Power optimization is a central issue in wireless network design. Given a graph with costs on the edges, the power of a node is the maximum cost of an edge incident to it, and the power of a graph is the sum of the powers of its nodes. Motivated by applications in wireless networks, we consider several fundamental undirected network design problems under the power minimization criteria. Given a graph G = (V , E) with edge costs {c(e) : e ∈ E} and degree requirements {r(v) : v ∈ V }, the Minimum-Power Edge-Multi-Cover (MPEMC) problem is to find a minimumpower subgraph G of G so that the degree of every node v in G is at least r(v). We give an O(log n)-approximation algorithms for MPEMC, improving the previous ratio O(log 4 n). This is used to derive an O(log n + α)-approximation algorithm for the undirected Minimum-Power k-Connected Subgraph (MPkCS) problem, where α is the best known ratio for the min-cost variant of the problem. Currently, α = O(log k · log n n−k ) which is O(log k) unless k = n − o(n), and is O(log 2 k) = O(log 2 n) for k = n − o(n). Our result shows that the min-power and the min-cost versions of the Preliminary version appeared in LATIN, pages 423-435, 2008. G. 736 Algorithmica (2011 k-Connected Subgraph problem are equivalent with respect to approximation, unless the min-cost variant admits an o(log n)-approximation, which seems to be out of reach at the moment.