JP4204984B2 - Multi-speed burst optical signal receiver with optimized reception sensitivity. - Google Patents

Description

  The present invention relates to an optical access system using a passive optical network (PON), and more particularly to a burst optical signal receiver in an optical subscriber unit (OLT).

  In an optical access system based on a passive optical network system (hereinafter referred to as “PON”), B-PON (Broadband Passive Optical Network) standardized by ITU-T (for example, refer to “Non-patent Document 1”) or standardization. Is G-PON (Gigabit Capability Passive Optical Network) (for example, refer to “Non-patent Document 2”). In the PON, a downstream signal transmission from an optical subscriber unit (hereinafter referred to as “OLT”) to an optical subscriber unit (ONU) is transmitted using broadcast continuous light. It is data transmission by. On the other hand, the uplink signal transmission from the ONU to the OLT is an optical burst transmission because it is time division multiple access (TDMA) from a plurality of ONUs.

  In optical burst transmission, at the beginning of an upstream signal transmitted in bursts from an ONU, a guard time for preventing collision between signals, an identification level setting for each burst signal, a preamble for performing bit synchronization, a head of a frame, By adding an overhead composed of a delimiter for establishing byte synchronization, a burst signal can be processed in the optical signal receiver of the OLT. The size of this overhead is selected for each transmission speed so that the burst signal can be received in consideration of transfer efficiency, and the overhead time length is shortened as the transmission speed increases. Has been. For this reason, the optical burst transmission has a problem that the signal becomes more difficult to handle as the transmission speed becomes higher than the data transmission method using continuous light.

  In order to alleviate this problem, in B-PON and G-PON, a plurality of uplink transmission rates can be selected with respect to the downlink transmission rate. For example, in G-PON, the transmission rate of 155.52 Mbit / s, 622.08 Mbit / s, or 1244.16 Mbit / s can be selected for the transmission rate of downlink 1244.16 Mbit / s. Further, there is also a transmission rate of downlink 2488.32 Mbit / s. On the other hand, a transmission rate of uplink 155.52 Mbit / s, 622.08 Mbit / s, 1244.16 Mbit / s, or 2488.32 Mbit / s can be selected. In a single G-PON system, one transmission rate is selected from these uplink rates.

ITU-T G983.1 ITU-T G984.1, 2

  On the other hand, in order to increase the uplink transmission speed after introducing the PON system once, it is necessary to replace not only the OLT but also the existing ONUs. For this reason, a great amount of labor and cost are required for the work. In order to solve this problem, a PON system that does not require replacement of the OLT and the ONU, that is, a PON system that accommodates a plurality of ONUs having different uplink transmission rates is assumed.

  A configuration example of a PON system that accommodates a plurality of ONUs having different uplink speeds will be described with reference to FIG. In this example, a G-PON system with a downlink speed of 1244.16 Mbit / s will be described as an example. The OLT 1 is connected to the ONUs 4a to 4d through the optical line 2 and the optical splitters 3a and 3b. Although only four ONUs 4a to 4d are shown for the sake of clarity, it is assumed that a large number of ONUs are connected. Downstream signal transmission from the OLT 1 to the ONUs 4a to 4d is performed by broadcast continuous light, and upstream signal transmission from the ONUs 4a to 4d to the OLT 1 is performed by burst light of time division multiple access.

  In the G-PON system with a downlink speed of 1244.16 Mbit / s, the upstream speeds that the ONUs 4a to 4d can take are 155.52 Mbit / s, 622.08 Mbit / s, and 1244.16 Mbit / s. The signal receiver needs to perform signal identification corresponding to three types of transmission rates.

  When transmitting data in the downlink direction, the OLT 1 creates a downlink frame by multiplexing grant information with data in the downlink transmission direction based on control information stored in the management table. The grant information is access right information for performing time division multiplexing control in the uplink transmission direction, and controls the burst transmission timing of each ONU 4a to 4d in the uplink transmission direction based on the grant information. In other words, before starting communication with the ONU, the OLT 1 performs time-sharing by controlling the transmission timing from the ONU by performing initial settings such as measuring the distance between the OLT 1 and the ONU and acquiring ONU information. Performs ranging to achieve multiple control. In the following embodiment, ONU transmission rate information managed by the OLT 1 by initial setting and uplink burst signal transmission timing information (arrival timing information) are used for predetermined processing.

  Next, referring to FIG. 2, the configuration of the optical signal receiver provided in OLT 1 shown in FIG. 1 that receives burst signals having different transmission rates from ONUs 4a to 4d, extracts clocks, and identifies burst signals. The figure is shown. The optical signal receiver 9 includes a light receiving unit 10, a preamplifier 11, an automatic gain control amplifier 12, a clock extraction and signal identification unit 13, and an automatic identification level control circuit 14. Next, the operation will be described. When receiving an optical signal that is a burst signal, the light receiving unit 10 converts the optical signal into an electric signal having a current value proportional to the square of the light intensity. The preamplifier 11 equalizes and amplifies the electric signal, and the automatic gain control amplifier 12 further amplifies the equalized and amplified electric signal. Then, the clock extraction and signal identification unit 13 extracts an optimum clock of the input optical signal and identifies the optical signal. At that time, the automatic identification level control circuit 14 generates a reference level and outputs it to the automatic gain control amplifier 12. This reference level is a signal for controlling the gain of the automatic gain control amplifier 12 so that the threshold value for identifying the optical signal is optimized in the clock extraction and signal identification unit 13, and from the ONUs 4a to 4d to the OLT 1 The optical signal receiver 9 is reset immediately before the optical signal as a burst signal arrives, and is automatically set to an optimum value for each burst signal in the automatic identification level control circuit 14.

  Specifically, the automatic identification level control circuit 14 receives the reset signal that defines the arrival timing at the OLT 1 of the electric signal output from the preamplifier 11 and the burst signal transmitted from each of the ONUs 4a to 4d. The preamble section of the electric signal is identified from the timing of the above, and an optimum reference level is generated and output for each burst signal from the preamble level. The clock extraction and signal identification unit 13 includes a clock recovery circuit 13a and a signal identification unit 13b. The electric signal amplified to the optimum level is identified using the optimum clock and is output as an identification signal. In this specification, a signal defining the burst signal arrival timing in the OLT obtained from the transmission timing of the burst signal transmitted from each ONU to the OLT and the signal transmission time between the OLT and the ONU is referred to as a reset signal. .

  In this way, in a PON system that contains a plurality of ONUs having different uplink speeds, the clock extraction and signal identification unit 13 of the OLT optical signal receiver 9 generates a clock having a frequency corresponding to the transmission speed of each burst signal. It is assumed that each burst signal is identified by using the generated burst signal.

  However, in the above-described PON system, the equalization gain band of the preamplifier 11 for equalizing and amplifying the electric signal is optimized to the highest speed among the transmission speeds of the plurality of ONUs, and is slower than the highest speed. Even if a speed signal is received, the reception sensitivity is limited to the lowest (bad) highest speed reception sensitivity among them. For example, in the above example, the uplink transmission rates are 155.52 Mbit / s, 622.08 Mbit / s, and 1244.16 Mbit / s, so that the equalization gain band of the preamplifier 11 is the maximum speed of the ONU. Because it is optimized for a certain 1244.16 Mbit / s, receiving the signals of 155.52 Mbit / s and 622.08 Mbit / s is the lowest (bad) of the three rates, receiving 1244.16 Mbit / s There was a drawback of being limited by sensitivity. Here, the optimum equalization gain bandwidth is proportional to the transmission rate, and the reception sensitivity is proportional to the square root of the equalization gain bandwidth. When the preamplifier 11 is a feedback resistance amplifier, the equalization gain bandwidth is inversely proportional to the feedback resistance, and the noise power density due to thermal noise is inversely proportional to the feedback resistance. At this time, when thermal noise generated by the feedback resistor is dominant as a noise source, the reception sensitivity is proportional to the equalization gain bandwidth.

  Accordingly, an object of the present invention is to provide an optimum equalization gain band for each burst signal transmission rate in a burst optical signal receiver used for an OLT accommodating a plurality of ONUs having different transmission rates of uplink burst signals. It is to provide a selectable burst optical signal receiver.

  In order to solve the above problem, the present invention provides a multi-rate burst optical signal reception means for switching the equalization gain band to an optimum value according to the transmission rate information of the upstream signal from the ONU and the arrival timing information of the upstream signal. Prepare for the preamplifier of the instrument. The outline of the optical signal receiver of the present invention will be described with reference to FIG. In the figure, the optical signal receiver 90 includes a light receiving unit 10, a preamplifier 110, an automatic gain control amplifier 12, a clock extraction and signal identification unit 13, an automatic identification level control circuit 14, and a switching signal generator 120. The light receiving unit 10, the automatic gain control amplifier 12, the clock extraction and signal identification unit 13, and the automatic identification level control circuit 14 have the same functions as the units having the same numbers shown in FIG. In FIG. 3, the switching signal generator 120 inputs the transmission rate information of the burst signal received by the optical signal receiver 90 and the reset signal indicating the OLT arrival timing of the burst signal, and precedes the burst signal. A switching signal that optimizes the equalization gain band of the amplifier 110 is output. The preamplifier 110 receives the switching signal from the switching signal generator 120 and sets the equalization gain band to an optimum value by switching the feedback resistor, for example, based on the switching signal. In the PON, the transmission rate and transmission timing (arrival timing) of the upstream burst optical signal transmitted from each ONU to the OLT are managed by the OLT. Therefore, in the present invention, the transmission gain information and transmission timing of each burst optical signal are effectively used, and the equalization gain band is set in the preamplifier 110.

Therefore, in the multi-speed burst optical signal receiver of the present invention, an optical subscriber unit and a plurality of optical subscriber terminators are connected via an optical line and an optical splitter, and the optical subscriber unit to the optical subscriber terminator. In the downstream direction, broadcast optical signals are transmitted continuously, and in the upstream direction from the optical subscriber unit to the optical subscriber unit, burst optical signals for time division multiple access are transmitted. In a multi-rate burst optical signal receiver used in an optical subscriber unit of an optical passive network in which the transmission timing of a burst optical signal in a direction is managed, the optical passive network is connected from the optical subscriber termination unit to the optical subscriber unit. A plurality of types of transmission rates are set for the transmission rate of the upstream burst optical signal to be transmitted, and the multi-rate burst optical signal receiver is sequentially sent from the optical subscriber terminating device. A light receiving unit that receives a burst optical signal, converts the received burst optical signal into an electrical signal, an amplification unit that has amplification means for amplifying the converted electrical signal, and a transmission speed of the received burst optical signal It extracts a clock, and a clock extraction and signal identification unit that identifies the burst optical signal, the amplifying unit may have a means for setting an equalization gain band according to the transmission rate of the burst optical signal received, The amplifying means of the amplifying unit is a feedback resistance type amplifier having a plurality of feedback resistors, and switches the plurality of feedback resistors at the arrival timing of the burst signal based on the transmission speed information of the received burst optical signal. And a switching signal generator for controlling the above . According to the present invention, since the amplification unit sets the equalization gain band using the transmission speed of the burst optical signal managed by the multi-speed burst optical signal receiver, the transmission speed of the received burst optical signal. Different equalization gain bands can be set for each.

In a preferred embodiment of the multi-rate burst optical signal receiver according to the present invention, an optical subscriber unit and a plurality of optical subscriber terminators are connected via an optical line and an optical splitter. In the downstream direction to the equipment, broadcast continuous optical signal transmission is performed, and in the upstream direction from the optical subscriber terminal equipment to the optical subscriber equipment, burst optical signals in time division multiple access are transmitted. In the multi-rate burst optical signal receiver used in the optical subscriber unit of the optical passive network in which the transmission timing of the upstream burst optical signal is managed in the optical passive network, the optical passive network is connected to the optical subscriber from the optical subscriber termination unit. A plurality of types of transmission rates are set for the transmission rate of the upstream burst optical signal transmitted to the device, and the multi-rate burst optical signal receiver is sequentially transmitted from the optical subscriber termination device. A light receiving unit that receives an incoming burst optical signal, converts the received burst optical signal into an electrical signal, an amplification unit that has amplification means for amplifying the converted electrical signal, and a transmission speed of the received burst optical signal. A clock extraction and signal identification unit for extracting a corresponding clock and identifying the burst optical signal, and the amplification unit has means for setting an equalization gain band according to the transmission speed of the received burst optical signal. The amplifying means of the amplifying unit is a feedback resistance type amplifier having a feedback variable resistance, and the value of the feedback variable resistance is determined based on the transmission speed information of the received burst optical signal at the arrival timing of the burst signal. It is further characterized by further comprising a switching signal generator for controlling switching .

In a preferred embodiment of the multi-rate burst optical signal receiver according to the present invention, an optical subscriber unit and a plurality of optical subscriber terminators are connected via an optical line and an optical splitter. In the downstream direction to the subscriber terminal equipment, broadcast optical signals are transmitted continuously. In the upstream direction from the optical subscriber terminal equipment to the optical subscriber equipment, burst optical signals for time division multiple access are transmitted. In the multi-rate burst optical signal receiver used in the optical subscriber unit of the optical passive network in which the transmission timing of the upstream burst optical signal is managed in the subscriber unit, the optical passive network is optically transmitted from the optical subscriber termination unit. A plurality of types of transmission rates are set for the transmission rate of the upstream burst optical signal transmitted to the subscriber unit, and the multi-rate burst optical signal receiver starts from the optical subscriber unit. A light receiving unit that receives a transmitted burst optical signal and converts the received burst optical signal into an electrical signal, an amplification unit that has amplification means for amplifying the converted electrical signal, and transmission of the received burst optical signal A clock extraction and signal identification unit for extracting a clock corresponding to the speed and identifying the burst optical signal, and the amplification unit is set for each of a plurality of types of transmission rates provided at the front stage or the rear stage of the amplification means And a selector that selects one of the plurality of electrical filters, and the timing of the arrival of the burst signal at the timing of arrival of the burst signal based on the transmission speed information of the received burst optical signal. And a switching signal generator for controlling the selector so as to switch the equalization gain band .

In a preferred embodiment of the multi-rate burst optical signal receiver according to the present invention, an optical subscriber unit and a plurality of optical subscriber terminators are connected via an optical line and an optical splitter. In the downstream direction to the subscriber terminal equipment, broadcast optical signals are transmitted continuously. In the upstream direction from the optical subscriber terminal equipment to the optical subscriber equipment, burst optical signals for time division multiple access are transmitted. In the multi-rate burst optical signal receiver used in the optical subscriber unit of the optical passive network in which the transmission timing of the upstream burst optical signal is managed in the subscriber unit, the optical passive network is optically transmitted from the optical subscriber termination unit. A plurality of types of transmission rates are set for the transmission rate of the upstream burst optical signal transmitted to the subscriber unit, and the multi-rate burst optical signal receiver starts from the optical subscriber unit. A light receiving unit that receives a transmitted burst optical signal and converts the received burst optical signal into an electrical signal, an amplification unit that has amplification means for amplifying the converted electrical signal, and transmission of the received burst optical signal A clock extraction and signal identification unit that extracts a clock according to speed and identifies the burst optical signal, and the amplification unit includes a variable electrical filter provided in a preceding stage or a subsequent stage of the amplification unit, and a burst signal A switching signal generator for controlling the value of the variable electrical filter so as to switch the equalization gain band of the variable electrical filter based on the transmission rate information of the received burst optical signal at the arrival timing of And According to the present invention, the amplifying unit sets the equalization gain band using the switching signal generated from the transmission rate information and arrival timing information of the burst optical signal managed by the multi-rate burst optical signal receiver. Therefore, a different equalization gain band can be set for each transmission speed of the received burst optical signal.

Further, in the preferred embodiment of the multi-rate burst optical signal receiver according to the present invention, the transmission rate of the upstream burst optical signal set in the optical subscriber terminating device is 2 ⁿ times the basic rate A (n = 0, 1). , 2... N) are selected from L types (L ≦ N + 1) of the transmission rates. According to the present invention, for example, in the case of G-PON with a downlink speed of 1244.16 Mbit / s, the basic speed is 155.52 Mbit / s, and the transmission speed of the uplink burst is 155.52 Mbit / s, 622.08 Mbit / s. And three speeds of 1244.16 Mbit / s can be used.

  According to the multi-rate burst optical signal receiver of the present invention, when receiving burst optical signals having different transmission rates, an equalization gain band optimum for the transmission rate of the burst optical signal can be selected. Thereby, it is possible to obtain a higher reception sensitivity for a signal having a lower transmission speed without being limited by the reception sensitivity of the burst optical signal having the highest transmission speed.

Hereinafter, embodiments of the preamplifier and the switching signal generator in the optical signal receiver of the present invention will be described with reference to FIGS. In this embodiment, a G-PON system having a downlink speed of 1244.16 Mbit / s will be described as an example. In the G-PON system with a downlink speed of 1244.16 Mbit / s, the uplink speed that can be taken by the ONU is 155.52 Mbit / s, 622.08 Mbit / s, or 1244.16 Mbit / s. Are three types, the basic transmission rate A is 155.52 Mbit / s, N is 3, and the maximum transmission rate 2 ^N × A is 1244.16 Mbit / s. 4 to 9 show only the light receiving unit 10, the preamplifiers 111 to 116, and the switching signal generator 120. The automatic gain control amplifier 12, the clock extraction and signal identification unit 13, and the automatic identification are shown. The level control circuit 14 is not shown. The actual configuration of the optical signal receiver is the same as that of the optical signal receiver 90 shown in FIG. A specific configuration of the preamplifier 110 in FIG. 3 is shown in the preamplifiers 111 to 116 in FIGS.

FIG. 4 shows a first embodiment of the optical signal receiver according to the present invention. The optical signal receiver according to the first embodiment includes a light receiving unit 10, a preamplifier 111, a switching signal generator 120, an automatic gain control amplifier 12, a clock extraction and signal identification unit 13, and an automatic identification level control circuit 14. The automatic gain control amplifier 12, the clock extraction and signal identification unit 13, and the automatic identification level control circuit 14 are not shown. In the figure, the preamplifier 111 includes an amplifier 111a, a feedback resistor 111b (feedback resistors _Rf1 , _Rf2 , _Rf3 ), and a selector 111c. Here, the feedback resistors R _f1 , R _f2 , and R _f3 have equalized gain bands that are optimal for transmission speeds of 1244.16 Mbit / s, 622.08 Mbit / s, and 155.52 Mbit / s, respectively. It is set to be able to The preamplifier 111 inputs an electric signal converted from the optical signal received by the light receiving unit 10. At this time, the selector 111c inputs the switching signal generated from the transmission rate information and the reset signal (ATC reset signal / burst signal arrival timing signal) from the switching signal generator 120, and the electric signal input to the preamplifier 111. The optimum feedback resistor is selected from the feedback resistors R _f1 , R _f2 , R _f3 and switched. In this case, since the equalization gain band is inversely proportional to the feedback resistance, the equalization gain band can be optimized. Accordingly, the preamplifier 111 outputs an electric signal in which the equalization gain band is optimized at the transmission speed of the input electric signal.

  According to the preamplifier 111 of the first embodiment, the optimum feedback resistor for the burst signal is selected from a plurality of preset feedback resistors based on the transmission rate information of the burst signal at the arrival timing of the burst signal. I tried to do it. Thereby, the equalization gain band can be optimized at the transmission rate of the burst signal, and high reception sensitivity can be obtained.

FIG. 5 shows a second embodiment of the optical signal receiver according to the present invention. The optical signal receiver of the second embodiment is different from the optical signal receiver of FIG. 4 in that the preamplifier 111 of the optical signal receiver shown in FIG. Specifically, the preamplifier 112 is different in that the feedback resistors R _f1 , R _f2 , R _f3 and the selector 111c shown in FIG. 4 are replaced with a feedback variable resistor 112b. In the figure, the preamplifier 112 has an amplifier 112a and a feedback variable resistor 112b. Here, the feedback variable resistor 112b has a resistance value such that an optimum equalization gain band can be obtained for transmission speeds of 1244.16 Mbit / s, 622.08 Mbit / s, and 155.52 Mbit / s, respectively. It shall be set. The feedback variable resistor 112b receives a switching signal from the switching signal generator 120 and switches the resistance value to an optimum resistance value for the input electric signal. Accordingly, the preamplifier 112 outputs an electric signal in which the equalization gain band is optimized at the transmission speed of the input electric signal.

  According to the preamplifier 112 of the second embodiment, the resistance of the feedback variable resistor 112b is set so as to obtain an optimum feedback resistance value for the burst signal based on the transmission speed information of the burst signal at the arrival timing of the burst signal. Changed the value. Thereby, the equalization gain band can be optimized at the transmission rate of the burst signal, and high reception sensitivity can be obtained.

FIG. 6 shows a third embodiment of the optical signal receiver according to the present invention. The optical signal receiver according to the third embodiment includes a light receiving unit 10, a preamplifier 113, a switching signal generator 120, an automatic gain control amplifier 12, a clock extraction and signal identification unit 13, and an automatic identification level control circuit 14. The automatic gain control amplifier 12, the clock extraction and signal identification unit 13, and the automatic identification level control circuit 14 are not shown. In the figure, the preamplifier 113 includes an amplifier 113a, a feedback resistor 113b (feedback resistor _Rf ), a selector 113c, and an electric filter 113d (electric filters EF1, EF2, EF3). Here, it is assumed that the feedback resistor _Rf is set so as to obtain an optimum equalization gain band with respect to a transmission rate of 1244.16 Mbit / s. In addition, the electric filters EF1, EF2, and EF3 are filters so that optimum equalization gain bands can be obtained for transmission speeds of 1244.16 Mbit / s, 622.08 Mbit / s, and 155.52 Mbit / s, respectively. It is assumed that a value has been set. The preamplifier 113 receives an electrical signal converted from the optical signal received by the light receiving unit 10, the amplifier 113a amplifies the electrical signal, and the selector 113c receives the amplified electrical signal. At this time, the selector 113c receives the switching signal generated from the transmission rate information and the reset signal from the switching signal generator 120, and selects the optimum electrical filter for the electrical signal input to the selector 113c by the electrical filters EF1 and EF2. , EF3 is selected and switched. Accordingly, the preamplifier 113 outputs an electric signal in which the equalization gain band is optimized at the transmission speed of the input electric signal.

  According to the preamplifier 113 of the third embodiment, the optimum electrical filter for the burst signal is selected from a plurality of preset electrical filters based on the transmission speed information of the burst signal at the arrival timing of the burst signal. I tried to do it. Thereby, high receiving sensitivity can be obtained at the transmission speed of the burst signal.

In addition, according to the preamplifier 113 of the third embodiment, the electric filter 113d is optimized for transmission speeds of 1244.16 Mbit / s, 622.08 Mbit / s, and 155.52 Mbit / s, respectively. The electric filters EF1, EF2, and EF3 set so as to obtain a gain gain band are provided, but the electric filter EF1 corresponding to 1244.16 Mbit / s is omitted, and the front and rear thereof are short-circuited. Also good. The feedback resistor R _f is set so that an optimum equalization gain band can be obtained with respect to a transmission rate of 1244.16 Mbit / s, so that the amplifier 113a generates an electric signal that has already been optimized at the transmission rate. It is because it is outputting.

FIG. 7 shows a fourth embodiment of the optical signal receiver according to the present invention. The optical signal receiver of the fourth embodiment is different from the optical signal receiver of FIG. 6 in that the preamplifier 113 of the optical signal receiver shown in FIG. Specifically, the preamplifier 114 is different in that the selector 113c and the electric filter 113d shown in FIG. 6 are replaced with a variable electric filter 114c. In the figure, the preamplifier 114 includes an amplifier 114a, a feedback resistor 114b, and a variable electrical filter 114c. Here, it is assumed that the feedback resistor _Rf is set so as to obtain an optimum equalization gain band with respect to a transmission rate of 1244.16 Mbit / s. In addition, the variable electrical filter 114c has filter values set so that an optimum equalization gain band can be obtained for transmission speeds of 1244.16 Mbit / s, 622.08 Mbit / s, and 155.52 Mbit / s, respectively. Shall be. The variable electric filter 114c receives the electric signal amplified by the amplifier 114a. At this time, the variable electric filter 114c receives the switching signal from the switching signal generator 120, and switches the value to the optimum electric filter value for the electric signal input to the variable electric filter 114c. Accordingly, the preamplifier 114 outputs an electric signal in which the equalization gain band is optimized at the transmission speed of the input electric signal.

  According to the preamplifier 114 of the fourth embodiment, the filter of the variable electric filter 114c is set so as to obtain an optimum electric filter value for the burst signal based on the transmission speed information of the burst signal at the arrival timing of the burst signal. Changed the value. As a result, the equalization band of the electric filter is switched to an optimum value for the transmission speed of the electric signal, and high reception sensitivity can be obtained at the transmission speed of the burst signal.

In addition, according to the preamplifier 114 of the fourth embodiment, the variable electric filter 114c is optimized for transmission speeds of 1244.16 Mbit / s, 622.08 Mbit / s, and 155.52 Mbit / s, respectively. The filter value can be changed so as to obtain an equalization gain band. Among these, the switching value is variable when a switching signal for switching to an electrical filter value corresponding to 1244.16 Mbit / s is input from the switching signal generator 120. The electrical filter 114c may omit the filtering and short-circuit the front and rear thereof. Similar to FIG. 6, since the feedback resistor R _f is set so as to obtain an equalization gain band optimized for a transmission rate of 1244.16 Mbit / s, the amplifier 114a is already optimal at the transmission rate. This is because a converted electric signal is output.

FIG. 8 shows a fifth embodiment of the optical signal receiver according to the present invention. The optical signal receiver of the fifth embodiment is different from the optical signal receiver of FIG. 6 in that the preamplifier 113 of the optical signal receiver shown in FIG. Specifically, the preamplifier 115 is different from the preamplifier 113 in that the order of the amplifier 113a and the feedback resistor 113b, the selector 113c, and the electric filter 113d is changed. In the figure, the preamplifier 115 includes an amplifier 115a, a feedback resistor 114b, a selector 115c, and an electric filter 115d (electric filters EF1, EF2, EF3). Here, it is assumed that the feedback resistor _Rf is set so as to obtain an optimum equalization gain band with respect to a transmission rate of 1244.16 Mbit / s. In addition, the electric filters EF1, EF2, and EF3 are set so that optimum equalization gain bands can be obtained for transmission speeds of 1244.16 Mbit / s, 622.08 Mbit / s, and 155.52 Mbit / s, respectively. It is assumed that The selector 115c receives an electrical signal converted from an optical signal from the light receiving unit 10. At this time, the selector 115c receives the switching signal from the switching signal generator 120, and selects and switches the optimum electrical filter for the electrical signal input to the selector 115c. The amplifier 115a receives an electric signal from the electric filter 115d, amplifies the electric signal, and outputs it.

  According to the preamplifier 115 of the fifth embodiment, the optimum electrical filter for the burst signal is selected from a plurality of preset electrical filters based on the transmission speed information of the burst signal at the arrival timing of the burst signal. I tried to do it. Thereby, the equalization gain band can be optimized at the transmission speed of the burst signal, and high reception sensitivity can be obtained at the transmission speed of the burst signal.

According to the preamplifier 115 of the fifth embodiment, the electric filter 115d is optimized for transmission speeds of 1244.16 Mbit / s, 622.08 Mbit / s, and 155.52 Mbit / s, respectively. The electric filters EF1, EF2, and EF3 set so as to obtain a gain gain band are provided, but the electric filter EF1 corresponding to 1244.16 Mbit / s is omitted, and the front and rear thereof are short-circuited. Also good. Since the feedback resistor R _f is set so as to obtain an equalization gain band optimized for a transmission rate of 1244.16 Mbit / s, the amplifier 115a outputs an electrical signal optimized for the transmission rate. Because it does.

FIG. 9 shows a sixth embodiment of the optical signal receiver according to the present invention. The optical signal receiver of the sixth embodiment is different from the optical signal receiver of FIG. 7 in that the preamplifier 114 of the optical signal receiver shown in FIG. Specifically, the preamplifier 116 is different from the preamplifier 114 in that the order of the amplifier 114a, the feedback resistor 114b, and the variable electrical filter 114c is changed. In the figure, the preamplifier 115 includes an amplifier 116a, a feedback resistor 116b, and a variable electrical filter 116c. Here, it is assumed that the feedback resistor _Rf is set so as to obtain an optimum equalization gain band with respect to a transmission rate of 1244.16 Mbit / s. Further, the variable electrical filter 116c has filter values set so as to obtain optimum equalization gain bands for transmission speeds of 1244.16 Mbit / s, 622.08 Mbit / s, and 155.52 Mbit / s, respectively. Shall be. The variable electrical filter 116 c receives an electrical signal converted from an optical signal from the light receiving unit 10. At this time, the variable electrical filter 116c receives the switching signal from the switching signal generator 120, and switches the filter value so that the optimal electrical filter value is obtained for the electrical signal input to the variable electrical filter 116c. Accordingly, the preamplifier 116 outputs an electric signal in which the equalization gain band is optimized at the transmission speed of the input electric signal.

  According to the preamplifier 116 of the sixth embodiment, the filter of the variable electrical filter 116c is set so as to obtain an optimum electrical filter value for the burst signal based on the transmission speed information of the burst signal at the arrival timing of the burst signal. Changed the value. As a result, the equalization band of the electric filter is switched to an optimum value for the transmission speed of the electric signal, and high reception sensitivity can be obtained at the transmission speed of the burst signal.

In addition, according to the preamplifier 116 of the sixth embodiment, the variable electric filter 116c is optimized for transmission speeds of 1244.16 Mbit / s, 622.08 Mbit / s, and 155.52 Mbit / s, respectively. The filter value can be changed so as to obtain an equalization gain band. Among these, the switching value is variable when a switching signal for switching to an electrical filter value corresponding to 1244.16 Mbit / s is input from the switching signal generator 120. The filtering by the electric filter 116c may be omitted, and the front and rear thereof may be short-circuited. Since the feedback resistor R _f is set so as to obtain an optimum equalization gain band for a transmission rate of 1244.16 Mbit / s, the amplifier 116a outputs an electrical signal optimized at the transmission rate. Because it is.

  The present invention has been described with reference to the embodiments. However, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the technical idea thereof. For example, in the above-described embodiment, the PON in which the downlink transmission rate is 1244.16 Mbit / s and three types of uplink transmission rates are mixed has been described. However, the downlink transmission rate is 2488.32 Mbit / s and four types of uplink transmission rates. Can be applied to a G-PON in which is specified, and can also be applied to a B-PON.

The OLT is a configuration example of a PON system in which a plurality of ONUs having different uplink speeds are mixedly accommodated. It is a block diagram of the optical signal receiver which extracts the clock of a burst signal and identifies a burst signal. It is a block diagram explaining the outline | summary of the optical signal receiver of this invention. It is a block diagram explaining Example 1 in the optical signal receiver of this invention. It is a block diagram explaining Example 2 in the optical signal receiver of this invention. It is a block diagram explaining Example 3 in the optical signal receiver of this invention. It is a block diagram explaining Example 4 in the optical signal receiver of this invention. It is a block diagram explaining Example 5 in the optical signal receiver of this invention. It is a block diagram explaining Example 6 in the optical signal receiver of this invention.

Explanation of symbols

1 OLT
2 Optical line 3a, 3b Optical splitter 4a-4d ONU
9,190 Optical signal receiver 10 Light receiver 11, 110-116 Preamplifier 12 Automatic gain control amplifier 13 Clock extraction and signal identification unit 13a Clock recovery circuit 13b Signal identifier 14 Automatic identification level control circuit 111a-116a Amplifier 111b, 113b, 114b, 115b, 116b feedback resistors 111c, 113c, 115c selector 112b feedback variable resistors 113d, 115d electric filters 114c, 116b variable electric filter 120 switching signal generator

Claims (5)

The optical subscriber unit is connected to a plurality of optical subscriber termination units via an optical line and an optical splitter, and the downstream direction from the optical subscriber unit to the optical subscriber termination unit transmits a broadcast continuous optical signal. In the upstream direction from the optical subscriber unit to the optical subscriber unit, the burst optical signal of time division multiple access is transmitted in the upstream direction, and the transmission timing of the upstream burst optical signal is managed in the optical subscriber unit In a multi-rate burst optical signal receiver used in an optical subscriber unit of a passive network,
In the optical passive network, a plurality of types of transmission rates are set for the transmission rate of the upstream burst optical signal transmitted from the optical subscriber terminal device to the optical subscriber device,
The multi-speed burst optical signal receiver receives a burst optical signal sequentially transmitted from an optical subscriber terminal device, converts a received burst optical signal into an electrical signal, and converts the converted electrical signal. An amplification unit having amplification means for amplifying, and a clock extraction and signal identification unit for extracting the clock according to the transmission speed of the received burst optical signal and identifying the burst optical signal;
The amplifying unit is to have a means for setting an equalization gain band according to the transmission rate of the burst optical signal received, and amplification means of the amplification unit is a feedback resistor type amplifier having a plurality of feedback resistors,
A multi-rate burst optical signal reception characterized by further comprising a switching signal generator that controls to switch the plurality of feedback resistors based on transmission speed information of the received burst optical signal at the arrival timing of the burst signal. vessel. The optical subscriber unit is connected to a plurality of optical subscriber termination units via an optical line and an optical splitter, and the downstream direction from the optical subscriber unit to the optical subscriber termination unit transmits a broadcast continuous optical signal. In the upstream direction from the optical subscriber unit to the optical subscriber unit, the burst optical signal of time division multiple access is transmitted in the upstream direction, and the transmission timing of the upstream burst optical signal is managed in the optical subscriber unit In a multi-rate burst optical signal receiver used in an optical subscriber unit of a passive network,
In the optical passive network, a plurality of types of transmission rates are set for the transmission rate of the upstream burst optical signal transmitted from the optical subscriber terminal device to the optical subscriber device,
The multi-speed burst optical signal receiver receives a burst optical signal sequentially transmitted from an optical subscriber terminal device, converts a received burst optical signal into an electrical signal, and converts the converted electrical signal. An amplification unit having amplification means for amplifying, and a clock extraction and signal identification unit for extracting the clock according to the transmission speed of the received burst optical signal and identifying the burst optical signal;
The amplifying unit has means for setting an equalization gain band according to the transmission speed of the received burst optical signal, and the amplifying unit of the amplifying unit is a feedback resistance type amplifier having a feedback variable resistor,
A multi-rate burst optical signal , further comprising a switching signal generator that controls to switch the value of the feedback variable resistor based on the transmission speed information of the received burst optical signal at the arrival timing of the burst signal. Receiver. The optical subscriber unit is connected to a plurality of optical subscriber termination units via an optical line and an optical splitter, and the downstream direction from the optical subscriber unit to the optical subscriber termination unit transmits a broadcast continuous optical signal. In the upstream direction from the optical subscriber unit to the optical subscriber unit, the burst optical signal of time division multiple access is transmitted in the upstream direction, and the transmission timing of the upstream burst optical signal is managed in the optical subscriber unit In a multi-rate burst optical signal receiver used in an optical subscriber unit of a passive network,
In the optical passive network, a plurality of types of transmission rates are set for the transmission rate of the upstream burst optical signal transmitted from the optical subscriber terminal device to the optical subscriber device,
The multi-speed burst optical signal receiver receives a burst optical signal sequentially transmitted from an optical subscriber terminal device, converts a received burst optical signal into an electrical signal, and converts the converted electrical signal. An amplification unit having amplification means for amplifying, and a clock extraction and signal identification unit for extracting the clock according to the transmission speed of the received burst optical signal and identifying the burst optical signal;
The amplifying unit has a plurality of electric filters respectively set for a plurality of types of transmission speeds provided at the front stage or the rear stage of the amplifying means,
A selector for selecting one of the plurality of electrical filters;
A switching signal generator for controlling the selector so as to switch the equalization gain band of the electric filter based on the transmission rate information of the received burst optical signal at the arrival timing of the burst signal, Multi-rate burst optical signal receiver. The optical subscriber unit is connected to a plurality of optical subscriber termination units via an optical line and an optical splitter, and the downstream direction from the optical subscriber unit to the optical subscriber termination unit transmits a broadcast continuous optical signal. In the upstream direction from the optical subscriber unit to the optical subscriber unit, the burst optical signal of time division multiple access is transmitted in the upstream direction, and the transmission timing of the upstream burst optical signal is managed in the optical subscriber unit In a multi-rate burst optical signal receiver used in an optical subscriber unit of a passive network,
In the optical passive network, a plurality of types of transmission rates are set for the transmission rate of the upstream burst optical signal transmitted from the optical subscriber terminal device to the optical subscriber device,
The multi-speed burst optical signal receiver receives a burst optical signal sequentially transmitted from an optical subscriber terminal device, converts a received burst optical signal into an electrical signal, and converts the converted electrical signal. An amplification unit having amplification means for amplifying, and a clock extraction and signal identification unit for extracting the clock according to the transmission speed of the received burst optical signal and identifying the burst optical signal;
The amplifying unit has a variable electrical filter provided at the front stage or the rear stage of the amplifying means,
A switching signal generator for controlling the value of the variable electrical filter so as to switch the equalization gain band of the variable electrical filter based on the transmission rate information of the received burst optical signal at the arrival timing of the burst signal; A multi-rate burst optical signal receiver. The multi-rate burst optical signal receiver according to any one of claims 1 to 4,
The transmission rate of the upstream burst optical signal set in the optical subscriber unit is L types (L = L) of the transmission rates ²ⁿ times the basic rate A (n = 0, 1, 2... N). A multi-rate burst optical signal receiver characterized by being selected from a rate of ≦ N + 1).

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