Method for the location-selective transmission of a signal by radio, method for the location-selective reception of a signal by radio, and transmission / reception unit for carrying out such a method

Description

[0001] The present invention relates to a method for location-selective transmission and reception of a signal by means of radio and a corresponding system for location-selective transmission and reception of a signal by means of radio. State of the art

[0002] Mobile network-based geocast services are known in the prior art. At the application level, a decision is made based on the subscriber's location as to whether a message is relevant to that subscriber. If the geocast service message is intended for subscribers in a specified region where the subscriber is located, the message is delivered to that subscriber. However, if the subscriber is not located in the specified region, the message is not delivered. In both cases, the message is still transmitted to the subscriber.

[0003] US 2003 / 0153288 A1 discloses that a receiver provides individual users with selected information. A high-speed digital program signal is broadcast and contains program data that begins at a reference time and is repeated at specified intervals. An index signal, containing the receiver's identifier along with the reference time and interval information, is also transmitted. The receiver monitors the index signal for its identifier. When the receiver recognizes its identifier, it downloads the timing and tuning information. The receiver then uses this timing and tuning information to receive, download, and store the program selected by the user. In some embodiments, a transceiver replaces the receiver to allow the user to make remote program requests.

[0004] WO 2008 / 147085 A2 discloses a local advertising-based e-commerce method and system. The local advertising-based e-commerce system comprises local systems installed separately at predefined locations and configured to display advertising content, as well as a system server configured to provide advertising information to the local systems. In response to an advertising request, the system server sets one or more local information points, taking into account areas based on the location of a business that requested the advertisement. For each local information point, the system server sets one or more local systems through which the advertisement is to be displayed and applies a varying number of exposures of the advertisement by the local systems to the respective local information points. Disclosure of the invention

[0005] The present invention relates to a method for location-selective transmission and reception of a signal according to claim 1 and a corresponding system for location-selective transmission and reception of a signal according to claim 7.

[0006] The method disclosed below serves for the location-selective transmission and reception of a signal using radio technology. In radio technology, signals of all kinds are transmitted wirelessly using modulated electromagnetic waves via radio waves. Radio technology includes, among other things, mobile communications and broadcasting.

[0007] Preferably, a receiver is understood to be a non-stationary receiver, for example a mobile phone or a mobile phone receiver installed in a motor vehicle. However, the receiver can also be stationary.

[0008] The term "transmitter" preferably refers to a fixed mobile phone transmitter. However, the transmitter can also be mobile.

[0009] The method of location-selective transmission and reception can be used, for example, in a geocast system. Here, the sender selectively transmits specific information only to receivers located within a predefined geographical area. This predefined geographical area can be a region or territory. Preferably, the region or territory is contiguous. Another application is the location-selective addressing of sensors, whether stationary or mobile. The specific information that the sender selectively transmits to the aforementioned receivers can be information that is particularly relevant to the receivers located within the predefined geographical area. This could include, for example, weather information or traffic information for the predefined geographical area.

[0010] In this sending and receiving method, both the sender and receiver are synchronized to the same time reference. This can be achieved, for example, through a multitude of periodically repeating points in time. However, these predetermined points in time do not necessarily have to repeat periodically. It is sufficient that the predetermined points in time are known to both the sender and the receiver.

[0011] In the sending and receiving procedure, the receiver receives a signal sent by the sender at one of the specified times and demodulates it if the receiver has received the signal at one of the specified times.

[0012] There is a time window within which the receiver can receive the signal. This time window depends primarily on the structure of the transmitted signal. An example of this is the cyclic prefix extension of an OFDM symbol, which allows the OFDM symbol to be demodulated at the receiver even with certain time shifts.

[0013] In the first step of the location-selective transmission and reception process, the transmitter determines a receiving location where the receiver is situated and to which it intends to selectively transmit the signal. This receiving location lies within an annular receiving zone. The position of the receiving zone depends on the transmitter's position and the signal propagation time. Since there is a time window within which the receiver can receive the signal, the receiving zone typically has an annular shape. If the transmitter sends the signal in a certain preferred direction, the receiving zone will have a segmented annular shape. The width of the receiving zone, i.e., its radial extent, depends on the structure of the transmitted signal.

[0014] In a second step of the process, the transmitter modifies the radial extent of the annular receiving zone by selecting a signal structure and then transmits the signal. The transmitter sends the signal at a time prior to the previously known reception time, which is a predetermined point in the time reference. The time difference between the transmission and reception times corresponds to the signal propagation time from the transmitter to the receiver, ensuring that the transmitted signal arrives at the receiver at the previously known reception time. Transmission can be isotropic (direction-independent) or direction-dependent. Direction-dependent transmission can be achieved through beamforming or directional antennas.

[0015] In a third step of the process, the receiver, which is located within the ring-shaped receiving zone with the modified radial extent, receives and demodulates the signal.

[0016] The method of location-selective transmission and reception of a signal via radio advantageously makes it possible for a transmitter to selectively send a signal to a receiver located within the reception area.

[0017] According to a preferred embodiment of the method for location-selective transmission and reception, the receiving location within the receiving zone can be determined with an accuracy between 300 m and 2 m. It is further preferred that the accuracy be between 300 m and 1 cm. This has the advantage that the position of a desired receiver is known to the aforementioned accuracy.

[0018] According to a preferred embodiment, the signal is transmitted by the transmitter in such a way that only a receiver located within the reception zone can receive the signal. According to a further preferred embodiment, the signal is transmitted by the transmitter, in particular by selecting the timing, in such a way that, without further synchronization, only a receiver located within the reception zone can receive the signal. According to a further preferred embodiment, the reason why, without further synchronization, only a receiver located within the reception zone can receive the signal is that the signal transmitted by the transmitter is modulated in such a way that only a receiver located within the reception zone can meaningfully demodulate the transmitted signal.In this context, "meaningful demodulation" means that the demodulated signal can be further processed within the scope of the respective application. This has the advantage that receivers who are not intended to receive the signal know, even after demodulation, whether the signal is meant for them.

[0019] Ensuring that only a receiver located within the reception area can receive the signal without further signal synchronization can preferably be achieved by selecting a suitable transmission method, such as spreading or multicarrier transmission with cyclic prefix modulation. In this context, excessively short or long signal propagation delays lead to non-functional demodulation, which is discarded by error correction mechanisms in the physical transmission layer.

[0020] According to another preferred embodiment, the transmitter uses a CAZAC function or a CAZAC sequence to modulate the mobile communication signal as part of a spreading method, and the receiver uses a corresponding demodulation.

[0021] A CAZAC function or CAZAC sequence is a complex-valued mathematical sequence or function that has a constant amplitude and whose autocorrelation is zero.

[0022] For the propagation of an electromagnetic signal, this has the advantage that even with multipath propagation no interference occurs, since the ZC sequences arriving at the receiver with a delay are orthogonal to each other.

[0023] For spreading methods, the CAZAC sequence is preferred, a Zadoff-Chu sequence (ZC sequence). The complex value at each position n of each Zadoff-Chu sequence with parameter u is given by: x u n = e − i π ⋅ u ⋅ n n + 1 + 2 ⋅ q N ZC , with 0 ≤ n < N ZC , 0 < u < N ZC und ggT N ZC u = 1 , q ∈ ℤ , where N ZC represents the length of the Zadoff-Chu sequence. The abbreviation GCD stands for the greatest common divisor of the two integer values ​​given in parentheses.

[0024] A CAZAC sequence can be used both in the selective transmission process and in the signal reception process.

[0025] Using a CAZAC sequence has the advantage that it can be easily generated and that demodulation does not contribute to reception in the event of a time shift corresponding to reception outside the reception area, due to the property of vanishing autocorrelation. This makes it clear to the receiver that the message is not intended for them and avoids potential interference with other signals.

[0026] Preferably, sending and / or receiving takes place at the physical layer. The physical layer is layer 1 in the OSI reference model. It defines the electronic, functional, and procedural parameters and tools for the physical connection between devices on a network. The most important function of the physical layer is to maintain a physical connection. This includes defining the structure of the bits, the meaning of the bits, and the methods for transmitting individual bits. The standards relevant for PC LANs also include the transmission medium, data connectors, amplifier levels, etc. The OSI model (Open Systems Interconnection Model) is a reference model for network protocols as a layered architecture. It is published as a standard by the International Telecommunication Union (ITU) and the International Organization for Standardization (ISO).Compared to embodiments where a decision is made at the application level as to where the signal is sent or from where the signal is received, the present feature has the advantage that the signal can be processed much faster, since the effort required to process each incoming signal through the entire communication protocol stack is eliminated.

[0027] According to a preferred embodiment, the transmitter sends the signal in a predetermined direction, or the receiver receives the signal from a predetermined direction. This output configuration can be implemented using beamforming or directional antennas. This configuration has the advantage of further increasing the selectivity of transmission or reception.

[0028] Ideally, both the transmitter and receiver are synchronized to the same time reference using the Global Positioning System (GPS). The GPS has the advantage of being available almost everywhere and representing a widely used standard.

[0029] According to a preferred embodiment, the radial extent of the annular receiving zone from the transmitter can be increased by selecting a specific signal structure. For example, the width of the receiving zone can be changed by selecting a longer cyclic prefix. A longer cyclic prefix allows the symbol to be effectively demodulated with a larger absolute time shift. This is particularly relevant for OFDM-based systems. This feature advantageously enables the signal to be transmitted to more receivers with location selectivity.

[0030] According to another embodiment, the width of the annular receiving zone can be increased by additional synchronization at the receiver. This, in addition to the common time reference, increases the receiving area at the receiver independently of the transmitter. This has the advantage that the signal can be sent to multiple receivers. Furthermore, it has the advantage that the signal can be received by multiple receivers.

[0031] The preferred method is location-selective sending and receiving in a geocast system. This has the advantage that messages sent via the geocast system, such as regional information on traffic, roads, etc., can only be sent to the intended recipients and / or received by the intended senders. Brief description of the drawings

[0032] Exemplary embodiments of the invention are shown in the drawings and are explained in more detail in the following description. Figure 1 shows a flowchart of a method for location-selective transmission of a signal by means of radio according to one embodiment. Figure 2 illustrates a spatial relationship between sender and receiver of a method for location-selective transmission according to one embodiment. Figure 3 Figure 1 shows a flowchart of a method for location-selective reception of a signal by means of radio according to one embodiment. Figure 4 illustrates a spatial relationship between sender and receiver of a method for location-selective reception according to one embodiment. Exemplary embodiments of the invention

[0033] Figure 1 shows a method 100 for location-selective transmission of a signal by means of radio.

[0034] In the first step 120 of the procedure 100, both a transmitter and a receiver are synchronized to the same time reference by the Global Positioning System.

[0035] In a second step 130 of the procedure 100, the receiver receives and demodulates a signal sent by the sender at the specified times of the time reference, if the receiver has received the signal at one of the specified times.

[0036] In a third step 140 of the procedure 100, the transmitter determines a receiving location within a receiving zone to which it intends to selectively send the signal. The position of the receiving zone depends on the position of the transmitter and the signal propagation time.

[0037] In this process, the width of the annular reception zone is increased by selecting a longer cyclic prefix from the transmitter. Furthermore, the width of the annular reception zone is increased by additional synchronization at the receiver.

[0038] In a fourth step (150) of the procedure (100), the transmitter sends the signal. The signal is transmitted in such a way that only a receiver located within the reception area can meaningfully demodulate it. This can be achieved, among other methods, using OFDM or a suitable spreading technique. For example, the transmitter uses a CAZAC sequence to modulate the mobile signal, and the receiver uses a corresponding demodulation technique.

[0039] The location-selective transmission of the output form of the Figure 1 is used in a geocast system.

[0040] In a fifth step 160 of procedure 100, the receiver, which is located within the reception zone, receives and demodulates the signal. The receiver can extend the reception zone independently of the transmitter through additional synchronization.

[0041] In the embodiment of the Figure 1 Sending and receiving takes place at the physical layer level.

[0042] Figure 2 illustrates a spatial relationship between sender and receiver of a method for location-selective transmission.

[0043] Figure 2Figure 1 shows a stationary transmitter 200 that wants to send a signal to a desired receiver 210 located in the reception zone 220. The desired receiver 210 is located in a motor vehicle. The distance between the transmitter 200 and the desired receiver 210 is L. The distance L corresponds to a specific travel time between the transmitter 200 and the desired receiver 210.

[0044] The signal is transmitted by transmitter 200 in such a way that only the intended receiver 210, located within reception zone 220, can meaningfully demodulate the signal. An unwanted receiver 230, located outside reception zone 220, cannot meaningfully demodulate the signal. The unwanted receiver 230 is also located in a motor vehicle.

[0045] Figure 3 Figure 110 shows a method for location-selective reception of a signal using radio.

[0046] In a first step 120 of the procedure 110, both a transmitter and a receiver are synchronized to the same time reference by the Global Positioning System.

[0047] In a third step 170 of the procedure 110, the transmitter sends a signal at predetermined times of the time reference. The transmitter uses a CAZAC sequence to modulate the radio signal, and the receiver performs a corresponding demodulation.

[0048] In a fourth step 180 of the procedure 110, the receiver determines a transmission location within a transmission zone from which it wants to selectively receive the signal. The position of the transmission zone depends on the position of the receiver and the signal propagation time.

[0049] In a fifth step 190 of the procedure 110, the receiver receives a signal sent by the transmitter at the selected reception time, which consists of the transmission time and the signal travel time, whereupon the receiver demodulates the signal if detection is successful.

[0050] In the embodiment of the Figure 3 Sending and receiving takes place at the physical layer level.

[0051] The location-selective reception of the embodiment of Figure 3 is used in a geocast system.

[0052] Figure 4 illustrates a spatial relationship between sender and receiver of a method for location-selective reception.

[0053] Figure 4Figure 1 shows a non-stationary receiver 240 located in a motor vehicle. The non-stationary receiver 240 intends to receive a signal from a desired transmitter 250, which is located in the transmission zone 260. The distance between the desired transmitter 250 and the receiver 240 is L. The distance L corresponds to a specific propagation delay between the desired transmitter 250 and the receiver 240. Since the transmitter sends a signal at predetermined times in the time reference and the transmission zone 260 of the desired transmitter 250 is known, the receiver 240 can calculate at which times it can expect a signal. If it also knows the transmission time, it can calculate the distance from which the transmitter sent the signal to it.

[0054] The position of transmission zone 260 depends on the position of receiver 240 and the signal's travel time. Receiver 240 waits for a signal sent by a transmitter at the times mentioned above. If receiver 240 detects a signal that it can meaningfully demodulate, it receives and demodulates the signal.

[0055] No messages are received from the unwanted transmitters 270, which are located outside the transmission zone 260, because the corresponding transit times generally do not correspond to the expected transit time.

Claims

1. Method (100) for the location-selective sending and receiving of a signal by radio, wherein both a transmitter (200) and a receiver (210) are synchronized to the same time reference (120), and, at a time from predetermined times of the time reference, the receiver (210) receives and demodulates a signal sent by the transmitter (200) if the receiver (210) has received the signal at a time among the predetermined times (130); having the following steps: the transmitter (200) determines a receiving location at which the receiver (210) is located and to which it wants to selectively send the signal (140), the receiving location being located within an annular receiving zone (220), a position of the annular receiving zone (220) being dependent on a position of the transmitter (200) and a signal propagation time, the transmitter (200) alters a radial extent of the annular receiving zone (220) by selecting the signal structure, the transmitter (200) sends the signal (150); and the receiver (210), which is located within the annular receiving zone (220) with the altered radial extent, receives and demodulates the signal (160).

2. Method according to Claim 1, characterized in that the signal is sent by the transmitter (200) in such a way that only a receiver (210) that is located within the annular receiving zone (220) can usefully demodulate the signal.

3. Method according to either of the preceding claims, characterized in that the transmitter uses a CAZAC function or a CAZAC sequence to modulate the radio signal and the receiver (210, 240) uses a corresponding demodulation.

4. Method according to one of the preceding claims, characterized in that the sending and receiving takes place at the level of the physical layer.

5. Method according to one of the preceding claims, characterized in that the transmitter (200, 250) and the receiver (210, 240) are synchronized to the same time reference by the Global Positioning System.

6. Method according to one of the preceding claims, characterized in that the location-selective sending and / or receiving is used in a geocast system.

7. System for the location-selective sending and receiving of a signal by radio comprising a transmitter (200) and a receiver (210), wherein both the transmitter (200) and the receiver (210) are synchronized to the same time reference (120), the receiver (210) is configured so as, at a time from predetermined times of the time reference, to receive and demodulate a signal sent by the transmitter (200) if the receiver (210) has received the signal at a time among the predetermined times; the transmitter (200) is configured so as to determine a receiving location at which the receiver (210) is located and to which it wants to selectively send the signal (140), the receiving location being located within an annular receiving zone (220), a position of the annular receiving zone (220) being dependent on a position of the transmitter (200) and a signal propagation time, so as to alter a radial extent of the annular receiving zone (220) by selecting the signal structure, and so as to send the signal; the receiver (210), which is located within the annular receiving zone (220) with the altered radial extent, is configured so as to receive and demodulate the signal.