CN116488768A

CN116488768A - Overhead information transmission method, communication device and system

Info

Publication number: CN116488768A
Application number: CN202210045058.2A
Authority: CN
Inventors: 傅相如; 苏伟; 刘翔
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2022-01-14
Filing date: 2022-01-14
Publication date: 2023-07-25
Also published as: WO2023134513A1

Abstract

The application discloses an overhead information transmission method, a communication device and a system, which relate to the field of optical communication and are used for reducing transmission delay of overhead information. The overhead information transmission method comprises the following steps: the method comprises the steps that first Optical Transport Network (OTN) equipment obtains overhead information, wherein the overhead information is used for indicating position information of a first Payload Block (PB) and service identifiers corresponding to Optical Service Unit (OSU) frames borne by the first PB; the first OTN device maps the overhead information into a payload region of the OTN frame; and sending the OTN frame.

Description

Overhead information transmission method, communication device and system

Technical Field

The present disclosure relates to the field of optical communications, and in particular, to an Overhead (OH) information transmission method, a communication device, and a system.

Background

The optical transport network (optical transport network, OTN) is used as a core technology of the next generation transport network, and can realize the bearing and flexible scheduling of large-particle service (bit rate is 1G-100G), but has the problems of low bearing efficiency, large time delay and the like when bearing small-particle service (bit rate is 2M-1.5G). Therefore, based on OTN derived optical service unit (optical service unit, OSU) frames, the service with any bit rate of 2M-100G can be carried, so that the carrying and flexible scheduling of small-particle service and large-particle service are realized.

In each transport period (transport period), a fixed number and fixed location of Payload Blocks (PB) may be allocated in the optical payload unit (optical payload unit, OPU) payload area of the OTN frame for carrying traffic data of OSU traffic, and overhead is configured in the OPU overhead area to indicate location information (called pattern) of these PB. Since the OPU overhead area is small, the PB location information indicated by a single transmission period is small, which increases the transmission delay of overhead information, resulting in degradation of some performance metrics, such as increasing the delay of service data resolution.

Disclosure of Invention

The embodiment of the application provides an overhead information transmission method, a communication device and a system, which are used for reducing the transmission delay of overhead information.

In order to achieve the above purpose, the embodiments of the present application adopt the following technical solutions.

In a first aspect, an embodiment of the present application provides an overhead information transmission method. The method comprises the following steps: the first OTN equipment acquires overhead information, wherein the overhead information is used for indicating the position information of a first payload block PB and a service identifier corresponding to an OSU frame of an optical service unit borne by the first PB, and the service identifier is carried in the OSU frame or can be carried at a position except the OSU frame in the first PB; the first OTN device maps the overhead information into a payload region of the OTN frame; and sending the OTN frame.

According to the overhead information transmission method, overhead information is transmitted in the payload area of the OTN frame, the overhead information is used for indicating the position information of the first PB in one multiframe and the service identifier corresponding to the OSU frame borne by the first PB, and the payload area is far larger than the overhead area, so that more overhead information can be transmitted in a single transmission period, and the transmission delay of the overhead information is reduced.

In one possible implementation, the mapping of the overhead information into the payload area of the OTN frame by the first OTN device specifically includes: the first OTN device maps the overhead information to the second PB of the payload area of the OTN frame, and the PB used for transmitting the service data in one multiframe may be referred to as a first PB, and the PB used for transmitting the overhead information in one multiframe may be referred to as a second PB, i.e., the second PB and the corresponding first PB are located in the same multiframe (or referred to as a transmission period). At this time, the receiving end can complete the analysis of the service data according to the overhead information in a transmission period, and rapidly analyze the service data.

In one possible implementation, the second PB is a PB located at a start or end position of the multiframe. In one multiframe, the position of the second PB carrying the overhead information may be earlier than the position of the first PB carrying the service data, that is, the first OTN device may send the overhead information carried in the second PB first and then send the service data carried in the first PB, so that the receiving end (the second OTN device later) receives and parses the overhead information first and then parses the service data according to the overhead information. The second PB carrying the overhead information may be located further than the first PB carrying the service data, and the network manager may configure the overhead information to the first OTN device and the second OTN device in advance, and then the first OTN device may send the service data carried in the first PB first and then send the overhead information carried in the second PB, so that after the second OTN device receives the overhead information in the OTN frame, the second OTN device checks the overhead information in the OTN frame according to the overhead information configured by the network manager, so as to determine whether network transmission is normal.

In one possible implementation, the second PB is one or more PB in succession in the multiframe, or the second PB is a plurality of PB evenly distributed in the multiframe. I.e. there are multiple PB's in a multiframe that can be used to transmit overhead information, reducing the transmission delay of overhead information.

In one possible implementation, the first PB comprises a plurality of consecutive PB's, the second PB comprises a first overhead field and one or more first identification fields, the one or more first identification fields corresponding to one or more consecutive PB's in the first PB, respectively; the first overhead field is used for indicating to transmit overhead information corresponding to one or a plurality of continuous PB in the first PB; the position of the first identification field in the second PB is used for indicating the position information of the PB corresponding to the first identification field, and the value of the first identification field is used for indicating the service identification corresponding to the OSU frame carried by the corresponding PB. In particular, the first OTN device may transmit overhead information of all (P) PB's in one multiframe. Can be applied to the following scenes: either before the initial transmission of the traffic data or when the system is idle.

In one possible implementation, the second PB comprises a second overhead field and at least one field set comprising a second identification field, a number field, and a location field; the second overhead field is used for indicating that the service corresponding to the OSU frame carried by the first PB has a change; the second identification field is used for indicating the service identification of the updated service; the quantity field is used for indicating the quantity of PB included in the target PB, wherein the target PB refers to PB of an OSU frame corresponding to the changed OSU service carried in the first PB; the location field is used to indicate location information of the target PB. The method can be applied to the scene that the business corresponding to the OSU frame carried by the first PB has change (such as updating and adding). Updating the service corresponding to the OSU frame of the first PB bearing means that the service corresponding to the OSU frame of the first PB bearing is changed from the first service to the second service; the new increase of the service corresponding to the OSU frame carried by the first PB indicates that the first PB originally does not carry the service and carries the service afterwards.

In one possible implementation, the location information of the target PB is absolute location information of the target PB in a multiframe, such as a sequence number of the target PB in a multiframe.

In one possible implementation, the target PB comprises a plurality of PBs, and the location information of the target PB comprises: absolute position information (e.g., sequence number) of one PB (e.g., the first PB) of the plurality of PBs of the target PB in the multiframe, and relative position information (e.g., sequence number offset) of the other PBs with respect to the one PB.

In one possible implementation, the second PB comprises a third overhead field and at least one third identification field; the third overhead field is used for indicating to delete the service corresponding to the OSU frame carried by the first PB; the third identification field is used to indicate the service identification of the deleted service. The method can be applied to a scene of deleting the service corresponding to the OSU frame borne by the first PB, wherein the service corresponding to the OSU frame borne by the first PB is the original borne service of the first PB and is not borne later.

In a second aspect, an embodiment of the present application provides an overhead information transmission method. The method comprises the following steps: the second OTN equipment receives an OTN frame, wherein a payload area of the OTN frame comprises overhead information, and the overhead information is used for indicating the position information of a first payload block PB and a service identifier corresponding to an optical service unit OSU frame borne by the first PB; the second OTN equipment receives the OSU frame according to the position information, analyzes service data of the service carried by the OSU frame according to the service identification, or checks the overhead information.

Other embodiments and technical effects of the second aspect may refer to the specific embodiments of the first aspect and are not repeated here.

In a third aspect, embodiments of the present application provide a first communication device. The first communication device comprises a processing module and a receiving and transmitting module; the processing module is used for acquiring overhead information, wherein the overhead information is used for indicating the position information of the first payload block PB and a service identifier corresponding to an OSU frame carried by the first PB; the processing module is also used for mapping the overhead information into a payload area of the OTN frame; and the receiving and transmitting module is used for transmitting the OTN frame.

In a possible implementation manner, the processing module is specifically configured to: and mapping the overhead information into a second PB in a payload area of the OTN frame, wherein the second PB and the first PB are positioned in the same multiframe.

Other embodiments and technical effects of the third aspect may refer to the specific embodiments of the first aspect and are not repeated here.

In a fourth aspect, embodiments of the present application provide a second communication device. The second communication device includes: a processing module and a receiving-transmitting module; the receiving and transmitting module is used for receiving an OTN frame, the payload area of the OTN frame comprises overhead information, and the overhead information is used for indicating the position information of a first payload block PB and a service identifier corresponding to an optical service unit OSU frame borne by the first PB; the receiving and transmitting module is also used for receiving the OSU frame according to the position information; and the processing module is used for analyzing service data of the service borne by the OSU frame according to the service identifier or checking the expense information.

Other embodiments and technical effects of the fourth aspect may refer to the specific embodiments of the first aspect and are not repeated here.

In a fifth aspect, embodiments of the present application provide a first communication device. The first communication device comprises a processor and a transceiver for communicating with other communication devices, which when executed by the processor causes the first communication device to perform the method according to the first aspect and any of its embodiments.

In a sixth aspect, embodiments of the present application provide a second communication device. The second communication device comprises a processor and a transceiver for communicating with other communication devices, which when executed by the processor causes the second communication device to perform the method of the second aspect and any of its embodiments.

In a seventh aspect, embodiments of the present application provide a chip system. The system-on-chip includes at least one processor and at least one interface circuit that can read instructions stored in a memory of the OTN device and send the instructions to the at least one processor. The instructions, when executed by at least one processor, cause the OTN device to perform the method of the first aspect and any of its embodiments, or to perform the method of the second aspect and any of its embodiments.

In an eighth aspect, embodiments of the present application provide a communication system. The communication system comprises a first communication device according to the third aspect and any of its embodiments and a second communication device according to the fourth aspect and any of its embodiments, or comprises a first communication device according to the fifth aspect and a second communication device according to the sixth aspect.

In a ninth aspect, embodiments of the present application provide a computer-readable storage medium. The computer readable storage medium comprises instructions which, when executed on an OTN device or communications apparatus, cause the OTN device or communications apparatus to perform the method of the first aspect and any of its embodiments or to perform the method of the second aspect and any of its embodiments.

In a tenth aspect, embodiments of the present application provide a computer program product comprising instructions. The instructions, when executed on an OTN device or communications apparatus, cause the OTN device or communications apparatus to perform the method as described in the first aspect and any of its embodiments or to perform the method as described in the second aspect and any of its embodiments.

The technical effects of any one of the embodiments of the second aspect to the tenth aspect may refer to the technical effects of the first aspect and any one of the embodiments thereof, and are not described herein.

Drawings

FIG. 1 is a schematic diagram of an OTN frame;

FIG. 2 is a schematic diagram of a multi-frame structure;

FIG. 3 is a schematic diagram of an OTN communication system;

FIG. 4 is a schematic diagram of an OTN device;

fig. 5 is a flow chart of an overhead information transmission method according to an embodiment of the present application;

fig. 6 is a schematic diagram of fields included in overhead information according to an embodiment of the present application;

FIG. 7 is a diagram illustrating fields included in another overhead information provided by an embodiment of the present application;

FIG. 8 is a diagram of fields included in yet another overhead information provided by an embodiment of the present application;

fig. 9 is a schematic diagram of fields included in still another overhead information provided in an embodiment of the present application;

fig. 10 is a schematic diagram of a location of a second PB in a multiframe according to an embodiment of the present application;

fig. 11 is a schematic structural diagram of a communication device according to an embodiment of the present application;

fig. 12 is a schematic structural diagram of another second communication device according to an embodiment of the present application;

fig. 13 is a schematic structural diagram of a chip system according to an embodiment of the present application.

Detailed Description

It should be noted that the terms "first," "second," and the like in the embodiments of the present application are used for distinguishing between the same type of feature, and not to be construed as indicating a relative importance, quantity, order, or the like.

The terms "exemplary" or "such as" and the like, as used in connection with embodiments of the present application, are intended to be exemplary, or descriptive. Any embodiment or design described herein as "exemplary" or "for example" should not be construed as preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "such as" is intended to present related concepts in a concrete fashion.

The terms "coupled" and "connected" in connection with embodiments of the present application are to be construed broadly, and may refer, for example, to a physical direct connection, or to an indirect connection via electronic devices, such as, for example, a connection via electrical resistance, inductance, capacitance, or other electronic devices.

The concepts to which the present application relates are first described.

OTN frame: the OTN standard defines different types of OTN frames, for example: optical transport unit k (optical transport unit k, OTUk) frames, variable rate optical transport unit (optical transport unit Cn, OTUCn) frames, flexible OTN interface (flexible OTN interface, flexO) frames, etc. As OTN technology evolves, it is possible to define new types of OTN frames, as well as applicable to the present application. Wherein different values of k in the OTUk frame represent different bit rates supported by the OTUk frame, k=0 represents a rate of 1.25Gbit/s, k=1 represents a rate of 2.5Gbit/s, k=2 represents a rate of 10Gbit/s, k=3 represents a rate of 40Gbit/s, and k=4 represents a rate of 100Gbit/s. The bit rate supported by OTUCn is n×100Gbps (n≡2). k=flex means a rate of n×1.25Gbit/s (n≡2).

The traditional OTN frame adopts a time slot dividing frame structure, the maximum support of 80 time slots is 80 time slots, the minimum granularity of the time slots is 1.25Gbps, which means that the maximum service access number of a single transmission period of the OTN frame is 80, and the OTN frame is suitable for carrying large-particle service. Fig. 1 shows a structure of an OTN frame, including a frame alignment signal (frame alignment signal, FAS), an OTUk overhead area, an OTUk payload area, and a forward error correction (forward error correction, FEC), the OTUk payload area including an optical data unit k (optical data unit k, ODUk) overhead area and an ODUk payload area, the ODUk payload area including an OPUk overhead area and an OPUk payload area, the OUPk payload area carrying traffic data (also referred to as a client (client) signal). An OTUk frame comprises 4 rows by 4080 columns of bytes, and the OTUk overhead area, the ODUk overhead area and the OPUk overhead area are collectively referred to as overhead areas of the OTN frame and are located in columns 1 to 16. The OPUk payload area is called the payload area of the OTN frame and is located in columns 17 to 3824. FAS is located at 1 st row, 1 st byte to 7 th byte of OTUk frame. FEC is located in columns 3825 to 4080.

FAS provides frame synchronization positioning functionality. The overhead area is used to provide network management functions at the optical transport unit level. The ODUk overhead area is used to provide maintenance and operation functions. The OPUk overhead area is used to provide the functionality of client signal adaptation. The payload area (OPUk payload) is used to provide the functionality of the client signal bearer. FEC is used to provide error detection and correction functions. Different values of k in OPUk, ODUk, and OTUk indicate different bit rates supported by the OTUk frame.

Payload and payload area: the payload refers to the bytes in a frame that carry valid data, also referred to as payload bytes. The payload region includes a plurality of payload bytes.

Overhead and overhead area: the overhead and overhead information referred to in this application refer to bytes in a frame that manage payloads, also referred to as overhead bytes, used to ensure correct transmission of the payload data in the payload area. The overhead area includes a plurality of overhead bytes.

PB: a plurality of bytes in succession in the payload area of an OTN frame constitute a PB. For example, one PB may be 192 bytes in succession in the payload area of an OTN frame.

Multiframe (P frame): as shown in fig. 2, consecutive P PB (pb#1-pb#p) of the payload zone in the OTN frame may be referred to as one multiframe. The sequence number of the nth PB in a multiframe is denoted by PB#n, and n is a positive integer. The consecutive P PB's may be PB's located in the payload region of the same OTN frame or may be PB's located in the payload region of different OTN frames. For example, the multiframe of ODU0 frames may include PB in the payload of 1.5 OTN frames, and the multiframe of ODU1 may include PB in the payload of 2 x 1.5 OTN frames.

The transmission period of one multiframe is equal to a PB length divided by a reference rate of PB, for example, a PB length of 192 bytes and a reference rate of PB of 10.4M, and is equal to about 148us, which is (192×8bit)/(10.4 Mbit/s).

The value of P can be obtained by the following equation 1.

Wherein R is _{opu_pld} Representing the OPU payload rate, T _opu Represents OPU frequency offset, R _ref The reference rate of PB is represented, where the OPU payload rate and OPU frequency offset are determined by ODU types including ODUk (k=0/1/2/2 e/3/4/25/25u/50/50 u) frames and ODUflex frames, and table 1 shows the OPU payload rate and OPU frequency offset of the ODUk frames, and the OPU payload rate and OPU frequency offset of the ODUflex frames are not limited. By way of example, table 1 also shows several possible values of the P value of an ODUk frame when the reference rate of PB is 2.6 Mbit/s.

TABLE 1

ODU type	OPU payload rate (kbit/s)	OPU frequency offset (ppm)	P value
				ODU0	1 238 954.310	+/-20	476
ODU1	2 488 320.000	+/-20	956
				ODU2	9 995 276.962	+/-20	3840
ODU2e	10 356 012.658	+/-100	3978
				ODU3	40 150 519.322	+/-20	15426
ODU4	104 355 975.330	+/-20	40096
				ODU25	26 299 210.130	+/-20	10104
ODU25u	24 991 818.732	+/-20	9602
				ODU50	52 598 420.261	+/-20	20209
ODU50u	49 983 637.464	+/-20	19204

Table 2 shows several examples of the number of payload areas of an OTN frame comprised by a multiframe, the P value of the multiframe, and the transmission period of the multiframe. In table 2, N is an integer of 2 or more.

TABLE 2

Optical service unit (optical service unit, OSU): the OSU frame is of a fixed size, including an overhead area and a payload area, and exemplary OSU frames (i.e., one PB) are 192 bytes, with the overhead area accounting for 7 bytes and the payload area accounting for 185 bytes. Wherein the overhead area includes, but is not limited to, the information shown in table 3, and the payload area is used to carry data of OSU traffic.

TABLE 3 Table 3

The OSU technology can divide the payload area in the OTN frame into PB, and the OSU frame of the OSU service can be mapped to one or more PB, so that the high-efficiency bearing of the services with different granularity of 2M-100 Gbps can be realized. As shown in fig. 2, C PB (pb#1-pb#c) in one multiframe (consecutive P PB) can be allocated for transmitting OSU frame, and the bit rate of OSU frame is C times the reference rate. Branch port numbers (tributary port number, TPN) may be added as an identification of OSU traffic when mapping OSU frames to PB. The specific mapping method is not limited, and may be synchronous mapping or asynchronous mapping, for example, a generic mapping procedure (generic mapping procedure, GMP) may be used.

Fig. 3 shows an OTN communication system. The system comprises a plurality of OTN devices 101 (such as A-H), the OTN devices 101 are connected through optical fibers 102, and different topology types such as linear type, annular type and mesh type can be formed according to specific needs. OTN device 101 may also receive or transmit traffic data through customer traffic interface 103. Depending on the actual needs, one OTN device 101 may have different functions. Generally, the OTN device 101 is classified into an optical layer device, an electrical layer device, and an opto-electronic hybrid device. An optical layer device refers to a device capable of processing an optical layer signal, such as: optical amplifiers (optical amplifier, OA), optical add-drop multiplexers (OADM), and the like. OA may also be referred to as optical line amplifiers (optical line amplifier, OLA), and is primarily used to amplify optical signals to support transmission over greater distances while ensuring specific performance of the optical signals. OADM is used to spatially transform an optical signal so that it may be output from different output ports (sometimes also referred to as directions). An electrical layer device refers to a device capable of processing an electrical layer signal, such as: a device capable of processing OTN signals. An opto-electronic hybrid device refers to a device that has the capability to process both optical layer signals and electrical layer signals. It should be noted that, depending on the specific integration requirement, one OTN device 101 may integrate a plurality of different functions. The technical scheme provided by the application is suitable for OTN equipment 101 containing an electric layer function in different forms and integration levels.

It should be noted that, the data frame structure used by the OTN device in the embodiment of the present application is an OTN frame, which is used for carrying various service data and providing rich management and monitoring functions.

Fig. 4 shows the structure of an OTN device 101. The OTN device 101 includes a tributary board 1011, a cross board 1012, a wiring board 1013, an optical layer processing board (not shown in the figure), and a system control and communication-like board 1014. The types and numbers of boards contained in OTN device 101 may vary depending on the particular needs. For example, OTN device 101, which is a core node, has no tributary board 1011. As another example, OTN device 101, which is an edge node, has multiple tributary boards 1011 or no optical cross board 1012. For another example, OTN device 101 supporting only electrical layer functions may not have an optical layer processing board.

The tributary board 1011, the cross board 1012 and the wiring board 1013 are used for processing electrical layer signals in OTN communications. The tributary board 1011 is used to implement reception and transmission of various customer services, such as synchronous digital hierarchy (synchronous digital hierarchy, SDH) service, packet service, ethernet service, and forwarding service.

Further, the board 1011 may be divided into a client side module and a signal processor. The client-side optical module may be an optical transceiver, for receiving and/or transmitting service data. The signal processor is used for realizing the mapping and demapping processing of the business data to the data frame.

The cross board 1012 is used to exchange data frames, and exchange one or more types of data frames is completed.

The wiring board 1013 mainly realizes processing of a line-side data frame. Specifically, the wiring board 1013 may be divided into a line-side optical module and a signal processor. The line-side optical module may be a line-side optical transceiver, and may be configured to receive and/or transmit data frames. The signal processor is used for multiplexing and demultiplexing data frames at the line side or mapping and demapping processing.

The system control and communication class board 304 is used to implement system control. Specifically, information can be collected from different single boards through the back board, or a control instruction can be sent to the corresponding single boards. For example, control board 1011 and wiring board 1013 perform the overhead information transmission methods related to the present application.

It should be noted that, unless specifically stated otherwise, a specific component (e.g., a signal processor) may be one or more, and the present application is not limited. It should also be noted that the present application does not limit the type of boards included in the device and the functional design and number of boards. It should be noted that, in a specific implementation, the two boards may also be designed as one board. In addition, OTN device 101 may also include a backup power supply, a fan for heat dissipation, and the like.

A multiframe may include P PBs, each of which may be configured to carry service data of a service, where the services carried by the respective PBs may be the same or different, and, for example, OSU services, may be identified by the TPN of the OSU service. Before sending service data of each service to the second OTN, the first OTN device may send overhead information of at least one PB in a multiframe to the second OTN device, where the overhead information is used to indicate location information of the at least one PB and a service identifier corresponding to an OSU frame carried by the at least one PB (for example, a TPN of an OSU service). The second OTN equipment can determine what the service carried by at least one PB in one multiframe is according to the overhead information, so that the service data of the service can be correctly analyzed.

In the prior art, overhead information is carried in an OPU overhead area of an OTN frame, and since the OPU overhead area is small, the overhead information transmitted in a single transmission period is small, which increases the transmission delay of the overhead information, resulting in degradation of some performance indexes, such as increasing the delay of service data analysis. To this end, the embodiments of the present application provide an overhead information transmission method, in which an OPU payload area of an OTN frame is allocated with an STU Overhead for STU (OSTU) frame for transmitting overhead information, and since the OPU payload area is far larger than the OPU overhead area, more overhead information can be transmitted in a single transmission period, thereby reducing transmission delay of the overhead information.

As shown in fig. 5, an embodiment of the present application provides an overhead information transmission method. The method comprises the following steps S101-S104.

S101, the first OTN equipment acquires overhead information.

In the embodiment of the present application, a PB for transmitting service data in one multiframe may be referred to as a first PB, and a PB for transmitting overhead information in one multiframe may be referred to as a second PB. The first PB and the second PB may be located in the same multiframe (or transmission period).

The overhead information is used to indicate the location information of the first PB in a multiframe (for example, the sequence number of the PB in a multiframe), and a service identifier (for example, the TPN of the OSU service) corresponding to the OSU frame carried by the first PB, where the service identifier is carried in the OSU frame, or may be carried in the first PB except for the location of the OSU frame. One overhead information may be corresponding to each PB in one multiframe, and then one multiframe (including P PBs) may correspond to P overhead information.

The location information of the PB in one frame referred to in the present application may be absolute location information of the PB in the frame (for example, a sequence number of the PB in the frame), or may be relative location information of the PB in the frame (for example, a sequence number offset of the PB relative to another PB in the frame); the absolute position information or the relative position information may be indicated explicitly (for example, by indicating a specific value), or implicitly (for example, by indicating the position or order of other information).

In one possible implementation, the first PB may include one or more consecutive PB's in one multiframe, and the first OTN device may send overhead information of one or more consecutive PB's in one multiframe, and in particular, the first OTN device may send overhead information of all (P) PB's in one multiframe. This embodiment can be applied to the following scenario: either before the initial transmission of the traffic data or when the system is idle.

As shown in fig. 6 or fig. 7, the second PB carrying the overhead information may include a first overhead field, a guard interval, and one or more first identification fields, where the one or more first identification fields respectively correspond to one or more consecutive PB in the first PB, that is, an nth first identification field corresponds to an nth PB in the first PB. The first overhead field is 7 bytes, the guard interval is 1 byte, and each first identification field is 2 bytes, for example. Assuming that one PB is 192 bytes in length, one second PB may include 92 first identification fields at most, and the first identification fields in the second PB may correspond to 92 consecutive PB in the first PB at most, that is, the second PB may transmit overhead information of 92 PB at most.

Wherein the first overhead field is used to indicate: the second PB is used for transmitting the overhead information corresponding to one or a plurality of continuous PBs in the first PB. The location of the first identification field in the second PB is used to indicate: in the location information of the PB corresponding to the first identification field in the first PB, for example, in fig. 6, the first identification field corresponds to pb#1, and the second first identification field corresponds to pb#2; in fig. 7, a first identification field corresponds to pb#2, and a second first identification field corresponds to pb#3. The value of the first identification field is used to indicate the service identifier corresponding to the OSU frame carried by the corresponding PB, and if the corresponding PB does not carry the service, the value of the first identification field may be an invalid value. For example, in fig. 6, the value of the first identification field indicates the service identifier corresponding to the OSU frame carried by pb#1, and the value of the second first identification field indicates the service identifier corresponding to the OSU frame carried by pb#2; in fig. 7, the value of the first identification field indicates the service identifier corresponding to the OSU frame carried by pb#2, and the value of the second first identification field indicates the service identifier corresponding to the OSU frame carried by pb#3.

Note that, since pb#1 in fig. 6 is actually the second PB for carrying overhead information, the value of the first identification field corresponding to pb#1 may be an invalid value. The scheme in fig. 7 may transmit overhead information for one more first PB than the scheme in fig. 6.

In another possible implementation manner, the first PB may include at least one PB in a multiframe, where the first PB includes a plurality of PB, the plurality of PB may be discontinuous PB, and the first OTN device may send overhead information of at least one PB in a multiframe, or the first OTN device may send overhead information of a portion PB in a multiframe. This embodiment can be applied to the following scenario: when the service corresponding to the OSU frame of the first PB bearer changes (updates and adds), or when the service corresponding to the OSU frame of the first PB bearer is deleted. The update of the service corresponding to the OSU frame of the first PB bearer means that the service corresponding to the OSU frame of the first PB bearer is changed from the first service to the second service; the new increase of the service corresponding to the OSU frame carried by the first PB indicates that the first PB originally does not carry the service and carries the service afterwards. Deleting the service corresponding to the OSU frame carried by the first PB means that the first PB originally carries the service and does not carry the service later.

For the scenario that the service corresponding to the OSU frame carried by the first PB changes (updates, and adds newly), as shown in fig. 8, the second PB carrying the overhead information may include a second overhead field, a guard interval, and at least one field set, where each field set corresponds to a service identifier of a service, that is, a content in one field set is used to indicate a service related content. Each field set includes a second identification field, a quantity field, and at least one location field. For example, the second overhead field may occupy 7 bytes, the guard interval may occupy 1 byte, the second identification field may occupy 2 bytes, the number field may occupy at least 1 byte, one location field may occupy at least 1 byte (e.g., K bytes, K being a positive integer), and the total length of at least one location field may be related to the number C indicated by the number field, C x K bytes.

The second overhead field is used for indicating that the service corresponding to the OSU frame carried by the first PB has a change. The second identification field is used to indicate a service identifier of one service after updating (for example, TPN of OSU service), for example, when the service corresponding to the OSU frame carried by the first PB changes from the first service to the second service, or when the first PB starts to carry the OSU frame corresponding to the second service, the second identification field is used to indicate the service identifier of the second service. The number field is used for indicating the number of PB included in the target PB, wherein the target PB refers to PB bearing an OSU frame corresponding to a changed OSU service in the first PB, for example, C PB bearing an OSU frame corresponding to a second service, and the number field is valued as C. The location field is used to indicate location information of the target PB.

The location information of the target PB may be absolute location information of each PB in the target PB in a multiframe, such as a sequence number of each PB in the target PB in a multiframe. Alternatively, when the target PB includes a plurality of PBs, the location information of the target PB may include: absolute position information (e.g., sequence number) of one PB (e.g., the first PB) of the plurality of PBs of the target PB in the multiframe, and relative position information (e.g., sequence number offset) of the other PBs with respect to the one PB. When the one PB is the first PB, the relative position information (for example, the sequence number offset) of the other PB with respect to the first PB may be the sequence number offset of the subsequent PB with respect to the previous PB, for example, the sequence number offset of the second PB with respect to the first PB, and the sequence number offset of the third PB with respect to the second PB.

For a scenario in which the traffic corresponding to the OSU frame carried by the first PB is deleted, as shown in fig. 9, the second PB carrying the overhead information may include a third overhead field, a guard interval, and at least one third identification field. The third overhead field is, for example, 7 bytes, the guard interval is 1 byte, and each third identification field is 2 bytes.

The third overhead field is used for indicating to delete the service corresponding to the OSU frame carried by the first PB; the third identification field is used to indicate the service identification of the deleted service (e.g., TPN of OSU service).

The guard interval referred to in this application is used to separate the overhead field in front of the guard interval from other fields in back of the guard interval.

S102, the first OTN device maps the overhead information into the payload area of the OTN frame (i.e. the payload area of the OPU frame).

In particular, the first OTN device may map the overhead information into the second PB of the payload region of the OTN frame.

In one multiframe (the multiframe is located in the payload area of the OTN frame), the second PB carrying overhead information may comprise one or more PB. One or more of the second PB's may be located at a start position of the multiframe as shown in fig. 10 a, or one or more of the second PB's may be located at an end position of the multiframe as shown in fig. 10B. When the second PB includes a plurality of PB, as shown in C or D in fig. 10, the plurality of PB in the second PB may be uniformly distributed in the multiframe, for example, one second PB is set every k PB in one multiframe, where k is a positive integer. Alternatively, as shown in fig. 10 a or B, the plurality of PB in the second PB may be one or more PB consecutive in the multiframe.

In one multiframe, the position of the second PB carrying the overhead information may be earlier than the position of the first PB carrying the service data, that is, the first OTN device may send the overhead information carried in the second PB first and then send the service data carried in the first PB, so that the receiving end (the second OTN device later) receives and parses the overhead information first and then parses the service data according to the overhead information. For example, when one or more of the second PB's are located at the start position of the multiframe as shown in fig. 10 a, or when a plurality of PB's in the second PB's as shown in fig. 10C may be uniformly distributed in the multiframe.

In a multiframe, after the second PB carrying the overhead information is located further than the first PB carrying the service data, the network manager may configure the overhead information to the first OTN device and the second OTN device in advance, and then the first OTN device may send the service data carried in the first PB first and then send the overhead information carried in the second PB, so that after the second OTN device receives the overhead information in the OTN frame, the overhead information in the OTN frame is checked according to the overhead information configured by the network manager, so as to determine whether network transmission is normal. For example, one or more of the second PBs as shown in FIG. 10B are located at the end of the multiframe.

The location of the second PB carrying overhead information may be fixedly allocated or flexibly allocated. A fixed allocation refers to one or more PB's in each multiframe at a fixed location (e.g., a starting location or an ending location of the multiframe) as a second PB, for transmitting overhead information only and not for transmitting traffic data, at least one PB at the fixed location being in an idle state (e.g., filling an invalid value) when no overhead information needs to be transmitted. The two communication parties (the first OTN device and the second OTN device) may agree on the fixed location of the second PB according to a protocol, or agree on the fixed location of the second PB through negotiation interaction, or determine the fixed location of the second PB according to a notification of a network manager. Flexible allocation means that when overhead information needs to be transmitted in one multiframe, at least one PB at a temporary location is allocated as a second PB to transmit overhead information, and at this time, indication information may be added to the header of the PB to indicate that the PB is the second PB (for transmitting overhead information). At least one PB at the temporary location transmits traffic data as the first PB when one multiframe does not need to transmit overhead information.

S103, the first OTN equipment transmits OTN frames.

Accordingly, the second OTN device receives the OTN frame.

For the scenario that the first OTN device sends overhead information of multiple PB's in one multiframe, since overhead information carried by the second PB in a transmission period of one multiframe is limited, transmission of the overhead information of multiple PB's may need to be completed through a transmission period of x (x is a positive integer) multiframes, that is, x represents a transmission period number of the overhead information, and x is a value obtained by dividing a number of overhead information of the first PB to be transmitted in one multiframe by a number of overhead information that can be transmitted by the second PB in one multiframe. The bandwidth efficiency of traffic data is the number of PB's carrying traffic data in a multiframe divided by the number of all PB's in the multiframe.

Taking the example that the first OTN device sends overhead information of all (P) PB s in one multiframe, the number of overhead information of the first PB s to be transmitted in one multiframe is P, and the number of overhead information that the second PB can transmit in one multiframe is CWherein (1)>Represents a rounding up, c=92 in fig. 6 and 7. />

Illustratively, in fig. 6 and fig. 7, the length of the overhead information of each PB is 2 bytes x 8 bits=16 bits, the length of the overhead information that can be carried by a second PB is cx16=92 x 16 bits, a multiframe includes 119 PB, and if the multiframe uses one PB as the second PB to transmit the overhead information, the bandwidth efficiency of the service data is (119-1)/119= 99.16%. Table 4 shows the x values of several transmission periods and the bandwidth efficiency of traffic data when one PB is used as the second PB transmission overhead information for one multiframe.

TABLE 4 Table 4

As can be seen from table 4, the bandwidth efficiency of the service data is very high, and can reach more than 99%. In addition, if only one PB is adopted as the second PB in one multiframe to transmit the overhead information, the larger the P value is, the larger the x value is, namely the more the transmission period of the overhead information is. Therefore, the PB number of transmission overhead information in one multiframe can be increased, so that the transmission period of overhead information is reduced, so that the transmission period meets the service requirement (not greater than ms), and table 5 shows the x values of several transmission periods and the bandwidth efficiency of service data when one multiframe uses different numbers of PB as the second PB to transmit overhead information.

TABLE 5

S104, the second OTN equipment receives the OSU frame borne by the first PB according to the position information of the first PB, and analyzes service data of the service borne by the OSU frame according to the service identifier corresponding to the OSU frame borne by the first PB, or checks the expense information.

In one possible implementation manner, the second OTN device may obtain, according to the overhead information, location information of the first PB and a service identifier corresponding to an OSU frame carried by the first PB, further determine the first PB according to the location information of the first PB, receive the OSU frame carried by the first PB, and parse service data of a service carried by the OSU frame according to the service identifier corresponding to the OSU frame carried by the first PB.

In another possible implementation manner, after the second OTN device receives the overhead information in the OTN frame, the second OTN device may check the overhead information in the OTN frame according to the overhead information configured by the network management device, so as to determine whether the network transmission is normal.

According to the overhead information transmission method, the communication device and the system, the overhead information is transmitted in the OPU payload area of the OTN frame, the overhead information is used for indicating the position information of the first PB in one multiframe and the service identifier corresponding to the OSU frame borne by the first PB, and the overhead information can be transmitted in a single transmission period because the OPU payload area is far larger than the OPU overhead area, so that the transmission delay of the overhead information is reduced.

It will be appreciated that in the above embodiments, the methods and/or steps implemented by the first OTN device may also be implemented by a component (e.g., a chip or a circuit) of the first OTN device. The methods and/or steps implemented by the second OTN device may also be implemented by a component (e.g., a chip or a circuit) of the second OTN device.

The embodiment of the application also provides a communication device. The communication device may be the first OTN device in the above method embodiment, or an apparatus including the first OTN device, or a chip or a functional module in the first OTN device, or a second OTN device in the above method embodiment, or an apparatus including the second OTN device, or a chip or a functional module in the second OTN device, so as to implement the above methods.

It will be appreciated that the communication device, in order to achieve the above-described functions, comprises corresponding hardware structures and/or software modules performing the respective functions. Those of skill in the art will readily appreciate that the elements and algorithm steps of the examples described in connection with the embodiments disclosed herein may be implemented as hardware or combinations of hardware and computer software. Whether a function is implemented as hardware or computer software driven hardware depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.

The embodiment of the application may divide the functional modules of the communication device according to the embodiment of the method, for example, each functional module may be divided corresponding to each function, or two or more functions may be integrated into one processing module. The integrated modules may be implemented in hardware or in software functional modules. It should be noted that, in the embodiment of the present application, the division of the modules is schematic, which is merely a logic function division, and other division manners may be implemented in actual implementation.

Fig. 11 shows a schematic structural diagram of a communication device 20. The communication device 20 comprises a processing module 201 and a transceiver module 202. The first communication device 20 may be the OTN device 101 in fig. 3, for example, the first OTN device or the second OTN device described above. The processing module 201 may also be referred to as a processing unit, and is configured to implement the processing function of the first OTN device or the second OTN device in the foregoing method embodiment. For example, steps S101, S102 in fig. 5 are performed, or step S104 in fig. 5 is performed. The transceiver module 202, which may also be referred to as a transceiver unit, is configured to implement the transceiver function of the first OTN device or the second OTN device in the above-described method embodiment. For example, step S103 in fig. 5 is performed. Transceiver module 202 may be referred to as a transceiver circuit, transceiver, or communication interface.

Taking the communication apparatus 20 as an example, the first OTN device in the above method embodiment is taken as an example. In a possible implementation manner, the processing module 201 is configured to obtain overhead information, where the overhead information is used to indicate location information of the first payload block PB and a service identifier corresponding to an OSU frame of an optical service unit carried by the first PB; the processing module is also used for mapping the overhead information into a payload area of the OTN frame; and the receiving and transmitting module is used for transmitting the OTN frame.

In another possible implementation, the processing module 201 is specifically configured to: and mapping the overhead information into a second PB in a payload area of the OTN frame, wherein the second PB and the first PB are positioned in the same multiframe.

Taking the communication device 20 as an example, the second OTN device in the above method embodiment is taken as an example. In a possible implementation manner, the transceiver module 202 is configured to receive an OTN frame, where a payload area of the OTN frame includes overhead information, and the overhead information is used to indicate location information of the first payload block PB and a service identifier corresponding to an OSU frame of an optical service unit carried by the first PB; the transceiver module 202 is further configured to receive OSU frames according to the location information; the processing module 201 is configured to parse service data of a service carried by the OSU frame according to the service identifier, or verify the expense information.

As shown in fig. 12, the embodiment of the application further provides a communication device. The communication device 30 comprises a processor 301, a memory 302 and a transceiver 303, the processor 301 being coupled to the memory 302 and the transceiver 303, the transceiver 303 being for supporting the communication device to communicate with other communication devices. When the processor 301 executes the computer program or instructions in the memory 302, a corresponding method of the first OTN device or the second OTN device in fig. 5 is performed. For example, processor 301 may be located in a system control and communications class board 1014 of OTN device 101 of fig. 4, and communications interface 303 may be located in tributary board 1011 or wiring board 1013 of OTN device 101 of fig. 4.

As shown in fig. 13, the embodiment of the application further provides a chip system. The chip system 40 comprises at least one processor 41 and at least one interface circuit 42. The at least one processor 41 and the at least one interface circuit 42 may be interconnected by wires. For example, at least one interface circuit 42 may be used to receive signals from other devices (e.g., in an OTN device) or to transmit signals to other communication devices (e.g., an optical transceiver in an OTN device).

The present application also provides a computer-readable storage medium including instructions that, when executed on the above-described OTN device or communication apparatus, cause the OTN device or communication apparatus to perform the functions or steps performed by the first OTN device or the second OTN device in the above-described method embodiment, for example, to perform the method shown in fig. 5.

Embodiments of the present application also provide a computer program product comprising instructions which, when executed on the above-described OTN device or communication apparatus, cause the OTN device or communication apparatus to perform the functions or steps performed by the first OTN device or the second OTN device in the above-described method embodiment, for example, to perform the method shown in fig. 5.

Technical effects concerning the communication apparatus, the computer-readable storage medium, the computer program product refer to technical effects of the previous method embodiments.

The processor referred to in the embodiments of the present application may be a chip. For example, it may be a field programmable gate array (field programmable gate array, FPGA), an application specific integrated chip (application specific integrated circuit, ASIC), a system on chip (SoC), a central processing unit (central processor unit, CPU), a network processor (network processor, NP), a digital signal processing circuit (digital signal processor, DSP), a microcontroller (micro controller unit, MCU), a programmable controller (programmable logic device, PLD) or other integrated chip.

The memory to which embodiments of the present application relate may be volatile memory or nonvolatile memory, or may include both volatile and nonvolatile memory. The nonvolatile memory may be a read-only memory (ROM), a Programmable ROM (PROM), an Erasable PROM (EPROM), an electrically Erasable EPROM (EEPROM), or a flash memory. The volatile memory may be random access memory (random access memory, RAM) which acts as an external cache. By way of example, and not limitation, many forms of RAM are available, such as Static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchronous DRAM (SLDRAM), and direct memory bus RAM (DR RAM). It should be noted that the memory of the systems and methods described herein is intended to comprise, without being limited to, these and any other suitable types of memory.

It should be understood that, in various embodiments of the present application, the sequence numbers of the foregoing processes do not mean the order of execution, and the order of execution of the processes should be determined by the functions and internal logic thereof, and should not constitute any limitation on the implementation process of the embodiments of the present application.

Those of ordinary skill in the art will appreciate that the various illustrative modules and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.

It will be clearly understood by those skilled in the art that, for convenience and brevity of description, specific working procedures of the above-described system, apparatus and module may refer to corresponding procedures in the foregoing method embodiments, which are not repeated herein.

In the several embodiments provided in this application, it should be understood that the disclosed systems, devices, and methods may be implemented in other ways. For example, the above-described device embodiments are merely illustrative, e.g., the division of the modules is merely a logical function division, and there may be additional divisions when actually implemented, e.g., multiple modules or components may be combined or integrated into another device, or some features may be omitted or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed with each other may be through some interface, indirect coupling or communication connection of devices or modules, electrical, mechanical, or other form.

The modules described as separate components may or may not be physically separate, and components shown as modules may or may not be physically separate, i.e., may be located in one device, or may be distributed over multiple devices. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

In addition, each functional module in each embodiment of the present application may be integrated in one device, or each module may exist alone physically, or two or more modules may be integrated in one device.

In the above embodiments, it may be implemented in whole or in part by software, hardware, firmware, or any combination thereof. When implemented using a software program, it may be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the processes or functions described in accordance with embodiments of the present application are produced in whole or in part. The computer may be a general purpose computer, a special purpose computer, a computer network, or other programmable apparatus. The computer instructions may be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another computer-readable storage medium, for example, the computer instructions may be transmitted from one website, computer, server, or data center to another website, computer, server, or data center by a wired (e.g., coaxial cable, fiber optic, digital subscriber line (Digital Subscriber Line, DSL)) or wireless (e.g., infrared, wireless, microwave, etc.). The computer readable storage medium may be any available medium that can be accessed by a computer or a data storage device including one or more servers, data centers, etc. that can be integrated with the medium. The usable medium may be a magnetic medium (e.g., a floppy Disk, a hard Disk, a magnetic tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a Solid State Disk (SSD)), or the like.

The foregoing is merely specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily think about changes or substitutions within the technical scope of the present application, and the changes and substitutions are intended to be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A method for transmitting overhead information, comprising:

the method comprises the steps that first Optical Transport Network (OTN) equipment obtains overhead information, wherein the overhead information is used for indicating position information of a first Payload Block (PB) and service identifiers corresponding to Optical Service Unit (OSU) frames borne by the first PB;

the first OTN device maps the overhead information into a payload region of an OTN frame;

and sending the OTN frame.

2. The method according to claim 1, wherein the first OTN device maps the overhead information into a payload area of an OTN frame, comprising:

the first OTN device maps the overhead information into a second PB of a payload region of the OTN frame, the second PB being located in a same multiframe as the first PB.

3. The method of claim 2, wherein the second PB is a PB at a start or end position of the multiframe.

4. The method of claim 2, wherein the second PB is one or more consecutive PB's in the multiframe, or wherein the second PB is a plurality of PB's evenly distributed in the multiframe.

5. The method according to any of claims 2-4, wherein the first PB comprises one or more consecutive PB's, the second PB comprises a first overhead field and one or more first identification fields, the one or more first identification fields corresponding to one or more consecutive PB's of the first PB's, respectively;

the first overhead field is used for indicating to transmit the overhead information corresponding to one or a plurality of continuous PB in the first PB;

the position of the first identification field in the second PB is used for indicating the position information of the PB corresponding to the first identification field, and the value of the first identification field is used for indicating the service identifier corresponding to the OSU frame carried by the corresponding PB.

6. The method of any of claims 2-4, wherein the second PB comprises a second overhead field and at least one field set comprising a second identification field, a number field, and a location field;

The second overhead field is configured to indicate that a service corresponding to an OSU frame carried by the first PB has a change;

the second identification field is used for indicating the service identification of the updated service;

the number field is used for indicating the number of PB included in the target PB, where the target PB is PB bearing an OSU frame corresponding to the changed OSU service in the first PB;

the location field is used to indicate location information of the target PB.

7. The method of claim 6 wherein the location information of the target PB is absolute location information of the target PB in the multiframe.

8. The method of claim 6 wherein the target PB comprises a plurality of PB, the location information of the target PB comprising: absolute position information of one PB of the plurality of PBs of the target PB in the multiframe, and relative position information of other PBs relative to the one PB.

9. The method according to any of claims 2-4, wherein the second PB comprises a third overhead field and at least one third identification field;

the third overhead field is configured to instruct deletion of a service corresponding to the OSU frame carried by the first PB;

The third identification field is used for indicating the service identification of the deleted service.

10. A method for transmitting overhead information, comprising:

the method comprises the steps that OTN equipment of a second Optical Transport Network (OTN) receives an OTN frame, wherein a payload area of the OTN frame comprises overhead information, and the overhead information is used for indicating position information of a first Payload Block (PB) and a service identifier corresponding to an Optical Service Unit (OSU) frame borne by the first PB;

and the second OTN equipment receives the OSU frame according to the position information, analyzes service data of the service carried by the OSU frame according to the service identifier, or checks the overhead information.

11. The method of claim 10, wherein the overhead information is carried in a second PB of a payload region of the OTN frame, the second PB being co-located with the first PB in a same multiframe.

12. The method of claim 11, wherein the second PB is a PB at a start or end position of the multiframe.

13. The method of claim 11, wherein the second PB is one or more consecutive PB's in the multiframe or the second PB is a plurality of PB's evenly distributed in the multiframe.

14. The method according to any of claims 11-13, wherein the first PB comprises one or more consecutive PB's, the second PB comprises a first overhead field and one or more first identification fields, the one or more first identification fields corresponding to one or more consecutive PB's of the first PB's, respectively;

15. The method of any of claims 11-13, wherein the second PB comprises a second overhead field and at least one field set comprising a second identification field, a number field, and a location field;

the location field is used to indicate location information of the target PB.

16. The method of claim 15 wherein the location information of the target PB is absolute location information of the target PB in the multiframe.

17. The method of claim 15 wherein the target PB comprises a plurality of PB, the location information of the target PB comprising: absolute position information of one PB of the plurality of PBs of the target PB in the multiframe, and relative position information of other PBs relative to the one PB.

18. The method according to any of claims 11-13, wherein the second PB comprises a third overhead field and at least one third identification field;

19. A first communication device comprising a processor and a transceiver for communicating with other communication devices, the method of any of claims 1-9 being performed when the processor executes instructions.

20. A second communication device comprising a processor and a transceiver for communicating with other communication devices, the method of any of claims 10-18 being performed when the processor executes instructions.

21. A communication system comprising a first communication device according to claim 19 and a second communication device according to claim 20.