In mobile wireless networks, the Root Sequence Index (RSI) is used to allocate uplink channels between the user equipment and the base station. The assignment of RSIs close-in-range to neighbor radios may cause collisions leading to failures on service establishment and performance degradation. In this study, we model the RSI allocation as a generalization of the classical Graph Coloring Problem, indicating that there must be a minimum distance for the assigned colors of two neighbors. For the RSI allocation, a maximal distance is also needed. We develop methods for allocating the RSI, while minimizing the risk of collisions, for two different operation modes found on carrier-grade networks. Both exact and heuristic methods are explored and compared. We test the proposed approaches on instances obtained from real-life context.