TWI260138B - Methods and systems for roaming in 802.11 wireless networks - Google Patents

Abstract

The present invention discloses a system and method for fast and smooth roaming in a wireless network with plural access points. In order to keep better communication quality, the client device may have dual-transceiver. One transceiver is applied for transmitting and receiving data packets to and from a current associated access point. Concurrently, the other transceiver would scan for another suitable access point and prepare to re-associate with it. As the communication quality degrades to a predetermined level, which indicates that the linkage between the client device and the currently associated access point might be broken, the transceiver in scanning mode would begin to re-associate with a new access point to reduce the latency time. After that, the transceiver originally in the linking mode would switch to scan for another suitable access point while the other transceiver is associated with the newly associated access point.

Description

1260138 V. Description of the Invention (1) Technical Field of the Invention The present invention relates to a method for quickly roaming in a wireless network of 802.11, which utilizes a network accessor capable of being (access ρ 〇int ; ΑΡ) a user device that searches for another network accessor while communicating, particularly with respect to a method of quickly roaming in the 802.1 wireless network, the method utilizes User device for dual transceivers. [Prior Art] In recent years, the IEEE 802.11 wireless local area network (WLAN) technology has become more and more popular, and its application level is widely existed in people's daily lives, while the computer system is mainly used to access the network. The tool of the road. However, due to the user's requirements for high mobility, there are more and more portable devices with access to the Internet, such as notebook computers, personal digital assistants, smart phones, and W i F i Telephones, etc., with these portable devices, users can access the network from anywhere. - Because the .WLAN communication architecture is based on the regional network infrastructure, the user device can connect to the network through the AP, and each AP has a certain coverage, such as a general network access device in the WLAN system. The radius of the wireless coverage is approximately one hundred to three hundred feet, and its actual size will depend on the power of the ring # and the radio frequency. Thus, the user device can access the network within the coverage of an AP, and such wireless connection settings covering a particular location are generally well suited for small or home offices (S0H0). In addition, in larger areas, such as office buildings, airports, communities, or even metropolitan areas, many APs will need to be deployed to build a broader coverage.

Page 7 1260138_ V. Description of the invention (2) - Wai. Since the user device has a portable nature, the user often carries the user device to move. However, because of the limitation of the WLAN system design, when the user device moves from the coverage of the AP in the connection to the coverage of another AP, it will need to first disconnect the AP from the original connection, and then connect with another AP. Make a link. Between the interruption of the link and the start of the link, the user device will lose the ability to connect to the network for a period of time, for some communication services, such as Internet telephony (V ο IP), video conferencing or instant video strings Streaming, this disconnection will result in poor service quality. Because the delay of roaming is too long, the roaming method across the coverage of neighboring APs is not suitable for portable devices. As can be seen from the above description, the delay time of roaming has a critical influence on the connection of the WLAN communication system, so it is necessary to provide a solution for fast roaming in the WLAN system to enable the user with the user device to move quickly and pass through the number. APs cover the boundaries of the scope, especially in the case of public communication systems with i-wide coverage. SUMMARY OF THE INVENTION In view of the above problems, the present invention provides a system and method for fast and smooth roaming in a wireless network having a plurality of APs. The purpose of the invention is to provide a wireless local area network system that includes a first network access point (AP) and a second network accessor for providing wireless communication. The user device is wirelessly coupled to the first network accessor, wherein the user device is capable of searching for the second network accessor while being connected to the first network accessor. Network management server coupled to

Page 8 J26〇138_ V. Invention Description (3) ~~—— :摅: The second network access device, wherein the first and second network accessors are based on the instructions of the network management server. Determining the access point of the user device = ° In addition, the user device may also include a dual transceiver, that is, the first reception = °. With the second transceiver. The first transceiver is primarily connected in a connected mode to the second network accessor and the second transceiver is in the seek mode to simultaneously access the network accessor. Another object of the affair is to provide a wireless local area network system for the user to set up, the user device includes a first transceiver for communicating with the jj access device, and a second The transceiver is used to search for the first, and the storage device. The first transceiver is connected in the connection mode to the first -= = and the second transceiver searches the second in the search mode. Another aspect of the invention is to provide a method for alkyne in a wireless local area network. First, the user device is connected to the first network access device, and the second network access device. Then, before the communication between the user device and the same sub-fetcher is interrupted, the user device will be connected to the j-network access device, and the user device will then be connected to the first brother, accessing The device searches for the third network accessor at the same time. The above-mentioned network access:,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, The present invention will be described in detail with reference to the preferred embodiments and the accompanying drawings, wherein all of the preferred embodiments of the present invention are merely illustrative, since == I,

(?) 1260138 V. DESCRIPTION OF THE INVENTION (4) In addition to the preferred embodiments herein, the invention is also broadly applicable to other embodiments. The invention is not limited to any embodiment, but should be determined by the scope of the appended claims and its equivalents. Referring to FIG. 1, a preferred embodiment of a system of 80 1 · 1 1 wireless local area network (w i r e 1 e s 1 o c a 1 a r e a n e t w o r k ; W L A N) is presented. The network management server (n e t w 〇 r k m a n a g e m e n t s e r v e r) 1 1 is used to control the system. In general, the network is set up with several network accessors.

(access point; AP) is connected to the Ethernet through a gateway. In the preferred embodiment shown in FIG. 1, a plurality of APs #4 0 - 1 4 7 are each connected to the gateway. The device 1 3 0 - 1 3 2 , and the gateway 1 3 〇 ~ 丨 3 2 can be an AP control seeker (AP c ο ntr ο 1 1 ergateway ). The gateway crying 1 3 0 - 1 3 2 is directly or indirectly connected to the network management server 1 through the Internet, and the network management server 1 1 is also connected to the authorization server (authentication server) 12 . Each network accessor in the system can control the ability of the device to access the Internet according to the instructions of the network management server 1, and the authorization server 丨2 is mainly used for rites. The identity of the user device, the user device access capability or the I user device bill' and the authorization server 丨2 can also store the user's = information in the database. _ #照图二, which is presented in the 8 0 2·11 wireless network system, the concept of rapid diffusion, innovation. In a preferred embodiment of the present invention, the user device has dual-transceivers, that is, the first transceiver and the first transceiver state 2 0 2, to achieve a plurality of network accessors. The purpose of roaming between. The first transceiver 201 is mainly used for transmitting and receiving data with the invention (5), and the second transceiver 2 〇2 also searches for the adjacent AP 2 2 - 2 5 and Be prepared to connect with the most suitable AP. In other words, the search transceiver will be converted to the primary transceiver for data transmission, and the primary transceiver responsible for data transmission will also be converted to the search transceiver. The dual transceivers in the user device of 8 0 2·11 complete each AP replacement by exchanging the two. It should be noted that the present invention can be applied to various kinds of wireless communication, and all devices in this specification comply with the standard of i eee 8 0 2 · 1 1 x, wherein χ includes but not limited to a, b or g . In Fig. 2, when the communication quality between the AP 2 1 and the first transceiver 207 is lowered to the level of g, the second transceiver 2 0 2 will perform the data transmission operation. That is, the first transceiver 2 2 2 can search for another suitable AP while the first transceiver 2 〇 1 is connected to ap 2 1 and before the connection of the first transceiver 2 〇 1 and AP 21 is interrupted. Connect to the appropriate ap 23 found. Therefore, the smooth switching process from AP 2 1 to another AP 23 in the connection will enable the connection to maintain good communication quality and maintain the desired transmission rate. The Tongcheng mouth can be judged according to the wireless signal strength between the user device 20 and the ap 2 1 in the connection and the data transmission rate. This communication quality is mainly used as a decision on when or where to fit another. Ap is the standard for linking to reduce the delay time of the AP switching procedure. It should be understood that the present invention Chen Naran can use other kinds of standards or methods to reduce the delay time. After the brothers are connected to the new a P 2 3, the first transceiver 2 〇 1 will instead search for another suitable AP, ie the second transceiver 2 〇 2 is working. Therefore, the first and second transceivers 20i, 2〇2 will repeatedly exchange their work as tasks' while the user device 20 maintains a good pass in fast roaming.

Page 11 1260138____ V. Description of invention (6) '---- Communication quality. In addition to synchronizing with the transceiver, the standard remote access AP with a number of A 8 8 0 2 · 1 1 wireless networks is used to authorize the feeder 12 By "authorizing" the server 12 to transmit user information to the new link, the user is pre-identified to confirm the identity and to omit the step of reconfirming the identity. However, the system according to the present invention occurs. Inside the device, that is, when the transceivers in the user device are transmitting data with the current connection, the connection data required for the connection with the potential device is obtained and the body is 27 m.:: When αρ When the switching occurs, the user device with the dual transceiver does not hang in advance to know which AP the authentication information needs to be sent to. Figure 4: A wide area 40, which requires several αρ 4〇1_4〇7 to it The scope of the cover, individually around the circle of AP 4〇1-4〇7 4 1 1 4 1 7 represents the signal of each Ap, p, female one π a 丄 叫 ^ called stamp cover. As shown in the figure, it is still blind: it is covered by the signal of any AP. The so-called number of such areas is closely related, that is, if the number of blind spots is usually the same, then vice versa. Because of more, the less the blind area is partially overlapped. When you have: 'Inevitably make the dance" ph ph 4 1 7 service,,?芸~(5) The user of the clothing set is covered by the 417 private direction 盍 盍 416, so that the two ϋ ϋ 范围 范围 范围 重叠 重叠 重叠 重叠 重叠 重叠 重叠 重叠 重叠 重叠 重叠 重叠 重叠 重叠 本 本 本Αρ 4〇$ In the preferred embodiment, 'because of the range of the area, the alternation of ΑΡ and the coverage of ΑΡ406 are generated in this overlapping area 431.

f 12 pages 8 1260138__ V. Description of invention (7) - inside. In order to reduce the blind spots of wireless connections, it is often necessary to overlap the coverage of the AP. The size of the coverage of the AP depends on the noise ratio of the wireless signal and the data transmission rate. The higher the data transmission rate, the higher the ratio of signal to noise, so the data transmission with low signal and noise ratio is low. The rate extends beyond its coverage. Since it is impossible to avoid partial overlap of the coverage of several APs, it is necessary to try to eliminate the signal interference between the APs. Referring to Figure 4, the basic concept is to enable neighboring APs to use different channels to avoid interference from wireless signals. As shown in the figure, the coverage of the coverage is partially overlapped. APs use different channels to avoid interference. The wider overlapping area will allow the search transceivers in the high speed mobile user device to have more time to prepare for the connection with the new AP. As shown in FIG. 5, the user device 50 moves from the coverage area 51 to the coverage area 5 1 6 . Since the user device 50 gradually moves away from the AP 5 0 7 , the user device 5 0 and the AP 5 0 7 The quality of communication will gradually decline and lead to a slower data transmission rate. Moreover, in accordance with a preferred embodiment of the present invention, regardless of the quality of the communication, the user device 50 will continue to search for other suitable APs. In other words, the user device 50 is ready to connect with another AP. The dotted line in Figure 5 represents the user device transmitting a probe packet (opbe Op a eket) to other APs to search for the best AP. When the communication quality is lowered to the preset level, the user device will be connected to another AP 50 6 before the user device and the currently connected A P 5 0 7 connection are disconnected. Therefore, the user device 50 can remain in the connected state and maintain a high data transfer rate. Then, as shown in FIG. 6, the user device 50 and the AP 5 0 6 will be

Page 13 1260138 —

At this point, the user device continues to search for other APs that generate new data links between the inventions (8). When approaching the boundary of the coverage area of the adjacent AP, the helmets from the AP, and the number of the slaves are weak, so that the user device may be interfered by the neighboring user device and cannot receive the signal normally. Figure 7 presents the phenomenon of blackout scenarios in which adjacent channels cause adjacent channels to cause interference between similar user devices. User A and User B are connected to API and AP2, in which user 移 is moving to AP2 and rj is not connected to user B, and communication signal between user B and AP2 is strong enough. The user who uses the same channel is stronger than the AP 1. Since the user B is not connected to the API and is the AP2, the wireless transmission of the user is completely controlled by the AP2, and the API cannot control the user B. B wireless transmission, so the user's communication with the API may be interrupted by the choice. & The network of the present invention can be applied to 8〇2·1 ib/g (2·4GHz band) or -802.11a (5&gt) ; GHz band), even 802.lla/b/g. For a typical simple 8 0 2 llg/b or 8 〇 2·丨la user device, the hardware usually only has one transceiver. At present, 802.11a /g can simultaneously use 80 2·1 lb/g of 2. 4GHz band and 80 2. 1 la of 5GHz band, which can be used for the invention by 8 〇 2 · 1 1 The implementation of the 2 · 4 G Η z or 5 G Η z band and other bands (such as certain licensed bands). The embodiment can apply the concept of dual transceiver to a wireless local area network having a number of A 8 8 0 2 · 1 a / b / g. Furthermore, the present invention is not limited to being physically built in 8 〇 2 ·丨丨User hardware

Page 14 i26〇!38 V. Invention Description (9) One (,, transceiver, if the transceiver and its basic frequency / media access cut ase~band/medium access c〇ntr〇i) deal with crying two t = change between the connection mode and the search mode, you can borrow;; ^ quickly arrest the end of the station to quickly search the AP near the AP to achieve the spoon of the present invention. The AP connection item obtained by this quick search is stored in the memory when the AP is switched. The connection information in the body 5 can be used as a fast roaming. Referring to Figure 8, the rate of data transmission is _ The smaller the data transmission rate, the more the 苴, , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , As shown, , = 22. The area covered by 812 is larger than the coverage: 8. The areas of 812 and 821 and the dry perimeter 8 2 2 are also larger than the coverage 1. The same coverage includes the preferred transmission rate: two (2) and the f range of 8" and: 21 refers to the formula with lower transmission rate. Ranges 81 2 and 82 - coverage will enable dual-receiving crying APs with a large area to prepare for high-speed traversal through each of the more fully owned APs. The invention may be generated as an important part of the 2': two: 5 tiger strength and data transmission speed:: the user device can make the operation mode of the power receiving state can be set to determine whether the AP is switched or not, the high data The transmission rate is used in the search mode 2: transmission mode to utilize the higher transmission rate. Covering the range of 2 gates = the use of the minimum perimeter 811 and the 822 of the weight of the Nie 弁 821 overlap area is greater than the 7 Becco set of transceivers;: 7 ' and the larger overlap area can be owned by More time:: Also use the user to bite, and mouth to another AP, special

1260138 V. INSTRUCTIONS (ίο) Not when the user device has a high degree of mobility. In summary, the present invention is utilized in a dual transceiver in a user device of 8 0 2 .

The concept significantly reduces the delay between the suspension and the AP, so the AP can roam around the wireless with several APs. It is to be understood that those skilled in the art are not limited to the scope of the modifications and the scope of the invention, and the scope should cover the broadest interpretation. The connection of the front A P and re-linking to another fast switching allows the user to install the network at a high speed in the network. However, it can be smoothly explained by the better example. All similar modifications and similar structures should be included in the application below without departing from the spirit and scope of the invention.

Page 16 1260138 _______ I 'Simple diagram of the diagram, [Simple description of the diagram] Figure 1 presents an embodiment of a wireless network system. Figure 2 is a block diagram showing the state of the user device with dual transceivers before the network accessor handoff. Figure 3 is a block diagram showing the state of the user device with dual transceivers after the network accessors are alternated. Figure 4 shows how several network accessors are configured in a wide area. Figure 5 shows the user device in a wireless network with several network accessors and moving before the network accessor alternates. After the six-segment network accessor alternates, the user device is located in the mobile network with several network accessors I and is in motion. Figure 7 shows the blackout scenario. Figure 8 shows the coverage of different transmission rates. [Main component symbol description] • A P network access device (accesspoint) ^ 2 0 user device 2 0 1 first transceiver 2 0 2 second transceiver # 1 - 2 5 network access device

Claims (1)

1260138___ VI. Patent Application Area -1. A wireless local area network (WLAN) system comprising: a first network access point and a second network access device for providing wireless communication; a user device (c1 ientdevice), the wireless device is coupled to the first network access device, wherein the user device is configured to search for the second network access device when connected to the first network access device; And a network management server, the handle is coupled to the first network accessor and the second network accessor, wherein the first network accessor and the second The network accessor determines the access capability of the user device according to the network management server # command. 2. The system of claim 1, wherein the wireless local area network, the user device, the first and second network accessors are all compliant with the IEEE 8 02.11 standard. 3. The system of claim 1, wherein the system further includes an authorization server that is coupled to the network management server to confirm the identity of the user device and grant the user device Access or calculate the bill for the user device. 4. The system of claim 1, wherein the user device comprises a first transceiver and a second transceiver, wherein the first transceiver is in a connection mode (1 inki ng m 〇de) to connect the first network accessor, and the second transceiver is in a search mode Page 18 1260138__ 6. Applying for the scanning mode to search for the second network access device. 5. The system of claim 4, wherein when the communication quality between the user device and the first network accessor is reduced to a predetermined level, the first transceiver is converted to a search mode and The second transceiver will transition to a connected mode to connect to the second network accessor. 6. The system of claim 5, wherein the communication quality is determined based on the wireless signal strength and/or the data transmission rate. The system of claim 1, wherein the user device comprises a transceiver and the transceiver is switchable between a search mode and a connection mode. [8] The system of claim 7, wherein when the communication quality between the user device and the first network accessor is reduced to a predetermined level, the transceiver is converted to the connection mode To connect the second network accessor. 9. The system of claim 1, wherein the first network accessor operating frequency is different from the operating frequency of the second network accessor. The system of claim 1, wherein the first network accessor has a first coverage area and the second network accessor has a second coverage area, wherein the first coverage area is The second coverage is partially weighted by 1260138_____. 1 1. A user device for a wireless local area network system, comprising: a first transceiver for communicating with a first network access device; and a second transceiver for searching for a first Two network accessors. 1 2 . The user device of claim 11, wherein the user device, the first network access device, and the second network access device are all compliant with the IEEE 8 0 2.1 1 standard . A. The user device of claim 11, wherein the first transceiver is connected to the first network accessor in a connection mode, and the second transceiver is in a search mode. Search for the second network accessor. 1 . The user device of claim 13 , wherein the first transceiver is reduced when the communication quality between the device and the first network accessor is reduced to a preset level Will be converted to the seek mode and the second transceiver will be converted to the connected mode for connection to the second network accessor. f 5. The user device of claim 14 of the patent application, wherein the communication quality is determined based on the wireless signal strength and/or the data transmission rate. 1 6. A method for roaming in a wireless local area network, the method comprising: searching for a 1260138_6, a patent scope-two network storage while a user device is connected to a first network access device The user device is in turn connected to the second network access device before the communication between the user device and the first network access device is interrupted; and the user device is connected to the first The second network accessor simultaneously searches for a third network accessor. The method of claim 16, wherein the wireless local area network, the user device, the first network access device, the second network access device, and the third network storage The pickers are in compliance with the IEEE 8 0 2. 1 1 standard. The method of claim 16, wherein the user device comprises a first transceiver and a second transceiver, wherein the first transceiver is connected to the first transceiver in a connection mode A network accessor, and the second transceiver searches for the second network accessor in a search mode. The method of claim 18, wherein when the user device is in turn connected to the second network accessor, the second transceiver is converted to the connected mode and the first transceiver The device will be converted to search mode. #0. The method of claim 18, wherein the user device is connected to the second network accessor by the second transceiver in the connected mode, and by being in the In the search mode, the first transceiver uses 1260138_6, and the patent application scope is 1. The method of claim 16, wherein the 4 includes a transceiver, and the transceiver can be switched between a search mode. . The method of claim 2, wherein when the switch is connected to the second network accessor, the transceiver is coupled to the second network accessor. 2 3. The method of claim 16, wherein the communication quality between the first network accessor is reduced to a user device that is instead connected to the second network access 2 4. The method of claim 23, wherein the method is based on the wireless signal strength and/or the data transmission rate, as in the method of claim 16, wherein the working frequency of the device is Different from the second network access device, the user device package type and a connection [the user device will be converted into the connection: the user device preset degree, the message quality is based on a network access working frequency.