WO2018133755A1

WO2018133755A1 - Session processing method and device

Info

Publication number: WO2018133755A1
Application number: PCT/CN2018/072574
Authority: WO
Inventors: 刘新蕊; 征学银
Original assignee: 中兴通讯股份有限公司
Priority date: 2017-01-22
Filing date: 2018-01-15
Publication date: 2018-07-26
Also published as: CN108347699A

Abstract

The invention discloses a session processing method comprising: a multicell/multicast coordination entity (MCE) acquiring session attribute information of a first session, wherein the session attribute information comprises session identifier and serving cell information, and the first session is a session being activated; and upon receiving a request for a second session, if the MCE determines according the session attribute information that the second session satisfies the following conditions, rejecting the request for the second session, wherein the conditions include: the second session and the first session comprise at least one identical session identifier, or the second session and the first session comprise serving cell information partially identical to each other. The invention further discloses a session processing device.

Description

Session processing method and device

Technical field

The present invention relates to the field of communications, and in particular to a multimedia broadcast multicast conference

Word processing method and device.

Background technique

The Enhanced Multimedia Broadcast Multicast Service (E-MBMS) is a broadcast technology in LTE that simultaneously transmits high-speed multimedia data services to all users or a certain group of users in the network.

When the Core Network (CN) initiates a Multimedia Broadcast Multicast Service (MBMS) session, the coverage area of the coverage area is identified by the MBMS Service Area. In some cases, the MBMS user service may provide different service content in different areas of the network, and the user equipment (User Equipment, UE) does not know the service data in each area when receiving the E-MBMS service data. What is the relationship. In order to prevent the same UE from receiving multiple copies of data provided by the same MBMS user service at the same time, there should be a constraint that for one MBMS user service, only one piece of data can be provided to the user in any particular area at the same time.

In some cases, in order to achieve the above constraints, constraints such as a suitable service area are configured for the MBMS in a Broadcast Multicast Service Center (BM-SC), and this constraint is enforced by the wireless base station. For example, when the wireless base station receives the session start request, if the session has the same Temporary Mobile Group Identity (TMGI) as a currently active session, and the service areas of the two sessions overlap. , the session establishment request is rejected.

However, the constraint of the broadcast multicast service in some cases requires the Evolved Node B (eNodeB) base station to participate in the implementation of the session constraint, and cannot timely detect the violation of the constraint in the session initiation process, thus causing excessive Unnecessary signaling interaction.

Summary of the invention

The present invention provides a method and apparatus for session processing to at least solve the problem that in some cases, a broadcast multicast service cannot find a violation of a constraint in a session initiation process in time, causing excessive unnecessary signaling interaction.

According to an aspect of the present invention, a method for session processing is provided, including: a Multi-cell/Multicast-Coordination Entity (MCE) acquires session attribute information of a currently activated first session, The session attribute information includes a session identifier and a service area information; and when the request for the second session is received, if the MCE determines that the second session satisfies the first condition according to the session attribute information, rejecting the The request for the second session, wherein the first condition comprises: the second session has at least one same session identifier as the first session, and the service area information of the second session is related to the first session The service area information is at least partially the same.

According to an aspect of the present invention, a session processing apparatus is provided, including: an obtaining module, configured to acquire session attribute information of a currently activated first session, wherein the session attribute information includes a session identifier and a service area information. And the first determining module, when receiving the request of the second session, the first determining module determines, according to the session attribute information, whether the second session satisfies the first condition, and if the first condition is met, Rejecting the request of the second session, wherein the first condition comprises: the second session has at least one same session identifier as the first session, and the service area information of the second session is related to the first session The service area information for a session is at least partially identical.

DRAWINGS

The drawings described herein are provided to provide a further understanding of the invention and constitute a part of this application. The illustrative embodiments of the present invention and the description thereof are intended to explain the present invention, but are not intended to limit the invention. In the drawing:

1 is a logical block diagram of an E-MBMS system according to the related art;

2 is a block diagram showing a hardware structure for implementing a session processing method according to an embodiment of the present invention;

3 is a flowchart of a session processing method according to an embodiment of the present invention;

4 is a schematic diagram of an example scenario in accordance with an embodiment of the present invention;

5 is a flowchart of an example of establishing a multimedia broadcast multicast session based on the example scenario of FIG. 4, in accordance with an embodiment of the present invention;

6 is a schematic diagram of another example scenario in accordance with an embodiment of the present invention;

7 is a flowchart of an example of establishing a multimedia broadcast multicast session based on the example scenario of FIG. 6 in accordance with an embodiment of the present invention;

FIG. 8 is a structural block diagram of a session processing apparatus according to an embodiment of the present invention.

detailed description

The invention will be described in detail below with reference to the drawings in conjunction with the embodiments. It should be noted that the embodiments in the present application and the features in the embodiments may be combined with each other without conflict.

It is to be understood that the terms "first", "second" and the like in the specification and claims of the present invention are used to distinguish similar objects, and are not necessarily used to describe a particular order or order. It is to be understood that the data so used is interchangeable, where appropriate, so that the embodiments of the invention described herein can be implemented in a sequence other than those illustrated or described herein. In addition, the terms "comprises" and "comprises" and "the" and "the" are intended to cover a non-exclusive inclusion, for example, a process, method, system, product, or device that comprises a series of steps or units is not necessarily limited to Those steps or units may include other steps or units not explicitly listed or inherent to such processes, methods, products or devices.

1 is a logical framework diagram of an E-MBMS system according to the related art, wherein the MCE is a logical entity introduced by the E-MBMS access network for implementing multi-cell coordinated transmission, and is responsible for coordinated management of the multicast cell. MCE can be either part of a functional entity or a separate entity. The control plane interface between the MCE and the base station eNodeB is an M2 interface, and the interaction signaling between the MCE and the base station eNodeB is carried on the M2 interface. The control plane interface between the Mobile Management Entity (MME) and the MCE is an M3 interface, and the interaction signaling between the MME and the MCE is carried on the M3 interface. The control plane interface between the MBMS gateway and the base station eNodeB is an M1 interface, and the interaction signaling between the MBMS gateway and the base station eNodeB is carried on the M1 interface.

As described above, in order to prevent the same UE from simultaneously receiving multiple copies of data provided by the same MBMS user service, the base station eNodeB participates in implementing constraints such as a suitable service area configured for the MBMS.

The inventor of the present invention has found that, due to the signaling interaction in the E-MBMS network, the MCE can learn the session attribute information of each E-MBMS through the M3 interface during the establishment of the E-MBMS session, and manage the M2 interfaces. The E-MBMS session flow, and thus the ability to collect all the information needed by the base station to implement E-MBMS session constraints, is capable of achieving the above constraints. In addition, excessive unnecessary signaling interaction between the MCE and the base station eNodeB can be avoided.

In accordance with an embodiment of the present invention, an embodiment of a method of multimedia broadcast multicast session processing is provided. It should be noted that the steps illustrated in the flowchart of the figures may be performed in a computer system such as a set of computer executable instructions, and although an exemplary logical sequence is illustrated in the flowchart, in some In this case, the steps shown or described may be performed in a different order than the ones described herein.

The method embodiments provided by the embodiments of the present application may be implemented in a mobile terminal, a computer terminal, or the like. Taking a computer terminal as an example, FIG. 2 is a hardware block diagram of a computer terminal for implementing a session processing method according to an embodiment of the present invention.

As shown in FIG. 2, computer terminal 10 may include one or more (only one shown) processor 102, memory 104 for storing data, and transmission device 106 for communication functions. Processor 102 may include, but is not limited to, a processing device such as a microprocessor or programmable logic device. It will be understood by those of ordinary skill in the art that the structure shown in FIG. 2 is merely illustrative and does not limit the structure of the apparatus for implementing the embodiments of the present application. For example, computer terminal 10 may also include more or fewer components than those shown in FIG. 2, or have a different configuration than that shown in FIG. 2.

The memory 104 can be used to store software programs and modules of application software, such as program instructions/modules corresponding to the processing methods of page content in embodiments of the present invention. The processor 102 executes a corresponding functional application and data processing by executing a software program and a module stored in the memory 104, for example, implementing a processing method corresponding to the above-described application. Memory 104 may include high speed random access memory and may also include non-volatile memory such as one or more magnetic storage devices, flash memory, or other non-volatile solid state memory. In some examples, memory 104 may further include memory remotely located relative to processor 102, which may be coupled to computer terminal 10 via a network. Examples of such networks include, but are not limited to, the Internet, intranets, local area networks, mobile communication networks, and combinations thereof.

Transmission device 106 is for receiving or transmitting data via a network. The network specific examples described above may include a wireless network provided by a communication provider of the computer terminal 10. In one example, transmission device 106 includes a network adapter that can be coupled to other network devices through a base station to communicate with the Internet. In one example, transmission device 106 can be a radio frequency module for communicating with the Internet wirelessly.

FIG. 3 is a flowchart of a session processing method according to an embodiment of the present invention.

As shown in FIG. 3, the session processing method according to an embodiment of the present invention may include steps S302 and S304.

At step S302, the MCE acquires session attribute information of the currently activated first session, where the session attribute information includes session identifier and service area information.

At step S304, when the request for the second session is received, if the MCE determines that the second session satisfies the first condition according to the session attribute information, the request for the second session is rejected. According to an embodiment of the present invention, the first condition may include that the second session has at least one same session identifier as the first session, and the service area information of the second session is at least partially identical to the service area information of the first session.

In one embodiment, the first session may include a session that has been successfully initiated to the base station.

In an embodiment, the method may further include: if the MCE determines that the second session satisfies the second condition according to the session attribute information, rejecting sending the second session request to the base station. According to an embodiment of the present invention, the second condition may include: the second session has at least one same session identifier as the session successfully initiated to the base station, and the service area of the second session has a service area of the session successfully initiated to the base station At least partially the same.

In an embodiment, the second condition may further include that the service area of the second session at least partially overlaps with the service area of the session that has been successfully initiated to the base station.

In an embodiment, the first may further include: the second session has at least one of the same service area information as the first session.

In order to make the technical solutions and implementation methods of the present invention clearer, different embodiments in various scenarios and implementations thereof will be described in detail below with reference to the accompanying drawings.

4 is a schematic diagram of an example scenario in accordance with an embodiment of the present invention, and FIG. 5 is a flowchart of an example of establishing a multimedia broadcast multicast session based on the example scenario of FIG. 4, in accordance with an embodiment of the present invention.

Referring to FIG. 4, in the present embodiment, three MBMS service areas are planned, and MBMS cell 1 is in MBMS service area 1, MBMS cell 2 is in MBMS service area 2, and MBMS cell 3 is in MBMS service area 3.

Referring to FIG. 5, based on the example scenario of FIG. 4, an example flow of a multimedia broadcast multicast session according to an embodiment of the present invention may include steps S501 to S505.

At step S501, a connection is successfully established between the MCE and the CN and the base stations eNodeB1 and eNodeB2. The base station eNodeB1 and eNodeB2 can notify the MCE of their respective service area information through the "M2Setup Request" message.

At step S502: the CN initiates an MBMS session bearer setup procedure. For example, the service area information included in the MBMS session start request sent by the CN to the MCE may include the MBMS service area 1 and the MBMS service area 2. On the premise that the radio resources of the multicast cell are sufficient, the MCE may send an MBMS session start response to the CN in response to the successful establishment of the MBMS session bearer.

At step S503, the MCE confirms that the service area of the MBMS session initiated by the CN is consistent with the service area to which the MBMS cell 1 belongs (ie, both are MBMS service areas 1), and therefore initiates an MBMS session bearer to the base station eNodeB1 to which the MBMS cell 1 belongs. The establishment process, that is, sending an MBMS session start request to the base station eNodeB1, and notifying the allocated radio resource information to the MBMS cell 1 through the MBMS scheduling indication procedure. The base station eNodeB1 may send an MBMS session start response to the MCE as a response.

At step S504, the MCE confirms that the service area of the MBMS session initiated by the CN is consistent with the service area to which the MBM cell 2 belongs (ie, both are MBMS service areas 2), and therefore initiates an MBMS session bearer to the base station eNodeB2 to which the MBMS cell 2 belongs. The establishment process, that is, sending an MBMS session start request to the base station eNodeB2, and notifying the MBMS cell 2 of the allocated radio resource information by the MBMS scheduling indication procedure. The base station eNodeB2 may send an MBMS Session Start Response to the MCE as a response.

In the foregoing successful establishment of the session, the MCE can save session attribute information of all successfully initiated sessions. Specifically, the MCE may save session attribute information of a session successfully initiated by each of the base stations eNodeB1 and eNodeB2 managed by the MCE.

At step S505: the CN may initiate the MBMS session bearer setup procedure again. For example, the Temporary Mobile Group Identity (TMGI) of the MBMS session initiated this time has at least one identical TMGI with the TMGI of the MBMS session initiated in step S502, and the service area information included in the MBMS session start request. The MBMS service area 1 and the MBMS service area 3 may be included. In this case, according to the session processing method of the embodiment of the present invention, the MCE can determine that the MBMS session satisfies the session constraint condition 1 (ie, the first condition). That is, by performing a query in the session attribute information that has been successfully initiated, it can be determined that there is a certain session (for example, the MBMS session established in step S502) and the session established by the request has at least one identical TMGI and the session is The service area information is at least partially identical to the service area information of the session established by the request (for example, both include MBMS service area 1). In this case, the MCE may reject the MBMS session start request and send an MBMS session start request failure to the CN as a response.

In this example, since the MBMS session requested to be initiated in step S505 has at least one identical TMGI with the MBMS session that has been successfully initiated in step S502, and its service area information and the service area of the MBMS session that has been successfully initiated in step S502 The information is at least partially identical (in this example, the at least partially identical service area information is MBMS service area 1), thereby satisfying session constraint 1, and thus the MBMS session start request initiated in step S505 is rejected.

6 is a schematic diagram of another example scenario in accordance with an embodiment of the present invention, and FIG. 7 is a flowchart of an example of establishing a multimedia broadcast multicast session based on the example scenario of FIG. 6 in accordance with an embodiment of the present invention.

Referring to FIG. 6, in the present embodiment, two MBMS service areas are planned, wherein the coverage area of the MBMS service area 1 is included in the coverage area of the MBMS service area 2, and the MBMS cell 1 is in the MBMS service area 1 (thus In MBMS Service Area 2), MBMS Cell 2 is only in MBMS Service Area 2.

Referring to FIG. 7, based on the example scenario of FIG. 6, an example flow of a multimedia broadcast multicast session according to an embodiment of the present invention may include steps S701 to S707.

Step S701 is substantially the same as step S501 shown in FIG.

At step S702: the CN initiates an MBMS session bearer setup procedure. For example, the service area information included in the MBMS session start request sent by the CN to the MCE may include only the MBMS service area 1 and not the MBMS service area 2. On the premise that the radio resources of the multicast cell are sufficient, the MCE may send an MBMS session start response to the CN in response to the successful establishment of the MBMS session bearer.

Step S703 is substantially the same as step S503 shown in FIG. Since the service area of the MBMS cell 2 is inconsistent with the service area of the MBMS session initiated by the CN, the MCE does not initiate an MBMS session bearer establishment procedure to the base station eNodeB2 to which the MBMS cell 2 belongs.

In this example, the MCE can save session attribute information that has been successfully initiated in the base station eNodeB1.

At step S704: the CN may initiate the MBMS session bearer setup procedure again. For example, the TMGI of the MBMS session initiated this time has at least one identical TMGI with the TMGI of the MBMS session initiated in step S702, and the service area information of the MBMS session start request may include only the MBMS service area 2. In this case, according to the session processing method of the embodiment of the present invention, the MCE may determine that the MBMS session initiated this time does not satisfy the constraint condition 1 (ie, the first condition). This is because the same service area information does not exist between the MBMS session initiated this time and the session that has been successfully initiated in the foregoing step S702. The service area information of the MBMS session initiated this time is only the MBMS service area 2. The service area information of the MBMS session that has been successfully initiated in step S702 is only the MBMS service area 1, which is different, and thus does not satisfy the session constraint condition 1. Then, the session admission judgment is performed, that is, in the case that the radio resource of the multicast cell is sufficient, and all or part of the multicast cell can transmit the MBMS session, the MCE may send an MBMS session start response to the CN, in response to the successful establishment of the MBMS session bearer. .

At step S705: according to the session processing method of the embodiment of the present invention, the MCE decides whether to transmit an MBMS session start request to the base station eNodeB1 according to the session constraint condition 2 (ie, the second condition). According to an embodiment of the present invention, the MCE queries in a list of session attribute information of a session that has been successfully initiated to a certain base station, if there is a session with the request to establish a session having at least one identical TMGI and the service areas are at least partially identical, The session start request is not sent to the base station. In this example, based on the query for the base station eNodeB1, the MBMS session has been successfully initiated to the base station eNodeB1 in step S703, the MBMS session having at least one identical TMGI with the session initiated by the CN in step S704. Since the session constraint condition 1 is not established, the MCE can judge the MBMS service area 1 (the service area information of the MBMS session established in step S702) and the MBMS service area 2 (the service area information of the MBMS session established in step S704). Both service areas cover the geographical area where the MBMS cell 1 is located, that is, the MBMS cell 1 is in the coverage area of both the MBMS service area 1 and the MBMS service area 2. That is, although the service area information of the two sessions is different (one is the MBMS service area 1 and the other is the MBMS service area 2), the service areas of the two sessions are at least partially identical (in the service area of the two sessions) In the case where at least the part of the MBMS cell 1 is overlapped, the session constraint 2 is satisfied, and the MCE does not issue an MBMS session start request to the base station eNodeB1 to which the MBMS cell 1 belongs.

At step S706: the MCE performs the same determination process as the step S705 for the base station eNodeB2 to determine whether the base station eNodeB2 satisfies the session constraint condition 2. In this case, since the MBMS session has not been successfully initiated to the base station eNodeB2, the session constraint 2 is not established.

Step S707 is substantially the same as step S504 shown in FIG.

It should be noted that the steps illustrated in the flowchart of the drawings may be performed in a computer system such as a set of computer executable instructions, and although an exemplary logical sequence is illustrated in the flowchart, in some cases The steps shown or described may be performed in an order different from that herein.

Through the description of the above embodiments, those skilled in the art can clearly understand that the method according to the above embodiments can be implemented by means of a combination of software and a necessary general hardware platform; of course, the method can also be implemented by hardware. But in many cases the former is a better implementation. Based on such understanding, portions of the technical solution of the present invention, or portions contributing to the prior art, may be embodied in the form of a software product that can be stored in a storage medium (eg, ROM/RAM, magnetic). A disc, an optical disc, and a number of instructions for causing a terminal device (which may be a cell phone, a computer, a server, or a network device, etc.) to perform the methods in various embodiments of the present invention.

Furthermore, embodiments of the present invention also provide a session processing apparatus, and FIG. 8 is a block diagram showing the structure of a session processing apparatus according to an embodiment of the present invention.

As shown in FIG. 8, the session processing apparatus according to the embodiment of the present invention may include a fetch module 800 and a first judging module 802. The obtaining module 800 is configured to obtain session attribute information of the first session that is currently activated. The session attribute information includes a session identifier and service area information. When receiving the request of the second session, the first determining module 802 determines, according to the session attribute information, whether the second session satisfies the first condition, and if the first condition is met, rejects the request of the second session. The first condition may include that the second session has at least one same session identifier as the first session, and the service area information of the second session is at least partially identical to the service area information of the first session.

The device is used to implement the above embodiments and preferred embodiments, and the embodiments that have been described are not described again. As used below, the term "module" may implement a combination of software and/or hardware of a predetermined function. Although the apparatus described in the following embodiments is preferably implemented in software, hardware, or a combination of software and hardware, is also possible and contemplated.

In summary, according to the foregoing embodiment of the present invention, when a plurality of broadcast multicast sessions belonging to the same MBMS user service are initiated, the MCE is used to detect the conflict, and the violation of the constraint in the session initiation process can be found more timely. The decision of the constraint is limited to a small number of network elements, which can narrow the scope involved in the judgment of the constraint and avoid unnecessary signaling interaction.

Embodiments of the present invention also provide a storage medium. In one embodiment, the storage medium may be used to store program code for implementing the multimedia broadcast multicast session processing method provided by the above embodiments when executed.

In one embodiment, the storage medium may be located in any one of the computer terminal groups in the computer network or in any one of the mobile terminal groups.

In one embodiment, the storage medium is configured to store program code for performing the first and second steps below.

At the first step, the MCE obtains session attribute information of the currently activated first session, wherein the session attribute information includes session identifier and service area information.

At the second step, when the request for the second session is received, if the MCE determines that the second session satisfies the first condition according to the session attribute information, rejecting the request for the second session, where The first condition includes: the second session has at least one same session identifier as the first session, and the service area information of the second session is at least partially identical to the service area information of the first session.

In the above-mentioned embodiments of the present invention, the descriptions of the various embodiments are different, and the parts that are not detailed in a certain embodiment can be referred to the related descriptions of other embodiments.

In the several embodiments provided by the present application, it should be understood that the disclosed technical content may be implemented in other ways. The device embodiments described above are merely illustrative. For example, the division of the unit is only an exemplary logical function division. In actual implementation, there may be another division manner. For example, multiple units or components may be used. Combinations may be integrated into another system, or some features may be omitted or not implemented. Furthermore, the mutual coupling or communication connection shown or discussed may be an indirect or direct coupling or an indirect or direct communication connection through some interface, unit or module, which may be electrical or otherwise. .

The units shown as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or may be distributed to multiple networks. On the unit. Some or all of the units may be selected according to actual needs to achieve the objectives of the embodiments.

In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above integrated unit can be implemented in the form of hardware or in the form of a software functional unit.

The integrated unit, if implemented in the form of a software functional unit and sold or used as a standalone product, may be stored in a computer readable storage medium. Based on such understanding, a part of the technical solution of the present invention or a part contributing to the prior art or all or part of the technical solution may be embodied in the form of a software product stored in a storage medium. And includes a number of instructions for causing a computer device (which may be a personal computer, server, or network device, etc.) to perform all or part of the steps of the methods described in various embodiments of the present invention. The foregoing storage medium includes: a U disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a removable hard disk, a magnetic disk, or an optical disk, and the like, which can store program codes.

The above is only a preferred embodiment of the invention and is not intended to limit the scope of the invention. It will be apparent to those skilled in the art that various modifications and changes can be made in the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and scope of the present invention are intended to be included within the scope of the present invention.

Claims

A session processing method, including:

The multi-cell/multicast coordination entity MCE acquires session attribute information of the currently activated first session, where the session attribute information includes session identifier and service area information;

When the request for the second session is received, if the MCE determines that the second session satisfies the first condition according to the session attribute information, rejecting the request of the second session, where the first condition includes:

The second session has at least one same session identifier as the first session, and the service area information of the second session is at least partially identical to the service area information of the first session.
The method of claim 1 wherein the first session comprises a session that has been successfully initiated to a base station.
The method of claim 2, wherein the method further comprises:

If the MCE determines that the second session meets the second condition according to the session attribute information, rejecting sending the second session request to the base station, where the second condition includes:

The second session has at least one same session identifier as the session successfully initiated to the base station, and the service area of the second session is at least partially identical to the service area of the session successfully initiated to the base station.
The method of claim 3 wherein said second condition further comprises:

The service area of the second session at least partially overlaps with the service area of the session that has been successfully initiated to the base station.
The method of claim 1 wherein said first condition further comprises:

The second session has at least one of the same service area information as the first session.
A session processing device includes:

An obtaining module, configured to acquire session attribute information of a currently activated first session, where the session attribute information includes a session identifier and service area information;

The first determining module, when receiving the request of the second session, the first determining module determines, according to the session attribute information, whether the second session meets the first condition, and if the first condition is met, rejects the a request for a second session, wherein the first condition comprises:

The second session has at least one same session identifier as the first session, and the service area information of the second session is at least partially identical to the service area information of the first session.
The apparatus of claim 6, wherein the first session comprises a session that has been successfully initiated to a base station.
The apparatus of claim 7 further comprising:

a second determining module, configured to determine, according to the session attribute information, whether the second session meets a second condition, and if the second condition is met, refuse to send the second session request to the base station, where the The second condition includes:

The second session has at least one same session identifier as the session successfully initiated to the base station, and the service area of the second session is at least partially identical to the service area of the session successfully initiated to the base station.
The apparatus of claim 8 wherein said second condition further comprises:

The service area of the second session at least partially overlaps with the service area of the session that has been successfully initiated to the base station.
The apparatus of claim 6 wherein said first condition further comprises:

The second session has at least one of the same service area information as the first session.