EP1992093A1

EP1992093A1 - Interleaver and deinterleaver for mimo multiple antenna systems

Info

Publication number: EP1992093A1
Application number: EP06793837A
Authority: EP
Inventors: Wojciech Kuropatwinski
Original assignee: Nokia Siemens Networks GmbH and Co KG
Current assignee: Nokia Solutions and Networks GmbH and Co KG
Priority date: 2005-11-10
Filing date: 2006-09-26
Publication date: 2008-11-19
Also published as: WO2007054400A1; DE102005053714B4; DE102005053714A1

Abstract

Disclosed is an interleaver (IL) for a MIMO multiple antenna system (AZ2), which is connected upstream from several transmit antenna branches (TX1 with TX4) and interleaves adjacent bits of a whole data flow (DSI) that is to be transmitted. Said interleaver (IL) additionally separates adjacent bits in the whole data flow (DSI) that is to be transmitted into different partial data flows (DA1 with DA4) in different transmit antenna branches with the aid of interleaving means.

Description

Interleaver and deinterleaver for MIMO multiple antenna systems

The invention relates to an interleaver for a MIMO multiple transmit / receive antenna system comprising a plurality of

Transmit antenna branches is upstream and the adjacent bits of a total data stream to be transmitted temporally scrambled.

The function and function of an "interleaver", ie scrambler, is to regroup adjacent bits in a data stream such that they have the greatest possible time interval from one another .These time-spread or scrambled bits in the data stream to be sent are, as they are transmitted over a transmission medium This means that the bit data stream detected by a receiver after a deinterleaving corresponding to "transmit-side interleaving" (ie, after a cancellation of the transmitter-side scrambling) is less of a block error is charged.

In many publications, such as e.g. [1] Farrokhi F.R., Foschini G.J., Lozano A., and Valenzuela

R.A., "Link-optimal space-time processing with multiple transmit and receive antennas," IEEE Comm. Lett., Vol.5, pp.

85-87, March 2001,

[2] Foschini G.J., Gans M.J., "On limits of wireless communication in a fading environment when using multiple antennas," Wireless Pers. Communications, pp. 311-335, 1998, [3] Foschini G.J., Golden G.D., Valenzuela R.A., Wolniansky

PW, "Simplified Processing for Wireless Communication at High Spectral Efficiency," IEEE J. Selected Areas Comm., Vol. 17, pp. 1841-1852, 1999 [4] Lozano A., Farrokhi FR, Valenzuela RA, "Lifting the limits on high-speed wireless data access using antenna arrays," IEEE Comm. Mag., Pp. 156-162, Sept.2001, and [5] Marzetta TL, "Blast training: Estimating the channel characteristics for space-time wireless," Proc. 37 ^th Annual Allerton Conf. on Comm., Control, and Computing, Monticello, IL, USA, Sept. 1999, several methods of "Multiple-Input Multiple-Output" (= MIMO) processing have been used that use multiple antenna elements on both the transmitter and receiver sides. Algorithms proposed there attempt to set the theoretical limit of the normalized MIMO channel capacity (in bps / HZ), which, depending on the number of transmit and receive antennas, far exceeds the normalized SISO (ie "single input single output", ie only one transmit antenna) Sender device and only a single receiving antenna is available at the receiving device) - channel capacity can be reached. The Bell Laboratories Layered Space-Time (BLAST) architecture seeks to realize a significant portion of this capacity, and the first proposal for this architecture is known as Diagonal Blast (D-Blast), a simplified processing that is already in real-time Demonstrator is the "Vertical Blast (V-Blast)" proposal. In this case, no channel information is available at the transmitter. An incoming data stream is distributed on transmit antennas and consequently statistically independent data streams of equal average power P _τ / _Mτ (P _τ = total transmit power, M _τ = number of transmit antennas) are transmitted over the different transmit antennas.

The V-Blast does not require coding. However, different methods of classical channel coding (eg, block and / or convolutional coding, Trellis Coded Modulation, etc.) are used to reduce the bit error rate (BER), that is, the bit error rate of the transmission. In the following, for example, the "Forward Error Correction", that is, forward error correction, is turned off for the use of channel coding in a so-called V-Blast system:

1.) On the one hand, it is possible to separate the independent data streams of the individual transmit antennas separately, i. selectively channel coding. After this encoding, the data is interleaved. This is illustrated schematically in FIG. 1. There, a data stream DS is generated with the aid of a generator unit GE in a multiple transmitter branch AZO. This data stream DS contains a multiplicity of bits. It is referred to in the jargon as "DX Data." With the aid of a subsequent demultiplexer DM, the total bit data stream DS before transferring its bits over the same available frequency channel to multiple data streams DSl with DS4 in different, ie in this embodiment four different transmitters The goal here is to send these multiple, here four partial data streams DS1 with DS4 simultaneously, ie simultaneously with the same available frequency channel via the transmission antennas TAI with TA4 of the transmission branches TZ1 with TZ4 Transmission antenna branch TZl with TZ4, the respective partial data flow DSl DS4 with a channel coding using a channel encoder CCl with CC4, in particular a forward error correction encoder subjected, so that channel-coded partial data streams DSU with DSI4 at the output of the respective channel coder CCl with CC4 are output This channel coded partial data DSU's with DSI4 will each be specific, i. for each antenna branch with the aid of a specific interleaver ILl with IL4 temporally interleaved, i. their bits are scrambled in time such that originally temporally adjacent bits have a possible large time interval from one another. These "interleaved" data streams in the individual transmitting antenna branches TZ1 to TZ4 are denoted DSU * by DSI4 * in FIG.

Partial data streams DSU * with DSI4 * processed separately in a downstream MIMO processing unit MP. In particular, they will Transmit antenna branch-specifically modulated, adjusted in terms of their performance, predistortion, etc., and finally radiated via the transmitting antenna TAI with TA4 at the end of their respective, specific transmission antenna branch TZl with TZ4. Of course, the MIMO processing unit MP also carries other usual

Processing steps for the respective bit stream of the respective specific transmitter antenna branch. The MIMO multicast antenna system thus formed is designated AZO in FIG. It may in particular be part of a mobile radio communication device, preferably a mobile radio device. Similarly, it may include a corresponding MIMO multiple receive antenna system performing an inverse operation to the transmit side.

An advantage of this MIMO multiple antenna system of Figure 1, each with its own interleaver per transmitter antenna branch is in particular that at a sufficiently large signal-to-noise ratio, the individual independent

Data streams can be detected with greater certainty. This is mainly useful in the so-called "linear nulling" and "symbol cancellation" method (analogous to "successive interference cancellation in muliuser detection" method), however, this is done with a larger

Computing costs paid because it is necessary to implement for each independent data stream separate codecs (coder and decoder) at the transmitter and receiver side. This is a disadvantage because even without the replacement of the classical channel coding, a very high computational effort for the detection of multiple data streams has to be overcome.

2.) On the other hand, according to a second concept, the bit total data stream to be transmitted can be coded and interleaved before being divided into a plurality of partial data streams in different transmission antenna branches. This case is schematically illustrated by means of the transmitting multiple antenna branch AZ1 of FIG. With the help of the generator unit GE, the total bit data stream DS is generated. It is denoted by "TX data (bits)." This bit total data stream DS is channel coded with the aid of a subsequent channel coder CC. In particular, in the exemplary embodiment of FIG. 2, it is subjected to forward error correction, ie a "Forward Error Correction" FEC At the output of the channel coder CC, a channel-coded bit total data stream DSI is available. This is fed to a single downstream interleaver IL, which performs a temporal scrambling of the individual bits of this channel-coded bit total data stream DSI. The bit total data stream IDSI output at the output of the interleaver IL is then fed to a downstream MIMO processing unit MPR. Only this process the bits of the interleaved total data stream such that the bits of the interleaved total data stream IDSI are divided into several, here four different transmission antenna branches TXl with TX4 and are emitted via their transmission antennas TAI with TA4. Of course, the MIMO processing unit MPR performs more common

Processing operations such as modulation, power adjustment, predistortion, etc. for the respective partial data stream specifically in the respective transmitting antenna branch TXl with TX4. In the case of the MIMO multicast antenna system AZ1 of FIG. 2, it is sufficient to implement only a single codec. As a result, the computational outlay is reduced in comparison with the multiple transmission antenna system AZO of FIG. This is advantageous in real transmission systems in which their arithmetic unit such as a digital signal processor has a large number of tasks to process and the computing resources are running out.

It is an object of the present invention to provide a way to make a bitstream data stream of a MIMO multicast antenna system more robust to block errors that may occur in transmission over a common frequency channel. In appropriate Way is a receive-side MIMO

Multi-receive antenna system that allows further reduction of block errors in the recovered total bitstream.

This object is achieved on the transmission side by means of an interleaver for a MIMO multiple transmission antenna system which precedes a plurality of transmission antenna branches and temporally scrambles adjacent bits of a total data stream to be transmitted, characterized in that scrambling means are provided such that adjacent bits in the total data stream to be transmitted in addition to the temporal scrambling on different partial data streams in different transmission antenna branches are divisible.

On the reception side, this object is achieved by the following deinterleaver according to the invention:

Deinterleaver for a MIMO receive antenna system downstream of a plurality of parallel receive antenna branches, and deinterleaving the bits of the partial data streams of the different receive antenna branches into a total data stream, characterized in that deinterleaver means are provided such that in addition to canceling the temporal scrambling the Incrementing the scrambling of the bits in the received data streams with respect to the various receive antenna branches is feasible for bits of the incoming sub-data streams.

Because the interleaver according to the invention performs a scrambled division of the bits onto different antenna branches in addition to the temporal scrambling of adjacent bits in the bit total data stream to be transmitted, the occurrence of block errors in the transmission is further reduced. For example, becomes a transmission antenna of the plurality of transmission antennas a MIMO multicast system of a

Radio communication device shadowed by the hand of a user, so is achieved by the random division of the bits of the total data using the interleaver according to the invention in addition to the time spreading of the bits passing through him, that the bits statistically distributed to all transmission antenna branches and thus to those with better Transmission conditions are divided. This can be improved block errors in the transmission of the bits to be transmitted

Reduce overall data stream. In other words, with the aid of the interleaver according to the invention, which now performs an interleaving of the bits of the overall data stream in two respects, it is possible to convert burst errors into single errors. However, individual errors can be corrected better than block errors on the receiver side with the help of a corresponding deinterleaver and subsequent error correction.

The invention further relates to a mobile radio communication device which has at least one interleaver according to the invention in its MIMO

Multicast antenna system and / or at least one deinterleaver according to the invention in its MIMO

Multiple receiving antenna system.

Other developments of the invention are in the

Subclaims reproduced.

The invention and its developments are explained in more detail with reference to drawings.

Show it:

FIGS. 1, 2 in schematic representation two previous MIMO

Multicast antenna branches, FIG. 3 is a schematic representation of a MIMO multicast antenna branch having an interleaver according to the invention in the common transmission antenna branch, before splitting into a plurality of transmission antenna branches, FIG.

FIG. 4 is a schematic representation of an example of the operation of the interleaver according to the invention of FIG. 3;

Figure 5 is a schematic representation of a MIMO Mehrfachempfangsantennenzweig comprising a deinterleaver according to the invention, and

Figure 6 schematically

Radio communication device with a MIMO multicast antenna system and / or MIMO multigate antenna system according to FIGS. 3 and 5.

Elements with the same function and mode of operation are each provided with the same reference numerals in FIGS.

FIG. 3 shows a schematic representation of an exemplary embodiment of a MIMO multicast antenna branch AZ2, which has an interleaver IL according to the invention

Functional principle. From the generator unit GE, the total bit data stream DS is generated. This is channel-coded with the aid of a downstream channel coder CC, in particular a forward error coder FEC. The channel-coded bit total data stream is designated DSI in FIG. It is fed to the downstream interleaver IL. With the aid of this interleaver IL, the bits of the channel-coded total data stream DSI become temporal scrambled. This temporal scrambling is carried out in such a way that adjacent bits in the channel-coded total data stream DSI are rearranged such that they have the greatest possible time interval from one another. This temporal spreading of the bits in the channel-coded overall data stream provides a first remedy by which the risk of block errors in the transmission of these time-scrambled bits can be reduced. On the other hand, the scrambling means of the interleaver IL are designed in such a way that adjacent bits in the overall data stream to be transmitted are, in addition to their temporal scrambling, split over different antenna branches, ie scrambled with respect to the provided antenna branches. In the exemplary embodiment of FIG. 3, the interleaver IL additionally scrambles the time-scrambled bits of the overall data stream to the four transmission antenna branches TX1 to TX4, ie it performs additional spatial scrambling (diversity). In this way, the total data stream DSI is divided into four partial data streams DA1 with DA4 in the four different antenna branches TX1 to TX4. Each sub-data stream DAl with DA4 receives both temporally and antenna-scrambled bits. Subsequently, the partial data streams DA1 with DA4 are modulated using a downstream MIMO processing unit MPR antenna branch-specific modulation methods, power adaptations,

Vorfilterungen, etc., and finally separately from each other via the transmission antennas TAI with TA4 their different transmission antenna branches TXl emitted with TX4.

FIG. 4 illustrates the operation of the interleaver IL for the four different transmission antenna branches TX1 and TX4 of FIG. 3 on the basis of an exemplary total bit data stream DSI which is divided into the four partial data streams DA1 and DA4. The Arabic numerals denote the indices of the bits in the total data stream DSI that arrive at the interleaver IL. The superscript Roman numerals in the Arabic numerals each symbolize a burst number to which the respective bit is assigned. The original bit Total data stream DSI contains namely the bits of several signal bursts. Here in the embodiment of Figure 4 are, for example, four bursts, which are marked by the Roman numerals I-IV. Consider, for example, the first data stream DAl at the output of the

Interleavers IL, it can be seen that bits from the same burst are separated in time by bits from other bursts. For example, the bit with the indexing I ^{1 of} the first burst I is temporally separated from the bit 305 of the first burst I by bits with the indices 2053 ¹¹ , 4105 ¹¹¹ , 6157 ^IV belonging to the burgs II, III, IV. This is caused by the temporal scrambling in the interleaver IL. In addition to the temporal scrambling of the bits in the incoming total data stream DSI, however, originally adjacent bits, such as in the same broadcast burst, are now split among the different data streams DA1 to DA4 of the different antenna branches TX1 to TX4. By way of example, the first bit with the index or the number 1 in the first burst I is contained in the first partial data stream DA1, while its originally adjacent bit with the number 2 of the same send burst I is transmitted offset in time by 6 bits in the fourth partial data stream DA4. Thus, the interleaver IL performs both a temporal scrambling and at the same time a spatial scrambling of originally adjacent bits of the total data stream to be processed. This temporal and spatial scrambling principle of the interleaver IL of the embodiment of FIGS. 3, 4 can be generalized to a bit overall data stream with N bits. In the following, a generalized, formal description of an inventive interleaver is shown by way of example for a MIMO system without channel information at the transmitter:

The input of the interleaver is a bitstream of length N. On the input side, the input bits are first assigned the indices from 1 to N. Due to the interleaving

Process, the interleaver indices I for the n-th antenna are advantageously calculated as follows: l (n, m + (k - l) • NoBu) = Stdx) + (n - 1) - fiχ [i- ϊ-] • NoA + BL + l \ + s - NoA ■ (m - l), mod N,

^ yNoAJ where n = \ ... NoAn, m = \ ... NoBu, k = l ... StValLen,

_ (IntLenPaA _{ΛT n} . _{Τ τ n} NoBpA _Λτ N s = fix. NoBu + 1, IntLenPar = -, NoBpA =

Noss «J NoBu NoA

Stlndx = StVaI (I + {q - 1) - StShift, mod StValLen), q = l ... StValLen, StVaI = 1, 1 + NoBu ^■ NoA, 1 + 2 • NoBu ^■ NoA, 1 + 3 • NoBu ^■ NoA, ... <N,

where n denotes the n-th transmission antenna branch,

NoA is the number of transmit antennas, m is the index of a respective transmit burst to be interleaved,

NoBu the number of bursts whose bits are grouped as a block within the total data stream,

BL is the length of the respective burst, k denotes the respective length of the vector Stlndx, fix is an integer rounding operation,

StValLen is a parameter for the length of the vector StVaI, and

StShift is an integer index increment parameter that is conveniently chosen to be as close to G as possible and to have the largest common divisor of the parameters StShift and StValLen equal to one.

FIG. 5 shows a schematic representation of a MIMO multiple receive antenna branch RZ1 with a deinterleaver DIL for reversing the transmit-side bit interleaving of FIG. 3 in a receiver. The MIMO multi-receive antenna branch RZl has a plurality of receive antenna branches RX1 with RX4. Via the receiving antennas RA1 and RA4, four separate partial data streams DA1 * with DA4 * are obtained with the aid of a MIMO reception processing unit MPR *. This MIMO receive processing unit MPR * performs a selective Demodulation, equalization, power amplification, etc. as well as other common processing procedures for the received data signals. The obtained bit data streams DAl * with DA4 * are selectively fed to the deinterleaver DIL, there deinterleaved in an inverse operation in terms of time and space, and from this the total bit data stream DSI * is obtained. The deinterleaver DIL thus reverses the temporal scrambling of the bits in the individual partial data streams DA1 * with DA4 * and their scrambling on the various receiving antenna branches RX1 with RX4. The bit total data stream DSI * thus recovered is finally DC channel decoded with the aid of a subsequent decoder. The decoded bit total data stream is designated DS * in FIG. This is finally fed to a receiver and processing unit RE.

Finally, FIG. 6 shows a mobile radiocommunication device MP, in particular a mobile radiotelephone, which has both the MIMO multicast antenna branch AZ2 of FIG. 3 and the MIMO multiple reception penten branch RZ1 of FIG.

Of course, it is also possible to provide the multicast antenna branch AZ1 alone or the MIMO receive antenna branch RZl alone in the radio communication device MP.

In addition, it may be appropriate to use a MIMO

Multi-transmission antenna branch containing an interleaver according to the invention to implement in other communication devices. The same applies to the corresponding MIMO receiving antenna branch.

In summary, the following results:

The interleavers so far described in numerous publications attempt to maximize the index spacing of the bits after the interleaver. In a V-Blast system, however, not only the largest possible time interval between the bit indices after the interleaver is important, but also the property that the bits that occur before the interleaver are not sent from the same antenna.

The interleaver according to the invention now provides that the overall data stream is interleaved in such a way that adjacent bits are scrambled in time as well as additionally reliably distributed to different antennas and thus less block errors can occur. In the case of an interleaver formed in this way, a second scrambling is thus taken into account in addition to the first temporal scrambling, namely the scrambling on the various transmission antenna branches. Thus, in the case of interleaving, the number of available transmit antennas or independent data streams also enters their different transmit antenna branches. By contrast, classical interleavers only consider the temporal

Scrambling component. The interleaving principle according to the invention is valid not only for V-Blast systems, but in particular also for all MIMO systems which operate without channel information at the transmitter and use classical channel coding methods. For MIMO systems, to which the channel information is available at the transmitter, it is expedient to include the modulation type of each independent data stream in the interleaver structure. Thus, the inventive interleaving principle can advantageously be used for all MIMO systems which use classical channel coding methods.

The multicast antenna system according to the invention on the transmitting side is characterized in particular by the fact that bits adjacent to the interleaver are scrambled in time and transmitted simultaneously by different antennas. Namely, it may happen that the data sent from an antenna has inferior transmission ratios with respect to SNR (for example, through

Shadowing the hand of an operator) than the data sent by the other antennas. This can then be after the deinterleaver in the associated Multiple-antenna receiving system on the receiver side which generates block errors that are more difficult to correct for a convolutional decoder in the receiver. However, if it is largely ensured that the bits adjacent to the interleaver are always transmitted by different antennas, then after the deinterleaver most of the block errors are converted into single errors, which can then be better corrected by a convolutional decoder at the receiver. In this way, the overall block error rate, ie block error rate (BER) of the transmission improves. The transmitting-side MIMO multicast antenna system and the receiving-side multiphase antenna system thereby constitute a combined MIMO multiple transmitting / receiving antenna system.

Claims

claims

1. Interleaver (IL) for a MIMO multiple transmission antenna system (AZ2), which is upstream of a plurality of transmission antenna branches (TXl with TX4) and temporally scrambles adjacent bits of a total data stream (DSI) to be transmitted, characterized in that scrambling means are provided such that adjacent bits in the total data stream (DSI) to be transmitted, in addition to temporal scrambling, can be subdivided into different sub-data streams (DA1 with DA4) in different transmission antenna branches (TX1 with TX4).

2. Interleaver according to claim 1, characterized in that the scrambling means are designed such that the input bits of an incoming, to be processed total data stream (DSI), which are assigned to the indices from 1 to N, temporally scrambled and additionally with respect to their distribution to the different transmission antenna branches (TXl with TX4) according to the following context umindiziert and output at the output of the interleaver (IL):

where l (n, m + (k-1) • NoBu) = Stlndx (k) + (n-1) • fixj ^ -! - J • NoA + BL + 1 + s ^■ NoA ^■ (m-1), mod N, where n = \ ... NoAn, m = l ... NoBu, k = l ... StValLen,

_ (IntLenPaΛ _{Λτ o} NoBpA _ΛT N s = fix • Nobu + 1, IntLenPar = -, = NoBpA

NoBu J NoBu NoA

Stlndx = StVaI (I + {ql) - StShifl, mod StValLen), q = l ... StValLen, StVaI = 1, 1 + NoBu ■ NoA, 1 + 2 • NoBu ^■ NoA, 1 + 3 • NoBu ^■ NoA, ... ≤ N,

where n denotes the n-th transmission antenna branch, NoA is the number of transmission antennas, m is the index of a transmission burst to be respectively interleaved,

StValLen is a parameter for the length of the vector StVaI, and

StShift is an integer index increment parameter.

3. Interleaver according to claim 2, characterized in that the vector StShift is selected such that it is as close as possible to the value G and on the other hand, the largest common divisor of the parameters StShift and StValLen is equal to 1.

4. Deinterleaver (DIL) for a MIMO receive antenna system, which is subordinate to several parallel receive antenna branches (RX1 with RX4), and the bits of the

Partial data streams (DAl * with DA4 *) of the various Receive antenna branches (RXL with RX4) to a total data stream (DSI *) temporally deinterleaved, characterized in that Deinterleavermittel are provided such that in addition to canceling the temporal scrambling of the bits of the incoming partial data streams (DAl * with DA4 *) in addition, an undo of the bits in the received data streams (DAl * with DA4 *) with respect to the different receiving antenna branches (RXl with RX4) is feasible.

A mobile radio communication device (MP) comprising at least one interleaver according to one of claims 1 to 3 in its MIMO multicast antenna system (AZI) and / or at least one deinterleaver according to claim 4 in its MIMO multicast antenna system (RZI).