In this paper, we investigate the outage probability of a multiuser multiple-input multiple-output (MU-MIMO) system in the heterogeneous network (HetNet) in the presence of unpredictable interference (UI) from coexisting ad hoc systems. In order to achieve multiuser diversity gain, the MU-MIMO system requires feedback carrying the signal-to-interference-plus-noise ratio (SINR) from all active users to the base station. However, the coexisting ad hoc systems in HetNet can unpredictably initiate their data transmission during the SINR feedback duration. This unpredictable behavior by the coexisting ad hoc systems causes a mismatch between the measured SINR and the instantaneous SINR. In order to investigate the performance of the MU-MIMO system in HetNets, we first categorize the interferences into predictable interference and UI. Based on this categorization, we analyze the outage probability of an MU-MIMO system using a max-SINR scheduler. The theoretical analyses show that the MU-MIMO system cannot achieve the maximum diversity gain, since the UI from the coexisting systems causes beam selection mismatch. Additionally, we show that reducing the interval between the measurement and data transmission prevents performance degradation by reducing the effect of the unpredictable behavior of the coexisting ad hoc systems.
Bibliographical noteFunding Information:
This work was supported in part by the Institute for Information and Communications Technology Promotion (IITP) grant through the Korea Government (MSIT) (Development on the core technologies of transmission, modulation, and coding with low-power and low-complexity for massive connectivity in the IoT environment) under Grant 2016-0-00181 and in part by the National Research Foundation of Korea (NRF) grant through the Korea Government under Grant NRF2015R1A2A1A01006162.
All Science Journal Classification (ASJC) codes
- Computer Science(all)
- Materials Science(all)