WO2013067809A1

WO2013067809A1 - Inter-protocol-layer data segmentation and recombination processing method and device

Info

Publication number: WO2013067809A1
Application number: PCT/CN2012/076101
Authority: WO
Inventors: 朱寰; 郭文丹
Original assignee: 中兴通讯股份有限公司
Priority date: 2011-11-09
Filing date: 2012-05-25
Publication date: 2013-05-16
Also published as: CN103108407A; CN103108407B

Abstract

Provided are an inter-protocol-layer data segmentation and recombination processing method and device, the method comprising: setting the length of an SNDCP layer packet data package, and segmenting an IP packet to form a segmented SN PDU packet; segmenting the segmented SN PDU packet according to the length of an LLC layer packet data package so as to form a segmented LLC PDU packet; obtaining an SN PDU packet after removing the LLC prefix of the segmented LLC PDU packet of the LLC layer; parsing the SNDCP prefix of each SN PDU packet to obtain IP data segments; sequencing and combining the IP data segments; and recombining the IP layer with the combined IP packet. The present invention presets the length of the SNDCP layer packet data package so that the SNDCP layer is no longer limited by the LLC layer, and reduces the coupling degree between the SNDCP layer and the LLC layer, thus maintaining the independence of each layer and ensuring higher flexibility.

Description

Protocol layer data segmentation, recombination processing method and device

The present invention is directed to the field of mobile communications, and in particular, to a method for processing data segmentation and reassembly between protocols based on a GPRS (General Packet Radio Service) system, and a segmentation/reassembly processing device. Background technique

GPRS is a mobile packet data service developed on the basis of the existing GSM (Global System for Mobile Communication). GPRS introduces a packet-switched functional entity in the GSM digital mobile communication network to complete the data transmission in the packet mode to complete the GPRS service, and the original GSM network completes the voice function. The GPRS system can be seen as a service extension based on the original GSM circuit-switched system to support the need for mobile users to access the Internet or other packet data networks using packet data mobile terminals.

The basic network structure of the GPRS system is shown in Figure 1. In the GPRS system, the Urn interface between the MS (Mobile Station) and the BSS (Base Station Subsystem) and the Gb interface between the BSS and the SGSN (Serving GPRS Support Node) The wireless protocol stack structure contains multiple protocols. The wireless data plane protocol stack structure of the GPRS system is shown in Figure 2. The SNDCP (Subnetwork Dependent Convergence Protocol) performs data segmentation/reassembly, header and data compression/decompression for the data plane, and aims to aggregate different network layer protocols into air interfaces. Transmission saves the wireless bandwidth resources of the wireless interface between the terminal and the core network, and improves the data transmission efficiency.

However, in the SNDCP layer protocol, there is no indication of the specific size of the layer segment, and the specific segmentation is large. The small size is limited by the segmentation size of the LLC (Logical Link Control) layer. If the LLC is an acknowledgment frame, that is, in the acknowledge mode, the size of each segment does not exceed 1520 Bytes; if the LLC is a non-acknowledgement frame, that is, in the no-answer mode, each segment does not exceed 500 Bytes. Therefore, the upper protocol layer is subject to the lower protocol layer, and the coupling between the upper protocol layer and the lower protocol layer is relatively large and cannot be independent of each other. Summary of the invention

The main object of the present invention is to provide a method and device for data segmentation and reassembly between protocol layers based on GPRS system, so as to solve the problem of excessive coupling between protocols.

In order to solve the above problems, the technical solution of the present invention is implemented as follows:

A method for inter-layer data segmentation processing based on GPRS system, comprising:

Setting the packet data length of the SNDCP layer, and transmitting the IP packet of the IP layer to the SNDCP layer;

The IP packet is segmented according to the set SNDCP layer packet length, and each segment is added with a SNDCP header to form a segment subnet protocol data unit SN PDU packet;

The segmented SN PDU message of the SNDCP layer is transmitted to the logical link control LLC layer; each segment is added with a LLC prefix to form a segmented LLC PDU message.

The packet data packet length of the SNDCP layer is greater than or equal to the LLC layer packet data packet length.

Wherein, the SNDCP prefix is added to each segment to add the following content to each segment: an idle bit field, a first segment indicator field, a last segment indicator field, a PDU number field, The segment number field in the non-acknowledgement mode, and the packet packet length field.

The SNDCP header further includes: a data compression coding field and a protocol control information compression coding field, for the first segment SN PDU message.

Wherein, adding the LLC prefix to each segment is to add the following content to each segment: Address field Fields, Control Domain Fields, and Frame Check Fields.

A method for reorganizing data between protocol layers based on a GPRS system, comprising: sending the obtained SN PDU message to the SNDCP layer;

Parsing the SNDCP header of each SN PDU packet, removing the SNDCP header from each SN PDU packet, obtaining an IP data segment, and sorting and combining the IP data segments, and the size of each sorting combination does not exceed the set SNDCP. Layer packet data packet length, and the combined IP packet is transmitted to the IP layer;

The IP layer reassembles the received IP packets.

The process of sorting and combining the IP data segments includes: parsing a header of the SN PDU packet, obtaining a sequence number of the packet in the prefix, and sorting the IP data segment according to the sequence number of the packet .

A protocol inter-layer data segmentation/reassembly processing device based on a GPRS system, comprising: a lower layer transceiver module, an upper layer transceiver module, a segmentation/reassembly module;

The segmentation/reassembly module is configured to set a packet data packet length of the SNDCP layer, and is configured to receive an IP packet by using an upper layer transceiver module, and process the IP packet according to the set SNDCP layer packet length. The lower layer transceiver module is forwarded to the LLC layer. The SN PDU packet is received by the lower layer transceiver module, and the SN PDU packet is reassembled according to the set SNDCP layer packet length.

The packet data packet length of the SNDCP layer is greater than or equal to the length of the LLC layer packet data packet.

The invention pre-sets the packet data packet length of the SNDCP layer, so that the SNDCP layer is no longer restricted by the LLC layer, and the coupling degree between the SNDCP layer and the LLC layer is reduced, so that the layers remain independent. Guaranteed greater flexibility. DRAWINGS

1 is a schematic diagram of a basic network structure of an existing GPRS system;

2 is a schematic structural diagram of a wireless data plane protocol of an existing GPRS system;

3 is a schematic diagram of SNDCP PDU segmentation/reassembly according to the present invention;

4 is a flowchart of a data segmentation processing method according to Embodiment 1 of the present invention;

FIG. 5 is a flowchart of a data reorganization processing method according to Embodiment 2 of the present invention;

FIG. 6 is a schematic structural diagram of a segmentation/reassembly processing apparatus according to Embodiment 3 of the present invention. detailed description

The present invention will be further described in detail below with reference to the accompanying drawings.

The main idea of the present invention is to increase the length of the SN PDU (Subnetwork Protocol Data Unit) segment by only the data of the layer by increasing the definition of the layer segment length of the packet data packet of the SNDCP layer. Parameter constraints, but not subject to the reverse constraints of the data parameters of the lower LLC layer.

According to the traditional protocol function description, the implementation of the upper layer protocol requires the lower layer to provide corresponding services. The segmentation/reassembly process needs to be performed when the PDU is transmitted between the upper and lower layers.

Both Ethernet and 802.3 have limitations on the length of the protocol data unit when it is transmitted. The maximum values are 1500 bytes and 1492 bytes, respectively. This maximum transmission length is called MTU (Maximum Transmit Unit).

If the IP layer has a packet to transmit and the length of the data is larger than the MTU of the link layer, the IP layer needs to divide the packet into segments so that each segment is smaller than the MTU. Packet data When passing through a GPRS network, it is also necessary to perform a segmentation/reassembly process between protocol layers.

Embodiment 1

FIG. 4 is a flowchart of an embodiment of a data segmentation processing method according to the present invention, where the specific The data segmentation processing method includes:

Step 101: The packet data packet length of the SNDCP layer is set in advance, and the IP packet of the upper layer IP layer is sent to the SNDCP layer; the IP packet is segmented, and each segment of the IP packet is given. Adding the SNDCP header to form a segmented SN PDU message;

LLC layer;

Step 104: After receiving the segmented SN PDU message, the LLC layer segments the packet according to the length of the packet data of the LLC layer, and adds the LLC prefix to each segment to form a segment LLCPDU packet.

The added fields in the SNDCP header in the prior art are different for the answer mode and the non-acknowledge mode (see 3GPP TS 44.065 protocol). As shown in Table 1, for the acknowledge mode, the added fields include: idle bit (X), first segment indicator (F), SN PDU message type.

(T), whether the last segment indicator (Μ) and the PDU number (N-PDU number); wherein for the first segment SN PDU message, the SNDCP header further includes: a data compression coding field (DCOMP) and Protocol Control Information Compression Coding (PCOMP) field. As shown in Table 2, for the non-acknowledgement mode, the added fields include: idle bit (X), first segment indicator (F), SN PDU message type (T), whether the last segment indicator ( Μ) and PDU number

(N-PDU number), segment number (Segment number); wherein for the first segment SN PDU message, the SNDCP header further includes: a data compression coding field (DCOMP) and a protocol control information compression coding (PCOMP) field . The SNPDU message type field is used to indicate the response mode or the non-answer mode.

Table 1

As shown in Table 3, the present invention does not need to distinguish between the acknowledge mode and the non-answer mode in the SNDCP header, and the SNPDU packet type field is no longer needed, and a SNDCP header is added to the fragmented SNPDU header. The field SN-PDU LI is used to indicate the length of the packet of this layer. For the first segment SN PDU message, the SNDCP header further includes: a data compression coding field (DCOMP) and a protocol control information compression coding (PCOMP) field.

Table 3 For setting the size of the packet data packet size of the SNDCP layer, since the SNDCP layer is no longer based on the length of the LLC layer packet data, the T field used to indicate the response or no response mode in the SNDCP header is deleted, so the SNDCP layer The packet data length no longer distinguishes between the mode, that is, the acknowledge mode and the no answer mode, so it is recommended that the packet data packet length of the SNDCP layer is greater than or equal to the length of the LLC layer packet data packet. In addition, since the segment length of the LLC layer data is 1520 or 500 in the response and non-answer modes, respectively, and the SNDCP mode is not described above, it is recommended that the segment size of the SN-PDU is not less than 1520, as shown in Table 3, SN. - The PDU LI field occupies 11 bits and can indicate a length of 1520 or more.

When a LLC header is added to a segmented SN PDU message segmented at the LLC layer, the added header may include: an address field field, a control field field, and a frame check field.

Embodiment 2

FIG. 5 is a flowchart of an embodiment of a data reorganization processing method, where the specific data reassembly processing method includes:

Step 201: The LLC header of the segment LLC PDU packet of the LLC layer is removed, and the SN PDU packet is obtained and sent to the upper SNDCP layer.

Step 202: Parse the SNDCP header of the SN PDU packet, remove the SNDCP header from each SN PDU packet, obtain an IP data segment, and sort and combine the IP data segments, and the combined size may not exceed the SNDCP layer setting. Packet packet length, the combined IP data segment is an IP packet, and the IP packet is transmitted to the IP layer;

Step 203: The IP layer reassembles the received IP packet again. It is also recommended that the packet data packet length of the SNDCP layer be greater than or equal to the length of the LLC layer packet data packet.

In the above method, the IP data segments may be arranged and combined in the following manner: First, the SNDCP header of the received SN PDU packet is parsed, and the sequence number of the packet in the SNDCP prefix is obtained through parsing, and finally according to The obtained message sequence number is arranged and combined with the IP data segments.

Embodiment 3

FIG. 6 is a schematic structural diagram of an embodiment of a data segmentation/reassembly processing device. The device includes: a lower layer transceiver module, an upper layer transceiver module, and a segmentation/reassembly module.

The sub-reassembly module is configured to set a packet data packet length of the SNDCP layer, and is configured to receive an IP packet by using an upper layer transceiver module, perform segmentation processing on the IP packet according to the set SNDCP layer packet data packet length, and then send and receive the IP packet through the lower layer. The module is forwarded to the LLC layer. It is also used to receive the SN PDU message through the lower layer transceiver module, reorganize the SN PDU message according to the set SNDCP layer packet length, and then forward it to the IP layer through the upper layer transceiver module.

In the apparatus of the present invention, the segmentation/reassembly module for setting the packet data length of the SNDCP layer, the setting of the packet data length of the SNDCP layer is suggested to be greater than or equal to the LLC layer packet data packet length.

In summary, the protocol layer data segmentation processing method and apparatus of the present invention sets the packet data packet length of the SNDCP layer to segment the IP packet to form a segment SN PDU report segmentation LLC PDU message. . The segmented LLC PDU packet of the LLC layer may be removed from the LLC header to obtain an SN PDU packet, and the SNDCP header of each SN PDU packet is parsed to obtain an IP data segment, and the IP data segments are sorted and combined. The IP layer reassembles the combined IP packets. The invention pre-sets the packet data packet length of the SNDCP layer, so that the SNDCP layer is no longer restricted by the LLC layer, and the coupling degree between the SNDCP layer and the LLC layer is reduced, so that the layers remain independent. Guaranteed greater flexibility.

The above description is only for the preferred embodiment of the present invention and is not intended to limit the scope of the present invention.

Claims

Claim

1. A method for inter-layer data segmentation processing based on a general packet radio service GPRS system, comprising:

Set the packet data packet length of the subnet-related aggregation protocol SNDCP layer, and transmit the IP packet of the IP layer to the SNDCP layer;

2. The method according to claim 1, wherein the packet data packet length of the SNDCP layer is greater than or equal to the LLC layer packet data packet length.

The method according to claim 1 or 2, wherein said adding a SNDCP header to each segment is to add the following to each segment: an idle bit field, a first segment indicator field, whether The last segment indicator field, the PDU number field, the segment number field in the non-acknowledgement mode, and the packet packet length field.

The method of claim 3, wherein, for the first segmented SN PDU message, the SNDCP header further comprises: a data compression coding field and a protocol control information compression coding field.

5. The method according to claim 1 or 2, wherein the adding the LLC header to each segment is to add the following to each segment: an address field field, a control field field, and a frame check field.

A data processing method for inter-layer data re-establishment based on the GPRS system, comprising: sending the obtained SN PDU message to the SNDCP layer;

Parse the SNDCP header of each SN PDU, and remove the SNDCP for each SN PDU. After the prefix, the IP data segment is obtained, and the IP data segments are sorted and combined, and the size of each sorting combination does not exceed the set SNDCP layer packet data packet length, and the combined IP packet is transmitted to the IP layer;

The IP layer reassembles the received IP packets.

7. The method according to claim 6, wherein the packet data packet length of the SNDCP layer is greater than or equal to the LLC layer packet data packet length.

The method according to claim 6 or 7, wherein the process of sorting and combining the IP data segments comprises: parsing a header of the SN PDU packet, and acquiring a sequence number of the packet in the prefix, according to the The message sequence number sorts and combines the IP data segments.

9. A protocol inter-layer data segmentation/reassembly processing device based on a GPRS system, comprising: a lower layer transceiver module, an upper layer transceiver module, and a sub/reassembly module; wherein

10. The apparatus according to claim 9, wherein the packet data packet length of the SNDCP layer is greater than or equal to the LLC layer packet data packet length.