WO2007076682A1

WO2007076682A1 - A broadband user access device and a method for broadband user access processing

Info

Publication number: WO2007076682A1
Application number: PCT/CN2006/003436
Authority: WO
Inventors: Jun Zhou
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2005-12-30
Filing date: 2006-12-15
Publication date: 2007-07-12
Also published as: CN1859585B; CN1859585A

Abstract

A broadband user access device includes an up interface and at least an up channel and a down channel. The down channel at least includes a digital modem, a modulation filter circuit and an electro optical converting module which are connected sequentially, and is used to process the signals received from the up interface and then transmits the signals that have been processed to the user terminal through the fiber connected to the electro optical converting module; the up channel at least includes an photoelectric converting module, a demodulation filter circuit and a digital modem which are connected sequentially, and is used to process the signals received from the user terminal through the fiber connected to the photoelectric converting module and then up transmits the signals that have been processed through the up interface. Another broadband user access device and a method for broadband user access processing both can omit the conversion processing of 2-4 line in the prior art.

Description

Broadband user access device and broadband user access processing method

The present invention relates to the field of communications technologies, and in particular, to a broadband user access device and a broadband user access processing method. Background of the invention

xDSL technology is a high-speed data transmission technology that transmits data over telephone twisted pair (Unshielded Twist Pair, UTP), except IDSL (ISDN Digital Subscriber Loop) and SHDSL (single pair high bit rate digital users) Baseband and other baseband transmission DSL

(Digital Subscriber Line) In addition, xDSL for passband transmission uses frequency division multiplexing technology to enable xDSL to coexist with traditional telephony services (POTS) on the same pair of twisted pairs. Among them, xDSL occupies a high frequency band, POTS (traditional telephone service) occupies a baseband portion below 4 kHz, and POTS signals and xDSL signals are separated by a splitter. XDSL for passband transmission uses discrete multitone modulation

(DMT) ₀ A system that provides multiple xDSL access is often referred to as a DSL access multiplexer.

(DSLAM), its system reference model is shown in Figure 1.

Since DSL is transmitted on the unshielded twisted pair UTP, and UTP is originally designed to transmit voice signals, the high frequency characteristics are not good; this results in a large attenuation of the xDSL signal occupying the high frequency, and the coverage of the xDSL service is affected. Restricted. In practical applications, the higher the access rate that the xDSL service can provide, the smaller its coverage. For example: ADSL2+ (ADSL2 with downstream bandwidth extension) can provide the highest rate of 25 Mbit/s in short distance, but at 6 km. The access rate is less than 1Mbps; VDSL2 (second-generation asymmetric digital subscriber line) is mainly for high-bandwidth services, so the main coverage is less than 1.5km (take 0.4mm cable as an example, the same below), A downlink rate of more than 40M can only be provided when the distance is less than 1000 meters. Due to the above problems, in most countries, only half of the users can be provided more than

40M downlink rate. In order to provide high-bandwidth access services to many users who are far away from the office, the operator shortens the line length by moving the DSLAM site down to the user, as shown in Figure 2: The DSLAM is pulled far to the user's location, and the DSLAM provides users with high-bandwidth access services, namely: FTTx (general name for fiber access) + XDSL access mode. This method can solve the distance problem, but due to the excessive dispersion of the site and the increase of the number of sites, the problem of inconvenient power supply and high operation and maintenance costs is becoming more and more prominent.

The trend of broadband access is to enter the copper, that is, the fiber is getting closer and closer to the user, and the subscriber line is getting shorter and shorter; but there are still cost problems in order to achieve the final fiber-to-the-home, fiber-to-the-desktop, Therefore, the last segment of the access network is still xDSL for a considerable period of time.

The MUSE Project (Multi Service Access Everywhere), which is funded by the European Union, focuses on the architecture and technology of multi-service access networks, and some of the interesting technologies are proposed in the sub-project Optical Access. For example: DSL over Optic for transmitting DSL signals through optical fibers; the specific method is to perform multi-channel xDSL signals for frequency multiplexing, linear modulation, etc., and then transmit them through optical fibers; at the opposite end, through linear demodulation and demultiplexing techniques, The signal of xDSL. Since the attenuation of the fiber is small, the coverage of xDSL can be extended to several tens of kilometers by this method, and since the device for modulation, demodulation, and demultiplexing can be solidified without software upgrade and maintenance, Make xDSL a maintenance-free, closed device and place it in a node close to the user. Figure 3 shows the networking diagram of DSL over Optic in the MUSE project.

Referring to Figure 4, Figure 4 is a schematic diagram of the principle of frequency shifting and multiplexing. Specifically, frequency shifting and multiplexing is similar to the modulation and multiplexing process in CATV (cable television). Frequency shifting modulates each user's xDSL signal onto a pre-designated carrier, and the carrier center frequency of each user The distance is orthogonal. This allows the frequency shift to be able to signal each user at the frequency. After being separated, the signals of the above frequency divisions are multiplexed together by a combiner to form a frequency division multiplexed signal. The process of frequency shifting and demultiplexing is exactly the opposite of the above.

Referring to Figure 5, Figure 5 is a schematic diagram of the network working principle of DSL over Optical fiber in the MUSE project. The solution of the MUSE project is to frequency shift and multiplex the analog signal output by the xDSL modem, and then transmit the signal application optical device to the node through the optical fiber in a linear optical emphasis system; the node can be demultiplexed and unloaded. The operation is to recover the xDSL analog signal, and the recovered xDSL analog signal is transmitted to the user through the twisted pair.

On the side of the optical equipment unit (ONU) of the customer equipment shown in FIG. 5, the optical splitter/synthesizer transmits the downlink optical signal to the linear photoelectric conversion module to be converted into an electrical signal, and then the electrical signal is branched through the splitter. Demodulation to multiple demodulators, the demodulated signal is filtered by a low-pass filter and then amplified by power. Finally, the second and fourth-line conversion circuits are converted into ordinary DSL electrical signals and sent to the line; The uplink DSL signal separated by the second and fourth line conversion circuits is subjected to amplification, modulation, band pass filtering, combining, electro-optical conversion, etc., and then the processed signal is sent to the optical fiber through the optical combiner/demultiplexer. .

On the central office device side of FIG. 5, a device optical line terminal (OLT) and a digital subscriber line access multiplexer (DSLAM) for performing DSL over Optic frequency shifting and multiplexing are provided; and the DSLAM and the OLT are separately set, The DSLAM and the OLT are connected by twisted pairs.

See Figure 6, Figure 6 for a schematic diagram of the frame structure of the DSLAM system. Usually, a DSLAM consists of the following parts connected by a data bus and a control bus on a motherboard (not shown): a control module that manages the entire DSLAM system, an uplink interface module that provides an upstream data aggregation interface, and a series of users. Interface module. Among them, as a key device, the xDSL user interface module is mainly composed of a motherboard interface, an xDSL digital modem module, a control part, and a power supply.

The xDSL digital modem module responsible for the modulation and demodulation of xDSL signals, usually It consists of an xDSL chipset and peripheral circuits. Specifically, a digital signal processor (DSP), an analog front end device (AFE), which is responsible for processing the digital signal, performs conversion between the analog signal and the digital signal and voltage amplification; the line driver receives the transmission signal from the AFE and completes the transmission of the signal. Power amplification; the receiving amplifier amplifies the received signal and sends it to the AFE; the analog front-end hybrid (Hybrid) circuit completes the second and fourth line conversion between the outer line (2) and the internal receive and transmit (each two) to realize the transmission signal, Separation between received signals. In fact, a pair of DSP and AFE can generally support multiple xDSL modems.

Since the OLT and the DSLAM are separately set, the xDSL interface part of the DSLAM needs to complete the 2-4 line conversion of receiving and transmitting signals, and since the OLT also needs to perform separation processing between the transmitted signal and the received signal, it is in the OLT. Also perform a 2-4 line transformation.

It can be seen from the above that the disadvantages of the prior art are: Since the DSLAM and the DSL over Optic frequency shifting and multiplexing OLT are separately set, and the DSLAM and the OLT are connected by a twisted pair cable; the xDSL interface part of the DSLAM needs to be completed. 2-4 line conversion of receiving and transmitting signals, and a 2-4 line transformation in the OLT. These 2-4 line conversion operations are virtually redundant, which will result in unnecessary cost increase and port density. Significant decline. Summary of the invention

In view of this, the main purpose of the embodiments of the present invention is to provide a broadband user access device and a broadband user access processing method, which strives for low cost and increases port density.

To achieve the above objective, the technical solution of the embodiment of the present invention is implemented as follows: The embodiment of the present invention discloses a broadband user access device, including an uplink interface part, and further includes at least one uplink and downlink channel, where:

The downlink channel includes at least a serially connected digital modulation and demodulation device, and a modulation filter a circuit, an electro-optical conversion module, configured to transmit, by the optical fiber connected to the optical interface, the signal received from the uplink interface to the user end;

The uplink channel includes at least a sequentially connected photoelectric conversion module, a demodulation filter circuit, and a digital modulation and demodulation device, and is configured to receive a signal from the optical fiber connected to the photoelectric conversion module, process the signal, and perform uplink through the uplink interface.

The embodiment of the present invention further discloses a broadband user access device, including a motherboard and a user interface board thereof, the user interface board includes a motherboard interface module, and further includes at least one uplink connected to the motherboard interface module. And the downstream channel, where:

The downlink channel includes at least a serially connected digital modulation and demodulation device, a modulation filter circuit, and an electro-optical conversion module, and the signal received from the motherboard interface module is processed and transmitted by the optical fiber connected to the electro-optical conversion module to the user end;

The uplink channel includes at least a photoelectric conversion module, a demodulation filter circuit, and a digital modulation and demodulation device, which are sequentially connected, and are configured to receive a signal from the optical fiber connected to the photoelectric conversion module, and then process the data through the motherboard interface module. .

The embodiment of the invention also discloses a broadband user access processing method, which uses an optical fiber to transmit a digital subscriber line signal between the user end and the central office, and processes the uplink data and the downlink data separately at the central office, where:

For the downlink data, the signal processed by the digital modulation and demodulation device is modulated and filtered, and the signal that completes the modulation and filtering is converted into an optical signal and transmitted to the user end through the optical fiber;

For the uplink data, the UE signal received through the optical fiber is converted into an electrical signal, and after the electrical signal is demodulated and filtered, it is processed by the digital modem device.

Compared with the prior art, the broadband user access device and the broadband user access processing method provided by the embodiments of the present invention can both modulate and filter the signal processed by the digital modulation and demodulation device, and convert the signal that completes the modulation and filtering. The optical signal is transmitted to the user end through the optical fiber; the user terminal signal received through the optical fiber can also be converted into an electrical signal, and the electrical signal is After demodulation and filtering, it is processed by the digital modulation and demodulation device; thus, the cost can be significantly reduced, and the port density can be effectively improved. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematic diagram of a reference model of an XDSL system;

2 is a schematic diagram of a DSLAM networking extended by an optical fiber;

Figure 3 is a networking diagram of DSL over Optic in the MUSE project.

Figure 4 is a schematic diagram of the principle of frequency shifting and multiplexing;

Figure 5 is a schematic diagram of the network working principle of the MUSE project;

Figure 6 is a schematic diagram of the frame structure of the DSLAM system;

7 is a logic block diagram of a modem section of an xDSL user interface board according to an embodiment of the present invention; FIG. 8 is a logic block diagram of a modem section of a xDSL user interface board in a splitter and demodulation combining according to an embodiment of the present invention;

FIG. 9 is a schematic structural diagram of a DSLAM of a user interface board according to an embodiment of the present invention; FIG. 10 is a schematic structural diagram of a small DSLAM according to an embodiment of the present invention. Mode for carrying out the invention

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

The embodiment of the invention provides a broadband user interface board and a broadband access device (such as a DSLAM as an example). As shown in FIG. 7 and FIG. 9, the two-way modem is taken as an example for description; in practical applications, one or more modems, such as 32-way or 48-way, etc., can also be applied, and those skilled in the art can easily Expand. In Figure 9, the user interface board includes a motherboard interface module, and further includes at least one uplink and downlink channel connected to the motherboard interface module.

Referring to Figure 7, Figure 7 is a logic block diagram of the modem portion of the xDSL user interface board. Figure 7 The sending channel (also called the downlink channel) includes at least a DSP, an AFE, a modulation filter circuit, and an electro-optical conversion module that are sequentially connected, and the downlink channel transmits the signal received from the motherboard interface module to the user end after being processed by the optical fiber; The receiving channel (also called the uplink channel) comprises at least a sequentially connected photoelectric conversion module, a demodulation filter circuit, an AFE, and a DSP sequence connection. The uplink channel receives the user terminal signal through the optical fiber, processes the signal, and passes the processed signal. The motherboard interface module is uplinked.

The DSP and AFE are digital modems of XDSL (ADSL or ADSL2 / ADSL2+/VDSL/VDSL2), and those skilled in the art will readily appreciate the use of other XDSL digital modems for processing. The photoelectric conversion module and the electro-optical conversion module can be two independent devices or integrated in the same module. Modulation is to frequency-shift the signal processed by the digital modulation and demodulation device, and then frequency-multiplex the signal after the multi-channel frequency is moved; demodulation is to perform frequency division and multiplexing on the multi-channel signal and input after moving. To the digital modem. 〉

An amplifier (possibly integrated into the AFE or the modulation and demodulation circuit) may be provided between the AFE of the downstream channel and the modulation filter circuit, and between the demodulation filter circuit of the upstream channel and the AFE.

The uplink channel and the downlink channel can be respectively connected to the user end through independent optical fibers. In this case, it is not necessary to apply the optical multiplexer/demultiplexer; of course, it is also possible to adopt optical multiplexing on the user side of the uplink channel and the downlink channel. The splitter uses an optical multiplexer/demultiplexer to respectively connect the electro-optical conversion module of the downlink channel and the photoelectric conversion module of the uplink channel, and the optical multiplexer and the optical demultiplexer respectively separate the optical signals received or locally transmitted through the optical fiber, The combination process ensures that one fiber can be shared between the uplink and the downlink. At this time, the light of different wavelengths may be used for the uplink and the downlink, and the same wavelength of light may be used.

When there are two channels or two or more modems, a combiner is arranged between each modulation filter circuit and the electro-optical conversion module of each downlink channel, and the combiner combines the multiple signals. Frequency division multiplexing is implemented; and, the combined signal is sent to the electro-optical conversion module for processing by the combiner. Further, a splitter is further disposed between each demodulation filter circuit and the photoelectric conversion module of each uplink channel, and the received multi-channel mixed signal is distributed to each demodulation filter circuit for processing by the splitter. Of course, if there is only one modem, there is no need for a combiner and a splitter.

Referring to FIG. 8, FIG. 8 is a logic block diagram of a modem section of an xDSL user interface board in a splitter and demodulation combining according to an embodiment of the present invention. As shown in FIG. 8, each signal can be demodulated and sent to each xDSL modem module separately, and the shunt and demodulation functions are integrated at this time; and, due to the use of a multi-channel demodulation device, Therefore, the splitter can be omitted.

Referring to FIG. 9, FIG. 9 is a schematic diagram of a DSLAM structure of a user interface board according to an embodiment of the present invention. As shown in FIG. 9, the broadband access device DSLAM applying the user interface board shown in FIG. 9 is composed of the following parts connected by a data bus and a control bus on a motherboard (not shown) - managing the entire DSLAM system The control board, the uplink interface board that provides the uplink data convergence interface, and the user interface board.

In particular, both DSP and AFE are devices in the DSL chipset. The multi-channel DSP is connected to the data bus and the control bus on the motherboard through the motherboard interface module, and is used for demodulating the data received from the optical fiber and sending it to the uplink interface board connected to the motherboard; otherwise, the The data of the uplink interface board is modulated and sent to the optical fiber. The optical multiplexer/demultiplexer is used to separate the optical signal received by the line from the locally transmitted optical signal, so that the upstream and downstream lights can share one optical fiber to save fiber resources. Of course, two optical fibers separated by uplink and downlink can also be used. To transmit, so there is no need to apply a multiplexer/demultiplexer.

The functions of DSP and AFE are unchanged from the prior art. Among them, the DSP completes the transmission direction xDSL framing, scrambling code, FEC coding, interleaving, constellation mapping, trellis coding, IFFT, plus cyclic prefix and time domain equalization in the receiving direction (may not) > de-cyclic prefix FFT, frequency domain Equalization, Viterbi decoding, de-constellation mapping, de-interleaving, FEC error correction, descrambling, user data recovery, etc.; AFE implementation of transmit direction digital / analog conversion, filtering, pre-position

S Amplify and receive direction low noise programmable amplification, AGC, filtering, analog to digital conversion and other analog domain signal processing functions. It is possible to integrate multiple xDSL processing channels into one DSP and one AFE.

In the transmit direction, as a buffer between the AFE and the modulator, the amplifier amplifies the analog signal output by the AFE to the appropriate amplitude and sends it to the modulator. Since the buffer circuit may be provided inside the AFE, the amplifier circuit is not necessary when a buffer circuit is provided inside the AFE. The modulator is used to frequency shift the signal to be transmitted so that the signal is modulated onto a carrier of a predetermined frequency. In practical applications, single sideband modulation, vestigial sideband modulation, or double sideband modulation may be employed; and, in order to improve bandwidth utilization, single sideband modulation and carrier suppression are generally employed. Of course, it is also possible to not suppress the carrier or to use double sideband modulation to reduce the complexity of the modulation and demodulation module.

Specifically, the double-sideband modulation can directly use envelope detection and demodulation, while the single-sideband modulation requires coherent demodulation, and it is necessary to generate a demodulated signal in phase with the same frequency of the modulated carrier, so the modulation process is slightly more complicated. Usually, each signal is modulated onto a different carrier frequency. The allocation rules of these carrier frequencies are determined in advance, and the spacing between each two adjacent carrier frequencies is usually equal and greater than or equal to the modulated signal. The width.

The modulated signal will be sent to the combiner module, and the combined multi-channel signal will be buffered and combined by the combiner module, and the combined broadband signal will be amplified to the required amplitude of the photoelectric conversion module; The conversion module receives the combined signal and converts the combined signal into an optical signal output. The intensity of the outputted optical signal is typically determined by the amplitude modulation result of the combined signal.

In the receiving direction, the multiplexer/demultiplexer sends the optical signal in the receiving direction to the photoelectric conversion module to convert it into an electrical signal and sends it to the splitter, and the splitter multiplies the received mixed signal to a plurality of signals. The demodulator performs demultiplexing and shifting. Wherein, the demultiplexing is to extract the frequency signal corresponding to the path from the multiplexed signal; the moving is to modulate the corresponding channel to the high frequency carrier. The xDSL signal is moved back to the original position (equivalent to the inverse processing of the processing shown in Figure 4). The result of the shifting process is that each xDSL consumes the frequency band defined by the original xDSL.

The shunted xDSL signal is filtered by low-pass filtering to be sent to the corresponding amplifying circuit, and the signal amplifier in the amplifying circuit acts as a buffer circuit between the low-pass filter and the AE, and is responsible for adjusting the signal to the AFE. The required amplitude is sent to the DSP for demodulation. Since there is an amplifier in the splitter and there is a buffer circuit inside the AFE, the amplifier circuit is not necessary. In addition, the splitter and the move-to-move function may be integrated in one module; or, the demodulator directly demodulates the multi-channel signal into multiple low-frequency signals, and the splitter may not be applied at this time.

It should be noted that: if single sideband modulation or suppression carrier is used, then the phase and frequency information of each carrier signal needs to be transmitted to the opposite end, and the opposite end uses the information for carrier recovery, and the recovered carrier is used. Perform coherent demodulation.

Referring to FIG. 10, FIG. 10 is a schematic structural diagram of a small DSLAM according to an embodiment of the present invention. As shown in Figure 10, embodiments of the present invention can be used with small DSLAMs (commonly referred to as pizza boxes). The way to implement a small DSLAM is usually to concentrate all the components of the general DSLAM on one board; the components include a control part and an uplink interface part connected to the control bus and the data bus, and at least one connected to the control bus and the data bus. The uplink and downlink channels, wherein: the downlink channel is composed of at least a DSP, an AFE, a modulation and filtering circuit, an electro-optical conversion module, and an optical fiber sequential connection, and the downlink channel is configured to process the signal received through the bus and transmit the optical fiber to the user end. The uplink channel is composed of at least an optical fiber, a photoelectric conversion module, a demodulation filter circuit, an AFE, and a DSP. The uplink channel is used to receive the user terminal signal through the optical fiber, and then the processed signal is uplinked through the bus.

The uplink channel and the downlink channel in FIG. 10 are respectively the same as the corresponding structures shown in FIG. 7, and are not described here again; and, in the uplink channel and the downlink channel, the same can be further set. The amplifier, combiner/splitter, combiner/demultiplexer, and the additional devices can be adjusted according to the specific use environment.

Finally, it should be noted that: the modulated bandpass filtering process is generally necessary, and the demodulated low-pass filtering process is generally necessary; and, the components performing these processes can be combined with other components (such as modulation and solution). Adjusted parts) combination settings. The multiplexer/demultiplexer is used in a single-fiber bidirectional transmission environment and can be removed in a dual-fiber bidirectional (each 3⁄4 fiber is responsible for only one direction) communication environment. It is necessary to apply the combiner when there is a multi-channel user interface, and it is not necessary to apply the combiner when it is single. The uplink channel and the downstream channel can share one DSP and one AFE, and can also use different DSPs and different AFEs respectively, and can also be processed by one DSP and one AFE.

It can be seen from the above that since the high-frequency modulation part and the xDSL interface part are not connected by a pair of lines, the transmission and reception are respectively connected, so there is no conversion from four lines to two lines and then from two lines to four lines. process. Since the 2-4 line conversion process is omitted, the broadband user access device and the broadband user access processing method provided by the embodiments of the present invention can significantly reduce the cost and effectively increase the port density.

Claims

Claim

A broadband user access device, comprising an uplink interface part, characterized in that it further comprises at least one uplink and downlink channel, wherein:

The downlink channel includes at least a serially connected digital modulation and demodulation device, a modulation filter circuit, and an electro-optical conversion module, and the signal received from the uplink interface is processed and transmitted to the user end by an optical fiber connected to the electro-optical conversion module;

2. The broadband user access device according to claim 1, wherein: said photoelectric conversion and electro-optic conversion are two devices independent of each other or integrated in the same module.

The broadband user access device according to claim 1 or 2, wherein: the uplink channel and the downlink channel are respectively connected to the user end by using independent optical fibers, or in the uplink channel and the downlink channel. Set the multiplexer/demultiplexer to share one fiber for the upstream and downstream channels.

The broadband user access device according to claim 3, wherein: a combiner is further connected between the modulation filter circuit and the electro-optical conversion module of the downlink channel, and the combiner is configured to combine the multiple signals. And sent to the electro-optical conversion module;

A splitter is further connected between the demodulation filter circuit of the uplink channel and the photoelectric conversion module, and the splitter is configured to split the received multi-channel mixed signal to the demodulation filter circuit.

The broadband user access device according to claim 4, wherein: the demodulation portion of the demodulation filter circuit and the splitter are combined in a multi-channel demodulator, and the multi-channel demodulation The device is connected to the photoelectric conversion module of the upstream channel.

The broadband user access device according to claim 1 or 2, characterized in that: The broadband user access device is a digital subscriber line access multiplexer DSLAM.

The broadband user access device according to claim 2, wherein: said digital modem device is a digital subscriber line modem device.

8. The broadband user access device of claim 1, wherein: the uplink interface comprises at least a motherboard interface module.

A broadband user access device, comprising a motherboard and a user interface board thereof, wherein the user interface board comprises a motherboard interface module, and further comprising at least one uplink connected to the motherboard interface module Downstream channel, where:

The downlink channel includes at least a serially connected digital modulation and demodulation device, a modulation filter circuit, and an electro-optical conversion module, and the signal received from the motherboard interface module is processed and transmitted by the optical fiber connected to the electro-optical conversion module to the user end; '

A broadband user access processing method, characterized in that: the optical fiber is used to transmit the digital subscriber line signal between the user end and the central office, and the uplink data and the downlink data are separately processed at the central office, wherein:

The broadband user access processing method according to claim 10, wherein the modulating comprises: performing frequency shifting on a signal processed by the digital modulation and demodulation device, and then performing multiplexed signals after frequency shifting Frequency division multiplexing

The demodulating includes: performing frequency decoding on a plurality of signals to be input to the digital modem device Sub-multiplex and move.

The broadband user access processing method according to claim 10 or U, characterized in that:

For the downlink data, after the modulation filtering is completed and before being converted into an optical signal, the downlink data of each channel is further processed;

For the uplink data, the converted electrical signal is further subjected to shunt processing after the conversion to the electrical signal and before the demodulation filtering.

The broadband user access processing method according to claim 10 or 11, wherein the modulation is single sideband modulation, vestigial sideband modulation, or double sideband modulation.