Bandwidth adaptive coverage system

Abstract

The invention discloses a bandwidth adaptive coverage system comprising a digital attenuator, an ADC module, a gain fine tuning module, a DC calibration module, a mirror image calibration module, a digital down-conversion DDC module, a variable broadband filter, a digital domain switch, a digital up-conversion DUC module, a PLAGC module and a DAC module which are connected in sequence. The DDS generation module is connected between the digital down conversion DDC module and the PLAGC module, and the AGC module is connected between the gain fine tuning module and the DC calibration module. According to the invention, the problem of source bandwidth change can be well solved, and signal detection and bandwidth self-adaption can be realized at low cost, so that the system performance is not influenced, and the signal does not need to be disconnected.

Description

Technical Field

[0001] The present invention relates to the technical field of indoor distribution systems for 5G mobile communications, and more specifically, to a bandwidth adaptive coverage system. Background Art

[0002] Currently, operators are continuously optimizing the network quality as the demands for services and coverage change. Generally, signal coverage is achieved using base stations. However, in order to consider the return on investment ratio, active distribution systems or repeaters are used for coverage in many medium- and low-value scenarios.

[0003] Operators select different indoor coverage solutions according to different capacity scenarios, construction convenience, and equipment costs. Among the current indoor coverage solutions, they can generally be divided into three types: distributed pico base stations, fiber optic repeaters, fiber optic distribution systems, coaxial cable distribution systems, and wireless repeaters, etc.

[0004] In order to provide a better network experience for users, the operating network will be regularly optimized and adjusted. If the coverage solution cannot adaptively change accordingly, it will require costs such as property coordination, network reconstruction, and later equipment maintenance. Therefore, it is necessary to provide a bandwidth adaptive coverage system. Summary of the Invention

[0005] The purpose of the present invention is to provide a bandwidth adaptive coverage system to overcome the defects existing in the prior art.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows: A bandwidth adaptive coverage system includes a digital attenuator, an ADC module, a gain fine-tuning module, a DC calibration module, an image calibration module, a digital down-conversion DDC module, a variable broadband filter, a digital domain switch, a digital up-conversion DUC, a PLAGC module, and a DAC module connected in sequence, a DDS generation module connected between the digital down-conversion DDC module and the PLAGC module, and an AGC module connected between the gain fine-tuning module and the DC calibration module.

[0007] Further, it further includes a baseband power statistics module connected between the variable broadband filter and the digital domain switch.

[0008] Further, the DDS generation module is further connected to a plurality of source extraction DDC modules, and each source extraction DDC module is sequentially connected to a decimation filter module, a shaping filter module, and a data interface, and the data interface is connected to a corresponding broadband indicator light.

[0009] Further, the AGC module is further connected to the digital attenuator through an SPI interface.

[0010] Further, the digital up-conversion DUC module and the digital down-conversion DDC module are used to up-convert or down-convert the baseband signal to the required frequency point. Assuming the data to be frequency-converted is I and Q, and the DDS of the frequency point is cosθ and sinθ, using the relationship of trigonometric functions, the formula of the digital up-conversion DUC module is as follows: I = I * cosθ - Q * sinθ Q = I * sinθ + Q * cosθ The formula of the digital down-conversion DDC module is as follows: I = I * cosθ + Q * sinθ Q = Q * cosθ - I * sinθ.

[0011] Compared with the prior art, the advantages of the present invention are as follows: A bandwidth adaptive coverage system provided by the present invention can well solve the problem of the change of the source bandwidth, and uses low cost to solve signal detection and bandwidth adaption, thus not affecting the system performance and without disconnecting the signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0013] Figure 1 is the schematic diagram of the bandwidth adaptive coverage system of the present invention.

[0014] Figure 2 is the circuit diagram of the bandwidth adaptive coverage system of the present invention.

[0015] Figure 3 is the uniquely determined relationship diagram of the resource unit with the frequency domain and time domain serial number groups in the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0016] The following will elaborate on the preferred embodiments of the present invention in conjunction with the drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making the protection scope of the present invention more clearly defined.

[0017] Refer to Figure 1As shown in the figure, this embodiment discloses a bandwidth adaptive coverage system, which includes a digital attenuator, an ADC module, a gain fine-tuning module, a DC calibration module, an image calibration module, a digital down-conversion DDC module, a variable broadband filter, a digital domain switch, a digital up-conversion DUC, a PLAGC module, and a DAC module that are connected in sequence. A DDS generation module is connected between the digital down-conversion DDC module and the PLAGC module, and an AGC module is connected between the gain fine-tuning module and the DC calibration module.

[0018] As Figure 2 shown in the figure, the digital attenuator of this embodiment can implement digital domain ATT attenuation processing and switching control of channel IQ data. The ATT attenuation value is calculated by the MCU, and the calculation formula is as follows: ATT setting value = round(8192 / (10^(DB / 20))). Where DB is the ATT attenuation value to be set, and the ATT setting value is the setting value calculated from the ATT attenuation value. This value is set into the FPGA and is an unsigned integer.

[0019] In the ADC module of this embodiment, each ADC receives a radio frequency signal with a maximum supported bandwidth of 40 MHz. The interface sampling rate is set to 46.08 MSPS, the interface level mode is LVDS, the clock per path is 92.16 MHz, and the data bit width is 12 bits.

[0020] The gain fine-tuning module of this embodiment is a reserved module with a step of 0.1 dB and a setting range of [-3dB, 3dB]. It is placed on the ADC receiving side and in front of the AGC, which is beneficial to accurate gain calibration.

[0021] In the DC calibration module of this embodiment, the transceiver uses a zero-IF scheme. The data sampled by the ADC inevitably has DC leakage signals. This DC leakage is related to the working environment of the digital board and may sometimes be relatively large, affecting the performance of the device. This design uses a DC calibration algorithm to calibrate the DC on the ADC side and minimize the impact of DC signals on the device.

[0022] The image calibration module of this embodiment has the same principle as the DC calibration. Using zero-IF reception will also generate image signals. To eliminate the image signals generated by the ADC, this design uses an image calibration module to reduce the received image signals to an acceptable range.

[0023] In the digital down-conversion DDC module of this embodiment, the digital up-conversion DUC and the digital down-conversion DDC are used to shift the baseband signal up or down to the required frequency point. The data to be frequency-converted is I and Q, and the DDS of the frequency point is cosθ and sinθ. Using the relationship of trigonometric functions, the formula for the digital down-conversion DDC is as follows: I = I * cosθ + Q * sinθ; Q = Q * cosθ - I * sinθ。

[0024] The variable broadband filter of this embodiment: belongs to the baseband shaping filter, and the design needs to meet the requirement of variable bandwidth. The variable bandwidth ranges from 5MHz, 10MHz, 15MHz, 20MHz, 30MHz to 40MHz. In each bandwidth configuration, except for the different passband frequencies, other parameters are the same. The configuration parameters of the filter are shown in the following table. The MCU sets the filter bandwidth required by the customer to the FPGA interface through the configuration interface, and the FPGA automatically imports the coefficients corresponding to the bandwidth into the filter.

[0025] The digital domain switch of this embodiment realizes the switch control of the digital pre-channel IQ data In the digital upconversion DUC of this embodiment, the digital upconversion DUC and the digital downconversion DDC shift the baseband signal up or down to the required frequency point. The data to be frequency-converted are I and Q, and the dds of the frequency point are cosθ and sinθ; using the relationship of trigonometric functions, the formula of the digital upconversion DUC is as follows: I = I * cosθ - Q * sinθ; Q = I * sinθ + Q * cosθ; The PLAGC module of this embodiment controls the digital power. If it is greater than a certain threshold, it controls the digital domain ATT to attenuate the value.

[0026] In the DAC module of this embodiment, each DAC receives a radio frequency signal with a maximum supported bandwidth of 40MHz. The interface sampling rate is set to 46.08MSPS, the interface level mode is LVDS, the clock on the same path is 92.16MHz, and the data bit width is 12 bits.

[0027] The process of the present invention to achieve bandwidth adaptive coverage is as follows: Step S1, receive the downlink broadband signal through the ADC; Step S2, perform low-pass filtering on the downlink broadband signal to extract the synchronization signal at the center of the bandwidth; Step S3, reduce the sampling rate of the synchronization signal; Step S4, perform signal detection on the decimated synchronization signal; Step S5, generate a broadband configuration according to the detected signal. The broadband configuration process is as follows: First, frequency shift Separate a part of the signal from the main signal, and the formula for the frequency value is: 1), when performing down frequency shift: Nco = frequency value / 122.88 * 2^32; 2). When up-converting the frequency: Nco = (122.88 - frequency value) / 122.88 * 2^32; Secondly, perform low-pass filtering on the low-pass filter The signal after frequency conversion is very large. In order to detect the signal of 1 RB (12 subcarriers), the received signal (baseband signal) is pre-filtered by a low-pass filter to extract the signal of the required bandwidth and reduce the influence of other signals.

[0028] In addition, the signal transmitted in one time slot of LTE can be described by a resource grid, and its size is subcarriers and OFDM symbols. Each resource unit can have a sequence group in the frequency domain and time domain which is uniquely determined. As Figure 3 shown. In the frequency domain axis direction, continuous subcarriers and the physical resources occupying one time slot are defined as a resource block (RB). The size of depends on the configuration of the cell transmission bandwidth and satisfies where

[0029] This embodiment further includes a baseband power statistics module connected between the variable broadband filter and the digital domain switch.

[0030] In this embodiment, the DDS generation module is also connected to a plurality of source extraction DDC modules. Each source extraction DDC module is sequentially connected to a decimation filter module, a shaping filter module, and a data interface, and the data interface is connected to the corresponding broadband indicator light.

[0031] In this embodiment, the AGC module is also connected to a digital attenuator through an SPI interface.

[0032] In this embodiment, the variable broadband filter belongs to a baseband shaping filter. In the design, it is required to meet the requirement of variable bandwidth. The variable bandwidth ranges from 5 MHz, 10 MHz, 15 MHz, 20 MHz, 30 MHz, and 40 MHz. In each bandwidth configuration, except for the different passband frequencies, other parameters are the same. The configuration parameters of the filter are shown in the following table. The MCU sets the filter bandwidth required by the customer to the FPGA interface through the configuration interface, and the FPGA automatically imports the coefficients corresponding to the bandwidth into the filter.

[0033] Table 1 Filter Parameter Configuration Serial number Signal sampling rate (MSPS) Signal bandwidth (MHz) Passband frequency (MHz) Stopband frequency (MHz) In-band ripple (dB) Stopband rejection (dB) Filter order 1 46.08 5 2.5 3.5 0.2 70 129 2 46.08 10 5 6 0.2 70 129 3 46.08 15 7.5 8.5 0.2 70 129 4 46.08 20 10 11 0.2 70 129 5 46.08 30 15 16 0.2 70 129 6 46.08 40 20 21 0.2 70 129 In this embodiment, the DAC module: Each DAC receives a radio frequency signal with a maximum supported bandwidth of 100 MHz. The interface sampling rate is set to be greater than 100 MSPS. The interface level mode is LVDS, and the data bit width is 12 bits.

[0034] A bandwidth adaptive coverage system provided by the present invention can well solve the problem of the change of the source bandwidth, and uses low cost to solve signal detection and bandwidth adaptation, so as not to affect the system performance and without disconnecting the signal.

[0035] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, the patent owner can make various deformations or modifications within the scope of the appended claims. As long as it does not exceed the protection scope described by the claims of the present invention, it should be within the protection scope of the present invention.

Claims

1. A bandwidth adaptive coverage system, characterized in that, It includes a digital attenuator, an ADC module, a gain fine-tuning module, a DC calibration module, an image calibration module, a digital down-conversion DDC module, a variable broadband filter, a digital domain switch, a digital up-conversion DUC module, a PLAGC module, and a DAC module that are connected in sequence, a DDS generation module connected between the digital down-conversion DDC module and the PLAGC module, and an AGC module connected between the gain fine-tuning module and the DC calibration module.

2. The bandwidth adaptive coverage system according to claim 1, wherein It further includes a baseband power statistics module connected between the variable broadband filter and the digital domain switch.

3. The bandwidth adaptive coverage system according to claim 1, wherein The DDS generation module is further connected to multiple source extraction DDC modules. Each source extraction DDC module is connected to a decimation filter module, a shaping filter module, and a data interface in sequence. The data interface is connected to a corresponding broadband indicator light.

4. The bandwidth adaptive coverage system according to claim 1, wherein The AGC module is also connected to the digital attenuator through an SPI interface.

5. The bandwidth adaptive coverage system according to claim 1, characterized in that The digital up-conversion DUC module and the digital down-conversion DDC module are used to shift the baseband signal up or down to the required frequency point. Assuming the data to be frequency-converted is I and Q, and the DDS of the frequency point is cosθ and sinθ, using the relationship of trigonometric functions, the formula of the digital up-conversion DUC module is as follows: I = I * cosθ - Q * sinθ Q = I * sinθ + Q * cosθ The formula of the digital down-conversion DDC module is as follows: I = I * cosθ + Q * sinθ Q = Q * cosθ - I * sinθ.

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