Development of Microwave Link for 8K Super Hi-Vision Program Contribution

Development of Microwave Link for 8K Super Hi-Vision Program Contribution Hirokazu Kamoda, Kenji Murase, Naohiko Iai, Hiroyuki Hamazumi and Kazuhiko Shibuya *1 *1 NHK Engineering System, Inc. As the satellite broadcasting of 4K/8K Super Hi-Vision is scheduled to start in 2018, the portable wireless contribution links for program production, which are used for electronic news gathering, outside broadcasting, etc., must be adapted to the 4K/8K format. We upgraded a HD (2K) microwave contribution link system particularly used for fixed and line-of-sight transmissions to adapt it to 4K/8K operations by increasing the transmission capacity. A 200-Mbps-class transmission capacity was achieved by enhancing the spectral efficiency while keeping the conventional channel bandwidth (18 MHz). To enhance the spectral efficiency, we employed dualpolarized MIMO (Multiple-Input Multiple-Output) using both horizontal and vertical polarizations and OFDM (Orthogonal Frequency Division Multiplexing) with higher-order modulation. We conducted outdoor experiments using a preliminary prototype built halfway through the development and proved the feasibility of the technologies by successful transmission of 8K video and audio signals over 50 km. 1. Introduction NHK has been conducting R&D on 4K/8K Super Hi- Vision, a television broadcasting service that will provide highly realistic, ultrahigh-definition images. Test satellite broadcasting of 4K/8K Super Hi-Vision began in 2016, and preparation to begin regular service in 2018 is in progress. This also generates a need to upgrade field pick-up units (FPUs) to 4K/8K. These are portable radio transmission devices that can quickly transmit live coverage or program materials for reporting or program production from venues around the country to the broadcast studio. Upgrading FPUs to 4K/8K involves increasing their transmission capacity so that they can transmit 4K and 8K video and audio signals (4K/8K signals), which require more capacity than HD signals. Microwave band (6-7 GHz) FPUs are used for most current HD reporting and program production. This microwave band is not strongly affected by rain and can be transmitted over distances up to 50 km, making efficient FPU operation possible. To maintain the same efficient operability with FPUs used for 4K/8K reporting and production (4K/8K FPUs), the FPUs must be upgraded to 4K/8K while still using microwave band frequencies. There is also a need to introduce 4K/8K FPUs smoothly while maintaining the existing microwave band channel allocations so that the operation of current HD FPUs can continue. Thus, technology is needed to increase spectral efficiency and dramatically increase transmission capacity without changing allocated channel bandwidths. In earlier research on technologies to increase spectral efficiency for next-generation digital terrestrial broadcasting 1)-3), dual-polarized multiple-input multiple-output (MIMO) and orthogonal frequency division multiplexing (OFDM) with higher-order modulation were found to be able to dramatically increase the transmission capacity while maintaining digital terrestrial television broadcasting bandwidths (6 MHz). From the perspective of increasing capacity, the application of this technology in FPUs is a promising option. The authors have studied increasing the transmission capacity by applying dual-polarized MIMO and OFDM with higher-order modulation to upgrade microwave-band FPUs to 4K/8K. This article discusses a microwave band 4K/8K FPU system that we have developed and reports on field transmission tests performed to confirm its feasibility. 2. Microwave band 4K/8K FPU system 2.1 Technical requirements for transmission capacity, frequency, and power To transmit 4K/8K signals using limited frequency resources, as with current HD systems, the compression coding of video and audio signals is unavoidable. Using H.265/ HEVC (High Efficiency Video Coding), the latest video compression encoding, a bit rate of between 100 and 300 2

Mbps would be needed to transmit a 4K/8K signal 4). Current HD FPUs have a transmission capacity of approximately 60 Mbps, so the transmission capacity must be increased by a factor of 2 to 5. To maintain the same operability of current FPUs, the same channel bandwidth of 18 MHz in the C (6.425-6.570 GHz) and D (6.870-7.125 GHz) bands is preserved. Also, to prevent new interference with existing radio systems, including current FPUs, the maximum transmission power is set at 5 W, the same as for current FPUs (although it is set to 0.2 W if an analog FPU is operating in an adjacent channel). The proposed system described below will use horizontal and vertical polarizations simultaneously, so the transmission power refers to the total power of both polarized signals. To summarize, the transmission capacity must be increased by a factor of 2 to 5 while maintaining current regulations of bandwidth and transmission power. 2.2 Overview of technologies to increase spectral efficiency Technologies to increase spectral efficiency, including dual-polarized MIMO and OFDM with higher-order modulation, had already been developed for next-generation terrestrial broadcasting research and were employed for the 4K/8K FPU. Dual-polarized MIMO is a technology that uses two orthogonally polarized waves to provide double the transmission capacity of current FPUs, which use a single polarization. Interference between the polarizations of the orthogonally polarized signal components can be canceled using MIMO detection *1. OFDM with higher-order modulation increases the number of modulation levels used for the quadrature amplitude modulation (QAM) of subcarriers from 64QAM, as used by current FPUs (Fig. 1 (a)), to 1024QAM (Fig. 1 (b)) or 4096QAM. This increases the number of bits transmitted with each carrier symbol from 6 bits to 10 bits or 12 bits, increasing the transmission capacity by a factor of 1.7 to 2. The transmission capacity was further increased by increasing the number of points used for fast Fourier Transforms (FFTs) from the current 2,048 to 8,192, increasing the effective symbol length relative to the guard interval (GI) length (Fig. 2), and by reducing the number of pilot signals. The transmission capacity can be increased by a factor of 2 to 5 by combining the above technologies. Note that to minimize the increase in the required carrier-to-noise ratio (C/N) as a result of increasing the number of modulation levels, instead of convolutional and Reed-Solomon concatenated coding used in current FPUs, a low-density parity check (LDPC) and Bose-Chaudhuri-Hocquenghem (BCH) concatenated coding is used as the forward error correction (FEC). * 1 With MIMO, the multiple transmitted signals arrive at the receiver having interfered with each other along the propagation path. The process of reconstructing the originally transmitted signals from multiple received signals is called MIMO detection. Generally, known signals are used to estimate the propagation path and the results are used to estimate the transmitted signals. Carrier orthogonal component amplitude Carrier in-phase component amplitude 64 (2 6 ) constellation points 64QAM (Current HD FPU) 1024 (2 10 ) constellation points 1024QAM (a) Figure 1: Increasing number of constellation points for subcarrier modulation (b) 3

Guard interval Effective symbol interval Number of FFT points: 2,048 100.14 µs 12.5 µs Number of FFT points: 8,192 400.57 µs 12.5 µs 8.3% improvement Time axis Figure 2: Increased transmission efficiency by increasing number of FFT points 2.3 4K/8K upgraded microwave band FPU system A photograph of the microwave band 4K/8K FPU introducing the advanced technologies discussed above is shown Table 1: Microwave band 4K/8K FPU transmission parameters Item Specification FFT size Occupied bandwidth (MHz) Carrier interval (khz) 2,048 17.21 9.99 8,192 17.20 2.50 Total 1,723 6,889 Data carriers 1,428 6,426 Number of carriers Pilot (CP/SP) *1 216/217 216/217 TMCC *2 16 64 AC *3 62/61 182/181 Subcarrier modulation FFT sampling clock (MHz) Effective symbol length (µs) Guard interval length (µs) Symbol length (µs) Number of symbols/ofdm frame OFDM frame length (ms) Inner code Outer code MIMO-supporting CP/SP carrier multiplication coefficient *4 64QAM, 256QAM, 1024QAM, 4096QAM 20.450743 100.14 400.57 12.52 12.52 112.66 413.09 440 440 49.57 181.76 LDPC code (Approx. code rates R =1/2, 2/3, 3/4, 5/6) BCH code SP: Horiz. (1,0), Vert. (0,1) CP: Horiz. (1,1), Vert. (1,-1) *1 CP: Continual Pilot, SP: Scattered Pilot *2 Transmission Multiplexing Configuration and Control *3 Auxiliary Channel *4 In parenthesis: (even-symbol multiplier, odd-symbol multiplier in Fig. 3. Block diagrams for this system are shown in Fig. 4 and the transmission parameters and the realized transmission bit rates are given in Tables 1 and 2, respectively. This system is based on the standards used for current OFDM FPUs, ARIB STD-B33 5) and STD-B57 6). The system is described in this section in order of the signal flow. (1) Converting input signals to FEC blocks In Fig. 4 (a), the input signal is an MPEG-2 transport stream (TS), with video and audio compression encoding Table 2: Microwave band 4K/8K FPU transmission rates 4

Transmitter radio-frequency head Modulator Dual-polarized antennas Receiver radio-frequency head Demodulator using H.256/HEVC (or other) and multiplexing, so this TS is first converted to FEC blocks. The FEC block structure is shown in Fig. 5. The TS is a continuous stream of fixed-length, 188-byte packets (TS packets), which are stored in the payload part of the FEC block. They are stored in a similar way to that used in the transmission method for advanced wideband digital satellite broadcasting (ARIB STD-B44 7) ), i.e., as a sequence of 187 bytes, excluding the synchronization byte (1 byte) at the beginning of the TS packet. The bits per field in the FEC block structure are shown in Table 3. The number of TS Modulator Figure 3: Microwave 4K/8K FPU OFDM frame composition IFFT and add GI MPEG-2 TS signal input FEC block config. BCH coding Time inter-leaving Energy dispersal LDPC coding Bit interleaving Symbol mapping Frequency/ polarization interleaving Pilot TMCC signal, etc. Time inter-leaving OFDM frame composition IFFT and add GI Quadrature modulation frequency head Quadrature modulation frequency head Dual-polarized antenna (a) Transmitter system frequency head Dualpolarized antenna frequency head Quadrature modulation Quadrature modulation GI removal FFT Extract pilot signal, etc. GI removal FFT MIMO detection Time de-interleaving Time de-interleaving Frequency/polarization deinterleaving Symbol demapping LLR computation Bit de-interleaving LDPC decoding Inverse energy dispersal Demodulator BCH decoding TS packet extraction MPEG-2 TS signal output (b) Receiver system Figure 4: Microwave band 4K/8K FPU transmitter/receiver systems 5

packets that can be stored in the payload depends on the code rate of the error correction code used. The parity for the outer code, BCH, computed from the header and payload is added. Stuff bits (6 bits) are also added, and energy dispersal is applied so that not too many consecutive 0 or 1 bits occur. The parity for the inner code, LDPC, is added to compose the 44,880-bit FEC block. Current FPUs 5)6) use a convolutional code for the inner code, so after error correction coding, it is a continuous, uninterrupted bit stream. Conversely, with the new FPU, a block code is used for the inner code, so processing can be carried out in FEC blocks as shown in Fig. 5. Thus, error correction coding and decoding can be performed in parallel, making it relatively easy to increase throughput. (2) Bit interleaving and subcarrier modulation To increase the performance of LDPC decoding, bit interleaving is carried out on FEC blocks in accordance with the subcarrier modulation scheme. Then symbol mapping *2 in accordance with the subcarrier modulation scheme is applied to the bit sequence to obtain 44,880/log2M carrier symbols per FEC block (M is the number of modulation levels). (3) Frequency/polarization interleaving and time interleaving The carrier symbols are lined up along the frequency axis (carrier direction) and interleaved between subcarriers and * 2 The process of assigning a bit pattern to a constellation point. polarizations. This distributes errors so that the error correction performance can be obtained at the receiver, even if there is frequency-selective fading due to multipath signals or differences in received power between the two polarizations. Then, time interleaving is performed in the time direction, giving a different delay to each carrier. This distributes errors due to fading, which causes the received power to drop momentarily. (4) OFDM frame composition Next, pilot signals, transmission and multiplexing configuration control (TMCC) signals, and auxiliary channel (AC) signals are added to compose OFDM frames. OFDM frames are composed for both the horizontally and vertically polarized signals. The TMCC signal includes a synchronization signal for OFDM frames and informs the receiver of the subcarrier modulation scheme used and other information. The AC signal is used to transmit information added by the user. The pilot signal is a signal known to the receiver, which is used to estimate the propagation channel. Sending a sequence of orthogonal pilot signals on the horizontally and vertically polarized signals enables the receiver to perform MIMO detection. The number of data carriers and the number of frame symbols are chosen such that FEC blocks fit in an OFDM frame without waste for all subcarrier modulation schemes. Thus, Number of data carriers Number of frame symbols log 2 M = n 44,880 (for integer n). (1) Therefore, OFDM frame synchronization enables immedi- Header Payload BCH code parity Stuff bits LDPC code parity Energy dispersal scope Figure 5: FEC block structure Table 3: FEC block structure bits Header Pilot LDPC code rate (Approx. code rate R) 61/120 (1/2) 81/120 (2/3) 89/120 (3/4) 101/120 (5/6) 176 176 176 176 22,440 29,920 32,912 37,400 BCH code parity 192 192 192 192 Stuff bits 6 6 6 6 LDPC code parity 22,066 14,586 11,594 7,106 Total length 44,880 44,880 44,880 44,880 6

ate start of error correction decoding and TS packet extraction. With current FPUs, a superframe is composed of eight OFDM frames 5)6). Because of this, it is necessary to receive up to eight OFDM frames before the extraction of TS packets can begin. With the new FPU, the FFT size is increased to 8,192 points, increasing the symbol length and frame length, but the start of every OFDM frame always coincides with the start of a TS packet, so TS packet extraction can begin after about the same duration as for current FPUs. (5) Transformation to time-domain signal and radiofrequency head The OFDM frame composed in the previous step is converted to time-domain signals one symbol at a time by an inverse FFT (IFFT), and the GI is added. Then, quadrature modulation is performed to obtain intermediate-frequency signals for horizontally and vertically polarized signals. In the radio-frequency head, the intermediate-frequency signals are converted to microwave-band-radio-frequency signals and transmitted as horizontally and vertically polarized signals from the dual-polarized antenna. A high-efficiency dual-polarized splash-plate feed *3 parabolic antenna is used. This antenna is able to send and receive both horizontally and vertically polarized signals using a polarization separator. We were able to improve the antenna efficiency while using the same parabolic reflector as for earlier antennas 8). (6) Reception process The reception process is basically the reverse of the transmission process. The propagation channel is estimated from the received pilot signals, and through MIMO detection, any cross-polarization interference occurring on the propagation path is canceled, and the symbols transmitted on horizontally and vertically polarized signals are estimated. It is assumed that the system will be used in line-of-sight environments where cross-polarization discrimination *4 will not degrade much, so a zero-forcing method, 9)*5 which requires less computation, is used for MIMO detection. In the demapping of the received symbols, the log-likelihood ratio (LLR) *6 is computed as the soft decision value for LDPC decoding. 3. Field transmission testing To test the feasibility of the microwave-band 4K/8K FPU, we conducted long-range transmission field tests. These tests were conducted while the R&D was still in progress, using basic test equipment with slightly different modulator and demodulator specifications from those of the system described in the previous sections. 3.1 Test equipment specifications The specifications of the basic test equipment used in these tests are given in Table 4. The OFDM carrier arrangement was based on the carrier arrangement in ISDB-T (used for digital terrestrial television broadcasting) 10) mode 3 (8,192 FFT points), with pilot signals modified for MIMO detection and other changes such as the total number of carriers. For subcarrier modulation, 64QAM to 4096QAM higher-order modulation was * 4 An index of the degree of discrimination between two orthogonally polarized signals. For example, when receiving a horizontally polarized signal, it is the ratio of the received power of the horizontally polarized component to the received power of the vertically polarized component that has leaked in. * 5 In this case, the MIMO propagation channel is expressed as a 2 2 matrix, and the transmitted signals are found by multiplying the two received signals by the inverse of this matrix. This requires the least computation among the MIMO detection methods. * 6 A value expressing the log of the ratio of the probability that the received bit is a zero to the probability that it is a one. Table 4: Main specifications of basic test equipment Item Specification * 3 A feed with an emitter that has a structure with a metal plate at the end of a waveguide separated by a dielectric material. 7

Table 5: Basic test equipment transmission rates used. The LDPC and BCH codes used were different from those described in the previous section but had very similar performance. The LDPC code (code length 64,800 bits) and BCH code from the DVB-T2 standard 11) were used. The transmission rates achieved with these transmission parameters are shown in Table 5. In order to support higher-order modulation, improvements were made to the radio-frequency head to obtain better frequency stability and phase noise characteristics than those of current microwave-band FPUs. For the antenna, the emitter used with the current FPUs was replaced with a splash-plate feed emitter to create dualpolarized parabolic antennas (with diameters of 0.6 m and 0.9 m) 8). 3.2 Test description and systems An overview of the test systems is shown in Fig. 6. The transmission distance was set to be farther than the standard link distance of 50 km set in the current FPU requirements 5). The transmitter was located at the Dodaira Observatory in Tokigawa Town, Hiki District, Saitama Prefecture, and the receiver was approximately 59 km away at the NHK Broadcast Center in Shibuya Ward, Tokyo. Transmission was in the D band and the antenna power was 0.2W (0.1 W per polarization). At the receiver, a variable attenuator was placed between the antenna and the radio-frequency head, enabling us to measure the relationship between the reception power and bit error rate. A codec supporting H.265/HEVC was not available at the time of these tests, so we inputted a 180 Mbps MPEG-2 TS 8K signal compressed using an H.264/AVC (Advanced Video Coding) encoder into the modulator, transmitted it, and used an H.264/AVC decoder for the output from the demodulator at the receiver to check the video on a monitor. We also recorded the received intermediate-frequency signals with a wave- Transmitter: Dodaira Observatory (Saitama Prefecture) Receiver: NHK Broadcasting Center (Shibuya Ward, Tokyo) 4K/8K FPU (transmitter) 4K/8K FPU (receiver) TS player Modulator Dual-polarized parabolic antenna frequency head (H,V) 59km H,V polarization Dual-polarized parabolic antenna VATT frequency head (H,V) Demodulator Bit error rate tester Video decoder Monitor Waveform recorder VATT: Variable attenuator H, V: horizontal/vertical polarizations Figure 6: Systems for field test using basic test equipment 8

form recorder so that we could analyze the propagation channel. 3.3 Test results We first measured the received power with the variable attenuator set to 0 db. During the test, the weather was clear and we measured values of -65 dbm when using the 0.6 m antenna and -62 dbm when using the 0.9 m antenna. These values are approximately 1.5 db lower than the values estimated by link budgets assuming free space propagation but are appropriate considering factors such as the systematic error in the measurement system, losses due to the error in the antenna direction, the plastic dome placed over the receiver, and signals reflected off the ground. We then measured the bit error rates while the attenuator setting was changed. These measurements and the results of prior laboratory tests are shown together in Fig. 7. For simplicity, Fig. 7 only shows the results for three sets of transmission parameters having transmission rates near 200 Mbps *7. The field test results show a degradation of approximately 1 db compared with the lab results, but this difference can be accounted for by considering the error due to differences in the measurement systems (in the lab, the error was measured by adding noise, while in the field, the input power was attenuated) and the effects of the propagation channel, including the antenna. The measured results in Fig. 7 show that transmission Bit error rate 10 0 10-1 10-2 10-3 10-4 10-5 10-6 10-7 1024QAM R=3/4 Field test Lab test 0.6m Parabolic reception power (VATT=0dB) 1024QAM R=5/6 0.9m Parabolic reception power (VATT=0dB) 4096QAM R=3/4 10-8 -80-75 -70-65 -60 Reception power [dbm] Figure 7: Reception power and bit error rate measurement results over 59 km is possible for parameters permitting transmission near 200 Mbps (1024QAM, R=5/6) with transmission margins of approximately 2.5 db when using the 0.6 m antenna and 5.5 db when using the 0.9 m antenna. Note that the 0.9 m antenna was still under development when these experiments were performed, and the gain of this antenna can be increased, meaning that the transmission margin can also be increased. We also transmitted an actual 8K signal from the TS player and confirmed that 8K video could be properly received on the monitor at the receiver, verifying the operation of the 4K/8K FPU. To check the propagation channel state using both horizontally and vertically polarized signals, we extracted the OFDM pilot signals from the received and recorded intermediate-frequency signals and computed the channel response for each subcarrier. The results are shown in Fig. 8 (a). To cancel the characteristics of devices such as the radio-frequency head, we performed a calibration with the principal-polarization components *8 obtained in the laboratory tests. Figure 8 (a) shows the propagation channel responses for 5,617 of the 6,865 carriers, for which a valid propagation channel could be estimated, with lower carrier numbers corresponding to lower frequencies. From Fig 8 (a), we can see that the principal-polarization components (H- H, V-V) have gently sloped response, but there is almost no difference between horizontally and vertically polarized signals. We consider that this frequency response is due to the characteristics of the antenna and polarization separator. The cross-polarization components (H-V, V-H) were in the range of -20 to -25 db, but the cross-polarization discrimination of the antenna itself is approximately 30 db, so there may also have been some mismatch in the alignment of the facing transmit and receive antennas. The condition numbers *9 for each subcarrier, calculated from the propagation channel responses, are also shown with the laboratory test values in Fig. 8 (b). For most of the subcarriers, the field test values were slightly degraded * 7 For Fig. 7, the variable attenuator could only be adjusted in 1 db intervals, but the bit error rate dropped sharply with only a small increase in the reception power. For this reason, at reception power settings with bit error rates below 10-3, errors were not detected and an estimation of the line is shown. * 8 Of the signals transmitted with a horizontally (or vertically) polarized wave, the signal component received with the horizontally (or vertically) polarized wave. 9

Propagation channel response (db) 0-5 -10-15 -20-25 H-H H-V V-H V-V Condition number (db) 1 0.8 0.6 0.4 0.2 Field test Lab test -30 0 1,000 2,000 3,000 4,000 5,000 0 0 1,000 2,000 3,000 4,000 5,000 Carrier number Carrier number (a) Propagation channel response (b) Condition number Figure 8: Per-carrier propagation channel responses and condition number from the laboratory results, but the values were below 0.6 db. This shows that polarization separation with almost no degradation due to noise accentuation was possible, even using the zero-forcing method, which is a simple MIMO detection method. We performed a computer simulation using the measured channel responses to estimate the degradation in the bit error rate characteristics and found that the field test characteristics were degraded by approximately 0.4 db (1024QAM, R=5/6) compared with the laboratory test characteristics. Thus, the degradation of approximately 1 db in Fig. 7 can be considered reasonable. These results suggest that there was no significant degradation in cross-polarization discrimination for the clear weather propagation in these tests. It will be necessary to take further measurements in the future to clarify the effects of factors such as rainy weather and long term changes. * 9 This refers to the ratio between the larger and smaller eigenvalues of the 2 2 matrix representing the MIMO propagation channel. The smaller this ratio, the less susceptible the channel is to noise. 4. Summary To enrich 4K/8K Super Hi-Vision broadcast programs, we have developed a portable microwave band field pickup unit (FPU) supporting 4K/8K. Currently, each broadcaster operates HD FPUs using different channels in the microwave band. In order to introduce 4K/8K FPUs smoothly without changing these channel allocations, we have improved spectral efficiency to increase the transmission capacity, so that 4K/8K video and audio signals can be transmitted while maintaining the current 18 MHz channel bandwidth. We introduced dual-polarized MIMO and OFDM with higher-order modulation technologies to increase spectral efficiency, achieving a transmission capacity of up to 300 Mbps. We also verified the ability to transmit 8K video and audio signals with a transmission power of 0.2 W at distances over 50 km in field transmission tests. We will continue to develop practical devices, so that operation can begin in time for the full-scale dissemination of 4K/8K broadcasting services expected in 2020. Acknowledgements We offer thanks to the Town of Tokigawa, Hiki District, Saitama Prefecture for willingly allowing the use of the Dodaira Observatory as the transmitter location for these field tests and to all persons involved. This article was revised and amended on the basis of the following report appearing in ITE Technical Report. H. Kamoda, T. Kumagai, T. Koyama, S. Okabe, K. Shibuya, N. Iai, H. Hamazumi: Long-haul transmission experiments of a microwave link system for Super Hi-Vision, ITE Technical Report, Vol. 40, No. 4, BCT2016-28, pp. 45-48 (2016). 10

References 1) K. Murayama: High-capacity transmission method for nextgeneration terrestrial broadcasting, NHK STRL R&D, No. 136, pp. 8-15 (2012). 2) S. Asakura, K. Murayama, M. Taguchi, T. Shitomi, K. Shibuya: Technology for the next generation of digital terrestrial broadcasting : Transmission characteristics of 4096QAM-OFDM, ITE Technical Report, Vol. 35, No. 10, pp. 43-46 (2011). 3) S. Asakura, K. Murayama, M. Taguchi, T. Shitomi, K. Shibuya: Technology for next generation of digital terrestrial broadcasting: A study of multi dimensional interleaving, ITE Technical Report, Vol. 36, No. 6, pp. 53-58 (2012). 4) Information and Communications Council, Information and Communications Technical Subcommittee, Broadcast Systems Committee Report (Draft): Technical Requirements for Microwave-band Stations (FPUs) used by Broadcasters for Ultrahigh-definition Television Broadcasting from Technical Requirements for Advancing Stations for use by Broadcasters in Question No. 2023 Technical Requirements for Broadcast Systems, http://www.soumu.go.jp/main_content/000467275.pdf (2017). 5) ARIB: Portable OFDM Digital Transmission System for Television Program Contribution, ARIB STD-B33, Ver. 1.2 (2011). 6) ARIB: 1.2GHz/2.3GHz-Band Portable OFDM Digital Transmission System for Television Program Contribution, ARIB STD-B57 Ver. 2.0 (2016). 7) ARIB: Transmission System for Advanced Wide Band Digital Satellite Broadcasting (ISDB-S3), ARIB STD-B44 Ver. 2.1 (2016). 8) T. Kumagai, K. Mitsuyama, N. Kogo, N. Iai: A dual-polarized parabolic antenna with splash-plate for bidirectional FPU, Proceedings of the IEICE General Conference, B-11-5, p. 422 (2015). 9) J. Barry, E. Lee, D. Messerschmitt: Digital Communication, 3rd Edition. Springer US, New York (2004). 10) ARIB: Transmission System for Digital Terrestrial Television Broadcasting, ARIB STD-B31 Ver. 1.9 (2010). 11) ETSI EN 302 755 V1.3.1, Digital Video Broadcasting (DVB); Frame Structure Channel Coding and Modulation for a Second Generation Digital Terrestrial Television Broadcasting System (DVB-T2) (2012). 11