WO2009106129A1

WO2009106129A1 - Method and device for determining a signal quality and system comprising said device

Info

Publication number: WO2009106129A1
Application number: PCT/EP2008/052291
Authority: WO
Inventors: Jaroslaw Kussyk
Original assignee: Siemens Aktiengesellschaft
Priority date: 2008-02-26
Filing date: 2008-02-26
Publication date: 2009-09-03

Abstract

The invention relates to a method and a device for determining a signal quality, wherein the input signal (r(t)) is split up in a plurality of sub-elements (rk1, rk2); a response value determination is carried out for some of the sub-elements; a correlation is carried out using the response value determinations; a measure for the signal quality (Q_k) is determined using said correlations. The invention further relates to a system comprising said device.

Description

description

Method and device for determining a signal quality and system comprising such a device

The invention relates to a method and a device for determining a signal quality, in particular a measure of a signal quality. Furthermore, a system comprising such a device is specified.

In communication devices, time and / or frequency diversity is often introduced to increase information transfer security. In this case, various spread spectrum techniques are used and / or the modulated signals are divided into individual subelements and transmitted at different times.

Are used in such communication systems and / or

Communication Networks Using routing algorithms which rely on the data transmission characteristics of individual sub-transmission links, it is often necessary or advantageous to determine a transmission quality upon receipt of the data.

However, an expense for the separate examination of individual partial transmission links results in a significant reduction of the data throughput in the communication system.

Thus, a received signal level and a noise or interference level are estimated for each partial transmission path of the communication network in a receiver, and the transmission quality of the partial transmission path is thereby determined. If the data transmission takes place in a channel with additive white Gaussian noise, then a signal-to-noise ratio (SNR) or a comparable size can be determined and based on this, an expected bit error probability can be determined. Among other things, this can be

Bit error probability can be used to evaluate the channel.

In transmission channels with interference, which represent no white Gaussian noise and moreover, if necessary, have strong time and / or frequency-selective properties, however, an expected bit error probability based on the signal-to-noise ratio can no longer be reliably determined.

The object of the invention is to avoid the above-mentioned disadvantages and in particular to provide an approach by which a characterization of the reception quality is made possible for severely disturbed transmission channels.

This object is achieved according to the features of the independent claims. Further developments of the invention will become apparent from the dependent claims.

To achieve the object, a method for determining a signal quality of an input signal is proposed

- In which the input signal is decomposed into several sub-elements;

in which a target size determination is carried out for a part of the subelements;

- in which an assignment is carried out on the basis of the target size determinations; - in which a measure of the signal quality is determined on the basis of the assignments. In this case, it is advantageous to specify a measure of the quality of a received input signal that can be used for a large number of different transmission channels with different interference. Thus, it is possible to detect when detecting a signal on the basis of this measure of the signal quality, how sure a corresponding signal could be detected. A meaningful measure of the signal quality is important, for example, in safety-relevant applications in which a high probability of a correctly received signal is to be assumed.

Due to the decomposition into subelements, a corresponding assignment can be made separately for a large number of individual parts of the input signal and these

Associations can then be included in the measure of signal quality.

The input signal can be any type of signal for which a signal quality, in particular a measure of the signal quality, is to be determined.

A development is that the assignment comprises a partial bit decision and / or a partial symbol decision.

Another development is that the target size determination based on a demodulation with a predetermined carrier signal, in particular with a predetermined carrier frequency, is performed.

In particular, the input signal may be a spread spectrum signal. The corresponding carrier frequencies are preferably stored or known at the receiver, so that a corresponding demodulation can take place. In particular, it is a development that the target size determination is performed for all subelements.

It is also a development that a combination signal is determined on the basis of the target size determinations. Preferably, the combination signal may additionally be determined based on or depending on the measure of signal quality.

In particular, an output signal can be determined based on the combination signal by means of a bit and / or symbol decision. In the context of a development, the output signal is additionally determined depending on the measure of the signal quality.

It is also an embodiment that an output signal as a whole is demodulated, in particular based on a useful signal receiver.

Furthermore, it is a training that based on the

Assignments the measure of the signal quality is determined at least partially taking into account the output signal.

In the context of an additional development, a statistic or a parameter for a plurality of subelements, in particular for a plurality of input signals, is determined on the basis of the measure for the signal quality.

A next development is that a bit and / or a symbol comprises a plurality of sub-elements.

Another embodiment is that the subelement comprises at least one bit, at least one symbol, at least one byte or at least one telegram. One embodiment is that the assignment comprises a hard decision.

An alternative embodiment is that the association comprises a soft decision, taking into account in particular further decisions (e.g., a temporal context).

Furthermore, to solve the above object, a device is provided for determining a

Signal quality comprising a processor unit, which is arranged such that the method as described herein on the processor unit is feasible.

In addition, to achieve the above object, a device is provided for determining a signal quality comprising a processor unit and / or an at least partially hardwired or logical circuit arrangement, which is set up in such a way that the method can be carried out as described herein.

Said processor unit can be or comprise any type of processor or computer or computer with correspondingly necessary peripherals (memory, input / output interfaces, input / output devices, etc.). Such a processor unit can in particular in one

Communication device may be provided, which in particular has a transmitter, receiver (receiver) or a transceiver.

Furthermore, a hardwired or logic circuit unit, for example an FPGA or an ASIC or another integrated circuit can be provided. In particular, electronic, electromagnetic, acoustic or other elements may be provided to detect and / or process different signals. In particular, the device may thus comprise a unit for parallel processing of signals and / or a unit for serial processing of signals.

The device may comprise or be embodied as: a measuring device, a diagnostic device, a counter, an information acquisition device, a control device, a direction finder and / or a corresponding system.

The device can be used in power engineering.

It is possible that the signal comprises different physical quantities:

an electrical variable,

an electromechanical size,

an electromagnetic variable,

an acoustic quantity, a thermal size,

a mechanical (in particular a hydraulic or pneumatic) size,

a chemical quantity,

- an optical size.

Combinations of the aforementioned sizes are possible as a signal (e).

It is a further development that the device is a communication device, wherein the communication device exchanges signals with another communication device via a communication link which at least partially comprises a power network.

Furthermore, to solve the problem, a system is provided comprising a device as described herein. Embodiments of the invention are illustrated and explained below with reference to the drawings.

Show it:

Fig.l a symbol sketch for determining a

Signal quality measure Qk based on an input signal r (t);

A block diagram for determining a

Data reception quality Q based on individual reception quality measures Q _k .

In the approach proposed here, payload data are preferably transmitted by means of a carrier signal w (t) which comprises a plurality of subelements W (Ii ₁ , -I ₁ ), wherein the subelements can be transmitted to one another in different frequency channels and at different times. The subelements preferably have a dependence on one another known to the receiver.

Advantageously, the subelements can also have the same information (relationship known to the receiver) for a period T _{D of} a useful data symbol and / or a useful data bit D _k . The individual modulated subelements Sk (tχ, f _D ) can be combined correspondingly to the transmission signal s (t).

In particular, an example of the approach presented here for determining a measure of a signal quality, in particular for a signal quality of data that a receiver receives via a communication channel, will be described below.

A receiver receives a signal r (t), also referred to as a received signal, which represents a mixture or an overlay of a transmitted useful signal s (t) and a noise signal and / or noise n (t). r (t) = s (t) + n (t)

The signal r (t) preferably comprises a plurality of payload data symbols and / or payload data bits D _k , each of which preferably has at least one subelement r _k (t!, F _D ).

The subelements r _k (t!, F _D ) are first individually demodulated taking into account the known carrier signal structure (the above-mentioned dependencies of individual subelements w (ti, f _D ) to one another).

Based on an intermediate _value I _k13 at the output of the demodulator, a decision D _klJ about the transmitted user data _symbol and / or user data _bit D _{k is} preferably made individually for each of the received subelements r _k (t!, F _D ).

The intermediate _values I _k13 , which are associated with a useful data _symbol and / or a useful data _bit D _k , are combined, for example, by summation to a value I _k .

Preferably, based on the combined value I _k , the entire received payload symbol and / or payload data bit D _{k is} decided, possibly with consideration of one

Reception quality _measure Q _k (see in particular subsequent comments).

From the subelements D _kl3 the received quality _measure Q _k can be determined as follows:

2

Qk = ^{1 ~} TN _τ -ΣN ^D ktj: D,

in which

Σ _Λ - D _kυ an arithmetic sum of all N 0 and 1 subelements D _k i _{j of} the received data bit D _k in a binary modulation.

In a soft bit decision, the subelements D _k i _{j can} also have values between 0 and 1.

In a high-order modulation, the received subelements D _{kij of} a useful data _symbol D _{k are} in their binary

Representation of M bits (D _ki j _P with p = 0, ..., MI) considered.

The reception quality _measure Q _k can be expressed as an average of the

Receiving _{quality measures} Q _kp each equivalent bits D _kijp of D ^ _{j are determined} as follows:

n - - 1 _* v-> MM "^" - ^" 1I ¹ nr \ - - v ΛM ^jW - ^" 1 = 0 ^{1 ~} T7 Σ -V ^D h> j _P (2),

N

in which

an arithmetic sum of N respectively equivalent bits D _k i _{jp of} the subelements D _k i _{j of} the received data symbol D _k in a more significant modulation.

In a soft bit decision, the equivalent bits D _k i _{jp may} also have values between 0 and 1.

As an alternative to equation (1), a Empfangsqualitätsmaß Q _'k be formed as follows for binary modulation:

in which Z- ^ ND _klJ - D _k

denotes an arithmetic sum of the absolute values of N differences between the received data bit D _k and its 0 and / or 1 subelements D _kij .

In a soft bit decision, the subelements D _kij and / or the data bits D _{k can} also have values between 0 and 1.

Accordingly, as an alternative to the equation (2), for higher-order modulations, a reception quality measure Q ' _k can be determined as follows:

M Dki ir, ^~ D ^' A, -P' A)

in which

ΣΛΓ Dkijp - D _{k [l}

an arithmetic sum of the absolute values of N differences between the pth bit D _{kp of} the received data symbol D _k and the respective equivalent bits D _{kijp of} its subelements D _k i _j .

In a soft bit decision, the equivalent bits D _kijp and / or the data bits D _{kp may} also have values between 0 and 1.

Based on the described reception _quality Q _k and / or Q ' _{k of} individual received user data _symbols and / or useful data bits D _kij , a Q statistic or different Q characteristics (eg a minimum value, an average value or a median value) can be determined and Characterization of the reception quality of entire data blocks are used.

Fig.l shows a symbol sketch for determining a signal quality measure Qk based on an input signal r (t).

Preferably, such a functional arrangement is provided in a receiver, wherein the input signal r (t) has been received via a more or less disturbed channel.

The approach presented here makes it possible to determine the signal quality even in cases where the channel does not have only Gaussian interference.

The input signal r (t) is supplied to a signal processor 101. This may, for example, be a FIR filter. Portions of the input signal r (t) are subdivided into subelements r _ki and r _k2 and each of these

Subelements r _ki and r _{k2 are} supplied to a processing unit 104a and 104b, respectively. The processing units 104a and 104b preferably each have means for determining the target size and a hard or soft decision unit (allocation unit).

The results of the processing units 104a and 104b are sent to a unit 103 for determining the

Signal quality measure Q _k supplied.

Furthermore, the subelements r _ki and r _k2 decomposed by the signal processing 101 also become one

User signal receiver 102 is supplied and there in a

Output signal D _k transferred. In particular, for this purpose, the useful signal receiver 102 has a bit and / or

Symbolic decision on. The payload receiver 102 preferably receives the signal as a whole and demodulates the completely received signal.

Advantageously, the measure of the determined signal quality Qk can be used to influence the output signal D _k . This will also be shown below with reference to FIG.

2 shows a block diagram for determining a data reception quality Q based on individual reception quality measures Q _k .

A serial input signal r (t) is fed to a unit 201 where it is converted into a parallel signal and split into a plurality of subelements r _k .

Each subelement r _k is supplied to a unit for determining target 202a to 202d. In each case, the unit for determining the target size is a demodulator in which a demodulation takes place on the basis of a known carrier signal w associated with the respective subelement.

Thus, a subelement r _k (ti, fi) of the unit becomes

Target size determination 202a supplied to the basis of the carrier signal w (ti, fi) determines a signal I _k i, which is an allocation unit 204a and a combination unit 203 is supplied. The assignment unit 204a performs, based on the signal ϊ _k i a bit and / or symbol decision and forwards a corresponding signal generated

to a unit 205 for determining a signal quality measure Q _k on.

A subelement r _k (t2, f2) becomes the unit for

Target size determination 202b supplied, which determines based on the carrier signal w (t2, f2) a signal I _k 2, the one Assignment unit 204b and the combination unit 203 is supplied. The allocation unit 204b performs a bit and / or symbol decision based on the signal ϊ _k 2 and forwards a corresponding generated signal Z) ^ ₂ to the unit 205.

A subelement r _k (t!, F _D ) is supplied to the target size determination unit 202c, which determines, based on the carrier signal w (t!, F _D ), a signal I _k i _D which is fed to an allocation unit 204c and the combination unit 203. The allocation unit 204c performs a bit and / or symbol decision based on the signal ϊ _k i _D and forwards a corresponding generated signal D _klJ to the unit 205.

Correspondingly, a subelement r _k (t _L , fB) is supplied to the target size determination unit 202d which, based on the carrier signal w (t _L , fB), determines a signal I _kN supplied to an allocation unit 204d and the combination unit 203. The allocation unit 204d performs a bit and / or symbol decision based on the signal I _kN and forwards a corresponding generated signal D ^ _N to the unit 205.

The combination unit 203 generates based on the

Signals ϊ _k i, I _k2 , ..., IkI ₁₁ , ■■■, IkN a combination signal I _k . This can be done for example by a summation, possibly by a weighted summation of the individual signals.

Optionally, the unit 205 for determining the signal quality measure based on at least one signal quality measure, the combination unit 203 influence such that it disregards those signals I _k , which differ by more than a predetermined amount of the other signals. Optionally, such a selection may also be made by the combination unit 203 without the at least one provided signal quality measure. The combination signal I _k is converted by means of a decision unit 207 into an output signal D _{f :} . This output signal D _k can also be taken into account in the unit 205 for determining the signal quality measure.

The decision unit 207 may have a bit and / or symbol decision comparable to the allocation units 204a to 204d. In particular, the

Decision unit 207 include a two-stage decision, which is divided, for example, in a first hard and a second soft decision.

The signal quality measurement unit 205 determines, based on the results of the individual allocation units 204a to 204d, a signal quality Qk which can optionally be made available to the combination unit 203 and / or the decision unit 207 for further processing.

It is also possible for the signal quality Q _k to be supplied to a unit 206 for determining a statistic and / or a characteristic Q for a plurality of subelements and / or for a plurality of input signals.

For example, in the unit 206 on the basis of the individual measures for the signal quality Q _k, an average value Q can be determined which indicates the average quality in the reception. Instead of the mean value or additionally, other measures or statistics, eg a scatter, can be determined.

In the allocation units 204a to 204d or in the decision unit 207, respectively a "hard" or a "soft" decision can be made (hard decision or soft decision). Here, a variety of different methods for determining a hard decision or a soft decision can be used. In particular, threshold comparisons or stochastic decisions are possible which, for example, take into account a given context, eg a time duration of a given length.

Other advantages:

An advantage of the approach presented here is that the measure of the reception quality Q _k and / or Q ' _{k is} largely independent of the type of interference signal and / or the noise n (t).

Advantageously, the intensity of the interference signal n (t) is utilized by determining a measure of a dispersion or divergence between the a priori same information subelements D _j and D _k ijp.

Thus, the approach is applicable to different transmission channels with different interfering signals or combinations of different interfering signals.

Instead of the scattering or divergence discussed above, other moments and / or statistics may be used instead of the mean values presented in determining the reception quality Q _k and / or Q ' _k .

Although the measures of the reception qualities Q _k and Q ' _{k are} comparable, the measure of the reception quality Q _{k has} the advantage that it can be formed prior to the actual decision about the user data symbol and / or useful data bit D _k received as a whole and can influence this.

On the other hand, the measure of the reception quality Q ' _k allows showing a divergence of a bit decision result depending on a majority of decision results on individual information subelements of a bit and / or a symbol.

Claims

claims

A method of determining a signal quality of an input signal, wherein the input signal is decomposed into a plurality of subelements;

- in which an assignment is carried out on the basis of the target size determinations;

- In the basis of the assignments a measure of the signal quality (Q _k ) is determined.

2. The method of claim 1, wherein the association comprises a partial bit decision and / or a partial symbol decision.

3. The method according to any one of the preceding claims, wherein the target size determination is carried out based on a demodulation with a predetermined carrier signal.

4. The method according to any one of the preceding claims, wherein the target size determination is performed for all sub-elements.

5. The method according to any one of the preceding claims, wherein based on the target size determinations, a combination signal (Ik) is determined.

6. The method of claim 5, wherein the

Combination signal (I _k ) is additionally determined depending on the measure of the signal quality (Q _k ).

7. The method according to any one of claims 5 or 6, wherein the basis of the combination signal (I _k ) by means of a bit and / or symbol decision, an output signal (D _k ) is determined.

8. The method of claim 7, wherein the output signal

(D _k ) is additionally determined depending on the measure of the signal quality (Qk).

9. The method according to any one of claims 1 to 6, wherein an output signal (D _k ) is demodulated as a whole in particular based on a Nutzsignalempfängers.

10. The method according to any one of the preceding claims, wherein based on the assignments, the measure of the signal quality (Qk) is determined at least partially taking into account the output signal (D _k ).

11. The method according to any one of the preceding claims, wherein based on the measure of the signal quality (Q _k ) a statistic or a characteristic (Q) for a plurality of sub-elements, in particular for a plurality of input signals, is determined.

12. The method according to any one of the preceding claims, wherein a bit and / or a symbol comprises a plurality of sub-elements.

13. The method according to any one of claims 1 to 11, wherein the sub-element comprises at least one bit, at least one symbol, at least one byte or at least one telegram.

14. The method according to any one of the preceding claims, wherein the assignment comprises a hard decision.

15. The method according to any one of the preceding claims, wherein the assignment comprises a soft decision, in particular, further decisions are taken into account.

16. A device for determining a signal quality comprising a processor unit and / or an at least partially hardwired or logical circuit arrangement, which is set up such that the method according to one of the preceding claims is feasible.

17. The apparatus of claim 16, wherein the device is a communication device, wherein the

Communication device with another communication device signals via a

Communication link, which at least partially includes a power grid, exchanges.

18. System comprising a device according to one of claims 16 or 17.