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Page 2 Lecture Notes in Computer Science 2865 Edited by G. Goos ...

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214 T. Chu and I. Nikolaidisaim at produc<strong>in</strong>g paths among all source-dest<strong>in</strong>ation pairs subject to the pernodebandwidth constra<strong>in</strong>ts and with the objective of m<strong>in</strong>imiz<strong>in</strong>g the powerconsumption.The <strong>in</strong>itial topology graph considered, G(V,E), is completely connected. Subsequentlyedges are removed to ensure that the capacity constra<strong>in</strong>ts are not violated.T is the set of source-dest<strong>in</strong>ation demands, where<strong>by</strong> T i,j is the demand(bits per second) from node i to node j. Ps is the set of all paths establishedwith the <strong>in</strong>tention of m<strong>in</strong>imiz<strong>in</strong>g energy cost. Shortest Path(G(V,E), D, source,dest<strong>in</strong>ation, Path) is any straightforward implementation of the shortest pathalgorithm from source node to dest<strong>in</strong>ation node on a graph whose connectivity iscaptured <strong>by</strong> G(V,E) and the edge costs are captured <strong>by</strong> D. The Shortest Path()returns true if a path is found and false if it could not, because the source anddest<strong>in</strong>ation are <strong>in</strong> two different connected components.2.1 Successive M<strong>in</strong>imum Energy PathsSuccessive_M<strong>in</strong>imum_Energy_Paths (Input: V, D, P, T; Output Ps)1: for all u ∈ V do2: C[u] ←03: end for4: G(V,E) ← completely connected graph of V nodes5: while T ≠ ∅ do6: select T i,j from T7: R ← C8: repeat9: reconstruct ← false10: if (!Shortest P ath(G, P, i, j, P ath)) then11: return (INFEASIBLE)12: else13: for all (u, v) ∈ P ath do14: for all x ∈ V do15: if D[u][v] ≤ D[u][x] then16: R[x] ← R[x]+T i,j17: end if18: if R[x] > capacity then19: reconstruct ← true20: end if21: end for22: end for23: if (!reconstruct) then24: C ← R25: Ps ← Ps∪ P ath26: else27: for all (u, v) ∈ P ath do28: for all (x, y) ∈ E do

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