Abstract:
The invention relates to a method of optimizing measurement duration in a telecommunications network, said telecommunications network comprising a first base station connected to a first radio network, at least a second base station connected to a second radio network, a core network connected to said first and second radio network, a database coupled to said core network, said method comprising: sending a first beacon period information belonging to said first base station from said first base station to said database; sending at least a second beacon period information belonging to said second base station from said second base station to said database; storing at least said first and second beacon period information on said database; sending a request of said second beacon period information from said first base station to said database; generating a response of said second beacon period information belonging to said second base station from said database to said first base station; forwarding said response of said first base station to said mobile terminal; adjusting measurement periods on the mobile terminal based on said response of said beacon period information.

Description:
[0001]    The invention is based on a priority application EP 07 291 193.6 which is hereby incorporated by reference. 
       TECHNICAL FIELD 
       [0002]    The invention relates to a method of optimizing measurement duration in a telecommunications network, to a mobile terminal, to a base station and to a database. 
       BACKGROUND OF THE INVENTION 
       [0003]    In telecommunication networks such as GSM/UMTS and WiMax the beacon signals are used for supervisory, control, synchronization or reference purposes. For example, when a mobile device requires a connection with a candidate base station or radio access technology, the beacon signal of the candidate is measured to obtain all required information regarding connection establishment and synchronization. While the mobile terminal is communicating with a base station, the mobile terminal or the base station defines measurement periods for trying to intercept the beacon signals and synchronize with the candidate base station. On a parallel action, the candidate base stations send the beacon signals on specific periods of time and duration. 
         [0004]    If the period used by the mobile terminal to initiate the measurements is not aligned with the beacon periods that the candidate base station sends to, it may take several beacon periods until the measurement period fits to the beacon period and the required measurements can be performed by the mobile terminal. As a consequence, a complete measurement execution can take up to some seconds. In the case of an abrupt signal degradation of the active radio link, such a long measurement time could for example hamper seamless or lossless intersystem handover. 
         [0005]    Therefore a method of optimizing the mobile terminal measurement time, an improved mobile terminal, an improved base station, and database is described in the following that is adapted for performing the method in accordance with the invention. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention provides a method of optimizing measurement duration in a telecommunications network, the telecommunications network comprising a first base station connected to a first radio network, at least a second base station connected to a second radio network, a core network connected to the first and second radio network, a database coupled to the core network, the method comprising: sending a first beacon period information belonging to the first base station from the first base station to the database; sending at least a second beacon period information belonging to the second base station from the second base station to the database; storing at least the first and second beacon period information on the database; sending a request of the second beacon period information from the first base station to the database; generating a response of the second beacon period information belonging to the second base station from the database to the first base station; forwarding the response of the first base station to the mobile terminal; adjusting measurement periods on the mobile terminal based on the response of the beacon period information. 
         [0007]    The method has the advantage that when the mobile terminal receives the beacon period information, it will know the time when the next beacon will be sent by the second base station. In that manner, the mobile terminal is able to adjust its measurement periods so that they can start at the same time as the second base station sends the beacon signals. As a consequence, the mobile terminal requires a minimum amount of time to complete the measurements of the second base station in order to for example share the load of a service with the second base station or initiate a handover to the second base station with a better signal strength. 
         [0008]    In accordance with an embodiment of the invention, the request of the second beacon period information is originated on the mobile terminal. 
         [0009]    One of the advantages of the invention is that in the case of dual-radio mobile terminals, which can measure the beacons of the second base station with a second radio interface independently of communication with the first radio interface, the beacon period information will be primarily requested by the mobile terminal itself. Alternatively, in the case of single-radio mobile terminals, the measurement of the beacons of the second base station must be executed with the same radio interface, which is being used for communication with the first base station, the beacon period information will be primarily requested by the first base station and this information is used in the following by the first base station to schedule measurement periods as for example in compressed mode for the mobile terminal. 
         [0010]    In accordance with an embodiment of the invention, the request of the second beacon period information is originated from a measurement trigger in the base station. 
         [0011]    In accordance with an embodiment of the invention, the request of the second beacon period information is originated from a measurement trigger in the mobile terminal. 
         [0012]    In accordance with an embodiment of the invention, the first base station, the second base station and the database are connected to at least a satellite/ground based timing module for generating a time reference and wherein the method further comprises: synchronizing in time the first base station, the second base station and the database to the time reference using the satellite/ground based timing module; generating a scheduled measurement period for the mobile terminal by the first base station using the time reference and the second beacon period information; sending the scheduled measurement period for the mobile terminal to the mobile terminal from the first base station. 
         [0013]    An advantage of the invention is that it does not require the base stations to be synchronized actively, i.e. their current beacon time is only measured in reference to the time reference and not changed for synchronization. Another advantage of the invention is that when connecting the base stations and the database to a timing module that generates a common time reference, it allows a direct sharing of the beacon period information and storing of the information into the database, without the need for regular system time reports and for absolute time or offset time calculations. When requested by the mobile terminal or the base station, the base station that is communicating with the mobile terminal can make a request to the database to obtain this beacon period information and use it directly for generating the scheduled measurement period to the mobile terminal or for simply forwarding or tunneling this beacon period information to the mobile terminal. 
         [0014]    In accordance with an embodiment of the invention, the database further comprises a first predefined transmission delay from a first base station to the database and a second predefined transmission delay from a second base station to the database. The database is connected to satellite ground based timing module for generating a time reference. The method further comprises: reporting at regular intervals a first base station system time to the database from the first base station; reporting at regular intervals a second base station system time to the database from the second base station. The method further comprises: converting the first and the second base station system time to the first and second absolute time; using the time reference and the predefined transmission delay by the database; generating a schedule measurement period for the mobile terminal by the first base station at regular intervals; and sending the schedule measurement period for the mobile terminal to the mobile terminal from the first base station. 
         [0015]    The method has the advantage that it is still possible to accomplish the optimization of the beacon measurement procedure to the second base station, without adding the timing module apparatus to the base stations. When the database is connected to a timing module, the first base station and the second base station regularly send intervals of information with the system time to the database so that the database can convert the data using the predefined transmission delay to the time reference provided by the timing module. 
         [0016]    In accordance with an embodiment of the invention, the first base station, the second base station, the mobile terminal and the database are coupled to at least a satellite or ground based timing module for generating a time reference. The method further comprises synchronizing in time the first base station, the second base station, the database and the mobile terminal to the time reference using the satellite or ground based timing module. 
         [0017]    This embodiment of the invention has the advantage that all the elements of the telecommunications network will have the same time reference, allowing to share all the beacon period information from the base stations without, for example, further time offset time or absolute time calculation. The mobile terminals are able to receive the beacon period information and use it as input for adjusting the measurement periods. 
         [0018]    In accordance with an embodiment of the invention, the first and the second radio networks use different radio technologies. The method has the advantage that the first and the second base stations do not necessarily need to be in the same radio network, but that they can belong to different radio access technologies. This allows flexibility in sharing the beacon period information also between different technologies as they will be connected to the same core network. 
         [0019]    In accordance with another embodiment of the invention the first and second radio networks are identical. This method has the advantage that both base stations may be connected to the same radio network, using the same radio access technology and sharing all the beacon period information. This information is used to make the response when the mobile terminal requires the beacon periods information for adjusting the measurement period and improving the measurement times. 
         [0020]    In another aspect, the invention relates to a mobile terminal that comprises means for requesting a second beacon period information belonging to at least a second base station from a first base station; means for receiving a response with the second beacon period information belonging to at least the second base station from the first base station; and means for adjusting measurement periods on the mobile terminal based on the second beacon period information. 
         [0021]    In accordance with an embodiment of the invention, the mobile terminal comprises further means for receiving schedule measurement periods for adjusting measurement period being generated by the first base station. 
         [0022]    In another aspect, the invention relates to a base station that comprises means for sending a first beacon period information belonging to a first base station to a database, means for forwarding the request of the second beacon period information to the database, and means for forwarding a response of the beacon period information belonging to the second base station from the database to the mobile terminal. 
         [0023]    In accordance with an embodiment of the invention, the base station further comprises: means for receiving a request from a mobile terminal of a second beacon period information belonging to a second base station; means for reporting at regular intervals a first base station system time to the database, means for generating a schedule measurement period for the mobile terminal using a second absolute time and the second beacon period information, and means for sending the schedule measurement period to the mobile terminal. 
         [0024]    In another aspect, the invention relates to a database that comprises means for receiving a first beacon period information belonging to a first base station from at least a first base station; means for storing the first beacon period information from at least the first base station; means for receiving at least a second beacon period information belonging to a second base station from the second base station; means for storing the second beacon period information from at least the second base station; means for receiving a request of at least the second beacon period information from the first base station; means for generating a response of at least the second beacon period information if requested by the first base station; and means for sending the response of at least the second beacon period information to the first base station. 
         [0025]    In accordance with an embodiment of the invention, the database is coupled to satellite or ground based timing module for generating a time reference, and connected to a core network. The database further comprises a first predefined transmission delay from a first base station to the database, and a second predefined transmission delay from the second base station to the database, the database further comprises means for receiving reports at regular intervals from a first base station system time, means for receiving reports at regular intervals from a second base station system time, means for converting the first and second base station system time to a first and second absolute time, using the time reference and the first and second transmission delays. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]    In the following preferred embodiments of the invention are described in greater detail by way of example only making reference to the drawings in which: 
           [0027]      FIG. 1  is a schematic of the prior art, 
           [0028]      FIG. 2  is a schematic of a synchronization method in accordance with an embodiment of the invention, 
           [0029]      FIG. 3  is a block diagram of a synchronization method in accordance with a first preferred embodiment of the invention, 
           [0030]      FIG. 4  is a block diagram of a further preferred embodiment of a synchronization method of the invention, 
           [0031]      FIG. 5  is a sequence of operation of a further preferred embodiment of the invention, 
           [0032]      FIG. 6  is a block diagram of a further preferred embodiment of a synchronization method of the invention, 
           [0033]      FIG. 7  is a sequence of operation of a further preferred embodiment of a synchronization method of the invention, 
           [0034]      FIG. 8  is a block diagram of a further preferred embodiment of a synchronization method of the invention, 
           [0035]      FIG. 9  is a block diagram of a further preferred embodiment of a synchronization method of the invention, 
           [0036]      FIG. 10  is a sequence of operation of a further preferred embodiment of a synchronization method of the invention, 
           [0037]      FIG. 11  is a sequence of operation of a further preferred embodiment of a synchronization method of the invention, 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0038]      FIG. 1  shows a prior art representation of the beacons  101  using a beacon period  102  that are sent by a base station, and the time  103  available on a mobile terminal for measuring beacons  101 . These two processes are executed in the telecommunication network in parallel and may be the result of a measurement trigger  104  and until the beacon period or the beacon time does not coincide with the time available for measurements in the mobile terminal, the mobile terminal will not be able to finish the measurement procedure  105 . As  FIG. 1  shows, the mobile terminal may require up to six measurement periods in order to obtain the same time as when the beacon is sent by the base station. 
         [0039]      FIG. 2  shows in the upper part a diagram of the beacons  101  sent by a base station at regular intervals  102 . When a mobile terminal requires to measure the beacon periods of a neighbor base station that may be a result of a measurement trigger  104 , the mobile terminal will send a request to the current base station where it is communicating with, in order to receive the beacon period information of at least a neighbor station or this information is automatically received by neighborhood information provisioning. Once this beacon period information is received, the mobile terminal will adjust this period of the measurements or alternatively the base station will schedule adequate measurement periods in a compressed mode manner. In this case, the time available for measurements  201  has been corrected so that it correlates with the time when the neighbor base station sends the beacons  101 . The duration of the measurement procedure  202  with adjusted measurement periods is much shorter than the duration  105  shown in  FIG. 1 . 
         [0040]      FIG. 3  shows a block diagram of a telecommunication network  300  that includes a mobile terminal  301 , a first radio access network  302 , a second radio access network  303  and a core network  304 . The mobile terminal comprises measurement periods  305  and a third computer program product  306 . The first radio access network  302  includes a first base station  307  that further comprises a first computer program product  308  and a first beacon period information  309 . The second radio access network  303  further comprises: a second base station  310  that further comprises a second computer program product  311  and a second beacon period information  312 . The core network  304  comprises a database  313  and a fourth computer program product  314 . 
         [0041]    The mobile terminal  301  establishes a communication using a first radio access network  302  and the first base station  307  as the access point to the network. Mobile terminal  301  completes regular measurements to neighbor base stations using measurement periods  305 . The core network is connected to both first and second radio access networks  302  and  303 . The first and the second base station  307 ,  310  send regular beacons to potential mobile terminals and all the related data to the beacon period information  309  and  312  to the database  313  in the core network  304 . The database  313  stores at least this first beacon period information  309  and second beacon period information  312  and makes it available if requested by the mobile terminal  301  or the first and second base station  307 ,  310 . 
         [0042]    One of the advantages of the invention is that by allowing an adjustment of the measurements done by the mobile terminal, it optimizes the time that it requires to complete these measurements, and an abrupt signal degradation is avoided by quickly initiating a transmission with a second base station and second radio access network, or by facilitating inter or intra-system handover. It may occur for example that the beacon period sent by the base station and the periods between the time available for measurements in the mobile terminal are very similar, so that it could take up to some seconds in order for the mobile terminal to receive and start the measurement of the beacon periods. 
         [0043]      FIG. 4  shows a block diagram of the telecommunications network that includes a mobile terminal  301 , a first and a second radio access network  302 ,  303  and a core network  304 . The elements in the embodiment shown in  FIG. 4  that correspond to elements of the embodiment of  FIG. 3  have been designated by the same reference signals. The first base station  307  further comprises a timing module  401 , the second base station  310  further comprises a timing module  402  and the core network  304  further comprises a timing module  403 . The timing modules  401 ,  402 , and  403  are used for generating common time reference between all the elements of the telecommunication network. These timing modules  401 ,  402 , and  403  are based on any satellite or ground based system as for example the global positioning system, GPS. 
         [0044]    This method has the advantage that when sending the first and second beacon period information  309  and  312 , the core network shares the same time reference that the first and second base station uses to generate the beacon period information, so that it can store it and interpreting into the system. When the mobile terminal receives the second beacon period information  312 , it will use this information to adjust the measurement period  305  without any need of time conversion or calculation. 
         [0045]      FIG. 5  shows a sequence of operation diagram. The sequence of operation diagram depicts the steps performed and the messages exchanged between the first base station, the second base station and the database. An initialisation or reconfiguration trigger  501  may start the sequence of operation in the base station. Then, the first base station sends the first beacon period information to the database  502 . An initialisation or reconfiguration trigger  504  may start the sequence of operation in the second base station and a second beacon period information belonging to the second base station will be sent to the database  505 . The database will then store the first and second beacon period information and make it available if requested by the mobile terminal or the base stations  503 ,  506 . 
         [0046]      FIG. 6  shows a block diagram of the telecommunication network that includes a mobile terminal  301 , a first and second radio access network  302 ,  303  and a core network  304 . The elements in the embodiment shown in  FIG. 6  that correspond to elements of the embodiment of  FIG. 3  and  FIG. 4  have been designated by the same reference signals. The first base station  307  further comprises a first system time  601 . The second base station  310  further comprises a second system time  602 . The database  313  further comprises a first and a second absolute time  605  and  606 . When the first and the second base station are connected to the core network  304 , the first and the second base station will send at regular intervals the first and second system time  601 ,  602  to the database  313 . 
         [0047]    When the database  313  receives this first and second system time  601 ,  602  it will use a first and second transmission delay  603  and  604  and the timing module  403  in order to calculate a first and second absolute time  605  and  606 . This first and second transmission delay  603 ,  604  are predefined in the database. The transmission delays may be for example manually introduced into the database, or may be measured by a measurement device in the core network. The first and the second system time  601 ,  602  may be sent to the core network  304  with a high priority so that the transmission delays of the first and second absolute times are accurate. 
         [0048]    One of the advantages is that most of the components of the telecommunication network do not require a timing module in order to improve the measurement time of the mobile terminal. This allows using first and second base station without an absolute time reference and just sending regular updates of the internal system time in order to make the calculations that later will be used by the mobile terminal. 
         [0049]      FIG. 7  shows a sequence of operation diagram. The sequence of operation diagram depicts the steps that are performed and the messages that are obtained between the first and second base station  307 ,  310  and the database  313 . After a periodic trigger  701 , the first base station reports the system time to the database  702 . The database then converts the system time to a first absolute time using the time reference generated by the timing module  703 . In the next step  704 , the absolute time is stored in the database. Later or in parallel, the second base station reports after a periodic trigger  705  the second system time to the database  706 . The database then converts the second base station system time in order to obtain the second absolute time  707 . In the next step  708 , the absolute time is stored in the database. 
         [0050]      FIG. 8  shows a block diagram of the telecommunications network that comprises a mobile terminal  301 , a first and second radio access network  302 ,  303  and a core network  304 . The elements in the embodiment shown in  FIG. 6  that correspond to elements of the embodiment of  FIG. 3  and  FIG. 4  have been designated by the same reference signals. The first base station  307  further comprises the generation of the schedule measurement period  801  that is transmitted to the mobile terminal in order to adjust the measurement periods  305 . The first and second beacon period information  802  and  803  have been previously stored in the database  313 . The timing modules  401 ,  402 ,  403  are used for generating a time reference that allows a system time comparison between all these three elements, database  313  and first and second base station  307  and  310 . 
         [0051]    The first base station  307  may request the second beacon information  803  from the database  313 . After its reception, the first base station  307  can generate a schedule measurement period  801  for the mobile terminal using the time reference generated by the timing module  401  and the second beacon period information  803  received from the database  313 . This schedule measurement period  801  is then sent to the mobile terminal  301  that uses this information in order to adjust the measurement periods  305 . The scheduled measurement periods  801  can for example be sent on regular intervals so that the mobile terminal  301  can in real time adjust the measurement periods according to the first base station. 
         [0052]    Alternatively, the first base station  302  may send an extended schedule of the measurement periods and sending times, so that the mobile terminal  301  adjusts the required measurement periods and measurement times for a longer interval. In this case, the base station  302  may require using the transmission delay between the first base station and the mobile terminal so that it can correctly interpret the values sent by the first base station. This transmission delay may be measured and sent by the mobile terminal  301 .  FIG. 8  represents a mixed type of network elements where some components have a timing module and some of the components do not have any timing module. 
         [0053]    The invention has the advantage that the mobile terminal does not require to have a timing module to synchronize the internal system time with the time of the rest of the components of the telecommunication network. This allows further adaptability of the type of mobile terminals that may use the optimization method of the measurement duration. 
         [0054]      FIG. 9  shows a block diagram of the telecommunications network that comprises a mobile terminal  301 , a first and second radio access network  302 ,  303  and a core network  304 . The elements in the embodiment shown in  FIG. 9  that correspond to elements of the embodiment of  FIG. 3 ,  FIG. 4  and  FIG. 8  have been designated by the same reference signals. The mobile terminal  301  further comprises a timing module  901 . The first and second beacon period information  802  and  803  have been previously stored in the database  313 . The timing modules  901 ,  502 ,  503 ,  504  are used for generating a time reference that allows a system time comparison between all these four elements, mobile terminal  301 , first and second base station  307  and  310 , and database  313 . In a further possibility, the mobile terminal may have a timing module and the first and second base stations do not have any timing module. 
         [0055]      FIG. 10  shows a sequence of operation diagram. The sequence of operation diagram depicts the steps that are performed and the messages that are obtained between the mobile terminal  301 , the first and second base station  307 ,  310  and the database  313 . After a measurement trigger  1001  generated at the first base station  307 , the first base station  307  sends a second beacon period information request to the database  313  in step  1002 . Then, the database responds with the second beacon period information  1003 . In the next step  1004 , a scheduled measurement period is generated by the first base station  307 , which includes all the information regarding the beacon period information that is transmitted by the database. The scheduled measurement period is then sent to the mobile terminal  1005 , which uses this information in order to adjust the measurement periods  1006 . 
         [0056]      FIG. 11  shows a sequence of operation diagram. The sequence of operation diagram depicts the steps that are performed and the messages that are obtained between the mobile terminal  301 , the first and second base station  307 ,  310  and the database  313 . After a measurement trigger  1101  generated at the mobile terminal  301 , the mobile terminal  301  initiates a request  1101  of the second beacon period information that is sent to the first base station  307 . When the first base station  307  receives the request from the mobile terminal  301 , it forwards the request to the database in step  1103 . The database  313  generates a response  1104  with the second beacon period information and sends the data to the first base station  307 , which will forward this information to the mobile terminal  301  in step  1105 . When this second beacon period information  311  has been received by the mobile terminal  301 , it adjusts the measurement periods  305  in step  1106  so that it corresponds to the beacon period transmission of the second base station  310 , allowing a rapid initiation of the measurements. 
       LIST OF REFERENCE NUMERALS 
       [0057]      
         [0000]    
       
         
               
               
             
           
               
                   
               
             
             
               
                 100 
                 Time Diagram 
               
               
                 101 
                 Time diagram from beacon periods 
               
               
                 102 
                 Beacon period 
               
               
                 103 
                 Time available for measurements 
               
               
                 104 
                 Measurement trigger 
               
               
                 105 
                 Duration of measurement procedure 
               
               
                 200 
                 Adjusted time diagram 
               
               
                 201 
                 Adjusted measurement period 
               
               
                 202 
                 Duration of adjusted measurement procedure 
               
               
                 300 
                 Block diagram 
               
               
                 301 
                 Mobile terminal 
               
               
                 302 
                 First radio access network 
               
               
                 303 
                 Second radio access network 
               
               
                 304 
                 Core network 
               
               
                 305 
                 Measurement periods 
               
               
                 306 
                 Third CPP 
               
               
                 307 
                 First base station 
               
               
                 308 
                 First CPP 
               
               
                 309 
                 First beacon period information 
               
               
                 310 
                 Second base station 
               
               
                 311 
                 Second CPP 
               
               
                 312 
                 Second beacon period information 
               
               
                 313 
                 Database 
               
               
                 314 
                 Fourth CPP 
               
               
                 400 
                 Block diagram 
               
               
                 401 
                 Timing module 
               
               
                 402 
                 Timing module 
               
               
                 403 
                 Timing module 
               
               
                 500 
                 Time diagram 
               
               
                 600 
                 Block diagram 
               
               
                 601 
                 First system time 
               
               
                 602 
                 Second system time 
               
               
                 603 
                 First transmission delay 
               
               
                 604 
                 Second transmission delay 
               
               
                 605 
                 First absolute time 
               
               
                 606 
                 Second absolute time 
               
               
                 700 
                 Time diagram 
               
               
                 800 
                 Block diagram 
               
               
                 801 
                 Scheduled measurement periods 
               
               
                 802 
                 First beacon period information 
               
               
                 803 
                 Second beacon period information 
               
               
                 900 
                 Block diagram 
               
               
                 901 
                 Timing module 
               
               
                 1000 
                 Time diagram 
               
               
                 1100 
                 Time diagram