DE102017012190A1 - Transmitter and receiver and corresponding procedures - Google Patents

Abstract

A receiver (10) is configured to receive at least one signal transmitted by a transmitter (1), the receiver (10) having a synchronization device (11), the synchronization device (11) being designed in such a way, starting from the received one Signal to synchronize the receiver (10) with the transmitter (1), wherein the receiver (10) comprises a signal evaluation device (12), wherein the signal evaluation device (12) from the received signal data for synchronization determined and sent to the synchronization device (11 ) for the synchronization, wherein the signal evaluation device (12) in the evaluation of a pilot sequence or a partial pilot sequence of a received signal, a time offset between a reference time of a transmission of the signal by the transmitter (1) and one for the evaluation of the reference Time taken and / or estimated value is determined, and where the Sig nalauswertevorrichtung (12) for further evaluation of the pilot sequence accesses symbols of a time offset adapted reference sequence, or wherein the signal evaluation device (12) for the further evaluation of the sub-pilot sequence on symbols of a part of a time offset adapted reference sequence or one of the time offset adapted portion of a reference sequence.

Description

The invention relates to a transmitter and to a receiver and corresponding method for transmitting signals or for synchronizing a receiver with a transmitter.

In many data transmission systems, pilot sequences (also called training sequences or synchronization sequences) are inserted into the data streams to be transmitted for signal detection or parameter estimation. This can be either the transmission of an uninterrupted data stream into which pilot sequences are interspersed at certain intervals, as well as a packet-oriented transmission in which each packet (also called a telegram) usually contains exactly one pilot sequence. The pilot sequence is also called the preamble or midamble if it is at the beginning or in the middle of the package. However, a pilot sequence can also be distributed within the package in the form of two or more subsequences.

In some radio-based systems with asynchronous packet transmission, the transmission pauses are considerably longer than the respective packet duration. In some systems telegram splitting (see [4] and [1], DE 10 2011 082 098 A1 ) in which each packet is divided into a number of subpackets - called fragments or telegram fragments. Each fragment usually contains its own pilot sequence. Telegram splitting proves to be particularly robust in interference-limited systems in which a large number of transmitters emit uncoordinated telegrams that are to be received and decoded by a single receiver. This happens z. As in telemetry systems, sensor networks or applications under the keyword Internet of Things (IoT).

• • Zeitsynchronisation: Schätzung der genauen zeitlichen Lage des Pakets sowie des optimalen Abtastzeitpunktes.
• • Frequenzsynchronisation: Schätzung und Korrektur der Frequenzablage zwischen Sende- und Empfangsoszillator also der Frequenzdifferenz zwischen der Trägerfrequenz des Sendesignals und der Mittenfrequenz des Empfangsfilters.
• • Phasensynchronisation: Schätzung der Phase nach erfolgter Frequenzkorrektur (nur erforderlich bei kohärenter Demodulation).

The demodulation of data of a radio-based data transmission system requires a receiver synchronization consisting of:

• • Time Synchronization: Estimate the exact timing of the packet and the optimal sampling time.
• • Frequency Synchronization: Estimation and correction of the frequency offset between the transmit and receive oscillators, ie the frequency difference between the carrier frequency of the transmit signal and the center frequency of the receive filter.
• • Phase synchronization: Estimation of the phase after frequency correction (only required for coherent demodulation).

In asynchronous packet transmission, these three types of synchronization are to be performed before demodulation for each packet independently of the previously received packets. For this purpose, each packet contains a pilot sequence, with the help of which the initial synchronization (so-called "initial acquisition") can be performed. In addition, during the data demodulation u. U. a tracking (so-called "tracking") of the parameters may be required. The problem of initial synchronization is considered below.

Telegram splitting has the advantage that systems, especially with a large number of uncoordinated transmitters, are robust against packet collisions. For telegram splitting, however, no approaches are known in the field of synchronization, and in particular frequency synchronization, which lead to satisfactory results.

The object of the invention is to propose a transmitter and a receiver, which in particular use telegram splitting and which are improved with regard to the synchronization with respect to the prior art.

The invention solves the problem by a transmitter.

The transmitter is designed to transmit at least one signal having a pilot sequence having a plurality of pilot symbols or a partial pilot sequence. In this case, the transmitter has a signal generator which provides the pilot sequence or partial pilot sequence.

In one embodiment, it is provided that the transmitter is configured in such a way to transmit at least one signal with a pilot sequence having a plurality of pilot symbols. The signal generator provides the pilot sequence such that the pilot sequence has at least two symbol groups each having at least two pilot symbols. In this case, the symbol groups generate an evaluation of a signal received as a result of the transmission of the signal from a receiver with regard to one phase Phase errors which are dependent on a time offset between a reference time of the transmission of the signal by the transmitter and a value assumed and / or estimated for the evaluation for the reference time and which together in the evaluation over the symbol groups in the Substantially compensate each other.

An embodiment is that the symbol groups partially overlap. Thus, in this embodiment, for example, at least one symbol belongs to two symbol groups.

In one embodiment, it is provided that at least one symbol group consists of a middle symbol and two flanking symbols. The middle symbol is in one embodiment the symbol that is evaluated in each case with respect to the phase.

An embodiment consists in that the transmitter is designed in such a way to emit signals each having a pilot sequence having at least four pilot symbols.

In one embodiment, it is provided that the transmitter emits signals having pilot sequences resulting from MSK modulation. The MSK modulation is therefore an example of a modulation for generating the pilot symbols of the signals to be transmitted. Alternatively, it is a GMSK modulation.

An embodiment consists in that the transmitter outputs data by at least two telegram fragments, which the transmitter emits as individual signals and which are shorter than a single total data containing telegram, outputs, and that at least one telegram fragment from the signal generator he witnessed pilot sequence or a part of the pilot sequence pilot sequence has. In this embodiment, telegram splitting is thus applied. One feature of telegram splitting in the prior art is that synchronization with a telegram fragment is generally not possible (eg, with a low SNR or with disturbances in the channel).

$$\begin{array}{l}\left[\text{1}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\right]\text{,}\\ \left[\text{0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\right]\text{ oder}\\ \left[\text{1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\right]\text{.}\end{array}$$

In an embodiment, it is provided that the signal generator provides the pilot sequence with a length of at least eight pilot symbols in such a way that the pilot sequence has one of the following forms: $$\left[\text{0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\right]\text{.}$$

$$\begin{array}{l}\left[\text{1}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\right]\text{.}\\ \left[\text{0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\right]\text{or}\\ \left[\text{1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\right]\text{,}\end{array}$$

The zeros and ones are each the pilot sequence bits before a modulation, ie before the mapping, from which the actual pilot symbols result. An example of the mapping is an MSK mapping, which will be described below (see 11 ).

In one embodiment, the signal generator provides the pilot sequence with a length of at least eight pilot symbols in such a way that a section of the pilot sequence, which is a single or multiple part of the pilot sequence, has one of the following forms: $$\begin{array}{l}\left[\text{0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\right]\text{.}\\ \left[\text{1}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\right]\text{.}\\ \left[\text{0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\right]\text{or}\\ \left[\text{1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\right]\text{.}\end{array}$$

The 0's and 1's are each the pilot sequence bits prior to a modulation that results in the actual pilot symbols. An example of the mapping is an MSK mapping, which will be described below (see 11 ).

$$\begin{array}{l}\left[\text{0}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\right]\text{,}\\ \left[\text{0}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\right]\text{,}\\ \left[\text{1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\right]\text{,}\\ \left[\text{1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\right]\text{,}\\ \left[\text{1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\right]\text{,}\\ \left[\text{1}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\right]\text{,}\\ \left[\text{1}\text{, 0}\text{, 1}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\right]\text{,}\\ \left[\text{1}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\right]\text{,}\\ \left[\text{1}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\right]\text{,}\\ \left[\text{1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\right]\text{,}\\ \left[\text{1}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\right]\text{,}\\ \left[\text{1}\text{, 1}\text{, 1}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\right]\text{,}\\ \left[\text{1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\right]\text{,}\\ \left[\text{1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\right]\text{,}\\ \left[\text{1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\right]\text{,}\\ \left[\text{1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\right]\text{,}\\ \left[\text{1}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\right]\text{ oder}\\ \left[\text{1}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\text{, 0}\text{, 0}\right]\text{.}\end{array}$$

In an embodiment, it is provided that the signal generator provides the pilot sequence with a length of at least twelve pilot symbols in such a way that the pilot sequence has one of the following forms: $$\begin{array}{l}\left[\text{0}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\right]\text{.}\\ \left[\text{0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\right]\text{.}\\ \left[\text{0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\right]\text{.}\\ \left[\text{0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\right]\text{.}\\ \left[\text{0}\text{, 0}\text{, 0}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\right]\text{.}\\ \left[\text{0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\right]\text{.}\\ \left[\text{0}\text{, 1}\text{, 0}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\right]\text{.}\\ \left[\text{0}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\right]\text{.}\\ \left[\text{0}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\right]\text{.}\end{array}$$

$$\begin{array}{l}\left[\text{0}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\right]\text{.}\\ \left[\text{0}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\right]\text{.}\\ \left[\text{1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\right]\text{.}\\ \left[\text{1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\right]\text{.}\\ \left[\text{1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\right]\text{.}\\ \left[\text{1}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\right]\text{.}\\ \left[\text{1}\text{, 0}\text{, 1}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\right]\text{.}\\ \left[\text{1}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\right]\text{.}\\ \left[\text{1}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\right]\text{.}\\ \left[\text{1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\right]\text{.}\\ \left[\text{1}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\right]\text{.}\\ \left[\text{1}\text{, 1}\text{, 1}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\right]\text{.}\\ \left[\text{1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\right]\text{.}\\ \left[\text{1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\right]\text{.}\\ \left[\text{1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\right]\text{.}\\ \left[\text{1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\right]\text{.}\\ \left[\text{1}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\right]\text{or}\\ \left[\text{1}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\text{, 0}\text{, 0}\right]\text{,}\end{array}$$

The zeros and ones are each the pilot sequence bits before modulation. An example of the mapping is an MSK mapping, which will be described below (see 11 ).

$$\begin{array}{l}\left[\text{0}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\right]\text{,}\\ \left[\text{0}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\right]\text{,}\\ \left[\text{0}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\right]\text{,}\\ \left[\text{1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\right]\text{,}\\ \left[\text{1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\right]\text{,}\\ \left[\text{1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\right]\text{,}\\ \left[\text{1}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\right]\text{,}\\ \left[\text{1}\text{, 0}\text{, 1}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\right]\text{,}\\ \left[\text{1}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\right]\text{,}\\ \left[\text{1}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\right]\text{,}\\ \left[\text{1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\right]\text{,}\\ \left[\text{1}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\right]\text{,}\\ \left[\text{1}\text{, 1}\text{, 1}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\right]\text{,}\\ \left[\text{1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\right]\text{,}\\ \left[\text{1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\right]\text{,}\\ \left[\text{1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\right]\text{,}\\ \left[\text{1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\right]\text{,}\\ \left[\text{1}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\right]\text{ oder}\\ \left[\text{1}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\text{, 0}\text{, 0}\right]\text{.}\end{array}$$

An embodiment is that the signal generator provides the pilot sequence with a length of at least twelve pilot symbols in such a way that a portion of the pilot sequence, which is simply or multiply part of the pilot sequence, has one of the following forms: $$\begin{array}{l}\left[\text{0}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\right]\text{.}\\ \left[\text{0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\right]\text{.}\\ \left[\text{0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\right]\text{.}\\ \left[\text{0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\right]\text{.}\\ \left[\text{0}\text{, 0}\text{, 0}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\right]\text{.}\\ \left[\text{0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\right]\text{.}\\ \left[\text{0}\text{, 1}\text{, 0}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\right]\text{.}\\ \left[\text{0}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\right]\text{.}\end{array}$$

$$\begin{array}{l}\left[\text{0}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\right]\text{.}\\ \left[\text{0}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\right]\text{.}\\ \left[\text{0}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\right]\text{.}\\ \left[\text{1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\right]\text{.}\\ \left[\text{1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\right]\text{.}\\ \left[\text{1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\right]\text{.}\\ \left[\text{1}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\right]\text{.}\\ \left[\text{1}\text{, 0}\text{, 1}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\right]\text{.}\\ \left[\text{1}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\right]\text{.}\\ \left[\text{1}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\right]\text{.}\\ \left[\text{1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\right]\text{.}\\ \left[\text{1}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\right]\text{.}\\ \left[\text{1}\text{, 1}\text{, 1}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\right]\text{.}\\ \left[\text{1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\right]\text{.}\\ \left[\text{1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\right]\text{.}\\ \left[\text{1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\right]\text{.}\\ \left[\text{1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\right]\text{.}\\ \left[\text{1}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\right]\text{or}\\ \left[\text{1}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\text{, 0}\text{, 0}\right]\text{,}\end{array}$$

The zeros and ones are each the pilot sequence bits before a modulation, ie before a mapping. An example of the mapping is an MSK mapping, which will be described below (see 11 ).

The transmitter thus uses pilot sequences for an improved - in one embodiment also fragmented - phase estimation when time skews occur.

The phase is determined between the transmitter (or the transmitter frequency) and the receiver (or the receiver frequency). This phase is influenced by the time offset, which relates to a reference time of the transmission of a signal and a value assumed or estimated for this during the evaluation. So the reference time z. Example, the time at which a signal or a pilot symbol of a pilot sequence of the signal is sent out. If an incorrect value (reference time point) is assumed or estimated during the evaluation of the pilot sequence, this has a direct effect on the determination of the phase. Therefore, the transmitter transmits signals with pilot sequences whose symbols, when a time offset occurs, generate such phase errors-as errors in the determination of the phase-which, on average, essentially compensate for the phase values determined per symbol.

Furthermore, the invention solves the problem by a method for transmitting signals.

In one embodiment, the method comprises at least the following steps:

The signals are transmitted with a pilot sequence having a plurality of pilot sequence symbols.

The pilot sequences are provided such that the pilot sequences each have at least two symbol groups each having at least two pilot symbols. In this case, when evaluating a signal received as a result of the transmission of the signal from a receiver to be synchronized with the transmitter, the symbol groups generate with respect to a phase a time offset between a reference time of transmission of the signal and a for the evaluation for the reference time assumed and / or estimated value dependent phase errors, which substantially mutually compensate each other in the evaluation over the symbol groups.

The above embodiments of the transmitter can be realized by steps of corresponding embodiments of the method, so that it is not necessary to repeat the statements here.

The following embodiments relate to the fact that the transmitter emits a plurality of signals, each having a partial pilot sequence. To determine the phase between transmitter and receiver, individual phase values are determined for the individual signals, and the individual phase values are then averaged over the signals. Therefore, for example, the phase errors do not compensate within a signal, but only on the evaluation of (preferably all) received signals. For example, in one embodiment, the signals are telegram fragments which do not have a complete pilot sequence but only partial pilot sequences which complement each other to form the complete pilot sequence. An estimation over several sub-pilot sequences is preferably only to be used if the individual sub-pilot sequences have been transmitted coherently and could still be received coherently at the receiver.

Therefore, according to a supplementary or alternative embodiment, the invention relates to a transmitter which is designed to emit at least two signals each having a pilot part sequence having a plurality of pilot symbols. The signal generator provides the sub-pilot sequences of the signals such that the sub-pilot sequences each comprise at least one symbol group with at least two pilot symbols, the symbol groups of the signals being evaluated by the receiver after receiving the signals Generate signals with respect to a phase of a time offset between a reference time of the respective transmission of a signal and a value assumed and / or estimated for the evaluation for the reference time dependent phase error, which in the evaluation of the signals substantially compensate each other.

In contrast to the previous embodiments, the phase errors in this embodiment thus compensate for evaluation over several signals.

According to one embodiment, at least one partial pilot sequence has at least two symbol groups, with the symbol groups partially overlapping.

An embodiment provides that at least one symbol group consists of a middle symbol and two flanking symbols.

In one embodiment, the transmitter transmits signals having partial pilot sequences resulting from MSK modulation.

An embodiment provides that the signal generator provides the sub-pilot sequences in such a way that the sub-pilot sequences taken together have a section that is single or multiple and that has the following forms: $$\begin{array}{l}\left[\text{0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\right]\text{.}\\ \left[\text{1}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\right]\text{.}\\ \left[\text{0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\right]\text{or}\\ \left[\text{1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\right]\text{.}\end{array}$$

The zeros and ones are each pilot sequence bits before modulation. An example of the mapping is an MSK mapping, which will be described below (see 11 ).

According to one embodiment, the signal generator provides the sub-pilot sequences such that the sub-pilot sequences taken together have a section which is single or multiple and has the following forms: $$\begin{array}{l}\left[\text{0}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\right]\text{.}\\ \left[\text{0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\right]\text{.}\\ \left[\text{0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\right]\text{.}\\ \left[\text{0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\right]\text{.}\\ \left[\text{0}\text{, 0}\text{, 0}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\right]\text{.}\\ \left[\text{0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\right]\text{.}\\ \left[\text{0}\text{, 1}\text{, 0}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\right]\text{.}\\ \left[\text{0}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\right]\text{.}\\ \left[\text{0}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\right]\text{.}\\ \left[\text{0}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\right]\text{.}\\ \left[\text{0}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\right]\text{.}\\ \left[\text{1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\right]\text{.}\\ \left[\text{1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\right]\text{.}\\ \left[\text{1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\right]\text{.}\\ \left[\text{1}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\right]\text{.}\\ \left[\text{1}\text{, 0}\text{, 1}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\right]\text{.}\\ \left[\text{1}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\right]\text{.}\\ \left[\text{1}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\right]\text{.}\\ \left[\text{1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\right]\text{.}\\ \left[\text{1}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\right]\text{.}\\ \left[\text{1}\text{, 1}\text{, 1}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\right]\text{.}\\ \left[\text{1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\right]\text{.}\\ \left[\text{1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\right]\text{.}\\ \left[\text{1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\text{, 0}\text{, 0}\text{, 0}\text{, 0}\right]\text{.}\\ \left[\text{1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\right]\text{.}\\ \left[\text{1}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 0}\right]\text{or}\\ \left[\text{1}\text{, 1}\text{, 1}\text{, 1}\text{, 1}\text{, 0}\text{, 1}\text{, 0}\text{, 1}\text{, 1}\text{, 0}\text{, 0}\right]\text{,}\end{array}$$

The zeros and ones are each pilot sequence bits before a modulation, ie before a mapping, to generate the pilot symbols. An example of the mapping is an MSK mapping, which will be described below (see 11 ).

The abovementioned embodiments thus likewise relate to an extension of the averaging with respect to the phase in a pilot sequence splitting.

If the pilot sequence is divided into several subregions, the result is an improved performance in the frequency estimation, since the difference between the sub-pilot sequences can also be used for frequency estimation if the coherence between the sub-pilot sequences is given.

If the same number of symbols of the sub-pilot sequences are sent per signal, the length of the sub-pilot sequences in relation to the entire pilot sequence is reduced by the factor of the number of split pilot sequences.

In one embodiment, the coherence between the partial pilot sequences is given.

Overall, the sub-pilot sequences are defined so that the sum of the phase errors is minimized with time shifting over several sub-pilot sequences.

The receiver therefore determines the phase not just from one signal but from several signals.

An embodiment of a method for emitting signals comprises at least the following steps:

At least two signals, each with a multiple pilot sequence symbols having partial pilot sequence are sent out.

The sub-pilot sequences are provided such that the sub-pilot sequence each have at least one symbol group each having at least two pilot symbols.

In this case, the symbol groups of the signals in an evaluation of signals received by a receiver (10) as a result of the transmission of the signals generate phase errors with respect to one phase which are dependent on a time offset between a reference instant of the respective emission of a signal and a signal the evaluation for the reference time assumed and / or estimated value depend on and compensate each other in the evaluation of the signals substantially mutually substantially.

The above embodiments of the transmitter can be realized by steps of corresponding embodiments of the method, so that it is not necessary to repeat the statements here.

In addition, the invention solves the problem by a receiver.

In one embodiment, the receiver is, in particular, independent of the design of the transmitter and, in particular, not related to a transmitter whose configurations have been described above. In alternative embodiments, the receiver is dependent on the type of signal transmission by the transmitter, so that receiver and transmitter form a system for data or information communication.

The receiver is configured to receive at least one signal transmitted by a transmitter. The receiver has a synchronization device. The synchronization device is designed in such a way, starting from the received signal to synchronize the receiver with the transmitter. The receiver has a signal evaluation device, wherein the signal evaluation device determines data for the synchronization from the received signal and transfers it to the synchronization device for the synchronization.

An embodiment of the receiver provides that the synchronization device is designed in such a way, starting from a pilot sequence or a partial pilot sequence of the received signal to make a synchronization of the receiver with the transmitter.

In one refinement, the signal evaluation device determines, based on symbols of the pilot sequence or the partial pilot sequence and based on symbols of a known reference sequence or part of a known reference sequence, a plurality (ie at least two) values for a phase between a pilot sequence and a partial pilot sequence the signal transmitted by the transmitter and the signal received by the receiver as a result of the transmission of the signal. The signal evaluator determines a total value for the phase from the values for the phase and passes the total value to the synchronization device for the synchronization.

An embodiment of the receiver provides that the signal evaluation device averages the values for the phases in order to determine the total value for the phase.

In one embodiment, the receiver receives a plurality of signals transmitted by the transmitter. The signal evaluation device determines from the received signal data for synchronization. The synchronization device uses the data obtained from the received signals together for synchronization.

An embodiment of the receiver provides that the receiver receives a plurality of signals transmitted by the transmitter, each having a partial pilot sequence. The partial pilot sequences complement each other to form a pilot sequence. The signal evaluator determines data for synchronization based on each sub-pilot sequence separately for each sub-pilot sequence.

In one embodiment, the receiver receives a plurality of signals transmitted by the transmitter, each having a partial pilot sequence. The partial pilot sequences complement each other to form a pilot sequence. The signal evaluator merges the sub-pilot sequences and then determines data for synchronization based on the merged sub-pilot sequences.

An embodiment of the receiver provides that, in the evaluation of a pilot sequence of a received signal, the signal evaluation device separates the pilot sequence into at least two sub-pilot sequences and determines data for the synchronization separately for each of the at least two sub-pilot sequences.

In one embodiment, when evaluating a pilot sequence of a received signal, the signal evaluation device determines a time offset between a reference time of a transmission of the signal by the transmitter and a value assumed and / or estimated for the evaluation for the reference time. For the further evaluation of the pilot sequence, the signal evaluation device accesses symbols of a reference sequence adapted to the time offset.

An embodiment of the receiver provides that the signal evaluation device in the evaluation of a partial pilot sequence of a received signal, a time offset between a reference time of a transmission of the signal by the transmitter and a value accepted and / or estimated for the evaluation for the reference time value determined. For the further evaluation of the sub-pilot sequence, the signal evaluation device accesses symbols of a part of a reference sequence adapted to the time offset or of a part of a reference sequence adapted to the time offset.

In one embodiment, the signal evaluation device adjusts the reference sequence or the part of the reference sequence in that the signal evaluation device shifts a known reference sequence or part of a known reference sequence in time by the determined time offset.

An embodiment of the receiver provides that the signal evaluation device carries out the adaptation of the reference sequence or the part of the reference sequence in that the signal evaluation device accesses a data memory with corresponding reference sequences or parts of reference sequences.

In one embodiment, the receiver has a filter device and a scanning device.

An embodiment thus relates to a correction of the reference symbols or the reference sequence for the evaluation of the received signals.

The adaptation of the reference sequence is advantageous, for example, in the case where oversampling of the received signals is very small. In addition, the time offset can be estimated much more accurately, for example by interpolation, than this for a correction z. B. by exposure through the filter is possible.

Therefore, the reference symbols of the reference sequence associated with the respective received signal are shifted by the determined value of the time shift. The corrected or time offset adjusted reference symbols are then used to estimate the phase error. Thus, the temporal offset of the symbols in the estimate can be almost completely suppressed. The adjusted reference sequences are therefore calculated depending on the determined or, for example, estimated time offset or a data memory, for. B. a look-up table taken.

Furthermore, the invention achieves the object by a method for synchronizing a receiver with a transmitter. The synchronization method, in one embodiment, is part of a method of receiving signals transmitted by a transmitter and received by a receiver. The method basically comprises receiving at least one signal from the transmitter, evaluating the signal to obtain synchronization data, and synchronizing the receiver using the synchronization data.

• • Mindestens ein von dem Sender ausgesendetes Signal wird von dem Empfänger empfangen.
• • Ausgehend von einer Pilotsequenz oder einer Teil-Pilotsequenz des empfangenen Signals wird eine Synchronisation des Empfängers mit dem Sender vorgenommen.

In one embodiment, the method comprises at least the following steps:

• At least one signal transmitted by the transmitter is received by the receiver.
• • Based on a pilot sequence or a partial pilot sequence of the received signal, the receiver is synchronized with the transmitter.

An embodiment provides that, based on symbols of the pilot sequence or the partial pilot sequence of the transmitted signal and a signal received as a result of the transmission of the signal from the receiver, a plurality of values for a phase between a pilot sequence and a partial pilot sequence of the emitted by the transmitter Signal and the signal received by the receiver as a result of the transmission of the signal, and that, based on the values for the phase, a total value for the phase is determined and used for the synchronization.

In one embodiment, it is provided that a plurality of transmitted signals are received, that data for the synchronization of each received signal are determined, and that the determined data are used together for the synchronization.

An embodiment provides that a time offset between a reference time of a transmission of the signal by the transmitter and a value assumed and / or estimated for the reference time is determined, and in that a pilot sequence of the received signal with symbols adapted to the time offset Reference sequence is evaluated.

In one embodiment, it is provided that a time offset between a reference time of a transmission of the signal by the transmitter and a value assumed and / or estimated for the reference time is determined, and that a partial pilot sequence of the received signal with symbols of a part a reference sequence adapted to the time offset or with symbols of a time offset adapted part of a reference sequence is evaluated.

The above embodiments of the receiver can be realized by steps of corresponding embodiments of the method, so that a repetition of the embodiments is omitted here.

The following embodiments of a receiver relate to the DFT method for determining the data for the synchronization of the receiver with the transmitter. The following embodiments at least partially supplement the preceding embodiments or represent independent alternatives.

An embodiment of the receiver provides that the receiver is configured in such a way to receive a plurality of telegram fragments transmitted by the transmitter, wherein the telegram fragments each have a partial pilot sequence, wherein the telegram fragments complement each other to form a telegram contains data sent to the transmitter and wherein the telegram fragments are shorter than a single telegram having the transmitted data. In addition, the partial pilot sequences complement each other to form a pilot sequence. The signal evaluation device determines, based on the partial pilot sequences and using the DFT method, a value for a frequency difference between a transmission frequency of the transmitter and a reception frequency of the receiver. This determination takes place in that the signal evaluation device determines values of decision variables for each sub-pilot sequence by the signal evaluation device combining the determined values of the decision variables via the sub-pilot sequences and carrying out a determination of a maximum value with the combined values. Optionally, the maximum value is compared with a decision threshold.

In an embodiment, it is provided that the signal evaluation device determines the values of the decision variables for each sub-pilot sequence by multiplying values of a multiplication of samples of the respective sub-pilot sequence by conjugate complex values of a same for a plurality of frequencies of a complex exponential oscillation called frequency hypotheses Number of reference symbols of a known reference sequence and with samples of the complex exponential oscillation forms and multiplies the multiplication values.

In accordance with one embodiment, the signal evaluation device combines the values of the decision variables determined for the sub-pilot sequences together (that is, jointly over the sub-pilot sequences) for the sub-pilot sequences, by adding the amounts of the values of the decision variables to the signal evaluation device.

In an embodiment, it is provided that the signal evaluation device combines the values of the decision variables determined for the sub-pilot sequences together for the sub-pilot sequences by the signal evaluation device forming a sum of the magnitudes of a real part and an imaginary part of the values of the decision variables.

According to one embodiment, the signal evaluation device combines the values of the decision variables determined for the sub-pilot sequences together for the sub-pilot sequences with one another, by the signal evaluation device adding up the absolute squares of the values of the decision variables.

In one embodiment, it is provided that the signal evaluation device combines the values of the decision variables determined for the sub-pilot sequences together for the sub-pilot sequences coherently, taking into account the magnitude and phase of the values of the decision variables.

According to one embodiment, the signal evaluation device combines the determined values of the decision variables with the inclusion of weighting factors.

In one embodiment, it is provided that the signal evaluation device combines the determined values of the decision variables with the inclusion of weighting factors relating in each case to the partial pilot sequences.

According to one embodiment, the signal evaluation device determines the weighting factors on the basis of a signal-to-noise ratio of the respective telegram fragment.

In one embodiment, it is provided that the signal evaluation device determines the weighting factors as proportional to a root from the signal-to-noise ratio.

According to one embodiment, the signal evaluation device determines the weighting factors as proportional to a root from a quotient of the signal-to-noise ratio and a noise power of the respective telegram fragment.

In one refinement, it is provided that the signal evaluation device determines the weighting factors as a function of a computing power available to the signal evaluation device or as a function of a ratio of the signal-to-noise ratio relative to a predefinable relational value or as a function of an interference power either as proportional to a root from the signal-to-noise ratio or proportional to a root of a quotient of the signal-to-noise ratio and a noise power of the respective telegram fragment determined.

According to one embodiment, the receiver is designed in such a way to receive a plurality of telegram fragments transmitted by the transmitter, wherein the telegram fragments each have a partial pilot sequence, wherein the telegram fragments complement each other to a telegram containing data transmitted by the transmitter wherein the telegram fragments are shorter than a single telegram having the transmitted data and wherein the partial pilot sequences complement each other to a pilot sequence. The signal evaluation device determines, based on the partial pilot sequences and using the DFT method, a value for a frequency difference between a transmission frequency of the transmitter and a reception frequency of the receiver, in which the signal evaluation device determines values of decision variables for each partial pilot sequence, the determined values of the decision variables is combined with each other via the sub-pilot sequences and with the combined values a determination of a maximum value is performed. It leads the Signal evaluation device, a time estimate for a time offset between a reference time of transmission of the telegram fragment and a for the evaluation of the telegram fragment for the reference time assumed and / or estimated value by by the signal evaluation device starting from a by the determination of the maximum Value maximum value and at least one with respect to a time variable to the maximum value adjacent value determines a time estimate for a time offset.

In one embodiment, it is provided that the receiver is designed in such a way to receive at least one telegram transmitted by the transmitter, the telegram having a pilot sequence. The signal evaluation device determines, based on the pilot sequence and using the DFT method, a value for a frequency difference between a transmission frequency of the transmitter and a reception frequency of the receiver, in which the signal evaluation device determines values of decision variables for the pilot sequence, performs a determination of a maximum value. In this case, the signal evaluation device carries out a time estimation for a time offset between a reference time of a transmission of the telegram and a value assumed and / or estimated for the evaluation of the telegram for the reference time by the signal evaluation device starting from a by the determination of the maximum Value obtained maximum value and at least one with respect to a time variable to the maximum value adjacent value determines a time estimate for a time offset.

According to one embodiment, the signal evaluation device obtains the maximum value based on the determination of the maximum value and a positive comparison of the maximum value with a decision threshold.

In an embodiment, it is provided that the signal evaluation device generates the time estimate from the maximum value and two adjacent values, and that the two adjacent values with respect to the time variable precede or follow the determined maximum value.

According to one embodiment, the signal evaluation device determines a polynomial for the maximum value and the two adjacent values. In addition, the signal evaluation device determines the time estimate from an extreme value associated with the polynomial.

An embodiment is that the signal evaluation device performs the interpolation with a second degree polynomial.

According to one embodiment, the signal evaluation device (12) carries out the interpolation with a polynomial of the following form: y (x) = y ₀ -c (xx ₀ ) ² where the free parameters y ₀ , c and x _{0 are} based on the maximum value and the adjacent values are determined.

wobei x₀ ein Abszissenwert eines Maximums des Polynoms, y(0) der Maximalwert und y(-1) sowie y(1) die benachbarten Werte sindThe transformation device determines the maximum value of the interpolation curve with the following function: $x_0=\frac{1}{2}\frac{y\left(1\right)-y\left(-1\right)}{2y\left(0\right)-y\left(1\right)-y\left(-1\right)}.$

where x _{0 is} an abscissa value of a maximum of the polynomial, y (0) is the maximum value, and y (-1) and y (1) are the adjacent values

As an interpolation function, in one embodiment a polynomial of the second degree of the form y (x) = y ₀ -c (xx ₀ ) ^{2 is} used.

The abscissa value x _{0 of} the polynomial maximum represents, for example, the improved time estimate (normalized to the sampling interval T / N).

berechnen.From the abscissa value x _{0 of} the maximum polynomial, the improved frequency estimate can be used $$\widehat{\nu }T=\frac{{\mathrm{<figure-callout\; id="0"\; label="i"\; filenames="DE102017012190A1\_0027.png,DE102017012190A1\_0029.png"\; state="\{\{state\}\}">i</figure-callout>}}_0+x_0}{N_{\text{FFT}}}-\{\begin{array}{cc}0& \text{For}{\mathrm{<figure-callout\; id="0"\; label="i"\; filenames="DE102017012190A1\_0027.png,DE102017012190A1\_0029.png"\; state="\{\{state\}\}">i</figure-callout>}}_0<N_{\text{FFT}}/2\\ 1& \text{For}{\mathrm{<figure-callout\; id="0"\; label="i"\; filenames="DE102017012190A1\_0027.png,DE102017012190A1\_0029.png"\; state="\{\{state\}\}">i</figure-callout>}}_0\ge N_{\text{FFT}}/2\end{array}$$

to calculate.

In one embodiment, it is provided that the receiver is configured in such a way to receive a plurality of telegram fragments transmitted by the transmitter, the telegram fragments each having a partial pilot sequence, the telegram fragments complementing one another by the telegram Transmitter sends transmitted data, wherein the telegram fragments are shorter than a single transmitted data having the telegram and wherein the sub-pilot sequences complement each other to a pilot sequence.

The signal evaluation device determines, based on the partial pilot sequences and using the DFT method, a value for a frequency difference between a transmission frequency of the transmitter and a reception frequency of the receiver. This is achieved by the signal evaluation device determining values of decision variables for each sub-pilot sequence, combining the determined values of the decision variables via the sub-pilot sequences and performing a determination of a maximum value with the combined values.

The signal evaluation device carries out a frequency estimation for the frequency difference, in that the signal evaluation device determines a frequency estimated value on the basis of a maximum value obtained by the determination of the maximum value and at least one value adjacent to the maximum value with regard to a frequency variable.

According to one embodiment, the receiver is designed in such a way to receive at least one telegram transmitted by the transmitter, the telegram having a pilot sequence. The signal evaluation device determines, based on the pilot sequence and using the DFT method, a value for a frequency difference between a transmission frequency of the transmitter and a reception frequency of the receiver, in which the signal evaluation device determines values of decision variables for the pilot sequence, performs a determination of a maximum value. The signal evaluation device determines a frequency estimate for the frequency difference by performing the signal evaluation device, starting from a maximum value obtained by the determination of the maximum value and at least one with respect to a frequency variable to the maximum value a frequency estimated value.

In one embodiment, it is provided that the signal evaluation device receives the maximum value from the maximum value and a positive comparison of the maximum value with a decision threshold.

According to one embodiment, the signal evaluation device generates the frequency estimated value from the maximum value and two adjacent values, wherein the two adjacent values with respect to the frequency variable precede or follow the determined maximum value.

In one embodiment, it is provided that the signal evaluation device determines a polynomial for the maximum value and the two adjacent values, and that the signal evaluation device determines the frequency estimated value from an extreme value associated with the polynomial.

An embodiment is that the signal evaluation device performs the interpolation with a second degree polynomial.

According to one embodiment, the signal evaluation device (12) carries out the interpolation with a polynomial of the following form: y (x) = y ₀ -c (xx ₀ ) ² where the free parameters y ₀ , c and x _{0 are} based on the maximum value and the adjacent values are determined.

wobei x₀ ein Abszissenwert eines Maximums des Polynoms, y(0) der Maximalwert und y(-1) sowie y(1) die benachbarten Werte sindThe transformation device determines the maximum value of the interpolation curve with the following function: $x_0=\frac{1}{2}\frac{y\left(1\right)-y\left(-1\right)}{2y\left(0\right)-y\left(1\right)-y\left(-1\right)}.$

where x _{0 is} an abscissa value of a maximum of the polynomial, y (0) is the maximum value, and y (-1) and y (1) are the adjacent values

As an interpolation function, in one embodiment a polynomial of the second degree of the form y (x) = y ₀ -c (xx ₀ ) ^{2 is} used.

The abscissa value x _{0 of} the polynomial maximum represents, for example, the improved time estimate (normalized to the sampling interval T / N).

berechnen.From the abscissa value x _{0 of} the maximum polynomial, the improved frequency estimate can be used

to calculate.

According to one embodiment, the signal evaluation device determines the time estimate and uses it for a new determination of the frequency difference by the signal evaluation device used in a re-determination of the values of the decision variable shifted by the time estimate samples of the respective sub-pilot sequences or reference symbols of a reference sequence to the Time estimate shifts in time.

In one embodiment, it is provided that the signal evaluation device carries out an interpolation of the sampled values of the respective partial pilot sequences for the new determination of the frequency difference.

According to one embodiment, after the frequency difference has been determined again, the signal evaluation device carries out a frequency estimation for the frequency difference by the signal evaluation device starting from a maximum value obtained by the determination of the maximum value and a positive comparison with the decision threshold and at least one value adjacent to a frequency variable Frequency estimate determined.

The abovementioned embodiments of the receiver can also be implemented on the method for synchronization-possibly as part of a method for receiving signals.

• • dass durch den Empfänger mehrere von dem Sender ausgesendete Telegramm-Fragmente empfangen werden,
  • o wobei die Telegramm-Fragmente jeweils eine Teil-Pilotsequenz aufweisen,
  • o wobei die Telegramm-Fragmente sich zu einem Telegramm ergänzen, das von dem Sender ausgesendete Daten beinhaltet,
  • o wobei die Telegramm-Fragmente kürzer als das Telegramm sind,
  • o wobei die Teil-Pilotsequenzen sich zu einer Pilotsequenz ergänzen,
• • dass ausgehend von den Teil-Pilotsequenzen der Empfänger mit dem Sender synchronisiert wird,
  • o wobei ausgehend von den Teil-Pilotsequenzen und unter Anwendung des DFT-Verfahrens ein Wert für eine Frequenzdifferenz zwischen einer Sendefrequenz des Senders und einer Empfangsfrequenz des Empfängers ermittelt wird,
    • ■ indem für jede Teil-Pilotsequenz Werte von Entscheidungsvariablen ermittelt werden,
    • ■ indem die ermittelten Werte der Entscheidungsvariablen über alle Teil-Pilotsequenzen miteinander kombiniert werden und
    • ■ indem mit den kombinierten Werten eine Bestimmung eines Maximum-Werts durchführt wird.

An embodiment of the method, which is complementary or alternative to the aforementioned embodiments, provides

• That a plurality of telegram fragments transmitted by the transmitter are received by the receiver,
  • o the telegram fragments each having a partial pilot sequence,
  • o the telegram fragments complement each other to form a telegram containing data transmitted by the transmitter,
  • o where the telegram fragments are shorter than the telegram,
  • o the partial pilot sequences complement each other to form a pilot sequence,
• That, starting from the sub-pilot sequences, the receiver is synchronized with the transmitter,
  • o wherein, based on the partial pilot sequences and using the DFT method, a value for a frequency difference between a transmission frequency of the transmitter and a reception frequency of the receiver is determined,
    • ■ by determining values of decision variables for each sub-pilot sequence,
    • ■ by combining the determined values of the decision variables across all sub-pilot sequences, and
    • ■ by making a determination of a maximum value with the combined values.

An embodiment provides that a plurality of telegram fragments transmitted by the transmitter are received by the receiver, the telegram fragments each having a partial pilot sequence, wherein the telegram fragments complement each other to form a telegram containing data transmitted by the transmitter , wherein the telegram fragments are shorter than the telegram, wherein the partial pilot sequences complement each other to a pilot sequence.

Based on the partial pilot sequences, the receiver is synchronized with the transmitter. Starting from the sub-pilot sequences and using the DFT method, a value for a frequency difference between a transmitting frequency of the transmitter and a receiving frequency of the receiver is determined by determining values of decision variables for each sub-pilot sequence by transposing the determined values of the decision variables all sub-pilot sequences are combined and by performing a determination of a maximum value with the combined values. A time estimate for a time lag between a reference Time of transmission of the telegram fragment and for the evaluation of the telegram fragment for the reference time assumed and / or estimated value is performed by the signal evaluation device starting from a maximum value obtained by the determination of the maximum value and at least one with respect Time variable to the maximum value adjacent value determines a time estimate for a time offset.

An embodiment consists in that at least one telegram transmitted by the transmitter is received by the receiver, the telegram having a pilot sequence, the receiver being synchronized with the transmitter starting from the pilot sequence, whereby, starting from the pilot sequence and using the DFT Method is a value for a frequency difference between a transmission frequency of the transmitter and a receiving frequency of the receiver is determined by determining values of decision variables for the pilot sequence by performing a determination of a maximum value with the determined values, wherein a time estimate for a time delay between a reference time of a transmission of the telegram fragment and a value assumed and / or estimated for the evaluation of the telegram fragment for the reference time is carried out by the signal evaluation device starting from a signal determined by the determination of the maximum value rts obtained maximum value and at least one with respect to a time variable to the maximum value adjacent value determines a time estimate for a time offset.

An embodiment provides that a plurality of telegram fragments transmitted by the transmitter are received by the receiver, the telegram fragments each having a partial pilot sequence, wherein the telegram fragments complement each other to form a telegram containing data transmitted by the transmitter , wherein the telegram fragments are shorter than the telegram, wherein the sub-pilot sequences complement each other to a pilot sequence, wherein starting from the sub-pilot sequences, the receiver is synchronized with the transmitter. Starting from the sub-pilot sequences and using the DFT method, a value for a frequency difference between a transmitting frequency of the transmitter and a receiving frequency of the receiver is determined by determining values of decision variables for each sub-pilot sequence by transposing the determined values of the decision variables all sub-pilot sequences are combined with each other and by performing a determination of a maximum value with the combined values. A frequency estimate for the frequency difference is performed by determining the signal evaluation device from a maximum value obtained by the determination of the maximum value and a frequency estimated value at least one value adjacent to the maximum value with respect to a frequency variable.

An embodiment consists in that at least one telegram transmitted by the transmitter is received by the receiver, the telegram having a pilot sequence. Based on the pilot sequence, the receiver is synchronized with the transmitter. Based on the pilot sequence and using the DFT method, a value for a frequency difference between a transmission frequency of the transmitter and a reception frequency of the receiver is determined by determining values of decision variables for the pilot sequence by determining a maximum value with the determined values is performed. A frequency estimation is performed for the frequency difference by determining the signal evaluation device from a maximum value obtained by the determination of the maximum value and at least one value adjacent to a frequency variable to the maximum value.

The above embodiments of the receiver can be realized by steps of corresponding embodiments of the method, so that a repetition of the embodiments is omitted here.

Depending on the configuration, the receiver uses a method for frequency estimation in the case of fragmented transmission, that is to say fragmentation of the telegrams during "telegram splitting".

In one embodiment, the DFT method for frequency estimation is thus extended to telegram splitting.

In one embodiment, a combination after the DFT, which is applied to the individual telegram fragments, and before the maximum value search, which thus refers to all telegram fragments made.

In one embodiment, the signal processing of the DFT method up to and including the DFT is applied to each telegram fragment in order to combine the results before the maximum value search via the frequency hypotheses. The further processing takes place on the basis of the combined values.

As an advantage results from the merge a significant noise reduction, which can significantly improve the estimation result for frequency and time.

In one embodiment, a combination is achieved by weighted addition of individual results, e.g. B. the amounts or square squares instead.

• • der Beträge,
• • der Summe der Beträge von Real- und Imaginärteil oder
• • der Betragsquadrate.

In different embodiments, a weighted addition of the respectively individually determined values of the decision variables is effected by an addition

• • the amounts,
• • the sum of the amounts of real and imaginary part or
• • the squares of sums.

Mathematically, the configurations can be formulated as follows:

Let d _{i, n} [k] be the decision variables (for i = 0, 1, ..., N _DFT -1) of the kth sampling time after the DFT of the nth fragment.

$$\text{Addition der Beträge von Re un Im:}\left|d_i\left[k\right]\right|={\displaystyle \sum _{n=0}^{N_{\text{frag}}-1}{c}_n\left(\left|\text{Re}\left\{d_{i,n}\left[k\right]\right\}\right|+\left|\text{Im}\left\{d_{i,n}\left[k\right]\right\}\right|\right)}$$

$$\text{Addition der Betragsquadrate:}{\left|d_i\left[k\right]\right|}^2={\displaystyle \sum _{n=0}^{N_{\text{frag}}-1}{c}_n^2{\left|d_{i,n}\left[k\right]\right|}^2}$$

Then: $$\text{Addition of the amounts:}\left|d_i\left[k\right]\right|={\displaystyle \underset{n=0}{\overset{N_{\text{question}}-1}{\Sigma }}{c}_n\left|d_{i.n}\left[k\right]\right|}$$

$$\text{Adding the amounts of Re un Im:}\left|d_i\left[k\right]\right|={\displaystyle \underset{n=0}{\overset{N_{\text{question}}-1}{\Sigma }}{c}_n\left(\left|\text{re}\left\{d_{i.n}\left[k\right]\right\}\right|+\left|\text{in the}\left\{d_{i.n}\left[k\right]\right\}\right|\right)}$$

$$\text{Addition of absolute squares:}{\left|d_i\left[k\right]\right|}^2={\displaystyle \underset{n=0}{\overset{N_{\text{question}}-1}{\Sigma }}{\mathrm{<figure-callout\; id="2"\; label="c\; n"\; filenames="DE102017012190A1\_0027.png,DE102017012190A1\_0036.png"\; state="\{\{state\}\}">c\; </figure-callout>}}_n^{}{\left|d_{i.n}\left[k\right]\right|}^2}$$

In one embodiment, it is provided that the symbol grid remains constant over the duration of all transmitted fragments and the distance between the fragments (eg in number of symbol intervals) is known to the receiver. In this case, the k-th samples from each telegram fragment (counted from the beginning of the fragment) correspond to each other. Furthermore, it is provided in one embodiment that the frequency offset over the duration of all fragments does not change significantly.

In one embodiment, a coherent combination, i. H. a combination of amount and phase of the respective determined value of the decision variables. This especially for the case that the carrier phase of telegram fragment remains the same telegram fragment, d. H. the coherence must be given over the telegram fragments.

The choice of weighting factors for the addition of the values of the decision variables is specified in some embodiments.

In one embodiment, the aforementioned weighting factors c _{n are} chosen to be proportional to the root of the estimated signal-to-noise power ratio SNR _{n of} the n-th telegram fragment, wherein the estimated SNR in one embodiment also includes the power of possibly existing interference signals. This corresponds to the Maximum Ratio Combining (MRC) for antenna diversity.

In the case of interference power, which may be different for the individual fragments, it is an embodiment to set the weighting factors proportional to the root of the ratio SNR _n / P _{Nn of} the estimated SNR to the estimated noise power P _{N of} the n-th telegram fragment ,

By choosing the weighting factors, the SNR in the decision variable after the combination is maximized.

Alternatively, the above weighting factors c _n will be set equal to 1. This corresponds to the well-known Equal Gain Combining (EGC) for antenna diversity.

An embodiment represents an improvement of the parameter estimates.

In one embodiment, an improvement of the time estimation by means of interpolation takes place.

To increase the accuracy of the time estimate, it provides an embodiment, after determining the time index k ₀ in the DFT method, the time estimate by an interpolation between the maximum value (ie | d _i [k ₀ ] |), the value before (ie | d _i [k ₀ -1] |) and the value after that (ie | d _i [k ₀ +1] |).

The two neighboring values must have the same frequency index as the maximum value, ie i = i ₀ [k ₀ ].

As an interpolation function, in one embodiment a polynomial of the second degree of the form y (x) = y ₀ -c (xx ₀ ) ^{2 is} used.

The free parameters y ₀ , c and x ₀ are determined in one embodiment such that the polynomial is represented by the three values y (-1) = | d _i [k ₀ -1] |, y (0) = | d _i k ₀ ] | and y (1) = | d _i [k ₀ +1] | runs.

The abscissa value x _{0 of} the polynomial maximum represents the improved time estimate (normalized to the sampling interval T / N). It can be calculated closed from the three given y-values as follows: $$x_0=\frac{1}{2}\frac{y\left(1\right)-y\left(-1\right)}{2y\left(0\right)-y\left(1\right)-y\left(-1\right)}.$$

In an alternative or additional embodiment, an improvement of the frequency estimation is carried out by means of interpolation.

To increase the accuracy of the frequency estimate, it provides an embodiment, after determining the time index k _0, the frequency _estimate by an interpolation between the maximum value at the point i ₀ (ie d _i0 [k ₀ ]), the value for i ₀ -1 (ie d _i0-1 [k ₀ ]) and the value for i ₀ +1 (ie d _{i0 + 1} [k ₀ ]).

The two neighboring values must come from the same DFT from which the maximum value was determined. This is the DFT at time k ₀ .

As an interpolation function, in one embodiment a polynomial of the second degree of the form y (x) = y ₀ -c (xx ₀ ) ^{2 is} used. This corresponds to the aforementioned polynomial as described for improving the time estimate.

The free parameters y ₀ , c and x ₀ are determined so that the polynomial is exactly defined by the three values y (-1) = | d _i0-1 [k ₀ ] |, y (0) = | d _i0 [k ₀ ] | and y (1) = | d _{i0 + 1} [k ₀ ] | runs.

berechnen.From the abscissa value x _{0 of} the maximum polynomial, the improved frequency estimate can be used

to calculate.

The value x ₀ can be calculated in a closed manner from the three given y-values according to formula (8).

In one embodiment, the following sequence of measures for estimation improvement is provided.

1. 1. Interpolation im Zeitbereich wie zuvor beschrieben. Ein Ergebnis ist der Zeitschätzwert τ̂.
2. 2. Näherungsweise Berechnung von L neuen Abtastwerten des Signals x(t) im Symboltakt, wobei die Abtastzeitpunkte gegenüber den ursprünglichen um τ̂ verschoben sind. Dies geschieht zweckmäßigerweise mittels einer Interpolationsfilterung der vorhandenen Abtastwerte x[k-LN-1], x[k-LN], ..., x[k+2].
   • • Als Interpolationsfilter wird in einer Ausgestaltung ein FIR-Filter mit vier Koeffizienten verwendet. Dies liefert erfahrungsgemäß eine ausreichende Genauigkeit bei 2-facher Überabtastung.
   • • Zur Berechnung der Filterkoeffizienten sieht es eine Ausgestaltung vor, die Methode der Minimierung des mittleren quadratischen Fehlers (Minimum Mean Square Error = MMSE) zu verwenden, wobei als Berechnungsgrundlage die Faltung des Modulationsimpulses mit der Impulsantwort des Empfangsfilters dient. Bei einem matched Filter als Empfangsfilter ist dies die AKF des Modulationsimpulses.
   • • Die Filterkoeffizienten lassen sich a priori für ein hinreichend feines Raster von Zeitschätzhypothesen (z. B. im Raster 0.01T) berechnen und abspeichern. Zur Anwendung kommt jeweils das Filter, dessen Zeithypothese dem aktuellen Zeitschätzwert τ̂ am nächsten liegt.
3. 3. Erneute Berechnung der Entscheidungsvariablen d_i[k₀] auf Basis der im vorherigen Schritt interpolierten Abtastwerte. Dabei kann eine andere DFT-Länge gewählt werden.
   • • Da nur drei Ausgangswerte der DFT interessieren, kann diese ersetzt werden durch die dreimalige Multiplikation mit Abtastwerten dreier komplexer Exponentialschwingungen mit den Frequenzen ${\nu }_{0}T-\frac{1}{N_{\text{DFT}}},{\nu }_{0}T\text{ und }{\nu }_{0}T+\frac{1}{N_{\text{DFT}}},$
     
     wobei die DFT-Länge beibehalten wird.
4. 4. Polynominterpolation im Frequenzbereich wie zuvor beschrieben. Ein Ergebnis ist der Frequenzschätzwert
5. 5. Zur weiteren Verbesserung der Schätzwerte wird in einer weiteren Ausgestaltung anschließend eine zweite Polynominterpolation durchgeführt, die Werte verwendet, die in einem dichteren Frequenzraster liegen. Dazu müssen die DFT-Eingangswerte dreimal mit Abtastwerten dreier komplexer Exponentialschwingungen mit den Frequenzen ν̂T -Δν̂T, ν̂T und ν̂T + Δν̂T multipliziert werden, wobei ΔγT<<1/N_DFT zu wählen ist. In einer Ausgestaltung gilt: $\mathrm{\Delta }\nu T=\frac{1}{8N_{\text{DFT}}}.$
   

In order to optimize time and frequency estimation, it is intended to work with an oversampling factor of N = 2 in one embodiment and to carry out the following operations in the specified sequence:

1. 1. Interpolation in the time domain as previously described. One result is the time estimate τ.
2. 2. Approximately calculate L new samples of the signal x (t) in the symbol clock, with the sampling times shifted from the original by τ. This is done expediently by means of interpolation filtering of the available samples x [k-LN-1], x [k-LN],..., X [k + 2].
   • In one embodiment, an FIR filter with four coefficients is used as the interpolation filter. Experience has shown that this provides sufficient accuracy with 2-fold oversampling.
   • • For the calculation of the filter coefficients, it is an embodiment to use the method of minimizing the mean square error (MMSE), where Basis of calculation is the convolution of the modulation pulse with the impulse response of the reception filter. For a matched filter as a receive filter, this is the AKF of the modulation pulse.
   • • The filter coefficients can be a priori calculated and stored for a sufficiently fine grid of time estimation hypotheses (eg in the 0.01T grid). In each case the filter is used whose time hypothesis is closest to the current time estimate τ.
3. 3. Re-calculation of the decision variable d _i [k ₀ ] on the basis of the samples interpolated in the previous step. In this case, a different DFT length can be selected.
   • • Since only three output values of the DFT are of interest, this can be replaced by the three-times multiplication with samples of three complex exponential oscillations with the frequencies ${\nu }_{0}T-\frac{1}{N_{\text{DFT}}}.{\nu }_{0}T\text{and}{\nu }_{0}T+\frac{1}{N_{\text{DFT}}}.$
     
     maintaining the DFT length.
4. 4. Polynomial interpolation in the frequency domain as previously described. One result is the frequency estimate
5. 5. In order to further improve the estimated values, in a further refinement, a second polynomial interpolation is then carried out, which uses values which lie in a denser frequency raster. For this, the DFT input values must be multiplied three times with samples of three complex exponential oscillations with the frequencies νT -ΔνT, νT and νT + ΔνT, where ΔγT << 1 / N _{DFT is} to be selected. In one embodiment: $\mathrm{\Delta }\nu T=\frac{1}{\mathrm{8th}{N}_{\text{DFT}}},$
   

As an alternative to steps 3 to 5, in one embodiment a method is used for the direct estimation of the remaining frequency offset. This is z. For example, the method of Louise and Reggiannini.

This only requires the following steps:

wobei die Abtastwerte x[.] die interpolierten Werte aus dem 2. Schritt sind. Die Multiplikation mit einer komplexen Exponentialschwingung mit der Frequenz ν₀T entspricht einer Frequenzkorrektur um die Frequenz ν₀T.3. Calculation of L values according to $$\begin{array}{cc}z\left[l\right]=x\left[k-\left(L-1-l\right)N\right]a\text{*}\left[l\right]e^{j2\pi l{\nu }_{0}T}& \text{for l}=0\mathrm{1,}\mathrm{2,}....\text{L}-\mathrm{1,}\end{array}$$

where the samples x [.] are the interpolated values from the 2nd step. The multiplication with a complex exponential oscillation with the frequency ν ₀ T corresponds to a frequency correction around the frequency ν ₀ T.

4. Carrying out the calculations according to the formulas (2) and (4) with the values from formula (9). The estimate for the total frequency offset then results from the sum of ν ₀ T and the estimate from formula (4).

Furthermore, the invention relates to a system for signal transmission, comprising at least one transmitter according to one of the embodiments discussed above and at least one receiver according to one of the above embodiments.

Finally, the invention relates to a computer program with a program code for carrying out the aforementioned method according to one of the above embodiments.

• 1 eine schematische Darstellung einer Signalverarbeitung zur Zeit- und Frequenzschätzung,
• 2 eine Darstellung eines MSK-Basisband-Signals für drei positiv gemappte Symbole,
• 3 eine Darstellung eines MSK-Basisband-Signals bei idealem Zeitversatz,
• 4 eine Darstellung eines MSK-Basisband-Signals bei negativem Zeitversatz,
• 5 einen Verlauf der Symbolamplitude nach der Matched Filterung über dem Zeitversatz,
• 6 einen Verlauf des Phasenoffsets des in der 5 betrachteten Symbols über dem Zeitversatz nach der Matched Filterung und der Multiplikation mit dem konjugiert komplexen des Referenzsymbols,
• 7 eine Darstellung eines MSK-Basisband-Signal für drei Symbole, wobei das letzte Symbol negativ gemappt ist,
• 8 einen Verlauf der Symbolamplitude aus 7 nach der Matched Filterung über dem Zeitversatz,
• 9 einen Verlauf des Phasenoffsets des in der 8 betrachteten Symbols über dem Zeitversatz nach der Matched Filterung und der Multiplikation mit dem konjugiert komplexen des Referenzsymbols,
• 10 eine schematische Darstellung eines Kommunikationssystem mit einem Sender und einem Empfänger,
• 11 eine schematische Darstellung eines Beispiels einer verwendeten Modulation und
• 12 eine Verdeutlichung einer Interpolation durch ein Polynom zweiten Grades.

Specifically, there are a variety of ways to design and develop the transmitter, the receiver, the system and the corresponding procedures. Reference is made on the one hand to the claims, on the other hand to the following description of embodiments in conjunction with the drawings. Show it:

• 1 a schematic representation of a signal processing for time and frequency estimation,
• 2 a representation of an MSK baseband signal for three positively mapped symbols,
• 3 a representation of an MSK baseband signal at ideal time offset,
• 4 a representation of an MSK baseband signal with a negative time offset,
• 5 a progression of the symbol amplitude after the matched filtering over the time offset,
• 6 a course of the phase offset of the in 5 considered symbol over the time offset after the matched filtering and the multiplication with the conjugate complex of the reference symbol,
• 7 a representation of an MSK baseband signal for three symbols, the last symbol being mapped negative,
• 8th a course of the symbol amplitude 7 after the matched filtering over the time offset,
• 9 a course of the phase offset of the in 8th considered symbol over the time offset after the matched filtering and the multiplication with the conjugate complex of the reference symbol,
• 10 a schematic representation of a communication system with a transmitter and a receiver,
• 11 a schematic representation of an example of a modulation used and
• 12 an illustration of an interpolation by a second degree polynomial.

When telegram splitting (see eg DE 10 2011 082 098 A1 ) data to be transmitted are not sent in a data packet, but rather several data packets are generated which may be transmitted at different frequencies and at different times. From a telegram thus several telegram fragments are generated. Each telegram fragment has a pilot sequence that serves to synchronize the sender and the receiver. The pilot sequences are identical in one embodiment and different in another embodiment.

A pilot sequence generally consists of a number L of modulation symbols (also referred to below as pilot symbols). It is usually transmitted compactly either at the beginning (preamble) or in the middle (midamble) of the telegram or the telegram fragment. However, it can also be split into two or more segments between which data symbols are transmitted. It is common practice to extract the pilot symbols from the same modulation alphabet as the data symbols (eg, multiple phase-shift keying, M-PSK, or M-ary quadrature amplitude modulation, M-QAM). The pilot symbols are known in advance to the receiver or are appropriately filed, for example.

In receivers, it is customary to downsample the received signal to the baseband after band-pass filtering and to sample and quantize it with equidistant time using an analog-to-digital converter (ADC). Each sample is complex-valued and consists of a real and an imaginary part. The sampling takes place at least in the symbol clock or a multiple thereof (so-called oversampling).

For the time estimation and frequency estimation required for the synchronization, several methods are known, which will be described below.

DFT method:

In [9] a method is described which is also suitable for large frequency deposits. The frequency deviation is the frequency difference between the carrier frequency of the transmission signal and the center frequency of the reception filter. The main signal processing steps are in 1 illustrated.

Where T is the symbol spacing or 1 / T is the symbol rate. N is the oversampling factor and k * T / N denotes the timing of the kth sample. The pilot symbols are named a [0], a [1], ..., a [L-1], where a [0] is transmitted first and a [L-1] last. The superscript * indicates that the conjugate complex value is to be used. The delay ^element is denoted by z ^-N , which is the delay by N samples. Furthermore, W is the window length for maximum value search in number of samples.

Time variables in parentheses are always time-continuous, z. B. r (t) denotes the continuous-time received signal. In contrast, time variables in square brackets are time-discrete and usually represent a consecutive numbering of samples. B. x [k] the k-th value of the (time-continuous) signal x (t) after the receive filter.

The signal is sampled and quantized equidistantly with N values per symbol after the receive filter which generates the signal x (t) from the signal r (t). At each time point k, L samples are taken at symbol spacing (ie every Nth sample) and multiplied first by the L conjugate complex pilot symbols. These become with the samples of a complex exponential oscillation multiplied and then added up. The last process is performed several times for different frequencies of this vibration, which are called frequency hypotheses. For equidistant frequency hypotheses this corresponds to the discrete Fourier transform (DFT) of the L products x [k] a * [L-1], x [kN] a * [L-2] to x [k- (L-1) N ] a * [0].

The DFT can be carried out particularly efficiently with the well-known Fast Fourier Transform (FFT) algorithm, provided that L is a power of two. If L is not a power of two, round up the DFT length to the next higher power of two and add L0 values to the many zeros so that an FFT can be applied. To increase the accuracy of the frequency estimation, the L FFT input values can be supplemented by an arbitrary number of further zeroes.

Each frequency hypothesis provides a complex value called d _i [k], which is called a decision variable. The index i refers to the ith frequency. For each time step k, the maximum of the amount | d _i [k] | determined over all frequency indices i. The maximum frequency index is denoted by i ₀ . If this maximum lies above a decision threshold d _thr , then a pilot sequence (alternatively also referred to as a training sequence) is considered recognized. The associated time index is denoted by k '. In the positive case that the maximum is above the decision threshold, k 'is set equal to k. In the negative case, k is increased (k becomes k + 1, 1 ). The comparison with the decision threshold is in each case optional.

It is known that a more detailed analysis of the received signal is necessary for more accurate time lag estimation.

Further processing is the following:

The decision variables are analyzed at time k 'and for each time following k', and the absolute value maximum is determined within a time window of given duration. The time index belonging to this maximum is denoted by k ₀ .

The frequency belonging to the index i ₀ [k ₀ ] already represents a rough estimate of the frequency deviation. It is denoted by ν ₀ and is given by $$\nu T=\frac{i_0}{N_{\text{DFT}}}-\{\begin{array}{cc}0& \text{For}{\mathrm{<figure-callout\; id="0"\; label="i"\; filenames="DE102017012190A1\_0027.png,DE102017012190A1\_0029.png"\; state="\{\{state\}\}">i</figure-callout>}}_0<N_{\text{DFT}}/2\\ 1& \text{For}{\mathrm{<figure-callout\; id="0"\; label="i"\; filenames="DE102017012190A1\_0027.png,DE102017012190A1\_0029.png"\; state="\{\{state\}\}">i</figure-callout>}}_0\ge N_{\text{DFT}}/2\end{array}$$

In the case of additive Gaussian perturbations, the DFT method is optimal in terms of the maximum likelihood estimation. It is applicable to frequency stores up to almost half the symbol rate. The estimation accuracy is essentially limited by the oversampling factor N and the DFT length NDFT. For large N and large NDFT, the mean square estimation error for both time and frequency comes close to the theoretically achievable limit (Cramer-Rao barrier). The method is applicable to any pilot sequences.

Frequency estimation according to Luise and Reggiannini:

mit $$\text{z}\left[\text{l}\right]=\text{x}\left[\text{k}-\left(\text{L}-1-\text{l}\right)\text{N}\right]\text{a*}\left[\text{l}\right]$$

The estimator according to Luise and Reggiannini is based on the following values:

With $$\text{z}\left[\text{l}\right]=\text{x}\left[\text{k}-\left(\text{L}-1-\text{l}\right)\text{N}\right]\text{a *}\left[\text{l}\right]$$

The frequency estimate results from: $$\widehat{\nu }T=\frac{1}{\pi \left(\mathrm{\Lambda }+1\right)}\text{bad}\left\{{\displaystyle \underset{\lambda =1}{\overset{\mathrm{\Lambda }}{\Sigma }}R\left[\lambda \right]}\right\}$$

• • Er ist innerhalb des nutzbaren Schätzbereichs auch für niedriges E_S/N₀ - also Energie pro Symbol als Maß für die Signal-zu-Rauschen-Verhältnis - als spektrale Rauschleistungsdichte erwartungstreu.
• • Für Λ = L/2 und E_S/N₀ > 0 dB liegt der Schätzer dicht an der der Cramer-Rao-Schranke und für die Frequenzablage Null genau auf der Cramer-Rao-Schranke. Man kann ihn als optimal bezeichnen.
• • Der Schätzbereich ist beschränkt auf: $\left|\nu T\right|\le \frac{\mathrm{0,85}}{\mathrm{<figure-callout\; id="1"\; label="\Lambda \; +"\; filenames="DE102017012190A1\_0027.png,DE102017012190A1\_0036.png"\; state="\{\{state\}\}">\Lambda </figure-callout>}+1}.$
  

The estimator has the following properties:

• • Within the usable estimation range it is also suitable for low E _S / N ₀ - ie energy per symbol as a measure of the signal-to-noise ratio - as spectral noise power density.
• • For Λ = L / 2 and E _S / N ₀ > 0 dB the estimator is close to that of the Cramer-Rao barrier and for frequency offset zero it is exactly on the Cramer-Rao barrier. You can call it optimal.
• • The estimation range is limited to: $\left|\nu T\right|\le \frac{0.85}{\mathrm{\Lambda }+1},$
  

A disadvantage is that sufficiently accurate time synchronization is required before use. Another disadvantage is that the method is not suitable for large frequency shelves because of the limited estimation range.

The phase estimate can be improved as described below.

For the data-aided phase offset estimation in coherent receivers, the synchronization symbols which are present in a transmitted packet are usually used. So the pilot symbols of the pilot sequences are used. The phases of the received symbols are compared with the expected phases (reference symbols). The difference between the two gives the phase offset. For noise suppression, for example, an averaging over a plurality of symbols is performed.

An example of such a phase estimate is the maximum likelihood estimator (see [6]).

This estimator will yield useful results if the exact time of transmission is known. However, this is usually determined in a previous estimate, where noise and other effects may cause discrepancies. In addition, due to limitations in computational power, it is not always possible to perform a reasonably accurate time estimate.

Thus, the receive symbols include a residual time offset that enters and degrades the phase estimate. It results from the residual time offset or generally time offset a phase error, which is added to the actually interesting phase between the transmission frequency of the transmitter and the reception frequency of the receiver and therefore affects the evaluation.

Embodiments describing an improvement of the phase estimation will be described below. The embodiments also apply to an improved frequency estimate, in the case where the frequency estimate is based on phase differences of adjacent symbols.

In symbol recovery (eg, by matched filtering and subsequent subsampling), a portion of at least one adjacent symbol is also introduced into the result by a time offset. This phenomenon is described below by means of an MSK modulation. The mapping serves, for example, the pilot sequence bits to the actual symbols of the pilot sequences.

To simplify the illustration, the following graphics each contain only three symbols. In this case, the middle symbol represents the symbol to be examined and the other two represent the chronologically preceding or succeeding symbol.

2 shows an MSK baseband signal with three symbols. In this case, both the symbol to be examined and the previous and following symbols have been mapped with positive amplitude. It is therefore a middle symbol and two flanking symbols. The curve a shows the real part and the curves b show the imaginary part of the signal. Plotted on the y-axis is the amplitude versus time at sampling times on the x-axis.

In the following, the influence of the phase for the middle symbol is examined, which is transmitted on the real part. The other two flanking symbols (the previous and following symbols) will be according to the MSK rule as an example of the mapping in the generation of the symbols to be transmitted on the imaginary part.

The symbol is recovered in the receiver using a matched filter, which is multiplied by the signal and then summed over the entire symbol. The 3 shows the length of the matched filter (stronger curve c). The filter extends over the entire middle symbol. In 3 Thus, the ideal case is shown in which no time offset occurs.

Due to the special MSK modulation, a so-called ISI (Intersymbol Interference, so-called symbol cross talk, see [7]) is inserted in the matched filtering for the reconstruction of the symbols. The symbol crosstalk is known and can be taken into account in the calculation of the phase differences.

For symbol recovery, the data is cut out within the range shown and multiplied by the matched filter (optimal filter) or an approximation. The symbol results from integration (in the time-continuous case) or summation (in the discrete-time case).

Will the reconstructed icon turn off 3 compared with the transmit symbol (or a reference symbol present to the receiver), it shows that there is no phase offset between the two symbols.

However, if a time offset occurs, the window for the matched filter is moved. The 4 shows this for a negative time offset where the correct time is after the assumed time. The start of the symbol is thus assumed too early. For the phase determination thus results from the time offset a phase error as an additional error in the actual determination of the phase.

Due to the time offset, more energy of the preceding flanking symbol and less of the mean symbol of interest flows into the reconstruction of the middle symbol. The value thus deviates from the expected setpoint. However, if the received value deviates from the expected one, this deviation will result in an error in the phase estimate.

Similarly, this applies to a positive time offset in which the actual symbol begins before the assumed time. This increases the influence, however, of the flanking symbol following the middle symbol.

A history of the results of symbol reconstruction at different time offsets shows 5 , The center represents the ideal point in time. The amplitude is plotted on the y-axis with respect to the time offset (or alternatively referred to as the timing error) in symbol lengths. Plotted are the real part R and the imaginary part I.

5 shows that at the ideal time the influence of the neighboring symbols (thus the flanking symbols in the example of the 2 ) is lowest. With increasing time offset, the influence of the neighboring symbols increases, ie in this example with MSK modulation the amplitude of the imaginary part increases.

If the received symbol (in this case the middle symbol) is multiplied by the conjugate complex of the transmitted symbol (ie the reference symbol or the corresponding symbol of the reference sequence), the phase offset between the reference symbol and the considered mean symbol of the combination of three is obtained Symbols of the pilot sequence of the received signal.

Shows the phase offset 6 for that 5 associated symbol above the time offset. In this symbol constellation, the phase offset - ie the resulting phase error due to the time offset - is always positive. However, the height depends on the amount of time offset.

The previous explanations show that the result of the matched filtering and thus also the phase error in time offsets depends on the preceding and following symbols, ie the symbols flanking in the example the respectively considered mean symbols.

To fully elucidate this, the result of matched filtering was time-shifted again for another symbol constellation. The symbol to be considered has also been mapped again with a positive amplitude, but the two flanking symbols have a different one Amplitude. The complex baseband signal and the result of matched filtering with different time offsets are in the 7 and the 8th shown.

The 7 shows the amplitude of the three symbols b, a, b versus time in sampling rates. The two flanking symbols b include the middle symbol a. In this MSK signal in the chosen constellation, no symbol crosstalk (ISI) occurs at the ideal sampling instant through the flanking symbols with the middle symbol.

The 8th shows the amplitude of the middle symbol after the matched filtering as a function of the time offset.

If the receive symbol after the matched filtering is the same as for the 6 multiplied by the complex conjugate value of the transmitted symbol, the phase offset between the reference symbol and the received symbol is obtained.

Shows the phase offset 9 for the in 8th considered middle symbol over the time offset. Compared to 6 the course of the phase offset is no longer only positive for all possible time offsets. For negative time offsets the phase offset is positive and for positive time offsets it changes sign and becomes negative.

Overall, the phase offset is dependent on the symbols that flank the respective evaluated symbol.

Therefore, the symbols are selected such that the phase errors resulting in each case as a result of a time offset in the evaluation of the individual symbols compensate each other when averaging over the affected symbols - be it from one signal or multiple signals.

The 10 shows a system 50 with a transmitter 1 and a receiver 10 ,

The transmitter 1 has a signal generator 2 and a signal output device 3 , The signal generator 2 generated from data that the sender 1 has to transmit the signals to be sent out. The data are, for example, sensor data or status data of the transmitter 1 even.

In the exemplary embodiment shown, the telegram splitting is applied, so that the data to be output are distributed to at least two signals, which can also be referred to as telegram fragments. The individual telegram fragments each have a pilot sequence, that of the signal generator 2 provided. The provision for the individual signals to be transmitted consists in one embodiment in that the signal generator 2 to a data store 4 accesses in which the data for the appropriate pilot sequence are stored. The signal output device 3 sends out the individual telegram fragments.

The individual telegram fragments are received by the receiver 10 received and processed. For processing is a synchronization between transmitter 1 and receiver 10 required, for which the synchronization device 11 is available. The synchronization are each the pilot sequences with their pilot symbols.

Synchronization is required in terms of time. This refers to the estimation of the timing of the received signal and the associated optimum timing for sampling the signal. For this synchronization is the synchronization device 11 with a scanning device 13 connected. The times of sampling can not be influenced in the rule. Rather, the time is necessary to reconstruct the symbols from the signal, which is generally oversampled, or else to perform an interpolation.

Another synchronization refers to the frequency in the example shown. Relevant here are the carrier frequency with which the signals from the transmitter 1 are emitted, and the center frequency of the filter device 14 , with which the received signals are filtered. Alternatively, the signals are frequency shifted after reception in front of the filter. The difference between the two frequencies is referred to as frequency offset. For the frequency synchronization here is the filter device 14 with the synchronization device 11 connected.

The frequency synchronization is followed by - in the case of a coherent demodulation or decoding - still a phase synchronization. For this synchronization, the signal evaluation device will be described below 12 described in more detail, the corresponding data for synchronization to the synchronization device 11 transmitted.

For determining the phase, it is provided that each pilot symbol of the pilot sequence of the received signal is compared with the associated reference symbol of a reference sequence. The reference sequence is the same as the pilot sequence used by the sender 1 used for the generation of the signal or has been inserted into the signal. If a phase value has been determined for each pilot symbol, then a total value z. B. by an average, generated over the individual phase values. The reference sequences are here in a data memory 15 deposited.

However, as previously explained, a timing error affects the window of the filter device 14 and the actual beginning of the symbol detrimental to the determination of the phase.

By averaging over the evaluation of several symbols for noise suppression, an averaging over the phase value errors is also performed. Therefore, it is provided that the mean phase error is used for all pilot symbols in the synchronization. So that the average error in the averaging over the individual phase values ideally results in zero or at least becomes very small, the dependence of the phase error of a symbol on the preceding and following symbols is taken into account on the basis of the above investigations. The symbols are thus selected such that the phase errors due to time offset just compensate each other when averaging over the individual values of the phases, which are generated per symbol.

Since several pilot symbols are transmitted one after the other, the previous and following symbols (that is, the symbols used in the example of FIG 2 flanking a mean or evaluated symbol) or they are known to the receiver. In order to compensate for the phase error by the individual pilot symbols as a whole, for each symbol on which a phase error can occur, a second is transmitted which has the opposite error (with the same time offset). This applies here to the symbols of a signal carrying a pilot sequence. In an alternative embodiment, the phase errors average over the partial pilot sequences a plurality of signals, which are in particular telegram fragments.

In one embodiment, it is therefore provided that the length of the pilot sequence has a multiple of the length of two, so that an even number of additions for the averaging arises.

The effect is explained using an example.

Is the sequence off 2 part of the pilot sequence, a positive phase offset is generated at a time offset that applies to both positive and negative time offsets. In order to correct this offset, a symbol must also be transmitted in which the error at the same level indicates a negative phase error.

The 11 shows the mapping rule of MSK modulation. Shown here are the possible constellation points of the MSK with precoding (in MATLAB also known as non-diff MSK).

The symbols to be transmitted are hereby divided into groups of four symbols, the first symbol being transmitted at time T ₀ . Similarly, at time T0, for a binary zero, the constellation point is +1 + 0j, and for a binary one, the constellation point is -1 + 0j. For the following symbol the time T ₀ + ΔT is selected. The constellation points thus result in 0 + 1j (binary one) and 0 - 1j (binary zero). For the two following points in time, the calculation of the constellation points takes place in the same way. After four symbols have been mapped to the constellation points, the time T _{0 is} started again.

For a pilot sequence length of eight symbols and the previously described MSK mapping rule, the following sequences yield both a good autocorrelation and a near-zero phase error due to a skew. Consecutive number Sequence of symbols annotation 0 [0, 1, 0, 0, 0, 0, 1, 0] 1 [1, 0, 1, 1, 1, 1, 0, 1] Inverted or mirrored sequence 0. 2 [0, 0, 0, 1, 0, 1, 1, 1] 3 [1, 1, 1, 0, 1, 0, 0, 0] Inverted or mirrored sequence 2.

Therefore, the pilot sequence with which the transmitter 1 sends out the signals defined such that the sum of the phase offsets is minimized at a time shift.

For a pilot sequence length of twelve symbols and the previously described MSK mapping rule, the following sequences were found, which have both a good autocorrelation and a near-zero phase error at time offset. Consecutive number Sequence of symbols in bits | ε _ν | Max 0 [0, 0, 0, 0, 0, 1, 1, 0, 1, 0, 1, 1] 0.0132892511307 1 [0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 1, 1] 0.00604862976372 2 [0, 0, 0, 1, 0, 1, 0, 0, 1, 1, 1, 1] 0.00669831471134 3 [0, 0, 0, 1, 0, 1, 1, 1, 1, 0, 1, 1] 0.00214046117234 4 [0, 0, 0, 1, 1, 0, 1, 0, 1, 1, 1, 1] 0.00228803319793 5 [0, 1, 0, 0, 0, 0, 1, 0, 1, 1, 1, 0] 0.00214191618191 6 [0, 1, 0, 0, 1, 1, 1, 1, 1, 0, 1, 0] 0.00228803319793 7 [0, 1, 0, 1, 0, 0, 1, 1, 1, 1, 1, 0] 0.0132920410548 8th [0, 1, 0, 1, 1, 1, 1, 1, 0, 0, 1, 0] 0.00228488288132 9 [0, 1, 1, 1, 0, 1, 0, 0, 0, 0, 1, 0] 0.00214482669223 10 [0, 1, 1, 1, 1, 0, 1, 0, 0, 0, 1, 0] 0.00604466832967 11 [1, 0, 0, 0, 0, 1, 0, 1, 1, 1, 0, 1] 0.00604862889634 12 [1, 0, 1, 0, 0, 0, 0, 0, 1, 1, 0, 1] 0.00229275981363 13 [1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 1] 0.0089182616364 14 [1, 0, 1, 0, 1, 1, 0, 0, 0, 0, 0, 1] 0.0132892511307 15 [1, 0, 1, 1, 0, 0, 0, 0, 0, 1, 0, 1] 0.00229275939358 16 [1, 0, 1, 1, 1, 0, 1, 0, 0, 0, 0, 1] 0.0060426888597 17 [1, 0, 1, 1, 1, 1, 1, 0, 0, 1, 0, 1] 0.00670003795849 18 [1, 1, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0] 0.00604466832967 19 [1, 1, 0, 1, 1, 1, 1, 0, 1, 0, 0, 0] 0.00214046162904 20 [1, 1, 1, 0, 0, 1, 0, 1, 0, 0, 0, 0] 0.00228645779938 21 [1, 1, 1, 0, 1, 0, 0, 0, 0, 1, 0, 0] 0.00214191618191 22 [1, 1, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0] 0.00229295513208 23 [1, 1, 1, 0, 1, 0, 1, 1, 0, 0, 0, 0] 0.00669917633491 24 [1, 1, 1, 0, 1, 1, 1, 1, 0, 1, 0, 0] 0.0060426888597 25 [1, 1, 1, 1, 1, 0, 0, 1, 0, 1, 0, 0] 0.0132808813584 26 [1, 1, 1, 1, 1, 0, 1, 0, 1, 1, 0, 0] 0.00855923745514

The zeros and ones are in each case the pilot sequence bits, which result in the symbols of the pilot sequence or the partial pilot sequence by a corresponding mapping.

The value | ε _ν | _{max is} the maximum systematic frequency estimation using a correlation taking into account a sample time error of -0.25T to + 0.25T and a frequency offset of vT of the received signal between -0.05 to +0.05.

The 12 shows a polynomial of the second degree of the form y (x) = y ₀ -c (xx ₀ ) ² v, as has been described in embodiments for improving the time and / or frequency estimation by means of interpolation.

Although some aspects have been described in the context of a device, it will be understood that these aspects also constitute a description of the corresponding method, so that a block or a component of a device is also to be understood as a corresponding method step or as a feature of a method step. Similarly, aspects described in connection with or as a method step also represent a description of a corresponding block or detail or feature of a corresponding device. Some or all of the method steps may be performed by a hardware device (or using a hardware device). Apparatus), such as a microprocessor, a programmable computer or an electronic circuit. In some embodiments, some or more of the most important method steps may be performed by such an apparatus.

Depending on particular implementation requirements, embodiments of the invention may be implemented in hardware or in software, or at least partially in hardware, or at least partially in software. The implementation may be performed using a digital storage medium such as a floppy disk, a DVD, a BluRay disc, a CD, a ROM, a PROM, an EPROM, an EEPROM or FLASH memory, a hard disk, or other magnetic or optical Memory are stored on the electronically readable control signals are stored, which can cooperate with a programmable computer system or cooperate such that the respective method is performed. Therefore, the digital storage medium can be computer readable.

Thus, some embodiments according to the invention include a data carrier having electronically readable control signals capable of interacting with a programmable computer system such that one of the methods described herein is performed.

In general, embodiments of the present invention may be implemented as a computer program product having a program code, wherein the program code is operable to perform one of the methods when the computer program product runs on a computer.

The program code can also be stored, for example, on a machine-readable carrier.

Other embodiments include the computer program for performing any of the methods described herein, wherein the computer program is stored on a machine-readable medium. In other words, an embodiment of the method according to the invention is thus a computer program which has a program code for performing one of the methods described herein when the computer program runs on a computer.

A further embodiment of the inventive method is thus a data carrier (or a digital storage medium or a computer-readable medium) on which the computer program is recorded for carrying out one of the methods described herein. The data carrier or the digital storage medium or the computer-readable medium are typically tangible and / or non-volatile.

A further embodiment of the method according to the invention is thus a data stream or a sequence of signals, which represent the computer program for performing one of the methods described herein. The data stream or the sequence of signals may be configured, for example, to be transferred via a data communication connection, for example via the Internet.

Another embodiment includes a processing device, such as a computer or a programmable logic device, that is configured or adapted to perform one of the methods described herein.

Another embodiment includes a computer on which the computer program is installed to perform one of the methods described herein.

Another embodiment according to the invention comprises a device or system adapted to transmit a computer program for performing at least one of the methods described herein to a receiver. The transmission can be done for example electronically or optically. The receiver may be, for example, a computer, a mobile device, a storage device or a similar device. For example, the device or system may include a file server for transmitting the computer program to the recipient.

In some embodiments, a programmable logic device (eg, a field programmable gate array, an FPGA) may be used to perform some or all of the functionality of the methods described herein. In some embodiments, a field programmable gate array may cooperate with a microprocessor to perform one of the methods described herein. In general, in some embodiments, the methods are performed by any hardware device. This may be a universal hardware such as a computer processor (CPU) or hardware specific to the process, such as an ASIC or, for example, a microprocessor, e.g. In the form of an ARM architecture.

The embodiments described above are merely illustrative of the principles of the present invention. It will be understood that modifications and variations of the arrangements and details described herein will be apparent to others of ordinary skill in the art. Therefore, it is intended that the invention be limited only by the scope of the appended claims and not by the specific details presented in the description and explanation of the embodiments herein.

references

1. [1] ZY Choi and YH Lee, "Frame synchronization in the presence of frequency offset," Communications, IEEE Transactions on, vol. 50, no. 7, pp. 1062-1065, 2002 ,
2. [2] Sust, MK; Businessman, RF; Molitor, F.; Bjornstrom, GA: Rapid acquisition concept for voice activated CDMA communication. In: IEEE Global Telecommunications Conference, 1990 Vol. 3, 1990, p. 1820 # 1826
3. [3] International Patent Application "Optimized Preamble and Methods for Interference Robust Packet Detection for Telemetry Applications" (PCT / EP2016 / 057014)
4. [4] G. Kilian, H. Petkov, R. Psiuk, H. Lieske, F. Beer, J. Robert, and A. Heuberger, "Improved coverage for low-power telemetry systems using telegram splitting," in Proceedings of 2013 European Conference on Smart Objects, Systems and Technologies (SmartSysTech), 2013
5. [5] G. Kilian, M. Breiling, HH Petkov, H. Lieske, F. Beer, J. Robert, and A. Heuberger, "Increasing Transmission Reliability for Telemetry Systems Using Telegram Splitting," IEEE Transactions on Communications, vol. 63, no. 3, pp. 949-961, Mar. 2015 ,
6. [6] Wolfgang Koch, Script for the Seminar on Receiver Synchronization at Fraunhofer IIS, 10.06.2015 - 15.06.2015
7. [7] Uwe Lambrette, Ralf Mehlan and Heinrich Meyr, Comparison of Demodulation Techniques for MSK, RWTH Aachen University, https://www.ice.rwthaachen.de/fileadmin/publications/Lambrette95TIRR.pdf, last retrieved: 19.09.2016
8. [8th] Kay, Steven M: Fundamentals of Statistical Signal Processing: Detection theory. Upper Saddle River, NJ: Prentice Hall PTR, 1998. ISBN 9780135041352
9. [9] Umberto Mengali, Aldo N. D'Andrea: "Synchronization Techniques for Digital Receivers" Plenary Press, 1997, ISBN 0 - 306 - 45725 -3
10. [10] Walter Kellermann: "Digital Signal Processing", lecture notes from WS 2016 / 17 , Chair for Multimedia Communications and Signal Processing (LMS) at the Friedrich-Alexander-University Erlangen-Nürnberg.
11. [11] Steven M. Kay: "Fundamentals of Statistical Signal Processing - Vol. 2: Detection Theory", Prentice Hall, 1998, ISBN: 0-13-345711-7
12. [12] ZY Choi and YH Lee, "Frame synchronization in the presence of frequency offset", IEEE Transactions on Communications, vol. 50, no. 7, pp. 1062-1065, 2002 ,

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102011082098 A1 [0003, 0165]

Cited non-patent literature

• Z.Y. Choi and Y.H. Lee, "Frame synchronization in the presence of frequency offset," Communications, IEEE Transactions on, vol. 50, no. 7, pp. 1062-1065, 2002 [0247]
• Sust, M.K. ; Kaufmann, R. F.; Molitor, F.; Bjornstrom, G.A .: Rapid acquisition concept for voice activated CDMA communication. In: IEEE Global Telecommunications Conference, 1990 Vol. 3, 1990, p. 1820 # 1826 [0247]
• G. Kilian, H. Petkov, R. Psiuk, H. Lieske, F. Beer, J. Robert, and A. Heuberger, "Improved coverage for low-power telemetry systems using telegram splitting," in Proceedings of 2013 European Conference on Smart Objects, Systems and Technologies (SmartSysTech), 2013 [0247]
• G. Kilian, M. Breiling, H.H. Petkov, H. Lieske, F. Beer, J. Robert, and A. Heuberger, "Increasing Transmission Reliability for Telemetry Systems Using Telegram Splitting," IEEE Transactions on Communications, vol. 63, no. 3, pp. 949-961, Mar. 2015 [0247]
• Kay, Steven M: Fundamentals of Statistical Signal Processing: Detection theory. Upper Saddle River, NJ: Prentice Hall PTR, 1998. ISBN 9780135041352 [0247]
• Steven M. Kay: "Fundamentals of Statistical Signal Processing - Vol. 2: Detection Theory", Prentice Hall, 1998, ISBN: 0-13-345711-7 [0247]
• Z. Y. Choi and Y.H. Lee, "Frame synchronization in the presence of frequency offset", IEEE Transactions on Communications, vol. 50, no. 7, pp. 1062-1065, 2002 [0247]

Claims (36)

Receiver (10), wherein the receiver (10) is configured to receive at least one signal transmitted by a transmitter (1), the receiver (10) having a synchronization device (11), wherein the synchronization device (11) is designed in such a way, starting from the received signal to synchronize the receiver (10) with the transmitter (1), the receiver (10) having a signal evaluation device (12), wherein the signal evaluation device (12) determines data for the synchronization from the received signal and transmits it to the synchronization device (11) for the synchronization, wherein the signal evaluation device (12) in the evaluation of a pilot sequence or a partial pilot sequence of a received signal, a time offset between a reference time of transmission of the signal by the transmitter (1) and one for the evaluation of the reference time and / or estimated value, and wherein the signal evaluation device (12) accesses symbols of a time offset adapted reference sequence for the further evaluation of the pilot sequence, or wherein the signal evaluation device (12) for further evaluation of the partial pilot sequence on symbols of a part of a time offset adapted reference sequence or on accesses the time offset adapted portion of a reference sequence. Receiver (10) to Claim 1 in which the signal evaluation device (12) carries out the adaptation of the reference sequence or of the part of the reference sequence in that the signal evaluation device (12) shifts a known reference sequence or part of a known reference sequence in time by the determined time offset. Receiver (10) to Claim 1 wherein the signal evaluation device (12) performs the adaptation of the reference sequence or of the part of the reference sequence by the signal evaluation device (12) accessing a data memory (15) with corresponding reference sequences or parts of reference sequences. Receiver (10) according to one of Claims 1 to 3 wherein the receiver (10) comprises a filter device (14) and a scanning device (13). Method for synchronizing a receiver (10) with a transmitter (1), wherein at least one signal transmitted by the transmitter (1) is received by the receiver (10), wherein starting from a pilot sequence or a partial pilot sequence of the received signal, a synchronization of the receiver (10) with the transmitter (1) is carried out wherein a time offset between a reference time of a transmission of the signal by the transmitter (1) and a value assumed and / or estimated for the reference time is determined, and wherein a pilot sequence of the received signal is evaluated with symbols of a time offset adapted reference sequence, or wherein a partial pilot sequence of the received signal is evaluated with symbols of a portion of a time offset matched reference sequence or symbols of a time offset adapted portion of a reference sequence. Receiver (10), wherein the receiver (10) is configured to receive at least one of a transmitter (1) emitted signal, wherein the receiver (10) comprises a synchronization device (11), wherein the synchronization device (11) is configured to perform a synchronization of the receiver (10) with the transmitter (1) on the basis of the received signal, the receiver (10) having a signal evaluation device (12), wherein the signal evaluation device (12) determines data for the synchronization from the received signal and is transmitted to the synchronization device (11) for the synchronization, wherein the receiver (10) is configured in such a way to receive a plurality of telegram fragments transmitted by the transmitter (1), the telegram fragments each having a partial pilot sequence, wherein the telegram Fragments add up to a telegram containing data sent by the sender (1), wherein the telegram fragments are shorter than a single telegram having the transmitted data, wherein the sub-pilot sequences complement each other to a pilot sequence, and wherein the signal evaluating device (12) from the partial pilot sequences and using the DFT method, a value for determining a frequency difference between a transmission frequency of the transmitter (1) and a reception frequency of the receiver (10), the signal evaluation device (12) determining values of decision variables (d _i [k]) for each partial pilot sequence, the determined values of the decision variables (i.e. _i [k]) are combined with each other via the sub-pilot sequences and with the combined values a determination of a maximum value is performed. Receiver (10) to Claim 6 wherein the signal evaluation device (12) determines the values of the decision variables (d _i [k]) for each sub-pilot sequence by the signal evaluation device (12) for a plurality of frequencies of a complex exponential oscillation called frequency hypotheses multiplication values of a multiplication of samples of the respective part Pilot sequence with conjugate complex values of an equal number of reference symbols of a known reference sequence and with samples of the complex exponential oscillation and accumulates the multiplication values. Receiver (10) to Claim 6 or 7 in that the signal evaluation device (12) combines the values of the decision variables (d _i [k]) determined for the sub-pilot sequences together for the sub-pilot sequences by the signal evaluation device (12) determining the values of the values of the decision variables (d _i [k ]). Receiver (10) to Claim 6 or 7 wherein the signal evaluation device (12) combines the values of the decision variables (d _i [k]) determined for the sub-pilot sequences together for the sub-pilot sequences by the signal evaluation device (12) summing the magnitudes of a real part and an imaginary part of the values of the decision variable (d _i [k]). Receiver (10) to Claim 6 or 7 wherein the signal evaluation device (12) combines the values of the decision variables (d _i [k]) determined for the sub-pilot sequences together for the sub-pilot sequences by the signal evaluation device (12) calculating the absolute squares of the values of the decision variables (d _i [k ]). Receiver (10) to Claim 6 or 7 wherein the signal evaluator (12) combines the values of the decision variables (d _i [k]) determined for the sub-pilot sequences together for the sub-pilot sequences coherently, taking into account the magnitude and phase of the values of the decision variables (d _i [k]) , Receiver (10) according to one of Claims 6 to 11 in which the signal evaluation device (12) combines the determined values of the decision variables (d _i [k]) with one another using weighting factors. Receiver (10) according to one of Claims 6 to 11 , wherein the signal evaluation device (12) combines the determined values of the decision variables (d _i [k]) with each other using weighting factors relating in each case to the sub-pilot sequences. Receiver (10) to Claim 12 or 13 , wherein the signal evaluation device (12) determines the weighting factors based on a signal-to-noise ratio of the respective telegram fragment. Receiver (10) to Claim 14 wherein the signal evaluator (12) determines the weighting factors as being proportional to a root of the signal-to-noise ratio. Receiver (10) to Claim 14 , wherein the signal evaluation device (12) determines the weighting factors as proportional to a root of a quotient of the signal-to-noise ratio and a noise power of the respective telegram fragment. Receiver (10) to Claim 14 wherein the signal evaluation device (12) determines the weighting factors as a function of a computing power available to the signal evaluation device or as a function of a ratio of the signal-to-noise ratio relative to a predefinable relational value or as a function of an interference power either as proportional to a root from the Signal-to-noise ratio or proportional to a root of a quotient of the signal-to-noise ratio and a noise power of the respective telegram fragment determined. Receiver (10) according to one of Claims 1 to 4 or 6 to 17 wherein the receiver (10) is configured to receive a plurality of telegram fragments transmitted by the transmitter (1), the telegram fragments each having a partial pilot sequence, the telegram fragments complementing one another by a telegram the data transmitted to the transmitter (1), wherein the telegram fragments are shorter than a single telegram having the transmitted data, the partial pilot sequences complement each other to a pilot sequence, and wherein the signal evaluation device (12) starting from the partial pilot sequences and determining, using the DFT method, a value for a frequency difference between a transmission frequency of the transmitter (1) and a reception frequency of the receiver (10), in that the signal evaluation device (12) generates values of decision variables (d _i [k]) for each partial pilot sequence determined, the determined values of the decision variables (d _i [k]) combined with each other via the partial pilot sequences and d a combined maximum-value determination, wherein the signal evaluation device (12) determines a time estimate for a time offset between a reference time of transmission of the telegram fragment and a time taken for the evaluation of the telegram fragment for the reference time and / or estimated value, in that the signal evaluation device (12) determines a time offset for a time offset on the basis of a maximum value obtained by the determination of the maximum value and at least one value adjacent to a maximum value with respect to a time variable. Receiver (10) according to one of Claims 1 to 4 or 6 to 17 wherein the receiver (10) is configured to receive at least one telegram transmitted by the transmitter (1), the telegram having a pilot sequence, the signal evaluating device (12) deriving a value from the pilot sequence and using the DFT method for a frequency difference between a transmission frequency of the transmitter (1) and a reception frequency of the receiver (10), in which the pilot sequence signal evaluator (12) determines values of decision variables (d _i [k]), determines maximum value, wherein the signal evaluation device (12) performs a time estimation for a time offset between a reference time of transmission of the telegram and an accepted and / or estimated value for the evaluation of the telegram for the reference time by the signal evaluation device (12) starting from a through the determination of the maximum value obtained maximum value and mi At least one adjacent to a time variable to the maximum value value determines a time estimate for a time offset. Receiver (10) to Claim 18 or 19 in which the signal evaluation device (12) obtains the maximum value based on the determination of the maximum value and a positive comparison of the maximum value with a decision threshold. Receiver (10) according to one of Claims 18 to 20 wherein the signal evaluator (12) generates the time estimate from the maximum value and two adjacent values, and wherein the two adjacent values precede or follow the determined maximum value in terms of the time variable. Receiver (10) to Claim 21 in which the signal evaluation device (12) determines a polynomial for the maximum value and the two adjacent values, and wherein the signal evaluation device (12) determines the time estimated value from an extreme value associated with the polynomial. Receiver (10) to Claim 22 in which the signal evaluation device (12) carries out the interpolation with a second-degree polynomial. Receiver (30) to Claim 23 , wherein the signal evaluation device (12) performs the interpolation with a polynomial of the form: y (x) = y ₀ - c (xx ₀ ) ² , and wherein the free parameters yo, c and xo are determined on the basis of the maximum and the neighboring points. Receiver (10) according to one of Claims 1 to 4 or 6 to 24 . wherein the receiver (10) is configured in such a way to receive a plurality of telegram fragments transmitted by the transmitter (1), the telegram fragments each having a partial pilot sequence, the telegram fragments complementing one another by the telegram Transmitter (1) contains transmitted data, wherein the telegram fragments are shorter than a single telegram comprising the transmitted data, the sub-pilot sequences complement each other to a pilot sequence, and wherein the signal evaluation device (12) starting from the sub-pilot sequences and Application of the DFT method determines a value for a frequency difference between a transmission frequency of the transmitter (1) and a reception frequency of the receiver (10) by the signal evaluation device (12) for each partial pilot sequence values of decision variables (d _i [k]) determined , the determined values of the decision variables (d _i [k]) are combined with each other via the sub-pilot sequences and with the combined values a determination of a maximum value, wherein the signal evaluation device (12) performs a frequency estimate for the frequency difference by the signal evaluation device (12) starting from a maximum value obtained by the determination of the maximum value and at least one with respect to a frequency variable to the maximum value Value determined a frequency estimate. Receiver (10) according to one of Claims 1 to 4 or 6 to 24 wherein the receiver (10) is configured to receive at least one telegram transmitted by the transmitter (1), the telegram having a pilot sequence, the signal evaluating device (12) deriving a value from the pilot sequence and using the DFT method for a frequency difference between a transmission frequency of the transmitter (1) and a reception frequency of the receiver (10), in which the pilot sequence signal evaluator (12) determines values of decision variables (d _i [k]), determines maximum value, wherein the signal evaluation device (12) carries out a frequency estimation for the frequency difference by the signal evaluation device (12) determining a frequency estimated value based on a maximum value obtained by the determination of the maximum value and at least one value adjacent to the maximum value with respect to a frequency variable. Receiver (10) to Claim 25 or 26 wherein the signal evaluation device (12) obtains the maximum value from the maximum value and a positive comparison of the maximum value with a decision threshold. Receiver (10) according to one of Claims 25 to 27 wherein the signal evaluating device (12) generates the frequency estimate from the maximum value and two adjacent values, wherein the two adjacent values in terms of the frequency variable precede or follow the determined maximum value. Receiver (10) to Claim 28 wherein the signal evaluation device (12) determines a polynomial for the maximum value and the two adjacent values, and wherein the signal evaluation device (12) determines the frequency estimated value from an extreme value associated with the polynomial. Receiver (10) to Claim 29 in which the signal evaluation device (12) carries out the interpolation with a second-degree polynomial. Receiver (30) to Claim 30 , wherein the signal evaluation device (12) performs the interpolation with a polynomial of the form: y (x) = y ₀ - c (xx ₀ ) ² , and wherein the free parameters y ₀ , c and x ₀ determined based on the maximum and the neighboring points are. Receiver (10) according to one of Claims 18 to 31 wherein the signal evaluation device (12) determines the time estimation value and uses it for a new determination of the frequency difference by the signal evaluation device (12) in a re-determination of the values of the decision variable (d _i [k]) shifted by the time estimate samples used respective sub-pilot sequences or temporally shifts reference symbols of a reference sequence by the time estimate. Receiver (10) to Claim 32 wherein the signal evaluation device (12) performs an interpolation of the samples of the respective sub-pilot sequences for the re-determination of the frequency difference. Receiver (10) to Claim 32 or 33 wherein the signal evaluation device (12) performs a frequency difference estimation after the frequency difference has been re-determined by the signal evaluation device (12) starting from a maximum value obtained by the determination of the maximum value and a positive comparison with the decision threshold and at least one Frequency variable adjacent value determines a frequency estimate. A method for synchronizing a receiver (10) with a transmitter (1), wherein at least one of the transmitter (1) emitted signal from the receiver (10) is received, starting from a pilot sequence or a partial pilot sequence of the received signal Synchronization of the receiver (10) with the transmitter (1) is carried out, wherein by the receiver (10) a plurality of the transmitter (1) emitted telegram fragments are received, the telegram fragments each having a partial pilot sequence, wherein the Telegram fragments complement each other to form a telegram containing data transmitted by the transmitter (1), the telegram fragments being shorter than the telegram, the partial pilot sequences complementing each other to form a pilot sequence, starting from the partial pilot sequences Receiver (10) is synchronized with the transmitter (1), wherein starting from the partial pilot sequences and using the DFT method, a value for a frequency difference between a transmission frequency of the transmitter (1) and a reception frequency of the receiver (10) is determined by determining values of decision variables (d _i [k]) for each partial pilot sequence by determining the determined values of the decision variables (d _i [k ]) are combined with each other over all the sub-pilot sequences and a determination of a maximum value is carried out with the combined values. Computer program with a program code for carrying out the method according to Claim 5 or 35 ,

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