WO2014163540A1

WO2014163540A1 - Message server and communication terminal

Info

Publication number: WO2014163540A1
Application number: PCT/SE2013/050359
Authority: WO
Inventors: Takeshi Matsumura; Toshikane Oda; Shinta Sugimoto; Shingo Murakami
Original assignee: Telefonaktiebolaget L M Ericsson (Publ)
Priority date: 2013-04-02
Filing date: 2013-04-02
Publication date: 2014-10-09

Abstract

A server (110) for controlling delivery of a message via a communication network (150) from a message provider (130) to a communication terminal (120) is provided. The terminal presents the message if a location of the communication terminal determined by a positioning unit (307) comprised in the communication terminal is included in a destination area (210) of the message. The server includes an obtaining unit (406) configured to obtain a delivery requirement for the message; and a control unit (409, 410) configured to request the communication terminal to perform a positioning operation so as to meet the delivery requirement. The delivery requirement includes an accuracy requirement for acceptable geographical error between the destination area and an actual location of the communication terminal that presents the message. Accuracy of the positioning unit is changed so as to meet the accuracy requirement in accordance with the request from the control unit.

Description

MESSAGE SERVER AND COMMUNICATION TERMINAL

TECHNICAL FIELD

[0001] The present invention relates to a message server and a communication terminal.

BACKGROUND

[0002] Geo-messaging is a technology to deliver a message to clients in a designated geographical area. The Geo-messaging enables infrastructure to vehicle communication as well as vehicle to vehicle

communication over cellular networks. A type of requirement for message delivery over the Geo-messaging technology is latency, which is a time length from when a message provider requests delivery of a message to when a client presents the message. For instance, if a message is about a traffic accident or an approaching emergency vehicle, the message must be delivered with a short latency.

[0003] To deliver a Geo-message to clients in a destination area, the clients inside the destination area must be identified. In case a client is a

smartphone, the current location of the client can be obtained from the GPS sensor, a cellular network' s cell identities, or Wi-Fi triangulation. GPS provides the most accurate positioning in general. An issue of using GPS sensors is the high battery consumption. One way of saving the battery is to reduce the frequency of obtaining locations from a GPS sensor. Another way is to combine the other positioning methods. However, these approaches degrade the positioning accuracy.

There is a trade-off between positioning accuracy and the battery consumption, and thus it is important to take a good balance between them. Another issue of using GPS sensors is the long delay before obtaining the first fix. To shorten the time the Assisted GPS (A- GPS) is commonly used.

[ 0004 ] WO2012/091785 proposes a device that has an active mode and a hibernate mode, and in the hibernate mode the sensors including the GPS and also the network interface device are turned off to reduce the battery consumption. The device can transit between the two modes based on its location, for example measured by using inaccurate locator while the device is in the hibernate mode and thus the GPS is off.

US2012/0177010A1 and WO2012/064860 propose solutions that use the coarse location measured by using the cellular network and activate the GPS locator when it enters or leaves a geographical area. US2012/ 0078501A1 proposes a navigation system that disseminates the navigation maps with different granularity according to predicted accuracy of positioning in a certain

geographical area. SUMMARY

[0005] The existing solutions described above do not focus on the fact that the required positioning accuracy can vary depending on the type of messages to be delivered. Thus, the solutions cannot efficiently reduce power consumption at a client in a messaging system. It is desirable to propose an efficient technique to reduce power consumption at a client in a messaging system.

[0006] According to an aspect of the invention, a server for controlling delivery of a message via a communication network from a message provider to a communication terminal is provided. The terminal presents the message if a location of the communication terminal determined by positioning means comprised in the communication terminal is included in a destination area of the message. The server includes obtaining means configured to obtain a delivery requirement for the message; and control means configured to request the communication terminal to perform a positioning operation so as to meet the delivery requirement. The delivery requirement includes an accuracy requirement for acceptable geographical error between the

destination area and an actual location of the

communication terminal that presents the message.

Accuracy of the positioning means is changed so as to meet the accuracy requirement in accordance with the request from the control means. According to another aspect of the invention, a communication terminal is provided. The terminal includes positioning means configured to determine a location of the communication terminal and that can change accuracy of the

determination; communication means configured to receive a message; presentation means configured to present the message if a location of the communication terminal determined by the positioning means is

included in a destination area of the message; and control means configured to change an operation of the positioning means if it is required by a server to meet a delivery requirement for the message. The delivery requirement includes an accuracy requirement for acceptable geographical error between the destination area and an actual location of the communication terminal that presents the message. The control means is configured to change the accuracy of the positioning means so as to meet the accuracy requirement in

accordance with the request from the server.

[0007] Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings .

BRIEF DESCRIPTION OF DRAWINGS

[0008] Fig. 1 illustrates a configuration of a messaging system according to some embodiments.

[0009] Fig. 2 illustrates three types of geographical areas used by the messaging system according to some embodiments .

[0010] Fig. 3 illustrates an exemplary block diagram of the communication terminal according to some

embodiments .

[0011] Fig. 4 illustrates an exemplary block diagram of the geo-message server according to some embodiments.

[0012] Fig. 5 illustrates detailed operations in the messaging system in Phase 1 according to some

embodiments .

[0013] Fig. 6 illustrates detailed operations in the messaging system in Phase 2 according to some

embodiments.

[0014] Fig. 7 illustrates detailed operations in the messaging system in Phase 3 according to some

embodiments .

[0015] Fig. 8 illustrates detailed operations in the messaging system while the communication terminal operates so as to meet the delivery requirement

according to some embodiments.

[0016] Fig. 9 illustrates an example way to determine a standby area and a buffer area according to some embodiments.

DETAILED DESCRIPTION [0017] Embodiments of the present invention will now be described with reference to the attached drawings. Each embodiment described below will be helpful in understanding a variety of concepts from the generic to the more specific. It should be noted that the

technical scope of the present invention is defined by claims, and is not limited by each embodiment described below. In addition, not all combinations of the

features described in the embodiments are always indispensable for the present invention.

[0018] Fig. 1 illustrates a configuration of a

messaging system 100 according to some embodiments. The messaging system 100 may comprise a geo-message server 110, one or more communication terminals 120, a message provider 130, and a policy management server 140. The components in the messaging system 100 may be connected with each other via a mobile network 150 such as 3G network, LTE network, or any other mobile networks which can transmit data between components.

[0019] The message provider 130 creates a message and requests the geo-message server 110 to deliver the message to each communication terminal 120 in a

destination area of the message. The message provider 130 may be a personal computer, a mobile terminal, or any other devices which can provide a message. If it is determined that a communication terminal 120 is located in the destination area, the communication terminal 120 presents the message. Otherwise, the communication terminal 120 does not present the message. The message to be delivered may be any types of messages such as advertisements, announcements, warnings, etc. The message may be presented at a communication terminal 120 which is located in the destination area at a certain time point (for example, just 10 o'clock or a time point at which the message provider 130 requests the geo-message server 110 to start delivery of a message) , or at any time point during a certain time period (for example, from 10 o'clock to 14 o'clock, or from when the message provider 130 requests the geo- message server 110 to start delivery of a message to when requests to terminate delivery of the message) . In the latter case, the message may be presented once or predetermined times during the certain time period, for example when it is determined for the first time that the communication terminal 120 is located in the destination area, or may be presented iteratively while the communication terminal 120 is located in the destination area.

[ 0020 ] The message provider 130 may provide a delivery requirement for the message to the geo-message server 110. The delivery requirement may specify how the message should be delivered, and may include an

accuracy requirement and a temporal requirement, and other requirements such as how many times the message should be presented (for example, once or iteratively) , when the message should be presented (for example, just 10 o'clock or from 10 o'clock to 14 o'clock), what type of user should receive the message (for example, man or woman) , etc.

[0021] The accuracy requirement may specify acceptable geographical error between the destination area and an actual location of the communication terminal 120 that presents the message. For example, if the destination area is a circular area with the radius of 500 m and the acceptable geographical error is 100 m to each direction, a communication terminal 120 which is located within 400 m from the center of the destination area should present the message; a communication terminal 120 which is located between 400-600 m from the center of the destination area may or may not present the message; and a communication terminal 120 which is located at 600 m or more from the center of the destination area should not present the message.

[0022] For example, when a message is an advertisement to be delivered to people with approximately 1,000 m of the Tokyo station, the message provider 130 most likely do not care if the message is received by a user at 1,100 m from the station. On the other hand, when a message is a request to drivers near an ambulance to stop their vehicles, the message provider 130 need rather strict control of the destination area where the message is delivered.

[0023] The temporal requirement may specify a time length from when the message provider 130 requests the geo-message server 110 to start delivery of a message to when a communication terminal 120 in the destination area presents the message. The message to be delivered may be provided to the geo-message server 110 together with the request of starting the delivery, or may be stored in the geo-message server 110 before the message provider 130 makes the request.

[0024] The geo-message server 110 controls delivery of a message from the message provider 130 to the

communication terminal 120 in the destination area so that the delivery requirement for the message is met. In order to meet the delivery requirement, the geo- message server 110 can request the communication terminal 120 to change its operation. For example, the geo-message server 110 can request the communication terminal 120 to change accuracy of positioning

operation, frequency of positioning operation, etc. For example, since it takes long time before obtaining the first fix using a GPS sensor in the communication terminal 120, the geo-message server 110 may request the communication terminal 120 to activate a GPS sensor before receiving a message.

[0025] Instead of or in addition to the request to the communication terminal 120, the geo-message server 110 can request the policy management server 140 to

establish a session for delivery of the message. For example, the geo-message server 110 can request the policy management server 140 to ensure quality of service, such as the average, minimum, maximum bit rates, latency, jitter, and error rate.

[0026] The policy management server 140 manages a session in the mobile network 150. The policy

management server 140 may include a PDF (Policy

Decision Function) and one or more PEPs (Policy

Enforcement Function) as specified 3GPP TS 23.207 titled "End-to end Quality of Service (QoS) concept and architecture." The PDF accepts a request for QoS control and makes one or more PEPs to enforce the QoS.

[0027] In some embodiments, the message delivery can be performed in three phases. In Phase 1, the message provider 130 notifies the geo-message server 110 that the message provider 130 has a message to be delivered to one or more communication terminals in a destination area of the message so that a corresponding delivery requirement is met. The message provider 130 may have two or more messages each of which may have a

respective destination area and delivery requirement. The geo-message server 110 may request one or more communication terminals 120 to change their operation. Furthermore, the geo-message server 110 may request the policy management server 140 to establish a session in - li the mobile network 150 between the geo-message server 110 and the message provider 130.

[0028] In Phase 2, the message provider 130 sends a message together with its destination area to the geo- message server 110 in the established session. Then, the geo-message server 110 delivers the message to one or more communication terminals 120 in the destination area. The message provider 130 may not provide the specific destination area to the geo-message server 110. In this case, the geo-message server 110 may deliver the message to all of the communication terminals that uses the messaging service of the geo-message server 110.

[0029] In Phase 3, at the end of the message delivery time, or upon receiving a notification that there is no need to deliver a message, the geo-message server 110 requests the policy management server 140 to tear down the established session and releases the reserved resources, and notifies the communication terminals 120 that there is no need to meet the delivery requirement.

[0030] In some embodiments, phase 1 and phase 2 can be executed together, that is, the session can be

established when a message is sent from the message provider 130. Phase 3 may be triggered by a timer measuring the period where no messages were sent in the session.

[0031] Fig. 2 illustrates three types of geographical areas used by the messaging system 100 according to some embodiments, that is, a destination area 210, a standby area 220, and a buffer area 230. In Fig. 2, the standby area 220 encompasses the destination area 210, and the buffer area 230 encompasses the destination area 210 and the standby area 220. As described above, the destination area 210 is a geographical area

associated with the message. The message is presented at the communication terminal 120 such as a

communication terminal at a location 211 within the destination area 210. The destination area 210 may be changed over time.

[ 0032 ] The standby area 220 is a geographical area in which the communication terminal 120 is required to meet the delivery requirement. In other words, when a communication terminal 120 is inside the standby area 220 of a message such as the communication terminal at the locations 211 and 221, the communication terminal 120 is ready to present the message so that the

delivery requirement is met. The standby area 220 may be specified by the message provider 130 and provided to geo-message server 110. Instead, the standby area 220 may be calculated by the geo-message server 110 based on the destination area and the delivery

requirement of a message to be delivered. The standby area 220 may be equal to the destination area 210.

Instead, when the message provider 130 intends to deliver multiple messages having different destination areas, the standby area 220 may cover all of the

destination areas.

[ 0033 ] The buffer area 230 is a geographical area where the geo-message server 110 starts sending the request to the communication terminal 120 and/or the policy management server 140 so that the delivery requirement is met. In other words, when a

communication terminal 120 moves from the outside of the buffer area to the inside of the buffer area (for example, a communication terminal 120 moves from a location 241 to a location 231), the geo-message server 110 starts sending the request to the communication terminal 120 to change its positioning operation and the request to the policy management server 140 to establish a session with the communication terminal 120. Thus, a communication terminal 120 inside the buffer area 230 and outside the standby area 220 may or may not be ready to present the message so that the

delivery requirement is met.

[ 0034 ] Fig. 3 illustrates an exemplary block diagram of the communication terminal 120 according to some embodiments. The communication terminal 120 is, for example, a mobile phone, a smartphone, a laptop

computer, a car-mounted navigation system, or any other types of device that can present a message. The

communication terminal 120 may include components shown in Fig. 3. The CPU 301 controls overall operations of the communication terminal 120. The storage device 302 stores computer programs and data used for operations of the communication terminal 120, such as a message to be presented, the destination area of the message, operation parameters of each sensors in the

communication terminal 120, etc. The storage device 302 may be implemented by a ROM, a RAM, a hard disk, and any combination thereof.

[0035] The Battery 303 supplies power to each

component in the communication terminal 120. The communication unit 304 can send/ receive data to/ from the mobile network 150. The communication unit 304 may operate according to any protocols, including 3G, LTE, Wi-Fi, Bluetooth, etc. The presentation unit 305 presents a message received by the communication unit 304. The presentation unit 305 may be implemented by a speaker and/or a display.

[0036] The message client unit 306 controls a

messaging operation in the communication terminal 120. If it is determined that the communication terminal 120 is located in the received destination area, the message client unit 306 instructs the presentation unit 305 to present the received message. The positioning unit 307 determines the current location of the

communication terminal 120 by use of at least one of the GPS sensor 308, the cellular network location sensor 309, the Wi-Fi location sensor 310, and other sensors (not shown) which are useful for determining the current location such as acceleration sensor, gyro sensor, Bluetooth, NFC (Near Field Communications), DSRC (Dedicated Short Range Communication) , microphones and cameras .

[0037] The positioning unit 307 can change positioning accuracy by changing a sensor to be used of positioning and/or by changing operational frequency of a sensor. For example, according to some embodiments, if it is required to determine the current location of the communication terminal 120 with high positioning accuracy, the positioning unit 307 determines the current location using the GPS sensor 308; otherwise, the positioning unit 307 determines the current

location using the cellular network location sensor 309 or Wi-Fi location sensor 310, in order to save power consumption of the battery 303. According to other embodiments, if it is required to determine the current location of the communication terminal 120 with high positioning accuracy, the positioning unit 307

determines the current location using the GPS sensor 308 with high frequency; otherwise, the positioning unit 307 determines the current location using the GPS sensor 308 with low frequency, in order to save power consumption of the battery 303.

[0038] The positioning unit 307 can also change time required to determine the current location of the communication terminal 120 by changing a sensor to be used of positioning and/or by changing states of a sensor. For example, according to some embodiments, if it is required to determine the current location of the communication terminal 120 within a certain time length (for example, 10 seconds), the positioning unit 307 determines the current location using the GPS sensor 308 in an active state (that is, a state after

performing the first fix) ; otherwise, the positioning unit 307 determines the current location using the GPS sensor 308 in an initializing state (that is, a state required to perform the first fix) , in order to save power consumption of the battery 303.

[ 0039 ] Fig. 4 illustrates an exemplary block diagram of the geo-message server 110 according to some

embodiments. The geo-message server 110 may include components shown in Fig. 4. The CPU 401 controls overall operations of the geo-message server 110. The storage device 402 stores computer programs and data used for operations of the geo-message server 110. The storage device 402 may be implemented by a ROM, a RAM, a hard disk, and any combination thereof.

[ 0040 ] The client information DB 403 manages client information of each communication terminal 120 that uses a messaging service by the geo-message server 110. The client information of each communication terminal 120 may include an identifier of the communication terminal 120, an address to be used for delivering a message, location information provided by the

communication terminal 120, and any other information which can be used for message delivery. The identifier and the address can be obtained when the user of the communication terminal 120 applies to the messaging service .

[0041] The message information DB 404 manages message information of each message to be delivered. The message information of each message may include message content, an identifier of the message provider, a delivery requirement, a destination area, a standby area, a buffer area, a presentation time point or period, and any other information which can be used for message delivery. Some items of message information may be received from the message provider 130 or calculated by the geo-message server 110.

[0042] The location obtaining unit 405 obtains

location information indicating the current location of each communication terminal 120 and stores it in the client information DB 403. The location obtaining unit 405 may receive the location information from the communication terminal 120 or from a server such as an LCS server defined in 3GPP TS 23.271 that manages the current location of the communication terminal. The message information obtaining unit 406 obtains message information of a message from the message provider 130 and stores it in the message information DB 404.

[0043] The message delivery unit 407 delivers a

message, which is stored in the message information DB 404 or received from the message provider 130, together with its destination area to the communication

terminals 120 whose address is stored in the client information DB 403. The message delivery unit 407 may deliver a message to all of the managed communication terminals 120, to the communication terminals 120 in the buffer area 230, or to the communication terminals 120 in the standby area 220.

[0044] The request determination unit 408 determines a request to the communication terminal 120 and/or a request to the mobile network 150 (for example, the policy management server 140), based on a delivery requirement of a message. For example, if the delivery requirement includes an accuracy requirement, the request determination unit 408 determines a request to the communication terminal 120 to meet the accuracy requirement. This request may specify how to change the positioning operation in the communication terminal 120, or may specify acceptable geographical error so that the communication terminal 120 can determine how to change the positioning operation in the communication terminal 120.

[0045] If the delivery requirement includes a temporal requirement, the request determination unit 408

determines a presentation requirement for the

communication terminal 120 and a transmission

requirement for the mobile network 150 based on the temporal requirement. The transmission requirement specifies a time length within which the mobile network 150 should transmit the message to the communication terminal 120. The presentation requirement specifies a time length within which the communication terminal 120 should determine whether it is in the destination area of the message and should present the message if so.

[0046] For example, if the temporal requirement indicates that a message should be presented within 5 seconds from the delivery instruction, the request determination unit 408 determines that the mobile network 150 should transmit the message to the

communication terminal 120 within 1 seconds and that the communication terminal 120 should determine whether it is in the destination area of the message and should present the message if so within 4 seconds. According to the determined requirements for both the

communication terminal 120 and the mobile network 150, the request determination unit 408 determines requests for both the communication terminal 120 and the mobile network 150.

[0047] For example, the request determination unit 408 can determine the required positioning accuracy (A_p) and positioning frequency (F_p) of the communication terminal 120 so as to meet the following inequalities and minimize the battery consumption under the

constraints .

F_p > 1 / (T_a - T_t) ,

Ά_ρ < E_p — V_est / Fp

, where E_p and T_a are the acceptable positioning error and the acceptable delivery time length specified in the delivery requirement respectively, T_t is the acceptable transmission time length in the mobile network 150, and V_est is an estimated moving speed mentioned above of the communication terminal 120. The estimated moving speed of the communication terminal 120 may be the maximum or average moving speed of all the communication terminals 120 stored in the client information DB 403, or a fixed value based on legal speed limit around the destination area.

[0048] A communication terminal may receive a message before entering the destination area of the message. A communication terminal may not receive a message even after the destination area of the message. From the message provider perspective the former is a false positive case and the latter is a true negative case. If the false positive is acceptable but true negative is not for the delivery of a message, then the request determination unit 408 may not make any requests and the message delivery unit 407 expands the destination area of the message and delivers the expanded

destination area to the communication terminal 120. If it is opposite, then the request determination unit 408 may not make any requests and the message delivery unit 407 reduces the destination area of the message and delivers the reduced destination area to the

communication terminal 120, unless the destination area is not too small. If the size of the standby area 220 is so small that the battery consumption can be ignored, then a high positioning accuracy can be used regardless of the type of message.

[0049] The client control unit 409 sends the request determined by the request determination unit 408 to the communication terminals 120 in the buffer area 230. The network control unit 410 sends the request determined by the request determination unit 408 to the mobile network 150. The network control unit 410 may implement a PCC AF (Policy and Charging Control Application

Function) defined in 3GPP TS 23.207.

[0050] The area determination unit 411 determines a buffer area 230 of a message based on a standby area 220, an estimated moving speed of the communication terminal 120, and estimated time from when the client control unit 409 and the network control unit sends the requests to when the delivery requirement is met. The buffer area 230 is determined wide enough to prevent a communication terminal 120 out of the buffer area 230 from entering the standby area 220 before the delivery requirement is met. The equation below is an example of determining the buffer area 230, assuming that a

standby area 220 is a circle:

Rb=Rq+V_est * T_est

where the i¾ is the radius of the circle forming the buffer area 230, is the radius of the circle forming the standby area 220, V_est is the an estimated moving speed mentioned above, and T_est is the estimated time from when the client control unit 409 and the network control unit sends the requests to when the delivery requirement is met at both of the communication

terminal 120 and the mobile network 150.

[0051] If the request from the geo-message server 110 to a communication terminal 120 is to use the GPS sensor 308 for positioning, T_est may be the time

required for activating the GPS sensor 308 and getting the first fix since the time to establish a session in the mobile network 150 is usually less than the time required for the GPS activation.

[0052] The accuracy requirement described above may be specified by the message provider 130, may be derived by the geo-message server 110 according to some

criteria. If the accuracy requirement is specified by the message provider 130, the geo-message server 110 uses the specified accuracy requirement after checking if it is acceptable (i.e. performing Admission Control) . [0053] Fig. 5 illustrates detailed operations in the messaging system 100 in Phase 1 described above. In step S501, the message client unit 306 in each

communication terminal 120 in the messaging system 100 sends location information indicating the current location of the communication terminal 120 determined by the positioning unit 307 to the geo-message server 110 via the communication unit 304. At this time, the positioning unit 307 may determine the current location with any accuracy, and thus may use low accuracy to save power consumption from the battery 303. The message client unit 306 performs step S501 iteratively At this time, the message client unit 306 may send the location information with any frequency, and thus may use low frequency to save power consumption from the battery 303.

[0054] In step S502, the message provider 130 sends a standby request to the geo-message server 110. The standby request notifies that the message provider 130 has a message to be delivered. The standby request includes a standby area 220 of the message and a delivery requirement for the message. The message information obtaining unit 406 in the geo-message server 110 obtains the standby area 220 and the

delivery requirement, and stores them in the message information DB 404. At this time, the message and its destination area 210 may not be sent to the geo-message server 110. The standby request may include multiple sets of the standby area 220 and the delivery

requirement and the geo-message server 110 may choose one from the multiple sets.

[0055] In step S503, the area determination unit 411 in the geo-message server 110 determines the buffer area of the message to be delivered, based on the standby area 220 obtained at step S502, as described above. In step S504, the request determination unit 408 in the geo-message server 110 determines a request to each communication terminal 120 in the messaging system 100 and a request to the mobile network 150, based on the delivery requirement obtained at step S502, as described above. The request determination unit 408 may return a response with the time length needed before the delivery requirement is met for all of the

communication terminals 120 in the buffer area 230.

[0056] In step S505, the client control unit 409 in the geo-message server 110 sends the request determined at step S504 to one or more communication terminals 120 in the buffer area 230. Also, the network control unit 410 in the geo-message server 110 sends the request determined at step S504 to the policy management server 140 to establish a session between the message provider 130 and one or more communication terminals 120 in the buffer area 230. The location of the communication terminals 120 used in step S504 is indicated by location information stored in the client information DB 403. It is assured that the communication terminal 120 in Fig. 5 is outside the buffer area 230 at this time and thus the client control unit 409 does not send the request at this time.

[0057] In the messaging system 100, a message is delivered from the message provider 130 to a

communication terminal 120 via the geo-message server 110 since the geo-message server 110 stores an address of each communication terminal 120. Thus, two sessions are established by the policy management server 140 for one communication terminal 120; one for between the message provider 130 and the geo-message server 110 and the other for between the geo-message server 110 and the communication terminal 120. The session between the message provider 130 and the geo-message server 110 may be shared with two or more communication terminals 120 to which a message is delivered.

[0058] In step S506, the message client unit 306 in each communication terminal 120 in the messaging system 100 sends location information in the same way as in step S501. In step S507, the client control unit 409 determines whether a communication terminal 120 is newly located in the buffer area 230. For example, such a communication terminal 120 exists if a communication terminal 120 moves from the outside of the buffer area 230 to the inside of the buffer area 230, or a communication terminal 120 is powered on in the buffer area 230. It is assured that the communication terminal 120 in Fig. 5 is inside the buffer area 230 at this time .

[0059] In step S508, the client control unit 409 in the geo-message server 110 sends the request determined at step S504 to one or more communication terminals 120 which newly appears in the buffer area 230. In step S509, the positioning unit 307 in the communication terminal 120 changes its positioning operation in accordance with the request received at step S508 and so as to minimize power consumed by the positioning unit 307. In step S510, the message client unit 306 in the communication terminal 120 sends location

information indicating the current location of the communication terminal 120 determined by the

positioning unit 307 that performs the changed

operation, to the geo-message server 110 via the communication unit 304.

[0060] In step S511, in parallel with steps S508-S510, the network control unit 410 in the geo-message server 110 sends the request determined at step S504 to the policy management server 140 to establish a session between the message provider 130 and one or more communication terminals 120 which newly appears in the buffer area 230. In step S512, the policy management server 140 establishes the requested session. Since a session between the message provider 130 and the geo- message server 110 is already established, the policy management server 140 may establish a session between the geo-message server 110 and the communication terminals 120. In step S513, the policy management server 140 may return acknowledge to the geo-message server 110 to notify that the session has been

established.

[0061] Fig. 6 illustrates detailed operations in the messaging system 100 in Phase 2 described above. In step S601, the message provider 130 sends a delivery instruction to the geo-message server 110. The delivery instruction may include a message to be delivered and its destination area, or may specify a message to be delivered and its destination area that are already stored in the message information DB 404 in the geo- message server 110.

[0062] In step S602, the message delivery unit 407 in the geo-message server 110 sends the instructed message and its destination area to one or more communication terminals 120 through the established session in the mobile network 150. The instructed message may be delivered to all of the communication terminals that uses the messaging service of the geo-message server 110, or to one or more communication terminals located in a certain area including the destination area. The message client unit 306 in the communication terminal 120 receives the message and destination area.

[0063] In step S603, the message client unit 306 obtains the current location of the communication terminal 120 from the positioning unit 307 and

determines whether the communication terminal 120 is in the destination area. In step S604, if the message client unit 306 determines that the communication terminal 120 is in the destination area, the message client unit 306 presents the message using the

presentation unit 305; otherwise, the message client unit 306 does not present the message.

[0064] If it is required that the message should be presented at a communication terminal 120 which is located in the destination area at any time point during a certain time period, the communication

terminal 120 repeats steps S603 and S604 during the certain time period. Steps S601-S604 may be performed for each delivery instruction from the message provider 130. When the destination area is updated, the message delivery unit 407 sends the new destination area to the communication terminals 120.

[0065] In the embodiment shown in Fig. 6, the

communication terminal 120 determines whether the communication terminal 120 is located in the

destination area. In some other embodiments, the geo- message server 110 may determine whether the

communication terminal 120 is located in the destination area based on the location information received from the communication terminal 120 or from a server in the mobile network. In this case, if the geo- message server 110 determines that the communication terminal 120 is in the destination area, the geo- message server 110 instructs the communication terminal 120 to present the message; otherwise, the message client unit 306 does not instruct to do so.

[ 0066 ] Fig. 7 illustrates detailed operations in the messaging system 100 in Phase 3 described above. In step S701, the message provider 130 sends a release request to the geo-message server 110. The release request notifies that the delivery requirement

specified in step S502 need not be met any more. For example, the message provider 130 may send the release request if it has no more messages to be delivered.

[ 0067 ] In step S702, the client control unit 409 in the geo-message server 110 notifies the communication terminals 120 in the buffer area 220 that there is no need to operate in accordance with the request sent at step S505 or S508. In step S703, the positioning unit 307 in the communication terminal 120 changes its positioning operation so as to minimize power consumed by the positioning unit 307. In step S704, the message client unit 306 in the communication terminal 120 sends location information indicating the current location of the communication terminal 120 determined by the positioning unit 307 that performs the changed

operation, to the geo-message server 110 via the communication unit 304.

[ 0068 ] In step S705, in parallel with steps S702-S704, the network control unit 410 in the geo-message server 110 sends a request to the policy management server 140 to release the session between the message provider 130 and one or more communication terminals 120. In step S706, the policy management server 140 releases the requested session. At this time, the policy management server 140 releases both of the session between the message provider 130 and the geo-message server 110 and the session (s) between the geo-message sever 110 and the communication terminal (s) 120. In step S707, the policy management server 140 may return acknowledge to the geo-message server 110 to notify that the session has been released.

[ 0069 ] Fig. 8 illustrates detailed operations in the messaging system 100 while the communication terminal 120 operates so as to meet the delivery requirement. In step S801, the message client unit 306 in the

communication terminal 120 sends location information indicating the current location of the communication terminal 120 determined by the positioning unit 307 that performs the changed operation, to the geo-message server 110 via the communication unit 304.

[ 0070 ] In step S802, the client control unit 409 determines whether a communication terminal 120 has moved from the inside of the buffer area 230 to the outside of the buffer area 230. It is assured that the communication terminal 120 in Fig. 8 has moved to the outside of the buffer area 230.

[0071] In step S803, the client control unit 409 in the geo-message server 110 notifies the communication terminals 120 which have moved to the outside of the buffer area 230 that there is no need to operate in accordance with the request sent at step S505 or S508. In step S803, the positioning unit 307 in the

communication terminal 120 changes its positioning operation so as to minimize power consumed by the positioning unit 307. In step S805, the message client unit 306 in the communication terminal 120 sends location information indicating the current location of the communication terminal 120 determined by the positioning unit 307 that performs the changed

operation, to the geo-message server 110 via the communication unit 304.

[0072] In step S806, in parallel with steps S803-S805, the network control unit 410 in the geo-message server 110 sends a request to the policy management server 140 to release the session between the geo-message server 110 and one or more communication terminals 120 which have moved to the outside of the buffer area 230. At this time, the policy management server 140 does not release the session between the message provider 130 and the geo-message server 110 since this session can be used to deliver a message to other communication terminals 120. In step S808, the policy management server 140 may return acknowledge to the geo-message server 110 to notify that the session has been released.

[0073] According to the embodiments shown in Figs, 5-8, the message provider 130 sends the standby request before sending the delivery instruction of a message. In some other embodiments, the message provider may send the delivery instruction of a message without sending the standby request. In these embodiments, the geo-message server 110 determines the standby area 220 to deliver the instructed message and performs steps S503-S505 and step S602 in parallel.

[0074] The messaging system 100 shown in Fig. 1 may be integrated with IMS (IP Multimedia Subsystem) to

provide end to end session management and QoS control. For example, if the message provider 130 is an IMS application server, the standby request in Fig. 5 from the message provider 130 to the geo-message server 110 can be realized by using IMS INVITE message, and the release request in Fig. 5 can be realized by using IMS BYE message. The geo-message server 110 may also be an IMS application server and the policy management server 140 may be a PCRF (Policy and Charging Rules Function) function. [0075] Fig. 9 illustrates an example way to determine a standby area and a buffer area. In case the message provider 130 is comprised in a vehicle like an

ambulance and a message to be delivered is a warning to vehicles in the destination area 910, a future location of the ambulance can be estimated with some accuracy. In Fig. 9, an ambulance at a location 901 travels from right to left on the road and the destination area 910 changes accordingly. From the map-matching technique the geo-message server 110 knows which road the

ambulance is traveling, and by combining a prior knowledge that there are no hospitals to the northbound road, the area determination unit 411 in the geo- message server 110 can determine the standby area 920 based on the estimated future location of the ambulance to cover only the roads the ambulance may travel on. The area determination unit 411 can also determine the buffer area 930 based on the standby area 920 as described above, and update the buffer area 930 stored in the message information DB 404.

[0076] According to the embodiments described above, a message from a message provider is delivered to a communication terminal so that a delivery requirement for the message is met. Furthermore, battery

consumption in the communication terminal can be reduced by changing positioning operations, while the delivery requirement is met. [ 0077 ] While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such

modifications and equivalent structures and functions.

Claims

1. A server (110) for controlling delivery of a message via a communication network (150) from a message provider (130) to a communication terminal (120) that presents the message if a location of the communication terminal determined by positioning means (307) comprised in the communication terminal is included in a destination area (210) of the message, the server comprising:

obtaining means (406) configured to obtain a delivery requirement for the message; and

control means (409, 410) configured to request the communication terminal to perform a positioning operation so as to meet the delivery requirement,

wherein the delivery requirement includes an accuracy requirement for acceptable geographical error between the destination area and an actual location of the communication terminal that presents the message, and

accuracy of the positioning means is changed so as to meet the accuracy requirement in accordance with the request from the control means.

2. The server according to claim 1, wherein

the communication terminal receives the message and then determines a location of the communication terminal using the positioning means, and presents the message if the determined location is included in the destination area,

the delivery requirement includes a presentation requirement of time from when the communication

terminal receives the message to when the communication terminal presents the message, and

time required for determining the location of the communication terminal by the positioning means is changed so as to meet the presentation requirement in accordance with the request from the control means.

3. The server according to claim 1 or 2, wherein

the delivery requirement includes a transmission requirement for transmission between the message provider and the communication terminal, and

the control means is further configured to request the communication network to establish a session for transmission of the message so as to meet the transmission requirement.

4. The server according to any one of claims 1-3, further comprising receiving means (405) configured to receive location information indicating the location of the communication terminal determined using the

positioning means,

wherein the control means is configured to perform the request if the received location information indicates that the communication terminal is located in a buffer area that encompasses the destination area.

5. The server according to claim 4, wherein the control means is further configured to notify at least one of the communication terminal and the communication network that there is no need to meet the delivery requirement if the received location information indicates that the communication terminal moves from the inside of the buffer area to the outside of the buffer area.

6. The server according to claim 4 or 5, further comprising area determination means (411) configured to determine the buffer area based on an area in which the communication terminal is required to meet the delivery requirement, an estimated moving speed of the

communication terminal, and estimated time from when the control means sends the request to when the delivery requirement is met.

7. The server according to claim 6, wherein the area determination means is further configured to estimate temporal change of the destination area and update the buffer area to correspond to the changed destination area .

8. A communication terminal (120) comprising:

positioning means (307) configured to determine a location of the communication terminal and that can change accuracy of the determination;

communication means (304) configured to receive a message;

presentation means (305) configured to present the message if a location of the communication terminal determined by the positioning means is included in a destination area of the message; and

control means (306) configured to change an operation of the positioning means if it is required by a server (110) to meet a delivery requirement for the message; wherein

the delivery requirement includes an accuracy requirement for acceptable geographical error between the destination area and an actual location of the communication terminal that presents the message, and the control means is configured to change the accuracy of the positioning means so as to meet the accuracy requirement in accordance with the request from the server.

9. The communication terminal according to claim 8, wherein

the control means is further configured to determine whether a location of the communication terminal determined by the positioning means is included in the destination area, after the

communication means receives the message,

the positioning means is further configured to change time required for the location determination; the delivery requirement includes a presentation requirement of time from when the communication means receives the message to when the presentation means presents the message, and

the control means is further configured to change the time required for the location determination so as to meet the presentation requirement in accordance with the request from the server.

10. The communication terminal according to claim 8 or 9, further comprising a battery (303) for supplying power to the positioning means,

wherein the control means is further configured to change an operation of the positioning means such that the delivery requirement is met and the power consumed by the positioning means is minimized.

11. The communication terminal according to any one of claims 8-10, wherein the control means is further configured to change an operation of the positioning means such that the power consumed by the positioning means is minimized, when the communication means receives a notification indicating that there is no need to meet the delivery requirement.

12. The communication terminal according to any one of claims 8-11, wherein the communication means is further configured to send, to the server, location information indicating the location determined by the positioning means, and receives the request from the server in response to the location information.

13. The communication terminal according to any one of claims 8-12, wherein the positioning means is configured to obtain the location by use of at least one of a GPS sensor (308), a cellular network location sensor (309), a Wi-Fi location sensor (310), an acceleration sensor, and a gyro sensor.