WO2004006524A1 - Device and method for determining the deviation of the carrier frequency of a mobile radio device from the carrier frequency of a base station - Google Patents

Abstract

The invention relates to a device for determining the frequency deviation (105) of a mobile radio device from a base station that emits a sequence of symbols. Said device comprises a unit (6-11) for calculating terms, whereby a term is composed of two symbols of the sequence received by the mobile radio device, and the term is used to determine the phase difference of the two symbols. The device further comprises a unit (14, 15) for establishing groups on the basis of the terms, whereby a term is associated with a group by means of the features of the symbols on which it is based, and a unit (39) for calculating the deviation (105) by means of a group.

Description

description

Device and method for determining the deviation of the carrier frequency of a mobile radio device from the carrier frequency of a base station

The invention relates to a device by means of which the / deviation of the carrier frequency of a mobile radio device from the carrier frequency of a base station can be determined. The invention further relates to a corresponding method.

To transmit symbols between a base station and a mobile radio device, the symbols are modulated onto a carrier frequency in the transmitter and demodulated in the receiver.

It is necessary for the mobile radio device to have the same carrier frequency as the base station. However, if there is a deviation in the carrier frequency in the mobile radio device, the deviation must be determined so that it can then be compensated for. Such

Frequency deviation can be caused in the mobile radio device, for example, by tolerances of the oscillator generating the carrier frequency. Another reason for frequency shifts can be temperature fluctuations. Furthermore, movements of the mobile radio device relative to the base station lead to Doppler frequency shifts.

As a rule, the phase difference between two successive symbols received by the mobile radio device is measured to determine the deviation of the carrier frequency of the mobile radio device, a known data sequence modulated onto the symbols possibly having to be demodulated beforehand. Since the symbols received are complex symbols, they can be represented by pointers in the complex number plane. If the two symbols were the same when they were generated in the base station, the phase difference between the of the two symbols received, the angle of rotation of the associated pointers can be viewed in the complex number plane. The phase difference represents a direct measure of the frequency difference between the carrier frequency of the base station and the carrier frequency of the mobile radio device.

In the UMTS (Universal Mobile Telecommunications System) standard, the frequency error of the mobile radio device can be determined using the pilot signal (Common Pilot Channel; CPICH). The pilot signal is one sent out by the base station

Signal by means of which the same pilot symbol or a continuously recurring pattern of two different pilot symbols is continuously transmitted. The pilot signal is therefore particularly suitable for the phase difference measurement described above.

The pilot symbols received by the mobile radio device are referred to below with r, the integer index _k indicating the chronological order of the pilot symbols r _k . The frequency deviation Δf can be calculated from the phase difference Δφ measured between two pilot symbols ri and r _k received directly one after the other using the following equation (1):

Δf = ^ üt, (1)

2πT ₌

where the time T _Ξ denotes the time interval between the transmission of the pilot symbols ri and r _k . The pilot symbol rate is calculated from 1 / T _S and is 15 kHz in the UMTS standard.

From the pilot symbol r _k and the complex conjugate

Pilot symbol rζ _i _ ₁ a complex product U can be formed:

Das Argument des komplexen Produkts Uk gibt die Phasendifferenz Δφ an:

The argument of the complex product Uk gives the phase difference Δφ:

Δφ = arg (U _k ) = (3)

The above equations (1) to (3) provide a calculation rule with which the

Frequency deviation Δf of the mobile device can be estimated. For the uniqueness range | Δf | this estimate results in:

| .DELTA.f | <= 7.5 kHz (4)

2T _S

For small phase differences Δφ, the variance var (Δφ) of the distribution of the phase difference Δφ with additive white Gaussian noise with a signal-to-noise ratio E _s / N ₀ and averaging over L values can be calculated approximately as follows:

So far, two pilot symbols rk and rk-i have been considered, which follow one another directly in the chronological sequence of the pilot symbols. However, the consideration of two pilot symbols r _k and r _k - _{D /} which are separated by D symbols in the chronological sequence of the pilot symbols has certain advantages. To make these advantages plausible, parameter D in equations (2), (4) and (5) must be taken into account:

U _k = r _k _ _D ^• r _k (6) 7.5 kHz

| .DELTA.f | <(7)

2T _S DD

The advantage of introducing the parameter D can be seen from equation (8): Increasing the parameter D leads to a reduction in the variance var (Δφ). However, increasing the parameter D according to equation (7) also leads to a reduction in the uniqueness range | Δf | ,

When operating the base station in STTD (Space Time Transmit Diversity) mode, the radio signal is transmitted by two antennas of the base station. In this case, the complex product U _k must be calculated separately for both antennas.

In known mobile radio devices, the deviation of the carrier frequency of the mobile radio device from the carrier frequency of the base station is calculated completely in the firmware by means of a digital signal processor. If several base stations and several transmission paths per base station are examined, all data are transmitted path-specifically to the digital signal processor. This leads to a high workload of both the digital signal processor and the data bus over which the data is transmitted.

The object of the invention is to provide a device for determining the deviation of the carrier frequency of a mobile radio device from the carrier frequency of a base station, in which the necessary computing operations are carried out at low cost. A corresponding procedure is also to be specified.

The problem underlying the invention is characterized by the features of independent claims 1 and 17 solved. Advantageous further developments and refinements of the invention are specified in the subclaims.

Using the device according to the invention, the deviation of the carrier frequency of a mobile radio device from the carrier frequency of at least one base station can be determined in the UMTS standard. For this purpose, a sequence of complex pilot symbols known in the mobile radio device is transmitted to the mobile radio device by radio from each base station. The device according to the invention contains a first, a second and a third unit. Terms are calculated using the first unit. A term is formed from at least two different pilot symbols of the sequence received by the mobile radio device. Furthermore, the phase difference between the two pilot symbols can be determined from a term. The second unit is used to form groups from the terms, a term being sorted into a group on the basis of features or properties of the pilot symbols on which it is based. The third unit is used to calculate the frequency deviation based on the terms of at least one group.

The features or properties of the pilot symbols, on the basis of which the pilot symbols are sorted into groups, relate, for example, to the affiliation to a specific base station from which the pilot symbols were transmitted, the path via which the pilot symbols were transmitted, or the transmission mode (STTD, normal Mode) of the pilot symbols. The device according to the invention can obtain information about such features or properties, for example, from the RAKE receiver in which the pilot symbols are obtained from pilot signals by demodulation.

An advantage of the invention lies in the combination of the terms into groups. The third unit, which is the final arithmetic operations for determining the Frequency deviation, not all terms need to be supplied as individual results due to the group formation, but only the intermediate results available for the groups. As a result, the data transfer on the data bus arranged between the second and the third unit is reduced, and the third unit is burdened with fewer computing operations. Another advantage of group formation can be seen in the fact that the group formation can be carried out according to criteria that are meaningful and inexpensive for further calculations.

For example, it is advantageous to combine the terms relating to a selection of the strongest signal transmission paths of each base station in a group. This can help reduce the Doppler effect. The combination of several paths for the formation of results also increases the quality of the results using diversity.

The first unit and the second unit are advantageously in the form of hard-wired circuits. This measure has an advantageous effect in that the work steps to be carried out by the first and second units are computationally intensive, but are uncomplicated and can therefore be carried out by hardware in a cost-effective manner.

A further advantageous embodiment of the invention provides that the third unit is replaced by a

Digital signal processor is realized. This maintains a high degree of flexibility of the device according to the invention. Furthermore, those to be executed by the digital signal processor

Computing operations with regard to the calculation of the frequency deviation are low, so that the digital signal processor has sufficient computing capacity for other tasks. For example, the criteria by which the terms in the second unit are sorted into groups can also be specified by the digital signal processor. The Digital signal processor can also take on other control tasks.

According to a preferred embodiment of the invention, the first unit is designed for the calculation of complex products, a complex product being formed from at least two different pilot symbols of the sequence received by the mobile radio device and the argument of the complex product indicating the phase difference between the two pilot symbols. As an alternative to this type of calculation, the phase angles of the at least two different pilot symbols could also first be calculated separately from one another, and then the phase difference could be calculated from the phase angles.

The first unit preferably contains a multiplier which has a first input and a second input. A circuit branch is arranged in front of the first input and contains a delay element and a unit for transforming a complex value into its complex conjugate value. The circuit branch is fed by the one pilot symbol and the second input is fed by the other pilot symbol.

The delay time of the delay element can advantageously be adjustable and specifiable.

The delay element can be implemented, for example, by a rewritable memory. A pilot symbol appears in front of his in the rewritable memory

Output temporarily stored as long as it corresponds to the delay time assigned to this pilot signal.

Furthermore, it can preferably be provided that an accumulator is arranged between the first unit and the second unit, which accumulates an adjustable number of terms in each case. The terms or, if appropriate, the accumulated terms of a group are advantageously added up in the second unit.

Furthermore, it is advantageous to provide a rewritable memory in which the integration results of the groups can be buffered. This means that a group can be accessed quickly as soon as a new term is to be added to this group.

A particularly preferred embodiment of the invention provides that the first unit and the second unit and, if appropriate, the accumulator are each designed in duplicate. This measure is particularly advantageous if a base station from which the mobile radio device receives pilot signals is operated in the STTD operating mode. A separate processing path is then available for the pilot symbols of each antenna of the base station.

When operating the base station in the STTD operating mode, it is also advantageous if the first two units are preceded by a fourth unit, which separates the received pilot symbols according to the associated antennas.

A rewritable memory is preferably connected upstream of the first unit or possibly the fourth unit. The rewritable memory is used to decouple the RAKE receiver of the mobile radio device from the downstream units of the device according to the invention.

A further preferred embodiment of the invention provides that mean values from terms or from groups of terms can be formed within the third unit. The device according to the invention preferably has a control unit. The control unit can, among other things, carry out control tasks for forming the groups. In particular, the control tasks can include the control of the accumulation of the terms in the given groups. Furthermore, the control unit can carry out further tasks, such as, for example, specifying the delay times for the delay elements. The digital signal processor can optionally take over tasks of the control unit.

An essential aspect of the invention relates to the features of the pilot symbols on the basis of which the groups are formed. These features advantageously relate to the associated base station or the associated ones

Transmission paths. For example, all terms that have arisen from pilot symbols of the same base station can be combined into a group. It is also conceivable to combine the terms that result from certain transmission paths in a group. It can be provided, for example, that the terms of the signal paths with the strongest signal are combined in a group by a base station. This would reduce the effects of the Doppler frequency shift caused by movement of the mobile device in the results of this group. Alternatively, the transmission paths of different base stations can be divided into different groups. This enables the calculation of the double frequency shift of a specific base station. The terms can always be several in all group formations

Be assigned to groups. The groups can also be defined across cells.

The method according to the invention serves to determine the deviation of the carrier frequency of a mobile radio device from the carrier frequency of at least one base station. From each base station to the mobile device is one in the Mobile device known sequence of complex pilot symbols transmitted by radio. To determine the carrier frequency deviation, terms are calculated in a first method step, each consisting of at least two different pilot symbols that of the

Mobile device received sequence are formed. The phase difference between the two pilot symbols can be determined from a term. In a second method step, groups are formed from the terms, a term being assigned to a group on the basis of features of the pilot symbols on which it is based. In a third method step, the carrier frequency deviation is calculated using the terms of at least one group.

By combining the terms into groups according to the invention, the determination of the frequency deviation can be carried out more efficiently than is possible with conventional methods. For example, a frequency shift caused by the Doppler effect can be reduced by a suitable group selection.

The two pilot symbols, from each of which a term of a group is formed, are preferably separated by a predetermined number of positions in the sequence of the pilot symbols.

According to a particularly preferred embodiment of the method according to the invention, the calculations are carried out twice for a group, the two calculations differing in that a different number of digits by which the pilot symbols used for the calculations lie apart is selected. This number of digits can be expressed, for example, by the parameter D introduced in equations (6) to (8). For example, it can be provided to first form a group in which a value greater than 1 is used for the parameter D, so that the variance of the phase difference measurement and thus the error of the frequency estimate are comparatively high turn out small. Furthermore, the otherwise identical calculations are carried out with the value 1 for the parameter D. This makes it possible to check whether the smaller uniqueness range | Δf | the calculation with the larger value for parameter D is not left.

The invention is explained in more detail below by way of example with reference to the drawings. In these show:

Fig. 1 is a schematic diagram of a in a

Embodiment of the invention integrable

Circuit;

2 shows a schematic circuit diagram of a further circuit which can be integrated into the exemplary embodiment of the invention; and

Fig. 3 is a schematic circuit diagram of the exemplary embodiment of the invention

Facility.

1 shows the schematic circuit diagram of a circuit 1. The circuit 1 can be part of an exemplary embodiment of the invention shown in FIG. 3

Be a facility. Since the mode of operation of the exemplary embodiment shown in FIG. 3 results from the mode of operation of circuit 1, it is necessary to first explain circuit 1.

Circuit 1 is integrated in a mobile radio device. Pilot signals received by the mobile radio device are demodulated in a RAKE receiver and converted into pilot symbols 100. The pilot symbols 100 enter the circuit 1 at a data rate of, for example, 15 ks / s. In the present case it is assumed that the base station from which the pilot symbols 100 were originally transmitted is in the STTD Operating mode is operated. In the STTD operating mode, the base station transmits its signals using two antennas 1 and 2. The pilot symbols 100 are divided into two data paths in the circuit 1, the pilot symbols 101 belonging to the antenna 1 being processed in one data path and the pilot symbols 102 belonging to the antenna 2 being processed in the other data path.

The data paths fed by the pilot symbols 101 and 102 are shown one above the other in FIG. 1. The upper data path relates to the antenna 2 of the base station. A sign unit 3 and an accumulator 4 are connected in series in this data path. The sign unit 3 has a control input which is connected to the output of an STTD coding unit 2. The STTD coding unit 2 is controlled by a control signal 200. The output of the accumulator 4 is connected both to an input of a multiplier 10 and to the input of a delay element 6. The delay element 6 is controlled by a control signal 201. The delay element 6 is followed by a conjugation unit 8. The output of the conjugation unit 8 is present at a further input of the multiplier 10. After the multiplier 10, an accumulator 12 and a grouping unit 14 are arranged in series in the order given. The accumulator 12 is controlled by a control signal 202, and the grouping unit 14 is controlled by a control signal 203. Furthermore, further data 103 are fed into the grouping unit 14. The data 103 can be the intermediate results of an integration of terms within a group. This is explained further below in connection with the description of FIG. 3. The output of the grouping unit 14 feeds an input of an adder 16.

The data path belonging to the antenna 1 is similar to the data path belonging to the antenna 2 built up. For this purpose, this data path has an accumulator 5, a delay element 7, a conjugation unit 9, a multiplier 11, an accumulator 13 and a grouping unit 15. The output of the grouping unit 15 is connected to a further input of the adder 16. In contrast to the data path fed by the pilot symbols 102, the data path fed by the pilot symbols 101 has no sign unit and no STTD coding unit.

The delay element 7, like the delay element 6, is controlled by the control signal 201. Furthermore, the accumulator 13 is controlled by the control signal 202 and the grouping unit 15 by the control signal 203. The grouping unit 15 also includes data 104, which, like the data 103, can be the intermediate results of an integration of terms within a group.

The adder 16 is an averaging unit 17 and

Computing unit 18 and a multiplier 19 connected downstream. The averaging unit 17 is controlled by a control signal 204. In addition to the output value of the calculation unit 18, the multiplier 19 is fed by a value 205. The multiplier 19 generates an output value 105.

In FIG. 1, as in FIG. 2 ^* described below, the data paths on which complex-value data are transmitted are represented by arrows with an additional vertical bar in front of the arrow head. Data and signal paths on which purely real data or signals are transmitted are shown by arrows without vertical bars. The control signals are indicated in FIGS. 1 and 2 by dashed arrows. In the STTD operating mode, the antenna 1 of the base station transmits the pilot symbol A = 1 + j 10 times in each time slot, with j denoting the imaginary unit. Antenna 2 of the base station also sends 10 pilot symbols per time slot, although in addition to pilot symbol A, pilot symbol -A = -1-j can also be transmitted. The pilot symbols transmitted by the antenna 2 per frame can be subdivided into units with four pilot symbols each, each unit having the pattern A, - A, -A, A formed from the four pilot symbols. There is only an irregularity in this pattern at the border of the frame.

After receiving the pilot signals in the mobile radio device, two successive pilot symbols of each antenna are folded. The folding of the pilot symbols transmitted by the antenna 1 is carried out in the accumulator 5. There, two successive pilot symbols are added up. The sum is then forwarded to delay element 7 and multiplier 11. This procedure means that a convolution value is output by the accumulator 5 only in every second processing cycle and the data rate after the accumulator 5 is thus reduced from 15 ks / s to 7.5 ks / s.

When the pilot symbols emitted by the antenna 2 are folded, two successive pilot symbols are also added up. It should be noted, however, that some of these pilot symbols have a negative sign. In order to avoid that the convolution leads to an incorrect result, such as 0 or -2A, the sign of each pilot symbol -A must be inverted before the convolution. This is accomplished by means of the sign unit 3. The sign unit 3 receives the information about which pilot symbol is to be inverted from the STTD coding unit 2, in which the pattern of the pilot symbols transmitted by the antenna 2 of the base station is filed. Furthermore, the STTD coding unit 2 requires information about the start of the frame in order to control the sign unit 3. This information is made available to the STTD coding unit 2 by the control signal 200. After removing the negative signs from the pilot symbols transmitted by the antenna 2, two successive pilot symbols are added in the accumulator 4 in the same way as in the accumulator 5. This convolution always gives the value 2A. After the accumulator 5, the data rate is also reduced to 7.5 ks / s.

A complex product according to equation (6) is formed from the convolution values generated by the accumulator 4 or 5 with the aid of the delay element 6 or 7, the conjugation unit 8 or 9 and the multiplier 10 or 11, wherein in equation (6) the values r _k -D and r _{k are} replaced by convolution values. For this purpose, a convolution value located in the delay element 6 or 7 is only output again when the accumulator 4 or 5 has generated the D-th subsequent convolution value. The size of the parameter D is supplied to the delay elements 6 and 7 by the control signal 201. The convolution value output by the delay element 6 or 7 is complex conjugated by means of the conjugation unit 8 or 9. The sign of the

Imaginary part of the convolution value inverted. In the subsequent multiplication in the multiplier 10 or 11, the convolution value output by the accumulator 4 or 5 in the respective processing cycle is multiplied by the time-delayed and conjugate convolution value simultaneously output by the conjugation unit 8 or 9. A predetermined number of complex products is then added up in the accumulator 12 or 13. The number of successive complex products, which are accumulated by the accumulators 12 and 13, is determined by the control signal 202 specified. In the present case, the summation extends over four complex products.

The sum of complex products generated by the accumulator 12 or 13 is fed to the grouping unit 14 or 15. Furthermore, the grouping unit 14 or 15 receives the data 103 or 104, which it sums up as intermediate results of an integration within a group with the data made available by the accumulator 12 or 13.

The convolution values output by the accumulator 4 or 5 are given below with P? designated. The index is j

(j = 1, 2) for the antenna from which the associated pilot symbols were transmitted and the integer index i indicates the chronological order of the convolution values. After passing through the grouping unit 14 or 15, the following value results:

In the present case, the accumulator 12 or 13 sums over four products output by the multiplier 10 or 11

^P io _m ^'p _m i • ^D i ^ese accumulation is controlled by the control signal 202nd The grouping unit 14 or 15 sums up the sums output by the accumulator 12 or 13 according to the control signal 203 with the data 103 or 104. This is characterized in the term (9) by the summation index m. It is explained further below that the summation index m identifies the summation results of the accumulator 12 or 13, which are to be combined to form a specific group result. For example, the index m can be used to denote all propagation paths within a cell, via which the results of the accumulator 12 or 13 are to be summed up. M in this example denotes the number of propagation paths within this cell.

All processing steps before the calculation of terms (9) take place in circuit 1 by means of a hardware circuit. Only the outputs of the grouping units 14 and 15 feed firmware, in which the further calculations for determining the frequency deviation are carried out by means of a digital signal processor 39. The in Fig. 1 in the

Units and circuit elements arranged in the digital signal processor 39 are therefore to be understood as calculation rules of an algorithm which is processed in the digital signal processor 39.

The terms output by the grouping units 14 and 15 are added by means of the digital signal processor 39. An average is then formed over a certain period of the average. These two steps are identified in FIG. 1 by the adder 16 and the averaging unit 17. The averaging period is fed to the averaging unit 17 by the control signal 204. As a result of the averaging, the data rate after the averaging unit 17 drops to a value of 7.5 / mean duration ks / s.

The phase difference Δφ is calculated from the mean value in accordance with equation (3) by inserting the mean value for the complex product U _k into the right-hand side of equation (3). For this calculation step stands in

Circuit 1, the calculation unit 18 is available.

According to equation (1), the phase difference Δφ must be multiplied by the factor 1 / (2πT _s ). It should be noted that this is due to the folding of two

Pilot symbols in the accumulators 4 and 5 the time T _s must be doubled. The parameter D be taken into account. A factor of 1 / (4πT _s D) results from these considerations, the factor l / T _{s representing} the pilot symbol rate at which the pilot symbols are transmitted by the base station. In the UMTS standard, this pilot symbol rate is 15 kHz. The multiplication by the factor 1 / (4πT _s D) is carried out in FIG. 1 by means of the multiplier 19, to which the factor 1 / (4πT _s D) is supplied by the value 205. This multiplication gives the frequency deviation Δf as the output value 105.

FIG. 2 shows the schematic circuit diagram of a circuit 20 which, like circuit 1, can be integrated in the exemplary embodiment of the invention shown in FIG. 3.

In contrast to the circuit 1 shown in FIG. 1, the circuit 20 is designed to process pilot symbols which have been received by a base station operated in the normal operating mode. In normal operating mode, a base station only sends signals via an antenna.

Circuit 20 emerges from circuit 1 when the upper data path of circuit 1, in which the pilot symbols 102 belonging to antenna 2 are processed, is omitted. Furthermore, in comparison to circuit 1, the accumulator 5, which could be bridged in circuit 1 to generate circuit 20, and the adder 16, whose function in the processing algorithm of digital signal processor 39 would have to be deleted, are eliminated in circuit 20.

The resulting circuit 20 is shown in FIG. 2. Similar or identical circuit elements, signals or calculation rules as in FIG. 1 have the same reference symbols in FIG. 2. It should be noted that in the accumulator 13 of the circuit 20, 8 complex products U _{k are} summed. This results in analogy to term (9) Term (10), which is output by the grouping unit 15:

In the term (10), the integer index k, which is specified by the control signal 202, indicates the chronological order of the pilot symbols r.

It should also be noted in the circuit 20 that the value 205 by which the phase difference Δφ is multiplied is 1 / (2πT _s D).

In circuit 20, the data rate up to the averaging in the averaging unit 17 has a value of 15 ks / s. After the averaging unit 17, the data rate is 15 / mean duration ks / s.

3 shows a circuit 30 for determining the deviation of the carrier frequency of a mobile radio device as an exemplary embodiment of the device according to the invention. The circuits 1 and 20 shown in FIGS. 1 and 2 can be integrated into the circuit 30.

Circuit 30, like circuits 1 and 20, is supplied with pilot symbols 100 which have been demodulated by the RAKE receiver of the mobile radio device. The pilot symbols 100 first reach an intermediate memory 31, which serves to decouple the RAKE structure from the downstream components of the circuit 30.

The pilot symbols 100 then pass through a decoupling unit 32 which, in the STTD operating mode, performs the task of separating the pilot symbols 100 according to the respective antenna. The circuit 1 shown in FIG. 1 relates to the STTD operating mode. The Decoupling unit 32 is also shown in FIG. 1. It includes the STTD coding unit 2, the sign unit 3 and the accumulators 4 and 5. The antenna decoupling is accomplished in the decoupling unit 32 as described above by folding two successive pilot symbols. For this purpose, the pilot symbol that is received first is first temporarily stored in a buffer 33 downstream of the decoupling unit 32. As soon as the second pilot symbol arrives in the decoupling unit 32, the pilot symbol temporarily stored in the buffer is loaded again into the decoupling unit 32 so that the folding of the two pilot symbols can be carried out there. The convolution value obtained in this way can then be stored in the intermediate store 33.

If the base station from which the pilot symbols 100 were transmitted is operated in the normal operating mode, the pilot symbols 100 are written directly into the buffer store 33. This is the operating mode of the base station for which the circuit 20 shown in FIG. 2 is designed.

The convolution values or pilot symbols temporarily stored in the intermediate memory 33 are read out in a hard-wired calculation unit 34 for their further processing. The circuit elements belonging to the calculation unit 34 are shown in FIGS. 1 and 2 for both operating modes of the base station. The calculation unit 34 contains the conjugation units 8 and 9, the multipliers 10 and 11, the accumulators 12 and 13 and the grouping units 14 and 15. To reduce the circuit complexity, the calculation unit 34 can result from a circuit part of a circuit which is suitable for SINR (Signal to Interference and Noise Ratio) calculations are used. It should be noted that the delay elements 6 and 7 in the circuit 30 are implemented by the buffer 33. Those convolution values or pilot symbols which are to be supplied to the multiplier 10 or 11 without delay are passed on from the decoupling unit 32 directly to the calculation unit 34. Those convolution values or pilot symbols which are to be delayed by means of the delay element 6 or 7 are temporarily stored in the intermediate memory 33 and are only forwarded to the calculation unit 34 at a later point in time.

The calculation unit 34 carries out the integration according to equation (10) or (9). Intermediate values of the summation are connected downstream of the calculation unit 34

Buffer 35 cached. As soon as a further pilot symbol or convolution result (summation index k or i in equation (10) or (9)) or a contribution to the accumulation of a group result (summation index m in equations (9) and (10)) is available, the temporary summation results are loaded from the buffer 35 into the calculation unit 34 as data 103 or 104 and the summation is supplemented or completed in accordance with equation (10) or (9).

The method described above is particularly suitable for the case in which the pilot symbols 100 are successively supplied by time-multiplexed RAKE fingers and the pilot symbols 100 have been forced to belong to a group due to the assignment of the RAKE fingers to specific propagation paths within specific cells. This is expressed in equations (9) and (10) by the index m. In addition, the pilot symbols 100 are transmitted in a time sequence according to a defined transmission sequence in the time slot or frame raster and demodulated by the RAKE fingers in time division multiplex. Doing so will 256 chips of demodulated pilot symbols 100 each supplied by the time-multiplexed RAKE fingers.

The aim of returning the data 103 and / or 104 to the calculation unit 34 is to combine the complex terms output by the accumulators 12 and 13 in groups in a flexible manner. The complex terms that are to be combined in a specific group can, for example, belong to a specific path on which the signals are transmitted from a specific base station to the mobile radio device. Furthermore, it can be provided that the complex terms belonging to several transmission paths of a specific base station are added up in a group. Another grouping option is characterized in that the complex terms of the signal-strongest paths of one or more base stations are integrated in a group. The user specifies which groups will ultimately be formed.

To calculate a group result, the grouping units 14 and 15 are provided with the intermediate results, which contain the complex terms of this group that have been added up so far, by means of the data 103 and 104, respectively. After a further complex term generated by the accumulator 12 or 13 has been added to the previous total in the grouping unit 14 or 15, the new intermediate result is again stored in the buffer 35. As soon as a new complex term belonging to this group has been calculated in the accumulator 12 or 13, this becomes

Intermediate result loaded again into the grouping unit 14 or 15. In the terms (9) and (10) the combination of the complex terms (r ^* _{/ k} _ _D • r _{m / k} ) becomes

Groups considered by the index m. After the group-wise integration has ended, the results of a group are fed to a digital signal processor 39, which carries out the further calculations for determining the frequency deviation Δf. 1 and 2, the computing steps to be carried out by the digital signal processor 39 are represented by the adder 16, the averaging unit 17, the calculation unit 18 and the multiplier 19. It is also conceivable that individual processing steps assigned to the digital signal processor 39 in the present exemplary embodiment are carried out in hardware.

As a rule, it is provided that the frequency deviation Δf is calculated for at least two different parameters D. For example, values 1 and 4 can be selected for parameter D.

In addition to its task of calculating the frequency deviation Δf, the digital signal processor 39 also performs control tasks for forming the groups. The digital signal processor 39 determines, for example, which groups are formed and feeds the corresponding specifications to a control unit 37. The control unit 37 controls an address generation unit 38. The address generation unit 38 specifies the addresses of the intermediate memory 35, in which those of the

Calculation unit 34 generated intermediate results of the individual groups are stored. As a result, the address generation unit 38 can select the intermediate results, which are stored as data 103 or 104 in the

Grouping unit 14 or 15 should be loaded.

Furthermore, a control unit 36 is provided in the circuit 30. The control unit 36 receives control signals 206 from the RAKE receiver. The control signals 206 contain information about which RAKE finger the pilot symbols 100 coming into the circuit 30 belong to. The means that the control unit 36 receives information about the associated base station, the operating mode of the base station and the transmission path of the pilot symbols 100 by means of the control signals 206 and the configuration data in the control unit 37.

If the information about the affiliation of a received pilot symbol 100 to a specific RAKE finger is communicated by means of the control signal 206, the configuration data in the control unit 37 can be used to determine which transmission path within which cell the relevant RAKE finger is receiving. The transmission mode can also be identified on the basis of the determined base station. As further information, this RAKE finger is assigned to a specific group via which the results are accumulated.

Furthermore, control signals are exchanged bidirectionally between the control units 36 and 37. The control signals 206 generated by the RAKE receiver are also supplied to the control unit 37.

The control unit 36 controls the buffer 33 with the control signal 201 and the calculation unit 34 with the control signals 202 and 203 on the basis of the information available to it. Furthermore, the control unit 36 informs the calculation unit 34 of the operating mode in which the base station belonging to the pilot symbols 100 is operated. Accordingly, the calculation unit 34 can be configured according to circuit 1 or circuit 20.

Claims

claims 1. Device (30) for determining the deviation (105) of the carrier frequency of a mobile radio device from the carrier frequency of at least one base station, a sequence of complex pilot symbols known in the mobile radio device being transmitted by radio from each base station to - a first unit (6, 8, 10; 7, 9, 11) for calculating terms, wherein a term is formed from at least two different pilot symbols of the sequence received by the mobile radio device and the phase difference between the two pilot symbols can be determined from the term , - a second unit (14; 15) for forming groups from the terms, a term being assigned to a group on the basis of features of the pilot symbols on which it is based, and - A third unit (39) for calculating the frequency deviation (105) based on the terms of at least one group. 2. Device (30) according to claim 1, characterized in that - the first unit (6, 8, 10; 7, 9, 11) and the second unit (14; 15) are in the form of a hard-wired circuit (33, 34) , 3. Device (30) according to claim 1 or 2, d a d u r c h g e k e n n z e i c h n e t, - That the third unit is in the form of a digital signal processor (39). 4. Device (30) according to one or more of the preceding claims, characterized in that - That the first unit (6, 8, 10; 7, 9, 11) is designed for the calculation of complex products, a complex product being formed from at least two different pilot symbols of the sequence received by the mobile radio device and the argument of the complex product being Indicates phase difference between the two pilot symbols. 5. Device (30) according to one or more of claims 2 to 4, d a d u r c h g e k e n n z e i c h n e t, - that the first unit has a multiplier (10; 11) with a first input and a second input, - That a circuit branch is arranged in front of the first input, which contains a delay element (6; 7) and a unit (8; 9) for forming the conjugate complex value from a complex value, and - That the circuit branch are fed by one pilot symbol and the second input by the other pilot symbol. 6. Device (30) according to claim 5, d a d u r c h g e k e n n z e i c h n e t, - That the delay time of the delay element (6; 7) is adjustable and can be predetermined. 7. Device (30) according to claim 5 or 6, d a d u r c h g e k e n n z e i c h n e t, - That the delay element (6; 7) is realized by a rewritable memory (33). 8. Device (30) according to one or more of the preceding claims, d a d u r c h g e k e n n z e i c h n e t, - That between the first unit (6, 8, 10; 7, 9, 11) and the second unit (14; 15) an accumulator (12; 13) is arranged for adding up an adjustable number of terms. 9. Device (30) according to one or more of the preceding claims, that the second unit (14; 15) is designed in such a way that the terms or, if appropriate, the accumulated terms of a group are added up. 10. Device (30) according to one or more of the preceding claims, g e k e n n z e i c h n e t d u r c h - A rewritable memory (35) in which the terms of the groups or, if applicable, the accumulated terms of the groups can be stored. 11. Device (30) according to one or more of the preceding claims, d a d u r c h g e k e n n z e i c h n e t, - That the first unit (6, 8, 10; 7, 9, 11) and the second unit (14; 15) and optionally the accumulator (12; 13) exist twice. 12. Device (30) according to claim 11, characterized in that - the first two units (6, 8, 10; 7, 9, 11) have a fourth unit (32) for separating the received pilot symbols according to the associated antennas which emit the pilot symbols Base station is upstream. 13. Device (30) according to one or more of the preceding claims, d a d u r c h g e k e n n z e i c h n e t, - That the first unit (6, 8, 10; 7, 9, 11) or optionally the fourth unit (32) is preceded by a rewritable memory (31). 14. Device (30) according to one or more of the preceding claims, d a d u r c h g e k e n n z e i c h n e t, - That the third unit (39) is designed for averaging terms or groups of terms. 15. Device (30) according to one or more of the preceding claims, g e k e n n z e i c h n e t d u r c h - a control unit (36, 37, 38, 39) for forming Groups and especially to control the accumulation of terms in the given groups. 16. Device (30) according to one or more of the preceding claims, d a d u r c h g e k e n n z e i c h n e t, - That the groups are formed on the basis of the affiliation of the pilot symbols on which the terms are based to base stations and / or transmission paths. 17. A method for determining the deviation (105) of the carrier frequency of a mobile radio device from the carrier frequency of at least one base station, a sequence of complex pilot symbols known in the mobile radio device being transmitted by radio from each base station, comprising the steps: (a) Calculating terms, wherein a term consists of at least two different pilot symbols that of the Mobile radio device received sequence is formed and the phase difference between the at least two pilot symbols can be determined from the term, (b) forming groups from the terms, a term being assigned to a group on the basis of features of the pilot symbols on which it is based, and (c) calculating the frequency deviation (105) on the basis of the terms of at least one group. 18. The method according to claim 17, d a d u r c h g e k e n n z e i c h n e t, - that in step (a) complex products are calculated, a complex product being formed from at least two different pilot symbols of the sequence received by the mobile radio device and the argument of the complex product indicating the phase difference between the at least two pilot symbols. 19. The method according to claim 17 or 18, d a d u r c h g e k e n n z e i c h n e t, - that in step (b) the terms of a group are added up. 20. The method according to one or more of claims 17 to 19, d a d u r c h g e k e n n z e i c h n e t, - That the groups are formed on the basis of the affiliation of the pilot symbols on which the terms are based to base stations and / or transmission paths. 21. The method according to one or more of claims 17 to 20, d a d u r c h g e k e n n z e i c h n e t, - that the two pilot symbols of the terms from which a group is formed are separated by a predetermined number of positions in the sequence of the pilot symbols. 22. The method according to claim 21, d a d u r c h g e k e n n z e i c h n e t, that a group is formed twice, the two groups differing in the number of places by which the pilot symbols on which their terms are based are located apart.