CN104796799B - A kind of optical fiber delay cable architecture and method with on-off delay function - Google Patents

Abstract

The invention discloses an optical fiber delay line structure and method with positive and negative delay functions. A common optical fiber delay line structure S1 capable of producing 0 to M unit delays and a common optical fiber delay line capable of producing 0 to N unit delays are combined. The line structure S2 is connected in series to form a new fiber delay line structure S, and S1 and S2 exist as substructures of S, and are under the unified control of the optical switch control module in S. When the optical fiber delay line structure of the present invention is applied to an optical packet switching network, the flexibility of node switching can be increased; when the optical fiber delay line structure of the present invention is applied to an optical burst switching network, the success of node resource reservation can be increased probability.

Description

A fiber delay line structure and method with positive and negative delay functions

technical field

The invention relates to the technical field of optical fiber delay lines, in particular to an optical fiber delay line structure and method with positive and negative delay functions.

Background technique

In the traditional optical network, the working mode of "optical transmission-electrical switching" is adopted, that is, data is transmitted in the form of optical signals in the link, and the optical signals are converted into electrical signals at nodes for switching processing, and then converted For the optical signal to be transmitted in the next link. This exchange method can be abbreviated as O-E-O (Optical-Electronic-Optical) exchange. In recent years, with the development of optical transmission technology, the improvement speed of nodes' processing capabilities in the electrical domain has been unable to keep up with the increase speed of optical link transmission capabilities, resulting in an "electronic bottleneck". In order to solve the electronic bottleneck problem, scholars have proposed a solution called all-optical switching. All-optical switching refers to a switching technology in which signals are directly switched to corresponding output ports in the optical domain without undergoing optical-electrical-optical conversion at intermediate nodes. All-optical switching can be abbreviated as O-O-O (Optical-Optical-Optical) switching. Optical Burst Switching (OBS) and Optical Packet Switching (Optical Packet Switching, OPS) are two typical all-optical switching technologies, both of which adopt the channel access mode of statistical multiplexing. In optical packet switching, data packets are directly converted into optical signals——optical packets, which are the basic unit of transmission and switching in the network. In optical burst switching, multiple data packets are first combined into a long burst, and then converted into an optical signal—optical burst. The basic unit of transmission and switching in the network is an optical burst. For convenience of description, optical packets and optical bursts are collectively referred to as optical packets below.

Since both optical burst switching and optical packet switching adopt the channel access method of statistical multiplexing, when two optical packets compete for the same channel resource at the same time, conflicts between optical packets will occur. If the conflicts cannot be effectively resolved, the cause data loss. In order to avoid data loss, when a collision occurs between two optical packets, one of the optical packets needs to be buffered. There is no buffer like Random Access Memory (RAM) in the optical domain; in order to realize the buffer function of data in the optical domain, an optical fiber delay line is usually used to delay the optical signal for a certain time. The simplest optical fiber delay line structure consists of two branches connected by a 1×2 optical switch. The signal passes through one branch without delay, and the other branch produces a fixed time delay. The specific branch through which the signal passes is determined by the optical switch. control. When a conflict occurs between two optical packets, one of the optical packets can be delayed for a period of time using the fiber delay line structure, and the delayed optical packet can be sent out on the output port after the output link is idle.

The traditional fiber delay line structure can only produce forward delay, and the flexibility is not good enough.

Contents of the invention

In order to solve the deficiencies in the prior art, the present invention provides a fiber delay line structure and method with positive and negative delay functions. In the optical burst switching network and optical packet switching network, in order to better solve the conflict between optical packets problem, one of the optical packets needs to be buffered using a fiber delay line structure. The ordinary fiber delay line structure can only produce positive delay. In order to improve the flexibility of optical packet delay, the present invention proposes a fiber delay line structure with both positive delay and negative delay functions.

Its technical solution is:

An optical fiber delay line structure with positive and negative delay functions, which is composed of an ordinary optical fiber delay line structure S1 capable of generating 0 to M unit delays and an ordinary optical fiber delay line structure S2 capable of generating 0 to N unit delays in series A new fiber delay line structure S, S1 and S2 exist as substructures of S, and are under the unified control of the optical switch control module in S.

A kind of fiber optic delay line method with positive and negative delay function, comprises the following steps:

(1) In the initial state, place S1 in the delay state of M units, place S2 in the delay state of 0 units, and stipulate that this state is the 0 delay state of the new optical fiber delay line structure S;

(2) When it is necessary to generate a delay of +n units for an optical packet, it is only necessary to maintain the state of the substructure S1 in the fiber delay line structure S (that is, the delay state of M units), and set the substructure S2 is placed in the n unit delay state;

(3) When a time delay of -m units needs to be generated for an optical packet, it is only necessary to maintain the state of the substructure S2 unchanged, and place the substructure S1 in a time delay state of M-m units.

Beneficial effects of the present invention: when the optical fiber delay line structure of the present invention is applied to an optical packet switching network, the flexibility of node switching can be increased; when the optical fiber delay line structure of the present invention is applied to an optical burst switching network, it can increase The success probability of a node reserving resources.

Description of drawings

Fig. 1 is a schematic composition diagram of an optical fiber delay line structure with positive and negative delay functions.

Fig. 2 is a schematic diagram of a zero-delay state of an optical fiber delay line structure with positive and negative delay functions. Among them, S1 is an ordinary optical fiber delay line structure with 0 to M unit delay functions; S2 is an ordinary optical fiber delay line structure with 0 to N unit delay functions; S is composed of S1 and S2 in series, and uses a The optical switch control module jointly controls S1 and S2. In the figure, the thick line shows the branch through which the optical signal passes in the 0-delay state of S.

Figure 3 is the +n unit delay states of the fiber delay line structure with positive and negative delay functions. In the figure, the thick line shows the branch that the optical signal passes through in the state of +n unit time delay of S.

Fig. 4 is the -m unit delay states of the fiber delay line structure with positive and negative delay functions. In the figure, the thick line shows the branch that the optical signal passes through in the state of -m unit time delay of S.

Fig. 5 is a schematic diagram of an optical switching node installed with a fiber delay line structure with positive and negative delay functions. In the figure, the switching function of the node for the optical packet is completed by the optical cross-connector, and the optical cross-connector has P signal entrances and P signal exits. Each entrance is connected with an input optical link, and each exit is connected with an output optical link. An optical fiber delay line structure S with positive and negative delay functions is installed at each entrance of the optical cross-connect.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments.

The specific implementation method of the present invention is to connect an ordinary optical fiber delay line structure S1 capable of generating 0 to M unit delays and an ordinary optical fiber delay line structure S2 capable of generating 0 to N unit delays in series to form a new optical fiber delay The line structure S, S1 and S2 exist as substructures of S, and are under the unified control of the optical switch control module in S. Fig. 1 is a schematic diagram of a fiber delay line structure with positive and negative delay functions. It should be noted that the present invention only requires that S1 can generate a delay of 0 to M units, and S2 can generate a delay of 0 to N units, and there is no special requirement for their internal structures to be parallel, series or mixed, but For clarity of description, the working principle of the optical fiber delay line structure with positive and negative delay functions is introduced below by taking the parallel structure as an example.

In the initial state, put S1 in the delay state of M units, put S2 in the delay state of 0 units, and specify this state as the 0 delay state of the new fiber delay line structure S, and the 0 hour of the positive and negative delay structure The delay state is shown in Figure 2; under normal conditions, the fiber delay line structure exists as a part of the input link, and all optical packets pass through the fiber delay line structure.

When it is necessary to generate a delay of +n units for an optical packet B, it is only necessary to maintain the state of the substructure S1 in the fiber delay line structure S (that is, the delay state of M units), and set the substructure S2 to in n unit delay states. All other optical packets pass through S in the 0 delay state of S, resulting in a delay of M units; optical packet B passes through S after S2 switching, resulting in a delay of M+n units; compared to other optical packets , the optical packet B produces a delay of +n units. The +n unit time delay states of S are shown in FIG. 3 .

When a delay of -m units needs to be generated for an optical packet B, only the state of the substructure S2 needs to be maintained, and the substructure S1 is placed in a delay state of M-m units. All other optical packets pass through S in the state of 0 delay of S, resulting in a delay of M units; optical packet B passes through S after S1 switching, resulting in a delay of M-m units; compared to other optical packets, the optical Packet B is equivalent to generating a delay of -m units. The delay state of -m units of S is shown in Fig. 4 .

The scope of application of the present invention is the optical burst switching network and the optical packet switching network, and can produce more obvious effects for the optical burst switching network adopting the bidirectional resource reservation mechanism. Fig. 5 is a schematic structural diagram of an optical switching node installed with an optical fiber delay line structure designed in the present invention. The following two application scenarios are used to introduce the working mode of the present invention applied in the optical burst switching network and the optical packet switching network: one scenario is an optical packet switching network or an optical burst switching network using a one-way resource reservation protocol; the other One scenario is an optical burst switching network using a bidirectional resource reservation protocol.

In the first scenario, when an optical packet is transmitted on an optical path, channel resources on multiple links used are not correlated. At a node, conflicts arise when optical packets from two ingress need to use the same egress link at the same time. At this time, the fiber delay line structure S at one of the entrances can be adjusted to delay the corresponding optical packet. The ordinary fiber delay line structure can only carry out forward delay to the optical packet, if the channel is still occupied after the forward delay, it will cause data loss. If the optical fiber delay line structure with positive and negative delay functions is used, when the conflict cannot be resolved after the positive delay, the optical packet can also be negatively delayed, so that the conflict can be resolved more flexibly and the data discarding rate can be reduced.

In the second scenario, before the optical packet is transmitted on the optical path, the control packet is used to reserve resources for the optical packet on each link in advance, and there is a fixed correspondence between the reserved resources on all links. When a conflict occurs on a link, although the ordinary fiber delay line structure can solve the conflict problem on the current link, it will cause the resources reserved on the subsequent link to be unavailable; With the fiber delay line structure, after a positive delay is performed at one node, a corresponding negative delay can be performed at the next node, so that the channel resources used by the optical packet are corrected back to the original time. Therefore, the fiber delay line structure with positive and negative delay functions can play a greater role in resolving conflicts.

The above is only a preferred specific embodiment of the present invention, and the scope of protection of the present invention is not limited thereto. Any person familiar with the technical field within the technical scope disclosed in the present invention can obviously obtain the simplicity of the technical solution. Changes or equivalent replacements all fall within the protection scope of the present invention.

Claims (1)

1. A fiber delay line structure with positive and negative delay functions, characterized in that a common fiber delay line structure S1 that can produce 0 to M unit delays and a common fiber delay that can produce 0 to N unit delays The line structure S2 is connected in series to form a new fiber delay line structure S, and S1 and S2 exist as substructures of S, which are under the unified control of the optical switch control module in S; The method for realizing the positive and negative delay of the optical fiber delay line comprises the following steps: (1) In the initial state, put S1 in the delay state of M units, place S2 in the delay state of 0 units, and stipulate that this state is the 0 delay state of the new fiber delay line structure S; (2) When it is necessary to generate a delay of +n units to an optical packet, it is only necessary to maintain the state of the substructure S1 in the fiber delay line structure S, and place the substructure S2 in a delay state of n units; (3) When a delay of -m units needs to be generated for an optical packet, it is only necessary to maintain the state of the substructure S2 unchanged, and place the substructure S1 in a delay state of M-m units.