In this paper, sum spectrum efficiency of two cell multiple-input multiple-output (MIMO) system having multiple antennas at base station (BS) and multiple user equipments (UEs) is analysed. The maximum ratio (MR) and multi-cell minimum mean squared error (M-MMSE) techniques are utilized for detection/precoding in the uplink/downlink scenario. In this paper, two boundary cases of propagation channel model: line of sight (LoS) and non-line of sight (NLoS), and generalized propagation channel model of millimeter wave (mmWave) are compared using MR and MMSE detection techniques. The closed bound expressions of sum spectrum efficiency of MR are expressed and simulated, whereas for M-MMSE, Monte-Carlo simulations are performed on the basis of its weighting vector. The fundamental limits on the system performance, using large antenna arrays and many UEs satisfying practical constraints like desired signal to noise ratio (SNR), low complexity in signal processing, gain of inter cell interference and finite-dimensional channels are analysed.