TWI312247B - Link layer assisted seamless mobility handoff method for wireless local area networks - Google Patents

Description

1312247 λ

IX. INSTRUCTIONS: [Technical Field of the Invention] The present invention relates to a method for applying to a wireless zone, by shortening the interruption time of the link layer exchange between different network areas to ensure the continuity of data transmission. ^度游=The communication quality of the network. And h to the wireless area [previous technology] In the future of advanced technology, the use of the network is indispensable - part, and the more _ road can = the more the life in the day, the wireless network environment is now Gradually two = work is also getting more and more 'but the existing hand-over method makes you want to use the second solution, the communication caused by roaming interrupts it!! Change H' (four) 岐 requirements (four) _ network Services (eg. Image U) 'The existing laws give users reasonable assurance in terms of communication quality. Yu Wanqi has nothing and the biggest value and progress of the technology we propose is to shorten the interruption caused by roaming in a relatively short period of time, so that even if it is an immediacy network transmission, the network Communication quality can also be guaranteed within a reasonable range. If the proposed technology can be smoothly promoted to commercial products, then I believe that it will help and greatly help many digital products. Taking mobile phones as an example, developers can develop mobile phones with the Internet as the backbone of communication to obtain high-speed data transmission speed. In this way, the mobile phone will no longer be just a tool for talking. It can also have the function of video calling, and with our proposed technology, the delay of the transmission can be reduced to a very low range. I don't feel the transmission of 5 1312247, delay, and the like, and the mobile communication speed of GSM, GPRS and other technologies on the market is not as fast. In the network development environment in recent years, the IEEE 802.11 standard Wireless Local Area Networks (WLANs) have experienced tremendous growth, and the number of users of wireless area networks has increased significantly. The advantages of wireless local area networks are the convenient connection and high-speed transmission efficiency, so that the technology of multimedia transmission and point-to-point transmission can be widely applied. According to the IEEE 802.11 network MAC standard, the network is divided into AD φ H〇c and Infrastructure modules, wherein in the AD Hoc module, all wireless nodes are connected to each other and establish a peer-to-peer communication system. In the Infrastructure module, an Access Point (AP) is used for data transmission of all wireless nodes. The infrastructure module is a relatively complete network system. Therefore, most of the current wireless area networks use the Infrastructure module as their network architecture system, and the present invention is directed to the network system of the Infrastructure module to the user. Develop and improve using the situation when roaming. References to “Mobility” by D. Saha, A. Mukherjee and M. Chakraborty in November 2004 / pages 33 to 34

Support in IP: A Survey of Related Protocols, we know that in the past few years, there have been many mobile communication protocols developed to implement roaming on wireless networks, and can be divided into single areas according to the connected subnets. Micromobiiity, Macromobility, and Global Mobility. In general, the primary purpose of the Mobile Protocol is to ensure continuity of regional and cross-regional mobility. And uninterrupted data transmission 'and the regional mobile system is a communication method of a larger time range' and the mobile communication protocol is used to link the communication path after the 1312247 roaming.

Mobile IP is a method commonly used for mobile communication in mobile communication. The Mobile IP provides mobility at the layer; the line node, and allows the wireless node to not lose the network ^ cable. In the case of the mobile IP, the mobile agent must perform the second tour in the wireless local area network. In the Mobile IP, a mobile agent (MA) must be set up on the limited network, wherein the mobile agent can be divided into home agents ( Home Agent, HA) and the forwarding agent (Foreign Agem, the mobile agent will periodically propagate the IP IP Advertisement packet in the wireless local area network. Net, when swimming to another subnet, the wireless node will:: to the action Ip princess sent by the corresponding corresponding forwarding agent, after some verification, there will be an IP-p transmission. The round-up. The road is built, and from then on, the packet data exchanged between the wireless node and the server is all transmitted through the two-way transmission channel. 1 The wireless node roams again to a new external child. network The line node must be associated with the new foreign material, and the relationship between the network and the wireless network that is connected to the previous forwarding agent can be removed. : Change is called Mobile IP change. The change is not yet, the time, * in the wireless node is not connected with the cable: the data shipped to the wireless node can not be transported Therefore, the delay time of changing hands & may lead to the decline of the quality of the transmission wheel. The faster the transmission of the network system, the more the packet will be sealed and the network will belong to the TCP network. , is - can be transmitted, and has a retransmission mechanism (Ret face mission P〇hCy) 'Therefore, the impact of the handoff delay is more serious. @How to shorten the 1312247 hand delay becomes the development of the wireless local area network [Important content] The purpose of this issue is to make the _ wireless 纟 _ segment between the users because of the mobile _ (four) into the hand (a) to ensure data transmission 丄i: and _ road The communication quality is within a reasonable range of no. 无:: The link of the monthly network is supplemented by Group, and the former n-tier 士士区1财系 contains a chain layer mode section] The aforementioned method includes the following = = the aforementioned first-network section and enters the aforementioned second network Detect! ^ System 阜 to arrow n — 7" District slave, the wireless node transmits a second base station connected to the base station broadcast; the second receives the control message 2 and the key layer module ίί: private link (4) No seams are exchanged to the wireless node: ί; (2) = before the sudden, the data can be transmitted and most of the changes, the impact of delays in the hand-changing steps, the method of invention. Since the hair can be modified by a small part to join the network of the link layer without IPW or ΙΡν6, it is proved that there is a stomach. The method of the present invention passes the test quality, and is transmitted in the UDPm=plus and _way handoff process. The ~fcp network of the present invention is applicable. For the purpose of illustration, it is intended to be clear and not to be based on the following figures:: this: drawings and examples, just as saying 1312247 [Embodiment] The present invention relates to Link Layer Assisted Seamless Mobility for Wireless LAN

Handoff Protocol (LASP), which is mainly used to shorten the communication interruption time caused by the movement of users roaming between different wireless local area network segments, and achieve efficient and efficient handoff (Handoff) to ensure the continuity of data transmission. 'To maintain the communication quality of the network. The invention is applied to the link layer of the wireless local area network to assist the seamless change hand φ method to provide a software detection mode to detect the action of changing the link layer; triggering after detecting a chain change hand movement A control message is used to establish a fast transfer path with the control message; and the registration procedure in the wireless network handoff agreement is accelerated, the handoff delay time is reduced, and the packet loss caused by the hand change action is avoided. In a wireless LAN (Infrastructure Mode) based on the IEEE 802.11 specification, a wireless node (M〇bne Node, MN) can be compared with a wireless network card (wireless Netw〇rk interface Card, WNIC). The second two different base stations (Access p〇ing, Ap) # signal strength and weakness - and then detect the movement of the wireless node, and the initial step of a chain of hands to change hands. Although all wireless network cards that meet the ΙΕΕΕ 8〇2·ΐι specifications are built into the firmware, they do not send any interrupt signals to notify the system, but the wireless network. The road card can still use the hardware control method to allow the software to detect the base station to which the wireless network card is currently connected. Refer to Infine〇n Techn〇i〇gy published in May 2005, AE) M8262 PCI/Cardbus/Mini-PCI WLAN MAC/BBP Controller Preliminary Data Sheet, Rev. 1312247, L1” The 'ADM8262 is a Base Band Processor/Medium Aeeess Control (BBP/MAC) controller that complies with the IEEE 802.11 specification. The controller uses two ABDA1-CSR26 and BSSID0_CSR27. The 4-bytes memory record is currently connected to the base station, and the movement of the controller can be detected by the software detection method. The present invention is applied to the link layer of the wireless local area network. The seam replacement method is referred to by S. Sharma, N. Zhu and T. Chiueh in the May 2004 IEEE Journal on Selected Areas in Communication, Volume 22, No. 4, pp. 643-652. Latency Mobile IP for Infrastructure-Mode Wireless LANs. Using the hardware function of the wireless network card to detect the relevant base station currently connected to the wireless network card by means of software detection, thereby detecting the absence The roaming situation of the node. The detection frequency determines the motion detection time of the wireless node, and each link layer change takes about several milliseconds. Therefore, the periodic Timer Service Routine can effectively detect the link. Layer change action. Refer to the first figure for the algorithm for detecting wireless node movement using software detection mode, where 'cun*ent_AP indicates the base station of the current wireless node, Candidate_AP indicates the candidate base station' and pr〇bed_Ap indicates The measured base station. Because the probability of the error returned by the 演 algorithm is about 0.4%, the value of the buffer value (Threshold) is set to 2 bit 3 to avoid unwanted control messages. The transfer is driven. Since the software detection requires only simple reading, comparison, and incremental actions, it does not have a significant performance impact on the Timer Service Routine. In the conventional wireless local area network, when a wireless node When roaming from one regional network to another, the data 1312247 that is intended to be transmitted to the wireless node is waiting for the wireless node to complete the handover. After the beginning of that path of the wireless nodes • diameter 'and for transmission of data. The link assisted seamless handover method of the present invention applied to a wireless local area network establishes a fast transfer path (Fast Data F〇rwarding) before the wireless node completes its handover step.

Path) 'Transfer the data to be transmitted to the wireless node to the destination on the correct transfer path, so that the data can be continuously received by the wireless node, avoiding the interruption of transmission caused by long time change time. And a large amount of data is missing' to achieve the purpose of Fast Data F〇rwarding. # 。, The present invention provides a control message in the fast transfer of the data, called RUM (R〇utmg Update Message) message, the data transfer path is changed by the RUM message, and the second picture is the RUM message. Architecture diagram, . Due to the data transmitted on the network, the wireless network or the wired network may be used as the transmission interface. Therefore, the RUM message must comply with the 802.11 standard and the 802.3 standard, and the standard of 8〇2.η and 8〇2 3 Fast format conversion between standards. The RUM message contains a set of information fields, which are in the packet conforming to the 8〇2 η standard, and the information field is located in the Sequence Control block of the Header. Among the 802.3-compliant packets, the information block is located in the Type header of the packet header. The group of information blocks includes a BA-Sent field, a ForwardingJBit block, an ipver rot, a reserved block, and a seqUence Number column. Bit. The size of the BA transmission block is lbtis, which is used to indicate whether the RUM message is transmitted by the buffer agent; the size of the forwarding block is lbtis, indicating whether the RUM message has been chained. The group (L2_M〇dule) is transferred as a bridge or switch; the size of the IP version is lbtis,

11 1312247 is used to indicate the ip format (IPv4, IPv6) stored in the content; the reserved field size is 5bits, which is reserved for other agreements to use or store related information; and the size of the serial number block For gbtis, to record the number of times a wireless node transmits RUM messages, each time a wireless node transmits a RUM message, the sequence number of the RUM message is increased, so that the link layer module or the buffer agent can By comparing the value of the message block of the RUM message to determine whether the received RUM message is a newer RUM message transmitted by the wireless node, the link layer module or the buffer agent is prevented from being delayed by the older RUM message. Affected. Since the information block of the RUM message can be stored in the 802.il-compliant packet and the 802.3-compliant packet, the information field can be used when converting a format between 802.11 and 802.3 standards. Stored in the packet. When a base station receives a RUM message from a wireless node and wants to transfer it to a wired network, the base station converts the RUM message from the 802.11 standard packet to the 802.3 standard packet, and controls the original sequence to be blocked. The group of information blocking content is copied and written into the type block of the 802.3 standard packet. The RUM message is used to change the forwarding path of the data. When a link layer module receives a RUM message, the link layer module forwards the RUM message to all but the mouthpiece that receives the RUM message. Import and update the records in the Forward Database Table (FDB Table) based on the MAC (Media Access Control) address in the received RUM message. The RUM message can be sent by a wireless node or a Buffer Agent (BA). The buffer agent cooperates with and connects to a mobile agent (MA) roaming handoff step. The buffer agent includes a reference table for recording the IP address and MAC address of all wireless nodes connected to the mobile agent.

:S 12 1312247 - The action agent can be a Home Agent (HA) or a Foreign Agent (FA). Since the base station transmits data by the link layer, when the transmitted packet fails to transmit, the base station can temporarily store the failed packet to the buffer to perform the retransmission mechanism (Retransmissi〇n). When a base station receives a RUM message from a wired network, updates the record in the forwarding data table, and the base station compares the RUM message with the packet temporarily stored in the buffer, when the buffer is stored in the buffer The target MAC address is the same as the MAC address of the RUM message, and the base station forwards the same packet to the destination according to the correct forwarding path according to the RUM message. By updating the forwarding data table with the RUM message, the base station can transfer the temporarily stored packet to the correct destination before the handover is completed, so as to avoid the loss of the packet data caused by the change of the wireless node. Referring to the second brother, a fast transfer algorithm is established for the link layer module. When a link layer module receives a RUM message, the link layer & group transfers the RUM message to Receiving all the ports other than the receiving port of the RUM message, and broadcasting the message; and updating the forwarding data table of the link layer module by using the MAC address of the RUM message, and establishing a fast forwarding Path, in which the fast forwarding path only needs to be 2 times the Expire Time, and does not impose too much burden on the link layer module. θ When a wireless node detects different When the wireless local area network roams, or when a buffer agent receives a Buffer Notification Message, the wireless node or the buffer agent sends a RUM message. If the message is sent by a wireless node, the MAC address of the RUM message is the same as the MAC address of the wireless node; and when the RUM message is sent by a buffer, the RUM message is sent. MAC address, and the buffer generation The VIAC address included in the buffer notification message received by the administrator is the same. When a wireless node makes a change, the buffer agent receives the data to be transmitted to the wireless node, and completes the Mobile IP at the wireless node. Before the registration mechanism is changed, the received data is forwarded to the correct destination. When the buffer agent receives a RUM message, wherein the MAC address of the RUM message is included in the reference table of the buffer agent, and When the forwarding code of the rum message is 1, the buffer agent uses the proxy ARP (Address).

Resolution Protocol (ARP) 'Receives the data to be transmitted to the wireless node described by the RUM message φ and establishes a Temporary Fast Data Forwarding Path to forward the received data to the correct destination. . When the wireless node completes the handover, the buffering agent stops the receiving and forwarding actions. By using the buffer agent, the data to be transmitted can be transmitted to the destination in the correct transfer path before the wireless node completes the handover, thereby enabling the data to be continuously received by the wireless node during the handover. Waiting for a long time to change hands caused a lot of data loss. Due to the long-term change of the wireless network, the transmission delay and data loss in the handover process are caused. Reference H. Yokota, A. Idoue, T.

Hasegawa and T. Kato; 2〇〇2 years of "Link" by M05/COM

Layer Assisted Mobile IP Fast Handoff Method over Wireless LAN Networks,,. In general, the agent request (Agent s〇lichati〇n, AS) and Agent Advertisement (AA) spend 2000-3000 milliseconds (ms) on the parent of Mobile IP, and occupy the Mobile IP change step. Most of the time. Therefore, shortening the exchange of proxy requests and proxy announcements can effectively shorten the time for handoffs. Since the proxy announcement is periodically broadcast by the mobile agent, the buffer agent who is connected to the action agent can store the latest proxy announcement for quick reply. * Refer to the fourth figure for the buffer agent to receive the RUM message operation table. When a buffer agent receives a RUM message, when the MAC address of the RUM message does not exist in the buffer agent's forwarding data table, to ^ The value of the transfer field of the RUM message is 〇, indicating that the mobile agent connected to the buffer agent is a routing agent to the wireless node transmitting the RUM message, so the buffer agent can be called It is a bypass buffer agent (fBA). The routing buffer agent treats the received RUM message as a proxy request and transmits the stored latest proxy advertisement to the wireless node transmitting the RU message, and prevents other wireless nodes from being affected by the proxy request. . After receiving the proxy announcement, the wireless node can directly perform the registration procedure of the Mobile IP handover, thereby greatly shortening the registration time of the handover to 2 or 3 milliseconds. In order to reduce the data loss caused by the hands-on registration procedure of the linkless module, the wireless node adds the address of its home agent to the RUM message to be transmitted. When a routing buffer agent receives a Rum message, the routing buffer agent can (4) the version of the RUM message to block the address of the home address, and write the MAC address obtained from the RUM message to the buffer. Notifying the message, and transmitting the buffer notification message to the decision-making agent, the agent can receive a buffer notification message, which can be called a buffer agent (10) A). After the wireless Λ Λ 并 并 传送 传送 — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — Mode) - short time to receive all the data to be transmitted to the wireless node that is roaming. After the Mobile IP registration procedure of the wireless network is completed, all the data stored in the buffer can be transferred by the path established above. It is passed to the forwarding agent and can be correctly transmitted to the wireless node. The fifth drawing of the present invention is a system for implementing a link-assisted seamless hand changing method for a wireless local area network. The network environment is divided into a plurality of switches (504) 505 by a router (R) 508 to be divided into a plurality of sub-networks, and the exchanges 504, 505 are connected to a plurality of base stations. 1, 5 〇 2, 5 〇 3 to cut the subnet ^ into a plurality of network segments. Each subnet switch 5 〇 4, 5 〇 5 points and 2 coincidence a mobile agent 506, 507 To handle the communication of the wireless network, a Corresponding Node (CN) 51 (H|i is any network node that communicates with the wireless node, and is connected to the router by the Internet. The wireless node 5〇〇 From the base station 5〇1. The tour to the base station 503 can be divided into three modes: the ground port 502 diffuse mode 1: when a wireless node 500 is covered by the network covered by the base station 501 network segment 'After the wireless node 5 is separated from the base. After the 5G1_ junction is connected, all the data to be shared by the base station % ^= 500 line node 500 before the completion of the change of the link layer is 兮A a △ Appropriate until the non-broadcasting is stored in the buffer of the base station 501 on the 2nd, to avoid the data legacy when the wireless point is changed. When the non-J node is sent out in soft mode, the wireless point 500 will immediately transmit a RU. The second 502 receives the R purchase message, and then the plane rides 16 1312247 and transmits it. To establish a new forwarding path, after receiving the RUM message, the base station 501 stores the data in the buffer with the same destination address as the MAC address included in the RUM message, according to the updated The correct forwarding path is transmitted to the wireless node 500 to avoid data loss caused by the wireless node 500 roaming. After the wireless node 500 sends the RUM message, the first buffer agent and the second buffer agent (not shown) and the link layer module respectively connected with the action agents 506, 507 are also received. Go to the RUM message. After the first buffer agent receives the RUM message, and the transfer code of the RUM message is 〇, and the IP address and the MAC address are already in the reference table of the first buffer agent, the first buffer The agent will ignore and discard the RUM message. Since the wireless node 5 transmitting the RUM message is roaming in the same subnet, the first buffer agent does not need to perform any update action for the roaming. After the link layer module (504, 505) receives the RUM message, the link layer, the group (504, 505) establishes a fast transfer path according to the algorithm shown in the third figure, and at the wireless node 5关闭 Turn off the fast transfer path when you complete the change. After the second buffer agent receives the RUM message, since the RUM message is sent by the link layer module (5〇4), the transfer code of the RUM message is set to 丨, and Because the forwarding code is 1 and there is no matching data in the table, the , and the table, the second buffer agent ignores and discards the RUM message. The mode 2 line, that is, the point 5〇G, is the network segment covered by the network segment roaming port 503 covered by the base station 502. The wireless node 500 enters the 5th, and uses the road roaming' Person 506 is the wireless node

, S 17 1312247 • 5GC) home agent, and the action agent 507 is the agent of the wireless node 500, and the buffer agent connected with the action agent 506 is the home buffer agent, and the mobile agent The buffer agent connected by person 507 is the bypass buffer agent. Although the MIMO wireless point 500 detects the wireless roaming in the software detection mode, the wireless node 500 immediately transmits a RUM message. After receiving the RUM message by the bypass buffer agent, since the forwarding code of the rum message is 〇, and the IP address and the MAc address included in the RUM message do not exist in the reference table of the routing buffer agent Therefore, the routing buffer transmits the latest proxy announcement to the wireless node 500. <= Further description, since the wireless node 500 is the first subnet to which the base station 5〇3 belongs, The sub-network's mobile communication protocol needs to update its data, so when the wireless node 500 receives the proxy announcement, the wireless node 500 begins the mobile IP handover registration procedure. After the switch 505 receives the RUM message, the switch 505 forwards the RUM message out to enable the home buffer agent and the base station 5〇2 to receive the RUJV [message, and build a fast transfer. path. After the home buffer agent receives the RUM message, since the rum message forwarding code is 1, and its IP address and MAC address are both in the reference table, the buffer agent uses the proxy ARP method to receive all The data packet to be transmitted to the wireless node 500. After the base station 502 receives the RUM message, the base station 502 finds all the data having the same MAC address as the RUM message in the stored buffer. The data received by the home buffer agent and the buffer data found by the base station 502 can be transmitted to the wireless node 5 according to the established fast transfer path. Since a link layer module establishes a fast transfer path requiring 1 to 2 times the Expire Time', the method of the present invention takes about 3 seconds to establish a fast turn 1312247-pass path. When the wireless node 500 completes the handover registration, all the data to be transmitted to the wireless node 500 is circulated through the transfer path established by the normal Mobile IP communication protocol. Mode 3: Since a link layer module may not be able to be joined by its home network and the bypass network, this will cause problems in the establishment of a fast transfer path. However, even if the fast transfer path cannot be established, the method of the present invention can still improve the communication quality and reduce the loss of data by shortening the registration time of the changeover. The wireless node 500 still transmits a RUm message when it detects a roaming. After the routing buffer agent receives the RUM message, the routing buffer agent will reply the latest agent announcement to the wireless node 5, and obtain the information of the home agent by the format of the RUM information. Although the wireless node 500 can be accelerated by the proxy announcement, some data packets are still lost during the registration process. In order to reduce the loss of data during the registration process, the method of the present invention utilizes a buffer notification message to enable the bypass buffer agent to 'pass-through the information obtained by the home agent-containing the RUM The MAC address of the message buffers the notification message to the home buffer agent, and by the normal step, the buffer notification message is also transmitted to the home agent. 2. After the buffer agent receives the buffer notification message, the agent is in the short-term mode, and then receives the packet information of the node 500, and transmits the message to the non-RUM message. The MAC address "^ is false = r: = MAc address is the MAC address. The base station 502 temporarily stored in the 丨 J is stored by receiving the pseudo 1312247 RUM message to transmit 'and no material After the money-sending procedure, 'all the buffers to be transferred to the wireless (4) can be transferred by the transfer path established by the MGbile IP-Passing. As described above, the present invention is applied to the wireless area network. The road key-bonding and auxiliary seamless-free hand-over method can effectively achieve high efficiency and fast (Handoff) to ensure the continuity of data transmission, thereby maintaining the communication quality of the network. The system for implementing the method of the present invention is implemented in a real environment, and the sixth diagram is an actual operating environment table according to an embodiment of the present invention, including a CPU, a network card device, and an operating system used by each node. Mobile IP used in the implementation environment The method is the PSU (Portland State University, PSU) method provided by the website http://www.cs.pdx.edu/research/SMN, and is based on the operating system of FreeBSD 4.9. The base of the implementation environment The Taiwanese Department uses the base station of the website mentioned at http://hostap.epitest.fi as the test condition. The base station provided by the website has the function of general base station, and can make a distinction for different channels. The network card used by the wireless node has a software detection method 'to detect roaming of the wireless node. The link layer module uses a router' and the router can be turned on or off according to experimental needs. The base station and the buffer agent have a buffer size of 5 〇〇K bytes' and the part of the wired network is constructed on the 100Base_T network device' and the wireless network part is constructed on the 802.11b standard.

Refer to A. Mishra, M. Shin, and W. Arbaugh's "All Empirical Analysis of the IEEE 20 1312247 802.11 MAC Layer Handoff Process" in the August 2003 ACM SIGCOMM Computer Communication Review, Vol. 33, No. 2 Layer change hand = usually takes 30 i 550 milliseconds (four). Referring to the present invention, the 'slave link handoff step is based on the time when the last block of the original subnet is received, and the end of the first block that receives the new subnet. Reference is made to the seventh figure for the implementation of the method of the invention = =) meter. All hand changes are between 3 〇 and 9 〇 milliseconds; , , : The hands are all completed within 40 to 50 milliseconds, and the average time for all handoff steps is 46.72 亳 冲 ϊ ί J ; In this way, the UD is used by the device; the packet is transmitted to the helmet J J UJJr in 10 seconds to transmit 100 packets. Referring to the eighth, the picture is: and each time the test is moving, the transit time system/indicating method is implemented in a single area (LASP) and does not include the present method. The time method for including the method of the present invention is - the packet is transmitted. Hi pass f time comparison, where the transmission is between. Further, the interval received by the destination node is transmitted in the left half of the eighth figure. Since the statistics of the 37th to the 44th method of the invention (LASP) are transferred to the no-point, the &amp; The temporary storage in the base station for a short period of time will increase significantly, far more than 37 to the 44th packet transmission will cause some packets to extend the transmission time of other packets. Although the material is lost. While the eighth picture is right, time, but the statistics of the package (LASP) can be avoided, it can be seen that j is the loss of the 45th to 53rd packets without using the method of the present invention. , ', when the point is changed, it will cause the first

A 21 1312247 - While the method of the present invention is implemented in a test of cross-regional mobility (Macro/Global • MobiHty) where wireless nodes are roaming across sub-networks in different sub-networks. In this test, according to the specifications of Mobile IP, the broadcast frequency of the proxy announcement is sent once per second. Although increasing the broadcast frequency of the proxy announcement can shorten the time of the handover step, it will cause too many messages to spread over the network. Therefore, it is not appropriate to excessively increase the broadcast frequency of the proxy advertisement. Referring to the ninth A and ninth B diagrams, respectively, a transmission time statistics table for implementing the method of the present invention and not using the method of the present invention in a cross-regional mobile test, in which a device is used A UDP packet of φ 64 bytes is transmitted to the wireless node to calculate the handover time of the wireless node. Reference IXA is an actual test without using the method of the present invention, wherein the transmission interval between packets is 50 milliseconds (ms). As shown in the figure, there is a 2.4 second transmission interruption time in the link layer change process, and 47 packets of data are lost, so it is not suitable for an immediate system that requires high transmission quality. And after the end of the handoff, the transmission time of the packet is greatly increased due to the increase of several routing processes due to the transmission path of the packet.

Reference IXB is a practical test using the method of the present invention, wherein the transmission interval between packets is 1 〇 millisecond (ms), and the left half of ninth B is the statistics using the link layer module. As a result, the right half of Figure IX is the statistical result of not using the link layer module. As shown in the figure, it is not necessary to use the link layer module. The process of changing hands requires about 9 〇 = less (ms), which is much smaller than the test result without using the method of the present invention, and using the two methods of the method. None of the packets were lost. X The left half of Figure IX uses the link layer module, and the changed 29th to 36th (four) packets are temporarily stored in the base station, and are transmitted to the wireless node after receiving the RUM message at the base station. The 37th to 41st packets are 1312247 * temporarily stored in the home buffer agent and then transferred to the wireless node, so the transmission time of the 37th to 41st packets needs to be increased by 2 milliseconds. The right half of Figure IX does not use the link layer module. A buffer agent sends a pseudo RUM message after receiving a buffer notification message, and causes the 45th to 52nd packets temporarily stored by the base station to be transferred. Passed to the home buffer agent, and the 53rd to 57th packets are directly stored in the buffer agent, and the aforementioned temporary storage of the home buffer agent is transferred after the wireless node completes the change of hands. To the wireless node, it takes more milliseconds than the test results using the link layer module. • Referring to Figures 18 and 10B, another method of the present invention is implemented in a cross-regional mobile implementation test in which a communication node is treated as a file server and the wireless node is FTP. The (File Transfer Protocol) method downloads 15 megabytes of data from the server to test the results of the method of the present invention in the TCP network environment. Among them, the TCP aspect uses the IP Mobility published by C. Perkins in August/May 77^.

Support for IPv4" Reno TCP technology, and the receiving end uses a Ddayed ACK technology' and the buffer size of the receiving end is 16K Bytes. Refer to the tenth A picture for the actual test without using the method of the present invention, In the normal hand change process, it will cause a transmission interruption time of 3.35 seconds. Referring to the tenth B picture, the actual test using the method of the present invention, as shown in the figure, the transmission interruption time during the hand change process is only 122. Milliseconds, referring to the test results of the tenth A and tenth B diagrams and the data graph of a static wireless node, it can be seen that the test using the method of the present invention can effectively improve the transmission efficiency. The method is a reliable transmission. When the packet is lost during the transmission process, the transmitter will resend the packet. Referring to Figure 10A, the packet starts to be lost in the 7.4th second, and the handover step is in the first step.

23 1312247 • The second is completed, but due to the TP resend mechanism, the wireless node takes 0.65 seconds to receive the retransmitted data, so the entire transmission interruption time will not end until 10.75 seconds. Refer to rc/V/P published by WR Stevens in J拙·Vol. 1 of 1994. The lower limit of the traditional TCP retransmission mechanism is 1 second and the upper limit is 64 seconds. In the l〇A diagram, TCP resend The time is set to 1 second, so the retransmission time of the first lost packet is at the 8.5th second, and after the packet is resent, the retransmission time is set to 2, and the index is {1, 2, 4 , ..., 64} The rule grows. Therefore, the second retransmission Φ will occur in the first 〇.5 seconds, at which time the packet is resent twice. Because of the change in Mobile IP, The handoff process takes 3 seconds, and the resend mechanism may take 2 to 3 times, so the data resend can cause a handoff interruption time of 3 to 7 seconds. As shown in Figure 10B, due to the transmission to The data of the wireless node may be temporarily stored in the home buffer agent and transferred after the fast forwarding path is established, but since the wireless node still cannot return an acknowledgment (ACK) packet to the communication node, the TCP is In the network environment, the presence or absence of the link layer module does not affect the test results of the method of the present invention. ❿ Reference J. Hoe in 1996 "Improving the Start-up Behavior of a Congestion Control Scheme for TCP" published in August. Due to the loss of multiple packets during the handover process, Reno TCP lost 2 consecutive packets and entered slow start mode (Slow) After the start, the fast resend mechanism will end, which will increase the difficulty of shortening the transmission interruption time of the hand change. Refer to S. Hoyd and T. Henderson's 'The New Reno' published by Shen 7F in April 199.

Modification to TCP’s Fast Recovery Algorithm by NewReno TCP’ or M. Mathis, J. Mahdavi, S. Floyd, and A. Romanow, published in 1996 24 1312247, “TCP Selective Acknowledgment

The SACK method of Options can effectively avoid the problem caused by TCP entering the slow start mode. Since the transmission of RUM messages also has the problem of transmission delay, refer to H. Yokota, A. Idoue, T. Hasegawa and T. Kato. "Link Layer Assisted" published in 2002

Mobile IP Fast Handoff Method over Wireless LAN

Networks" 'When a control message has a transmission delay, the data is transmitted to the incorrect destination, thus invalidating the LLAMIP (Link Layer Assisted Mobile IP) method. The method of the present invention (LASP) uses a sequence number (Sequence Number) In order to avoid the influence of the delay of the control message, after a buffer agent or a link layer module receives a RUM message, the buffer agent or the link layer module can compare the received RUM message by the serial number. The latest RUM message, or only the older RUM message with a transmission delay, can avoid the problem of data transmission to the incorrect destination caused by the transmission delay of the control message. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS It will be apparent to those skilled in the art that various changes and modifications can be made without departing from the scope of the inventions.

25 1312247 [Simple diagram of the diagram 1 The first diagram is a representation of the algorithm for detecting the movement of the wireless node using the software detection method; the second diagram is the architecture diagram of the RUM message; the third diagram is the establishment of the link layer module. A representation of the algorithm of the fast transfer path; the fourth figure is an operation table for the buffer agent to receive the RUM message; the fifth figure is a system architecture diagram of an embodiment of the present invention; and the sixth figure is an actual embodiment of the present invention. The seventh embodiment is a transmission time statistics table of a link layer according to an embodiment of the present invention; the eighth figure is a transmission time statistics table for a single-region mobile test according to an embodiment of the present invention; The transmission time statistics table of the cross-regional mobile test is known; the ninth B is a transmission time statistics table of the cross-regional mobile test according to an embodiment of the present invention; and the tenth A is a cross-regional mobile test of the prior art. Transmission interruption time representation diagram; FIG. 10B is a transmission interruption time data diagram of the cross-regional mobile test according to an embodiment of the present invention; and FIG. 11 is a test result of the tenth A diagram and the tenth B diagram Quiet FIG wireless node comparative data. The main part of the representative symbol: 500 - wireless Lang points 501, 502, 503 ... base station

26 v 1312247

504, 505...switch 506, 507...action agent 508...router 509...internet 510--communication node

27

Claims (1)

1312247 X. Patent application scope: 1. A link layer assisted seamless replacement method for wireless local area network, the wireless local area network includes a link layer module, and the foregoing chain layer module system Connecting the first network segment and the second network segment, the foregoing method includes the following steps: (a) detecting, by a wireless node, whether to leave the first network segment and enter the second network region And (b) if the wireless node enters the second network segment, the foregoing φ line node transmits a control message to a second base station in the second network segment, wherein the foregoing control message includes a sequence number, wherein the sequence number is used to record the number of times the wireless node transmits the control message; (c) the foregoing second base station broadcasts the aforementioned control message; and (d) the foregoing link layer module receives The aforementioned control message is to update the forwarding data table. φ 2. As applied in the first aspect of the patent application, the link layer applied to the wireless local area network assists the seamless hand changing method, wherein the aforementioned link layer module can be a switch or a bridge. 3. The method of claim 1, wherein the control message further comprises a transcode for recording whether the control message is via a link layer. The module was transferred. :s 28 1312247 4. The method as claimed in claim 1, wherein the control message further comprises a format information for recording the aforementioned control message as IPv4. Or the format of IPv6. 5. The method of claim 1, wherein the control message further comprises a MAC address of the wireless node. 6. The method for applying the patent scope range 1 or 5 to a link layer assisted seamless handover method for a wireless local area network, wherein the first network is after the wireless node leaves the first network segment The first base station of the road segment receives all the data to be transmitted to the wireless node, and transfers the data to be transmitted to the wireless node to the wireless node according to the MAC address of the received control message. 7. The method of claim 1, wherein the link layer module transmits the foregoing control message after the step (d), further comprising a transmitting step after the step (d) To the other link layer modules in the wireless local area network, and according to the foregoing control message, change the content of one of the link layer modules to transfer the data table. 8. A link layer assisted seamless handover method for a wireless local area network, wherein the wireless local area network includes first and second sub-networks, and the first sub-network has a first link The layer module is coupled to a first network segment, and the second sub-network has a second link layer module for connecting a second network segment. The method comprises the following steps: : S 29 1312247 ( a) detecting, by a wireless node, whether to leave the first network segment and entering the second network segment, (b) if the wireless node enters the second network segment, the wireless node transmits a control message to a second base station in the second network segment; (c) the foregoing second base station broadcasts the aforementioned control message; (d) the second link layer module receives the foregoing Controlling the message to update the forwarding data table, and transmitting the received control message to the first link layer module of the first sub-network; and (e) the first link layer module is received according to The aforementioned control message updates the forwarding data sheet. 9. The application method of claim 8 is applied to a link layer of a wireless local area network, wherein the link layer module can be a switch or a bridge. 10. The method of claim 8 is applied to a link layer assisted seamless handover method for a wireless local area network, wherein the control message further includes a transcode for recording whether the control message is via a link layer. The module was transferred. 11. The method of claim 8 is applied to a link layer assisted seamless handover method for a wireless local area network, wherein the control message further includes a format information for recording the foregoing control message in an IPv4 or IPv6 format. . 12. If the application scope of the patent application is applied to the link layer of the wireless local area network, the s 30 1312247 auxiliary seamless change method, the complex Φ铪, +, ^, ^, and the control message further include a sequence. Code, the sequence number is used to record the number of control messages. Quote wireless point-to-point communication description 13 · If the application of patent scope item 8 is applied to the auxiliary seamless hand-over method, the chain link layer of the complex c-area network, *-, +, @, 中中After the step (6), a transmission step is further included, and the first button layer module is attached to the control message of the goods receipt. The first sub-theft broadcast is connected to the tV: the eighth item of the patent is applied to the link-free layer handover method of the green-free regional network, wherein the foregoing control message further includes the mac address of the foregoing wireless node. 15. For example, the reference to the data (4) 8 or 14 assists the wireless local area network to facilitate the seamless handover method, wherein after the foregoing wireless node leaves the first network segment, the aforementioned first network One of the road sections - the base station receives all the data to be transmitted to the wireless node, and transfers the data to be transmitted to the wireless node to the wireless node according to the mac address of the received control message. 16. The method as claimed in claim 8 , wherein the second sub-network further comprises a second mobile agent, and the second mobile agent The second buffer agent is connected to the second buffer agent, and the second buffer agent transmits an agent advertisement to the wireless node after receiving the control message to accelerate the Mobile IP registration procedure of the wireless node. ... 31 1312247 17. The method of claim 8, wherein the first sub-network further comprises - a first action agent, and the foregoing a first proxy agent connected to the first proxy agent, after receiving the control message, the first buffer agent receives all the data to be transmitted to the wireless node in a proxy ARP manner, and according to the received control message mac The address is transferred to the wireless node by the stored data to be transmitted to the foregoing wireless node. • 18. The binding layer assisted seamless handoff method applied to the wireless local area network as claimed in claim 16 or the third item, wherein the first and second buffer agents include a reference table, respectively Recording the Ip address and the MAC address of the wireless node connected to the first and second mobile agents, so that the first and second buffer agents can identify whether the transmitter of the received control message is in the same The wireless node of the subnet. 19·=Application of the patent scope No. 8, item 16, or item 17 applies to the link layer assisted seamless handover method of the wireless local area network, wherein the foregoing control further includes a buffer transmission code for recording Whether the aforementioned control message is transmitted by the buffer agent. A key layer assisted seamless handover method for a wireless local area network. The wireless local area network includes first and second sub-networks, and the aforementioned one sub-network has a first network segment. And a first action agent's first action agent and a first buffer agent, and the second child network has a second network segment and a second action agent, the foregoing Second acting agent and linking a second buffer agent 32 1312247 person, the foregoing method comprises the following steps: (a) detecting, by a wireless node, whether to leave the first network segment and entering the second network segment; (b) if the foregoing wireless node enters the a second network segment, wherein the wireless node transmits a control message including a MAC address of the wireless node to a second base station in the second network segment; (c) the second base station broadcast station Receiving the aforementioned control message; (d) the second buffer agent receives the control message and transmits a buffer message to the first buffer agent and the first action agent; (e) the first buffer The agent receives the buffer message and broadcasts a pseudo control message, and receives all data to be transmitted to the wireless node according to the received buffer message; and (f) the first buffer agent after the mobile IP registration is completed , that is, all the data to be transmitted to the foregoing wireless node is transferred to the foregoing wireless node. 21. For example, the application of patent item 20 applies to the link layer of the wireless local area network. The auxiliary seamless hand changing method may be a switch or a bridge. 22. The method as claimed in claim 20, wherein the control message further comprises a transcode for recording whether the control message is via a link layer. The module was transferred. 33 1312247 Auxiliary 20 methods for the link layer layer application in the wireless local area network, wherein the foregoing control message further includes - format / to record the aforementioned control message is IPv4 or IPv6 24. If the patent application scope is not connected Sewing the hand J method in the wireless local area network chain sequence number, the pre-order" to /, the middle of the control message, the step contains a control message, and the above-mentioned wireless node transmits the aforementioned auxiliary The second item applies to the wireless local area network link layer method 'where the aforementioned control message further includes - transmitted ^ &quot; to record whether the aforementioned control message is buffered by the agent The first and second items shall be: the link layer of the wireless local area network, and the method of the hand, wherein the first and second buffer agent reference tables are used to record the first and second action generations, respectively. The person, the IP address of the wireless node and the mac address, enable the above-mentioned =, ., and f buffer agents to recognize whether the transmitter of the received control message is a wireless node located in the same subnet. 27. The method as claimed in claim 2, wherein the second buffer agent receives the foregoing control message and transmits an agent announcement to the wireless node, To speed up the Mobile IP registration procedure of the aforementioned wireless node. 34 1312247 The scope of the patent application is applied to the link layer of the wireless local area network, and there is no seam change method, wherein the buffer notification message further includes the same MAC address as the MAC address included in the control message. site. 29 claiming that the scope of the patent scope is applied to the link layer of the wireless local area network, the helper seam replacement method, wherein the pseudo control message further includes the same MAC address as the MAC address included in the control message. A claim for the scope of the patent scope is applied to the link layer of the wireless local area network to help the seamless handover method, wherein after the foregoing wireless node leaves the first network segment, the first network segment - the base station receives all the materials to be transmitted to the aforementioned wireless node, and transfers the stored data to the aforementioned wireless node to the aforementioned first buffer agent according to the received pseudo control message. Beizhu 31. The link layer assisted seamless hand-over method applied to the wireless local area network as claimed in Item 20 or Item 3 of the patent application, wherein after step (e), another step-step, the aforementioned first-buffer The agent enters the -promiscuous mode after transmitting the pseudo-control message to receive the data transmitted by the aforementioned first-base station to the wireless node. - A kind of secret seamless handover method for the link network of the secret network, the wireless local area network includes a subnet, the subnet includes a network segment and a mobile agent. The foregoing mobile agent is connected to a buffer agent. The foregoing method includes the following steps: ° 35 32. 1312247 (a) The wireless node detects whether to leave the first network segment and enter the foregoing second network. And (b) if the wireless node enters the second network segment, the wireless node transmits a control message including a MAC address of the wireless node to a second one of the second network segments. (c) the aforementioned control message received by the aforementioned base station broadcaster; (d) the buffer agent receives the aforementioned control message and replies an agent announcement to the wireless node; and (e) the aforementioned wireless node receives The aforementioned agent announced and began the registration process of Mobile IP. 36