A method for steering of roaming (SOR) in wireless communication networks includes sending by a mobile equipment (ME) a registration message to a visited public land mobile network (VPLMN). The ME receives a first message from a home public land mobile network (HPLMN) through the VPLMN. The ME determines that the first message has failed a security check. In response to determining that the first message has failed the security check, the ME sends a second message to the VPLMN, the second message including an indication that the first message has failed the security check.

Steering of user equipment (UE) in a visited public land mobile network (VPLMN) is a procedure enabling a home public land mobile network (HPLMN) to update a list of preferred PLMN/access technology combinations at the UE via non-access stratum (NAS) signaling. The HPLMN updates the list of preferred PLMN/access technology combinations, e.g., depending on the public land mobile network (PLMN) where the UE is registered or when required by HPLMN operator policies. Steering of UE in VPLMN may also be known as steering of roaming (SOR). SOR enables a HPLMN to steer a user equipment (UE) from one network to another. SOR is a technique whereby a roaming UE is encouraged to roam to a preferred roamed-to network by the HPLMN. For example, a UE is registered on one public land mobile network (PLMN), and for some reason the UE's HPLMN wants the UE to register on another PLMN.
Like reference numbers and designations in the various drawings indicate like elements. cl DETAILED DESCRIPTION
The present disclosure is directed to steering of roaming (SOR) in wireless communication networks (i.e. steering of user equipment (UE) in visited public land mobile network (VPLMN)). In some wireless networks, such as fifth generation (5G) networks, a home operator (e.g., home public land mobile network (HPLMN)) can steer a UE from one network to another. For example, a UE is registered on one public land mobile network (PLMN), and the UE's HPLMN may want the UE to register on another PLMN.
A UE can perform a PLMN search to find an alternative PLMN. For example, when the UE first powers up, the UE can perform an initial PLMN search. After the UE powers up, the UE can perform the PLMN search periodically. The periodical PLMN search, for example, enables the UE to find a PLMN which has a higher priority than the UE's current PLMN (the PLMN that the UE is currently registered is also called the UE's VPLMN or Registered PLMN (RPLMN)). For example, the UE is on a VPLMN (2nd network) other than its HPLMN (1st network), and the UE can periodically search for the HPLMN. The periodical PLMN search can happen when a timer expires. An example of such a timer is a timer known as timer T. The PLMN search may only take place when the UE is in an IDLE mode, IDLE state, 5GMM-IDLE mode, or CM-IDLE state e.g. a state where there is no active communications taking place with the network. If the UE performed a PLMN search/selection in a CONNECTED mode, any connection would be lost as the radio would have to disconnect from the current PLMN. Therefore, if the timer T expires, the UE has to wait until the UE is in an idle mode to perform the PLMN search.
In some cases, such as in fourth generation (4G), third generation (3G), or second generation (2G) systems, once a UE has attached to a VPLMN, the HPLMN sends a Short Message (SM) including a secured packet (as defined in ETSI TS 102 225). This secured packet includes at least one PLMN identity. The SM is received by the Mobile Equipment (ME) of the UE, and based on an indication (e.g., code point) in the SM the ME determines that some or all of the contents of the SM is for the universal integrated circuit card (UICC) of the UE. The UICC then receives the SM and unpacks the SM to determine that it includes a secured packet. The content of the secured packet updates the Preferred Operator PLMN list (e.g., the most top entry) in the UICC, and the UICC sends a Universal Subscriber Identity Module (USIM) Application Toolkit (USAT) REFRESH command to the ME. Upon receipt of the REFRESH command, the ME reads the Preferred Operator PLMN list from the UICC or from the REFRESH command if a PLMN list was included, and stores the list in the memory of the ME. The ME then performs a PLMN search taking into account the PLMNs in the updated Preferred Operator PLMN list. The updated Preferred Operator PLMN list may have changed as a result of the secured packet. One will appreciate that the Preferred Operator PLMN list is an entry in the USIM application that can only be modified by the entity that has the necessary keys that allow modifications to be performed e.g. Home service provider, the HPLMN. However it could be any application that provides the functionality to the ME to indicate which networks should be chosen when the UE performs a PLMN selection.
In some cases, such as in 5G networks, an authentication procedure (which is part of a registration procedure) can be used to transport a list of networks or PLMNs (or a list of preferred PLMN and access technology combinations) to the UE. FIG. 1 is a data flow diagram 100 illustrating an example process of using an authentication procedure to transport a list of preferred PLMN and access technology combinations. The data flow diagram 100 is according to 3GPP CT1 contribution C1-180462 which is hereby incorporated by reference. The data flow diagram 100 includes a UE 102, a VPLMN access and mobility management function (AMF) node 104, an HPLMN authentication server function (AUSF) node 106, and an HPLMN unified data management (UDM) node 108. The UE 102 can include an ME and a (removable) memory module. An example of a memory module is a UICC. The UICC may include a subscriber identity module (SIM), a Universal SIM (USIM), or a Removable User Identity Module (R-UIM) which are collectively known as UICC applications. The ME and the UICC can use a set of commands, USAT commands defined in 3GPP TS 31.111 to exchange data and request each other to perform operations on behalf of the other entity. A UE may also be known as a mobile station (MS). The nodes 104, 106, and 108 can be core network components. The AMF can include access and mobility management functions such as registration management, connection management, mobility management, and access authentication and authorization. The AUSF can provide UE authentication services. The UDM can have similar functionalities as Home Location Register (HLR) or Home Subscriber Server (HSS), such as generating 3GPP Authentication and Key Agreement (AKA) authentication credentials. In this disclosure, access technology refers to radio access technology.
In FIG. 1, during steps 5-7 of the authentication procedure, the HPLMN UDM 108 can send SOR data (e.g., a list of preferred PLMN, a list of preferred PLMN and access technology combinations, or an HPLMN protected list of preferred PLMN/access technology combinations) to the UE 102. For example, if the HPLMN wants the UE to register on a different PLMN (3rd network), the HPLMN UDM 108 can send the SOR data. However, after the UE 102 receives the SOR data, the UE cannot perform a PLMN search because the UE is in a connected mode during the authentication phase (as discussed above, the PLMN search is performed when the UE is in an idle mode). In some cases, the timer T is not set until the UE completes the registration procedure. In other words, the timer T is started upon completion of the registration procedure, and the UE does not perform a PLMN search until the timer T expires. As a result, the UE 102 can be registered on an undesirable PLMN for a considerable amount of time. However, it is beneficial for an operator to steer (request the UE to perform a PLMN search) the UE to a different PLMN at its earliest convenience, for example, before the attach or registration attempt successfully completes. Further, a UE in the authentication phase cannot use the existing procedures of 2G, 3G, or 4G systems to receive a secured packet that includes the SOR data, because a UE cannot receive an SM if it is not attached or registered to a network.
Besides that, the UE may be on an undesirable PLMN for a long time, the SOR data delivery in FIG. 1 also has the following issues. First, in steps 5-7, the SOR data is sent in clear text to the UE 102. As a result, the SOR data can be modified by the VPLMN node 104. Second, the authentication procedure in 5G networks uses Extensible Authentication Protocol (EAP). In some cases, the data in the first EAP packet can be modified and even removed by the VPLMN node 104, and the receiving UE 102 and the sending HPLMN node 108 do not know that this has been done. Third, persistent information on the USIM or UICC may not be updated, causing the HPLMN to possibly send SOR data repeatedly. A UICC or USIM (e.g., memory module) contains persistent data or information. Persistent data refers to data stored in a memory which would not be rendered inaccessible or even wiped or cleared, upon, e.g., restart of the device or module within the device. For example, the ME reads, e.g., the data "Operator Controlled PLMN Selector with Access Technology" or other data from the USIM or UICC, e.g., after the ME boots or activated. The ME may read the data at other times, e.g. upon receiving the REFRESH command. The ME may modify the data "Operator Controlled PLMN Selector with Access Technology" based on the received SOR data, and the modification made by the ME should be synced to the USIM or UICC so that the persistent data is updated and the updates are available after, e.g., reboot, boot up or startup. However, write access to some UICC or USIM data, including the "Operator Controlled PLMN Selector with Access Technology", is protected as described earlier. Only the HPLMN operator has the credentials for the write access to this data. Neither the VPLMN nor the ME has these credentials. In other words, after receiving the SOR data, the ME in the UE 102 cannot update the persistent data on the UICC or USIM, which may cause the HPLMN to send SOR data repeatedly.
In some cases, a UE can be in a manual network selection mode. In the manual network selection mode, the UE selects a PLMN without necessarily considering the HPLMN's preferences. In an automatic network selection mode, the UE does consider the HPLMN's preferences when selecting a PLMN. In the case of manual network selection mode, SOR may not take place because the device has chosen a VPLMN or network per the UE's preferences. Another reason for a UE selecting a network or VPLMN is because the VPLMN is included in the "User Controlled PLMN Selector with Access Technology" list. For example, the UE finds a network on the "User Controlled PLMN Selector with Access Technology" list. The user/application has populated the "User Controlled PLMN Selector with Access Technology" list with PLMN entry(s) and it is akin to performing a manual network selection, i.e., the UE has chosen a network for a specific reason. Therefore, SOR may not take place if the UE has chosen a VPLMN and a network in the "User Controlled PLMN Selector with Access Technology" list.
In some cases, a UE can be battery constrained (or resource constrained). Because the PLMN search (e.g. network discovery process) consumes battery power and there is no guarantee that an alternative network is available, it is desirable that SOR operations take into account if a UE is battery constrained to prolong battery life. In some cases, a UE can be mobility constrained such as fixed UEs, and it may be desirable not to perform SOR because the PLMNs available to the UE are not likely to change.
The SOR procedure, according to methods and systems described herein, enables an operator to steer a UE to a different PLMN at the earliest convenience, e.g., before the attach or registration attempts successfully completes. The described approach uses a secured packet to deliver SOR data so that intermediate nodes along the path cannot modify the SOR data. The described approach can also update the persistent information on the UICC based on the SOR data. The described method also informs the PLMN if the UE will be unable to act on the SOR information due to the automatic network selection mode, user controlled PLMN selector list, or manual network selection mode. Another reason why the UE is unable to select a different PLMN is because the PLMN currently being registered continues to be the highest priority PLMN. Finally, the secured packet may fail an integrity check at the UICC. In any of these cases, the ME may be requested, via USAT, by the memory module to transmit a second secured packet to the network. The second secured packet may indicate to the network the reasons why the UE cannot select another PLMN or the integrity check failure. In some cases, a security check comprises an integrity check. In this disclosure, terms "security check" and "integrity check" can be interchangeable. Security check may also be determining by the ME or UICC that one to many information elements, indicators, SOR date or secured packet that should have been present (expected) in a received message are received in the received message. Determining could be based on configuration within the ME and or UICC.
5G terminologies used in this disclosure are described below.
5G system mobility management (5GMM)-IDLE mode: The term is used standalone. A UE in 5GMM-IDLE mode means the UE can be either in 5GMM-IDLE mode over 3GPP access or in 5GMM-IDLE mode over non-3GPP access.
5GMM-CONNECTED mode: The term is used standalone. A UE in 5GMM-CONNECTED mode means the UE can be either in 5GMM-CONNECTED mode over 3GPP access or in 5GMM-CONNECTED mode over non-3GPP access.
5GMM-IDLE mode over 3GPP access: AUE is in 5GMM-IDLE mode over 3GPP access when no N1 non-access stratum (NAS) signaling connection between the UE and network over 3GPP access exists. The term 5GMM-IDLE mode over 3GPP access used in this disclosure corresponds to the term Connection Management IDLE (CM-IDLE) state for 3GPP access used in 3GPP TS 23.501.
5GMM-CONNECTED mode over 3GPP access: A UE is in 5GMM-CONNECTED mode over 3GPP access when an N1 NAS signaling connection between the UE and network over 3GPP access exists. The term 5GMM-CONNECTED mode over 3GPP access used in the present document corresponds to the term CM-CONNECTED state for 3GPP access used in 3GPP TS 23.501.
5GMM-IDLE mode over non-3GPP access: AUE is in 5GMM-IDLE mode over non-3GPP access when no N1 NAS signaling connection between the UE and network over non-3GPP access exists. The term 5GMM-IDLE mode over non-3GPP access used in this disclosure corresponds to the term CM-IDLE state for non-3GPP access used in 3GPP TS 23.501.
5GMM-CONNECTED mode over non-3GPP access: A UE is in 5GMM-CONNECTED mode over non-3GPP access when it has an N1 NAS signaling connection between the UE and network over non-3GPP access exists. The term 5GMM-CONNECTED mode over non-3GPP access used in this disclosure corresponds to the term CM-CONNECTED state for non-3GPP access used in 3GPP TS 23.501.
Access stratum connection: A peer to peer access stratum connection between either the UE and the Next Generation-radio access network (NG-RAN) for 3GPP access or the UE and the N3IWF for non-3GPP access. The access stratum connection for 3GPP access corresponds to a radio resource control (RRC) connection via the Uu reference point. The creation of the access stratum connection for non-3GPP access corresponds to the completion of the IKE_SA_INIT exchange (see IETF RFC 7296) via the NWu reference point.
N1 NAS signaling connection: A peer to peer N1 mode connection between UE and AMF. An N1 NAS signaling connection is either the concatenation of an RRC connection via the Uu reference point and an NG connection via the N2 reference point for 3GPP access, or the concatenation of an IPsec tunnel via the NWu reference point and an NG connection via the N2 reference point for non-3GPP access.
5G PLMN search procedure is described as follows.
The PLMN search procedure for 5G is substantially identical to PLMN search procedures for PLMNs using EPC or GPRS core networks. As discussed above, a PLMN search happens initially and a PLMN search also happens periodically. The PLMN search that happens periodically occurs when a timer (e.g., the timer T discussed above) expires. The periodically happening PLMN search searches for a higher priority PLMN.
For example, 3GPP TS 23.122 provides the following description for the PLMN search procedure. If the MS is in a VPLMN, the MS shall periodically attempt to obtain service on its HPLMN (if the EHPLMN list is not present or is empty) or one of its EHPLMNs (if the EHPLMN list is present) or a higher priority PLMN/access technology combinations listed in "user controlled PLMN selector" or "operator controlled PLMN selector" by scanning in accordance with the requirements that are applicable to i), ii) and iii) as below. In the case that the mobile has a stored "Equivalent PLMNs" list the mobile shall only select a PLMN if it is of a higher priority than those of the same country as the current serving PLMN which are stored in the "Equivalent PLMNs" list. For this purpose, a value of timer T may be stored in the SIM. The interpretation of the stored value depends on the radio capabilities supported by the MS. The MS selects and attempts registration on other PLMN/access technology combinations, if available and allowable, in the following order: i) either the HPLMN (if the EHPLMN list is not present or is empty) or the highest priority EHPLMN that is available (if the EHPLMN list is present); ii) each PLMN/access technology combination in the "User Controlled PLMN Selector with Access Technology" data file in the SIM (in priority order); iii) each PLMN/access technology combination in the "Operator Controlled PLMN Selector with Access Technology" data file in the SIM (in priority order).
In addition to using the "Operator Controlled PLMN Selector" list, the device or UE can also use the "User Controlled PLMN Selector with Access Technology" list. If the device, when performing a PLMN search finds a PLMN that is in the "User Controlled PLMN Selector with Access Technology", then the device will choose this PLMN (with higher priority) than any PLMN in "Operator Controlled PLMN Selector".
Turning to a general description of the elements, a UE may be referred to as a mobile electronic device, user device, mobile station, subscriber station, portable electronic device, mobile communications device, wireless modem, wireless terminal, mobile equipment, session initiation protocol (SIP) user agent, set-top box, test equipment, or embedded modem. Examples of a UE may include a cellular phone, personal data assistant (PDA), smart phone, laptop, tablet personal computer (PC), pager, portable computer, portable gaming device, wearable electronic device, or other mobile communications device having components for communicating data via a wireless communication network. The wireless communication network may include a wireless link over at least one of a licensed spectrum and an unlicensed spectrum.
Other examples of a UE include mobile and fixed electronic devices. A UE may include a ME device and a removable memory module, such as a UICC that includes a SIM application, a USIM application, or an R-UIM application all known as UICC applications. The term "UE" can also refer to any hardware or software component that can terminate a communication session for a user. In addition, the terms "user equipment," "UE," "user equipment device," "user agent," "UA," "user device," and "mobile device" can be used synonymously herein. A UICC could also be a secure element that contains UICC applications that perform similar functionality.
The wireless communication network may include one or a plurality of radio access networks (RANs), other access networks such as fixed Ethernet or IEEE 802.11 WLAN, core networks (CNs), and external networks. The RANs may comprise one or more radio access technologies. The radio access technologies can be 3GPP access technologies or non-3GPP access technologies. In some implementations, the radio access technologies may be Global System for Mobile communication (GSM), Interim Standard 95 (IS-95), Universal Mobile Telecommunications System (UMTS), CDMA2000 (Code Division Multiple Access), Evolved Universal Mobile Telecommunications System (UMTS), Long Term Evolution (LTE), LTE-Advanced, or 5G access technologies. In some instances, the core networks may be evolved packet cores (EPCs) or 5G cores. The core networks may include AMF, Session Management Function (SMF), UDM, Authentication, Authorization, and Accounting (AAA) server, or other network nodes or entities.
FIG. 2 is a data flow diagram 200 illustrating an example SOR procedure, according to some implementations of the present disclosure. The data flow diagram 200 includes a UE having a UICC 202 and a ME 204, a first network node 206, a second network node 208, and a third network node 210. The first network node 206 can be an AMF or SMF node of a first VPLMN (2nd network), e.g., PLMNa. The second network node 208 can be an AMF or SMF node of a second VPLMN (3rd network), e.g., PLMNb. The third network node 210 can be a UDM node of an HPLMN (1st network).
At step 1, the ME 204 sends a message to the first network node 206 to start a registration/attach procedure with PLMNa. For example, the ME 204 can send a REGISTRATION REQUEST message to the first network node 206. In some cases, an N1 NAS signaling connection between the ME 204 and the first network node 206 can carry the REGISTRATION REQUEST message. The UE can use 3GPP access or non-3GPP access technologies. The N1 NAS signaling connection can be over 3GPP access or non-3GPP access. For example, the UE can be in a 5GMM-CONNECTED mode over 3GPP access, and an N1 NAS signaling connection over 3GPP access exists between the UE and first network node 206.
At step 1a, the first network node 206 forwards the message in step 1 (e.g., the REGISTRATION REQUEST) to the third network node 210 in HPLMN. The first network node 206 can forward the message to the third network node 210 without going through the second network node 208. In some cases, as will be discussed in FIGS. 3A-5, the messages of steps 1 and 1a can include an indication that indicates the type of device (e.g., battery constrained or mobility constrained) and the operating mode (e.g., manual network selection mode). This indication can help the third network node 210 in HPLMN to determine whether to send SOR data to the UE. For example, if the UE is battery constrained, mobility constrained, or in a manual network selection mode, a node within the HPLMN (e.g. third network node) may not send SOR data to the UE.
At step 2, the third network node 210 sends a secured packet to the first network node 206. The secured packet can include SOR data. At step 3, as will be discussed in FIGS. 6-8E, the first network node 206 sends the secured packet received in step 2 to the ME 204. In other words, the secured packet is received during the registration/attach procedure. In some cases, in step 3, the secured packet is received in a DL NAS TRANSPORT message. In some other implementations, step 3can be a REGISTRATION ACCEPT message or an ATTACH ACCEPT message including the SOR data or the secured packet. In some cases, EAP is used for the authentication procedure in the registration procedure (e.g., 5G networks use EAP for authentication), and the secured packet can be received in an EAP message. In some cases, the secured packet can be packets in a SM, and hence "secured packet" can be interchanged with "SM containing a secured packet".
At step 4, the ME 204 determines by an indication (e.g., code point) in the message received at step 3 that the content is for the UICC, and the ME 204 sends the secured packet to the UICC 202. The UICC 202 decodes the secured packet and retrieves the SOR data. In some cases, during steps 2-4, the secured packet is encoded by the third network node 210 in HPLMN and decoded by the UICC 202, while the intermediate entities such as the first network node 206 and the ME 204 do not decode the secured packet. Based on the SOR data, the UICC 202 can make decisions whether to trigger PLMN search.
At step 5, the ME 204 receives an indication from the UICC 202. The indication can indicate the ME 204 to terminate the ongoing registration/attach procedure and trigger a PLMN search. In some cases, the indication from the UICC 202 can be received via a USAT command. The USAT command can be a REFRESH command. The REFRESH command can include an indication that an SOR procedure should be initiated. In some cases, as will be discussed in FIG. 9, the REFRESH command at step 5 can optionally contain a list of preferred PLMNs so that the ME 204 can perform the PLMN search based on the list. In some cases, the REFRESH command does not contain the list of preferred PLMNs, and the REFRESH command triggers the ME 204 to download an environment file from the UICC 202 that includes a list of preferred PLMNs. The ME 204 then performs the PLMN search based on the downloaded list.
At step 6, based on the indication in step 5, the ME 204 can terminate the registration/attach procedure with PLMNa. In some cases, for terminating the registration/attach procedure, the ME 204 can release the N1 NAS signaling connection between the ME 204 and the first network node 206. In some cases, the termination of the registration/attach procedure includes the ME 204 sending an authentication failure message or a REGISTRATION COMPLETE message to the first network node 206. The authentication failure message or the REGISTRATION COMPLETE message can include an indicator, either indicating a failed receipt of the secured packet (e.g., the secured packet failed an integrity check as discussed below), a successful receipt of the secured packet, or indicating that the ME will not perform a PLMN search with an optional qualification for the reason why. The indicator indicating failure can prevent the network (e.g., PLMNa) from retransmitting a registration procedure related message. The indication indicating failure could be further qualified to indicate the actual reason, examples being but not limited to: PLMN search, PLMN temporary not allowed etc. When the indicator indicates a successful receipt, the indicator identifies to the network that the secured packet was successfully received and the ME will perform a PLMN search. When the indicator indicates that the ME will not perform a PLMN search, the indicator may be qualified indicating the reason: ME is in a manual network selection mode, VPLMN (RPLMN) is on the User controlled PLMN list, there are no other available PLMNs, PLMN temporary not allowed etc.
At step 7, the ME 204 can start the PLMN search to find an alternative network (e.g., PLMNb) to attach or register. At step 8, the ME 204 starts the registration/attach procedure with PLMNb.
In some cases, after the ME 204 receives the USAT command in step 5, if the ME is a device type of at least one of but not limited to battery constrained, resource constrained, mobility constrained, or the ME has selected a network (RPLMN) because that network was in the User controlled PLMN list (i.e., that network is a user-preferred PLMN), the ME 204 does not perform the PLMN search until when either the periodical PLMN search timer T expires or when the ME 204 performs a PLMN search for other reasons. In some cases, when the ME 204 receives the USAT command in step 5, if the UE is in a manual network selection mode or the ME has selected a network (RPLMN) because that network was in the User controlled PLMN list, the UE refrains from performing a PLMN search. The User controlled PLMN list is also called "User Controlled PLMN Selector with Access Technology" list. In some cases, the ME 204 can inform the network (e.g., a node of the HPLMN (e.g., third network or third network's node)) that it is in a manual network selection mode or the ME has selected a network (RPLMN) because that network was in the User controlled PLMN list so that a node of the HPLMN (third network node) does not send SOR data.
In some cases, the indication received from the UICC 202 in step 5 indicates that the secured packet failed an integrity check at the UICC. The indication that the secured packet failed the integrity check may cause the ME 204 to remove the PLMN with which the UE is attempting to register (e.g., PLMNa) from the "Operator Controlled PLMN Selector with Access Technology" list stored in the ME 204 and optionally include PLMNa in a forbidden PLMN list (e.g. EFFPLMN (Forbidden PLMNs)). In some cases, if the current registration/attach procedure with PLMNa is for emergency services, the UE starts the PLMN search after there is no longer a need for emergency services. In some implementations, in step 6, the ME may send a message, e.g., a REGISTER COMPLETE message or an ATTACH COMPLETE message, to the network containing an indication indicating that the secured packet failed the integrity/security check, that the VPLMN is on the User controlled PLMN list or that the ME is in a manual network selection mode. The sending of the message maybe dependent on the ME being configured to respond (e.g., the ME is configured to respond the REGISTRATION ACCEPT/ATTACH ACCEPT message in step 3). This configuration may be stored in an Open Mobile Alliance (OMA) device management (DM) file in the ME, read from the UICC and then stored in the ME, or could have been received in the REGISTRATION ACCEPT/ATTACH ACCEPT message in step 3. In some cases, the ME is configured to expect to receive SOR data in the REGISTRATION ACCEPT/ATTACH ACCEPT message in step 3 e.g. either as indication in the REGISTRATION ACCEPT/ATTACH ACCEPT message in step 3 or as an indication in the SOR data or secured packet that was in the REGISTRATION ACCEPT/ATTACH ACCEPT message in step 3. This configuration may be stored in the OMA DM file in the ME, or read from the UICC and then stored in the ME.
In some case, if the UE is in a manual network selection mode, the following procedure can be performed:
1. The ME starts registration/attach procedure with a VPLMN.
2. The ME receives a first secured packet including SOR data from, e.g., UDM in HPLMN.
3. The UE determines that it is in a manual network selection mode.
4. The ME sends the first secured packet to the UICC along with an indication that the UE is in a manual network selection mode.
5. The ME receives a second secured packet from the UICC, where the second secured packet includes an indication that the ME is in a manual network selection mode.
6. The ME can optionally send to the network the second secured packet (e.g., HPLMN) and optionally include an indication that the ME is in a manual network selection mode so that the HPLMN does not send SOR data. In some cases, the ME can continue the current registration/attach procedure with the VPLMN.
In some cases, if the UE is in a manual network selection mode or the UE selected a PLMN that was in the User controlled PLMN list, the following procedure can be performed:
1. The ME starts registration/attach procedure with a VPLMN.
2. The ME receives a secured packet including SOR data from, e.g., UDM in HPLMN. For example, the secured packet can be received using EAP as shown in FIGS. 6-8E.
3. The ME sends the secured packet to the UICC.
4. The ME receives an indication from the UICC to perform a PLMN search. For example, the USAT REFRESH command from the UICC can include an indicator to perform a PLMN search.
5. Because the ME is in a manual network selection mode or the UE selected a PLMN that was in the User controlled PLMN list, the ME decides not to perform the PLMN search and continues the current registration/attach procedure with the VPLMN. For example, the ME can send an EAP response message to the network, where the EAP message, e.g., EAP-response, may contain an indication why the ME is continuing with the PLMN search, e.g., in the manual network selection mode, or UE used the User controlled PLMN list.
In this disclosure, the described approach for the case when the UE is in a manual network selection mode is also applicable to the case when the ME selected a network (PLMN) in the "User Controlled PLMN Selector with Access Technology" list.
As discussed above, in step 1 of FIG. 2 the ME can indicate the device type (e.g., battery constrained, mobility constrained device, and in a manual network selection mode). FIGS. 4A-5 describes two methods for indicating the device type. FIGS. 3A-3B illustrate a data flow diagram 300 of an example registration procedure from 3GPP TS 23.502. FIGS. 4A-4C illustrate including the device type indicator in a REGISTRATION REQUEST message (e.g., step 1 of FIG. 3A), while FIG. 5 illustrates including the device type indicator in an EAP message (i.e., step 9 of FIG. 3A).
FIGS. 4A-4C illustrate an example description for including a device type indicator in a REGISTRATION REQUEST message, according to some implementations of the present disclosure. For example, the registration initiation procedure described in 3GPP TS 24.501 can be modified to include the underlined text shown in FIGS. 4A-4C. Table 22.214.171.124.1 in FIG. 4B and Table 184.108.40.206.1 in FIG. 4C illustrate that the REGISTRATION REQUEST message can include a new information element "device type" to indicate whether the UE is a battery or resource constrained device, a mobility constrained device, and/or in a manual network selection mode. In some implementations, the setting of the battery constrained indicator can change if the device is connected to a power supply, as such the ME might send a mobility management message including the device type. One skilled in the art will appreciate that in this disclosure message names, code point names, etc. are used for illustrative purposes, and other message names and code point names can be used. For example, indicators can be sent using new information elements or extending existing information elements. In this disclosure, occurrences of "shall" could be "may" or "should".
FIG. 5 illustrates an example description for including a device type indicator in an EAP message, according to some implementations of the present disclosure. For example, 3GPP TS 24.302 can be modified to include the underlined text shown in FIG. 5. Table 8.2.X.1-1 in FIG. 5 shows that an EAP-Response/AKA'-Challenge message can include an AT_SORInfo_Request attribute containing the device type indicator.
As discussed above, in step 2-3 of FIG. 2 the HPLMN (e.g., UDM) can send the secured packet including SOR data to the UE. FIGS. 6-8E describe methods for sending the SOR data.
FIG. 6 is a data flow diagram 600 illustrating an example procedure using EAP signaling to send SOR data, according to some implementations of the present disclosure. The data flow diagram 600 includes a UE 602, an AAA server 604 in a VPLMN, and a database or UDM 606 in HPLMN. The AAA server 604 can also be replaced with AMF and/or UDM. At step 4, the AAA server 604 in VPLMN sends an authentication challenge to the UE 602. The authentication challenge can include an AT_SORInfo_Request_Supported attribute (described in section 8.2.X.1 in FIG. 8C) indicating that the AAA server 604 supports the UE 602 requesting SOR data. At step 5, in response to receiving the indicator that the AAA server 604 supports the UE 602 requesting SOR data, the UE 602 sends an authentication response to the AAA server 604, where the authentication response includes an AT_SORInfo_Request attribute (described in section 8.2.X.2 in FIG. 8E) indicating that the UE 602 requests SOR data, optionally if the UE is battery constrained or operating in manual network selection mode. At step 6, the AAA server 604 forwards the authentication response to the database 606 in HPLMN. The authentication response in step 6 also includes the AT_SORInfo_Request attribute indicating that the UE 602 requests SOR data. The UDM/HSS/HLR takes into account the operating mode of the UE and if it is battery constrained. At step 7, in response to receiving the indicator indicating that the UE 602 requests SOR data, the database 606 in HPLMN sends an authentication acknowledgement to the AAA server 604, where the authentication acknowledgement includes an AT_SORInfo_RESP attribute (described in section 8.2.X.3 in FIGS. 8D-8E) that contains the SOR data. At step 8, the AAA server 604 forwards the authentication acknowledgement to the UE 602. The authentication acknowledgement in step 8 also includes the AT_SORInfo_RESP attribute containing the SOR data.
FIG. 7 is a data flow diagram 700 illustrating an example process using EAP signaling for obtaining SOR data in 5G networks, according to some implementations of the present disclosure. The example process is also applicable to other EAP framework methods, e.g., EAP methods used to access wireless local area networks (WLANs), where the names of the functions can be different. The data flow diagram 700 includes a UE 702, an Security Anchor Functionality (SEAF) or AMF node 704 in a VPLMN, a Authentication Server Function (AUSF) node 706 in an HPLMN, and a UDM/Authentication credential Repository and Processing Function (ARPF) node 708 in the HPLMN. Similar to FIG. 6, at step 4 of FIG. 7, the EAP-Request/AKA'-Challenge can include the AT_SORInfo_Request_Supported attribute indicating that the SEAF/AMF 704 supports the UE 702 requesting SOR data. At steps 5 and 6 of FIG. 7, the EAP-Response/AKA'-Challenge can include the AT_SORInfo_Request attribute indicating that the UE 702 requests SOR data. The messages in steps 7 and 8 of FIG. 7 can include the AT_SORInfo_RESP attribute containing the SOR data. In some cases, a decision to send an indication that SOR is supported in step 2 and/or 3 is based upon the network and/or the location that the UE has requested to register on. In some cases, the data sent in step 7 could be sent in step 3.
FIGS. 8A-8E illustrate an example description of sending SOR data in EAP-AKA', according to some implementations of the present disclosure. For example, 3GPP TS 24.302 can be modified to include the underlined text shown in FIG. 8.
In some cases, at step 5 in FIG. 2, the ME can receive a USAT REFRESH command from the UICC. The REFRESH command can optionally contain a list of PLMNs for 5G access technology (e.g. NG or E-UTRAN connected to 5G core network), or a PLMN-with-access-technology (PLMNwAct) list containing access technology selector including radio access technologies (RATs) used to determine to perform the 5G SOR procedure or steering of a UE from one VPLMN to another VPLMN.
FIG. 9 illustrates an example description of a REFRESH command, according to some implementations of the present disclosure. For example, 3GPP TS 31.111 can be modified to include the underlined text shown in FIG. 9 so that the REFRESH command includes two new parameters "(5G) PLMN List" and "(5G) PLMNwAcT list". In some cases, the PLMN list and the PLMNwAcT list can define the preferred PLMNs in a priority order. The ME can obtain the PLMN list or the PLMNwAcT list from the REFRESH command, and performs the PLMN search based on the list, e.g., starting from the highest priority PLMN.
FIG. 10 illustrates an example description of an environment file (EF) for data "Operator Controlled PLMN Selector with Access Technology", according to some implementations of the present disclosure. For example, 3GPP TS 31.102 can be modified as shown in FIG. 10 to indicate three different embodiments, i.e., 5G System (5GS) supported by New Radio (NR) access, 5G System (5GS) supported by E-UTRA, or EPS (EPC supported by E-UTRA). In some cases, the EF file EFOPLMNwACT is on the UICC and includes preferred PLMNs in a priority order. The REFRESH command can trigger the ME to download EFOPLMNWACT to the memory of the ME so that the ME can perform the PLMN search based on the preferred PLMNs, e.g., starting from the highest priority PLMN.
In some cases, the 5G SOR procedure or steering of a UE from one VPLMN to another VPLMN may involve terminating the ongoing registration procedure by at least one of a REGISTRATION COMPLETE message, an authentication failure message, or releasing the N1 NAS signaling connection.
In some cases, upon the UE (or ME, UE and ME can be interchangeable in this disclosure) terminating the ongoing registration procedure, the UE continues operations as if the UE was switched on or the UE was recovered from lack of coverage, and the UE selects the highest priority PLMN that is available. Alternatively, upon the UE terminating the ongoing registration procedure, the UE selects the highest priority PLMN or equivalent highest priority PLMN (if it is available) using all access technologies via which it had previously discovered the previously highest priority PLMN. Upon failing to discover a higher priority PLMN than the previously highest priority PLMN, the UE using all access technologies that the UE is capable of and if necessary to discover a higher priority PLMN.
As an alternative, if the UE is either battery constrained or the network was selected because the UE is operating in manual network selection mode or the UE had selected a PLMN from the user controlled PLMN list, the ME can ignore the REFRESH command but use the updated Preferred Operator PLMN list that has been read into the ME's memory when the ME performs a PLMN search, e.g., because the periodical search timer T expired. The ME continues operations as if the ME was switched on or the ME has lost PLMN coverage.
FIG. 11 is a data flow diagram 1100 illustrating an example SOR procedure, according to some implementations of the present disclosure. The data flow diagram 1100 modifies the procedure in FIG. 1 based on the described approaches in the present disclosure. FIGS. 12A-12B illustrate an example description for the SOR procedure of FIG. 11, according to some implementations of the present disclosure. FIGS. 12A-12B show changes to the 3GPP CT1 contribution C1-180462.
FIGS. 15A-15F illustrate an example description for steering of UE in VPLMN during registration and after registration, according to some implementations of the present disclosure. The example description in FIGS. 15A-15F can be included in 3GPP TS 23.122. Message 6 in figure C.1.1 of FIGS. 15A-15B (i.e., REGISTRATION ACCEPT) can be in step 3 of FIG. 2. Message 10 in figure C.1.1 of FIGS. 15A-15B (i.e., REGISTRATION COMPLETE) can be in step 6 of FIG. 2.
In some cases, if the SOR data (e.g., the secured packet including the HPLMN protected list of preferred PLMN/access technology combinations) is successfully received (e.g., successful security check), and if the VPLMN the ME is currently attempting to register is not a user-preferred PLMN and the ME is not in a manual selection mode, the ME may terminate the current registration procedure and perform a PLMN search based on the SOR data e.g. after completion of the REGISTRATION/ATTACH procedure (step 10) or before in any of steps 7-9. In some cases, if the SOR data is successfully received, and if the VPLMN the ME is currently attempting to register is a user-preferred PLMN or the ME is in a manual selection mode, the ME may continue the current registration procedure and not to perform the PLMN search. In some cases, if the SOR data is not successfully received (e.g., fails security check, or the ME is configured to receive the SOR data but did not receive), and if the VPLMN the ME is currently attempting to register is not a user-preferred PLMN and the ME is not in a manual selection mode, the ME may terminate the current registration procedure and perform a PLMN search. In some cases, if the SOR data is not successfully received, and if the VPLMN the ME is currently attempting to register is a user-preferred PLMN or the ME is in a manual selection mode, the ME may continue the current registration procedure and not to perform the PLMN search.
In message 10 of figure C.1.1 in FIGS. 15A-15B (i.e., REGISTRATION COMPLETE), the ME, if configured, can send one or more indications indicating that the SOR data was not received, that the SOR data failed security check, that the VPLMN the ME is currently attempting to register is a user-preferred PLMN, or that the ME is in a manual selection mode. As shown in the text in FIGS. 15C-15E, there can be two options for operations associated with message 10. In the second option, operation 10a can be performed if the SOR data is not successfully received (e.g., unsuccessful or failed security check), and operation 10b can be performed if the SOR data is successfully received (e.g., successful security check).
FIG. 13 is a schematic illustrating an example network node 1300 according to some implementations of the present disclosure. For example, the network nodes 206, 208, 210, 604, 606, 704, 706, and 708 can be implemented by the network node 1300. The illustrated device 1300 includes a processing module 1302, a wired communication subsystem 1304, and a wireless communication subsystem 1306. The wireless communication subsystem 1306 can receive data traffic and control traffic from the UE. In some implementations, the wireless communication subsystem 1306 may include a receiver and a transmitter. The wired communication subsystem 1304 can be configured to transmit and receive control information between other access node devices via backhaul connections. The processing module 1302 can include one or more processing components (alternatively referred to as "processors" or "central processing units" (CPUs)) capable of executing instructions related to one or more of the processes, steps, or actions described above in connection with one or more of the implementations disclosed herein. The processing module 1302 can also include other auxiliary components, such as random access memory (RAM), read only memory (ROM), secondary storage (for example, a hard disk drive, flash memory or other non-transitory storage medium). The processing module 1302 can execute certain instructions and commands to provide wireless or wired communication, using the wired communication subsystem 1304 or a wireless communication subsystem 1306. Various other components can also be included in the device 1300.
FIG. 14 is a schematic illustrating an example UE 1400 apparatus according to some implementations of the present disclosure. The example UE 1400 includes a processing unit 1402, a computer-readable storage medium 1404 (for example, ROM or flash memory), a wireless communication subsystem 1406, an interface 1408, and an I/O interface 1410. The processing unit 1402 can include one or more processing components (alternatively referred to as "processors" or "central processing units" (CPUs)) configured to execute instructions related to one or more of the processes, steps, or actions described above in connection with one or more of the implementations disclosed herein. The processing unit 1402 can also include other auxiliary components, such as random access memory (RAM) and read only memory (ROM). The computer-readable storage medium 1404 can be embodied by a non-transitory medium configured to store an operating system (OS) of the device 1400 and various other computer-executable software programs for performing one or more of the processes, steps, or actions described above.
The wireless communication subsystem 1406 may be configured to provide wireless communications for data information or control information provided by the processing unit 1402. The wireless communication subsystem 1406 can include, for example, one or more antennas, a receiver, a transmitter, a local oscillator, a mixer, and a digital signal processing (DSP) unit. In some implementations, the subsystem 1406 can support multiple input multiple output (MIMO) transmissions. In some implementations, the receivers in the wireless communication subsystems 1406 can be an advance receiver or a baseline receiver. Two receivers can be implemented with identical, similar, or different receiver processing algorithms.
The user interface 1408 can include, for example, one or more of a screen or touch screen (for example, a liquid crystal display (LCD), a light emitting display (LED), an organic light emitting display (OLED), a microelectromechanical system (MEMS) display), a keyboard or keypad, a trackball, a speaker, and a microphone. The I/O interface 1410 can include, for example, a universal serial bus (USB) interface. A skilled artisan will readily appreciate that various other components can also be included in the example UE device 1400.
While operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be employed. Moreover, the separation of various system components in the implementation described above should not be understood as requiring such separation in all implementations, and it should be understood that the described program components and systems can generally be integrated together in a signal software product or packaged into multiple software products.
Also, techniques, systems, subsystems, and methods described and illustrated in the various implementations as discrete or separate may be combined or integrated with other systems, modules, techniques, or methods. Other items shown or discussed as coupled or directly coupled or communicating with each other may be indirectly coupled or communicating through some interface, device, or intermediate component, whether electrically, mechanically, or otherwise. Other examples of changes, substitutions, and alterations are ascertainable by one skilled in the art and may be made.
While the above detailed description has shown, described, and pointed out the fundamental novel features of the disclosure as applied to various implementations, it will be understood that various omissions, substitutions, and changes in the form and details of the system illustrated may be made by those skilled in the art. In addition, the order of method steps is not implied by the order they appear in the claims.

Steering of roaming in wireless communication networks


A novel modified polysaccharide, a solid phase to which the polysaccharide is adhered, methods for detecting N-deacetylase activity, N-sulfotransferase activity and N-deacetylase/N-sulfotransferase activity in a sample which utilizes said solid phase, and detection kits thereof.

The abbreviations to be used in the application documents are as follows.    BSA: bovine serum albumin    EDC: 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide    EDNA: ethylenediamine tetraacetic acid    ELISA: enzyme-linked immunosorbent assay    GlcA: glucuronic acid    GlcN: glucosamine    GlcNAc: N-acetylglucosamine    HEPES: 2-[4-(2-hydroxyethyl)-1-piperazinyl]ethanesulfonic acid    HP: heparin    HPLC: high-performance liquid chromatography    HRP: horseradish peroxidase    HS: heparan sulfate    IgG: immunoglobulin G    MES: 2-morpholinoethanesulfonic acid    NAH: N-acetyl heparosan    ND: N-deacetylase    NDST: N-deacetylase/N-sulfotransferase    PAPS: 5′-phosphoadenosine 3′-phosphosulfate    PBS: phosphate buffered saline    PCR: polymerase chain reaction    PDP: 2-pyridyldisulfidepropionyl    RIA: radioimmunoassay    SDS: sodium dodecyl sulfate    SPDP: N-succinimidyl-3-(2-pyridylthio)propionate    SS bond: disulfide bond    ST: N-sulfotransferase    TBS: Tris-HCl buffered saline    TMB: 3,3′,5,5′-tetramethylbenzidine
NDST is an enzyme which is concerned in the synthesis of HP and HS, and is an enzyme that has both of the ND activity and ST activity. It has been reported that 4 species of variants (NDST 1, NDST 2, NDST 3 and NDST 4) are present in NDST and their substrate specificity and the like are different from one another. For example, ND activity of NDST 3 is high and ST activity thereof is low. On the other hand, ND activity of NDST 4 is low and ST activity thereof is markedly high (Non-patent Reference 1).
It has been reported that NDST 1 knockout mice are newborn-lethal. On the other hand, although NDST 2 knockout mice do not show lethality, reduction of granules inside the mast cell, reduction of HP negative charge, reduction of the histamine content to 1/170 and the like changes have been reported (Non-patent References 2 to 8). Thus, there is a possibility that NDST is concerned in the diseases caused by such phenomena in the living body.
Regarding the method for measuring NDST activity, a measuring method which uses a substrate labeled with a radioisotope is known. According to the method, using NAH in which the acetyl group of GlcNAc residue is labeled with a radioisotope (3H) as a substrate, the ND activity of NDST is measured by measuring the amount of CH3COO3H released from the substrate by the enzymatic activity. Additionally, the ST activity of NDST is measured using PAPS labeled with a radioisotope (35S) and N-desulfated HP or N-desulfated HS, by measuring the incorporated amount of N-sulfate (35S) of said polysaccharide by the enzymatic activity (Non-patent References 1, 12 to 15, Patent Reference 1).
Additionally, although the methods for measuring NDST activity which do not use radioisotope are also known, only a sandwich ELISA method which uses a monoclonal antibody JM403 (Non-patent References 9 and 10) and an HPLC method which uses heparinase digests of the reaction product have been reported.
Although the former measuring method is a method which uses the reaction of de-N-acetylated region formed by ND with the antibody JM403, it requires two or more epitopes since it is a sandwich method. Additionally, the ST activity cannot be detected by the method (Non-patent Reference 11).
Although the latter measuring method is a method in which de-N-acetylation degree and N-sulfation degree of the de-N-acetylated NAH formed by the ND activity and ST activity and the unsaturated disaccharide obtained by the heparinase digestion of N-sulfated NAH are calculated using the "2-8 structural analysis as a combination of glycosaminoglycan degrading enzyme and HPLC" described in Non-patent Reference 16, it is not suited for chromatography, screening and the like methods for measuring activity of multiple samples (Patent Reference 2, Non-patent Reference 17).
When activities of ND, ST and NDST can be measured conveniently and quickly with high sensitivity and high accuracy and also at a moderate price, not only the detection, morbid state understanding and the like of diseases in which such enzymes are concerned and risks thereof can be easily carried out, but also screening and the like of substances which provide changes in the activities of said enzymes (inhibitors, activators and the like) can be carried out efficiently.    Patent Reference 1: US 2003/0109501A    Patent Reference 2: US 2004/0043447A    Non-patent Reference 1: Aikawa, J. et al., 2001, Journal of Biological Chemistry, vol. 276, no. 8, p. 5876-5882    Non-patent Reference Z: Humphries, D. E. et al., 1999, Nature, vol. 400, p. 769-772    Non-patent Reference 3: Forsberg, E. et al., 1999, Nature, vol. 400, p. 773-776    Non-patent Reference 4: Ringivall, M. et al., 2000, Journal of Biological Chemistry, vol. 275, no. 34, p. 25926-25930    Non-patent Reference 5: Pikas, D. E. et al., 2000, Biochemistry, vol. 39, p. 4552-4558    Non-patent Reference 6: Fukuda, M. et al., 2001, Journal of Biological Chemistry, vol. 276, no. 51, p. 47747-47750    Non-patent Reference 7: Esko, J. D. et al., 2001, Journal of Clinical Investigation, vol. 108, p. 169-173    Non-patent Reference S: Forsberg, E. et al., 2001, Journal of Clinical Investigation, vol, 108, p. 175-180    Non-patent Reference 9: van den Born, J. et al., 1992, Kidney International, vol. 41, p. 115-123    Non-patent Reference 10: van den Born, Y. et al., 1995, Journal of Biological Chemistry, vol. 270, no. 52, p. 31303-31309    Non-patent Reference 11: van den Born, J. et al., 2003, Glycobiology, vol. 13, no. 1, p. 1-10    Non-patent Reference 12: Brandan, E. et al, 1988, Journal of Biological Chemistry, vol. 263, no. 5, p. 2417-2422    Non-patent Reference 13: Bame, K. J. et al., 1991, Journal of Biological Chemistry, vol. 266, no. 16, p. 10287-10293    Non-patent Reference 14: Bame, K. J. et al., 1991, Journal of Biological Chemistry, vol. 266, no. 19, p. 12461-12468    Non-patent Reference 15: Verdugo, D. E. et al., 2002, Analytical Biochemistry, vol. 307, p. 330-336    Non-patent Reference 16: Shin Seikagaku Jikken Koza 3, Toshitsu II (published by Tokyo Kagaku Dojin, 1991), p. 49-62    Non-patent Reference 17: Saribas, A. S. et al., 2004, Glycobiology, vol. 14, no. 12, p. 1217-1228

Method for determination of N-deacetylase/N-sulfotransferase activity


A process for preparing a redistributed poly(phenylene ether), comprising reacting a poly(phenylene ether) in a reactive diluent monomer with a polyhydric phenol in the presence of a redistribution catalyst to form a composition comprising a redistributed poly(phenylene ether) in the reactive monomer diluent. The redistributed poly(phenylene ether) exhibits an intrinsic viscosity in the range of about 0.06 deciliters per gram to about 0.25 deciliters per gram, measured in chloroform at 25° C. The redistributed poly(phenylene ether) can be functionalized and admixed with unsaturated resin such as an unsaturated polyester resin or vinyl ester resin to obtain a varnish composition that, when cured, can form an electrically insulative thermoset.

Although the stator windings of electrical inductive devices, such as motors, are wound with magnet wire having enamel or other insulative coating thereon, it is often desirable to further coat the windings and seal them from the environment. For example, protection of the stator windings by an additional coating is desirable in blower motors utilized in cooling systems for locomotive traction motors. Protection is also desirable in open motors utilized in driving pumps in oil field applications, which are exposed directly to blowing sand and dirt as well as moisture.
Conventional curable varnish compositions, such as those used in certain locomotive traction motors, are so-called "solventless" varnishes based on unsaturated polyester resin (UPR). These varnish systems, however, have a glass transition temperature (Tg) significantly below 80° C. Thus, their performance at motor operating temperatures, usually about 160° C., can result in significant thermal degradation after extended operating times. In addition, such varnishes tend to chip or crack, particularly when subjected to vibrations accompanying locomotive operation. Such UPR varnishes also have a high moisture absorption rate and their ester bonds are hydrolysable, which can result in more frequent maintenance intervals than desired.
What is needed is a varnish composition that can better withstand higher temperature and a method for electrically insulating electrical devices with the varnish composition. Polyphenylene ether resins (hereinafter "PPE") are commercially attractive materials because of their unique combination of physical, chemical, and electrical properties. Furthermore, the combination of PPE with other resins can provide blends that result in additional overall properties such as chemical resistance, high strength, and high flow. However, the use of PPE, especially of low intrinsic viscosity, is relatively expensive for use in a varnish composition.
One method of making a PPE of low intrinsic viscosity is by the redistribution of the PPE by reaction with a phenolic compound. For example, UK 1 119 914 describes the redistribution of poly(phenylene ether) with phenolic compounds, designating the redistribution by the term equilibration. In the redistribution reaction, poly(phenylene ether) is dissolved in a solvent with a phenolic compound and a promoter and heated at elevated temperatures. The poly(phenylene ether) polymer is split into shorter units, wherein the phenolic compound is incorporated into the poly(phenylene ether).
More recently, redistribution of poly(phenylene ethers) employing certain classes of phenolic compounds to obtain oligomers, using toluene or a blend of toluene and an alcohol as solvent, was disclosed in U.S. Pat. No. 5,880,221. After redistribution, the poly(phenylene ether) was isolated by precipitation or evaporation of a solvent mixture.
It would be desirable to develop a commercially attractive process for preparing a varnish composition comprising PPE. It should be apparent that each process step and associated mechanical equipment such as reaction vessels used in preparing the PPE and the varnish composition are a significant consideration in determining the commercial feasibility of using PPE in a varnish composition.

Varnish compositions for electrical insulation and method of using the same


A multiplex extender 26 for permitting discrete I/O devices 34, not individually equipped to decode multiplex channel addresses, to be multiplexed on a time division multiplexed control bus 10. The multiplex extender 26 is connected intermediate the time division multiplexed control bus 10 and a branch line 30 and includes a multiplex channel address decoder 78, a data disconnect switch 82 and a branch line controller 90. The multiplex channel address decoder 78 is selectively programmed to one of the multiplex channel addresses of the time division multiplexed control bus 10. The multiplex channel address decoder 78 produces one or more output signals, each being determined by the multiplex channel address which has most recently been decoded. The data disconnect switch 82, connected in series with a data line of the time division multiplexed control bus 10 and a data line of the branch line 30, either passes or blocks the flow of data between the time division multiplexed control bus 10 and the discrete I/O devices 34 in response to the output signal from the multiplex channel decoder 78. A data latch/repeater 86, also connected to the data line of the time division multiplexed control bus 10, selectively stores data from the time division multiplexed control bus 10 or repeats previously stored data to and the discrete I/O devices 34 A branch line controller 90 transmits the previously stored data from the data latch/repeater 86 to the branch line 30 when the data disconnect switch 82 is blocking data frames from the time division multiplexed control bus 10. The multiplex extender 26 can also incorporate a heartbeat pass-through/repeater 94 for passing a heartbeat pulse to the discrete I/O devices 34 during each data frame.

It is known to use time division multiplexing on a control bus or network to increase the number of control devices which may be attached to that bus. Multiplexing increases the given number of unique I/O addresses (time slots) of the control bus by adding one or more multiplexed channels, each channel having a unique address and a number of I/O addresses. The I/O addresses of each multiplex channel are the same. Data is sent over the control bus in frames, each of which includes a particular one of the multiplex channel addresses followed by data for each of the I/O devices on that particular multiplex channel. The unique multiplex channel address ensures that only one multiplex channel can be accessed by the bus controller at a time. Since the I/O addresses on each multiplex channel are the same, each I/O device must have a decoding circuit which can decode both the multiplex channel addresses and the I/O address. This prevents an I/O device on one multiplex channel from receiving data directed to an I/O device on another multiplex channel. Output devices have an additional multiplexing problem since they require a refresh signal during each data frame. Since each data frame is addressed to a different multiplex channel address, the output devices connected to one multiplex channel will not receive their next refresh signal until all of the other multiplex channels on the control bus have received one data frame. Therefore, some means must be provided for each output device to receive a refresh signal during each data frame, regardless of the multiplex channel to which it is addressed. The extra circuitry required for decoding multiplex channel addresses and accessing refresh signals increases the cost and circuit board space requirements for each I/O device. These cost and space increases may not be as significant in the larger and more expensive analog device modules, but it can be significant in the smaller and less expensive discrete I/O device modules. Therefore, it would be desirable to have a device which could extend multiplexing capabilities to a number of down line modules, either analog or discrete I/O devices, without requiring that each module have its own multiplex channel decoder and refresh circuitry. Niobrara R&D Corporation of Joplin, Miss., has developed a device which permits the installation of discrete input devices on a time division multiplexed control bus. However, their device will not permit discrete output devices to be installed on a time division multiplexed control bus. Some control bus systems also require a "heartbeat" pulse to indicate whether or not a bus fault has occurred or whether the main (up-line) data line has failed to change states from HIGH to LOW or LOW to HIGH in the last data frame. The heartbeat pulse must be received by each I/O device during each data frame, regardless of the multiplex channel to which the frame is addressed. It is therefore required that the multiplex extending device also include circuitry for passing the heartbeat pulse to all I/O device on the control bus during each data frame. A heartbeat type control bus system is described in U.S. Pat. Nos. 4,808,994; 5,553,070 and 5,631,854 issued to Riley and U.S. Pat. No. 5,555,267 issued to Burke Jr., et al. all of which are incorporated herein by reference.

Multiplex extender for discrete I/O devices on a time division network


An elevator ice tray storage apparatus includes a storage bin and an elevator platform assembly overlying the bottom of the storage bin. The assembly includes a base member which slides on the bottom of the storage bin, and a platform for elevating an ice tray into a first elevated storage position. A handle and guides are provided for facilitating the manipulation of the elevator assembly. Rollers are provided at the back end of the platform for rolling against the back end wall of the storage bin as the elevator assembly elevates an ice tray. One or more elevated storage positions are provided, each having hinged flaps that rotate out of the way to allow a tray to pass by as it is being elevated and which rotate back to a flat repose position, on which side edges of a tray are lowered to rest.

1. Field of the Invention
The invention relates to the storage of ice trays in a refrigerator freezer portion where the trays are stored in a stacked orientation inside a bin using an elevator platform to insert each consecutive tray.
2. Description of Related Art
Ice trays and methods of stacking are known in the art. However, most are designed such that the trays themselves are independently stackable or are stackable within a container bin.
All of these prior art devices still have disadvantages when a tray freshly filled with water is inserted in the freezer. For example, as a consumer attempts to reach in and place a tray on top of another, water often times is spilled over to the side. If a tray already placed on top of a tray with frozen ice cubes, has yet to freeze and a consumer desires ice cubes, the consumer must carefully raise the tray with water and carefully pull the lower tray out of the freezer. This inevitably leads to some spilling of water more often then not because of the coordination required when a consumer at eye level is reaching away from his body to handle trays with fingers.
When other objects in the freezer do not stack well such as frozen backs of french fries or chicken fillets, or certain meats such as hamburger packages, they often slide to side against stacked trays which again may spill water if not yet frozen. Frozen water on the bottom surface of a freezer not only affects the efficiency of the freezer portion but if the water works its way into the coil portion of the freezer, then the coils may freeze over making the freezer portion work extremely inefficient.
Known related art includes the ice tray and storage container depicted in U.S. Pat. No. 3,670,523 to Fogt et al., the pan and ice trays depicted in U.S. Pat. No. 3,352,528, the stackable ice tray and bin assembly depicted in U.S. Pat. No. 5,830,379 to Tunzi, the container and ice cube tray assembly depicted in U.S. Pat. No. 4,789,130 to Stich et al. and the rotatable ice cube tray unit depicted in U.S. Design Pat. No. Des. 307,280 to Waller et al.
The Waller unit assumes that the trays contain frozen ice and the trays themselves are designed so that when the bottom tray is pulled, as shown in FIG. 7, a careful view of FIG. 8 shows that the next tray above the pulled tray will drop down, most likely starting from the back end, until it fully drops to the bottom surface of the bin. If any trays still have unfrozen water in the cube portions, water is certain to spill inside the bin.
None of the devices in the above references solve the problem of ensuring that any tray containing water is inserted while supported to prevent spillage, and is stacked in relation to other trays in such a way that the other trays are not tipped or fall over.
The present invention is an elevator ice tray storage apparatus which includes an ice tray storage bin having a bottom, opposite spaced-apart side walls, a back end wall and an open front end; and means for elevating ice trays to a first elevated storage position, said first elevated storage position having means for level supporting of ice tray side edges along the side walls of the storage bin, wherein when said means for elevating ice trays is lowered to its lowest position, a height between said means for elevating ice trays and a lower surface of a first ice tray being supported at the first elevated storage position is sufficient to enable a second ice tray to be placed on said means for elevating ice trays.
The means for elevating ice trays includes an elevator platform assembly in an overlying relationship to the bottom of the storage bin. The elevator platform assembly includes a base member which is in a slidable relationship with the underlying bottom of the storage bin, and a platform parallel to and above the base member, the platform constituting a platform for supporting and elevating an ice tray to be stored in the storage bin at the first elevated storage position.
A first riser member is pivotally connected to an upper surface of the base member near a back end of said base member. This first riser member is also pivotally connected to a lower surface of the platform at a predetermined distance from a back end of said platform. A second riser member is pivotally connected to the upper surface of the base member at a predetermined distance from a front end of said base member. As with the first riser member, this second riser member is also pivotally connected to the lower surface of the platform at a predetermined distance from a front end of said platform. The first and second riser members are the same height and pivotally connected so as to maintain a parallel relationship as the elevator platform assembly is manipulated.
The back end of said platform further has roller means which engage the back end wall of the storage bin and roll up and down the back end wall of the storage bin as the elevator platform assembly is manipulated to store ice trays in the storage bin. The back end of the platform and the back end of the base member are offset from each other such that the back end of the base member is spaced from the back end wall of the storage bin a distance greater than a distance of the back end of the platform from the back end wall of the storage bin.
In other embodiments of the invention where more than two trays are intended to be stored, that is, one at the first elevated storage position and one on the platform, the invention includes a second elevated storage position above the first elevated storage position or a second and third elevated storage position, the third elevated storage position being above the second elevated storage position. The second elevated storage position has means for level supporting of ice tray side edges along the side walls of the storage bin and the third elevated storage position also has means for level supporting of ice tray side edges along the side walls of the storage bin.
In operation, when a second ice tray is elevated for placement at the first elevated storage position, the second ice tray comes into contact with the first ice tray. The means for elevating ice trays then elevates both the first and second ice trays until the first ice tray is positionable at the second elevated storage position. The means for elevating ice trays is then lowered so that the first ice tray comes to rest on the means for level supporting of ice tray side edges at the second elevated storage position. When the third elevated storage position is incorporated into the apparatus, the third ice tray is elevated for placement at the first elevated storage position, the third ice tray comes into contact with the second ice tray, and the second ice tray then comes into contact with the first ice tray as the means for elevating ice trays continues to elevate, the means for elevating ice trays then elevates the first, second and third ice trays until the first ice tray is positionable at the third elevated storage position, the means for elevating ice trays is then lowered so that the first ice tray comes to rest on the means for level supporting of ice tray side edges at the third elevated storage position, the means for elevating ice trays then continues to be lowered until the second ice tray comes to rest on the means for level supporting of ice tray side edges at the second elevated storage position, the means for elevating ice trays then continues to be lowered so that the third ice tray comes to rest on the means for level supporting of ice tray side edges at the first elevated storage position.
It is preferred that the bottom of the storage bin includes means for guiding the travel of the base member in and out of the storage bin from the front end of the storage bin.
The means for level supporting of ice tray side edges along the side walls of the storage bin at the first, second or third elevated storage positions preferably includes at least one longitudinally hinged ice tray support on each side wall, each being parallel to and of substantially equal distance from the bottom of the storage bin, with each at least one longitudinally hinged ice tray support constituting a flap which is rotatable from a generally horizontal planar position of repose to a generally vertical position when side edges of the ice tray to be stored engage corresponding opposite flaps while being elevated to the first elevated storage position, and the corresponding opposite flaps returning to the repose position after each tray is elevated past a rotated height of the flaps. When the ice tray to be stored is then lowered, its corresponding side edges engage and rest on the corresponding opposite flaps.
When the ice tray is placed on the platform for elevated storage, the base member is pushed toward the back end of the bin, simultaneously allowing the roller means at the back end of the platform to vertically roll against the end wall of the storage bin and in turn rotating the riser members toward a vertical orientation until the platform elevates the ice tray a sufficient height so its side edges engage and upwardly push the first row of the corresponding opposite flaps, passing said corresponding opposite flaps at the first elevated storage position to allow them to return to the position of repose, and when the base member is then pulled back to lower the platform, the ice tray lowers and its side edges engage the corresponding flaps in the position of repose, allowing the platform to be lowered a sufficient spacing from a bottom of the ice tray stored in the first elevated storage position to further allow the subsequent placement of the second ice tray on the platform.
The means for guiding the travel of the base member preferably includes means for minimizing one of lateral movement, vertical movement and a combination of lateral and vertical movement of the base member as it slides in and out of the storage bin. In addition, the base member should include means for facilitating the sliding of the base member in and out of the front end of the storage bin while inserting an ice tray, such as handle means on a portion of the base member adjacent the front end of the storage bin.
In order to maintain some rigidity or at least to prevent the upper portion of the storage bin from spreading open which could make an ice tray dislodge from the supporting flaps, it is recommended that means at the top of the storage bin for maintaining the side walls in a generally parallel relationship be provided. This can simply be some bracing or strapping like members across designated portions at the top of the storage bin, in particular, at least across the front edge or near the front edge of the storage bin.
The storage bin bottom, side walls and back end wall may be continuously formed such as in an injection molding process therein making the joints integral, or they may be fixedly connected such as by adhesive or other mechanical means like fasteners, or a combination of such means may be incorporated.
It is not necessary that the platform be allowed to be lowered such that the platform, riser members and base member essentially lay on top of the other; however, it is recommended that a first support member vertically extending from the bottom of the storage bin near the back end of the storage bin for support engagement of the platform in its lowered position be provided, and a second support member vertically extending from an intermediate location on the base member of the elevator platform assembly for support engagement of the platform in its lowered position be provided. The first and second support members are dimensioned so as to maintain the platform in a generally parallel relationship to the bottom of the storage bin, yet spaced apart a desired predetermined distance.
If the riser members rotate 90xc2x0 or greater, it is possible that when the base member is pulled to start lowering the trays, that all the trays will instead come out of the storage bin at once and the platform will not lower unless the riser members are caused to be nudged to less than a 90xc2x0 orientation. If this is undesirable, then it is recommended that means for limiting the inward travel of the base member be provided so that the first and second riser members are prevented from elevating into this generally vertical orientation.
Although it may be preferred that the elevator platform assembly be readily removable from the storage bin to provide ready access for cleaning the storage bin, means for limiting the outward travel of the base member to prevent the elevator platform assembly from completely exiting the storage bin, may optionally be provided.


Provided are an apparatus and a method that can acquire a shaded three-dimensional image having a high contrast for a thick cell culture specimen. Provided are an apparatus and a method that observe a biological sample accommodated in a container by a modulation contrast method using a near-infrared wavelength, at least the bottom surface of the container being formed of a plastic raw material.

In recent years, with progress of stem cell research and regenerative medicine, stereoscopic cells have been prepared for transplantation and other uses. Cells for transplantation are preferably those which are not labeled with fluorescence or the like, and it has been required to observe three-dimensional thick cultured cells (for example, spheroids, cell sheets, etc.) by non-labeling.

Cell observation apparatus and cell observation method


A variable-gain amplifier includes an amplifier stage; an attenuating network receiving an input signal; a plurality of transconductance stages, connected between respective nodes of the attenuating network and the amplifier stage, wherein each of the transconductance stages has a differential circuit, configured to supply differential currents to the amplifier stage; and a gain-control circuit for controlling the transconductance stages according to an electrical control quantity. Each of the transconductance stages further includes a current-divider circuit associated to the differential circuit and controlled by the gain-control circuit so as to divide the differential currents between the amplifier stage and a dispersion line proportionally to the control quantity.

1. Field of the Invention
The present invention relates to a variable-gain amplifier with high linearity as to gain variations.
2. Discussion of the Related Art
In the field of analog electronics, it is known to use variable-gain amplifiers when signals of very different amplitudes on particularly wide frequency bands are to be processed. In these cases, variable-gain amplifiers enable adapting the amplitude of the output signal to the specific working conditions, preventing saturation of the downstream-connected stage and without degrading the linearity of the signal.
Variable-gain amplifiers of the type designated by the reference number 1 in FIG. 1, are known. They include an attenuating network 2, a plurality of transconductance stages 3, a constant-gain amplifier 5, and a gain-control stage 6, which is associated to the transconductance stages 3. The attenuating network 2 is of the ladder resistive type and receives an input voltage VIN on inputs 2a, 2b. The transconductance stages 3 have first inputs each connected to a respective node 2c of the attenuating network 2 and second inputs connected to the output of the constant-gain amplifier 5 through a feedback line 7. The outputs of the transconductance stages 3 are connected to an input of the constant-gain amplifier 5. The gain-control stage 6 supplies a total constant biasing current IB, which is split among the transconductance stages 3 in a proportion indicated by a control voltage VC. In practice, it is possible to control the weight of each transconductance stage 3 for driving the constant-gain amplifier 5. The overall gain of the variable-gain amplifier 1 is greater when one of the transconductance stages 3 closest to the inputs 2a, 2b of the attenuating network 2, receiving the least attenuated input voltage VIN, prevails, and smaller when one of the transconductance stages 3 furthest from the inputs 2a, 2b prevails. The overall gain of the variable-gain amplifier 1 can thus be controlled over a wide range of values.
Known variable-gain amplifiers have, however, some drawbacks, in particular because the conditions of biasing and thus the transconductance of the individual transconductance stages vary. Even though it is possible to obtain a good linearity between the control voltage and the overall gain (designated, respectively, by VC and A in the plot of FIG. 2a), however, the harmonic distortion, for example, the third-order one, disadvantageously has an irregular pattern as the control voltage varies. In this connection, see the plot of FIG. 2b, where the third-order harmonic distortion is designated by HD3.

Variable-gain amplifier with high linearity as to gain variations


A method and system for measuring a characteristic of a machine is provided. The system includes a speed sensor including a housing, a variable reluctance sensor (VRS) mounted at least partially within the housing, and a digitization circuit electrically coupled to an output of the VRS. The digitization circuit is also mounted within the housing and is configured to convert a substantially sinusoidal output of the VRS into a digital output signal.

The field of the invention relates generally to variable reluctance speed sensors, and more specifically, to signal conditioning of variable reluctance speed sensor output signals.
At least some known variable reluctance sensors include wire wrapped around a permanent magnet and are configured to sense a steel target that is part of a rotating assembly. For example, in an industrial application, the steel target may be coupled to, and rotate with, a rotor of a generator. As the steel target passes the variable reluctance sensor, a magnetic field produced by the sensor is disrupted, producing a sinusoidal voltage signal. Variable reluctance speed sensors are self-powered devices that provide an approximately 0.7 Volt peak-to-peak output at relatively low engine speeds and an approximately 50 Volt peak-to-peak output at relatively high speeds. The low output voltage signals generated at low engine speeds are difficult to accurately measure by the engine control circuitry and often require extensive filtering and signal amplification stages. The frequency and amplitude of the sinusoidal voltage signal are proportional to the speed of the rotor. The amplitude of the sinusoidal voltage signal output by the sensor is also dependent upon the distance between the sensor and the steel target. Because variable reluctance sensors do not require external power to generate an output signal, they are also referred to as "passive" magnetic sensors. The sensor output is provided to remote signal-processing circuitry for analysis. The signal-processing circuitry is positioned remotely from the sensor due to high temperatures and/or other harsh environmental conditions present at the position of the sensor. Due in part to the remote positioning of the signal-processing circuitry, if the circuitry is configured to analyze sensor output from a high speed rotor, the sensor may not produce an output signal with an adequate amplitude for signal-processing when the rotor is rotating at a low speed. However, incorporating signal conditioning circuitry within the speed sensor is problematic for two reasons, the high temperature environment (180° C.+) does not permit the use of cost effective integrated circuits, and employing electronics within sensors typically increases the number of wires and weight required to implement the interconnecting speed sensor and engine control harness.

Method and apparatus for amplified variable reluctance speed sensor


An integrated circuit including an amplifier and a first circuit. The amplifier is configured to receive a sensed signal and provide an amplified signal. The first circuit is configured to track a first signal that is based on the amplified signal. The first circuit includes a first comparator, tracking logic and a first digital to analog converter. The first comparator is configured to respond to a second signal that is based on the first signal and provide a comparator output signal. The tracking logic is configured to receive the comparator output signal and update a digital output. The first digital to analog converter is configured to receive the digital output and provide a tracking signal that is summed with the first signal to provide the second signal.

Sensors are employed in a wide range of technological applications including automotive, industrial and consumer applications. These applications need sensors that operate reliably according to specified performance characteristics. For this reason, sensors are calibrated to offset deviations in sensor performance and to ensure that measurements are performed accurately. The sensor industry has developed self-calibrating sensors to reduce calibration time and cost. Self-calibrating sensors include some Hall effect sensors, magneto-resistive sensors and other suitable sensors.
Usually, in Hall effect sensors, a constant current is provided to a Hall element or plate and a magnetic field is applied perpendicular to the current flowing through the Hall plate. Charge carriers in the Hall plate are deflected due to the Lorentz force to create a Hall voltage that is perpendicular to both the magnetic field and the current flow. This Hall voltage can be measured and is directly proportional to the magnetic field. Hall effect sensors are used for speed, rotational speed, linear position, linear angle and position measurements in automotive, industrial and consumer applications.
Magneto-resistive (XMR) sensors, typically, include a supporting magnet and one or more XMR sensor elements for measuring a magnetic field. The supporting magnet and the XMR sensor elements are in a fixed position relative to each other. The XMR sensor elements do not usually operate in their saturation range and the supporting magnet provides a back bias magnetic field that is superimposed on the XMR sensor elements to stabilize the transfer characteristic of the XMR sensor elements. As the position of a detected object changes relative to the source of the magnetic field, the magnetic field produces a proportional voltage signal in the XMR sensor elements. Suitable XMR sensor elements include anisotropic magneto-resistive (AMR) sensor elements, giant magneto-resistive (GMR) sensor elements, tunneling magneto-resistive (TMR) sensor elements, and colossal magneto-resistive (CMR) sensor elements. XMR sensors can be used as proximity sensors, motion sensors, position sensors, or speed sensors.
Typically, self-calibrating sensors with switching outputs are self-adjusted to a switching point. Minimum and maximum values of the incoming signal are obtained and the switching point is calculated from them. For example, the optimum switching point may be exactly half-way between the maximum and minimum values. Usually, a fast regulation or tracking loop follows the incoming signal to determine an offset signal, which is summed with the incoming signal to adjust the incoming signal to the switching point. In the adjusted condition, the offset signal is a DC signal that is overlaid on the incoming signal. A main comparator receives the incoming signal or a signal based on the incoming signal and provides an output that switches from one state to another.
The resolution of the tracking loop must be high enough to track the incoming signal and provide the offset signal. Also, sometimes the tracking loop circuitry cannot follow offset jumps in the incoming signal, where the offset jumps may be caused by external disturbances or the changing of a sensor air-gap. In addition, the tracking loop often includes circuitry that introduces errors into the incoming signal, such as amplifiers that introduce offset error, gain error and noise, and comparators that introduce offset error.
For these and other reasons there is a need for the present invention.


A cartridge for a valve housing having outlets, the cartridge comprising a stationary body sleeve for fixed insertion within the housing and having outlet ports permanently aligned with the outlets of the housing, a moveable substantially hollow stem sleeve inserted within the stationary body sleeve and having an opening selectively alignable with the ports of the stationary body sleeve, the body sleeve and hollow stem being connected to one another by a retaining ring which aligns and maintains the cartridge as a unit in the housing.

Back flow preventers are used in commercial and household installations, for example, bidets, Roman tubs, barber shop and hairdressing salon fixtures, laboratory sinks, food processing facilities, chemical manufacturing, metal plating facilities, just to name a few, to prevent the contamination of the potable water supply. The water in each case is used in different manners and the installation of back flow preventers and check valves would be required for each use to protect the water supply from contamination or a separate back flow preventer and check valve would be installed in the line in advance of the components in the system. For example, in a bidet, the water is diverted to the rim or the spray. In a soaking or whirlpool bath tub the water is diverted to the spout, shower head or removable handheld shower. A number of proposals have been made for the diversion of fluids. Various methods and devices have been used to protect the potable water system from contamination. The premises may be isolated to protect the purveyor's water distribution system by installing a back flow preventer at the water line into the building. an area may be isolated when a portion of the building has toxic material used there. That portion of the building should be isolated by installing a back flow preventer so as to protect the individual using the water within the building. Finally one may individually isolate each fixture or piece of equipment from the water system such as is the case in Applicant's own structure described in Canadian Patent 1,225,006 which provides back flow prevention, in a compact, easily manufactured, effective unit. The present invention describes improvements thereto by adding a plurality of checking devices and improves the structure and repair of the diverting valve.
It is therefore an object of this invention, to provide a diverter valve with, integral atmospheric type vacuum breaker and inlet and outlet check valves in an integral structure which is entirely reliable and easily serviced.
Further and other objects of the invention will be realized by those skilled in the art from the following summary of the invention and detailed description of preferred embodiments thereof.

Diverter valves with integral back flow preventer and inlet and outlet check valve mechanisms