Topology control for ad-hoc networks is crucial due to the absence of a fixed infrastructure that can guarantee satisfactory connectivity among communication nodes. In this paper, we study the impacts of adjustment of transmission power as a means to control the network topology (connectivity) to the signal-to-interference-plus-noise (SINR) ratio and the number of hops between two nodes, where the SINR and the hop count are highly related to the network throughput and packet delay, respectively. We investigate three distinct topologies: fully, minimally and moderately connected networks. Our results show that adjusting the power level is a very effective way to control the network topology, while enabling to achieve the desirable tradeoffs among SINR and hop count.