Bandwidth Overlap Factor for Feasible Coexistence of LTE-A and Point to Multipoint LMDS Systems

The necessity to share the radio spectrum becomes highly significant in the recent time due to emerging new wireless technologies and, the cost and difficulty in attaining new frequency spectrum licenses. However, spectrum sharing leads to substantial interference between the close systems especially in the same frequency band. In this paper, we present a spectrum sharing scheme to investigate coexistence feasibility results in interference from orthogonal frequency division multiplexing (OFDM)-based Long Term Evolution-Advanced (LTE-A) into point to multipoint (P-MP) local multipoint distribution service (LMDS). This method proposes a spectrum frequency mask for the OFDM-based LTE-A according to bandwidth overlapping method with the P-MP LMDS system. The relative power spectral density of the proposed spectrum emission mask due to bandwidth overlap has been mathematically derived in a more compact closed-form. It shows smoother and 1.7 dB less than that of traditional OFDM mask in the main spectrum bandwidth which in turn leads to reduce the interference effects to LMDS system. The coexistence coordination studies are made at the frequency of 3500 MHz, on the base of co-primary operation and co-located systems. The numerical results demonstrate that the difference in amount of the required carrier frequency for safe coexistence increases as LMDS sector size increases. In addition, OFDM system with small channel bandwidth is much more affected than the wider channel bandwidth in terms of the necessary minimum guard bandwidth for harmless coexistence when the LMDS cell size changes from 0.5 to 3 km².