CN1567915A - A method for settled transmission of wireless TCP/IP message header - Google Patents

Abstract

The invention is a wireless transmission control protocol /Internet protocol (WTCP/IP) header-set data transmitting method, using packet header as an ID of the packet as being transmitted, setting the compressed format of the packet header, using the property of Internet point-to-point transmission, reducing the settings of source packet network layer, so as to reduce data transmission quantity between base station and mobile station.

Description

A kind of wireless transmission control protocol/Internet protocol header is set transmission method

Technical field

The present invention relates to a kind of TCP (Transmission Control Protocol/Internet Protocol, TCP/IP) header (header) compressed format, be particularly related to a kind of use affirmation mode (acknowledgement mode) and reduce base station (base station) and travelling carriage (mobilestation, MS) the TCP/IP compressed format of the transmission of preamble amount between.

Background technology

In recent years, along with the progress of mobile communication technology, various digital mobile products such as mobile phone, notebook computer, PDA etc., have been come in people's the life.People are to also just growing with each passing day such as wireless Internet access demands such as receiving and dispatching email, reception real time information at any time.How to realize the interconnection and interflow of radio communication and internet, just become important research project.With reference to Fig. 1, this figure is the system construction drawing of getting online without being tethered to a cable.Want to use the user of internet resource just to need a point-to-point connection to go up down-transmitting data, from the angle of getting online without being tethered to a cable, a point-to-point connection can be divided into two parts: the wireless connections part of (base station) and the wired connection part from the base station to the internet from user to the base station.In the wireless connections part, the user arrives base station with wireless mode with data transmission by utilizing the digital mobile product, perhaps receives the signal that the base station sends.Wired connection is partly utilized existing network configuration, such as telephone network, fiber optic network etc., connects the internet, links to each other with far-end such as server, personal computer, work station etc.

At present, point-to-point transmission agreement commonly used on the internet is TCP (TCP/IP), and TCP/IP is a kind of point-to-point transmission communication protocol that is based upon on traditional cable network.Because it possesses reliability and robustness, the growth along with the use of WWW (World Wide Web) is being widely used on the internet at present.

In traditional cable network, if transmit bigger data,, data will be divided into many less parts for fear of once taking too big bandwidth, transmit in proper order with the form of divide into groups (package), reconfigure the grouping that is received by receiving terminal at last.So just can obtain the data that transmitting terminal transmits.But because the internet extends in all direction, and connection status constantly changes, and for the fastest arrival destination, path that each grouping is walked will be different, so receive that the order of grouping also will be different with the order that sends.For example, factors such as though All roads lead to Rome, the road conditions in every main road are jammed, distance are all different, so even set out in the identical time, the time that arrives Rome but can be different.Therefore, need in grouping, do some marks, the grouping of could recombinating of just so-called header (header), receiving terminal.With reference to Fig. 2, this figure is the header format that TCP/IP commonly used at present divides into groups.The tcp/ip header form can be divided into transmission control protocol (TCP) header and Internet protocol (IP) header two parts.

The IP header portion at first is described.The IP header comprises version field, accounts for the space of 4 bits, is used for the employed TCP/IP version of mark; The IP header length field accounts for the space of 4 bits, is used for illustrating the bit space that the IP header is shared; Type of service field accounts for the space of 8 bits, and it is a kind of in minimum delay, maximum output, maximum reliability and the minimum internal memory expense; The total packet length field accounts for the space of 16 bits, is used to refer to the shared altogether byte number of this grouping; Identification field accounts for the space of 16 bits, and each grouping all can have a unique numbering, so that receiving terminal reconfigures this grouping; The Information sign group accounts for the space of 3 bits, is respectively: the Warning Mark field of 1 bit, shown in the A among Fig. 2, be used to refer to and whether enable this Information sign group, and the inseparable segment mark field of 1 bit (Don ' t Fragment, DF), shown in the B among Fig. 2, be used to refer to this last attribute field of sectional and 1 bit of whether dividing into groups (More Fragments, MF), whether shown in the C among Fig. 2, being used to refer to this grouping is last grouping; The split fix field accounts for the space of 13 bits, is used to refer to the position that the address of institute's segmentation begins to locate with respect to former data; Lifetime field accounts for the space of 8 bits, is used to refer to this and divides into groups the effective time; The communication protocol field accounts for the space of 8 bits, is used to refer to the type of this employed procotol of dividing into groups; Header checksum field accounts for the space of 16 bits, is used for checking mistake, to guarantee that grouping can correctly be transmitted; Source address field accounts for the space of 32 bits, the address that is used for storing transmit leg; And destination address field (DAF), account for the space of 32 bits, be used for storing recipient's address.The above-mentioned IP header accounts for 20 bytes altogether.

The following describes the TCP header portion.The TCP header comprises: the source port number field, account for the space of 16 bits, and be used to refer to the working port of transmitting terminal; Destination slogan field accounts for the space of 16 bits, is used to refer to the working port of receiving terminal; The field that sends sequence number accounts for the space of 32 bits, is used to refer to the numbering of grouping; The acknowledged sequence number field accounts for the space of 32 bits, is used to refer to the numbering of receiving grouping; The TCP header length field accounts for the space of 4 bits, is used for illustrating the bit space that the TCP header is shared; Reserved field accounts for the space of 6 bits, does not use this field at present as yet; The steering needle group accounts for the space of 6 bits, and comprising: (Urgent Pointer field urg), shown in the D among Fig. 2, accounts for the space of 1 bit to the emergency sign field, and whether be used to refer to this grouping is the grouping that carries emergency data; (whether Acknowledgment field ack), shown in the E among Fig. 2, accounts for the space of 1 bit to the acknowledgement indicator field, be used to refer to this grouping and require receiving terminal to send affirmation; (whether PushFunction psh), shown in the F among Fig. 2, accounts for the space of 1 bit to urgent attribute field, be used to refer to this grouping and require receiving terminal as early as possible these data to be passed to application program; (Reset theconnection rst), shown in the G among Fig. 2, accounts for the space of 1 bit, is used to refer to whether resend grouping to retransmit attribute field; (Synchronize syn), shown in the H among Fig. 2, accounts for the space of 1 bit to the synchronous mark field, is used to refer to and whether carries out synchronization negotiation; (whether Finish fin), accounts for the space of 1 bit to the complement mark field, shown in the I among Fig. 2, be used to refer to transmission and finish; The buffer length field accounts for the space of 16 bits, is used to refer to the packet count that the space of buffering area can receive, and produces to avoid exceeding the length of buffering area and overflows (overflow) mistake; Checksum field accounts for the space of 16 bits, is used for checking mistake, to guarantee that grouping can correctly be transmitted; Urgent pointer accounts for the space of 16 bits, when the indication of emergency sign field carries urgent grouping, and the position at this field store emergency data place.Above-mentioned TCP header accounts for 20 bytes altogether.In principle, the length of TCP header is the integral multiple of word (word)

From the above, general tcp/ip header accounts for 40 bytes altogether, and each grouping just all will increase the transmission quantity of 40 bytes, and this is quite huge in fact, and the waste resource.So the someone proposes some header-compressed (compression) method successively.On traditional cable network, commonly used at present is exactly the TCP gauge outfit compression method that Van Jacobson proposes, and just is called as the gauge outfit compression method of RFC 1144.RFC 1144 is the fields that can not change in life cycle by deletion, such as version field, destination address field (DAF) or destination slogan field etc., reaches the compression purpose.

Wireless connections also all adopt this method to come header compression at present.Yet RFC 1144 is compressions of being done at traditional cable network structure, is not for cordless communication network designs, and is subjected to such as bandwidth narrower restriction for wireless transmission and does not do comprehensive consideration.And the bottleneck of cordless communication network is wireless connections, therefore how effectively to increase data transmission rate, just become important research project, so for wireless connections, each unnecessary data that passes will reduce actual active data transfer rate more, therefore if can do further compression by other condition, just can improve the active data transfer rate such as the characteristic of radio communication etc.

Summary of the invention

Main purpose of the present invention provides a kind of TCP (TCP/IP) header-compressed form.

Another object of the present invention provides and a kind ofly can lower unnecessary transmission, to increase the tcp/ip header compressed format of actual volume of transmitted data.

For achieving the above object, the invention provides a kind of header-compressed form of the sign during as transmitted in packets, this compressed format is used for the affirmation pattern of wireless network, reduce the transmission of preamble amount of the wireless connections between base station and the travelling carriage, it comprises:

Connect sequence number field, be used for storing the connection sequence number, with the indication tcp/ip header required information relevant with the base station;

The buffer length field is used for the memory buffer length value, the packet count that can receive with the buffering area of indication receiving terminal;

With

A plurality of controlled flag fields are used to provide necessary information, with control transmission.

Description of drawings

Fig. 1 is the network structure of getting online without being tethered to a cable;

Fig. 2 is the header format that TCP/IP commonly used at present divides into groups;

Fig. 3 is the network structure of GPRS;

Fig. 4 is the structure chart on the transfer of data plane of GPRS;

Fig. 5 is header structure figure according to an embodiment of the invention.

The drawing reference numeral explanation:

1, connects sequence number field

2, buffer length field

3, controlled flag field

31, last attribute field

32, emergency sign field

33, acknowledgement indicator field

34, urgent attribute field

35, retransmit attribute field

36, synchronous mark field

37, complement mark field

38, retention position

4, urgent pointer

Embodiment

In order to make characteristics of the present invention, purpose and function more clear, in conjunction with the accompanying drawings the present invention is elaborated now.

The objective of the invention is to reduce the shared byte number of tcp/ip header.Except the method for using traditional RFC1144, can also start with from the characteristics of radio communication.Radio communication is that single-hop (single-hop) connects with the different cordless communication networks that are of wire communication maximum, after data are sent from transmitting terminal, can directly deliver to receiving terminal; And wireline communication network to be multi-hop (multi-hop) connect, after data are sent from transmitting terminal, can select the path of the fastest arrival.Because network conditions is changing at any time, may successively arrive receiving terminal through different paths so belong to the different grouping of same data.That is to say that in wireless connections mobile phone is that direct-connected single-hop is connected with the base station, can may not transmit through the different path of too much bar that the order of the feasible grouping that receives is different with the order of transmission as cable network.What want special declaration is, the connotation that multi-hop herein connects with the multipath effect (multi-patheffect) of radio communication is different, and multi-hop connects and refers to that different grouping is via different paths arrival receiving terminals; And multipath effect refers to the same phenomenons such as the refraction that is subjected to the influence of topography in the transmission course and produces, reflection that are grouped in, and makes receiving terminal successively receive several by the caused interference phenomenon of the signal of same signal source.Both meanings are different, earlier clarification here.At last, in the needed data of tcp/ip header, some can find in wireless communication protocol in fact, and like this, both have just had the place of repeating, and therefore, the part of repetition just can be omitted, and will not transmit.

Below utilize the embodiment that applies the present invention to GPRS to specify the present invention.Full name of GPRS is " GPRS (General Packet Radio Service) ", is the data transmission service of at present the most frequently used wireless network.GPRS is based upon on the second generation digital mobile telephone system GSM (Global System for Mobile communication), and it is improved, and is also referred to as the 2.5th third-generation mobile communication.With reference to Fig. 3, it is the network structure of GPRS.In the network configuration of GPRS, base transceiver station among the BSS (base transceiver station, BTS) receive user's signal after, with its be transferred to base station controller (Base Station Controller, BSC), at this moment, BSC with voice signal through circuit switching (circuit switch), by mobile switching centre (Mobile Switching Center, MSC), be sent to public telephone network (Public SwitchTelephone Network, PSTN); Perhaps with the packet switching (package switch) of data-signal process, by Serving GPRS Support Node (Serving GPRS Support Node, SGSN) and Gateway GPRS Support Node (Gateway GPRS Support Node GGSN), is connected to the internet.Wherein, the major function of SGSN be identification GPRS the used BTS of validated user, recording user, give user equipment allocation dynamic IP addressing (Dynamic IP Address), receive data from GGSN after, its dismounting is become grouping, be sent to wireless subscriber terminal equipment by BSC, BTS then.SGSN is to be connected by the trunk in the GPRS network (backbone) net with GGSN.

With reference to Fig. 4, it is the structure chart on GPRS transfer of data plane.From bottom to top roughly can be divided into physical layer, wireless connection control (Radio Link Control here successively at travelling carriage, RLC)/medium access control (Medium Access Control, MAC) layer, logic connect control (Logical LinkControl, LLC) layer, subnet dependent converge (Subnetwork Dependent Convergence, SNDC) layer and network layer.

Below the part relevant with the present invention done simple description.The function of rlc/mac layer is exactly to allow the service on upper strata can pass through the physical layer transmission of GPRS air interface smoothly.It has defined the load mode that allows a plurality of mobile phones can share the identical traffic medium simultaneously.Wherein, rlc layer mainly is responsible for process and the correction process of data by air interface (air interface) transmission, and here, the mode that error correction is taked mainly is that selectivity retransmits (selective ARQ).MAC layer between mobile phone and base station mainly is to adopt mode based on the time slot A LOHA agreement of reserving (slotted ALOHA basedreservation protocol) allow a plurality of user's shared bands.It mainly is in charge of the trial of a plurality of mobile phone access Radio Resources, and determines the mode of allocation of radio resources in network terminal.When a plurality of mobile phones send the wireless channel access request, because resource-constrained will produce collision.One of groundwork of MAC is exactly the retransmit issue that solves after bumping, and in addition, MAC also is responsible in the service request that a plurality of mobile phones propose, the user that decision will be served, and, provide suitable service according to user's request.Logic connects key-course, and (Logical Link Control LLC) provides the encryption logic of the high reliability between MS and the SGSN to connect.LLC adds LLC address, control field for the SNDC data cell from upper strata SNDC layer, thereby generates complete LLC frame.In addition, LLC can realize the repeating transmission control of multiple spot addressing and Frame.SNDC (Subnetwork Dependant Convergence) layer is between GPRS serving GPRS support node and base station, finish by the SNDC agreement with communicating by letter of upper strata, it can be with the PDU of network layer, different demands according to lower floor's network, be segmented into one or more LLC frames and finish protocol conversion work, in addition, SNDCP also is responsible for the multitask of user data and compression, tcp/ip header conversion, and requires to decide load mode etc. according to quality of services for users.

As previously mentioned, the objective of the invention is to utilize the gauge outfit compression method of (1) RFC 1144, compression as the version field in the IP header, IP header length field, and the TCP header in the source port number field, reach TCP header length field etc.; (2) utilizing radio communication is the characteristic that single-hop connects, and compression is as the field that sends sequence number in the TCP header, acknowledged sequence number field etc.; Existing information when (3) utilizing travelling carriage and base station to connect, compression are as header checksum field etc.Utilize compression method to compress above-mentioned 3 described fields, can reduce unnecessary portions in the header, improve effective transfer rate.

With reference to Fig. 5, its be the present invention be applied to GPRS affirmation pattern (acknowledge mode) under specific embodiment.In the present embodiment, compressed format header according to the present invention accounts for the space of 32 bits, and the header of each grouping comprises:

Connect sequence number field 1, account for the space of 16 bits, be connected sequence number when being used to store the base station and connecting, with the relevant required information of tcp/ip header in indication base station with travelling carriage, wherein this of each TCP/IP connection connects all differences of sequence number, makes it to make a distinction mutually;

Buffer length field 2 accounts for the space of 8 bits, is used for the memory buffer length value, the largest packet number that its indication rx-side buffering district can receive; In original TCP/IP grouping, because the order difference that grouping arrives, so the buffer length field will take the space of 16 bits, so that storage can transmit the absolute quantity of grouping.It is the characteristic that single-hop connects that present embodiment utilizes radio communication, the order that grouping arrives is fixed, thus can send with previous header in the difference of buffer length because the change amplitude is not too large, difference is just near 0, so only need 8 bit spaces just to be enough to represent.With

A plurality of controlled flag fields 3 account for the space of 8 bits, are used for the control information that provides transmission required, so that control transmission.Wherein these a plurality of controlled flag fields 3 generally include: last attribute field 31, account for the space of 1 bit, and be used to indicate whether the grouping that is received is last grouping; Emergency sign field 32 accounts for the space of 1 bit, is used to indicate whether this grouping is urgent grouping, wherein, if when this emergency sign field indicates this to be grouped into urgent grouping, the urgent pointer 4 of other regeneration 16 bits of this header format is so that the position at indicating emergency data place; Whether acknowledgement indicator field 33 accounts for the space of 1 bit, be used to indicate this grouping to require receiving terminal to return affirmation.Whether urgent attribute field 34 accounts for the space of 1 bit, be used to indicate this grouping to require receiving terminal as early as possible these data to be passed to application program; Retransmit attribute field 35, account for the space of 1 bit, be used to indicate whether that requirement retransfers; Synchronous mark field 36 accounts for the space of 1 bit, is used to indicate whether carry out synchronization negotiation; Whether complement mark field 37 accounts for the space of 1 bit, be used for indication and transmit and finish; With retention position 38, be used for the preparation field that function expands, be the integral multiple of byte (byte) in order to make the shared space of a plurality of controlled flag fields usually, normally that it is the shared byte of the length of retention position 38 is filled up.In the present embodiment, above-mentioned 7 controlled flag fields take the space of 7 bits altogether, and in order to fill up 1 byte (8), retention position 38 will take the space of 1 bit.

Below, the present invention is done more detailed analysis.At first, connect for same TCP/IP, in the life cycle of TCP, there are many data can not change, that is to say, after the initialized action of process, required data have been arranged in the base station, and at this moment, the base station can be with these storage in being numbered the database of x, and will number x notice travelling carriage, this x connects sequence number exactly.So when travelling carriage transmits data, be the user of numbering x as long as show it earlier, the database that the base station will be gone to be numbered x is sought related data, and need not be transmitted by travelling carriage.Certainly, connect in order to distinguish all, this connection sequence number that each TCP/IP connects all should be different.These data generally include: as destination slogan field, receiving port number field, TCP header length field and the reserved field in the version field in the IP header, IP header length field, type of service field, lifetime field, communication protocol field, source address field, destination address field (DAF) and the TCP header.Wherein important field is four fields such as source address field, destination address field (DAF), source port number field and receiving port number field.Remove source address field and be Network Service Access Point Identifier (Network Service Access PointIdentifier by the SNDC layer, NSAPI) outside obtaining, destination address field (DAF), source port number field and receiving port number field all are to obtain by connecting the entrained data of sequence number field.Usually in base station and travelling carriage, all can write down and be connected sequence number, so that base station and travelling carriage are consulted.

Secondly, be the single-hop connection characteristics according to execution wireless transmission and radio communication under affirmation mode, the field that sends sequence number, acknowledged sequence number field and these information of split fix field are to find in SNDC and LLC header.Therefore field, acknowledged sequence number field and the split fix field of sending sequence number all can be omitted.And the function of the checksum field of the header checksum field of IP header and TCP header can be replaced by the inspection sequence field of the frame school in the LLC layer (frame check sequence field), so also can omit.Therefore, compressed format as shown in Figure 5 is in conjunction with the data in the base station, and such compressed format is feasible really.

According to the header-compressed form of present embodiment, only need 4 bytes in the ideal case, compare with traditional tcp/ip header of 40 bytes of needs, can save 90% space.Even under very rare urgent grouping situation, according to the header of present embodiment also 6 bytes of a needs (urgent pointer accounts for two bytes).During TCP/IP connected, most of the time can be used compressed format, so just can save the space of a large amount of unnecessary transmission, to improve effective speed.The present invention is not limited to be used for GPRS certainly, and in 3-G (Generation Three mobile communication system) (3G), such header-compressed form also can use.

Only be the preferred embodiments of the present invention, the not purpose that should be construed as limiting the scope of the invention as mentioned above.That is,, can make various equal variations and modification in form and details to the present invention not by under situation by the spirit and scope of the present invention that claims limited.

Claims (23)

1. wireless transmission control protocol/Internet protocol header is set transmission method, and this method of use reduces the transmission of preamble amount between base station and the travelling carriage under the affirmation pattern of wireless network, and this method comprises:

Mark with the header format of wireless transmission control protocol/Internet protocol during as the transmission grouping;

Set this header format, it had:

Connect sequence number field, be used for storage and connect sequence number, with the relevant required information of tcp/ip header in indication base station;

The buffer length field is used for the memory buffer length value, with the packet count of indicating the rx-side buffering district to receive; With

A plurality of controlled flag fields are used to submit necessary information, with control transmission.

2. wireless transmission control protocol as claimed in claim 1/Internet protocol header is set transmission method, and wherein the connection sequence number of each TCP/IP connection is all different.

3. wireless transmission control protocol as claimed in claim 1/Internet protocol header is set transmission method, and wherein this connection sequence number field connection sequence number of being stored is corresponding with destination address, destination slogan field and source port number field at least.

4. wireless transmission control protocol as claimed in claim 1/Internet protocol header is set transmission method, and wherein these a plurality of controlled flag fields also comprise last attribute field, are used to indicate whether this grouping is last grouping.

5. wireless transmission control protocol as claimed in claim 1/Internet protocol header is set transmission method, and wherein these a plurality of controlled flag fields also comprise the emergency sign field, are used to indicate whether this grouping is urgent grouping.

6. wireless transmission control protocol as claimed in claim 5/Internet protocol header is set transmission method, and wherein, when this was grouped into urgent grouping, this header format also generated a urgent pointer, was used to indicate the position at emergency data place.

7. wireless transmission control protocol as claimed in claim 6/Internet protocol header is set transmission method, and wherein, this urgent pointer takies the space of 16 bits.

8. whether wireless transmission control protocol as claimed in claim 1/Internet protocol header is set transmission method, and wherein these a plurality of controlled flag fields also comprise the acknowledgement indicator field, be used to indicate this grouping to require receiving terminal to send and confirm.

9. wireless transmission control protocol as claimed in claim 1/Internet protocol header is set transmission method, and wherein these a plurality of controlled flag fields also comprise urgent attribute field, are used to indicate receiving terminal whether as early as possible application program to be passed in this grouping.

10. wireless transmission control protocol as claimed in claim 1/Internet protocol header is set transmission method, and whether wherein these a plurality of controlled flag fields also comprise the re-transmission attribute field, be used to indicate this grouping to need to retransfer.

11. wireless transmission control protocol as claimed in claim 1/Internet protocol header is set transmission method, wherein these a plurality of controlled flag fields also comprise the synchronous mark field, are used to indicate this grouping whether to need to carry out synchronization negotiation.

12. wireless transmission control protocol as claimed in claim 1/Internet protocol header is set transmission method, whether wherein these a plurality of controlled flag fields also comprise the complement mark field, be used to indicate the transmission of this grouping to finish.

13. wireless transmission control protocol as claimed in claim 1/Internet protocol header is set transmission method, wherein this a plurality of controlled flag fields also comprise retention position, for the function expansion prepares.

14. wireless transmission control protocol as claimed in claim 1/Internet protocol header is set transmission method, wherein the length of these a plurality of controlled flag fields is integral multiples of byte.

15. wireless transmission control protocol as claimed in claim 14/Internet protocol header is set transmission method, wherein the length of these a plurality of controlled flag fields is 8 bits.

16. wireless transmission control protocol as claimed in claim 1/Internet protocol header is set transmission method, wherein, header length is 32 bits.

17. wireless transmission control protocol as claimed in claim 1/Internet protocol header is set transmission method, wherein this connection sequence number field accounts for the space of 16 bits.

18. wireless transmission control protocol as claimed in claim 1/Internet protocol header is set transmission method, this buffer length field wherein accounts for the space of 8 bits.

19. wireless transmission control protocol as claimed in claim 1/Internet protocol header is set transmission method, the wherein space of these a plurality of controlled flag fields account 8 bits.

20. wireless transmission control protocol as claimed in claim 1/Internet protocol header is set transmission method, wherein this ready position length is the bit number that is used to fill up the byte that these a plurality of controlled flag fields are not filled up.

21. wireless transmission control protocol as claimed in claim 1/Internet protocol header is set transmission method, wherein this buffer length field can with previous header in the difference of buffer length field represent.

22. wireless transmission control protocol as claimed in claim 1/Internet protocol header is set transmission method, wherein this header format can be used for GPRS.

23. wireless transmission control protocol as claimed in claim 1/Internet protocol header is set transmission method, wherein this header format can be used for 3-G (Generation Three mobile communication system).

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