CN101013930B - Optical access network system - Google Patents
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- CN101013930B CN101013930B CN 200610169214 CN200610169214A CN101013930B CN 101013930 B CN101013930 B CN 101013930B CN 200610169214 CN200610169214 CN 200610169214 CN 200610169214 A CN200610169214 A CN 200610169214A CN 101013930 B CN101013930 B CN 101013930B
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Abstract
An optical access network system capable of transmitting and receiving high-speed signals and which allows the number of subscribers to be increased without increasing the number of wavelengths used is provided. An optical line terminal and an optical network unit are joined via an optical fiber transmitting line, a star coupler, and a plurality of branching optical fiber transmitting lines. The optical line terminal and optical network unit are constituted comprising an optical processing section and an electrical processing section. The optical processing section comprises a light-emitting element and a light-receiving element. The electrical processing section comprises a transmitting signal processing section that generates an encoded transmitting signal in the form of an electrical signal by encoding a transmitting signal and a receiving signal processing section that obtains a receiving signal by decoding a code-division-multiplexed signal that has been converted from optical-signal form to electrical-signal form by the light-receiving element. The optical access network system is characterized in that the decoding processing circuit that the receiving signal processing section comprises is constituted comprising an analog matched filter and a decision circuit.
Description
Technical field
The present invention relates in PON (Passive Optical Network, EPON), be used for the optical access network system that service provider and entrant utilize code division multiplexing (CDM:Code Division Multiplexing) mode to communicate.
Background technology
Paying close attention to via PON the service provider (also is being called ' center ' later on sometimes.) and a plurality of entrant (also be called ' user ' later on sometimes.) connect and the optical access network system of formation.In the explanation afterwards; Sometimes the device with service provider's side is called optical line terminal device or OLT (Optical Line Terminal; Optical line terminal), sometimes the device of entrant's side is called optical terminal device or ONU (Optical Network Unit, optical network unit).
PON is connecting as the light clutch of passive component midway and an optical fiber transmission path is separated into a plurality of optical fiber transmission paths at optical fiber transmission path; With this light clutch is the network (for example, with reference to non-patent literature 1) of a plurality of optical terminal devices of the star-like connection in center.Through to the network using PON between connection center and user, a plurality of users can Sharing Center and the light clutch between optical fiber transmission path, and can the suppression equipment cost.
In utilizing the optical access network system in the past of PON, adopt time division multiplexing (TDM:Time Division Multiplexing) mode, discern user's (for example, with reference to non-patent literature 2) through the time slot of control TDM signal to each channel allocation.Here, (also be called ' upward signal ' later on sometimes from the signal of user to the center.) and therefrom mind-set user's signal (also be called ' downstream signal ' later on sometimes.) the use wavelength optical signals.This is because upward signal and downstream signal are shared an optical fiber transmission path, therefore in order to discern upward signal and downstream signal based on the difference of wavelength.Upward signal separates through optical band pass filter with downstream signal and is synthetic, each user with in the heart signal close ripple and partial wave through the light clutch.
On the other hand, in utilizing the optical access network system of PON, also consider to transmit the method (for example, with reference to non-patent literature 3) of upward signal with wavelength division multiplexing (WDM:Wavelength Division Multiplexing) mode.But,,, therefore need dwindle the wavelength interval of the channel of distributing to adjacency because the wavelength band width that can utilize is limited in order to increase the multiplexing number of channel (being number of users here).Like this,, need the wavelength stability of light source, need a lot of equipment costs for guaranteeing this stability in order to dwindle the wavelength interval.
Therefore, the number of wavelengths that does not preferably increase utilization just makes the multiplexing number of channel increase and transmission capacity is increased.As one of its method, consider to carry out the method for communicating (for example, with reference to patent documentation 1) between center and the user through the CDM transmission.
In patent documentation 1 disclosed communication means, take the signal of telecommunication of transmission is taken advantage of a yard computing, after up-converting to wireless frequency (RF:Radio Frequency) signal, convert the method for optical transmission signal into.In addition, in patent documentation 2, in the disclosed passive-type entrant network, be employed in the signal of telecommunication of transmission is taken advantage of the method that converts optical transmission signal into and transmit after yard computing, and also comprise the WDM mode that adopts in addition.Here, send light signal and receiving optical signals and use the method for carrying out deciliter through light circulator, transmission light signal and receiving optical signals use same wavelength.
In patent documentation 1 and 2, in disclosed each device, multiply by the sign indicating number synchronous to received signal with transmitter side for receiving signal.The structure example of the receiver that for this reason utilizes discloses in non-patent literature 4.In this receiver, after the RF signal is converted into the signal of telecommunication of base band,, generate the auto-correlation waveform through digital shift register and digital correlation arithmetic unit by the A/D conversion, receive signal thereby take out.
Through PON is adopted the CDM mode, can not increase the multiplexing number of channel (corresponding to number of users even do not increase the number of wavelengths of utilization yet.)。
[non-patent literature 1] horizontal fields etc., ' light ア Network セ ス シ ス テ system ATM-PON ' Oki Electric researchs and develops No. 182, Vol.67, No.1, in April, 2000
[non-patent literature 2] Ian M.McGregor; Et al. " Implementation of a TDMPassive Optical Network for Subscriber Loop Applications ", J.LightwaveTechnology, Vol.7; No.11, November 1989
[non-patent literature 3] K.W.Lim.et al. " Fault Localization in WDM PassiveOptical Network by Reusing Downstream Light Sources "; IEEE PhotonicsTechnology Letters Vol.17; No.12, December 2005
[non-patent literature 4] Rushikesh S.Kalaspurkar, et al. " PerformanceEvaluation of a Recurring State Dynamic Digital Matched Filter forDS-CDMA ", IEEE 2003
[patent documentation 1] Japan special table 2001-512919 communique
[patent documentation 2] TOHKEMY 2004-282742 communique
But, if carry out to comprise the signal of telecommunication of transmission is taken advantage of yard computing and up-converted to the light access method of pass through the PON realization of A/D switch process of step and the A/D converter of RF signal, then produce following problem.That is,, there is following difficulty as being that the situation of the signal (signal of high bit rate) of the high speed of 100Mbit/s is that an example describes with transmitting-receiving bit rate (bit rate).In this case, for being the diffusion rate subsistence level 1.6Gbit/s that 16 sign indicating number is encoded required to signal with code length (code length be defined in back narration), also need about 8 times frequency for up-converting to the RF signal, so need the above carrier wave of 12.8GHz.Therefore, needing at least, the speed more than 1Gbit/s makes A/D converter and takes advantage of the digital multiplier of yard computing to carry out work to the signal of telecommunication of transmission.Under the present situation, being difficult to obtain can be with the A/D converter and the digital multiplier of such high speed operation.
In addition; In the optical access network system that passes through the PON realization in the past; In order to prevent to sneak into the reflecting background that in optical connector that the light deciliter element that is used for being provided with light transmission path is connected etc., takes place, upward signal and downstream signal utilize the light of different wave length.Therefore, entrant terminal of every increase just needs two kinds of different light of wavelength, and the different light number of wavelength that needs becomes very many.
Summary of the invention
Therefore, the objective of the invention is to, the first, provide a kind of can the transceiving high speed signal pass through the optical access network system that PON realizes.In addition, the second, even provide a kind of increase entrant number also needn't as photosystem of the same race in the past, increase the optical access network system that passes through the PON realization of the number of wavelengths of utilizing.
The present invention relates between the optical terminal device of the device that optical line terminal device and conduct as the device that is arranged at service provider's side are arranged at user side, utilize the optical access network system of the bidirectional optical of code division multiplexing.The optical line terminal device is coupled through optical fiber transmission path, light clutch and a plurality of optical fiber transmission path that separates with a plurality of optical terminal devices.In the optical fiber transmission path, the light clutch is set, is coupled with the optical line terminal device at the other end of this optical fiber transmission path at the one of which end.In addition, this optical fiber transmission path is separated into a plurality of separation optical fiber transmission paths through the light clutch, and an optical terminal device is coupled respectively on this separation optical fiber transmission path.
These a plurality of optical terminal devices are distributed different mutually sign indicating numbers respectively, between optical line terminal device and a plurality of optical terminal device, utilized the bidirectional optical of code division multiplexing.Optical line terminal device and a plurality of optical terminal device have respectively: send signal processing part, it will send signal encoding and generate coding transmission signal and output; And the reception signal processing part, it receives the code division multiplex signal that is transmitted by code division multiplexing, this code division multiplex signal decoding back is taken out receive signal.
In order to achieve the above object, the reception signal processing part of optical access network system of the present invention has the decoding processing circuit with the code division multiplex signal decoding, and this decoding processing circuit has analog matched filter and decision circuit.And, this analog matched filter have analogue shift register, positive signal with adder, negative signal with adder, will be respectively from this positive signal with adder and this negative signal analog adder, low pass filter with the output signal plus of adder.
In addition, send signal processing part and have: sign indicating number is given circuit, and it is encoded to sending signal; And delay circuit; It is connected to the back level that this yard given circuit; Coding being sent the phase place of signal adjusts; It is decoded and auto-correlation waveform that generate is decoded with the reflecting background component that in optical connector, takes place and cross-correlation waveform that generate staggers on time shaft make to send signal, and output is sent signal through the adjusted said coding of phase place.
According to optical access network system of the present invention; Have analog matched filter and decision circuit owing to receive the decoding processing circuit that signal processing part had; This analog matched filter constitute have analogue shift register, positive signal with adder, negative signal with adder, analog adder, low pass filter, signal that therefore can transceiving high speed.That is, code signal is sent with the multiplexing back of the state of baseband signal, in receiving signal processing part, do not use the analog matched filter of A/D converter to carry out decoding through utilizing, thus signal that can transceiving high speed.
In addition; Send signal processing part and coding is sent the delay circuit that the phase place of signal is adjusted, can prevent to send the problem of sneaking into that signal occurs in the reflecting background that takes place in the light deciliter optical connector that the ripple element is connected that is used for being provided with light transmission path etc. through having.Therefore, needn't utilize the light of different wave length, and needn't increase the quantity of the different light of the wavelength that needs upward signal and downstream signal.
In receiving the analog matched filter that signal processing part had, code division multiplex signal is decoded.The crest of the auto-correlation waveform that its result is obtained and the crest of cross-correlation waveform compare, and the crest of cross-correlation waveform is little.Therefore; Through staggering, thereby can become the state that makes decision circuit judge the crest of auto-correlation waveform easily at the decoded cross-correlation waveform that generates of reflecting background component that will send the decoded auto-correlation waveform that generates of signal on the time shaft and in optical connector etc., take place.The state that should judge easily is meant from the decoded output signal of analog matched filter output with respect to the S/N of the crest of auto-correlation waveform than big state.
On time shaft, above-mentioned auto-correlation waveform and cross-correlation waveform are staggered, through sending the phase place of signal by the adjustment of the transmission delay circuit that signal processing part had and can easily realizing.
Description of drawings
Fig. 1 is the summary frame assumption diagram of the optical access network system of first embodiment.
Fig. 2 is used to explain the figure that sends the process that signal is encoded.
Fig. 3 is used to explain the figure that receives the decoded process of signal.
Fig. 4 is used to explain the figure that sneaks into the situation that receives signal processing part from the reverberation of optical connector.
Fig. 5 is the figure of the relation of the expression crest location that will receive the auto-correlation waveform under the situation of signal and the signal decoding of having sneaked into the transmission signal that reflects.
Fig. 6 is the summary frame assumption diagram of analog matched filter.
Fig. 7 is used to explain the summary frame assumption diagram of decision circuit and the figure of operating principle thereof.
Fig. 8 is the summary frame assumption diagram of the optical access network system of second embodiment.
Embodiment
Below, with reference to description of drawings execution mode of the present invention.In addition, each figure expression structure example of the present invention, the configuration relation etc. of only roughly having represented each composed component is to be able to understand degree of the present invention, and the present invention is not limited to illustrative example.In addition, in following explanation, use specific material and condition etc. sometimes, but these materials and condition only are one of preferred example, thereby, not limited by this.In addition, in each figure, give the same label and represent, also omit the explanation of its repetition sometimes for same structure.In addition, in the summary frame assumption diagram shown in following, represent the path of light signals such as optical fiber with thick line, represent the path of the signal of telecommunication with fine rule.
< first embodiment >
The structure and the action thereof of the optical access network system of first embodiment are described with reference to Fig. 1.Fig. 1 is the summary frame assumption diagram of the optical access network system of expression first embodiment.Optical access network system shown in Figure 1 has supposed that entrant's number (number of users) is 4 situation, and promptly optical terminal device is 4 a situation, although be 4, but no matter is how many platforms, and following explanation is all set up.In Fig. 1, in order to discern a plurality of optical terminal devices, the optical terminal device that has been assigned with first channel is expressed as ONU-1, the optical terminal device that has been assigned with the 4th channel is expressed as ONU-4.From ONU-1 to ONU-4 any one all is same structure.In the explanation of the optical access network system of first embodiment afterwards, under the situation of the structure that optical terminal device is described, generally be expressed as optical terminal device 10 and describe.
The optical access network system of first embodiment is as the optical line terminal device 100 of the device that is arranged at service provider's side with as being arranged between the optical terminal device (from ONU-1 to ONU-4, being expressed as optical terminal device 10 later on) of the device of user side the optical access network system that carries out bidirectional optical through code division multiplexing.Optical line terminal device 100 is coupled through optical fiber transmission path 70, light clutch 66 and a plurality of optical fiber transmission path that separates with optical terminal device 10.
Optical fiber transmission path 70 is provided with light clutch 66 at the one of which end, is coupled with optical line terminal device 100 at the other end of this optical fiber transmission path 70.In addition, this optical fiber transmission path 70 is separated into a plurality of separation optical fiber transmission paths by light clutch 66, is coupled with an optical terminal device on this separation optical fiber transmission path respectively.In Fig. 1, the optical fiber transmission path that connects ONU-1 is expressed as separation optical fiber transmission path 74, the optical fiber transmission path that connects ONU-4 is expressed as separates optical fiber transmission path 76.
(ONU-1 to ONU-4) is assigned with different sign indicating number mutually respectively on these a plurality of optical terminal devices, between optical line terminal device 100 and these optical terminal devices, carries out two-way communication through code division multiplexing.
Receive signal processing part 22 and have the decoding processing circuit 30 that is used for the code division multiplex signal process of decoding, and have automatic gain control (AGC:Auto Gain Control) element 28, time signal reproducing circuit 34, frequency divider 38, second delay circuit (in Fig. 1, being expressed as delay circuit 2) 40.In addition, send signal processing part 24 and have encoding process circuit 82 and driver 60.Driver 60 has used amplifier (AMP:Amplifier).
Optical access network system of the present invention is characterised in that decoding processing circuit 30 has analog matched filter 44 and decision circuit 46, particularly is characterised in that the structure of analog matched filter 44.The back is described in detail, can be so that be used for code division multiplex signal with analog matched filter 44 and decision circuit 46 process of decoding transceiving high speedizations.
On the other hand, optical line terminal device 100 is also same with optical terminal device 10, constitutes to have optical processing portion 102 and electric processing section 104.Optical processing portion 102 is same with the optical processing portion 12 of optical terminal device 10, has light-emitting component 122 and photo detector 126.In addition, electric processing section 104 has the signal processing part 106 of transmission, receives signal processing part 108 and clock signal generating circuit 110.
Send signal processing part 106 and have encoding process circuit row 116 and driver 120, these encoding process circuit row 116 have the encoding process circuit that has been assigned with the sign indicating number identical with the sign indicating number that the transmission signal processing section from ONU-1 to ONU-4 is not distributed parallelly connectedly.Encoding process circuit with transmission signal processing part same structure from ONU-1 to ONU-4 is expressed as sign indicating number 1 to sign indicating number 4 in Fig. 1 respectively.Close enter drive 120 behind the ripple from being expressed as signal that sign indicating number 1 exports respectively to the encoding process circuit of sign indicating number 4 by signal of telecommunication wave multiplexer 118.
In addition; Receive signal processing part 108 and have decoding processing circuit row 132 and automatic gain control element 128, these decoding processing circuit row 132 have the decoding processing circuit that has been assigned with the sign indicating number identical with the sign indicating number that the reception signal processing part from ONU-1 to ONU-4 is distributed respectively parallelly connectedly.The decoding processing circuit that has been assigned with the sign indicating number identical with the sign indicating number that ONU-1 is distributed respectively to the reception signal processing part of ONU-4 is expressed as decoding 1 to decoding 4 in Fig. 1.Separate the back from the signal of automatic gain control element 128 output by signal of telecommunication separator 130 and be expressed as the decoding processing circuit of decoding 1 to decoding 4 by input respectively.
From clock signal generating circuit 110 pairs of transmissions signal processing part 106 and reception signal processing part 108 clock signal is provided.The clock signal that provides from clock signal generating circuit 110 is the clock signal that becomes the benchmark of this optical access network system.In optical terminal device 10, from the code division multiplex signal that receives, extract this clock signal through time signal reproducing circuit 34, and be used for the decoding of code division multiplex signal.
The optical access network system of said structure shown in Figure 1 moves as following explanation.
At first, be example explanation downstream signal with first channel.(what in Fig. 1, be expressed as optical line terminal device 100 ' sends signal input ch1 ' to the transmission signal of first channel.) be transfused to being expressed as of the encoding process circuit row 116 that have in the electric processing section 104 of optical line terminal device 100 ' the encoding process circuit of sign indicating number 1 ', and signal of telecommunication output is sent as coding in the back that is encoded.Coding sends the signal of telecommunication and is closed by signal of telecommunication wave multiplexer 118 and be transfused to driver 120 as the code division multiplexing signal of telecommunication behind the ripple and be exaggerated, and the light-emitting component 122 that the code division multiplexing signal of telecommunication after the amplification is had by optical processing portion 102 converts light signal into and exports as the code division multiplexing light signal.Light-emitting component 122 for example can utilize semiconductor laser.
The code division multiplexing light signal is via optical coupler 124, optical connector 72, and is transfused to the optical processing portion 12 of optical terminal device 10 via optical fiber transmission path 70, optical connector 68, light clutch 66, optical connector 61.Be transfused to the optical coupler 16 that the code division multiplexing optical signals optical processing portion 12 of optical processing portion 12 had and be transfused to photo detector 18, and after being converted into the code division multiplexing signal of telecommunication, be transfused to the electric processing section 14 of optical terminal device 10.Photo detector 18 for example can utilize photodiode.
The code division multiplexing signal of telecommunication that is transfused to electric processing section 14 is separated into two by signal of telecommunication separator 26, and one is transfused to time signal reproducing circuit 34, and another is transfused to automatic gain control element 28.From the code division multiplexing signal of telecommunication that is transfused to time signal reproducing circuit 34, extract clock signal.In addition, the code division multiplexing signal of telecommunication and its intensity that is transfused to automatic gain control element 28 irrelevant and be adjusted to have with this automatic gain control element 28 in the code division multiplexing signal of telecommunication of certain magnitude of voltage of setting, and be transfused to decoding processing circuit 30.This certain magnitude of voltage is that the composed component of the analog matched filter 44 that had with decoding processing circuit 30 is the value that the incoming level of analogue shift register equates.
Be transfused to decision circuit 46 after analog matched filter 44 decodings that the code division multiplexing signal of telecommunication of having been adjusted magnitude of voltage is at first had by decoding processing circuit 30.In decision circuit 46, in signal, only extract auto-correlation waveform component and output by analog matched filter 44 decodings.That is the reception signal that, generates from this auto-correlation waveform component is the signal component that the ONU-1 of first channel receives.
As stated, downstream signal is promptly from optical line terminal device 100 multiplexing code division multiplexing optical signal transmission after the transmission signal conduct of optical terminal device 10 transmission is encoded.Then, in optical terminal device 10, the code division multiplexing light signal is converted into behind the code division multiplexing signal of telecommunication decoded.That is, the decoding processing in the optical terminal device 10 all is performed under the state of the signal of telecommunication.
Optical access network system of the present invention is characterised in that coding that sends signal and the electric processing section that receives the decoding of signal, and later explanation is the center with the action specification in the electric processing section mostly.The required signal of the action specification of this electric processing section is that coding sends the signal of telecommunication or the code division multiplexing signal of telecommunication.Thereby, in the explanation afterwards, except necessary especially situation, do not distinguish the light signal or the signal of telecommunication.That is, not showing the code division multiplexing light signal or the code division multiplexing signal of telecommunication clearly is the signal of telecommunication or light signal and be expressed as code division multiplex signal.
Then, be example explanation upward signal with first channel.The transmission signal of first channel (is expressed as optical terminal device 10 ' sending the signal input ' in Fig. 1.) be transfused in the encoding process circuit 82 that the transmission signal processing part 24 of the electric processing section 14 of optical terminal device 10 had, and signal output is sent as coding in the back that is encoded.Coding sends signal and (is expressed as delay circuit 1 among Fig. 1 via first delay circuit.) 58 be transfused to driver 60 and amplify, the coding after the amplification sends signal and is converted into light signal through the light-emitting component 20 that optical processing portion 12 is had.Light-emitting component 20 can utilize semiconductor laser.
Coding sends signal and is transfused to light clutch 66 and becomes code division multiplex signal via optical coupler 16 and optical connector 61, is transfused to the optical processing portion 102 of optical line terminal device 100 via optical connector 68, optical fiber transmission path 70, optical connector 72.Be transfused to after optical coupler 124 that the code division multiplex signal of optical processing portion 102 had via optical processing portion 102 is transfused to photo detector 126 and is converted into the signal of telecommunication, be transfused to the electric processing section 104 of optical line terminal device 100.Photo detector 126 can utilize photodiode.
The code division multiplex signal that is transfused to electric processing section 104 is transfused to the automatic gain control element 128 that reception signal processing part 108 is had; With its intensity irrelevant and be adjusted to have with this automatic gain control element 128 in the coding of certain magnitude of voltage of setting receive the signal of telecommunication, and be transfused to ' the decoding processing circuit of decoding 1 ' that is represented as of decoding processing circuit row 132.In this decoding processing circuit, the processing that the decoding processing circuit that carries out being had with optical terminal device 10 30 is same generates the signal and the output that come from the ONU-1 transmission of first channel.
< encoding process >
Is that the example explanation is to sending the process that signal is encoded with reference to Fig. 2 (A1) to (C) with first channel.In (C), omitted the transverse axis and the longitudinal axis at Fig. 2 (A1), but the direction of the direction indication time shaft of transverse axis, the intensity of the direction indication signal of the longitudinal axis.Fig. 2 (A1) and (A2) represent that respectively the transmission signal of first channel and coding send signal, Fig. 2 (B1) and (B2) represent that respectively the transmission signal of second channel and coding send signal.And the coding transmission signal that the coding of Fig. 2 (C) expression first channel sends signal and second channel is closed the time waveform of the code division multiplex signal behind the ripple.At Fig. 2 (A1) in (C), with 0 level of chain-dotted line expression signal.And, with being expressed as ' 1 ' more than 0 level, 0 level following table is shown ' 1 '.
The transmission signal hypothesis of first channel shown in Fig. 2 (A1) be (1,0,1 ...) situation and show its time waveform.Fig. 2 (A2) supposes that by code length be the sign indicating number that 4 (1,0,0,1) obtains, and shows through this yard time waveform that the coding of first channel that generates sends signal of encoding.In addition, the transmission signal hypothesis of the second channel shown in Fig. 2 (B1) be (1,1,0 ...) situation and show its time waveform.Fig. 2 (B2) supposes that by code length be the sign indicating number that 4 (1,0,1,0) obtains, and shows through this yard time waveform that the coding of the second channel that generates sends signal of encoding.
Here, the item number by ' 0 ' and ' 1 ' ordered series of numbers that constitute of regulation sign indicating number is also referred to as code length sometimes.In this example, the ordered series of numbers of regulation sign indicating number is (1,0,0,1) or (1,0,1,0), because the item number of this data rows is 4, so code length is 4.In addition, the ordered series of numbers of giving sign indicating number is called sign indicating number string, also each item ' 0 ' and ' 1 ' of sign indicating number string is called chip (chip) sometimes.And 0 and 1 itself is also referred to as code value sometimes.Time width to 1 Bit Allocation in Discrete of sending signal (is also referred to as time slot.) be that the transmission speed of sending signal is the inverse of bit rate.The inverse of the time width that 1 chip of sign indicating number is distributed is also referred to as chip-rate (chip rate) sometimes.
When encoding, constitute 4 chips of sign indicating number to the time slot allocation of distributing to 1 bit that sends signal.That is, on time shaft, be configured, so that on time shaft, ordered series of numbers (1,0,0,1) or (1,0,1,0) pairing code signal of regulation sign indicating number are controlled in 1 bit that sends signal fully.
The meaning that to send signal encoding with the sign indicating number of code length 4 is equivalent to ask the transmission signal (also to be expressed as ' D ' later on sometimes.) and code signal (also be expressed as ' C ' later on sometimes.) long-pending D * C.In addition, in following explanation, when needs differences was D corresponding with which channel or C, the interpolation number of channel was represented.For example, be that the D of first channel and the situation of C are represented D respectively
1And C
1For second channel etc. too.
Specifically, giving circuit to the sign indicating number that is used for quadrature D * C, to use the gate circuit that in the output of nonequivalence operation EXOR (exclusive or) door, has connected inverter be XNOR EXNOR (exclusive nor) circuit.In this case, with the transmission signal that is expressed as 1 and 0 binary signal and coding send signal etc. convert into 1 with-1 binary signal.Specifically, adjustment is sent signal and coding and is sent the bias voltage of signal and the center of the amplitude of these signals changed to about 0V get final product.
The transmission signal of first channel shown in Fig. 2 (A1) be (1,0,1 ...), so be converted into 1 with-1 binary signal after become (1 ,-1,1 ...).The sign indicating number that the transmission signal encoding of first channel is utilized is (1,0,0,1), thus be converted into 1 with-1 binary signal after become (1 ,-1 ,-1,1).
First of the transmission signal of first channel is ' 1 ', second, and to be the ' 0 ', three be ' 1 '.Here, the transmission signal of first channel is by (1 ,-1 ,-1; 1) sign indicating number that obtains encode be meant first promptly ' 1 ' sign indicating number that obtain by (1 ,-1 ,-1,1) encode; Second promptly ' 1 ' sign indicating number that obtain by (1 ,-1 ,-1,1) encode; The 3rd promptly ' 1 ' sign indicating number that obtain by (1 ,-1 ,-1,1) encode.Though not shown, the 4th a later situation about being encoded too.
Encode and be equivalent to quadrature D * C sending signal D with sign indicating number C, the conduct primary ' 1 ' of therefore sending signal is encoded as (D first (1)) * C (1 ,-1 ,-1,1)=(1 * 1,1 * (1), 1 * (1), 1 * 1)=(1 ,-1 ,-1,1).The conduct deputy ' 1 ' of sending signal is encoded as (D second (1)) * C (1 ,-1 ,-1,1)=((1) * 1, (1) * (1), (1) * (1), (1) * 1)=(1,1,1 ,-1).For the 3rd too.Thereby, as above to state so brightly, the transmission signal of first channel shown in Fig. 2 (A1) is encoded and the coding that obtains sends signal and becomes ((1 ,-1 ,-1,1), (1,1,1;-1), (1 ,-1 ,-1,1))=(1 ,-1 ,-1,1 ,-1; 1,1 ,-1,1 ,-1 ,-1,1 ...) (Fig. 2 (A2)).
In addition, also same at the transmission signal of the second channel shown in Fig. 2 (B1) with the situation of above-mentioned first channel by sign indicating number (1,0,1,0) being converted under 1 situation that obtains (1 ,-1,1 ,-1) encoding with-1 binary signal.The conduct primary ' 1 ' of sending signal is encoded as (D first (1)) * C (1 ,-1,1 ,-1)=(1 * 1,1 * (1), 1 * 1,1 * (1))=(1 ,-1,1 ,-1).Second that sends signal also is ' 1 ', so second of D also is encoded as (1 ,-1,1 ,-1).
Because the 3rd is ' 1 ', therefore be encoded as (D the 3rd (1)) * C (1 ,-1,1 ,-1)=((1) * 1, (1) * (1), (1) * 1, (1) * (1))=(1,1 ,-1,1).Thereby, as above state bright that kind, the transmission signal of the second channel shown in Fig. 2 (B1) is encoded and the coding that obtains sends signal and is ((1 ,-1,1 ,-1), (1 ,-1,1;-1), (1,1 ,-1,1))=(1 ,-1,1 ,-1,1;-1,1 ,-1 ,-1,1 ,-1,1 ...) (Fig. 2 (B2)).
Coding by first channel sends signal (1 ,-1 ,-1,1 ,-1,1,1 ,-1,1 ,-1 ,-1,1;) and the coding of second channel send signal (1 ,-1,1 ,-1,1 ,-1,1 ,-1 ,-1,1 ,-1,1;) code division multiplex signal that obtains of sum become (1+1 ,-1-1 ,-1+1,1-1 ,-1+1,1-1,1+1 ,-1-1,1-1 ,-1+1 ,-1-1,1+1)=(+2;-2,0,0,0,0,2 ,-2,0,0 ,-2,2), Fig. 2 (C) representes the time waveform of this code division multiplex signal.
After being converted into light signal, code division multiplex signal shown in Fig. 2 (C) in optical fiber transmission path, transmits.After receiving by optical line terminal device or optical terminal device, be converted into the signal of telecommunication and decoding once more after, extract and receive signal.Thereby the absolute value of the amplitude of the time waveform of the code division multiplex signal shown in Fig. 2 (C) does not have the meaning of essence.Thereby, Fig. 2 (C) though shown in code division multiplex signal the maximum of amplitude and the center of minimum value are made as 0 level, show as (+1 ,-1,0,0,0,0,1 ,-1,0,0 ,-1,1) after the value of amplitude is normalized to 1, also have the same meaning.
< decoding processing >
Is the process that the example explanation is decoded to code division multiplex signal with reference to Fig. 3 (A) to (D) with first channel.At Fig. 3 (A) and (B), the direction of transverse axis express time axle.The longitudinal axis omits, but the intensity of the direction indication time of the longitudinal axis.Fig. 3 (A) expression is transfused to the time waveform of the code division multiplex signal of the analog matched filter that the decoding processing circuit had.The maximum of the amplitude of the code division multiplex signal shown in above-mentioned Fig. 2 (C) and the center of minimum value are set at 0 level, with the value normalization of amplitude and be expressed as 1.Fig. 3 (B) expression is by the time waveform of the signal of analog matched filter decoding and output.Of the back, be that the reception signal component of the optical terminal device of the channel that receives is the cross-correlation waveform component sum that is received beyond the optical terminal device of auto-correlation waveform component and the channel that receives from the signal of analog matched filter output.That is, the cross-correlation waveform component is a noise component(s).
The time waveform of the signal that Fig. 3 (C1) expression is undertaken by decision circuit exporting behind the threshold determination.Fig. 3 (C2) expression is used for the time waveform with the clock signal of the semaphore lock (latch) shown in Fig. 3 (C1).In addition, Fig. 3 (D) expression by the clock signal shown in Fig. 3 (C2) with the carrying out shown in Fig. 3 (C1) semaphore lock exported behind the threshold determination and the time waveform of the signal that obtains.Signal shown in this Fig. 3 (D) is for receiving signal.Fig. 3 (C1), (C2) and transverse axis (D) and the longitudinal axis are omitted, but the direction of the direction indication time shaft of transverse axis, the intensity of the direction indication signal of the longitudinal axis.In addition, with 0 level of chain-dotted line expression signal.
The decision circuit that signal from analog matched filter output is carried out determination processing is equivalent to the decision circuit 46 that decoding processing circuit 30 shown in Figure 1 is had.In addition, in Fig. 1, also comprise be used for by the clock signal shown in Fig. 3 (C2) with the carrying out shown in Fig. 3 (C1) lock-in circuit of the semaphore lock exported after the determination processing, be expressed as decision circuit 46, itself has omitted diagram lock-in circuit.
The meaning of as stated, the transmission signal being encoded is equivalent to ask the long-pending D * C that sends signal D and code signal C.On the other hand, receive the code division multiplex signal that sends after being encoded and this code division multiplex signal decoded corresponding to same yard code division multiplex signal being encoded once more.
Code division multiplex signal is that the coding of first channel sends signal (D
1* C
1), the coding of second channel sends signal (D
2* C
2), the coding of the 3rd channel sends signal (D
3* C
3) wait the whole codings that are re-used to send the signal sum.Thereby code division multiplex signal is expressed as (D
1* C
1)+(D
2* C
2)+(D
3* C
3)+...Use sign indicating number C to first channel allocation
1This code division multiplex signal decoding is equivalent to ask { (D
1* C
1)+(D
2* C
2)+(D
3* C
3)+... C
1(with same sign indicating number code division multiplex signal being encoded once more).
That is, the time waveform by the signal of output after the analog matched filter decoding is to have reflected { (D
1* C
1)+(D
2* C
2)+(D
3* C
3)+... C
1=(D
1* C
1) C
1+ (D
2* C
2) C
1+ (D
3* C
3) C
1+ ...=D
1* C
1 2+ (D
2* C
2* C
1)+(D
3* C
3* C
1)+... Signal.Here, C
1 2=1.This is that the chip that therefore constitutes both sign indicating numbers all is same value because be the long-pending of same sign indicating number, promptly ' 1 ' or ' 1 '.Just because with regard to C
1 2Computing to each chip of sign indicating number, one is decided to be ' 1 ' as 1 * 1=1 or (1) * (1)=1.Thereby, represent first D of the time waveform of above-mentioned signal by analog matched filter decoding and output
1* C
1 2Become D
1, constitute everybody pulsed D of the transmission signal of first channel
1Be reproduced.That is, this component is equivalent to by the signal of analog matched filter decoding and the output auto-correlation waveform component with respect to the transmission signal of first channel.
On the other hand, since second of the time waveform of the above-mentioned signal by analog matched filter decoding and output of expression later be C
1* C
i≠ 1 (here, i=2,3 ...), so from (D
2* C
2) C
1And (D
3* C
3) C
1Item play everybody pulsed D of the transmission signal that constitutes second, third channel of can not regenerating
2And D
3That is, these components are equivalent to by the signal of analog matched filter decoding and the output cross-correlation waveform component with respect to the transmission signal of first channel.
As discussed above, through analog matched filter, can code division multiplex signal be decoded and regeneration auto-correlation waveform component.In Fig. 3 (B), the pulse component shown on the time shaft (is represented by P and Q among Fig. 3 (B).) be the auto-correlation waveform component.In addition, the cross-correlation waveform component is the noise component(s) that is controlled at across between the dotted line that time shaft is represented up and down.In Fig. 3 (B), because the shape of cross-correlation waveform component is very complicated, so use the dotted line of representing up and down across time shaft to represent the level of its maximum and minimum value, its detail shape is omitted.
After being handled the time waveform by the signal of output after the analog matched filter decoding shown in Fig. 3 (B) by decision circuit, Fig. 3 (C1) expression only extracts and exports the signal of auto-correlation waveform component.Signal shown in Fig. 3 (C1) obtains the reception signal shown in Fig. 3 (D) by the locking of the clock signal shown in Fig. 3 (C2).
Then, with reference to Fig. 3 (C1), (C2) and (D) content of the locking processing in the explanation decision circuit.Can utilize known D circuits for triggering etc. owing to be used to carry out the lock-in circuit of locking processing, so lock-in circuit omission explanation itself.In this embodiment, as the D circuits for triggering, utilized MC100LVEL31 (ON semiconductor manufactured).
Of the back, the signal by analog matched filter decoding back output shown in Fig. 3 (B) is handled and generated the time waveform shown in Fig. 3 (C1) by the threshold process circuit.That is, the threshold process circuit plays the effect of the analog codec conversion of signals shown in Fig. 3 (B) for the digital decoding signal shown in Fig. 3 (C1).Thereby the time waveform shown in Fig. 3 (C1) is characterised in that corresponding to the auto-correlation waveform component of the signal of the decoded back output shown in Fig. 3 (B) and presents square wave (rectangular pulse).The size of the amplitude of this rectangular pulse is by threshold process circuit regulation, and the size of the amplitude of all rectangular pulses that appear among Fig. 3 (C1) is certain.Represent an example of this rectangular pulse with two downward arrow clampings of having given a, b respectively among Fig. 3 (C1).The threshold process circuit can suitably select suitable comparator to utilize from known comparator.In the present embodiment, utilized MAX9600 (MAXIM Integrated Products manufactured).
When the clock signal shown in the digital decoding signal shown in Fig. 3 (C1) and Fig. 3 (C2) is transfused to the D circuits for triggering that play the lock-in circuit function, carry out following processing, obtain the reception signal shown in Fig. 3 (D).
In the moment (for example being expressed as the moment of X among Fig. 3 (C2)) of the rising edge of the signal shown in Fig. 3 (C2); Exist the rectangular pulse corresponding (for example, to represent by two downward arrow clampings of having given a, b respectively among Fig. 3 (C1) with the crest of the auto-correlation waveform of digital decoding signal.) situation under, begin from the signal of the lead-out terminal of D circuits for triggering output with ' 1 ' suitable intensity.Then; Till moment of the next rising edge of clock signal (being expressed as the moment of Y among Fig. 3 (C2)) once more; Continue the signal of output and ' 1 ' suitable intensity from the lead-out terminal of D circuits for triggering; In this moment, be changed to the signal of the signal that is equivalent to ' 1 ' intensity from the output of the lead-out terminal of D circuits for triggering.
Equally, then beginning from the signal of the output of the lead-out terminal of D circuits for triggering and ' 1 ' suitable intensity is the moment that among Fig. 3 (C2), is expressed as the rising edge clock signal of Z.And being changed to the signal that is equivalent to ' 1 ' intensity from the output signal of the lead-out terminal of D circuits for triggering is that (this moment has broken away from Fig. 3 (C2) in the moment that clock signal rises once more.)。
As discussed above; In the life period of the rectangular pulse corresponding with the crest of the auto-correlation waveform of digital decoding signal; During to the rising edge signal of D circuits for triggering input clock signal, generate the rectangular pulse that is equivalent to ' 1 ' intensity of the reception signal shown in Fig. 3 (D).On the other hand; Outside the life period of the rectangular pulse corresponding with the crest of the auto-correlation waveform of digital decoding signal; The D circuits for triggering have been imported under the situation of rising edge of clock signal signal, still kept from the state of the lead-out terminal of D circuits for triggering output with ' 1 ' suitable signal.
Like this, whether there is the corresponding rectangular pulse of crest with the auto-correlation waveform of digital decoding signal corresponding to moment, from the lead-out terminal output of D circuits for triggering and ' 1 ' suitable signal or output and ' 1 ' suitable signal in rising edge of clock signal.Thus, receiving signal is reproduced.Reception signal shown in Fig. 3 (D) be as the transmission signal shown in Fig. 2 (A1) (1 ,-1,1 ...) a part (1 ,-1,1 ...) result that is reproduced of part.In Fig. 3 (D), for show clearly with (1 ,-1,1 ...) suitable part, with bracket ' 1 ' and ' 1 ' of signal value is bracketed expression.
Can know from above-mentioned explanation,, then can not generate the reception signal shown in Fig. 3 (D) if do not have the corresponding square wave of crest with the auto-correlation waveform of digital decoding signal in rising edge of clock signal moment.Thereby, must need digital decoding signal shown in adjustment Fig. 3 (C1) and the relative position relation of clock signal on time shaft shown in Fig. 3 (C2).The adjustment of both relative position relations is described with reference to Fig. 1.
After being separated by signal of telecommunication separator 26 from the code division multiplex signal of photo detector 18 output, a separated part is transfused to time signal reproducing circuit 34, and the clock signal of transmission rate frequency is reproduced and exports.The clock signal of this transmission rate frequency is separated by signal of telecommunication separator 36, and after a separated part was transfused to frequency divider 38, the clock signal and the quilt that are converted into the basic rate frequency were exported.Here, the transmission rate frequency is meant the pairing frequency of the bit rate of code division multiplex signal, and the basic rate frequency is meant the pairing frequency of bit rate of the transmission signal of each channel.That is, the frequency that obtains divided by the number of channel of transmission rate frequency is the basic rate frequency.
Be transfused to second delay circuit 40 from the clock signal of frequency divider 38 outputs, its phase place is adjusted the back and is exported.From the clock signal of second delay circuit 40 output shown in Fig. 3 (C2).That is, can adjust the position on the time shaft of the clock signal shown in Fig. 3 (C2) through second delay circuit 40.This adjustment can be carried out also can carrying out automatically through manual mode.A kind of means that are used to make this adjustment automation are disclosed in the day disclosure special permission communique (TOHKEMY 2005-33544 communique).
Here, the noise component(s) that comprises in the time waveform shown in the key diagram 3 (B) by the signal of output after the analog matched filter decoding.In the optical terminal device 10 of optical access network system shown in Figure 1, send signal from sending signal processing part 24 outputs, on the other hand, handling part 22 inputs to received signal receive signal.Here, to each channel allocation be used to encode the sign indicating number and be used to decode the sign indicating number.And these sign indicating numbers use same code.Therefore, being used for of taking place to be provided with in the light transmission path sneaked into the problem in the reception signal that is transfused to the reception signal processing part with the reflecting background of the light deciliter generations such as optical connector that the ripple element is connected.
Explain that with reference to Fig. 4 this reflecting background sneaks into the mechanism that receives signal.Fig. 4 is used to explain the figure that sneaks into the situation that receives signal processing part from the reverberation of optical connector.In Fig. 4, from Fig. 1, only take out the explanation reflecting background and sneak into the required part of mechanism that receives signal and represent.Send port 3 inputs of signal, after port one output, be transfused to optical connector 61 from light-emitting component 20 output backs from optical coupler 16.Send the port one of the part back input optical coupler 16 of signal from optical connector 61 reflections.The transmission signal of this reflection is transfused to photo detector 18 after port 2 outputs of optical coupler 16.
Thereby, to photo detector 18 input from the port one input of optical coupler 16 and from the reception signal a of port 2 outputs with from a part of b of the transmission signal of optical connector 61 reflections.A part of b of this transmission signal is reflected from 3 inputs of the port of optical coupler 16 and from the transmission signal of port one output from optical connector 61 and input port 1 and the part after port 2 outputs once more.
With reference to Fig. 5 (A) and (B) the explanation situation of having carried out decoding to received signal with the signal of the transmission signal of having sneaked into reflection.Fig. 5 (A) and (B) be to represent that to received signal signal with the transmission signal of having sneaked into reflection has carried out the figure of relation of the crest location of the auto-correlation waveform under the situation of decoding.Transverse axis express time axle, the longitudinal axis is omitted, but expression signal intensity on the direction of the longitudinal axis.
Carried out encoded signals with the reception signal with identical sign indicating number owing to send signal, so produce the consistent situation of crest location of both auto-correlation waveforms.At Fig. 5 (A) and (B), the represented crest of c representes to receive the auto-correlation waveform of signal, the auto-correlation waveform of the transmission signal that the crest that is expressed as r is represented to be reflected.The consistent situation of crest location of the auto-correlation waveform of the transmission signal of Fig. 5 (A) expression reception signal and reflection, the inconsistent situation of crest location of the auto-correlation waveform of the transmission signal of Fig. 5 (B) expression reception signal and reflection.
At Fig. 5 (A) and (B); The cross-correlation waveform component that receives signal is the noise component(s) that is controlled between the thick dashed line that time shaft is represented up and down, and the cross-correlation waveform component that sends signal is the noise component(s) that is controlled between the fine dotted line that time shaft is represented up and down.The cross-correlation waveform component is because its shape is very complicated, so use the dotted line of representing up and down across time shaft to represent the level of its maximum and minimum value, its detailed shape is omitted.
Under the consistent situation of the crest location of the auto-correlation waveform of the transmission signal of reception signal shown in Fig. 5 (A) and reflection; The crest of the auto-correlation waveform of reception signal is the signal component of essence with the difference of the crest of the auto-correlation waveform that sends signal, in Fig. 5 (A), is expressed as S
1The value that the N of the S/N ratio under this situation is provided is the peak intensity of sending the auto-correlation waveform of signal, in Fig. 5 (A), is expressed as N
1
On the other hand, under both the inconsistent situation of crest location of auto-correlation waveform shown in Fig. 5 (B), the crest of auto-correlation waveform is the signal component of essence with the difference of the crest of the cross-correlation waveform component that receives signal, in Fig. 5 (B), is expressed as S
2The value that the N of the S/N ratio under this situation is provided is the peak intensity that receives the cross-correlation waveform component of signal, in Fig. 5 (B), is expressed as N
2
Like Fig. 5 (A) and (B), because S
1＜S
2, N
1＞N
2, so the S/N under the inconsistent situation of crest location of two auto-correlation waveforms shown in Fig. 5 (B) compares S
2/ N
2S/N greater than under the consistent situation of the crest location of two auto-correlation waveforms shown in Fig. 5 (A) compares S
1/ N
1That is (S,
2/ N
2)＞(S
1/ N
1).Thereby the crest location of the auto-correlation waveform of the crest location through making the auto-correlation waveform that receives signal and the transmission signal of reflection staggers and receives, and can increase the S/N ratio, so we can say preferably like this two crest locations to be staggered and receive.
Realize adjusting the crest location of the auto-correlation waveform of the transmission signal that receives signal and reflection through the retardation of adjusting first delay circuit 58 shown in Figure 1.When being the example explanation with the situation of first channel, the coding of giving circuit 56 outputs from sign indicating number sends signal and is transfused to first delay circuit 58, and its phase place is adjusted.In first delay circuit 58; Because coding sends the delay of signals amount and is adjusted, so can adjust crest location and the position relation of crest location on time shaft of sending the auto-correlation waveform of signal from the coding of first delay circuit, 58 outputs of the auto-correlation waveform of the transmission signal that reflects from optical connector 61.The interval of the crest location of two auto-correlation waveforms changes corresponding to the retardation that in first delay circuit 58, obtains.That is, shown in Fig. 5 (B), can be made as the inconsistent state of crest location of two auto-correlation waveforms.The interval of the crest location of the auto-correlation waveform of the transmission signal of pairing reception signal of the retardation that in first delay circuit 58, obtains and reflection is represented by the line segment that is parallel to time shaft that has added arrow at two ends in Fig. 5 (B).
< analog matched filter >
One of characteristic of optical access network system of the present invention is by analog matched filter code division multiplex signal to be decoded.Therefore, with reference to Fig. 6 (A) and (B) structure and the action thereof of explanation analog matched filter.
Fig. 6 (A) and (B) be the summary frame assumption diagram of analog matched filter.Analog matched filter comprise analogue shift register 140, positive signal with adder 142, negative signal with adder 144, will be respectively from this positive signal with adder 142 and this negative signal analog adder 146, low pass filter 148 with the output signal plus of adder 144.Positive signal has amplifier 150 and sign-changing amplifier 152 with adder 142 and negative signal respectively with adder 144.Amplifier 150 and sign-changing amplifier 152 omit its peripheral circuit and represent.
Input is from the code division multiplex signal of automatic gain control element 28 outputs on the input terminal that is expressed as the data input.In addition, on the input terminal that is expressed as the clock input, import the clock signal of the transmission rate frequency of separating by signal of telecommunication separator 36.
The sign indicating number that analog matched filter supposition shown in Fig. 6 (A) is obtained by ordered series of numbers (1,0,0,1) is decoded and is designed.That is, suppose first embodiment by the sign indicating number situation of decoding of distributing to first channel.The sign indicating number that is obtained by ordered series of numbers (1,0,0,1) may also be referred to as the sign indicating number that is obtained by ordered series of numbers (1 ,-1 ,-1,1) when the two-value of carrying out ' 1 ' and ' 1 ' shows.
Here, for simply, the component that at first in code division multiplex signal, only takes out first channel describes.Also sneak into the transmission signal behind the coding of the channel beyond first channel in the code division multiplex signal, but since they encode by the sign indicating number different with the sign indicating number of distributing to first channel, so do not regenerate.
The coding of first channel shown in the key diagram 2 (A2) sends the situation that signal is reproduced by the analog matched filter conduct and the reception signal of the identical time waveform of transmission signal of first channel with the time waveform shown in Fig. 2 (A1).
Bit rate at each channel is 125Mbit/s; Is under the multiplexing situation in 16 orthogonal code coding back to 16 channels with code length; Perhaps the bit rate at each channel is 62.5Mbit/s, is that the chip-rate of coding is 2Gbit/s under the multiplexing situation in 32 orthogonal code coding back to 32 channels with code length.That is, the electric charge of each inter-stage of CCD shift register gets final product with the 2Gb/s displacement.In the opposite CCD shift register under present situation, the shifting speed of the electric charge of each inter-stage is guaranteed about 10Gbit/s, so according to the analog matched filter that uses the CCD shift register, can realize easily that chip-rate is the coding of 2Gbit/s.That is, in PON, realize that easily being used for the service provider utilizes the code division multiplexing mode to carry out the optical access network system of communicating by letter of 100Mbit/s level with the entrant.
Import the clock signal of transfer rate frequency at the clock input terminal of CCD shift register 140.In addition, the sub-input code division multiplex signal of the data input pin of CCD shift register 140 (coding shown in Fig. 2 (A2) sends signal).With Fig. 6 (A) and the input terminal of the first order of the CCD shift register 140 (B) be expressed as D
1, lead-out terminal is expressed as Q
1In addition, second, third and four-input terminal are expressed as D respectively
2, D
3, D
4, lead-out terminal is expressed as Q respectively
2, Q
3, Q
4Data input pin of CCD shift register 140 is connected to the input terminal D of the first order
1
With reference to Fig. 6 (A) the decoded principle of code division multiplex signal with first channel of sign indicating number (1 ,-1 ,-1,1) coding is described.
At first, to the sub-D of data input pin of the first order of CCD shift register
1The input code division multiplex signal, promptly here for the coding of first channel shown in Fig. 2 (A2) send signal ' 1 ' (time slot that is expressed as CS1 of Fig. 2 (A2) is 1.) time, with clock signal synchronously from the lead-out terminal Q of the first order
1Output ' 1 '.Then, to the sub-D of the data input pin of the first order
1The coding of importing first channel send signal ' 1 ' (time slot that is expressed as CS2 of Fig. 2 (A2) is-1.) time, with clock signal synchronously from the lead-out terminal Q of the first order
1Output ' 1 ' is from partial lead-out terminal Q
2Output ' 1 '.Like this, constantly to the sub-D of the data input pin of the first order
1During the signal of time slot that input is expressed as CS3 and the time slot that is expressed as CS4, the signal of output and clock signal synchronously respectively stagger 1 grade and export from the lead-out terminal of the first order to the fourth stage earlier.
Send the chip that exists in the time slot of just in time CS1 to CS4 of signal all by stage, from each lead-out terminal, the Q of the first order to the fourth stage at coding from the data input pin input of analogue shift register 140
1, Q
2, Q
3And Q
4The output valve (Q of lead-out terminal
1, Q
2, Q
3, Q
4) be (1 ,-1 ,-1,1).That is, each output valve of the first order to the fourth stage is (Q
1, Q
2, Q
3, Q
4) in analogue shift register 140, be rendered as magnitude of voltage in the position that is expressed as F, G, H, I.
The magnitude of voltage of the magnitude of voltage of position F and position I is transfused to positive signal with adder 142, closes input amplifier 150 behind the ripple by signal of telecommunication wave multiplexer 154, is exported after becoming the signal suitable with the magnitude of voltage sum of the magnitude of voltage of position F and position I.On the other hand, the magnitude of voltage of the magnitude of voltage of position G and position H is transfused to negative signal with adder 144, closes input sign-changing amplifier 152 behind the ripple by signal of telecommunication wave multiplexer 156, with the magnitude of voltage of position G and the suitable magnitude of voltage of magnitude of voltage sum of position H (be negative value.) be converted into behind the positive magnitude of voltage and exported.
Be transfused to low pass filter 148 after closing ripple from the output signal of amplifier 150 with from the output signal of sign-changing amplifier 152 by analog adder 146.
Low pass filter 148 plays the signal of leaching basic rate frequency from the signal of analog adder 146 outputs and the effect of interdicting the noise component(s) of high frequency.
Send the chip that exists in the time slot of just in time CS1 to CS4 of signal all by stage, from Q at coding from the data input pin input of analogue shift register 140
1, Q
2, Q
3And Q
4The output valve (Q of lead-out terminal
1, Q
2, Q
3, Q
4) be (1 ,-1 ,-1,1), so in signal of telecommunication wave multiplexer 154, the position current potential of F and I is that current potential 1 is transfused to current potential 1, becomes current potential 2 and be transfused to amplifier 150.In addition, to the current potential-1 and the current potential-1 of the current potential of the position of signal of telecommunication wave multiplexer 156 input G and H, be transfused to sign-changing amplifier 152 after becoming current potential-2.
Thereby the current potential that is directly proportional with current potential 2 from amplifier 150 output is (here, for simply being made as 1 with magnification ratio.) signal, be inverted (here, for simply magnification ratio being made as-1 from sign-changing amplifier 152 output potentials-2.) after the signal of current potential 2, both close the ripple afterpotential by analog adder 146 is that 4 signal is via the data output end output of low pass filter 148 from CCD shift register 140.
Output valve (the Q of CCD shift register 140
1, Q
2, Q
3, Q
4) to become (1 ,-1 ,-1,1) successively be that the chip that in the time slot of CS9 to CS12, exists is all by the stage from the data input pin input of analogue shift register 140.At this moment, equally be 4 signal from the sub-output potential of the data output end of CCD shift register 140.
Output valve (the Q of CCD shift register 140
1, Q
2, Q
3, Q
4) when becoming the output different, can be not the signal more than 4 from the sub-output potential of the data output end of CCD shift register 140 with (1 ,-1 ,-1,1), current potential is necessarily less than 4.If this is with the output valve (Q of CCD shift register 140
1, Q
2, Q
3, Q
4) situation and the above-mentioned explanation that become the for example states such as (1 ,-1,1,1) different with (1 ,-1 ,-1,1) just study equally and can understand.
Then, with reference to Fig. 6 (B) the decoded principle of code division multiplex signal with the second channel of sign indicating number (1 ,-1,1 ,-1) coding is described.Different being of analog matched filter shown in Fig. 6 (A) and the analog matched filter shown in Fig. 6 (B) taken out the signal of wanting input amplifier 150 and sign-changing amplifier 152 from certain position of F, G, H, I.In the analog matched filter shown in Fig. 6 (A), take out the input signal of pair amplifier 150 from the position of F and I, take out input signal from the position of G and H to sign-changing amplifier 152.On the contrary, in the analog matched filter shown in Fig. 6 (B), take out the input signal of pair amplifier 150 from the position of G and I, take out input signal sign-changing amplifier 152 from the position of F and H.Like this, can according to take out from certain position of F, G, H, I the signal of wanting input amplifier 150 and sign-changing amplifier 152 set code length be 4 arbitrarily yard.
Also sneaked into the transmission signal that is encoded of the channel beyond the second channel in the code division multiplex signal, encoded with the sign indicating number different but these are, so do not regenerate with the sign indicating number that second channel is distributed.
Coding transmission signal to the second channel shown in Fig. 2 (B2) is described by the situation of analog matched filter conduct with the reception signal regeneration of the same time waveform of transmission signal of the second channel with the described time waveform of Fig. 2 (B1).In the analog matched filter shown in Fig. 6 (B), the action of decoding is same with the analog matched filter shown in Fig. 6 (A) basically.
At first, to the sub-D of data input pin of the first order of CCD shift register
1The input code division multiplex signal, promptly here for the coding of the second channel shown in Fig. 2 (B2) send signal ' 1 ' (time slot that is expressed as CS1 of Fig. 2 (B2) is 1.) time, with clock signal synchronously from the lead-out terminal Q of the first order
1Output ' 1 '.Then, to the sub-D of the data input pin of the first order
1The coding of input second channel send signal ' 1 ' (time slot that is expressed as CS2 of Fig. 2 (B2) is-1.) time, with clock signal synchronously from the lead-out terminal Q of the first order
1Output ' 1 ' is from partial lead-out terminal Q
2Output ' 1 '.Like this, constantly to the sub-D of the data input pin of the first order
1During the signal of time slot that input is expressed as CS3 and the time slot that is expressed as CS4, the signal of output and clock signal are synchronously exported from the lead-out terminal of the first order to the fourth stage 1 grade of quilt that respectively staggers earlier.
Send the chip that exists in the time slot of just in time CS1 to CS4 of signal all by stage, from each lead-out terminal, the Q of the first order to the fourth stage at coding from the data input pin input of analogue shift register 140
1, Q
2, Q
3And Q
4The output valve (Q of lead-out terminal
1, Q
2, Q
3, Q
4) be (1,1 ,-1,1).That is, each output valve of the first order to the fourth stage is (Q
1, Q
2, Q
3, Q
4) in analogue shift register 140, be rendered as magnitude of voltage in the position that is expressed as F, G, H, I.
The magnitude of voltage of the magnitude of voltage of position G and position I is transfused to positive signal with adder 142, closes input amplifier 150 behind the ripple by signal of telecommunication wave multiplexer 154, is exported after becoming the signal suitable with the magnitude of voltage sum of the magnitude of voltage of position G and position I.On the other hand, the magnitude of voltage of the magnitude of voltage of position F and position H is transfused to negative signal with adder 144, closes input sign-changing amplifier 152 behind the ripple by signal of telecommunication wave multiplexer 156, with the magnitude of voltage of position F and the suitable magnitude of voltage of magnitude of voltage sum of position H (be negative value.) be converted into behind the positive magnitude of voltage and exported.
Be transfused to low pass filter 148 after closing ripple from the output signal of amplifier 150 with from the output signal of sign-changing amplifier 152 by analog adder 146.
Send the chip that exists in the time slot of just in time CS1 to CS4 of signal all by stage, from Q at coding from the data input pin input of analogue shift register 140
1, Q
2, Q
3And Q
4The i.e. (Q of output valve of lead-out terminal
1, Q
2, Q
3, Q
4) be (1,1 ,-1,1), so in signal of telecommunication wave multiplexer 154, the locational current potential of G and I is current potential 1 and current potential 1, becomes current potential 2 and be transfused to amplifier 150.In addition, be current potential-1 and current potential-1 to the locational current potential of signal of telecommunication wave multiplexer 156 input F and H, be transfused to sign-changing amplifier 152 after becoming current potential-2.
Thereby; Export the signal of the current potential that is directly proportional with current potential 2 from amplifier 150; Current potential after being inverted from sign-changing amplifier 152 output potentials-2 is 2 signal, and both are closed behind the ripple as current potential by analog adder 146 is that 4 signal is via the data output end output of low pass filter 148 from CCD shift register 140.
Output valve (the Q of CCD shift register 140
1, Q
2, Q
3, Q
4) to become (1,1 ,-1,1) successively be that the chip that in the time slot of CS5 to CS8, exists is all by the stage from the data input pin input of analogue shift register 140.At this moment, equally be 4 signal from the sub-output potential of the data output end of CCD shift register 140.
Output valve (the Q of CCD shift register 140
1, Q
2, Q
3, Q
4) when becoming the output different, can be not the signal more than 4 from the sub-output potential of the data output end of CCD shift register 140 with (1,1 ,-1,1), current potential is necessarily less than 4.
As discussed above, only at the output valve (Q of CCD shift register 140
1, Q
2, Q
3, Q
4) under the situation consistent, from the sub-output potential of the data output end of CCD shift register 140 4 signal with the sign indicating number of setting.This is the signal suitable with the auto-correlation waveform.For example, the coding of first channel is sent in the time waveform of the signal that obtains behind the signal decoding shown in Fig. 3 (B), the crest that is expressed as P and Q is to be the crest that appears moment of 4 signal from the sub-output potential of the data output end of CCD shift register 140.
< decision circuit >
The structure and the action of decision circuit are described with reference to Fig. 7 (A) to (C).Fig. 7 (A) is the summary frame assumption diagram of decision circuit, the time waveform of Fig. 7 (B) expression signal behind analog matched filter output decoded.In addition, the time waveform of Fig. 7 (C) expression signal that carried out exporting behind the threshold determination.
Time waveform shown in Fig. 7 (B) is equivalent to the time waveform by the signal of output after the analog matched filter decoding shown in Fig. 3 (B).Fig. 7 (B) is different in appearance with Fig. 3 (B), but each figure is convenience and the abstract representation of explanation, and the time waveform of the signal in the reality approaches Fig. 7 (B).
Decision circuit constitutes has comparator 42 and D circuits for triggering 52.From the analogue data input terminal of decision circuit the input terminal (IN) of comparator 42 is imported the decoded signal from analog matched filter output shown in Fig. 7 (B).Be set at the signal of the current potential of threshold value from a threshold level input terminal (REF) input.This current potential is equivalent to be expressed as among Fig. 7 (B) current potential of threshold value.
Level from the signal of input terminal (IN) input has surpassed under the situation of threshold value, is equivalent to the signal of 1 current potential from lead-out terminal (OUT) output of comparator 42.On the other hand, be lower than under the situation of threshold value at the level from the signal of input terminal (IN) input, output is equivalent to the signal of 0 current potential.Thereby, become the time waveform shown in Fig. 7 (C) from the time waveform of the signal of the lead-out terminal (OUT) of comparator 42 output.Time waveform shown in Fig. 7 (C) is corresponding to the time waveform shown in above-mentioned Fig. 3 (C1).
The signal of the time waveform shown in Fig. 7 (C) is transfused to the input terminal (D) of D circuits for triggering 52.On the other hand, at sub (CLK) input clock signal of the clock signal input terminal of D circuits for triggering 52.The clock signal that is transfused to clock signal input terminal (CLK) is the clock signal shown in Fig. 3 (C2).That is, will be imported into the semaphore lock exported behind the threshold determination of carrying out of input terminal (D) through this clock signal.Owing to the principle of lock out action has been described, so do not do repetition here.
In Fig. 3 (C1), the width of rectangular pulse is equally represented, but in fact the waveform shown in Fig. 7 (C) like this, the width of rectangular pulse is unequal.But, get final product owing in the width range of this rectangular pulse, comprise the moment of rising edge of clock signal, so the width of this rectangular pulse need not certain equating.But, need be by the position of second delay circuit adjustment clock signal on time shaft, be controlled in the scope of width (W1 and W2) of the rectangular pulse shown in Fig. 7 (C) so that be transfused to the moment of the rising edge of clock signal of clock signal input terminal (CLK).
< second embodiment >
The structure and the action thereof of the optical access network system of second embodiment are described with reference to Fig. 8.Fig. 8 is the summary frame assumption diagram of the optical access network system of second embodiment.In a second embodiment, supposed that entrant's number is 16 situation.Be with the optical access network system difference of first embodiment; In the optical access network system of first embodiment; The employed signal wavelength of communicating by letter is merely a kind of; And in the optical access network system of second embodiment, be so-called WDM (the Wavelength Division Multiplex) system that four kinds of wavelength are used as signal wavelength.
Thereby, relevant with signal wavelength lambda
1The structure of the part that communicates is identical with the optical access network system of first embodiment.The wavelength that signal wavelength utilizes uses λ
1To λ
4Four kinds, thereby for number of users expand to 4 times (ONU-1 to ONU-16) size system.That is, from ONU-1 to ONU-4, utilizing wavelength X
1, from ONU-5 to ONU-8, utilizing wavelength X
2, from ONU-9 to ONU-12, utilizing wavelength X
3, from ONU-13 to ONU-16, utilizing wavelength X
4In addition, can make the sign indicating number that ONU-1,5,9 and 13 is distributed shared.Equally, the sign indicating number that ONU-2,6,10 and 14 is distributed, the sign indicating number that ONU-3,7,11 and 15 is distributed, the sign indicating number that ONU-4,8,12 and 16 is distributed respectively can be shared.In addition, ONU-1 to ONU16 corresponds respectively to first channel (ch1) to the 16th channel (ch16).Certainly, the distribution of above-mentioned sign indicating number and only be an example to the distribution of the channel of ONU should not be defined in this.
Wavelength through with signal wavelength utilization increases to λ
1To λ
4Four kinds; Light clutch 66-1 and the 66-4 corresponding with light clutch in the optical access network system of first embodiment 66; And between the optical coupler 124-1 and 124-4 corresponding, need have the wavelength selectivity multiplexer/demultiplexer 50 and 54 of wavelength selectivity with optical coupler 124.
Wavelength selectivity multiplexer/demultiplexer as having wavelength selectivity for example can use the WDM multiplexer/demultiplexer.In addition, also can utilize each port to be provided with device through the different filter of wavelength to the light clutch and the separated light of this light clutch of output with wavelength selectivity.
In the optical access network system of second embodiment, with λ
1To λ
4The structure of the each several part that communicates of signal wavelength the optical access network system with first embodiment is identical respectively, therefore can know the high speed signal of transmit-receive sharing, and obtain need the number of wavelengths of utilizing not being increased to the effect about photosystem of the same race in the past.
Claims (1)
1. optical access network system; This optical access network system is provided with the light clutch at an end of optical fiber transmission path; And and the optical line terminal device and a plurality of optical terminal device of the other end of said optical fiber transmission path coupling between; These a plurality of optical terminal devices are distributed mutually different sign indicating numbers respectively, carry out bidirectional optical through code division multiplexing, said a plurality of optical terminal devices respectively with separate form a plurality of through said smooth clutch and separate the optical fiber transmission paths coupling; This optical access network system is characterised in that
Said a plurality of optical terminal device and said optical line terminal device have respectively: send signal processing part, it is encoded to the transmission signal and generates coding and sends signal and output; And the reception signal processing part, it receives the code division multiplex signal that is transmitted by code division multiplexing, and take out after this code division multiplex signal is decoded and receive signal,
Said transmission signal processing part has: sign indicating number is given circuit, and it is encoded to said transmission signal; And delay circuit; It is connected to the back level that this yard given circuit; Said coding being sent the phase place of signal adjusts; It is decoded and auto-correlation waveform that generate is decoded with the reflecting background component that in optical connector, takes place and cross-correlation waveform that generate staggers on time shaft make to send signal, and output is sent signal through the adjusted said coding of phase place
Said reception signal processing part has the decoding processing circuit that said code division multiplex signal is decoded, and this decoding processing circuit has analog matched filter and decision circuit,
This analog matched filter has: analogue shift register, positive signal with adder, negative signal with adder, will be respectively from this positive signal with adder and this negative signal analog adder and low pass filter with the output signal plus of adder.
Applications Claiming Priority (6)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2006026342A JP4784323B2 (en) | 2006-02-02 | 2006-02-02 | Optical access network system |
| JP2006-026342 | 2006-02-02 | ||
| JP2006026341A JP4876602B2 (en) | 2006-02-02 | 2006-02-02 | Optical access network system |
| JP2006-026341 | 2006-02-02 | ||
| JP2006026341 | 2006-02-02 | ||
| JP2006026342 | 2006-02-02 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN101013930A CN101013930A (en) | 2007-08-08 |
| CN101013930B true CN101013930B (en) | 2012-05-23 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 200610169214 Expired - Fee Related CN101013930B (en) | 2006-02-02 | 2006-12-20 | Optical access network system |
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| JP (1) | JP4876602B2 (en) |
| CN (1) | CN101013930B (en) |
Families Citing this family (5)
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|---|---|---|---|---|
| JP4775209B2 (en) * | 2006-09-22 | 2011-09-21 | 沖電気工業株式会社 | Code division multiplexing optical access network system |
| JP4973402B2 (en) | 2007-09-07 | 2012-07-11 | 沖電気工業株式会社 | Parallel decoder |
| JP2009194524A (en) | 2008-02-13 | 2009-08-27 | Oki Electric Ind Co Ltd | Passive optical network communicating system |
| JP5206013B2 (en) * | 2008-02-20 | 2013-06-12 | 沖電気工業株式会社 | Optical communication network and intensity adjustment method in optical communication network |
| JP5056463B2 (en) * | 2008-02-20 | 2012-10-24 | 沖電気工業株式会社 | Code division multiplexing transmission / reception system |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1275004A (en) * | 1999-02-06 | 2000-11-29 | 阿尔卡塔尔公司 | Light transmission system and transmitter and receiver thereof |
| CN1278681A (en) * | 1999-06-18 | 2001-01-03 | 阿尔卡塔尔公司 | Sending and receiving installation for synchronous CDMA network of multipoint-to-one-point |
| CN1397113A (en) * | 2000-01-14 | 2003-02-12 | 康宁股份有限公司 | System and method for measuring in-band cross-talk in optical communication system |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS62105541A (en) * | 1985-11-01 | 1987-05-16 | Fujitsu Ltd | Optical receiving circuit |
| JP3058820B2 (en) * | 1995-12-11 | 2000-07-04 | 沖電気工業株式会社 | Demodulation method for spread spectrum communication and demodulation device using the method |
| JP4370043B2 (en) * | 2000-05-18 | 2009-11-25 | 新日本無線株式会社 | Spread spectrum communication system |
| JP4075405B2 (en) * | 2002-02-25 | 2008-04-16 | 沖電気工業株式会社 | Receiver |
| JP4419391B2 (en) * | 2003-01-09 | 2010-02-24 | 沖電気工業株式会社 | Transmission medium access control system and relay side terminal device |
| JP4161830B2 (en) * | 2003-07-14 | 2008-10-08 | 沖電気工業株式会社 | Communications system |
-
2006
- 2006-02-02 JP JP2006026341A patent/JP4876602B2/en not_active Expired - Fee Related
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1275004A (en) * | 1999-02-06 | 2000-11-29 | 阿尔卡塔尔公司 | Light transmission system and transmitter and receiver thereof |
| CN1278681A (en) * | 1999-06-18 | 2001-01-03 | 阿尔卡塔尔公司 | Sending and receiving installation for synchronous CDMA network of multipoint-to-one-point |
| CN1397113A (en) * | 2000-01-14 | 2003-02-12 | 康宁股份有限公司 | System and method for measuring in-band cross-talk in optical communication system |
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| Publication number | Publication date |
|---|---|
| JP4876602B2 (en) | 2012-02-15 |
| JP2007208746A (en) | 2007-08-16 |
| CN101013930A (en) | 2007-08-08 |
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