초록 ▼

The system for automatic planning of delays in a network (N) of SFN type comprises: means initiating an OFDM transmission for each radio transmitter (4), inter-symbol delays being provided; a calculation module processing network data and determining figures of populations located in zones with i

The system for automatic planning of delays in a network (N) of SFN type comprises: means initiating an OFDM transmission for each radio transmitter (4), inter-symbol delays being provided; a calculation module processing network data and determining figures of populations located in zones with interference; control means and initiation means to delay transmission at each transmitter, with a delay varying between 0 and 1 ms; delay adjustment means linked to the control means for combinations of delays for all transmitters. The module (11) recalculates the figures of populations located in interference zones for successive combinations of delays, and configuration means (13) of the system provide the number of permitted iterations. The optimal combination is obtained when said estimated population figures are minimum.

대표청구항 ▼

The invention claimed is: 1. Method for automatic planning of transmission time delays of different radio transmitters (4) generating radio cells with one single frequency to form a digital television broadcasting wireless network (N) that is time and frequency synchronous, implemented via a comput

The invention claimed is: 1. Method for automatic planning of transmission time delays of different radio transmitters (4) generating radio cells with one single frequency to form a digital television broadcasting wireless network (N) that is time and frequency synchronous, implemented via a computing system (1) comprising memorization means (12) to store data related to the network (N) including data (3) representing geographical areas divided into a plurality of dots or pixels (301, 302, 303) in accordance with the divisions of said network (N) and containing the position of the radio transmitters (4), population data corresponding to the network divisions, data (31) specifying a transmission level of the transmitters and a sensitivity threshold level of radio reception by terminals of the cell (1), data (32) representing a radio propagation attenuation law and data representing a time period of guard intervals (GI) inserted between data frames, the system (1) also comprising a calculation module (11) and means for parametering a plurality of radio transmitters (4), the method comprising for each radio transmitter (4) an initiation step to initiate a transmission at a determined instant, characterized in that it comprises a processing step (500) to process data related to the network (N) using the calculation module (11) to calculate data representing figures of populations located in zones (Br) of disturbing interference and a step (54) to adjust said initiation step performed for each radio transmitter (4) using a transmission delay varying between 0 and a non-zero value less than 1 ms with memorization for each radio transmitter (4) of the delay used, the adjustment step (54) being follower by a reiteration of processing step (500) to re-estimate figures of populations located in zones of disturbing interference, processing step (500) being reiterated with a number of iterations parametered using the configuration means (13) of the system (1), the adjustment step being finalized after the iterations by using a memorized combination of delays for each transmitter in the set of transmitters (4) allowing a minimum figure to be reached of said estimated populations in zones (Br) of disturbing interference. 2. Method as in claim 1, characterized in that processing step (500) to process data related to the network (N) comprises: a determination step (50) to determine radio coverage of the network (N), including processing by the calculation module (11) of geographical map data (3) containing the position of the radio transmitters (4), data (31) specifying a transmission level of the transmitters and a sensitivity threshold level of radio reception by terminals of the cell (1) and data (32) representing a radio propagation attenuation law, to generate data representing coverage maps (CN) of the network (N) which, for each of the transmitters (4), specify field levels of the signals received in each of the pixels (301, 302, 303); for each radio transmitter (4), an estimation step (51) to estimate an effective signal and an interference signal in pixels of the network (N), using a breakdown made by the calculation module (11) of field levels of signals received via the network (N) into an effective component and an interfering component, the calculation module (11) using a weighting function which can be parametered to make said breakdown. 3. Method as in claim 2, wherein step (500) to process data related to the network (N), for each radio transmitter (4), comprises: a step (52) to calculate an interference probability (P1, P2, P3) for each pixel (301, 302, 303), in which a value representing the signal to disturbance ratio is first calculated by the calculation module (11) for each pixel (301, 302, 303) on the basis of estimated signals associated with the respective pixels, said disturbance consisting of intercellular interference and noise related to the width of the channel used by the transmitters (4) of the cell, then the interference probability (P1, P2, P3) in the pixel is deduced from the calculations of said ratio in the pixels by the calculation module (11); and a step (53) to determine a criterion representing a total population located in zones of disturbing interference, said criterion being determined by the calculation module (11) on the basis of interference probabilities (P1, P2, P3) in each pixel and population data corresponding to the divisions of the network. 4. Method as in claim 3, wherein adjustment step (54) to adjust said initiation step is made in a manner determined by the calculation module (11) to reach a minimum sum of said criteria as calculated by integration on all transmitters (4), said minimum resulting in particular from at least one comparison made by comparison means of the calculation module (11) between several separate solutions for adjusting transmission delays within the network (N). 5. Method as in claim 3, wherein the interference probability (P1, P2, P3) in each pixel (301, 302, 303) is deduced from the calculations of said ratio in the pixels of the cell made by comparison means of the calculation module (11), a minimum ratio value being stored in the memorization means (12) and used by the comparison means to determine, for each pixel, whether the minimum ratio is reached and thereby allow the obtaining of interference probability (P1, P2, P3) for the pixel (301, 302, 303). 6. Method as in claim 2, wherein transmissions are made following the T-DAB standard, the weighting coefficient which can be parametered having the form: where: Wi represents the weighting coefficient of the i-th signal; Tu represents the effective period of a symbol; Δ represents the intersymbol delay; and t represents the instant of arrival of the signal compared with a reference instant. 7. Method as in claim 2, wherein transmissions are made following the DVB standard, the weighting coefficient which can be parametered having the form: where: Wi represents the weighting coefficient of the i-th signal; Tu represents the effective period of a symbol; Δ represents the inter-symbol delay; t represents the instant of arrival of the signal compared with a reference instant; and Tp represents the interval of effective contribution of the signal. 8. Method as in claim 1, wherein adjustment step (54) uses values distributed with a pitch of between 1 μs and 45 μs over a range of values whose amplitude remains less than 500 μs. 9. Method as in claim 1, wherein adjustment step (54) uses values distributed with a pitch of between 5 μs and 45 μs over a range of values whose amplitude remains less than 500 μs. 10. Method as in claim 1, wherein the initiation step to initiate a transmission at a determined instant comprises the splitting of a signal received by the transmitter (4) into a plurality of transmission signals on a plurality of sub-carriers in accordance with digital frequency modulation of OFDM type, guard intervals (GI) having a same determined transmission period being inserted between data frames forming OFDM-modulated symbols (S), the transmission period of the guard intervals (GI) being a constant function of the transmission period of a symbol (S). 11. Method as in claim 1, characterized in that it comprises a memorization step to memorize data on traffic density of users of a mobile telephony network to replace population data. 12. Method as in claim 2, wherein step (50) to determine radio coverage comprises a determination step by the calculation module (11), for each pixel (301, 302, 303), to determine a respective distance between each transmitter (4) and the pixel under consideration, followed by a correction step of this distance by the calculation module (11) taking into account the delay parametered for the respective transmitters (4) by the delay adjustment means. 13. System (1) for automatic planning of transmission time delays of different radio transmitters (4) generating radio cells with one same frequency, to form a digital television broadcasting wireless network (N) that is time and frequency synchronous, comprising memorization means (12) for storing data related to the network (N) including data (3) representing geographical areas divided into a plurality of dots or pixels (301, 302, 303) according to the divisions of said network (N) and containing the position of the radio transmitters (4), population data corresponding to the divisions of the network, data (31) specifying a transmission level of the transmitters and a sensitivity threshold level of radio reception by terminals of the cell (1), data (32) representing a radio propagation attenuation law, and data representing a time period of the guard intervals (GI) inserted between data frames, the system (1) also comprising a calculation module (11) and means for parametering a plurality of radio transmitters (4), characterized in that it comprises initiation means for initiating a transmission at a determined instant for each radio transmitter (4), the calculation module (11) by processing data related to the network (N), being arranged for calculating data representing figures of populations located in zones of disturbing interference, said parametering means being able to use delays which are stored in the memorization means (12), control means and initiation means being provided for delaying transmission at each radio transmitter (4), with a delay varying between 0 and a non-zero value less than 1 ms, said delay being memorized for each radio transmitter (4), the delay adjustment means being linked to the control means to provide different combinations of delays for all the transmitters (4), the calculation module (11) being provided with iteration means allowing re-calculation of figures of populations located in zones of disturbing interference for separate delay combinations, the configuration means (13) of the system (1) being linked to the calculation module (11) to provide a number of iterations allowing the deactivation of the iteration means, said control means being able, from among the combinations provided by the delay adjustment means, to use a combination of delays for all the transmitters (4) which corresponds to the obtaining by the calculation module (11) of a minimum figure for said estimated population figures. 14. System (1) as in claim 13, wherein the calculation module (11), to calculate data representing figures of populations located in zones (Br) of disturbing interference, contains: means for determining wireless coverage of the network (N), able to process geographical map data (3) containing the position of the radio transmitters (4), data (31) specifying a transmission level of the transmitters and a sensitivity threshold level of radio reception by terminals of the cell (1) and data (32) representing a radio propagation attenuation law, to generate data representing coverage maps (CN) of the network (N) which, for each of the transmitters (4), specifies field levels of signals received in each of the pixels (301, 302, 303); means for estimating, for each transmitter (4), an effective signal and an interference signal in pixels of the network (N), these estimation means being able to break down field levels of signals received via the network (N) into an effective component and an interferer component, and to use a weighting function parametered using the configuration means (13) to make said breakdown; means for determining, for each radio transmitter (4), an interference probability (P1, P2, P3) for each pixel (301, 302, 303), arranged to calculate a value representing the signal to disturbance ratio for each pixel (301, 302, 303) on the basis of estimated signals associated with the respective pixels provided by the estimation means, said disturbance consisting of intercellular interference and noise related to the width of the channel used by the transmitters (4) of the cell, said determination means calculating interference probability (P1, P2, P3) in the pixel on the basis of calculations of said ratio in the pixels; association means allowing, for each transmitter (4), the determination of a criterion representing the total population located in zones (Br) of disturbing interference, said criterion being determined by association of interference probability (P1, P2, P3) in each pixel (301, 302, 303) with population data corresponding to the divisions of the network (N). 15. System (1) as in claim 14, wherein the calculation module (11) determines the combination of delays to be used by the control means via comparison means of the calculation module (11) which, from among a plurality of sums of criteria respectively corresponding to the different combinations of delays, determine a minimum sum of said criteria calculated by integration on all the transmitters (4). 16. System (1) as in claim 14, wherein the interference probability (P1, P2, P3) in each pixel (301, 302, 303) is deduced from the calculations of said ratio in the pixels of the cell by the comparison means of the calculation module (11), a minimum ratio value being stored in the memorization means (12) and used by the comparison means to determine for each pixel whether the minimum ratio is reached and thereby to allow the obtaining of interference probability for the pixel (301, 302, 303). 17. Network for broadcasting wireless communications containing at least one TV or radio program, characterized in that it consists of a mobile telephony network comprising a plurality of transmitter sites forming respective radio cells (20) together defining a radio coverage, and in that all these sites are equipped with transmitters (4) for the broadcasting of TV or radio and in that they are all parametered with one same UHF frequency to generate a radio cell, the transmitters (4) being arranged to send frames forming an OFDM-modulated symbol (S) with a guard interval (GI) corresponding to a fraction of between one quarter and one sixteenth of the transmission period of a frame, the transmitters (4) being arranged to initiate their respective transmission with a determined shift or delay varying between 0 and a non-zero value less than 1 ms and not exceeding twice the period of the guard interval (GI), said network using a combination of delays adapted so as to minimize the number of zones (Br) of disturbing interference coinciding with populated areas.