We address the issue of wireless ad hoc network connectivity by using a tail model that is derived from the signal to interference and noise ratio (SINR). The SINR model more accurately describes link connectivity than the traditionally used disk model in the real-world. We first assess the network connectivity by measuring the conductance of the network and find the bottleneck location of the network, and then deploy a relay node to improve the connectivity at the bottleneck. A partition algorithm is proposed to address the first problem, and an optimization problem is proposed to address the relay node deployment problem. The relay node deployment problem is solved by using approximate convex optimization models, and the approximation performance is analyzed. Simulation results show that the partition algorithm based on the SINR model identifies the network bottleneck more accurately than the previous methods based on the binary model. It also verifies that the relay node can significantly relieve the bottleneck and make the network more tightly knit.