WO2023130217A1

WO2023130217A1 - Method and apparatus for radio over ethernet

Info

Publication number: WO2023130217A1
Application number: PCT/CN2022/070134
Authority: WO
Inventors: Daiying LIU; Jun Deng
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2022-01-04
Filing date: 2022-01-04
Publication date: 2023-07-13

Abstract

Various embodiments of the present disclosure provide a method for radio over Ethernet (RoE). According to the method, a first RoE device may transmit a first message with a first timestamp to a second RoE device. The first message may include: a first parameter which is related to presentation time of RoE data from the first RoE device at the second RoE device; and a second parameter which is related to presentation time of RoE data from the second RoE device at the first RoE device. The first parameter and the second parameter are set to have a same first value. In an embodiment, the first RoE device may receive a candidate value of the first parameter from the second RoE device, which may enable the first parameter and the second parameter to be adjusted from the first value to a second value.

Description

METHOD AND APPARATUS FOR RADIO OVER ETHERNET

FIELD OF THE INVENTION

The present disclosure generally relates to communication networks, and more specifically, to a method and apparatus for radio over Ethernet (RoE) .

BACKGROUND

This section introduces aspects that may facilitate a better understanding of the disclosure. Accordingly, the statements of this section are to be read in this light and are not to be understood as admissions about what is in the prior art or what is not in the prior art.

RoE is the encapsulation and mapping of radio protocols for transport over Ethernet frames. Radio data may be encapsulated into Ethernet frames and forwarded because today’s transport networking solutions may not be able to satisfy various expectations on radio data transmissions. On the other hand, Ethernet technology has experienced steady and cost-efficient speed and capacity growth, driven by the enterprise, access, and data-center markets, and has inherent characteristics that allow it to satisfy other expectations.

SUMMARY

This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

Timestamp mode may be used for RoE. There may be a timestamp field in the RoE header in RoE packets generated by a RoE mapper device. It may be a 32-bit field and provide a start-of-frame marker, a condensed sequence number, and the absolute time for presentation (i.e., the presentation time) of the packet information by a RoE de-mapper device at the receiving endpoint. A RoE device may need to determine the correct presentation time according to the current time and the latency, so that a remote RoE end can replay the RoE packet information continuously according to the presentation time. The existing implementations for the presentation time are usually based on user-configured latency. However, the latency may be affected by many factors, e.g., including but not limited to the time for data conversion, encapsulation, forwarding, de-encapsulation, etc., which may vary with communication environments and device capabilities. It may be very likely to configure or set the latency small or too large, resulting in the failure of smooth presentation of the RoE packet information due to the improper presentation time based on unsuitable latency configuration. Therefore, it may be desirable to determine the presentation time of RoE packet data in a more efficient way.

Various embodiments of the present disclosure propose a solution for RoE, which can enable the presentation time of RoE packet data to be determined more accurately, e.g., by dynamically determining the transmission delay between a pair of RoE devices and/or adaptively adjusting the presentation time according to the transmission delay.

According to a first aspect of the present disclosure, there is provided a method which may be performed by a first RoE device. The method comprises: transmitting a first message with a first timestamp to a second RoE device. In an embodiment, the first message may include a first parameter and a second parameter. The first parameter is related to presentation time of RoE data from the first RoE device at the second RoE device. The second parameter is related to presentation time of RoE data from the second RoE device at the first RoE device. The first parameter and the second parameter may be set to have a same first value. A time when the first message arrives at the second RoE device may be indicated by a second timestamp which may have a first difference from the first timestamp. In accordance with an exemplary embodiment, when a gap between the first difference and the first value is equal to or larger than a threshold, the method may further comprise: receiving a candidate value of the first parameter from the second RoE device. According to the candidate value of the first parameter received from the second RoE device and a candidate value of the second parameter determined by the first RoE device, the first RoE device may adjust the first parameter and the second parameter from the first value to a second value. In accordance with an exemplary embodiment, the method may further comprise: transmitting the second value of the first parameter and the second parameter to the second RoE device.

In accordance with an exemplary embodiment, the candidate value of the first parameter may be equal to the first difference between the first timestamp and the second timestamp.

In accordance with an exemplary embodiment, the second value of the first parameter and the second parameter may be equal to a larger of the candidate value of the first parameter and the candidate value of the second parameter.

In accordance with an exemplary embodiment, when the first RoE device does not receive a second message with a third timestamp from the second RoE device, the candidate value of the second parameter determined by the first RoE device may be equal to the first value.

In accordance with an exemplary embodiment, the method according to the first aspect of the present disclosure may further comprise: receiving a second message with a third timestamp from the second RoE device. In an embodiment, the second message may include the first parameter and the second parameter, and the first parameter and the second parameter may be set to have the same first value.

In accordance with an exemplary embodiment, the method according to the first aspect of the present disclosure may further comprise: calculating a second difference between the third timestamp and a fourth timestamp. In an embodiment, a time when the second message arrives at the first RoE device may be indicated by the fourth timestamp.

In accordance with an exemplary embodiment, the candidate value of the second parameter may be determined by the first RoE device according to the second difference between the third timestamp and the fourth timestamp.

In accordance with an exemplary embodiment, when the second difference between the third timestamp and the fourth timestamp is different from the first value, the candidate value of the second parameter determined by the first RoE device may be equal to the second difference between the third timestamp and the fourth timestamp.

In accordance with an exemplary embodiment, the method according to the first aspect of the present disclosure may further comprise: determining the presentation time of the RoE data from the second RoE device at the first RoE device, according to the second parameter.

In accordance with an exemplary embodiment, the method according to the first aspect of the present disclosure may further comprise: determining delay time of RoE transmission from the first RoE device to the second RoE device, according to the first parameter.

According to a second aspect of the present disclosure, there is provided an apparatus which may be implemented as a first RoE device. The apparatus may comprise one or more processors and one or more memories comprising computer program codes. The one or more memories and the computer program codes may be configured to, with the one or more processors, cause the apparatus at least to perform any step of the method according to the first aspect of the present disclosure.

According to a third aspect of the present disclosure, there is provided a computer-readable medium storing computer program codes which, when executed on a computer, cause the computer to perform any step of the method according to the first aspect of the present disclosure.

According to a fourth aspect of the present disclosure, there is provided a method which may be performed by a second RoE device. The method comprises: receiving a first message with a first timestamp from a first RoE device. In an embodiment, the first message may include a first parameter and a second parameter. The first parameter is related to presentation time of RoE data from the first RoE device at the second RoE device. The second parameter is related to presentation time of RoE data from the second RoE device at the first RoE device. The first parameter and the second parameter may be set to have a same first value. In accordance with an exemplary embodiment, the method may further comprise: calculating a first difference between the first timestamp and a second timestamp. A time when the first message arrives at the second RoE device may be indicated by the second timestamp. In accordance with an exemplary embodiment, when a gap between the first difference and the first value is equal to or larger than a threshold, the method may further comprise: transmitting a candidate value of the first parameter to the first RoE device to adjust the first parameter and the second parameter from the first value to a second value. In accordance with an exemplary embodiment, the method may further comprise: receiving the second value of the first parameter and the second parameter from the first RoE device.

In accordance with an exemplary embodiment, the second value of the first parameter and the second parameter may be equal to a larger of the candidate value of the first parameter transmitted to the first RoE device and a candidate value of the second parameter determined by the first RoE device.

In accordance with an exemplary embodiment, when the second RoE device does not transmit a second message with a third timestamp to the first RoE device, the candidate value of the second parameter determined by the first RoE device may be equal to the first value.

In accordance with an exemplary embodiment, the method according to the fourth aspect of the present disclosure may further comprise: transmitting a second message with a third timestamp to the first RoE device. In an embodiment, the second message may include the first parameter and the second parameter, and the first parameter and the second parameter may be set to have the same first value.

In accordance with an exemplary embodiment, a time when the second message arrives at the first RoE device may be indicated by a fourth timestamp which may have a second difference from the third timestamp. In an embodiment, the candidate value of the second parameter may be determined by the first RoE device according to the second difference between the third timestamp and the fourth timestamp.

In accordance with an exemplary embodiment, the method according to the fourth aspect of the present disclosure may further comprise: determining the presentation time of the RoE data from the first RoE device at the second RoE device, according to the first parameter.

In accordance with an exemplary embodiment, the method according to the fourth aspect of the present disclosure may further comprise: determining delay time of RoE transmission from the second RoE device to the first RoE device, according to the second parameter.

According to a fifth aspect of the present disclosure, there is provided an apparatus which may be implemented as a second RoE device. The apparatus may comprise one or more processors and one or more memories comprising computer program codes. The one or more memories and the computer program codes may be configured to, with the one or more processors, cause the apparatus at least to perform any step of the method according to the fourth aspect of the present disclosure.

According to a sixth aspect of the present disclosure, there is provided a computer-readable medium storing computer program codes which, when executed on a computer, cause the computer to perform any step of the method according to the fourth aspect of the present disclosure.

Various exemplary embodiments according to the present disclosure can enable the RoE delay time to be measured automatically and accurately, e.g., by utilizing timestamp information exchanged between RoE devices, so that the RoE devices can adjust the presentation time adaptively with a change of the measured RoE delay time. This can make the calculation of the presentation time of RoE packet data easier and more flexible, thereby reducing the difficulty of user configuration, saving operation and maintenance cost, and improving data transmission and presentation performance.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure itself, the preferable mode of use and further objectives are best understood by reference to the following detailed description of the embodiments when read in conjunction with the accompanying drawings, in which:

Fig. 1 is a diagram illustrating an exemplary RoE deployment scenario according to an embodiment of the present disclosure;

Fig. 2 is a diagram illustrating an exemplary Ethernet message format according to an embodiment of the present disclosure;

Fig. 3 is a diagram illustrating an exemplary message processing procedure according to an embodiment of the present disclosure;

Fig. 4 is a flowchart illustrating a method according to an embodiment of the present disclosure; and

Fig. 5 is a flowchart illustrating another method according to an embodiment of the present disclosure; and

Fig. 6 is a block diagram illustrating an apparatus according to an embodiment of the present disclosure.

DETAILED DESCRIPTION

The embodiments of the present disclosure are described in detail with reference to the accompanying drawings. It should be understood that these embodiments are discussed only for the purpose of enabling those skilled persons in the art to better understand and thus implement the present disclosure, rather than suggesting any limitations on the scope of the present disclosure. Reference throughout this specification to features, advantages, or similar language does not imply that all of the features and advantages that may be realized with the present disclosure should be or are in any single embodiment of the disclosure. Rather, language referring to the features and advantages is understood to mean that a specific feature, advantage, or characteristic described in connection with an embodiment is included in at least one embodiment of the present disclosure. Furthermore, the described features, advantages, and characteristics of the disclosure may be combined in any suitable manner in one or more embodiments. One skilled in the relevant art will recognize that the disclosure may be practiced without one or more of the specific features or advantages of a particular embodiment. In other instances, additional features and advantages may be recognized in certain embodiments that may not be present in all embodiments of the disclosure.

As used herein, the terms “first” , “second” and so forth refer to different elements. The singular forms “a” and “an” are intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises” , “comprising” , “has” , “having” , “includes” and/or “including” as used herein, specify the presence of stated features, elements, and/or components and the like, but do not preclude the presence or addition of one or more other features, elements, components and/or combinations thereof. The term “based on” is to be read as “based at least in part on” . The term “one embodiment” and “an embodiment” are to be read as “at least one embodiment” . The term “another embodiment” is to be read as “at least one other embodiment” . Other definitions, explicit and implicit, may be included below.

As a standard for radio over Ethernet encapsulations and mappings, Institute of Electrical and Electronics Engineers (IEEE) 1914.3 specifies details that allow Ethernet to partake in the new RoE transport networking solution for the fifth generation (5G) /new radio (NR) cellular services.

In order to use RoE timestamp mode correctly, a RoE device may need to enter the correct presentation time in the timestamp field of the RoE header. This presentation time is a future time that tells the remote RoE end when to replay the RoE packet payload into a common public radio interface (CPRI) and send to the connected baseband unit (BBU) or remote radio unit (RRU) . According to this principle, the presentation time may be calculated as below:

Presentation time = Current time + Latency (1)

The latency (also called “delay time” in this document, or “delay” for short) may include many complex factors, such as the time for CPRI data to be converted and encapsulated into the Ethernet packets by the mapper, the time for one or more RoE devices to forward the Ethernet packets, the Ethernet packets forwarding time on the Ethernet, and the time for a remote RoE device to decapsulate the RoE packets and convert them into CPRI data, etc.

Generally, the above factors are collectively referred to as latency. If the presentation time is not correct, CPRI frames may not be replayed continuously and the CPRI connection between the BBU and the RRU may go down.

A widely used implementation for the presentation time is based on user-configured latency. Thus, it may be possible to set the latency larger or smaller than needed. Setting the latency larger than needed may have the following drawbacks:

- The RoE de-mapper may need to have a big buffer to cache the RoE packets arrived earlier than the presentation time.

- The total CPRI latency between a BBU and an RRU may increase accordingly so that the radio performance may be impacted.

On the other hand, in the case that the latency is set smaller than needed, some or all of the RoE packets may arrive the de-mapper later than the presentation time, and this may cause the CPRI to go down and endanger the radio access network (RAN) service.

All RoE products in the industry today are user-configured for the latency, so there may be some challenging issues as below:

- The calculation of latency is very complicated and many factors may need to be considered. Moreover, some factors (such as the conversion time of CPRI data to RoE packets and the forwarding delay of RoE devices, etc. ) may involve very detailed implementations, which may be very unfriendly to user configuration and error-prone.

- Some latency (such as the forwarding time of Ethernet packets on the Ethernet) may change frequently. The traffic between a pair of RoE devices may be very large (e.g., usually more than 100G) . Therefore, once congestion occurs on the Ethernet, the total delay time may change drastically, resulting in traffic interruption. In addition, some fronthaul deployment may have a traffic path redundancy design, which means that the RoE traffic may have more than one path from one RoE end (mapper) to the other RoE end (de-mapper) and the traffic path may change with the network failure/event, and so the latency may change accordingly.

- The latency is relevant to the fiber length (～5μs latency per kilometer of fiber) , but it may not be easy for the operator to know the exact fiber length and to sum it up with other factors. The configuration may be always based on estimation, which is not accurate and problematic.

In addition, it is also problematic to set the latency too large for safety, because the performance of BBU/RRU may decrease with the increase of the latency. Therefore, it may be desirable to achieve the accurate configuration to solve one or more above problems.

Various exemplary embodiments of the present disclosure propose a solution to make the RoE delay time or latency be measured automatically. In accordance with an exemplary embodiment, the transmission delay between a pair of RoE devices (e.g., including the chip forwarding delay of the RoE devices and the packet forwarding delay on the Ethernet network, etc. ) may be accurately measured by exchanging one or more messages with timestamp information between the RoE devices, so as to achieve the purpose of automatically configuring the latency setting in timestamp mode of RoE. Through the message interaction between the pair of RoE devices, the complex transmission delay time can be automatically measured and the presentation time of RoE packet data may be calculated precisely. In accordance with another embodiment, a change of transmission delay time on the Ethernet network (e.g., a change of transmission time due to congestion, or a change of forwarding path due to a variation on some dynamic protocols, such as media access control/Ethernet virtual private network (MAC/EVPN) , etc. ) may be perceived and the RoE delay time setting may be automatically adjusted according to the change of transmission delay time.

Many advantages may be achieved by applying the proposed solutions. For example, compared to the conventional user-configuration of delay time, automatic measurement and configuration of delay time can decrease the operation complexity for customers, improve user experience and reduce the deployment and maintenance cost. It also can efficiently avoid RAN crash caused by a sudden change of the Ethernet forwarding path. In addition to automatically measuring the delay time, the proposed solutions may also support dynamical adjustment of equipment configuration (e.g., configurations of latency/delay time/presentation time, etc. ) , so as to ensure RoE service ability.

Fig. 1 is a diagram illustrating an exemplary RoE deployment scenario according to an embodiment of the present disclosure. In the exemplary RoE deployment scenario as shown in Fig. 1, a BBU may communicate with RoE device 1 via CPRI, and similarly an RRU may communicate with RoE device 2 via CPRI. RoE traffic data may be exchanged between RoE device 1 and RoE device 2 through the Ethernet. Transmission delay and data processing time on both RoE devices may not be fixed, but may change dynamically. In accordance with an exemplary embodiment, a time-stamped message may be used to measure the delay time between a pair of RoE devices such as RoE device 1 and RoE device 2.

Fig. 2 is a diagram illustrating an exemplary Ethernet message format according to an embodiment of the present disclosure. According to the new Ethernet message format definition as shown in Fig. 2, the timestamp may be carried in the Ethernet message and exchanged between a pair of RoE devices. As an example, an Ethernet message may include the following fields:

● DST MAC: Ethernet packet destination MAC;

● SRC MAC: Ethernet packet source MAC;

● VLAN (Virtual Local Area Network) : Ethernet packet VLAN type and identifier (ID) ;

● Ether Type: FC3D, which may be required by standard IEEE 1914.3;

● RoE PKT Version and Type: Fixed to 0, indicating this is a control packet;

● Flow ID: RoE session flow ID, which may be the unique ID to identify one RoE session;

● Length: Cover everything after this field, in octets; Fixed to 25 bytes for this packet format;

● Message Type: Indicating that this message may be used for delay monitoring, or delay adjustment request/reply;

● TS-Da1: Delay time applied on device 1 (e.g., one of a pair of RoE devices) ;

● TS-Da2: Delay time applied on device 2 (e.g., the other of the pair of RoE devices) ;

● TS: The timestamp needs to be carried to the remote device.

It can be appreciated that the Ethernet message format shown in Fig. 2 is just an example, more or less fields with each containing more or less bytes may be applicable for various embodiments of the present disclosure. In an embodiment, the Ethernet format may be configurable, e.g., when the “transmission delay automatic measurement” is enabled and/or the “transmission delay automatic measurement period” is valid. This can provide enough flexibility for deployment, especially for the case that some special scenarios may need to set a value of the delay time manually.

Fig. 3 is a diagram illustrating an exemplary message processing procedure according to an embodiment of the present disclosure. Two RoE devices (i.e., RoE device A and RoE device B in Fig. 3) may be involved in this message processing procedure. As an example, a RoE device may include a RoE mapper, a timestamp generator, a RoE de-mapper, and a delay controller. The mapper device of RoE device A may start an Ethernet frame to the de-mapper device of RoE device B. Similarly, the mapper device of RoE device B may start an Ethernet frame to the de-mapper device of RoE device A. In accordance with an exemplary embodiment, the message processing procedure shown in Fig. 3 may include delay monitoring in Phase 1 and optionally delay adjustment in Phase 2.

During Phase 1, the two ends of RoE transmission (i.e., RoE device A and RoE device B) may monitor the delay time continuously or periodically or on demand. In the initial state, since both RoE device A and RoE device B have no knowledge about the delay time between the two RoE devices, a delay parameter D-a (which indicates the delay time of transmission from RoE device A to RoE device B) and a delay parameter D-b (which indicates the delay time of transmission from RoE device B to RoE device A) may be set to 0 or any other suitable value. In the stable state, D-a and D-b which can be determined by performing delay monitoring may have the same value, e.g., due to the same or similar communication environment and/or transmission configuration.

In order to implement the delay monitoring, the delay controller of RoE device A may trigger delay measurement in step 1-a, e.g., continuously, periodically or on demand, then the delay parameters D-a and D-b may be dynamically obtained through packet interaction at both ends. In step 2-a, the RoE mapper of RoE device A may generate a delay monitoring message with a timestamp Ta1, a delay parameter D-a used by this mapper, and a delay parameter D-b used by the remote mapper. In an embodiment, according to the message format as defined in Fig. 2, the delay monitoring message may have the “TS-Da1” field set to D-a, the “TS-Da2” field set to D-b, and the “TS” field set to Ta1. In step 3-a, the RoE mapper of RoE device A may send the delay monitoring message as a RoE in band message. In step 4-a, the RoE de-mapper of RoE device B may receive the delay monitoring message from RoE device A, and add the timestamp Tb1. In step 5-a, the delay controller of RoE device B can calculate a new value of the delay parameter D-a as D-a’=Tb1-Ta1. In this case, RoE device B can get the measured delay time D-a=D-a’ (from RoE device A to RoE device B) . In an embodiment, RoE device B may send a message with the new value of the delay parameter D-a=D-a’ to RoE device A, so that RoE device A can also get this value and may optionally add it into the delay monitoring message next time.

In accordance with an exemplary embodiment, RoE device B may also follow the same or similar handling procedure with RoE device A, so as to monitor the delay time from RoE device B to RoE device A. For example, the delay controller of RoE device B may trigger delay measurement in step 1-b, and the RoE mapper of RoE device B may generate, in step 2-b, a delay monitoring message with a timestamp Tb2, a delay parameter D-b used by this mapper, and a delay parameter D-a used by the remote mapper. In an embodiment, according to the message format as defined in Fig. 2, the delay monitoring message may have the “TS-Da1” field set to D-a, the “TS-Da2” field set to D-b, and the “TS” field set to Tb2. In step 3-b, the RoE mapper of RoE device B may send the delay monitoring message as a RoE in band message. In step 4-b, the RoE de-mapper of RoE device A may receive the delay monitoring message from RoE device B, and add the timestamp Ta2. In step 5-b, the delay controller of RoE device A can calculate a new value of the delay parameter D-b as D-b’＝Ta2-Tb2. In this case, RoE device A can get the measured delay time D-b=D-b’ (from RoE device B to RoE device A) . In an embodiment, RoE device A may send a message with the new value of the delay parameter D-b=D-b’ to RoE device B, so that RoE device B can also get this value and may optionally add it into the delay monitoring message next time.

During Phase 2, any of the two ends (e.g., RoE device A and RoE device B) may find that the measured delay (e.g., D-a’/D-b’) is different from the delay in use (e.g., D-a/D-b) . In an embodiment, when the gap between the measured delay and the delay in use crosses a threshold, the RoE device may trigger a delay adjustment, so as to change the configuration of delay time and/or presentation time.

In accordance with an exemplary embodiment, the delay controller of RoE device A may detect that the measured delay D-b’ is different from the delay in use, i.e. D-a and D-b (D-a=D-b) . If the gap between the measured delay and the delay in use crosses the threshold, the delay controller of RoE device A may trigger a delay adjustment and send a request message with the suggested delay D’=D-b’ to RoE device B, as shown in step “Req: 1” of Fig. 3. In an embodiment, according to the message format shown in Fig. 2, the request message may have the “TS-Da1” field set to D-a, the “TS-Da2” field set to D-b, and the “TS” field set to D-b’. At the remote end, upon receiving the request message, the delay controller of RoE device B can calculate a new value of delay as D” = Max (D-b’, D-a’) , where D-a’ is the delay from RoE device A to RoE device B as measured in step 5-a. In an embodiment, according to the delay D” , the RoE device B may adaptively adjust its presentation time configuration in step “Req: 2” .

In accordance with an exemplary embodiment, the delay controller of RoE device B may trigger a delay adjustment and send a reply message with the suggested delay D” = Max (D-b’, D-a’) to RoE device A, as shown in step “Rep: 1” . In an embodiment, according to the message format shown in Fig. 2, the reply message may have the “TS-Da1” field set to D-a, the “TS-Da2” field set to D-b=D” , and the “TS” field set to D” . In step “Rep: 2” , upon receiving the reply message with the suggested delay D” , RoE device A may adaptively adjust its presentation time configuration according to the delay D” .

According to various exemplary embodiments, the delay time between a pair of RoE devices such as RoE device A and RoE device B can be measured automatically and accurately without user configuration, thereby reducing the network operating costs while increasing the flexibility of Ethernet forwarding path planning. Moreover, since the presentation time can be adjusted with a change of the delay time according to the exemplary embodiments, a RoE device can replay RoE packet data correctly and timely, ensuring the RoE service performance.

Fig. 4 is a flowchart illustrating a method 400 according to an embodiment of the present disclosure. The method 400 illustrated in Fig. 4 may be performed by a first RoE device (e.g., RoE device B in Fig. 3) or an apparatus communicatively coupled to the first RoE device. In accordance with an exemplary embodiment, the first RoE device may be configured to support delay time measurement and/or adjustment by exchanging messages with one or more other RoE devices.

According to the exemplary method 400 illustrated in Fig. 4, the first RoE device may transmit a first message with a first timestamp (e.g., Tb2 as described with respect to Fig. 3) to a second RoE device (e.g., RoE device A in Fig. 3) , as shown in block 402. In an embodiment, the first message may include a first parameter (e.g., D-b as described with respect to Fig. 3) and a second parameter (e.g., D-a as described with respect to Fig. 3) . The first parameter is related to presentation time of RoE data from the first RoE device at the second RoE device. The second parameter is related to presentation time of RoE data from the second RoE device at the first RoE device. The first parameter and the second parameter may be set to have a same first value. In an embodiment, a time when the first message arrives at the second RoE device may be indicated by a second timestamp (e.g., Ta2 as described with respect to Fig. 3) which may have a first difference from the first timestamp.

In accordance with an exemplary embodiment, when a gap between the first difference and the first value is equal to or larger than a threshold, the first RoE device may receive a candidate value (e.g., D-b’ as described with respect to Fig. 3) of the first parameter from the second RoE device, as shown in block 404. According to the candidate value of the first parameter received from the second RoE device and a candidate value (e.g., D-a or D-a’ as described with respect to Fig. 3) of the second parameter determined by the first RoE device, the first RoE device may adjust the first parameter and the second parameter from the first value to a second value, as shown in block 406. In an embodiment, the first RoE device may transmit the second value of the first parameter and the second parameter to the second RoE device, as shown in block 408.

In accordance with an exemplary embodiment, the first RoE device may receive a second message with a third timestamp (e.g., Ta1 as described with respect to Fig. 3) from the second RoE device. In an embodiment, the second message may include the first parameter and the second parameter, and the first parameter and the second parameter may be set to have the same first value.

In accordance with an exemplary embodiment, the first RoE device may calculate a second difference between the third timestamp and a fourth timestamp (e.g., Tb1 as described with respect to Fig. 3) . A time when the second message arrives at the first RoE device may be indicated by the fourth timestamp.

In accordance with an exemplary embodiment, the first RoE device may determine the candidate value of the second parameter according to the second difference between the third timestamp and the fourth timestamp.

In accordance with an exemplary embodiment, the first RoE device may determine the presentation time of the RoE data from the second RoE device at the first RoE device, according to the second parameter. Alternatively or additionally, the first RoE device may determine the presentation time of the RoE data from the first RoE device at the second RoE device, according to the first parameter.

In accordance with an exemplary embodiment, the first RoE device may determine delay time of RoE transmission from the first RoE device to the second RoE device, according to the first parameter. Alternatively or additionally, the first RoE device may determine delay time of RoE transmission from the second RoE device to the first RoE device, according to the second parameter.

Fig. 5 is a flowchart illustrating a method 500 according to an embodiment of the present disclosure. The method 500 illustrated in Fig. 5 may be performed by a second RoE device (e.g., RoE device A in Fig. 3) or an apparatus communicatively coupled to the second RoE device. In accordance with an exemplary embodiment, the second RoE device may be configured to support delay time measurement and/or adjustment by exchanging messages with one or more other RoE devices (e.g., RoE device B in Fig. 3) .

According to the exemplary method 500 illustrated in Fig. 5, the second RoE device may receive a first message (e.g., the first message as described with respect to Fig. 4) with a first timestamp from a first RoE device (e.g., the first RoE device as described with respect to Fig. 4) , as shown in block 502. In an embodiment, the first message may include a first parameter (e.g., D-b as described with respect to Fig. 3) and a second parameter (e.g., D-a as described with respect to Fig. 3) . The first parameter is related to presentation time of RoE data from the first RoE device at the second RoE device. The second parameter is related to presentation time of RoE data from the second RoE device at the first RoE device. The first parameter and the second parameter may be set to have a same first value. In accordance with an exemplary embodiment, the second RoE device may calculate a first difference between the first timestamp and a second timestamp, as shown in block 504. In an embodiment, a time when the first message arrives at the second RoE device may be indicated by the second timestamp.

In accordance with an exemplary embodiment, when a gap between the first difference and the first value is equal to or larger than a threshold, the second RoE device may transmit a candidate value (e.g., D-b’ as described with respect to Fig. 3) of the first parameter to the first RoE device to adjust the first parameter and the second parameter from the first value to a second value, as shown in block 506. In an embodiment, the second RoE device may receive the second value of the first parameter and the second parameter from the first RoE device, as shown in block 508.

In accordance with an exemplary embodiment, the second value of the first parameter and the second parameter may be equal to a larger of the candidate value of the first parameter transmitted to the first RoE device and a candidate value (e.g., D-a or D-a’ as described with respect to Fig. 3) of the second parameter determined by the first RoE device.

In accordance with an exemplary embodiment, the second RoE device may transmit a second message with a third timestamp to the first RoE device. In an embodiment, the second message may include the first parameter and the second parameter, and the first parameter and the second parameter may be set to have the same first value.

In accordance with an exemplary embodiment, the second RoE device may determine the presentation time of the RoE data from the first RoE device at the second RoE device, according to the first parameter. Alternatively or additionally, the second RoE device may determine the presentation time of the RoE data from the second RoE device at the first RoE device, according to the second parameter.

In accordance with an exemplary embodiment, the second RoE device may determine delay time of RoE transmission from the second RoE device to the first RoE device, according to the second parameter. Alternatively or additionally, the second RoE device may determine delay time of RoE transmission from the first RoE device to the second RoE device, according to the first parameter.

It can be appreciated that the first RoE device as described with respect to Fig. 4 may also be configured to perform the method 500 as described with respect to Fig. 5, according to different application scenarios and service requirements. Similarly, it can be appreciated that the second RoE device as described with respect to Fig. 5 may also be configured to perform the method 400 as described with respect to Fig. 4, according to different application scenarios and service requirements.

The various blocks shown in Figs. 4-5 may be viewed as method steps, and/or as operations that result from operation of computer program code, and/or as a plurality of coupled logic circuit elements constructed to carry out the associated function (s) . The schematic flow chart diagrams described above are generally set forth as logical flow chart diagrams. As such, the depicted order and labeled steps are indicative of specific embodiments of the presented methods. Other steps and methods may be conceived that are equivalent in function, logic, or effect to one or more steps, or portions thereof, of the illustrated methods. Additionally, the order in which a particular method occurs may or may not strictly adhere to the order of the corresponding steps shown.

Fig. 6 is a block diagram illustrating an apparatus 600 according to various embodiments of the present disclosure. As shown in Fig. 6, the apparatus 600 may comprise one or more processors such as processor 601 and one or more memories such as memory 602 storing computer program codes 603. The memory 602 may be non-transitory machine/processor/computer readable storage medium. In accordance with some exemplary embodiments, the apparatus 600 may be implemented as an integrated circuit chip or module that can be plugged or installed into a first RoE device as described with respect to Fig. 4, or a second RoE device as described with respect to Fig. 5. In such cases, the apparatus 600 may be implemented as a first RoE device as described with respect to Fig. 4, or a second RoE device as described with respect to Fig. 5.

In some implementations, the one or more memories 602 and the computer program codes 603 may be configured to, with the one or more processors 601, cause the apparatus 600 at least to perform any operation of the method as described in connection with Fig. 4. In other implementations, the one or more memories 602 and the computer program codes 603 may be configured to, with the one or more processors 601, cause the apparatus 600 at least to perform any operation of the method as described in connection with Fig. 5. Alternatively or additionally, the one or more memories 602 and the computer program codes 603 may be configured to, with the one or more processors 601, cause the apparatus 600 at least to perform more or less operations to implement the proposed methods according to the exemplary embodiments of the present disclosure.

In general, the various exemplary embodiments may be implemented in hardware or special purpose chips, circuits, software, logic or any combination thereof. For example, some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device, although the disclosure is not limited thereto. While various aspects of the exemplary embodiments of this disclosure may be illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

As such, it should be appreciated that at least some aspects of the exemplary embodiments of the disclosure may be practiced in various components such as integrated circuit chips and modules. It should thus be appreciated that the exemplary embodiments of this disclosure may be realized in an apparatus that is embodied as an integrated circuit, where the integrated circuit may comprise circuitry (as well as possibly firmware) for embodying at least one or more of a data processor, a digital signal processor, baseband circuitry and radio frequency circuitry that are configurable so as to operate in accordance with the exemplary embodiments of this disclosure.

It should be appreciated that at least some aspects of the exemplary embodiments of the disclosure may be embodied in computer-executable instructions, such as in one or more program modules, executed by one or more computers or other devices. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types when executed by a processor in a computer or other device. The computer executable instructions may be stored on a computer readable medium such as a hard disk, optical disk, removable storage media, solid state memory, random access memory (RAM) , etc. As will be appreciated by one of skill in the art, the function of the program modules may be combined or distributed as desired in various embodiments. In addition, the function may be embodied in whole or partly in firmware or hardware equivalents such as integrated circuits, field programmable gate arrays (FPGA) , and the like.

The present disclosure includes any novel feature or combination of features disclosed herein either explicitly or any generalization thereof. Various modifications and adaptations to the foregoing exemplary embodiments of this disclosure may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings. However, any and all modifications will still fall within the scope of the non-limiting and exemplary embodiments of this disclosure.

Claims

A method (400) performed by a first radio over Ethernet, RoE, device, comprising:

transmitting (402) a first message with a first timestamp to a second RoE device, wherein the first message includes a first parameter and a second parameter, the first parameter is related to presentation time of RoE data from the first RoE device at the second RoE device, the second parameter is related to presentation time of RoE data from the second RoE device at the first RoE device, and the first parameter and the second parameter are set to have a same first value;

wherein a time when the first message arrives at the second RoE device is indicated by a second timestamp which has a first difference from the first timestamp, and when a gap between the first difference and the first value is equal to or larger than a threshold, the method further comprises:

receiving (404) a candidate value of the first parameter from the second RoE device;

adjusting (406) the first parameter and the second parameter from the first value to a second value, according to the candidate value of the first parameter received from the second RoE device and a candidate value of the second parameter determined by the first RoE device; and

transmitting (408) the second value of the first parameter and the second parameter to the second RoE device.
The method according to claim 1, wherein the candidate value of the first parameter is equal to the first difference between the first timestamp and the second timestamp.
The method according to claim 1 or 2, wherein the second value of the first parameter and the second parameter is equal to a larger of the candidate value of the first parameter and the candidate value of the second parameter.
The method according to any of claims 1-3, wherein when the first RoE device does not receive a second message with a third timestamp from the second RoE device, the candidate value of the second parameter determined by the first RoE device is equal to the first value.
The method according to any of claims 1-4, further comprising:

receiving a second message with a third timestamp from the second RoE device, wherein the second message includes the first parameter and the second parameter, and the first parameter and the second parameter are set to have the same first value; and

calculating a second difference between the third timestamp and a fourth timestamp, wherein a time when the second message arrives at the first RoE device is indicated by the fourth timestamp.
The method according to claim 5, wherein the candidate value of the second parameter is determined by the first RoE device according to the second difference between the third timestamp and the fourth timestamp.
The method according to claim 5 or 6, wherein when the second difference between the third timestamp and the fourth timestamp is different from the first value, the candidate value of the second parameter determined by the first RoE device is equal to the second difference between the third timestamp and the fourth timestamp.
The method according to any of claims 1-7, further comprising:

determining the presentation time of the RoE data from the second RoE device at the first RoE device, according to the second parameter.
The method according to any of claims 1-8, further comprises:

determining delay time of RoE transmission from the first RoE device to the second RoE device, according to the first parameter.
A first radio over Ethernet, RoE, device (600) , comprising:

one or more processors (601) ; and

one or more memories (602) storing computer program codes (603) ,

the one or more memories (602) and the computer program codes (603) configured to, with the one or more processors (601) , cause the first RoE device (600) at least to:

transmit a first message with a first timestamp to a second RoE device, wherein the first message includes a first parameter and a second parameter, the first parameter is related to presentation time of RoE data from the first RoE device at the second RoE device, the second parameter is related to presentation time of RoE data from the second RoE device at the first RoE device, and the first parameter and the second parameter are set to have a same first value;

wherein a time when the first message arrives at the second RoE device is indicated by a second timestamp which has a first difference from the first timestamp, and when a gap between the first difference and the first value is equal to or larger than a threshold, the method further comprises:

receive a candidate value of the first parameter from the second RoE device;

adjust the first parameter and the second parameter from the first value to a second value, according to the candidate value of the first parameter received from the second RoE device and a candidate value of the second parameter determined by the first RoE device; and

transmit the second value of the first parameter and the second parameter to the second RoE device.
The first RoE device according to claim 10, wherein the one or more memories and the computer program codes are configured to, with the one or more processors, cause the first RoE device to perform the method according to any one of claims 2-9.
A computer-readable medium storing computer program codes (603) which, when executed on a computer, cause the computer to perform any step of the method according to any one of claims 1-9.
A method (500) performed by a second radio over Ethernet, RoE, device, comprising:

receiving (502) a first message with a first timestamp from a first RoE device, wherein the first message includes a first parameter and a second parameter, the first parameter is related to presentation time of RoE data from the first RoE device at the second RoE device, the second parameter is related to presentation time of RoE data from the second RoE device at the first RoE device, and the first parameter and the second parameter are set to have a same first value;

calculating (504) a first difference between the first timestamp and a second timestamp, wherein a time when the first message arrives at the second RoE device is indicated by the second timestamp; and

wherein when a gap between the first difference and the first value is equal to or larger than a threshold, the method further comprises:

transmitting (506) a candidate value of the first parameter to the first RoE device to adjust the first parameter and the second parameter from the first value to a second value; and

receiving (508) the second value of the first parameter and the second parameter from the first RoE device.
The method according to claim 13, wherein the candidate value of the first parameter is equal to the first difference between the first timestamp and the second timestamp.
The method according to claim 13 or 14, wherein the second value of the first parameter and the second parameter is equal to a larger of the candidate value of the first parameter transmitted to the first RoE device and a candidate value of the second parameter determined by the first RoE device.
The method according to any of claims 13-15, wherein when the second RoE device does not transmit a second message with a third timestamp to the first RoE device, the candidate value of the second parameter determined by the first RoE device is equal to the first value.
The method according to any of claims 13-16, further comprising:

transmitting a second message with a third timestamp to the first RoE device, wherein the second message includes the first parameter and the second parameter, and the first parameter and the second parameter are set to have the same first value.
The method according to claim 17, wherein a time when the second message arrives at the first RoE device is indicated by a fourth timestamp which has a second difference from the third timestamp, and wherein the candidate value of the second parameter is determined by the first RoE device according to the second difference between the third timestamp and the fourth timestamp.
The method according to claim 17 or 18, wherein when the second difference between the third timestamp and the fourth timestamp is different from the first value, the candidate value of the second parameter determined by the first RoE device is equal to the second difference between the third timestamp and the fourth timestamp.
The method according to any of claims 13-19, further comprising:

determining the presentation time of the RoE data from the first RoE device at the second RoE device, according to the first parameter.
The method according to any of claims 13-20, further comprising:

determining delay time of RoE transmission from the second RoE device to the first RoE device, according to the second parameter.
A second radio over Ethernet, RoE, device (600) , comprising:

one or more processors (601) ; and

one or more memories (602) storing computer program codes (603) ,

the one or more memories (602) and the computer program codes (603) configured to, with the one or more processors (601) , cause the second RoE device (600) at least to:

receive a first message with a first timestamp from a first RoE device, wherein the first message includes a first parameter and a second parameter, the first parameter is related to presentation time of RoE data from the first RoE device at the second RoE device, the second parameter is related to presentation time of RoE data from the second RoE device at the first RoE device, and the first parameter and the second parameter are set to have a same first value;

calculate a first difference between the first timestamp and a second timestamp, wherein a time when the first message arrives at the second RoE device is indicated by the second timestamp; and

wherein when a gap between the first difference and the first value is equal to or larger than a threshold, the method further comprises:

transmit a candidate value of the first parameter to the first RoE device to adjust the first parameter and the second parameter from the first value to a second value; and

receive the second value of the first parameter and the second parameter from the first RoE device.
The second RoE device according to claim 22, wherein the one or more memories and the computer program codes are configured to, with the one or more processors, cause the second RoE device to perform the method according to any one of claims 14-21.
A computer-readable medium storing computer program codes (603) which, when executed on a computer, cause the computer to perform any step of the method according to any one of claims 13-21.