Quasi-synchronous TETRA single-frequency network and methods for selective communication in a quasi-synchronous TETRA single-frequency network

Abstract

The invention relates to a quasi-synchronous TETRA single-frequency network (sQGN) comprising at least two or more base stations (sTBS) with disjoint or at least partially overlapping radio cells (CA), wherein the base stations (sTBS) are interconnected for synchronous or quasi-synchronous single-frequency transmission of communication signals (RC) in the TETRA standard to at least one mobile station (MS). It is proposed that selective single-frequency radiation of communication signals (RC) by a base station (sTBS) can be controlled based on a reception criterion of the mobile station (MS) with respect to the base stations (sTBS). In a secondary aspect, a method for operating the aforementioned TETRA single-frequency network (sQGN) is proposed, wherein single-frequency radiation of communication signals (RC) to a mobile station (MS) is selectively carried out via at least one base station (sTBS) based on a reception criterion.

Description

[0001] The invention relates to a TETRA single frequency network for quasi-synchronous communication, as defined in Chapter 6, paragraph 6.1.3 of ETSI Technical Report ETR-300-1 of May 1997.

[0002] The aim of the invention is to provide a resource-saving single-frequency network and operating method with an increased number of possible subscribers in single-frequency operation through improved call resource utilization and optimized bandwidth utilization. STATE OF THE ART

[0003] The ever-increasing demands of authorities and organizations with security responsibilities require a high-performance, comprehensive communications infrastructure. The available frequency band is extremely limited, which is why frequency-efficient solutions are increasingly gaining attention to ensure the most seamless coverage possible.

[0004] In the context of the invention, communication is understood as an exchange of user data, be it analogue or digital-based data, such as voice or video data or other user data.

[0005] In synchronous transmission in a single-frequency network, also known as a simulcast network, large geographical areas can be covered using just one frequency resource. All base stations used transmit and receive on the same physical channel and are synchronized in such a way that interference with mobile stations such as handheld radios is minimal. However, this method has the disadvantage that call resources—i.e., bandwidth and the number of available voice and data channels—become scarce. In particular, the total number of logical channels does not scale with the number of TETRA base stations, as is the case in cellular networks. Thus, a nationwide network with a generally high number of mobile stations faces limited physical channels.In order to comply with the operating principle of synchronous transmission, each call and data resource must be transmitted to all base stations in the network and transmitted from there, with each physical channel transporting identical data at the same time.

[0006] Similar synchronous TETRA single-frequency networks are known from the prior art, for example, from EP 2 280 497 B1 or EP 2 876 822 B1. These describe various devices and methods for providing synchronous single-frequency transmission of TETRA communication signals.

[0007] US 2013 / 0178218 A1 discloses a single-frequency network suitable for TETRA, with a synchronization master unit deciding which base stations participate in selective single-frequency transmission based on a reception criterion such as the position of an addressed receiving mobile station. The decision regarding the transmitting base stations is made centrally by the synchronization master unit, which maintains a database of available base stations.

[0008] US 5,263,177 A describes a similar single frequency network, in which a master unit determines a selective transmission based on a reception field strength by a base station.

[0009] Other generic single-frequency networks are described in US 2003 / 0060221 A1, DE 691 27 737 T2, and US 6,381,466 B1. The object of the invention is the economical use of call resources in a TETRA single-frequency network with quasi-synchronous transmission, i.e., in single-frequency operation with a plurality of base stations.

[0010] Particular attention is paid to the functionality, operational experience, and design of the TETRA single-frequency network, which must meet the highest standards of reliability. This is a fundamental principle of mission-critical communications in the TETRA communication standard and is not yet replicated in any other mobile communications standard, such as 4G / 5G. The goal is to ensure that all information from the sender is also transmitted to the receiver. DISCLOSURE OF THE INVENTION

[0011] In a first aspect, the invention relates to a quasi-synchronous TETRA single-frequency network comprising at least two or more base stations with disjoint or at least partially overlapping radio cells, wherein the base stations are interconnected for synchronous or quasi-synchronous single-frequency radiation in the TETRA standard of communication signals to at least one mobile station.

[0012] In this case, a selective single-frequency radiation of communication signals can be controlled by a base station based on a reception criterion of the mobile station with respect to the base stations.

[0013] According to the invention, a single-frequency radiation of a communication signal by the base stations to the mobile station can be controlled on the basis of the reception criterion within the base stations.

[0014] In other words, the invention relates to a TETRA single-frequency network comprising at least two or more base stations with disjoint or at least partially overlapping effective ranges, in which the base stations are connected to one another for synchronous or quasi-synchronous single-frequency radiation in the TETRA standard from physical channels to at least one mobile station, such as a mobile handset, vehicle radio, etc.

[0015] Each base station individually evaluates its reception criterion with a mobile station addressed by a communication signal and decides, if a preset threshold value is exceeded or not reached compared to the reception criterion, whether a simulcast transmission of a communication signal can take place or not take place.

[0016] Thus, each base station individually evaluates its reception criteria with a mobile station addressed by a communication signal. If a preset threshold is exceeded or undershot compared to the reception criterion, it decides whether a single-frequency transmission of a communication signal can be initiated or omitted. According to the invention, a selective transmission of different logical channels per base station through the same physical channels at the same time in the single-frequency network can be controlled based on the local assignment of the MS to one or more TBSs. This allows different data to be transmitted simultaneously per base station, thereby increasing capacity in the single-frequency network and maintaining network performance for a growing number of users.

[0017] The aim of the invention is therefore to provide a quasi-synchronous TETRA single-frequency network and an operating method utilizing this to increase capacity in TETRA single-frequency operation by simultaneously transmitting different data per physical channel per base station. This provides each base station with a limited number of physical channels, typically four, which can be allocated independently of one another. Ideally, this results in the number of logical channels increasing by this limited number, for example, by four, for each additional base station. This contradicts the principles of a single-frequency network, since identical information must be transmitted at every location at all times.

[0018] In an advantageous embodiment, the base stations can be connected to at least one synchronization master unit via communication links, wherein the selective forwarding of communication signals can preferably also be controlled by the synchronization master unit. In this embodiment, a reception criterion for each connected base station can be transmitted to the synchronization master unit, which, when forwarding communication signals, only considers those base stations whose reception criteria enable high-quality transmission. Thus, the evaluation of the individual reception criteria and the selective forwarding of communication signals are centrally controlled.

[0019] Naturally, mixed forms of centralized and decentralized reception criteria evaluations are conceivable within a quasi-synchronous single-frequency network with at least one synchronization master unit and individual base stations. It is also conceivable to transfer the inventive concept to an association of several single-frequency networks in which communication channels can be opened between two single-frequency networks. This can enable central or decentralized assignment of all connected mobile stations to at least one effective range of a base station based on suitable physical characteristics as a reception criterion. In addition, or alternatively, central or decentralized assignment of all connected mobile stations to at least one effective range (12) of a base station can be enabled based on transmitted TETRA protocol information and / or TETRA functions.

[0020] In an advantageous embodiment, the reception criterion can include a reception field strength, a bit error rate, a message error rate (MER), a vector error rate (VER), a registration or deregistration of the mobile stations upon dialing into the base stations, location data of the mobile station, in particular WLAN / GPS / mobile radio location data or radio beacon data, and / or predicted movement data of a mobile station, and / or a frequency signature of a mobile station. The base station can then securely reuse resources in a particularly advantageous manner if all subscribers in the network and their locations are known. For this purpose, it is proposed, for example, to extend the Layer 3 function MM of the TETRA-specific ISO / OSI reference model, which includes deregistration / registration, to include further event data and thus introduce an sMM.This includes at least, but is not limited to, the reception field strength, the VER, the BER, the MER of the last operation of each MS referenced to sTBS, as well as the most recently transmitted location coordinates, e.g., GPS coordinates. All data can be time-referenced to ensure timeliness. In this respect, the reception criterion can, for example, include a reception field strength or reception quality of a mobile station, such as a handheld radio, at the base station, a registration of a mobile station when dialing into the base station, location data of a mobile station, in particular WLAN / GPS / mobile radio location data or radio beacon data, and / or predicted movement data and / or a frequency signature of a mobile station. Thus, the signal-to-noise ratio (SNR) or the bit error rate (BER) can be evaluated as a reception criterion.Any parameter that provides a measure of whether a single-frequency transmission from a base station can be received by a mobile station with sufficiently high quality or whether a bidirectional communication link can be established between the base station and mobile station can be used as a reception criterion. This can be done by comparing the spatial position of the base station to the mobile station; the transmission and reception quality can also be used as a reception criterion. The spatial position of a base station is usually known. A mobile station can be spatially located, for example, via a satellite positioning system such as GPS, GLONASS, GALILEO or similar systems such as STARLINK, as is already common with smartphones. Local location determination systems such as direction finding using radio beacons could also be used, which can be integrated into the base station and / or the mobile station if necessary.Optical position detection using a camera in the mobile station (e.g., a smartphone-like handset) is also conceivable, providing information about the nearest base station. A base station that falls below a threshold for a reception criterion will refrain from transmitting a communication signal intended for the mobile station, thus saving bandwidth in this radio cell and ensuring that only a few base stations in good radio contact with mobile stations participate in the transmission of the communication signals.

[0021] In an advantageous embodiment, the synchronization master unit (sSMI) can be configured to synchronize the modulation, carrier frequency, and / or phase data of selectable base stations (sTBS) in order to provide uniform or selective single-frequency radiation.

[0022] In a subordinate aspect, a method for operating a quasi-synchronous TETRA single-frequency network as proposed above is proposed, wherein single-frequency radiation of communication signals to a mobile station is carried out selectively via at least one base station on the basis of a reception criterion.

[0023] Within the scope of the operating method according to the invention, at least one, preferably all, base stations (BTS) decide individually on the selective single-frequency transmission of the communication signal based on a reception criterion. In this respect, the use of a synchronization master unit can be dispensed with.

[0024] Within the scope of the operating method, in one embodiment, a synchronization master unit connected to at least two, in particular all, base stations via communication links can also decide on a selective single-frequency transmission of the communication signal from a base station based on a reception criterion and preferably control a selective forwarding of communication signals to the base station via the communication link. This operating method is particularly suitable for a central decision regarding the forwarding of communication signals to be transmitted, whereby a synchronization master unit can evaluate specific reception criteria with respect to all connected base stations.

[0025] In an advantageous embodiment of the operating method, a synchronization master unit, which is connected via communication links to at least two, in particular all, base stations, can also decide on a selective single-frequency radiation of the communication signal of a base station based on a reception criterion and preferably control a selective forwarding of communication signals via the communication link to the base stations

[0026] In an advantageous further development of the aforementioned embodiment of the operating method, the synchronization master unit can decide on a selective single-frequency transmission of the communication signal of a base station based on a registration or deregistration of a mobile station, a reception field strength, a bit error rate (BER), a message error rate MER, a vector error rate VER, location data of the mobile station, in particular WLAN / GPS / mobile radio location data or radio beacon data, and / or predicted movement data and / or a frequency signature of a mobile station (MS). In other words, for example, a localization of the call participants, in particular the mobile stations such as handheld radios, etc., which can of course also be permanently installed radio devices in vehicles, of a call or data resource can be achieved by defining a reception criterion, for example based on a) a reception field strength of the call participant at the base station b) a reception quality, e.g. based on an SNR or BER value c) registration or re-registration when dialing into the base station system d) GPS data of the terminal device e) or comparable localization services are implemented, whereby only base stations located within the transmission / reception range of the call participants participate in the single-frequency transmission of communication signals addressed to this HRT. All other base stations do not occupy any call resources and remain available. Through precise localization and knowledge of which subscriber is at which location at which time, the required call resources can be allocated in a targeted manner.

[0027] The targeted transmission of different data on a frequency can cause interference, which is perceived as disruption to the end devices. For this reason, the localization of the end devices should be clear so that every participant can communicate. If this is done correctly, no resources are allocated to base stations that do not meet a reception criterion. This allows full system performance to be maintained.

[0028] If a mobile station is located in the overlap area between two base stations, the base stations would transmit identical information, even though only one is necessary for reception. By selectively assigning each station to a BTS, the interference zone can be suppressed.

[0029] The invention's greatest strength lies in spatially extensive networks with a large number of base stations, or when linking multiple TETRA single-frequency networks together, for example, via a single-frequency gateway. For example, an internal single-frequency network within a building can be connected to a single-frequency network in a neighboring building or building complex, and the advantages of the invention can extend across multiple single-frequency networks.

[0030] In an advantageous further development of the aforementioned embodiment of the operating method, the synchronization master unit can synchronize the modulation, carrier frequency, and / or phase data of selectable base stations in order to provide uniform or selective single-frequency transmission. Base stations in a single-frequency network typically transmit at the same frequency. For synchronization, this further development involves synchronizing the relevant radio parameters by the synchronization master unit. Longer travel distances or different processing times of heterogeneous base stations in the single-frequency network can be taken into account during the master unit's synchronization.

[0031] In an advantageous further development of the aforementioned embodiment of the operating method, the synchronization master unit and / or the base stations can decide on selective single-frequency transmission based on an individual identification number and / or a group identification number of a mobile station. Thus, it is conceivable to restrict communication based on the selection of TETRA group GSSIs and a TETRA subscriber identification ISSI. This would result, for example, in regional and supra-regional talkgroups, which can be provided exclusively on dedicated base stations.

[0032] In an advantageous further development of the aforementioned embodiment of the operating method, the synchronization master unit and / or the base stations can request re-registration of the mobile stations based at least on an update rate and / or information from the control channel. Thus, a re-registration method (RRE) can be used to re-locate unknown or time-lapsed subscribers. This can be done depending on the CCH load and the configured update rate. Motion vectors can also be advantageous, since higher update rates may be necessary depending on the movement speed.A frequency signature can serve as a unique identification feature of the mobile station, enabling it to be assigned to a base station within reception range, so that communication directed to this mobile station can be sent and received only via this base station in a resource-saving manner.

[0033] The proposed Tetra single-frequency network and the proposed operating procedure serve to ensure the assignment of each mobile station to the coverage areas of all base stations in the single-frequency network. This provides the basis for the base stations to decide which logical channels can be transmitted simultaneously. This can be achieved by modifying the TETRA Switching and Management Infrastructure (SwMi), i.e., the entire hardware and process flows of the TETRA single-frequency network, or other suitable TETRA standard entities. Signaling can be modified from base station to mobile station, thus selectively making different data available to each base station. The processing of the selectively transmitted data should continue to follow the TETRA standard.

[0034] The actual decision as to which logical channel is transmitted at which time per base station can be found, for example, in a modified Layer 3 function Cell - Radio Cell Information of the TETRA-specific ISO / OSI reference model. In addition to the resource requirements of a mobile station, the CC function can use the data described above to assign the effective range of the base station to a mobile station and can assign the necessary logical channels to the individual base stations accordingly.

[0035] In the simplest case, all mobile stations requesting a resource can be uniquely assigned to one or more effective areas. To address mission-critical considerations, it may be necessary to consider what happens to a mobile station that is not uniquely assigned or not assigned at all.

[0036] To restore the status, a single-frequency network-wide re-registration of the affected subscriber can first be initiated. If this option is unsuccessful, the logical channel QGN could continue to be transmitted to provide user data throughout the entire coverage area of ​​the single-frequency network.

[0037] The invention's greatest strength lies in spatially extensive networks with numerous base stations, for example, in two neighboring locations. A large portion of the resulting communication will take place within a single location. This would, in the simplest case, double the number of possible simultaneous calls. In the event of major disasters, emergency services can be pooled and directly utilize their established communication channels. It is crucial that the selective transmission of data per base station occurs in such a way that no or negligible interference zones arise, ensuring that all participants can be reached under all circumstances. The base stations must also transmit TETRA data intelligently to avoid interference. DRAWINGS

[0038] Further advantages will become apparent from the accompanying drawing description. The drawings illustrate exemplary embodiments of the invention. The drawings, the description, and the claims contain numerous features in combination. Those skilled in the art will also expediently consider the features individually and combine them into further meaningful combinations.

[0039] They show: Fig. 1 a state-of-the-art TETRA single-frequency network QGN; Fig. 2 an embodiment of a quasi-synchronous TETRA single-frequency network sQGN; Fig. 3 a schematic block diagram of a channel distribution of a base station TBS of the prior art: Fig. 4 a schematic block diagram of a channel distribution of an embodiment of a single-frequency network sQGN with selectively transmitting base stations sTBS1 to sTBS3; Fig. 5 an ISO / OSI layer model of the entities of another embodiment of a quasi-selective TETRA single-frequency network sQGN.

[0040] In the figures, similar elements are numbered with the same reference numerals. The figures are merely examples and are not to be construed as limiting.

[0041] This is how Fig. 1 shows a state-of-the-art TETRA single-frequency network QGN with three base stations TBS1, TBS2, and TBS3, each defining a radio cell with an effective range CA1, CA2, and CA3. The effective ranges CA1, CA2, and CA3 overlap in some areas. Each base station TBS is connected to at least one handheld mobile station MS via communication signals RC. A mobile station MS2 is located in the reception range of the radio cell CA1 of the base station TBS1, as is an MS3 in the radio cell CA2 of TBS2, and MS1 and MS4 in the radio cell CA3 of TBS3. For example, a call setup RC from MS1, directed to MS2 via TBS3, is transferred to TBS1 and TBS2 and transmitted in the quasi-synchronous single-frequency network sQGN. The communication signal RC thus occupies a call resource even though the receiver is not located in the transmission / reception range CA2 and CA3 of TBS2 and TBS3.TBS2 and TBS3 thus occupy a physical channel, even though no call participants are within the effective range of these base stations. This allocates resources that could theoretically be made available for another call resource. In the current state of the art, when a mobile station MS transmits a communication signal RC that is directed only to one other mobile station, the communication signal RC is transmitted quasi-synchronously across all base stations TBS. Thus, the communication channel used by the communication signal RC is utilized network-wide and requires a relatively large call resource.

[0042] The Fig. 2 shows the extension of the Fig. 1, the single-frequency network QGN is expanded to include base stations with selective radiation, leading to a quasi-synchronous single-frequency network (sQGN). Here, different logical data is transmitted on the same physical channels. Fig. Figure 2 thus shows a first embodiment of a resource-optimized TETRA single-frequency network (sQGN). With respect to mobile station 1 and mobile station 2, sTBS1 determines that a high reception quality prevails by field strength detection in radio cell CA1 and defines a positive reception criterion for MS1 and MS2. Due to the spatial distance and reduced reception field strength, sTBS1 can only determine a negative reception criterion for MS4, MS5, and MS6. Similarly, sTBS2 defines a positive reception criterion for MS4 and MS5 and negative reception criteria for the remaining mobile stations. sTBS3 determines a positive reception criterion for MS5 and MS6.

[0043] If sTBS1 now receives a communication signal RC1 from MS! directed to MS3, sTBS1 forwards it to MS3 due to the positive reception criterion for MS3, and does not forward the communication signal RC1 to further base stations sTBS2 and sTBS3 of the TETRA single-frequency network sQGN. If sTBS1 then receives a communication signal RC2 from MS2 directed to MS5, sTBS1 refrains from transmitting RC2 and forwards it via the selective synchronization master unit sSMI to the further base stations sTBS2 and sTBS3. Since both demonstrate a positive reception criterion for MS5, RC2 is transmitted via both sTBS2 and sTBS3 as a selective single-frequency signal.

[0044] As already mentioned, the base stations sTBS2 and sTBS3 do not necessarily have to transmit the call via the communication signals RC1 between MS1 ​​and MS3, since these are located exclusively within the effective range CA1 of the base station sTBS1. For a mobile station MS5 that has good communication quality with the base stations sBTS2 and sBTS3, a call occurs simultaneously on a physical channel between MS2 and MS5 within the effective range of the sTBS1, parallel to the call between MS1 ​​and MS2. Thus, in the single-frequency network, the same resource is used multiple times without interference.

[0045] In another connection scenario (not shown), mobile station MS1 ​​can establish a call RCx via sTBS1 and attempt to reach mobile station MS4 via sTBS2. The selective synchronization master unit sSMI accepts the call setup and makes the connection available in the two coverage areas CA1 of sTBS1 and CA2 of sTBS2. Call RCs is not transmitted to sTBS3 because no MS in its coverage area CA3 is participating. At the same time, MS3 wants to establish another call RCy to MS6 via sTBS3. Conventionally, this would not be possible, and call RCy would be placed on hold. In this embodiment, the situation is known to the selective synchronization master unit sSMI. Accordingly, a call between MS3 and MS4 is established in parallel to the call MS1 and MS2 by establishing different logical channels on the same physical channel—in this case, call channels RCx and RCy.In the present case, the effective capacity would have doubled, since the state of the art did not provide capacity for both calls in the single-frequency network QGN according to . Fig. 1 would have been available. However, this may be an embodiment according to Fig. 2 reach.

[0046] In the Fig. Figure 3 shows the assignment of the logical channels L1, L2, L3, and L4 to the physical channels P1, P2, P3, and P4 per base station TBS, according to the state of the art. Each base station has four physical channels available, P1 to P4. These describe the frequency and the corresponding time slot. The data to be transmitted is located in the logical channels L1 to L4. In a conventional single-frequency network, identical logical channels are transmitted on one physical channel at each base station; for example, a main control channel (MCCH) and three traffic channels (TCH) are shown. The base station TBS calculates data that can be transmitted on the four additional physical channels P1 to P4 available according to the standard, or in higher modulation schemes.A full logical channel L1 can be transmitted per physical channel P1, with the information to be transmitted being provided by the base station TBS. For example, L1 carries the information of the control channel CCH, L2 the information of traffic channel 1 TCH1, L3 the information of traffic channel 2 TCH2, and L4 the information of traffic channel 3 TCH1. If additional traffic channels are to be considered, this limits the resources of the physical channels. These can only be expanded by adding more bandwidth, using higher modulation schemes, or by adding additional base station carriers, which also require additional frequencies. Conventionally, this limitation cannot be overcome without expending additional physical resources.An embodiment of a quasi-synchronous single-frequency network sQGN according to the invention efficiently uses the available resources and reuses them.

[0047] Fig. Figure 4 shows a block diagram of another embodiment 10 of a quasi-synchronous TETRA single-frequency network sQGN. Two base stations sTBS1, sTBS2, and sTBS3, each capable of transmitting via physical channels P1 to P3 of a single-frequency network, are each connected to a synchronization master unit sSMI via communication links BS-MI-CC. The synchronization master unit sSMI continuously receives reception criteria from each base station sTBS1, sTBS2, and sTBS3 for each mobile station MS located in the TETRA single-frequency network sQGN. If a communication signal RC is received via at least one base station sTBS1, STBS2 or sTBS3 with regard to forwarding to a mobile station MS, the synchronization master unit sSMI evaluates all reception criteria with regard to the target MS and forwards the communication signal RC selectively only via the communication links BS-MI-CC to those base stations sTBS which are with regard tothe destination mobile station MS must have a positive reception criterion.

[0048] In the Fig. Figure 5 shows a partial OSI model of an embodiment of a single-frequency network (sQGN) with TETRA stacks of the base stations (sTBS) and the selective synchronization master unit (sSMI). All entities are necessary for the operation of a base station (sTBS) and are standardized in many respects. Likewise, the presented model may only be deviated from in one way or another, ensuring interoperability, the manufacturer-independent functionality of all TETRA functions. Thus, in this embodiment, the Mobility Management (MM) can be expanded to include additional functional data relating to subscriber localization. A fundamental function of Mobility Management is the de-registration / registration of a mobile station (MS) within the effective range (CA) of a base station (sTBS). Thus, all subscribers, i.e., mobile stations (MS), are known to Mobility Management.The resulting subscriber matrix is ​​expanded to map the event data for location and timeliness. Which MS, for example, is authorized to establish a call is mapped in the Call Control CC entity. This is where the function of the selective synchronization master unit (sQGN) is implemented. In addition to the actual requirements for establishing a call and distributing the available resources, the patent also implements the reuse of physical channels in the single-frequency network (sQGN).

[0049] As in Fig. As shown in Figure 5, the OSI model of the TETRA stack of the further embodiment of a single-frequency sQGN shows, a physical channel can be transmitted at any time, which transports the information of a logical channel. Due to, for example, a large spatial distance between sTBS1 and sTBSx, it is possible to transmit different logical channels on the same physical channel at the same time. While the logical channels L1 to L4 on sTBS1, for example, transport L1 MCCH, L2 TCH2, L3 TCH2 and L4 TCH3, the logical channels L1 MCCH, L2 TCH1, L5 TCH4 and L6 TCH5 are transmitted on sTBSx. In the present example, for example, two additional logical channels, a total of 6 logical channels, can be transported over the available physical channels. This would correspond to an expansion of the resources by 50% without, as in Fig. 1 described additional frequency resources.

[0050] Further training levels are conceivable, and the efficient reuse of physical channels in other entities could also take place. List of reference symbols QGN Quasi-synchronous TETRA single-frequency network of the state of the art TBS Tetra state-of-the-art base station SMI synchronization master unit sQGN Embodiment of a quasi-synchronous TETRA single-frequency network of the state of the art sTBS Selective Tetra Base Station sSMI Selective Synchronization Master Unit MS mobile station - terminal BER Bit Error Ratio - bit error rate MER Message Error Rate VER Vector Error Rate - Vector error rate of the modulation quality GSSI Group Short Subscriber Identity - group identification number ISSI Individual Short Subscriber Identity - Individual Identification Number MCCH Main Control Channel TCH Traffic Channel - Traffic Channel CCH Control Channel L1, L2, L3, L4 Logical channel P1, P3, P3, P4 Physical Channel MM Mobility Management - Radio Cell Change Control RRE Re-Registration CC Cell / Colour Code - radio cell information CA Cell Area / Effective area of ​​a base station RC communication signals BS-MI-CC Communication link between TBS and SMI

Claims

[1] Quasi-synchronous TETRA single-frequency network (sQGN) comprising at least two or more base stations (sTBS) with disjoint or at least partially overlapping radio cells (CA), wherein the base stations (sTBS) are interconnected for synchronous or quasi-synchronous single-frequency radiation in the TETRA standard of communication signals (RC) to at least one mobile station (MS), wherein a selective single-frequency radiation of communication signals (RC) can be controlled by a base station (sTBS) on the basis of a reception criterion of the mobile station (MS) with respect to the base stations (sTBS), characterized by that a single-frequency radiation of a communication signal (RC) by the base stations (sTBS) to the mobile station (MS) can be controlled on the basis of the reception criterion within the base stations (sTBS). [2] TETRA single frequency network (sQGN) according to claim 1, characterized bythat the base stations (sTBS) are connected to at least one synchronization master unit (sSMI) via communication links (BS-MI-CC), wherein a selective forwarding of communication signals (RC) can preferably also be controlled by the synchronization master unit (sSMI). [3] TETRA single frequency network (sQGN) according to one of the preceding claims, characterized by that the reception criterion comprises a reception field strength, a bit error rate (BER), a message error rate (MER), a vector error rate (VER), a registration or deregistration (RRE) of the mobile station (MS) when dialing into the base stations (sTBS), location data of the mobile station (MS), in particular WLAN / GPS / mobile radio location data or radio beacon data, and / or predicted movement data of a mobile station (MS) and / or a frequency signature of a mobile station (MS). [4] TETRA single frequency network (sQGN) according to claim 2, characterized bythat the synchronization master unit (sSMI) is configured to synchronize the modulation, carrier frequency, and / or phase data of selectable base stations (sTBS) in order to provide uniform or selective single-frequency radiation [5] Method for operating a quasi-synchronous TETRA single-frequency network (sQGN) according to one of the preceding claims, wherein single-frequency radiation of communication signals (RC) to a mobile station (MS) is carried out selectively via at least one base station (sTBS) on the basis of a reception criterion, characterized by that at least one, preferably all base stations (sTBS) decide on the selective single-frequency radiation of the communication signal (RC) on the basis of a reception criterion. [6] Method according to claim 5, characterized bythat a synchronization master unit (sSMI), which is connected via communication links (BS-MI-CC) to at least two, in particular all, base stations (sTBS), also decides on a selective common frequency radiation of the communication signal (RC) of a base station (sTBS) on the basis of a reception criterion and preferably controls a selective forwarding of communication signals (RC) via the communication link (BS-MI-CC) to the base stations (sTBS). [7] Method according to claim 6, characterized bythat the synchronization master unit (sSMI) also decides on a selective single-frequency radiation of the communication signal (RC) of a base station (sTBS) on the basis of a registration or deregistration (RRE) of a mobile station (MS), a reception field strength, a bit error rate (BER), a message error rate (MER), a vector error rate (VER), location data of the mobile station (MS), in particular WLAN / GPS / mobile radio location data or radio beacon data, and / or predicted movement data of a mobile station (MS), and / or a frequency signature of a mobile station (MS). [8] Method according to one of claims 6 or 7, characterized by that the synchronization master unit (sSMI) synchronizes the modulation, carrier frequency, and / or phase data of selectable base stations (sTBS) in order to provide uniform or selective single-frequency radiation [9] Method according to one of claims 6 to 8, characterized bythat the synchronization master unit (sSMI) and / or the base stations (TBS) decide on selective single-frequency transmission based on an individual identification number (ISSI) and / or a group identification number (GSSI) of a mobile station (MS). [10] Method according to one of claims 6 to 9, characterized by that the synchronization master unit (sSMI) and / or the base stations (TBS) request a re-registration (RRE) of the mobile stations (MS) at least on the basis of an update rate and / or information of the control channel (CCH).

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