RU2427084C2 - Method and device for gaining and maintaining control of traffic from radio base station in cellular telephony system - Google Patents

Abstract

FIELD: information technology.

SUBSTANCE: temporary radio base station (RBS, 140) is positioned in or adjacent to the targeted RBS (120), and transmits at a frequency in the candidate list of the targeted RBS (120). The transmissions are at such a power level that the traffic of the targeted RBS (120) is transferred to the temporary RBS (140). The temporary RBS transmits the identification signal the RBS whose frequency the temporary RBS transmits at, and transmits a list of candidate frequencies such that user terminals whose traffic has been transferred to the temporary RBS cannot find signals with sufficient strength on any of the candidate frequencies.

EFFECT: preventing cellular telephones from functioning within a certain geographical area.

17 cl, 5 dwg

Description

FIELD OF THE INVENTION

The present invention relates to a method and apparatus for providing and maintaining, through a temporary radio base station, traffic control to and from a target radio base station in a wireless cellular communication system. The system under consideration provides several base stations for controlling and routing traffic to and from user terminals in the system, and each base station routes and manages traffic to and from a specific cell within the system.

State of the art

There are many situations in which it is desirable for government agencies, such as law enforcement agencies, to prevent the use of cell phones within a specific geographic area. For example, in the event of a situation of public unrest, such as riots, it may be desirable for the police or other similar government bodies to prevent cell phones from operating within a specific area of the city.

Other cases where it may also be desirable to prevent the functioning of cellular networks in a given geographical area, may be, for example, before a police raid on a building. Another example of a problem area that can be resolved by banning cellular telephony in a selected area are cell phones that are secretly carried to prisons, which is starting to become a big problem.

Traditionally, the prohibition of cellular telephone communications within the region was carried out in the same way as traditional electronic jamming. This means that traditional solutions were used, which are mainly aimed at transmitting a signal of intentional interference, usually noise, at appropriate frequencies in order to “drown” information in noise and thereby create a signal-to-noise ratio that prevents detection by user terminals in the target area of the signal with "payload".

The problem of the method described above, i.e. The so-called "frontal" interference, is that it is a method that consumes significant energy, thereby making the equipment heavy and not too portable. In addition, since noise signals are transmitted with a relatively high output power at well-known frequencies, it may be enough for experienced users to recognize that external interference has occurred in the system.

FR 2858742 describes a procedure and apparatus for interfering with cellular communication systems that solves some of the problems described above. Nevertheless, it turns out that the device requires significant processor power, since it is based on a rather complex algorithm and tries to identify certain signals on a more or less permanent basis.

SUMMARY OF THE INVENTION

Therefore, there is a need for a method and apparatus by which cellular traffic control in a specific area can be obtained without creating a need for substantial processor performance and transmitting device power. In addition, traffic management should not only be obtained, but also supported. The traffic that is required to receive and maintain its management is the traffic between user terminals in a certain area and the radio base station (RBS) or stations through which this traffic is controlled and routed.

This need is met by the present invention in that it provides a method for receiving and maintaining, through a temporary base station, traffic control to and from a target base station in a wireless cellular communication system, the system comprising a certain number of base stations for routing traffic to and from user terminals in the system.

Each radio base station in this system controls traffic to and from a specific cell within the system, and at least several radio base stations in the system transmit an identification signal and a list of frequency options for use by user terminals when switching to another base station.

The phrase “switching to another base station” means the fact that user terminals in a cellular system must have their traffic controlled and routable through a radio base station that meets certain criteria, including signal strength (power). When the signal strength from the current base station drops below a predetermined predetermined level over a predetermined predetermined time interval, a traffic handover is performed to another base station from which a cleaner signal is received by the user terminal.

According to the invention, traffic control to and from the target base station is obtained by positioning the temporary base station in the cell of the target base station or adjacent to the hundredth of the target base station and programming the temporary base station so as to transmit on one of the frequencies in the list of options transmitted in the broadcast mode through the target base station.

Preferably, but not necessarily, the frequency at which the temporary RBS is programmed to transmit is the frequency used by RBS, which is not directly adjacent to the hundredth target RBS.

Thus, the temporary base station is configured to transmit at a frequency that is monitored by the user terminals of the area in question, and at a power level that provides handover of the user terminal (s) to the temporary base station from the target base station. In addition, the temporary base station is configured to transmit, as its identification signal, a signal that is the same as the identification signal of the base station at the frequency of which the temporary base station transmits. Therefore, traffic control of the target base station is obtained through a temporary base station.

In order to provide the possibility of a temporary base station not only receiving but also supporting traffic control of the target base station, the temporary base station is programmed to transmit a list of frequency options, but the list is such that user terminals cannot find signals with sufficient efficiency in any of the frequency options nearby with a control interception area. Accordingly, traffic control that is transmitted to the temporary base station must also be supported by it.

In a preferred embodiment of the invention, the list of frequency options is empty, which means that frequency options cannot be found by the radio base stations that have been received since the user terminals are not actually looking for frequency options.

The method of the invention can be applied to a certain number of cellular telephone communication systems, among which may be mentioned TDMA systems, for example a GSM system, or CDMA systems.

If the invention is applied to a GSM system, the identification signal to be used is the so-called CGI signal or BSIC signal (BSIC is the identification code of the base station), and the list of frequency options is the so-called BA list (BA - allocation BCCH, where BCCH means broadcast control channel).

Also, unlike the prior art, advanced algorithms or more processor power are not required in order to achieve the objectives of the invention. In addition, the temporary base station according to the invention makes it possible to achieve the desired goals in a much more energy-efficient manner, which makes it possible to construct a smaller and more compact device than previously, which can be supposedly powered by batteries. Also, unlike traditional sources of intentional interference, which used the “frontal” approach, the device according to the invention does not cause such a significant disturbing noise in the system.

Brief Description of the Drawings

The invention is described in more detail below with reference to the accompanying drawings, in which

Figure 1 illustrates a portion of a cellular system in which the invention may be applied.

Figure 2 illustrates a flowchart showing the main steps of the method according to the invention.

FIGS. 3 and 4 illustrate alternative steps for a flowchart of the method of FIG. 2.

5 illustrates a system in which it is applied.

DETAILED DESCRIPTION OF THE INVENTION

The invention is described in more detail below, and the application is carried out according to some examples of a cellular system in order to illustrate the inventive concept. The examples mainly show the invention applicable to a common GSM system, in other words, to a system that is based on the principle of TDMA, time division multiple access. Nevertheless, it should be noted how specialists in this field of technology should be aware that the invention can equally well be applied to cellular systems that are based on other principles, such as, for example, CDMA, code division multiple access.

Before describing the invented concept, a brief description of some functions in a cellular telephone system should be performed.

Figure 1 illustrates a general diagram of a wireless cellular system 100, or at least part of such a system. As indicated in FIG. 1, the system contains a plurality of separate and neighboring geographical areas, the so-called “cells”, roughly shown by a cell designated 110. Within each cell, there is usually one radio base station (RBS) 120 that controls all traffic in and from user terminals 130 in the cell, and by which all traffic from user terminals 130 in the cell 120 is routed. The user terminals in the system constantly monitor the quality of the received signal from the RBS, which routes and controls their traffic, in order to determine when their traffic should instead be controlled and routed through another RBS, in other words, should the so-called “handover” of another RBS be performed .

Signal quality, as well as certain other predefined parameters, are used in determining whether a handover should be performed. The decision to complete the handover can be made either through the user terminal 130, or through the so-called base station controller (BSC) at the system level. Typically, a decision is made by a management function or control in a user terminal if the user terminal is not participating in an active session, i.e. when the terminal is in the so-called "idle mode", and by the BSC, if the user terminal is in the so-called "active mode", i.e. There is a running voice or data signal. In the second case, i.e. during active mode, the user terminal reports important data to the BSC, which then determines whether or not the handover should be performed.

Each cell in system 100 has a globally unique identifier within the system, in some systems, such as GSM, referred to as the CGI global identifier for a cell, which typically consists of 15-18 bytes. Since the CGI contains such a sufficiently large number of bits, a shorter identifier is often used by the radio base station in the cell, the shorter identifier being referred to as BSIC, the identification code of the base station.

The BSIC or CGI are broadcasted at regular intervals by the base station 120 in the cell 110, so that the cell and its base station can be identified by the user terminals 130. The BSIC and / or CGI are broadcasted by the base stations on a special channel, usually through a special logical channel. Also in this broadcast, a so-called BA list is usually included, which is a list of frequencies used by the radio base stations next to the broadcast radio base station.

With reference to FIG. 1 and cell 110, the BA list is thereby used by user terminals 130 in cell 110 to know which other frequencies should be monitored for signal quality and possibly used in handover.

In the “passive mode” case, the handover is approximately as follows: the user terminal 130 in cell 110 listens for a broadcast message from the radio base station in cell 110 and must monitor the frequencies in the BA list to check if they provide better signal quality than the radio base station in cell 110. If the answer is yes and certain criteria are met, such as, for example, the duration of the signal quality, the user terminal 130 switches its traffic to the base iostantsiyu with best quality and then begins to track the BA-list of the radio base station.

With reference to FIG. 1, as well as to a flowchart of FIG. 2, an example of a method according to the invention is shown. Imagine an area in which it is desirable that cellular telephone communication could not be carried out, for example, the well-known shelter of criminals, in which the police decided to make a sudden raid. It will be very valuable for the police if cell calls cannot be made to or from places near the building before and during the raid. The management of all cellular telephone communications in this area is carried out by means of a conventional RBS in the system, and this RBS is thereby the “target” for intercepting traffic control.

Briefly, and in more detail later in this text, the method according to the invention uses additional RBS, from now on referred to as RBS, in order to obtain traffic control of the target RBS.

In order to optimally use the invention, it is necessary to determine which frequencies are in the list of options, i.e. in the BA list of the GSM system of the target base station. This information can be obtained in a variety of ways, for example, from the operator or operators of cellular systems in this area or through measurements performed in the area in which it is desirable to obtain and maintain traffic control.

In addition, it is necessary to obtain the identification code of the station, at the frequency of which the temporary base station must transmit. This information can also be obtained through field measurements or from a system operator.

It is also applicable to find out what signal level the user terminals have in the area under consideration, since it is desirable to transmit at the output power level for temporary RBS, which will make user terminals try to switch their traffic to temporary RBS, but as an alternative, this can be done by simple transmission with the output the level with which, as is known a priori, the target RBS cannot be compared.

When the information described above is received, it is used in temporary RBS as follows:

- Temporary RBS is positioned in the cell of the target RBS or adjacent to said cell, see step 210 of FIG. 2.

- The temporary RBS is configured to transmit on one or more frequencies in the list of variants of the target RBS, said frequency being used by the RBS, which is appropriately not directly adjacent to the hundredth of the target RBS, see step 220 in FIG. 2.

- Transmissions at the mentioned control frequency are performed with such a power level that the user terminals within a certain area receive a signal from a temporary RBS as a better signal than the target RBS, and, accordingly, sought to switch their traffic to a temporary RBS, see step 230 on figure 2.

- The temporary RBS transmits on its control channel identification data that is the same as for the RBS whose control frequency is used, see step 240 in FIG. 2.

Thus, through the steps outlined above, user terminals in a certain area should perceive a signal that is more powerful than the target RBS signal, and since the received signal is one of the signals in the list of options for the target RBS, they should perceive it as a normal "competing" signal and Switch your traffic to temporary RBS. When and if the BSC is notified of the intensity of the measured signal through user terminals, it instructs them to switch their traffic to temporary RBS for the same reason, i.e. that temporary RBS is perceived as a normal “handover” option.

These steps apply either to the GSM system, i.e. to a TDMA system, or to a CDMA system. As an example, if applied to a GSM system, the identification signal that is transmitted may be a so-called CGI- (global identifier for a cell) or a BSIC signal. This is illustrated in FIG.

Thus, control is obtained of part or all of the traffic of the target RBS, depending on the output level, which is used for transmissions via temporary RBS. The next question is to ensure that control is also supported through temporary RBS, which can be done as follows: user terminals whose traffic is transmitted to temporary RBS, as explained above, listen on the frequencies contained in the list of options of their current RBS, t .e. in this case, temporary RBS.

In order to support the management of these user terminals, the temporary RBS according to the invention is programmed to transmit a list of frequency options, the list being such that user terminals whose traffic is transmitted to the temporary RBS cannot find signals from any of the frequency options near the cell target RBSs, at least not with signal strength such that they appear to be “attractive” options for handover. Thus, there are no "competing frequencies" to listen to, or at least to which you can switch.

One way to achieve this list of options is to empty the list of options, or, alternatively, the list of options may contain RBS frequencies that are known to be so distant that they cannot compete with the temporary RBS. These two alternatives are shown in FIG.

This step of the invention can also be applied equally optimally to TDMA systems or CDMA systems. If applied to a GSM system, the list of options is usually the so-called BA list.

Thus, through the invention, traffic control to and from the target RBS is obtained by and will be supported by the temporary RBS, which is the purpose of the invention.

Returning now to the positioning of the temporary RBS and its programming with respect to the frequency at which it must transmit in order to get traffic control from the target RBS, as well as its list of options, reference is made to FIG. 5.

In FIG. 5, the wireless cellular communication system of FIG. 1 is shown again, with a target RBS designated as 120 and a cell that it controls designated 110. A temporary RBS according to the invention is provided by reference 140.

As mentioned above, the frequency at which the temporary RBS 140 is configured to transmit is selected from the list of options of the target RBS 120. However, the frequency should not be selected from one of the frequencies used by neighboring cells or base stations, for example, a base station of a cell, denoted as 157-159 in FIG. 5, since these base stations can provide a strong signal to target terminals RBS 120.

On the contrary, the temporary RBS 140 should be programmed to transmit at a frequency that is in the list of variants of the target RBS 120, but which belongs to RBS, which is as far away as possible from the target RBS 120, while being in the list of variants of the target RBS 120. Word “remote” in this context can be considered to mean either geographically or as an indicator of signal strength from this RBS in cell 110. One example of such appropriate base stations is shown by 151 in FIG. 5. However, if required, for example, by scheduling and reusing frequencies, the temporary base station may need to “borrow” the frequency and identifier from the neighboring RBS 157-159.

The invention is not limited to the examples of embodiments shown in the drawings and described above, and may vary freely within the scope of the attached claims.

Claims (17)

1. A method for providing and maintaining through a temporary radio base station (RBS) traffic control to and from a target RBS in a wireless cellular communication system, said system comprising a plurality of RBSs for routing traffic to and from user terminals in the system, each RBS controlling traffic to and from a particular cell within the system, with each of at least several of the aforementioned set of RBSs in the system transmitting an identification signal and a list of frequency options for use by user terminals when switching RBS, the method comprising the steps of:
positioning said temporary RBS in the cell of the target RBS or adjacent to the cell of the target RBS,
program the temporary RBS so as to transmit on one of the frequencies in the list of options transmitted in broadcast mode by the target RBS,
transmitting temporary RBS with such a power level that traffic to and from user terminals in the cell of the target RBS is transmitted to temporary RBS,
program the temporary RBS so as to transmit an identification signal that is the same as the identification signal RBS at the frequency of which the temporary RBS is transmitted,
the said temporary RBS is programmed to transmit a list of frequency options, the list being such that user terminals whose traffic is transmitted to the temporary RBS cannot find signals of sufficient intensity in any of the frequency options near the hundredth target RBS. 2. The method of claim 1, wherein the frequency at which the temporary RBS is programmed to transmit is the frequency used by RBS that is not directly adjacent to the hundredth of the target RBS. 3. The method according to claim 1, in which the list of frequency options is empty, so that frequency options cannot be found. 4. The method according to claim 1, used in a code division multiple access (CDMA) system. 5. The method according to claim 1, used in a multiple access system with time division multiplexing (TDMA). 6. The method according to claim 5, used in the global system for mobile communications (GSM). 7. The method according to claim 6, in which the identification signal is a global identifier signal for a cell (CGI). 8. The method of claim 6, wherein the identification signal is a base station identification code (BSIC) signal. 9. The method according to claim 6, in which the list of frequency options is a list of allocation of broadcast control channels (VA list). 10. A temporary base station (RBS), configured to receive and maintain traffic control to and from a target base station in a wireless cellular communication system, said system comprising a plurality of RBSs for routing traffic to and from user terminals in the system, each RBS controls traffic to and from a specific cell within the system, with each of at least one or more of the aforementioned set of RBSs in the system transmitting an identification signal and a list of frequency options for and use by user terminals when switching RBS, wherein the temporary RBS comprises means for transmitting on one of the frequencies in the list of options transmitted in broadcast mode by the target RBS, transmitting means configured to transmit at such a power level that traffic to and from users to the cell of the target RBS will be transmitted to the temporary RBS,
means configured to instruct her to transmit an identification signal, which is the same as the identification signal RBS, the frequency of which transmits a temporary RBS,
means configured to instruct her to transmit a list of frequency options, the list being such that user terminals whose traffic is transmitted to the temporary RBS cannot find signals of sufficient intensity in any of the frequency options near the hundredth target RBS. 11. The temporary base station (RBS) of claim 10, in which the list of frequency options can be made empty, as a result of which the frequency options cannot be found. 12. The temporary base station (RBS) of claim 10, which is RBS for use in a code division multiple access (CDMA) system. 13. The temporary base station (RBS) of claim 10, which is RBS for use in a time division multiple access (TDMA) system. 14. The temporary base station (RBS) of claim 13, which is RBS for use in a global system for mobile communications (GSM). 15. The temporary base station (RBS) of claim 14, wherein the identification signal is a global cell identifier (CGI) signal. 16. The temporary base station (RBS) of claim 14, wherein the identification signal is a base station identification code (BSIC) signal. 17. The temporary base station (RBS) according to 14, in which the list of frequency options is a list of allocation of broadcast control channels (VA list).

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