CN113099328A - Resource allocation method of multi-core elastic optical network based on node and crosstalk perception - Google Patents

Resource allocation method of multi-core elastic optical network based on node and crosstalk perception Download PDF

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CN113099328A
CN113099328A CN202110372772.8A CN202110372772A CN113099328A CN 113099328 A CN113099328 A CN 113099328A CN 202110372772 A CN202110372772 A CN 202110372772A CN 113099328 A CN113099328 A CN 113099328A
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frequency
service request
path
core
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CN113099328B (en
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刘焕淋
胡会霞
陈勇
胡俊岭
唐畅
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Chongqing University of Post and Telecommunications
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
    • H04Q11/0062—Network aspects
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
    • H04Q11/0005—Switch and router aspects
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
    • H04Q11/0062—Network aspects
    • H04Q2011/0086—Network resource allocation, dimensioning or optimisation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
    • H04Q11/0062—Network aspects
    • H04Q2011/009—Topology aspects

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Abstract

The invention relates to a resource allocation method of a multi-core elastic optical network based on node and crosstalk perception, and belongs to the technical field of optical fiber communication. The method of the invention firstly determines the importance of the nodes according to the intermediate centrality of the nodes, and arranges the nodes in a descending order according to the importance of the nodes, and configures the limited spectrum converters for the ordered optical network nodes according to a certain proportion value of the number of the optical network nodes; in the routing selection stage of the service request, designing a path weight calculation method considering the path load and the use proportion of a limited spectrum converter in the path, and sequencing the candidate paths in an ascending order; in the fiber core frequency spectrum distribution stage, a fiber core grouping and frequency spectrum partitioning method is adopted, and a fiber core frequency spectrum selection method considering the compactness of a frequency spectrum interval and the number of overlapping frequency gaps of the frequency spectrum interval is designed, so that the crosstalk value between fiber cores is reduced; for the service request with failed spectrum allocation, the available spectrum block is searched for the service request again through the limited spectrum converter, and the probability of successful transmission of the service is improved.

Description

Resource allocation method of multi-core elastic optical network based on node and crosstalk perception
Technical Field
The invention belongs to the technical field of optical fiber communication, and relates to a resource allocation method of a multi-core elastic optical network based on node and crosstalk sensing.
Background
With the rapid development of internet services, the consumption of network bandwidth resources is increasing, and optical networks are favored by operators due to the advantages of large transmission capacity, long transmission distance, and the like. The traditional wavelength division multiplexing network adopts fixed spectrum granularity and a single modulation format, and can not meet flexible and variable service requests. Elastic Optical Networks (EONs) based on Optical orthogonal frequency division multiplexing technology can flexibly allocate spectrum granularity and adaptively select modulation formats, and have attracted extensive attention and research in recent years. With increasing traffic demands, the EONs using single-core optical fibers cannot meet the transmission demands of services, and Space Division Multiplexing (SDM) technology uses multi-core optical fibers to expand the capacity of the optical fibers from a physical structure, which is an effective means for overcoming the capacity bottleneck of the optical fibers at present. The multi-core optical fiber elastic optical network combines the advantages of the space division multiplexing technology and the elastic optical network, and has the advantages of flexible spectrum allocation mode, large transmission capacity, high resource utilization rate and the like.
In the multi-core elastic optical network, service request allocation must meet three constraint conditions of spectrum allocation, so that flexibility of service request allocation is reduced. In order to alleviate the influence of the spectrum constraint condition on the service request allocation, relevant devices can be configured in the nodes of the multi-core elastic optical network. The node is provided with a limited spectrum converter, so that the consistency constraint during spectrum allocation can be relaxed, and a service request which is failed in allocation can be converted into other frequency slots of the same fiber core within the spectrum conversion range, so that the probability of successful transmission of the service request is improved, and the influence of crosstalk between the cores on the service request is optimized to a certain extent. However, the additional cost of having spectrum conversion capability at all nodes in the network is balanced with the improved blocking rate of the fully configured network, and the limited spectrum converters are not cost-effective to fully configure in the network. Therefore, the cost for configuring the optical devices can be reduced by adopting sparse configuration, and if the sparse configuration is adopted, the selection of the nodes of the network is a difficult problem. The existing method for measuring the node importance is either directly sorted according to the node degrees or sorted according to the node load, the former has the phenomenon that the edge node degrees can also be higher, which is not objective enough, and the latter can judge when a service request is transmitted in a network, and is not suitable for the device configuration of the node. In the multi-Core elastic optical network, Inter-Core Crosstalk (ICXT) is inevitably generated between cores, that is, frequency gap overlapping occurs in a service request during transmission, so that optical signal power leaks into adjacent cores, and the quality of service transmission is affected. In summary, it is important to reasonably select the nodes configured with the finite spectrum converters to reduce the cost and to more reasonably allocate resources to the nodes during traffic transmission to reduce the influence of crosstalk between the cores on resource allocation.
Disclosure of Invention
In view of this, an object of the present invention is to provide a resource allocation method for a multi-core elastic optical network based on node and crosstalk sensing, in which a limited spectrum converter is configured at a network node to relax spectrum consistency constraints, and in a spectrum allocation stage, the spectrum utilization rate is improved by considering the influence of crosstalk.
In order to achieve the purpose, the invention provides the following technical scheme:
a multi-core elastic optical network resource allocation method based on node and crosstalk perception comprises the following steps:
s1: calculating the intermediary centrality of each node in the network topology according to a node intermediary centrality formula, arranging the nodes in the network in a descending order according to the calculated intermediary centrality value, and selecting a certain number of nodes to configure a finite spectrum converter;
s2: selecting K candidate paths in a multi-core elastic optical network by using a shortest path method according to a service request, wherein the value of K is a maximum integer value taken upwards from the average degree of nodes of a network topology, calculating the weight value of each candidate path according to a path weight formula, and arranging the candidate paths in a set P in an ascending order according to the size of the path weight value;
the calculation formula of the path weight value is as follows:
Figure BDA0003009936560000021
in the path weight formula, α1、α2For the weight coefficient, respectively representing the path load and the finite spectrum converter pair configured in the pathInfluence of candidate Path, wherein1+α2＝1，hopkHop count, W, for the kth candidate pathLiThe weighted value of the ith link in the candidate path k, RC and RC are the number of available finite spectrum converters and the total number of finite spectrum converters at the node, respectively.
S3: performing fiber core frequency spectrum allocation for the service request in the path set P, designing a frequency spectrum allocation weight formula, calculating frequency spectrum allocation weight values when the service request is allocated in different frequency spectrum intervals, and selecting an allocation mode with the minimum frequency spectrum allocation weight value to allocate a fiber core and a frequency spectrum block for the service request;
s4: and calculating the crosstalk value between cores when the service request is transmitted, and reducing the crosstalk by a frequency spectrum conversion method if the crosstalk value does not meet the crosstalk threshold condition.
Further, the S1 is specifically implemented by the following steps:
s101: according to a node intermediary centrality calculation formula, carrying out descending order arrangement on each node in the network topology, wherein the larger the intermediary centrality value of the node is, the more important the node is;
the calculation formula of the node intermediary centrality is as follows:
Figure BDA0003009936560000022
in this formula, V is the set of nodes in the network, pi(s, t) represents the number of shortest paths passing through an intermediate node i, wherein, | V | represents the number of nodes in the network, and 0.5(| V | -1) × (| V | -2) represents the total number of shortest-length paths in the network if one shortest-length path is selected between any node pair in the network except the node i.
S102: determining the proportion theta of the nodes configured with the limited spectrum converter in the network according to the number of the nodes and the links in the network, wherein the value range is
Figure BDA0003009936560000031
L is the number of links in the network,
Figure BDA0003009936560000032
is an upward integer value;
s103: and selecting | V | multiplied by theta nodes according to the node sorting result of S101, and sequentially configuring the finite spectrum converters for the nodes.
Further, the S3 is specifically implemented by the following steps:
s301: grouping fiber cores according to the idea of vertex coloring, dividing non-adjacent fiber cores into a group, partitioning a frequency spectrum to further reduce the influence of crosstalk between the cores, wherein the partition number is related to the grouping number of the fiber cores, when the grouping number of the fiber cores is an odd number, the partition number is the fiber core grouping number plus 1, when the grouping number of the fiber cores is an even number, the partition number is equal to the fiber core grouping number, and the frequency gap number of each partition is obtained by a section frequency gap calculation formula;
wherein, the interval frequency gap calculation formula is as follows:
Figure BDA0003009936560000033
in the formula, firstly, service requests with the same maximum factor are aggregated into a group according to the size of the frequency slot number required by the service request bandwidth, m and n are respectively the number of types of the ith group of service requests and the total number of types of the service requests, RxAnd RijThe number of frequency slots, P, required by the xth service request and the ith group of the jth service request respectivelyxAnd PijThe ratio of the xth service request and the ith group jth service request to the total service request is respectively, S is the total number of frequency slots in the fiber core, and the subscript min FS indicates that the number of frequency slots allocated to the group i must be a multiple of the number of frequency slots required by the minimum service request bandwidth in the group i.
S302: calculating the maximum factor of the frequency slot number required by the service request, selecting a proper frequency spectrum interval for distributing frequency spectrum resources for the service request, if the service request is distributed in an odd interval, adopting a first matching criterion to distribute the frequency spectrum resources, namely searching available frequency spectrum blocks from the frequency slots with low index values, and if the service request is distributed in an even interval, adopting a last matching criterion to distribute the frequency spectrum resources, namely searching the available frequency spectrum blocks from the frequency slots with high index values;
s303: if the service request has no available frequency spectrum resources in the frequency spectrum interval with the maximum factor, checking whether the frequency gap number required by the service request has the same factor as the frequency gap number required by other groups of service requests, if so, allocating the service request to the corresponding frequency spectrum interval, allocating a proper frequency spectrum block for the service request according to a service allocation rule, if not, searching an idle frequency spectrum block with the maximum frequency spectrum allocation weighted value in all other frequency spectrum intervals according to a frequency spectrum allocation weight formula to transmit the service request, and recording a candidate path where the frequency spectrum block is located and a fiber core serial number.
The calculation formula of the spectrum allocation weight is as follows:
Figure BDA0003009936560000041
in the calculation formula of the spectrum allocation weight,
Figure BDA0003009936560000042
to select the weight values for spectral blocks in the core c interval s of the candidate path k,
Figure BDA0003009936560000043
the spectral compactness of the core c interval s of the candidate path k,
Figure BDA0003009936560000044
for selecting a spectral block in the interval s of cores c of the candidate path k, the number of frequency slots in which the adjacent core c' overlaps the selected spectral block, wherein,
Figure BDA0003009936560000045
Figure BDA0003009936560000046
and
Figure BDA0003009936560000047
respectively represent the core c regions in the candidate path kThe maximum occupied frequency slot index value and the minimum occupied frequency slot index value of s,
Figure BDA0003009936560000048
the state of the ith frequency slot in the segment s of the fiber core c representing the candidate path k occupies 0, otherwise it is 1,
Figure BDA0003009936560000049
represents the frequency slot number contained in the jth idle spectrum block in the core c interval s of the candidate path k,
Figure BDA00030099365600000410
the number of free spectral blocks in the core c interval s of the candidate path k,
Figure BDA00030099365600000411
fs、ferespectively a starting frequency slot index value and an ending frequency slot index value, P, of the selected spectrum blockcoreTo select a set of adjacent cores of the core,
Figure BDA00030099365600000412
and
Figure BDA00030099365600000413
respectively represents the occupation states of the jth frequency slot in the fiber core c and the fiber core c' adjacent to the fiber core c, wherein the occupation state is 0, and otherwise, the occupation state is 1.
Further, the S4 is specifically implemented by the following steps:
s401: calculating an inter-core crosstalk value during service request transmission according to an inter-core crosstalk calculation formula, if the value is smaller than a threshold range of crosstalk tolerance, allocating the frequency spectrum block to the service request, and otherwise, checking whether a node capable of performing frequency spectrum conversion exists in a candidate path of the service request;
wherein, the calculation formula of the crosstalk between the cores is as follows:
XTc＝∑XTcc′
in the intercore crosstalk calculation formula, XTcc′Is the value of the crosstalk between the core c and its neighboring core c
Figure BDA00030099365600000414
L is the optical fiber transmission length, h represents the incremental crosstalk per unit transmission length,
Figure BDA00030099365600000415
wherein, alpha, r, beta, omegathRespectively representing the coupling coefficient, bend radius, propagation constant and core pitch.
S402: if the candidate path has a node capable of performing spectrum conversion, judging whether a spectrum block meeting the bandwidth requirement of the service request exists in the spectrum conversion range of the transmission fiber core, if so, preferentially selecting a spectrum block with a few frequency gaps overlapped with the adjacent fiber core for the service request, and recording the candidate path and the fiber core serial number of the spectrum block, otherwise, searching a proper spectrum block for the service request by adopting the method S3 in the next candidate path, and recording the candidate path and the fiber core serial number of the spectrum block.
The invention has the beneficial effects that: the invention provides a resource allocation method of a multi-core elastic optical network based on node and crosstalk perception. Firstly, in order to reduce the cost of network devices, the nodes in the network are arranged in a descending order according to a mediation centrality formula of the nodes, and a certain number of nodes are selected from the network to configure a limited spectrum converter, so that the constraint of consistency in the spectrum allocation process can be relaxed; secondly, in a routing stage, searching K candidate paths for the service request according to a K shortest path algorithm, and then designing a path weight calculation method considering the path load and the use proportion of the finite spectrum converters in the paths to arrange the candidate paths in an ascending order; thirdly, in the fiber core frequency spectrum distribution stage, a fiber core grouping and frequency spectrum partitioning method is adopted, and a fiber core frequency spectrum selection method considering the compactness of the frequency spectrum interval and the number of overlapped frequency gaps of the frequency spectrum interval is designed to reduce the influence of crosstalk; and finally, for the service request with failed spectrum allocation, the service request is optimized through a limited spectrum converter, so that the probability of successful transmission of the service request is improved. According to the invention, firstly, the limited spectrum converter is sparsely configured in the network to relax the constraint of spectrum consistency, secondly, in the spectrum allocation stage, a fiber core grouping and spectrum partitioning strategy is adopted, and when spectrum resources are selected for a service request, a spectrum block with small crosstalk influence is preferentially selected for transmission, so that the probability of service request blocking is reduced.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the means of the instrumentalities and combinations particularly pointed out hereinafter.
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In order to make the object, technical scheme and beneficial effect of the invention more clear, the invention provides the following drawings for explanation:
FIG. 1 is a flow chart of a multi-core elastic optical network resource allocation method;
FIG. 2 is an exemplary diagram of a path selection;
FIG. 3 is a schematic diagram of core grouping and spectral zoning;
fig. 4 is a diagram of an example of spectrum selection.
Detailed Description
Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
Fig. 1 is a flowchart of a resource allocation method for a multi-core elastic optical network, which will be described in detail below:
step 1: counting available resources of the network, initializing a candidate path set P phi, sequencing nodes in the network according to an intermediary centrality value calculated by the formula (1), selecting | V | multiplied by theta nodes according to a given value range of theta, and configuring a finite spectrum converter for the nodes in sequence, wherein,
Figure BDA0003009936560000061
l is the number of links in the network,
Figure BDA0003009936560000062
is an upward integer value;
Figure BDA0003009936560000063
in formula (1), V is a node set in the network, pi(s, t) represents the number of shortest paths passing through an intermediate node i, wherein, | V | represents the number of nodes in the network, and 0.5(| V | -1) × (| V | -2) represents the total number of shortest-length paths in the network if one shortest-length path is selected between any node pair in the network except the node i.
Step 2: grouping fiber cores according to a vertex coloring principle, and carrying out partition processing on a frequency spectrum according to the given service request number and the occupied proportion, wherein the size of a frequency spectrum interval is calculated by a formula (2);
Figure BDA0003009936560000064
in the formula (2), m and n are the number of kinds of the ith group service request and the total number of kinds of the service request respectively, RxAnd RijThe number of frequency slots, P, required by the xth service request and the ith group of the jth service request respectivelyxAnd PijThe ratio of the xth service request and the ith group jth service request to the total service request is respectively, S is the total number of frequency slots in the fiber core, and the subscript min FS indicates that the number of frequency slots allocated to the group i must be a multiple of the number of frequency slots required by the minimum service request bandwidth in the group i.
And step 3: searching K candidate paths for the service request according to a shortest path algorithm, and determining the modulation level of the service request and the frequency slot number required by the service request according to the path length;
and 4, step 4: calculating the weight value of each candidate path according to a formula (3), and arranging the candidate paths in the set P in an ascending order according to the weight value of the paths, wherein a path sequence number k is 1;
Figure BDA0003009936560000065
in the formula (3), α1、α2The weight coefficients represent the influence of the path load and the finite spectrum converter arranged in the path on the candidate path respectively, wherein alpha1+α2＝1，hopkThe hop count for the kth candidate path,
Figure BDA0003009936560000066
the weighted value of the ith link in the candidate path k, RC and RC are the number of available finite spectrum converters and the total number of finite spectrum converters at the node, respectively.
And 5: searching all available spectrum blocks in the candidate path k according to the size of the spectrum block required by the service request, judging whether the service request has the available spectrum blocks in the fiber core interval, if so, turning to the step 6, otherwise, turning to the step 8;
step 6: according to the spectrum allocation rule of the spectrum interval, if the service request is allocated in the odd interval, adopting a first matching rule to allocate spectrum resources, and if the service request is allocated in the even interval, adopting a last matching rule to allocate spectrum resources;
and 7: according to equation (4), the crosstalk value XT between cores when the service requests to select the spectrum block in the spectrum interval is calculatedcJudging whether the value is smaller than the crosstalk threshold value, if so, turning to the step 17, otherwise, turning to the step 10;
XTc＝∑XTcc′ (4)
in formula (4), XTcc′Is the value of the crosstalk between the core c and its neighboring core c
Figure BDA0003009936560000071
L is the optical fiber transmission length, h represents the incremental crosstalk per unit transmission length,
Figure BDA0003009936560000072
wherein, alpha, r, beta, omegathRespectively representing the coupling coefficient, bend radius, propagation constant and core pitch.
And 8: judging whether the service request can be aggregated with other service requests into a group, if so, turning to the step 6, otherwise, turning to the step 9;
and step 9: searching available spectrum resource blocks in the rest spectrum intervals of the fiber core group, if available spectrum blocks exist in the fiber core interval, performing spectrum allocation weight calculation on all the spectrum blocks capable of performing service transmission according to the formula (5), selecting the spectrum block with the largest spectrum allocation weight value to transmit a service request, and turning to the step 7, and if no available spectrum block exists in the fiber core interval, turning to the step 10;
Figure BDA0003009936560000073
in the formula (5), the reaction mixture is,
Figure BDA0003009936560000074
to select the weight values for spectral blocks in the core c interval s of the candidate path k,
Figure BDA0003009936560000075
the spectral compactness of the core c interval s of the candidate path k,
Figure BDA0003009936560000076
for selecting a spectral block in the interval s of cores c of the candidate path k, the number of frequency slots in which the adjacent core c' overlaps the selected spectral block, wherein,
Figure BDA0003009936560000077
Figure BDA00030099365600000715
and
Figure BDA0003009936560000078
respectively representing the maximum occupied frequency slot index value and the minimum occupied frequency slot index value of the fiber core c interval s of the candidate path k,
Figure BDA0003009936560000079
the state of the ith frequency slot in the segment s of the fiber core c representing the candidate path k occupies 0, otherwise it is 1,
Figure BDA00030099365600000710
represents the frequency slot number contained in the jth idle spectrum block in the core c interval s of the candidate path k,
Figure BDA00030099365600000711
the number of free spectral blocks in the core c interval s of the candidate path k,
Figure BDA00030099365600000712
fs、ferespectively a starting frequency slot index value and an ending frequency slot index value, P, of the selected spectrum blockcoreTo select a set of adjacent cores of the core,
Figure BDA00030099365600000713
and
Figure BDA00030099365600000714
the spectral states respectively representing the jth frequency slot in the fiber core c and the fiber core c' adjacent to the fiber core c occupy 0, otherwise 1.
Step 10: judging whether a node configured with a limited spectrum converter exists in the candidate path, if so, turning to the step 11, otherwise, turning to the step 12;
step 11: judging whether the service request has an available spectrum block meeting a crosstalk threshold value in a spectrum conversion range, if so, turning to the step 13, otherwise, blocking the service request;
step 12: judging whether k is smaller than | P |, wherein | P | is the total number of the candidate paths, if so, turning to the step 5, otherwise, blocking the service request;
step 13: and successfully transmitting the service request, and outputting the path selected by the service request, the fiber core serial number and the spectrum resource.
Fig. 2 is a diagram of a path selection example, assuming that a 2FS service request is transmitted from node 1 to node 6 and each link has enough spectrum resources to transmit the service, 3 shortest paths are selected for service transmission. The numbers on the links in the figure represent the link load, the node 2 being configured withA node of the finite spectrum converters, and the numbers (a, b) on the node represent the number of finite spectrum converters available at the node and the total number of finite spectrum converters. Calculating the weight value of each candidate path according to the formula (2), and setting the weight coefficient alpha in the formula (2)1＝α2When the weight value of candidate path 1 is 0.5, W1When the weight value of candidate path 2 is 0.5 × 0.8+0.5 × 0, the weight value is W20.5 × (0.6+0.4+0.5) +0.5 × 0 ═ 0.75, and the weight value of candidate path 3 is set to be 0.5 × (0.6+0.4+0.5) +
Figure BDA0003009936560000081
And performing ascending arrangement on the candidate paths according to the weight values of the candidate paths, wherein the ordering result is as follows: w1→W2→W3And selecting the candidate path with the minimum weight value for transmission, so that the candidate path 1 is selected for service transmission.
FIG. 3 is a schematic diagram of core grouping and spectral zoning. First, according to the idea of vertex coloring, the seven-core optical fiber can be divided into three groups, and the circles of different filling shapes in the figure represent different fiber core groups. And secondly, partitioning the frequency spectrum according to the number of the fiber core groups, wherein the number of the fiber core groups is odd 3, the number of the frequency spectrum partitions is 4, and the size of each interval is calculated according to the size of the service request and the proportion of the service request. When frequency slots are allocated to the service requests in the frequency spectrum interval, the service requests belonging to the first group are allocated in the first interval of the fiber core group 1 by adopting a first matching criterion; distributing the service requests belonging to the second group in a second interval of the fiber core group 2 by adopting a last matching criterion; similarly, the first matching criterion is adopted to allocate the service requests belonging to the third group in the third interval of the fiber core group 1 or the fiber core group 2, and the last matching criterion is adopted to allocate the service requests belonging to the last group in the last interval of the fiber core group 3.
Fig. 4 is a diagram of an example of spectrum selection. When a 4FS service request cannot find a spectrum block meeting the bandwidth requirement in the interval 1 of the fiber core group 2 of the path, and the maximum factors of the frequency gaps of the two-interval and three-interval distribution service requests are 3 and 5, and cannot be aggregated with the 4FS service request, the service distribution in the two-interval or three-interval is considered at this timeAnd (6) requesting. According to the spectrum allocation criterion, a last matching criterion is adopted in interval distribution, and a first matching criterion is adopted in interval distribution. Calculating the spectrum distribution weighted values when the service request selects the second interval and the third interval of the fiber core group 2 and the spectrum blocks are transmitted according to the formula (4), taking the spectrum block of the second interval of the fiber core group 2 as an example, calculating the spectrum compactness of the spectrum block as
Figure BDA0003009936560000082
Secondly, calculating the number of overlapping frequency gaps of the fiber core 2 and the adjacent fiber core, wherein the fiber core adjacent to the fiber core 2 comprises the fiber core 1, the fiber core 3 and the fiber core 7, no overlapping frequency gap exists between the fiber core 1 and the fiber core 2 in the spectrum block range selected by the fiber core 2, the number of overlapping frequency gaps between the fiber core 3 and the fiber core 2 is 4, the number of overlapping frequency gaps between the fiber core 7 and the fiber core 2 is 0, and the total number of overlapping frequency gaps is
Figure BDA0003009936560000091
The spectrum is assigned a weight value of
Figure BDA0003009936560000092
The weight values on other fiber cores and intervals are calculated in the same way,
Figure BDA0003009936560000093
Figure BDA0003009936560000094
when allocating spectrum blocks for service requests, the spectrum block with the largest weight value of spectrum allocation is preferentially selected, and the index value of the second intermediate frequency gap in the fiber core 2 interval is selected to be [6,9 ] according to the calculation results]The spectrum block of (1).
Finally, it is noted that the above-mentioned preferred embodiments illustrate rather than limit the invention, and that, although the invention has been described in detail with reference to the above-mentioned preferred embodiments, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the scope of the invention as defined by the appended claims.

Claims (2)

1. A resource allocation method of a multi-core elastic optical network based on node and crosstalk perception is characterized in that: the method comprises the following steps:
s1: according to a node intermediary centrality formula in an optical network, computing the intermediary centrality of each node in the network topology, sequencing the nodes in the network in a descending order according to the intermediary centrality value, wherein the larger the intermediary centrality value of the node is, the more important the node is, secondly, according to the number of the nodes and links in the network, determining the proportion theta of the nodes which can be configured with the limited spectrum converter in the network, wherein the value range of the proportion of the nodes which can perform spectrum conversion in the network is
Figure FDA0003009936550000011
L is the number of links in the network, | V | represents the number of nodes in the network,
Figure FDA0003009936550000012
taking an integer value upwards, then selecting | V | multiplied by theta nodes according to the sorting of the nodes, and configuring a finite spectrum converter for the nodes in sequence;
the calculation formula of the node intermediary centrality is as follows:
Figure FDA0003009936550000013
in this formula, V is the set of nodes in the network, pi(s, t) represents the number of shortest paths passing through the intermediate node i with the source node s and the destination node t, and 0.5(| V | -1) × (| V | -2) represents the total number of shortest-length paths in the network, except for the node i, if one shortest-length path is selected between any node pair in the network.
S2: selecting K candidate paths in a multi-core elastic optical network by using a shortest path method according to a service request, wherein the value of K is a maximum integer value taken upwards from the average degree of nodes of a network topology, calculating the weight value of each candidate path according to a path weight formula, and arranging the candidate paths in a set P in an ascending order according to the size of the path weight value;
the calculation formula of the path weight value is as follows:
Figure FDA0003009936550000014
in the path weight formula, α1、α2The weight coefficients represent the influence of the path load and the finite spectrum converter arranged in the path on the candidate path respectively, wherein alpha1+α2＝1，hopkThe hop count for the kth candidate path,
Figure FDA0003009936550000015
the weighted value of the ith link in the candidate path k, RC and RC are the number of available finite spectrum converters and the total number of finite spectrum converters at the node, respectively.
S3: performing fiber core frequency spectrum allocation on the service request in the path set P, designing a frequency spectrum allocation weight formula, calculating frequency spectrum allocation weight values when the service request is allocated in different frequency spectrum intervals of the candidate path, and selecting an allocation mode with the minimum frequency spectrum allocation weight value as a service request allocation path, a fiber core and a frequency spectrum block;
s4: calculating the crosstalk value among cores when the service request uses the path, the fiber core and the spectrum block determined in the last step for transmission, if the crosstalk value does not meet the crosstalk threshold condition, reducing the crosstalk through a spectrum conversion method, firstly checking whether a node capable of performing spectrum conversion exists in the candidate path of the service request, if so, judging whether a spectrum block meeting the service bandwidth requirement exists in the spectrum conversion range of the transmission fiber core, if so, preferentially selecting a spectrum block with a few frequency gaps overlapped with the adjacent fiber core for the service request, and recording the candidate path and the fiber core serial number of the spectrum block, otherwise, searching a proper spectrum block for the service request by adopting the method S3 in the next candidate path, and recording the candidate path and the fiber core serial number of the spectrum block.
2. The method for resource allocation based on node and crosstalk awareness in the multi-core elastic optical network as claimed in claim 1, wherein: the specific method of S3 is as follows:
s301: grouping fiber cores according to the idea of vertex coloring, dividing non-adjacent fiber cores into a group, partitioning a frequency spectrum to further reduce the influence of crosstalk between the cores, wherein the partition number is related to the grouping number of the fiber cores, when the grouping number of the fiber cores is an odd number, the partition number is the fiber core grouping number plus 1, when the grouping number of the fiber cores is an even number, the partition number is equal to the fiber core grouping number, and the frequency gap number of each partition is obtained by a section frequency gap calculation formula;
wherein, the interval frequency gap calculation formula is as follows:
Figure FDA0003009936550000021
in the interval frequency slot calculation formula, firstly, service requests with the same maximum factor are aggregated into a group according to the size of the frequency slot number required by the service request bandwidth, m and n are respectively the number of the types of the ith group of service requests and the total number of the types of the service requests, RxAnd RijThe number of frequency slots, P, required by the xth service request and the ith group of the jth service request respectivelyxAnd PijThe ratio of the xth service request and the ith group jth service request to the total service request is respectively, S is the total number of frequency slots in the fiber core, and the subscript min FS indicates that the number of frequency slots allocated to the group i must be a multiple of the number of frequency slots required by the minimum service request bandwidth in the group i.
S302: calculating the maximum factor of the frequency slot number required by the service request, selecting a proper frequency spectrum interval for distributing frequency spectrum resources for the service request, if the service request is distributed in an odd interval, adopting a first matching criterion to distribute the frequency spectrum resources, namely searching available frequency spectrum blocks from the frequency slots with low index values, and if the service request is distributed in an even interval, adopting a last matching criterion to distribute the frequency spectrum resources, namely searching the available frequency spectrum blocks from the frequency slots with high index values;
s303: if the service request has no available frequency spectrum resources in the frequency spectrum interval with the maximum factor, checking whether the frequency gap number required by the service request has the same factor as the frequency gap number required by other groups of service requests, if so, allocating the service request to the corresponding frequency spectrum interval, allocating a proper frequency spectrum block for the service request according to a service allocation rule, if not, searching an idle frequency spectrum block with the maximum frequency spectrum allocation weighted value in all other frequency spectrum intervals according to a frequency spectrum allocation weight formula to transmit the service request, and recording a candidate path where the frequency spectrum block is located and a fiber core serial number.
The calculation formula of the spectrum allocation weight is as follows:
Figure FDA0003009936550000031
in the calculation formula of the spectrum allocation weight,
Figure FDA0003009936550000032
to select the weight values for spectral blocks in the core c interval s of the candidate path k,
Figure FDA0003009936550000033
the spectral compactness of the core c interval s of the candidate path k,
Figure FDA0003009936550000034
for selecting a spectral block in the interval s of cores c of the candidate path k, the number of frequency slots in which the adjacent core c' overlaps the selected spectral block, wherein,
Figure FDA0003009936550000035
Figure FDA0003009936550000036
and
Figure FDA0003009936550000037
respectively representing the maximum occupied frequency slot index value and the minimum occupied frequency slot index value of the fiber core c interval s of the candidate path k,
Figure FDA0003009936550000038
the state of the ith frequency slot in the segment s of the fiber core c representing the candidate path k occupies 0, otherwise it is 1,
Figure FDA0003009936550000039
represents the frequency slot number contained in the jth idle spectrum block in the core c interval s of the candidate path k,
Figure FDA00030099365500000310
the number of free spectral blocks in the core c interval s of the candidate path k,
Figure FDA00030099365500000311
fs、ferespectively a starting frequency slot index value and an ending frequency slot index value, P, of the selected spectrum blockcoreTo select a set of adjacent cores of the core,
Figure FDA00030099365500000312
and
Figure FDA00030099365500000313
respectively represents the occupation states of the jth frequency slot in the fiber core c and the fiber core c' adjacent to the fiber core c, wherein the occupation state is 0, and otherwise, the occupation state is 1.
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