Teppei Oyama

TV white space availability in Japan estimated using D/U-based and I/N-based protection rules

This paper reports estimates of TV white space (TVWS) availability in Japan that are based on the separation distances calculated using D/U-based and I/N-based rules. Calculating the TVWS availability with various TVWS-device parameters—antenna height, transmission power, protected area threshold, and adjacent channel leakage ratio (ACLR)—revealed the parameter dependence of the availability of TVWS channels. The effect of changing the protected area threshold is shown to differ between D/U-based and I/N-based rules: only in D/U-based rule do both separation distance and protected area decrease when the protected area threshold increases. We also show that the effect of the ACLR is smaller than that of the other parameters. Our estimates can be utilized as reference data showing how changes in TVWS availability depend on various TVWS device parameters.

Field experiment results using 2×2 and 4×4 MIMO precoding in E-UTRA downlink

We present field experiment results on multiple input multiple output (MIMO) precoding using orthogonal frequency division multiple access (OFDMA) in the E-UTRA downlink. We measured the throughput performance of 4×4 MIMO precoding with 1- to 4-stream transmission. Time variation characteristics of throughput, SINR, and antenna correlations are compared to evaluate the selection criteria for the number of streams. The throughput performance of 2×2 MIMO precoding are also evaluated and compared with the results of the 4×4 MIMO case. Based on the evaluation of the field experiment results, we verify that the throughput is maximized using 3- or 4-stream transmission. Furthermore, we verify that 2-stream transmission is also effective for 4×4 MIMO in an actual propagation environment, since high antenna correlation sometimes happens on which the throughput performance of 3- or 4-stream transmission is severely degraded. Evaluation results also show that the estimated gain of rank adaptation is about 11.6% for 4×4 MIMO and about 6% for 2×2 MIMO.