Method for the locationally selective transmission of a signal by radio, method for the locationally selective reception of a signal by radio, and transmitter/receiver unit for carrying out such a method

Abstract

A method is described for the locationally selective transmission of a signal by radio. Both a transmitter and a receiver are synchronized to the same time reference. The receiver receiving and demodulating, at a time that is one of the specified times of the time reference, a signal transmitted by the transmitter, if the receiver has received the signal at a time that is one of the specified times. The method includes the transmitter determining a receive location within a receive zone to which it wishes to transmit the signal in selective fashion, a position in the receive zone being a function of a position of the transmitter and a signal runtime. The method also includes the transmitter transmitting the signal; and the receiver, which is situated inside the receive zone, receives and demodulates the signal.

Claims

1. A method for a locationally selective reception of a signal by radio, both a transmitter and a receiver being synchronized to the same time reference, and the transmitter transmitting the signal at a time that is one of the specified times of the time reference, the method comprising the following steps: determining, by the receiver, a transmit location within a transmit zone from which the receiver is to selectively receive the signal, a position in the transmit zone being a function of a position of the receiver and a signal runtime, wherein the transmit zone is annular; and during a receive time period, receiving and demodulating, by the receiver, the signal transmitted by the transmitter, wherein a width of the transmit zone is a function of a signal structure of the signal.

2. The method as recited in claim 1, wherein the width of the transmit zone is a function of a length of a cyclic prefix of the signal structure.

3. The method as recited in claim 1, wherein the receiving take places on a level of a physical layer.

4. The method as recited in claim 1, wherein the receiver and transmitter are synchronized to the same time reference by the Global Positioning System.

5. The method as recited in claim 1, wherein the locationally selective reception is used in a geocasting system.

6. The method as recited in claim 1, wherein the receiver demodulates the radio signal as modulated using a CAZAC sequence.

7. The method as recited in claim 1, wherein receiving is independent of direction.

8. The method as recited in claim 1, wherein receiving is directionally dependent.

9. The method as recited in claim 8, wherein directionally dependent receiving is performed through beamforming.

10. The method as recited in claim 8, wherein directionally dependent receiving is performed through using directed antennas.

11. A receiver that is set up to receive a signal in locationally selective fashion, the receiver configured to: determine a transmit location within a transmit zone from which the receiver is to selectively receive the signal, a position in the transmit zone being a function of a position of the receiver and a signal runtime, wherein the transmit zone is annular; and during a receive time period, receive and demodulate a signal transmitted by the transmitter, wherein a width of the transmit zone is a function of a signal structure of the signal.

12. The receiver as recited in claim 11, wherein the width of the transmit zone is a function of a length of a cyclic prefix of the signal structure.

13. The receiver as recited in claim 11, wherein the receiving take places on a level of a physical layer.

14. The receiver as recited in claim 11, wherein the receiver and transmitter are synchronized to the same time reference by the Global Positioning System.

15. A non-transitory machine-readable storage medium on which is stored a computer program for a locationally selective reception of a signal by radio, the computer program, when executed by a computer, causing the computer to perform: determining a transmit location within a transmit zone from which the receiver is to selectively receive the signal, a position in the transmit zone being a function of a position of the receiver and a signal runtime, wherein the transmit zone is annular; and during a receive time period, receiving and demodulating a signal transmitted by the transmitter, wherein a width of the transmit zone is a function of a signal structure of the signal.

16. The non-transitory machine-readable storage medium as recited in claim 15, wherein the width of the transmit zone is a function of a length of a cyclic prefix of the signal structure.

17. The non-transitory machine-readable storage medium as recited in claim 15, wherein the receiving take places on a level of a physical layer.

18. The non-transitory machine-readable storage medium as recited in claim 15, wherein the receiver and transmitter are synchronized to the same time reference by the Global Positioning System.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Exemplary embodiments of the present invention are shown in the figures and are explained in more detail below.

(2) FIG. 1 shows a flow diagram of a method for the locationally selective transmission of the signal by radio according to a specific embodiment.

(3) FIG. 2 illustrates a spatial relationship between the transmitter and receiver of a method for locationally selective transmission according to a specific embodiment.

(4) FIG. 3 shows a flow diagram of a method for locationally selective reception of a signal by radio according to a specific embodiment.

(5) FIG. 4 illustrates a spatial relationship between the transmitter and receiver of a method for locationally selective reception according to a specific embodiment.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

(6) FIG. 1 shows a method 100 for the locationally selective transmission of a signal by radio.

(7) In the first step 120 of method 100, both a transmitter and a receiver are synchronized to the same time reference by the Global Positioning System.

(8) In a second step 130 of method 100, at the specified times of the time reference the receiver receives and demodulates a signal sent by the transmitter, if the transmitter has received the signal at one of the specified times.

(9) In a third step 140 of method 100, the transmitter determines a receive location within a receive zone to which it wishes to selectively transmit the signal. Here, a position in the receive zone is a function of a position of the transmitter and a signal runtime.

(10) Here, a width of the annular receive zone is enlarged by the transmitter through the selection of a length of a cyclic prefix. In addition, the width of the annular receive zone is enlarged by an additional synchronization at the receiver.

(11) In a fourth step 150 of method 100, the transmitter transmits the signal. Here, the signal is transmitted by the transmitter in such a way that only one receiver, situated within the receive zone, can correctly demodulate the signal. This can be brought about, inter alia, by OFDM or a corresponding spreading method. For example, here the transmitter uses a CAZAC sequence for the modulation of the mobile radiotelephone signal, and the receiver uses a corresponding demodulation.

(12) The locationally selective transmission of the initial form of FIG. 1 is used in a geocasting system.

(13) In a fifth step 160 of method 100, the receiver situated within the receive zone receives and demodulates the signal. Here, the receiver can enlarge the receive zone, independently of the transmitter, through an additional synchronization.

(14) In the specific embodiment of FIG. 1, the transmission and reception take place on the level of the physical layer.

(15) FIG. 2 illustrates a spatial relationship between the transmitter and receiver of a method for locationally selective transmission.

(16) FIG. 2 shows a stationary transmitter 200 that wishes to send a signal to a desired receiver 210 situated in receive zone 220. Desired receiver 210 is here situated in a motor vehicle. The distance between transmitter 200 and desired receiver 210 is L. The distance L corresponds to a particular runtime between transmitter 200 and desired receiver 210.

(17) The signal is transmitted by transmitter 200 in such a way that only the desired receiver 210, situated within receive zone 220, can correctly demodulate the signal. An undesired receiver 230, not situated in receive zone 220, cannot correctly demodulate the signal. Undesired receiver 230 is here also situated in a motor vehicle.

(18) FIG. 3 shows a method 110 for the locationally selective reception of a signal by radio.

(19) In a first step 120 of method 110, both a transmitter and a receiver are synchronized to the same time reference by the Global Positioning System.

(20) In a third step 170 of method 110, the transmitter sends a signal at specified times of the time reference. Here, the transmitter uses a CAZAC sequence for the modulation of the radio signal, and the receiver uses a corresponding demodulation.

(21) In a fourth step 180 of method 110, the receiver determines a transmit location within a transmit zone from which it wishes to selectively receive the signal. Here, a position in the transmit zone is a function of a position of the receiver and a signal runtime.

(22) In a fifth step 190 of method 110, the receiver receives a signal sent by the transmitter at the selected receive time, resulting from the transmit time and the signal runtime, whereupon the receiver demodulates the signal when there is a successful detection.

(23) In the specific embodiment of FIG. 3, the transmission and reception take place on the level of the physical layer.

(24) The locationally selective reception of the specific embodiment of FIG. 3 is used in a geocasting system.

(25) FIG. 4 illustrates a spatial relationship between the transmitter and receiver of a method for locationally selective reception.

(26) FIG. 4 shows a nonstationary receiver 240 situated in a motor vehicle. Nonstationary receiver 240 intends to receive a signal from a desired transmitter 250 situated in transmit zone 260. The distance between desired transmitter 250 and receiver 240 is L. The distance L corresponds to a particular runtime between desired transmitter 250 and receiver 240. Because the transmitter transmits a signal at one of the specified times of the time reference, and transmit zone 260 of desired transmitter 250 is known, receiver 240 can calculate the times at which it can expect a signal. If the receiver additionally knows the transmit time, it can calculate the distance from which the transmitter has transmitted the signal to the receiver.

(27) The position of transmit zone 260 is a function of the position of receiver 240 and the runtime of the signal. At the above-named times, receiver 240 waits for a signal transmitted by a transmitter. If receiver 240 has recognized a signal that it can correctly demodulate, then it receives and demodulates the signal.

(28) No messages are received from the undesired transmitters 270 situated outside transmit zone 260, because the corresponding runtimes generally do not correspond to the expected runtime.