CN1997238B - TDMA passive optical network OLT system for broadcast service - Google Patents

Abstract

There is provided a TDMA (time division multiple access) PON (passive optical network chromium) OLT (optical line terminal) system for broadcasting service, comprising: a packet processor determining information according to a frame type (unicast, multicast, and broadcast frames) and a switch output port using header information (an IP address of a packet header, a MAC (multiple access control) address of an ethernet frame, etc.) of data received from an external node or an ONT (optical network terminal) and attaching the information to a header portion of the frame to generate second data; the switch copies the second data for a preset number of times according to the transmission mode and transmits the second data to the corresponding destination output port according to the identification code; m TDMA PON MAC processors, remove the identification code added to the second data and change the second data into TDMA PON frame; and M optical transceivers converting the TDMA PON frame into an optical signal and transmitting the optical signal to the ONTs.

Description

Time Division Multiple Access Passive Optical Network Optical Line Termination System for Broadcasting Service

Cross References to Related Applications

This application claims Korean Patent Application No. 10-2005-0121026 filed with the Korean Intellectual Property Office on December 9, 2005, and Korean Patent Application No. 10-2006 filed with the Korean Intellectual Property Office on March 30, 2006 - Priority of 0029083, the content of which is hereby incorporated by reference.

technical field

The present invention relates to a system for broadcasting services in a Passive Optical Network (PON) system, and more particularly to a Time Division Multiple Access (TDMA) PON Optical Line Terminal (OLT) capable of simultaneous broadcasting and communication services over a single optical cable system.

Background technique

Network enterprises have made substantial investments in Triple Service (TPS) capable of handling broadcast, voice, and data in one network.

More downstream bandwidth is required for an Optical Network Terminal (ONT) in an OLT in order to provide users with broadcasting services such as Internet Protocol Television (IPTV) using a Fiber-to-the-Home (FTTH) network.

In an ultra-high-speed Internet network, the downlink traffic is larger than the uplink traffic. Therefore, if a broadcast service is additionally provided, the ratio of downlink traffic to uplink traffic is severely asymmetric.

However, in the Gigabit PON (GPON) system recommended in ITU-T G.984.1~2, the ratio of downstream traffic to upstream traffic can be in the range between 1:1 and 1:4. In the case of an Ethernet PON (EPON) system standardized in IEEE 802.3ah, the ratio of downstream traffic to upstream traffic is 1:1.

Therefore, in the current TDMA PON system and the current network structure, the network efficiency is reduced due to the severe asymmetry of the upstream and downstream speeds foreseen. This increases the overhead of the OLT equipment.

The multicast method used in TDMA-PON to solve this problem delays channel change, thus causing user inconvenience. Furthermore, the broadcasting method using additional wavelength division multiplexing requires expensive optical transceivers and expensive optical amplifiers to provide only broadcasting signals.

Contents of the invention

The present invention provides a Time Division Multiple Access (TDMA) Passive Optical Network (PON) Optical Line Terminal (OLT) system for broadcasting services.

According to one aspect of the present invention, a transmitter of a TDMA PON OLT system for broadcasting is provided, including: a packet processor, which determines whether to use the first data as broadcast, multicast, or unicast based on the header of the first data And receive, and add the identification code that is used to determine the output port to generate the second data; The switch copies the second data for a predetermined number of times and transmits the second data to the corresponding output port according to the identification code; M TDMA PON MAC processors, removing the identification code added to the second data and converting the second data into a TDMA PON frame; and M optical transceivers, converting the TDMA PON frame into an optical signal and transmitting the optical signal to the ONT.

According to another aspect of the present invention, a kind of receiver of the TDMA PON OLT system that is used for broadcasting service is provided, comprising: M optical receivers, receive the optical signal with burst mode characteristic, this optical signal is transmitted from ONT and extract data from the optical signal; M TDMA PON MAC processors, recovering TDMA PON frames from the extracted data; switches, multiplexing the recovered TDMA PON frames; and packet processors, recovering TDMA PON frames from the multiplexed frames One of Ethernet frame data and packet data is recovered.

Description of drawings

The above and other features of the present invention will become more apparent by describing in detail exemplary embodiments of the present invention with reference to the accompanying drawings, in which:

FIG. 1 is a view illustrating a method of transmitting a frame in an existing TDMA PON OLT system; and

FIG. 2 is a view illustrating a configuration of a TDMA PONOLT system for providing a broadcast service such as IPTV according to the present invention.

Detailed ways

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a view illustrating a method of transmitting a frame in an existing Time Division Multiple Access (TDMA) Passive Optical Network (PON) Optical Line Terminal (OLT) system.

Among methods of transmitting data to users using a fiber-to-the-home (FTTH) network, TDMA PON technologies such as Ethernet PON (EPON) and Gigabit PON (GPON) are standardized. During the downlink transmission of data signals from the OLT to the Optical Network Terminal (ONT), TDMA PON uses continuous mode transmission technology as the existing optical transmission technology. However, during the upstream transmission of data signals from ONT to OLT, TDMA PON uses a burst mode transmission technique to transmit packet data received from each ONT.

Downstream traffic transmitted from OLT 100 to ONT 120 to ONT 130 will now be described. The packet processor 101 of the OLT 100 processes data of the L3 to L7 layers received from an external node or from the ONT 120 to the ONT 130, and transfers the processed frame to TDMA PON Media Access Control (MAC) processors 102 and 104.

In the case where a packet processor with data processing performance A is connected to a TDMA PON MAC processor with a link speed of A/m, M TDMA PON MAC processors 102 and 104 are multiplexed and connected to each other to reduce the number of elements. TDMA PON MAC processors 102 and 104 transmit TDMA PON frames with Logical Link Identifier (LLID) or Optical Network Unit (ONU) ID to optical transceivers 103 and 105 according to the standard proposal of GPON and EPON.

The optical transceivers 103 and 105 convert electrical signals into optical signals, and transmit the optical signals to the splitter 140 through optical lines according to standard recommendations. The splitter 140 splits each optical signal into k optical signals within the splitting range according to standard recommendations, and transmits the k optical signals to the ONT 120 to the ONT 130.

Optical transceivers 121 to 131 of ONT 120 to ONT 130 convert optical signals into electrical signals, and transmit the electrical signals to TDMA PON MAC processors 122 to 132. TDMA PON MAC processors 122 to 132 extract data from electrical signals to recover TDMA PON frames transmitted from OLT 100.

The TDMA PON MAC processors 122 to 132 transform the recovered TDMA PON frames into Ethernet frames and transmit the Ethernet frames to the bridges 123 to 133 according to the standard recommendations of GPON and EPON. The bridges 123 to 133 transmit the Ethernet frames to the destination user equipment.

Upstream signals sent from ONTs 120 to 130 to OLT 100 will now be described. Bridges 123 to 133 of ONTs 120 to 130 transfer Ethernet frames received from user equipment to TDMA PON MAC processors 122 to 132.

TDMA PON MAC processors 122 to 132 transform Ethernet frames into TDMA PON frames, and transmit TDMA PON frames to optical transceivers only when frames are allowed to be transmitted to TDMA PON MAC processors 122 to 132 under the control of OLT 100 121 to 131.

The optical transceivers 121 to 131 convert electrical signals into optical signals, and transmit the optical signals only when frame transmission is allowed, and intercept the optical signals when frame transmission is not allowed, so as to prevent signal interference in the ONTs 120 to 130. Such a signaling method is called burst mode.

The splitter 140 multiplexes the signals received from the k ONTs, and transmits the multiplexed signal to the optical transceiver 103 of the OLT 100 .

The optical transceiver 103 extracts data from the optical signal transmitted in burst mode, and transmits the extracted data to the TDMA PON MAC processor 102.

The TDMA PON MAC processor 102 processes frames according to standard recommendations and transfers the processed frames to the packet processor 101. The packet processor 101 processes packets transferred from the maximum number of M TDMA PON MAC processors 102 and TDMA PON MAC processors 104, and transfers the processed packets to an uplink or a destination port of the PON.

Compared with the existing network, more downlink bandwidth is needed to use the FTTH network to provide users with broadcast services such as IPTV. In the ultra-high-speed Internet, the downstream traffic is heavier than the upstream traffic. If broadcasting services are additionally provided, the ratio of downstream traffic to upstream traffic is increasingly asymmetric. In an asymmetrical TDMA PON system, network resources cannot be used efficiently due to asymmetrical traffic characteristics. As a result, equipment and facility costs are increased.

In the existing TDMA PON system, due to the limitation of the bandwidth, the broadcast frames that require a lot of bandwidth are not transmitted to all PON users. However, the IPTV broadcasting service is provided to all PON users by multicasting using the Internet Group Management Protocol (IGMP), or broadcasting using a wavelength division multiplexing method using a wavelength separated from a data communication signal.

Multicasting may cause user inconvenience due to channel change delay. The broadcasting method using the wavelength division multiplexing method additionally requires an expensive optical receiver and an expensive optical amplifier only for broadcasting signals, thus increasing the overhead for constructing the existing TDMA PON system.

FIG. 2 is a view illustrating a configuration of a TDMAPON OLT system for providing a broadcast service such as IPTV according to an embodiment of the present invention.

The TDMA PON OLT system according to this embodiment includes a packet processor 201, a switch 202, TDMA PON MAC processors 203 and 205, and optical transceivers 204 and 206. In the TDMA PON OLT system, the transmission mode is classified into downlink transmission from OLT to ONT and uplink transmission from ONT to OLT.

The grouping processor 201 of OLT 200 processes the data of L3 to L7 layer from ONT 220 to 230 or from external node reception in the downstream direction, produces the internal frame that comprises the information of relevant purpose TDMA PON port and frame identification, and this internal frame sent to switch 202.

The packet processor 201 recovers frames from the data received by the maximum number of M TDMA PON MAC processors 203 and 205 in the upstream direction, and transmits these frames to the uplink or TDMA PON port.

The switch 202 of the OLT 200 is connected to a maximum number of M TDMA PON MAC processors, receives traffic frames with a bandwidth of the maximum amount A from the packet processor 201 in the downlink direction, and classifies the frames into broadcast, multicast, and unicast frames, copy broadcast frames and send them to all m TDMAPON MAC processors, send unicast frames to destination TDMA PON MAC processors, and copy multicast frames and send them to the designated destination Ground TDMA PON MAC processor.

The switch 202 multiplexes frames received from the maximum number m of TDMA PON MAC processors in the upstream direction and transfers the multiplexed frames to the packet processor 201 having the maximum packet processing performance A.

Here, M represents the number of TDMA PON MAC processors that can be connected to the packet processor through the switch, and is determined by the user by measuring the upstream traffic volume received from the TDMA PON MAC processor. If the user does not allow any frames to be lost or damaged, the transmission speed of the uplink data of M TDMA PON MAC processors can be measured such that the maximum link speed (A) in the downlink direction is divided by the maximum transmission speed to determine the value resulting from the division As M.

However, if the user allows the loss of some low-level frames, the data transfer speed can be reduced. Therefore, the value of m can be increased to connect more TDMA PON MAC processors to the packet processor 201.

TDMA PON MAC processors 203 and 205 receive frames from switch 202 in the downstream direction, process MAC functions for TDMA PON downstream signals, and transmit frames to optical transceivers 204 and 206.

TDMA PON MAC processors 203 and 205 receive signals from optical transceivers 204 and 206 in the upstream direction, process MAC functions for TDMA PON upstream signals, and transmit signals to switch 202.

The optical transceivers 204 and 206 of the OLT 200 receive frames from the TDMA PON MAC processors 203 and 204 in the downstream direction, convert the electrical signals into optical signals with speed A/n, and transmit the optical signals to the splitter 240. Here, n represents the ratio of the downlink speed to the uplink speed.

Since EPON has 1G speed in the downstream direction and 1G speed in the upstream direction, n=1. In the case of GPON with 2.5G speed in the downstream direction and 1.25G speed in the upstream direction, n=2. During conversion into an optical signal, the power of the number k branches of the splitter must be properly adjusted.

Optical transceivers 204 and 206 of OLT 200 extract data from optical signals transmitted in bursts in the upstream direction, and transmit the extracted data to TDMA PON MAC processors 203 and 205. TDMAPON MAC processors 203 and 205 process frames according to standard recommendations and pass the processed frames to switch 202.

The splitter 240 splits the optical signal having the transmission speed A in the downstream direction and transmits the split signal to the ONTs 220 to 230. k represents the number of branches of the splitter 240 . Splitter 240 multiplexes the optical signals received from ONTs 220-230 in the upstream direction and transmits the multiplexed optical signals to optical transceivers 204 and 206 of OLT 200.

ONTs 220 to 230 include optical transceivers 221 and 231, TDMA PON MAC processors 222 and 232, and bridges 223 and 233, respectively. Optical transceivers 221 and 231 convert optical signals into electrical signals and transmit the electrical signals to TDMA PON MAC processors 222 and 232.

Optical transceivers 204 and 206 convert electrical signals to optical signals in the upstream direction, transmit optical signals only when frames are allowed to be transmitted, and intercept optical signals to prevent signal interference in ONTs 220-230.

The TDMA PON MAC processors 222 and 232 recover the TDMA PON frames received from the OLT 200 in the downstream direction, convert only the TDMA PON frames transmitted to the TDMA PON MAC processors 222 and 232 into Ethernet frames, and transmit the Ethernet frames to the bridge Devices 223 and 233. The TDMA PON MAC processors 222 and 232 convert the Ethernet frames into TDMA PON frames and transmit the TDMA PON frames to the optical transceivers 221 and 231 only when the OLT 200 allows transmission of frames to it.

The bridges 223 and 233 process the frame in the downstream direction and transmit the frame to the destination user equipment according to the destination address of the Ethernet header. The bridges 223 and 233 transfer frames received from the destination user equipment, that is, frames to be transmitted to the OLT 200, to the TDMA PON MAC processors 222 and 232.

As described above, in the TDMA PON OLT system according to the present invention, broadcasting services such as IPTV can be effectively broadcasted using a TDMA PON-based FTTH network.

Therefore, it is possible to reduce the time delay for switching channels caused by providing broadcast services such as IPTV in the existing TDMA PON OLT system.

Moreover, the uplink and downlink transmission speeds can be set asymmetrically in the TDMA PON-based FTTH network. Therefore, a maximum number of users can be accommodated. As a result, network resources can be efficiently utilized to efficiently and economically provide IPTV services in TDMA PON based FTTH networks.

While the invention has been particularly shown and described with reference to the exemplary embodiments, it should be understood by those skilled in the art that changes may be made in form and without departing from the spirit and scope of the invention as defined by the appended claims. Various changes were made in the details.

Claims (7)

1. A transmitter of a TDMA (Time Division Multiple Access) PON (Passive Optical Network) OLT (Optical Line Terminal) system, which includes a larger amount of The downlink data transmitted from OLT to ONT, the transmitter includes: a packet processor, using header information of data received from an external node or ONT to determine information about a frame type and a switch output port, and appending the information to the header portion of the frame to generate an internal frame, wherein the data's The header information includes the IP address of the packet header and the MAC (media access control) address of the Ethernet frame, and the frame type is unicast, multicast, and broadcast frame; a switch, classifying the frame type and the switch output port based on the identification information of the frame received from the packet processor, duplicating the broadcast frame and sending it to all M TDMA PONMAC processors, duplicating the multicast frame and Transmit it to the corresponding switch output port, and only transmit the unicast frame to the corresponding destination output port; M TDMA PON MAC processors, receive the internal frame from the switch, and remove the frame type and switch output port appended to the frame header in order to transform the internal frame into a TDMA PON frame information; and M optical transceivers convert the TDMA PON frames output from the M TDMA PON MAC processors into optical signals and transmit the optical signals to the ONT. 2. A receiver for a TDMA PON OLT system, the system includes a larger amount of downstream data transmitted from the OLT to the ONT than the upstream data transmitted from the ONT to the OLT, the receiver comprising: M optical transceivers extracting data from optical signals transmitted in burst mode in TDMA PON; M TDMA PON MAC processors recover TDMA PON frames from the extracted data; a switch that multiplexes said frames received from said M TDMA PON MAC processors and transmits the multiplexed frames to a packet processor; and A packet processor recovers Ethernet frames or packets from the multiplexed frames and processes them. 3. An optical transceiver for a TDMA PON OLT system for broadcasting services, comprising: a packet processor determining whether to receive the first data as broadcast, multicast, or unicast based on a header of the first data, and adding an identification code for determining an output port to generate second data; The switch copies the second data for a predetermined number of times and transmits the second data to the corresponding output port according to the identification code; M TDMA PON MAC processors, removing the identification code added to the second data and transforming the second data into a TDMA PON frame; and M optical transceivers convert the TDMA PON frame into an optical signal and transmit the optical signal to the ONT. 4. The optical transceiver of claim 3, wherein the first data is one of packet data and Ethernet frame data. 5. The optical transceiver of claim 3, wherein the packet processor adds the identification code to a reserved header of the first data. 6. The optical transceiver of claim 3, wherein said switch replicates data broadcast by a number M of TDMA PON MAC processors, and replicates data broadcast by a plurality of TDMA PON MAC processors to which data is to be transmitted. broadcast data. 7. An optical receiver for a TDMA PON OLT system for broadcasting services, comprising: M optical receivers, receiving an optical signal having a burst mode characteristic, the optical signal being sent from the ONT, and extracting data from the optical signal; M TDMA PON MAC processors recover TDMA PON frames from the extracted data; a switch that multiplexes the recovered TDMAPON frames; and A packet processor recovers one of Ethernet frame data and packet data from the multiplexed frame.

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