Learn More
ÐGiven a WDM optical network with wavelength channels on its fiber links, we consider the problem of finding the minimum set of network nodes such that, with wavelength converters at these nodes, broadcast can be supported in the network. We call this problem the Converter Placement problem. We model a given network using a graph q with colors on its edges(More)
This paper first studied the timeslot assignment problem in time division multiple access/code division multiple access (TDMA/CDMA) wireless ad hoc networks. Given a path P, we prove that a timeslot assignment providing one unit of bandwidth on P can be found in O(jPj) time if such an assignment exists. The results have been extended to the case that P can(More)
—Over years, virtual backbone has attracted lots of attentions as a promising approach to deal with the broadcasting storm problem in wireless networks. One popular way to construct a quality virtual backbone is to solve the minimum connected dominating set problem. However, a virtual backbone computed in this way is not resilient against topology change(More)
A connected dominating set in a graph is a subset of vertices such that every vertex is either in the subset or adjacent to a vertex in the subset and the subgraph induced by the subset is connected. A minimum-connected dominating set is such a vertex subset with minimum cardinality. An application in ad hoc wireless networks requires the study of the(More)
—This paper investigates the optimal replication of data objects at hierarchical and transparent web proxies. By transparent, we mean the proxies are capable of intercepting users' requests and forwarding the requests to a higher level proxy if the requested data are not present in their local cache. Two cases of data replication at proxies are studied: 1)(More)
Consider an asymmetric wireless network represented by a digraph G = (V , E). A subset of vertices U is called a strongly connected dominating set (SCDS) if the subgraph induced by U is strongly connected and every vertex not in U has both an in-neighbor in U and an out-neighbor in U. SCDS plays an important role of the virtual backbone in asymmetric(More)
In this paper, we discuss the energy efficient multicast problem in ad hoc wireless networks. The problem of our concern is: given an ad hoc wireless network and a multicast request, to find a multicast tree such that the total energy cost of the multicast tree is minimized. Each node in the network is assumed to have a fixed level of transmission power. We(More)