• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:

    公开号:SE1050830A1
    申请号:SE1050830
    申请日:2010-07-26
    公开日:2012-01-27
    发明作者:Pelle Bergkvist；Andreas Nielsen
    申请人:Connectblue Ab；
    IPC主号:
    专利说明:

    15 20 25 30 2 Another problem with different wireless technologies is that the scan for new wireless networks affects the performance of the wireless network used.
    SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned problems and to provide roaming, without appreciable communication losses. In accordance with the invention, at least two cooperating interfaced communication units are used to achieve roaming. The use of several independent communication units also opens up the possibility of combining roaming with redundancy.
    A local communication network on a client side comprises a first client communication unit and at least a second communication unit, wherein both the first client communication unit and the second communication unit or units comprise a first interface unit, the first interface unit providing a communication path between the local communication network and a remote network.
    The local communication network is a local link used for communication between the client communication units that act as bridge devices to the remote communication network.
    In some embodiments, the client communication units constitute wireless clients, which communicate with the remote network through wireless access points.
    The wireless clients function as bridges, which forward packets from the local communication network to the remote communication network and vice versa. To prevent network loops, only one of the clients is allowed to bridge packets at a time. This mechanism is controlled by a protocol, which uses a local link (by local link is meant a network connection between the clients and for example an Ethernet network) to prepare and perform roaming and redundancy.
    It should be noted that both roaming and redundancy can be achieved, regardless of the communication protocols and techniques used.
    The inventive concept can be used in wired as well as wireless systems and radio systems as well as in combinations thereof. 10 15 20 25 30 3 In some embodiments, the local area network operates under a predefined protocol. The protocol defines three device states of the wireless clients: Master, Slave and Available, which are also called the first state, the second state and the third state. When the wireless clients restart, they will enter the Available state. The goal of the protocol is then to select a Master Client and a Slave Client for the local link.
    The device called Master determines roaming and more by controlling the Slave device over the local link.
    An active Master Client maintains a wireless connection with the remote communication network and bridges data from the local communication network to an access point of the remote communication network. The master client instructs an associated Slave device to begin scanning for a connection with better transfer properties. Different criteria for what is considered better can be determined in different systems. Examples of such criteria are the Received Signal Strength Indicator (RSSI), or an access point included in a list of preferred access points. Other criteria can also be used. While the scan is in progress, there are no performance losses, as the exchange of information takes place through the Master Client.
    If the Slave Unit detects a more preferred connection, the Master Unit can initiate roaming by instructing the Slave Unit to establish communication over the new link. Once the Slave Unit has established communication, there will in fact be two simultaneous wireless connections between the local communication network and the remote communication network. However, only the Master Unit will bridge the packet and handle the communication in this mode.
    After receiving notification that the Slave Unit has established communication, the Master Unit will initiate Role Change and instruct the Slave Unit to change permits. After the Role Shift process has taken place, the former Slave Unit will become the Master Unit and vice versa. The bridge will be taken over immediately by the new Master Unit while the old Master Unit shuts it down. The former Master Unit, which is now a slave unit, disconnects the current connection and is instructed to start searching for another, in the same way as above.
    The master unit and the slave unit continuously monitor each other's function. A polling system can be used. If the Master Unit detects a malfunction of the Slave Unit, a search is made for a wireless client that is in the Available state. If a client in the Available mode is found, the Master Unit will select it as the Slave Unit and instruct the client accordingly. If a Slave Unit detects a malfunction of the associated Master Unit, it will change state and become a Master Unit. Communication will be resumed immediately and a search for a Slave unit will take place among the clients who are in the Available state.
    It should be noted that all particular features of the invention are found on the client side. Consequently, the remote communication network can be configured by default and use standard wireless hardware and no special firmware.
    BRIEF DESCRIPTION OF THE DRAWINGS In order to make the manner in which the above and other advantages and objects of the invention are easier to understand, a more detailed description of the above invention will be given with reference to certain embodiments, which are shown in the following drawings.
    Noting that these drawings show only typical embodiments of the invention and therefore should not be construed as limiting its scope, the invention will be described and explained in detail and with further details with reference to the accompanying drawings, in which: Fig. 1 is a general overview block diagram of an embodiment of a system in accordance with the invention, Fig. 2 is a general block diagram of an embodiment of a wireless system in accordance with the invention, Fig. 3 is a general block diagram of the embodiment shown in Fig. 2. after changing state, Fig. 4 is a schematic block diagram of the system of Fig. 2 during a first error detection procedure and Fig. 5 is a schematic block diagram of the system of Fig. 2 during a second error detection procedure.
    DETAILED DESCRIPTION The schematic block diagram of Fig. 1 shows a first client communication unit 10 and a second client communication unit 12. In some embodiments, the first client communication unit 10 and the second client communication unit 12 are identically equipped and include first interface units 14 for communication. over a local Iänkn network 16.
    The first client communication unit 10 and the second client communication unit 12 also include second interface units 18 for communication over remote networks 20. In some embodiments, the remote network is a wireless network and the other interface units 18 are wireless interface units. In such embodiments, the remote network 20 comprises a plurality of access points, cf. Fig. 2.
    In the embodiment shown in Fig. 1, the first client communication unit 10 acts as a Master and bridges data between the local link network 16 and the remote network 20 through a bridge unit 22. In this context, bridging corresponds to a process for transparently exchanging data over a first communication path. . A roaming controller 24 of the first client communication unit 10 communicates through said first interface units 14 with a roaming controller 24 of the second client communication unit 12 serving as a slave. The roaming controller 24 includes means for determining whether a second communication path is preferred before the first the communication route. The local network 16 and the remote network 20 may be wired, wireless or arbitrary combinations thereof.
    The master unit has selected a Slave unit from any number of communication units in the Available state. In some embodiments, the selected Slave Unit continuously informs the Master Unit of current communication data, such as the Received Signal Strength Indicator (RSSI). Other information that can be transferred from 10 15 20 25 30 6 The master unit to the Slave unit includes a list of preferred access points. The slave unit is instructed by the Master unit to search for Access points that can offer better transmission quality and thereby provide an alternative second communication path.
    When the second client communication unit 12 operates as a Slave unit, it continuously searches for an alternative communication path through an alternative access point. If an alternative communication path is encountered, information about this is sent to the first client communication unit 10 through the local link network. It should be noted that during the scanning process performed by the Slave Unit, no capacity losses occur during the communication performed by the Master Unit. The roaming control unit 24 at the Master unit decides on the basis of the information received from the Slave unit whether a roaming process is to be started.
    The first client communication unit 10 and the second client communication unit 12 also include a timer or monitoring unit 26. The monitoring unit 26 of the client communication unit operating as Master Unit expects a punctual control question from the corresponding monitoring unit of the client communication unit operating as Slave unit. Receipt of the control question and the answer, respectively, is used in an error detection arrangement described below.
    In the installation shown in Fig. 2, four of the first type of client communication units are connected via wire to the local link network 16.
    A first client communication unit is marked M and works as a Master unit. A second client communication unit is marked S and works as a Slave unit. The two additional client communication units are marked A and are in the Available state and are therefore not active in operation.
    All brewing, i.e. communication between networks, is handled transparently by the Master Unit through the first communication path to the remote network 20. As shown in Fig. 2, the remote network 20 forms a wireless connection and comprises a plurality of access points. A first access point 28 is currently involved in the communication between the networks. A second access point 30 and a plurality of additional access points are currently not involved. The first access point 28 corresponds to the first communication path. The slave communication unit and the master communication unit communicate through the local link network and exchange data regarding the current transmission quality and possible alternative communication paths. The local area network may be a conventional Ethernet network.
    Master unit M communicates an instruction to Slave unit S through the local link network for starting a scanning process. The purpose of the scanning process is to locate an access point that is preferred over the first access point 28. In some embodiments, Slave Unit S continuously reports back to Master Unit M on alternative communication paths and alternative access points found.
    When the slave unit S has located the second access point 30, the roaming control unit 24 of the master unit M compares transmission characteristics and other aspects of the first access point 28 and of the second access point 30. If the roaming control unit 24 of the master unit M determines that the second access point 30 has several desired transmission characteristics, or is more preferred for other reasons, the Master Unit M notifies the Slave Unit S to begin a process to connect to the second access point 30. The brewing through the Master Unit M continues during the connection process.
    The brewing through the first access point 28 continues, even after the completion of the connection process and the establishment of a connection through the second access point 30. When the connection process is completed and a complete connection through the second access point 30 is present, Slave Unit S Master Unit M notifies this. The master unit M then sends a role change instruction to the Slave unit S to become a new Master, as shown in Fig. 3.
    After taking over the role of Master, the brewing of the communication is also taken over and moved to the second access point 30, whereby a second communication path is provided. This step completes the roaming procedure. The former Master Unit will be a Slave Unit S with a broken wireless connection. The new Master Unit sends instructions to the new Slave Unit S to begin the process of scanning for an alternative communication path in the manner described above.
    An error detection procedure is shown in Fig. 4. The purpose of the error detection procedure is to provide redundancy for client communication devices, whereby any device A in the Available state can replace a Slave device or a Master device. In order to be able to detect faults in the units, the Slave Unit continuously monitors the Master Unit's work. Correspondingly, the Master Unit checks the status of the Slave Unit. In some embodiments, the Slave Unit continuously queries the Master Unit.
    The monitoring unit 26 (compare Fig. 1) of the Master Unit is used as a timer which ends when the predetermined timeout time has elapsed.
    The timer restarts at each poll request. The master unit must respond to the query request from the Slave unit with an answer to the question. A polling request followed by an associated answer constitutes a successful polling. A successful poll ends and restarts the surveillance.
    As long as Slave Unit S operates, each interrogation request is continuously received and answered by Master Unit M. Should Slave Unit S cease to function or disconnect from the local link network 16, any interrogation request from Slave Unit S will no longer reach Master Unit M. As a as a result, the monitoring unit of the Master Unit M will consider the Slave Unit as non-functional or as disconnected and will create a warning signal, and a search for a unit A in the Available state will be initiated, as shown in a middle part of Figs. 4. When a unit A in the Available state has been found, the Master unit M will send role change instructions for changing the working state from Available to Slave. The slave unit S confirms the role change, and the situation shown in a lower part of Fig. 4 will exist.
    Another fault condition is detected when the Slave Unit S does not receive a confirmation signal from the Master Unit M after sending an interrogation request. This situation is shown at the top of Fig. 5. The slave unit S will in this case assume that the Master unit M is out of order or has been disconnected from the local link network 16. Instead, the Slave unit S designates itself as the new Master unit M, as shown in the middle of Fig. 5. 10 15 20 25 30 9 The new Master Unit M then checks if there are any client communication units available in the local link network 16. If a unit A in the Available state is found, the Master Unit M selects it and sends a role change command. When unit A in the Available state receives the role change command, it becomes a new Slave unit S, as shown at the bottom of Fig. 5.
    During all transition procedures, only one client communication unit works as a Master Unit and actively brews traffic between the local link network and the remote network. Therefore, no network loops can occur. A second client communication unit that works as a Slave unit continuously searches for access points in the remote network. Complete communication is established between the Slave Unit and a new access point, before the traffic is switched in a roaming procedure. Since the establishment of a communication path is performed by a client communication unit other than the client communication unit that bridges the traffic, there is no reduction in communication performance during this process. Furthermore, the remote network does not need to be modified in any way, as all roaming functionality is integrated on the client side. In accordance with what has been described above, the protocol used in accordance with the invention defines three device states, namely Master, Slave and Available. Preferably, all client communication devices restart and start in the Available state. On the basis of different timing properties, a client communication unit will enter the Master state and then appoint another client communication unit in the Available state to become a Slave unit controlled by the Master unit.
    In some embodiments, the local link network 16 is a wireless system. In some embodiments, the remote network 20 is a wired system. Various combinations of wired and wireless network systems can be used within the scope of the invention. Roaming and redundancy can still be achieved in the systems described above, without modification of the systems. Although certain illustrative embodiments of the invention have been specifically described, it should be understood that various other modifications may be readily apparent to one skilled in the art without departing from the spirit of the invention. Accordingly, it is not intended that the scope of the appended claims be limited by this specification, but that the claims be construed to cover all the equivalent embodiments of the invention which will be apparent to those skilled in the art to which the invention pertains.
    权利要求:
    Claims (8)
    [1]
    A local communication network (16), comprising a first client communication unit (10) and at least a second communication unit (12), wherein both said first client communication unit (10) and at least said second communication unit (12) comprise a first interface unit (14). ) and a second interface unit (18), the first interface unit (14) being operatively connected to the local communication network and said second interface unit being operatively connected to a remote network (20), characterized in that to. the first client communication unit (10) and at least said second communication unit (12) comprises a bridge unit (22) arranged to transparently bridge traffic between the local communication network (16) and the remote network (20), the first client communication unit (10) and at least said second communication unit (12) operates in a first state, in which the first client communication unit (10) bridges traffic k between the local communication network (16) and the remote network (20) through a first communication path, and in a second state, in which the second communication unit (12) searches for alternative second communication path, a roaming controller (24) of the first client communication unit a (10) includes means for determining whether the alternative second communication path is preferred over the first communication path, the roaming controller (24) of the first client communication unit (10) is operatively connected to the second client communication unit (12) to establish communication through the second communication path, the second client communication unit (12) is operatively connected to the first client communication unit (10) for checking the functional status of the first client communication unit (10) and the first client communication unit (10) is designed to switch states for the first the client communication unit (10) to the other 10 15 20 2 The state, to switch states of the second client communication unit (12) to the first state and to activate the bridge unit (22) of the second client communication unit (12) to transparently bridge traffic between the local communication network (16) and the remote network ( 20).
    [2]
    The local communication network (16) according to claim 1, wherein the first client communication unit (10) and the second client communication unit (12) comprise error detection means (26).
    [3]
    The local communication network (16) according to claim 2, wherein the error detecting means comprises a monitoring unit (26) with a timer for repeatedly sending the interrogation request, when the client communication unit is operating in the second state, and for confirming the interrogation request, when the client communication unit works in the first state.
    [4]
    A method of performing roaming in a local communication system, comprising a) b) establishing a first communication path between a first client communication unit (10) of the local communication system and a remote network, the first client communication unit (10) operating in a first state, in a second client communication unit (12) of the local communication unit when operating in a second state, continuous scanning for a second communication path with better transmission properties, in the second client communication unit (12) of the local com communication unit, preparing and establishing a second communication path, performing roaming of the communication from the first communication path to the second communication path, interrupting the communication between the first client communication unit of the local communication system 10 15 20 25 30 13 f) in the second client communication unit (12) continuously monitor the first client communication unit (10) with respect to fault detection and g) in the first client communication unit of the local communication unit, continuous scanning for an additional communication path with better transmission characteristics.
    [5]
    A method according to claim 4, also comprising the step of continuously transmitting error detection signals to the first client communication unit (10) in the second client communication unit (12) and changing working state to the first state when detecting errors of the first client communication unit ( 1 O).
    [6]
    A method according to claim 5, also comprising the step of sending a poll request from the second client communication unit (12) to the first client communication unit (10), when a predetermined timeout time has elapsed.
    [7]
    A method according to claim 4, also comprising the steps of operating a plurality of client communication units operating in a third operating state and automatically switching operating states from the third state to the first state of a first client communication unit (10).
    [8]
    A method according to claim 4, also comprising the steps of operating a plurality of client communication units operating in a third operating state, switching working states from the third working state to the first working state of a first client communication unit (10) and sending instructions from the first the client communication unit (10) to switch the operating state to the other state.
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    同族专利:
    公开号 | 公开日
    EP2556702A1|2013-02-13|
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    WO2012015353A1|2012-02-02|
    EP2556702B1|2016-10-12|
    US20130273909A1|2013-10-17|
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    法律状态:
    2017-03-07| NUG| Patent has lapsed|
    优先权:
    申请号 | 申请日 | 专利标题
    SE1050830A|SE537688C2|2010-07-26|2010-07-26|Method and device for roaming in a local communication system|SE1050830A| SE537688C2|2010-07-26|2010-07-26|Method and device for roaming in a local communication system|
    EP11771285.1A| EP2556702B1|2010-07-26|2011-07-12|A method and a device for roaming in a local communication system|
    US13/812,381| US9161202B2|2010-07-26|2011-07-12|Method and a device for roaming in a local communication system|
    PCT/SE2011/050944| WO2012015353A1|2010-07-26|2011-07-12|A method and a device for roaming in a local communication system|
    CA2806358A| CA2806358A1|2010-07-26|2011-07-12|A method and a device for roaming in a local communication system|
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