A METHOD OF REDUCING POWER CONSUMPTION IN A DIGITAL AUDIO BROADCASTING RECEIVER

Abstract: A method of reducing power consumption in a digital audio broadcasting receiver by only deinterleaving a directory channel to determine if there is any information of interest, and if so, preferably, thereafter determine where the information of interest is.

Description: A method of reducing power consumption in a digital audio broadcasting receiver FIELD OF THE INVENTION The present invention relates generally to a method and a device for lowering the power consumption of radio frequency receiver, especially receivers that can receive digital audio broadcasting (DAB), portable, mobile or stationary. BACKGROUND TO THE INVENTION Digital radio broadcasting (DAB) is a relatively new method of broadcasting radio and information. Primarily it was intended as a new radio broadcasting system to mobile, portable and stationary receivers, and is now also increasing in popularity in data applications. DAB is relatively broadband with a useful transport bit rate of approximately 0.6 to 1.8 Mbit/second in dependence on the specific implementation. Its increased popularity for broadcasting information other than digital sound is probably due to its capacity, relatively low cost for transfer per unit of data, coverage, and the robustness of information transfer. The robustness of information transfer is necessary for it to be useful for information transfer in a simplex system without a feedback channel. The robustness is at least in part due to time and frequency interleaving of a main service channel (MSC) where the information is transferred. Its increasing popularity has led to a desire to make DAB receivers more portable and mobile. There is a desire to be able to use DAB receivers in conjunction with handheld and laptop computers. Handheld and laptop computers are low power consumers to be able to offer long operating times with battery usage only. Peripherals connected to or integrated into handheld and laptop computers therefore need to be low power consumers. A standard DAB receiver is not optimized for low power consumption. There is thus a need to lower the power consumption of DAB receivers. SUMMARY OF THE INVENTION An object of the invention is to define a method for reducing the power consumption of a DAB receiver. Another object of the invention is to define a DAB receiver with low power consumption. The aforementioned objects are achieved according to the invention by a method of reducing power consumption in a digital audio broadcasting receiver, and a receiver carrying out the method, by only deinterleaving desired information. The desired information can advantageously be a directory channel to help determine if there is any information of interest, and if so, preferably, thereafter determine where the information of interest is. Preferably the directory channel and the information of interest is only deinterleaved if the directory channel or the information of interest has not previously been deinterleaved, i.e. is available deinterleaved already. The aforementioned objects are also achieved according to the invention by a method of reducing power consumption in a digital audio broadcasting receiver when receiving a radio frequency signal including information entities. According to the invention the method comprises a number of steps in the digital audio broadcasting receiver. In a first step receiving the radio frequency signal including the information entities in frames, which frames comprise at least one main service channel. In a second step only deinterleaving a directory channel comprising a directory of what entities of information is included in the at least one main service channel. In a third step determining from the directory if there is any information of interest among the information entities in a main service channel of the at least one main service channel. In a fourth step only deinterleaving a part of the main service channel that includes the information of interest if it is determined that there is information of interest. In a fifth step making the deinterleaved information of interest available in the receiver. Thus the amount of deinterleaving in the digital audio broadcasting receiver is reduced thereby enabling a reduced average power consumption of the digital audio broadcasting receiver in comparison with a digital audio broadcasting receiver which continuously deinterleaves. In one version of the method the step of determining from the directory if there is any information of interest comprises two substeps. A first substep of presenting the directory to a requester. A second substep of determining that there is information of interest in a main service channel of the at least one main service channel if a selection of an information of interest out of the directory is received from the requester. In some versions of the method the directory channel is a sub channel in the main service channel and in other versions the directory channel is comprised in a fast information channel. Advantageously the directory channel comprises at least one descriptor of at least one information entity, each descriptor being associated with a corresponding information entity by means of a link to the information entity. One or more of the features of the above-described different methods according to the invention can be combined in any desired manner, as long as the features are not contradictory. The aforementioned objects are achieved in accordance with the invention also by a digital audio broadcasting receiver with reduced power consumption when receiving a signal including information entities. The receiver comprises a number of means arranged to carry out the invention. A first means is arranged to receive a radio frequency signal including the information entities in frames, which frames comprises a main service channel. A second means is arranged to control a deinterleaver means to only deinterleave a directory channel comprising a directory of what information entities are included in the at least one service channel. A third means is arranged to determine from the directory if there is any information of interest in a main service channel of the at least one main service channel. A fourth means is arranged to control a deinterleaver means to only deinterleave the parts of the main service channel that includes the information of interest if it was determined that there is information of interest. A fifth means is arranged to make the deinterleaved information of interest available in the receiver. Thus the amount of deinterleaving in the digital audio broadcasting receiver is reduced thereby enabling a reduced average power consumption of the digital audio broadcasting receiver. Different embodiments of the receiver according to the invention can be reached according to additional features mentioned above in connection with the description of the method according to the invention. The features of the above-described different embodiments of a device according to the invention can be combined in any desired manner, as long as no conflict occurs. The aforementioned objects are also achieved according to the invention by a method of reducing power consumption in a digital audio broadcasting receiver when receiving a radio frequency signal including information entities. According to the invention the method comprises a number of steps in the digital audio broadcasting receiver. In a first step receiving a radio frequency signal including the information entities in frames, which frames comprise at least one main service channel. In a second step only deinterleaving desired information entities. In a third step making the deinterleaved information entities available in the receiver. Thus reducing the amount of deinterleaving in the digital audio broadcasting receiver thereby enabling a reduced average power consumption of the digital audio broadcasting receiver. Advantageously the step of deinterleaving desired information entities is only executed if the desired information is not already deinterleaved and available in the receiver. The aforementioned objects are also achieved according to the invention by a method of reducing power consumption in a digital audio broadcasting receiver when receiving a signal including information of interest. According to the invention the method comprises a number of steps in the digital audio broadcasting receiver. In a first step receiving a radio frequency signal including the information of interest in frames, which frames comprises a main service channel. In a second step determining if the information of interest is available in the receiver. In a third step only deinterleaving the parts of the main service channel that includes the information of interest if it was determined that the information of interest is not available in the receiver. In a fourth step making the deinterleaved information of interest available in the receiver. Thus the amount of deinterleaving in the digital audio broadcasting receiver is reduced thereby enabling a reduced average power consumption of the digital audio broadcasting receiver. In one version of the method the step of determining if the information of interest is available in the receiver, comprises substeps. A first substep of decoding a fast information channel comprised in the frame to retrieve directory information. A second substep of comparing the directory information in the fast information channel of what information of interest the main service channel includes with what information is available in the receiver, and if the information of interest included in the main service channel is available in the receiver then determining that the information of interest is available in the receiver. Preferably the method comprises the step of broadcasting directory information in the fast information channel, in a digital audio broadcasting transmitter broadcasting the signal including information of interest. In another version of the method the step of determining if the information of interest is available in the receiver, comprises other substeps. A first other substep of deinterleaving a directory channel in the main service channel to retrieve directory information. A second other substep of comparing the directory information in the directory channel of what information of interest the main service channel includes with what information is available in the receiver, and if the information of interest included in the main service channel is available in the receiver then determining that the information of interest is available in the receiver. Preferably the method comprises the step of broadcasting directory information in the directory channel in the main service channel, in a digital audio broadcasting transmitter broadcasting the signal including information of interest. Advantageously the directory channel is a dedicated sub-channel in the main service channel. Preferably the information of interest is broadcasted in entities of data files or data carousels, where each unique data file or unique data carousel is assigned a specific version number, the version number being used to determine if the information of interest is available in the receiver. One or more of the features of the above-described different methods according to the invention can be combined in any desired manner, as long as the features are not contradictory. The aforementioned objects are achieved in accordance with the invention also by a digital audio broadcasting receiver with reduced power consumption when receiving a signal including information of interest. The receiver comprises a number of means arranged to carry out the invention. A first means is arranged to receive a radio frequency signal including the information of interest in frames, which frames comprises a main service channel. A second means is arranged to determine if the information of interest is available in the receiver. A third means is arranged to control a deinterleaver means to only deinterleave the parts of the main service channel that includes the information of interest if it was determined that the information of interest is not available in the receiver. A fourth means is arranged to make the deinterleaved information of interest available in the receiver. Thus the amount of deinterleaving in the digital audio broadcasting receiver is reduced thereby enabling a reduced average power consumption of the digital audio broadcasting receiver. Different embodiments of the receiver according to the invention can be reached according to additional features mentioned above in connection with the description of the method according to the invention. The features of the above-described different embodiments of a device according to the invention can be combined in any desired manner, as long as no conflict occurs. The aforementioned objects are also achieved according to the invention by a method of reducing power consumption in a digital audio broadcasting receiver when receiving a signal including information of interest broadcasted by a digital audio broadcasting transmitter. The method comprises a number of steps in the digital audio broadcasting transmitter. A first step assigning an identity to an entity of the information of interest, each identical entity of the information of interest being assigned an identical identity. A second step broadcasting the identity of an entity of the information of interest. A third step broadcasting the entity of the information of interest. Thereby enabling the digital audio broadcasting receiver to reduce the amount of deinterleaving enabling a reduced average power consumption of the digital audio broadcasting receiver, by only deinterleaving information of interest with assigned identities which have not been previously received. Preferably an entity of the information of interest is a data file or a data carousel. Advantageously the assigned identities are version numbers. In some versions the assigned identities are broadcasted in a fast information channel. In other versions the assigned identities are broadcasted in a subchannel comprised in a master service channel. By providing a method for lowering the power consumption of DAB receivers and by providing a DAB receiver with low power consumption, the range of possible applications for the use of digital audio broadcasting increases. Especially the use of DAB as an information transfer medium increases by enabling the use of DAB receivers in truly portable and mobile situations where low power consumption is essential. DESCRIPTION OF THE FIGURES The invention will now be described in more detail for explanatory, and in no sense limiting, purposes, with reference to the following figures, in which Fig. 1 shows a block diagram of one DAB frame, Fig. 2 shows a block diagram of a digital audio broadcasting (DAB) transmitter, Fig. 3 shows a block diagram of a digital audio broadcasting (DAB) receiver, Fig. 4 shows a flow chart of a basic method of reducing power consumption in a digital audio broadcasting receiver according to the invention, Fig. 5 shows a flow chart of an enhancement of the method according to the invention, Fig. 6 shows a flow chart of a specific method according to the invention, Fig. 7 shows a time diagram of a DAB data carousel transmission and reception according to the invention, and Fig. 8 shows a time diagram of a DAB data file transmission and reception according to the invention. DESCRIPTION OF PREFERRED EMBODIMENTS In order to clarify the system according to the invention, some examples of its use will now be described in connection with Figures 1 to 8. Figure 1 shows a block diagram of one DAB frame, which is provided for a deeper understanding of the DAB system. DAB frames are sent in succession. A DAB frame mainly comprises a synchronization channel 101, 102, a fast information channel (FIC) 103, and a main service channel (MSC) 104. The synchronization channel 101, 102 comprises a null symbol 101 and at least one phase reference symbol 102. The fast information channel (FIC) 103 is, for example, used for multiplex configuration information (MCI) and service information (SI). The main service channel 104 carries the desired useful information, which can be a number of coded audio programs/channels, one or more digital information transfers, or a combination of these. Usually more than one program/channel or information transfer is coded into the main service channel. A DAB frame is configured to provide a robust way of transferring information, i.e. packets of digital information, from a transmitter to a receiver without any feedback through, for example, a back channel. Figure 2 shows a block diagram of a digital audio broadcasting (DAB) transmitter 200. DAB frames, which make up a DAB signal, are assembled in the transmitter before transmission/broadcasting. Packets of digital information 201, 203, such as sound services 201 and data services 203, are first coded 210, 211, 212, 213, error protected, and then time interleaved 214, 215. These are thereafter multiplexed 220, 222 into the main service channel together with other optional services 202, 204, according to a predetermined, but changeable, service configuration 205. The multiplexer output is frequency interleaved 226 and combined with multiplex control and service information 205 which travel in the fast information channel 224 in order to avoid the time interleaving process. Finally, very rugged synchronization symbols are added before applying orthogonal frequency division multiplexing (OFDM) 228, 230 and differential quadrature phase-shift keying (QPSK) modulation onto a large number of carriers to form the DAB signal 209. Figure 3 shows a block diagram of a digital audio broadcasting receiver 300. The receiver 300 comprises an antenna 302, a tuner 304, an analog to digital converter process 306, an information path 308 that runs the desired information through the receiver 300, a Fast Frequency Transform (FFT) and differential demodulation stage 312, a time and frequency deinterleaver and error corrector processes 314, optionally an audio decoder process 322, optionally one or more speaker(s) 324, a data decoder process 332, one or more connections of data information to data services 334, a user interface 342, a controller and synchronizer 344, and a data/control buss 346. Most of the functionality of a digital audio broadcasting receiver 300 is usually performed in one or more digital processors such as digital signal processors. A digital audio broadcasting receiver might just as well be implemented with discrete hardware blocks or anything in between, for example the tuner 304 and analog to digital converter 306 are with current technology preferably implemented as discrete hardware. A via the antenna 302 received signal is selected, down-converted and quadrature demodulated in the tuner 304 before applying it to the analog to digital converter 306. Thereafter, the receiver performs FFT and differential demodulation 312 followed by time and frequency de-interleaving and error correction 314 to output the original coded services data. The deinterleaved data can then be either put into an audio decoder 322 for sound reproduction through one or more speakers 324 or be put into a data decoder 332 for the sending desired data 334 to other processes or devices. The controller and synchronizer 344 will ensure that data flows correctly through the receiver according to inputs and indication to the user interface 342, which might be a panel or another computer or process. During attempts to reduce the power consumption of DAB receivers it was discovered that the major power consumption in a DAB receiver is the de- interleaving and error correction 314 of the main service channel (MSC), which is where information of interest is. It has also been discovered that the power consumption is directly related to how much of the MSC that is actually deinterleaved, thus according to the invention only desired parts of the MSC are deinterleaved instead of routinely just deinterleaving the whole MSC to first thereafter pick out the parts that are of interest. According to the invention deinterleaving is kept to a minimum. According to an enhancement of the invention power reduction is optimized by a two step process, each step only deinterleaving an absolute minimum of the MSC. Firstly only a directory channel of the MSC, or in some special cases the FIC, is deinterleaved to determine what information is in the current MSC and possibly future MSCs. This first step then either autonomously or by user intervention, determines if any of the information is information of interest. If there is information of interest, then secondly the information of interest is deinterleaved. An enhancement of the method will then continuously keep track of any updates of the information of interest by means of deinterleaving only the directory channel or the FIC and only deinterleave the relevant parts of the MSC when there is an update of the information of interest. So by not continuously deinterleaving the complete MSC, it has been experimentally tested that it is possible to achieve a substantial power reduction. A first problem is therefor to determine what information is in the MSC, and decide if any of the information is information of interest. According to the invention, to avoid having to continuoulsy deinterleave the complete MSC, a directory channel or possibly in some cases the FIC, comprises information of what is contained in the MSC and/or what will become available in the MSC in the, preferably near, future. The directory channel can, for example, comprise a title, possibly a short abstract, and some sort of indication, such as a link, to where this information is available. Figure 4 shows a flow chart of a method according to the invention, how this is done in a receiver to economize power according to the invention. In a first step/state 410 the receiver receives information/data and possibly information of interest in DAB frames. From the first step 410, the procedure continues with a second step 420. The second step 420 deinterleaves a directory channel of the MSC and extracts information about what information is available in the received MSC and/or what information will be available in the MSC. This directory channel should be as small as possible and only comprise an absolute minimum of information, which will vary from application to application. Since it is relatively small the receiver will not waste much power when deinterleaving it. After the second step 420 the procedure continues with a third step 430. The third step 430 determines if the information that is available in the received MSC and/or the information that will be available in the MSC is some information of interest. If user interaction is necessary for determination, then the contents of the directory channel is preferably presented to a user in a suitable manner such as via audio or visually via a screen. If it is determined that the received MSC, or some future MSC, comprises some information of interest then the procedure continues with a fourth step 440. On the other hand if it is determined that the MSC does not comprise any information of interest, then the procedure continues with the first step 410 of receiving. Suitably the directory channel is only deinterleaved again when it has been updated. This procedure can suitably be done according to the enhancement according to Figure 5. The fourth step 440 determines if the information of interest that is available in the MSC and/or will become available, is available and already deinterleaved in the receiver or not. If the information of interest is not available in the receiver then the procedure will preferably continue with the enhancement according to Figure 5, preferably with the first step 550 if the information of interest will become available in a future MSC, and preferably with the third step 570 if the information of interest is available in the current MSC. On the other hand, if the information of interest is available in the receiver, then the procedure will continue with the first step 410 without deinterleaving the MSC any further. The information of interest will then suitably be supplied to the requester. Figure 5 shows a flow chart of a preferred enhancement method of reducing power consumption in a digital audio broadcasting receiver according to the invention. The enhancement basically only deinterleaves new information by keeping track of what information is already deinterleaved in the receiver. In a first step/state 550 the receiver receives information/data and possibly information of interest in DAB frames. After the first step 550, in a second step 560 it is checked to determine if the information of interest, which is received, or the receiver will receive, is available in the receiver. If it is determined that the information of interest is not available in the receiver then the procedure continues with a third step 570. The third step 570, deinterleaves only the parts of the MSC which comprise information interest which is not available in the receiver. It will thus deinterleave parts of the presently received MSC if it is the currently received MSC that comprises the not locally available information of interest, or wait until it has received the correct future frame with the MSC with the not locally available information of interest. Thereafter in a fourth step 580 the newly received and deinterleaved information of interest is made available and also marked as available in the receiver. The procedure will then preferably continue with the first step 550 again. If, in the second step 560, it was determined that the information of interest was available in the receiver, then the MSC would not be deinterleaved, but the procedure would simply continue with the first step 550. Figure 6 shows a flow chart of a specific method according to the invention, specifically it also shows an expansion of the second step 560 of Figure 5. From the first step 550 of Figure 5, the procedure continues with a first expanded step 662. The first expanded step 662 decodes the FIC or an information channel in the MSC, such as the directory channel, and extracts information about what information is available in the received MSC and/or what information will be available in the MSC. After the first expanded step 662 the procedure continues with a second expanded step 664. The second expanded step 664 determines if the information that is available in the received MSC and/or the information that will be available in the MSC is some information of interest. If it is determined that the MSC comprises some information of interest then the procedure continues with a third expanded step 666. On the other hand if it is determined that the MSC does not comprise any information of interest, then the procedure continues with the first step 550 of Figure 5. The third expanded step 666 determines if the information of interest that is available in the MSC and/or will become available, is available in the receiver or not. If the information of interest is not available in the receiver then the procedure will continue with the third step 570 of Figure 5. On the other hand if the information of interest is available in the receiver, then the procedure will continue with the first step 550 of Figure 5 without deinterleaving the MSC. With knowledge of what type of data transport many different information services utilizes, came the invention of not continuously deinterleaving the complete MSC. Information that is transferred over a broadcasting system, especially if there is no feedback channel (uplink) to ask for specific desired information, is usually transferred continuously or at certain intervals and when there is a change. The first type of information transfer is based on the assumption that the information provider does not know when a single receiver is turned on and therefore to ensure that all receivers are to be able to receive all the information of interest, continuously transmits the information over and over again. This type of information transfer is often referred to as using data carousels. A service provider could, for example, have a total of 50 pieces of information to broadcast. These 50 pieces of information are then continuously transferred, starting with the first one, then the second one and so on until the fiftieth has been transferred, then the procedure starts all over again with transferring the first piece of information again, and then the second one again and so on. If one piece of information becomes obsolete then it is removed and perhaps replaced by new updated information. This type of information transfer is for example used for Teletext systems. The second type of information transfer is based on the assumption that all interested receivers are more or less continuously tuned in and waiting for new updated information. According to the enhancement of the invention, a receiver keeps track of what information it has already received and thus it does not deinterleave the MSC for information the receiver already has. Even though the information might be information of interest, it might be redundant, i.e. not necessary to receive again. If the MSC does not comprise any information of interest at all then it is not necessary to deinterleave the MSC at all. Figure 7 shows a time diagram of a DAB data carousel transmission 710 and reception 730 according to the invention. A top line indicates the activity of an MSC channel with interesting information 710 over time. A middle line indicates the activity of a directory 720 sub-channel in the MSC or FIC, over time. A bottom line indicates the activity over time of the deinterleaver deinterleaving 730 the MSC channel with interesting information. According to the invention data carousels are labeled with version numbers to thereby be able to keep track of what is transmitted and what is available in a receiver and what is not, in an efficient manner. When information is broadcasted in the form of data carousels a channel will look like the top line 710 with all the information of the data carousel 712, 713, 714, 715 being continuously broadcasted. In the example according to Figure 7, interesting information of a data carousel version one 712, 713 is broadcasted twice, and interesting information of the data carousel version two 714, 715 is also broadcasted twice. According to the invention each version of a data carousel is given a version number, which means that when information in the data carousel is changed/updated, then a new version number is assigned to the data carousel. In this way by only keeping track of a single version number, which only requires very little bandwidth to transmit, a receiver can determine if it has received/stored the information of a specific version of a data carousel, or not. According to the invention the version number of a currently broadcasting, or to be broadcasted, data carousel is transferred 721 , 722, 723, 724 in a sub-channel in the MSC or in the FIC, in dependence on the specific embodiment. In this manner a deinterleaver of a receiver only has to deinterleave 732, 734 a desired channel when there is information of interest in that channel that has not been received before. The version number is preferably at least transferred 721, 723 just before the first time a new version is broadcasted, to thereby enable the deinterleaver to wake-up in time to deinterleave the channel of interest. In some embodiments a corresponding version number is repetetively transferred 721, 722, 723, 724 at least once for each broadcasting of a data carousel. Figure 8 shows a time diagram of a DAB data file transmission 810 and reception 830 according to the invention. Figure 8 shows another manner of transferring information. Just as in Figure 7, Figure 8 shows a top line indicates the activity of an MSC channel with interesting information 810 over time. A middle line indicates the activity of a directory 820 sub-channel in the MSC or FIC, over time. A bottom line indicates the activity over time of the deinterleaver deinterleaving 830 the MSC channel with interesting information. According to the invention data files are labeled with version numbers to thereby be able to keep track of what file is transmitted and which files are available in a receiver and which are not, in an efficient manner. When information is broadcasted in the form of files a channel will look like the top line 810, each file 812, 814, 815 being broadcasted one or more times. In the example according to Figure 8, interesting information of a data file version one 812 is broadcasted once, and interesting information of the data file version two 814, 815 is broadcasted twice. As with the previously describe data carousels according to the invention each version of a data file is given a version number. According to the invention the version number of a currently broadcasting, or to be broadcasted, data file is transferred 821, 822, 823, 824, 825 in a sub-channel in the MSC or in the FIC, in dependence on the specific embodiment. In this manner a deinterleaver of a receiver only has to deinterleave 832, 834 a desired channel when there is information of interest in that channel that has not been received before. The version number is preferably at least transferred 821, 823 just before the first time a new version is broadcasted, to thereby enable the deinterleaver to wake-up in time to deinterleave the channel of interest. In some embodiments a corresponding version number is repetetively transferred 821, 822, 823, 824, 825 at least once for each broadcasting of a data file. The present invention can be put into apparatus-form either as pure hardware, as pure software or as a combination of hardware and software. If the method according to the invention is realized in the form of software, it can be completely independent or it can be one part of a larger program. The software can suitably be located in a general-purpose computer or in a dedicated computer. As a summary, the invention can basically be described as a device and a method which provide means to enable a lower power consumption of a digital audio broadcasting receiver by first only decoding a small part of the received MSC to thereby determine if there should be any further decoding. The invention is not limited to the embodiments described above but may be varied within the scope of the appended patent claims. 2000-09-25 FIG 1 a block diagram of one DAB frame 101 null symbol, 102 phase reference symbol, 103 FIC fast information channel, 104 MSC main service channel - audio programs, FIG 2 a block diagram of a digital audio broadcasting transmitter, 200 an example of a digital audio broadcasting transmitter where the invention is suitably implemented, 201 sound service, 202 other services, 203 data service, 204 other services, 205 services configuration, 209 DAB signal, 210 audio encoder, 211 data encoder, 212 channel encoder, 213 channel encoder, 214 time interleaver, 215 time interleaver, 220 MUX, 222 MUX controller, 224 FIC generator, 226 frequency interleaver, 228 sync generator, 230 OFDM. FIG 3 a block diagram of a digital audio broadcasting receiver, 300 an example of a digital audio broadcasting receiver where the invention is suitably implemented, 302 antenna, 304 tuner, 306 analog to digital conversion, 308 information path, 312 Fast Frequency Transform (FFT) stage and differential demodulation, 314 time and frequency deinterleaver and error correction 322 audio decoder, 324 speaker(s), 332 data decoder, 334 data information to data services, 342 user interface, 344 control and synchronization, 346 data buss / control buss, FIG 4 a flow chart of a basic method of reducing power consumption in a digital audio broadcasting receiver according to the invention, 410 entry, from no of a third step, or from yes of a fourth step: a first step/state of receiving information in DAB frames, 420 from the first step: a second step, deinterleave an information/directory channel of the MSC and extract information about what information is available in the received MSC and/or what information will be available in the MSC, 430 from the second step: the third step, is the information that is available in the received MSC and/or the information that will be available in the MSC any information of interest? 440 from yes of the third step: the fourth step, is the information of interest that is available and/or will be available, is it available in the receiver ? FIG 5 a flow chart of a preferred enhancement method of reducing power consumption in a digital audio broadcasting receiver according to the invention, 550 advantageously from no of the fourth step of Fig. 4, from a fourth step, or from yes of a second step (or from no of a second expanded step or from yes of a third expanded step of Fig. 6): a first step/state receiving information of interest in DAB frames, 560 from the first step: the second step, check to see if information of interest, which is received, or the receiver will receive, is available in the receiver ? 570 from no of the second step (or from no of third expanded step of Fig. 6): a third step, deinterleave only parts, which comprise information interest, which is not available in the receiver, 580 from the third step: the fourth step, make and mark newly received and deinterleaved information of interest available in the receiver. FIG 6 expansion of second step of Fig. 5 according to a specific method according to the invention, 662 from the first step of Fig. 5: a first expanded step, decode FIC and extract information about what information is available in the received MSC and/or what information will be available in the MSC, 664 from the first expanded step: the second expanded step, is the information that is available in the received MSC and/or the information that will be available in the MSC any information of interest? 666 from yes of the second expanded step: the third expanded step, is the information of interest that is available and/or will be available, is it available in the receiver ? FIG 7 shows a time diagram of a DAB data carousel transmission and reception according to the invention, 710 MSC channel with interesting information; 712 interesting information data carousel version 1 ; 713 interesting information data carousel version 1 ; 714 interesting information data carousel version 2; 715 interesting information data carousel version 2; 720 directory MSC sub-channel or FIC; 721 first indication version 1 ; 722 version 1 ; 723 first indication version 2; 724 version 2; 730 MSC de-interleaving of relevant channel; 732 deinterleaving relevant channel with interesting information data carousel version 1 ; 734 deinterleaving relevant channel with interesting information data carousel version 2. FIG 8 shows a time diagram of a DAB data file transmission and reception according to the invention, 810 MSC channel with interesting information; 812 interesting information, file version 1 ; 814 interesting information, file version 2; 815 interesting information, file version 2; 820 directory MSC sub-channel or FIC; 821 first indication version 1 ; 822 version 1; 823 first indication version 2; 824 version 2; 825 version 2, second time; 830 MSC de-interleaving of relevant channel; 832 deinterleaving relevant channel with interesting info, file version 1 ; 834 deinterleaving relevant channel with interesting info, file version 2.

Claims: CLAIMS 1. A method of reducing power consumption in a digital audio broadcasting receiver when receiving a radio frequency signal comprising information entities, characterized in that the method comprises the following steps in the digital audio broadcasting receiver: - receiving the radio frequency signal including the information entities in frames, which frames comprise at least one main service channel; only deinterleaving a directory channel comprising a directory of what entities of information is included in the at least one main service channel; - determining from the directory if there is any information of interest among the information entities in a main service channel of the at least one main service channel; if it is determined that there is information of interest, then only deinterleaving a part of the main service channel that includes the information of interest; making the deinterleaved information of interest available in the receiver; thus reducing the amount of deinterleaving in the digital audio broadcasting receiver thereby enabling a reduced average power consumption of the digital audio broadcasting receiver. 2. The method according to claim 1, characterized in that the step of determining from the directory if there is any information of interest comprises the following substeps: - presenting the directory to a requester; determining that there is information of interest in a main service channel of the at least one main service channel if a selection of an information of interest out of the directory is received from the requester. 3. The method according to claim 1 or 2, characterized in that the directory channel is a sub channel in the main service channel. 4. The method according to claim 1 or 2, characterized in that the directory channel is comprised in a fast information channel. 5. The method according to any one of claims 1 to 4, characterized in that the directory channel comprises at least one descriptor of at least one information entity, each descriptor being associated with a corresponding information entity by means of a link to the information entity. 6. A digital audio broadcasting receiver with reduced power consumption when receiving a signal including information entities, characterized in that the receiver comprises: - means arranged to receive a radio frequency signal including the information entities in frames, which frames comprises a main service channel; means arranged to control a deinterleaver means to only deinterleave a directory channel comprising a directory of what information entities are included in the at least one service channel; means arranged to determine from the directory if there is any information of interest in a main service channel of the at least one main service channel; means arranged to control a deinterleaver means to only deinterleave the parts of the main service channel that includes the information of interest if it was determined that there is information of interest; means arranged to make the deinterleaved information of interest available in the receiver; thus the amount of deinterleaving in the digital audio broadcasting receiver is reduced thereby enabling a reduced average power consumption of the digital audio broadcasting receiver. 7. A method of reducing power consumption in a digital audio broadcasting receiver when receiving a radio frequency signal comprising information entities, characterized in that the method comprises the following steps in the digital audio broadcasting receiver: receiving the radio frequency signal including the information entities in frames, which frames comprise at least one main service channel; only deinterleaving desired information entities; making the deinterleaved information entities available in the receiver; thus reducing the amount of deinterleaving in the digital audio broadcasting receiver thereby enabling a reduced average power consumption of the digital audio broadcasting receiver. 8. The method according to claim 7, characterized in that the step of deinterleaving desired information entities is only executed if the desired information is not already deinterleaved and available in the receiver.

Inventors: BOHM KRISTINA, OSSFELDT JAN, BOHM, KRISTINA, OSSFELDT, JAN
Applicants: BOHM KRISTINA, OSSFELDT JAN, TERACOM AB, BOHM, KRISTINA, OSSFELDT, JAN
Application year: 2000
Main classification: H04H1
IPC codes: H04B1, H04H20, H04H60