Method and device for transmitting data according to a hybrid ARQ method

The present invention relates to a method and an appropriately designed device for transmitting data according to a hybrid ARQ method in a Communication system, particularly a mobile radio system.

Especially in connection with mobile radio systems is often the use of so-called package access method or proposed packet-oriented data connection, since the emerging types of messages often a very high have burst factor, so that only short periods of activity exist, which are interrupted by long periods of rest. Packet-oriented data connections can in this case the Efficiency in comparison with other A data transmission method in which a continuous is data stream available, greatly increase, since in Data transmission method with a continuous A data stream once assigned resource, such. As a Carrier frequency or a time slot during the entire Communication relationship remains allocated, ie a resource also remains available when currently no rest data transfers so that this resource for other net participants is not available. this leads to to a non-optimal use of the scarce Frequency spectrum for mobile radio systems.

Future mobile radio systems, such as in accordance with the UMTS mobile radio standard ( "Universal Mobile Telecommunications System "), are a number of different services offer, which in addition to pure voice transmission winning multimedia applications are becoming increasingly important will. The associated services with diversity different transmission rates requires a very flexible access protocol on the air interface future mobile radio systems. packet-oriented Data transmission methods have adapted here very proved.

In connection with the UMTS mobile communication systems has been in packet-oriented data connection a so-called ARQ process ( "Automatic Repeat Request") proposed. there are transmitted from a transmitter to a receiver Data packets on the receiver side after their decoding checked for their quality. If a received Data packet in error, the receiver requests a re Transmission of this data packet from the transmitter at, ie a retransmission data packet from the transmitter to the sent receiver, which with the previously transmitted incorrectly received data packets identical or partially is identical (depending on whether the retransmission data packet less or the same number of data as the original Data packet contains is, from a full or a partial repetition spoken). The rules for the UMTS mobile standard proposed ARQ process is both the transmission of data as well as of so-called Header information provided in a data packet, wherein the Header information includes information regarding error checking, such as CRC bits ( "Cyclic Redundancy Check") have, and can also be encoded for error correction (So-called. FEC, Forward Error Correction).

According the current proposals of the UMTS specification the introduction of a so-called hybrid ARQ method, provided, which as "incremental redundancy" -ARQ process referred to as. The main difference to the previously conventional ARQ method described is that in the Receiver coding using multiple Data packets with the same information source, but different channel coding is performed. ie are more data packets with the same information origin decoded and evaluated until an originally transmitted decoded data packet in the receiver as error-free is valid. in the Contrary to the ARQ method described above are in the hybrid ARQ method, the repetition of data packets (which are also referred to as a "Retransmission") typically not identical to the data packet originally transmitted.

In Fig. 3, the signal processing which according to the discussed the current state of UMTS standardization, Hybrid ARQ method shown.

As shown in Fig. 3, is the generation of the Transmission signal in the processing of the actual Data and the processing of the header information subdivided. be on the header page of a Function block 3 produced a header information supplied to functional block 12, which ensures that all the headers of all data packets, the same in the Radio packet to be sent to a single header are combined (so-called. "Header Concatenation"). On Functional block 13 adds the resulting Header Information CRC bits for error detection added. Next, a function block of a 14 And channel coding of a function block 15, a Rate matching of the resulting bitstream supplied. An interleaver 16 causes the symbols supplied to it, arranged or bits in a certain way and in time are spread. The output from the interleaver 16 Data blocks are of a function block 17 the individual Transmission or radio frame allocated (so-called. "Radio Frame Segmentation ").

On the data side is also a functional block 4 for Adding CRC bits is provided. A functional block 5 used for splitting of a channel coder 6 supplied Data such that on of the channel encoder 6 is always a carried out a certain number of bits limited coding can be.

Through the processing performed by the channel encoder 6 Channel coding is the actually data to be sent redundant information added. This has the consequence that several consecutively transmitted data packets with the same bits have information origin. In the hybrid ARQ method, (According to the so-called type II and III), in a faulty reception or a faulty decoding a data packet by the receiver is not the same Data packet again from the transmitter to the receiver sent, but the transmitter transmits a data packet, which at least partially with the same bits Information origin as contained in the originally transmitted comprises data packet bits contained. The recipient can through joint evaluation of all data packets which bits with have the same information origin, originally transmitted information with better quality regain.

To carry out the above-described hybrid-ARQ process it is required that in the presence of corresponding request of the recipient of the same Information originating the data transmission signals "Incremental redundancy", which was originally in the transmitted data packet and the corresponding Repeat data packets received, are generated (So-called "Redundancy Selection"). For this purpose, according to the channel encoder 6, a corresponding function block 7 provided, which as of the functional block 3 Supervisory Body is controlled and after the channel coding a corresponding Bitselektion performs. In this way are from the function block 7, depending on the Triggering by the functional block 3 which in the first packet and in repeating data packets to be transmitted bits selected.

The output from the function block 7 data is a Function block 8 is supplied which by hiding or Omission of individual bits (known. Puncturing) or Repeat individual bits (known. repetition), the bit rate of the data stream adjusts. From a subsequent functional block 9 can the data stream called DTX bits ( "Discontinuous Transmission ") are added. Furthermore, also on the data page function blocks 10 and 11 are provided, which same functions as those in the header page provided Function blocks 16 and 17 perceive.

will conclude on the data and header page output bits of a function block 18 to the respective existing physical transmission or transmission channel ready or multiplexed (so-called. "multiplexing").

For a powerful possible hybrid or "Incremental Redundancy "-ARQ process is the FEC coding of the different data repetition packets as possible so to Select that these data packets typically low have identity or correspondence with one another. This is in particular in UMTS, due to the high flexibility of the performed channel coding and data adjusting for the individual transmission channels problematic, particularly since the channel coding not only in terms of their Performance can be optimized. It will play Other factors, such as the memory requirement and the complexity of the algorithms performed, a essential role, and this in particular the on side Mobile station algorithms executed relates.

Generally, with the reference to FIG. 3 described hybrid ARQ method the problem, an originally transmitted Data packet and optionally one or more of the following Sent repeat data packets to achieve a possible high quality encode as cheaply as possible.

The present invention is therefore based on the object, a method and a correspondingly designed Device for data transmission according to a hybrid ARQ method, propose, on which the principle of a hybrid ARQ method with increased flexibility and better utilization the possible coding gain without significant increase the complexity and the memory requirements are realized can.

This object is inventively achieved by a method with the features of claim 1 and an apparatus having the Features of claim 23 is released. The sub-claims each define preferred and advantageous Embodiments of the present invention.

The basic idea of ​​the present invention is based on the function blocks shown in FIG. 3, 7 and 8 for Redundancy selection ( "Redundancy Selection") or rate matching summarize ( "rate matching"), so that a can be carried out more efficient coding. Here are the Functional blocks 7 and 8, that shown in Fig. 3 Hybrid ARQ structure in particular replaced by a structure which a Bitseparation to generate multiple (different coded) parallel bit streams with subsequent Bitkollektion performs. The different bit streams be an independent rate adaptation subjected. In this manner, in coding a achieved greater flexibility. Pro to be transmitted data packet or repeat data packet, the different parallel bit streams preferably proportionately together be combined. This is particularly Bitrepetierung advantageously used.

The advantage of the inventively proposed method or of the corresponding device is a higher Flexibility and better utilization of the possible Coding gain, while in addition a less repetition based rate matching without any appreciable increase in the And complexity of the (in particular for carrying out the Interleaving needed) memory requirements can be achieved.

In the dependent claims are preferred embodiments the present invention describes the particular the manner carried out according to the invention Bitseparation or Bitkollektion and the choice of Rate matching for each different bit streams, resulting from the Bitseparation concern.

The present invention will in more detail below with With reference to the accompanying drawings using preferred Embodiments of a packet-oriented data transfer explained in a mobile radio system in which the present Invention is of course not limited to cellular systems is limited, but generally in any kind of can be used in communication systems in which a Hybrid ARQ method is provided for data transmission.<sl><li>Fig. 1 shows a diagram to illustrate the Signal processing in accordance with a particular packet-oriented Hybrid ARQ process of the present invention,</li><li>Fig. 2 shows a diagram to illustrate the Communication in a mobile radio system, and</li><li>Fig. 3 shows a diagram to illustrate the Signal processing according to a conventional packet-oriented hybrid ARQ method.</li></sl>

As has already been explained above, will now be assumed that with the aid of the present invention a packet-oriented data transmission in a Mobile radio system, as for example schematically in FIG. 2 is shown to be realized. Here, in Fig. 2 for example, the communication between a base station 1 and a mobile station 2 of a mobile radio system, For example, a UMTS mobile radio system shown. The Transmitting information from the base station 1 to the Mobile station 2 via the so-called "downlink" channel DL, during the transfer of the information from the Mobile station 2 to the base station 1 via the so-called "Uplink" channel UL done. The present invention is by way of example below with reference to a packet-oriented Data transmission from the base station 1 to the mobile station 2, ie on the basis of a packet-oriented data transfer the "downlink" channel, explained, and the present Invention, however, in analogy to a data transmission via the "Uplink" channel is applicable. Further, the present invention analogous below to FIG. 3 on the basis of to be carried out in the respective stations Signal processing measures discussed, but to Note that in each receiver for evaluation In this way, the transmitter side processed data a corresponding signal processing in the reverse order is required, so that by the present invention not only the transmitter side, but also the receiver side is concerned.

In Fig. 1, the signal processing of the data in packets is to transmitted data and header information for a inventive hybrid ARQ method shown. The present invention relates to substantially the Processing of the data part, so that in Fig. 1 Function blocks shown 12-17 which headers part the concern, the functional blocks shown in Figure 3 12th - 17 correspond. Likewise match those shown in Fig. 1 Function Blocks: 3 - 6 and 9-11 and the corresponding 18 in Fig. 3 functional blocks shown, so that regarding the role and function of these function blocks to the above explanations relating to FIG. 3 can be referenced.

As is apparent from Fig.1 that in Fig were. 3 Function blocks 7 and 8 represented by a new Function section 19 are replaced. This function section 19 includes a function block 20, which, depending on a drive by the function block 3 of the upstream channel encoder 6 output coded bits dividing at least two parallel bit streams which separately, ie independently, a Rate matching undergo. In FIG. 1 in this respect three bit streams shown, wherein for each Bitstream a functional block 21 - 23 for carrying out a Rate matching, ie for puncturing or repetition individual bits, is provided. arise in this way several differently coded parallel bit streams are fed to a further function block 24th This Another function block 24 has the task of the individual bits of the parallel bit streams in the same order, which of the functional block 20 for the Bitseparation, ie for the Allocation to the parallel bit streams used has been picking up. In this way, ensured that total the order after the rate matching leftover bits not changed.

If per data packet exclusively one of several parallel Bitstreams is selected, the signal processing is in accordance with FIG. 1 in the signal processing shown in FIG. 3 can be transferred. It However, it is apparent that with the aid of in FIG. 1 Signal processing shown increased flexibility can be obtained in coding. Specifically, per data packet the different parallel bitstreams are proportionately combined, this being particularly is advantageously in Bitrepetierung. So can For example, instead of applying a pure Repetition coding in a single bit stream, as in the repetition coding shown in Fig. 3 the Case would be, in the signal processing shown in Fig. 1 of A bitstream unchanged, ie without performing Rate matching, are transmitted, wherein at the same time in FIG. 1 bitstream B shown with a corresponding rate matching for Filling the remaining transmission signal used can. In particular, the division of the bits of the channel encoded bit stream to the individual bit streams AC are selected such that for a data or Repeat data packet number. N only bits of the bit streams 1 to N be used. This is according to the state shown in Fig. 3 art not possible and only by the inventively proposed principle, as exemplified is shown in Fig. 1, realized. These Variant has the advantage that the receiver for Receiving the retransmission data packet number. N only memory N bit blocks must be reserved, as is known a priori, that the receiving data only from these N bit blocks originate. More generally, can also be designed a scheme in the number of repetition for the data packets 1 to N Bit blocks used monotonous or even strictly with N increases.

Below, preferred embodiments of the 20 and 24, carried out by the function blocks Bitseparation or Bitkollektion and for the Functional blocks 21 - 23 performed rate adaptation are explained.

Regarding the choice of the parallel rate matching pattern, which, as well as by the function blocks 21 and 22 optionally 23 can be realized, can be provided, these to choose such that the total of the Functional section 19 to perform a task which equivalent to that shown by in Fig. 3 Function blocks 7 and 8 in accordance with the duties performed current state of the specification.

Likewise, the data packets may consist in repetition with data more than two parallel bitstreams A - C is filled in such a way be that the bits of a bit stream or branch to 100%, ie unchanged, transmitted, while the bits of other bit streams or branches fill the remaining data. According to a further embodiment, the Rate matching pattern be selected such that the Data packets for repetition to with data from just two parallel bitstreams are filled, wherein the one Bitstream to 100%, ie unchanged transmitted while the other bit stream, the remaining data fills.

The operation of the function blocks 20 and 24, in such a way be selected such that a data packet to be transmitted original always Data of the bitstream A or - if the data of the bitstream A already 100% are transmitted - data of the bitstreams A and B contains. For the first repetition packet then preferably data of the bitstream B or - if the data of the Bitstream B are transferred already to 100% - Dates Bitstream B and A used. For the second Repeat data packet, it is particularly advantageous data the bit stream C or - if the data of the bit stream C already 100% are transferred - the data bit streams and C B to use.

Generally, it is the goal, by combinations of the memory most efficient use in the mobile station 2 and thus Data in the data packets with respect to their origin possible not to apply excessive scatter. In addition to a highest possible profit be exploited in coding can.

Below is an optimal choice regarding the Storage requirements of the mobile station 2 illustrates, the hereinafter described embodiment a compromise between the memory and the expected represents performance. According to this be embodiment to repeat or to repeating bits only of such branches or bitstreams selected whose data according also according to the prior art are already transmitted Fig. 3, whereby an increased Memory requirements, especially in the receiver is avoided. The original data packet contains, according to this Embodiment only data of the bit stream A. first repeat data packet contains data of the bitstream B or - if the data of the bitstream B already 100% transmitted - data of the bitstreams B and A. In that regard, is true, this embodiment with the previously described Embodiment match. In contrast to the previously however described embodiment includes the second Repeat data packet data of the bit stream C or - if the data of the bit stream C are already transferred to 100% - Data of the bitstream C as well as of the bit stream B and / or the Bitstream A.

Generally, it is favorable if after exactly one requested Repeat about the same number of bits of the bit streams A and B be transmitted. After exactly two requested Repetitions should be approximately the same number of bits of Bitstreams A, B and C are transmitted.

Of course, all be within the present patent application described Embodiments generally applicable to more than two Apply repetitions.

According to a further variant of the present invention may after coding by the channel encoder 6 of those Branches or bitstreams AC, which is not primarily for the transmission pending, much of the data are punctured, as by the subsequent rate matching anyway from these Bitstreams, only a small proportion (typically z. B. 10%) the selected bits to be transmitted. It is therefore harmless if immediately 90% of the bits of these branches or Bitstreams will be deleted. This measure at the intermediary function blocks corresponding to less Storage space, so that this variant primarily on a further reduction in the memory requirement aims.

For the latter variant is the following Variant equivalent described. Instead of choosing a specific bit stream (eg the bitstream B) with subsequent puncturing to 90% can also take this be introduced bitstream two bitstreams (eg bitstream B ' and bitstream B "), wherein said one bit stream (B ') 10% of the bits contains the original bit stream (B).

LIST OF REFERENCE NUMBERS

<dl tsize="11" compact="compact"><dt>1</dt><dd>base station</dd><dt>2</dt><dd>mobile station</dd><dt>3</dt><dd>Function block for HARQ header generation and redundancy control</dd><dt>4.13</dt><dd>Function block for adding CRC bits</dd><dt>5</dt><dd>Function block to the code block segmentation</dd><dt>6.14</dt><dd>Function block for channel coding</dd><dt>7</dt><dd>Function block for redundancy selection</dd><dt>8,15, 21-23</dt><dd>Function block for rate matching</dd><dt>9</dt><dd>Function block for adding DTX bits</dd><dt>10.16</dt><dd>Function block for interleaving</dd><dt>11.17</dt><dd>Function block for transmit frame segmentation</dd><dt>18</dt><dd>Function block for multiplexing on a broadcast channel</dd><dt>19</dt><dd>Functional section for redundancy selection and rate matching</dd><dt>20</dt><dd>Function block for Bitseparation</dd><dt>24</dt><dd>Function block for Bitkollektion</dd><dt>25</dt><dd>AC bitstream</dd><dt>26</dt><dd>DL "downlink" channel</dd><dt>UL "</dt><dd>Uplink "channel</dd></dl>