CN1871867B - Virtual cellular radio network - Google Patents

Abstract

A virtual network (24) is created by providing antennas (14) controlled by the same base station (8) with control signals of different virtual base stations. A virtual network controller (20) comprised in the base station is arranged for performing handovers between sets of physical channels of the different virtual base stations. The handover is preferably performed transparently towards the main communication network. This transparency is preferably provided by associating physical channels of virtual base stations with communication channels of the main communications network. Preferably, position estimations of a mobile terminal (6) connected to the base station (8) are performed by the virtual network controller (20), whereby such estimations can be kept secret within the virtual network (24).

Description

virtual cellular radio network

technical field

The present invention relates generally to cellular communication networks and, more particularly, to such a network having geographically smaller cells.

Background technique

The possibility to determine the location of a mobile device has enabled application developers and wireless network operators to offer location-based and location-aware services. Examples of this are tour guide systems, shopping assistance, friend finders, and other information services that provide mobile users with information about the mobile user's environment.

In addition to commercial services, several governments have mandated that network operators be able to determine the location of emergency calls. For example, there is a government requirement in the USA (FCC E911) that it must be possible to determine the location of a certain percentage of all emergency calls. The requirements for the indoor environment are no different compared to the outdoor environment.

In an outdoor environment, position estimation may be performed using external methods for position determination, eg GPS (Global Positioning System) based methods like Assisted-GPS (A-GPS). Location estimation can also be performed using the wireless network itself. The methods of using wireless networks can be divided into two main groups. The first group includes methods based on the radio cell to which the mobile terminal is attached, eg by using a Cell-ID or E-CGI (Enhanced Cell Global Identity). The second group uses measurements of radio signals from several base stations (BS) and uses eg time difference (TD) to determine the terminal position.

In order to be able to connect to a mobile network or to perform a handover when already connected to a network, a mobile terminal usually constantly measures available signals from its own base station and from other base stations. These signals are usually control signals intended for measuring the radio conditions of the transmission, which, together with data, contain information on how to establish the connection to the transmitting base station. In particular, the control signal comprises data which constitute base station identification data by themselves or together with the carrier frequency on which the control signal is transmitted. In this way, the mobile terminal is able to obtain the identity of the transmitting base station and estimate the radio conditions. In GSM (Global System for Mobile Communications), the mobile terminal usually compiles this information in a neighbor list, which is transmitted as information to the network.

The location estimate can be based on measurements in a neighbor list. Then, combined with knowledge of the precise location of the base station, the relationship between the distance to the radio base station and the radio conditions is used. Within the communication network, the location of the base station is known. This means that the neighbor list can be easily used for position estimation according to different algorithms. The accuracy of the location estimate is proportional to the cell size.

Triangulation methods or Time Difference (TD) methods utilize signals associated with two or more base stations. These signals are used to calculate where the mobile terminal is located, or to calculate how far the mobile terminal is located from the base station. This calculation is based on the relative or absolute difference in the time taken for a signal to travel between the terminal and the different base stations. The achievable accuracy of the TD method depends on the system structure, physical state, and radio conditions. Typically, in mobile telephone systems, the accuracy of the ID method is 50-150 meters. The TD method is relatively time and resource consuming.

Fingerprinting methods exploit the fact that everywhere has a more or less unique characteristic signature of the received radio signal. This is a result of multipath and reflections within buildings or obstacles. By storing in the database characteristic radio signatures of different locations, it is possible to determine the location of the device by comparing the received signal signature with the signature stored in the database. Fingerprinting methods require continuously updated databases. High results also often depend on being able to match signals from different sources or different base stations.

A terminal located indoors typically has a connection to a base station covering the surrounding outdoor area, the quality of which is lower when the terminal is located indoors than when the terminal is located outdoors. To improve the indoor coverage situation, many larger buildings are equipped with indoor telephone systems. Indoor systems usually consist of a base station and distributed antenna system or leaky cable antenna in most cases. For buildings covering large areas, repeaters are often used. This makes the whole building look like one big radio cell, and it is impossible to determine where the terminals are located within the building. Furthermore, due to the weak signals from outdoor base stations, more complex methods such as triangulation cannot usually be applied.

WO-92/02104 describes a cellular radio system in which a plurality of base stations, each having a radio transceiver, provide radio coverage over respective radio coverage areas. The identification transmitter repeatedly transmits an identification signal over an identification radio coverage area at least partially within one of said radio coverage areas, so that a mobile station 6 having a radio transceiver can communicate with one of the base stations, and, upon receipt of the identification signal, the mobile station can then be determined to be within said identity radio coverage of the identity transmitter.

WO-01/01714 discloses defining times and places for a mobile phone when you do not want to use the mobile phone. The mobile radio system constantly monitors whether said time and place have been reached when the mobile phone is not in use, and if this is the case, an action is initiated which renders the mobile phone unusable. According to the simplest scenario, a request to shutdown is issued. In the most extreme cases, the mobile phone switches off automatically. When a mobile phone is not in use at a particular location, the mobile radio system constantly monitors the location of the mobile phone within the mobile radio system.

In EP-1109416 a Wireless Mobile Server (WMS) in a cellular network presents the appearance of a single MSC/VLR to the ANS-41 signaling network. The WMS hides from the Call Server (CS) the fact that one or more terminals in the call are wireless or mobile; thus enabling the utilization of CS derived from outside the MSC. Supporting the operation of the WMS is the Terminal Proxy (TP), which effectively hides the radio technology-specific operational details of the radio access network according to the WMS.

A simple solution is to use another system not based on any mobile phone system for positioning. This could be an indoor GPS system, a WLAN (Wireless Local Area Network) or Bluetooth based system, or some other sensor solution. However, such systems require additional complex equipment and the terminals are also equipped with special hardware and/or software, which makes this solution costly.

Another simple solution is to increase the number of indoor base stations, which reduces the cell size. Since this solution can reuse communication resources more efficiently, it will also increase the total available resources.

However, since the cost of such a solution would be high, the base station is an expensive piece of equipment. Furthermore, the introduction of smaller cells will increase the number of handovers necessary because of the increased likelihood of mobile terminals crossing cell boundaries. By introducing very small cells necessary for precise positioning, the number of handovers is greatly increased. Therefore, the load of the connected BSC or RNC for handling the handover procedure will also increase greatly.

In some applications, the introduction of a hierarchical structure with a layer of macro cells and a layer of micro cells helps to solve the problem of frequent handovers. Mobile terminals that move relatively fast are allocated to macro cells, and mobile terminals that move slowly or quasi-stationary can be allocated to micro cells. In this way, a more accurate position estimate can be made for a slowly moving mobile terminal. However, the introduction of a macro cell layer and a micro cell layer requires an additional communication channel, because in general, a macro cell and a micro cell cannot use the same communication channel. Furthermore, managing this layered structure is laborious, requiring both hardware and software considerations. Finally, precise location determination of fast-moving terminals remains impossible.

In some cases, it is required to have precise location determination for local features. For example, in a large office building or product factory, the current location of any employee can be discovered if the employees are all carrying mobile devices. This is very advantageous for office management and factory management, but for network operators, location determination "inside a specific office building" is sufficient. Furthermore, some local data, eg inside a building, can reveal company secrets. Therefore, it is desirable to have an accurate position estimate in many situations, but this is usually not available to the entire communication network except in emergency situations. Selective access to location information is not possible in the prior art.

Contents of the invention

A problem with the prior art is that it is difficult to improve the accuracy of the location estimate without greatly increasing the signaling traffic to the radio access station controller or the management of the hierarchical cell structure. Another problem with the prior art is that it is not possible to make position estimates selectively available to different network users.

It is an object of the present invention to provide a method and apparatus for improving the accuracy of position estimation. Another object of the invention is to provide a method and an arrangement which do not increase the traffic load on the radio access station controller. It is a further object of the present invention to provide a method and apparatus for making position estimate information selectively available to different communication network parties and/or to a certain local area. Yet another object is to provide such a method and device which enhances the control possibilities for local users (eg building owners) over a radio network within a respective local area.

The above objects are achieved by a method and a device according to the appended claims. In summary, a virtual network is created by providing the signals of the antennas to the antennas controlled by the same radio access station. A virtual network controller is arranged to perform switching between sets of physical channels of different antennas. Preferably, the handover is performed transparently to the primary communication network. Transparency is preferably provided by associating the physical channel of the antenna with the communication channel of the primary communication network. Preferably, location estimation is performed by a network controller whereby such estimation can be kept private within the virtual network.

An advantage of the present invention is that, to a certain extent, the virtual network can be managed separately from the main communication network. This can greatly reduce the amount of handover-related traffic between the radio access station and the radio access station controller. Furthermore, switching and position estimation using antennas can be kept private within the virtual network.

Description of drawings

The present invention, together with further objects and advantages thereof, is best understood by reference to the accompanying drawings together with the ensuing description.

Figure 1A is a schematic illustration of a cellular communication system;

Fig. 1 B is the block diagram of connecting network unit in cellular communication system;

Figure 2 is an illustration of typical content in a neighbor list;

Figure 3 is a schematic illustration of a distributed antenna system according to the prior art;

Figure 4 is a schematic illustration of a part of a radio network according to an embodiment of the invention;

Figure 5 is a schematic illustration of a portion of a radio network with a distributed antenna system according to an embodiment of the invention;

6A and 6B are schematic illustrations of transformation functions of a virtual network controller on a control plane and a data plane, respectively, according to an embodiment of the present invention;

7A and 7B are schematic illustrations of other virtual network controller embodiments according to the present invention;

FIG. 7C is a schematic illustration of carrier reuse in a virtual cellular network embodiment according to the present invention;

Figure 8 is a block diagram of an embodiment of a radio base station according to the present invention;

Figure 9 is a block diagram of another radio base station embodiment according to the present invention;

Figure 10 is an illustration of transitioning between an internal neighbor list and an external neighbor list;

11A-C are cell plan views of a virtual network according to the present invention; and

Figure 12 is a flowchart illustrating the main steps in one embodiment of the method according to the invention.

Detailed ways

In order to fully understand the operation of the present invention, a short review of control signaling and general position estimation in cellular networks is first given.

In the main part of this detailed description of the invention, a system based on GSM technology is used as an exemplary embodiment. However, the basic idea of the invention is not restricted to these specifically described embodiments, but is generally applicable to many different cellular communication systems.

A cellular network 10 is schematically illustrated in FIG. 1A, the basic idea of which is to structure the network as a grid of cells 4A-4J, where each cell 4A-4J is served by a radio base station 2A-2J. covered area. Communication takes place via different radio resources. In order to avoid interference between mobile phones 6 and radio base stations 2A-2J in adjacent cells, communications between mobile phones 6 and base stations 2A-2J use different resources or communication channels, i.e. slightly different (e.g., frequency and encoding) configuration or settings. The number of those resources or "configurations" is limited. In the GSM system, resources are formed by a limited number of allowed carrier frequencies and they are used to isolate communications in different cells. In WCDMA (Wideband Code Division Multiple Access) systems, resources are characterized by a limited number of different codes. The consequence of the limited number of radio resources means that it is important to plan the network 10 carefully.

Mobile stations (MS), mobile phones, mobile terminals, and handsets all refer to devices that are movable within the area covered by a communication system. These terms will be used as equivalent expressions in the disclosure of the present invention. The device is typically a mobile phone, a handheld computer, a so-called Personal Digital Assistant (PDA), or other device or device equipped with a radio receiver for cellular or mobile networks.

A block diagram of network elements in a GSM network is illustrated in Figure 1B. The MSC (Mobile Services Switching Center) 50 is typically connected to other MSCs, or to other external networks 52 via (not shown) a GMSC (Gateway to MSC). The MSC 50 is connected to one or more BSCs (Base Station Controllers) 60 and has switching means 51 which connect the different network elements connected to the BSC 60. The BSC 60 is responsible for managing one or more base stations 8, and the traffic to and from the MSC 50 and different base stations 8 is switched by a switching function 61. The BSC 60 also has means 62 for performing handover and means 63 for performing position estimation, 63 estimating the position of a mobile terminal connected to the base station 8, for example by using a neighbor list reported by the mobile terminal. Alternatively, the means 63 for estimating position may be arranged for reporting information associated with the position determination to another node within the network in which the actual estimation is performed. The base station 8 comprises a transceiver radio interface 71 which divides the traffic of the different channel frequencies to the transceiver units 72A and 72B. The outputs of transceivers 72A, 72B are multiplexed by multiplexer 74 and sent to antenna 14 . The functions in the base station 8 are controlled by a base station control system 73 .

Communications using a cellular communication system typically involve data and control signals sent on traffic and control channels, respectively. There are three types of control channels in the GSM system. BCH (Broadcast Channel) includes channels that continuously send information about cell and network parameters to mobile terminals. For example, the channel BCCH (Broadcast Control Channel) is used to transmit cell specific information. Communication on the BCH channel takes place in the DL (downlink) direction. BCH data is provided by base station 8 .

Other control channels are used for paging, access functions, and signaling between the network and the mobile terminal before or during a call. Such control signaling is used eg by the mobile terminal to inform the network eg of measurements of neighboring transmitters. Signaling related to authentication is also performed by such control signaling. For CCCH (Common Control Channel) and DCCH (Dedicated Control Channel), the information is usually provided to or by the BSC or MSC, and the information is only relayed through the base station.

Returning to FIG. 1A, in most cellular networks 10, the mobile terminal 6 continuously measures the reception condition of radio signals. There are several reasons. One is the ability to modify transmit power to avoid sending with unnecessarily high transmit power. Usually, but not necessarily, the radio base station with the best radio conditions is the one used to connect to the cellular network. The base station with the best radio conditions is also the one closest to the mobile phone 6 in most cases. In FIG. 1A, a mobile phone 6 is connected via a base station 2F. Thus, the mobile telephone 6 is located within the cell 4F of that particular base station 2F. A radio cell is defined as the area around a base station, in which a base station is the base station with the best connection to the mobile phone. Since the cellular network knows the locations of the transmission points associated with the base stations, the identification of the base station with the best radio conditions also gives an approximate location estimate for the mobile phone. The cell size is proportional to the base station density. Thus, in Figure 1A, it can be concluded that the mobile telephone 6 is currently within the cell 4F.

To know which base station to connect to, the mobile phone also constantly measures signals sent from other base stations. These signals are dedicated control signals intended to measure radio conditions between the mobile phone and the base station. Along with data, these signals include information on how to establish a connection to the base station that sent the signal. As mentioned above, communication within adjacent cells is performed through links with slightly different configurations to avoid interference. Often those different configurations are used to send control signals. As an example, in GSM, control signals from one base station are transmitted on a different frequency than control signals transmitted from adjacent base stations. However, more distant base stations can use the same frequency in reuse mode. In order to be able to separate those base stations associated with different cells but transmitting control signals on the same frequency, the control signals also contain other information that can distinguish the control signal from one base station from the control signal area from another base station. This information alone or in combination with the frequency of the control signal gives the possibility to identify a particular base station. In other words, the control signal includes base station identification data. In GSM, so-called color codes are used to separate the different base stations from each other.

The network usually informs the mobile terminal which base stations are nearby. The mobile phone then knows what control signals to look for. If the information to be measured is not available, the mobile phone can also measure the signal from every other base station. This may be the case, for example, in areas not covered by the user's operator but covered by other operators. The measurement results of the control signals transmitted from the base station are usually stored in coded form in the mobile terminal. In a mobile terminal, such a list of neighboring base stations, or at least data corresponding to such a list, is kept up to date and is often referred to as a neighbor list.

An example of such a neighbor list for the case of FIG. 1 is illustrated in FIG. 2 . The list is sorted based on radio condition quality, with base stations having the best radio conditions at the top of the list. Each row 100 of the list refers to a particular base station. In this example, the first column 102 includes base station identifications. The second part 104 includes additional information. In this embodiment, the second column 105 includes general information. The third to fifth columns 106-108 include data associated with, for example, measurements of radio condition quality for each base station, signal quality, prohibition flags, or similar data important to handover decisions.

The measurements of this list are continuously transmitted to the base station to keep the network up to date with radio conditions. Thereby the base station or any network server connected to the station can retrieve the contents of the neighbor list of any connected mobile terminal.

In this disclosure, the expressions "location" and "location" will be used. "Location" means a geographic location given in coordinates or degrees (eg, WGS-84 datum). It can also contain bearing and/or direction, velocity, acceleration, etc., and can also give position in relative measurements. A "place" is a more personal location, defined by or in relation to the type of institution or residence. Examples of "places" are: "military area/factory", "hospital", "government office", "theater", "close to emergency exit". It is assumed that the expression "location" also includes places included by "location".

The most common position estimation is to determine the approximate position to be within the cell of the base station with the best radio connection to the mobile terminal (ie the base station at the top of the neighbor list). In FIG. 1A, this means that there is a certain probability that it can be concluded that the mobile phone 6 is located within the cell 4F. Using several entries in the neighbor list for different algorithms means that better accuracy can be calculated than the cell, which is the cell where the mobile phone is located. In Fig. 2 it is seen that the base station 2G is in the second position in the neighbor list. It is then likely that the mobile phone is located within a 60° sector facing the cell 4G, marked with a dotted line in Figure 1A. Furthermore, since base station 21 is the third entry in the neighbor list, it is also possible that mobile terminal 6 is located on the half of the sector closest to cell 4I. Furthermore, additional accuracy can be obtained by taking into account, for example, signal strength ratios and the like.

The conversion or computation of the neighbor list into a position and/or location estimate can be performed in the cellular system or within the terminal. If the position estimation is done in the system, eg in a network server, the mobile terminal has to send a neighbor list or measurements corresponding to the neighbor list to the radio base station. If the mobile terminal performs the position estimation itself, then in a basic concept this estimation may consist, for example, of determining the closest base station, eg in the form of a cell ID. In some cases, such a location estimate can be sufficient to support many location determination based services. However, if the actual geographic location is to be estimated, the mobile terminal first needs information about that particular environment. Such information should contain at least the known positions of the different base stations, and this information can be deduced, for example, from instructions about the base stations to be measured. Other information that may be specific to a site, building, or environment may also be useful. Such specific information about eg a specific building may comprise map information by means of which some areas where the mobile terminal is unlikely to be located can be excluded by the position determination. It is for example obvious that the mobile terminal cannot be located within a solid wall, and it is also quite possible that the mobile terminal is not hovering 10 meters above the ground.

Indoor coverage in cellular systems is often of lower quality than outdoors. Therefore, many larger buildings have their own local cell or multiple local cells. A typical existing system is illustrated in FIG. 3 . A single base station 8 serves a distributed antenna system comprising a plurality of antennas 14 distributed over an indoor area. Repeaters 12 may be present to boost the signal during distribution. Since all antennas provide the same information, mobile terminal 6 sees all antennas 14 together as one transmission system associated with one single cell 4 . Furthermore, since the mobile terminal 6 does not know which antenna it is actually communicating with, the precise position estimation described above is unlikely to work well. One way to improve the accuracy of the location estimate is to provide smaller cells.

It is assumed that distributed antenna systems as well as leaky cable systems and subsystems fed by repeaters or any other active components are particularly suitable for implementing the invention. The term "antenna" is often used both for an antenna in a distributed antenna system and for a part of a leaky cable on a leaky cable antenna. However, the invention is applicable to all possible types of antenna systems.

Typical bad connections to base stations used for outdoor coverage, combined with environments with many fading, also make it difficult or even impossible to use base stations located outdoors for triangulation. Use repeaters in some buildings that spread out over large areas (such as airports). The cell then becomes even larger, which leads to a larger area in which the mobile phone is located when it is connected to the cell, ie a less accurate position estimate.

The accuracy of location estimation based on neighbor lists is basically proportional to the cell size. In general, smaller cells enable more precise and accurate location estimates. However, cells are controlled by base stations, and base stations are usually very expensive. At least in methods in which the base station for position estimation cannot effectively participate in positioning, the functionality required in the base station for position estimation is very limited. In fact, it is sufficient for the positioning routine if only control signals including base station identification data are sent from well-defined locations.

As mentioned above, the present invention is applicable to most cellular communication networks. However, it was also mentioned above that it is presently believed to be particularly advantageous when the invention is applied to the estimation of the position of mobile terminals located in distributed antenna systems, leaky cable systems, or sub-systems fed by repeaters. The accuracy of the position determination method according to the invention depends eg on the building or environment in which the invention is implemented, and other preconditions as well as various customer requirements. However, a position accuracy of 20-50 meters is considered realistic. The invention can be advantageously used to locate mobile terminals in indoor systems, underground railway systems (subways) and subsystems connected to macrocellular systems (eg tunnels to radio macrocells using repeaters).

The basic idea of the invention is to divide a larger cell into several smaller virtual cells. A virtual cell is virtual in the sense that it is not known or at least not completely known to the macro network. The virtual cells together form a local virtual cellular network controlled by a base station with a VNC (Virtual Network Controller). Much of the intelligence that manages the connection to the mobile phone is contained within the VNC, normally performed within the network element, eg the BSC in GSM, or the RNC (Radio Network Controller) in WCDMA. An embodiment of a radio network according to the invention is schematically illustrated in FIG. 4 . Here, four antennas 14 are connected to the base station 8 via separate antenna cables 16 . Each antenna 14 transmits control signals with respective virtual base station identification data on a different broadcast channel, and each antenna 14 constitutes the center of a virtual cell 7 in the local virtual cellular network 24. The base station 8 is further connected to the BSC via a connection 22 . Base station 8 physically and/or logically includes VNC 20 .

According to the present invention, VNC 20 includes functionality for managing switching within a virtual network. If the mobile terminal 6 moves from one virtual cell 7 to another, the VNC 20 has full responsibility for managing the switching between channels available on the corresponding antenna 14.

The mobile terminal 6 regards the virtual cell 7 as an ordinary cell in an ordinary cellular network, and cannot notice the existence of the VNC 20. Thus, the mobile terminal 6 provides measurements of adjacent control channels and reports such measurements to the communication network as in a normal cellular network. However, according to the invention, some information provided by the mobile terminal 6 is terminated in the VNC 20, or at least monitored, and if appropriate, forwarded to the BSC.

In the preferred embodiment of the present invention, the VNC terminates any connection information with a connection to the local virtual cellular network 24 . This means that the BSC controlling the base stations 8 and other components in the cellular network do not experience virtual cells at all. From the main network point of view, base station 8 and VNC 20 work as the base station of a single cell.

Dividing the cell into several virtual cells 7 of the virtual network 24 results in providing the mobile terminal 6 with more precise information about its actual location. Control signaling from each of the antennas 14 can be measured and can provide a basis for a more precise position determination. At the same time, the primary communication network is not disturbed by the increased cell division, or at least the disturbance is reduced to a very low level. The assumed increased handover requirements in the virtual network 24 are managed internally, ie by the VNC, and the BSC only handles handovers from the virtual network 24 to other external cells and from other external cells to the virtual network 24 . In a preferred embodiment, the BSC is not even aware of the existence of the virtual cell 7 .

When creating a virtual cellular network like that of Figure 4, often multiple new antennas must be provided. However, existing antennas can be used if the idea according to the invention is implemented eg in a distributed antenna system. An embodiment of the invention with a distributed antenna system is schematically illustrated in FIG. 5 . The four antennas 14 of the distributed antenna system 15 are connected to the base station 8 via a common antenna cable 17. As mentioned above, each antenna 14 transmits control signals with respective virtual base station identification data on a different broadcast channel, and each antenna 14 forms the center of a virtual cell 7 in the local virtual cellular network 14 . The base station 8 is further connected to the BSC via a connection 22 . Base station 8 physically and/or logically includes VNC 20. In the present invention, the VNC 20 also includes a signal injector 26 that multiplexes control signals to all antennas 14 onto one common antenna cable 17. On each antenna 14 there is provided a signal selector 28 which filters the signals on the common antenna cable 17 in order to extract the signal associated with that particular antenna. These devices are described in more detail further below. In such a configuration, the VNC 20 includes a central unit 20 and a plurality of satellite units 28, but they are still logically part of the base station 8.

6A and 6B illustrate the principle of making the virtual network 24 invisible to external systems by schematically representing the channels available for control signals and data signals, respectively. Five physical channel sets c0-c4 are depicted in FIG. 6A. In this embodiment, a GSM system is assumed, and the physical channel sets correspond to different carrier frequencies. In the right part of the figure, the channel state at the BSC side is illustrated. On the main network side, carrier frequencies c0-c4 are allocated to the base station with BSIC "BS0". Carrier frequency c0 is used for the control channel, specifically slot 0 (from 8 slots). Carrier frequencies c1-c4 are used as pure traffic channels and are therefore time slots for which carrier c0 is not used for control signaling.

On the virtual network side, carrier frequencies c0-c4 are assigned to five different virtual base stations with BSICs "VBS0" to "CBS4" respectively. Each virtual base station is assigned a specific carrier frequency c0-c4 on which both control signaling and data traffic should be transmitted.

A control signal 31 intended for a mobile terminal connected to the base station BS0 is intended to be transmitted in a specific time slot of the carrier frequency c0. The carriers, or actually the signals intended to be sent on these carriers, are sent to the VNC 20. The VNC 20 includes a channel changer 30 that associates a communication channel of the external network with a physical channel of the internal virtual cellular network. This is illustrated by line 32 . Here it can be seen that the control signal 31 arriving at the time slot of c0 is associated with the time slot in the virtual network side carrier c3, as indicated by line 29 . Carrier c3 is allocated to virtual base station VBS3. The content of the BCH part of the control signaling is usually provided by the base station. In the present invention, this function is easily integrated into the control signal injector 33 in VNC. In this example, the control signal injector 33 provides BCH data defining VBS3 and inserts these data into the control signals sent to the virtual network. Also, depending on the association 32 of the channel changer 30, it may be necessary to modify the DCCH control signal both in the UL (uplink) direction and in the DL direction. This is performed by DCCH modifier 39 . In the DL signal, any data relating to the actual carrier used or identified by the base station is exchanged for the corresponding data for the associated channel in the virtual cellular network. In the UL signal, the corresponding data exchange takes place.

The corresponding data plane is illustrated in Figure 6B. The data traffic 34 associated with the control signal 31 in Fig. 6A is allocated to a specific time slot of the carrier c4 on the primary network side. The channel changer 30 of the VNC 20 associates this input channel with a time slot of the carrier c336 on the virtual network side, illustrated by line 35. The data content has not been changed. With this configuration, the host network will be essentially ignorant of the actual channels used in the virtual cellular network.

Since only the VNC 20 has full knowledge of the radio connections within the virtual network, switching within the virtual network must be managed by the VNC or a device connected to the VNC. Therefore, VNC 20 also includes switch manager 37 . When the signal level of the mobile terminal connected to the virtual base station VBS3 is too low, it needs to be handed over. In the UL direction, the terminal's neighbor list is sent intermittently on the DCCH in the form of measurement reports. Since DCCH modifier 39 has access to this information, the appropriate selection for handover can be made by VNC 20 . Assuming that the mobile terminal has moved closer to VBS2, the handover manager 37 issues an instruction to change the channel changer 30 association. On the main network side, the control channel on c0 is currently associated 32' with a time slot of carrier c2 (ie, 29') on the virtual network side. Similarly, according to 35', the association of the traffic channel is changed to the traffic channel in carrier c2, 36'.

The main network will be completely unaware of such a switching process. Hence, the BSC will not experience any load increase due to the increased number of handovers. Even if in some applications the VNC 20 is not configured to completely separate the virtual channel space from the main network, the VNC 20 can manage the actual handover and then only report new applications to the BSC.

In radio networks where the wireless network has a virtual cellular network that is logically separated from the rest of the radio network, additionally the location determination means must be integrated into the VNC. In FIGS. 6A and 6B , the position estimator is indicated by reference numeral 38 . The position estimator 38 has access to the association of the channel changer 30 and by accessing the precise local data of the antenna, and the data connecting a certain carrier to a certain antenna, the position estimator 38 can easily determine the first position of the mobile position. an approximate value. Furthermore, since the DCCH data is usually modified within the VNC, the location estimator 38 can also be easily provided with information from the mobile terminal's neighbor list. This information can then be used to improve the position estimate. However, actual position estimation in this manner may be performed according to well known prior art procedures.

The case of having more available channels than virtual cells is illustrated in Fig. 7a. In this figure, control channels are shown as solid lines and traffic channels are shown as dashed lines. Three virtual base stations VBSO-VBS2 are included in the virtual network. Each virtual base station occupies a carrier for control signaling, in this example carriers c0-c2. On the virtual network side, carriers c3 and c4 are also used as pure traffic channels. Control signaling from the control channel in c0 on the main network side is associated with each control channel in c0-c2 on the virtual network side. In addition, traffic signals are not only associated with the individual dedicated channels c0-c2, but also with the general traffic channels on c3 and c4. In one embodiment, the traffic channels on c3 and c4 may also be dedicated channels, ie intended for a certain virtual base station. However, in another embodiment, the traffic channels on c3 and c4 may constitute a common resource used by all base stations. However, the VNC must keep a record of which common traffic channels are being used.

Figure 7b illustrates a system with more virtual base stations than available carriers. In this case, only three carriers c0-c2 are available, but there are 8 virtual base stations VBS0-VBS7. The same signal channel carrier frequency is allocated to the virtual base stations VBS0, VBS3 and CBS6. The same signal channel carrier frequency is also allocated to VBS1, VBS4 and VBS7, and the same signal channel carrier frequency is also allocated to VBS2 and VBS5. The cells corresponding to these virtual base stations are illustrated in Figure 7c, where it can be seen that the virtual network is arranged to apply carrier reuse, at least for those used for control signaling. Two adjacent cells do not use the same carrier, but cells that are further apart do. The VNC associates the control signal of the c0 carrier on the main network side with the appropriate control signal carrier on the virtual network side. The virtual base station identification data is also provided for the BCH on the virtual network side, which makes it possible to distinguish virtual base stations using the same carrier frequency. For example, the control signals to VBS0 and VBS3 are sent on the same carrier frequency, but the BCH intended for VBS0 is different from the BCH intended for VBS3. In this embodiment, each of the virtual base stations VBSO-VBS7 has access to only one carrier, which means that traffic data represented by dashed lines must be associated with the same carrier frequency used for control signals on the virtual network side.

From Figures 6a-6b, Figures 7a-7c, it will be apparent to anyone skilled in the art that different combinations of carrier applications may be utilized. For example, carrier reuse virtual network configuration can also be combined with pure traffic data carriers. In this configuration, the service carrier can be dedicated to a specific virtual cell, or can be used as a common resource for the entire virtual network.

Implementation of the VNC functionality can be done in many different ways. Figure 8 illustrates a block diagram of one possible configuration. Base station 8 is connected to BSC 60. The main part of the VNC 20 functionality is located at the input of the base station 8 and, preferably, can be integrated with the transceiver radio interface 71 of the base station 8. As described above, the VNC transforms predetermined carriers and control signaling used during communication with the BSC into virtual network carriers and virtual network control signals. The output of the VNC 20 is divided into outputs for each predetermined virtual network carrier. Each output includes a data traffic output and a control signal output, or only a data traffic output, each output being connected to a transceiver unit 72, depending on the application of the carrier in question. Control signals and data traffic are typically processed in separate error handling units 80 , 81 before they are encoded in the codec unit 82 . The encoded signal is usually released in spikes, so that the encoded signal is processed in the spike processing unit 83 . The DL signal is multiplexed onto the available channels of the carrier in the channel multiplexer 84 and modulated in the modulator 85 . Similarly, UL traffic is demodulated in demodulator 86 and demultiplexed in demultiplexer 87 .

In this embodiment, a distributed antenna system is assumed, and all used carriers are transmitted to the antennas through one common antenna cable 17 . The modulated signals to and from the transceiver unit 72 are multiplexed in an antenna transmit multiplexer 74 . The antenna transmit multiplexer 74 and the BCCH injector 33 function as a control signal injector (see FIG. 5 ). Preferably, the control signal comprising the carrier is multiplexed in such a way that it can be easily extracted or filtered out. The multiplexed signal is sent on the antenna cable 17 and on each antenna 14 to a signal selector 28 . Signal selector 28 includes a filter 88 or separation unit that separates out the carrier containing the control signal intended for use with the carrier and any common service carrier (if present) A virtual base station associated with a particular antenna. These separated carriers are demultiplexed in demultiplexer 89 and modified to appropriate characteristics. Then, the signal of the separated carrier is transmitted by the antenna 14 as a radio frequency electromagnetic wave. Corresponding functions for UR communication are stored in the signal selector 28 and the multiplexers 74 , 89 .

Figure 9 illustrates another embodiment of VNC implementation in a base station. Here, for example, a function of converting a carrier and a control signal is provided for DL related to encoding and spike processing. The BSC 60 is connected to a transceiver radio interface 71 within the base station 8, and signals intended for different carriers are switched to a separate transceiver unit 72. The transceiver unit 72 is arranged for error handling, encoding and spike handling in a conventional manner. In this embodiment, however, the output of the spike processing unit 83 is connected to the VNC 20, which performs the necessary transformations on the carrier and data associated with the virtual base station. Signals intended for different virtual network carriers are multiplexed in multiplexer 74 and then transmitted onto a common antenna cable. In this embodiment, in addition to the filter 88 and the demultiplexing unit 89, the signal selector 28 is also provided with a channel modulator 84, a modulator unit 85, a demultiplexer unit 86 and a channel demultiplexer 87, These units are located in the main base station 8 .

Many other implementations of the invention are possible, and the scope of protection of the invention should not be limited to these exemplary embodiments, but is defined entirely by the appended patent claims.

The basic idea of the invention - the separation of the virtual network from the main network - offers further possible advantages. Since the virtual network base station is only used in the virtual network, the main network cannot know the existence of the virtual network base station at all. However, in order to provide improved location determination, knowledge of the location of the virtual base station must be exploited. This means that the location determination functionality must also be provided by VNC or any server connected to VNC, as briefly described above. The VNC is fully aware of the virtual network configuration, and mobile terminals connected to the VNC continuously send measurement reports corresponding to their neighbor lists. Thereby an accurate position determination can be provided.

In cases where base stations including VNC are operated eg by companies or authorities, precise positioning is worth protecting. Knowledge of the movement patterns of specific mobile terminals can be used for planning eg terrorist attacks or for industrial espionage. In this case, the operator may choose to keep the precise location private from the rest of the communications network. The only information provided to the external network will be that the mobile terminal exists somewhere within the cell of the base station. Therefore, before the mobile terminal's measurement report, ie its neighbor list is forwarded to the external network, it has to be modified. Figure 10 illustrates such a neighbor list modification. The neighbor list for internal use in the virtual network is illustrated on the left. The list includes entries corresponding to measurements of virtual base station signals (denoted by the initial "V") and measurements of normal base station signals. VNC is included in the base station (indicated by "A") for the external network. VNC modifies the neighbor list before it is forwarded to the outside network. Since the first entry is a virtual base station, use this entry as the main signal for the entire virtual network. Measured values such as the quality of the radio conditions are saved, but now with reference to a "normal" base station "A". Delete the remaining virtual base station entries and keep only the normal base station entries. The main network receives the modified neighbor list and can use this neighbor list for somewhat less accurate position determination.

If the precise location is to be exported to a macro network, ie a network outside the local network, this has to be handled and approved by the VNC and/or positioning unit. In a system where the local position estimate is kept secret, there is preferably a function to override this secrecy when an emergency call is made. Emergency calls can be detected by the VNC, which then provides the complete location information to the operator.

The situation when a mobile terminal enters or leaves a virtual network requires additional arrangements. In FIG. 11A, a building 120 is equipped with a virtual network with 9 virtual cells 121-129, but is seen as one cell 140 on the outside. The building 120 has an entrance 130 which is covered by a virtual cell 121 . Since the use of the virtual network is only concerned with entering through this portal 130, the virtual cell 121 can be used as a portal virtual cell. This virtual cell then preferably has the same BSIC and the same control carrier frequency as the "foreign" cell 140 .

When a mobile terminal is handed over to a cell 140 controlled by a base station with VNC, the mobile terminal enters into the virtual network. The mobile terminal receives information about the virtual cell BSIC and the control carrier frequency to search for from the VNC. The VNC also takes over the switching and position estimation routines. Thus, the virtual base station will appear in the neighbor list. As the mobile terminal moves within the building 120, handoffs to other virtual cells will be performed by the VNC. The BSC still considers the mobile terminal to be within cell 140.

When the mobile terminal leaves the building and the signal from the virtual cell 121 becomes too low, at the top of the neighbor list, external cells are available again and the mobile terminal requests a handover to one of these cells. The VNC recognizes these cells as foreign cells and sends handover control back to the BSC.

In order to avoid a mobile station located in a cell in the virtual network other than the virtual cell 121 requesting a handover to a foreign cell, the VNC can delete any foreign cell from the measurement list. Alternatively, an external cell in the neighbor list may be provided with a flag indicating that handover to this cell is not allowed. Another alternative is that VNC itself keeps track of which switching operations are allowed. Since all handovers from the virtual cell have to be handled by the VNC, except for mobile stations located in the virtual cell 121, the VNC can easily deny requests for handovers to external cells.

In FIG. 11B , building 120 has two entrances. Here, the entrance virtual cell 121 must appear at both entrances. The operation then follows the previously described principles. A small disadvantage in this environment is that there may be difficulties in distinguishing between the different inlets 130 .

Another embodiment, which readily operates with multiple inlets 130, is illustrated in FIG. 11C. Here, the "outer" cell 140 of the base station connected to the building 120 covers the entire building area. Control signals and BSIC are available everywhere. However, when the mobile terminal enters the cell, the mobile terminal will automatically be handed over by the VNC to the virtual cell, which will provide an improved position estimate. Consequently, the "outer" cells 140 will also remain at a very low usage level, which ensures free capacity for mobile stations entering or leaving the building. Therefore, this common control channel will be used as an interface between the virtual network and the main network.

Carrier switching between the external network and the virtual network and switching of different carrier channels creates some minor complications. If a single carrier for control signals and multiple traffic channel carriers are used on the external network, but all carriers are used for control signals to different virtual base stations, then the number of traffic channels in the virtual network is less than in the external network . Therefore, the external network must be notified of this limitation in the total amount of available resources. However, it is not necessary to know the precise configuration of these resources.

VNC makes it possible to keep some information private within a virtual network. VNC is also suitable for adding other functions. Within the area covered by a base station, eg a building, there can be some sub-areas, for which there are some rules for the use of mobile terminals. In hospitals, mobile terminals may interfere with life-sustaining medical equipment, so the use of mobile terminals is often prohibited in many end areas. However, there may be many locations within a hospital that allow the mobile terminal to be used in any manner. If the hospital is covered by a virtual network, the VNC can determine the precise location of each mobile terminal. If a mobile terminal approaches an area where mobile terminals are prohibited, the VNC can send a notification to the user, or simply disconnect the mobile terminal.

Another application suitable for integration into VNC may be portal authorization. If a mobile terminal enters an area in which only those authorized persons are allowed to carry a valid mobile terminal, the VNC can request proof of authorization from the user of the mobile terminal, for example in conjunction with a handover procedure. If the user fails to provide such proof of authorization, VNC can cut off the call. Furthermore, the VNC can request such authorization verification if the mobile terminal attempts to connect while already in a restricted area.

Power control is another feature, where the VNC preferably works as a regulator or converter device. Commands and measurements from mobile terminals and BSCs are transformed into information meaningful in the context of the respective cells. The details of this actual implementation will not be discussed further.

The management method according to the invention is mainly aimed at management in cellular mobile radio systems. GSM is the mobile radiotelephone standard used in the exemplary embodiments described within this disclosure. However, the invention is also applicable to other cellular mobile radio systems and their associated standards, e.g. based on TDMA (Time Division Multiple Access), CDMA (Code Division Multiple Access), Wideband CDMA (WCDMA) and TDD (Time Division Duplex) technologies other radio standards.

In the GSM-based embodiments described above, the base station is a radio access station as used in GSM. Likewise, the base station controller is the radio access station controller of the GSM example. These types of nodes also exist in other systems, but sometimes under slightly different names. For example, in WCDMA, access points and radio network controllers correspond to radio access stations and radio station access controllers, respectively. In 3G applications, base stations are often denoted "Node Bs". In this disclosure, "radio access station" is intended to include all different types of base stations, Node Bs, access points, etc., depending on the communication method used.

In the described GSM-based embodiment, time slots constitute physical channels. A physical channel is the smallest portion of radio resources that can be allocated to a single specific user. Thus, a carrier frequency can be viewed as a set of time slots (or physical channels) that can all be used by a particular base station. A base station may also have access to more than one carrier frequency, ie more than one set of physical channels.

In WCDMA, the physical channel is characterized by a specific code, typically a combination of a scrambling code and a channelization code. Each access point can generally use a physical channel with a specific scrambling code, which is in principle independent of the channelization code used. A naturally defined set of physical channels usable by a particular radio access station is characterized in WCDMA by a particular scrambling code.

There is also a minimum allocable resource unit in other cellular communication systems, and the minimum allocable resource unit is called a physical channel in this disclosure. Each radio access station typically also has some set of physical channels, either predefined during cell planning, or not. Therefore, the principles regarding carriers and time slots in the embodiments described above are generally applicable to the set of physical channels and the physical channels themselves.

The main steps of one embodiment of the method according to the invention are illustrated in Fig. 12. The program starts at step 200 . In step 210, control signals associated with the first virtual base station are provided to the first antenna. In step 212, control signals associated with the second virtual base station are provided to the second antenna. In step 214, switching between the first virtual base station and the second virtual base station is performed in the general base station controlling the two virtual base stations. The program ends at step 299.

The embodiments described above are to be understood as a few illustrative examples of the invention. It will be understood by those skilled in the art that various modifications, combinations and changes can be made to these embodiments without departing from the scope of the present invention. In particular, solutions of different parts in different embodiments may be combined into other configurations where technically possible. However, the scope of the present invention is defined by the appended claims.

Claims (38)

1. A radio access station (8), which accesses m physical channel sets (c0-c4), where m is an integer greater than 1; having an antenna output for connection to n antennas (14) in the virtual cellular network (24), n being an integer greater than 1, and comprising a virtual network controller (20) for managing internal handoffs in said virtual cellular network, said virtual network controller (20) comprising a channel changer (30) to be used for channels for communicating with the radio access station controller (60) and physical channels of the set of physical channels (c0-c4) used by said n antennas (14) are associated with each other for communicating with the mobile terminal (6); The virtual network controller (20) is configured to control the first physical channel set in the m physical channel sets (c0-c4) and the second physical channel set in the m physical channel sets (c0-c4) switching operation between; it is characterized in that: the virtual network controller (20) also includes a position determination device (38), and the position determination device (38) is used for accessing the channel changer (30) The location of said mobile terminal (6) is associated and determined by accessing precise location data of an antenna (14) and data linking a certain carrier to one of said n antennas. 2. The radio access station according to claim 1, characterized in that: The virtual network controller (20) is arranged to provide, on said first set of physical channels, control signals associated with a first antenna and having respective virtual base station identification data, intended for said n antennas ( 14) in the first antenna; and The virtual network controller (20) is arranged to provide, on the second set of physical channels, control signals associated with a second antenna different from the first antenna and having respective virtual base station identification data, intended for use in A second antenna among the n antennas (14). 3. A radio access station according to claim 1 or 2, characterized in that said virtual network controller (20) is arranged to terminate any connection information with a connection to said virtual cellular network and to only The information associated with the radio access stations as a whole is transmitted to the radio access station controller (60), whereby the connected mobile terminal (6) regards the n antennas (14) as separate cells (7 ) antennas, and the radio access station controller (60) regards the n antennas (14) as antennas of a single cell (4). 4. A radio access station according to claim 1 or 2, characterized in that said position determining means (38) further estimates the position of said mobile terminal based on a neighbor list (100; 110). 5. The radio access station according to claim 4, characterized in that said virtual network controller (20) further comprises means for modifying the neighbor list (100; 110) of the connected mobile terminal (6) for forwarding to Means for said radio access station controller (60). 6. A radio access station according to claim 1 or 2, characterized in that said antenna output is the output of a common antenna cable (17). 7. The radio access station according to claim 1 or 2, characterized in that said virtual network controller (20) comprises a broadcast control signal injector (26, 33). 8. The radio access station according to claim 1 or 2, characterized in that at least one of the n antennas (14) is connected via a separate antenna cable. 9. A radio access station according to claim 1 or 2, characterized in that said radio access station is selected from a list consisting of: base station; access points; and Node B. 10. A radio access station according to claim 1 or 2, characterized in that said radio access station operates according to GSM, whereby said set of physical channels are frequency carriers (c0-c4) and said physical channels is the time slot. 11. A radio access station according to claim 1 or 2, characterized in that said radio access station operates according to CDMA, whereby said set of physical channels is characterized by a scrambling code and said physical channels are represented by a channelization code characterization. 12. A radio access station according to claim 1 or 2, characterized in that said radio access station operates according to WCDMA whereby said set of physical channels is characterized by a scrambling code and said physical channels are represented by a channelization code characterization. 13. A radio access station according to claim 1 or 2, characterized by means for restricting the use of mobile terminals within the area covered by said radio access station. 14. A radio access station according to claim 13, characterized in that said means for restricting use comprises notification means for sending a notification to the mobile terminal when the mobile terminal enters a restricted-use area. 15. A radio access station according to claim 13, characterized in that said means for restricting use comprises cut-off means for cutting off communications to mobile terminals located in a restricted-use area. 16. A radio access station according to claim 13, characterized in that said means for restricting use comprises authorization means for requesting an authorization certificate from a mobile terminal located in or entering a restricted-use area. 17. A radio access network comprising: radio access station controller (60); a radio access station (8), which accesses m physical channel sets (c0-c4), where m is an integer greater than 1; and a virtual cellular network (24) comprising n antennas (14) connected to said radio access station (8), n being an integer greater than 1, Wherein said radio access station (8) comprises a virtual network controller (20) for managing internal switching in said virtual cellular network, said virtual network controller (20) comprising a channel changer (30), The channel changer (30) compares the channel used for communication with the radio access station controller (60) and the physical channels of the physical channel set (c0-c4) used by the n antennas (14) to each other Associated; The virtual network controller (20) is configured to control the first physical channel set in the m physical channel sets (c0-c4) and the second physical channel set in the m physical channel sets (c0-c4) Switching between operations, It is characterized in that: the virtual network controller (20) also includes a position determination device (38), and the position determination device (38) is used for accessing the association in the channel changer (30) and accessing the antenna ( 14) and data connecting a certain carrier to one of said n antennas to determine the position of the mobile terminal (6). 18. The radio access network according to claim 17, characterized in that: The virtual network controller (20) is arranged to provide, on said first set of physical channels, control signals associated with a first antenna and having respective virtual base station identification data, intended for said n antennas ( 14) in the first antenna; and The virtual network controller (20) is arranged to provide, on the second set of physical channels, control signals associated with second antennas different from the first antenna and having respective virtual base station identification data, intended for use in A second antenna among the n antennas (14). 19. A radio access network according to claim 17 or 18, characterized in that said virtual network controller (20) is arranged to terminate any connection information with a connection to said virtual cellular network and to only The information associated with the radio access stations as a whole is transmitted to the radio access station controller (60), whereby the connected mobile terminal (6) regards the n antennas (14) as separate cells (7 ) antennas, and the radio access station controller (60) regards the n antennas (14) as antennas of a single cell (4). 20. The radio access network according to claim 17 or 18, characterized in that said location determining means (38) further estimates the location of said mobile terminal based on a neighbor list (100; 110). 21. The radio access network according to claim 20, characterized in that said virtual network controller (20) further comprises means for modifying the neighbor list (100; 110) of the connected mobile terminal (60) for forwarding to Means for said radio access station controller (60). 22. The radio access network according to claim 17 or 18, characterized in that said n antennas (14) are connected by a common antenna cable (17). 23. The radio access network according to claim 17 or 18, characterized by a signal selector (28) on each of said n antennas (14), said virtual network controller (20) comprising a broadcast Control signal injectors (26, 33). 24. The radio access network according to claim 17 or 18, characterized in that at least one of said n antennas (14) is connected by a separate antenna cable. 25. A radio access network according to claim 17 or 18, characterized in that said radio access station is selected from a list consisting of: base station; access points; and Node B. 26. A radio access network according to claim 17 or 18, characterized in that said radio access station controller is selected from the list consisting of: base station controller; and radio network controller. 27. A radio access network according to claim 17 or 18, characterized in that said radio access network operates according to GSM, whereby said set of physical channels are frequency carriers (c0-c4) and said physical channels is the time slot. 28. A radio access network according to claim 17 or 18, characterized in that said radio access network operates according to CDMA, whereby said set of physical channels is characterized by a scrambling code and said physical channels are represented by a channelization code characterization. 29. A radio access network according to claim 17 or 18, characterized in that said radio access network operates according to WCDMA, whereby said set of physical channels is characterized by a scrambling code and the physical channels are characterized by a channelization code. 30. A method of managing a portion of a mobile communication network by performing the steps of: providing control signals associated with the first antenna and having respective virtual base station identification data on a first set of physical channels intended for the first antenna; providing on a second set of physical channels a control signal associated with a second antenna different from the first antenna and having respective virtual base station identification data intended for the second antenna; associating with each other the channel used for communication with the radio access station controller (60) and the physical channels of the set (c0-c4) of physical channels used by n antennas (14) for communication with the mobile terminal (6) communication; performing handover of communication between the sets of physical channels (c0-c4) of the two antennas (14) controlled by the radio access station (8), characterized by the further step of determining said mobile terminal (6) by accessing channel associations and by accessing precise position data of antennas (14) and data connecting a certain carrier to one of said n antennas )s position. 31. A method according to claim 30, characterized in that said handover is performed transparently with respect to a radio access station controller (60) controlling said radio access station (8). 32. The method according to claim 30 or 31, characterized by the further step of: A physical channel of an antenna is adaptively associated with a communication channel used between said radio access station (8) and said radio access station controller (60). 33. The method according to claim 30 or 31, characterized by the further step of: In said radio access station (8), the position of a mobile terminal (6) connected to one of said n antennas is estimated. 34. A method according to claim 33, characterized in that said step of estimating is based on the contents of a neighbor list. 35. The method according to claim 34, characterized by the further step of: The use of mobile terminals is restricted within the area covered by said radio access station. 36. A method according to claim 35, characterized in that said step of restricting use includes the step of notifying the mobile terminal when the mobile terminal enters a restricted-use area. 37. A method according to claim 36, characterized in that said step of restricting use includes the step of cutting off communications to mobile terminals located in a restricted-use area. 38. The method according to claim 36, characterized in that said step of restricting use includes the step of requesting authorization authentication from a mobile terminal located in or entering a restricted-use area.

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