KR20040057027A - An optical network unit device and method for transmitting data of ethernet passive optical network - Google Patents

Abstract

PURPOSE: An ONU(Optical Network Unit) in an E-PON(Ethernet-Passive Optical Network) and a method for transmitting data therein are provided to shorten clock recovery time in a network-side OLT(Optical Line Terminal) by transmitting a signal pattern of 1010101010 or 0101010101,= in which 0 and 1 appear alternately, as a start signal pattern for clock recovery in the network-side OLT. CONSTITUTION: A transmitting part(230) in an ONU(200) comprises a state control part(231) and an encoder(232). If a GMII(Gigabit Ethernet Media Independent Interface) signal(TXD£7:0|), a GMII Tx enable signal(TX_EN), a GMII Tx error signal(TX_ER), and a GMII Tx clock(GTX_CLK) are received from a medium access control part(210) and an Xmit signal is received from an AN(Auto-Negotiation) part(220), the state control part(231) creates a set of code groups having control information according to the received signals and sends 8-bit parallel data, based on the created set. The encoder(232) converts the 8-bit parallel data into 10-bit code group data.

Description

E-POON's optical subscriber device and data transmission method {AN OPTICAL NETWORK UNIT DEVICE AND METHOD FOR TRANSMITTING DATA OF ETHERNET PASSIVE OPTICAL NETWORK}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical subscriber device of E-PON and a data transmission method thereof, and in particular, an E-PON which increases the bandwidth usage efficiency in an E-PON (Ethernet-Passive Optical Network, hereinafter referred to as 'E-PON'). An optical subscriber device and a data transmission method thereof.

Currently, ASL (Asymmetric Digital Subscriber Line) and Cable Modem are most commonly used for high-speed Internet services. ADSL provides high speed internet service by using existing telephone line. It provides high speed service of 2Mbps ~ 10Mbps by installing ADSL modem in subscriber's computer.

Cable modems provide high-speed Internet service using coaxial cable installed for existing cable TV service. The cable modem should be installed in the PC while the subscriber is receiving cable TV service.

The high speed internet service has a much larger transmission capacity (2Mbps ~ 10Mbps) compared to the existing 56Kbps telephone line modem, and is satisfactory for providing services such as Internet web surfing (HTTP), e-mail, and file transfer (FTP). However, Voice over Internet Protocol (VoIP), Video on Demand (VoD), Internet broadcasting service, and the like have limitations to meet the requirements of newly added users.

In addition, the cable modem high-speed Internet service has a disadvantage in that the available bandwidth is reduced as the number of subscribers increases, ADSL high-speed Internet service has a disadvantage that the bandwidth can be provided as the distance from the telephone company to the subscriber network is farther away .

To address these shortcomings, Fiber To The Home (FTTH), Fiber To The Building (FTTB), and Fiber To The Curb (FTTC), which install fiber optic cables to subscriber networks, have been proposed. Research is underway on E-PON to improve.

E-PON is a network that combines Ethernet technology with only passive devices instead of using active devices that use power in optical subscriber networks to improve price competitiveness.

The specification for E-PON is being produced by the Institute of Electrical and Electronics Engineers (IEEE) 802.3ah Ethernet in the first Mile Task Force. A display example of such an E-PON is attached to FIG. 1.

1 illustrates a structure of an E-PON according to the prior art, and as shown in FIG. 1, an E-PON is a structure of a point-to-multi point, and one optical (OLT) Line Terminal: Optical Termination Unit, hereinafter referred to as 'OLT', 10) A number of ONUs (Optical Subscriber Unit, hereinafter referred to as 'ONU', 20) are used to connect a splitter (30), a passive element, to a port. Connected through

The data transfer between the OLT 10 and the ONU 20 is transmitted through an Ethernet frame, and the downstream from the OLT 10 to the ONU 20 transmits data through broadcasting. The upstream signal from the ONU 20 to the OLT 10 uses a time division multiplexing access (TDMA) method to share the bandwidth allocated to several ONUs.

That is, in transmitting the uplink signal to the OLT 10, the existing ONUs 20 receive IDLE data from the OLT 10 so as not to collide with each other through a burst mode. (The clock recovery time in the OLT and data for code group alignment) are sent to the OLT 10, and then the uplink frame is transmitted according to the TDMA scheme.

Through this, the OLT 10 receives signals of different levels from each ONU, which is shown in FIG. 2.

FIG. 2 is a diagram illustrating a reception signal level in an OLT of an E-PON according to the prior art, and the left hatched portion means a large reception signal level, and the right hatched portion means a low reception signal level. . When receiving different levels of received signals as described above, the general OLT 10 receives data received after the clock recovery time Tcr.

At this time, the initial signal transmitted from the ONU 20 applied to the burst mode of the E-PON to the OLT 10 is IDLE, and becomes '00111110101001000101' to increase the clock recovery time in the OLT 10. This not only degrades the overall upward bandwidth usage efficiency, but also causes system performance degradation.

The technical problem to be solved by the present invention is to solve this problem, by transmitting a signal pattern in which 0 and 1 alternately display the start signal pattern for clock recovery in the network side optical termination apparatus (OLT), network side optical termination apparatus It is an object of the present invention to provide an optical subscriber device of E-PON and a data transmission method thereof that can reduce clock recovery time in an (OLT).

Another object of the present invention is to provide an optical subscriber device of E-PON and a data transmission method thereof, which can increase uplink bandwidth usage efficiency in an access network sharing uplink channels.

1 is a view showing the structure of the E-PON of the embodiment according to the prior art.

2 is a diagram illustrating a reception signal level in the OLT of the E-PON according to the prior art.

3 is a diagram illustrating an optical subscriber device of an E-PON according to an embodiment of the present invention.

FIG. 4 is a diagram for describing an operation process of the state controller illustrated in FIG. 3.

5 is a diagram illustrating a code group state according to an embodiment of the present invention.

6 is a diagram illustrating transmission and reception signal timing of an optical subscriber device according to an embodiment of the present invention.

※ Explanation of code for main part of drawing ※

200: optical subscriber device

210: medium access control unit 220: automatic negotiation unit

230: transmitting unit 231: state control unit

232: encoder 240: PMA

250: optical transmitter

The optical subscriber device of the E-PON according to the present invention for achieving the above object is, in the multiple optical subscriber device for transmitting data burst at the time allowed by a single network-side optical termination device, the network-side optical termination device from the outside A medium access control unit for receiving a window signal which is a signal related to whether or not to allow data transmission to a network; According to the state of the received window signal, after generating a start signal pattern for shortening the clock recovery time of the network-side optical termination device as a signal pattern of a predetermined bit alternately 0 and 1, and then transmitted, the network-side optical A transmitter for transmitting burst data to be transmitted to an end device; And an optical transmitter for transmitting the bursted data transmitted from the transmitter only at a time allowed by the network side optical termination device.

At this time, the generated start signal pattern is characterized in that it comprises a signal pattern of 1010101010 or 0101010101.

In addition, the data transmission method of the optical subscriber device of the E-PON according to another aspect of the present invention, in the data transmission method of a plurality of optical subscriber devices for transmitting data burst at a time allowed by a single network-side optical termination device a) receiving a window signal which is a signal related to whether data transmission is allowed from the outside to the network side optical termination device; b) generating and transmitting a start signal pattern for reducing a clock recovery time of the network side optical termination device as a signal pattern of a predetermined bit in which 0 and 1 alternately according to the state of the received window signal; And c) transmitting the bursted data only at a time allowed by the network-side optical termination device, and then transmitting a code group indicating the end of the bursted data to the network-side optical termination device. .

A recording medium comprising a data transmission method of a plurality of optical subscriber apparatuses for transmitting data burst at a time allowed by a single network-side optical termination apparatus according to another aspect of the present invention, comprising: a) network-side optical termination from the outside; Receiving a window signal, which is a signal associated with the permission of data transmission to the device; b) a function of generating a start signal pattern for shortening a clock recovery time of the network side optical termination device as a signal pattern of a predetermined bit in which 0s and 1s alternately appear according to the state of the received window signal and transmitting the generated signal; And c) transmitting the bursted data only at the time allowed by the network-side optical termination device, and then transmitting a code group indicating the end of the bursted data to the network-side optical termination device. Characterized by the medium.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 3 is a diagram illustrating an optical subscriber device of an E-PON according to an embodiment of the present invention. Referring to the drawings, FIG. 3 illustrates the principals of an optical subscriber device (Optical Network Unit, 200), in particular, a transmitter (ONU PCS TX, 230). The details of the function and operation process are as follows.

Referring to FIG. 3, the transmitter 230 of the optical subscriber device 200 includes a state controller 231 and an encoder 232.

First, the GMII (Gigabit Ethernet Media Independent Interface) interface of the Gigabit Ethernet MAC chip and PHY chip (hereinafter referred to as GMII) from the media access control unit (E-PON ONU MAC, 210) and TXD [ 7: 0] and TX_EN, the GMII transmission enable signal, TX_ER, the GMII transmission error signal, and GTX_CLK, the transmission clock (frequency 125 MHz) of GMII, and notify the operation status from the auto-negotiation unit 220. When the Xmit signal is received, the state controller 231 sets a set of code groups having control information according to the received signal (for example, / C /, / I /, / S /, / T /, / R /, / V / etc.), and then sends 8-bit parallel data according to the set of generated code groups. Thereafter, the encoder 232 converts the transmitted 8-bit parallel data into 10-bit code group data so as to reduce an error in data transmission.

Then, the operation of each functional unit will be described in detail with reference to the accompanying drawings.

FIG. 4 is a diagram for describing an operation process of the state controller illustrated in FIG. 3. In the state controller 231, 0 and 1 alternately appear as a start signal pattern for clock recovery when burst data is received at an OLT receiver. In order to generate the signal pattern '1010101010', a set of code groups as shown in FIG. 4 is generated.

In detail, a portion indicated by a dotted line in FIG. 4 is a code group added by the state control unit 231 according to an embodiment of the present invention, and a variable (Tx_o_set) for indicating any one of a set of code groups having control information. Enter the / P / code, which is the signal pattern '1010101010' where 0 and 1 alternately appear and is defined as D21.5. In this case, the input / P / code may be defined as D10.2 which is '0101010101' in some cases.

Through this, the transmitter 230 transmits the 10-bit parallel data tx_code-group [9: 0] according to the input / P / code to the PMA 240.

5 is a diagram illustrating a code group state according to an embodiment of the present invention. As shown, the state control unit 231 transitions from the GENERATE_CODE_GROUPS state (a standby state for generation of a transmission code group) to the SPECIAL_GO state. Add / P / code to Then, the added / P / code is input to the code group tx_code_group.

Next, FIG. 6 is a diagram illustrating transmission and reception signal timing of an optical subscriber device according to an embodiment of the present invention. Referring to FIG. 6, the overall operation of the optical subscriber device according to the present invention will be described as follows. .

First, when the window signal (signal related to whether or not the OLT allows the transmission of the signal to the optical subscriber device in the PON system) is received from the medium access control unit 210, the auto negotiation unit 220 corresponds to the received signal. The laser on / off signal is transmitted to the optical transmitter 250.

On the other hand, when the window signal received from the medium access control unit 210 is FALSE, the Xmit signal (signal for notifying the operation state of the PCS transmission unit) is kept in the IDLE state and becomes the PON state when the window signal becomes TRUE. The optical subscriber device 200 enters the DATA state after the code group alignment time Tlr and clock recovery time Tcr for receiving burst data have elapsed. After that, when the widow signal becomes FALSE again, the IDLE state is established. The IDLE state is maintained until the widow signal is TRUE again.

In this case, when the xmit signal is in the DATA state, the medium access control unit 210 enables the transmission enable signal TX_EN after transmitting the IDLE signal necessary for the code group alignment at the OLT PCS receiver, and enables 8-bit parallel data TXD [. 7: 0] also send together.

Thereafter, the transmitter 231 transmits a start signal pattern in which 10-bit parallel data, that is, 0 and 1, alternately appear to the PMA 240 according to the received 8-bit parallel data and the xmit signal state.

In detail, the transmitter 231 transmits the IDLE code group /K28.5/D16.2/ to the PMA 240 when the xmit signal state received from the auto negotiation unit 220 is IDLE. When the xmit signal state is PON, / P /, that is, /D21.5/ is transmitted.

On the other hand, if the state of the received Xmit signal is DATA and the transmit enable signal TX_EN is FALSE, the tx_code-group data transmitted to the PMA 240 is transmitted through IDLE, and when the transmit enable signal TX_EN becomes TRUE again. Code group data encoded with 8-bit parallel data is transmitted to PMA (Physical Media Attachment) 240 starting with / S / which indicates the start of an Ethernet frame.

At this time, in order for the OLT PCS receiving end to recognize the end of the frame and allow normal frame reception, the transmitter 230 according to the present invention transmits a / T / R / I / control code group indicating the end of the frame. The TRUE signal of the window signal must be FALSE later than TX_EN is FALSE.

Thereafter, the PMA 240 transmits the serial data tx_bit for the received code group data to the optical transmitter 250, and the optical transmitter 250 transmits the corresponding data to the OLT which is the network side optical termination device. At this time, the optical transmitter 250 is an optical transmitter having a burst-mode (BM) transmission function.

Specifically, in Ethernet-PON, the optical transceiver cannot use the continuous-mode (CM) transceiver used in the point-to-point link because several optical subscriber devices share the uplink channel. Therefore, the optical subscriber device uses an optical transmitter having a Burst-mode (BM) transmission function that sends data only at a specific time granted by the OLT, and the OLT uses Burst-mode optical for receiving burst data from the optical subscriber device. You will use a receiver.

An optical subscriber device having an optical transmitter having a burst-mode transmission function transmits a newly defined preamble signal “1010101010” without transmitting an IDLE signal at the clock recovery time of the OLT. Reduce clock recovery time. This has the effect of increasing the overall bandwidth utilization efficiency of the E-PON system.

The drawings and detailed description of the invention are merely exemplary of the invention, which are used for the purpose of illustrating the invention only and are not intended to limit the scope of the invention as defined in the claims or in the claims. Therefore, those skilled in the art will understand that various modifications and equivalent other embodiments are possible from this. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

The optical subscriber device of E-PON and its configuration method according to the present invention transmit a signal pattern in which 0 and 1 alternately as a start signal pattern for clock recovery when burst data is received at the network side optical end device (OLT) receiving end. As a result, the clock recovery time in the network-side optical termination device (OLT) can be reduced, and the efficiency of upstream bandwidth usage of the entire system can be increased.

Claims (11)

In a plurality of optical subscriber devices that transmit data burst at a time allowed by a single network side optical termination device, A medium access control unit for receiving a window signal which is a signal related to whether data transmission is allowed from the outside to the network side optical termination device; According to the state of the received window signal, after generating a start signal pattern for shortening the clock recovery time of the network-side optical termination device as a signal pattern of a predetermined bit alternately 0 and 1, and then transmitted, the network-side optical A transmitter for transmitting burst data to be transmitted to an end device; And An optical transmitter for transmitting the bursted data transmitted from the transmitter only at a time allowed by the network side optical termination device Optical subscriber device comprising a. According to claim 1, Wherein the generated start signal pattern includes a signal pattern of 1010101010 or 0101010101. The method of claim 2, The transmitting unit, When 8-bit parallel data, an enable signal, a transmission error signal, and a transmission clock are received from the medium access control unit, a code group set having control information is generated according to the state of the received signal and the window signal, and then generated. A state controller for transmitting 8-bit parallel data according to the code group set; And The encoder converts the transmitted 8-bit parallel data into 10-bit parallel data and sends the same. Optical subscriber device comprising a. The method of claim 3, wherein And a code group set generated by the state controller includes a / P / code defined as 1010101010 signal pattern /D21.5/. The method of claim 4, wherein And the included / P / code is defined as /D10.2/, which is a signal pattern of 0101010101. According to claim 1, The automatic negotiation unit generates and transmits a signal for controlling on / off of the optical transmitter according to the state of the received window signal, and reconstructs a signal related to the burst data transmission permission and provides the signal to the transmitter. The optical subscriber device further comprises. In the data transmission method of a plurality of optical subscriber device for transmitting data burst at a time allowed by a single network side optical termination device, a) receiving a window signal which is a signal related to whether data transmission is allowed from the outside to the network side optical termination device; b) generating and transmitting a start signal pattern for reducing a clock recovery time of the network side optical termination device as a signal pattern of a predetermined bit in which 0 and 1 alternately according to the state of the received window signal; And c) transmitting the bursted data only at the time allowed by the network-side optical terminator, and transmitting a code group indicating the end of the bursted data to the network-side optical terminator; Data transmission method of the optical subscriber device comprising a. The method of claim 7, wherein Step c) is Generating a code group set having control information according to the state of the received signal and the window signal when 8-bit parallel data and an enable signal, a transmission error signal, and a transmission clock are received; And Converting 8-bit parallel data according to the generated code group set into 10-bit parallel data and transmitting the same Data transmission method of the optical subscriber device comprising a. The method of claim 8, The generated code group set includes a / P / code defined as 1010101010 signal pattern /D21.5/. The method of claim 9, The included / P / code is defined as /D10.2/, which is a signal pattern of 0101010101. A recording medium comprising a data transmission method of a plurality of optical subscriber devices for transmitting data burst at a time allowed by a single network side optical termination device, a) a function of receiving a window signal, which is a signal related to whether data transmission is allowed from the outside to the network side optical termination device; b) a function of generating a start signal pattern for shortening a clock recovery time of the network side optical termination device as a signal pattern of a predetermined bit in which 0s and 1s alternately appear according to the state of the received window signal and transmitting the generated signal; And c) a function of transmitting a code group indicating the end of the transmitted bursted data to the network-side optical termination device after transmitting the bursted data only at the time allowed by the network-side optical termination device; The recording medium in which the program is stored.