A method and communication apparatus for signal synchronization applied to an ultra-wideband system

Abstract

The present application is applied to a wireless personal area network system based on ultra-wideband, including 802.15 series protocols, such as 802.15.4a protocol, 802.15.4z protocol or 802.15.4ab protocol, etc., and can also support IEEE 802.11ax next-generation Wi-Fi protocol, such as 802.11be, Wi-Fi 7 or ultra-high throughput, such as 802.11b. The present application provides a method and a communication device for signal synchronization applied to an ultra-wideband system. The method comprises: transmitting a narrowband signal, the PPDU of the narrowband signal comprising at least one pilot symbol, the pilot symbol being used by the PPDU for a receiving device to obtain time-frequency synchronization information of an ultra-wideband signal; and transmitting an ultra-wideband signal. By estimating the carrier frequency offset based on these inserted pilot symbols and the preamble in the PPDU, high-precision time-frequency synchronization of the ultra-wideband signal between the transmitting device and the receiving device can be achieved.

Description

[0001] This application is a divisional application. The original application has the application number 202210703945.4 and the original application date is June 21, 2022. The entire contents of the original application are incorporated herein by reference. Technical Field

[0002] This application relates to the field of ultra-wideband technology, and more specifically, to a method and communication device for signal synchronization applied to ultra-wideband systems. Background Technology

[0003] Ultra-wideband (UWB) technology is a wireless carrier communication technology that transmits and receives extremely narrow pulses with durations of nanoseconds or microseconds or less to achieve data transmission. UWB technology occupies a wide spectral range and has a very low radiative spectral density, giving it advantages such as strong multipath resolution, low power consumption, and high security.

[0004] Because UWB technology transmits data using extremely narrow pulses, it places high demands on the time-frequency synchronization of the transmitting and receiving devices. Although initial time-frequency synchronization information provided by narrow-band (NB) signals can assist in the time-frequency synchronization of UWB signals, the initial time-frequency synchronization information provided by existing NB signals has significant errors, which reduces the time-frequency synchronization accuracy of UWB signals. Summary of the Invention

[0005] This application provides a method and communication device for signal synchronization in ultra-wideband systems. By inserting at least one pilot symbol into the PPDU of the NB signal and estimating the carrier frequency offset based on the inserted pilot symbol and the original preamble in the PPDU, this method can support the estimation and compensation of carrier frequency offset during data reception, and the estimation accuracy of carrier frequency offset is higher, thereby achieving high-precision time-frequency synchronization of UWB signals between the transmitting and receiving devices.

[0006] In a first aspect, a method for synchronizing ultra-wideband signals is provided, comprising: transmitting a narrowband signal, wherein the physical layer protocol data unit (PPDU) of the narrowband signal includes at least one pilot symbol, the at least one pilot symbol being used by a receiving device to acquire time-frequency synchronization information of the narrowband signal, and the at least one pilot symbol being a symbol agreed upon by the transmitting device and the receiving device; transmitting an ultra-wideband signal; wherein the time-frequency synchronization information of the narrowband signal is used by the receiving device to acquire time-frequency synchronization information of the ultra-wideband signal.

[0007] It should be understood that a narrowband signal can be understood as a signal with a bandwidth less than or equal to the first threshold, and an ultra-wideband signal can be understood as a signal with a bandwidth greater than or equal to the second threshold, where the second threshold is greater than the first threshold.

[0008] By inserting at least one pilot symbol into the PPDU of the narrowband signal, and estimating the carrier frequency offset based on the inserted pilot symbol and the original preamble in the PPDU, the estimation and compensation of the carrier frequency offset during data reception can be supported, and the estimation accuracy of the carrier frequency offset is higher, thereby achieving high-precision time-frequency synchronization of UWB signals between the transmitting and receiving devices.

[0009] In conjunction with the first aspect, in some implementations of the first aspect, the physical layer protocol service data unit (PSDU) of the physical layer protocol data unit (PPDU) includes at least one pilot symbol.

[0010] Specifically, the number of bytes in the PDSU of the PPDU of the narrowband signal is variable. By embedding at least one pilot symbol in the PSDU of the PPDU of the narrowband signal for the receiving device to obtain the time-frequency synchronization information of the narrowband signal, the carrier frequency offset estimation and compensation can be achieved during data reception without much modification to the PPDU frame structure. Moreover, the estimation accuracy of the carrier frequency offset is higher, thereby achieving high-precision time-frequency synchronization of the UWB signal between the transmitting and receiving devices.

[0011] In conjunction with the first aspect, in some implementations of the first aspect, each pilot symbol includes M bits of 0, where M is an integer multiple of 4.

[0012] In conjunction with the first aspect, in some implementations of the first aspect, narrowband signals and ultra-wideband signals share a common local clock.

[0013] Specifically, narrowband signals and ultra-wideband signals share a common local clock. This allows the receiving device to obtain the time-frequency synchronization information of the ultra-wideband signal based on the time-frequency synchronization information of the narrowband signal it receives, thereby achieving time-frequency synchronization between the receiving and transmitting devices in the ultra-wideband signal.

[0014] Secondly, a method for synchronizing ultra-wideband signals is provided, comprising: receiving a narrowband signal, wherein the physical layer protocol data unit of the narrowband signal includes at least one pilot symbol, the pilot symbol being used by the receiving device to obtain time-frequency synchronization information of the narrowband signal, and the pilot symbol being a symbol agreed upon by the transmitting device and the receiving device; receiving an ultra-wideband signal; and obtaining time-frequency synchronization information of the ultra-wideband signal based on the time-frequency synchronization information of the narrowband signal.

[0015] In conjunction with the second aspect, in some implementations of the second aspect, the physical layer service data unit of the physical layer protocol data unit includes at least one pilot symbol.

[0016] In conjunction with the second aspect, in some implementations of the second aspect, each pilot symbol includes M bits of 0, where M is an integer multiple of 4.

[0017] In conjunction with the second aspect, in some implementations of the second aspect, narrowband signals and ultra-wideband signals share a common local clock.

[0018] Thirdly, a communication device is provided, comprising: a transmitting unit for transmitting a narrowband signal, wherein the physical layer protocol data unit of the narrowband signal includes at least one pilot symbol, the at least one pilot symbol being used by a receiving device to acquire time-frequency synchronization information of the narrowband signal, and the at least one pilot symbol being a symbol agreed upon by the communication device and the receiving device; the transmitting unit is further configured to transmit an ultra-wideband signal; wherein the time-frequency synchronization information of the narrowband signal is used by the receiving device to acquire time-frequency synchronization information of the ultra-wideband signal.

[0019] In conjunction with the third aspect, in some implementations of the third aspect, the physical layer service data unit of the physical layer protocol data unit includes at least one pilot symbol.

[0020] In conjunction with the third aspect, in some implementations of the third aspect, the number of pilot symbols is related to the number of bytes of the physical layer service data unit.

[0021] In conjunction with the third aspect, in some implementations of the third aspect, each pilot symbol includes M bits of 0, where M is an integer multiple of 4.

[0022] In conjunction with the third aspect, in some implementations of the third aspect, narrowband signals and ultra-wideband signals share a common local clock.

[0023] Fourthly, a communication device is provided, comprising: a receiving unit for receiving a narrowband signal, wherein the physical layer protocol data unit of the narrowband signal includes at least one pilot symbol, the pilot symbol being used by the communication device to obtain time-frequency synchronization information of the narrowband signal, and the pilot symbol being a symbol agreed upon by the transmitting device and the communication device; the receiving unit is further configured to receive an ultra-wideband signal; and a processing unit for obtaining time-frequency synchronization information of the ultra-wideband signal based on the time-frequency synchronization information of the narrowband signal.

[0024] In conjunction with the fourth aspect, in some implementations of the fourth aspect, the physical layer service data unit of the physical layer protocol data unit includes at least one pilot symbol.

[0025] In conjunction with the fourth aspect, in some implementations of the fourth aspect, each pilot symbol includes M bits of 0, where M is an integer multiple of 4.

[0026] In conjunction with the fourth aspect, in some implementations of the fourth aspect, narrowband signals and ultra-wideband signals share a common local clock.

[0027] Fifthly, a communication device is provided, including a processor and a memory. Optionally, it may also include a transceiver. The memory stores a computer program, the processor invokes and runs the computer program stored in the memory, and controls the transceiver to send and receive signals, so that the communication device performs the methods described in the first aspect, or any possible implementation thereof.

[0028] A sixth aspect provides a communication device including a processor and a memory. Optionally, it may also include a transceiver. The memory stores a computer program, the processor invokes and runs the computer program stored in the memory, and controls the transceiver to send and receive signals, causing the communication device to perform the methods described in the second aspect, or any possible implementation thereof.

[0029] A seventh aspect provides a communication device, including a processor and a communication interface, the communication interface being configured to receive data and / or information and transmit the received data and / or information to the processor, the processor processing the data and / or information, and the communication interface being further configured to output the processed data and / or information such that a method as described in the first aspect, or any possible implementation thereof, is executed.

[0030] Eighthly, a communication device is provided, comprising a processor and a communication interface, the communication interface being configured to receive (or input) data and / or information and to transmit the received data and / or information to the processor, the processor processing the data and / or information, and the communication interface being further configured to output the processed data and / or information such that a method as described in the second aspect, or any possible implementation thereof, is executed.

[0031] A ninth aspect provides a communication device including at least one processor coupled to at least one memory, the at least one processor being configured to execute a computer program or instructions stored in the at least one memory to cause the communication device to perform a method as described in the first aspect, or any possible implementation thereof.

[0032] A tenth aspect provides a communication device including at least one processor coupled to at least one memory, the at least one processor being configured to execute a computer program or instructions stored in the at least one memory to cause the communication device to perform a method as described in the second aspect, or any possible implementation thereof.

[0033] Eleventhly, a computer-readable storage medium is provided, wherein computer instructions are stored therein, which, when executed on a computer, cause a method as described in the first aspect, or any possible implementation thereof, to be performed.

[0034] In a twelfth aspect, a computer-readable storage medium is provided, wherein computer instructions are stored therein, which, when executed on a computer, cause the method as described in the second aspect, or any possible implementation thereof, to be performed.

[0035] In a thirteenth aspect, a computer program product is provided, the computer program product comprising computer program code that, when the computer program code is run on a computer, causes a method as described in the first aspect, or any possible implementation thereof, to be executed.

[0036] In a fourteenth aspect, a computer program product is provided, the computer program product comprising computer program code that, when the computer program code is run on a computer, causes a method as described in the second aspect, or any possible implementation thereof, to be executed.

[0037] In a fifteenth aspect, a wireless communication system is provided, including a communication device as described in the third aspect and a communication device as described in the fourth aspect. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the PPDU100 narrowband system.

[0039] Figure 2 This is an architecture diagram of the communication system 200 applicable to embodiments of this application.

[0040] Figure 3 This is an interactive flowchart of a signal synchronization method 300 applied to an ultra-wideband system according to an embodiment of this application.

[0041] Figure 4 This is a schematic diagram of the narrowband signal PPDU400 according to an embodiment of this application.

[0042] Figure 5 This is a schematic diagram of the simulation results of the CFO based on PPDU400.

[0043] Figure 6 This is a schematic diagram of the internal structure of the transmitting / receiving device.

[0044] Figure 7 This is a schematic block diagram of a communication device 700 according to an embodiment of this application.

[0045] Figure 8 This is a schematic structural diagram of a communication device 800 according to an embodiment of this application. Detailed Implementation

[0046] The technical solutions in this application will now be described with reference to the accompanying drawings.

[0047] The technical solution of this application can be applied to wireless personal area networks (WPANs). Currently, WPANs adopt the IEEE 802.15 standard. WPANs can be used for communication between digital auxiliary devices such as telephones, computers, and peripherals within a small range. Technologies supporting wireless personal area networks include Bluetooth, ZigBee, Ultra Wideband (UWB), Infrared Data Association (IrDA) connectivity, and Home Radio Frequency (HomeRF). From a network architecture perspective, WPANs are located at the bottom layer of the overall network architecture, used for wireless connections between devices within a small range, i.e., point-to-point short-range connections, and can be considered short-range wireless communication networks. Depending on the application scenario, WPANs are further divided into high-rate (HR) WPANs and low-rate (LR) WPANs. HR-WPANs can be used to support various high-rate multimedia applications, including high-quality audio and video delivery, multi-megabyte music and image document transmission, etc. LR-WPAN can be used for general business in daily life.

[0048] In WPAN, devices are categorized into full-function devices (FFDs) and reduced-function devices (RFDs) based on their communication capabilities. FFDs can communicate with each other and with each other. RFDs cannot communicate directly; they can only communicate with FFDs or forward data through an FFD. The FFD associated with an RFD is called its coordinator. RFDs are primarily used for simple control applications, such as light switches and passive infrared sensors. They transmit relatively little data, consume minimal transmission and communication resources, and have low cost. The coordinator can also be called a personal area network (PAN) coordinator or central control node. The PAN coordinator is the master control node of the entire network, and there is typically only one PAN coordinator in each ad hoc network. It has functions such as membership management, link information management, and packet forwarding.

[0049] Optionally, the device (e.g., a transmitting device or a receiving device) in the embodiments of this application can be a device that supports the 802.15 series, such as a device that supports 802.15.4a and 802.15.4z, as well as a device that supports various WPAN standards, such as those currently under discussion or subsequent versions.

[0050] Optionally, this application can be applied to UWB-based wireless personal area network systems, including 802.15 series protocols, such as 802.15.4a, 802.15.4z, or 802.15.4ab. It can also support next-generation Wi-Fi protocols such as IEEE 802.11ax, Wi-Fi 7, or EHT, as well as 802.11b.

[0051] In this embodiment, the aforementioned device may be a communication server, router, switch, bridge, computer, mobile phone, smart home device, vehicle communication device, etc.

[0052] In this embodiment, the device includes a hardware layer, an operating system layer running on top of the hardware layer, and an application layer running on the operating system layer. The hardware layer includes hardware such as a central processing unit (CPU), a memory management unit (MMU), and memory (also called main memory). The operating system can be any one or more computer operating systems that implement business processing through processes, such as Linux, Unix, Android, iOS, or Windows. The application layer includes applications such as browsers, address books, word processing software, and instant messaging software. Furthermore, this embodiment does not specifically limit the structure of the execution entity of the method provided in this embodiment, as long as it can communicate according to the method provided in this embodiment by running a program that records the code of the method provided in this embodiment. For example, the execution entity of the method provided in this embodiment can be an FFD or an RFD, or a functional module in an FFD or RFD that can call and execute a program.

[0053] Furthermore, various aspects or features of this application can be implemented as methods, apparatus, or articles of manufacture using standard programming and / or engineering techniques. The term "article of manufacture" as used herein encompasses a computer program accessible from any computer-readable device, carrier, or medium. For example, computer-readable media may include, but are not limited to: magnetic storage devices (e.g., hard disks, floppy disks, or magnetic tapes), optical discs (e.g., compact discs (CDs), digital versatile discs (DVDs), etc.), smart cards, and flash memory devices (e.g., erasable programmable read-only memory (EPROMs), cards, sticks, or key drives, etc.). Additionally, the various storage media described herein may represent one or more devices and / or other machine-readable media for storing information. The term "machine-readable medium" may include, but is not limited to, wireless channels and various other media capable of storing, containing, and / or carrying instructions and / or data.

[0054] The technical solutions of this application can also be applied to wireless local area network systems such as Internet of Things (IoT) networks or vehicle-to-everything (V2X) networks. Of course, the embodiments of this application can also be applied to other possible communication systems, such as Long Term Evolution (LTE) systems, LTE Frequency Division Duplex (FDD) systems, LTE Time Division Duplex (TDD) systems, Universal Mobile Telecommunication System (UMTS), Worldwide Interoperability for Microwave Access (WiMAX) systems, 5th generation (5G) systems, and future 6th generation (6G) systems.

[0055] The communication systems described above that are applicable to this application are merely illustrative examples, and the communication systems applicable to this application are not limited to these. They will be uniformly described here and will not be repeated below.

[0056] In WPAN, UWB technology uses nanosecond-level non-sinusoidal narrow pulses to transmit data, thus occupying a wide spectral range. Due to its narrow pulses and extremely low radiation spectral density, UWB technology has advantages such as strong multipath resolution, low power consumption, and strong security.

[0057] Currently, UWB technology has been incorporated into the IEEE 802 series of wireless standards, and the UWB-based WPAN standard IEEE 802.15.4a and its evolved version IEEE 802.15.4z have been released. The development of the next-generation UWB WPAN standard, 802.15.4ab, is also on the agenda.

[0058] Since UWB technology transmits data by sending and receiving extremely narrow pulses with durations in the nanosecond or microsecond range, synchronization between the transmitting and receiving devices is crucial. This synchronization can be understood as follows: the transmitting device sends its physical layer protocol data units (PPDUs) as pulse signals, and the receiving device determines which pulse signal, from among the received signals, marks the beginning of the PPDU it intends to receive; alternatively, it can be understood as the receiving device compensating for the carrier frequency discrepancy between the transmitting and receiving devices.

[0059] Currently, time-frequency synchronization of UWB signals by receiving devices is mainly achieved by detecting the synchronization header (SHR) in the PPDU of the narrow band (NB) signal transmitted by the transmitting device. Specifically, the NB signal initially sent by the transmitting device to the receiving device provides initial time-frequency synchronization information for the subsequent UWB signal transmitted by the transmitting device to the receiving device. The receiving device can determine the starting position of the PPDU of the UWB signal to be received and the carrier frequency deviation between the transmitting and receiving devices by performing correlation detection on the SHR of the NB signal PPDU, and then compensate for the carrier frequency offset. The structure of the NB signal PPDU can be found in [reference needed]. Figure 1 .

[0060] Figure 1 This is a structural diagram of the PPDU100 narrowband system. (Example) Figure 1 As shown, PPDU100 includes SHR, physical header (PHR), and physical layer (PHY) payload field. The PHY payload field can also be understood as a physical layer protocol service data unit (PSDU). Additionally, SHR includes a preamble and a start-of-frame delimiter (SFD).

[0061] Specifically, the preamble consists of 32 bits of 0 and is used for symbol and chip synchronization. The SFD is a fixed 10100111, used to determine the end of the preamble and the beginning of the data frame. The PHR indicates the length of the PSDU, and its value can be 1-127, representing the number of bytes in the PSDU from 1 to 127.

[0062] Specifically, the NB signal used to assist in the time-frequency synchronization of the UWB signal can be transmitted using offset-quadrature phase shift keying (O-QPSK) modulation. To enhance the robustness of the system, 4-bit encoded (or unencoded) bit information can be mapped onto an 8- or 32-bit spreading code sequence before O-QPSK modulation, and the time-frequency synchronization information of the transmitted information bits can be determined by receiving the spread sequence. For example: Data bit in PPDU → Data symbol → Chip → O-QPSK modulation → Modulated data Specifically, every four data bits in the PPDU100 are mapped to a data symbol, and each data symbol is mapped to a spreading code sequence consisting of 32 chips. The mapping relationship between data symbols and spreading code sequences is shown in Table 1.

[0063] Table 1

[0064] As mentioned earlier, the preamble in the PPDU100 of the NB signal consists of 32 bits of 0, which can be mapped to 8 data symbols, specifically corresponding to data symbol 0 in Table 1. In other words, the preamble in the PPDU100 can be mapped to 8 identical spreading code sequences corresponding to data symbol 0. Furthermore, the carrier frequency offset (CFO) performed by the receiving device based on the preamble in the PPDU100 of the transmitting device's NB signal can be expressed as: (1) in, The preamble is used to represent CFO, and T represents the time interval between two chips with the same value, where the two chips are located at the same position in the two spreading code sequences corresponding to the periodic data symbols. As mentioned earlier, the preamble can be mapped to eight identical spreading code sequences. Therefore, the maximum value of T is... The minimum value is . Used to indicate chip duration. Additionally, the "7" above indicates the number of spreading code sequences between the first and eighth spreading code sequences corresponding to data symbol 0. The "1" above indicates the number of spreading code sequences between the first and second spreading code sequences corresponding to data symbol 0.

[0065] As can be seen from the above formula, the receiving device estimates the preamble of the NB signal through the PPDU100. The absolute value of the precision of f satisfies the following condition: (2) It is understandable that the NB signal and UWB signal from either the transmitting or receiving device share the same local clock. In other words, the NB signal transmitted by the transmitting device and the UWB signal received by the receiving device share the same local clock. Specifically, for the transmitting device, the transmitted NB signal and UWB signal share the same local clock; for the receiving device, the received NB signal and UWB signal share the same local clock. However, there is a frequency discrepancy between the transmitting and receiving devices. For example, if the frequency of the NB signal transmitted by the transmitting device is F1, and the frequency of the NB signal received by the receiving device is F2, then |F2 - F1| = The transmitting device sends a UWB signal at frequency F3, and the receiving device receives a UWB signal at frequency F4. |F4-F3|=A* Where A is a fixed parameter. Therefore, the receiving device can obtain the time-frequency synchronization information of the received UWB signal based on the time-frequency synchronization information of the NB signal received from the transmitting device.

[0066] As can be seen from formula (2), the result obtained by the receiving device for CFO estimation based on the preamble in the PPDU100 of the transmitting device's NB signal will be affected by... The impact, if If the error is too small, it will result in a large residual deviation, which will make the time-frequency synchronization of the UWB signal based on the NB signal inaccurate between the transmitting and receiving devices.

[0067] In view of the above-mentioned technical problems, this application provides a method and communication device for signal synchronization in ultra-wideband systems. By inserting at least one pilot symbol into the PPDU of the NB signal and estimating the carrier frequency offset based on the inserted pilot symbol and the original preamble in the PPDU, the method can support the estimation and compensation of carrier frequency offset during data reception. Moreover, the estimation accuracy of CFO is higher, thereby achieving high-precision time-frequency synchronization of UWB signals between the transmitting and receiving devices.

[0068] The following description, in conjunction with the accompanying drawings, illustrates the method for UWB signal synchronization according to embodiments of this application and its application scenarios.

[0069] Figure 2 This is an architecture diagram of the communication system 200 applicable to embodiments of this application. For example... Figure 2As shown, the communication system 200 includes at least one transmitting device 210 and one receiving device 220. The transmitting device 210 and the receiving device 220 can communicate via UWB technology or NB technology. The transmitting device 210 and the receiving device 220 may include a UWB signal processing module and an NB signal processing module. For example, the transmitting device 210 includes a UWB signal transmitting module and an NB signal transmitting module. The receiving device 220 includes a UWB signal receiving module and an NB signal receiving module.

[0070] Understandable Figure 2 The communication system 200 is described using only one transmitting device and one receiving device as an example, but the communication system 200 is not limited to including more other devices; for example, it may also include more receiving devices. Furthermore, in this embodiment, the transmitting device refers to a device that transmits UWB signals, and the receiving device refers to a device that receives UWB signals.

[0071] Optionally, the transmitting and receiving devices can have a variety of possible application scenarios. For example, in a star topology or a point-to-point topology, the data communication between the central control node and one or more other devices in a star topology is also applicable to the communication between different devices in a point-to-point topology.

[0072] Furthermore, the signal synchronization method for ultra-wideband systems provided in this application is also applicable to any scenario that may require UWB signal synchronization, and the embodiments of this application are not limited thereto.

[0073] Figure 3 This is an interactive flowchart of a signal synchronization method 300 applied to an ultra-wideband system according to an embodiment of this application. Figure 3 The method flow can be executed by the transmitting / receiving device, or by a module and / or device (e.g., a chip or integrated circuit) with corresponding functions installed in the transmitting / receiving device, without limitation. The following embodiments use a transmitting / receiving device as an example for illustration. Method 300 includes: S310. The transmitting device transmits an NB signal. The PPDU of the NB signal includes at least one pilot symbol. The at least one pilot symbol is used by the receiving device to obtain the time and frequency synchronization information of the NB signal.

[0074] It is understandable that pilot symbols are symbols agreed upon between transmitting and receiving devices.

[0075] Alternatively, the pilot symbols can also be predefined symbols in the protocol.

[0076] S320, the receiving device receives the NB signal.

[0077] For example, the transmitting device can be Figure 2 The transmitting device 210 shown can be a receiving device. Figure 2 The receiving device 220 shown.

[0078] It should be understood that a narrowband signal can be understood as a signal with a bandwidth less than or equal to the first threshold, and an ultra-wideband signal can be understood as a signal with a bandwidth greater than or equal to the second threshold, where the second threshold is greater than the first threshold.

[0079] Specifically, the transmitting device can send NB signals through the Tx NB module. Correspondingly, the receiving device can receive the NB signals through the Rx NB module.

[0080] By receiving and processing the NB signal, the receiving device can obtain the time and frequency synchronization information of the NB signal. In other words, the receiving device can achieve time and frequency synchronization with the NB signal.

[0081] For example, the receiving device can process the NB signal through the NB signal processing module to obtain the time-frequency synchronization information of the NB signal. Further, the NB signal processing module of the receiving device provides the obtained time-frequency synchronization information of the NB signal to the UWB signal processing module of the receiving device.

[0082] In the technical solution of this application, the receiving device receives and processes the NB signal from the transmitting device to achieve time-frequency synchronization with the transmitting device on the NB signal. It can be considered that the NB signal provides time-frequency synchronization information to the receiving device. Based on this time-frequency synchronization information, the receiving device then estimates the time-frequency synchronization information of the UWB signal from the transmitting device.

[0083] S330, The transmitting device sends a UWB signal.

[0084] For example, the transmitting device can transmit UWB signals through a Tx UWB module.

[0085] S340, the receiving device receives UWB signals.

[0086] S350: The receiving device obtains the time-frequency synchronization information of the UWB signal based on the time-frequency synchronization information of the NB signal.

[0087] Specifically, the receiving device obtains the time-frequency synchronization information of the UWB signal based on the time-frequency synchronization information of the NB signal. That is, the receiving device can obtain more accurate time-frequency synchronization information of the UWB signal based on the time-frequency synchronization information provided by the NB signal.

[0088] As shown in S320, the NB signal processing module of the receiving device provides the time-frequency synchronization information of the obtained NB signal to the UWB signal processing module of the receiving device. Based on this, the UWB signal processing module of the receiving device obtains more accurate time-frequency synchronization information of the UWB signal according to the time-frequency synchronization information of the NB signal provided by the NB signal processing module.

[0089] As can be seen, this application proposes a "two-step time-frequency synchronization scheme for UWB signals": Step 1: The transmitting device first sends the NB signal, and the receiving device can obtain the initial time and frequency synchronization information; Step 2: The transmitting device sends the UWB signal after the NB signal.

[0090] Optionally, the time-frequency synchronization information of the NB signal may include time synchronization information and frequency synchronization information.

[0091] Specifically, the PPDU of the NB signal received by the receiving device includes at least one pilot symbol, and this at least one pilot symbol is used by the receiving device to obtain more accurate time and frequency synchronization information of the NB signal. For example, by adding a pilot symbol, T in formula (2) max The value is larger, so the CFO estimation accuracy will be higher, and the time-frequency synchronization information of the UWB signal is obtained based on the obtained time-frequency synchronization information of the NB signal. For details on the structure of the PPDU including at least one pilot symbol, please refer to [link to relevant documentation]. Figure 4 .

[0092] Optionally, this application does not limit the specific form of the NB signal. For example, it does not limit the frequency, bandwidth, frame format, or modulation method of the NB signal. For example, the NB signal can be a Zigbee / Bluetooth signal, a frequency in the 2.4GHz industrial scientific medical (ISM) band, using a bandwidth of 1MHz or 2MHz, or employing O-QPSK modulation, etc.

[0093] By inserting at least one pilot symbol into the PPDU of the NB signal, and estimating the CFO based on the inserted pilot symbol and the original preamble in the PPDU, the estimation and compensation of CFO during data reception can be supported, and the estimation accuracy of CFO is higher. This enables high-precision time-frequency synchronization of UWB signals between the transmitting and receiving devices.

[0094] The following section will describe the structure of a PPDU including at least one pilot symbol, along with related simulation results, in conjunction with the accompanying drawings.

[0095] Figure 4This is a schematic diagram of the structure of PPDU400 according to an embodiment of this application. Figure 4 As shown, the PSDU of PPDU400 includes at least one pilot symbol. Exemplarily, the at least one pilot symbol may be distributed periodically or aperiodically among the PSDUs.

[0096] One possible implementation is to correlate the number of pilot symbols with the number of bytes in the PSDU. See Table 2 for details.

[0097] Table 2

[0098] In Table 2, when the number of bytes in the PSDU is ≥95, the number of pilot symbols can be 4. When the number of bytes in the PSDU is between 62 and 95, the number of pilot symbols can be 3. When the number of bytes in the PSDU is between 31 and 62, the number of pilot symbols can be 2. When the number of bytes in the PSDU is less than 31, the number of pilot symbols can be 1. It should be understood that the content shown in Table 2 is for illustrative purposes only.

[0099] One possible implementation involves periodically distributing pilot symbols within the PSDU. The position of the pilot symbols is determined by an initial offset and a periodic interval. The initial offset refers to the number of symbols between the first pilot symbol and the starting position of the PSDU.

[0100] Optionally, the interval period of the pilot symbols is fixed, that is, the pilot symbols are periodically inserted into the PSDU.

[0101] Specifically, the number of bytes in the PDSU of the PPDU of the narrowband signal is variable. By embedding at least one pilot symbol in the PSDU of the PPDU of the narrowband signal for the receiving device to obtain the time-frequency synchronization information of the narrowband signal, the carrier frequency offset estimation and compensation can be achieved during data reception without much modification to the structure of the PPDU. Moreover, the estimation accuracy of the carrier frequency offset is higher, thereby achieving high-precision time-frequency synchronization of the UWB signal between the transmitting and receiving devices.

[0102] In one possible implementation, each pilot symbol comprises M bits, where M is an integer multiple of 4, for example, M = 4, 8, 12...

[0103] In one possible implementation, each pilot symbol includes M bits. These M bits can be all 0 bits, all 1 bits, or a combination of both; this embodiment does not impose any limitations.

[0104] Optionally, the bits constituting the pilot symbol can remain unchanged within a PPDU data packet.

[0105] Figure 5 This is a schematic diagram illustrating the simulation results of a CFO based on PPDU400. (Example) Figure 5 As shown, in an additive white Gaussian noise (AWGN) channel, the number of PSDU bytes in PPDU400, including pilot symbols, is 127, and each pilot symbol consists of 4 bits of 0. Figure 5 The horizontal axis represents the power ratio of each chip to the background noise (in decibels (dB)), and the vertical axis represents the bit error rate at the receiver. Figure 5 Simulation results are presented for CFO estimation based on the preamble, as well as for CFO estimation based on the preamble and different numbers of inserted pilot symbols. See details in [link to documentation]. Figure 5 .

[0106] Specifically, Figure 5 The different curves in the figure represent the decoding results based on different CFO estimation methods. Among them, Figure 5 The solid curves marked with an asterisk (*) represent the decoding results of the CFO estimation method based on the preamble; the solid curves marked with a plus sign (+) represent the decoding results of the CFO estimation method based on the preamble and four pilot symbols (each pilot symbol consisting of four all-zero bits); the dashed curves marked with a plus sign (+) represent the decoding results of the CFO estimation method based on the preamble and four pilot symbols (each pilot symbol consisting of eight all-zero bits); the solid curves marked with a triangle (△) represent the decoding results of the CFO estimation method based on the preamble and six pilot symbols (each pilot symbol consisting of four all-zero bits); and the dashed curves marked with a triangle (△) represent the decoding results of the CFO estimation method based on the preamble and six pilot symbols (each pilot symbol consisting of eight all-zero bits). The decoding results of the CFO estimation method based on 8 bits of all zeros are shown in the figure. The solid curve “□” represents the decoding result of the CFO estimation method based on the preamble and 4 pilot symbols (each pilot symbol consists of 4 bits of all zeros). The dashed curve “□” represents the decoding result of the CFO estimation method based on the preamble and 6 pilot symbols (each pilot symbol consists of 8 bits of all zeros). The solid curve “☆” represents the decoding result of the CFO estimation method based on the preamble and 8 pilot symbols. The dashed curve “☆” represents the decoding result of the CFO estimation method based on the preamble and 10 pilot symbols (each pilot symbol consists of 4 bits of all zeros).

[0107] A comparison of different curves shows that the decoding results of the CFO estimation method based on the preamble are comparable to those of the CFO estimation methods based on the preamble and 4 pilot symbols, as well as the CFO estimation methods based on the preamble and 4 pilot symbols, and the CFO estimation methods based on the preamble and 6 pilot symbols, all under the same bit error rate, for example, 10. -3Simulation results showing a lower chip-to-background noise power ratio for CFO estimation based on multiple inserted pilot symbols and preamble indicate that CFO estimation based on multiple inserted pilot symbols and preamble has better performance and higher accuracy. This verifies that by inserting at least one pilot symbol into the PPDU of the NB signal and estimating CFO based on the inserted pilot symbol and the original preamble in the PPDU, CFO estimation and compensation can be supported during data reception. This can improve the accuracy of CFO estimation and thus achieve high-precision time-frequency synchronization of UWB signals between transmitting and receiving devices.

[0108] One possible implementation uses 4 or 6 pilot symbols. Each pilot symbol consists of 4 bits of all zeros. This allows for a balance between time-frequency synchronization performance and resource overhead.

[0109] The communication apparatus of the present application embodiments will be described below with reference to the accompanying drawings.

[0110] Figure 6 This is a schematic diagram of the internal structure of the transmitting / receiving device. For example... Figure 6 As shown, taking a receiving device as an example, the receiving device may include an NB signal processing module and a UWB signal processing module. The NB signal processing module processes the NB signal received from the transmitting device via the radio frequency module; the UWB signal processing module processes the UWB signal received from the transmitting device via the radio frequency module. Furthermore, the NB signal processing module and the UWB signal processing module can exchange data and / or information. For example, the NB signal processing module may send the coarse time-frequency synchronization information obtained by processing the received NB signal from the transmitting device to the UWB signal processing module. The transmitting device works similarly and will not be described further.

[0111] Figure 7 This is a schematic block diagram of a communication device 700 according to an embodiment of this application. Figure 7 As shown, the communication device 700 includes a processing unit 710 and a receiving unit 720.

[0112] Optionally, the communication device 700 may correspond to the receiving device in the embodiments of this application.

[0113] At this time, each unit of the communication device 700 is used to perform the following functions: Processing unit 710 is used for: It processes narrowband signals and is used to obtain the time-frequency synchronization information of UWB signals based on the time-frequency synchronization information of NB signals. The receiving unit 720 is used to receive NB signals and UWB signals.

[0114] Optionally, in one embodiment, the receiving unit 720 is configured to receive the UWB signal according to the time-frequency synchronization information of the NB signal; In addition, there is a processing unit 710, which is used to detect the UWB signal and obtain the time-frequency synchronization information of the UWB signal.

[0115] In the above implementations, the receiving unit 720 and the transmitting unit 730 can also be integrated into a transceiver unit, which has both receiving and transmitting functions. This is not a limitation here.

[0116] In various embodiments of the communication device 700 corresponding to the receiving device, the processing unit 710 is used to perform processing and / or operations implemented internally by the receiving device, other than the sending and receiving actions. The receiving unit 720 is used to perform the receiving action of the receiving device, and the sending unit 730 is used to perform the sending action of the receiving device.

[0117] Optionally, the communication device 700 may correspond to the transmitting device in the embodiments of this application. Optionally, the communication device 700 may further include a transmitting unit 730.

[0118] At this time, each unit of the communication device 700 is used to perform the following functions: Processing unit 710 is used to generate NB signals and UWB signals; Transmitting unit 730, used for: Send NB signal; Send UWB signal.

[0119] In the above implementations, the receiving unit 720 and the transmitting unit 730 can also be integrated into a transceiver unit, which has both receiving and transmitting functions. This is not a limitation here.

[0120] In various embodiments of the communication device 700 corresponding to the transmitting device, the processing unit 710 is used to perform processing and / or operations implemented internally by the transmitting device, other than the sending and receiving operations. The receiving unit 720 is used to perform the receiving operation of the transmitting device, and the sending unit 730 is used to perform the sending operation of the transmitting device.

[0121] Figure 8 This is a schematic structural diagram of a communication device 800 according to an embodiment of this application. Figure 8 As shown, the communication device 800 includes one or more processors 810, one or more memories 820, and one or more communication interfaces 830. The processor 810 is used to control the communication interface 830 to transmit and receive signals, the memory 820 is used to store computer programs, and the processor 810 is used to call and run the computer programs from the memory 820 so that the communication device 800 performs the processes performed by the receiving device or the transmitting device in the various method embodiments of this application.

[0122] For example, processor 810 may have Figure 7 The processing unit 710 shown has the following functions, and the communication interface 830 may have... Figure 7 The functions of the receiving unit 720 and / or the transmitting unit 730 shown are as follows. Specifically, the processor 810 can be used to perform processing or operations executed internally by the communication device, and the communication interface 830 is used to perform the transmitting and / or receiving operations of the communication device.

[0123] Optionally, in one implementation, the communication device 800 can be the receiving device in the method embodiment. In this implementation, the communication interface 830 can be the transceiver of the receiving device. The transceiver may include a receiver and / or a transmitter. Optionally, the processor 810 can be the baseband device of the receiving device, and the communication interface 830 can be a radio frequency device.

[0124] In another implementation, the communication device 800 can be a chip (or chip system) installed in the receiving device. In this implementation, the communication interface 830 can be an interface circuit or an input / output interface.

[0125] Optionally, in one implementation, the communication device 800 can be the transmitting device in the method embodiment. In this implementation, the communication interface 830 can be a transceiver of the transmitting device. The transceiver may include a receiver and / or a transmitter. Optionally, the processor 810 can be a baseband device of the transmitting device, and the communication interface 830 can be a radio frequency device.

[0126] In another implementation, the communication device 800 can be a chip (or chip system) installed in the transmitting device. In this implementation, the communication interface 830 can be an interface circuit or an input / output interface.

[0127] in, Figure 8 The dashed box following a device (e.g., processor, memory, or communication interface) indicates that there can be more than one such device.

[0128] In addition, this application also provides a computer-readable storage medium storing computer instructions that, when executed on a computer, cause the operations and / or processes performed by a receiving device in the various method embodiments of this application to be executed.

[0129] This application also provides a computer-readable storage medium storing computer instructions that, when executed on a computer, cause operations and / or processes performed by a transmitting device in the various method embodiments of this application to be performed.

[0130] This application also provides a computer program product, which includes computer program code or instructions that, when executed on a computer, cause the operations and / or processes performed by the receiving device in the various method embodiments of this application to be executed.

[0131] This application also provides a computer program product, which includes computer program code or instructions that, when executed on a computer, cause the operations and / or processes performed by the transmitting device in the various method embodiments of this application to be executed.

[0132] This application also provides a chip including a processor, a memory for storing a computer program disposed independently of the chip, the processor for executing the computer program stored in the memory, causing a communication device on which the chip is mounted to perform operations and / or processes performed by a receiving device in any of the method embodiments.

[0133] This application also provides a chip including a processor, a memory for storing a computer program disposed independently of the chip, the processor for executing the computer program stored in the memory, causing a communication device on which the chip is mounted to perform operations and / or processes performed by a transmitting device in any of the method embodiments.

[0134] Furthermore, the chip may also include a communication interface. The communication interface may be an input / output interface or an interface circuit, etc. Furthermore, the chip may also include the memory.

[0135] Optionally, the processor can be one or more, and the memory can be one or more.

[0136] This application also provides a communication device (e.g., a chip or chip system) including a processor and a communication interface, the communication interface being used to receive (or input) data and / or information and transmit the received data and / or information to the processor, the processor processing the data and / or information, and the communication interface being further used to output (or output) the data and / or information processed by the processor, so that operations and / or processes performed by a receiving device in any method embodiment are executed.

[0137] This application also provides a communication device (e.g., a chip or chip system) including a processor and a communication interface, the communication interface being used to receive (or input) data and / or information and transmit the received data and / or information to the processor, the processor processing the data and / or information, and the communication interface being further used to output (or output) the data and / or information processed by the processor, so that operations and / or processes performed by a transmitting device in any method embodiment are executed.

[0138] This application also provides a communication device including at least one processor coupled to at least one memory, the at least one processor being configured to execute a computer program or instructions stored in the at least one memory, causing the communication device to perform operations and / or processes performed by a receiving device in any of the method embodiments.

[0139] This application also provides a communication device including at least one processor coupled to at least one memory, the at least one processor being configured to execute a computer program or instructions stored in the at least one memory, causing the communication device to perform operations and / or processes performed by a transmitting device in any of the method embodiments.

[0140] This application also provides a wireless communication system, including the receiving device described in the method embodiments of this application. Optionally, it may also include the transmitting device described in the method embodiments.

[0141] The processor in this application embodiment can be an integrated circuit chip with the ability to process signals. In implementation, each step of the above method embodiment can be completed by integrated logic circuits in the processor's hardware or by instructions in software form. The processor can be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. A general-purpose processor can be a microprocessor or any conventional processor. The steps of the method disclosed in this application embodiment can be directly implemented by a hardware encoding processor, or by a combination of hardware and software modules in the encoding processor. The software modules can reside in random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, or other mature storage media in the art. This storage medium is located in memory; the processor reads information from the memory and, in conjunction with its hardware, completes the steps of the above method.

[0142] The memory in the embodiments of this application can be volatile memory or non-volatile memory, or may include both volatile and non-volatile memory. The non-volatile memory can be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. The volatile memory can be random access memory (RAM), which is used as an external cache. By way of example, but not limitation, many forms of RAM are available, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDRSDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous linked dynamic random access memory (SLDRAM), and direct rambus RAM (DRRAM). It should be noted that the memory used in the systems and methods described herein is intended to include, but is not limited to, these and any other suitable types of memory.

[0143] The methods provided in the above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any combination thereof. When implemented in software, they can be implemented, in whole or in part, in the form of a computer program product. The computer program product may include one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions may be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium may be any available medium accessible to a computer or a data storage device such as a server or data center that integrates one or more available media.

[0144] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0145] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0146] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0147] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0148] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0149] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0150] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for signal synchronization applied to an ultra-wideband system, characterized in that, include: A physical layer protocol data unit (PPDU) for transmitting narrowband signals, wherein the PPDU includes M bits of 0, the M bits of 0 being used by the receiving device to obtain time and frequency synchronization information, the M bits of 0 being a symbol agreed upon by the transmitting device and the receiving device, and M being an integer multiple of 4; Send ultra-wideband signals.

2. The method according to claim 1, characterized in that, The Physical Layer Service Data Unit (PSDU) of the PPDU includes the M bits 0.

3. The method according to claim 1 or 2, characterized in that, The time-frequency synchronization information is used by the receiving device to obtain the time-frequency synchronization information of the ultra-wideband signal.

4. The method according to any one of claims 1 to 3, characterized in that, The PPDU uses offset-quadrature phase shift keying (O-QPSK) modulation.

5. A communication device, characterized in that, include: The transmitting unit is a physical layer protocol data unit (PPDU) for transmitting narrowband signals. The PPDU includes M bits of 0, which are used by the receiving device to obtain time and frequency synchronization information. The M bits of 0 are symbols agreed upon by the communication device and the receiving device, and M is an integer multiple of 4. The transmitting unit is also used to transmit ultra-wideband signals.

6. The apparatus according to claim 5, characterized in that, The Physical Layer Service Data Unit (PSDU) of the PPDU includes the M bits 0.

7. The apparatus according to claim 5 or 6, characterized in that, The time-frequency synchronization information is used by the receiving device to obtain the time-frequency synchronization information of the ultra-wideband signal.

8. The apparatus according to any one of claims 5 to 7, characterized in that, The PPDU uses offset-quadrature phase shift keying (O-QPSK) modulation.

9. A method for signal synchronization applied to an ultra-wideband system, characterized in that, include: The Physical Layer Protocol Data Unit (PPDU) for receiving narrowband signals includes M bits of 0. The M bits of 0 are used by the receiving device to obtain time and frequency synchronization information. The M bits of 0 are symbols agreed upon by the transmitting device and the receiving device. M is an integer multiple of 4. Receives ultra-wideband signals.

10. The method according to claim 9, characterized in that, The Physical Layer Service Data Unit (PSDU) of the PPDU includes the M bits 0.

11. The method according to claim 9 or 10, characterized in that, The time-frequency synchronization information is used by the receiving device to obtain the time-frequency synchronization information of the ultra-wideband signal.

12. The method according to any one of claims 9 to 11, characterized in that, The PPDU uses offset-quadrature phase shift keying (O-QPSK) modulation.

13. A communication device, characterized in that, include: The receiving unit is used to receive the physical layer protocol data unit (PPDU) of the narrowband signal. The PPDU includes M bits of 0. The M bits of 0 are used by the communication device to obtain the time and frequency synchronization information of the narrowband signal. The M bits of 0 are symbols agreed upon by the transmitting device and the communication device. M is an integer multiple of 4. The receiving unit is also used to receive ultra-wideband signals.

14. The apparatus according to claim 13, characterized in that, The Physical Layer Service Data Unit (PSDU) of the PPDU includes the M bits 0.

15. The apparatus according to claim 13 or 14, characterized in that, The time-frequency synchronization information is used by the communication device to obtain the time-frequency synchronization information of the ultra-wideband signal.

16. The apparatus according to any one of claims 13 to 15, characterized in that, The PPDU uses offset-quadrature phase shift keying (O-QPSK) modulation.

17. A communication device, characterized in that, It includes at least one processor coupled to at least one memory, the at least one processor being configured to execute a computer program or instructions stored in the at least one memory, such that the method of any one of claims 1 to 4 is performed.

18. A communication device, characterized in that, The method includes at least one processor coupled to at least one memory, the at least one processor being configured to execute a computer program or instructions stored in the at least one memory, such that the method of any one of claims 9 to 12 is performed.

19. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions that, when executed on a computer, cause the method of any one of claims 1 to 4 to be performed, or cause the method of any one of claims 9 to 12 to be performed.

20. A computer program product, characterized in that, The computer program product includes computer program code that, when run on a computer, causes the method of any one of claims 1 to 4 to be performed, or causes the method of any one of claims 9 to 12 to be performed.

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