Much recent interest has focused on applying multihop relaying to conventional cellular communication systems. Multihop relaying can broaden the cell coverage and enhance the capacity of cellular systems. However, as is well-known, cell coverage can also be broadened simply by lowering the transmission rate in a conventional cellular system. According to this commonality, we theoretically formulate the performance of cellular systems with multihop relaying in terms of outage probability and spectral efficiency using the same methodology to formulate the performance of cellular systems with rate adaptation. Simulation results reveal that multihop relaying and rate adaptation have very similar effects on the performance of cellular systems