EP1232596A2

EP1232596A2 - Method for adjusting the data rate in a communication device and the corresponding communication device

Info

Publication number: EP1232596A2
Application number: EP00989785A
Authority: EP
Inventors: Andreas Lobinger; Jürgen MICHEL; Bernhard Raaf
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 1999-11-25
Filing date: 2000-11-22
Publication date: 2002-08-21
Also published as: WO2001039421A3; US7346835B1; CN1399829A; WO2001039421A2; CN1188978C

Abstract

The invention relates to a method for adapting the data rate of a data stream in a communication device (1), in particular in a mobile radio transmitter, whereby the individual data blocks are pointed, according to a specific pointing model and the bits pointed according to the pointing model are removed from the respective data block. The pointing model is configured in such a way that it has a steadily increasing pointing rate extending from the middle of the discrete data block to at least one end of said data block.

Description

description

Method for adapting the data rate in a communication device and corresponding communication device

The present invention relates to a method according to the preamble of claim 1 for adapting the data rate m of a communication device and a corresponding communication device according to the preamble of claim 35.

Mobile radio technology is developing rapidly. The standardization of the so-called UMTS mobile radio standard ('Universal Mobile

Telecom unication system ') for mobile devices of the third generation of mobile phones. According to the current state of UMTS standardization, it is provided that the data to be transmitted via a high-frequency channel are subjected to channel coding, with convolutional codes being used in particular for this purpose. The channel coding encodes the data to be transmitted redundantly, which enables a more reliable recovery of the transmitted data on the receiver side. The code used for channel coding is determined by its

Characterized code rate r = k / n, where k denotes the number of data or message bits to be transmitted and n denotes the number of bits present after coding. The lower the code rate, the more efficient the code is. However, a problem associated with coding is that the data rate is reduced by a factor of r.

In order to adapt the data rate of the coded data stream to the respective possible transmission rate, a rate adaptation ('rate matchmg') is carried out in the transmitter, with bits being either removed from the data stream or doubled in the data stream according to a specific pattern. The Removing bits is called 'puncturing' and doubling is called 'repeating'.

According to the current state of UMTS standardization, it is proposed to use an algorithm for rate adaptation which punctures with an approximately regular puncturing pattern, i.e. the bits to be punctured are distributed equidistantly over the coded data block to be punctured.

In addition, it is known that in the case of convolutional coding, the bit error rate (BER) decreases at the edge of a correspondingly coded data block. It is also known that the bit error rate within a data block can be changed locally by puncturing which is distributed unevenly. These findings were used to heuristically find a puncturing pattern, after which all bits of the punctured data block have a bit error rate corresponding to their respective importance. However, such a procedure is not practical for UMTS mobile radio systems, since a general algorithm is required here, which delivers the desired results for each bit number of a data block to be punctured and for each puncturing rate.

The present invention is therefore based on the object of providing a method for adapting the data rate of a data stream m of a communication device and a corresponding communication device which leads to a satisfactory bit error rate and in particular m mobile radio systems with convolutional coding can be used.

This object is achieved according to the invention by a method having the features of claim 1 or one

Communication device with the features of claim 35 solved. The subclaims define preferred and advantageous embodiments of the present invention.

According to the invention, the individual data blocks of the data stream are punctured to adapt the data rate in accordance with a specific puncturing pattern, the puncturing pattern being designed such that it has a puncturing rate which increases continuously from a central region of the individual data blocks to at least one end of the individual data blocks.

The puncturing pattern preferably has a puncturing rate which increases continuously from the central region to both ends of the respective data block hm. In this way, the bits are punctured more strongly at the beginning and end of the data block to be punctured, whereby this is not done with a uniform puncturing rate, but with a puncturing rate that increases continuously towards the two ends of the respective data block, i.e. the distance between the punctured bits becomes shorter and shorter towards the two ends of the data block.

In the context of the present application, “continuously increasing puncturing rate” is also understood to mean that the distance between punctured bits averaged over a certain number of successive bits decreases monotonously. The "specific number" can be defined, for example, by the quotient from the length of influence of the code and the code rate, since the range of coded bits that depend on a bit to be transmitted contains this "specific number" of bits. For example, for a code with influence length 9 and a code rate 1/3 for the "certain number" of bits, by means of which the averaged distance between punctured bits can be determined, the value is 27. With code rate 1/2, the "determined" Number "18. This puncturing leads to an evenly distributed error rate of the individual bits over the punctured data block and also results in a reduced overall probability of error.

These advantages are retained even if the data blocks are initially punctured as described and then subjected to puncturing again with a uniform puncturing pattern. Likewise, after the puncturing described above, a

Repetition can be carried out. In this way, the desired data rate, i.e. a puncturing with a fixed puncturing pattern, the puncturing rate of which increases steadily towards the two ends of the respective data block, and a subsequent further puncturing or reptying operation, can very easily be carried out by means of two successive operations. the desired number of bits to be transmitted per data block.

The present invention is particularly suitable for

Adaptation of the data rate of a convolutionally coded data stream and can therefore preferably be used in UMTS mobile radio systems, this relating both to the area of the mobile radio transmitter and also to that of the mobile radio receiver. However, the invention is not limited to this area of application, but can generally be used wherever the data rate of a data stream has to be adapted.

The present invention is described in more detail below with reference to the accompanying drawing using preferred exemplary embodiments.

1 shows a simplified block diagram of a mobile radio transmitter according to the invention,

Fig. 2 shows a representation of different exemplary embodiments for em puncturing pattern, which of a unit shown in FIG. 1 can be used to adapt the data rate,

3A shows a comparison of the results achievable with puncturing according to the invention or with conventional puncturing with regard to the bit error probability distributed over a punctured data block, and

3B shows a comparison of the results achievable with puncturing according to the invention or with conventional puncturing with regard to the resulting overall error probability,

FIG. 4 shows an illustration of various exemplary embodiments for a puncturing pattern which can be used by a unit shown in FIG. 1 for adapting the data rate.

5 shows an exemplary embodiment of the invention in which the edge puncturing is carried out after a first interleaver.

1 schematically shows the structure of a mobile radio transmitter 1 according to the invention, of which data or communication information, in particular

Voice information is transmitted to a receiver via a high-frequency transmission channel. 1 shows, in particular, the components involved in the coding of this information or data. The information supplied by a data source 2, for example a microphone, is first converted into a bit sequence using a 3 m digital source encoder. The speech-coded data are then coded with the aid of a channel encoder 4, the actual useful or message bits being coded redundantly, as a result of which

Transmission errors can be recognized and then corrected. The code rate r resulting from the channel coding is an important parameter for describing the code used in each case for channel coding and, as has already been mentioned, is defined by the expression r = k / n. Here, k denotes the number of data bits and n the number of bits coded in total, ie the number of redundant bits added corresponds to the expression n-k. A code with the code rate r defined above is also referred to as an (n, k) code, the performance of the code increasing with decreasing code rate r. So-called block codes or convolutional codes are usually used for channel coding.

In the following, it should be assumed that - as is determined by the current state of UMTS standardization - convolutional codes are used for channel coding. A significant difference to block codes is that convolutional codes do not encode individual data blocks in succession, but that they are continuous processing, with each current code word of an input sequence to be coded also depending on the previous input sequences. Regardless of the code rate r = k / n, convolutional codes are also characterized by the so-called influence length or 'constramt length' K. The 'Constramt Length' indicates the number of cycles of k new input bits of the convolutional encoder 5 em bit influences the code word output by the convolutional encoder 5.

Before the channel-coded information is transmitted to αe receivers, it can be fed to an interleaver 5, which rearranges the bits to be transmitted in time according to a certain scheme and thereby spreads the time, so that the errors which generally occur in bundles are distributed in order to create a so-called memoryless Obtain transmission channel with a quasi-random error distribution. The information or data coded in this way is fed to a modulator 7, the task of which is is to modulate the data onto a carrier signal and to transmit it to a receiver via a high-frequency transmission channel 3 in accordance with a predetermined multiple access method.

For transmission, the coded data stream is divided into m data blocks, the convolutional encoder 4 being set to a known state at the start of a data block m. In the end, each coded data block is terminated by so-called 'tail bits', so that the convolutional encoder 4 is again in a known state. This construction of the convolutional code and of the convolutional encoder 4 ensures that the bits at the beginning and end of a coded data block are better protected against transmission errors than in the middle of the block.

The error probability of a bit differs depending on its location within the respective data block. This effect is used, for example, in voice transmission in GSM mobile radio systems by placing the most important bits at the two ends of the block where the probability of error is lowest. In data transmissions, however, data packets are generally already discarded if only one single transmitted bit is faulty, which is the case, for example, in

Receiver can be determined by a so-called 'Cyclic Redundancy Check' (CRC). It is therefore not possible to speak of important or less important bits in a data transmission, but all bits are to be regarded as equally important.

In order to adapt the data rate of the coded data stream to the respective possible transmission rate, a rate adjustment ('rate matchmg') is carried out in front of the modulator 7. In the exemplary embodiment shown in FIG

Rate adjustment divided into two units 6a and 6b, the unit 6a puncturing according to a certain Puncturing pattern is carried out in order to achieve a more uniform error distribution over a data block. The optional unit 6b then optionally carries out further puncturing or repetition in order to finally obtain the desired data rate. The sequence of the units 6a and 6b and the interleaver 5 shown in FIG. 1 are only to be understood as examples. The interleaver can also be arranged after the unit 6b. Likewise, the interleaver 5 can also be replaced by two interleavers before and after the unit 6b, etc.

The present invention is based on the principle of puncturing the coded data blocks more strongly during the rate adaptation at the beginning and / or at the end of the respective data block, this occurring with a puncturing rate which decreases from the edge to the center of the respective data block, i.e. in a data block output by the unit 6a, the distance between successive puncturing is the smallest at the beginning and at the end of the respective data block and becomes ever larger towards the middle.

Different embodiments are conceivable for the puncturing pattern to be used by the unit 6a. In the simplest case, the puncturing of each data block is always carried out with the same pattern. However, depending on the length of the data block to be punctured, different puncturing patterns can also be used. This procedure is particularly advantageous for short data blocks, since in this case the specified puncturing pattern can be shortened in order to avoid overlapping or 'growing together' of the sections of the puncturing pattern provided for the beginning and end of the block, which would otherwise result in excessive puncturing of the central area of the data block could result. When using a convolutional code with a code rate r = 1 / n and a 'Constramt Length' K, an encoded data block n * (Kl) tail bits are inserted. The puncturing pattern used by the rate adjustment unit 6 should therefore be designed in this case such that less than n * (Kl) bits are punctured together at the beginning and end of the data block to be punctured. This can be achieved by puncturing less than n * (Kl) / 2 bits at the beginning and at the end of the data block.

2 shows various possibilities for puncturing patterns according to the invention, the individual puncturing patterns AC each in a pattern beginning section (to be applied to the beginning of a data block), a pattern middle section (to be applied to the central area of the data block) and a pattern section (to be applied to the end of the data block) ) Pattern end portion are divided and each digit em coded bit. A bit to be transmitted is designated by a '1' and a bit to be removed or punctured by a '0' em from the respective data block. The individual patterns can each be formed algorithmically and have in common that no bit is punctured by the pattern center section, since it only comprises '1' bits. The pattern start and pattern end sections, on the other hand, are each designed such that the puncturing rate increases continuously from the central section to the edge hm and the distances between the punctured bits become shorter and shorter. In addition, the individual patterns A-C are each designed such that the pattern end section is mirror-symmetrical to that

Pattern start section is built. Alternatively, different patterns can also be used for the pattern start section and the pattern end section. It is also denkoar to puncture only on one side, ie either at the beginning or at the end of the respective data block. Puncturing only on one side offers advantages in particular in the case of a so-called "blind rate detection". It is not known a priori on the receiver side how many bits are transmitted exactly. Only a number of possible lengths are known, for example 40, 80 or 120 bits. For each of these options, the receiver directs a decoding em. To determine the actual length used, the data contains a checksum, on the basis of which a decision is made on the reception side about the length used. A Viterbi algorithm or a similar algorithm can also be used to decode the convolutional codes. Such a detection method can also be used for puncturing on both sides. For this purpose, a so-called forward recursion over the length of the puncturing pattern is carried out several times for the area of the puncturing pattern at the end of the data. Since the forward recursion is the most computationally complex part of the Viterbi algorithm, no puncturing is carried out at the end of the data in an embodiment of the invention.

As can be seen in FIG. 2, the pattern A - as seen from the two ends or edges of the data block to be punctured - has bits 2, 4, 7, 10, 14, 18, 22 and 26 at both ends of the data block punctured. In the case of pattern B, on the other hand, bits 1, 3, 6, 9, 13, 17, 21 and 25 of the respective data block are punctured, whereas in pattern C bits 1, 2, 4, 6, 8, 11, 14 are punctured and 17 are dotted.

The puncturing pattern C1 is designed such that the pattern start and the pattern end have only zeros, whereas the puncturing pattern C2 is designed such that the pattern start and the pattern end each have 8 zeros. (_0 L r to ^ p- ¹

Cn O cn o (J1 O (π φ t ^→ <er Φ α J sc Cd P_ CΛ H ö C ¹ - ι-d <P ^ Q t ^→ S PJ ti o ^y Q rt PJ Tl ≤ rt C

P CΛ Φ Φ Φ t ^→ P Φ HP φ PJ Φ PJ CΛ POP φ φ α P tr P α t ^→ PPP Φ P CΛ

PHN t ^→ tt Φ PP CΛ rt 3 3 P ¹ rt PH £ TJ PP t ^→ Φ o Φ PPP Φ

Φ H <Φ PJ P ^→ ω TJ CΛ rt PJ Φ? N • n P φ P- ^y HH PJ p ^→ rt ti f ^→ ω HPP iQ rt Φ HJ rt PJ rt PP rt rt er P CΛ φ rt tr rt Φ P ot ^→ rt Φ O Φ rt Φ PC <PPP er t ^→ PQ yQ CΛ PP Φ o 3 σ H Φ Φ P ti PP

Φ t ^→ Φ t. Φ P Φ N n <t ^→ φ cn • o Φ Φ ti tr P Φ P t ^→ Φ Φ ιQ P

TJ P Hi P Hi PP t ^→ Φ iQ <→ P tr O ti Ξ tr H t ^→ Φ Φ cn CΛ P ti _^ cn Φ

Φ 3 PJ φ OJ • PP t. CX s: Φ QO P- P Φ \ -> rt PPPP rt Φ ω CL P ti P rt o r + O CΛ 3 PJ P o Φ P ^→ PPP Φ P t ^→ rt Φ P PJ PP tr J

P 0 ⁾ tr Φ t ^→ o ιQ • → o TJ ^→ Cd O Ul ^ Q yQ n Q yQ ^y Q CΛ d rt & rt J ιQ Φ rt ⁾

Φ rt PP & t CΛ er ^ TJ α PPP ω φ Φ ö CΛ PPP CΛ & CΛ ts Φ P tf P CΛ rt 3 Φ Φ φ Φ Φ o_ P 1 N PJ <3 Φ P ^y Q CL P 3 n

P • QS CTJ yQ rt Φ PPP \ - → P CΛ PC CΛ φ Φ rt OPH f ^→ 3 rt φ PP o <tr

P Φ Φ P Φ CΛ rt → - o_ rt OPP Φ t ^→ rt ζ rt P ti <CL CΛ H Φ sQ 3 H rt P- ¹ rt Φ ö Φ α n PP yQ P yQ JP rt ≤ Φ P rt § ti tτj

Φ c_ φ & Φ rt φ ≤ 3 Φ & t yQ Φ rt H PJ Φ tr φ P CL t ^→ CΛ Φ P "s: P l- P Φ H Φ NH Φ TJ φ CΛ N ^ Q t ^→ t ^→ Φ PJ PPP ti Φ ti P rt ti P Φ P o PPP PJ t> Φ H T. PJ Φ CΛ φ P rt υ3 P rt PP α t ^→ Φ J o P ^→ t— Φ • P ro α ^ rt α P: LJ P ^{^} Hi Φ V yQ Φ Φ PPOPP tr P_ rt yQ P o P Φ P- ¹ P Cd P φ P Φ £ P φ φ M ^→ 3 s: ^y Q Φ tr CL rt CL Φ φ P rt tr rt t ^→ HP Φ p Z tr P TJ PNO o cn t ^→ Ö φ Φ rt Φ

• P rt o rt h rt Φ h ^• »φ 3 PP g §: ti t ^→ PJ CL rt P tr ^h 0 ti

3 <o! -R CΛ P P P o rt rt J tr o Φ L PJ N tr P ^ • P s: P

C_ ^y Q o PJ φ P ιQ P s: φ P Φ ≤ P _P Φ Φ PP φ rt P Φ φ P Φ P

P P_ PH φ 3 yQ o t. Φ Φ PP t ^→ P rt P Φ ti P c? 3? u Q

PP φ CL Cd Hi P er d ^y Q ro T) PH ^ Q rt tr P Φ dt ¹ - ω CΛ P rt L CΛ

CΛ t ^→ Φ o PP r α Φ P Φ PPPP Φ PJ φ ti P <Φ PH rt rt rt P Φ er 3 rt s: TJ n- tr PP iQ P rt PP ^" CΛ σs P- h Φ CΛ OP CΛ Hi J φ PP

P 3 PJ TJ CΛ H Φ φ CΛ CΛ? PJ ιQ er rt rt P rt t ^→ rt P L_l P Φ ti • CΛ

CΛ yQ P P φ rt P PJ 3 ö rt P CΛ O φ - »rt P- P Φ

- α PP rt o → - α P ^J tr PT) PP PJ Hi PH, rt 3 s: P £ Φ J P- CL CL PP s Φ p PN s: Φ P CΛ CΛ rt o φ P Φ PJ • Φ PP ti P p: ON Φ QP ti

≤ Φ P £ P 3 3 o rt Φ P ^J H C_ CΛ H tr H, t ^→ PJ ^y Q Φ PO s. 3 H

Φ Φ P ≤ yQ • H? R tr Φ P Q P; P rt H ö α P tr Φ ιQ tr P 3 CL 3

• → P P Φ α Ό rt H er rt P φ Φ PJ vQ P Φ rt P P Λ <CΛ PJ P P

CΛ P Φ t → p ^→ CL • JPP • ^y QHP Φ φ PP Hi rt φ Φ L Ω> Q et P rt

3 CL PJ P CΛ φ Φ 3 O PJ PP CΛ Φ CL rt Φ t ^→ ti P tr P PJ

P PJ Φ P φ> cn ι-f o P O IM φ 3 <PJ o φ t-i P • l- → S N φ Φ P Φ O Φ

PPP p Φ c Φ rt? P; P Φ tr J3 PP Φ h- ^y Φ PP CL P tr P ^y Q lh Φ ιQ CΛ P 3 2 cn HP w H φ 3> 3 P rt P Φ s PPP

PH PJ Φ P- ιQ α - φ t ^→ ≤ H Φ P yQ Φ Φ CL P ^J PJ CL cn Φ CL Φ

P Φ PX p ≤ M Φ o 3 c_ Φ c? PP Hi CΛ cn t ^→ PP rt tr φ rt 3 φ ti ω HP oo PHP α PJ - P to Φ P ^ ^y QO <Hi P Φ ti P PJ ti rt P ιQ er tr 0 ^ Q φ P rt t φ PJ tr OPSQ cn P ιQ yQ

P Φ Φ Φ Φ t. CΛ er P TJ Φ Φ t ^→ ≤ er t ^→ PPQO φ rt TJ Φ

^ QHP P> o er rt Φ φ P rt Φ Φ Φ P ^y Q CL CΛ <Φ tr P Φ Φ P t →

Φ TJ Φ - ^y tr P PJ Φ N Hi rt t ^→ • ^ φ PJ P rt o ≤ Φ PPPPP tf P t ^→ o_ rt P c P ^J Φ CΛ Φ P φ Φ os: & PP Φ PPPN n; P

PPQ Φ CΛ Hi P ^J PP Φ CΛ P ^J tr P ιQ ^y QHPP Φ op "rt ^y Q

^ .V φ Φ φ o PJ H 3 Φ ti P ω P TJ PP ^J - ^→ CL 3 P Φ

CD rt PJ 3 σ s α t ^→ ro P PJ o O ^y QPPP Φ P ⁾ Φ t ^→

H ? 3 Φ PJ P P o_ P 3 P P tr tr P- Φ P H o Φ H &> t-i Φ

P ^J Φ r + PP rt Φ φ Φ Φ P sQ PP <Φ 3 1? Φ - PPPP ti O H- P Φ P_ CΛ ι-f rt φ ^ Φ o α ti PJ o rt CL * QP

P t ^→ P φ Φ 0 P Φ φ t ^→ PP t> PP φ TJ Φ ^y Q TJ

P - φ M α t3 φ P CΛ N φ Φ Φ Φ N P P P P ιQ o P PJ P 1 P rt P

P rt P Φ φ Φ n Φ ti P tr 3 rt Φ

arises when the number of bits after coding corresponds exactly to the number of bits to be transmitted. If you simply use edge puncturing in this case, 8 bits are punctured at both ends (e.g. in the event that 8 bits are punctured at each end by the edge puncturing) and then repeated in conventional rate matching step 16 of the remaining bits. Simulations have shown that, at least in some scenarios, this is more unfavorable than neither puncturing nor repeating.

In addition to the method described in the previous exemplary embodiment, the following exemplary embodiment can also be used to avoid this disadvantage:

The edge puncturing is not carried out immediately after the convolutional coder, but only integrated in the rate-matchmg. The following example assumes that k bits should be punctured on both edges.

If the number of bits to be punctured is greater than 2k, then, as already described, 2k bits are punctured at the edge and then the remaining bits according to the standard algorithm m (evenly) as far as possible.

If the number of deltaN bits to be punctured is between 1 and 2k, only deltaN bits are punctured at the beginning and end. It is advisable to puncture deltaN / 2 bits at the beginning and at the end of the block, if deltaN is odd, either round up at the beginning and round up at the end or vice versa. This avoids having to repeat 2k-deltaN bits after puncturing 2k bits at the ends in the following rate matching step. In this case, no further puncturing or repetition are necessary after the edge puncturing. If bits are repeated, the end puncturing is not carried out at all.

The following method can be used as a further variant of this exemplary embodiment:

This variant divides the coded bits m into three areas em: start (length k in the example), middle and end (length k again). The rate matchmg is then carried out as follows:

If the number of bits deltaN to be punctured is between 1 and 2k, deltaN / 2 bits are punctured at the beginning and end, as in the exemplary embodiment described immediately above.

If the number of bits to be punctured is greater than 2k, then k bits are punctured at the beginning and end, the remaining puncturing is in the middle, i.e. performed in the range of N-2k bits.

If deltaN bits have to be repeated, k bits are not processed at the beginning and end, they are neither punctured nor repeated, the entire repetition is in the middle, i.e. performed in the range of N-2k bits.

The advantage of this method is that both puncturing and repetition can be carried out on the same area of the middle N-2k bits. This makes it possible to standardize the algorithm. In addition, the bits are not repeated in the end, which is advantageous since these bits carry less information.

Seen overall, in this exemplary embodiment the edge bits are preferably punctured when punctured and not repeated when repeated, that is (except in the event that neither repetition nor puncturing is to be carried out) transmitted with less weight than the bits not on the edge.

This method can also be implemented efficiently in the case where the rate matchmg is carried out after a first interleaver. This is the case, for example, in the UMTS system in the uplink, that is to say the transmission from the mobile station to the base station. The coded radio frames are first divided into different radio frames after coding, the number of these frames is denoted by F. This is done by writing the bit m a matrix with F columns, optionally a subsequent column swap. The bits are then read out in columns. It is preferable to ensure, if necessary by padding, that the number of bits is divisible by F.

If the maximum number of bits k to be punctured at each edge is divisible by F, m are available for each radio frame k / F bit at both ends for edge puncturing, the puncturing can then, according to the same method as already described, also be carried out separately for each radio frame. In particular, in the event that between 0 and 2 * k / F bits are to be punctured per radio frame, only part of the maximum number per radio frame is punctured. if the

If the number of bits to be punctured is odd, less punctuation is made either at the beginning or at the end of the bit. It is advisable to use less dots alternately at the beginning or end, at least not always at the beginning or always at the end.

If the maximum number of bits k to be punctured on each edge is not divisible by F, but 2k is divisible by F, a total of 2k / F bits are available for each radio frame for edge puncturing. The puncturing can also be carried out here analogously to the above-mentioned methods, it should be noted that with some radio frames the Number of bits to be punctured at the beginning and end can be different. If an odd number of edge punctures is to be carried out in such cases, it is advisable to puncture one more bit at the end where more bits are available.

Fig. 5 shows an exemplary puncturing according to the above. Method. It is assumed that the maximum number of bits to be punctured is k = 6 at the beginning and end, and the number of radio frames F =. In order to simplify the representation, a column swap is not assumed. In the figure, the bits potentially to be punctured during the edge puncturing are represented by a border, these are the first 6 (bits 0,1,2,3,4,5) and last 6 (bits 46,47,48,49, 50.51) bits. It is also assumed that a total of 4 bits are punctured. The bits marked in bold (bits 1,2,50,51) are punctured.

As a further exemplary embodiment, in the event that k is not divisible by F, the next smaller value of k which is divisible by F can also be used instead. In the example k = 6 and F = 4, k = 4 was selected.

FIG. 3A shows, by way of example, the course of the bit error rate for the individual transmitted bits of a data block as a function of their position or location in the data block for conventional puncturing with a regular puncturing rate of 20% (curve a) and for puncturing according to the invention with the above pattern C, in which only eight bits are punctured at the beginning and end of the data block with a puncturing rate increasing in each case to the data block edge, m combination with a subsequent regular puncturing with a puncturing rate of 10% (curve b). From Fig. 3A it can be seen that by using the puncturing pattern according to the invention, through which in particular the tail bits of the data block to be transmitted are punctured, a more uniform course of the bit error rate can be achieved over the entire data block. Since puncturing is less frequent in the central area of the data block compared to the conventional procedure, a lower probability of error can be obtained there.

3B shows the course of the total error rate over the signal-to-noise ratio (SNR) for the same cases. From Fig. 3B it can be seen that with the aid of the invention (curve b) a bit error rate which is improved by approximately 0.25 dB compared to the conventional procedure (curve a) can be achieved.

The present invention has previously been described using a cellular transmitter. Of course, the invention can, however, also be extended to mobile radio receivers where, in order to adapt the data rate in the manner described above, punctured or repeated signal corresponding to the puncturing or respectively used. Repetition patterns must be worked up. In this case, additional bits m are added to the respective receiver for punctured or repeated bits on the transmission side, or the reception bit stream is combined, or two or more bits of the reception bit stream are combined. When additional bits are inserted, it is noted in the form of a so-called 'soft decision' information that their information content is very uncertain. The processing of the received signal can be carried out in the reverse order of FIG. 1 for the respective receiver.

The patterns A to C explained above prove to be particularly advantageous in complex simulations, in particular in combination with rate 1/3 coders. For coders of rate 1/2, the patterns D to K, which result from FIG. 4, turn out to be particularly advantageous in complex simulations. The use of these patterns D through K can analogous to the use of patterns A to C and corresponding further developments explained above. As already explained above, due to the higher code rate, fewer coded tail bits are transmitted than at rate 1/3. Therefore, suitable puncturing patterns for rate 1/2 comprise fewer bits than puncturing patterns for rate 1/3.

As can be seen in FIG. 4, the pattern D shows bits 3, 5, 8 and 9 from the front end of the data block to be punctured and bits no. 2 from the rear end of the data block to be punctured. 5, 6 and 8 dotted.

For patterns E and F, the same puncturing pattern is used from the rear end as for pattern D.

Patterns E punctuate bits 3, 5, 9 and 10 from the front end of the data block to be punctured.

Pattern F punctures bits 3, 5, 6 and 10 from the front end of the data block to be punctured.

The patterns G to I use the same at the front end

Puncturing patterns like the patterns D to F, but seen from the rear end of the data block to be punctured, bits 3, 5, 9 and 10 are punctured.

Pattern J punctures bits 1, 3, 5 and 8 at both ends of the data block, as seen from the two ends or edges of the data block to be punctured. In the case of pattern K, on the other hand, bits 2, 4, 8 and 11 of the respective data block are punctured from the two ends or edges of the data block to be punctured. For data blocks with very few bits, for example only 3 transmitted bits, there is no distribution of the bit error rate (BER) depending on the position of the bit, as explained above, since all 3 bits are on the "edge" and are better protected against errors there. There are, so to speak, no bits that lie in the "middle". For such short blocks, with conventional coding - due to the construction principle of the convolutional codes - there are also transmitted bits that have a fixed value of 0, that is to say carry no information. An embodiment variant of the invention now provides for the pattern to be selected such that, in the case of such short blocks, these bits are preferably punctured without any information content. The same pattern can be used for these very short blocks as well as for longer blocks, which facilitates a uniform implementation for all block sizes.

Another embodiment of the invention provides for an optimization of the Hammmg distance, or generally an optimization of the weight distribution, for very short blocks. With long codes, the weight distribution depends primarily on the polynomials used; with short codes, a code with good weight distribution can be generated by suitable puncturing patterns.

In connection with a UMTS, the data in the Uplmk can be distributed over 1, 2, 4 or 8 frames of length 10 ms. If the number of bits after coding is not divisible by 1, 2, 4 or 8, a corresponding number of dummy bits is inserted in embodiment variants which can be combined with the configurations explained above, in order to ensure an even distribution of the bits to allow the frames. A further advantageous embodiment provides for the end puncturing pattern to be shortened accordingly instead of adding dummy bits. As a result, additional bits can be used for transmission and at the same time a number that can be divided by the number of frames generated by bits. In contrast to the dummy bits, the unpunctured bits carry information and thus contribute to improving the transmission.

The puncturing pattern is thus shortened in such a way that a number results as the length of the data block after the puncturing, which enables the subsequent data processing to be carried out efficiently.

This can be achieved in particular that the

Puncturing pattern is shortened in such a way that the length of the data block after puncturing can be divided by the number of frames over which the data block is distributed (mterleaved)

Of course, a combination of the above-mentioned criteria is also possible when selecting a puncturing pattern. For example, if patterns D to I are used, all bits without information content are punctured at the rate 1/2 code for 3 bits currently proposed for UMTS and em code with optimal weight distribution is generated from the remaining 14 bits transmitted. Even with 2 bits transmitted, pattern D punctures all bits without information content. If only one bit is transmitted, 4 out of a total of 6 bits are punctured without any information content.

At the same time, these patterns also show good properties with longer block sizes (e.g. 32 bits).

Claims

claims

1. A method for adapting the data rate in a communication device, comprising puncturing a data block

Data stream according to a certain puncturing pattern, so as to adapt the data rate, whereby puncturing removes bits corresponding to the puncturing pattern from the data block, characterized in that the puncturing is carried out with a puncturing pattern which extends from a central region of the data lock to at least one end of the data block h has a steadily increasing puncturing rate.

2. The method of claim 1, d a d u r c h g e k e n n z e i c h n e t that the puncturing rate of the puncturing pattern in the middle

The area of the data block is essentially 0 °.

3. The method of claim 1 or 2, so that the puncturing is carried out with a puncturing pattern which has a steadily increasing puncturing rate from the central region of the data block to both ends of the data block.

4. The method according to any one of the preceding claims, characterized in that the puncturing pattern comprises a first pattern section for the start area of the data block, a second pattern section for the central area of the data block and a third pattern section for the end area of the data block, and that the puncturing pattern is designed in such a way , that the

Dotting of the first pattern section is mirror symmetrical to the dotting of the third pattern section.

5. The method according to any one of the preceding claims, d a d u r c h g e k e n n z e i c h n e t that several successive data blocks of the data stream are punctured with the same puncturing pattern.

6. The method according to any one of claims 1-4, d a d u r c h g e k e n n z e i c h n e t that the puncturing pattern m is adjusted depending on the length of the data block to be punctured accordingly.

7. The method according to claim 6, d a d u r c h g e k e n n z e i c h n e t that the puncturing pattern for a data block, the length of which is smaller than an predetermined limit value, is shortened.

8. The method according to any one of the preceding claims, characterized in that the puncturing pattern is designed such that the puncturing, viewed from the corresponding end of the data block to be punctured, bits No. 2, No. 4, No. 7, No. 10, No. 14, No. 18, No. 22 and No. 26 of the data block can be removed.

9. The method according to any one of claims 1-7, characterized in that the puncturing pattern is designed such that the puncturing, viewed from the corresponding end of the data block to be punctured, bits No. 1, No. 3, No. 6, No. 9, No. 13, No. 17, No. 21 and No. 25 of the data block are removed.

10. The method according to any one of claims 1-7, characterized in that the puncturing pattern is designed such that by the puncturing, from the corresponding end of the Considering puncturing data blocks, bits No. 1, No. 2, No. 4, No. 6, No. 8, No. 11, No. 14 and No. 17 of the data block are removed.

11. The method according to any one of claims 1-7, d a d u r c h g e k e n n z e i c h n e t that the puncturing pattern is designed such that the puncturing, viewed from the front end of the data block to be punctured, each bits No. 3, No. 5, No. 8 and No. 9 and, viewed from the rear end of the data block to be punctured, bits No. 2, No. 5, No. 6 and No. 8 of the data block are respectively removed.

12. The method according to any one of the preceding claims, characterized in that the data block to be punctured comprises data encoded with a convolutional code, the convolutional code having a code rate 1 / n and a constramt length K, and in that the puncturing pattern is designed such that the Puncturing from a start and / or end area of the data block, which is inserted when coding with the convolutional code tail bits, less than n * (Kl) bits are removed.

13. The method according to any one of the preceding claims, d a d u r c h g e k e n n z e i c h n e t that the puncturing pattern is designed such that less than n * (K-l) / 2 bits are removed from the starting area and the end area of the data block by the puncturing

14. The method according to any one of the preceding claims, characterized in that after puncturing the data block em further puncturing process by which bits are removed from the already punctured data block according to a further puncturing pattern, or em Repetition process by which bits are doubled in the already punctured data block according to a certain repetition pattern.

15. The method according to claim 14, so that the further puncturing pattern of the further puncturing process or the repeating pattern of the repeating process corresponds to an approximately regular puncturing or repetition of the already punctured data block.

16. The method according to any one of the preceding claims, characterized in that the bits of the data block are first multiplied prior to puncturing, wherein certain bits of the data block, which are selected according to the puncturing pattern, are multiplied at a lower rate than the other bits of the data block, and that the bit stream of the data block resulting from this multiplication is then punctured with a puncturing rate such that a desired repetition rate results.

17. The method according to any one of the preceding claims, d a d u r c h g e k e n n z e i c h n e t that the puncturing pattern is designed such that the pattern start and the pattern end has only zeros.

18. The method according to any one of the preceding claims, d a d u r c h g e k e n n z e i c h n e t that the puncturing pattern is designed such that the pattern start and the pattern end each have 8 zeros.

19. The method according to any one of claims 1 to 17, characterized in that the puncturing pattern is designed such that the pattern start and the pattern end each have 9 zeros.

20. The method according to any one of claims 1 to 17, so that the puncturing pattern is designed in such a way that the pattern start and the pattern end at a rate 1 / n convolutional encoder each have a multiple of n zeros.

21. The method according to any one of claims 1 to 17, so that the puncturing pattern is designed in such a way that the beginning and end of the pattern have 6 or 9 zeros at a rate 1/3 convolutional encoder.

22. The method according to any one of claims 1 to 17, so that the puncturing pattern is designed such that the pattern beginning and the pattern end at a rate 1/2 convolutional encoder each have 4 or 6 zeros.

23. The method according to any one of claims 1 to 17, d a d u r c h g e k e n n z e i c h n e t that the puncturing pattern is designed such that the beginning and end of the pattern in a system with a rate 1/2 and a rate 1/3 convolutional encoder each have 6 zeros for both codes.

24. The method according to any one of the preceding claims, characterized in that the data block is a first or a last data block of a plurality of data blocks which results from the segmentation of a larger data block, with only the beginning or the end of the first or last data block is punctured.

25. The method according to any one of claims 1 to 23, characterized in that the method is only used if the data blocks are not segmented into several blocks for coding, for example due to their size.

26. The method according to any one of the preceding claims, that the number of bits to be punctured at the ends is reduced if the total number of remaining bits has otherwise fallen below a predetermined value.

27. The method according to any one of the preceding claims, characterized in that mm (deltaN / 2, k) bits are punctured at both ends, deltaN representing the number of bits to be punctured and k representing the maximum number of bits to be punctured at an edge ,

28. The method according to any one of the preceding claims, d a d u r c h g e k e n n z e i c h n e t that if the number of bits deltaN to be punctured is greater than 2k, 2k bits are punctured first on both edges and subsequently punctured deltaN-2k bits according to a further puncturing pattern.

29. The method according to any one of the preceding claims, characterized in that when the number of bits deltaN to be punctured is between 1 and 2k-l, deltaN / 2 bits are punctured on both edges, in the event that deltaN is odd, the Expression deltaN / 2 is rounded up at one edge and rounded off at the other.

30. The method according to any one of the preceding claims, characterized in that if a repetition is to be carried out in total, the first and last k bits of this repetition be excluded and the repetition is only applied to the remaining bits m in the middle.

31. The method according to any one of the preceding claims, that the coded bits m are divided into the three areas beginning (length k) middle and end (length k) and the rate adjustment is carried out according to the following rule:

- If bits are to be repeated, only bits in the middle part are repeated, but none in the beginning and

end;

- If the number of bits deltaN to be punctured is between 1 and 2k, deltaN / 2 bits are punctured at the beginning and end; - If the number of bits to be punctured is greater than 2k, then k bits are punctured at the beginning and end, the remaining puncturing is carried out in the area of the middle, in particular in the area of the N-2k bits.

32. The method according to any one of the preceding claims, that the puncturing is carried out separately for each radio frame after a first interleaver that distributes the bits to F radio frames.

33. The method according to claim 32, d a d u r c h g e k e n n z e i c h n e t that in the event that the number of bits to be punctured per radio frame is odd, an additional bit is punctured partially at the beginning or end of an additional bit.

34. The method according to claim 33, characterized in that the number of maximally km to be punctured at the edges km is selected depending on the number of radio frames F such that k is divisible by F.

35. Communication device, with a puncturing device (6) for puncturing a data block of a data stream supplied to the puncturing device (6) in accordance with a specific puncturing pattern in order to adapt the data rate of the data stream, the puncturing device (1) by puncturing the bits corresponding to the puncturing pattern from the data block removed, characterized in that the puncturing device (6) is designed such that the puncturing is carried out with a puncturing pattern which has a continuously increasing puncturing rate from a central region of the data block to at least one end of the data block hm.

36. Communication device according to claim 35, so that the communication device (1) or the puncturing device (6) is designed to carry out the method according to one of claims 1-34.

37. Communication device according to claim 35 or 36, so that the communication device (1) is a mobile radio transmission or mobile radio reception device, in particular a UMTS mobile radio transmission or UMTS mobile radio reception device.