MXPA00003855A - Channel resource utilization during a positioning handover - Google Patents

Abstract

A telecommunications system and method for efficiently managing physical channels during a positioning handover to a target Base Transceiver Station. This can be accomplished by allowing a positioning handover to occur from one channel type, e.g., a traffic channel of the serving BTS, to another channel type, e.g., a control channel of the target BTS. Advantageously, in case of congestion on one type of channel in the target cell, the other type can be used, which allows the positioning handover to the desired target BTS to be performed and the data needed to be collected.

Description

UTILIZATION OF CHANNEL RESOURCE DURING A LOCALIZATION TRANSFER BACKGROUND OF THE PRESENT INVENTION Field of the Invention The present invention relates generally to telecommunication systems and methods for determining the geographic location of a mobile terminal within a cellular network, and specifically refers to efficiently managing physical channels during a transfer of data. location to a target base transceiver station. Background v Objectives of the Present Invention Cellular telecommunications is one of the fastest growing and most demanding applications in telecommunications. Currently, it represents a large and continuously growing percentage of all new telephony subscriptions around the world. A standardization group, the European Telecommunications Standards Institute (ETSI) was established in 1982 to formulate the specifications for the Global Mobile Communication System (GSM), the mobile cellular radio system digital Now with reference to Figure 1 of the drawings, a public GSM land mobile network (PLMN) is illustrated, such as a cellular network 10, which in turn is composed of a plurality of areas 12, each with a Switching Center Mobile (MSC = Mobile Switching Center) 14, and an Integrated Visitor Location Register (VLR = Visitor Location Register) 16 there. The MSC / VLR areas 12 in turn include a plurality of location areas (LA = Location Areas) 18, which are defined as that part of a given MSC / VLR area 12, wherein a mobile station (MS) (terminal) 20, can move freely without having to send information of the updated location to the area MSC / VLR 12 that controls the LA 18. Each location area 12 is divided into a number of cells 22. The mobile station (MS) 20 is the physical equipment, for example a car telephone or other portable telephone, used by mobile subscribers to communicate with the cellular network 10, among themselves and users outside of the network of subscribers, both physical and wireless. The MSC 14 is in communication with at least one Base Station Controller (BSC = Base Station Controller) 23, which in turn is in contact with at least one Base Transceiver Station (BTS = Base Transceiver Station) 24. The BTS is the physical equipment illustrated for simplicity as a radio tower , which provides radio coverage to the geographic part of cell 22 for which it is responsible. It will be understood that the BSC 23 can be connected to several base transceiver stations 24 and can be implemented as a standalone node or integrated with the MSC 14. In any event, the components of BSC 23 and BTS 24, as a whole, refer to general as a Base Station System (BSS = Base Station System) 25. With additional reference to Figure 1, the PLMN service area or cellular network, includes a Service Area Location Record (HLR = Home Location Register) 26 , which is a database that maintains all subscriber information, for example user profiles, current location information, International Mobile Subscriber Identity (IMSI) numbers, and other administrative information. The HLR 26 can be colocalized with a particular MSC 14, integrated with the MSC 14 or alternatively it can serve multiple MSCs 14, the last of which is illustrated in Figure 1. The VLR 16 is a database containing information regarding all mobile stations 20 currently located within the MSC / VLR area 12. If an MS 20 operates outside the service area in a new MSC / VLR area 12, the VLR 16 connected to that MSC 14 will request data regarding that mobile station 20 of the HLR database 26 (simultaneously reporting to the HLR 26 regarding the current location of the MS 20). Agree with this, if the user of the MS 20 then wishes to make a call, the local VLR 16 will have the necessary identification information without having to interrogate the HLR 26. In the manner described above, the VLR and HLR databases 16 and 26 respectively they contain various subscriber information associated with a given MS 20. Determining the geographical location of an MS within a cellular network has recently become important for a wide range of applications. For example, location services can be used by transportation companies and taxis to determine the location of their vehicles. In addition, for emergency calls, for example 911 calls, the exact location of the mobile terminal can be extremely important for the outcome of the emergency situation. In addition, location services can be used to determine the location of a stolen car, for the detection of calls in the area of the service area, which are charged at a lower rate for the detection of microcell hot spots, or for the subscriber Determine for example the nearest gas station, restaurant or hospital.

Currently, as can be seen in Figure 2 of the drawings, before a request for network location, the Base Station System (BSS = Base Station System) (220 and 240) that serves the MS 200 generates location data, which are supplied to the Mobile Switching Center (MSC) 260. This location data is then sent to a Location Center (PC = Positioning Center) 270 for geographic location calculation of the MS 200. The location of the MS 200 can then be sent to the application 280 within the network that requested the location. In order to precisely determine the location of the MS 200, location data of three separate base transceiver stations (210, 220 and 230) are required. This location data for GSM systems includes a synchronization advance value (TA = Timing Advance) which corresponds to the amount of time in advance that the MS 200 must send a message in order for the BTS 220 to receive it in the slot However, it should be understood that any distance estimate can be used, instead of the TA value of the GSM systems. When a message is sent from MS 200 to BTS 220, there is a propagation delay, which depends on the distance between MS 200 and BTS 220. TA values are expressed in bit periods, and may be in the range of 0 to 63, with each bit period corresponding to approximately 550 rs between the MS 200 and the BTS 220. Once a TA value for a BTS 220 is determined, the distance between the MS 200 and that particular BTS 220 is known, but the current location is not known. If, for example, the value TA = 1, the MS 200 can be anywhere within a radius of 550 rs. Two TA values of 2 BTSs, for example BTSs 210 and 220, provide two possible points where the MS 200 can be located (where the two radii intersect). However, with three TA values of three BTSs, for example BTSs 210, 220 and 230, the location of the MS 200 can be determined with a certain degree of accuracy. Using a triangulation algorithm, with knowledge of the three TA values and site location data associated with each BTS (210, 220 and 230) the location of the mobile station 200 can be determined (with some precision) by the location center 270 Therefore, advance values in synchronization (TA) of the original BTS (service) 220 and two neighboring BTSs (target) (210 and 230) are obtained. In order for each target BTS (210 and 230) to determine a TA value, a location transfer must occur to each of the BTSs (210 and 230). A transfer of location is identical to an ordinary asynchronous transfer. The target BTS, for example BTS 210, distinguishes the transfer of location from an ordinary transfer by a new ACTIVATION TYPE in the CHANNEL ACTIVATION message. Unlike an ordinary transfer, upon receiving a TRANSFER ACCESS message from the MS 200, the target BTS 210 only calculates the TA value and does not respond to the mobile station 200, that is, PHYSICAL INFORMATION is not sent ( PHYSICAL INFORMATION) to the MS 200. In this way, the MS 200 will then return to the previous channel assigned by the original BTS 220, after the time period defined by the internal counter of the MS 200 expires, for example 320 milliseconds. The digital GMS system uses Multiple Access with Time Division (TDMA = Time Multiple Division) Access) to handle radio traffic in each cell. TDMA divides each frequency (carrier) into 8 time slots (physical channels). The logical channels are then mapped to these physical channels. Examples of logical channels include Traffic Channels (speech) (TCH = traffic channels) and Control Channels (CCH = Control Channels). In a GSM cellular network, a traffic channel occupies a physical channel, while 8 dedicated control channels occupy a physical channel.

During a location transfer, an asynchronous transfer is usually made from one traffic channel to another traffic channel, or from one control channel to another control channel. To collect the necessary data, the channel in the target BTS 230 is used for approximately 320 milliseconds. This means that the traffic capacity in the target cell is affected somewhat. Furthermore, if there is no waiting channel of the desired type in the target BTS 230, the location transfer will not occur. Therefore, location data for that target BTS 230 can not be collected.

Therefore, when making location transfers from one type of channel to the same type of channel, for example from one traffic channel to another traffic channel, channel resources are not used efficiently. It is therefore an object of the invention to allow a location transfer from one type of channel to another type of channel to occur, for example from a traffic channel of the service BTS to a control channel of the target BTS, to In order to efficiently use the physical channels of the target BTS. SUMMARY OF THE INVENTION The present invention is directed to telecommunications systems and methods for efficiently managing physical channels during a transfer of location to a target base transceiver station. This can be achieved by allowing a location transfer from one type of channel, for example, a service BTS traffic channel to another type of channel, for example a control channel of the target BTS, to occur. Advantageously, in case of congestion in one type of channel in the target cell, the other type can be used, which allows location transfer to the desired target BTS to be performed and the required data collected. A Channel of Autonomous Dedicated Control (SDCCH = Stand-alone Dedicated Control Channel) is one eighth of a physical channel, whereas a Channel of Traffic (TCH) occupies a whole physical channel. Therefore, when using SDCCH for location transfers, the physical channels in the target BTS can be used efficiently. BRIEF DESCRIPTION OF THE DRAWINGS The described inventions will be illustrated with reference to the accompanying drawings, which illustrate important sample embodiments of the invention and which are incorporated in the specification by reference, wherein: Figure 1 is a block diagram of a system wireless telecommunications of conventional terrestrial base; Figure 2 illustrates a sample location transfer where location data is acquired by a target base transceiver station and transmitted to a service base station controller; and Figures 3A and 3B are flow charts demonstrating steps in a sample channel assignment process during a location transfer to a target base transceiver station. DETAILED DESCRIPTION OF EXEMPLARY MODALITIES CURRENTLY PREFERRED The numerous innovative teachings of the present application will be described with particular reference to the currently preferred exemplary embodiment. However, it should be understood that this kind of modalities only provide a few examples of the many advantageous uses of the innovative teachings present. In general, the statements made in the specification of the present application do not necessarily delimit any of the claimed inventions. Furthermore, some statements may apply some inventive characteristics but not others. After a location transfer as illustrated in Figure 2 of the drawings, a mobile station (MS) 200 returns to the previous channel of a service BTS 220 (according to the normal process) after a period of time defined by the internal counter MSs 200. According to the GSM specifications, this time period for a traffic channel (TCH) is 320 milliseconds and for a dedicated autonomous control channel (SDCCH), it is 675 milliseconds. Therefore, using TCHs during a location transfer allows a shorter speech interruption. However, using SDCCHs during a location transfer, more efficient utilization of channel resources is provided due to the fact that a control channel is only one eighth of a physical channel, while a traffic channel occupies an entire channel physical. In addition, a preferred channel type differs depending on the state of the MS 200, for example when the mobile station 200 that is located is in a sleep mode (not in use), the preferred channel type is an SDCCH, and when the mobile station 200 is in a dedicated mode (in use) a TCH is preferred. However, in case of congestion in the target cell 250, the preferred channel type does not need to be used. On the contrary, a different type of channel can be assigned to carry out the location transfer in order to maximize the channel occupation duration as well as the efficient use of channel resources. Now with reference to Figures 3A and 3B of the drawings, they are illustrated in a sample channel assignment process during a location transfer. Initially, after a location request is received by the mobile switching center 260 (step 300) serving the location area 205 that the MS 200 is within a location center 270, which can be located within the MS 260 or can be a separate node, in communication with the MS 260, the MS 260 sends this location request to the service source base station (BSC) controller 240 (step 305). The originating BSC 240 then determines which base transceiver stations (BTSs) 210, 220 and 230 can be used to acquire a synchronization advance (TA) value (step 310) to accurately determine the location of the MS 200. First, it is obtains a TA value from the service BTS 220 (TAI) (step 315) and then TA values are obtained from the other target BTSs (210 and 230) when performing a location transfer. The transfer of location is achieved by service BSC 240, which sends a new ACTIVATION TYPE in the CHANNEL ACTIVATION message to the target BTS 230, which informs the target BTS 230 that it requires perform a location transfer (step 320). The target BTS 230 then recognizes the CHANNEL ACTIVATION message to the service BSC 250 (step 325).

Subsequently, the BSC 240 sends a command to the MS 200 via the service BTS 220 (step 335) to transmit a TRANSFER ACCESS message (HANDOVER ACCESS) to the target BTS 230 (step 340). Subsequently, as illustrated in Figure 3B of the drawings (step 342) the preferred channel type TCH or SDCCH) is determined by the BSC 240 (step 345). As previously established, the preferred channel type depends on the location case. For example, if the MS 200 is in a sleep mode, a control channel will be preferred, whereas if the MS 200 is in a dedicated mode, the preferred channel type would be a traffic channel. Subsequently, the BSC 240 determines whether the preferred channel type is available to the target BTS 230 (step 350). If so, the target BTS 230 allocates that channel type (step 355) and conducts the location transfer (step 365). However, if the channel type is not available, the BSC 240 then determines if another type of channel is available (step 360). If the second channel type is available, the target BSC 230 allocates that channel (step 355) and perform the location transfer (stage 365). However, in the event that no type of channel is available, the BSC 240 must then determine if any other BTSs (not shown) in the area that can perform a location transfer (step 370). If another BTS (not shown) exists (step 372) then the BSC 240 informs this BTS (not shown) that a location transfer will be carried out (step 320). Subsequently, the preferred channel type for this target BTS (not shown) is determined (step 345), and a determination is made as to what types of channel, if any, are available to the additional target BTS (not shown) (steps 350). -365). If no other BTS can perform the location transfer, the BSC 240 must then inform the location center 270 by the MSC 260 that the location data can not be obtained (step 375). If a channel type is available in the target cell 250, during the time that the MS 200 waits with a response from the target BTS 230, for example around 320 milliseconds for a TCH, the target BTS 230 measures the forward value synchronization (access delay) (TA3) (step 380), using access bursts that are sent by the MSC 200 and send this location data to the service BSC 240 (step 385). The TA value measured by the target BTS 230 (TA3) is then transmitted by the service BSC 250 to the MSC 260 (step 390). Finally, the acquired TA value of the target BTS 230 (TA3) together with other TA values (TAI and TA2) are sent to the location center (PC) 270 from the MSC 260 (step 392), where the location of the MS 200 using the triangulation algorithm (step 394). PC 270 then presents the geographic location of MS 200 to the requesting application (node) 280 (step 396) for further processing (step 398). As will be recognized by those skilled in the art, the innovative concepts described in the present application can be modified and varied over a wide range of applications. Accordingly, the scope of the patented matter will not be limited to any of the specific exemplary teachings discussed. For example, it should be noted that the previously described handling of location data can be implemented in any cellular system, and will not be limited to GSM systems. In other cellular systems, the Base Station Controller function can be implemented within the mobile switching center itself.

Claims (28)

1. - A telecommunications system for managing channel allocation during a location transfer of a certain one of a plurality of mobile terminals in wireless communication with a mobile switching center, the telecommunications system is characterized in that it comprises: a service base transceiver station, in communication with the mobile switching center; and a first target base transceiver station, in communication with the mobile switching center, the first target base transceiver station has a first associated channel type, the first target base transceiver station allocates one of the channels of the first channel type, when the First type of channel is available for location transfer, the first base transceiver station allocates one of the channels of a second channel type when the first type of channel is not available for location transfer.

2. - The telecommunications system according to claim 1, characterized in that the first type of channel is a traffic channel.

3. - The telecommunications system according to claim 2, characterized in that the first type of channel occupies one of a plurality of physical channels associated with the first target base transceiver station and wherein the amount of time occupied by the channel of the First type of channel during location transfer is approximately 320 milliseconds.

4. - The telecommunications system according to claim 1, characterized in that the second type of channel is a dedicated autonomous control channel.

5. The telecommunications system according to claim 4, characterized in that the second type of channel occupies one-eighth of a plurality of physical channels associated with the first target base transceiver station, and wherein the amount of time occupied by the Channel of the second type of channel is approximately 675 milliseconds.

6. The telecommunications system according to claim 1, characterized in that the first type of channel is a control channel and the second type of channel is a traffic channel.

7. The telecommunications system according to claim 1, characterized in that the first type of channel is a control channel when the determined mobile terminal is in an idle state, the first type of channel is a traffic channel when the determined mobile terminal is in a dedicated mode.

8. The telecommunications system according to claim 1, characterized in that it also comprises a location center connected to the mobile switching center, the location center sends a location request of the determined mobile terminal to the mobile switching center, the mobile switching center sends the location request to a base station controller connected to the base service transceiver station, the base service transceiver station determines first location data associated with the determined mobile terminal and sends the first location data to the center of location through the mobile switching center and the base station controller.

9. - The telecommunications system according to claim 8, characterized in that the first location data comprise a synchronization advance value.

10. The telecommunications system according to claim 8, characterized in that it also comprises a second target base transceiver station, the second base transceiver station determines the second location data associated with the determined mobile terminal and sends the second location data to the location center through the mobile switching center and the base station controller.

11. The telecommunications system according to claim 10, characterized in that the base station controller determines the first target base transceiver station and the second target base transceiver station, the first target base transceiver station determines third location data associated with the determined mobile terminal during the location transfer, the first transceiver station The target base sends the third location data to the location center through the mobile switching center and the base station controller.

12. The telecommunications system according to claim 11, characterized in that the location center calculates the location of the determined mobile terminal using first, second and third location data.

13. The telecommunications system according to claim 12, characterized in that the location center sends the location of the determined mobile terminal to a node requesting location.

14. Method for managing channel allocation during a location transfer of a certain one of a plurality of mobile terminals from a service base transceiver station to a first target base transceiver station, the determined mobile terminal is in wireless communication with a center of transmission. mobile switching, the method is characterized in that it comprises the steps of: determining a first type of channel associated with the first target base transceiver station, the first target base transceiver station and the base service transceiver station are in communication with the mobile switching center; assign, by the first target base transceiver station, one of the channels of the first type of channel to perform the location transfer when the first type of channel is available; and assigning, by the first target base transceiver station, one of the channels of a second type of channel to perform the location transfer when the first type of channel is not available.

15. - The telecommunications method according to claim 14, characterized in that the first type of channel is a traffic channel.

16. The method of telecommunications according to claim 15, characterized in that the first type of channel occupies one of a plurality of channels associated with the first target base transceiver station and wherein the amount of time occupied by the channel of the first Channel type during location transfer is approximately 320 milliseconds.

17. The telecommunications method according to claim 14, characterized in that the second type of channel is a dedicated autonomous control channel.

18. The method of telecommunications according to claim 17, characterized in that the second type of channel occupies one eighth of one of a plurality of physical channels associated with the first target base station, and wherein the amount of time occupied the channel of the second type of channel is approximately 675 milliseconds.

19. The telecommunications method according to claim 14, characterized in that the first type of channel is a control channel and the second type of channel is a traffic channel.

20. The telecommunications system according to claim 14, characterized in that the first type of channel is a control channel when the determined mobile terminal is in a sleep mode, the first type of channel is a traffic channel when the determined mobile terminal is in a dedicated mode.

21. - The telecommunication method according to claim 14, characterized in that it also comprises before the step of determining the first type of channel, the steps of: sending a location request to the mobile switching center, by a location center connected to the mobile switching center; and sending through the mobile switching center, the location request to a base station controller connected to the base service transceiver station; determining, by the service base transceiver station, first location data associated with the determined mobile terminal; and sending, by the service base receiving station, the first location data to a location center through the mobile switching center and the base station controller.

22. - The telecommunication method according to claim 21, characterized in that the step of determining the first type of channel is performed by the base station controller.

23. The telecommunications method according to claim 21, characterized in that the step of determining the first type of channel is performed by the mobile switching center.

24. - The telecommunications method according to claim 21, characterized in that the first location data comprises a synchronization advance value.

25. The telecommunications method according to claim 21, characterized in that it also comprises, after the step of sending the location request, the steps of: determining by a second target base transceiver station in communication with the mobile switching center, second location data associated with the determined mobile terminal; and sending by the second target base transceiver station, the second location data to the location center through the mobile switching center and the base station controller.

26. The telecommunications method according to claim 25, characterized in that it also comprises, before the step of determining the second location data, the step of: determining by the controller of the base station, the first target base transceiver station and the second target base transceiver station; and comprising, after the step of allocating the channel of the second type of channel, the steps of: determining, by the first target base transceiver station, third location data associated with the determined mobile terminal during the location transfer; and sending, by the first target base transceiver station, the third location data to the location center through the mobile switching center and the base station controller.

27. The telecommunications method according to claim 26, characterized in that it also comprises, after the steps of sending the first, second and third location data, the step of: calculating, by the location center, the location or location of the determined mobile terminal, using the first, second and third location data.

28. The telecommunications method according to claim 27, characterized in that it also comprises, after the calculation step, the step of: sending the location of the determined mobile terminal to a location application connected to the location center.