Indoor MIMO performance with HSPA+ and LTE
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MIMO:n suorituskyky sisätiloissa HSPA+ ja LTE tekniikoilla
The focus of this thesis is to perform and study indoor measurements with both HSPA+ and LTE MIMO setups. The reason behind this study is to validate the benefits of MIMO implementation in indoor cells. MIMO scheme is compared against single antenna configurations and other test cases, such as different antenna diversity setups for spatial multiplexing and studying the effect of attenuation imbalance in MIMO antenna lines. In terms of performance, air interface throughput is used to compare different setups. Measurements were performed in a office building, using single cell with minimal interfernce. Throughput results were gathered in both mobile routes and in static locations, using laptop and spatial multiplexing MIMO capable commercial USB modems. Results obtained from these measurements follow the expectations, for the most part, made in measurement plan, based on literacy and theory behind MIMO and wireless radio access methods. On good channel conditions, near the antenna and at LOS locations, the maximal practical throughput peaks can be seen, and average rate is notably higher than single antenna setups. For HSPA+ on best channel conditions, spatial multiplexing MIMO gain is around 50% compared to single antenna and in worse channel condition, the average gain is only around 5 to 15%. With LTE, the MIMO gain in good channel conditions averages around 60% and on worse channel it still gives 15 to 30% average gain. LTE with OFDMA is more stable in terms of throughput variance than HSPA+ using WCDMA. Static measurement results show that current state of dual stream MIMO reception is very sensitive to receiver antenna orientation with both HSPA+ and LTE. Small change in receiver orientation can have a large effect to obtained throughput rate.