A cellular network is often modelled as a graph and the channel assignment problem is formulated as a coloring problem of the graph. Sen et al. (1998) introduced the notion of cellular graphs that models the hexagonal cell structure of a cellular network. Assuming a k-band buffering system where the interference does not extend beyond k cells away from the call originating cell, we provided two different formulations of the channel assignment problem: Distance-k chromatic number problem and k-band chromatic bandwidth problem. The channel assignment algorithms presented in Sen et al. were non-optimal. In this paper we provide: (i) a new algorithm for the distance-k chromatic number problem that is optimal and (ii) a near optimal algorithm for the 2-band chromatic bandwidth problem that has a performance bound of 4/3. The complexity of the algorithms is O(p), where p is the number of cells.