CN101006704A - Dynamic packet buffering system for mobile handoff - Google Patents

Abstract

The present invention relates to the use of buffering packets for the mobile node at an access router or network node near the edge of the network that the mobile is moving away from or towards. The buffered packets are then forwarded to the mobile node once the handoff process is completed. This invention also relates to the use of buffering packets originating from the mobile node during the handoff process. The buffered packets are then forwarded to their intended destinations once the handoff process is completed. The buffering system is used in conjunction with existing mobility protocols, access protocols, or as an independent network or link layer mechanism.

Description

Be used for moving the dynamic packet buffering system that switches

Technical field

The application relates to wireless network, in some preferred embodiments, relates to the method that the mobile device of improvement between contiguous network etc. switches.

Background technology

1. network and Internet protocol

Have polytype computer network, the most famous is the Internet.The Internet is the worldwide network of computer network.Now, the Internet is the public and self-supporting network that can use millions of users.The Internet uses a group communication protocol that is called as TCP/IP (being transmission control protocol/Internet protocol) to connect main frame.The Internet has the communication construction that is known as internet backbone.Access to internet backbone is mainly controlled by the ISP (ISP) to company and the individual access of reselling.

IP (Internet protocol) can be on network sends to the agreement of another equipment with data from an equipment (for example phone, PDA[personal digital assistant], computer etc.).IP is a connectionless protocol.Now, there is the IP of various version, comprises for example IPv4, IPv6 etc.Each main process equipment on network has at least one IP address, and it identifies the attachment point of described main process equipment to IP network.In the connection of communication period between end points is discontinuous.When the user sent or receive data or message, data or message were divided into the composition that is called grouping.Each grouping is counted as independently data cell.

In order to be standardized in the transmission between the point on the Internet or the similar network, set up OSI (open system interconnection) model.Osi model is divided into seven stack layers with the communication process between two points in the network, and each layer adds the function group of himself.Each device processes message, thus the downward stream of end points place existence sent by each layer, and receiving the stream that makes progress of end points place existence by a plurality of layers.The normally merging of device operating system, application software, TCP/IP and/or other transmission and procotol and other software and hardware of the program of seven layer functions and/or hardware is provided.

Usually, when the user transmits or be delivered to the user, use uppermost four layers, when by equipment (IP main process equipment) pass-along message, use nethermost three layers when message.The IP main frame is any apparatus on network that can send and receive the IP grouping, for example server, router or work station.The destination upwards is not delivered to higher layer for the message of some other main frame, but is forwarded to other main frame.In OSI and other similar model, IP is in the 3rd layer, just network layer.The stratose of osi model goes out as follows.Layer 7 is an application layer, this layer for example identification communication side, identification service quality, consider subscription authentication and privacy, identification constraint to the data sentence structure, or the like.Layer 6 (being presentation layer) be for example that will arrive and data that go out from a kind of presentation format be converted to another presentation format etc. layer.Layer 5 (being session layer) are for example session to be provided with, to coordinate and stops, the layer that exchanges between using and talk with.Layer 4 (being transport layer) are the layers of for example managing end-to-end control and error checking etc.Layer 3 (being network layer) are the layers of for example handling route and forwarding etc.Layer 2 (being data link layer) be for example be provided for physical level synchronously, carry out the layer that transmission protocol knowledge and management etc. were filled and provided to bit.Institute of Electrical and Electric Engineers (IEEE) is divided into two further sublayer: MAC (medium access control) layer again with data link layer, to controlling to physical layer with from the transfer of data of physical layer; And LLC (logic link control) layer, carry out interface with network layer, interpreted command, and execution error recovers.Layer 1 (being physical layer) is for example at the layer of physical level by network transmission data stream.IEEE is divided into PLCP (physical layer convergence procedure) sublayer and PMD (physical medium is relevant) sublayer again with physical layer.

Usually, the layer higher than layer 2 (such as those layers that comprise network layer in the osi model or layer 3 etc.) is called as higher level.

2. wireless network

Wireless network can comprise polytype mobile device, for example honeycomb and radio telephone, PC (personal computer), laptop computer, wearable computer, cordless telephone, beep-pager, mobile phone, printer, PDA etc.For example, mobile device can comprise the digital system of the fast wireless transmission that is used to guarantee voice and/or data.Typical mobile device comprises some or all in the following assembly: transceiver (be transmitter and receiver, comprise the single-chip transceiver that for example has integrated transmitter, receiver and other desirable other functional unit); Antenna; Processor; One or more audio sensors (loud speaker or the microphone that for example are used for voice communication); Electromagnetic data memory (for example ROM in the equipment of data processing is provided, RAM, digital data memory etc.); Flash memory; Complete chip or integrated circuit; Interface (for example USB, CODEC, UART, PCM etc.); And/or other assembly.

WLAN can be used for radio communication, wherein the mobile subscriber can be connected to Local Area Network by wireless connections.Radio communication can comprise the communication of for example propagating via electromagnetic wave (for example light, infrared ray, radio, microwave).Current various wlan standards, for example bluetooth, IEEE 802.11 and the ownership RF of existing.

By the mode of example, blue tooth products is used between mobile computer, mobile phone, portable handheld device, PDA(Personal Digital Assistant) and other mobile device link is provided, and is provided to the connection of the Internet.Bluetooth is to calculate and the telecommunication industry standard, and it describes mobile device in detail and how can use short-distance wireless ease of connection ground to interconnect each other and interconnect with non-mobile device.Bluetooth created digital wireless protocols to solve because terminal use's problem that various mobile devices increase sharply and cause, wherein need to keep data sync with consistent from an equipment to another equipment, to allow thus do not have joint working from the equipment of different vendor together.Can come bluetooth equipment is named according to general name notion.For example, bluetooth equipment can have bluetooth device name (BDN) or with the related title of unique bluetooth device address (BDA).Bluetooth equipment also can add Internet protocol (IP) network.If bluetooth equipment moves on IP network, then it can be equipped with IP address and IP (network) title.Therefore, the bluetooth equipment that is configured to add IP network can comprise for example BDN, BDA, IP address and IP title.Term " IP title " refers to the title corresponding with the IP address of interface.

Ieee standard---IEEE 802.11 has stipulated to be used for the technology of WLAN and equipment.By using 802.11, can finish and support the Wireless Networking of each single base station of a plurality of equipment.In some instances, but equipment assembled in advance radio hardware, and perhaps the user can install the discrete hardware (such as card) that comprises antenna.For example, whether no matter access point (AP), travelling carriage (STA), bridge, pcmcia card or miscellaneous equipment, the equipment that uses in 802.11 all comprises three significant elements usually: wireless set, antenna and be controlled at MAC (medium access control) layer of stream of packets between the point in the network.

In addition, can in some wireless networks, use many interface equipments (MID).MID can comprise two or more independently network interfaces (for example blue tooth interface and 802.11 interfaces), thereby allows MID to add two independently networks, and carries out interface with bluetooth equipment.MID can have the IP address and with general purpose I P (network) title of IP address correlation.

Wireless Communication Equipment can comprise bluetooth equipment, many interface equipments (MID), 802.11x equipment (comprising for example IEEE 802.11 equipment of 802.11a, 802.11b and 802.11g equipment), ownership RF (ownership radio frequency) equipment, Wi-Fi (Wireless Fidelity) equipment, GPRS (general packet radio service) equipment, 3G cellular device, 2.5G cellular device, GSM (global system for mobile communications), EDGE (the enhancing data of GSM evolution) equipment, TDMA type (time division multiple access) equipment or comprise CDMA type (code division multiple access) equipment of CDMA2000, but be not limited thereto.But the address that each network equipment containing type is indefinite, it comprises (but being not limited thereto) IP address, bluetooth device address, bluetooth common name, bluetooth IP address, bluetooth IP adopted name, 802.11IP address, 802.11 IP adopted names or IEEE MAC Address.

Wireless network can also relate to method and the agreement of setting up in for example mobile IP (Internet protocol) system, pcs system and other mobile network system.With regard to mobile IP, it relates to the communication protocol of being created by the Internet engineering duty group (IETF).By mobile IP, mobile device user can move through network when keeping the IP address of its original allocation.Mobile IP has strengthened Internet protocol (IP), and has added when mobile device connects in its home network outside, is used for internet traffic is forwarded to the device of described mobile device.The Care-of Address (CoA) that mobile IP is distributed in the home address on the home network and identifies the current location of described equipment in network and subnet thereof for each mobile node.When equipment was moved to different networks, described equipment received new Care-of Address.Mobile agent on the home network can be related with its Care-of Address with each home address.Mobile node can when changing its Care-of Address whenever it, send to home agent with Binding Update by using for example internet control message protocol (ICMP).

Usually, in basic IP Route Selection (being outside mobile IP), routing mechanism is based on following hypothesis: each network node always has the constant attachment point to for example the Internet, and each IP addresses of nodes identifies its accompanying network link.Term " node " comprises tie point as used herein, and described tie point can comprise for example redistribution point or be used for the end points of transfer of data, and can discern, handle communication and/or communication is transmitted to other node.For example, internet router can be checked IP address prefix of the network of marking equipment for example etc.So at network level, router can be checked the one group of bit that for example identifies particular subnet.So in sub-network level, router can be checked the one group of bit that for example identifies particular device.Under the situation of the mobile IP of typical case communication, if the user disconnects from for example the Internet and being connected and attempting reconnecting at new subnet of mobile device, then described equipment must be configured to new IP address, correct netmask and default router.Otherwise routing protocol can not correctly be submitted grouping.

3. the switching of mobile device

Under the situation of the mobile device that for example has IP-based radio network interface (such as IEEE 802.11 or 802.16 interfaces), when described mobile device when a network moves to another network, it need be carried out roaming or switch.Under the situation of existing changing method, finish switching by carrying out the specific switching of following series of protocols layer usually:

The first, switching occurs in physical layer.In this, mobile device is transformed into wireless base station or WAP (wireless access point) in the objective network for example with its wireless channel.

The second, switching occurs in layer 2.In this, mobile device connects the converting into target network with its layer 2 (being link layer).As mentioned above, link layer or layer 2 refer to the agreement under the IP layer of being right after of carrying customer flow.If objective network need layer 2 authentication, the then authentication of mobile device execution and objective network.

The 3rd, switching occurs in the IP layer.In this, mobile device obtains local ip address from objective network, if needing IP layer authentication, described objective network carries out described authentication, thereafter, carry out IP layer position and upgrade, thereby make the IP grouping of going to described mobile device to be sent to described mobile device via described objective network by IP network.In some instances, support a kind of mode of IP layer to be to use the mobile IP that defines by the Internet engineering duty group (IETF).

The 4th, switching occurs in application layer.Mobile device is carried out in the required step of application layer, will correctly flow to application on the described mobile device via described objective network to guarantee its application traffic.For example,, can upgrade its current location with its ownership sip server, realize that application layer switches by mobile device when mobile device is used to manage when its application layer signal transmits by the Session Initiation Protocol of ietf definition.If described objective network needs, then mobile device may also need to carry out the application-layer authentication with objective network.This situation for example, mobile device is just using the IP Multimedia System (IMS) in 3GPP (third generation partner program) wireless network of being visited, wherein, IMS supports on the 3GPP network for the application layer signal transmission of multimedia application and the system based on SIP of management.

Sometimes, switching of IP layer or application layer are switched just enough.That is to say, may need not all to carry out the IP layer and application layer is switched both.When these existing methods are used for IP-based wireless network, can cause tangible switching delay.For example, in the geographic area that has many wireless lan (wlan)s (for example city), in complexity building or household's inside or exist in other public place of a plurality of WLAN, mobile device can receive stronger radio signal from a plurality of wireless networks simultaneously.Yet described mobile device may not be authorized to use some network in these wireless networks.

Under above-mentioned existing changing method, mobile device will come the select target network based on for example radio signal strength, and will experience above-mentioned steps with the linking objective network, find whether it be authorized to use described network or described network mobile device required capacity (for example sufficient available bandwidth) or service whether be not provided thereafter.Therefore, mobile device must be attempted being connected to another network, and repeats this process, and finally being connected to it up to it provides and allow its network that uses its required capacity or service (perhaps having tried all possible to the greatest extent network up to it).Therefore, under the situation of existing system, switching may spend the intolerable long period, and may postpone the sensitive application such as live voice and/or Video Applications.Though known various system and method, but still need be used for carrying out improved system and the method for switching at wireless network.

Summary of the invention

The extensive aspect of the preferred embodiments of the present invention is between the mobile device and communication node that move along a series of adjacent networks, switches under the situation of packet loss not having.When a network moves to another network, the period that does not have network to connect during mobile node can be run into.The packet buffer of the network node that the edge of the network node at the edge of the network that can be positioned at couple in router by use, is leaving near described mobile device, the network shifted near described mobile device is approaching and/or each mobile device at mobile node place realizes not having the packet loss of switching.When finishing handoff procedure, give described mobile node with the packet forward that is cushioned.

Being on the other hand of preferred embodiment in conjunction with having mobility protocol, access protocol or conduct independently network or link layer mechanism now, use buffering, and the protocol definition that will be used to cushion control is independent agreement, thereby the system of making and mobility management protocol are generally compatible.Described buffering control protocol between mobile device and mobile node with signals events and parameter.

The packet forward that the definition on the other hand of preferred embodiment is used for being cushioned creates a mechanism for the tunnel of mobile node, so that the independence of mobility management protocol to be provided.

Being on the other hand of preferred embodiment is buffered in the grouping that is in during the switching cycle in the transmission in buffer joint.In case finish switching, the grouping that is cushioned just is cleared and is transmitted to the mobile device that is positioned at reposition.Buffer joint can be set in mobile device, with the grouping of going out during in the mobile device buffer joint, being buffered in switching cycle, and buffer joint can be arranged on the network edge place, with buffering from the network edge buffer send and the grouping of going to described mobile device.The place is provided with buffer joint at single or multiple mobile devices, provides in bidirectional buffering between transfer period and the compensation to packet loss on both direction.

In another aspect of the preferred embodiments, before switching, the flow before switching arrives mobile device via previous network.When mobile device was prepared to move to new network, it gave buffer joint with the intention of oneself with signalisation, and described buffer joint begins the flow of going to described mobile device is cushioned.In case finish switching, the grouping that described mobile device is just cushioned to empty with the described buffer joint of signalisation is also given the described mobile device that is arranged in described new network with the packet forward that is cushioned, described buffer joint can belong to the node that needs adhoc buffer to support, and can belong to previous couple in router or next couple in router or described mobile device.

In another aspect of the preferred embodiments, buffer joint is the network entity that the grouping of one or more mobile devices is gone in intercepting, and when described mobile device is in the handoff procedure, grouping is carried out adhoc buffer to avoid packet loss, described buffer joint classification is for the grouping of each mobile node, the grouping that buffering is classified, and finish switch after the suitably grouping that cushioned of forwarding, and wherein, cushion the mobile device of service with each step in these steps of signalisation by request.

In another aspect of the preferred embodiments, after sure service finishes, existing buffering control protocol is transmitted the grouping that is cushioned with signalisation, and wherein when described buffer joint began to empty the grouping that is cushioned, it had been provided with the current Care-of Address of mobile device.Before emptying and transmitting the grouping that is cushioned, described buffering control protocol is also given described buffer joint with the current Care-of Address of described mobile node with signalisation.

In another aspect of the preferred embodiments, when mobile device is in the identical IP subnet with the buffering node, the grouping that is cushioned is sent to described mobile device by this locality, and when mobile device is on the different IP link with the buffering node, the grouping that is cushioned is addressed to its next hop router towards described mobile device, and uses the IP Route Selection to be sent to described mobile device.

In another aspect of the preferred embodiments, during crossing over, buffer stage takes place the period of traffic classification and buffering, described buffer stage is providing buffering service to begin immediately after responding the initial buffer request at buffer joint by indication, and finishes when serving termination condition when satisfied.In described buffer stage, buffer joint and mobile device can exchange one or more extended requests, and wherein, extension request negotiation is finished in each exchange.

The definition on the other hand of preferred embodiment: the buffering control protocol makes mobile device can specify the type (traffic classification) of the flow that will cushion.This permission mobile device is signaled buffer joint neatly and only interested flow is cushioned.This also helps buffer joint to reduce the required resource allocation of buffer requests.

The definition on the other hand of preferred embodiment: the resource that buffer joint adjustment and negotiation will distribute in carrying out the buffering service.The amount of the resource that will distribute is based on each request and considers the switching demand of mobile node and the availability of the resource in the buffer joint, calculates.Described negotiation is the part in the buffering control protocol.

The buffer joint of definition on the other hand of preferred embodiment is present in the mobile node.This helps to be present in the software application in the mobile node that is just sending grouping.When producing switching, the grouping that is sent is cushioned.Under these circumstances, mobile node is transmitted in localization to the signal of buffer joint and carries out.When the grouping that is cushioned will be cleared and transmit, the IP address, destination of the grouping that is cushioned was constant, and will carry out route to described IP address via normal IP Route Selection.

Following description in conjunction with the drawings will be more readily understood above-mentioned and/or others, characteristics and/or the advantage of various embodiment.Under applicable situation, various embodiment can comprise and/or get rid of different aspects, feature and/or advantage.In addition, under applicable situation, various embodiment can merge one or more aspects or the characteristics of other embodiment.The description of aspect, characteristics and/or the advantage of specific embodiment should be interpreted as and limit other embodiment or claim.

Description of drawings

Fig. 1 is the schematic diagram that serves as the buffering of packets model of BN with couple in router;

Fig. 2 is the schematic diagram with buffering of packets of pre-authentication/pre-configured;

Fig. 3 is the schematic diagram that is used for the buffer joint that is positioned at MN (BN) of going out to divide into groups;

Fig. 4 is the diagrammatic sketch of BCP protocol streams.

Embodiment

In the accompanying drawings, unrestricted mode shows the preferred embodiments of the present invention in the mode of example.

Though the present invention can implement with multiple different form, but should understand a plurality of exemplary embodiment as described herein like this, be the example that the disclosure should be considered to provide principle of the present invention, and these examples be not for the present invention is limited to this describe/or at the preferred embodiment shown in this.

Preferred embodiment is introduced

It is as follows to abridge as used herein: mobile node (MN); Communication node (CN); Buffer joint (BN); Empty strategy (FP); Buffering control protocol (BCP); Service finishes (EOS); Buffer sizes (bsz); Time limit overtime (hp); Sorting flow (tc); Care-of Address (CoA); Object code (rcode).

In mobile environment, can be contemplated that the mobile node (MN) that moves to another network from a network will not have network to connect for some time.Therefore, during switching cycle (HP), the grouping of going to MN in the transmission will be lost probably.Handoff procedure is worsened by such fact, promptly still passes through previous network for the packet traffic path of MN, till MN is notified to suitable entity with its reposition (mobile IPv 4/6 Binding Updates).In the case, leave moment of previous network, learn the reposition (HA or the CN that are used for the mobile IP v 6 routing optimality) of MN and suitably transmit moment of grouping, packet loss can take place up to suitable entity from MN.The so long phase of losing will seriously hinder can not the described stream transmission application quality of losing of full remuneration.

Prior art attempts to locate to alleviate described losing at network endpoint (that is media application).Most of multimedia application is by play buffer, FEC[10], based on feedback [8] and other the technology [9] of RTCP, the influence of packet loss is minimized, perhaps repair the little interruption in the flow.Yet existing solution had not both been considered excessive packet loss or excessive deferral, did not support losing the real-time application (for example VoIP) with delay-sensitive yet.In addition, these mechanism depend critically upon the cooperation of terminal system.If CN and MN distance are far, then any mechanism based on re-transmission all will cause postponing.The invention provides a kind of solution except that application endpoints, this solution is located at the couple in router place or at the network entity (buffer joint) at the edge of the network that is leaving or shifting near mobile device, and the packet buffer of each mobile device is provided.Be in the grouping in the transmission during in buffer joint (BN), switching cycle will being buffered in.When switching is finished, the grouping that is cushioned will be cleared, and send to the MN that is in the reposition.This method is BN, that go to MN for arriving, all groupings provide zero packets to lose.This solution has also been described and has been made MN can have the buffering scheme that the bigger granularity of BN behavior is controlled, thereby helps to reduce whole switching delay.

In switching cycle, go out to be grouped in the handoff procedure and also may lose by what MN sent.In the case, also can realize BN in this locality in MN, coming provides the buffering solution for the going out grouping in the switching cycle.All have BN in MN and network edge, this provides the bidirectional buffering between transfer period, and has compensated the packet loss on the both direction.

BN also can be arranged in access point, is used for assisting the MN that carries out active scan especially.When MN carried out active scan on the channel different with current related access point, described MN can no longer receive grouping from this access point.One embodiment of the present of invention use the MN battery saving mode to come with the described access point sight of signalisation, and make described access point represent MN to begin to cushion.Originally implementing BN on one's body at access point provides and good control identical functions to buffer circle and buffer sizes, as described in the 2.1.6.

1.1 background

Below preferred embodiment has improved and/or other background information.In the following file each is all incorporated herein by reference, for reference:

[1]Moore，N.，Choi?J.，Pentland?Bret，“Tunnel?Buffering?for?MobileIPv6，”draft-moore-mobopts-tunnel-buffexing-00.txt，July?2004；

[2]Khalil，M.，Akhtar?H.，Qaddoura?E.，Perkins?C，Cerpa?A.，“BufferManagement?for?Mobile?IP，”draft-mkhalil-mobileip-buffer-00.txt，October?1999；

[3]R.Koodli，“Fast?Handovers?for?Mobile?IPv6，”draft-ietf-mipshop-fast-mipv6-03.txt，October?2004；

[4]Krishnamurtrii?G.，Chalmers?R.，Perkins?C，“Buffer?Managementfox?Smooth?HandOvers?in?Mobile?IPv6，”draft-krishnamurthi-mobileip-buffer6-00.txt，July?2000；

[5]Chul-Ho?Lee，Dongwook?Lee，JongWon?Kim，“Seamless?MPEG-4Video?Streaming?over?Mobile?IP-enabled?Wireless?LAN，”NetworkResearch?Workshop?2004/18 ^th?APAN?meeting；

[6]Perkins?C.，Wang?K-Y.，“Optimized?smooth?handoffs?in?MobileIP，”Proceedings?of?IEEE?Symposium?on?Computers?and?Communications，July?1999；

[7]Pejman?Roshan，Jonathan?Leary，“802.11?Wireless?LANFundamentals，”Cisco?Press，ISBN?1587050773，December?2003；

[8]Rosenberg?J.，Schulzrinne?H.，“An?RTP?Payload?Format?forGeneric?Forward?Error?Correction”，RFC?2733，December?1999；

[9]Perkins?C.，Hodson?O.，“Options?for?Repair?of?Streaming?Media，”RFC?2354，June?1998；

[10]Bremen?J.，Wenger?S.，Sato?N.，et.Al.，“Extended?RTP?Profile?forRTCP-based?feedback(RTP/AVPF)，”draft-ietf-avt-rtcp-feedback-11.txt，August?2004；

[11]Reza?Rejaie?et?al.RAP：An?End-to-end?Rate-based?CongestionControl?Mechanism?for?Real-time?Streams?in?the?Internet，March?1999.

Existing two motions provide overall similar pooling feature [1,2].These two motions have all defined the expansion to mobile IP (v4/v6) agreement, to be supported in the buffering in network between transfer period.Preferred embodiment comprises for example one or more, all preferred in the existing unsupported following new features of scheme.

Existing motion and specific mobility management protocol are combined closely.On the contrary, this method is defined as independent agreement by cushioning control protocol, can with any mobility management protocol cooperation.

In existing motion, the position of buffer joint is limited to mobile agent, for example home agent and mobility anchor point.On the contrary, this method provides buffer joint position more flexibly.

In existing motion, the grouping that is cushioned to the mobile node forwarding switching cycle is finished after depends critically upon the forwarding behavior of mobile agent of the mobility management protocol of institute's combination.On the contrary, the tunnel that this method has defined itself creates a mechanism, and it is used for transmitting the grouping that is cushioned to mobile node, thereby desirable mobility management protocol independence is provided.

In the preferred embodiment of this method, defined the detailed queue mechanism of buffering packets and the detailed behavior under forwarding mechanism and the error situation, and in existing motion, do not had these details.

There is not ready-made protocol-specific in the link layer definition in the buffering of packets that is controlled between transfer period at the access point place.Method for optimizing described here can be defined within link layer, is used to be controlled between transfer period the buffering of packets at the access point place.

Be provided at the comparison between some embodiment of existing method and this method below.

Reference paper [1] has been described the application of adding the P bit in the mobility header of BU (Binding Update) and LBU (local Binding Update) message.In the time will cushioning (P bit value for ' 1 ') and when will transmit (the P bit value is ' 0 '), the value of P bit is indicated HA (home agent).Compare with some embodiment of this method, for example, dynamic negotiation can appear and can select to cushion end a plurality of behaviors aspect, this scheme be have circumscribed.

Reference paper [2] has been described the mobile IPv 4 buffered protocol that is similar to method proposed by the invention.The most similar place is the explicit definition to the control protocol of management buffering duration, negotiate buffer size and flow stream identifying information (IP traffic filtering device).Under the constraint of mobile IPv 4 environment, reference paper [2] is recommended to send the duration of determining buffer circle with explicit signal, but also the implicit time in rental period to buffer.Though this method can have some similitudes on function, this method is exceeding the scope work of mobile IPv 4 technology, and the position of BN is not limited to FA (Foreign Agent) or HA (home agent).

Reference paper [4] is the mobile IP v 6 version of [2], and has described similar mechanism.The unsupported feature of method that propose among the present invention, existing is that buffer management is found.It utilizes the IPv6 router advertisement to check the buffer capacity of network.Generally speaking, the method for describing in [4] and [2] is substantially the same.

Reference paper [8,9 and 10] provides optional mechanism to reduce packet loss, and does not use any buffer management agreement, but depends critically upon the cooperation of client.

Use the power management function of IEEE 802.11 to avoid the existing method [7] of packet loss when existing in MN (mobile node) active scan.In the method, MN is just entering park mode with this MN of signalisation current access point, and the grouping that this access point is attempted to cushion for MN is waken up up to MN.Yet in other situation, this method can not be used for buffering packets between transfer period.Thereby this shortcoming owing to the supposition of this method MN wake up stop to cushion after its continuation be associated with this access point and cause, and because this method do not carry in order to satisfy the specific QoS demand may needs additional information, for example Business Stream identifying information, buffer size and buffering cycle are so applicability is limited.

2. structure

In a preferred embodiment, there are two required (2) primary clustering: BN of buffering scheme and buffering control protocol (BCP).BCP signals incident and parameter between MN and BN.BCP is a reliable protocol, comprises that request (BReq) and response (BAns) with retransmission capabilities are right.In part 3, go through BCP.

In this structure, in buffering with between transmitting tangible separation is arranged, this makes can be with any node that forwards a packet to that is cushioned, described in the 2.1.5 joint when emptying buffer.Under the situation of mobility protocol, all carry out forwarding no matter whether relate to the tunnel.The use of BCP has also defined and significantly the separating of any mobility management protocol.Some BCP use as follows:

1) between host side and its couple in router as shown in Figure 1;

2) between host side and its access point.In the case, described buffering control protocol can be defined within L2 or L3.

Figure 1 illustrates the buffering of packets model of couple in router as BN.The most handy Business Stream 116,122 and 104 towards MN 102 is described this buffer model.Before switching, the flow 118 before switching arrives MN 102 via previous network 110.In case the MN decision moves to new network 112, then the MN explicitly is given BN 106 by signal with its Notice of Intention.Then, BN 106 begins to cushion the flow of still transmitting by previous network 110 116 to MN 110.In case switch and to finish, then MN 102 grouping 104 of notifying BN 106 to empty buffering by signal (explicitly or implicitly), and the grouping 104 that is cushioned is forwarded to MN 102 in the new network 112, shown in line 120.Yet, need emphasis to be pointed out that, the position of BN is not limited to this topological structure.As discussing in the 2.1.6 joint, BN can be positioned on any node that needs the adhoc buffer support.As example, previous couple in router 108, next couple in router 109 and mobile device 102 can all have buffer capacity.Flowline 114 is illustrated between communication node 100 and the MN 102, the acquisition routing optimality, switching flow afterwards.

That flowline 122 is illustrated in is between CN and the MN 102, that have Care-of Address, the flow after switching.There are two required critical piece: BN of buffering scheme and cushion control protocol (BCP).BCP signals incident and parameter between MN and BN.BCP is a reliable protocol, by the request with retransmission capabilities (BReq) and response (BAns) to constituting.In the 3rd joint, go through BCP.

2.1 buffer joint

In a preferred embodiment, buffer joint (BN) is a network entity, and when one or more MN were in the handoff procedure, grouping and these groupings of adhoc buffer that described one or more MN are gone in this network entity intercepting were to avoid packet loss.For this reason, BN must be to the branch group categories of each MN, the described grouping of buffering and the suitably grouping that cushioned of forwarding switching is finished after.In addition, each in these steps all is with signalisation by the MN of request buffering service.

2.1.1 buffer joint and buffering control protocol

With respect to MN, BN is passive entity.MN uses BCP to come to the service of BN request buffering.This agreement is also passed on the buffer requests result and is comprised the error condition of transmit error signal.BN response request (each BReq that is received is sent BAns), but never produce request.In joint 3, go through BCP.

2.1.2 traffic classification

BN must be able to classify to flow, and for asking each MN dynamic assignment buffer of service.When MN sends BReq[initial] time, MN points out the classification of the flow of necessary buffering.[initial] specified signal type (initial) and signal parameter that send, that comprise traffic classes information by MN.MN can be only interested in the flow of buffering particular type, but not go to all flows of MN.If MN does not provide classification information, then BN should cushion all flows for MN.

2.1.3 buffer sizes (bsz) is distributed

Also can be at BReq[initial] in consult the size of BN institute assigned buffers by MN.MN can learn the length and the flow rate of switching cycle in advance, thereby can calculate the reasonable value of buffer sizes (bsz).Yet BN can apply restriction to this value, with the conserve memory resource.Therefore, the end value of BN assignment bsz.BN with this end value as Bans[initial] a part pass MN back.If MN does not accept the value that BN provides, then MN can be by sending the signal BReq[stop that the expression desire stops the buffering service to BN] cancel its buffering service request.

MN also can be at BReq[initial] in point out whether the bsz that its proposes is the receptible amount that can not be littler of its demand.MN can be by at BReq[initial] be provided with in the parameter and force mark (flag.m) to indicate this information.Can not satisfy at BN under the situation of this requirement, BN ends service immediately and passes through Bans[initial] give MN with error back.In the case, BN does not even keep the state information about this service.

Though during initial negotiation, be provided with the bsz value, in the process of buffering service, can also dynamically adjust the bsz value.Details is seen part 3.3.2.

2.1.3 the buffering service duration

Because the buffering service is a transient service, so in case BN receives BReq[initial from MN] and set up the value of being consulted, just begin buffering.Then by the state information of BN maintenance about this service.If owing to certain reason BN can not accept initial request, then described in 2.1.7 joint, BN can be with this failure information as Bans[initial] a part pass to MN.Handed over service should comprise the switching cycle that MN could not send or receive the IP grouping at least.The termination of buffer circle is that service finishes (EOS) duration, it can have result sure or that negate, can utilize time limit method and the explicit signal in 2.1.3.1 joint and 2.1.3.2 joint, described respectively to transmit method, the buffer circle (bp) of determining to have positive result.Because one in the described method can replace another kind of method, so these two methods are mutual exclusion but complementation.When satisfying as during the buffer circle that negative decision occurs having in the error condition described in the 2.1.7 joint.

2.1.3.1 time limit buffering

The negotiable time limit timeout value of BN and MN (bp) is to determine EOS.At explicit reception BReq[stop] before overtime expiration constitutes existing compulsory execution and the sure EOS that empties strategy (FP), as described in the 2.1.4 joint.Big bp value may cause buffer to overflow.In the case, as overflowing accident handling buffer described in the 2.1.7.1 joint.Overtime length comprises the switching cycle that MN could not send or receive the IP grouping.

2.1.3.2 explicit signal transmits

Explicit reception BReq[stop before the bp value expiration of formerly being set up] constitute and affirm EOS and execute existing FP.Described in the 2.1.4 joint.Previous BReq[ext] signal also may carry the new FP value that covers any Existing policies.In the case, should execute new FP.The duration that explicit signal transmits should comprise the switching cycle that MN could not send or receive the IP grouping.Explicit signal transmits and can use with the time limit buffering.Explicit signal transmits and also can be used for the dynamic behaviour of regulating networks, for example changes the demand to buffer sizes.

2.1.3.3 error condition

In buffering viability error condition that occur, that force the buffering end of service, constituting negates EOS.If BN attempts to carry out limited recovery, then can put teeth in any existing FP.Yet error condition is considered to be destructive usually, and all resources and the state information of distributing to this service should be released to system, sees the 2.1.7 joint.

2.1.4 empty strategy

The BReq[initial that MN sends] and the such strategy of follow-up BReq indication, in a single day promptly satisfying EOS, BN just executes the grouping of any buffering.Transmit or abandon the array that is cushioned by the strategy (FP) that empties that BN executes, and utilize BCP or the outer mechanism of band (for example ICMP) that explicit error notification is sent to MN.BReq[initial from MN] comprise acquiescence FP, do not receive the follow-up BReq[ext of this acquiescence of any covering FP in case the buffering service finishes], BN just executes this acquiescence FP.The follow-up BReq[ext that comprises new FP] cover the FP of any previous foundation.

2.1.5 packet forward

When transmitting the grouping that is cushioned after existing FP is affirming EOS, BN must be able to learn the current C oA of MN when it begins to empty the grouping that is cushioned.The current C oA of MN may be identical with the CoA that registers in BN, if perhaps MN is at the CoA that has changed it after the BN registration, then the current C oA of MN may be different with the CoA that registers in BN.In order to make BCP and any mobility management protocol cooperation, itself has the mechanism of the current C oA of MN being informed BN when BN begins to empty the grouping that is cushioned BCP.This is to be included in BReq[stop by the current C oA with MN] realize in the message.Do not sending BReq[stop with signal] the situation that saves described time limit buffering as 2.1.3.1 under, BCP can be included in BReq[ext with CoA before the bp expiration] in the signal.Send a more than BReq[ext if having the MN of different CoA], then BN can use the CoA that last sends with signal.

Preferably, empty cushioned grouping and forwarding cushioned is grouped as follows execution.

If MN and BN in identical IP subnet, then utilize ARP(Address Resolution Protocol) that grouping this locality of being cushioned is sent to MN.Otherwise, if MN and BN on different IP links, then the grouping that is cushioned is sent to its next hop router towards MN, and utilizes the IP routing to be transmitted to MN.Under latter event, can in the IP tunnel between the current C oA of BN and MN, transmit the grouping that is cushioned.If, then pass through BReq[stop carrying out the explicit signal transmission to stop there is not this IP tunnel before the buffering] and BAns exchanges or the bp expiration, is sent by explicit signal and sets up described IP tunnel.As the part that IP tunnel is set up, BN must remain on the CoA of the MN in the previous network and the mapping between the current C oA.Then, the routing of buffering packets can be so that transmit this grouping by IP tunnel.Setting up under the certain situation of described IP tunnel by mobile management/optimization agreement (for example FMIP6[3]), described tunnel is used for transmitting the grouping that is cushioned, and need not create another tunnel.

Under MN and BN were positioned at situation on the different IP links, except creating IP tunnel, BN can revise the destination address of the IP grouping that is cushioned.During transmitting, BN can be revised as current C oA with the purpose IP address of grouping of buffering.Then, grouping will be transmitted to current C oA by normal IP routing.This has reduced the additional management that is associated with the IP tunnel of setting up and be maintained to MN.This IP mobility management protocol may not have tunnelling function can with or if not use under the situation of mobility management protocol also be helpful.

2.1.6 the position of BN in network

Though BN can be placed on any node on the communication path between MN and the CN, but preferably BN is placed on the accompanying previous couple in router of as shown in Figure 1 MN before switching, perhaps is placed on the accompanying new couple in router of as shown in Figure 2 MN after switching.Fig. 2 shows has pre-authentication/pre-configured buffering of packets, and under BN 214 is positioned at situation on the new network, can suppose some pre-authentications or pre-configuredly finishes before the MN motion.Pre-configured process makes that BN can be under situation about helping without any mobility protocol, even determines the address of MN before MN moves.Yet in all cases, no matter BN is arranged in previous network and still is arranged in new network, can adopt identical structure, and not changing alternately between BN and the MN.

Couple in router 204 is arranged in previous network 216, and couple in router (BN) 205 is arranged in new network 218.Flow before the switching between flowline 206 expression CN 202 and the MN 200.Flow after the switching between flowline 210 expression communication nodes 202 and the MN 200.Buffer traffic between flowline 212 expression CN 202 and the BN 214.Signal between flowline 208 expression MN 200 and the BN 214 transmits.

As shown in Figure 3, the another location of BN can be in MN self.Couple in router 314 is in new network 302, and couple in router 318 is formerly in the network 300.Buffer traffic between flowline 312 expression CN 304 and the MN 324.

Flow before flowline 306 switchings of expression from MN to CN.Signal between flowline 308 expression MN and the buffering node 310 transmits.The flow of flowline 316 expression after the switching of BN 310 to CN 304.

In this, Fig. 3 shows and is used for the buffer joint that is positioned at MN 324 (BN) of going out to divide into groups.In the case, BN is used in go out divide into groups the provide buffering service of switching cycle to MN.This is used and previous disclosed BN position mutual exclusion and complementation.With the BN that is arranged in MN, can realize bidirectional buffering.As previous position, not not changing alternately between the structure of BN and BN and the MN.

It also is helpful for the ping-pong between transfer period that BN is arranged in MN.For example, switch and when oneself is associated with previous network again, ping-pong takes place when MN fails to finish in new network.In the case, BN is to may be playing Restoration Mechanism in the grouping of losing between kaput switching trial period.When external outflow is carried out buffering at the MN place, only determine the forwarding behavior of buffering packets by the destination address of each grouping.In addition, not needing external signal to send in MN place buffering goes out to divide into groups.Reference paper [11] has been discussed buffering and has been gone out flow so that congested control to be provided, and does not handle mobile situation but this reference paper is concrete.

BN also can be arranged in previous access point, thus when MN in order to find new access point or to test the connectivity of new access point and when carrying out active scan, help grouping is cushioned.

2.1.7 error condition

Error condition or negative EOS can be because following former thereby generations.

2.1.7.1 BN can not provide service

BN may receive the BReq[initial of the MN that can not assent owing to resource limit].When the resource of BN was restricted owing to the existing buffering service that offers other MN, this thing happens in meeting.If BN decision is at BReq[initial] in the parameter forced of the MN total resources that can provide greater than system, also this situation can appear then.In the case, BN can be at BAns[initial] in this fault message is conveyed to MN, notice MN BN can not provide institute's requested service.BN will not keep any state information for institute's requested service.MN can select to resubmit the new BReq[initial with adjusted value].In the case, BN will be described new BReq[initial] handle as new service request.

2.1.7.2 buffer overflows

When as described in the 2.1.3 joint, when the grouping number of BN queuing has surpassed institute's assigned buffers capacity before satisfying buffer EOS, buffer takes place overflow.In the case, BN may not convey to situation MN and negotiate further measure, for example passes through BReq[ext] the prolongation buffer circle.MN can be in the centre of hand-off process, and BN will take following measure based on the previous management strategy that disposes like this.

2.1.7.2.1 tail drop finished up to the buffering duration

For recoverable environment is provided, BN can select only to keep the current grouping that cushions and abandon follow-up newly arrived grouping (tail drop).In case the buffering duration finishes, can described in the 2.1.4 joint, execute existing FP.This makes BN can limit the grouping number that MN will lose.

2.1.7.2.2 stop the buffering service

Be discontented with owing to resource limit under the situation about can be restorative maybe can not recover, BN can select to stop cushioning service fully and discharge all associated resources.In the case, in case exchanged follow-up BReq/BAns signaling, MN just can learn the action of BN.If such signaling do not occur when the buffering duration finishes, then BN can abandon all correlation behaviors that it is kept for related buffering service dumbly.

2.1.7.3 signal transmits fault (buffering control protocol fault)

When buffering control protocol mistake occurring, signal transmits fault and takes place.Buffering control protocol (BCP) provides re-transmission feature and the fault processing feature that can indicate this incident.BN can be according to suitably moving as the error severity of discussing in 3.5 joints.

2.1.7.4 system/host failure

The system failure can comprise that memory exhaustion, overall network connect other fault that main frame under fault or the BN or system enter instability and non-up state.Cause any incident or the situation of described state can be considered to destructive, and cause BN not work.The action that BN takes such incident will be depended on the seriousness and the restorability scheme that is arranged in the system of situation.In the case, the applicability of BN is determined by its execution mode.

2.2 demand

To realize seamless service stream in order in being grouped in transmission, being cushioned, need to impose restriction.

2.2.1 the priority of the grouping that is cushioned

For fear of the order entanglement that grouping sends, should keep the priority of the grouping after any relatively newly arrived switching of the grouping that is cushioned.Affirm that EOS and BN must transmit the grouping that is cushioned in case satisfy, BN must determine that the grouping that is cushioned has been forwarded to MN before any newly arrived grouping is sent to MN.For the order of the grouping that keeps sending to MN, this is essential.The method overwhelming majority that realizes is the specific and attached execution mode of available mechanism in the system.Universal method is as follows.

2.2.1.1 the additional forwarding queue among the BN

Except that the main buffer of BN, can implement additional forwarding queue.Newly arrived when described forwarding queue can be used to be stored in the buffer that empties BN, go to grouping MN, after switching.This has the effect of using two buffers in turn.Emptying of buffer is that the high main buffer of priority ratio forwarding queue is proprietary.For example, system can utilize flow control formation (that is Linux flow-control module) to realize queue priority.

2.2.1.2 system receiver formation

Some systems adopt interface receiver queue (network drive rx formation), before the grouping that arrives is by system forwards it is cushioned.BN can utilize this feature by obtaining in advance being stored in the processing of the grouping in this formation.BN can take system in advance, and empties its buffer before system begins to transmit the grouping that is stored in the receiver queue.A warning is: receiver queue keeps all groupings that arrive for interface.Therefore, the processing that obtains in advance receiver queue will postpone the transmission of all groupings usually, and not only postpone the transmission of the grouping of MN.

2.2.2 for emptying and forwarding rate of EOS

In the BN after the sure EOS empty with forwarding rate should be greater than the receiving velocity of the grouping after the newly arrived switching.If not so, be likely that then the formation (2.2.1.1 and 2.2.1.2) of preserving the grouping after switching will be filled before the buffer empties of BN.Formation after this will cause switching is overflowed, and finally causes packet loss.If BN takies all other behaviors (that is, spin locking) in the system in advance, then can carry out emptying and transmitting specially by BN.This can guarantee to empty and transmit will occur in before any other forwarding.Yet, because long taking in advance can have adverse effect to system health, so BN should more pay close attention to this method.In all cases, described scheme is that implementation is specific.

2.2.3 the maximum cushioning service duration

Should come in BN, can manage the maximum figure of ground configuration service duration by definition as in the maximum duration of the bp value described in the 2.1.3.1 joint and the full-size of buffer.These boundaries should be considered the available local resource of BN.Described boundary should be considered to the non negotiable value.

2.2.4 communication link to MN

Suppose that the signal transmission (BCP) between MN and BN is present in switching before with afterwards.

3. cushion control protocol (BCP)

BCP is the control protocol that MN is used for asking the buffering service at BN place.It is by request and the simple and reliable message transfer service of response signal to forming.BCP can be defined as New Deal, or is defined as the expansion to existing protocol (for example PANA, SIP and mobile IP (v4/v6)), perhaps is defined as the expansion to link layer protocol.For example, in mobile IP v 6, can in Binding Update/acknowledgement message exchange, define new mobility option with TLV form carrying BCP.In PANA, definable can be additional to the BCP AVP of PUR/PUA message.Can adopt other method, as long as can meet the requirement that the BCP signal transmits.In all cases, the transmission of BCP signal and coding can be specific to each agreements of carrying BCP.

3.1 protocol signal

As rule, request signal sends to BN from MN; In response to request signal, response signal sends to MN from BN.BN never produces request signal.Request signails carry is about the parameter of request, and response signal contains object code.Keep reliability by using transmission time limit, re-transmission and fault processing behavior.Signal below BCP uses is right.

3.1.1 BReq[initial] and BAns[initial]

Always at first between MN and BN, exchange these signals.Described signal is used for setting up the buffering service described in the 3.3.1 joint.These signals have following form.

BReq[initial]＝{id，bp，tc，bsz，p}

Id-is used for identifying uniquely to BN the MN Id of MN.This can be mac address or the source address of MN.

The bp-buffer circle

The specific flow of application that tc-will classify and cushion

The bsz-suggestion will the assigned buffers size

P-is for the FP of EOS, and effective value is lost, transmitted or abandons by signal

The flag{m}-request marks

Whether set bsz is compulsory and can not consults m-

BAns[initial]＝{id，bp，bsz，rcode}

Id-is used for identifying uniquely to BN the MN Id of MN.This can be mac address or the source address of MN.

Bp-is used for the buffer circle of this service

Bsz-is the buffer sizes of this service assignment

The object code that rcode-BN provides

3.1.2 BReq[ext] and BAns[ext]

These signals of exchange after setting up the buffering service and before or after the switching cycle at MN.They are used for expanding the parameter as the described buffering service of 3.3.2 joint.

BReq[ext]＝{id，seq，bp，bsz，p，coa}

Id-is at BReq[initial] in the MN id that sends

Seq-burst number

The buffer circle that bp-is additional can be zero (0)

The buffer sizes that bsz-is additional can be zero (0)

P-is for the new FP of EOS, and effective value is dropped, transmits or abandons by signal

The current C oA of coa-MN

BAns[ext]＝{id，seq，bp，bsz，rcode}

Id-is at BReq[initial] in the MN id that sends

Seq-burst number, must and BReq[ext] coupling

Bp-is used for the new buffer circle of this service

Bsz-is the new buffer sizes of this service assignment

The object code that rcode-BN provides

3.1.3 BReq[stop] and BAns[stop]

Exchange these signals in order to finish the buffering service, described in the 3.3.3 joint.

BReq[stop]＝{id，p，coa}

Id-is at BReq[initial] in the MN id that sends

P-stops FP for EOS, and effective value is dropped, transmits or abandons by signal

The current C oA of coa-MN

BAns[stop]＝{id，rcode}

Id-is at BReq[initial] in the MN id that sends

The object code that rcode-BN provides

3.2 Service Properties

BCP also creates Service Properties (state information) in BN.These attributes can comprise following content:

MN?Id(id)；

Buffer circle (bp);

The buffer sizes (bsz) of consulting;

Traffic classes (tc) parameter;

FP, current EOS empties strategy;

Last extended requests sequence number;

Current MN CoA;

Previous MN CoA.

Can in the request stage described in the 3.2.1 joint, distribute these attributes.In case receive effective request signal or other local event, BN just upgrades described property value.Attributes lifetime is limited to the duration of service.If satisfy positive or negative EOS, then BN discharges the resource that is occupied by these attributes.

3.3 service stage

Usually, BCP can be divided into three phases with the BN service.The buffering service must be finished these stages in turn.

3.3.1 service request phases

Service request phases is to be used for setting up the starting stage that buffering is served into MN.Service request phases is included in the single BReq[initial that exchanges between MN and the BN]/BAns[initial] signal, to consult buffer requirement and to determine whether BN can satisfy these demands.If BN can support MN, distribution state information then, and begin the buffering of MN flow immediately.Then, BN sends the BAns[initial that has the successful object code (rcode) of indication to MN].If the recommended value that BN provides MN is made adjustment and service can be provided, then also begin the buffering service, simultaneously BAns[initial] comprise the rcode of misdirection.If BN can not provide service, then do not distribute state information, and BN sends the BAns[initial that has suitable error code].MN is at initial BReq[initial] in parameter below sending.

3.3.1.1 buffer circle

Because MN can learn the length (this can be the estimated value of switching cycle) of buffer circle in advance, so MN can send to BN with this value.Described in the 2.2.3 joint, if this value is no more than the maximum figure of local configuration, then BN can will should be worth as bp.If should value under maximum figure, then BN should be at BAns[initial] in rcode is arranged to represent successfully.If should value surpass maximum figure, then BN can refuse buffer requests or use maximum figure as the bp value.Under any situation, BN should be by at BAns[initial] in rcode is arranged to represent the decision notice MN of mistake with it.If BN uses MN to think inappropriate maximum, then MN has the right to choose of the service of termination.In the case, MN can enter immediately as at termination phase described in the 3.3.3 joint.

3.3.1.2 buffer sizes (bsz)

MN can advise will be at the employed bsz of viability BN.Because MN can learn employed application and corresponding expectation flow rate and channel situation in advance, so this is possible.In conjunction with switching cycle, MN can calculate and hold the required rational bsz of sorting flow.Yet the bsz that MN provided is suggestive to BN.BN has final authority based on local available resources to the actual bsz that will use.If BN can accept the bsz of MN suggestion, then BN can be at BAns[initial] in the successful rcode of expression is set, if BN can not accept the value of being advised, then BN can use the maximum figure of local configuration, and by at BAns[initial] in rcode is arranged to represent that mistake notifies MN with its decision.If the bsz that BN proposes is improper, then MN has the right to choose of the service of termination.In the case, MN can enter immediately as at the termination phase described in the 3.3.3 joint.

3.3.1.3 traffic classes (tc)

Acquiescence BN in buffer circle goes to buffering all flows of MN.Yet MN can provide the parameter of the discharge pattern that is cushioned about needs.This be MN to the interested situation of flow (tc) that only cushions particular type under.The form of tc parameter is according to embodiment and difference, and MN can learn this execution mode in advance.

3.3.1.4 empty strategy

The such strategy of FP indication that MN sends: in case satisfy EOS described in the 2.1.3 joint, BN just should execute the grouping that is cushioned.The strategy of current support is to transmit or abandon grouping described in the 2.1.4 joint.Since the service become nonsensical, BReq[initial] in, the regulation all abandon the grouping that is cushioned at any EOS BN the FP value may seem improper.Yet, may there be such situation, described in saving at 2.1.3, MN decides according to the EOS condition that satisfies and executes two strategies that (2) are different.As an example, MN can wish to abandon all groupings when satisfying time limit buffering EOS, and transmits all groupings when explicit signal transmits EOS when satisfying.In the case, acquiescence FP is set to abandon all groupings, sends the follow-up BReq[stop of EOS certainly with signal] can carry the FP that is used to indicate all groupings of forwarding.

At BReq[initial] in the FP that provides also can be configured to sky.In the case, employed FP can be the value of local configuration.

3.3.2 buffer stage

Buffer stage comprises the period that traffic classification and buffering take place.Buffer stage provides the BAns[initial of buffering service at BN with expression in request stage] begin immediately after responding, and when satisfying the EOS condition, finish.During this stage, the commutative one or more extended requests of BN and MN (BReq[ext]/BAns[ext]).Extension request negotiation is finished in each exchange.Extended requests allows MN to consult the property value of having set up again between request stage or previous extended requests commutation period.This makes the buffering service be expanded.In this cycle, also can carry out BReq[stop]/BAns[stop] exchange to end the buffering service.In the case, BReq[stop] FP that provides can execute the strategy of the grouping that abandons all bufferings.

Because handshaking was carried out before or after switching cycle, therefore when carrying out extended requests, should cause concern.Therefore, mobile node carries out synchronously handshaking and switching cycle, to guarantee that network connects available during handshaking.

With BReq[initial] contrast, by BReq[ext] parameter that provides is added in the existing property value.Except FP, the new value that obtains can be obeyed identical restriction and the condition that is applied to initial value in the 3.1.1 joint.Mobile node is at each BReq[ext] in send following parameter.

3.3.2.1 buffer circle

Mobile node can be at BReq[ext] additional switching delay is notified to buffer joint in the signal.At BReq[ext] in the switching value that provides be added to existing switch attribute value, and obey the restriction and the condition of appointment in the 3.3.1.1 joint.For each the new BReq[ext that receives by buffer joint], all repeat this process.To adjusting under the uninterested situation of this particular value, can this parameter be set to zero (0) at mobile node.

3.3.2.2 buffer sizes (bsz)

Mobile node can provide the suggestion of the bsz that also needs about extended requests to buffer joint.At BReq[ext] in the bsz value that provides be added to existing bsz property value, and obey the restriction and the condition of appointment in the 3.3.1.1 joint.For each the new BReq[ext that receives by buffer joint], all repeat this process.To adjusting under the uninterested situation of this particular value, can this parameter be set to zero (0) at mobile node.

3.3.2.3 empty strategy

NM can use BReq[ext] set up the new acquiescence FP that is used for the service of current buffering.When satisfying EOS, buffer joint puts teeth in new FP.If at BReq[ext] in the FP that provides for empty, then this is that the indication buffer joint keeps existing FP property value.If existing property value is empty, then buffer joint should be set to local Configuration Values by the FP property value.

3.3.2.4 CoA information

Also can be with BReq[ext] be used to upgrade the CoA of mobile node, with the convenient forwarding of in the 2.1.5 joint, describing.Thereby transmit under the situation that satisfies EOS certainly in overtime preemption explicit signal of time limit, need be at BReq[ext] go up carrying CoA.At BReq[ext] in carrying CoA parameter also make BCP and buffering node on framework, be independent of environment for use.As example, the buffer joint (as shown in Figure 3) that resides on the mobile node can be notified to buffer joint by the CoA that it is previous, in case the ping-pong of discussing in the 2.1.6 joint.

3.3.3 termination phase

When satisfying EOS, begin termination phase, as described in the 2.1.3 joint, and when the whole resources for the buffering service assignment are released to system, finish.When satisfied EOS certainly and compulsory execution forwarding strategy, buffer joint should be followed the forwarding demand of description in 2.1.5 joint and 2.2 joints.Under the situation that explicit signal transmits, between NM and buffering node, exchange BReq[stop]/BAns[stop] to stop the buffering service.Mobile node should with switching cycle synchronously to guarantee that the network during handshaking is connected.Also can use explicit BReq[stop by mobile node] interrupt cushioning and serve.Wherein have the BReq[stop that executes the FP that abandons grouping when mobile node sends with signal] time, break in service.BReq[stop] have a following parameter.In addition, give mobile node if buffer joint has been determined the packet forward of carrying out buffering, mobile node and buffering node and do not have the tunnel between buffer joint and mobile node on different IP links, then buffer joint also is created to the new tunnel of mobile node.

3.3.3.1 empty strategy

During termination phase, buffer joint should put teeth at BReq[stop] in the FP that provides.If at BReq[stop] in the FP that provides for empty, then buffer joint should put teeth in existing FP property value.The FP that appointment is transmitted should follow the forwarding demand in 2.2 joints.

3.3.3.2 CoA information

If BReq[stop] signaling bearer CoA information, then it should be substituted in BReq[ext] in the previous CoA information of carrying, and should when transmitting the grouping cushioned, use.Under new CoA resides in situation in the IP network that is different from its ownership place, BReq[stop] also can be used as the signal of setting up the IP-IP tunnel.2.1.5 provide details in the joint.

3.4 protocol signal stream

Protocol streams shown in Fig. 4 relates to mobile node switching, traffic classification and buffering, so it provides the general sequence of handshaking.Variable o1 and o2 have defined in buffer stage when network and have been connected the period that effective mobile node and buffering node can occur may exist the time.

3.5 protocol reliability

BCP is a locking stepping agreement, needs to finish existing handshaking before can initiating another handshaking.Simplified the stringency in state-transition in the buffer joint and the re-transmission like this.

BCP uses the overtime and re-transmission of transmission, to detect failure in signal transmits.Repeat requests signal only.If mobile node sends request and do not receive in specifying time out period and replys, then it should retransmit this request.Do not reply if after the maximum times that retransmits having occurred, receive, error condition then in MN, occurs.Transmitting maximum times both overtime and that retransmit should be rational value, to minimize whole delay.Should not retransmit the answer signal that sends by buffer joint.The signal that the buffer joint reply retransmits arbitrarily responds with identical answer signal.If lose with being connected fully of MN, then buffer joint can rely on the hp value to stop the buffering service.

For BReq[ext], buffer joint also should rely on the serial number of this signal association determines the BReq[ext that it receives] whether be re-transmission.The BAns[ext that sends by buffer joint] must provide and be associated with the BReq[ext that this is replied] in the matching order that is equal to of serial number number.Owing to may produce a plurality of BReq[ext]/BAns[ext] exchange, therefore need this processing.BReq[initial]/BAns[initial] and BReq[stop]/BAns[stop] signal do not need the serial number inspection, this be since these exchanges should be respectively in the beginning of buffering service with only occur once between tailend.Also can come supplementary signal validity by the value of checks sequence number.

3.6 in network, find the buffer joint availability

The network entity with in its new network of just shifting to that mobile node can be attempted in existing network sends BReq[initial], to find the availability of buffering service.Mobile node can use the response from network entity to lack to indicate which network that the buffering service is not provided.The response disappearance should be defined as the re-transmission trial of mobile node arrival maximum times but not receive the time of replying.If mobile node does not all receive response from two networks, then there is not service.If mobile node all receives response from two networks, then which network mobile node should select service will be provided, and interrupts the request in nonoptional network.The availability of buffering service perhaps, can be provided by the current mechanism such as DNS or DHCP.

3.7 security consideration

BCP does not provide inherent fail safe.BCP relies on by lower level, IP layer (being IPsec) or to parents' agreement of carrying BCP fail safe is provided, described in 3.8 joints.

3.8 realize considering

But the method and apparatus that exists in the realization using system of buffer joint.For example, in linux system, can carry out traffic classification by using network filter (ip table) or flow-control module.Can use these instruments complicated classifying rules to be set based on each stream.In addition, can also realize buffering together with the specific control use traffic of buffer joint control module.

Broad range of the present invention

Though described exemplary embodiment of the present invention at this, but the invention is not restricted to various preferred embodiment described here, but comprise have the equivalent element that it will be understood by those skilled in the art that based on the disclosure, any and whole embodiment of modification, omission, (for example containing the aspect of each embodiment) combination, change and/or variation.Be not limited in this specification based on the language that adopts in the claims or handling the example of describing during the application (its example is interpreted as non-removing property) and broadly explaining the qualification in the claim.For example, in the disclosure, term " preferably " is non-removing property, and expression " preferably, but be not limited thereto ".

In the disclosure and during handling application, under situation about require limiting, will only adopt device to add the qualification that function or step add function for specific rights, following full terms is present in the described qualification: a) clearly statement " device " or " step "; B) function of clearly statement correspondence; And c) do not state structure, material or support the action of this structure.In the disclosure and during handling application, term " the present invention " or " invention " can be used as the one or more aspects that refer in the disclosure.Language of the present invention should be by the incorrect key mark that is interpreted as, should be interpreted as being applied to all aspects or embodiment improperly (promptly, should be understood that the present invention has many aspects and embodiment), and should be interpreted as limiting the scope of the application or claim improperly.In the disclosure and during handling application, term " embodiment " can be used to describe any aspect, characteristics, process or step and combination in any and/or its arbitrary portion etc.In certain embodiments, various embodiment can comprise overlapping feature.In the disclosure, can adopt: " for example " of expression " giving an example " hereinafter to be referred as term.

Claims (22)

1. one kind switches and does not have the method for packet loss, wherein mobile device moves along the network of a series of vicinities, described method comprises: at couple in router, the network node of the network edge that approaching described mobile device is leaving, the network node of the network edge that approaching described mobile device is being shifted to, at least one place in mobile node and the communication node, the packet buffer of each mobile device is provided, when the period that described mobile node does not have network to connect during it is run into when a network moves to another network, and when finishing described hand-off process, the packet forward that is cushioned is given described mobile node and/or transmitted the described grouping that cushions from described mobile node.

2. the method for claim 1, wherein in conjunction with existing mobility protocol, access protocol, or as independently network or link layer mechanism are used buffering.

3. method as claimed in claim 2, wherein, the protocol definition that will be used to cushion control is independent agreement, buffer system and mobility management protocol are generally compatible thus.

4. method as claimed in claim 3 comprises: the packet forward that definition is used for being cushioned creates a mechanism for the tunnel of mobile node, so that the independence of mobility management protocol to be provided.

5. method as claimed in claim 3 comprises: as the part of described forwarding, nCoA is revised as in the purpose IP address of the described grouping that cushions, as the mechanism of the complexity that is used to reduce tunnel management.

6. method as claimed in claim 3 comprises: nCoA is revised as in the purpose IP address of the described grouping that cushions.

7. the method for claim 1 further comprises: by defined agreement is provided at link layer, be controlled between transfer period the buffering of packets at the access point place.

8. the method for claim 1, further comprise: be buffered in the described buffer joint that is in the transmission during the switching cycle and divide into groups, and, just empty the grouping that is cushioned, and the buffering packets that is emptied is transmitted to the described mobile device that is positioned at reposition in case finish switching.

9. the method for claim 1, further comprise: be buffered in the grouping of going out from described mobile device during the switching cycle, and be in the buffer joint at network edge grouping is cushioned, thereby between transfer period, provide bidirectional buffering, and on both direction, compensate packet loss.

10. the method for claim 1 further comprises: when described mobile node is carried out active scan, at the buffer joint that is arranged in access point grouping is cushioned.

11. the method for claim 1, wherein, before switching, flow before switching arrives described mobile device via previous network, when described mobile device is prepared to move to new network, described mobile device sends its intention to described buffer joint with signal, and described buffer joint begins still cushioning by described previous forwarded and the flow of going to described mobile device, in case finish switching, the grouping that described mobile device is just cushioned to empty with the described buffer joint of signalisation, and give the described mobile device be arranged in described new network with the described packet forward that cushions, described buffer joint is couple in router formerly, on next couple in router and/or the described mobile device.

12. the method for claim 1, further comprise: in the node as network entity grouping is cushioned, wherein said network entity intercepting is gone to the grouping of one or more mobile devices and temporarily described grouping is cushioned to avoid packet loss when described each mobile device is in handoff procedure; In described network entity buffer joint, the grouping of each mobile node is classified; After finishing switching, suitably transmit the grouping that is cushioned, and wherein, cushion the mobile device of service with each step in these steps of signalisation by request.

13. method as claimed in claim 12 further comprises: use BReq[initial by described mobile node] classification of the indication grouping that will be cushioned, only to cushion the interested grouping of described mobile node by the described buffer joint of signalisation.

14. the method for claim 1, wherein, described mobile device uses the buffering control protocol to the service of described buffer joint request buffering, described agreement transmits buffer requests result and error condition, described buffer joint responds request but does not generate request, described buffering service is a transient service, and receives BReq[initial from mobile device when buffer joint] and begin to cushion when having set up the value of being consulted.

15. the method for claim 1, wherein, the BReq[initial that sends by described mobile device] and follow-up BReq indicate the strategy of described buffer joint to the grouping compulsory execution of any buffering, emptying strategy is executed by described buffer joint, the described strategy that empties is to transmit or abandon the grouping that is cushioned, and mechanism sends to described mobile device with explicit error notification outside use buffering control protocol or the band.

16. method as claimed in claim 7, wherein, the existing agreement that empties is transmitted the grouping that is cushioned after sure service finishes, wherein when described buffer joint begins to empty the grouping that is cushioned, it has been provided with the current Care-of Address of described mobile device, and described buffering control protocol indicates the current Care-of Address of described mobile node to described buffer joint.

17. method as claimed in claim 16, wherein, when described mobile device and described buffer joint are in the identical IP subnet, by using address resolution protocol that described grouping this locality of cushioning is sent to described mobile device, and when described mobile device and described buffer joint are on the different IP link, the grouping that is cushioned is sent to its next hop router towards described mobile device, and use the IP routing that the grouping that is cushioned is sent to described mobile device.

18. method as claimed in claim 2 wherein, is used the buffering service of described buffering control protocol with request buffer joint place by described mobile device, described buffering control protocol is new agreement, the expansion of existing protocol or the expansion of link layer protocol.

19. the method for claim 1, wherein, during crossing over, buffer stage takes place the period of traffic classification and buffering, described buffer stage is providing the BAns[initial of buffering service at described buffer joint with indication in request stage] begin immediately after responding, and when satisfying the condition of service end, finish, in described buffer stage, described buffer joint and described mobile device can exchange one or more extended requests, and wherein, extension request negotiation is finished in each exchange.

20. method as claimed in claim 19.Wherein, be positioned under the situation at same place at described buffer joint and described mobile device, extension request negotiation is carried out in this locality in described mobile device.

21. one kind is used to switch and does not have the system of packet loss, wherein mobile device moves along a series of adjacent networks, and the stage that does not have network to connect during mobile node is run into, described system comprises: at couple in router, near the described network node that moves the network edge that is leaving, the network node of the network edge that approaching described mobile device is being shifted to, the packet buffer of each mobile device at mobile node and/or communication node place, wherein when finishing handoff procedure, described buffer node is given the packet forward that is cushioned described mobile node and/or is transmitted the described grouping that cushions from described mobile node.

22. system as claimed in claim 21, described system also comprises:

The packet buffer of each mobile device, the network node of the network node of the network edge that it is positioned at couple in router, leaving near described mobile device and/or the network edge shifted near described mobile device;

Mobile node;

Communication node;

Buffering control protocol, the independent agreement that it is defined as and mobility management protocol is general compatible, described buffering control protocol between described mobile device and described mobile node with signals events and parameter;

The queuing and the forwarding mechanism that are used for buffering packets;

Buffer joint in described mobile device, it is used for the grouping of going out during described mobile device buffer joint is buffered in switching cycle, buffering packets in the buffer joint of network edge, described buffer joint is providing bidirectional buffering and compensating packet loss on both direction between transfer period, described buffer joint is that intercepting is gone to the grouping of one or more mobile devices and temporarily described grouping cushioned to avoid the network entity of packet loss when described each mobile device is in handoff procedure, described buffer joint is classified to the grouping of each mobile node, and suitably transmits the grouping that is cushioned after finishing switching; And

Address resolution protocol, when described mobile device and described buffer joint are in the identical IP subnet, described grouping this locality of cushioning is sent to described mobile device, and when described mobile device and described buffer joint are in the different IP link, the described grouping that cushions is sent to next hop router towards described mobile device, and use the IP routing to send the grouping that is cushioned to described mobile device.

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