In this paper, we propose a cooperative transmission scheme (CTS) for system throughput enhancement in enterprise femtocell downlink systems. In our scheme, the user equipment (UE) is capable of receiving the desired signal from the serving femtocell base station (fBS) as well as from an adjacent fBS. Thus, the UE achieves an improved signal-to-interference ratio (SIR) by using two time synchronized signals. Performances of the proposed scheme are evaluated in terms of the call-level quality of service (QoS) (i.e., call blocking probability) and the packet-level QoS (i.e., outage probability). We first measure the resource utilization and call blocking probability for the downlink resources for various offered load in femtocell. Based on that, we obtain the outage probability and effective throughput of the system via computer simulations. Simulation results show that compared to the conventional scheme, the proposed scheme can reduce the UE's outage probability in the enterprise femtocell environment. In particular, a significant performance improvement can be achieved with the proposed CTS for UEs located at the cell edge.
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