Backbone has been used extensively in various aspects (e.g., routing, route maintenance, broadcast, scheduling) for wireless networks. Previous methods are mostly designed to minimize the backbone size. However, in many applications, it is desirable to construct a backbone with small cost when each wireless node has a cost of being in the backbone. In this paper, we first show that previous methods specifically designed to minimize the backbone size may produce a backbone with a large cost. We then propose an efficient distributed method to construct a weighted sparse backbone with low cost. We prove that the total cost of the constructed backbone is within a small constant factor of the optimum for homogeneous networks when either the nodes' costs are smooth or the network maximum node degree is bounded. We also show that with a small modification the constructed backbone is efficient for unicast: the total cost (or hop) of the least cost (or hop) path connecting any two nodes usingbackbone is no more than 3 (or 4) times of the least cost (or hop) path in the original communication graph. As a side product, we give an efficient overlay based multicast structure whose total cost is no more than 10 times of the minimum when the network is modeled by UDG. Our theoretical results are corroborated by our simulation studies.
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