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the CRC function for the broadband (more than Gbps) quality measurement tool based on the HpFP socket library, hperf [3]. e performance of hperf is veried by measur-ing the throughput and packet loss ratio in INTELSAT communication [4], distributed storage system [5], and real-time weather radar data processing system [6][7] etc. We set up hperf in both sender (S) and receiver (R), and then measure the network condition. e arguments of the sender and receiver are as follows.e “-mt” option is a target throughput of HpFP. e target throughput is set by . It is conrmed that the throughput of 10 Gbps can be achieved by HpFP in the case of a packet loss ratio of less than 1% and RTT of geostationary orbit satellite [8]. e CRC is performed in HpFP using the “-crc” option. e error check interval in packets is set by . e output of hperf is saved in the

le. In the next sections, we analyze these output log les. In the WINDS experiment, we avoid bottleneck of buer size settings by setting kernel parameters using the sysctl command. e setting values of kernel parameters are as follows.4WINDS experiments4.1Experiment condition and preliminary experimentIn this section, we investigate the network conditions of the WINDS with bent-pipe mode using CRC function for HpFP. e conguration of the experiment is the same as shown in Fig. 2. In this paper, the RTT is xed to 250 ms of geostationary orbit satellite. Moreover, the target throughput of HpFP is set to 10 Mbps. Figure 5 shows the large-scale in-vehicle earth station. e experiment is conducted in Nakatsugawa, Gifu Prefecture in December 2016. e weather is cloudy during the whole time (with a short period of rain) of the experiment in which the results are discussed here. Figure 6 shows the distribution of clouds of the day of experiment taken by the Himawari-8 real-time web[9][10]. Note that the Nakatsugawa area is covered with clouds.As a preliminary experiment, we conrmed the quality of the communication line with 4K video streaming (throughput is 2.6 Gbps) by transmitting narrowband hperf (target throughput is 10 Mbps), as in the previous experi-ments [1][2]. We recognized lots of noise in the received video, as shown in Fig. 7. It means the deterioration of quality of communication lines. e receiving throughput is about 1.3 Gbps by counting the number of packets using dstat at the receiver. erefore, the packet loss rate (PLR) of the whole system is estimated to be about 50%. In Figure 8, the output results of log of hperf are taken every 500 ms in the preliminary experiment. Figure 8 (a) shows (a)(b)(c)FiF4　Throughput in WINDS satellite communication experiment:(a) throughput for a single connection in the case of RTT of 0 ms (target throughput per connection is 1.0 Gbps, 1.6 Gbps, and 1.7 Gbps, respectively), (b) throughput for two connections in the case of RTT of 0 ms, 250 ms, and 4,000 ms, respectively (target throughput per connection is 1.4 Gbps) and (c) throughput for multiple (50) connections in the case of RTT of 0 ms, 250 ms and 4,000 ms, respectively (target throughput per connection is 54 Mbps)3 Ultra-High-Speed Satellite Communication Technology170　　　Journal of the National Institute of Information and Communications Technology Vol. 64 No. 2 (2017)