A communication transmitter for generating a periodic signal for channel

measurements

DESCRIPTION

The invention relates to a communication transmitter for generating a periodic signal for channel measurements. In particular, the invention relates to a communication transmitter generating a periodic signal upon the basis of predefined seed sequences.

BACKGROUND OF THE INVENTION

In communication technologies training signals are widely used for characterization of a transmission channel between a transmitter and a receiver. The structure and content of the training signals are predefined and are known to the transmitter and the receiver, which allows for an adaptation of the receiver to varying characteristics of the transmission channel

High Efficiency Short Training Field (HE-STF) is a periodic signal, based on which the receiver can accurately adjust the automatic gain control (AGC) of the channel. The periodic structure of the signal in the time domain allows the receiver to use a simple cross- correlation or auto-correlation detector to detect the signal and to perform the AGC. HE-STF signals are commonly used in orthogonal frequency-division multiplexing- (OFDM) or in orthogonal frequency-division multiplexing access- (OFDMA) based technologies in order to reduce the peak-to-average power ratio (PAPR).

The existing legacy short training fields according to the 802.1 1 standards such as

802.1 1 a/g/n/ac allow to lower the PAPR significantly. However, the recent implementations of the 802.1 1 ax standard, which uses OFDMA technology, introduce sequences that yield a PAPR low enough only on parts of the bandwidth. The remaining parts, however, yield a high PAPR, which may limit the performance of future deployments. The limitation of this solution is caused by using a single seed sequence for all bandwidths.

Even though the existing short training field based solution for the 802.1 1 ax standard described above already leads to a reduced PAPR for some bandwidth parts, there is still a need for a further improvement of HE-STF sequences. In particular, there is a need for improved seed sequences for derivation of the HE-STF sequences.

SUMMARY OF THE INVENTION

It is the object of the invention to provide seed sequences for generating a periodic signal with reduced PAPR.

This object is achieved by the features of the independent claims. Further implementation forms are apparent from the dependent claims, the description and the figures.

According to a first aspect, the invention relates to a communication transmitter for providing a periodic signal for channel measurements, in particular for channel gain measurements. The communication transmitter comprises a processor being configured to determine the periodic signal upon the basis of at least one of the following seed sequences:

a first seed sequence

M1=[1,-1, 1, 1, 1,-1,-1,-1,-1, 1,-1, 1, 1] for transmitting the periodic signal within a first bandwidth,

a second seed sequence

M2=[1, 1,-1,-1,-1, 1,-1, 1,-1,-1,-1,-1, 1,-1,-1,-1, 1,-1, 1, 1, 1, 1,-1,-1, 1,-1,-1,-1,-1,1] for transmitting the periodic signal within a second bandwidth, the second bandwidth comprising the first bandwidth,

a third seed sequence

M3_1=[-1,-1, 1, 1, 1,-1, 1, 1, 1,-1, 1,-1,-1,-1,-1, 1,-1,-1,-1, 1,-1, 1, 1, 1,-1,-1, 1,-1, 1,1] for transmitting the periodic signal within the third bandwidth, the third bandwidth comprising the second bandwidth or a fourth seed sequence

M3_2=[-1,-1, 1,-1, 1, 1,-1,-1, 1 , 1 , 1 , -1 , 1 , 1 , 1 , -1 , -1 , -1 , 1 , 1 , 1 , -1 , 1 , -1 , -1 , 1 , -1 , 1 , 1] for transmitting the periodic signal within the third bandwidth, the third bandwidth comprising the second bandwidth,

or one of the following further seed sequences M1a = [1, 1, 1, -1, 1, 1, -1];

M2a= [-1, 1, 1, 1, 1, -1];

M3a = [1, 1, -1, 1, -1, -1];

M4a = [1, -1, -1, -1];

M5a = [1, 1, 0, 1, -1];

M6a = [-1, 1,-1, -1];

M7a = [-1, -1, -1, 1, -1, 1, 1];

M8a = [1, 1, -1, -1, -1, 1, -1];

M9a = [-1, -1, 1]; and

M10a= [1, -1,-1, -1, -1, 1, -1].

Advantageously, applying different seed sequences for different bandwidths allows for a significant PAPR reduction.

In a first possible implementation form of the communication transmitter according to the first aspect, the processor is configured to determine the periodic signal for transmission within the third bandwidth upon the basis of the third seed sequence M3_1 , in particular for a lower portion of the third bandwidth, and the fourth seed sequence M3_2, in particular for an upper portion of the third bandwidth. Advantageously, the implementation form allows for estimation of a signal for channel measurements in case of a wider bandwidth.

In a second possible implementation form of the communication transmitter according to the first aspect, the processor is further configured to generate the periodic signal (HES1 , HES2, HES3, HES) from at least one of the seed sequences, upon the basis of one of the following formulas:

HES1 (-120:8:120) =[M1, -1, -1, 0, -1, +1, -fliplr(M1)]; HES2(-240:8:240=[M2, 0, -fliplr(M2)];

HES3(-496:8:496) =[M3_1 , 0, M3_2, +1 , +1 , 0, +1 , -1 , fliplr(M3_2), 0, fliplr(M3_1 )]; wherein fliplr denotes reversing the order of seed sequence entries, M1 , M2, M3_1 and M3_2 denoting seed sequences, in particular the seed sequences of the first aspect or HES(-120:8:1 20) = [M1 a, M2a, -M5a, M2a, -fliplr(Ml a)] ;

HES(-240:8:240) = [-fliplr(M1 a), -M3a, M4a, M3a, 0, M3a, 0, -M3a, 0, -M3a, M4a, - M3a, (M1 a) ] ; HES(-496:8:496) = [M8a, M3a, M4a, fliplr(M3a), M7a, 0, fliplr(M3a), fliplr(M1 a), - fliplr(M9a), M8a, fliplr(M3a), M5a, M3a, fliplr(M8a), -fliplr(M9a), fliplr(M8a), M2a, 0, M1 0a, fliplr(M3a), M4a, M3a, fliplr(M8a)]; wherein fliplr denotes reversing the order of seed sequence entries, and wherein M1 , M2, M3_1 and M3_2, and M1 a to M10a denote the seed sequences, and -1 20:8:1 20 denotes the subcarrier positions -1 20 to 1 20 with jumps of 8 positions for a 20MHz bandwidth, -240:8:240 denotes the subcarrier positions -240 to 240 with jumps of 8 positions for a 40MHz bandwidth and -496:8:496 denotes the subcarrier positions -496 to 496 with jumps of 8 positions for a 80MHz bandwidth.

Advantageously, the obtained periodic signals (HES1 , HES2, HES3, HES) for channel measurements lead to a PAPR reduction.

In a third possible implementation form of the communication transmitter according to the first aspect, the communication transmitter further comprises a memory being arranged to store the seed sequences, and wherein the processor is configured to retrieve the respective seed sequence from the memory to determine the periodic signal. In a fourth possible implementation form of the communication transmitter according to the first aspect, the communication transmitter further comprises a communication interface for transmitting the periodic signal according to a multicarrier transmission technology, in particular according to the OFDM transmission technology.

In a fifth possible implementation form of the communication transmitter according to the first aspect, the periodic signal is a High Efficiency Short Training Field signal (HE-STF).

In a sixth possible implementation form of the communication transmitter according to the first aspect, the first bandwidth is 20 MHz and/or the second bandwidth is 40 MHz and/or the wherein the third bandwidth is 80 MHz.

Advantageously, the implementation form can be applied within the 802.11 standard. According to a second aspect, the invention relates to a seed sequence for providing a periodic signal for channel measurements, in particular a High Efficiency Short Training Field signal for channel gain measurements. The seed sequence is one from one of the following seed sequences: a first seed sequence

M1=[1,-1, 1, 1, 1,-1,-1,-1,-1, 1,-1, 1, 1] for transmitting the periodic signal within a first bandwidth, a second seed sequence

M2=[1, 1,-1,-1,-1, 1,-1, 1,-1,-1,-1,-1, 1,-1,-1,-1, 1,-1, 1, 1, 1, 1,-1,-1, 1,-1,-1,-1,-1,1] for transmitting the periodic signal within a second bandwidth, the second bandwidth comprising the first bandwidth, a third seed sequence M3_1=[-1,-1, 1, 1, 1,-1, 1, 1, 1,-1, 1,-1,-1,-1,-1, 1,-1,-1,-1, 1,-1, 1, 1, 1,-1,-1, 1,-1, 1,1] for transmitting the periodic signal within the third bandwidth, the third bandwidth comprising the second bandwidth, or a fourth seed sequence

M3_2=[-1,-1, 1,-1, 1, 1,-1,-1, 1 , 1 , 1 , -1 , 1 , 1 , 1 , -1 , -1 , -1 , 1 , 1 , 1 , -1 , 1 , -1 , -1 , 1 , -1 , 1 , 1] for transmitting the periodic signal within the third bandwidth, the third bandwidth comprising the second bandwidth, or one of the following further seed sequences

M1a = [1, 1, 1, -1, 1, 1, -1];

M2a=[-1, 1, 1, 1, 1, -1];

M3a = [1, 1, -1, 1, -1, -1];

M4a = [1, -1, -1, -1];

M5a = [1, 1, 0, 1, -1];

M6a = [-1, 1,-1, -1];

M7a = [-1, -1, -1, 1, -1, 1, 1];

M8a = [1, 1, -1, -1, -1, 1, -1];

M9a = [-1, -1, 1];and

M10a= [1, -1,-1, -1, -1, 1, -1].

According to a third aspect, the invention relates to a High Efficiency Short Training Field signal (HES1 , HES2, HES3, HES), having one of the following structures:

HES1 (-120:8:120) =[M1, -1, -1, 0, -1, +1, -fliplr(M1)];

HES2(-240:8:240) =[M2, 0, -fliplr(M2)];

HES3(-496:8:496) =[M3_1, 0, M3_2, +1.+1, 0, +1, -1, fliplr(M3_2), 0, fliplr(M3_1)]; HES(-120:8:120) = [M1a, M2a, -M5a, M2a, -fliplr(Mla)];

HES(-240:8:240) = [-fliplr(M1 a), -M3a, M4a, M3a, 0, M3a, 0, -M3a, 0, -M3a, M4a, - M3a, (M1a)];

HES(-496:8:496) = [M8a, M3a, M4a, fliplr(M3a), M7a, 0, fliplr(M3a), fliplr(M1a), - fliplr(M9a), M8a, fliplr(M3a), M5a, M3a, fliplr(M8a), -fliplr(M9a), fliplr(M8a), M2a, 0, M10a, fliplr(M3a), M4a, M3a, fliplr(M8a)]; wherein fliplr denotes reversing the order of seed sequence entries, and wherein M1 , M2, M3_1 and M3_2 and M1ato M10a denote seed sequences, and -120:8:120 denotes the subcarrier positions -120 to 120 with jumps of 8 positions for a 20MHz bandwidth, - 240:8:240 denotes the subcarrier positions -240 to 240 with jumps of 8 positions for a 40MHz bandwidth and -496:8:496 denotes the subcarrier positions -496 to 496 with jumps of 8 positions for a 80MHz bandwidth.

According to a fourth aspect, the invention relates to a method for providing a periodic signal for channel measurements, in particular for channel gain measurements, the method comprising determining the periodic signal upon the basis of at least one of the following seed sequences: a first seed sequence

M1=[1,-1, 1, 1, 1,-1,-1,-1,-1, 1,-1, 1, 1] for transmitting the periodic signal within a first bandwidth,

a second seed sequence

M2=[1, 1,-1,-1,-1, 1,-1, 1,-1,-1,-1,-1, 1,-1,-1,-1, 1,-1, 1, 1, 1, 1,-1,-1, 1,-1,-1,-1,-1,1] for transmitting the periodic signal within a second bandwidth, the second bandwidth comprising the first bandwidth, a third seed sequence M3_1=[-1,-1, 1, 1, 1,-1, 1, 1, 1,-1, 1,-1,-1,-1,-1, 1,-1,-1,-1, 1,-1, 1, 1, 1,-1,-1, 1,-1, 1,1] for transmitting the periodic signal within the third bandwidth, the third bandwidth comprising the second bandwidth, or a fourth seed sequence

M3_2=[-1,-1, 1,-1, 1, 1,-1,-1, 1 , 1 , 1 , -1 , 1 , 1 , 1 , -1 , -1 , -1 , 1 , 1 , 1 , -1 , 1 , -1 , -1 , 1 , -1 , 1 , 1] for transmitting the periodic signal within the third bandwidth, the third bandwidth comprising the second bandwidth. or one of the following further seed sequences

M1a = [1, 1, 1, -1, 1, 1, -1];

M2a= [-1, 1, 1, 1, 1, -1];

M3a = [1, 1, -1, 1, -1, -1];

M4a = [1, -1, -1, -1];

M5a = [1, 1, 0, 1, -1];

M6a = [-1, 1,-1, -1];

M7a = [-1, -1, -1, 1, -1, 1, 1];

M8a = [1, 1, -1, -1, -1, 1, -1];

M9a = [-1, -1, 1]; and

M10a= [1, -1,-1, -1, -1, 1, -1].

In a first possible implementation form of the method for providing a periodic signal for channel measurements according to the fourth aspect of the invention, the method further comprises determining the periodic signal for transmission within the third bandwidth upon the basis of the third seed sequence M3_1 , in particular for a lower portion of the third bandwidth, and the fourth seed sequence M3_2, in particular for an upper portion of the third bandwidth. In a second possible implementation form of the method for providing a periodic signal for channel measurements according to the fourth aspect of the invention, the periodic signal, e.g. HES1 , HES2, HES3, is generated from at least one of the seed sequences, upon the basis of one of the following formulas:

HES1 (-1 20:8:1 20) =[M1 , -1 , -1 , 0, -1 , +1 , -fliplr(M1 )]; HES2(-240:8:240) =[M2, 0, -fliplr(M2)]; HES3(-496:8:496) =[M3_1 , 0, M3_2, +1 , +1 , 0, +1 , -1 , fliplr(M3_2), 0, fliplr(M3_1 )]; HES(-120:8:1 20) = [M1 a, M2a, -M5a, M2a, -fliplr(Ml a)] ;

HES(-240:8:240) = [-fliplr(M1 a), -M3a, M4a, M3a, 0, M3a, 0, -M3a, 0, -M3a, M4a, - M3a, (M1 a) ] ;

HES(-496:8:496) = [M8a, M3a, M4a, fliplr(M3a), M7a, 0, fliplr(M3a), fliplr(M1 a), - fliplr(M9a), M8a, fliplr(M3a), M5a, M3a, fliplr(M8a), -fliplr(M9a), fliplr(M8a), M2a, 0, M1 0a, fliplr(M3a), M4a, M3a, fliplr(M8a)]; wherein fliplr denotes reversing the order of seed sequence entries, and wherein M1 , M2, M3_1 and M3_2 and M1 a to M10a denote seed sequences, and -1 20:8:1 20 denotes the subcarrier positions -120 to 1 20 with jumps of 8 positions for a 20MHz bandwidth, - 240:8:240 denotes the subcarrier positions -240 to 240 with jumps of 8 positions for a 40MHz bandwidth and -496:8:496 denotes the subcarrier positions -496 to 496 with jumps of 8 positions for a 80MHz bandwidth.

In a third possible implementation form of the method for providing a periodic signal for channel measurements according to the fourth aspect of the invention, the method comprises determining the periodic signal for transmission within the third bandwidth upon the basis of the third seed sequence M3_1 , in particular for a lower portion of the third bandwidth, and the fourth seed sequence M3_2, in particular for an upper portion of the third bandwidth. In a fourth possible implementation form of the method for providing a periodic signal for channel measurements according to the fourth aspect of the invention, the method comprises transmitting the periodic signal according to a multicarrier transmission technology, in particular according to the OFDM transmission technology.

According to a fifth aspect, the invention relates to a computer program for performing the method of the fourth aspect as such or of anyone of the implementation forms thereof, when the computer program is executed on a computer. The invention can be implemented in hardware and/or software.

BRIEF DESCRIPTION OF EMBODIMENTS

Fig. 1 shows a schematic diagram illustrating a transmission of a periodic signal by a transmitter; and

Fig. 2 shows a schematic diagram of the communication transmitter.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

In the following detailed description, reference is made to the accompanying drawings, which form a part of the disclosure, and in which are shown, by way of illustration, specific aspects in which the present invention may be practiced. It is understood that other aspects may be utilized and structural or logical changes may be made without departing from the scope of the present invention. The following detailed description, therefore, is not to be taken in a limiting sense, as the scope of the present invention is defined by the appended claims.

For instance, it is understood that a disclosure in connection with a described method may also hold true for a corresponding device or system configured to perform the method and vice versa. For example, if a specific method step is described, a corresponding device may include a unit to perform the described method step, even if such unit is not explicitly described or illustrated in the figures. Further, it is understood that the features of the various exemplary aspects described herein may be combined with each other, unless specifically noted otherwise. Fig.1 shows a schematic diagram illustrating a communication transmitter 100 configured to generate a periodic signal 101 for channel measurements, in particular for channel gain measurements, according to an embodiment. The transmitter 100 is configured to operate at different bandwidths. Depending on the bandwidth, the periodic channel 101 is generated upon the base of the following sequences:

M1=[1,-1, 1, 1, 1,-1,-1,-1,-1, 1,-1, 1, 1];

M2=[1, 1,-1,-1,-1, 1,-1, 1,-1,-1,-1,-1, 1,-1,-1,-1, 1,-1, 1, 1, 1, 1,-1,-1, 1,-1,-1,-1,-1,1];

M3_1=[-1,-1, 1, 1, 1,-1, 1, 1, 1,-1, 1,-1,-1,-1,-1, 1,-1,-1,-1, 1,-1, 1, 1, 1,-1,-1, 1,-1,1,1]; M3_2=[-1,-1, 1,-1, 1, 1,-1,-1, 1 , 1 , 1 , -1 , 1 , 1 , 1 , -1 , -1 , -1 , 1 , 1 , 1 , -1 , 1 , -1 , -1 , 1 , -1 , 1 , 1]; or one of the following further seed sequences

M1a = [1, 1, 1, -1, 1, 1, -1];

M2a= [-1, 1, 1, 1, 1, -1];

M3a = [1, 1, -1, 1, -1, -1];

M4a = [1, -1, -1, -1];

M5a = [1, 1, 0, 1, -1];

M6a = [-1, 1,-1, -1];

M7a = [-1, -1, -1, 1, -1, 1, 1];

M8a = [1, 1, -1, -1, -1, 1, -1];

M9a = [-1, -1, 1]; and

M10a= [1, -1,-1, -1, -1, 1, -1]; wherein M1 is used to generate the periodic signal 101 within a first bandwidth, M2 is used to generate the periodic signal 101 within a second bandwidth, the second bandwidth comprising the first bandwidth, and/or M3_1 and M3_2, as well as M1 a to M10a are used to generate the periodic signal within a third bandwidth, the third bandwidth comprising the second bandwidth. The entries of the seed sequences are digital values, in particular digital binary values. The seed sequences can be provided by digital memory cells having digital states representing the respective entry. The periodic signal 101 is generated from at least one of the seed sequences upon the basis of one of the following formulas:

HES1 =[M1 , -1 , -1 , 0, -1 , +1 , -fliplr(M1 )] HES2=[M2, 0, -fliplr(M2)]

HES3=[M3_1 , 0, M3_2, +1 , +1 , 0, +1 , -1 , fliplr(M3_2), 0, fliplr(M3_1 )]

HES(-120:8:1 20) = [M1 a, M2a, -M5a, M2a, -fliplr(Ml a)] HES(-240:8:240) = [-fliplr(M1 a), -M3a, M4a, M3a, 0, M3a, 0, -M3a, 0, -M3a, M4a, - M3a, (M1 a) ]

HES(-496:8:496) = [M8a, M3a, M4a, fliplr(M3a), M7a, 0, fliplr(M3a), fliplr(M1 a), - fliplr(M9a), M8a, fliplr(M3a), M5a, M3a, fliplr(M8a), -fliplr(M9a), fliplr(M8a), M2a, 0, M1 0a, fliplr(M3a), M4a, M3a, fliplr(M8a)]; wherein fliplr denotes reversing the order of seed sequence entries, and wherein M1 , M2, M3_1 and M3_2 and M1 a to M10a denote seed sequences, and -1 20:8:1 20 denotes the subcarrier positions -120 to 1 20 with jumps of 8 positions for a 20MHz bandwidth, - 240:8:240 denotes the subcarrier positions -240 to 240 with jumps of 8 positions for a 40MHz bandwidth and -496:8:496 denotes the subcarrier positions -496 to 496 with jumps of 8 positions for a 80MHz bandwidth.

Once generated, the periodic signal 101 is transmitted through a communication network 103 to a receiver 105. The receiver 105 is configured to perform AGC adjustment upon the base of the received periodic signal 101 . Fig. 2 shows a schematic diagram illustrating the communication transmitter 100 for providing the periodic signal 101 for channel measurements, in particular for channel gain measurements, according to an embodiment. The communication transmitter 100 comprises a processor 107 being configured to determine the periodic signal 101 upon the basis of at least one of the following seed sequences: the first seed sequence M1 for transmitting the periodic signal 101 within a first bandwidth, e.g. 20MHz, the second seed sequence M2 for transmitting the periodic signal 101 within a second bandwidth, e.g. 40MHz, the third seed sequence M3_1 for transmitting the periodic signal 101 within the third bandwidth, e.g. 80 MHz and/or the fourth seed sequence M3_2 for transmitting the periodic signal 101 within the third bandwidth. The third and fourth seed sequences can be used to generate the periodic signal 101 in different portions of the third bandwidth, e.g. in a lower portion and in an upper portion.

In an embodiment, the processor 107 is configured to determine the periodic signal 101 for transmission within the third bandwidth upon the basis of the third seed sequence M3_1 , in particular for a lower portion of the third bandwidth, and the fourth seed sequence M3_2, in particular for an upper portion of the third bandwidth.

In an embodiment, the processor 107 is configured to generate the periodic signal 101 e.g. HES1 , HES2, HES3 from at least one of the seed sequences, upon the basis of one of the formulas described above.

The periodic signals 101 , e.g. HES1 , HES2, HES3, HES can lead to the PAPR reduction by 1 -2.5 dB and are efficient for small resource allocations. The periodic signal 101 , in particular HES3 and HES can also be applied in case of a wider bandwidth such as 80 MHz. As shown in Fig. 2, in an embodiment, the communication transmitter 100 further comprises a memory 109 being arranged to store the seed sequences, and wherein the processor 107 is configured to retrieve the respective seed sequence from the memory 109 to determine the periodic signal 101 .

The memory 109 allows to store the seed sequences M1 , M2, M3_1 , M3_2 and to

specifically select the seed sequence, which leads to a PAPR reduction for a given bandwidth. As shown in Fig. 2, the communication transmitter 100 further comprises a communication interface 1 1 1 for transmitting the periodic signal 101 according to a multicarrier transmission technology, in particular according to the OFDM transmission technology.

In an embodiment, the periodic signal 101 is a High Efficiency Short Training Field signal (HE-STF).

In an embodiment, the first bandwidth is 20 MHz and/or the second bandwidth is 40 MHz and/or the third bandwidth is 80 MHz. The transmitter 100 can be configured to perform multi-carrier communication based on the OFDM transmission technology according to the 802.1 1 ax standard. In order to adjust the AGC it can transmit a periodic HE-STF signal 101 to the receiver 105. The transmission can be performed in the 20 MHz, the 40 MHz or 80 MHz bandwidth. Depending on the

bandwidth, the processor 107 of the transmitter 100 is configured to select one of the seed sequences described herein from the memory 109 and to generate a corresponding periodic HE-STF signal.

For example, for the 20 MHz bandwidth, the processor 107 can select the seed sequence M1 and the periodic signal HES1 , for the 40 MHz bandwidth the processor 107 can select the seed sequence M2 and the periodic signal HES2, and for the 80 MHz bandwidth the processor 107 can select the seed sequences M3_1 and M3_2, as well as the periodic signal HES3.

The transmitter 101 can be configured to carry out a method for providing the periodic signal 101 for channel measurements, in particular for channel gain measurements, comprises determining the periodic signal 101 upon the basis of the first seed sequence M1 for transmitting the periodic signal 101 within the first bandwidth or upon the basis of the second seed sequence M2 for transmitting the periodic signal 101 within the second bandwidth, the second bandwidth comprising the first bandwidth, or upon the basis of the third seed sequence M3_1 and/or the fourth seed sequence M3_2 for transmitting the periodic signal 101 within the third bandwidth, the third bandwidth comprising the second bandwidth.

The seed sequences M1 , M2 and M3_1 , M3_2 can have the structure as described above. In an embodiment, the periodic signal 101 is generated from at least one of the seed sequences, upon the basis of one of the formulas HES1 , HES2, HES3 described above by the transmitter 101 , in particular by the processor 107.

In an embodiment, the method further comprises transmitting the periodic signal 101 according to a multicarrier transmission technology, in particular according to the OFDM transmission technology. The transmission can be carried out by the communication interface 1 1 1 .

Generally, the method described in the embodiments can be performed by the

communication transmitter 100.

Embodiments of the invention provide a reduced PAPR by applying different periodic training signals for different bandwidths. The periodic signals are derived from predefined seed sequences. The embodiments of the invention can be applied to different bandwidths, in particular to 20 MHz, 40 MHz or 80 MHz bandwidths according to the 802.1 1 ax standard. The resulting PAPR can reduced by up to 2.5 dB.

Decreasing of the PAPR of the transmission channel enables transmitting with a higher average power, which increases the transmit signal-to-noise ratio. This, in turn, leads to improvement in throughput and/or to extending the transmission range.

Additionally, reducing PAPR may yield cost reduction for low-end devices.

While a particular feature or aspect of the disclosure may have been disclosed with respect to only one of several implementations or embodiments, such feature or aspect may be combined with one or more other features or aspects of the other implementations or embodiments as may be desired and advantageous for any given or particular application. Furthermore, to the extent that the terms "include", "have", "with", or other variants thereof are used in either the detailed description or the claims, such terms are intended to be inclusive in a manner similar to the term "comprise". Also, the terms "exemplary", "for example" and "e.g." are merely meant as an example, rather than the best or optimal. The terms "coupled" and "connected", along with derivatives may have been used. It should be understood that these terms may have been used to indicate that two elements cooperate or interact with each other regardless whether they are in direct physical or electrical contact, or they are not in direct contact with each other.

Although specific aspects have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent

implementations may be substituted for the specific aspects shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the specific aspects discussed herein.

Although the elements in the following claims are recited in a particular sequence with corresponding labeling, unless the claim recitations otherwise imply a particular sequence for implementing some or all of those elements, those elements are not necessarily intended to be limited to being implemented in that particular sequence.

Many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the above teachings. Of course, those skilled in the art readily recognize that there are numerous applications of the invention beyond those described herein. While the present invention has been described with reference to one or more particular embodiments, those skilled in the art recognize that many changes may be made thereto without departing from the scope of the present invention. It is therefore to be understood that within the scope of the appended claims and their equivalents, the invention may be practiced otherwise than as specifically described herein.