IMS PDN/PDU FOR EMERGENCY CALL

Solutions for placing an emergency call over a wireless network improve speed and reliability by prioritizing using an internet protocol (IP) multimedia subsystem (IMS) packet data network (PDN) or protocol data unit (PDU) network (PDN/PDU) over domain reselection when a call attempt fails over an emergency PDN/PDU (EPDN/EPDU). Examples include establishing an IMS PDN/PDU session for a user equipment (UE) over a wireless network; attempting, by the UE, an emergency call using an EPDN/EPDU over the wireless network; and based on at least a failure of the emergency call over the EPDN/EPDU, reattempting the emergency call using the IMS PDN/PDU over the wireless network. Based on at least a failure of the emergency call over the IMS PDN/PDU, the UE performs domain reselection and reattempts the emergency call using a second wireless network. In some examples, wireless networks transmit a network policy for handling the emergency call to the UE.

BACKGROUND

When a user equipment (UE) attempts to place an emergency call over a cellular network, the default behavior is for the UE to attempt to setup a new session over an emergency packet data network (EPDN) or emergency protocol data unit (EPDU) network (EPDN/EPDU). However, if there is a problem that prevents the call from connecting, the UE will perform domain reselection, and attempt to connect the emergency call using a different network—also through an EPDN/EPDU, but using the different network. Unfortunately, if the other network is unavailable for any reason, or the attempt through the other EPDN/EPDU fails, the UE's ability to make the emergency call will be frustrated and delayed.

SUMMARY

The following summary is provided to illustrate examples disclosed herein but is not meant to limit all examples to any particular configuration or sequence of operations.

Disclosed solutions for placing an emergency call over a wireless network improve speed and reliability by prioritizing using an internet protocol (IP) multimedia subsystem (IMS) packet data network (PDN) or protocol data unit (PDU) network (IMS PDN/PDU) over domain reselection when a call attempt fails over an emergency PDN (EPDN) or emergency protocol data unit (EPDU) network (EPDN/EPDU). Examples include establishing an IMS PDN/PDU session for a user equipment (UE) over a first wireless network: attempting, by the UE, an emergency call using an EPDN/EPDU over the first wireless network; and based on at least a failure of the emergency call over the EPDN/EPDU, reattempting the emergency call using the IMS PDN/PDU over the first wireless network. Based on at least a failure of the emergency call over the IMS PDN/PDU, the UE performs domain reselection and reattempts the emergency call using a second wireless network. In some examples, the first wireless network transmits, to the UE, a network policy for handling the emergency call.

Corresponding reference characters indicate corresponding parts throughout the drawings. References made throughout this disclosure. relating to specific examples, are provided for illustrative purposes, and are not meant to limit all implementations or to be interpreted as excluding the existence of additional implementations that also incorporate the recited features.

DETAILED DESCRIPTION

Disclosed solutions for placing an emergency call over a wireless network improve speed and reliability by prioritizing using an internet protocol (IP) multimedia subsystem (IMS) packet data network (PDN) or protocol data unit (PDU) network (IMS PDN/PDU) over domain reselection when a call attempt fails over an emergency PDN (EPDN) or emergency protocol data unit (EPDU) network (EPDN/EPDU). Examples include establishing an IMS PDN/PDU session for a user equipment (UE) over a first wireless network: attempting, by the UE, an emergency call using an EPDN/EPDU over the first wireless network; and based on at least a failure of the emergency call over the EPDN/EPDU, reattempting the emergency call using the IMS PDN/PDU over the first wireless network. Based on at least a failure of the emergency call over the IMS PDN/PDU, the UE performs domain reselection and reattempts the emergency call using a second wireless network. In some examples, the first wireless network transmits, to the UE, a network policy for handling the emergency call.

Aspects of the disclosure enhance public safety by improving the connection speed of emergency calls placed over cellular networks, as well as enabling emergency center call-back. This is accomplished, at least in part by, based on at least a failure of an emergency call over an EPDN/EPDU, reattempting the emergency call using an IMS PDN/PDU over a wireless network. This provides multiple advantages over current solutions, which are specified in Third Generation Partnership Project (3GPP) technical standards (TSs).

Advantages include faster call connection by avoiding time-consuming domain reselection, when the emergency call is successful with the IMS PDN/PDU; potentially improved location information for the UE available to first responders; and providing for emergency center call-back. Emergency calls placed by UEs over cellular networks, for example enhanced 911 (e911) calls in the United States (US) and enhanced 112 (e112) calls in the European Union (EU), are typically answered and handled by a public safety answering point (PSAP). If the emergency call is disconnected, the PSAP may need to call the UE back.

However, if the UE performed domain reselection, and is on a visited network, not fully authenticated, the UE call-back information (e.g., the UE phone number) might not be provided to the PSAP. Further, the UE's location may not be known with the same degree of accuracy as to the visited network, as it had been to the cellular network on which it had been prior to domain reselection. Whereas the prior cellular network may have received global positioning system (GPS) coordinates from the UE, the visited network may not have had time to receive the GPS coordinates and so may only know the location of the UE based on the location of the serving base station. Thus, the proposed solution of retaining the UE on the original cellular network, and using the IMS PDN/PDU, rather than performing domain reselection (as specified by 3GPP in certain circumstances) improves public safety.

With reference now to the figures,FIG.1illustrates an architecture100that advantageously provides for a UE102placing an emergency call106over a wireless network110using an IMS PDN/PDU132. UE102has an emergency call manager142(shown as EMC MGR) that controls the actions of UE102for placing emergency call106to a PSAP150. Emergency call manager142uses a network policy140that, in some examples is downloaded from wireless network110, to dictate how UE102reattempts emergency call 1-6 when experiencing call failures.

In some examples, UE102has a version of network policy140installed by its home network. In some examples, UE102downloads network policy140upon registration with a new wireless network, such as wireless network110or other wireless network160. In some examples, wireless networks110and160push their own copies of network policy140to all UEs that register. In examples in which wireless networks110and160have different versions of network policy140, network policy140is based on which wireless network to which UE102is attached.

For example, if UE102reports its location (e.g., GPS coordinates) to wireless network110as being somewhere in which UE102is also likely within coverage of wireless network160, wireless network110selects and sends UE102network policy140that instructs UE012to (1) attempt emergency calls first with an EPDN/EPDU, then if that attempt fails, (2) next attempt with an IMS PDN/PDU, then if that attempt fails, (3) next perform domain reselection and attempt the emergency call on the new network (e.g., cellular network160).

However, if UE102reports its location to wireless network110as being somewhere in which UE102is likely not within coverage of any other wireless network other than wireless network110, domain reselection will waste valuable time for the user of UE102. So instead, wireless network110selects and sends UE102a different network policy140that instructs UE012to (1) attempt emergency calls first with an EPDN/EPDU, then if that attempt fails, (2) next attempt with an IMS PDN/PDU, then if that attempt fails, (3) alternate between attempting with the EPDN/EPDU again and the IMS PDN/PDU again and only try domain reselection after some specified minimum number of further attempts with the EPDN/EPDU and IMS PDN/PDU.

UE102connects to a radio access network (RAN)112of wireless network110using an air interface104. Wireless network110also has an access node120, a session management node122, a policy node124, a packet routing node126, and a proxy node128. In some examples, wireless network stories copies of network policy140in policy node124, and in some examples may have multiple network policies140that are selected based on at least the location of UE102. In some examples, proxy node128comprises a proxy call session control function (P-CSCF).

In fifth generation (5G) cellular examples, RAN112comprises a gNode B (gNB), access node120comprises an access mobility function (AMF), session management node122comprises a session management function (SMF), policy node124comprises a policy control function (PCF), and packet routing node126comprises a user plane function (UPF). Also, in 5G, IMS PDN/PDU132uses a PDU network. In fourth generation (4G) cellular examples, RAN112comprises an eNodeB (eNB), access node120comprises a mobility management entity (MME), session management node122comprises a system architecture evolution gateway (SAEGW) control plane (SAEGW-C), policy node124comprises a policy and rules charging function (PCRF), and packet routing node126comprises a SAEGW-user plane (SAEGW-U). An SAEGW is a combination of a serving gateway (SGW) and a packet data network gateway (PGW). Also, in 4G, IMS PDN/PDU132uses a PDN.

Access node120, session management node122, and policy node124carry signaling, such as call setup signaling, and are within a control plane of wireless network110. Packet routing node126and proxy node128carry data packets, such as voice data packets, and are within a user plane of wireless network110.

Proxy node128communicates with an IMS130, which has IMS PDN/PDU132and a border gateway134. IMS130connects wireless network110with PSAP150, either with a packet switched connection, or with a circuit switched connection, such as through a public switched telephone network (PSTN)154. In some examples, border gateway134provides the connection for IMS130between proxy node128and PSTN154, bridging packet switched and circuit switched networks.

Proxy node128also permits wireless network110to connect to PSAP through an EPDN/EPDU138. Packet routing node126connects to a PDN156(e.g., the internet) for other data services. Wireless network160may be configured similarly to wireless network110.

FIGS.2and3illustrate message sequence diagrams200and300, respectively, for messages that may be used in (e.g., routed through) architecture100, when UE102attempts to place emergency call106. Message sequence diagram200ofFIG.2shows messages for when the initial attempt to place emergency call106through EPDN/EPDU138is unsuccessful, but an attempt to place emergency call106through IMS PDN/PDU132is successful. Message sequence diagram300ofFIG.3shows messages for when the initial attempt to place emergency call106through EPDN/EPDU138, and the reattempt through IMS PDN/PDU132, are both unsuccessful, and so UE102performs domain reselection to place emergency call106through cellular network160.

FIGS.2and3are described in conjunction with the description ofFIG.4, which illustrates a flowchart400of exemplary operations associated with UE102placing emergency call106. In some examples, at least a portion of flowchart400may be performed using one or more computing devices800ofFIG.8. Flowchart400commences with UE102registering with wireless network110in operation402. In some examples, UE102is in roaming coverage when connected to wireless network110. The registration of operation402is shown as message202a(UE102registering with RAN112) and message202b(UE102also registering with access node120) inFIG.2. ForFIG.3, messages202a-236are the same as inFIG.2.FIG.3has further messages that are unique to operations436-440of flowchart400.

The location of UE102determined in operation404. Initially, wireless network110may use the known location of the serving cell site of RAN112, until UE10obtains its location via GPS or other means, which is shown as message204, and reports its location to wireless network110(e.g., session management node122) using message206.

Operation406establishes PDN connectivity (4G) or a PDUs session (5G) with IMS PDN/PDU132, which is provided as IMS PDN/PDU session212(seeFIG.2), over wireless network110with messages208a-210c. UE102requests a PDN/PDU connection using message208ato access node120, which creates a request message208bto session management node122, which forwards the request to policy node124using message208c. Policy node124returns a create session response as message210ato session management node122, which forwards the response to access node120using message210b. Access node120sends a connectivity accept message210cto UE102.

Network policy140is selected for UE102in operation408. Session management node122uses message214to request policy node124to select a network policy140for UE102, for example, based on at least the location of UE102. Policy node124select a preferred network policy140, shown as message216, and sends it to session management node122using message218a. In some examples, network policy140specifies that emergency call106is to be attempted over EPDN/EPDU138first and IMS PDN/PDU132second. In some examples, network policy140further specifies that domain reselection is to be performed after emergency call106fails with IMS PDN/PDU132. In some examples (e.g., when wireless networks110and160have different sets of network policies140), network policy140is based on at least UE102being attached to wireless network110.

In operation410, wireless network110transmits network policy140to UE102using message218b, and UE102receives network policy140from wireless network110. The user of UE102uses UE102to initiate emergency call106in operation412, which is shown as message220. In some examples, emergency call106comprises a 911 call or a 112 call, which may be e911 and e112 calls when placed from a UE connected to a wireless network.

In operation414, UE102(e.g., following network policy140), attempts emergency call106using EPDN/EPDU138over wireless network110. This uses messages222a-224cand message230. Messages222a-224care similar to messages206a-210c, but are for setting up an EPDN/EPDU session226(rather than IMS PDN/PDU session212). Operation414uses operation416to set up EPDN/EPDU session226, and operation418to transmit an SOS Invite message230to EPDN/EPDU138.

If the setup of EPDN/EPDU session226is successful, it is accomplished in this manner: UE102requests a PDN connection using message222ato access node120, which creates a request message222bto session management node122, which forwards the request to policy node124using message222c. Policy node124returns a create session response as message224ato session management node122, which forwards the response to access node120using message224b. Access node120sends a connectivity accept message224cto UE102.

There are two error scenarios described herein. In one error scenario, the setup of EPDN/EPDU session226is successful within the allotted time, an emergency call IMS registration228is successful, and after UE102transmits SOS Invite message230to EPDN/EPDU138, EPDN/EPDU138returns (transmits) an error message232to UE102, such as a session initiation protocol (SIP) error. In some examples, the SIP error comprises a three-digit error code starting with 4, 5, or 6 (e.g., 4xx/5xx/6xx).

Another error scenario is that either the setup of EPDN/EPDU session226or emergency call IMS registration228is unsuccessful within the allotted time. Both error conditions are captured in operation420.

Decision operation422determines whether the attempt to make emergency call106using EPDN/EPDU138has failed, and is performed using flowchart500ofFIG.5. Turning briefly toFIG.5, flowchart500is described. In some examples, at least a portion of flowchart500may be performed using one or more computing devices800ofFIG.8. Flowchart500is used as the process for both decision operation422, which determines whether the attempt to make emergency call106using EPDN/EPDU138has failed, and also for decision operation436below, which determines whether the attempt to make emergency call106using IMS PDN/PDU132has failed.

In some examples, the operations of flowchart500are carried out within emergency call manager142of UE102. Flowchart500commences with decision operation502determining whether an error message (e.g., error message232or an error message302ofFIG.3) has been received. In some examples, an error message is a SIP error code starting with 4, 5, or 6. If so, operation504, returns a failure condition (e.g., sets a failure flag), and flowchart400resumes.

However, if an error message has not been received, decision operation506determines whether there is a timeout condition. If so, flowchart500moves to operation504to return the error condition. Otherwise, operation508returns success (no failure), for example by setting a success flag, and flowchart400resumes.

Returning to flowchart400ofFIG.4, if the attempt to make emergency call106using EPDN/EPDU138did not fail, flowchart400moves to operation424. In operation424, based on at least a successful attempt at placing emergency call106using IMS PDN/PDU132, wireless network110hosts emergency call106, and UE102connects to emergency call106.

However, in this example, the attempt to make emergency call106using EPDN/EPDU138did fail, so flowchart400moves to operation426. Emergency call manager142consults network policy140, shown as message234, and of UE102reattempts emergency call106using IMS PDN/PDU132over wireless network110. As part of operation426, UE102transmits an SOS Invite message236to IMS PDN/PDU132in operation428.

Decision operation430determines whether an error condition prevents completion of emergency call106over IMS PDN/PDU132. If emergency call106can proceed over IMS PDN/PDU132, a create session message238is sent (transmitted) to UE102in operation432. Message238is shown only inFIG.2.

In the alternative, if an error condition prevents placing emergency call106over IMS PDN/PDU132, error message302is sent (transmitted) to UE102in operation434. Error message302is shown only inFIG.3. Error message302may be similar to error message232. Decision operation436determines whether the attempt at making emergency call106using IMS PDN/PDU132has failed, and is performed using flowchart500as described above.

If the attempt has not failed, then remaining with the messages ofFIG.2, a connection accept message238is sent to UE102, and flowchart400moves to operation424.

However, if the attempt has failed, emergency call manager142consults network policy140and performs domain reselection in operation438, selecting wireless network160. This is shown as message304inFIG.3. UE102registers with wireless network160using message306. In operation440, UE102reattempts emergency call106wireless network160, and flowchart400moves to operation424.

FIG.6illustrates a flowchart600of exemplary operations associated with examples of architecture100. In some examples, at least a portion of flowchart600may be performed using one or more computing devices800ofFIG.8. Flowchart600commences with operation602, which includes establishing, between a UE and an IMS PDN/PDU, an IMS PDN/PDU session over a first wireless network.

Operation604includes attempting, by the UE, an emergency call using an EPDN/EPDU over the first wireless network, and is performed using operation606, which includes attempting to establish, between the UE and the EPDN/EPDU, an EPDN/EPDU session over the first wireless network. Operation608includes, based on at least a failure of the emergency call over the EPDN/EPDU, reattempting the emergency call using the IMS PDN/PDU over the first wireless network.

FIG.7illustrates a flowchart700of exemplary operations associated with examples of architecture100. In some examples, at least a portion of flowchart700may be performed using one or more computing devices800ofFIG.8. Flowchart700commences with operation702, which includes establishing, between a UE and an IMS PDN/PDU, an IMS PDN/PDU session over a first wireless network.

Operation704includes transmitting, by the first wireless network, to the UE, a network policy for handling an emergency call, the network policy prioritizing the IMS PDN/PDU over domain reselection. Operation706includes, based on at least an attempt by the UE to place the emergency call using the EPDN/EPDU, attempting to establish, between the UE and the EPDN/EPDU, an EPDN/EPDU session over the first wireless network. Operation708includes transmitting, to the UE, a first SIP error. Operation710includes, based on at least an attempt by the UE to place the emergency call using the IMS PDN/PDU, attempting to establish, between the UE and the IMS PDN/PDU, an IMS PDN/PDU session over the first wireless network.

FIG.8illustrates a block diagram of computing device800that may be used as any component described herein that may require computational or storage capacity. Computing device800has at least a processor802and a memory804that holds program code810, data area820, and other logic and storage830. Memory804is any device allowing information, such as computer executable instructions and/or other data, to be stored and retrieved. For example, memory804may include one or more random access memory (RAM) modules, flash memory modules, hard disks, solid-state disks, persistent memory devices, and/or optical disks. Program code810comprises computer executable instructions and computer executable components including instructions used to perform operations described herein. Data area820holds data used to perform operations described herein. Memory804also includes other logic and storage830that performs or facilitates other functions disclosed herein or otherwise required of computing device800. An input/output (I/O) component840facilitates receiving input from users and other devices and generating displays for users and outputs for other devices. A network interface850permits communication over a network860with a remote node870, which may represent another implementation of computing device800. For example, a remote node870may represent another of the above-noted nodes within architecture100.

Additional Examples

An example method of placing an emergency call over a wireless network comprises: establishing, between a UE and an IMS PDN/PDU, an IMS PDN/PDU session over a first wireless network: attempting, by the UE, an emergency call using an EPDN/EPDU over the first wireless network, the emergency call attempt using the EPDN/EPDU comprising: attempting to establish, between the UE and the EPDN/EPDU, an EPDN/EPDU session over the first wireless network; and based on at least a failure of the emergency call over the EPDN/EPDU, reattempting the emergency call using the IMS PDN/PDU over the first wireless network.

An example system for placing an emergency call over a wireless network comprises: a processor; and a computer-readable medium storing instructions that are operative upon execution by the processor to: establish, between a UE and an IMS PDN/PDU, an IMS PDN/PDU session over a first wireless network; attempt, by the UE, an emergency call using an EPDN/EPDU over the first wireless network, the emergency call attempt using the EPDN/EPDU comprising: attempting to establish, between the UE and the EPDN/EPDU, an EPDN/EPDU session over the first wireless network; and based on at least a failure of the emergency call over the EPDN/EPDU, reattempt the emergency call using the IMS PDN/PDU over the first wireless network.

One or more example computer storage devices has computer-executable instructions stored thereon, which, upon execution by a computer, cause the computer to perform operations comprising: establishing, between a UE and an IMS PDN/PDU, an IMS PDN/PDU session over a first wireless network: attempting, by the UE, an emergency call using an emergency PDN (EPDN/EPDU) over the first wireless network, the emergency call attempt using the EPDN/EPDU comprising: attempting to establish, between the UE and the EPDN/EPDU, an EPDN/EPDU session over the first wireless network; and based on at least a failure of the emergency call over the EPDN/EPDU, reattempting the emergency call using the IMS PDN/PDU over the first wireless network.

Another example method comprises: establishing, between a UE and an IMS PDN/PDU, an IMS PDN/PDU session over a first wireless network: transmitting, by the first wireless network, to the UE, a network policy for handling an emergency call, the network policy prioritizing the IMS PDN/PDU over domain reselection; based on at least an attempt by the UE to place the emergency call using the EPDN/EPDU, attempting to establish, between the UE and the EPDN/EPDU, an EPDN/EPDU session over the first wireless network: transmitting, to the UE, a first SIP error; and based on at least an attempt by the UE to place the emergency call using the IMS PDN/PDU, attempting to establish, between the UE and the IMS PDN/PDU, an IMS PDN/PDU session over the first wireless network.

Another example system for placing an emergency call over a wireless network comprises: a processor; and a computer-readable medium storing instructions that are operative upon execution by the processor to: establish, between a UE and an IMS PDN/PDU, an IMS PDN/PDU session over a first wireless network: transmit, by the first wireless network, to the UE, a network policy for handling an emergency call, the network policy prioritizing the IMS PDN/PDU over domain reselection; based on at least an attempt by the UE to place the emergency call using the EPDN/EPDU, attempt to establish, between the UE and the EPDN/EPDU, an EPDN/EPDU session over the first wireless network; transmit, to the UE, a first SIP error; and based on at least an attempt by the UE to place the emergency call using the IMS PDN/PDU, attempt to establish, between the UE and the IMS PDN/PDU, an IMS PDN/PDU session over the first wireless network.

One or more additional computer storage devices has computer-executable instructions stored thereon, which, upon execution by a computer, cause the computer to perform operations comprising: establishing, between a UE and an IMS PDN/PDU, an IMS PDN/PDU session over a first wireless network: transmitting, by the first wireless network, to the UE, a network policy for handling an emergency call, the network policy prioritizing the IMS PDN/PDU over domain reselection; based on at least an attempt by the UE to place the emergency call using the EPDN/EPDU, attempting to establish, between the UE and the EPDN/EPDU, an EPDN/EPDU session over the first wireless network; transmitting, to the UE, a first SIP error; and based on at least an attempt by the UE to place the emergency call using the IMS PDN/PDU, attempting to establish, between the UE and the IMS PDN/PDU, an IMS PDN/PDU session over the first wireless network.

Alternatively, or in addition to the other examples described herein, examples include any combination of the following:receiving, by the UE, from the first wireless network, a network policy for handling the emergency call, the network policy prioritizing the IMS PDN/PDU over domain reselection;based on at least a failure of the emergency call over the IMS PDN/PDU, performing domain reselection;reattempting the emergency call using a second wireless network;based on at least a successful attempt at placing the emergency call, connecting to the emergency call;the emergency call attempt using the EPDN/EPDU further comprises transmitting, by the UE, to the EPDN/EPDU, an SOS Invite;the emergency call attempt using the IMS PDN/PDU comprises transmitting, by the UE, to the IMS PDN/PDU, an SOS Invite;the UE is in roaming coverage when connected to the first wireless network;transmitting, by the first wireless network, to the UE, the network policy;the UE registering with the first wireless network;determining a location of the UE;the network policy specifies that the emergency call is to be attempted over the EPDN/EPDU first and the IMS PDN/PDU second;the network policy further specifies that domain reselection is to be performed after the emergency call fails with the IMS PDN/PDU;the network policy is based on at least the location of the UE;the network policy is based on at least the UE being attached to the first wireless network;the user initiates an emergency call;the emergency call comprises a 911 call or a 112 call;based on at least an attempt by the UE to place the emergency call using the IMS PDN/PDU, attempting to establish, between the UE and the EPDN/EPDU, an EPDN/EPDU session over the first wireless network;transmitting, to the UE, a first SIP error;determining whether the emergency call attempt using the EPDN/EPDU has failed;determining whether the emergency call attempt using the EPDN/EPDU has failed comprises receiving a first SIP error;the first SIP error comprises an error code starting with 4, 5, or 6;determining whether the emergency call attempt using the EPDN/EPDU has failed comprises detecting a timeout condition;transmitting, to the UE, a second SIP error;determining whether the emergency call attempt using the IMS PDN/PDU has failed;determining whether the emergency call attempt using the IMS PDN/PDU has failed comprises receiving a second SIP error;the second SIP error comprises an error code starting with 4, 5, or 6;determining whether the emergency call attempt using the IMS PDN/PDU has failed comprises detecting a timeout condition; andbased on at least a successful attempt at placing the emergency call using the IMS PDN/PDU, hosting the emergency call.

The order of execution or performance of the operations in examples of the disclosure illustrated and described herein is not essential, unless otherwise specified. That is, the operations may be performed in any order, unless otherwise specified, and examples of the disclosure may include additional or fewer operations than those disclosed herein. For example, it is contemplated that executing or performing a particular operation before, contemporaneously with, or after another operation is within the scope of aspects of the disclosure. It will be understood that the benefits and advantages described above may relate to one embodiment or may relate to several embodiments. When introducing elements of aspects of the disclosure or the examples thereof, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. The term “exemplary” is intended to mean “an example of.”