CN203387690U - Multi-mode digital DAS supporting multi-source access - Google Patents

Abstract

The utility model relates to a multi-mode digital DAS system supporting multi-source access. The near-end optical fiber transmission link is connected with the near-end FPGA, and the near-end FPGA is respectively connected with the near-end analog-to-digital conversion chip and the near-end digital-to-analog conversion chip. The near-end analog-to-digital conversion chip is connected to the downlink part of the near-end radio frequency link, the near-end digital-to-analog conversion chip is connected to the uplink part of the near-end radio frequency link, and the downlink part of the near-end radio frequency link is connected to the near-end radio frequency link The uplink part is respectively connected with the duplexer. The beneficial effects of the utility model are: when simultaneous coverage of multi-standard signals is required, and base stations of different systems are located in different locations, the multi-standard signals can be synthesized in the above-mentioned manner by placing slave AUs and transmitted to the same RU The unit and RU output are coupled by POI and then covered by a set of antenna feeder system. In this way, only one system is needed to achieve simultaneous coverage of multi-standard signals, which reduces system cost and construction difficulty.

Description

Multi-mode digital DAS system supporting multi-source access

technical field

The utility model relates to the field of mobile communication coverage, in particular to a multi-mode digital DAS system supporting multi-information source access.

Background technique

The existing indoor mobile communication environment has too many areas that need to be improved:

In terms of coverage, due to the shielding and absorption of the building itself, a large transmission loss of radio waves is caused, forming a weak field strength area or even a blind area of the mobile signal; in terms of capacity, buildings such as large shopping malls and conference centers, due to mobile The density of telephone use is too high, the local network capacity cannot meet the needs of users, and wireless channel congestion occurs; in terms of quality, radio frequency interference is very likely to exist in the high-rise space of buildings, the service cell signal is unstable, and ping-pong switching effects occur, and the voice quality is difficult to guarantee. And there is a phenomenon of dropped calls.

DAS (Distribute Antenna System) system is a means to effectively solve the above problems. The construction of the DAS system can comprehensively improve the call quality in the building, increase the connection rate of mobile phones, and open up a high-quality indoor mobile communication area; at the same time, the use of the micro-cellular system can share the traffic of the outdoor macro-cell and expand the network. Capacity, improving the service level of the mobile network as a whole.

The existing digital DAS system includes access unit AU (Access Unit), expansion unit EU (Expansion Unit) and remote unit RU (Remote Unit), and the signals are transmitted between each unit through optical fiber or twisted pair. The AU unit couples the wireless signal of the base station through radio frequency, performs analog-to-digital conversion and digital filtering processing, transmits it to the RU through the EU unit, converts it into a radio frequency signal, and transmits it to the antenna.

There is only one AU unit in a traditional DAS system, which is used to couple signals from the BTS. For a multi-mode DAS system, if BTSs of different standards are located in different physical locations, multiple systems are required to complete the coverage of multi-standard signals. This brings about a series of problems such as construction difficulties and high equipment costs.

Utility model content

The purpose of the utility model is to overcome the deficiencies of the prior art, and provide a multi-mode digital DAS system that supports multi-source access, which can support simultaneous access to radio frequency signals from multiple base stations at different physical locations.

The purpose of this utility model is accomplished through the following technical solutions, which include a near-end access unit AU, an extension unit EU, and a remote unit RU, and the described near-end access unit AU, extension unit EU and remote unit RU connected via fiber optics;

The near-end access unit AU includes: a duplexer, a near-end radio frequency link uplink part, a near-end radio frequency link downlink part, a near-end digital-to-analog conversion chip, a near-end analog-to-digital conversion chip, a near-end FPGA and a near-end End optical fiber transmission link, described near-end optical fiber transmission link is connected with near-end FPGA, and described near-end FPGA is connected with near-end analog-to-digital conversion chip and near-end digital-to-analog conversion chip respectively, near-end analog-to-digital conversion chip It is connected to the downlink part of the near-end radio frequency link, the near-end digital-to-analog conversion chip is connected to the uplink part of the near-end radio frequency link, and the downlink part of the near-end radio frequency link and the uplink part of the near-end radio frequency link are respectively connected to the duplexer ;

The expansion unit EU includes: an expansion unit optical fiber transmission link, an expansion unit FPGA, and an expansion unit Gigabit Ethernet port. The expansion unit optical fiber transmission link is connected to the expansion unit FPGA, and the expansion unit FPGA is connected to the expansion unit Gigabit Ethernet port connected;

The remote unit RU includes: a duplexer, a power amplifier, a low noise amplifier, an uplink part of a remote radio frequency link, a downlink part of a remote radio frequency link, a remote digital-to-analog conversion chip, a remote analog-to-digital conversion chip, The remote FPGA, the remote optical fiber transmission link and the remote Gigabit Ethernet port, the duplexer is connected with the power amplifier and the low noise amplifier respectively, and the power amplifier is connected with the downlink part of the remote radio frequency link, the remote digital The analog-to-analog conversion chip is connected with the remote FPGA, and the low-noise amplifier is connected with the uplink part of the remote radio frequency link, the remote analog-to-digital conversion chip, and the remote FPGA in turn, and the remote FPGA is connected with the remote optical fiber transmission link and the remote Connect to the end Gigabit Ethernet port.

As a preference, the interconnection of the near-end access units AU is supported, so that radio frequency signals of multiple base stations in different physical locations can be simultaneously connected to the DAS system; when the near-end access units AU are interconnected, they are logically divided into main The end access unit AU and the slave near-end access unit AU, the slave near-end access unit AU only implements the access function of radio frequency signals, and the main near-end access unit AU is responsible for the entire system while realizing radio frequency signal access monitoring, management and maintenance functions.

As a preference, the optical fiber transmission protocol of the near-end access unit AU, extension unit EU and remote unit RU is adapted based on the CPRI protocol, which supports the simultaneous transmission of signals of multiple standards, and supports the transmission of Gigabit Ethernet signals at the same time.

As a preference, the digital signal processing part in the FPGA of the near-end access unit AU and the remote unit RU includes DDC and DUC, and each channel can be independently configured as 10MHz, 20MHz, 40MHz and 60MHz.

Preferably, the extension unit EU and the remote unit RU support transparent transmission of Gigabit Ethernet.

Preferably, it only supports networking through the near-end access unit AU and the remote unit RU, and can realize the function of the traditional digital optical fiber repeater.

The beneficial effects of the utility model are: when it is necessary to realize simultaneous coverage of multi-system signals, and base stations of different systems are located in different locations, the multi-system signals can be synthesized according to the above-mentioned method by placing the slave AU, and transmitted to the same RU unit, RU output is coupled by POI and then covered by a set of antenna feeder system. In this way, only one system is needed to achieve simultaneous coverage of multi-standard signals, which reduces system cost and construction difficulty.

Description of drawings

Fig. 1 is a topological structure diagram of the utility model.

Figure 2 is a first schematic diagram of the internal modules of the AU device of the present invention.

Fig. 3 is a first schematic diagram of the internal modules of the RU device of the present invention.

Fig. 4 is the second schematic diagram of the internal modules of the AU device of the present invention.

Fig. 5 is the second schematic diagram of the internal modules of the RU device of the present invention.

Fig. 6 is a schematic diagram of the internal modules of the EU device of the present invention.

Detailed ways

In order to make the purpose, technical solution and advantages of the utility model clearer, the utility model will be further described in detail below in conjunction with the accompanying drawings.

Fig. 1 is a topological structure diagram of the utility model. Among them, AU1 serves as the master near-end access unit AU, and AU2 and AU3 serve as slave near-end access units AU. AU2 and AU3 respectively couple radio frequency signals from different base stations, and after digital processing, transmit them from the optical fiber to the main near-end access unit AU, form a frame together with the signal received by the main near-end access unit AU, and then transmit to the extension unit EU via optical fiber , the main near-end access unit AU can connect up to 4 EU devices.

The main function of the extension unit EU is the expansion of the optical port and the access of Gigabit Ethernet. Each expansion unit EU device can be connected to 8 remote units RU, and supports a maximum of 8 levels of EU cascading networking.

The remote unit RU performs digital IF processing on the signal received from the optical fiber, up-converts and amplifies the power, outputs it to the POI for combination, and finally outputs it to the antenna feeder system to achieve signal coverage. The remote unit RU can support a maximum of 6 levels of cascading.

The utility model can also support networking with only the main near-end access unit AU and the remote unit RU, and its advantage is that when the area to be covered is small, the extension unit EU equipment can be saved and the cost can be reduced.

FIG. 2 is a schematic diagram of hardware circuit modules inside an AU device. The AU device supports 4 independent radio frequency channels, and can support the simultaneous access of signals of 4 different formats.

The functions of each unit in Figure 2 are as follows:

Duplexer: The duplexer receives the downlink signal output by the base station, and at the same time transmits the uplink signal of the machine to the base station. It consists of two sets of stop-band filters with different frequencies to ensure that both reception and transmission can work normally at the same time.

Frequency conversion and filter circuit: including LO circuit (Local Oscillator), up-converter, down-converter and filter. The LO generates a carrier frequency signal, which is input to the up-converter and down-converter. The up-converter is realized by AQM (Analog Quardrature Modulation) circuit, which modulates the IQ signal of the intermediate frequency into a radio frequency signal of the required carrier frequency. The down-converter is implemented by a frequency mixing circuit, which mixes down the radio frequency signal to obtain the required intermediate frequency signal. At the same time, a filter is added to the circuit to suppress the spectral components outside the required passband.

Digital/analog conversion and analog/digital conversion circuit: including the ADC and the anti-aliasing filter before it, and the DAC and the image rejection filter after it. The high-performance ADC and DAC ensure that a single channel supports a maximum signal bandwidth of 60MHz.

FPGA: FPGA includes digital intermediate frequency processor and optical fiber protocol processor.

The digital IF processor includes DDC (Digital Down Convert) and DUC (Digital Up Convert), power detection, ALC (Auto Level Control) and other auxiliary functions. DDC and DUC are one of the core technologies of Software Defined Radio (SoftwareDefined Radio), and are also the key of the utility model. The DDC performs channel filtering according to the bandwidth of the input RF channel signal, and extracts to an appropriate sampling rate. The utility model supports 4 different bandwidth settings, respectively 10MHz, 20MHz, 40MHz, and 60MHz. The DDC module respectively down-samples the digital signals of these 4 bandwidths, and obtains sampling rates of 11.52MSps, 23.04MSps, 46.08MSps and 69.12 digital signal in MSps. The advantage of the above processing is that, for a channel with a relatively narrow signal bandwidth, by reducing the data rate, the optical fiber transmission bandwidth can be saved.

The processing process of DUC is opposite to that of DDC. The signal with low sampling rate is interpolated to the sampling rate of DAC, and at the same time, the spectral image generated in the processing process is suppressed by the filter.

The optical fiber transmission protocol of the utility model is adapted based on CPRI (Common Public Radio Interface) to meet the transmission requirements of multi-channel and multi-standard signals that can be flexibly configured.

The digital signal processed by the DDC module is transmitted to the expansion unit EU through the optical fiber according to the rules of the optical fiber transmission protocol.

According to the above, the near-end access unit AU includes 6 optical fiber interfaces, 2 of which are used to support AU cascading to expand the number of input channels. When the near-end access unit AU acts as a slave AU, it only transmits the data received from the local radio frequency channel; when the near-end access unit AU acts as the master In addition to the data received by the radio frequency channel of the machine, the data transmitted from the near-end access unit AU needs to be reassembled and transmitted to the extension unit EU together.

The main near-end access unit AU of the utility model can be connected to two slave near-end access units AU at the same time, and the remote unit RU supports cascading, and each near-end access unit AU and remote unit RU have 4 Therefore, a set of equipment (AU+EU+RU) can support a maximum of 12 independent signal accesses. In a multi-operator and multi-standard environment, it greatly reduces the number of devices and lowers the networking The complexity and cost are greatly reduced, which is the biggest advantage of the utility model compared with the traditional DAS equipment.

FIG. 3 is a schematic diagram of internal hardware circuit modules of the RU device. The working process of the remote unit RU is similar to that of the near-end access unit AU. The difference is that a low-noise amplifier LNA is added in the uplink, and a power amplifier PA is added in the downlink to increase signal coverage and improve receiving sensitivity.

The working process of the remote unit RU of the utility model is as follows: receiving the optical signal from the extension unit EU or the near-end access unit AU from the optical fiber, and entering the FPGA for digital processing after photoelectric conversion. The FPGA parses the required signal from the optical fiber protocol, and performs digital/analog conversion after digital up-conversion DUC processing. After the up-conversion and filtering circuit, it is sent to the power amplifier PA module for signal amplification to ensure the signal strength requirements of the coverage area. Each RF channel sends the amplified RF signal to the antenna feeder system after POI coupling to achieve signal coverage. In the uplink direction, the signal received from the antenna is amplified by the low-noise amplifier LNA, then down-converted and filtered, processed by the digital down-converted DDC, converted to analog/digital, and finally output to the base station through the near-end access unit AU.

The Gigabit Ethernet signal accessed through the extension unit EU is output through the network interface after recovery at the RU end, and can be plugged in to achieve WLAN coverage, or connected to other IP devices to provide Ethernet channels.

It can be understood that, for those skilled in the art, any equivalent replacement or change to the technical solution and the concept of the utility model of the utility model shall belong to the protection scope of the appended claims of the utility model.

Claims (5)

1. a multimode numeral DAS system of supporting multiple source access is characterized in that: comprise near-end access unit AU, and expanding element EU, far-end unit RU, described near-end access unit AU, expanding element EU are connected by optical fiber with far-end unit RU;

Described near-end access unit AU comprises: duplexer, near-end radio frequency link ascender, near-end radio frequency link descender, the near-end analog-digital chip, the near-end modulus conversion chip, near-end FPGA and near-end fiber transmission link, described near-end fiber transmission link is connected with near-end FPGA, described near-end FPGA is connected with the near-end analog-digital chip with the near-end modulus conversion chip respectively, the near-end modulus conversion chip is connected with near-end radio frequency link descender, the near-end analog-digital chip is connected with near-end radio frequency link ascender, near-end radio frequency link descender is connected with duplexer respectively with near-end radio frequency link ascender,

Described expanding element EU comprises: expanding element fiber transmission link, expanding element FPGA, expanding element gigabit Ethernet mouth, described expanding element fiber transmission link is connected with expanding element FPGA, and expanding element FPGA is connected with expanding element gigabit Ethernet mouth;

Described far-end unit RU comprises: duplexer, power amplifier, low noise amplifier, far end radio frequency link ascender, far end radio frequency link descender, the far-end analog-digital chip, the far-end modulus conversion chip, far-end FPGA, distal fiber transmission link and far-end gigabit Ethernet mouth, described duplexer is connected with low noise amplifier with power amplifier respectively, power amplifier successively with far end radio frequency link descender, far-end analog-digital chip and far-end FPGA are connected, low noise amplifier successively with far end radio frequency link ascender, far-end modulus conversion chip and far-end FPGA are connected, described far-end FPGA is connected with distal fiber transmission link and far-end gigabit Ethernet mouth.

2. the multimode numeral DAS system of support multiple source access according to claim 1, is characterized in that: support the interconnected of near-end access unit AU, with the base station radio-frequency signal of realizing a plurality of different physical locations, can access the DAS system simultaneously; When described near-end access unit AU is interconnected, from being divided in logic main near-end access unit AU and from near-end access unit AU, only realize the access function of radiofrequency signal from near-end access unit AU, main near-end access unit AU, when realizing the radiofrequency signal access, also is responsible for monitoring, management and the maintenance function of whole system.

3. the multimode numeral DAS system that support multiple source according to claim 1 accesses, it is characterized in that: the Optical Fiber Transmission agreement of described near-end access unit AU, expanding element EU and far-end unit RU is adapted based on the CPRI agreement, support the signal of multiple types to transmit simultaneously, support the transmission of gigabit ethernet signal simultaneously.

4. the multimode numeral DAS system that support multiple source according to claim 1 accesses, it is characterized in that: the signal process part in the FPGA of described near-end access unit AU and far-end unit RU comprises DDC and DUC, every passage prop root is the signal bandwidth of border input factually, and separate configurations is 10MHz, 20MHz, 40MHz or 60MHz.

5. the multimode numeral DAS system of support multiple source access according to claim 1, is characterized in that: the transparent transmission of described expanding element EU and far-end unit RU support gigabit Ethernet.

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