WO2020256602A1

WO2020256602A1 - Delivery of packet data

Info

Publication number: WO2020256602A1
Application number: PCT/SE2019/050572
Authority: WO
Inventors: Annikki Welin; Mats Forsman; Tomas Thyni
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2019-06-17
Filing date: 2019-06-17
Publication date: 2020-12-24

Abstract

The present disclosure relates to methods of controlling delivery of data packets to a final destination node (12), and devices (10a, 11a) performing the method.In an aspect, a method of a receiving node (11a) of controlling delivery of a data packet to a final destination node (12) is provided. The method comprises receiving (S101) the data packet comprising an indicator of a time period available for delivering the data packet to the final destination node (12), determining (S102) remaining time required for delivering the data packet to the destination node (12), determining (S103) whether or not there is sufficient time remaining for delivering the data packet to the destination node (12), and if so delivering (S104) the data packet to the destination node (12).

Description

DELIVERY OF PACKET DATA

TECHNICAL FIELD

[0001] The present disclosure relates to methods of controlling delivery of data packets to a final destination node, and devices performing the method.

BACKGROUND

[0002] Fronthaul structures for mobile networks are based on the transport of sampled radio signals from/to baseband (BB) processing units such as for instance radio base stations (RBSs) to/from remote radio heads (RRHs), where a protocol commonly being used in the communication between an RBS and an RRH is the Common Public Radio Interface (CPRI) or the evolved CPRI (eCPRI).

[0003] The CPRI defines an interface between REC (Radio Equipment Control) and

RE (Radio Equipment). For instance, the REC maybe an RBS located on the ground while the RE may be a radio transceiver located in a tower and connected to the RBS via a fibre optic link.

[0004] Large amounts of data packets having high bit rates are transported in these front haul links. These data packets are sensitive to delay and long propagation times.

SUMMARY

[0005] One object is to solve, or at least mitigate, this problem in the art and thus to provide an improved method of controlling delivery of one or more data packets to a final destination node.

[0006] This object is attained in a first aspect by a method of a receiving node of controlling delivery of a data packet to a final destination node. The method comprises receiving the data packet comprising an indicator of a time period available for delivering the data packet to the final destination node, determining remaining time required for delivering the data packet to the destination node, determining whether or not there is sufficient time remaining for delivering the data packet to the destination node, and if so delivering the data packet to the destination node.

[0007] This object is attained in a second aspect by a receiving node configured to control delivery of a data packet to a final destination node. The receiving node comprises a processing unit and a memory, said memory containing instructions executable by said processing unit, whereby the receiving node is operative to receive the data packet comprising an indicator of a time period available for delivering the data packet to the final destination node, determine remaining time required for delivering the data packet to the destination node, determine whether or not there is sufficient time remaining for delivering the data packet to the destination node, and if so to deliver the data packet to the destination node.

[0008] This object is attained in a third aspect by a method of a transmitting node of facilitating delivery of a data packet to a final destination node. The method comprises sending, to a receiving node configured to forward the data packet towards the final destination node, the data packet comprising an indicator of a time period available for delivering the data packet to the final destination node.

[0009] This object is attained in a fourth aspect by a transmitting node configured to facilitate delivery of a data packet to a final destination node. The transmitting node comprises a processing unit and a memory, said memory containing instructions executable by said processing unit, whereby the transmitting node is operative to send, to a receiving node configured to forward the data packet towards the final destination node, the data packet comprising an indicator of a time period available for delivering the data packet to the final destination node.

[0010] In an application of a fronthaul structure in a mobile network, it maybe important that data packets to be used in the application do not arrive too late. That is; it is important that delivered data packets arrive on time. Therefore, the propagation time of a data packet should not exceed a given maximum value (which itself may depend on the particular application). This is solved in an embodiment by a

transmitting node determining a maximal time period that is allowed to elapse before a data packet to be delivered from the transmitting node to a final destination node has arrived too late. A receiving node receiving the data packet and forwarding the packet to the final destination node may discard the packet if it cannot be delivered on time as stipulated by the set maximal time period.

[0011] In an embodiment, the data packet is scheduled for delivery to the

destination node, wherein the delivering of the data packet to the destination node further comprises delivering the data packet to the destination node in accordance with said scheduling.

[0012] In an embodiment, a first data packet having less time remaining than a second data packet is scheduled to be delivered before the second data packet. [0013] In an embodiment, the indicator of a time period available for delivering the data packet to a final destination node is an indicator of the time period available after the data packet has been transferred from a transmitting node from which the data packet is received, wherein a propagation time for the data packet from the data packet transmitting node to the receiving node is determined.

[0014] In an embodiment, the indicator of a time period available for delivering the data packet to a final destination node is an indicator of the time period available after the data packet has been transferred from the transmitting node.

[0015] In an embodiment the data packet is further configured to comprise a current point time when the data packet is being transmitted.

[0016] Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/an/the element, apparatus, component, means, step, etc." are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Aspects and embodiments are now described, by way of example, with refer ence to the accompanying drawings, in which:

[0018] Figure 1 illustrates a fronthaul structure in a mobile network in which embodiments may be implemented;

[0019] Figure 2 illustrates a first RU determining that a data packet received over an air interface to be delivered to an RBS needs to be delivered to the RBS within TA = 75 ps according to an embodiment;

[0020] Figure 3 shows a flowchart illustrating a method of a receiving node of controlling delivery of a data packet to a final destination node according to an embodiment;

[0021] Figure 4 shows a flowchart illustrating a method of a receiving node of controlling delivery of a data packet to a final destination node according to another embodiment; [0022] Figure 5 shows a flowchart illustrating a method of a receiving node of controlling delivery of a data packet to a final destination node according to a further embodiment;

[0023] Figure 6 illustrates a receiving node according to an embodiment; and

[0024] Figure 7 illustrates a transmitting node according to an embodiment.

DETAILED DESCRIPTION

[0025] The aspects of the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which certain

embodiments of the invention are shown.

[0026] These aspects may, however, be embodied in many different forms and should not be construed as limiting; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and to fully convey the scope of all aspects of invention to those skilled in the art. Like numbers refer to like elements throughout the description.

[0027] Figure 1 illustrates a fronthaul structure in a mobile network in which embodiments maybe implemented. The fronthaul structure comprises a plurality of remote radio heads (RRHs), commonly referred to as radio units (RUs) loa-d, and a plurality of switches lia-c connecting the RUs loa-d to an RBS 12.

[0028] In the fronthaul structure of Figure 1, it is important that data packets to be used in an application - for instance at the RBS 12 or at any one of the RUs loa-d or mobile terminals (not shown) served by the RUs - do not arrive too late. That is; it is important that data packets delivered by the RUs loa-d, via the switches lia-c, to the RBS 12 arrive on time (and vice versa). Therefore, the propagation time of a data packet transmitted between the RUs loa-d and the RBS 12 cannot exceed a given maximum value (which itself depends on the particular application). As can be concluded, any congestion in the path 13 between the RUs loa-d and the RBS 12 may cause failure in an application making use of the data packets travelling along the path.

[0029] This is solved in an embodiment by each RU loa-d determining a maximal time period TA that is allowed to elapse before a data packet to be delivered from the RU to the RBS 12 is considered to have arrived too late at the RBS 12. For instance, data packets may comprise IQ modulated (“in-phase and quadrature”) data to be used in an application at the RBS 12, which is able to compensate for delays in the IQ data up to a certain degree. However, if a maximal delay is exceeded, the RBSs 12 can no longer compensate for the delay, and one or more delayed data packets cannot be used in the application.

[0030] Figure 2 illustrates the first RU 10a determining that a data packet received over an air interface to be delivered to the RBS 12 needs to be delivered to the RBS 12 within T_A = 75 ps. The RU may for instance identify a radio bearer type which may indicate an allowed latency of the data packets.

[0031] Alternatively, the data packet may comprise a header identifying which type of application the data packet is applicable to, and the first RU 10a may store a look-up table where application identifiers are mapped to a particular value of a time period within which the data packet should be delivered to the RBS 12.

[0032] Reference will further be made to Figure 3 showing a flowchart illustrating a method of a receiving node of controlling delivery of a data packet to a final destination node according to an embodiment, where the receiving node is illustrated by the first switch 11a and the final destination node is illustrated by the RBS 12.

[0033] The data packet, and an indicator of the time period T_A that is available for delivering the data packet to the RBS 12 after having been transferred from the first RU 10a, is the sent from the first RU 10a towards the RBS 12 along the path 13 and is initially received by first switch 11a in step S101.

[0034] Now, in an embodiment the first switch 11a may measure (or in other ways acquire information specifying) propagation time T_pi of the data packet from the first RU 10a to the first switch 11a, which in this particular example is assumed to amount to T_PI = 20 ps.

[0035] In an alternative embodiment (illustrated in Figure 3), the first RU 10a may measure, or have access to, the propagation time T_pi of the data packet from the first RU 10a to the first switch 11a. If so, the first RU 10a will send the data packet in step S101 along with an indicator of the time period T_A’ that is available for delivering the data packet to the RBS 12 after having been transferred from the first switch 11a, thereby taking into account the propagation time Tpi already at the first RU 10a: T_A‘ = T_A - Tpi. This embodiment has the advantage that the first switch 11a is not burdened with the task of determining the propagation time Tpi. [0036] Either way, the first switch 11a determines in step S102 remaining time T_p2 required for delivering the data packet to the RBS 12. In this exemplifying embodiment, it is assumed that the first switch 11a“pings” the RBS 12 and concludes that the propagation time T_p2 from the first switch 11a to the RBS 12 is T_p2 = 45 ps. Other measurement methods may be envisaged, such as utilization of a Two-Way Active Measurement Protocol (TWAMP).

[0037] Hence, at this stage the first switch 11a determines whether or not there is sufficient time TR remaining for delivering the data packet to the RBS 12, as illustrated in step S103:

TR = T._\ - T_pi - T_P2 = TA’ - T_p2 = 75 - 20 - 45 = 10 ps.

[0038] That is, as long as TR ³ o, there is sufficient time remaining for delivering the received data packet to the RBS 12. The first switch 11a will thus deliver the data packet to the RBS 12 by forwarding the data packet to the second switch 11a in step S104, which in its turn will perform a similar computation as that just performed by the first switch 11a in order to conclude whether there is sufficient time TR remaining or not for the second switch 11b to deliver the data packet to the RBS 12.

[0039] For instance, there may be an unexpected delay between the first switch 11a and the second switch 11b (which was not foreseen by the first switch 11a), in which case the second switch 11b may conclude that there is not enough time TR remaining for data packet delivery and thus discard the received data packet.

[0040] If the computation above would result in TR < o at the first switch 11a, there is not sufficient time remaining for the data packet to be delivered to the RBS 12 in time, and the first switch 11a would thus discard the data packet in step S105. This is advantageous, since outdated packets are not sent unnecessarily along the path 13; any data packets sent will consume bandwidth, which preferably should be avoided given that the RBS 12 cannot make use of data packets too late.

[0041] Figure 4 shows a flowchart illustrating a method of a receiving node of controlling delivery of a data packet to a final destination node according to another embodiment. A difference between the embodiment of Figure 4 and that of Figure 3 is that, as previously mentioned, the first switch 11a measures propagation time T_pi of the data packet from the first RU 10a to the first switch 11a, which in this particular example is assumed to amount to T_pi = 20 ps. [0042] Further, in step S101, an indicator of the time period TA that is allowed to elapse before the data packet must be delivered to the RBS 12 after having been transferred from the first RU 10a is received.

[0043] In practice, the first switch 11a will receive a large number of packets from the first RU 10a, each comprising an indicator of the time period TA’ that is allowed to elapse before the data packet must be delivered to the RBS 12 (or alternatively TA).

[0044] Hence, the first switch 11a must determine whether or not these data packets should be delivered to the RBS 12.

[0045] In an embodiment, the packets received at the first switch 11a (and at the second switch 11b and third switch 11c) is scheduled for delivery towards the RBS 12.

[0046] This embodiment will be described with reference to Figure 5. The first RU 10a will send the data packet in step S101 along with an indicator of the time period TA’ that is allowed to elapse before the data packet must be delivered to the RBS 12 after having been transferred from the first switch 11a. Thus, as in Figure 3, the first RU 10a considers the propagation time T_pi resulting in TA‘ = TA - T_pi. An indicator TA’ is included with each data packet, even though the time period TA’ that is allowed to elapse before a data packet must be delivered to the RBS 12 may be the same for different packets.

[0047] Thereafter, in step S102, the first switch 11a determines remaining time T_p2 required for delivering each data packet to the RBS 12. In this example, T_p2 is assumed to be the same for all data packets, even though it maybe envisaged that this differs for different data packets.

[0048] Again, it is assumed that the first switch 11a“pings” the RBS 12 and concludes that the propagation time T_p2 from the first switch 11a to the RBS 12 is T_p2 = 45 ps.

[0049] Hence, at this stage the first switch 11a determines whether or not there is sufficient time TR remaining for delivering the data packet to the RBS 12, as illustrated in step S103:

1 R = 1A 1 PI— i P2 = 1A— i P2.

[0050] However, in this exemplifying embodiment, several data packets are received each potentially having a different time period TA’ available for delivering the data packet to the RBS 12. [0051] Table 1 in the below illustrates different data packets and the time period available for delivery of each packet to the RBS 12 from the first switch 11a before the data packets are received too late.

Table 1. Received data packets and their delivery timing.

[0052] Hence, based on the information of Table 1, the first switch 11a will determine in step S103 whether or not there is sufficient time remaining for delivering the received data packets to the RBS 12:

TR_I = 60 - 45 = 15 ps,

TR₂ = 75 - 45 = 30 ps,

TR₃ = 50 - 45 = 5 s,

TR₄ = 60 - 45 = 15 ps, and TR_S = 40 - 45 = -5 PS.

[0053] As can be concluded, for data packets no. 1-4 there is sufficient time remaining for the data packets to be delivered to the RBS 12 from the first switch 11a. However, data packet no. 5 will be discarded in step S105.

[0054] As further can be concluded, the margin for successful delivery is smallest for packet no. 3. The data packets will thus be scheduled in step Si03a as shown in Table 2 below, where the first-listed packet is scheduled to be delivered first and the last-listed packet is scheduled to be delivered last.

Table 2. Scheduled data packets.

[0055] The first switch 11a will thus deliver the data packet to the RBS 12 by forwarding the data packet to the second switch 11a in step S104 based in the performed scheduling, i.e. in the order listed in Table 2.

[0056] Advantageously, with the scheduling, data packets for which the delivery is urgent is scheduled to be delivered first, while data packets with a greater delivery margin are less prioritized during the scheduling.

[0057] In an embodiment, the first RU 10a includes with the data packet and the indicator of the time period T_A available for delivering the data packet to the RBS 12 after the data packet has been transferred from the first RU 10a a time stamp indicating the current time at the first RU 10a when transferring the data packet. For instance, the time stamp maybe the current Coordinated Universal Time (UTC).

[0058] This is advantageous since the first switch 11a then can determine the propagation time of the data packet from the first RU 10a to the first switch 11a by deriving the time of day upon receiving the data packet and comprising the derived time from the received current time.

[0059] Figure 6 illustrates a receiving node 11a, e.g. the first switch, according to an embodiment. The steps of the method performed by the receiving node 11a, being embodied e.g. in the form of a computer or server, of controlling delivery of a data packet to a final destination node according to embodiments are in practice performed by a processing unit 20 embodied in the form of one or more microprocessors arranged to execute a computer program 21 downloaded to a suitable storage volatile medium 22 associated with the microprocessor, such as a Random Access Memory (RAM), or a non-volatile storage medium such as a Flash memory or a hard disk drive. The processing unit 20 is arranged to cause the receiving node 11a to carry out the method according to embodiments when the appropriate computer program 21 comprising computer-executable instructions is downloaded to the storage medium 22 and executed by the processing unit 20. The storage medium 22 may also be a computer program product comprising the computer program 21. Alternatively, the computer program 21 maybe transferred to the storage medium 22 by means of a suitable computer program product, such as a Digital Versatile Disc (DVD) or a memory stick.

As a further alternative, the computer program 21 maybe downloaded to the storage medium 22 over a network. The processing unit 20 may alternatively be embodied in the form of a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a complex programmable logic device (CPLD), etc.

[0060] Figure 7 illustrates a transmitting node 10a, e.g. the first RU, according to an embodiment. The steps of the method performed by the transmitting node 10a, being embodied e.g. in the form of a computer or server, of facilitating delivery of a data packet to a final destination node according to embodiments are in practice performed by a processing unit 30 embodied in the form of one or more microprocessors arranged to execute a computer program 31 downloaded to a suitable storage volatile medium 32 associated with the microprocessor, such as a RAM, or a non-volatile storage medium such as a Flash memory or a hard disk drive. The processing unit 30 is arranged to cause the transmitting node 10a to carry out the method according to embodiments when the appropriate computer program 31 comprising computer-executable instructions is downloaded to the storage medium 32 and executed by the processing unit 30. The storage medium 32 may also be a computer program product comprising the computer program 31. Alternatively, the computer program 31 maybe transferred to the storage medium 32 by means of a suitable computer program product, such as a DVD or a memory stick. As a further alternative, the computer program 31 maybe downloaded to the storage medium 32 over a network. The processing unit 30 may alternatively be embodied in the form of a DSP, an ASIC, an FPGA, a CPLD, etc.

[0061] The aspects of the present disclosure have mainly been described above with reference to a few embodiments and examples thereof. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the invention, as defined by the appended patent claims.

[0062] Thus, while various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.

Claims

1. A method of a receiving node (na) of controlling delivery of a data packet to a final destination node (12), comprising:

receiving (S101) the data packet comprising an indicator of a time period available for delivering the data packet to the final destination node (12);

determining (S102) remaining time required for delivering the data packet to the destination node (12);

determining (S103) whether or not there is sufficient time remaining for delivering the data packet to the destination node (12); and if so

delivering (S104) the data packet to the destination node (12).

2. The method of claim 1, wherein in case it is determined (S103) that there is not sufficient time remaining for delivering the data packet to the destination node (12): discarding (S105) the received data packet.

3. The method of claim 1, further comprising:

scheduling (Si03a) the data packet for delivery to the destination node (12);

wherein the delivering (S104) of the data packet to the destination node (12) further comprises:

delivering the data packet to the destination node (12) in accordance with said scheduling.

4. The method of claim 3, wherein a first data packet having less time remaining than a second data packet is scheduled to be delivered before the second data packet.

5. The method of any one of the preceding claims, wherein the indicator of a time period available for delivering the data packet to a final destination node (12) is an indicator of the time period available after the data packet has been transferred from a transmitting node (10a) from which the data packet is received, further comprising: determining (Sioia) a propagation time for the data packet from the data packet transmitting node (10a) to the receiving node (11a).

6. A method of a transmitting node (10a) of facilitating delivery of a data packet to a final destination node (12), comprising:

sending (S101), to a receiving node (11a) configured to forward the data packet towards the final destination node (12), the data packet comprising an indicator of a time period available for delivering the data packet to the final destination node (12).

7. The method of claim 6, wherein the indicator of a time period available for delivering the data packet to a final destination node (12) is an indicator of the time period available after the data packet has been transferred from the transmitting node (10a).

8. The method according to any one of the preceding claims, the data packet further being configured to comprise a current point time when the data packet is being transmitted.

9. A computer program (21) comprising computer-executable instructions for causing a receiving node (11a) to perform steps recited in any one of claims 1-5 and 8 when the computer-executable instructions are executed on a processing unit (20) included in the receiving node (11a).

10. A computer program product comprising a computer readable medium (22), the computer readable medium having the computer program (21) according to claim 9 embodied thereon.

11. A computer program (31) comprising computer-executable instructions for causing a transmitting node (10a) to perform steps recited in any one of claims 6-8 when the computer-executable instructions are executed on a processing unit (30) included in the transmitting node (10a).

12. A computer program product comprising a computer readable medium (32), the computer readable medium having the computer program (31) according to claim 11 embodied thereon.

13. A receiving node (11a) configured to control delivery of a data packet to a final destination node (12), the receiving node (11a) comprising a processing unit (20) and a memory (22), said memory containing instructions (21) executable by said processing unit (20), whereby the receiving node (11a) is operative to:

receive the data packet comprising an indicator of a time period available for delivering the data packet to the final destination node (12);

determine remaining time required for delivering the data packet to the destination node (12);

determine whether or not there is sufficient time remaining for delivering the data packet to the destination node (12); and if so to

deliver the data packet to the destination node (12).

14. The receiving node (11a) of claim 13, further being operative to, in case it is determined that there is not sufficient time remaining for delivering the data packet to the destination node (12):

discard the received data packet.

15. The receiving node (11a) of claim 13, further being operative to:

schedule the data packet for delivery to the destination node (12); and further being operative to, when delivering the data packet to the destination node (12):

deliver the data packet to the destination node (12) in accordance with said scheduling.

16. The receiving node (11a) of claim 15, further being operative to schedule delivery of a first data packet having less time remaining than a second data packet, before the second data packet.

17. The receiving node (11a) of any one of claims 13-16, wherein the indicator of a time period available for delivering the data packet to a final destination node (12) is an indicator of the time period available after the data packet has been transferred from a transmitting node (10a) from which the data packet is received, the receiving node (11a) further being operative to:

determine a propagation time for the data packet from the data packet

transmitting node (10a) to the receiving node (11a).

18. A transmitting node (10a) configured to facilitate delivery of a data packet to a final destination node (12), the transmitting node (10a) comprising a processing unit (30) and a memory (32), said memory containing instructions (31) executable by said processing unit (30), whereby the transmitting node (10a) is operative to:

send (S101), to a receiving node (11a) configured to forward the data packet towards the final destination node (12), the data packet comprising an indicator of a time period available for delivering the data packet to the final destination node (12).

19. The transmitting node (10a) of claim 18, wherein the indicator of a time period available for delivering the data packet to a final destination node (12) is an indicator of the time period available after the data packet has been transferred from the

transmitting node (10a).

20. The transmitting node (10a) according to any one of claims 18 or 19, the data packet further being configured to comprise a current point time when the data packet is being transmitted.