QoS Guaranteed Resource Allocation in Cooperative Cellular Network with MIMO-Based Relays

Relay-based cooperative transmission in cellular wireless networks has been an area of tremendous research recently. Since MIMO technique has been shown to increase the spectral efficiency significantly, relays with MIMO antennas seem to be potential candidate for future cooperative cellular system in order to achieve reliable transmission, high system throughput and extended network coverage. In this paper, we study a cellular system scenario where quality of service (QoS) of multiple data streams originating from a base station (BS) targeted to multiple mobile stations (MSs) is guaranteed by using pre-installed relay stations (RSs) with MIMO antennas. We propose a low-complexity algorithm to design precoder matrices at BS and RS by using joint zero-forcing strategy to avoid multiuser interference in the signal received at the MSs via both the direct path (BS-MS) and the relay path (BS-RS-MS). The proposed algorithm guarantees a predefined signal-to-noise ratio at each user within the transmit power constraint at BS and with the minimal sum transmit power of BS and RS. Simulation results show that proposed algorithm outperforms the singular value decomposition (SVD)-based scheme existing in the literature by keeping the outage probability lower. Moreover, the performance of proposed algorithm compared to that of SVD-based scheme is further improved when the RS is not situated directly between the BS and the MSs.