Cooperative Wireless Multicell OFDMA Network with Backhaul Capacity Constraints

This papers considers the downlink of a wireless multicell downlink orthogonal frequency division multiple-access (OFDMA) system where neighboring base-stations (BSs) can jointly encode and transmit data signals to their users using zero-forcing (ZF) precoding in each frequency tone, but only a limited backhaul-capacity is available for each BS to share its user´s data streams with the neighboring BSs. A numerical algorithm is proposed to maximize the network-wide utility of this system subject to backhaul capacity constraints. The proposed algorithm first selects a subset of frequency tones for each BS to share its user´s data streams with the neighboring BSs and then, jointly schedules users and adapts the precoding coefficients and the power spectra of the BSs to effectively utilize the limited backhaul capacity. Numerical results show that using the proposed algorithm, the gain in downlink sum-rate per cell can be made to scale linearly with the available backhaul capacity per BS between the no-cooperation and the full-cooperation scenarios.