Method for adapting the bit rate of a bit stream which is to be transmitted in a communication system and corresponding communication device

Translation of description of equivalent WO 03024014 A2

description

Method of adjusting the bit rate of a communications system to be transmitted bit stream and corresponding communication munikationsvorrichtung

The present invention relates to a method for adapting the bit rate of a in a communications system, particularly a Mobilfunksytem, ​​to be transmitted bit stream as well as a corresponding communication device.

The mobile technology is in a rapid development. Instantly ( "Universal Mobile Telecommunication System") is carried out for mobile phones of third generation mobile communications in the standardization of the so-called UMTS standards.

Here, a rate matching on the transmitting side ( "Rate mats ching") is provided to the bit rate of the transmitted bit stream adapted to the respectively possible transmission rate, wherein either the bits removed from the bit stream or multiplied in the bit stream, in particular doubled, are , The removal of bits is referred to as puncturing ( "puncturing") and multiplying the repetition ( "Repetition").

A possible construction of the transmission path of a mobile radio transmitter, in which such bit rate adjustment is provided, is exemplary shown in FIG. 1

An alternative, more data or transport blocks data stream is first expanded by a device 1 so-called "tail bits". The thus outputted from the means 1 bit stream is supplied to a channel coder 2 is supplied, where the information bits in dependence on the respectively applied type of channel coding, redundant bits are added, so that for most coding schemes on the one hand so-called systematic bits and on the other hand, parity bits ( "Parity Bits ") are created. Depending on the code rate of the coder 2 Kanalco- arise more or less systematic bits or parity bits. The parity bits have a lower priority or importance for the decoding of the corresponding message in some encoding schemes than the systematic bits. In the channel encoder 2 may be, for example, in UMTS mobile radio systems a so-called turbo encoder, which is generally constructed from interleaved convolutional.

The channel coder 2 is a bit rate matching device 3 downstream, which punctures the bits supplied thereto according to a certain bit rate matching algorithm and / or repeats. Due to the lower importance or priority of the parity bits, the parity bits are conventionally to Bitratenanpas- sung preferably dots, because they are less important for a successful decoding of each message on the receiving end as the systematic bits.

The output from the bit rate matching device 3 bit stream is scrambled with the aid of an interleaver 4, so that the individual bits are rearranged in time according to a particular interleaving scheme. The interleaver 4 has the consequence that the priorities of the individual bits are not known to exist in the bit stream output from it.

The output from the interleaver 4 bits are applied to a modulator 5, respectively, which depends on the modulation type used in each case displayed more of these bits to certain

mapping symbols of a multi-dimensional symbol space and transmits the symbols to a receiver. In a QPSK modulation ( "Quadrature Phase Shift Keying") each have two bits are divided into four equally spaced in a two-dimensional symbol space symbols, while at a

8PSK modulation three bits at a lβQAM modulation ( "quad raturamplitudenmodulation") and four bits at a 64QAM Modulation six bits are assigned to a symbol in a two-dimensional symbol space.

The symbols generated from the modulator 5 is transmitted in the form of a real and imaginary parts, which uniquely describe the position of the respective symbol in the two-dimensional symbol space. A modulator 5 downstream demultiplexer 7 distributes the symbols on possibly multiple channels, where the symbol sequence reNCy with different channelization or spreading codes Wi ... W_M are encoded, as shown in Figure 1 in the form of corresponding multiplier. 8 About an adder 9, the sum signal of different channel-coded symbol sequences is generated and output.

In addition, a by the acronym AMCS ( "Adaptive Modulation and Coding Schemes") provided in accordance with Figure 1 control unit 6 is provided which by the modulation alphabet to be used in each of the modulator 5 and the coding schemes and code rates of the channel coder 2 and the breakdown between the different channelization codes the demultiplexer 7 sets.

The transmit path structure shown in Figure 1 corresponds to, for example, of a so-called HSDPA ( "High Speed

Downlink Packet Access ") provided in UMTS Mobilfunksytemen structure of the physical layer. It is a packet-switched connection, whereby in addition a so-called ARQ (" Automatic Repeat Request ") can be used, wherein the receiver (eg, a mobile station ) of a data packet with a faulty reception of this data packet retransmission thereof by the transmitter (for example a base station) requests, after which the transmitter transmits a repeat of the original the sent data packet to the receiver. One problem with the function of the modulator shown in Figure 1 5 is that because of the modulation type selected in each case all the modulator 5 supplied bits can not be transferred equally sure that the reliability of the individual bits varies as a function of the position of symbol in the symbol space to which the individual bits are mapped.

This will be explained in more detail below achieved with reference to Figure 6, wherein by way of example the signal constellation or the two-dimensional symbol space 12 is shown for a 16QAM modulation in Fig. 6 Here are four bits ii, qr, i₂ and q in the order given a symbol 13 of the two-dimensional symbol shown in Figure 6 space assigned 12, wherein the type of imaging of the individual bits is called the icons 13 as the "Gray Mapping". In Figure 6, in each case those columns or rows of symbols are marked with a bar, which a bit or ii i₂ or qi or q correspond with the value "1". From the representation of Figure 6 can be seen, for example, the symbols with i₂ = "1" eight neighbors with the value i = "0" have, for example, while symbols with ii = "1" only four potential neighbors with ii = "0" and thus have only four direct decision thresholds. This has the consequence that the symbols with the bits ii = "1" are better protected against erroneous transmission as symbols with i₂ = "1". The same is true for example for the symbols qi = "1", which have a greater reliability than symbols with q₂ = "1". In principle can thus be said that in the signal constellation shown in FIG 6, the bits ii and qi greater reliability in terms of error-free determination of information content than the bits i₂ or q₂,

In the transmit path structure shown in Figure 1 thus occurs the problem that on the one hand bits with different priority or importance for the decoding of the respective Message are provided and on the other hand, the modulator 5 transfer all bits equally safe or track on the same reliable symbols can not, which are then transmitted in the form of its real part Re and its in-phase component and its imaginary or in its quadrature component, so that optionally bits are mapped and transmitted with a high priority on symbols with low reliability, of which the data transmission reliability and data transmission quality suffers.

In this regard, a specific assignment of the bits to the symbols 13 of icon area has already been proposed, for each transmission attempt of a data block 12 to make so that when using a skillful assignment rule after several transfers an approximation of the reliability of the individual bits can be achieved. This applies however only if a data block is repeated several times. The transmission reliability in the first transmission of a data block is not improved by this proposal. Access to are not considered the different priorities of the channel-coded bits in this proposal. A further problem associated with this proposed problem is that the repetition packet not to the originally transmitted data packet due to the different loan figure of the individual bits to the transmitted symbols are inevitably the same. This means that on the receiver side, the two repetitions can not be combined immediately before the demodulator, but instead a so-called log-likelihood combination be performed on bit uss. The received in-phase and quadrature values ​​are first transmitted in probabilities for the bits converted in order to derive the bits actually transmitted with the greatest probability. However, the log-likelihood combination has over the aforementioned simple symbol combination in which the symbols of the original data packet with symbols of the repeat data packet just before the demodulator to Application of a channel estimate weighted by the respective signal / noise ratio can be added, particularly in poor transmission characteristics underperformed on. Furthermore, with the conventional Sy - bolkombination in a (for example, the in-phase

Component) associated with the memory location two bit information are kept, so that space can be saved.

Another proposal is shown in Figure 2, wherein, after the channel encoder or turbo encoder 2, which isolated by systematic bits and parity bits P S outputs the bits a separate processing of the systematic bits and parity bits is carried out Therefore, in particular two separate interleavers are provided 4a and 4b, in which an input device 10, a parallel / serial conversion on only one bit stream takes place in such a way that an intelligent possible assignment of bits with different priorities or importances to the bit positions with varying degrees of reliability can take place within the individual symbols. The bits with the highest priority, ie the systematic bits S, preferably to the bit positions with the highest reliability and the bits with the lowest priority, that is, the parity bits distributed to the bit positions with the lowest reliability. Since often more bits with the highest priority are available as bit positions with the highest reliability, usually not an optimal solution is possible. In addition, this variant requires terleavern at home and the additional means 10 considerable additional implementation complexity due to the majority.

The present invention has for its object to provide a method for adapting the bit rate of a transmitted in a communication system to bitstream and a communication device, wherein the data transmission quality and data security can be improved with the least possible effort. In particular, with the simplest possible means the best possible picture more important bits be ensured at bit positions with high reliability within the individual modulation symbols.

This object is achieved by a method having the features of claim 1 or a communications device with the features of claim 18th The subclaims each define preferred and advantageous embodiments of the present invention.

The invention proposes to use for bit rate adjustment a bit rate matching algorithm in which especially in the case of puncturing or repetition, the quality or reliability of with which in an actual transmission through the respective bit a certain information content can be transmitted effectively to transfer dienen- bits, , in particular the reliability of the corresponding bit positions within the symbols to be transmitted are taken into account.

Ideal an allocation of the bits to be transmitted of each bit stream to the bits actually available for transmission is such that the sum of the reliabilities of the available for the transmission of bits corresponding to a particular bit of the bit stream, exactly proportional to the importance of the respective bits. The association will not in practice only in special cases (for example, if all bits have the same importance and is every bit equal to frequently repeats, etc.) accessible.

Therefore, the invention proposes to achieve at least an average over several successive bits of the transmitted bit stream as accurate as possible approximation to this ideal, that is, the puncturing / repetition to make such that for a certain number of consecutive bits of the transmitted bit stream, the sum of the importances these bits as well as possible in a fixed proportionality nis bits used to sum of the reliabilities for those bits for transmission stands.

According to an embodiment of the present invention in this respect is provided locally to increase the puncture rate (or to reduce the repetition rate), if the quotient of the sum of the importances of the previously bits to be transmitted divided by the sum of the reliabilities of the bits used for this purpose for transmitting greater than a predetermined threshold value. Conversely locally the puncturing rate is reduced (or the repetition rate is increased), if the quotient of the sum of the importances of the previously bits to be transmitted divided by the sum of the reliabilities of the bits used for this purpose for the transmission less than the predetermined threshold value.

According to a preferred embodiment of the invention this is achieved in that is used in determining an error value which is a measure for the deviation between the outer genblicklichen puncturing or repetition rate and the desired puncturing or repetition rate, an update parameter, which bitspezifisch is selected for each serving for the transmission bit depending on the reliability with which in an actual transmission through the respective bit, a certain information content can be transmitted. That this update parameter is not selected to be constant, but changes bitspezifisch depending on the quality and reliability of serving to transfer bits, so that when the puncturing or repetition, the quality and reliability of the components used to transfer bits can be considered what quality the increases and security of data transmission.

it when in the Bitratenanpassungs- algorithm not only the quality and reliability of the components used to transfer bits into account is particularly advantageous, but the importance or priority of the bits of the bit rate matching to be subjected to bit stream. In this respect, a corresponding update parameters are used, which is, bitspezifisch selected individually for each bit of the bitstream for which a decision as puncturing / repetition needs to be made. Using the measures described above can thus be ensured that for a certain amount of adjacent bits, the sum of the importances of the bits to be transmitted is always as good as possible at a fixed ratio to the sum of the reliabilities of the bits used for it for transmission.

According to the invention is in particular a Bitratenanpassungalgo- algorithm used, which is in contrast to conventional bit rate matching algorithms designed such that can take place in a single data block both puncturing and repetition of bits in a simple manner, wherein the different importances and reliability fluids of bits can be included within a data block.

In order to obtain the information necessary for carrying out the present invention, information about the reliability of the individual components used to transfer bits, various measures can be taken. So separate interleaver for example, for different classes of bits to the different importances may be used, wherein the signals output from the interleavers bits of the respective bit class are mapped to specific bit positions with respective reliabilities of the symbols to be transmitted, so that in performing the bit rate matching purely by vornehe- both the is Wichtigkeits- and reliability of information available. Alternatively, the sequence of the reliability can transmittances at the output of the channel encoder also from the known reliabilities depending on the modulation type used in each case calculated by deinterleaving will. Such explicit Deinterleavingoperation can be avoided if the interleaver used in each case, at least with respect to the assignment of the bits of different bit classes, each having different reliabilities, implements a simple mapping rule, which, depending on the modulation type selected in each case by a corresponding configuration of the respective Inter - can be achieved leavers. To this end, preferred embodiments are described in detail.

Studies of the turbo coding, it turned out that the Paritätbitströme usually provided by a turbo encoder are completely equivalent not, but that it makes sense, the parity bits, which are used in Turbodeco- coder first to send a somewhat lower puncturing than the parity bits of second parity bit stream. Thus, the parity bits of the first parity bit stream could be provided with a slightly higher importance or priority than the parity bits of the second Parität- bitstream.

In communication systems in which the previously described ARQ procedure applies, the importance or priority of the individual bits can be selected depending on the number of times the corresponding data packet is transmitted.

The present invention is preferably suitable for use in Mobilfunksytemen, in particular for use in UMTS mobile communication systems. Of course, however, the present invention is not limited to this preferred application, but may generally refer to any communication system where the transmitter side a bit rate adjustment is performed, application. In addition, affected by the present invention not only the transmitter side, but also the receiver side since the receiver side, an ER inventively processed received signal must be evaluated.

The present invention is more detail below with reference to the accompanying drawings would take based on preferred embodiments illustrated.

1 shows a simplified block diagram of a transmitting path structure of a mobile radio transmitter in which the present invention can be implemented,

Figure 2 shows a simplified block diagram of the transmission path structure of a mobile radio transmitter according to another embodiment of the present invention,

Figure 3 shows a simplified block diagram of the transmission path structure of a mobile radio transmitter according to yet another embodiment of the present invention,

Figure 4 shows a bit-rate adaptation algorithm in accordance with a preferred embodiment of the present invention,

5A-5C show possible assignments of deinterleavers, which according to other embodiments of the present invention in accordance with appropriately designed interleavers may be used, and

Figure 6 shows the signal constellation for 16QAM modulation.

4 shows a bit rate adaptation algorithm is shown in accordance with a preferred embodiment, as it can be used for example in the bit rate matching device 3 of the transmitter shown in FIG. 1 With regard to the function and operation of each component shown in Figure 1, reference is made at this point in addition to the foregoing. The bit rate matching algorithm based on calculating an error value e, which is a measure of the deviation between the instantaneous puncturing or repetition rate and the desired puncturing or repetition rate, whereby at the bit rate matching algorithm shown in Figure 4, two update parameter e_mi_nus and e_pι_us are used, with the aid of the error value either e_mi_nus reduce or e_Pι_us is increased. By evaluating the in this way each updated error value e is judged whether (and if so how often) the respective bit to be transmitted or not.

Here, it is assumed that each of the bit rate matching device 3 supplied bit x_m a particular impor- tance and priority w (x_mis assigned) representing the relevance of the respective bit for decoding and retrieval of a corresponding message on the receiver side. The larger the value w (x_m) Of a bit x_m is, the greater the importance of the corresponding bit. The impor- tance of the individual bits m can thus particularly in turbo encoders may be different, since it is known that came from Turbocodierern systematic bits are more important for the Decodability the corresponding message than the less important parity bits. In a convolution encoder, for example, the bits wear at the beginning and end of a lower information content and can therefore be provided with a lower importance. The sum of the importances of the individual bits of N bits comprehensive data package adds up to a parameter K:

(1) Σ ( _Xm) = K m = l

Conversely, it is assumed that for each transmitted bit, that is, each output given by the bit rate matching device 3 bits y_n, Reliability or quality v (y_nis) defined which corresponds to the ease with which the information content of the bits can be transmitted. As has already been explained above with reference to Figure 6, are assigned by the processing performed by modulator 5 shown in Figure 1 Modulation more bits a particular symbol in the rule, but the reliability or safety of the individual bits within these symbols not is identical, but some bits can be transmitted more secure than others. Moreover, the bits can be transmitted with different power, the interference power may be different at the time of sending the bits or the individual bits can vary widely from one training sequence or pilot symbols, which are used for channel estimation, be removed or due to other circumstances, different reliabilities exhibit. Each output bit of the bit rate matching device 3, ie, each transferred bit y_nIs thus a bit-specific value v (y_nassigned), the reliability of the output bits y_n increases, the larger the value of v (y_n) Is. The sum of the reliabilities of all Nc bits of a detection device 3 outputted from the data packet Bitratenanpas- here results in a parameter L:

nc

(2) Σ v (y_n) = L n = l

Depending on the in the above formulas (1) and (2) defined contexts for each input bit x_m a bit-specific update parameter e_mi_nus (ΠO defined as follows:

(3) e_minus(M) = w (x_m) • L

Also, for each output y_n the bit rate matching device 3, that is to be transferred for each bit, a bit-specific update parameter e_pι_usdefined (n) as follows: (4) e_pι_us(N) = v (y_n) ^■ K

This bit-update parameters used in the bit rate matching algorithm as follows shown in Figure 4:

In step 100, the error value e is first egg to an initial value_ni set that the error between the instantaneous and the desired puncturing / Repetie- insurance rate at the beginning of the process is. This initial value ei_ni usually has the sake of simplicity the value 1. Subsequently, the index of the currently considered bit is set to 1 in step 101, while also in a step 102, the index of output for each data packet from the bit rate matching unit 3 bits to the index 1 becomes. Subsequently, the in a WHILE loop 103 embedded workflow for all N bits of the respective data packet is performed. In this case, in a step 104 for bit x_m the error value e updated, for which purpose the difference between the instantaneous error value and the respective bits of the x_m specific update parameter e_mi_nus(M) is calculated. If the result is e <0 (step 105), the corresponding bit x_m selected for the transmission and processing of the 3 Bitratenanpassungseinrich- released for transfer or output to interleaver 4 (Sehritt 106). Subsequently, the corresponding error value e to the specific for each bit to be transmitted and for the respective output bit update parameter e is_pι_UΞ(N) (step 107) and the index of output bits is incremented (step 108). from figure

4 it is apparent that through the steps 105-108, the corresponding bit x_m often selected for the transmission and the error value to e_pι_us (N) is increased, until the error value e has a value reached is greater than zero. This means that the bit x_m is not selected for transmission, and thus punctured, if the updated value in step 104, error e of the already before performing Loop comprising steps 105-108 is greater than zero. On the other hand, in the case that, after the step 104, the error value e <0, the bit x_m as often repeats, as the error value e to reach the value zero to e_pι_us(Π) can be enlarged. After completion of the loop comprising steps 105-108, the index m of the input bits of the bit rate matching device 3 is increased (step 109) and the process for the new input bit starting at the step 104 is performed again.

When the bit rate matching algorithm shown in Figure 4, by varying the parameters e_rai_nUs and e_pι_us controlled areas in which punctured bits and the areas in which bits are to be repeats. A puncturing, refer det generally in those areas instead where applicable e_mi_nus <e_pius / while conversely a repetition is performed where applicable e_mirms > e_pι_us,

The update parameter e_pι_UΞ may be proportional to the chosen transmission quality of the respective output bits of the bit rate matching device 3 formation content to Switzerland or.

To realize the above-explained Bitratenanpassungsal- algorithm has the bit rate matching device 3 already when executing the bit rate matching algorithm reliability or quality v (y_n) Of bits used for transmission y_n, Ie for example the "Gray mapping" scheme of each provided modulator 5 be to map the bits to be transmitted to the corresponding symbols known. This may be problematic, since between the bit rate matching device 3 and the modulator 5 is usually of the interleaver shown in Figure 1 4 is provided, which undertakes a time based reordering of the passungseinrichtung of the Bitratenan- 3 output bit sequence. This problem is solvable, if the influence of the interleaver is considered vers. 4 However, for simplicity might for each bit class in which bits of the same reliability v (y_n) And quality are summarized, separate interleavers 4a, 4b are used, as has been explained earlier with reference to FIG. 2 In a 16QAM modulation (see Figure 6) would therefore only two separate interleaver 4a, 4b required because there are only two different reliabilities of the individual bit positions within the 6 symbols shown in Figure, and thus two different classes of bits. Since each interleaver 4a, 4b is each assigned to a bit class in this case, the bit rate matching device 3 is implicitly the reliability of the bits of the two output bit streams known.

however, If no separate interleaver may be used provided the general case, the sequence of reliabilities v (y_n) At the output of the channel coder 2 ving by Deinterlea- using a deinterleaver 11 from the known reliabilities v (y_k) The type of modulation used in each case are calculated, where n denotes the index of passungseinrichtung from Bitratenan- 3 bits output and k the bit index by the interleaver. 4 A corresponding embodiment is shown in Figure 3, with the significances and priorities w (x_m) Of the input x_m the bit rate matching device 3 can be derived from the turbo encoder channel or second

An explicit deinterleaving operation can be avoided if in the interleaver 4 shown in Figure 4 at least in relation to include the assignment of the individual output bits of the bit rate matching device 3, which have different reliabilities, a simple mapping rule is implemented.

The simplest implementation of this principle it is, if the function of the interleaver 4, the order of the bits with different reliabilities, that is, the sequence of the different classes of bits, unchanged remains. Occur in the modulation by the modulator 5, for example, in a 16QAM modulation, bits alternately low and high reliability, this is consequently also before the interleaver 4 of the case, so that the Bitratenan- passungseinrichtung 3 slightly due to the order of the

Bit output or due to the bit index n to the respective inherent reliability v (y_n) Can close. This can be in the Blockin- currently used for UMTS Mobilfunksyteme interleaver with column exchange, in which the individual bits line by line written and read column by column, relatively easy to implement when the number of columns to the number of different reliability depending on the currently selected is modulation prime. If, in addition, the number of lines of Blockin- terleavers with the number of different reliabilities, ie the number of bit classes relatively prime, an assignment given a suitable column exchange erreichen-, wherein the order of modulation bits is always alternately while otherwise within a column of the interleaver te alternately, that is, there are few "joints" where this particular order is breached. These few "joints" are not annoying because with a suitable choice of Spaltenvertauschungsoperation the number of "contact points" can be kept low.

Such an interleaver implementation is for the example of a 16QAM modulation illustrated in Figure 5A, wherein not the interleaver 4 itself, but the corresponding de-interleaver 11 is shown in Figure 5A, that is, have the input data, the order of the bit reliabilities v (y_k) At the modulator 5, which of the deinterleaving 11 the desired sequence v (y_n) Is output to the reliabilities for the bit rate matching device. 3 In the example shown in Figure 5A, the memory of Deinterleavings line by line filled and read column by column, the

lines are described in the order 1, 2, 3, 4, 5, 6, 7 and read the columns in the order 1, 4, 3, 2, 5 the (what the aforementioned column exchange equivalent). In a 16QAM modulation, there is - as already mentioned - only two classes of bits with different reliability, wherein the reliable bit positions in Figure 5 with H ( "high reliability"), and the less reliable with L ( "Low reliability") are designated , At the modulator 5, a sequence of two H and two L-bits bits is combined into a modulation symbol in each case. In the example shown in FIG 5A, the number of different bit classes (two) and the number of rows (seven) and the number of columns (five) is relatively prime. The columns - as indicated above - sen read out in the order 1, 4, 3, 2, 5, is obtained both before and after the interleaver 4, the alternating sequence of two H and two L bits bits. This means that the functionality of interleaver 4 is transparent and the assignment of the individual reliabilities v (y_n) For each output bit of the bit rate matching device 3 very simple.

A similar example is illustrated in Figure 5B, which are provided in the example shown there instead of seven lines eight lines, so that the coprimality described above is no longer present. If the columns are read in the order of 1, 5, 2, 3, 4, the alternating sequence of two H bits and two L bits can not be adhered to exactly. Generally there is no more reading sequence for which this predetermined alternating sequence to be copied exactly. Within a column, however, the alternating sequence is maintained, and only the "joints" between two columns (for example between columns 5 and 2, between the columns 2 and 3 and between columns 3 and 4) irregularities.

Another simple mapping provides that bits y_n v with the same reliability (y_n) Immediately come consecutively. This can be achieved if the number of columns of the interleaver 4 by the number of different Bit classes, in which the bits are combined with different reliabilities, is divisible. In addition, the column permutation of the interleaver 4 may be selected so that such an allocation is achieved.

A corresponding example is shown in Figure 5C, again not the interleaver 4, but the associated de-interleaver is represented eleventh The number of columns (eight) is by the number of different bit classes (two at a 16QAM modulation) divisible. By a suitable reading order, for example, by reading the columns in the order 1, 5, - 2, 6, 3, 7, 4, 8, a moiety of the H- and L-bits can be achieved, so that also for the bit rate matching device 3 depending on the index n of bits each issued and provided for transmitting and from knowledge of the Interleaverstruk- simple structure to the associated bit reliability v (y_n) Can be closed.

By means of the present invention may thus - as has been described in detail above - both the importance or priority of the individual bits x_m of that bit stream, a bit rate adaptation which is to be subjected, as well as the reliability or quality of the bits y_nWhich are provided to perform the bit rate matching for transmission, are taken into account at the bit rate adaptation, in dependence upon the respective Betriebsbzw. Transmission conditions perform an optimal bit rate adaptation.

In this case, in particular in communication systems with ARQ processes in which an erroneous reception of the data packet is requested by the receiver for re-transmission from the transmitter, the importance or priority of the individual bits x_m be chosen depending on the number of times the corresponding data packet is transmitted. This is particularly interesting because in a turbine bocodierung the systematic bits in the first transfer are more important than the parity bits, while in a repeat of this transfer this difference even the parity bits may be more important or less fails. This measure can also be achieved that different bits are used for each transmission of a data block (in part). It can by the present invention, both so-called IR method ( "incremental redundancy"), in which the retransmitted data packets to the data packet originally transmitted are only partly identical, and so-called "chase combining" - - processes in which the are bits of all repeating data packets with the original data packet identical, can be realized. If preferred, instead of a puncturing uses a repetition, different bits can be repeats indeed always sent using the previously proposed action the same bits, but in the different transmissions of each data block (in part). An additional space is not therefore taken benö-.