6 research outputs found
Traffic Grooming in Unidirectional WDM Rings with Bounded Degree Request Graph
Traffic grooming is a major issue in optical networks. It refers to grouping
low rate signals into higher speed streams, in order to reduce the equipment
cost. In SONET WDM networks, this cost is mostly given by the number of
electronic terminations, namely ADMs. We consider the case when the topology is
a unidirectional ring. In graph-theoretical terms, the traffic grooming problem
in this case consists in partitioning the edges of a request graph into
subgraphs with a maximum number of edges, while minimizing the total number of
vertices of the decomposition. We consider the case when the request graph has
bounded maximum degree , and our aim is to design a network being able
to support any request graph satisfying the degree constraints. The existing
theoretical models in the literature are much more rigid, and do not allow such
adaptability. We formalize the problem, and solve the cases (for all
values of ) and (except the case C=4). We also provide lower
and upper bounds for the general case
Traffic Grooming in Unidirectional WDM Rings with Bounded Degree Request Graph
Traffic grooming is a major issue in optical networks. It refers to grouping low rate signals into higher speed streams, in order to reduce the equipment cost. In SONET WDM networks, this cost is mostly given by the number of electronic terminations, namely ADMs. We consider the case when the topology is a unidirectional ring. In graph-theoretical terms, the traffic grooming problem in this case consists in partitioning the edges of a request graph into subgraphs with a maximum number of edges, while minimizing the total number of vertices of the decomposition. We consider the case when the request graph has bounded maximum degree , and our aim is to design a network being able to support any request graph satisfying the degree constraints. The existing theoretical models in the literature are much more rigid, and do not allow such adaptability. We formalize the problem, and solve the cases (for all values of ) and (except the case ). We also provide lower and upper bounds for the general case
Drop cost and wavelength optimal two-period grooming with ratio 4
We study grooming for two-period optical networks, a variation of the traffic
grooming problem for WDM ring networks introduced by Colbourn, Quattrocchi, and
Syrotiuk. In the two-period grooming problem, during the first period of time,
there is all-to-all uniform traffic among nodes, each request using
of the bandwidth; and during the second period, there is all-to-all uniform
traffic only among a subset of nodes, each request now being allowed to
use of the bandwidth, where . We determine the minimum drop cost
(minimum number of ADMs) for any and C=4 and . To do
this, we use tools of graph decompositions. Indeed the two-period grooming
problem corresponds to minimizing the total number of vertices in a partition
of the edges of the complete graph into subgraphs, where each subgraph
has at most edges and where furthermore it contains at most edges of
the complete graph on specified vertices. Subject to the condition that the
two-period grooming has the least drop cost, the minimum number of wavelengths
required is also determined in each case
Traffic Grooming in Bidirectional WDM Ring Networks
We study the minimization of ADMs (Add-Drop Multiplexers) in optical WDM bidirectional rings considering symmetric shortest path routing and all-to-all unitary requests. We precisely formulate the problem in terms of graph decompositions, and state a general lower bound for all the values of the grooming factor and , the size of the ring. We first study exhaustively the cases , , and , providing improved lower bounds, optimal constructions for several infinite families, as well as asymptotically optimal constructions and approximations. We then study the case , focusing specifically on the case for some . We give optimal decompositions for several congruence classes of using the existence of some combinatorial designs. We conclude with a comparison of the cost functions in unidirectional and bidirectional WDM rings
Traffic Grooming in Bidirectional WDM Ring Networks
We study the minimization of ADMs (Add-Drop Multiplexers) in optical WDM bidirectional rings considering symmetric shortest path routing and all-to-all unitary requests. We precisely formulate the problem in terms of graph decompositions, and state a general lower bound for all the values of the grooming factor and , the size of the ring. We first study exhaustively the cases , , and , providing improved lower bounds, optimal constructions for several infinite families, as well as asymptotically optimal constructions and approximations. We then study the case , focusing specifically on the case for some . We give optimal decompositions for several congruence classes of using the existence of some combinatorial designs. We conclude with a comparison of the cost functions in unidirectional and bidirectional WDM rings