DE10229640A1 - Rate adjustment procedure - Google Patents

Abstract

Method for adapting the rate to a defined data rate, DOLLAR A - in which the data whose data rate is adjusted is composed of at least two coded data streams, and DOLLAR A - in which the rate adaptation of the data rates of the at least two data streams to the defined data rate using a Rate adjustment pattern takes place, via which the scheme for repeating or puncturing individual data sequences from the data streams is determined and which is the same for the at least two data streams.

Description

The present invention relates to a method for rate adaptation, in which the bit rate of data streams to a fixed bit rate, for example of a physical channel, is adjusted.

Transmission channels in mobile radio systems offer, for example, because of their embedding in broadcast formats only fixed data or raw data transfer rates, while the Send and receive data rates of different signals or applications differ. Hence it is in general necessary to adapt the data rates to each other at an interface.

Such an adjustment or rate adjustment is described below using an example from the UMTS standardization:
In UMTS (Universal Mobile Telecommunication System), data packets are sent to a mobile station (UE = User Equipment) via the "High-Speed Downlink Shared Channel" (HS-DSCH). The associated control information is transmitted via the "High-Speed Shared Control Channel" (HS-SCCH), such as the channelization codes used for the HS-DSCH, which are codes with which transmissions are spread in a recipient-specific manner and the modulation scheme, for example QPSK ( Quadrature Phase Shift Keying) or 16QAM (16 Quadrature Amplitude Modulation). So that the receiving mobile station can recognize that the information on the HS-SCCH is intended for it, this control information or this user data is linked to identification information. In this context one speaks of a masking of the data. Before the link, both the useful data and the identification data are encoded and a subsequent rate adjustment is carried out.

However, this process is correct complex, which is disadvantageous in particular in the case of the mobile radio terminal, when these coding and rate adjustment operations are resolved, to get back to the original (Useful) data to come.

Based on this state of the art It is an object of the present invention to adjust the rate one that is shared by several communication participants Low complexity channel perform.

This task is accomplished through a process according to the characteristics of the independent Claim 1 solved. Advantageous further developments result from the dependent claims.

The essence of the invention is in the Overall coding of one used by several communication participants Channel rate adjustment for User data and identification data, with whose help identified is for who the data is intended to design according to a common scheme.

This has the advantage that the complexity of the decoding especially on the receiving end becomes lower.

Another aspect of the invention aims to design a rate adjustment pattern which the rate adjustment for User data and identification data according to a common scheme if possible keeping the original good Information allowed. A rate adjustment pattern indicates which bits repeated or shortened (dotted) from a data sequence be the one you want Get data rate.

Advantages and configurations of the In the following, examples of the invention are illustrated, partly with reference to figures explained.

Show it

1 an overview of the overall coding for a channel in which the data to be transmitted are masked using the identification data;

2 a diagram illustrating individual processes in the overall coding;

3 the previous implementation of the overall coding in the HS-SCCH according to the prior art;

4 an embodiment of an inventive implementation of the overall coding in the HS-SCCH;

5 an exemplary implementation on the receiver side for receiving the HS-SCCH in the currently used specification (release 99 );

6 an embodiment of the implementation on the receiver side in an overall coding according to the in 4 shown proposal.

Overall coding of useful and identification data

1

In 1 An overall coding for user data (LD: load data) and identification data (ID: identification data), which are sent via a shared channel in a communication system, can be seen schematically. Transmitted data (TD: Transferred Data) are composed of user data LD, which are linked to the identification data ID, in order to identify the recipient for which the transmitted data TD are intended. The linking of user data LD and identification data ID takes place in the context of an overall coding (CC: Channel Coding), usually a channel coding. Channel coding is understood to mean the adaptation of digital values to the physical transmission medium, that is to say, for example, coding with subsequent rate adaptation.

Under overall coding in this Case coding, rate adjustment and linking of the user and identification data Roger that. However, it is not imperative that everyone steps listed take place, the overall coding can for example also in one Coding exist alone without rate adjustment.

This in 1 The scheme shown is known per se, however, the prior art and the invention differ in the procedure for the overall coding.

2

In 2 individual process blocks of the overall coding CC are broken down. The user data LD are first subjected to a coding C_LD. In the context of this coding, for which convolutional codes in particular are used, LD redundancy is added to the useful data, as a result of which a more reliable recovery of the transmitted data TD in the event of transmission errors is possible on the receiver side. The code used in the encoding is characterized by its code rate R = K / N, where K denotes the number of data or message bits to be transmitted and N the number of bits present after encoding. The lower the code rate, the more efficient the code is. A problem associated with the coding, however, is that the data rate is reduced by the factor R and the information is therefore packed more densely and a partial loss can therefore be more problematic than with less densely packed information.

At the data rate of the encoded data stream to the respective possible transmission rate rate matching (rate matching) RM_LD carried out, according to a certain pattern either bits from the data stream removed or repeated in the data stream. The removal of Bits is called "puncturing" and repeating referred to as "repeat" by bits.

In an analogous way, the identification data ID first a coding C_ID and then a rate adjustment RM_ID subjected. This is followed by identification data and user data in a linking process L linked together whereby the to be transmitted Data TD are formed.

This in 2 The procedure shown is known in principle, but the state of the art and the invention differ in the implementation of the rate adjustment for user data LD and identification data ID.

3

In 3 is the implementation of the overall coding of the HS-SCCH part 1 according to the current specification UMTS standard (FDD, Release 5 ) mapped. The user data LD are formed by the channel information bits x _{ccs, 1} , x _{ccs, 2} , ..., x _{ccs, 7} . The channel information bits are referred to in specialist circles as "channelization code set bits". Furthermore, the modulation scheme bit x _{ms, 1} which is also referred to as "modulation scheme bit", is incorporated into the user data. This user data is processed with a rate 1/3 convolutional encoder in accordance with the 1999 standard (release 99 ) encoded. Eight tail bits attached before this coding at the end of the bit block enable easier and more reliable decoding on the receiver side. The multiplexer MUX enables an alternate polling of channel information bits X _{cc s} and the modulation scheme bit X _ms . The entirety of the data present after the multiplexer is referred to as X ₁ .

Thus there are 16 bits on the input side of the encoder or encoder or before the coding process C_LD, while on the output side of the encoder or after the coding process C_LD there are 48 bits due to the rate 1/3. This coded bit block is referred to as Z ₁ . The index 1 means here that it is a size which is the part 1 (Part 1 ) concerns the HS-SCCH. The part 1 this control channel contains data which the receiver must decode immediately in order to process incoming data on the HS-DSCH (HS Downlink Shared Channel) accordingly. The data of the part is correspondingly present 2 (Part 2 ) less time critical.

On the physical channel, that is, the actual transmission channel, stand for the part 1 of the control channel HS-SCCH only 40 bits are available for transmission. To get from 48 bits to the 40 bits that are in part 1 can be physically transmitted, a rate adjustment takes place according to the following rate adjustment pattern 1 ): From the bit block or the sequence Z ₁ , which results from the coding process C_LD, the bits at the positions 1 . 2 . 4 . 8th . 42 . 45 . 47 . 48 punctured. If a notation with a second index j is used, which identifies the bit position and runs from 1 to 48 in the case shown, then the bits to be punctured can be specified as Z _1.1 , Z _1.2 , Z _1.4 , Z _{1 , 8} , Z ₁ , ₄₂ , Z _1.45 , Z _1.47 , Z _1.48 . As before, the first index indicates that it is part 1 of the HS-SCCH. This spelling is then in 3 after the rate adjustment process the sequence R _1.1 R _1.2 , ... R _1.40 before.

The control channel HS-SCCH is intercepted by several mobile stations or mobile radio terminals (UE: User Equipment). To identify the mobile station UE in question, or so this mobile station does the part 1 can decode and so that a mobile station that is not addressed recognizes this, the user data, consisting of channel information data and the modulation scheme, are identified by the identification data or a specific mask that is dependent on the identification number of the mobile station.

In the case shown here, based on the 16-bit identification number of the mobile station (UE ID) using rate ½ coding according to the 1999 standard (release 99 ) generates a so-called scrambling code specific to the identification number of the mobile station, with which the user data is masked. The identification number of the mobile station UE ID is assigned to the mobile station in the respective cell by the respective base station. Scrambling is therefore a "personalization" of the information. This is done using the so-called "scrambling codes", with which the signal is modified in order to separate or separate signals for individual terminals or base stations.

To generate the scrambling code, the 16 bits of the identification number of the mobile station UE ID X _{ue, 1} , ... X _{ue, 16} and the attached eight tail bits are used in accordance with the 1999 standard (release 99 ) encoded with the rate ½ convolutional encoder (C_ID). This also results in (16 + 8) x2 = 48 bits of a sequence B at the output of the convolutional encoder. In order to achieve a length of 40 bits here, the rate adjustment algorithm from the 1999 standard (Release 99 ) used for puncturing (RM_ID), in which of the sequence B, consisting of bits b ₁ , b ₂ , ... b ₄₈ , where the index indicates the bit position, bits b ₁ , b ₇ , b ₁₃ , b ₁₉ , b ₂₅ , b ₃₁ , b ₃₇ , b _{43 can be} punctured. The sequence C thus formed, consisting of bits c ₁ , c ₂ , ... c ₄₀ , results in the necessary reduction from 48 bits to 40 bits.

So there are LD for the branch of the user data and the branch of the identification data ID for their respective rate adjustment RM_LD or RM_ID different rate adjustment patterns used. The reasons are as follows:

• - in the Generally lie in the branch with the identification data ID or not in the branch with the user data LD after the coding level same number of bits before. This can be due to the number of output bits, this means the number of bits of the identification number of the mobile station or channel information or modulation information bits lie, as well as the rate of coding. This is inevitably one different rate adjustment required.
• - The coding in the coding stage C _{L D} or C _ID serves, inter alia, to interleave the bits with one another, so that the original bit sequence X _i or X _{U E} can be restored on the receiver side even in the case of poor transmission conditions. A good entanglement in this sense naturally looks different for different or differently structured input data X _ue or X _i (= X _{cc S} or X _ms ), especially when different coding rates are used. As a result, individual bits have different importance after the coding stage. This different importance depends on how many input bits of the coding stage an output bit of the coding stage is associated with. The more input bits flow into the output bit, the more important the output bit is to restore the original data. In the case of a rate adjustment pattern, in the case of puncturing data, bits are preferably punctured which are of less importance in this sense.
• In other words, lead with different coding, for example with different ones Convolutional encoders and subsequent Rate adjustment different rate adjustment patterns to different Distance properties regarding the Hamming distances of the resulting code sequences or code words and determine thus the performance the coding.

The use of different rate adjustment patterns and the associated re Space and memory requirements are only a minor problem in the base station, since the appropriate hardware is available there to handle even complex computing processes. However, this does not apply to the receiving mobile station.

As already mentioned above, the aim of the invention is to make the overall coding, in particular the rate adjustment, less complex than it is currently, that is to say the specification according to the release 5 the case is.

A main aspect of the invention is going to adjust the rate for Identification data ID and user data LD according to a common To make rate adjustment patterns.

There are basically two approaches to this conceivable:

• i) the use of a common rate adjustment pattern, but separate implementation the rate adjustment for User data LD and identification data ID.
• ii) The use of a common rate adjustment pattern and the joint implementation the rate adjustment.

4

In 4 a process sequence designed according to solution ii) is now shown, also for the example of the control channel HS-SCCH. In this case, the identification data ID, here referred to as the identification bit sequence X _ue , and the channel information data, here X _ccs and X _ms , are linked with one another after the respective coding C_LD or C_ID and then subjected to a common rate adjustment. The linking is done, for example, by an XOR function, if one defines the two values that a bit can take with 0 and 1. If the values - 1 and 1 are assumed, the link can be made by multiplication. However, other bitwise links can also be used.

In 4 become, analogous to in 3 , the data resulting from the coding process designated Z ₁ .

In deviation from 3 Here the bit block or the bit sequence or the sequence R ₁ denotes the data before the common rate adjustment, but after the combination.

By proceeding according to the solutions i) or ii) the following advantages are achieved: Because the rate adjustment is done with just one rate adjustment pattern the decoding in the receiver, for example, the mobile station UE, correspondingly easier. A less complexity is already achieved when the rate adjustment for identification data ID and User data LD is carried out separately according to the same pattern (Solution i).

According to solution ii) the rate adjustment summarized, this means a further simplification.

Various Rate matching pattern

Another aspect of the invention is the design of a rate adjustment pattern, which can be seen as a common Scheme for Usable data LD and identification data ID are approximately equally suitable. An important aspect here is, among other things, that the Hamming distance or the Hamming distance after linking if possible is great for example the linked ones Data in the event of a faulty transmission if possible to be able to reconstruct well.

"Hamming distance" means the number of bits by which two code words of equal length differ from one another. This is used for error detection by receiving data units with valid Characters are compared. Any correction is made after the principle of probability.

To continue the information content the user data LD if possible A good Hamming distance is also desirable here. These and others Criteria such as the signal-to-noise ratio however not necessarily independent of each other, which among other things can lead, that trying to make an "optimized" rate adjustment pattern to find multiple, different rate adjustment patterns leads, those in mathematical speech possibly also as secondary minima of the optimization problem could be called.

Among other things, pointing to the common Rate adjustment pattern some variants special advantages:

a) Using the current puncturing algorithm (Release99):
In the sequence r _1.1 , r _1.2 , ..., r _1.48 , the bits r _1.1 , r _1.7 , r _1.13 , r _1.19 , r _1.25 , r _1.31 , r _1.37 , r _1.43 punctured, and thus the sequence s _1.1 , s _1.2 ... s _{1.40 is obtained} . This has the advantage that only minor adjustments to the currently used system have to be made.

This puncturing pattern - like other rate adjustment patterns - can be shifted, for example by an offset (offset) 0 <= k <6. This means that for the case of the standard from 1999 (Release99), the bits r _{1 + k} , r _{7 + k} , r _{13 + k} , r _{19 + k} , r _{25 + k} , r _{31 + k} , r _{37 + k} , r _{43 + k} . The size of the storage k is determined by the distance between the last bit position to be punctured and the last bit position. So the last bit to be punctured is at the position 42 With a total length of 48 bits, the puncturing pattern can be shifted back by a maximum of 6 positions.

b) This is used as a puncturing pattern for the user data of the part 1 of the HS-SCCH optimized puncturing pattern "Pattern 1" [1] uses:
From the sequence r1.1, r1.2, ..., r1.48, the bits r1.1, r1.2, r1.4, r1.8, r1.42, r1.45, r1.47, r1 , 48 dotted, and the sequence s1.1, s1.2 ... s1.40 is thus obtained. This variant is particularly advantageous because it optimally encodes the HS-SCCH data and, moreover, the sequences for masking the data in the code space are at a greater distance from one another, i.e. a greater Hamming distance than with puncturing according to the Release99 puncturing algorithm.

c) A new puncturing pattern, which also encodes the coding properties of the data of the part 1 of the HS-SCCH and the recognition possibilities of the masking with the UE ID can be solved by an optimization, whereby the secondary conditions are predetermined by the data structure in the identification data branch and in the user data branch.

With such an optimization will first a target function is formed in which the size to be optimized is mapped becomes. Considering the constraints caused by the system are then for these Target function sought an extremum, for example the target function minimized.

As a target function to be minimized the overall probability of error P (E) of detection is used for optimization and the correct decoding of the user data of the user data branch:

P (E) = P (not detected) + P (not decoded). (1) Detection is understood here to mean that the decision based on the scrambling with identification data that the packet is intended for the mobile station is made correctly. that, that is. This objective function can be calculated or approximated under system-related boundary conditions, such as the number of channels to be observed, or boundary conditions of the control channel allocation. Based on the usual detection criteria and decoding algorithms specifically proposed for this, a rate adaptation pattern is then sought which minimizes the target function.

This is in the following using the example of an application of the part 1 of the HS-SCCH explained.

For the special case of the control channel HS-SCCH is used for decoding requires much less energy than for detection, so that in the above formula (1) P (E) by P (not detected) can be approximated. P (not detected) sets due to the above Boundary conditions from three linear terms together, terms higher In the following, order becomes due to its negligible Neglected influence:

Die Terme setzen sich hierbei im Einzelnen zusammen aus: P (E) ≈ P (not detected) = P (FA) -1 , + P (MD) + P (FA), (2) where P (FA) denotes the overall false alarm probability and P (MD) denotes the non-detection probability. The Tiefindex -1 indicates the influence of the previous time step. For the special case of four control channels, the procedure after the "consecutive scheduling calls" and a random decision for a control channel, if more than one can meet the detection criteria, Eq.

The terms are made up of:

• 1) The triple false alarm probability from the previous time period: False alarm probability is the case when the mobile station incorrectly assumes that the data packet is intended for it, although it is actually intended for another or no mobile station. This contribution comes about as follows: If the mobile station incorrectly selected a different HS-SCCH than the HS-SCCH on which the information is currently being transmitted from the base station due to a false alarm in the previous time period (also called TTI, Transmission Time Interval) thus the mobile station can use all resources for the current time slot which are required for "listening" to the other, unselected HS-SCCH's for other tasks. This stems from the fact that the standard provides for the case that from a base station data is sent to a mobile station, the same HS-SCCH is always used in successive time steps. In this context one speaks of the so-called "consecutive scheduling rule". This leads to an on Saving resources in the mobile station, but has the side effect that an error in the previous time step also has consequences for the current time step.
• 2) The non-detection probability in the current time period. This simply means that the mobile station does not recognize that the message for it is determined.
• 3) 1.5 times the false alarm probability from the current time interval. This contribution comes about when the Mobile station in the current time step due to a false alarm falsely selects two HS-SCCHs, this means So that because of z. B any transmission errors both HS-SCCH's with the same UE ID seem to be masked. While the information is currently being transmitted on one of the HS-SCCHs will be over transmit the other HS-SCCH information for another mobile station. The mobile station must then select one from these two candidates. Here it is assumed for the sake of simplicity that one happens to be of the two candidates selected becomes. Since there are up to three competing HS-SCCH channels in addition to the correct channel, the factor is 1.5 = 3/2. Should go to Differentiation of the candidates further criteria can be used can, this factor can possibly be reduced.
• In the following, criteria are given as examples which can be decided which of several potential HS-SCCH channels the correct one is:  - The Channel that is most likely to be decoded, or where the decoding metric is smallest.  - possibly are not all possible Useful data useful for a given network configuration or mobile station applicable. For example can the channel information bits are a number of for subsequent data transmission indicate signaled codes that are greater than the number of Codes which the mobile station supports or which are currently in the Base station are configured. Such an assignment indicates this indicates that the channel information bits were received incorrectly and consequently the corresponding HS-SCCH can be discarded. something similar applies to the modulation scheme bit if it is an unsupported modulation type displays.

Based on this objective function the following puncturing pattern appears to be particularly suitable. Are the positions where the bit punctures for better readability is marked with 0, positions at which no puncturing are marked with 1: 011101101011111111111111111111111111111100011101

Simplify decoding on the receiving end

As already stated, the proposed simplification of the rate adjustment in particular on the Receiving end for example in a mobile station, due to the smaller number complexity decoding a big one Advantage.

Differences in decoding, as they currently are takes place and how according to the invention can be done are set out below.

5

In 5 An example implementation can be seen in the receiver device as it is in the current specification (release 99 ) is required. The transmitted data TD is received via the air interface AI (Air Interface). These transmitted data TD are demodulated in the demodulator Demod. After demodulation, this data is fed directly to a bit error count unit. On the other hand, this data is linked to the masking data, for example by an XOR connection or a multiplication. The masking data are generated in the mobile station from the identification number of the mobile station UE ID, which is encoded and then subjected to a rate adjustment (RM2). This is followed by the link with the demodulated, transmitted data TD. The rate adjustment RM2 of the masking data is required in order to match the bit lengths of the masking data to the bit length of the received data TD.

A reversal of the rate matching is performed before decoding RM1 ^-1 Dec for the associated signal. This data is decoded and re-encoded to check whether the information was intended for the respective receiving mobile station and subjected to a further rate adjustment RM1 before it is linked again with the masking data. The result of this new combination also flows into the bit error count unit. The detection of the errors is based on processing 40 bits, i.e. as many bits as are transmitted via the air interface AI per HS-SCCH frame (HS-SCCH subframe), which consists of three so-called slots or time slots.

6

In 6 two exemplary implementations can be seen which can be used with a rate adjustment carried out according to the invention.

In the picture above (DEC_40) the is based Bit error detection in the bit error count unit Bit Error Count as well to 40 bits. Due to the ID and User data LD used the same rate adjustment pattern Rate adjustment only together with those received and transmitted via the air interface Data TD, immediately before the bit error count unit Bit Error Count.

In this way, compared to the prior art, a rate adjustment is saved, namely that as from 5 can be seen, the masking data before a link to the received data.

The details are in 6 The following steps are shown in the example above (dec 40):
The transmitted data TD are received via the air interface AI. After a demodulation process Demod, the data are split up and, on the one hand, flow directly into a bit error count unit Bit Error Count in a first branch. In the other branch, the rate adjustment RM- ^{1 is} canceled or canceled and then linked to the masking data, which are generated by coding the mobile station identification number. In contrast to that in 5 The implementation shown does not require a rate adjustment of the masking data, since the rate adjustment of the transmitted data was undone before the link was made.

The linked data is decoded in a decoding process Dec. On the one hand, the required data is then available Data before, on the other hand, this data is in a further encoding process Subjected to coding and linked again with the masking data. This happens for the purpose of error detection in the bit error counter Bit error count, in which this data after the reconnection as well flow a rate adjustment process RM.

In summary, compared to that in 5 implementation shown saved a rate adjustment. This is made possible by using a common rate adjustment pattern for user data LD and masking data ID in the transmitter. If different rate adjustment patterns are used, the common rate adjustment in the rate adjustment unit RM in 6 for example, do not lead to the original signal in front of the bit error counter.

Even clearer improvements, namely the saving of two rate adjustments, are shown in the image below 6 implementation shown.

Based on the image below (dec_48) the detection of bit errors on 48 bits. In this case it is only the undo the rate adjustment. A further rate adjustment is no longer required.

In detail, in the illustration below 6 The following steps are carried out: The transmitted data TD are received via the air interface AI. Subsequently, the rate adjustment RM- ^{1 is} canceled, which is necessary because, on the one hand, the data is passed in a first branch directly to the bit error counting unit Bit Error Count, in which the bit error detection takes place on the basis of 48 bits.

On the other hand, in a second branch, this data is linked to the masking data generated in the mobile station from the mobile station identification number UE ID. After the linking and a subsequent decoding Dec, the required data are then available. Analogous to the example above, the data is subjected to a coding coding for the subsequent error detection and then linked to the masking data. A rate adjustment after the link is in contrast to the example above in 6 not necessary, since there are 48 bits, on the basis of which the error detection also takes place.

So in this implementation no rate adjustment required.

In general, the detection can be supported by further criteria or based on entirely different criteria. These criteria are explained below: As for the detection of the HS-SCCH, Part 1 The false alarm probability is also an important factor, for example a combination, for example a logical AND operation of the bit error counter with a so-called status criterion. This state criterion assumes data only if the best decoding metric occurs in a decoding state, which is an element of a predefined set of states. Decoding metric is a measure of the decoding probability.

To determine the best decoding metric a data record often becomes a so-called Viterbi decoder used. The following statements therefore refer to such a Viterbi decoder, let but apply accordingly to other decoding algorithms generalize. Generally, a Viterbi decoder compares that received data record with all potential Records the predefined set of states and then selects the data sequence, which is the most likely with the actually transmitted Match data sequence.

The Viterbi decoder or decoder is widely used for decoding convolution encoded data used. It calculates a set of states for each bit position, the number of which depends on the so-called influence length Le. Each state then corresponds to a possible value of the last Le bits under consideration. A metric is calculated for each state, which represents a measure of the probability that this state or the associated bit sequence is the one that is actually transmitted.

As already described, in Coding process based on the actual data, so-called tail bits, which generally have the value 0. This has the consequence that at the end of the decoding, one assumes an ideal decoding that Zero state, in which the last Le bits are assumed to be 0, the most likely should be. In the simplest case, the state set contains for the Final state in which it is assumed that the data packet is actually for the mobile station is determined, only the zero state. Then the criterion also called zero-state criterion. The mobile station then only assumes that the data packet is intended for it is when actually at the end of decoding the zero state as the most likely it turns. Otherwise the mobile station assumes that the packet not for it is determined. This criterion is used in particular for lowering the false alarm probability. In other words, compares the mobile station a priori information for this criterion, namely the known fact that the tail or end bits are 0, with the value of these bits, which can be decoded without use of this knowledge. A match is then used as an indication that the entire coding is consistent and therefore is correct.

The use of the zero state criterion leads however when using the rate adjustment pattern of the data, which in particular many bits in the area of the bits at the end, which belong to the tail bits dotted, to a higher one Non-detection probability than, for example, using a rate adjustment pattern, which less or none of the last bits in the data block punctured. In principle, there is a way to avoid this deterioration two possibilities:

• 1. The zero state criterion is expanded to a 'best state' criterion and the presence of data is assumed as soon as the best decoding metric occurs in a state which is contained in a predetermined set of states M, for example in addition to the state 0 (that is ... 00) also the states 1 (that is ... 01) and 2 (that is ... 10) of the 256 possible states of the Viterbi decoder with influence length 9 , However, this procedure can lead to a slightly higher probability of false alarms. For the individual case, it must be weighed up whether a slightly increased probability of false alarms or a slightly higher probability of non-detection is more favorable.
• 2. A rate adjustment pattern specially optimized for the two above-mentioned detection criteria is used. Such an optimized rate adjustment pattern is characterized by the fact that it punctures as little as possible in the area of the end or tail bits. In extreme cases, the entire tail area is not punctured. at 8th Tail bits and a coding rate R = 1/3 coding result in 3 * 8 = 24 bits that are not punctured. This tail area is characterized by the fact that it depends on fewer and fewer data bits, particularly in the case of the last bits. As a result, the bits in the tail area are increasingly correlated. On the one hand, these bits are then less helpful for decoding the data by a decoder. On the other hand, these bits are then better suited for the detection of differences in a mask, ie the identification data. Bits that do not contain any information at all would be ideal for this, but on the other hand this would represent a waste of bits in the decoding.

It makes a good compromise represents the bits in the tail area not to puncture, and to carry out the puncturing completely outside this area.

Möglichkeiten ergeben.For this second option, simulations were created that were used to search for rate adjustment patterns by optimizing the target function. Since the search for suitable rate adjustment patterns would be too complex, taking into account all possibilities, the search was limited to selected areas taking into account the constraints shown above. If 6 bits were cut from 48 bits, there would already be

Opportunities.

Have proven to be particularly suitable the following puncturing patterns obtained by the above search are highlighted. For better readability there are positions where a bit is shortened marked with 0, positions at which no bit is shortened with 1.

Rate adjustment pattern A

Rate adjustment pattern B

In both patterns it is clearly too see that no cuts (puncturing) were made in the end area become.

Among other system requirements or channel properties, puncturing affects the tail area or less dots only in the beginning area of the tail area strongly on the detection probability.

For the search for such rate adjustment patterns will then, if necessary modified the constraints or the selected areas extended. For example the computer-aided Search for the case of the HS-SCCH also on the first 28 bits, that is to say partially also in an area in which the tail bits already have an influence, be extended to find a good puncturing pattern there.

Other uses

Sharing rate adjustment patterns was especially for the HS-SCCH explains however, it is not limited to this. Also with other control channels uses a masking of the user data, whereby the invention in different configurations can be used. Further applications result in principle for all channels, in which different data streams for transmission linked together and a rate adjustment is required.

Finally, it should be mentioned with reference to the drawings that the term "pattern" is also used for rate adjustment patterns; under, Physical Channel Mapping ^'and the figure is understood in the physical data channel. XOR is used as a shorthand for an exclusive OR combination.

Abbreviations

HSDPA High Speed Downlink Packet Access
HS-DSCH High Speed Downlink Shared Channel (data)
HS-SCCH High Speed Shared Control Channel (control information, signaling)
UE User Equipment (name for a UMTS mobile station)
UE ID identification number of the mobile station

swell

[1] R1-02-0605, "Coding and Rate Matching for HS-SCCH", TSG RAN WG1 Meeting # 25, Paris, April 9-12, 2002.

The cited document is a document by 3GPP (Third Generation Gartnership Project), address: ETSI, Mobile Competence Center, 650, route des Lucioles, 06921 Sophia-Antipolis Cedex and is here in the format used by this organization cited.

Claims (12)

Method for rate adaptation to a specified data rate,  - in which the data, whose data rate is adjusted, from at least two coded streams be put together, and  - where the rate adjustment the data rates of the at least two data streams to the specified data rate A rate adjustment pattern is used via which the scheme for repeating or puncturing individual data sequences from the data streams is determined and which for the at least two data streams is equal to. The method of claim 1, wherein the data by linking the at least two data streams be formed, and the rate adjustment. before or after linking the streams he follows. The method of claim 2, wherein the link is a bitwise link is. Method according to one of the preceding claims, which the coding of at least one data stream by convolutional coding he follows. Method according to one of the preceding claims, which the specified data rate by the data rate one of at least a first transmitting / receiving unit and a second transmitting / receiving unit physical channel in a communication system will, and - at which the at least two data streams on the one hand from data user data (LD) and on the other hand identification data (ID) to identify the second communication device become,  - at which separate the user data (LD) and the identification data (ID) are coded from each other,  - and the coding (C LD, C-ID) takes place in such a way that for user data LD and identification data ID gives the same bit rate after the coding process and  - the rate adjustment to the for the bit rate set using the for user data (LD) and identification data (ID) of the same rate adjustment pattern he follows. Method according to one of the preceding claims, which the coding process a bit sequence of bits 1 to n in one fixed time window, which sets the rate and the rate adjustment is made by a rate adjustment pattern by which individual bits from this bit sequence are punctured. Method according to one of the preceding claims, which the physical channel is the high speed shared Control Channel (HS-SCCH). Method according to one of the preceding claims, which the identification data is the identification number a transmitting / receiving unit. Method according to Claims 7 and 8, in which the rate adjustment is carried out using a rate adjustment pattern, by virtue of the bits at the positions in the bit sequence consisting of n = 48 bits 1 . 2 . 4 . 8th . 42 . 45 . 47 . 48 be punctured. A method according to claims 7 and 8, wherein in the bit sequence consisting of n = 48 bits, the bits at the positions 1 . 7 . 13 . 19 . 25 . 31 . 37 . 43 be punctured. The method of claim 10, wherein the position of the to be punctured Bits is shifted by an integer k, where 0 <k <= 5 applies. Method according to claim 4 or 7 and 8, in which the user data (LD) a defined bit sequence is added before coding, the coding for User data (LD) is made and a link before or after the rate adjustment with the coded identification data (ID), the Rate adjustment is done using a rate adjustment pattern, by which only or preferably bits are punctured that do not Carry information about bits in these specified bit sequences.