DE102004017488B4 - A method and apparatus for combining symbols for different transmit antenna diversity modes in a Rake receiver - Google Patents

Abstract

A method for combining symbols in a rake receiver broadcast in different transmit antenna diversity modes and received over different propagation paths, wherein in at least one transmit antenna diversity mode, at least two received symbols are needed to compensate for transmit antenna diversity at the receiver end, with the steps :
Path weighting and compensating the antenna diversity of the symbols of a first symbol stream transmitted in a transmit antenna diversity mode;
Path weighting the symbols of a second symbol stream transmitted in a mode without transmit antenna diversity; and
- Combining corresponding, weighted and possibly antenna diversity compensated symbols of the first and second symbol streams, wherein
Both in path-weighting and compensating the antenna diversity of the symbols of the first symbol stream and in path-weighting the symbols of the second symbol stream, a fixed uniform input-output timing scheme is adhered to, after which at least one of the first symbol of the respective symbol stream is accepted waiting for the subsequent second symbol of the symbol stream to be accepted until ...

Description

The The invention relates to a method and a device for combining of symbols in a rake receiver, wherein the symbols are broadcast in different transmit antenna diversity modes and about different Propagation paths were received.

Mobile third generation systems, such as 3GPP ^(3rd Generation Partnership Project), provide for the use of transmission antenna diversity (so-called TX-antenna diversity). Transmitting antenna diversity means that the transmission signal is emitted from at least two different antennas. If two transmit antennas are used, as is the case, for example, in the Universal Mobile Telecommunications System (UMTS) standard, the radiated signal on one of the two transmit antennas (usually on the connected second antenna) can be coded according to a special rule so that both transmit signal streams be sent at the same time orthogonal to each other. By properly decoding the received signal resulting from a superposition of the antenna signals radiated from the two transmit antennas, the performance of the data transmission system can be significantly improved by TX antenna diversity.

in the UMTS standard, four TX antenna diversity modes are provided: In Normal mode (normal mode) no TX antenna diversity is used, i.e. the signal is emitted by a single antenna. in the STTD mode (Space Time Transmit Diversity) is transmitted via the first antenna of the unchanged transmission data stream and over the second antenna is the STTD-coded Data stream sent out. The STTD encoding causes each two consecutively received symbols are needed to be two in the receiver the symbols underlying the STTD coding. The performed in STTD mode STTD encoding of the over the second antenna radiated data stream is the UMTS standard 3GPP TS 25.211 V4.6.0 (2002-09) in chapter 5.3.1.1. For CLTD (closed-loop Transmit diversity), two transmit antennas are also used. The transmitting antenna services become antenna-specific through feedback information controlled by the receiver back to the transmitter (base station) become. The UMTS standard specifies two different CLTD modes, namely the CLTD1 mode and the CLTD2 mode. Further details are the UMTS standard 3GPP TS 25.214 V4.2.0 (2001-09) in chapters 7.2 (CLTD1 mode) and 7.3 (CLTD2 mode).

The Working principle of Rake receivers is known to be in signal components of the same emitted signal but come via different propagation paths (Paths) to the receiver were separated (i.e., path-wise) to demodulate, synchronize and combine. The synchronization as well as path-wise demodulation takes place in the rake fingers, wherein each propagation path is assigned a rake finger. The outputs the rake finger is a combiner connected downstream of which those symbols, that go back to the same signal, combined.

difficulties occur when over different propagation paths received symbols pointing to the same Signal go back, emitter-side with different TX antenna diversity modes are radiated. This case can occur with UMTS systems when in the Rake receiver Signal is to be demodulated, emitted by two base stations which work with different TX antenna diversity modes. In this case, the combination must take into account that from one base station radiated signal in another TX antennas diversity mode is present as the radiated from the other base station signal. For example, one of the two base stations operates in normal mode and the other base station in STTD mode, can be the one from the former Base station received symbols at the output of rake fingers immediately be further processed while the symbols received from the second base station due to STTD coding must be processed in pairs (as already mentioned, need for Compensating the STTD antenna diversity always processed symbol pairs become).

A possibility to the solution of this problem (combining symbols emitted with different TX antenna diversity modes There are several different hardware modules in the combiner Provide each hardware module for the processing of symbols a particular TX antenna diversity mode. Of the Disadvantage of this solution is that a lot of hardware is required.

• – Einige Symbole, die sogenannten TPC (Transmit Power Control) Symbole, die dazu dienen, eine Leistungsregelung im Sender zu ermöglichen, müssen so schnell wie möglich ausgewertet werden, um eine ausreichend kleine Zeitkonstante der Leistungsregelung zu erreichen.
• – Sofern der Rake-Empfänger mit einer Steuerungs-Pipeline ausgerüstet ist, in welcher Steuerdaten parallel zu und synchron mit den empfangenen Symbolen mitgeführt werden (jedes Steuerdatum ist einem empfangenen Symbol zugeordnet), muss auch der Strom der Steuerdaten in der Steuerungs-Pipeline je nach dem TX-Antennendiversitätsmodus des zugehörigen Symbolstroms unterschiedlich verarbeitet werden. Somit müssen auch für die Steuerdatenverarbeitung TX- Antennendiversitäts-spezifische Hardware-Schaltungen vorgesehen sein.

In addition to the requirement that in the combiner the different TX antenna diversity modes must be taken into account when combining associated symbols, there are also further requirements:

• - Some symbols, the so-called TPC (Transmit Power Control) symbols, which are used to enable power regulation in the transmitter, must be evaluated as quickly as possible in order to obtain a to achieve a sufficiently small time constant of the power control.
• If the rake receiver is equipped with a control pipeline in which control data is carried in parallel with and synchronized with the received symbols (each control data is associated with a received symbol), the flow of control data in the control pipeline must also be dependent the TX antenna diversity mode of the associated symbol stream are processed differently. Thus, also for the control data processing TX antenna diversity-specific hardware circuits must be provided.

Of the Invention is the task of specifying a method, which is a low-cost Combination of emitted with different TX antenna diversity modes Symbol streams in a radio receiver allows. Furthermore, the invention aims to provide a device for combining Symbols of such symbol streams in a rake receiver to accomplish.

EP 1 039 658 A2 describes a method of operating a communications circuit in which a plurality of signals are received from a plurality of remote transmitters and in which it is determined which transmitters use transmitter diversity. In this case, a signal strength of each signal of the plurality of signals is determined.

The The invention is based task by the Features of the independent claims solved. advantageous Embodiments and developments of the invention are specified in the subclaims.

Therefore be in the inventive method the symbols of a first symbol stream, which in a mode with Transmit antenna diversity was compensated, path-weighted and compensated for antenna diversity. The symbols of a second symbol stream which transmit in a mode without transmit antenna diversity became path-weighted. Subsequently, corresponding, weighted and possibly antenna diversity compensated symbols of combined first and second symbol stream. It will both while path-weighting and compensating the antenna diversity of the symbols of the first symbol stream as well as the path weighting of the symbols of the second symbol stream, a fixed uniform input-output timing scheme complied with, in which after receiving a first symbol of the respective symbol stream at least on the acceptance of the waiting for the next second symbol of the symbol stream, to a first weighted and possibly antenna diversity compensated Symbol is output.

In other words, for path-weighting and compensating the antenna diversity of symbols of that symbol stream transmitted in the transmit antenna diversity mode in which at least two received symbols are needed for receiver-side transmit antenna diversity compensation (in the UMTS standard the STTD mode), the above-mentioned input-output timing scheme is mandatory anyway, otherwise no compensation of the antenna diversity would be possible. However, the invention is based on the idea that all symbol streams (irrespective of whether these symbol streams are based on antenna diversity or not) are processed during the path weighting and, if necessary, compensated antenna diversity with this fixed input-output timing scheme. It should be noted that for a symbol stream broadcast without TX antenna diversity, there is in itself no reason to delay the output of the first received symbol in the path weighting until the subsequent second symbol arrives. The same applies to symbol streams which have been transmitted in a transmission antenna diversity mode, unless this mode requires that at least two received symbols are needed for transmitter antenna diversity compensation (in the UMTS standard, this applies to the transmit antenna diversity modes CLTD1 mode and CLTD2 mode). According to the invention, symbols from such symbol streams in the path weighting and the compensation of the transmission antenna diversity are processed in the same way over time as symbols from that symbol stream in which at least two received symbols are required on the receiver side for the compensation of the transmission antenna diversity. The advantage achieved by the method according to the invention is that all the data processing steps to be performed in the signal path behind the path weighting and the possibly required compensation of the transmission antenna diversity in the combiner are independent of the transmission antenna diversity mode used. This is especially true for the combination of symbols transmitted over different propagation paths within the same cell for the standardization of the cell-combined symbols and for the combination of cell-combined, normalized symbols derived from different cells (ie emitted from different base stations).

There in the method according to the invention always the output of the first received symbol by at least one Symbol time delay It is important that this latency critical processes in the Rake receiver no over fee delayed become. This is especially true for the evaluation of transmit power control symbols (TPC symbols), the fastest possible must be done. To one as possible low latency for to ensure such processes a particularly preferred embodiment of the method according to the invention is characterized in that the fixed uniform input-output timing scheme as follows is: while a first symbol period becomes the first symbol of the respective Symbol stream received. While This first symbol time period finds no output of a weighted one and optionally antenna diversity compensated symbol of respective symbol stream instead. While the following second symbol period becomes the following one second symbol of the symbol stream accepted. Well be within this second symbol period both the first weighted and optionally Antenna diversity compensated Symbol as well as the second weighted and optionally antenna diversity compensated Symbol issued.

So while the symbols of each symbol stream on the input side in the symbol time clock (the reason for this is that everyone Rake finger in symbol time clock outputs symbols) becomes a non-regular output timing scheme selected: Both weighted and possibly antenna diversity compensated Symbols are output within a (second) symbol period. The second obtained symbol thus becomes different from the first one obtained Symbol is not delayed by at least one symbol duration. Thereby can be achieved that time-critical processes based on this second symbol can be executed without significant latency, what in the UMTS receiver for the timely evaluation of the TPC symbols of crucial importance is.

It It should be noted that the invention is also applicable to antenna diversity modes a number of transmit antennas greater than two applicable is. If e.g. four transmitting antennas are used, four each successively received symbols needed to be four in the receiver the broadcast antenna diversity encoding identify underlying symbols. In this case, that can first weighted symbol only immediately after receipt of the fourth Symbols are output, and the weighted second, third and The fourth symbol is output a short time later. Also in this case, this output schedule is for all Symbol streams i.e. especially for those symbol streams, used in normal mode.

Preferably is the weighted and possibly antenna diversity compensated second symbol maximum four chip time periods later as the weighted and optionally antenna diversity compensated first symbol issued. This will result in the considered processing (Path-weighting and antenna diversity compensation) for the second symbol a short processing time (maximum of four chip time periods) guaranteed. About that It also ensures that the inventive method for all in the UMTS standard specified spreading factors SF (as spreading factor SF is the number in CDMA (Code Division Multiple Access) systems chips per symbol), since SF = 4 is the minimum Spreading factor is.

A further advantageous embodiment of the method according to the invention characterized in that when accepting the first symbol the same is stored in a memory. When accepting of the second symbol, the first symbol is read from the memory. Subsequently Both the first and second symbols are path-weighted and optionally antenna diversity compensated. Now that will be weighted and possibly antenna diversity compensated first symbol and weighted and possibly antenna diversity compensated second icon stored in the memory. To spend the weighted and optionally antenna diversity compensated second symbol this is read from the memory. The saving of the first symbol and the weighted and optionally antenna diversity compensated second symbol preferably in the same memory location. The particular advantage of this approach is the fact that the space for both symbols is used, that is, to carry out this Process variant only a single memory location of the memory is required per demodulated symbol stream.

Preferably, the transmit antenna diversity mode is the STTD mode or the CLTD1 mode or the CLTD2 mode, and the non-transmit antenna diversity mode is the Normal mode in UMTS standard. As already explained, in this case the combination of symbols in the Rake receiver for all transmit antenna diversity modes can be performed with a single (shared) dedicated hardware.

following the invention with reference to an embodiment with reference closer to the drawings explains; in these shows:

1 a schematic representation of functional blocks of a Rake receiver for the demodulation of signals from different mobile radio cells;

2 a schematic representation of the circuit structure of the combiner of in 1 shown rake receiver;

3 a circuit diagram of in 2 illustrated unit for path-weighting and compensating antenna diversity;

4 a schematic representation of the timing of the data processing in the in 3 illustrated unit for path-weighting and compensating antenna diversity; and

5 a schematic representation of the partitioning of in 2 illustrated memory.

1 shows the functional structure of a rake receiver. The receiver has a plurality of rake fingers RF1, RF2, RF3, RF4 and a combiner MRC (maximum ratio combiner) connected downstream of the rake fingers RF1-4.

Of the Structure of a rake finger RF1-4 is known. A rake finger does not point in an input-side delay stage, a despreading stage and an Integrate & Dump unit on. In the delay stage becomes the path delay of the propagation path to be demodulated. The despreading stage takes a multiplication of the obtained spread-coded signal with the corresponding spreading sequence (in the case of UMTS is the spreading sequence the product of the channelization code and the scrambling code) in front. As a result, from the received total signal, which is an overlay the signals from all physical channels of several base stations, one signal component is filtered out, in the case of UMTS coming from a particular base station (de-scrambling), which is assigned to a specific physical channel (de-channelization) and the over a certain propagation path has been transmitted (setting the specific path delay). The path delay time compensated, despread (de-channelization) and descrambled (de-scrambling) signal will then be in the inte grate & dump unit via SF chips integrated, creating symbols. At the exit of each rake finger RF1-4 is thus a symbol stream for further processing Available.

1 illustrates a situation in which the rake fingers RF1 and RF2 are assigned to a first mobile radio cell A, while the rake fingers RF3 and RF4 demodulate a signal which is radiated by a second mobile radio cell B. Whereas the rake finger RF1 (RF3) demodulates the LOS signal component (line of sight) transmitted via the propagation path P1 (P1 '), the rake finger RF2 (RF4) demodulates a signal component which is propagated via the propagation path P2 (P2'). ) is transmitted and thereby reflected on an obstacle.

The combiner MRC has on the input side for each rake finger RF1-4 a path weighting unit PG1, PG2, PG3, PG4. The path weighting units PG1, PG2 (PG3, PG4) that process a signal from the same cell A (cell B) are followed by an intracell combination unit IZK. In the signal path behind the intracell combination unit IZK is a normalization level NS. If the same physical channel (eg DPDCH: Dedicated Physical Data Channel) is demodulated in the rake fingers RF1, RF2 and RF3, RF4, the outputs of the normalization stage NS are fed to an intercell combination unit EZK. The combined signals of the demodulated channel (eg DPDCH) are at the output 1 Combiner MRC available. At the exits 2 and 3 Cell-specific symbols are output. In the present example, these are cell-specific symbols from the physical channels DPCCH (Dedicated Physical Control Channel), PDSCH (Physical Downlink Shared Channel) and sCCPCH (Secondary Common Control Physical Channel). It should be noted that a path-specific normalization is possible by pulling the normalization level NS in front of the intracell combination unit IZK becomes.

It should also be noted that the in 1 As is well known, both the rake fingers RF1-4 and the path weighting units PG1-4 can be time multiplexed, ie, in extreme cases, only one rake at a time Finger RF1 and a path weighting unit PG1. The same applies to the other components IZK, NS and EZK.

• – Die Funktion der Pfad-Gewichtungseinheit PG1-4 besteht darin, durch Multiplikation des jeweiligen Symbolstroms mit einem geeigneten Gewichtsfaktor die bei der Signalübertragung über die Luftschnittstelle aufgetretene Signaldämpfung und Phasenrotation auszugleichen und darüber hinaus den senderseitig eingesetzten Sendeantennendiversitätsmodus (normal mode, STTD, CLTD1-Modus, CLTD2-Modus) zu kompensieren.
• – Die Aufgabe der Intrazell-Kombinationseinheiten IZK besteht darin, Symbole eines Signals (physikalischen Kanals), die in einer Mobilfunkzelle über verschiedene Ausbreitungspfade P1, P2 bzw. P1', P2' übertragen wurden, zu kombinieren.
• – Die Aufgabe der Normierungsstufe NS besteht darin, eine geeignete Gewichtung (Normierung) der erhaltenen gewichteten und zellweise kombinierten Symbole in Abhängigkeit von dem SINR (Signal-to-Interference and Noise Ratio) durchzuführen. Hierfür ist eine Schätzung des in jeder Zelle (bzw. bei fingerspezifischer Normierung des in jedem Pfad) vorhandenen Rauschpegels und eine Leistungsmessung des Nutzsignals erforderlich. Da die Art und Weise der Normierung für die vorliegende Erfindung keine Rolle spielt, wird auf die Funktionsweise der Normierungsstufe NS im Folgenden nicht näher eingegangen.
• – Wie in der 2 noch näher erläutert, werden in dem Kombinierer MRC bestimmte Steuerinformationen aus dem Kanal DPCCH extrahiert, die für jede Zelle unterschiedlich sein können. Es handelt sich hierbei beispielsweise um die TPC-Symbole und um die TFCI-Symbole (TFCI: Transport Format Combination Indicator).
• – In der Interzell-Kombinationseinheit EZK werden normierte Symbole desselben physikalischen Kanals (Signals), die aus unterschiedlichen Zellen erhalten wurden, addiert.

The operation of the combiner MRC is as follows:

• The function of the path weighting unit PG1-4 is to equalize the signal attenuation and phase rotation occurring in the air-interface signal transmission by multiplying the respective symbol current by a suitable weighting factor, and moreover, to use the transmitter-antenna diversity mode (normal mode, STTD, CLTD1 mode , CLTD2 mode).
• The task of the intracell combining units IZK is to combine symbols of a signal (physical channel) transmitted in a mobile radio cell via different propagation paths P1, P2 or P1 ', P2'.
• The task of the normalization stage NS is to perform a suitable weighting (normalization) of the weighted and cell-by-cell combined symbols obtained as a function of the signal-to-interference and noise ratio (SINR). This requires an estimate of the noise level present in each cell (or finger-specific normalization of the path in each path) and a power measurement of the wanted signal. Since the manner of normalization for the present invention is irrelevant, the operation of the normalization stage NS will not be discussed in more detail below.
• - Like in the 2 to be explained in more detail, in the combiner MRC certain control information is extracted from the channel DPCCH, which may be different for each cell. These are, for example, the TPC symbols and the TFCI symbols (TFCI: Transport Format Combination Indicator).
• In the inter-cell combination unit EZK, normalized symbols of the same physical channel (signal) obtained from different cells are added.

wobei

C

Anzahl der zum Empfangssignal beitragenden Zellen ist,

L_i

Anzahl der zum Empfangssignal beitragenden Pfade in der Zelle i ist,

S_cha,i,j

das an dem Eingang des Kombinierers MRC für den Kanal cha, die Zelle i und den Pfad j empfangene Symbol ist,

n_cha,i

der Normierungsfaktor für den Kanal cha und die Zelle i ist,

w_i,j

der Gewichtsfaktor zu dem Pfad j der Zelle i ist,

S_cha

das resultierende Symbol für den Kanal cha ist.

The operation of the combiner MRC is described by the following equation; in equation (1) different transmit antenna diversity modes are not considered (equation (1) applies to the normal mode without transmit antenna diversity):

in which

C

Number of cells contributing to the received signal,

L _i

Number of paths contributing to the received signal in cell i,

S _{cha, i, j}

is the symbol received at the input of the combiner MRC for the channel cha, the cell i and the path j,

n _{cha, i}

is the normalization factor for channel cha and cell i,

w _{i, j}

is the weighting factor to the path j of cell i,

S _cha

the resulting symbol for the cha channel is.

Essential for the invention is that after the path weighting, ie behind the path or weighting units PG1-4 (dashed line 4 ), Antenna diversity mode compensated symbols are passed to the subsequent functional units IZK, NS, EZK, etc. with an identical output timing scheme. The signal processing behind the dot-dash line 4 is thus independent of the used transmit antenna diversity mode. In particular, in the intercell combining unit EZK, it is not necessary to consider whether different transmission antenna diversity modes exist in the cells 1 and 2 be used. This allows a simple hardware structure of the combiner MRC.

2 shows a block diagram of the combiner MRC. The combiner MRC are functionally preceded by several rake fingers. There may either be multiple physical rake fingers (not shown), or there may be only one physical rake finger that forms multiple "virtual" rake fingers by time division multiplexing.

Time-multiplexed rake fingers are known and, for example, in the application DE 102 20 906 A1 disclosed.

Further becomes the path weighting unit PG (here also time division multiplexed is operated and therefore at any time one of the path weighting units PG1-4 represents) a control pipeline ("control pipe "). Control data is transferred in the control pipeline i.e. Each data symbol is one (or more) specific control date assigned in parallel and in the entire signal processing transported at the same time ("symbol-accompanying") with "his" symbol becomes.

If a multiplex operation of the rake fingers and the combiner MRC is assumed, the path weighting unit PG is informed of the current finger number n via the control pipeline. Depending on the current finger number n, the required path weights w _{i, j are} read from a weight table WT. Due to the assignment of a rake finger to a path j in a cell i, n uniquely identifies the value pair (i, j).

The path weights w _{i, j} are further dependent on the transmit antenna diversity mode employed in cell i.

The path weighting unit PG has a write data connection 10 and a read data connection 11 with a symbol memory in which a symbol table ST is created.

From the path weighting unit PG, the weighted symbols become over a data connection 12 and the symbol-accompanying control data via a data connection 13 the intracellular unit IZK forwarded. The intracell combination unit IZK provides via a data connection 14 cell accumulated symbols and via a control data connection 15 the associated control data on. The normalization unit NS receives the normalization factors n _{cha, i} and obtains information concerning the cell i and the channel cha of the cell accumulated symbols to be normalized. The unit TFCI-EX performs extraction of cell-specific normalized TFCI symbols, and the unit TPC-EX performs extraction of cell-specific normalized TPC symbols from the normalized symbols.

The How the path weighting unit PG works in the various Transmit antenna diversity modes is as follows:

It becomes a symbol stream with respect to a path j and a signal at the input of the path weighting unit PG considered.

r

empfangenes Symbol (entweder gerade oder ungerade) an dem Eingang der Pfad-Gewichtungseinheit PG

r_e und r_o

gerade bzw. ungerade empfangene Symbole

z

ein gewichtetes Symbol, das über die Datenverbindung 12 von der Pfad-Gewichtungseinheit PG ausgegeben wird. Es kann entweder gerade (z_e) oder ungerade (z_o) sein.

h₁ und h₂

Kanalgewichte der Antenne 1 bzw. Antenne 2 entsprechend der (reellen) Amplitudendämpfung und der Phasenrotation, die durch die Luftschnittstelle bewirkt werden. Die Kanalgewichte h₁ und h₂ werden durch eine Kanalschätzung basierend auf Pilotsymbolen (z.B. den Pilotsymbolen in dem CPICH-Kanal (Common Pilot Channel) ermittelt).

W₁ und W₂

Gewichte, die in dem CLTD-Modi der Sendeantenne 1 bzw. der Sendeantenne 2 zugeordnet sind.

The individual symbols should be indexed with a continuous symbol index. Even symbols are even-numbered symbols, odd-numbered symbols are odd-numbered symbols. By definition, the first symbol of a frame has the index 0 (zero) and is therefore a straight symbol. The following notation is used:

r

received symbol (either even or odd) at the input of the path weighting unit PG

r _e and r _o

even or odd received symbols

z

a weighted symbol over the data connection 12 is output from the path weighting unit PG. It can be either even (z _e ) or odd (z _o ).

h ₁ and h ₂

Channel weights of the antenna 1 or antenna 2 according to the (real) amplitude attenuation and the phase rotation caused by the air interface. The channel weights h ₁ and h ₂ are determined by a channel estimation based on pilot symbols (eg, the pilot symbols in the Common Pilot Channel (CPICH)).

W ₁ and W ₂

Weights in the CLTD modes of the transmitting antenna 1 or the transmitting antenna 2 assigned.

All cited Sizes are complex-valued.

The following equations include both the consideration of signal distortion and the compensation of the respective transmit antenna diversity mode:
Normal mode: z = h * 1 · R (2) STTD mode: z e ≈ h * 1 · r e + h 2 · r * O and Z O ≈ -h 2 · r * e + h * 1 · r O (3) CLTD1 mode and CLTD2 mode z = (W 1 ·H 1 + W 2 ·H 2 * * R (4) where * denotes the complex conjugation.

W_1D und W_2D

Antennen-Gewichte für die Sendeantennen 1 bzw. 2 für den DPCH-Kanal

W_1S und W_2S

Antennen-Gewichte für die Sendeantennen 1 bzw. 2 für den PDSCH-Kanal

In the CLTD modes different antenna weights are used on the transmitter side for the transmission of the DPCH channel and the PDSCH channel:

W _1D and W _2D

Antenna weights for the transmit antennas 1 respectively. 2 for the DPCH channel

W _1S and W _2S

Antenna weights for the transmit antennas 1 respectively. 2 for the PDSCH channel

In order to enable processing of symbols in all transmit antenna diversity modes, the path weighting unit PG is supplied with the weights C ₁ and C ₂ given in Table 1 according to the invention.

Table 1 Weights delivered to PG

The above equations show that only in the STTD mode two received symbols r _e and r _{o are} needed to calculate a weighted and antenna diversity mode compensated symbol z _e and z _o, respectively. In the other transmit antenna diversity modes (normal mode, CLTD1 mode, CLTD2 mode), in principle any received symbol r could be weighted immediately and compensated for antenna diversity. Despite the advantage (lowest possible latency) of such an approach, according to the invention, for all transmit antenna diversity modes, one and the same identical input-output timing scheme is used for received / output symbols in the path weighting unit PG.

The input-output timing scheme of the path weighting unit PG according to the invention common to all transmission antenna diversity modes is shown in FIG 4 shown. In 4 the demodulation of a channel (eg DPCH) with a spreading factor SF = 256 is assumed. The received symbols r therefore have the same length as the symbols of the CPICH channel CPICH0, CPICH1, CPICH2, CPICH3.

• 1. Wenn ein gerades Symbol r (Symbol 0) an der Pfad-Gewichtungs-Einheit PG ankommt, wird es gespeichert.
• 2. Wenn das darauffolgende ungerade Symbol (Symbol 1) ankommt, werden 2.1 sowohl das gerade Symbol (Symbol 0) als auch das ungerade Symbol (Symbol 1) gewichtet; 2.2 das gewichtete gerade Symbol (gewichtetes Symbol 0) wird ausgegeben; und 2.3 das gewichtete ungerade Symbol wird gespeichert, und zwar an derselben Adresse, unter welcher das empfangene gerade Symbol (Symbol 0) gespeichert war.
• 3. Eine kurze Zeitdauer (z.B. 4 Chips) später wird das gewichtete ungerade Symbol (gewichtetes Symbol 1) ausgegeben.

This in 4 illustrated embodiment of the method according to the invention comprises three steps:

• 1. When a straight symbol r (symbol 0) arrives at the path weighting unit PG, it is stored.
• 2. When the subsequent odd symbol (symbol 1) arrives, 2.1 both the even symbol (symbol 0) and the odd symbol (symbol 1) are weighted; 2.2 the weighted even symbol (weighted symbol 0) is output; and 2.3 the weighted odd symbol is stored at the same address under which the received even symbol (symbol 0) was stored.
• 3. A short period of time (eg 4 chips) later, the weighted odd symbol (weighted symbol 1) is output.

It it is noted that when demodulating a channel with a spreading factor SF <256 the received symbols r shorter as the CPICH symbols CPICH0, CPICH1, ..., are.

As already mentioned, the weights C ₁ and C _{2 are} based on the ent in the CPICH channel pilot symbols CPICH0, CPICH1, CPICH2, CPICH3, ... calculated by channel estimation. If the channel to be demodulated (eg DPCH, PDSCH or sCCPCH) has the spreading factor SF = 256, the even symbol is always weighted with the weight for the next odd symbol and the weights for the even symbols are never used. This is because the CPICH channel has the fixed spreading factor SF = 256 and therefore weights C ₁ , C _{2 are} always supplied every 256 chips.

• – Die ausgegebenen Symbole werden stets (für sämtliche Sendeantennen-Diversitätsmodi) zu festen vorgegebenen Zeiten ausgegeben (bei den geraden Symbolen beträgt die Eingabe-Ausgabe-Verzögerung ein Datensymbol, bei den ungeraden Symbolen beträgt die Eingabe-Ausgabe-Verzögerung die fest vorgegebene Zeitdauer, hier 4 Chips). Einander entsprechende Symbole aus unterschiedlichen Zellen (in welchen unterschiedliche Sendeantennen-Diversitätsmodi eingesetzt werden) sind stets zueinander zeitlich ausgerichtet. Sie können im weiteren Verarbeitungsweg im Gleichtakt weiterverarbeitet und in der Interzell-Kombinationseinheit EZK direkt addiert werden.
• – Das ungerade gewichtete Symbol 1 wird kurz nach dem gewichteten geraden Symbol 0 ausgegeben. Dies ist insbesondere für die Extraktion der TPC-Symbole des DPCCH-Kanals wichtig, die so schnell wie möglich (im Prozessor DSP) weiterverarbeitet werden müssen, da die Reaktionszeit auf die TPC-Befehle kritisch ist (innerhalb von 512 Chips muss der Empfänger spätestens auf TPC-Befehle reagieren). Da in jedem möglichen Zeitschlitzformat bei einem Spreizfaktor SF < 512 das letzte TPC-Symbol im TPC-Feld an einer ungeraden Position ist, wird gewährleistet, dass für die Verarbeitung der TPC-Symbole in dem Kombinierer MRC lediglich vier Chip-Zeitdauern (Verarbeitungszeit der Pfad-Gewichtungseinheit PG) plus der Verarbeitungszeit in den übrigen Prozessierungseinheiten benötigt wird. Dieses Prinzip bewirkt, dass die Latenz des letzten TPC-Symbols in dem TPC-Feld innerhalb des Kombinierers MRC unabhängig von dem Spreizfaktor SF des DPCH-Kanals ist.

This in 4 illustrated embodiment of the method according to the invention has the following advantages:

• - The output symbols are always output (for all transmit antenna diversity modes) at fixed given times (for the even symbols the input-output delay is a data symbol, for the odd symbols the input-output delay is the fixed duration, here 4 chips). Corresponding symbols from different cells (in which different transmit antenna diversity modes are used) are always aligned with each other in time. They can be further processed in the further processing path in common mode and added directly in the intercell combination unit EZK.
• The odd weighted symbol 1 is output shortly after the weighted even symbol 0. This is particularly important for the extraction of the TPC symbols of the DPCCH channel, which must be processed as fast as possible (in the DSP processor), since the response time to the TPC commands is critical (within 512 chips, the receiver must be at latest TPC commands respond). Since the last TPC symbol in the TPC field is in an odd position in every possible time slot format with a spreading factor SF <512, it is ensured that only four chip time periods (processing time of the path Weighting unit PG) plus the processing time in the other processing units. This principle causes the latency of the last TPC symbol in the TPC field within the combiner MRC to be independent of the spreading factor SF of the DPCH channel.

at the method according to the invention Although it is disadvantageous that even with the transmit antenna diversity modes CLTD1 mode, CLTD2 mode and normal mode in the path weighting unit PG even Symbols and odd weighted symbols are cached have to. Furthermore, the over transferred the control pipeline Control information of a corresponding (synchronous) processing be subjected. These disadvantages, however, are due to the already addressed benefits accepted.

3 shows a circuit diagram of the path weighting unit PG. The path weighting unit PG comprises a state machine SM (also referred to as state machine) with a state register SR, a calculation unit CALC, an output stage OS, a two-way multiplexer MUX1 and three two-way demultiplexers DMUX1, DMUX2 and DMUX 3. The control pipeline ("control pipe ") is the state machine SM supplied. The state machine SM serves the sequence control of the illustrated circuit. If the received symbol r is a straight symbol r _e , it is written into the symbol table ST by the demultiplexer DMUX1 via the multiplexer MUX1 in accordance with a control signal ct1. If the received symbol r is an odd symbol r _o , this is fed to the calculation unit CALC. The stored even symbol r _e is via the read data connection 11 and the demultiplexer DMUX2 read and also the calculation unit CALC forwarded. Now the calculation unit CALC is activated via an activation signal ena1. The calculation unit CALC performs the transmission antenna diversity specific weighting of the two symbols r _e and r _o . According to equations (2) to (4), the weighting comprises one or more multiplication operations and, in the case of the STTD mode, an addition or subtraction. The weighted even symbol z _e is fed to the output stage OS via the demultiplexer DMUX3 and output. The weighted odd symbol z _o is transmitted via the demultiplexer DMUX3 and the multiplexer MUX1 as well as the write data connection 10 entered in the symbol table ST. Four chip durations later, the weighted odd symbol z _o stored in the symbol table becomes over the write data connection 11 and the demultiplexer DMUX 2 the output stage OS supplied and output. The timing of the output stage OS via an activation signal ena2, which is provided by the state machine SM. In the 3 shown circuit is in hard-wired form, ie realized as a dedicated hardware circuit.

Like the circuit diagram in 3 As can be seen, an analog (ie temporally synchronous) processing is performed for the control data in the control pipeline. This ensures that the control data output by the output stage OS continue to be symbol-accompanying at the output of the path weighting unit PG, ie to preserve their time assignment to the output symbols z.

5 shows the partitioning of the symbol table ST. For each rake finger, two memory locations are provided, namely a memory space for the control data and a memory space for the (even or odd-weighted) symbols.

In the present example there are memory locations for N _RF rake fingers (however, due to the time-division multiplexing operation, as already mentioned, there must not be N _RF physical rake fingers). For rake fingers that demodulate different paths with respect to the same signal, corresponding symbols / weighted symbols are always stored in the memory areas in each multiplex cycle, even if the signal was transmitted with different transmit antenna diversity modes over the paths.

Of the Multiplex operation of the rake finger can, as already mentioned, for example done in the way that only a single physical rake finger is present, and a multiplexing cycle spans four chip periods (i.e., within four chip periods, each rake finger becomes multiplexed once ) Driven.

Claims (12)

Method of combining symbols in one Rake receiver, which broadcast in different transmit antenna diversity modes and over different Propagation paths were received, wherein in at least one mode with broadcast antenna diversity at least two received symbols are needed at the receiver side to compensate for transmit antenna diversity, with the steps: - path weights and compensating the antenna diversity of the symbols of a first one Symbol stream which transmit in a transmit antenna diversity mode has been; - path weights the symbols of a second symbol stream, which in a mode without Transmit antenna diversity has been; and - Combine mutually corresponding, weighted and possibly antenna diversity compensated Symbols of the first and second symbol streams, where - either while path-weighting and compensating the antenna diversity of the symbols of the first symbol stream as well as the path weighting of the symbols of the second symbol stream, a fixed uniform input-output timing scheme is maintained, in which after receiving a first Symbols of the respective symbol stream at least on the accept the next second symbol of the symbol stream is waited for, to a first weighted and possibly antenna diversity compensated Symbol is output. Method according to claim 1, characterized, that the fixed uniform input-output time scheme is: - during one first symbol time duration - Receive the first symbol of the respective symbol stream and - no output a weighted and possibly antenna diversity compensated Symbols of the respective symbol stream; - during the following second Symbol duration - Receive of the subsequent second symbol of the symbol stream and - Output of the first weighted and possibly antenna diversity compensated Symbols and the second weighted and possibly antenna diversity compensated symbol. Method according to claim 2, characterized, that - during the second symbol time period first the weighted and optionally Antenna diversity compensated first symbol is issued and - maximum 4 chip time periods later the weighted and possibly antenna diversity compensated second Symbol is output. Method according to claim 2 or 3, characterized by the steps of - taking the first symbol storing it in a memory (ST); Upon receiving the second symbol, reading the first symbol from the memory (ST) and weighting and optionally antenna diversity compensating the first and second symbols; at closing - outputting the weighted and possibly antenna diversity compensated first symbol and - storing the weighted and optionally antenna diversity compensated second symbol in the memory (ST); after that - to output the weighted and possibly antenna diversity compensated second symbol reading it from the memory (ST). Method according to claim 4, characterized in that that storing the first symbol and the weighted and, where appropriate Antenna diversity compensated second icon on the same location. Method according to one of the preceding claims, characterized thereby extracting transmit power control symbols the path-weighted and possibly antenna diversity compensated first or second symbol stream. Method according to one of the preceding claims, characterized characterized in that the mode with transmit antenna diversity is the STTD mode or the first CLTD mode or the second CLTD mode and in the Mode without transmit antenna diversity is the normal mode in the UMTS standard. Device for combining symbols in one Rake receiver, which broadcast in different transmit antenna diversity modes and over different Propagation paths were received, wherein in at least one mode with broadcast antenna diversity at least two received symbols are needed at the receiver side to compensate for transmit antenna diversity, with: - at least a unit (PG; PG1, PG2, PG3, PG4) for path-weighting and compensating the antenna diversity of the symbols a first symbol stream transmitting in a transmit antenna diversity mode was, and to the path-weighting the symbols of a second symbol stream, which in a mode without Transmit antenna diversity was, and - one Unit (EZK) for combining corresponding weighted ones and optionally antenna diversity compensated symbols of first and second symbol streams, where The unit (PG; PG1, PG2, PG3, PG4) for path weighting and optionally compensating the antenna diversity the symbols independently of whether the first symbol stream or the second symbol stream is being processed will comply with a fixed uniform input-output schedule which after accepting a first symbol of the respective Symbol stream at least on the acceptance of the following second symbol of the symbol stream is waited until a first weighted and optionally antenna diversity compensated symbol output becomes. Device according to claim 8, characterized, that the unit (PG; PG1, PG2, PG3, PG4) for path weighting and optionally compensating the antenna diversity of the symbols is designed, symbol streams according to the following to process consistent time input-output schema: - during one first symbol time duration - Receive a first symbol of the respective symbol stream and - no output a weighted and possibly antenna diversity compensated Symbols of the respective symbol stream; - during a subsequent one second symbol period - Receive of the subsequent second symbol of the symbol stream and - Output of the first weighted and possibly antenna diversity compensated Symbols and the second weighted and possibly antenna diversity compensated symbol. Apparatus according to claim 9, characterized in that the unit (PG; PG1, PG2, PG3, PG4) for path-weighting and optionally compensating the antenna diversity of the symbols comprises: - at least one memory (ST) for storing the first symbol and for storing the weighted and possibly antenna diversity compensated second symbol; A calculation unit (CAL) for path-weighting and possibly antenna diversity compensating symbols of the first and second symbol streams, and a state machine (SM) for controlling the timings of accesses to the memory (ST) and the calculations of the calculation unit (CALC). Device according to one of claims 8 to 10, characterized by a unit (TPC-EX) for extracting transmission power control symbols, in the signal path behind the unit (PG; PG1, PG2, PG3, PG4) for Path weighting and possibly compensating the antenna diversity of the symbols is arranged. Device according to one of claims 8 to 11, characterized in that the device (MRC) for combining is sent according to the UMTS standard Symbols, where the transmission antenna diversity mode is the STTD mode or the first CLTD mode or the second CLTD mode and in the mode without transmit antenna diversity around the normal mode in the UMTS standard is.