System and method for transmitting and receiving chirped pilot signals for channel estimation from a chirped DFT-OFDM module

Abstract

A method of operating a network controller device is disclosed. The method includes assigning a first set of parameters of a chirped sequence pilot signal to a first network device. The method further includes assigning a second set of parameters of a chirped sequence pilot signal to a second network device, where the second set of parameters are different from the first set of parameters. The first set of parameters are to be used by the first network device to generate a first chirped sequence pilot signal, and the second set of parameters are to be used by the second network device to generate a second chirped sequence pilot signal.

Description

[0001] SYSTEM AND METHOD FOR TRANSMITTING AND RECEIVING PILOT SIGNALS FOR CHANNEL

[0002] ESTIMATION

[0003] TECHNICAL FIELD

[0004] The present disclosure relates generally to the field of wireless communication systems and, more specifically, to a system, and a method for transmitting and receiving pilot signals for low peak-to-average power ratio (PAPR) sensing and channel estimation purposes.

[0005] BACKGROUND

[0006] In modem wireless communication systems, accurate channel estimation is vital for achieving high data rates and reliable communication. The channel estimation involves the process of characterizing the transmission medium so that the transmitted signal can be accurately received and decoded. The channel estimation process relies on pilot signals, which are predefined signals known to both a transmitter and a receiver. One common technique for the channel estimation involves the use of an Orthogonal Frequency-Division Multiplexing (OFDM), a method that splits the data stream into multiple parallel sub-channels, each carrying a portion of the data at a lower rate. While the OFDM is effective for combating multipath fading and achieving high spectral efficiency, it suffers from a high peak-to-average power ratio (PAPR), which leads to power inefficiency and signal distortion.

[0007] To mitigate the high PAPR problem, various techniques have been proposed such as use of a Discrete Fourier Transform (DFT) spreading, which spreads the signal across the subcarriers, resulting in a lower PAPR. Additionally, chirped sequence pilot signals, which are frequency-modulated signals that sweep through a range of frequencies, have been shown to improve channel estimation performance due to their robustness against noise and interference. However, the implementation of the chirped sequence pilot signals in a network with multiple network devices introduces several challenges. Each network device needs to generate and use unique chirped sequence pilot signals to avoid interference and ensure accurate channel estimation. The uniqueness requires the assignment of specific parameters to each network device, which complicates the network management and signal processing.

[0008] Therefore, in light of the foregoing discussion, there exists a need to overcome the aforementioned drawbacks associated with the conventional systems and the conventional methods for transmitting and receiving pilot signals for PAPR sensing and channel estimation.

[0009] SUMMARY

[0010] The present disclosure provides a system, a method, and a computer program for transmitting and receiving the pilot signals for low-peak-to-average power ratio (PAPR) sensing and channel estimation purposes. The present disclosure provides a solution to the existing problem of how to mitigate interference across multiple network devices while maintaining low PAPR and compatibility with low-sampling rate receivers. An objective of the present disclosure is to provide a solution that overcomes at least partially the problems encountered in the prior art and provides an improved system and an improved method for transmitting and receiving pilot signals for low PAPR sensing and channel estimation.

[0011] One or more objectives of the present disclosure are achieved by the solutions provided in the enclosed independent claims. Advantageous implementations of the present disclosure are further defined in the dependent claims.

[0012] In one aspect, the present disclosure provides a method of operating a network controller device. The method includes assigning a first set of parameters of a chirped sequence pilot signal to a first network device. The method further includes assigning a second set of parameters of a chirped sequence pilot signal to a second network device. The second set of parameters are different from the first set of parameters. Further, the first set of parameters are to be used by the first network device to generate a first chirped sequence pilot signal, and the second set of parameters are to be used by the second network device to generate a second chirped sequence pilot signal.

[0013] Advantageously, by assigning different sets of parameters to the first network device and the second network device, the method ensures that the generated chirped sequence pilot signals are unique for each network device. The uniqueness helps in reducing interference between pilot signals, leading to better channel estimation and sensing performance. Enhanced channel estimation accuracy is achieved through the use of chirped sequence pilot signals with carefully assigned parameters. Accurate channel estimation is critical for reliable communication and accurate sensing performance. Additionally, the chirped sequence pilot signals are designed to have a lower PAPR, which minimizes power fluctuations and reduces the risk of signal distortion. Minimized power fluctuation results in more efficient use of power and improves the quality of the transmitted signals. By allowing the assignment of different sets of parameters to multiple network devices, the method supports scalability. Furthermore, the method provides flexibility in generating chirped sequence pilot signals, accommodating both discrete-time and continuous-time chirping. The flexibility allows for adaptation to various hardware and system requirements, making the method versatile for different network scenarios. By optimizing the parameters for each network device, the method ensures efficient utilization of network resources, such as bandwidth and power.

[0014] In a second aspect, the present disclosure provides a method of operating a network device. The method includes Determining a first set of parameters of a chirped sequence pilot signal. The method further includes generating a chirped sequence pilot signal using the first set of parameters.

[0015] Advantageously, the method ensures that the generated chirped sequence pilot signal is optimally configured for the specific channel conditions and network requirements. By using the assigned parameters, the network device can produce a pilot signal with a low peak-to-average power ratio (PAPR), which reduces power consumption and minimizes signal distortion. The method also enhances the accuracy of channel estimation, as the chirped sequence pilot signal is tailored to the communication environment, improving the overall reliability and performance of the network. Additionally, the method approach enables dynamic and flexible network management, allowing for efficient adaptation to changing conditions and requirements.

[0016] In an implementation form, network device (304) receiving an assigned first set of parameters of a chirped sequence pilot.

[0017] In an implementation form, the generated chirped sequence pilot signal is output from a chirped discrete fourier transform (DFT) spread orthogonal frequency-division multiplexing (OFDM) module.

[0018] The chirping introduces a frequency spreading, which helps in resolving multipath components more effectively. The resolution of multipath components results in a more precise separation of multipath signals, improving the accuracy of channel estimation. Using cyclic or frequency shifts in chirping makes the signal more resilient to interference. The technique can help distinguish between signals from different users or cells, reducing cross-channel interference and enhancing signal clarity.

[0019] In an implementation form, , the chirped DFT-s-OFDM module applies to the sequence at its input a phase rotation, wherein the phase rotation is based on a polynomial function of the input index, and passes it to a DFT module, and applies to the output of the DFT module a phase rotation producing an intermediate sequence, wherein the phase rotation is based on a polynomial function of the output index and the linear component of the polynomial is based on a frequency shift parameter and a chirp rate parameter.

[0020] In an implementation form, , the chirped DFT-s-OFDM module maps the samples of an intermediate sequence to consecutive inputs of an Inverse Discrete Fourier Transform, IDFT, and produces a chirped sequence by applying to the output of the IDFT module a discrete-time chirping by a phase rotation, wherein the discrete-time chirping is based on a polynomial phase rotation function of the intermediate sequence index whose quadratic term is based on a chirp rate parameter

[0021] In an implementation form, , the chirped sequence is mapped to a set of subcarriers at the input of an OFDM modulator.

[0022] In another implementation form, the assigned set of parameters include values representing a sequence length, a scrambling identifier, a random seed, a Zadoff-Chu root, a cyclic shift, a frequency shift, and a chirp rate.

[0023] Advantageously, specifying the sequence length ensures that the chirped sequence pilot signal is appropriately structured for efficient processing within the network controller device. The assigned set of parameters directly impacts the duration and characteristics of the chirped sequence pilot signal, influencing its ability to convey information reliably over the channel. The scrambling identifier, the random seed or the Zadoff Chu root value parameters contribute to the chirped sequence pilot signal uniqueness and security. The cyclic shift and the frequency shift parameters allow the network controller device to adjust the timing and frequency characteristics of the chirped sequence pilot signal dynamically to create, for example, multiple orthogonal pilot resources.

[0024] In another implementation form, the OFDM module has a number of inputs defined by the sequence length value included in the respective assigned set of parameters.

[0025] In such an implementation, the sequence length value dictates the number of inputs to the OFDM module, allowing the network device to optimize the allocation of resources. The allocation ensures that the available bandwidth and time slots are utilized efficiently, maximizing the network capacity and performance. By tailoring the number of OFDM module inputs to the sequence length, the network device can more precisely control the frequency domain representation of the chirped sequence pilot signal.

[0026] In another implementation form, a chirping is defined by the values of the cyclic shift or the frequency shift.

[0027] By assigning unique cyclic shift values to different cells or users, the network device significantly reduces intra-cell and intercell interference. The reduction in interference ensures that overlapping chirp signals can be distinguished, leading to better channel estimation and sensing performance. Frequency shifts create orthogonal chirp signals that minimize the chances of interference between signals from different cells or users, further improving the overall signal quality. Unique cyclic and frequency shifts help in creating distinct signal identities. The distinctiveness allows receivers to quickly identify and separate signals, even in a crowded spectral environment, enhancing multi-user detection and decoding. The cyclic shift and the frequency shifts contribute to better channel estimation by providing distinct pilot signals.

[0028] In an implementation form, the generated chirped sequence pilot signal is generated by replacing a discrete-time chirping with a continuous-time chirping.

[0029] The continuous-time chirping eliminates the need for DAC operating at a high sample rate. Reducing sample rate requirements, data rates, and receiver processing load, thereby saving computational resources. By avoiding quantization errors, the continuous-time chirping maintains higher signal fidelity and allows for precise control in time and frequency domains.

[0030] In an implementation form, the continuous-time chirping is performed after a digital-to-analog converter (DAC) performs digital-to- analog conversion.

[0031] By performing continuous time chirping after digital to analog conversion, the network device may leverage digital signal processing techniques to more flexibly and precisely control the bandwidth of the pilot signal so that it does not exceed the allocated bandwidth. In a third aspect, the present disclosure provides a method of operating a network device. The method of operating the network device includes receiving a chirp-based pilot signal and performing channel estimation based on a received chirp-based pilot signal.

[0032] In an implementation form, the chirp-based pilot signal is a chirped sequence pilot signal that has been generated according to the method of the second aspect.

[0033] By receiving a specific set of parameters from the network controller, the chirped sequence pilot signal can be optimized for the current network conditions. The optimized conditions lead to more accurate channel estimation, enhancing the reliability of data transmission. The assignment of unique parameter sets (such as cyclic shift and frequency shift) to different devices or cells helps in distinguishing between signals, thereby reducing interference and improving overall network performance. The network controller device dynamically adjusts the parameters based on real-time network conditions, allowing the generated chirped sequence pilot signal to be tailored for optimal performance in varying environments. The use of the set of assigned parameters ensures that the chirped sequence pilot signals are optimized for spectral efficiency.

[0034] In an implementation form, the channel estimation is performed by feeding an output of an analog-to-digital converter to a chirped Discrete DFT spread OFDM receiver module which has a number of outputs defined by a sequence length value included in the respective assigned set of parameters.

[0035] The use of chirped signals in DFT spread OFDM helps mitigate frequency offsets, which can degrade signal quality, especially in wireless channels. The spreading technique helps to improve resistance against multipath fading, ensuring more reliable signal reception even in environments with significant reflections and signal delays. The DFT spreading inherently lowers the PAPR of the transmitted pilot signal, which is beneficial for reducing power amplifier requirements and enhancing energy efficiency.

[0036] In an implementation form, the channel estimation is performed by feeding an output of an analog-to-digital converter to a chirped DFT receiver module which has a chirping defined by a cyclic or frequency shift values included in the respective assigned set of parameters.

[0037] The use of chirping (cyclic or frequency shifts) improves the ability of the to resolve different frequency components, allowing for more accurate separation and estimation of signal paths in the presence of frequency- selective fading. By spreading the signal over a wider bandwidth and applying shifts, chirped DFT can help reduce the impact of narrowband interference, leading to cleaner signal reception and better performance in noisy environments.

[0038] In an implementation form, the network device that receives the generated chirped sequence pilot signal, and which performs channel estimation replaces the chirping with a continuous time dechirping performed before an analog to digital conversion takes place.

[0039] The continuous-time de-chirping eliminates the need for ADC operating at a high sample rate. Reducing sampling rate requirements, data rates, and receiver processing load, thereby saving computational resources. By avoiding quantization errors, the continuous-time chirping maintains higher signal fidelity and allows for precise control in time and frequency domains.

[0040] In an implementation form, the network device that receives the generated chirped sequence pilot signal, and which performs channel estimation replaces the analog-to-digital converter with a sub-Nyquist analog-to-digital converter i.e., an analog-to- digital converter operating with a sampling rate smaller or equal than the bandwidth of the pilot signal, and replaces the chirping with a chirping done with a chirp rate larger or equal than the chirp rate of the pilot signal. This sub-Nyquist sampling does not result in aliasing the received pilot signal thanks to the chirp nature of that signal. In a fourth aspect, the present disclosure provides a system comprising means adapted for carrying out all the steps of the method of the first aspect.

[0041] The system achieves all the advantages and technical effects of the method of the first aspect of the present disclosure.

[0042] In a fifth aspect, the present disclosure provides the network device for carrying out all steps for the method of the second aspect and the third aspect.

[0043] The network device achieves all the advantages and technical effects of the methods of the second aspect and the third aspect of the present disclosure.

[0044] In a sixth aspect, the present disclosure provides a computer program comprising instructions for carrying out all the steps of the methods of the first aspect, the second aspect and the third aspect when the computer program is executed on a computer system.

[0045] It is to be appreciated that all the aforementioned implementation forms can be combined.

[0046] It has to be noted that all devices, elements, circuitry, units, and means described in the present application could be implemented in the software or hardware elements or any kind of combination thereof. All steps which are performed by the various entities described in the present application as well as the functionalities described to be performed by the various entities are intended to mean that the respective entity is adapted to or configured to perform the respective steps and functionalities. Even if, in the following description of specific embodiments, a specific functionality or step to be performed by external entities is not reflected in the description of a specific detailed element of that entity which performs that specific step or functionality, it should be clear for a skilled person that these methods and functionalities can be implemented in respective software or hardware elements, or any kind of combination thereof. It will be appreciated that features of the present disclosure are susceptible to being combined in various combinations without departing from the scope of the present disclosure as defined by the appended claims.

[0047] Additional aspects, advantages, features, and objects of the present disclosure would be made apparent from the drawings and the detailed description of the illustrative implementations construed in conjunction with the appended claims that follow.

[0048] BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The summary above, as well as the following detailed description of illustrative embodiments, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the present disclosure, exemplary constructions of the disclosure are shown in the drawings. However, the present disclosure is not limited to specific methods and instrumentalities disclosed herein. Moreover, those in the art will understand that the drawings are not to scale. Wherever possible, like elements have been indicated by identical numbers.

[0050] Embodiments of the present disclosure will now be described, by way of example only, with reference to the following diagrams wherein:

[0051] FIG. 1 is a block diagram that depicts a system configured for transmitting and receiving pilot signals for low peak- to-average power ratio (PAPR) sensing and channel estimation, in accordance with an embodiment of the present disclosure;

[0052] FIG. 2 is a flowchart depicting a method for operating the network controller device, in accordance with an embodiment of the present disclosure;

[0053] FIG. 3 is a block diagram of a network device used for generating chirped sequence pilot signals, in accordance with an embodiment of the present disclosure; FIG. 4 is a flowchart depicting a method for operating the network device to generate chirped sequence pilot signals, in accordance with another embodiment of the present disclosure;

[0054] FIG. 5 is a flowchart depicting a method for operating the network device for channel estimation, in accordance with an embodiment of the present disclosure;

[0055] Fig. 6 is an exemplary diagram that depicts the generation of a chirped sequence pilot signal by using the network device transmitter, in accordance with an embodiment of the present disclosure;

[0056] Fig. 7 is an exemplary diagram that depicts the channel estimation process by using the network device receiver, in accordance with an embodiment of the present disclosure.

[0057] Fig. 8 is an exemplary diagram that depicts the channel estimation process by using the network device receiver, in accordance with an embodiment of the present disclosure.

[0058] Fig. 9 shows a schematic flowchart of a pilot signal transmission method according to an embodiment of this disclosure; and

[0059] Fig. 10 shows a schematic flowchart of a pilot signal transmission method according to an embodiment of this disclosure.

[0060] In the accompanying drawings, an underlined number is employed to represent an item over which the underlined number is positioned or an item to which the underlined number is adjacent. A non-underlined number relates to an item identified by a line linking the non-underlined number to the item. When a number is non-underlined and accompanied by an associated arrow, the non-underlined number is used to identify a general item at which the arrow is pointing.

[0061] DETAILED DESCRIPTION OF EMBODIMENTS

[0062] The following detailed description illustrates embodiments of the present disclosure and ways in which they can be implemented. Although some modes of carrying out the present disclosure have been disclosed, those skilled in the art would recognize that other embodiments for carrying out or practicing the present disclosure are also possible.

[0063] FIG. 1 is a block diagram that depicts a system configured for transmitting and receiving pilot signals for low peak-to-average power ratio (PAPR) sensing and channel estimation, in accordance with an embodiment of the present disclosure. With reference to FIG.1 , there is shown a block diagram 100 that includes a system 102. The system 102 includes a network controller device 104, a first network device 106 and a second network device 116. The first network device 106 includes a first transmitter 108 and a first receiver 110. The first transmitter 108 includes a first transmitter’s plurality of antennas 112, and the first receiver includes a first receiver’s plurality of antennas 114. The second network device 116 includes a second transmitter 118 and a second receiver 120. The second transmitter 118 includes a second transmitter’s plurality of antennas 122, and the second receiver 120 includes a second receiver’s plurality of antennas 124.

[0064] The system 102 is designed to enhance wireless communication through the use of chirped sequence pilot signals for improved channel estimation and interference management. The system 102 includes a network controller device 104 which plays a role in assigning unique sets of parameters for chirped sequence pilot signals to each of the network devices, i.e. the first network device 106 and the second network device 116. Specifically, the network controller device 104 assigns a first set of parameters to the first network device 106 and the second set of parameters to the second network device 116. The chirped sequence pilot signals are generated by each of the network devices (the first network device 106 and the second network device 116) based on the assigned set of parameters. The generated chirped sequence pilot signals are then used for channel estimation, with the first network device 106 and the second network device 116 feeding the output of their analog-to-digital converters (ADCs). The network controller device 104 is a central component within system 102 responsible for managing and coordinating the operations of network devices (i.e., the first network device 106 and the second network device 116 leading to better channel estimation and sensing performance. The network controller device 104 manages network resources such as bandwidth, frequency channels, and transmission power to optimize wireless communication network performance and, reduce interference between network devices and operate in a synchronized manner, coordinating their transmissions to avoid collisions and ensure seamless communication.

[0065] The first network device 106 is designed to handle both the transmission and reception of data, leading to better channel estimation and sensing performance. The first network device 106 is the responsible for generating and transmitting pilot signals, including chirped sequence pilot signals, based on parameters assigned by the network controller device 104. The first network device 106 includes modules for essential signal processing tasks such as modulation, demodulation, error correction, and channel estimation.

[0066] The first transmitter 108 refers to a component of the first network device 106, which is responsible for generating and transmitting pilot signals. The first transmitter 108 incorporates advanced technologies and multiple antennas to optimize signal transmission quality and efficiency. The first transmitter 108 uses the first transmitter’s plurality of antennas 112 that enables advanced communication techniques like beamforming and spatial multiplexing, which enhance transmission quality, increase data throughput, and improve signal coverage. The first transmitter 108 generates signals, including chirped sequence pilot signals, based on parameters assigned by the network controller device 104.

[0067] The first receiver 110 refers to the component of the first network device 106 designed to receive and process chirped sequence pilot signals transmitted by the network controller device 104 within the wireless communication system. The first receiver 110 captures incoming signals through the first transmitter’s plurality of antennas 112. The first receiver 110, processes these signals to extract transmitted data, perform demodulation, and decode the information accurately.

[0068] The first transmitter’s plurality of antennas 112 is a set of multiple antennas used for transmitting data signals to the network controller device 104. The first transmitter’s plurality of antennas 112 enables advanced techniques like beamforming and spatial multiplexing to improve transmission quality and capacity.

[0069] The first receiver’s plurality of antennas 114 is a set of multiple antennas used for receiving data signals from the network controller device 104. The antennas enhance signal reception through spatial diversity, which helps mitigate interference and multipath effects.

[0070] The second network device 116 and its components have the same functionalities and specifications as that of the first network device 106.

[0071] The network controller device 104 is configured to assign a first set of parameters of a chirped sequence pilot signal to the first network device 106. The first set of parameters refers to a specific collection of values assigned to the first network device 106 to define the characteristics and behavior of the chirped sequence pilot signals it generates. The chirped sequence pilot signal is a type of reference signal used in the wireless communication systems to facilitate accurate channel estimation and synchronization. The chirped sequence pilot signal is characterized by its frequency modulation, where the frequency of the signal changes over time according to a predefined pattern, known as chirping . In accordance with an embodiment, the assigned set of parameters include values representing a sequence length, a sequence related ID, i.e., a scrambling identifier, a random seed, a Zadoff-Chu root or a cyclic shift, a frequency shift, and a chirp rate. Advantageously, specifying the sequence length ensures that the chirped sequence pilot signal is appropriately structured for efficient processing within the network controller device. The assigned set of parameters directly impacts the duration and characteristics of the chirped sequence pilot signal, influencing its ability to convey information reliably over the channel. The scrambling identifier and the identifier, the random seed or the Zadoff Chu root value parameters contribute to the chirped sequence pilot signal uniqueness and. The cyclic shift and the frequency shift parameters allow the network controller device to adjust the timing and frequency characteristics of the chirped sequence pilot signal dynamically to create, for example, multiple orthogonal pilot resources.

[0072] In accordance with an embodiment, the chirping is defined by the values of the cyclic shift or the frequency shift. The cyclic shift offers the ability to fine-tune the signal properties within the same frequency band, allowing for flexible network design and deployment strategies without needing additional bandwidth and frequency shift allows for the distribution of signals across different frequency bands, providing more options for managing spectrum resources and reducing the likelihood of overlapping signals. By spreading the signals over different cyclic shifts and frequency bands, the system 102 can support more users within the same spectral resources, increasing the overall network capacity. The ability to define the chirping through cyclic and frequency shifts ensures that the system can scale to support future network demands. The scalability ensures that the network remains relevant and capable of handling increasing traffic and user densities.

[0073] In operation, the network controller device 104 initializes the first set of parameters that will define the chirped sequence pilot signal. Once the set of parameters is determined, the network controller device 104 assigns the set of parameters specifically to the first network device 106. The assignment ensures that the set of parameters is unique to the first network device 106, minimizing the risk of signal interference with other devices. The network controller device 104 communicates the assigned set of parameters to the first network device 106. The communication may occur over a secure control channel or through a signalling protocol designed for network management. The parameters are sent in a structured format that the first network device 106 can interpret and use. The first network device 106 receives the set of parameters transmitted by the network controller device 104. The first network device 106 is equipped with the necessary software and hardware to decode and store these parameters for subsequent use.

[0074] The network controller device 104 is further configured to assign a second set of parameters of a chirped sequence pilot signal to the second network device. The second set of parameters are different from the first set of parameters. The network controller device 104 identifies the second network device 116 within the network. The identification may be based on the unique identifier of the second network device 116, such as its MAC (Media Access Control) address, IP address, or another unique device identifier.

[0075] The network controller device 104 ensures that the second set of parameters is different from the first set of parameters. The difference is achieved by using different values for each parameter, applying algorithms or randomization techniques to generate distinct values, and ensuring non-overlapping ranges for parameters such as frequency shift and cyclic shift. The network controller device 104 assigns the generated set of parameters to the second network device 116. The assignment may be communicated through configuration messages in which the network controller device 104 sends configuration messages to the second network device 116, detailing the assigned parameters. In some implementations, the assignment may be communicated through control channels in which the parameters can be transmitted over dedicated control channels within the network. The network controller device 104 verifies that the second network device 116 has correctly received and applied the assigned parameters. In some implementations, verification is done through acknowledgement messages and monitoring. The network controller device 104 may periodically re-evaluate and adapt the parameters based on network conditions, device mobility, and environmental factors to maintain optimal performance.

[0076] The first set of parameters are to be used by the first network device 106 to generate a first chirped sequence pilot signal, and the second set of parameters are to be used by the second network device 116 to generate a second chirped sequence pilot signal. Upon receiving the set of parameters, the first network device 106 network device and the second network device 116 configure their respective signal generation module. Using the configured signal generation module, the first network device 106 and the second network device 116 generate the chirped sequence pilot signal. The signal generation module processes the input according to the set of parameters, producing a pilot signal with the desired characteristics. In accordance with an embodiment, the generated chirped sequence pilot signal is output from a chirped Discrete Fourier Transform (DFT) spread Orthogonal Frequency-Division Multiplexing (OFDM) module. The chirping introduces a frequency spreading, which helps in resolving multipath components more effectively. The resolution of multipath components results in a more precise separation of multipath signals, improving the accuracy of channel estimation. Using cyclic or frequency shifts in chirping makes the signal more resilient to interference. The technique can help distinguish between signals from different users or cells, reducing cross-channel interference and enhancing signal clarity.

[0077] Finally, the generated chirped sequence pilot signal is transmitted by the first network device 106. The generated chirped sequence pilot signal is used for various purposes, including synchronization, channel estimation, and reducing interference. The unique set of parameters ensures that the generated chirped sequence pilot signal is distinct from those of other network devices, enhancing the overall performance and reliability of the network.

[0078] In accordance with an embodiment, the generated chirped sequence pilot signal is generated by replacing a discrete-time chirping with a continuous-time chirping. The continuous-time chirping involves generating a signal in the analog domain where the frequency variation occurs smoothly over time without discrete steps. An analog circuit or a continuous waveform generator is used to create the chirped signal whose frequency continuously increases or decreases over time. After generating the continuous-time chirped signal, it can be converted back into the digital domain if needed using an Analog-to-Digital Converter (ADC). The ADC samples the continuous signal at specific intervals, converting it into a discrete-time signal for further digital processing if required. The continuous-time chirping eliminates the need for DAC operating at a high sample rate. Reducing sample rate requirements, data rates, and receiver processing load, thereby saving computational resources. By avoiding quantization errors, the continuous-time chirping maintains higher signal fidelity and allows for precise control in time and frequency domains.

[0079] In accordance with an embodiment, the continuous-time chirping is performed after a digital-to-analog converter performs digital-to-analog conversion. By performing continuous time chirping after digital to analog conversion, the network device may leverage digital signal processing techniques to more flexibly and precisely control the bandwidth of the pilot signal so that it doesn’t exceed the allocated bandwidth.

[0080] In accordance with an embodiment, the OFDM module has a number of inputs defined by the sequence length value included in the respective assigned set of parameters. By tailoring the number of OFDM inputs to the sequence length, the respective network devices, i.e., the first network device 106 and the second network device 116 can more precisely control the frequency domain representation of the signal. The precise control leads to better spectral efficiency, minimizing the amount of unused spectrum and reducing interference between channels. The ability to define the number of inputs based on the sequence length allows for fine-tuning of the signal processing.

[0081] FIG. 2 is a flowchart depicting a method for operating the network controller device, in accordance with an embodiment of the present disclosure. With reference to FIG. 2, there is shown a flowchart of a method 200 for operating the network controller device 104. The method 200 includes steps 202 to 204.

[0082] At step 202, the method 200 includes assigning the first set of parameters of the chirped sequence pilot signal to the first network device 106. The network controller device 104 initializes the assignment process, preparing the necessary parameters for the chirped sequence pilot signal. The preparation may involve setting up internal variables, memory allocations, and communication channels. The network controller device 104 generates the first set of parameters for the chirped sequence pilot signal. The first set of parameters includes values for sequence length, a sequence related ID, i.e., a scrambling identifier, a random seed, a Zadoff-Chu root or a cyclic shift, a frequency shift, and a chirp rate. Advantageously, specifying the sequence length ensures that the chirped sequence pilot signal is appropriately structured for efficient processing within the network controller device. The assigned set of parameters directly impacts the duration and characteristics of the chirped sequence pilot signal, influencing its ability to convey information reliably over the channel. The scrambling identifier and the identifier, the random seed or the Zadoff Chu root value parameters contribute to the chirped sequence pilot signal uniqueness and. The cyclic shift and the frequency shift parameters allow the network controller device to adjust the timing and frequency characteristics of the chirped sequence pilot signal dynamically to create, for example, multiple orthogonal pilot resources.

[0083] At step 204, the method 200 includes assigning a second set of parameters of a chirped sequence pilot signal to the second network device 116. The second set of parameters are different from the first set of parameters. The network controller device 104 prepares to generate and assign the second set of parameters for the chirped sequence pilot signal specifically for the second network device 116. The process involves setting up the necessary software and hardware resources. The network controller device 104 generates the second set of parameters, ensuring these parameters differ from those assigned to the first network device 106. The generated parameters are customized to suit the specific operational capabilities and requirements of the second network device 116. The customization ensures that the second network device 116 can effectively use the second set of parameters to generate a pilot signal optimized for its environment. The second set of parameters is packaged into a configuration data package that can be transmitted to the second network device 116. The configuration data package is transmitted from the network controller device 104 to the second network device 116. The transmission can be performed via wired or wireless communication channels. The second network device 116 receives the configuration data package. Upon successful reception, the device may send an acknowledgement back to the network controller to confirm receipt and readiness to apply the parameters.

[0084] The first set of parameters are to be used by the first network device 106 to generate a first chirped sequence pilot signal, and the second set of parameters are to be used by the second network device 116 to generate a second chirped sequence pilot signal. In some implementations, both the network devices (i.e., the first network device 106 and the second network device 116) use their respective Zadoff-Chu roots to generate a base sequence with good correlation properties. The Zadoff-Chu sequence is a complex-valued mathematical sequence that, when applied to a signal, gives rise to a new signal of constant amplitude. When cyclically shifted versions of a Zadoff-Chu sequence is imposed upon a signal, the resulting set of signals detected at the receiver are uncorrelated with one another. The Zadoff-Chu sequence serves as the fundamental building block for the pilot signal.

[0085] In some other implementations, each device (i.e., the first network device 106 and the second network device 116) applies the scrambling identifier to the base sequence to create a unique scrambled sequence, which ensures that each pilot signal is distinct and resistant to interference. The first network device 106 applies the cyclic shift and frequency shift parameters to the scrambled sequence, which adjusts the timing and frequency characteristics of the signal, helping it to adapt to the specific channel conditions. The second network device 116 applies its own cyclic shift and frequency shift parameters similarly. Both the network devices (i.e., the first network device 106 and the second network device 116) apply their respective chirp rate to the sequence. The application of the chirp rate involves modulating the frequency of the signal over time according to the specified chirp rate, creating the chirped sequence. Initially, both devices generate the chirped sequence in discrete-time format. After generating the discrete-time chirped sequence, each network device (i.e., the first network device 106 and the second network device 116) converts it to a continuous-time signal. The conversion involves using digital-to-analog converters and applying continuous-time chirping to refine the signal further. The first network device 106 outputs the first chirped sequence pilot signal, which is now ready for transmission over the wireless channel. The second network device 116 outputs the second chirped sequence pilot signal, similarly, prepared for transmission.

[0086] A unique set of parameters ensures that the pilot signals from different network devices (i.e., the first network device 106 and the second network device 116) do not interfere with each other, enhancing signal clarity. The steps 202 to 204 are only illustrative, and other alternatives can also be provided where one or more steps are added, one or more steps are removed, or one or more steps are provided in a different sequence without departing from the scope of the claims herein.

[0087] FIG. 3 is a block diagram of a network device used for generating chirped sequence pilot signals, in accordance with an embodiment of the present disclosure. FIG. 3 is described in conjunction with FIG.1 and FIG.2. With reference to FIG. 3, there is shown a block diagram 300 of a network device 304, which is used for generating chirped sequence pilot signals. The network device 304 includes a chirped-sequence pilot parameter setter 306, a chirped- sequence pilots generator 308, a plurality of digital to analog converter (DAC) 310, such as a first DAC 310A, upto an nth DAC 310N, an antenna sub-system 312. The antenna sub-system 312 includes a plurality of antennas 314, such as a first antenna 314A, upto an nth antenna 314N.

[0088] The network device 304 is a communication component designed to handle the transmission and reception of data within a network. It includes transmitters and receivers equipped with multiple antennas, DACs, and advanced signal processing modules. The key features such as MIMO (multiple input multiple output) technology, adaptive modulation and coding, and chirped sequence pilot signal leading to better channel estimation and sensing performance.

[0089] The chirped-sequence pilot parameter setter 306 receives the assignment signalling and configures the following set of parameters such as time-frequency resources, which specifies when and on which frequencies the pilots will be transmitted, sequence type, which defines the type of sequence to be used (e.g., Zadoff-Chu, Gold sequence), sequence length which determines the length of the pilot sequence, sequence index as the specific identifier for the sequence, helping to differentiate it from others, chirp parameters that define how the chirping will be applied (e.g., chirp rate, frequency shifts).

[0090] The plurality of DAC 310 refers to multiple DAC units integrated within the network device 304. The DACs are electronic devices that convert digital signals (binary data) into analog signals (continuous signals) that can be processed by various analog devices such as amplifiers, radios, and other communication hardware.

[0091] The antenna sub-system 312 is responsible for the transmission of the generated chirped sequence pilot signal. The antenna sub-system 312 includes multiple antennas and associated circuitry, facilitating the efficient propagation of signals over the air.

[0092] The plurality of antennas 314 refers to a collection of multiple antennas integrated within antenna sub-system 312. The plurality of antennas 314 work together to enhance the performance of the network device 304 by improving signal quality, increasing data throughput, and enabling advanced transmission and reception techniques.

[0093] The network device 304 is configured to receive an assigned first set of parameters of a chirped sequence pilot received from a network controller device 104. The network controller device 104 (which manages network resources and operations) assigns a specific set of parameters for a chirped sequence pilot signal. The parameters are critical for the network device to generate the correct chirped sequence pilot signal for communication purposes. The network device 304 receives this assigned first set of parameters from the network controller device 104. These parameters include essential details such as sequence type, sequence length, chirp rate, cyclic shift, frequency shift, and other related configurations. Upon receiving the first set of parameters, the network device 304 configures its internal systems to use the first set of parameters.

[0094] The network device 304 is further configured to generate a chirped sequence pilot signal using the received assigned first set of parameters. It then generates the chirped sequence pilot signal based on the assigned parameters. This signal is used for various purposes, such as synchronization, channel estimation, or other communication tasks within the network.

[0095] The network controller device 104 assigns specific parameters 302 for generating chirped sequence pilot signals to the network device 304. The network device 304 sets the parameters in the chirped-sequence pilot parameter setter 306. The chirped- sequence pilots generator 308 uses the set of parameters to generate the chirped sequence pilot signals. The generated digital pilot signals are converted to analog signals by the DACs. The analog signals are transmitted through the antenna sub-system 312, which includes the plurality of antennas 314 for enhanced performance.

[0096] FIG. 4 is a flowchart depicting a method for operating a network controller device to generate chirped sequence pilot signals, in accordance with an embodiment of the present disclosure. FIG. 4 is explained in conjunction with FIGs 1 to 3. With reference to FIG. 4, there is shown a flowchart of a method 400 for operating the network device 304. The method 400 includes steps 402 to 404.

[0097] At step 402, the method 400 includes receiving the assigned first set of parameters of the chirped sequence pilot, received from the network controller device 104. The network device 304 establishes a communication link with the network controller device 104. The link can be over various network protocols such as Wi-Fi, Ethernet, or a cellular network. The network device 304 looks for incoming data transmissions from the network controller device. The network device 304 is prepared to receive a packet or message that contains the required parameters. When the network controller device 104 sends the data packet containing the first set of parameters, the network device 304 detects and receives this packet. The network device 304 parses the received data packet to extract the first set of parameters. The first set of parameters include values such as sequence length, scrambling identifier, random seed, Zadoff-Chu root, cyclic shift, frequency shift, and chirp rate. The network device 304 stores the extracted parameters in its memory or registers, making them available for the subsequent steps in the process. In some implementations, the network device 304 may send an acknowledgement back to the network controller device 104 to confirm that the parameters have been successfully received and stored.

[0098] At step 404, the method 400 includes generating a chirped sequence pilot signal using the received assigned first set of parameters. The network device 304 initializes the generation process by loading the received parameters into its processing unit. These parameters include the sequence length, scrambling identifier, random seed, Zadoff-Chu root, cyclic shift, frequency shift, and chirp rate.

[0099] In some implementations, using the Zadoff-Chu root parameter, the network device generates a base sequence. The Zadoff- Chu sequence is known for its good correlation properties, which help in distinguishing signals from different devices and reducing interference. The chirp rate parameter determines how quickly the frequency of the signal changes over time. The network device modulates the signal according to the specified chirp rate, producing a chirped signal that sweeps across a range of frequencies. Finally, the sequence is then processed through the DFT spread module the modulated chirped sequence pilot signal is output from the network device 304, ready for transmission. The modulated chirped sequence pilot signal can now be transmitted over the communication channel to perform tasks like channel estimation and synchronization.

[0100] The steps 402 to 404 are only illustrative, and other alternatives can also be provided where one or more steps are added, one or more steps are removed, or one or more steps are provided in a different sequence without departing from the scope of the claims herein.

[0101] FIG. 5 is a diagram is a flowchart depicting a method for operating the network device for channel estimation, in accordance with an embodiment of the present disclosure. With reference to FIG. 5, there is shown a flowchart of a method 500 for operating the network device 304. The method 500 includes step 502.

[0102] At step 502, the method 500 includes receiving a generated chirped sequence pilot signal and performing channel estimation based on the received generated chirped sequence pilot signal. The generated chirped sequence pilot signal has been generated according to the method 400. In accordance with an embodiment, the channel estimation is performed by feeding an output of an analog to digital converter to a chirped DFT spread OFDM receiver module which has a number of outputs defined by a sequence length value included in the respective assigned set of parameters. The channel estimation is performed in the OFDM receiver module that utilizes a chirped DFT-spread OFDM receiver module. The ADC converts the received analog signal into a digital signal, which translates the continuous-time signal (received over the air) into a discrete-time signal that digital circuits can process. The chirped DFT-spread OFDM receiver module processes the digital signal output from the ADC to perform channel estimation. The digital signal output from the ADC is fed into the chirped DFT-spread OFDM receiver module. The signal contains the pilot sequences that were transmitted for the purpose of channel estimation. The number of outputs from the receiver module is defined by the sequence length value. The value is part of the set of parameters assigned to the network device. The sequence length determines the number of points in the DFT (Discrete Fourier Transform) and IDFT (Inverse Discrete Fourier Transform) operations within the chirped DFT receiver module. The chirped DFT-spread OFDM receiver applies a de-chirping process to the received pilot sequences. The process involves removing the quadratic phase shift that was introduced during transmission. The de-chirped sequences are then transformed into the frequency domain using a DFT. The length of DFT is determined by the sequence length parameter.

[0103] By analyzing the frequency-domain representation of the pilot sequences, the receiver estimates the channel characteristics. The process of channel estimation characteristics involves measuring how the transmission channel has distorted the pilot sequences. The frequency-domain channel estimates are then converted back into the time domain using an IDFT, which helps in preparing the channel estimates for subsequent signal processing tasks. The output of the chirped DFT-spread OFDM receiver module consists of channel estimates that describe the transmission channel's effects. The receiver uses these estimates to equalize the received data signals, compensating for channel impairments like multipath fading and Doppler shifts. The ADC's role is to convert the received analog signal into a digital format that the digital receiver module can process.

[0104] In yet another implementation, the sequence length parameter directly impacts the DFT and IDFT operations, determining the number of points used in these transforms and thereby influencing the granularity and accuracy of the channel estimation. The chirped DFT process helps in spreading the signal across multiple subcarriers, making the channel estimation robust against frequency- selective fading and other channel impairments. By using the ADC to convert the analog signal to a digital signal and a chirped DFT-spread OFDM receiver module for processing, this embodiment ensures efficient and accurate channel estimation.

[0105] In accordance with an embodiment, channel estimation is performed by feeding an output of an analog to digital converter to a DFT spread OFDM receiver module which has a chirping defined by a cyclic or frequency shift values included in the respective assigned set of parameters.

[0106] The use of DFT-spread OFDM combined with chirping (defined by cyclic or frequency shift values) allows for more precise channel characterization. Precision is essential for accurately estimating the effects of the channel on the transmitted signals. The DFT operation provides high-resolution frequency domain representation, which is vital for identifying and compensating for channel impairments such as fading and interference. The cyclic or frequency shift values included in the chirping process help in mitigating multipath effects. Multipath propagation, where signals take multiple paths to reach the receiver, can cause severe signal degradation.

[0107] The unique chirping patterns and frequency shifts allow the receiver to better distinguish between overlapping signals, improving the overall signal-to-noise ratio (SNR) and leading to leading to better channel estimation and sensing performance. The ability to define chirping using cyclic or frequency shift values in the assigned set of parameters provides flexibility. Network controllers can dynamically adjust these parameters based on real-time channel conditions, optimizing performance. The method is scalable to different network sizes and configurations. It can be adapted to various environments, from low- mobility scenarios (like indoor Wi-Fi) to high-mobility scenarios (like vehicular communications). In accordance with an embodiment, the network device 304 that receives the generated chirped sequence pilot signal, and which performs channel estimation replaces the chirping with a continuous time dechirping performed before an analog to digital conversion takes place.

[0108] The step 502 is only illustrative, and other alternatives can also be provided where one or more steps are added, one or more steps are removed, or one or more steps are provided in a different sequence without departing from the scope of the claims herein.

[0109] FIG. 6 is an exemplary diagram that depicts the generation of a chirped sequence pilot signal by using the network device transmitter, in accordance with an embodiment of the present disclosure. FIG. 6 is explained in conjunction with FIGs. 1 to 5. With reference to Fig. 6, there is shown an exemplary diagram 600 that depicts the generation of a chirped sequence pilot signal by using the network device transmitter 602. The network device transmitter 602 includes a chirped DFT module 616 of a size “M”, an Inverse Discrete Fourier Transform (IDFT) module 618 and a digital to analog converter 620.

[0110] The chirped DFT module 616 is modification ofthe standard DFT- technique. The "chirped" aspect introduces additional phase rotations to create a chirp- like signal structure. The chirped DFT module 616 spreads the input data across subcarriers, similar to Single-Carrier Frequency Division Multiple Access (SC-FDMA) and introduces controlled frequency dispersion through chirping, which can be beneficial for sensing application.

[0111] The IDFT module 618 transforms a frequency-domain signal back into the time domain. It performs the inverse operation of the DFT (Discrete Fourier Transform). The IDFT module 618 has an N-point IDFT, meaning it processes N input points. The input to this IDFT includes the M points from the previous stage, i.e. the chirped DFT module 616, zero-padded to N points (where N > M). Zero-padding in the frequency domain (expanding from M to N points) results in interpolation in the time domain, effectively up sampling the signal. The IDFT is implemented using Fast Fourier Transform (FFT) algorithms for efficiency, especially when N is large.

[0112] The digital to analog converter 620 is an electronic device that converts a digital signal, comprising discrete numerical values, into a continuous-time analog signal. The functionality involves receiving a digital signal, typically in binary-coded discrete values, and converting these values into a continuous analog signal through several steps, such as decoding the digital values, converting each value into a corresponding voltage or current level in discrete steps, and applying a smoothing filter to remove high-frequency components, thereby creating a smooth continuous signal.

[0113] A pilot sequence 604 (denoted by p[m]) of length “M” includes a plurality of elements, such as a first element p[0], upto an nth element p[M-l], Each element of the pilot sequence 604 is multiplied by a corresponding complex exponential term. For example, the first element “p[OJ” is multiplied by “eA(-i2jtcOA2) and the nth element “p[M-l]” is multiplied by “eA(-i2jtc(M- 1)A2)”. The multiplication results in a modified sequence, which includes a plurality of modified elements 606, such as a first modified element 606A, up to nth modified element 606N. The multiplication applies a quadratic phase shift to each element of the pilot sequence. The plurality of modified elements of the modified sequence is fed into the chirped DFT module 616. The output of the DFT is then multiplied elementwise with another set of complex exponentials. For example, a first output is multiplied by “eA(i27t((2Ncmo)O) / N)” upto nth output is multiplied by “eA(i27t((2Ncmo) (M-l)) / N)”. The multiplication results in a plurality of outputs 608, such as a first output 608A, upto an nth output 608N. Further, the multiplication also applies a linear phase shift that depends on the index and the parameter mo The plurality of outputs 608 are then passed through the IDFT module 618. The IDFT module 618 produces a plurality of IDFT outputs 610, such as a first IDFT output 618A, upto an nth IDFT output 618N is produced. The IDFT module 618 spreads the signal across N subcarriers, generating the OFDM signal. The plurality of output of the IDFT frequency-domain sequence is then fed into a converting it back to the plurality of IDFT outputs 610 into the time domain. The digital to analog converter 620 converts the discrete-time digital signal, i.e., the plurality of the IDFT outputs 610 into a continuous-time analog signal. It bridges the digital processing domain with the analog transmission domain. Finally, the multiplication of the output from DAC is done with continuous- time chirp function (phno t) 612, which leads to a generated chirped sequence pilot signal 614.

[0114] Fig. 7 is an exemplary diagram that depicts the channel estimation process by using the network device receiver, in accordance with an embodiment of present disclosure. FIG. 7 is explained in conjunction with FIGs. 1 to 6. With reference to FIG. 7 there is shown an exemplary diagram 700 depicting a network device receiver 702. The network device receiver 702 includes an anti-aliasing filter 706, an analog-to-digital converter (ADC) 708, a serial-to-parallel (S / P) converter 710, and a DFT module 712.

[0115] The anti-aliasing filter 706 is a low-pass filter that allows frequencies below a specific cutoff frequency to pass through while attenuating frequencies above the cutoff. The cutoff frequency of the anti-aliasing filter 706 is chosen based on the Nyquist rate, which is half the sampling rate of the ADC 708.

[0116] The ADC 708 is a device that converts continuous analog signals into discrete digital signals and performs the conversion through sampling, quantization, and encoding, with key specifications such as resolution, sampling rate, and signal-to-noise ratio determining its performance and suitability for various applications.

[0117] The serial-to-parallel (S / P) converter 710 is an electronic circuit that converts data transmitted serially (one bit at a time) into parallel format (multiple bits simultaneously). Conversion is essential in digital communication systems and data processing applications where parallel data handling is more efficient or required by subsequent stages of processing.

[0118] The DFT module 712 transforms the received time-domain signal back into the frequency domain. .

[0119] An incoming signal 704 is first multiplied, i.e., mixed with a continuous version of the chirped sequence pilot signal 614 to generate a mixed signal 714. The mixing de-chirp the incoming signal 704, essentially reversing the chirping applied at the network device transmitter 602. The mixed signal 714 is then passed through the anti-aliasing filter 706. The anti-aliasing filter 706 removes high-frequency components that may cause aliasing during sampling. The anti-aliasing filter 706 generates a filtered signal 718. The filtered signal 718 is fed into the ADC 708. The ADC 708 samples the filtered signal 718. The sampling period “Ts” is noted, where (Bandwidth) * Ts =(M / N), where “M” is the number of useful samples, and “N” is the total number of samples.

[0120] The ADC 708 is used to convert the filtered signal 718 to a discrete-time digital signal 720. The discrete-time digital signal 720 is fed into the serial-to-parallel (S / P) converter 710. The serial-to-parallel (S / P) converter 710 converts the discrete-time digital signal 720 into a parallel discrete-time digital signal 722, to prepare the data for block processing in the DFT module 712. The parallel discrete-time digital signal 722 produced by the serial-to-parallel (S / P) converter 710 is fed into the DFT module 712. The DFT module 712 performs a DFT on the parallel discrete-time digital signal 722 and transforms it into the frequency domain. The output of the DFT produces a signal 724, which is used for channel estimation 726. The channel estimation 726 may involve various signal-processing techniques to extract information about the channel or environment.

[0121] Fig. 8 is an exemplary diagram that depicts the channel estimation process by using the network device receiver, in accordance with an embodiment of present disclosure. FIG. 8 is explained in conjunction with FIGs. 1 to 6. With reference to FIG. 8 there is shown an exemplary diagram 800 depicting a network device receiver 802. The network device receiver 802 includes an anti-aliasing filter 806, an analog-to-digital converter (ADC) 808, a serial-to-parallel (S / P) converter 810, discrete time dechirping module 812 and a DFT module 814. The anti-aliasing filter 806 is a low-pass filter that allows frequencies below a specific cutoff frequency to pass through while attenuating frequencies above the cutoff. The cutoff frequency of the anti-aliasing filter 806 is chosen based on the Nyquist rate associated with the pilot signal bandwidth.

[0122] The ADC 808 samples the received continuous time pilot signal at its input with a sampling rate smaller or equal than the bandwidth of the pilot signal.

[0123] The module 810 is S / P converter.

[0124] The discrete time de-chirping module 812 applies a phase rotation to the output of the ADC samples where the phase rotation is based on a polynomial phase rotation function of the output of the ADC samples index whose quadratic term is based on a chirp rate parameter and linear component of the polynomial is based on a frequency shift parameter.

[0125] The module 814 is a DFT module.

[0126] An incoming signal 804 related to a transmitted chirp-based pilot is first passed through the anti-aliasing filter 806. The antialiasing filter 806 removes high-frequency components that may cause aliasing during sampling. The cutoff frequency of the anti-aliasing filter 806 is chosen based on the Nyquist rate associated with the pilot signal bandwidth. The anti-aliasing filter 806 generates a filtered signal 816. The filtered signal 816 is fed into the ADC 808. The ADC 808 samples the filtered signal 816 with a sampling rate smaller or equal than the bandwidth of the pilot signal. The sampling rate “Fs” is noted, where (Bandwidth) / Fs = O, where “O” is a down sampling factor greater or equal to one.

[0127] The ADC 808 is used to convert the filtered signal 816 to a discrete-time digital signal 818. The discrete-time digital signal 818 is fed into the S / P converter 810. The S / P converter 810 converts the discrete-time digital signal 818 into a parallel discretetime digital signal 820, to prepare the data for block processing in the Discrete time de-chirping module 812. The parallel discrete-time digital signal 820 produced by the S / P converter 810 is fed into the discrete time de-chirping module 812. The discrete time de-chirping module 812 performs discrete time de-chirping on the parallel discrete- time digital signal 820 with a chirp rate that is O times larger than the chirp rate value of the transmitted pilot signal and with a frequency offset that is based on the frequency shift of the transmitted pilot and produces signal 822. The DFT module 814 performs a DFT on the signal 822. The output of the DFT produces a signal 824, which is used for channel estimation 824. The channel estimation 824 may involve various signal-processing techniques to extract information about the channel or environment.

[0128] FIG. 9 shows a flow chart for the transmission of chirped- sequence pilot for bi-static sensing in the downlink of a wireless communication system according to an embodiment of this disclosure. Similar to the previous embodiments, this wireless communication system comprises a network device 106 acting as a base station and another network device 106 acting as user equipment.

[0129] Optionally, the transmission procedure may be started with the user equipment 106 requesting (901), optionally using a radio resource configuration (RRC)message, chirped-sequence pilot resources for bi-static sensing. Then, the base station 106 signals (902) the parameters and time-frequency resources of chirped-sequence bi-static pilot optionally using a downlink control information (DCI) message. Then, the base station 106 transmits (903) chirped-sequence pilot on signalled time- frequency resources configured using the signalled parameters. FIG. 10 shows a flow chart for the transmission of chirped-sequence pilot for multi-static sensing in the downlink of a wireless communication system according to an embodiment of this disclosure. Similar to the previous embodiments, this wireless communication system comprises a network device 106 acting as a transmission point 1 (TRP 1), a network device 116 acting as a transmission point 2 (TRP 2) and another network device 106 acting as user equipment.

[0130] Optionally, the transmission procedure may be started with the user equipment 106 requesting (1001), optionally using a radio resource configuration message, chirped-sequence pilot resources for multi-static sensing. Then, the TRP 1 106 signals (1002), using a downlink control information message, two sets of parameters of chirped-sequence multi-static pilot optionally with two different frequency shift values. Then, the TRP 1 106 transmits (1003) chirped-sequence pilot using the first set of parameters and TRP 2 116 transmits (1004) chirped-sequence pilot using the second set of parameters.

[0131] There is provided a computer program comprising instructions that, when executed by a computer system, cause the computer system to implement the method 200, 400, 500. In an example, the instructions are implemented on the computer-readable media, which include, but are not limited to, Electrically Erasable Programmable Read-Only Memory (EEPROM), Random Access Memory (RAM), Read-Only Memory (ROM), Hard Disk Drive (HDD), Flash memory, a Secure Digital (SD) card, Solid-State Drive (SSD), a computer-readable storage medium, and / or CPU cache memory.

[0132] Modifications to embodiments of the present disclosure described in the foregoing are possible without departing from the scope of the present disclosure as defined by the accompanying claims. Expressions such as "including", "comprising", "incorporating", "have", "is" used to describe, and claim the present disclosure are intended to be construed in a non-exclusive manner, namely allowing for items, components or elements not explicitly described also to be present. Reference to the singular is also to be construed to relate to the plural. The word "exemplary" is used herein to mean "serving as an example, instance or illustration". Any embodiment described as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments or to exclude the incorporation of features from other embodiments. The word "optionally" is used herein to mean "is provided in some embodiments and not provided in other embodiments". It is appreciated that certain features of the present disclosure, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable combination or as suitable in any other described embodiment of the disclosure.

Claims

CLAIMS1. A method (200) of operating a network controller device (104), comprising steps of: assigning a first set of parameters of a chirped sequence pilot signal to a first network device (106); and assigning a second set of parameters of a chirped sequence pilot signal to a second network device (116), wherein the second set of parameters are different from the first set of parameters; wherein the first set of parameters are to be used by the first network device ( 106) to generate a first chirped sequence pilot signal, and wherein the second set of parameters are to be used by the second network device (116) to generate a second chirped sequence pilot signal.

2. A method (400) of operating a network device (304), comprising steps of: determining a first set of parameters of a chirped sequence pilot, and generating a chirped sequence pilot signal using the first set of parameters.

3. The method of claim 2, wherein the method further comprises: receiving, by the network device (304), an assigned first set of parameters of a chirped sequence pilot.

4. The method (200,400) of any preceding claim, wherein the generated chirped sequence pilot signal is output from a chirped Discrete Fourier Transform, DFT, spread Orthogonal Frequency-Division Multiplexing, OFDM, chirped DFT-s-OFDM, module.

5. The method of claim 4, wherein the chirped DFT-s-OFDM module applies to the sequence at its input a phase rotation, wherein the phase rotation is based on a polynomial function of the input index, and passes it to a DFT module, and applies to the output of the DFT module a phase rotation producing an intermediate sequence, wherein the phase rotation is based on a polynomial function of the output index and the linear component of the polynomial is based on a frequency shift parameter and a chirp rate parameter.

6. The method of claim 4, wherein the chirped DFT-s-OFDM module maps the samples of an intermediate sequence to consecutive inputs of an Inverse Discrete Fourier Transform, IDFT, and produces a chirped sequence by applying to the output of the IDFT module a discrete-time chirping by a phase rotation, wherein the discrete-time chirping is based on a polynomial phase rotation function of the intermediate sequence index whose quadratic term is based on a chirp rate parameter.

7. The method of claim 4, wherein the chirped sequence is mapped to a set of subcarriers at the input of an OFDM modulator.

8. The method (200,400) of any preceding claim, wherein the assigned set of parameters include values representing a sequence length, a scrambling identifier, a random seed, a Zadoff-Chu root, a cyclic shift, a frequency shift, and a chirp rate.

9. The method (200,400) of claim 4, wherein a or the OFDM module has a number of inputs defined by the sequence length value included in the respective assigned set of parameters.

10. The method (200,400) of claim 4, wherein a chirping is defined by the values of the cyclic shift or the frequency shift.

11. The method (200,400) of claim 1 or 2, wherein the generated chirped sequence pilot signal is generated by replacing a discrete-time chirping with a continuous-time chirping12. The method (200,400) of claim 11, wherein the continuous-time chirping is performed after a digital to analog converter.

13. A method (500) of operating a network device, comprising steps of receiving a chirp-based pilot signal and performing channel estimation based on a received chirp-based pilot signal.

14. The method of claim 9, wherein the chirp-based pilot signal is a chirped sequence pilot signal that has been generated according to a first set of parameters.

15. The method (500) of claim 13, wherein the channel estimation is performed by feeding an output of an analog to digital converter to a chirped Discrete Fourier Transform, DFT, spread Orthogonal Frequency-Division Multiplexing, OFDM, receiver module which has a number of outputs defined by a sequence length value included in the respective assigned set of parameters.

16. The method (500) of claim 13, wherein the channel estimation is performed by feeding an output of an analog to digital converter to a chirped Discrete Fourier Transform, DFT, spread Orthogonal Frequency-Division Multiplexing, OFDM, receiver module which has a chirping defined by a cyclic or frequency shift values included in the respective assigned set of parameters.

17. The method (500) of claim 13, wherein the network device that receives the generated chirped sequence pilot signal and which performs channel estimation replaces the chirping with a continuous time dechirping performed before an analog to digital conversion takes place.

18. The method (500) of claim 13, wherein the receiver performs channel estimation using a receiver circuit with reduced sampling rate to sample the received pilot signal.

19. The method (500) of claim 18, wherein the reduced sampling rate is less than or equal to the bandwidth of the pilot signal.

20. The method (500) of claim 18, wherein the receiver circuit operates without performing analog de-chirping.

21. A network device comprising means adapted for carrying out all the steps of the method according to any preceding method claim.

22. A computer program comprising instructions for carrying out all the steps of the method according to any preceding method claim, when said computer program is executed on a computer system.

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