Protection method and system in flexible bandwidth optical networks with multi-core fiber

A protection method in a flexible bandwidth optical network with multi-core fiber, comprising:

• S1, generating a group of connection requests CRs;
• S2, for each connection request from the group of the connection requests CRs, calculating a working path from a source node s to a destination node d and K protection paths that do not intersect a link of the working path;
• S3, setting a maximum crosstalk threshold Amax of an optical fiber link according to a modulation format of a connection request, searching an optical fiber link for a candidate spectrum block that satisfies spectral continuity and spectral consistency, and calculating a crosstalk value;
• and searching for a candidate spectrum block with a crosstalk value less than or equal to the set crosstalk threshold Amax, wherein
• if the candidate spectrum block that satisfies a crosstalk threshold constraint is found, the candidate spectrum block is recorded, and S4 is performed, or
• if the candidate spectrum block that satisfies a crosstalk threshold constraint is not found, the connection request is blocked;
• S4, setting the maximum crosstalk threshold Amax of the optical fiber link according to the modulation format of a connection request, and searching an optical fiber link for a candidate spectrum block that satisfies the spectral continuity and the spectral consistency and has a bandwidth equal to a bandwidth requirements of a connection request, wherein
• if the candidate spectrum block is empty, S5 is performed, or
• if the candidate spectrum block is not empty, a crosstalk value is calculated, and
• searching for the candidate spectrum block that satisfies a crosstalk threshold requirement, wherein
• if the candidate spectrum block that satisfies the crosstalk threshold requirement is found, the candidate spectrum block is recorded, and the connection request is successfully established, or
• if the candidate spectrum block that satisfies the crosstalk threshold requirement is not found, S5 is performed;
• S5, compressing the transmission bandwidth of a connection request on a protection path qi and a protection core cp, and performing S4 after a compressed state of bandwidth is reached, wherein if a spectrum resource that satisfies the spectral continuity, the spectral consistency, and the crosstalk threshold constraint fails to be found, the connection request is blocked;
• and
• S6, establishing a group of connection requests based on S1 to S5,
• wherein First Formula (1) is used in S3 to calculate a crosstalk impact value Mfijcl of a spectral gap numbered j in an ith candidate spectrum block on a core c of an optical fiber link l by an adjacent core, and the expression of First Formula (1) is:
• M
• f
• i
• ⁢
• j
• cl
• =
• {
• τ
• 1
• ×
• ∑
• r
• ∈
• n
• ⁢
• F
• j
• r
• ⁢
• l
• ⁢
• ,
• if
• ⁢
• ⁢
• ∑
• r
• ∈
• n
• ⁢
• F
• j
• r
• ⁢
• l
• >
• 1
• ,
• j
• ∈
• F
• ⁢
• M
• i
• τ
• 0
• ×
• ∑
• r
• ∈
• n
• ⁢
• F
• j
• r
• ⁢
• l
• ⁢
• ,
• if
• ⁢
• ⁢
• ∑
• r
• ∈
• n
• ⁢
• F
• j
• r
• ⁢
• l
• ≤
• 1
• ,
• j
• ∈
• F
• ⁢
• M
• i
• (
• 1
• )
• wherein τ0 and τ1 are crosstalk weight value adjustment factors, τ0∈[0,1], and τ1∈[2,3];
• Second Formula (2) is used in S3 to calculate an optical fiber link crosstalk value Aficl(dB) corresponding to the ith candidate spectrum block on the core c of the optical fiber link l, and the expression of Second Formula (2) is:
• A
• f
• i
• cl
• ⁡
• (
• dB
• )
• =
• 101
• ⁢
• g
• ⁢
• {
• n
• -
• n
• ·
• exp
• ⁡
• [
• -
• (
• n
• +
• 1
• )
• ·
• 2
• ⁢
• hL
• ]
• 1
• +
• n
• ·
• exp
• ⁡
• [
• -
• (
• n
• +
• 1
• )
• ·
• 2
• ⁢
• hL
• ]
• }
• ×
• FS
• FS
• +
• ∑
• j
• ∈
• FM
• i
• ⁢
• M
• f
• i
• ⁢
• j
• cl
• ⁢
• ⁢
• where
• ⁢
• ⁢
• h
• =
• 2
• ⁢
• K
• 2
• ⁢
• r
• βω
• th
• ,
• (
• 2
• )
• h is an average increase in crosstalk in each unit of length, n is a quantity of adjacent cores, L is the length of optical fiber, and κ, r, β, and ωth are all physical parameters of the optical fiber, and respectively represent a coupling coefficient, a radius of curvature, a propagation constant, and a centre-to-centre distance;
• Mfijcl is the crosstalk impact value of the spectral gap numbered j in the ith candidate spectrum block on the core c of the optical fiber link l by an adjacent core;
• and
• Σj∈FMi Mfijcl is a crosstalk impact value of the ith candidate spectrum block on the core c of the optical fiber link l by an adjacent core;
• and when the value of Aficl(dB) increases, it indicates that a spectrum block calculated on the core c of the optical fiber link l is susceptible to higher impact from crosstalk.