-readable storage medium may be a transitory or a non-transitory computer-readable storage medium. Thus, embodiments herein may disclose the slave unit 13 for handling communication of the slave unit 13 in a communication network, wherein the slave unit 13 comprises processing circuitry and a memory, said memory comprising instructions executable by said processing circuitry whereby said slave unit 13 is operative to perform any of the methods herein.

[0248] In some embodiments a more general term “network node” or “radio network node” is used and it can correspond to any type of radio-network node or any network node, which communicates with a UE and / or with another network node.

[0249] In some embodiments the non-limiting term wireless device or user equipment (UE) is used and it refers to any type of wireless device communicating with a network node and / or with another wireless device in a cellular or mobile communication system. Examples of UE are target device, device to device (D2D) UE, proximity capable UE (aka ProSe UE), loT capable device, machine type UE or UE capable of machine to machine (M2M) communication, Tablet, mobile terminals, smart phone, laptop embedded equipped (LEE), laptop mounted equipment (LME), USB dongles etc.

[0250] Embodiments are applicable to any RAT or multi-RAT systems, where the wireless device receives and / or transmit signals (e.g. data) e.g. NR, Wi-Fi, LTE, LTE-Advanced, Wideband CodeDivision Multiple Access (WCDMA), Global System for Mobile communications / enhanced Data rate for GSM Evolution (GSM / EDGE), Worldwide Interoperability for Microwave Access (WiMax), or Ultra Mobile Broadband (UMB), just to mention a few possible implementations.

[0251] As will be readily understood by those familiar with communications design, that functions means or modules may be implemented using digital logic and / or one or more microcontrollers, microprocessors, or other digital hardware. In some embodiments, several or all of the various functions may be implemented together, such as in a single application-specific integrated circuit (ASIC), or in two or more separate devices with appropriate hardware and / or software interfaces between them. Several of the functions may be implemented on a processor shared with other functional components of a radio network node, for example.

[0252] Alternatively, several of the functional elements of the processing means discussed may be provided through the use of dedicated hardware, while others are provided with hardware for executing software, in association with the appropriate software or firmware. Thus, the term “processor” or “controller” as used herein does not exclusively refer to hardware capable of executing software and may implicitly include, without limitation, digital signal processor (DSP) hardware, read-only memory (ROM) for storing software, random-access memory for storing software and / or program or application data, and non-volatile memory. Other hardware, conventional and / or custom, may also be included. Designers of communications receivers will appreciate the cost, performance, and maintenance trade-offs inherent in these design choices.

[0253] In certain embodiments, some or all of the functionality described herein may be provided by processing circuitry executing instructions stored on in memory, which in certain embodiments may be a computer program product in the form of a non-transitory computer-readable storage medium. In alternative embodiments, some or all of the functionality may be provided by the processing circuitry without executing instructions stored on a separate or discrete device-readable storage medium, such as in a hard-wired manner. In any of those particular embodiments, whether executing instructions stored on a non-transitory computer-readable storage medium or not, the processing circuitry can be configured to perform the described functionality. The benefits provided by such functionality are not limited to the processing circuitry alone or to other components of the computing device, but are enjoyed by the computing device as a whole, and / or by end users and a wireless network generally.

[0254] It will be appreciated that the foregoing description and the accompanying drawings represent non-limiting examples of the methods and apparatus taught herein. As such, the apparatus and techniques taught herein are not limited by the foregoing description and accompanying drawings. Instead, the embodiments herein are limited only by the following claims and their legal equivalents.

Claims

CLAIMS1. A method performed by a master unit for handling communication in a communication network, the method comprising:transmitting (402) to a slave unit, a first precision time protocol, PTP, indication comprising a first time stamp of a first internal clock of the master unit;receiving (403) from the slave unit, a second PTP indication comprising a second time stamp of a second internal clock of the slave unit; andestimating (404) a time error indication between the first and second internal clocks based on the first and second PTP indications.

2. The method according to claim 1, wherein the master unit is a baseband unit, BBU, and the slave unit is a radio unit, RU, that are connected via an enhanced Common Public Radio Interface, eCPRI, connection and utilize PTP for clock synchronization.

3. The method according to any of the claims 1-2, wherein the second PTP indication is received over an additional eCPRI between the master unit and the slave unit for testing purposes.

4. The method according to any of the claims 1-3, wherein the master unit sets up a second connection to the slave unit to receive the second PTP indication, wherein the second connection is set up between a second port at the master unit and a second port of the slave unit and wherein the second port at the master unit is set to an uncalibrated state.

5. The method according to any of the claims 1-4, further comprisingusing (405) the time error indication to monitor a synchronization performance of the slave unit (13).

6. A method performed by a slave unit for handling communication in a communication network, the method comprisingreceiving (503) from a master unit or another slave unit, a first precision time protocol, PTP, indication comprising a first time stamp of a first internal clock of the master unit; andtransmitting (504) to the master unit or the other slave unit, a second PTP indication comprising a second time stamp of a second internal clock of the slave unit using a second connection to the master unit to transmit the second PTP indication, wherein the second connection is set up between a second port at the master unit and a secondport of the slave unit and wherein the second port at the master unit is set to an uncalibrated state.

7. A master unit (12) for handling communication in a communication network (1), wherein the master unit (12) is configured to:transmit to a slave unit (13), a first precision time protocol, PTP, indication comprising a first time stamp of a first internal clock of the master unit (12);receive from the slave unit (13), a second PTP indication comprising a second time stamp of a second internal clock of the slave unit (13); andestimate a time error indication between the first and second internal clocks based on the first and second PTP indications.

8. The master unit (12) according to claim 7, wherein the master unit is a baseband unit, BBU, and the slave unit is a radio unit, RU, that are configured to be connected via an enhanced Common Public Radio Interface, eCPRI, connection and to utilize PTP for clock synchronization.

9. The master unit (12) according to any of the claims 7-8, wherein the master unit (12) is configured to receive the second PTP indication over an additional eCPRI between the master unit (12) and the slave unit (13) for testing purposes.

10. The master unit (12) according to any of the claims 7-9, wherein the master unit (12) is configured to set up a second connection to the slave unit (13) to receive the second PTP indication, wherein the second connection is set up between a second port at the master unit (12) and a second port of the slave unit (13) and wherein the second port at the master unit is set to an uncalibrated state.

11. The master unit (12) according to any of the claims 7-10, wherein the master unit (12) is configured to use the time error indication to monitor a synchronization performance of the slave unit (13).

12. A slave unit (13) for handling communication in a communication network, wherein the slave unit (13) is configured to:receive from a master unit (12) or another slave unit, a first precision time protocol, PTP, indication comprising a first time stamp of a first internal clock of the master unit (12); andtransmit to the master unit (12) or the other slave unit, a second PTP indication comprising a second time stamp of a second internal clock of the slave unit using asecond connection to the master unit (12) to transmit the second PTP indication, wherein the second connection is set up between a second port at the master unit (12) and a second port of the slave unit (13) and wherein the second port at the master unit is set to an uncalibrated state.

13. A computer program product comprising instructions, which, when executed on at least one processor, cause the at least one processor to carry out the method according to any of the claims 1-6, as performed by the master unit and the slave unit, respectively.

14. A computer-readable storage medium, having stored thereon a computer program product comprising instructions which, when executed on at least one processor, cause the at least one processor to carry out the method according to any of the claims 1-6, as performed by the master unit and the slave unit, respectively.

Images