Self-adaptive waveform switching ultra wide band transceiver

Abstract

The invention relates to the technical field of pulse ultra-wideband, and particularly discloses a self-adaptive waveform switching ultra-wideband transceiver and a control method thereof, and the transceiver comprises a distance detection module which is used for detecting the distance between a UWB transmitter and a remote UWB receiver; the control module is connected with the distance detection module, and controls the pulse shape and output power switching of the UWB transmitter according to the detection result of the distance detection module; and the transmitting module is used for transmitting the UWB signal in a first mode in a first pulse shape and preset first output power under the control of the control module, or transmitting the UWB signal in a second mode in a second pulse shape and preset second output power. According to the invention, the adaptability and practicability of the system in various environments are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of impulse ultra-wideband, and particularly relates to an adaptive waveform switching ultra-wideband transceiver. Background Art

[0002] The operating frequency of an ultra-wideband (UWB) system is usually in the range of 3.1 GHz to 10.6 GHz. With advantages such as large bandwidth, low cost, and stable performance, it is widely used in fields such as positioning, communication, and radar sensing. When using impulse radio-UWB (IR-UWB) for positioning or ranging, the ranging accuracy is affected by various factors: Signal-to-noise ratio (SNR): The higher the SNR, the better the ranging accuracy.

[0003] Antenna gain: A higher antenna gain can enhance the signal strength and improve the accuracy.

[0004] Pulse width: Although a shorter pulse width can improve the accuracy, it will reduce the ranging range.

[0005] Transmit power: Increasing the transmit power can improve the accuracy, but it will also increase the interference.

[0006] Multipath interference: In an environment with many reflecting surfaces, multipath interference will cause errors in the ranging accuracy.

[0007] Receiving sensitivity: The higher the receiving sensitivity, the higher the accuracy.

[0008] Frequency stability: The more stable the frequency, the more accurate the ranging.

[0009] Environmental factors: Environmental factors such as temperature, humidity, and atmospheric pressure will also affect the ranging accuracy.

[0010] To achieve spectral compatibility with other shared-band systems, UWB systems face strict transmit power limitations. For example, the Federal Communications Commission (FCC) in the United States stipulates that the equivalent isotropic radiated power (EIRP) of UWB transmission signals needs to be lower than -41.3 dBm / MHz; in China, the operating frequency range of UWB radios with an allowable effective EIRP not greater than -41.3 dBm / MHz is from 7.163 to 8.812 GHz. In addition, there are also out-of-band emission limit regulations in different regions. For example, the out-of-band emission limit for specific frequency bands in China is defined as Figure 1 shown.

[0011] The pulse shape also has an important impact on the ranging accuracy and spectral mask of UWB signals. The IEEE 802.15.4z(2020) standard defines the default or recommended pulse shapes for high-rate pulse repetition frequency (HRP) UWB, while also allowing the use of other pulse shapes. However, different pulse shapes have their own advantages and disadvantages. For example, pulses with precursors are beneficial for meeting out-of-band emission mask requirements but may affect ranging accuracy; pulses without precursors usually provide better ranging accuracy but have higher requirements for the linearity of radio frequency power amplifiers (PAs). Traditional methods have many problems in meeting in-band and out-of-band emission mask requirements. For example, simply reducing the output power will shorten the communication and ranging distances; improving the PA linearity will increase power consumption, system complexity, and cost, and there is an upper limit to the improvement of linearity. Summary of the Invention

[0012] The purpose of the present invention is to provide an adaptive waveform switching ultra-wideband transceiver to solve the problem that the existing UWB system cannot balance ranging accuracy and ranging distance when meeting the emission mask requirements.

[0013] The purpose of the present invention can be achieved through the following technical solutions: An adaptive waveform switching ultra-wideband transceiver, comprising: A distance detection module for detecting the distance between a UWB transmitter and a remote UWB receiver; A control module connected to the distance detection module, and according to the detection result of the distance detection module, controlling the switching of the pulse shape and output power of the UWB transmitter; A transmission module, under the control of the control module, transmitting UWB signals in a first mode with a first pulse shape and a preset first output power, or transmitting UWB signals in a second mode with a second pulse shape and a preset second output power; Wherein, the first pulse shape includes a peak pulse with one or more precursors, the second pulse shape includes a peak pulse without precursors, and the second output power is lower than the first output power. When the distance detection module detects that the distance between the remote UWB receiver and the UWB transmitter is within a predefined distance, the control module triggers the transmission module to switch from the first mode to the second mode.

[0014] As a further solution of the present invention: when the distance detection module detects that the distance between the remote UWB receiver and the UWB transmitter exceeds the predefined distance, the control module configures the transmission module to switch back to the first mode.

[0015] As a further solution of the present invention: the first output power is determined by the in-band UWB emission requirements, and the second output power is determined by the out-of-band UWB emission requirements.

[0016] As a further aspect of the present invention: the second output power is 1 - 3 dB lower than the first output power, the predefined distance is set based on the UWB emission mask requirement, and the predefined distance is not greater than 3 meters.

[0017] A control method for an adaptive waveform switching ultra-wideband transceiver, the method comprising: Adapting the pulse shape and output power of the UWB transmitter according to the distance between the UWB transmitter and the remote UWB receiver; Configuring the UWB transmitter to transmit a UWB signal in a first mode using a first pulse shape and a first output power, wherein the first pulse shape includes a peak pulse having one or more precursors; Configuring the UWB transmitter to transmit a UWB signal in a second mode using a second pulse shape and a second output power, wherein the second pulse shape includes a peak pulse without precursors, and the second output power is lower than the first output power; When it is detected that the distance between the remote UWB receiver and the UWB transmitter is within the predefined distance, triggering a switch from the first mode to the second mode.

[0018] As a further aspect of the present invention: when it is detected that the distance between the remote UWB receiver and the UWB transmitter exceeds the predefined distance, configuring the radio to switch back to the first mode.

[0019] As a further aspect of the present invention: the first output power is determined by the in-band UWB emission requirement, and the second output power is determined by the out-of-band UWB emission requirement.

[0020] As a further aspect of the present invention: the second output power is lower than the first output power (e.g., 3 dB lower or lower), the predefined distance is set based on the UWB emission mask requirement, and the predefined distance is not greater than 3 meters.

[0021] Advantages of the present invention: By adaptively adjusting the pulse shape and output power, a pulse shape that is conducive to meeting out-of-band emission requirements and ensuring the ranging distance is adopted at long distances, and a pulse shape that can improve ranging accuracy is adopted at short distances, effectively solving the problem that traditional UWB systems cannot balance ranging accuracy and ranging distance; The output power in different modes is determined according to in-band and out-of-band emission requirements, and combined with the selection of appropriate pulse shapes, ensuring that UWB signals can meet strict emission mask regulations in different frequency bands, enhancing the spectral compatibility with other systems; The output power and predefined distance are configurable, enabling the UWB transceiver of the present invention to be flexibly adjusted according to different application scenarios, emission regulations, and expected detection distances, improving the adaptability and practicality of the system in various environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention will be further described below with reference to the accompanying drawings.

[0023] Figure 1 is the definition of out-of-band emission limits for a specific frequency band in the present invention; Figure 2 is the recommended time-domain mask diagram for high-resolution pulse ultra-wideband (HRP UWB) physical layer pulses in the present invention; Figure 3 is the required reference pulse duration in each channel in the present invention; Figure 4 is an example diagram of a compliant pulse in the present invention; Figure 5 is the Japanese ultra-wideband (UWB) emission mask in the present invention; Figure 6 is the Korean ultra-wideband (UWB) emission mask in the present invention; Figure 7 is an example of the first pulse waveform and the second pulse waveform in the present invention; Figure 8 is a schematic flowchart of the control method of the adaptive waveform switching ultra-wideband transceiver in the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0025] Please refer to Figure 1 and Figure 8As shown, the present invention is an adaptive waveform switching ultra-wideband transceiver. The maximum output power of UWB radios is restricted by regulations in different regions, which also imposes limitations on the link budget or the maximum communication and / or ranging distance of UWB systems. In addition to in-band emission limitations, there are also regulations on out-of-band emission limitations in different regions. Therefore, it is also possible that the output power deduced from the in-band UWB spectrum requirements may still cause the spectral mask to violate some out-of-band emission requirements, such as in Japan and South Korea, respectively as Figure 5 and Figure 6 shown.

[0026] The IEEE 802.15.4z (2020) standard defines the default or recommended pulse shape p(t) for high-rate pulse repetition frequency (HRP) UWB, where the transmitted pulse exhibits minimum precursor energy. "In Figure 4 , the middle pulse has a precursor, while the left pulse has no precursor." It further defines that "if the transmitted pulse follows the minimum precursor pulse recommendation, the transmitted pulse shape p(t) should be constrained by the Figure 2 time-domain mask, where the peak amplitude of the pulse is scaled to 1 and the time unit is Tp, defined in Figure 3 . The pulse should rise monotonically to the first peak amplitude; the first peak amplitude is defined as the maximum amplitude of the pulse before it first drops by more than 1.25%.

[0027] In China, the out-of-band emission limit is defined as Figure 1 shown. In order to simultaneously meet the in-band and out-of-band emission mask requirements, there are several ways as follows: The most direct method is to further reduce the output power (compared with the value derived from the in-band emission limit), so that the entire spectral mask of the UWB signal will shift downward. The disadvantage of this method is also obvious. Since the transmitted power is reduced, the entire link budget also correspondingly decreases, and the communication and / or ranging distance will be shortened.

[0028] The selection of the waveform also has an impact on spectral leakage. For example, a waveform with fewer spectral side lobes can be selected to reduce the interference to adjacent spectra.

[0029] For pulse ultra-wideband systems, the linearity of the radio frequency power amplifier (PA) is also a crucial parameter. Linearity directly affects the signal quality, spectral broadening, and the performance of the entire system. The radio frequency PA usually needs to have high linearity to ensure that no distortion is introduced at high power output, otherwise it will cause the spectral expansion of the signal and may also exceed the allowable spectral density limit. Therefore, in order to meet the strict in-band and out-of-band emission masks, another method is to further improve the linearity of the radio frequency power amplifier (PA).

[0030] Improving the PA linearity can be achieved by selecting a PA architecture with better linearity or by cascading multiple amplifiers to provide higher linearity. However, both of these methods have their drawbacks. More linear PAs (such as class A) tend to be less efficient, which may lead to higher power consumption and heat dissipation requirements. Cascading multiple amplifiers to provide higher linearity, on the other hand, comes at the cost of increased system complexity and size, as well as higher cost and power consumption. Additionally, the improvement in linearity by these methods is limited to a certain extent, meaning that further increasing the power consumption or complexity will not effectively enhance the linearity anymore.

[0031] Selecting waveforms with lower PA linearity requirements can also alleviate this problem: For UWB pulses with precursors, that is, in the time domain, there is one or more small peaks before the main pulse, and these small peaks are called precursors. Such waveforms can give the PA more time to gradually reach the peak current, thus making it less likely to have spectral leakage caused by distortion. On the contrary, peak pulses without precursors (sometimes also called maximum phase pulses or peak-first pulses) have much higher requirements for the linearity of radio frequency power amplifiers. Therefore, under the same PA linearity conditions, selecting waveforms with peak pulses having one or more precursors (sometimes also called minimum phase pulses) is also beneficial for meeting the in-band and out-of-band emission mask requirements and avoiding the additional costs to the transmitter design and power consumption caused by simply improving the PA linearity.

[0032] However, when the highest peak is not the leading edge of the pulse, the ranging accuracy may be affected. This is because distance measurement in UWB systems is based on the time-of-flight (ToF) technology. Two UWB radios exchange a series of ultra-short pulses and measure the ToF by calculating the time difference between the transmitted and received pulses. Then the distance between the two UWB radios can be calculated using the following formula: Distance = (speed of light x time-of-flight) / 2 The accuracy of the ranging system depends on several factors, such as the accuracy of the clock used to measure ToF, the quality of the antennas used, the signal processing algorithms, and environmental factors (such as reflections, interference, and multipath propagation).

[0033] Multipath propagation is a phenomenon that occurs when radio waves are reflected from surfaces and arrive at the receiver at different times, resulting in signal interference and distortion. In pulsed UWB ranging, multipath propagation can cause errors in the time-of-flight measurement, thus affecting the ranging accuracy.

[0034] Depending on the communication channel, the transmitted pulse may reflect from multiple surfaces before reaching the receiver. The receiver may receive multiple copies of the same signal, each with a different delay due to different travel path lengths. This can cause the ToF measured by the receiver to be longer than the actual distance, resulting in an overestimation of the distance between the transmitter and the receiver.

[0035] To mitigate the effects of multipath propagation, UWB ranging systems use various signal processing techniques such as time gating, pulse shaping, and correlation analysis. These techniques can help identify and filter out the reflected signals, enabling the receiver to accurately measure the ToF and obtain an accurate distance measurement. However, in some environments, such as indoor environments with many reflective surfaces, multipath propagation still poses a challenge to UWB ranging accuracy.

[0036] In practical applications, due to the existence of a multipath channel, the system needs to separate the direct path between the transmitter and the receiver, i.e., the first path, from multiple reflected paths. Once the direct path is separated, the system can use the ToF of the direct path to calculate a more accurate distance between the transmitter and the receiver.

[0037] It is generally believed that if the leading edge of an ultra-wideband pulse is clear and sharp, the time of arrival can be measured more accurately. Therefore, a peak pulse without a precursor (sometimes also called a maximum-phase pulse, a peak-first pulse, or a minimum-precursor-energy pulse) usually provides better ranging accuracy.

[0038] For a pulse with a precursor, when calculating the distance, small peaks before the highest peak may sometimes be misjudged as the shortest path or the direct path, especially when the distance between the transmitter (TX) and the receiver (RX) is short and the signal fading is small (in this case, the receiver will detect a strong precursor peak).

[0039] It can be seen that different pulse shapes should be selected when designing the pulse shape from the perspective of ranging accuracy and from the perspective of maximum ranging distance.

[0040] It is worth mentioning that the same amount of ranging error may have different effects on the ranging performance of short-range targets and long-range targets. This is because when the distance is large, the error in ranging accuracy may be proportionally smaller to the total distance. For example, if the absolute ranging error is 5 cm, the impact will be different when two UWB radios are 20 meters apart or 2 meters apart. The ranging error is sometimes also expressed as a percentage of the true distance between the transmitter and the receiver.

[0041] Therefore, the present invention proposes to adaptively control the pulse shape of the UWB waveform to achieve a balance between ranging accuracy and ranging distance.

[0042] In a specific embodiment, refer to Figure 7 as shown (whereFigure 7 The pulse1 on the left represents the first pulse shape, Figure 7 and the pulse0 on the right represents the second pulse shape): Configure the UWB transmitter to transmit a UWB signal in a first mode using the first pulse shape and a first output power; wherein, the first pulse shape includes a peak pulse having one or more precursors; and Configure the UWB transmitter to transmit a UWB signal in a second mode using the second pulse shape and a second output power; wherein, the second pulse shape includes a peak pulse without a precursor; wherein, the second output power is lower than the first output power; wherein, when the distance between the remote UWB receiver and the UWB transmitter is detected to be within a predefined distance, a switch from the first mode to the second mode is triggered.

[0043] In this embodiment, when the distance between the remote UWB receiver and the UWB transmitter is detected to exceed the predefined distance, configure the radio to switch back to the first mode; - The first output power is determined by the most stringent in-band UWB emission requirements; - The second output power is determined by the most stringent out-of-band UWB emission requirements; - The second output power is 1 - 3 dB lower than the first output power; - The first and second output powers are configurable, depending on the expected maximum detection distance, emission regulations, or application requirements.

[0044] - The predefined distance is configurable; - The predefined distance is determined based on local regulations regarding the UWB emission mask; The predefined distance is not greater than 3 meters, for example, 1.5 - 3 meters.

[0045] The above has described in detail an embodiment of the present invention, but the content described is only a preferred embodiment of the present invention and cannot be considered as limiting the scope of implementation of the present invention. All equivalent changes and improvements made according to the scope of the present invention application should still fall within the patent coverage scope of the present invention.

Claims

1. An adaptive waveform switching ultra-wideband transceiver, characterized in that, Comprising: A distance detection module for detecting the distance between a UWB transmitter and a remote UWB receiver; A control module connected to the distance detection module, and controlling the pulse shape and output power switching of the UWB transmitter according to the detection result of the distance detection module; A transmitting module, under the control of the control module, transmitting UWB signals in a first mode with a first pulse shape and a preset first output power, or transmitting UWB signals in a second mode with a second pulse shape and a preset second output power; Wherein, the first pulse shape includes a peak pulse with one or more precursors, the second pulse shape includes a peak pulse without a precursor, and the second output power is lower than the first output power.

2. The adaptive waveform switching ultra-wideband transceiver according to claim 1, wherein When the distance detection module detects that the distance between the remote UWB receiver and the UWB transmitter is within a predefined distance, the control module triggers the transmitting module to switch from the first mode to the second mode.

3. An adaptive waveform switching ultra-wideband transceiver according to claim 1, wherein, When the distance detection module detects that the distance between the remote UWB receiver and the UWB transmitter exceeds the predefined distance, the control module configures the transmitting module to switch back to the first mode.

4. An adaptive waveform switching ultra-wideband transceiver according to claim 1, characterized in that, The first output power is determined by in-band UWB emission requirements, and the second output power is determined by out-of-band UWB emission requirements.

5. An adaptive waveform switching ultra-wideband transceiver according to claim 1, characterized in that, The second output power is lower than the first output power.

6. An adaptive waveform switching ultra-wideband transceiver according to claim 1, characterized in that The predefined distance is set based on UWB emission mask requirements, and the predefined distance is not greater than 3 meters.

7. A control method for an adaptive waveform switching ultra-wideband transceiver, characterized in that, The method includes: Adaptingly adjusting the pulse shape and output power of the UWB transmitter according to the distance between the UWB transmitter and the remote UWB receiver; Configuring the UWB transmitter to transmit UWB signals in a first mode with a first pulse shape and a first output power, wherein the first pulse shape includes a peak pulse with one or more precursors; Configuring the UWB transmitter to transmit UWB signals in a second mode with a second pulse shape and a second output power, wherein the second pulse shape includes a peak pulse without a precursor, and the second output power is lower than the first output power.

8. The control method of an adaptive waveform switching ultra-wideband transceiver according to claim 7, characterized in that When it is detected that the distance between the remote UWB receiver and the UWB transmitter is within a predefined distance, triggering a switch from the first mode to the second mode.

9. The control method of an adaptive waveform switching ultra-wideband transceiver according to claim 7, characterized in that When it is detected that the distance between the remote UWB receiver and the UWB transmitter exceeds the predefined distance, configuring the radio to switch back to the first mode.

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