In this paper we study low complexity linear receivers for millimeter-wave (mmWave) communication systems with uniform circular arrays (UCAs) in line-of-sight (LOS) multiple-input multiple-output (MIMO) channels. Typical applications are fixed wireless access such as small cell backhaul for high rate large capacity communications. Conventional zero forcing (ZF) and minimum mean squared error (MMSE) receivers require computations of matrix inverses which have high computational complexity. We show that the MIMO channel matrices for UCAs in LOS-MIMO channels are circulant matrices. Based on the properties of circulant matrices, we propose low complexity linear receivers without matrix inverse for LOS-MIMO systems with UCAs. With significantly reduced complexity, the proposed algorithms are mathematically equivalent to the conventional linear receivers without any performance loss. Simulation results also show that the proposed mmWave LOS-MIMO system is not sensitive to the variations of link ranges.