DE102018206200A1 - Method for detecting a channel impulse response in a system, in particular for communication, system, transmitting device and receiving device - Google Patents

Abstract

The invention relates to a method for detecting a channel impulse response in a system operated in particular for communication in which at least one transmitter transmits at least one signal to at least one receiver wirelessly, in particular by radio, at the transmitter and receiver as discrete, in particular at least partially operated as an integrated circuit, elements are operated such that the transmitter transmits at least one signal, in particular a narrow pulse; f) a receiver receives the signal manipulated by the transmission channel, g) the manipulated signal is prepared such that it h) the manipulated prepared signal at the mixer is mixed with a reference signal such that a mixed signal is present which at least correlates with the channel impulse response. The invention further relates to a transmitting device and a receiving device each having means for carrying out of the procedure.

Description

The invention relates to a method for detecting a channel impulse response in a system, in particular for communication, according to the preamble of claim 1 and a transmitting device according to the preamble of claim 12 and receiving device according to the preamble of claim 14.

The channel impulse response is known from communications engineering as a variable describing the properties of a transmission channel. This can be regarded as mathematical models of the channel usually as ideal conditions, in particular ideal transmission channel, reproducing formula. Measuring the channel impulse response, ie the real transmission conditions, between a point A and one point B is however a technical problem.

In radio-based systems, it is known that the channel impulse response is mixed with the ideal transmission signal to include an image of reality in the system consideration. The channel impulse response distorts an electromagnetic signal as it propagates in space. It is strongly location-dependent and reflects the environmental influences.
With the help of the location information in the channel impulse response, this can be used for example in the field of radio location. It is therefore known to provide this function in integrated circuits, ICs. However, despite the evaluation of the location information, these ICs do not provide any measurement of the channel impulse response.
The problem underlying the invention is therefore to provide a solution that overcomes the disadvantages of the prior art.

This object is achieved by the method for detecting a channel impulse response in a, in particular for communication, system starting from the preamble of claim 1 by its characterizing features and a transmitting device according to the preamble of claim 12 by its characterizing features and the receiving device according to the preamble of the claim 14 solved by its characterizing features.

1. a) der Sender zumindest ein Signal, insbesondere einen schmalen Impuls, sendet,
2. b) ein Empfänger das durch den Übertragungskanal manipulierte Signal empfängt,
3. c) das manipulierte Signal derart vorbereitet wird, dass es einem Mischer zugeführt werden kann,
4. d) das manipulierte vorbereitete Signal am Mischer mit einem Referenzsignal derart gemischt wird, dass ein gemischtes Signal vorliegt, welches mit der Kanalimpulsantwort zumindest korreliert.

In the method according to the invention for detecting a channel impulse response in a system operated in particular for communication in which at least one signal is transmitted wirelessly, in particular by radio, from at least one transmitter to at least one receiver, the transmitter and the receiver are considered to be discrete, in particular at least partially implemented as an integrated circuit, elements operated such that

1. a) the transmitter transmits at least one signal, in particular a narrow pulse,
2. b) a receiver receives the signal manipulated by the transmission channel,
3. c) the manipulated signal is prepared so that it can be fed to a mixer,
4. d) the manipulated prepared signal at the mixer is mixed with a reference signal such that there is a mixed signal which at least correlates with the channel impulse response.

One of the significant advantages of the method according to the invention is that at least one extraction of the channel impulse response, in particular the channel impulse response directly, as a useful signal provides, and makes, in particular through the operation of discrete and / or integrated circuits, this commercially available.

In the transmitting device according to the invention, which can be configured as refinements as a radar and / or radio transmitting device, in particular, for example as an RFID tag, and the receiving device according to the invention, as a further development as a radar and / or radio receiving device, in particular, for example as RFID, Day, can be configured, means are provided for carrying out the method and / or its further developments.

By these two devices according to the invention, in each case the implementation of the method according to the invention is achieved, thus enabling the realization of the advantages of the invention and its developments.

Further advantageous embodiments of the invention are given in the dependent claims.

If the method according to the invention is developed in such a way that for the preparation of the manipulated signal it is supplied to at least a first filter, in particular bandpass filter, for, in particular bandpass, filtering and / or at least a first amplifier device for amplification, a signal correlating to the channel impulse response is obtained is optimized for further processing, because the useful signal components can be better detected by the filtering and / or amplification.

In a further development of the method according to the invention, the mixed signal is fed to a second filter, in particular low-pass filtering, designed in particular as a low-pass filter. In particular, the low-pass filtering frees the signal from unnecessary frequency ranges and thus also reduces the noise level of the signal so that it is further optimized for detection.

Preferably, the method according to the invention is developed in such a way that the, in particular low-pass, filtered signal is supplied to a second amplifier device for amplification and / or at least one analog-to-digital converter for analog-to-digital conversion. As a result, the intermediate frequency, IF, signal obtained, in particular by the preceding development, is converted into a digital signal, which is thus accessible to the data processing, wherein, if necessary, prior amplification of the signal may possibly improve the conversion.

According to a development of the method, the reference signal is formed from a carrier frequency in the "ultra-wide-band", UWB, frequency range. This development allows the broadband detection of channel properties in a simple way.

Preferably, this approach is complemented by the development of the method according to the invention in which the correlating signal is processed by means of at least one method of signal processing such that the channel impulse response is extracted from the correlating signal.

As an alternative development, which makes a broadband detection possible, the development of the method according to the invention is to be regarded, in which the reference signal is formed from a signal generated identically to the transmitted signal. This makes it possible, in particular if the method according to the invention is developed in such a way that the transmitter and the receiver are operated in a synchronized manner, at least for the duration of the method steps according to one of the preceding methods, that the channel impulse response as a useful signal already be removed without further signal processing.

Alternatively or additionally, the method according to the invention is developed in such a way that the, in particular low-pass, filtered and / or amplified signal is supplied to a large number of sequentially arranged analog-to-digital converters for analog-to-digital conversion. This enables a more cost-effective implementation of the method, since there are fewer requirements for the individual analog-to-digital converters, in particular with regard to the sample rate.

Preferably, the inventive method is further developed such that the transmitted signal is generated at the transmitting end with a first UWB chip and / or the identically generated signal at the receiving end with a second UWB chip. The use of UWB chips is characterized by the fact that they enable highly accurate synchronization.

Also particularly suitable is the inventive development of the method according to the invention in which the UWB signals are at least partially formed according to the standard IEEE 02.15 4a. This ensures, among other things, the simultaneous use of the transmission channel for location, communication and synchronization.

• Figur eine schematische Darstellung eines Ausführungsbeispiels des Verfahrens sowie Ausführungsbeispiele der das erfindungsgemäße Verfahren durchführenden Anordnungen.

Further details and advantages of the invention will be explained in more detail with reference to an embodiment shown in the single figure. It shows the

• Figure a schematic representation of an embodiment of the method and embodiments of the method according to the invention performing arrangements.

The figure shows an exemplary embodiment of the method according to the invention, whose operation by means of embodiments of the inventive arrangements.

The embodiment of the method according to the invention is based in principle that for measuring a channel impulse response, a transmitting unit Tx at one point A and a receiving unit Rx at a point away from it B is used.

The transmitter Tx radiates to it in a first step S1 a known signal sequence, ideally a pulse out. During transmission in the room, the transmission signal is permanently influenced by the environment.

At the receiver Rx becomes a signal distorted by the channel characteristics in a second step S2 receive. The initially ideal signal, for example shaped as a pulse, may be on the receiving side, for example Rx Sequential impulses include, which then indicate multipath propagation in space, which makes use of, inter alia, the invention.

According to the considerations that underlie the embodiment of the arrangement according to the invention, these sequence pulses can be detected, in which, as the arrangement according to the invention makes, it is realized as a discretely constructed circuit group.

For the detection of these follow-up pulses is on a transmission side Tx sent out a narrow pulse. On the reception side Rx this signal is received, bandpass filtered, amplified, converted to baseband with a mixer and sampled an analog-to-digital converter. By means of digital signal evaluation, the channel impulse response in the time and frequency domain can be analyzed.

The invention now goes beyond integrated circuits (IC) constructed in this way since, in contrast, it offers the possibility of recording the channel impulse response or making it accessible to the user. In contrast to such circuits, the solution according to the invention avoids the focus of these circuits solely on the provision of the concentration and on a resulting optimization of the circuit on the communication. Rather, the invention solves this paradigm and can make on the basis of the embodiments set forth on further inventive considerations based details of the invention to make channel impulse response accessible to the user or to be able to record.

The invention extends the capabilities of a commercially available ultra-wideband Integrated Integrated Circuit (IC) based communication and location system with its solution features. It enables the channel impulse response or channel properties to be measured parallel to the location / communication. A possible circuit structure of the invention will be illustrated as an embodiment of an arrangement of the invention together with the inventive method, which implements and thus provides, in the following section.

To recognize is a transmitting unit Tx that came from a first UWB IC IC1 and a first antenna A1 consists. The chip IC1 is able to generate IEEE 802.15.4a compliant UWB signals. The first transmission antenna A1 emitted in a first step S1 the embodiment of the method according to the invention on the transmitting and receiving side known signal sequences.

For an extraction of the channel impulse response from that in a second step S2 from a second antenna A2 and a third antenna A3 received signal are, according to the illustrated embodiment after one in a third step S3 bandpass filtering on a bandpass filter BP and gain at a first amplifier AMP1 given two ways to get the channel impulse response.

Basically, the invention provides that a mixer MX at an entrance that of the third antenna A3 gets signal and mixes it with one in a fourth step S4 provided reference signal in a fifth step S5 , At the exit of the mixer MX you get the desired signal.

After the mixer MX the signal is in a sixth step S6 on a low pass filter TP low-pass filtered. This step S6 eliminates unneeded frequency ranges that would otherwise raise the noise level of the signal. Subsequently, the ZF Signal in a seventh step S7 through a second amplifier AMP 2 once again amplified and subsequently eighth step converted by an analog-to-digital converter A / D from an analog signal to a digitally sampled signal. An analog-to-digital converter (ADC) is used for this purpose.

possibility 1 in the figure, the position of a switch ST to 1, uses as the reference signal a carrier frequency generated by the generator G in the UWB frequency range, followed by the received signal of the upper branch in the fifth step S5 in the purely real intermediate frequency range of eg 50 Hz to 550 MHz (at a UWB signal bandwidth of 500 MHz) is mixed down. Subsequently, the analog intermediate frequency signal is sampled digitally, ie the sixth to eighth steps are carried out, until the channel impulse response can then be extracted with further signal processing.

possibility 2 , which in the figure corresponds to the position of a switch ST at 1, uses as reference signal a signal identical to the transmission signal which is present at the receiving end Rx with a second UWB chip IC2 in the fourth step S4 is produced. This is done according to the example in the fourth step S4 a synchronization of transmitting and receiving unit needed by your microprocessor uP and a third integrated UWB IC IC3 , which together with the second chip IC2 form a unit SYNC for synchronization is performed. The resulting output signal at the mixer MX is achieved by this temporal tuning achieved the sought channel impulse response. The analog channel impulse response must then also be the sixth to seventh step S6 ... S7 , so in particular still be scanned. In comparison to possibility 1 but then no further processing is necessary.

The invention is not limited to the explained steps and embodiments of the embodiments of the method and the arrangement, but further combinations of individual features of the illustrated with alternative or additional developments are conceivable. For this purpose, in the following discussion, in addition to the partially more detailed representation of already explained embodiments, a few further variations falling within the scope of the claims are shown or contrasted as a non-exhaustive outline. This should be done in a structured manner based on the functions or function groups that are included in the example shown:

Analog / Digital Converter

The invention can be further developed for this purpose, inter alia, by two methods for converting the analog signal into a digital signal.

On the one hand, a powerful ADC can be used. This must have a sample rate of at least 1.1 GSps, so that signals with a frequency of up to 550 MHz can be sampled. For UWB channels with a bandwidth of 1 or 1.5 GHz, at least 3 GSps are required.

An alternative to this is sequential sampling. For this purpose, several ADCs are used with a much lower sample rate (compared to the first solution). The signal at the output of the intermediate frequency amplifier is converted into the frequency domain by means of Fast Fourier Transformation (FFT). The spectrum to be sampled is divided into smaller pieces and an ADC is used for each piece. Subsequently, the digital subfrequency bands are added together and the overall spectrum of the UWB signal is obtained. The channel impulse response is obtained after the inverse FFT.

synchronization

The synchronization according to the embodiment, in particular the synchronization described in the previous paragraph, is also realized by means of UWB signals. Due to their very high signal bandwidth, UWB pulses have a high-precision temporal resolution in the nano to pico seconds range. This allows a precise temporal synchronization between transmitting and receiving units or multiple receiving units.

In a broader sense, such a synchronization method can also be used to temporally synchronize dedicated radio transmitter and receiver units and to enable a coherent transmitting and receiving function.

Coherent radio modules

The two radio unit synchronization procedure described in the previous section can also be used for radio systems with other radio standards. For example, the synchronous operation of two or more radar sensors, and in particular all other radio transmitters and receivers.

There are two possibilities. First, the local oscillator on the various radio units can be synchronized using UWB technology. On the other hand, the software-based control of the transmitting / receiving unit can be synchronized. A highly accurate reference signal then allows a common time base on all devices.

A preferred development of the invention is in this case as a rule that the transmission signal does not have to consist of a single ultra-wideband pulse, but also works with IEEE 802.15.4a standard compliant UWB signals and this a simultaneous use of the channel for communication, positioning and Synchronization enabled.

This can be used to create commercially available UWB ICs that measure the channel impulse response, since the invention makes it possible to simultaneously receive signal for location functions and to measure the channel impulse response

Another advantageous embodiment that supports this is the high-precision synchronization. In this system, it allows the mixed signal to be fed in at the exact time of arrival. The invention also provides developments as an RFID reader or radar sensors and here this precise synchronization allows coherent transmitting and receiving units to operate.

The sampling of the signal in the A / D block has been processed in addition to processing by means of an oscilloscope or a line-topped analog-to-digital converter and alternatively processed by sequential sampling, which represent a cost-effective alternative.

Claims (15)

Method for detecting a channel impulse response in a system operated in particular for communication, in which at least one signal is transmitted wirelessly, in particular by radio, from at least one transmitter to at least one receiver, characterized in that the transmitter and the receiver are discrete, in particular a) the transmitter transmits at least one signal, in particular a narrow pulse, b) a receiver receives the signal manipulated by the transmission channel, c) the manipulated signal is prepared in such a way that it can be fed to a mixer, d) the manipulated prepared signal at the mixer is mixed with a reference signal such that there is a mixed signal which at least correlates with the channel impulse response. e) Advantage which allows at least one extraction of the channel impulse response. Method according to the preceding claim, characterized in that for the preparation of the manipulated signal it is fed to at least a first filter, in particular bandpass filter, for, in particular bandpass, filtering and / or at least a first amplifier device for amplification. Method according to one of the two preceding claims, characterized in that the mixed signal to a second, in particular as a low-pass filter, filter for, in particular low-pass, filtering is supplied. Method according to the preceding claim, characterized in that the, in particular low-pass, filtered signal of a second amplifier means for amplifying and / or at least one analog-to-digital converter for analog-to-digital conversion is supplied. Method according to the preceding claim, characterized in that the reference signal is formed from a carrier frequency in the "ultra-wide-band", UWB, frequency range. Method according to the preceding claim, characterized in that the correlating signal is processed by means of at least one method of signal processing such that the channel impulse response is extracted from the correlating signal. Method according to one of Claims 1 to 4 , characterized in that the reference signal is formed from a signal identically generated with the transmitted signal. Method according to the preceding claim, characterized in that the transmitter and the receiver are operated synchronized at least for the duration of the method steps according to one of the preceding methods. Method according to one of Claims 4 to 8th , characterized in that the, in particular low-pass, filtered and / or amplified signal is supplied to a plurality of sequentially arranged analog-to-digital converters for analog-digital conversion. Method according to one of the preceding claims, characterized in that the transmitted signal is generated on the transmitting side with a first UWB chip and / or the identically generated signal on the receiving side with a second UWB chip. Method according to the preceding claim, characterized in that the UWB signals are at least partially formed according to the standard IEEE 02.15 4a. Transmitting device characterized by means for carrying out the method according to one of the preceding claims. Transmitting device according to the preceding claim, characterized in that the transmitting device is designed as a radar and / or radio transmitting device, in particular, for example RFID, tag. Receiving device characterized by means for performing the method according to one of Claims 1 to 11 , Receiving device according to the preceding claim, characterized in that the receiving device is designed as a radar and / or radio receiving device, in particular, for example, as RFID, reader.

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