CN103152657B - Wave division multiplexing orthogonal frequency division multiplexing passive optical network (WDM-OFDM-PON) system based on shared transmitter energy-saving scheme - Google Patents

Abstract

A WDM-OFDM-PON system based on a shared transmitter energy saving scheme in the field of optical communications, comprising: a multi-longitudinal mode laser, a first circulator, a first wavelength division multiplexing device, an optical switch, and N first optical couplers , an orthogonal frequency division multiplexing transmitting device, a second wavelength division multiplexing device, N optical network units, a second circulator, a third wavelength division multiplexing device and N first optical receiving devices, an orthogonal frequency division multiplexing The transmitting device includes: N first electro-optic modulation units for modulating and amplifying the optical carrier and reflecting it, and N correspondingly connected to each first electro-optic modulation unit for generating orthogonal frequency division multiplexing electrical signals digital signal processing unit. The invention realizes that multiple wavelength channels (corresponding to multiple users) share the same orthogonal frequency division multiplexing transmitting device to transmit downlink data, thereby realizing the effect of energy saving.

Description

WDM-OFDM-PON System Based on Shared Transmitter Energy Saving Scheme

technical field

The present invention relates to a system in the technical field of optical communication, in particular to a wavelength division multiplexing-orthogonal frequency division multiplexing-passive optical network (WDM-OFDM-PON) system based on a shared transmitter energy saving scheme.

Background technique

Information and Communication Technology (ICT) has brought earth-shaking changes to human society, but it also consumes more and more energy and releases more and more greenhouse gases. According to statistics, the energy consumed by various equipment and devices required by ICT has accounted for 8% of the world's total energy consumption. Moreover, with the rapid growth of user data bandwidth and the number of network users in recent years, the energy consumed by ICT will increase exponentially in the foreseeable future, which will lead to energy depletion and the development of ICT will become unsustainable.

In the ICT field, the optical fiber access network consumes about 70% of the energy consumed by the entire telecommunication network due to the large number of active devices. Therefore, many scholars and researchers have devoted their energy to the exploration of energy-saving solutions for access networks. After detailed statistical analysis of data, the paper entitled "Energy consumption inwired and wireless access networks" published in IEEE Communication Magazines pointed out that the passive optical network (PON) structure is an access network with the least energy consumption and the highest energy efficiency. At present, a large number of documents and various standards focus on the energy-saving schemes realized in time-division multiplexing passive optical networks (TDM PON) such as EPON and GPON that have been laid. (WDMPON) The research on how to realize energy saving is still relatively small. As the preferred solution for the next generation of PON, WDM PON has the advantages of large bandwidth, easy upgrade and high security, and the introduction of OFDM technology can greatly improve the spectrum utilization rate, and it may be commercialized in the next ten to twenty years. However, WDM technology needs to install corresponding transceivers for each user, and OFDM technology needs to use high-speed digital signal processing (DSP) chips with high energy consumption, which will greatly increase the power consumption in PON. Therefore, research on WDM-OFDM- The energy-saving scheme in PON has very important significance.

After searching the existing literature, it is found that the paper "A Cost-effective Pilot-Tone-based Monitoring Technique for Power Saving in RSOA-based WDM-PON" in the Optical Fiber Communication Conference (Optical Fiber Communication Conference) 2011 (based on RSOA wavelength division multiplexing Energy Saving Scheme Using Pilot Monitoring Technology in Passive Optical Networks)", proposed an energy saving mode that uses the monitoring signal sent by RSOA in WDM PON to control the switch of devices in PON. The principle of the scheme is as follows: the optical line terminal (OLT) is connected to the remote node (RN) by a feeder fiber, and the arrayed waveguide grating (AWG) at the RN is used to transfer the 16-32 The wavelength demultiplexing, the signal carried on each wavelength is sent to the optical network unit (ONU) through the distributed fiber (distributed fiber), at the ONU end, most of the downlink data is used to receive and restore the downlink data, and the other part Enter the reflective semiconductor optical amplifier (RSOA) to modulate and amplify the uplink signal. After passing through the circulator, the uplink signal returns to the _optical line terminal according to the original line; when there is no When the uplink and downlink data pass through, the optical line terminal and the ONU end will turn off all the transceivers corresponding to this wavelength channel and enter the sleep mode; when an ONU _k needs to send data, it will modulate a signal on the RSOA of the ONU end. A clock signal with a frequency of several megahertz, so that the amplified stimulated radiation noise (ASE) emitted by RSOA will carry a signal of this frequency. At the optical line terminal, another receiver specially monitoring the ONU terminal signal will detect this signal. clock signal, so as to determine that the ONU _k is to send a signal, the transceiver of the corresponding optical line terminal is turned on to realize the uplink and downlink transmission of the signal. This energy-saving solution based on RSOA monitoring signals can make the optical access network system enter sleep mode when there is no information transmission, and wake up the transceiver equipment of the optical line terminal through the monitoring signal sent by RSOA, so as to achieve a certain degree of energy saving, but there are still The following two disadvantages: (1) The traffic of the network is often bursty and intermittent, so the devices at the optical line terminal need to be switched frequently, which will damage the performance and life of the optical line terminal transceiver device; (2) the sleep mode is It runs in a "sleep-on-sleep" cycle mode. Even if there is no data transmission, it needs to be turned on periodically. According to the document "EPON Powersaving via Sleep Mode", the turn-on time of sleep mode accounts for the total 1/5 of the time, so about 20% of the energy is wasted.

Contents of the invention

The present invention aims at the above-mentioned deficiencies existing in the prior art, and provides a WDM-OFDM-PON system based on a shared transmitter energy-saving scheme, and realizes multiple wavelength channels (corresponding to Multiple users) share the same OFDM signal transmitting device to transmit downlink data, so as to achieve the effect of energy saving.

The present invention is achieved through the following technical solutions, and the present invention includes: a multi-longitudinal-mode laser generating N optical carriers of different wavelengths, a first circulator, a first wavelength division multiplexing device, one end having N input ports and another An optical switch with N ² output ports at one end, N first optical couplers (OC) with N input ports at one end and 1 output port at the other end, an orthogonal frequency division multiplexing (OFDM) transmitting device, the first Two wavelength division multiplexing devices, N optical network units (ONUs), a second circulator, a third wavelength division multiplexing device and N first optical receiving devices, wherein:

The multi-longitudinal mode laser generates N optical carriers of different wavelengths, the first port and the second port of the first circulator are respectively connected to the output end of the laser and the input end of the first wavelength division multiplexing device, and the first wavelength division multiplexing The N output ports of the device are respectively connected to the N input ports of the optical switch to transmit N optical carriers of different wavelengths; the N ² outlets of the optical switch are respectively connected to the N input ports of the N first optical couplers to transmit N different optical carriers; the output ports of the N first optical couplers are respectively connected to the input ports of the OFDM transmitting device;

The OFDM transmitting device includes: N first electro-optic modulation units for modulating and amplifying the optical carrier and reflecting it, N correspondingly connected to each first electro-optic modulation unit for generating orthogonal frequency A digital signal processing unit for division multiplexing (OFDM) electrical signals, wherein:

When the sum of the user downlink data rates carried on k (1≤k≤N) optical carriers is less than the modulation rate of a single first electro-optical modulation unit, the k optical carriers are all input to the same first electro-optic modulation unit by electrically controlling the optical switch The electro-optical modulation unit, so that other k-1 first electro-optic modulation units and k-1 corresponding digital signal processing units are idle; the digital signal processing unit generates an OFDM that contains the downlink data required by k users The electrical signal is transmitted to the first electro-optical modulation unit, wherein the downlink data required by different users occupies different numbers of sub-carriers of the electrical signal according to their rates, and the first electro-optical modulation unit modulates the electrical signal onto k optical carriers After generating k downlink optical signals, each downlink optical signal is amplified and reflected back to the first circulator;

The first port of the second circulator is connected to the third port of the first circulator, the second port is connected to the input end of the second wavelength division multiplexing device, and the output end of the second wavelength division multiplexing device is respectively distributed through the corresponding The optical fiber is connected to N optical network units, and the N downlink optical signals transmitted from the first circulator are demultiplexed and transmitted to each optical network unit;

The input end of the third wavelength division multiplexing device is connected to the third port of the second circulator, and the output end is connected to N first optical receiving devices respectively, and the third wavelength division multiplexing device receives the uplink sent from each optical network unit The optical signal is then demultiplexed and transmitted to each first optical receiving device respectively, and the first optical receiving device receives the uplink optical signal and recovers the uplink data.

The downlink data required by different users occupies different numbers of subcarriers of the OFDM electrical signal according to their rates, which is realized by a digital signal processing unit, which includes: The conversion unit that needs to convert the downlink data from serial data to parallel data, the code pattern mapping unit used to perform quadrature amplitude modulation on the parallel data converted by the previous unit, and the fast Fourier transform unit used to convert the data modulated by the previous unit The calculation unit of the inverse transform operation (IFFT), the pre-unit for inserting the data generated by the previous unit into a cyclic prefix (cyelic prefix) to form a data stream, and performing digital-to-analog conversion on the data stream to form an orthogonal frequency division multiplexing (OFDM) electrical signal and transmit the electrical signal to the signal generation unit of the first electro-optic modulation unit.

The quadrature amplitude modulation is a modulation method with 16 symbols.

The insertion of the cyclic prefix is specifically to copy the last 20 symbols of each block signal of the data and place them at the head end of the block signal to form a serial data stream of 276 symbols as a block signal.

The interval between the N wavelengths of the optical carrier generated by the multi-longitudinal-mode laser is consistent with the channel interval of the first wavelength division multiplexing device and the second wavelength division multiplexing device.

The first wavelength division multiplexing device, the second wavelength division multiplexing device and the third wavelength division multiplexing device are arrayed waveguide gratings (AWG).

The optical network unit includes: N second optical couplers with one input port and two output ports, a second optical receiving device for receiving downlink optical signals and recovering user downlink data, and a second optical receiving device for modulating and amplifying The second electro-optical modulation unit for reflecting the optical carrier, wherein: the input ports of each second optical coupler are connected with the second wavelength division multiplexing device, and the first output ports are respectively connected with each second light receiving device for transmission The downlink optical signal demultiplexed by the second wavelength division multiplexing device; the second output port of the second optical coupler is connected to the second electro-optic modulation unit, and transmits the downlink optical signal as an optical carrier for loading uplink data, and the second electro-optic The modulation unit modulates and amplifies the optical carrier with the uplink data and reflects the generated uplink optical signal back to the second optical coupler, and the uplink optical signal passes through the second optical coupler, the second wavelength division multiplexing device and the second circulator. The third port is input to the third wavelength division multiplexing device.

The first electro-optic modulation unit and the second electro-optic modulation unit are used to modulate the electrical signal onto the optical carrier to generate an uplink or downlink optical signal modulation function, and to amplify the generated uplink or downlink optical signal. Optical amplification function And a reflection function for reflecting uplink or downlink optical signals.

The input end of the third wavelength division multiplexing device is connected to the third port of the second circulator through a feeder fiber.

The technical principle of the solution of the present invention is as follows: in the general non-energy-saving operation mode, each optical carrier output from the output port of the first wavelength division multiplexing device is connected to the corresponding N first electro-optical modulation units through an optical switch, and N is a natural constant The first electro-optic modulation unit is loaded with an electrical signal generated by the digital signal processing unit. At this time, regardless of the downlink rate on each wavelength channel, the N first electro-optic modulation units and their associated N digital signal processing units need to be turned on.

In the energy-saving operation mode proposed by us, when the downlink rate on some wavelength channels is small, for example, the sum of the downlink data rates on the three wavelength channels λ _i , λ _m and λ _n is less than the maximum of a single first electro-optic modulation unit The modulation rate can be adjusted by adjusting the optical switch so that the three optical carriers of λ _i , λ _m and λ _n are input to a first electro-optic modulation unit i, and the first electro-optic modulation unit modulates the electrical signal, wherein the subcarrier of the electrical signal Load user downlink data on channels i, m and n respectively. In this way, the other two first electro-optic modulation units m, n and the corresponding digital signal processing units m, n can be turned off, thereby saving energy. During the operation of the passive access network, the downlink signal rate on each wavelength channel will change with time, and by dynamically adjusting the optical switch, a part of the first electro-optical modulation unit and the related digital signal processing unit can be turned off , thus saving power consumption.

Beneficial effect

The present invention dynamically adjusts the optical switch according to the change of the downlink rate of each channel, so that multiple wavelength channels can share a single OFDM transmitting device, thereby turning off the remaining OFDM transmitting devices, greatly reducing optical The power consumption of the line terminal; at the optical line terminal OFDM transmitting device, the subcarrier dynamic allocation method of the OFDM signal is used, that is, the downlink data of different users occupies the electrical signal according to their different rates Different subcarriers make the downlink data of multiple channels modulated into the same electrical signal, and different numbers of subcarriers can be flexibly modulated according to the rate of each downlink data, and the modulation and demodulation are relatively easy and convenient; in the optical network unit end, a part of the downlink optical signal is used as the light source of the second electro-optical modulation unit, without installing a special adjustable laser in the optical network unit, which saves the construction cost of the passive optical network; in addition, this embodiment utilizes the first An electro-optic modulation unit is used as a transmitter of the downlink optical signal, and has the functions of simultaneous amplification and modulation, which simplifies the structure of the optical line terminal.

Description of drawings

Fig. 1 is the structural representation of embodiment 1;

Fig. 2 is a schematic diagram of the generation of OFDM electrical signals in Embodiment 1;

FIG. 3 is a schematic diagram of downlink optical signal transmission in Embodiment 1;

Fig. 4 is the spectrum diagram of the OFDM electrical signal in Embodiment 1;

Fig. 5 obtains bit error rate curve figure for embodiment 1;

FIG. 6 is a graph of energy saving efficiency of Embodiment 1. FIG.

Detailed ways

The embodiments of the present invention are described in detail below. This embodiment is implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operating procedures are provided, but the protection scope of the present invention is not limited to the following implementation example.

Example 1

As shown in Figure 1, this embodiment includes: a multi-longitudinal-mode laser 1 generating N optical carriers of different wavelengths, a first circulator 2, a first wavelength division multiplexing device 3, one end having N input ports and An optical switch 4 with N ² output ports at the other end, N first optical couplers 5 with N input ports at one end and 1 output port at the other end, an orthogonal frequency division multiplexing transmitting device, a second wavelength division Multiplexing device 6, N optical network units 7, second circulator 8, third wavelength division multiplexing device 9 and N first optical receiving devices 10, wherein:

Multi-longitudinal mode laser 1, first circulator 2, first wavelength division multiplexing device 3, optical switch 4, first optical coupler 5, orthogonal frequency division multiplexing transmitting device, second circulator 8, third wave The multiplexing device 9 belongs to the optical line terminal;

The downlink optical signal sent from the optical line terminal to the optical network unit 7 is generated by the multi-longitudinal mode laser 1. The optical carrier of N wavelengths, the first port and the second port of the first circulator 2 are respectively connected to the output of the multi-longitudinal mode laser 1 end, the input end of the first wavelength division multiplexing device 3 is connected, and N output ports of the first wavelength division multiplexing device 3 are respectively connected with N input ports of the optical switch 4 to transmit optical carriers of N different wavelengths; The ^N2 outlets of the switch 4 are respectively connected to the N input ports of the N first optical couplers 5 to transmit N different optical carriers; the output ports of the N first optical couplers 5 are respectively connected to the OFDM Connect with the input port of the transmitter;

The OFDM transmitting device includes: N first electro-optic modulation units 11 for modulating and amplifying the optical carrier and reflecting it, N correspondingly connected to each first electro-optic modulation unit 11 for generating positive A digital signal processing unit 12 for cross-frequency division multiplexing electrical signals, wherein:

When the sum of the user downlink data rates carried on k (1≤k≤N) optical carriers is less than the modulation rate of a single first electro-optic modulation unit 11, the k optical carriers are all input to the same The first electro-optic modulation unit 11, so that other k-1 first electro-optic modulation units 11 and k-1 corresponding digital signal processing units 12 are idle; the digital signal processing unit 12 generates an OFDM electrical signal and It is transmitted to the first electro-optical modulation unit 11, wherein the downlink data of different users occupies different numbers of subcarriers of the electrical signal according to their rates, and the first electro-optic modulation unit 11 modulates the electrical signal onto k optical carriers to generate k After the downlink optical signal, each downlink optical signal is amplified and reflected back to the first circulator 2;

When the sum of the downlink rates of the k optical carriers is greater than the modulation rate of a single first electro-optic modulation unit 11, the k optical carriers are all input to two or more first electro-optic modulation units 11 by electrically controlling the optical switch 4 ;

The first port of the second circulator 8 is connected with the third port of the first circulator 2, the second port is connected with the input end of the second wavelength division multiplexing device 6, and the output ends of the second wavelength division multiplexing device 6 are respectively Connecting to N optical network units 7 through corresponding distribution optical fibers, demultiplexing the N downlink optical signals transmitted here from the first circulator 2 and transmitting them to each optical network unit 7 respectively;

The input end of the third wavelength division multiplexing device 9 is connected with the third port of the second circulator 8, and the output end is connected with N first optical receiving devices 10 respectively, and the third wavelength division multiplexing device 9 receives signals from each optical network. The uplink signal sent by the unit 7 is demultiplexed and transmitted to each first optical receiving device 10 respectively, and the first optical receiving device 10 receives the uplink optical signal and recovers the uplink data.

As shown in FIG. 2 , the downlink data of different users occupy different numbers of subcarriers of the electrical signal according to their rates, which is realized by the digital signal processing unit 12, which includes: A conversion unit for converting data from serial data to parallel data, a code pattern mapping unit for performing quadrature amplitude modulation (QAM) on the parallel data converted by the previous unit, and performing fast Fourier on the data modulated by the previous unit The calculation unit of the leaf inverse transform operation (IFFT), the pre-unit for inserting the data generated by the previous unit into a cyclic prefix (cyelic prefix) to form a data stream, and performing digital-to-analog conversion on the data stream to form an OFDM Use (OFDM) electrical signals and transmit the electrical signals to the signal generation unit of the first electro-optical modulation unit 11 .

The quadrature amplitude modulation is a modulation method with 16 symbols.

The insertion of the cyclic prefix is specifically to copy the last 20 symbols of each block signal of the data and put them at the head end of the block signal to form a serial data stream of 276 symbols as a block signal.

In this embodiment, the digital signal processing unit 12 uses a digital processing chip (DSP) based on the inverse fast Fourier transform operation, which is used to convert the serially entered binary data into electrical signals to complete serial data conversion, code pattern Mapping, inverse fast Fourier transform operation (IFFT), inserting cyclic prefix (cyelic prefix) processing; and using an arbitrary waveform generator (AWG) to complete digital-to-analog conversion.

The optical network unit 7 includes: N second optical couplers 13 with one input port and two output ports, a second optical receiving device 14 for receiving downlink optical signals and recovering user downlink data, and A second electro-optical modulation unit 15 that modulates and amplifies the optical carrier and reflects it, wherein: the input ports of each second optical coupler 13 are connected to the second wavelength division multiplexing device 6, and the first output ports are respectively connected to each second The two optical receiving devices 14 are connected to transmit the downlink optical signal demultiplexed by the second wavelength division multiplexing device 6; the second output port of the second optical coupler 13 is connected to the second electro-optic modulation unit 15, and transmits the downlink optical signal as The optical carrier loaded with uplink data, the second electro-optical modulation unit 15 modulates and amplifies the optical carrier with the uplink data and reflects the generated uplink optical signal back to the second optical coupler 13, and the uplink optical signal passes through the second optical coupler 13, The third port of the second wavelength division multiplexing device 6 and the second circulator 8 is input to the third wavelength division multiplexing device 9 .

The first electro-optic modulation unit 11 and/or the second electro-optic modulation unit 15 are used to modulate an electrical signal onto an optical carrier to generate an uplink or downlink optical signal, and are used to amplify the generated uplink or downlink optical signal The optical amplifying device and the reflecting device for reflecting the uplink or downlink optical signal.

In this embodiment, the first electro-optic modulation unit 11 and the second electro-optic modulation unit 15 use a reflective semiconductor optical amplifier (RSOA) to complete modulation and amplification processing.

The first light receiving device 10 and/or the second light receiving device 14 use: a photodetector for receiving uplink or downlink optical signals and a digital processing chip (DSP) for recovering uplink or downlink data.

The spacing between the N wavelengths of the multi-longitudinal mode laser 1 (MML) used in this embodiment is consistent with the channel spacing of the first and second wavelength division multiplexing devices 6 .

The first wavelength division multiplexing device 3, the second wavelength division multiplexing device 6 and the third wavelength division multiplexing device 9 are arrayed waveguide gratings (AWG), which are 1xN wavelength division multiplexing/demultiplexing devices, containing Mixed signals of N wavelengths enter from the entrance of the arrayed waveguide grating, and signals with different wavelengths are output from the N ports; similarly, if N optical signals corresponding to the wavelengths are input at the N ports, the N optical signals can be output at the output port multiplexed into one fiber.

The input end of the third wavelength division multiplexing device 9 is connected to the third port of the second circulator 8 using a feeder fiber. In this embodiment, the feeder fiber is a standard single-mode fiber with a length of 20km. Its The loss attenuation coefficient is 0.2dB/km.

In this embodiment, the optical switch 4 uses an electronically controlled mechanical optical switch 4 .

In this embodiment, the distribution optical fiber is a standard single-mode optical fiber with a length of 1-5 km, and its function is to transmit optical signals of corresponding wavelengths to the optical network unit 7 .

As shown in FIG. 3 , in this embodiment, three channel wavelengths share one OFDM transmitting device as an example to analyze the generation principle of downlink optical signals in detail. The upper part of the optical line terminal is a digital signal processing unit 12, which is used to generate OFDM electrical signals, and the lower part is electro-optic modulation to generate downlink optical signals. In the previous part, the downlink data in the channels i, m and n are input to the digital signal processing unit 12, and an electrical signal is generated through the process shown in FIG. 2 . In the next part, the optical carriers whose wavelengths are respectively λi, λm and λn emitted by the multi-longitudinal-mode laser 1 pass through a 3x1 optical coupler and then enter the first electro-optic modulation unit 11, that is, the reflective semiconductor optical amplifier of this embodiment is completed Optical signal modulation, amplification processing, optical signal through 25km feeder fiber, to the arrayed waveguide grating at the remote node. After being demultiplexed by the arrayed waveguide grating, the three wavelengths are respectively transmitted by the distribution optical fiber to the respective optical network unit 7 for reception and demodulation to obtain respective downlink data.

As shown in Figure 4, (a) is under the energy-saving scheme, when three channels i, m and n share the downlink data of the first electro-optic modulation unit 11, the orthogonal frequency division multiplexing OFDM signal generated by the digital signal processing unit 12 Electrogram. The OFDM electrical signal has a total of 256 subcarriers, and the code pattern format modulated on each subcarrier is 16QAM, in which the downlink data on channels i and n each occupy 32 subcarriers, and the downlink data on channel m occupies 64 subcarriers. carrier, and the remaining subcarriers do not carry any data. It can be seen from Figure (a) that channels i and n occupy a signal bandwidth of about 0.625 GHz, and channel m occupies a signal bandwidth of about 1.25 GHz. Figures (b), (c) and (d) show that channels i, m and n respectively use the first electro-optic modulation unit 11i, the first electro-optic modulation unit 11m and the first electro-optic modulation unit 11n to transmit downlink in the non-energy-saving operation mode. For data, the frequency spectrum diagram of each OFDM electrical signal.

As shown in FIG. 5 is the bit error rate curve obtained by the solution of the present invention. Figure (a) is the bit error curve of the downlink data obtained under the energy-saving scheme. The black curve is the bit error curve measured in the back-to-back situation. Under the bit error rate of 10e ^-3 , the received power is about -19.6dBm, The red curve is the bit error curve measured under the condition of transmitting 25km feeder fiber. Under the bit error rate of 10e ^-3 , the received power is about -18.8dBm. Figure (b) is the bit error curve of the downlink data obtained in the non-energy-saving operation mode. The black curve is the bit error curve measured in the back-to-back situation. Under the bit error rate of 10e ^-3 , the received power is about -19.9dBm , the red curve is the bit error curve measured under the condition of transmitting 25km feeder fiber, under the bit error rate of 10e ^-3 , the received power is about -19dBm. It can be seen from the bit error curve that the energy-saving solution has only about 0.2-0.3dBm impact on the performance of the original WDM-OFDM-PON solution, which is relatively small.

As shown in FIG. 6 is a schematic diagram of the energy saving efficiency of the solution of the present invention. The vertical axis of the schematic diagram represents the number of OFDM transmitting devices that need to be turned on by the optical line terminal, and the horizontal axis represents 24 hours of a day. We know that the amount of network traffic varies with the time of day, with the least amount of network traffic occurring between 3:00 am and 6:00 am. Therefore, at this time, the number of OFDM transmitting devices turned on under the energy-saving scheme is the least, which is about 1/3. The black curve in the figure represents the number of OFDM transmitters that need to be turned on in ordinary wavelength division multiplexing-orthogonal frequency division multiplexing-passive optical network WDM-OFDM-PON, which has always been 32 (here it is assumed that wavelength division multiplexing The total number of channels of the passive optical network WDM-PON is 32). The red curve represents the change of the number of ON-OFDM transmitters with time under the operation of the energy-saving scheme. It can be seen from the figure that the energy consumption of the optical line terminal can be reduced by 33.6% by using the energy-saving scheme of the present invention.

Example 2

Refer to Embodiment 1 for other settings, but in this embodiment, the first electro-optic modulation unit 11 and the second electro-optic modulation unit 15 use a Mach-Zehnder modulator (MZM) to modulate the optical signal and an erbium-doped fiber amplifier (EDFA) to amplify the optical signal .

In this embodiment, the first light receiving device 10 and/or the second light receiving device 14 use: an optical receiver (Rx) array for receiving uplink and downlink signals and recovering uplink and downlink data.

Claims (8)

1. wavelength division multiplexing-OFDM-the passive optical network based on shared transmitter energy-saving scheme, it is characterized in that, comprising: Multi-Longitudinal Mode laser of light carrier producing N number of different wave length, the first circulator, the first WDM device, one end have N number of input port and the other end has N ²the optical switch of individual output port, N number of one end have N number of input port and the other end has the first optical coupler of 1 output port, orthogonal frequency division multiplex ransmitting injection device, the second WDM device, N number of optical network unit, the second circulator, the 3rd WDM device and N number of first optical pickup apparatus, wherein:

Downlink data produces the light carrier of N number of wavelength by Multi-Longitudinal Mode laser, first port of the first circulator is connected with the output of Multi-Longitudinal Mode laser, the input of the first WDM device respectively with the second port, and N number of output port of the first WDM device is connected with N number of input port of optical switch the light carrier transmitting N number of different wave length respectively; The N of optical switch ²individual outlet is connected to transmit N number of different light carrier from N number of input port of N number of first optical coupler respectively; The output port of N number of first optical coupler is connected with the input port of orthogonal frequency division multiplex ransmitting injection device respectively;

Orthogonal frequency division multiplex ransmitting injection device comprises: N number of for modulating and amplifying light carrier and carried out the first electrooptic modulation unit, the respectively N number of digital signal processing unit for there is the OFDM signal of telecommunication that be connected corresponding to each the first electrooptic modulation unit that reflect, wherein:

When the downstream data rate sum that k light carrier carries is less than the modulation rate of single first electrooptic modulation unit, 1≤k≤N, k light carrier is made all to be input to same first electrooptic modulation unit by electric control optical switch, thus idle other k-1 the first electrooptic modulation unit and the individual corresponding digital signal processing unit of k-1; Digital signal processing unit produces an OFDM signal of telecommunication and transfers to the first electrooptic modulation unit, wherein the downlink data of different user occupies the different number of sub carrier wave of this signal of telecommunication according to the difference of its speed, is carried out amplifying by each downlink optical signal and be reflected back the first circulator after this signal of telecommunication is modulated to and k light carrier produces k downlink optical signal by the first electrooptic modulation unit;

First port of the second circulator is connected with the 3rd port of the first circulator, second port is connected with the input of the second WDM device, and the output of the second WDM device is connected from the first circulator, the N number of downlink optical signal transmitted so far carries out demultiplexing and transfers to each optical network unit respectively respectively by the profile fiber of correspondence with N number of optical network unit;

The input of the 3rd WDM device is connected with the 3rd port of the second circulator, output is connected with N number of first optical pickup apparatus respectively, and the 3rd WDM device is carried out demultiplexing after receiving the uplink optical signal sent from each optical network unit and transferred to each first optical pickup apparatus respectively and recover upstream data after receiving uplink optical signal by the first optical pickup apparatus.

2. system according to claim 1, it is characterized in that, the downlink data of described different user, the different number of sub carrier wave of this signal of telecommunication is occupied according to the difference of its speed, this is realized by digital signal processing unit, this unit comprises: for user's downlink data to be converted to the converting unit of parallel data from serial data, for the parallel data of last cell translation being carried out the pattern map unit of quadrature amplitude modulation, for the data of last cells modulate being carried out the computing unit of inverse fast Fourier transform computing, data for being produced by last unit are carried out inserting circulation prefix processing and are formed the front end units of data flow and data flow carried out digital-to-analogue conversion and form the OFDM signal of telecommunication by the signal generating unit of this electric signal transmission to the first electrooptic modulation unit.

3. system according to claim 2, is characterized in that, described quadrature amplitude modulation is a kind of modulation system of 16 kinds of symbols.

4. system according to claim 2, is characterized in that, described insertion Cyclic Prefix is placed on the head end of block signal after specifically end 20 code elements of each block signal of data being copied, and 276 code elements forming serial are the data flow of a block signal.

5. system according to claim 1, is characterized in that, the interval between N number of wavelength of the light carrier that described Multi-Longitudinal Mode laser produces is consistent with the channel spacing of the first WDM device and the second WDM device.

6. system according to claim 1, is characterized in that, the first described WDM device, the second WDM device and the 3rd WDM device are array waveguide grating.

7. system according to claim 1, it is characterized in that, described optical network unit comprises: N number of the second optical coupler having an input port and 2 output ports, for receiving downlink optical signal and recovering the second optical pickup apparatus of user's downlink data, for modulating and amplifying light carrier and carried out the second electrooptic modulation unit of reflecting, wherein: the input port of each the second optical coupler is all connected with the second WDM device, first output port is connected with each second optical pickup apparatus the downlink optical signal transmitted by the second WDM device demultiplexing respectively, second output port of the second optical coupler is connected with the second electrooptic modulation unit, transmission downlink optical signal is as the light carrier loading upstream data, second electrooptic modulation unit upstream data is modulated light carrier and is amplified and the uplink optical signal of generation is reflected back the second optical coupler, and uplink optical signal is input to the 3rd WDM device via the 3rd port of the second optical coupler, the second WDM device and the second circulator.

8. system according to claim 1, is characterized in that, the input of the 3rd described WDM device is use feeder fiber to be connected with the 3rd port of the second circulator.