CN108882304B - Method and device for encapsulating data packet in data link layer - Google Patents
Method and device for encapsulating data packet in data link layer Download PDFInfo
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- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W28/00—Network traffic management; Network resource management
- H04W28/02—Traffic management, e.g. flow control or congestion control
- H04W28/06—Optimizing the usage of the radio link, e.g. header compression, information sizing, discarding information
- H04W28/065—Optimizing the usage of the radio link, e.g. header compression, information sizing, discarding information using assembly or disassembly of packets
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Abstract
The invention provides a method and a device for encapsulating data packets in a data link layer, wherein the method comprises the following steps: acquiring a data packet to be encapsulated; the method comprises the steps of cascading and encapsulating a plurality of data packets into Protocol Data Unit (PDU) packets, wherein each concatenated data packet in the PDU packets comprises a Length Indication (LI) field indicating the byte length of the data packet. The embodiment of the invention reduces the whole expense of a data link layer and can process the data packet with high efficiency and low time delay.
Description
Technical Field
The present invention relates to the field of mobile communications technologies, and in particular, to a method and an apparatus for encapsulating data packets in a data link layer.
Background
In the current development of the protocol stack scheme of the fifth Generation mobile communication technology (5th-Generation, 5G) in 3GPP, it is proposed that the protocol stack function of the data link layer needs to process a data packet with high efficiency and low delay, and requires Long Term Evolution (LTE) as a baseline.
In addition, the data link layer includes three protocol layers, a data convergence protocol (PDCP) layer, a Radio Link (RLC) layer, and a Medium Access Control (MAC) layer, wherein each protocol layer has a separate Protocol Data Unit (PDU), and the PDUs are constructed in different manners in each protocol layer, which results in an increase in the overall overhead of the data link layer.
Disclosure of Invention
The invention aims to provide a method and a device for encapsulating data packets in a data link layer, so as to reduce the overall overhead of the data link layer and process the data packets with high efficiency and low time delay.
In order to achieve the above object, the present invention provides a method for encapsulating a data packet in a data link layer, comprising:
acquiring a data packet to be encapsulated;
the method comprises the steps of cascading and encapsulating a plurality of data packets into Protocol Data Unit (PDU) packets, wherein each concatenated data packet in the PDU packets comprises a Length Indication (LI) field indicating the byte length of the data packet.
Optionally, when the method is applied to a data convergence protocol PDCP layer or a radio link RLC layer, a concatenation indication CI field for indicating whether a concatenation function of a PDU packet is started is included in a header of the PDU packet.
Optionally, when a plurality of data packets are encapsulated into a PDU packet in a cascade, the CI field in the header of the PDU packet indicates that the PDU packet has started the cascade function.
Optionally, when the value of the CI field is 0, indicating that the PDU packet does not start the concatenation function; and when the value of the CI field is 1, indicating that the PDU packet starts the cascade function.
Optionally, the CI field is 1 byte in length.
Optionally, the data packet comprises a service data unit SDU and/or fragment; the header of the PDU packet also comprises an FI field used for indicating whether the PDU packet comprises the segment and the position of the segment in the PDU packet.
Optionally, when the value of the FI field is 00, it indicates that no segment is included in the PDU packet; when the value of the FI field is 01, indicating that the PDU packet comprises a segment and the segment is at the starting position of the payload of the PDU packet; when the value of the FI field is 10, indicating that the PDU packet comprises the segment and the segment is at the tail position of the payload of the PDU packet; when the value of the FI field is 11, indicating that one or two segments are included in the PDU packet; wherein, when the PDU packet includes a segment, the PDU packet does not include SDU; when the PDU packet comprises two segments, one segment is at the starting position of the payload of the PDU packet, the other segment is at the end position of the payload of the PDU packet, and zero or more SDUs are included between the two segments.
On the other hand, an embodiment of the present invention further provides a device for encapsulating a data packet in a data link layer, where the device includes:
the acquisition module is used for acquiring a data packet to be encapsulated;
the device comprises an encapsulation module, a Protocol Data Unit (PDU) module and a control module, wherein the encapsulation module is used for encapsulating a plurality of data packets into a Protocol Data Unit (PDU) packet in a cascading way, and each concatenated data packet in the PDU packet comprises a Length Indication (LI) field indicating the byte length of the data packet.
Optionally, when the apparatus is applied to a data convergence protocol PDCP layer or a radio link RLC layer, a concatenation indication CI field for indicating whether a concatenation function of a PDU packet is started is included in a header of the PDU packet.
Optionally, when the encapsulating module encapsulates a plurality of data packets into the PDU packet in a cascade manner, the CI field in the header of the PDU packet indicates that the PDU packet has started the cascade function.
Optionally, when the value of the CI field is 0, indicating that the PDU packet does not start the concatenation function; and when the value of the CI field is 1, indicating that the PDU packet starts the cascade function.
Optionally, the CI field is 1 byte in length.
Optionally, the data packet comprises a service data unit SDU and/or fragment; the header of the PDU packet also comprises an FI field used for indicating whether the PDU packet comprises the segment and the position of the segment in the PDU packet.
Optionally, when the value of the FI field is 00, it indicates that no segment is included in the PDU packet; when the value of the FI field is 01, indicating that the PDU packet comprises a segment and the segment is at the starting position of the payload of the PDU packet; when the value of the FI field is 10, indicating that the PDU packet comprises the segment and the segment is at the tail position of the payload of the PDU packet; when the value of the FI field is 11, indicating that one or two segments are included in the PDU packet; wherein, when the PDU packet includes a segment, the PDU packet does not include SDU; when the PDU packet comprises two segments, one segment is at the starting position of the payload of the PDU packet, the other segment is at the end position of the payload of the PDU packet, and zero or more SDUs are included between the two segments.
The invention has the beneficial effects that:
when a data packet to be encapsulated is obtained and a plurality of data packets are encapsulated into a PDU packet in a cascading way, the length indication information of the encapsulated data packet does not need to be included in the packet header of the PDU packet by including a length indication LI field indicating the byte length of the data packet in each cascaded data packet in the PDU packet, so that the length of the packet header of the PDU packet is fixed, the cost of the PDU packet is reduced, the building speed of the PDU packet is increased, the data sending time delay is reduced, and the purpose of processing the data packet with high efficiency and low time delay is achieved; in addition, the LI field is only included in the concatenated data packets in the PDU packet, namely the LI field is not included in the non-concatenated data packets, so that the overall overhead of a data link layer is reduced; therefore, the embodiment of the invention realizes the purpose of processing the data packet with high efficiency and low time delay while reducing the overall overhead of a data link layer.
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FIG. 1 is a flow chart illustrating the steps of a method for encapsulating data packets in a data link layer in an embodiment of the present invention;
fig. 2 shows a general mode of RLC SDU in 5G;
FIG. 3 is a diagram showing the format of a 5-byte Sequence Number (SN) length RLC UM PDU with a CI field in 5G;
FIG. 4 is a diagram showing the format of an RLC UM PDU with a length of 10 bytes SN and carrying a CI field in 5G;
FIG. 5 is a diagram showing the format of a 10-byte SN RLC AM PDU with a CI field in 5G;
FIG. 6 shows a format diagram of RLC AM PDU segmentation with CI field in 5G;
fig. 7 shows a block diagram of an apparatus for encapsulating data packets in a data link layer.
Detailed Description
Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
The method for encapsulating a data packet in a data link layer provided in an embodiment of the present invention is a method for encapsulating a data packet in a data link layer in 5G, and as shown in fig. 1, is a flowchart of steps of the method for encapsulating a data packet in a data link layer in an embodiment of the present invention, and includes:
in this step, the data packet may specifically include a Service Data Unit (SDU) and/or a segment.
Wherein, SDU is the data set of user service of the appointed layer, when transmitting to the receiver, the data is not changed in the same protocol layer, namely the service part; then, after being sent to the lower layer, the lower layer encapsulates the PDU and sends the PDU. SDUs are units of information from higher layer protocols that are transferred to lower layer protocols. The SDUs of the Nth layer and the PDUs of the previous layer are in one-to-one correspondence. According to the difference of PDU data, sending to the appointed layer of receiving end. The PDU is data transferred between N-layer protocol entities, and SDU submitted by a user is sent to an opposite-end protocol entity in the form of PDU through a lower-layer channel through data sending/receiving management. And recovering the PDU into SDU at the receiving end and sending the SDU to a receiving end user.
In addition, segmentation means that if the bandwidth of the lower channel cannot meet the requirement of delivering the SDU, one SDU needs to be divided into multiple segments, and the multiple segments are packaged into PDUs and transmitted.
And 102, cascading and packaging the plurality of data packets into a Protocol Data Unit (PDU) packet.
In this step, specifically, when a plurality of data packets are encapsulated into a PDU packet in a cascade manner, each concatenated data packet in the PDU packet includes a length indication LI field indicating the byte length of the data packet.
For example, when a plurality of SDUs are concatenated and encapsulated into a PDU, for each SDU being concatenated, a length indication LI field indicating the byte length of the respective SDU is included in each concatenated SDU in the PDU; when encapsulating a plurality of segments into a PDU in a cascade, for each segment in the cascade, each segment in the PDU includes a length indication LI field indicating the byte length of the respective segment; when concatenating and encapsulating the plurality of SDUs and the plurality of segments into a PDU, for each SDU and segment being concatenated, a length indication LI field indicating a byte length of the respective SDU is included in each concatenated SDU in the PDU and a length indication LI field indicating a byte length of the respective segment is included in each concatenated segment.
Therefore, only each cascaded data packet in the PDU packet comprises the length indication LI field indicating the byte length of the data packet, so that the header of the PDU packet does not need to comprise the length indication information of the encapsulated data packet, the length of the header of the PDU packet is fixed, the PDU packet cost is reduced, meanwhile, the building speed of the PDU packet is improved, the data transmission time delay is reduced, and the purpose of processing the data packet with high efficiency and low time delay is achieved.
Of course, it should be noted herein that if only one data packet is encapsulated as a PDU packet, that is, only one SDU or one segment is encapsulated as a PDU, the PDU packet does not concatenate the data packet, and therefore, the data packet does not need to include a length indication LI field indicating the byte length of the data packet. Therefore, compared with the condition that the PDU packets in the prior art need to carry the length indication information of the byte length of the data packets, the whole overhead of the data link layer is reduced.
To sum up, the embodiment of the present invention makes the packet header of the PDU packet not need to include the length indication information of the encapsulated data packet by including the length indication LI field indicating the byte length of the data packet in each cascaded data packet in the PDU packet, so that the length of the packet header of the PDU packet is fixed, thereby reducing the overhead of the PDU packet, improving the building speed of the PDU packet, reducing the data transmission delay, and achieving the purpose of processing the data packet with high efficiency and low delay; in addition, the LI field is only included in the concatenated data packets in the PDU packet, namely the LI field is not included in the non-concatenated data packets, so that the overall overhead of a data link layer is reduced; therefore, the embodiment of the invention realizes the purpose of processing the data packet with high efficiency and low time delay while reducing the overall overhead of a data link layer.
In addition, further, the method for encapsulating the data packet in the data link layer is applied to the PDCP layer or the RLC layer, that is, when the PDCP layer or the RLC layer has the concatenation function, at this time, the header of the PDU packet includes a concatenation indication CI field for indicating whether the PDU packet has started the concatenation function.
Specifically, when a plurality of data packets are encapsulated into a PDU packet in a cascade manner, the CI field in the header of the PDU packet indicates that the PDU packet has started the cascade function. Preferably, when the value of the CI field is 0, it indicates that the PDU packet does not start the concatenation function; when the value of the CI field is 1, it indicates that the PDU packet has started the concatenation function. Therefore, whether a plurality of data packets are cascaded in the PDU packet can be determined by checking the CI field in the PDU packet, and a foundation is provided for analyzing the PDU packet.
In addition, specifically, since the CI field indicates whether the PDU packet has started the concatenation function, the length of the CI field may be 1 byte.
Of course, it should be noted herein that, if the above method for encapsulating a data packet in the data link layer is applied to the MAC layer, that is, when the MAC layer has a concatenation function, the header of the PDU packet does not need to include a concatenation indication CI field for indicating whether the PDU packet has started the concatenation function.
Furthermore, the data packet includes SDU and/or segment, and the header of the PDU packet also includes FI field for indicating whether the segment is included in the PDU packet and the position of the segment in the PDU packet. Specifically, whether the PDU packet has the segment and the position of the segment in the PDU packet can be determined according to the value of the FI field, so as to provide a basis for parsing the PDU packet.
Specifically, when the value of the FI field is 00, it indicates that no segment is included in the PDU packet; when the value of the FI field is 01, indicating that the PDU packet comprises the segment and the segment is at the starting position of the payload of the PDU packet; when the value of the FI field is 10, indicating that the PDU packet comprises the segment and the segment is at the tail position of the payload of the PDU packet; when the value of the FI field is 11, indicating that one or two segments are included in the PDU packet, wherein when one segment is included in the PDU packet, the PDU packet does not include SDU; when two segments are included in the PDU packet, one segment is at the beginning of the PDU packet payload, the other segment is at the end of the PDU packet payload, and zero or more SDUs are included between the two segments.
Therefore, the embodiment of the invention can determine whether the PDU package is cascaded or not through the CI field and the FI field included in the PDU package, and the data package for the cascade connection is segmented or SDU, thereby providing a foundation for analyzing and restoring the PDU package to the SDU and increasing the analyzing speed of the PDU package.
Next, a method for encapsulating a packet in the 5G data link layer will be described based on the data link layer in LTE.
In the number link layer in LTE, PDCP PDUs in 5G are the same as PDCP PDUs in LTE, and MAC PDUs in 5G are the same as MAC PDUs in LTE.
Further, for RLC PDUs in 5G:
first, when RLC PDUs are transmitted in a Transparent Mode (TM), the RLC PDUs in 5G are the same as RLC TM PDUs in LTE.
When the RLC PDU is transmitted in an Acknowledged Mode (AM) or an Unacknowledged Mode (UM) or a preset mode, a general mode of the RLC SDU in 5G may be as shown in fig. 2. The preset mode is a mode in which an RLC header needs to be added or removed in the RLC.
In fig. 2, LI denotes a length indication field of the byte length of SDU. Specifically, the length of LI may be 16 bytes or other whole bytes, such as 8 bytes, 24 bytes, etc. In addition, specifically, whether the LI field needs to be carried or not can be selected according to whether the SDU is concatenated or not, wherein when the SDU is a concatenated data packet in the PDU packet, the SDU includes the LI field, and when the SDU is not a concatenated data packet in the PDU packet, the SDU does not include the LI field.
Note that, in fig. 2, fields other than the LI field are the same as the RLC SDU in LTE, and a repeated description thereof is not given here.
In addition, the LI field and the SDU indicating the byte length are placed together, but not centrally placed in the packet header of the RLC PDU, so that the packet header of the RLC PDU is of a fixed length, the establishment speed of the RLC PDU is increased, the data transmission delay is reduced, and the purpose of processing a data packet with high efficiency and low delay is achieved; in addition, the LI field is only included in the concatenated data packets in the PDU packets, i.e., the LI field is not included in the non-concatenated data packets, which results in a reduction of the overall overhead of the data link layer.
Secondly, when the RLC PDU is transmitted in AM or UM or a preset mode, a concatenation indication CI field for indicating whether the RLC PDU starts a concatenation function needs to be added to the header of the RLC PDU in 5G. Specifically, the definition of the CI field may be as follows:
the length of the CI field is 1 byte, and when the value of the CI field is 0, the PDU packet is indicated not to start the cascade function, and when the value of the CI field is 1, the PDU packet is indicated to start the cascade function. Therefore, whether the RLC PDU starts the cascading function or not can be determined by checking the RLC PDU, and a foundation is provided for analyzing and restoring the RLC PDU to the SDU.
Hereinafter, the RLC UM PDU and RLC AM PDU in 5G are separately explained.
First, as shown in fig. 3, it is a format diagram of RLC UM PDU carrying CI field with 5 byte Sequence Number (SN) length in 5G; fig. 4 is a format diagram of RLC UM PDU with length of 10 bytes SN and carrying CI field in 5G.
As can be seen from fig. 3 and 4, the header of the RLC UM PDU further includes an FI field for indicating whether the segment is included in the PDU packet and the position of the segment in the PDU packet. Specifically, whether the PDU packet has the segment and the position of the segment in the PDU packet can be determined according to the value of the FI field, so as to provide a basis for parsing the PDU packet.
When the value of the FI field is 00, indicating that the PDU packet does not comprise segments; when the value of the FI field is 01, indicating that the PDU packet comprises the segment and the segment is at the starting position of the payload of the PDU packet; when the value of the FI field is 10, indicating that the PDU packet comprises the segment and the segment is at the tail position of the payload of the PDU packet; when the value of the FI field is 11, indicating that one or two segments are included in the PDU packet; wherein, when the PDU packet includes a segment, the PDU packet does not include SDU; when two segments are included in the PDU packet, one segment is at the beginning of the PDU packet payload, the other segment is at the end of the PDU packet payload, and zero or more SDUs are included between the two segments.
In addition, the data packet included in the PDU packet may be determined according to the combination status of the FI field and the CI field. Of course, the data packet may include SDUs and/or segments.
Specifically, when determining a data packet included in the PDU packet according to the combined state of the FI field and the CI field:
when the value of the FI field is 00, indicating that the PDU packet does not include segments, and when the value of the CI field is 1, indicating that the PDU packet starts a cascading function, wherein each cascaded SDU in the PDU packet includes an LI field; if the value of the CI field is 0, indicating that the PDU packet does not start the concatenation function, and at this time, the PDU packet only includes one SDU, so that the SDU does not include the LI field, but the length is indicated by the L field in the MAC header.
When the value of the FI field is 01, indicating that the PDU includes a segment and the segment is at the start position of the payload of the PDU, and if the value of the CI field is 1, indicating that the PDU starts a concatenation function, wherein the concatenated segment of the PDU includes an LI field, and each concatenated SDU also includes an LI field; and if the value of the CI field is 0, indicating that the PDU packet does not start the cascade function, namely the PDU packet only comprises one segment.
When the value of the FI field is 10, indicating that the PDU includes a segment and the segment is located at the tail position of the payload of the PDU, and if the value of the CI field is 1, indicating that the PDU starts a concatenation function, where the concatenated segment in the PDU includes an LI field, and each concatenated SDU also includes an LI field; and if the value of the CI field is 0, indicating that the PDU packet does not start the cascade function, namely the PDU packet only comprises one segment.
When the value of the FI field is 11, indicating that the PDU packet comprises one or two segments; when the PDU packet comprises one segment, the PDU packet only comprises the segment and does not comprise the SDU; when two segments are included in the PDU packet, one segment is at the beginning of the PDU packet payload, the other segment is at the end of the PDU packet payload, and zero or more SDUs are included between the two segments. At this time, if the value of the CI field is 1, it indicates that the PDU packet has started the concatenation function, and certainly at this time, the concatenated segments in the PDU packet include an LI field, and each concatenated SDU also includes an LI field; and if the value of the CI field is 0, indicating that the PDU packet does not start the cascade function, namely the PDU packet only comprises one segment.
In addition, it should be noted herein that fields other than the CI field in fig. 3 are the same as the RLC UM PDU of 5-byte SN length in LTE, and fields other than the CI field in fig. 4 are the same as the RLC UM PDU of 10-byte SN length in LTE, and thus a repeated description thereof will not be made herein.
Second, as shown in fig. 5, it is a format diagram of RLC AM PDU carrying CI field with SN length of 10 bytes in 5G.
As can be seen from fig. 5, the header of the RLC AM PDU packet further includes an FI field for indicating whether the PDU packet includes a segment and a position of the segment in the PDU packet. Specifically, whether the PDU packet has the segment and the position of the segment in the PDU packet can be determined according to the value of the FI field, so as to provide a basis for parsing the PDU packet.
At this time, the content indicated by the value of the FI field in the RLC AM PDU packet and the content of the data packet included in the PDU packet determined by the combination status of the FI field and the CI field are the same as those of the RLC UM PDU packet, and a description thereof will not be repeated.
In addition, it should be noted that fields other than the CI field in fig. 5 are the same as the RLC AM PDU of 10-byte SN length in LTE, and therefore, a repeated description thereof is not made here.
Thirdly, as shown in fig. 6, it is a format diagram of RLC AM PDU segments carrying CI fields in 5G.
As can be seen from fig. 6, the header of RLC AM PDU segmentation (re-segmentation of retransmission) also includes an FI field for indicating whether the PDU packet includes a segment and where the segment is located in the PDU packet. Specifically, whether the PDU packet has the segment and the position of the segment in the PDU packet can be determined according to the value of the FI field, so as to provide a basis for parsing the PDU packet.
At this time, the content indicated by the value of the FI field in the RLC AM PDU packet and the content of the data packet included in the PDU packet determined by the combination status of the FI field and the CI field are the same as those of the RLC UM PDU packet, and a description thereof will not be repeated.
In addition, it should be noted that fields other than the CI field in fig. 6 are the same as RLC AM PDU packet segmentation in LTE, and therefore, a repeated description thereof is not made here.
Therefore, whether the RLC PDU packet is cascaded or not can be determined through the CI field and the FI field included in the RLC PDU packet, and the cascaded data packet is segmented or SDU, so that a basis is provided for analyzing and restoring the PDU packet into the SDU, and the analyzing speed of the PDU packet is increased.
Therefore, in the embodiment of the invention, each cascaded data packet in the PDU packet comprises the length indication LI field for indicating the byte length of the data packet, so that the packet head of the PDU packet does not need to comprise the length indication information of the encapsulated data packet, and the length of the packet head of the PDU packet is fixed, thereby reducing the cost of the PDU packet, improving the building speed of the PDU packet, reducing the data sending time delay and achieving the purpose of processing the data packet with high efficiency and low time delay; in addition, the LI field is only included in the concatenated data packets in the PDU packet, namely the LI field is not included in the non-concatenated data packets, so that the overall overhead of a data link layer is reduced; in addition, whether the PDU package is cascaded or not can be determined by including the CI field and the FI field in the PDU package, and the cascaded data package is segmented or SDU, so that a basis is provided for analyzing and restoring the PDU package to the SDU, and the analyzing speed of the PDU package is increased.
Fig. 7 is a block diagram illustrating an apparatus for encapsulating a data packet in a data link layer according to an embodiment of the present invention, where the apparatus includes:
an obtaining module 701, configured to obtain a data packet to be encapsulated;
an encapsulating module 702, configured to encapsulate a plurality of data packets into a protocol data unit PDU packet in a cascade manner, where each concatenated data packet in the PDU packet includes a length indication LI field indicating a byte length of the data packet.
Optionally, when the apparatus is applied to a data convergence protocol PDCP layer or a radio link RLC layer, a concatenation indication CI field for indicating whether a concatenation function of a PDU packet is started is included in a header of the PDU packet.
Optionally, when the encapsulating module encapsulates a plurality of data packets into the PDU packet in a cascade manner, the CI field in the header of the PDU packet indicates that the PDU packet has started the cascade function.
Optionally, when the value of the CI field is 0, indicating that the PDU packet does not start the concatenation function; and when the value of the CI field is 1, indicating that the PDU packet starts the cascade function.
Optionally, the CI field is 1 byte in length.
Optionally, the data packet comprises a service data unit SDU and/or fragment; the header of the PDU packet also comprises an FI field used for indicating whether the PDU packet comprises the segment and the position of the segment in the PDU packet.
Optionally, when the value of the FI field is 00, it indicates that no segment is included in the PDU packet; when the value of the FI field is 01, indicating that the PDU packet comprises a segment and the segment is at the starting position of the payload of the PDU packet; when the value of the FI field is 10, indicating that the PDU packet comprises the segment and the segment is at the tail position of the payload of the PDU packet; when the value of the FI field is 11, indicating that one or two segments are included in the PDU packet; wherein, when the PDU packet includes a segment, the PDU packet does not include SDU; when the PDU packet comprises two segments, one segment is at the starting position of the payload of the PDU packet, the other segment is at the end position of the payload of the PDU packet, and zero or more SDUs are included between the two segments.
Therefore, the device enables the header of the PDU packet to be fixed in length by including the length indication LI field indicating the byte length of the data packet in each cascaded data packet in the PDU packet, so that the header of the PDU packet does not need to include the length indication information of the encapsulated data packet, thereby improving the building speed of the PDU packet, reducing the data sending time delay and achieving the purpose of processing the data packet with high efficiency and low time delay while reducing the cost of the PDU packet; in addition, the LI field is only included in the concatenated data packets in the PDU packet, namely the LI field is not included in the non-concatenated data packets, so that the overall overhead of a data link layer is reduced; therefore, the embodiment of the invention realizes the purpose of processing the data packet with high efficiency and low time delay while reducing the overall overhead of a data link layer.
While the preferred embodiments of the present invention have been described, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the following claims.
Claims (10)
1. A method in a data link layer for encapsulating data packets, comprising:
acquiring a data packet to be encapsulated;
cascading and encapsulating a plurality of data packets into a Protocol Data Unit (PDU) packet, wherein each concatenated data packet in the PDU packet comprises a Length Indication (LI) field indicating the byte length of the data packet;
when the method is applied to a data convergence protocol PDCP layer or a radio link RLC layer, the header of the PDU packet comprises a cascade indication CI field used for indicating whether the PDU packet starts a cascade function or not;
when a plurality of data packets are packaged into a PDU packet in a cascading way, a CI field in the head of the PDU packet indicates that the PDU packet starts a cascading function; and the LI field is included only in the concatenated packet of the PDU packet.
2. The method of claim 1, wherein the CI field is 1 bit in length.
3. The method of claim 1,
the data packet comprises a service data unit SDU and/or fragment;
the header of the PDU packet also comprises an FI field used for indicating whether the PDU packet comprises the segment and the position of the segment in the PDU packet.
4. The method of claim 3,
when the value of the FI field is 00, indicating that no segment is included in the PDU packet;
when the value of the FI field is 01, indicating that the PDU packet comprises a segment and the segment is at the starting position of the payload of the PDU packet;
when the value of the FI field is 10, indicating that the PDU packet comprises the segment and the segment is at the tail position of the payload of the PDU packet;
when the value of the FI field is 11, indicating that one or two segments are included in the PDU packet; wherein, when the PDU packet includes a segment, the PDU packet does not include SDU; when the PDU packet comprises two segments, one segment is at the starting position of the payload of the PDU packet, the other segment is at the end position of the payload of the PDU packet, and zero or more SDUs are included between the two segments.
5. The method of claim 4,
when the value of the CI field is 0, indicating that the PDU packet does not start a cascade function;
and when the value of the CI field is 1, indicating that the PDU packet starts the cascade function.
6. An apparatus for encapsulating data packets in a data link layer, comprising:
the acquisition module is used for acquiring a data packet to be encapsulated;
the device comprises an encapsulation module, a sending module and a receiving module, wherein the encapsulation module is used for cascading and encapsulating a plurality of data packets into a Protocol Data Unit (PDU) packet, and each cascaded data packet in the PDU packet comprises a Length Indication (LI) field indicating the byte length of the data packet;
when the device is applied to a data convergence protocol PDCP layer or a radio link RLC layer, the header of the PDU packet comprises a cascade indication CI field used for indicating whether the PDU packet starts a cascade function or not;
when an encapsulation module encapsulates a plurality of data packets into a PDU packet in a cascading manner, a CI field in the head of the PDU packet indicates that the PDU packet starts a cascading function; and the LI field is included only in the concatenated packet of the PDU packet.
7. The apparatus of claim 6, wherein the CI field is 1 bit in length.
8. The apparatus according to claim 6, wherein the data packet comprises service data units, SDUs, and/or segments; the header of the PDU packet also comprises an FI field used for indicating whether the PDU packet comprises the segment and the position of the segment in the PDU packet.
9. The apparatus of claim 8, wherein when the FI field has a value of 00, it indicates that no fragment is included in the PDU packet; when the value of the FI field is 01, indicating that the PDU packet comprises a segment and the segment is at the starting position of the payload of the PDU packet; when the value of the FI field is 10, indicating that the PDU packet comprises the segment and the segment is at the tail position of the payload of the PDU packet; when the value of the FI field is 11, indicating that one or two segments are included in the PDU packet; wherein, when the PDU packet includes a segment, the PDU packet does not include SDU; when the PDU packet comprises two segments, one segment is at the starting position of the payload of the PDU packet, the other segment is at the end position of the payload of the PDU packet, and zero or more SDUs are included between the two segments.
10. The apparatus of claim 9, wherein when the value of the CI field is 0, indicating that a PDU packet does not initiate a concatenation function; and when the value of the CI field is 1, indicating that the PDU packet starts the cascade function.
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