16-QAM OFDM-Based W-Band Polarization-Division Duplex Communication System with Multi-gigabit Performance

Abstract

This paper presents a novel 90 GHz band 16-quadrature amplitude modulation (16-QAM) orthogonal frequency-division multiplexing (OFDM) communication system. The system can deliver 6 Gbps through six channels with a bandwidth of 3 GHz. Each channel occupies 500 MHz and delivers 1 Gbps using 16-QAM OFDM. To implement the system, a low-noise amplifier and an RF up/down conversion fourthharmonically pumped mixer are implemented using a 0.1-μm gallium arsenide pseudomorphic high-electronmobility transistor process. A polarization-division duplex architecture is used for full-duplex communication. In a digital modem, OFDM with 256-point fast Fourier transform and (255, 239) Reed-Solomon forward error correction codecs are used. The modem can compensate for a carrier-frequency offset of up to 50 ppm and a symbol rate offset of up to 1 ppm. Experiment results show that the system can achieve a bit error rate of 10 -5 at a signal-to-noise ratio of about 19.8 dB.Keywords: W-band, PDD, OFDM, 10 Gigabit Ethernet, error correction code. Manuscript received Sept. 22, 2013; revised Feb. 10, 2014; accepted Feb. 13, 2014. Hyung Chul Park (corresponding author, hcpark@seoultech.ac.kr) is with the Department of Electronic and IT Media Engineering, Seoul National University of Science and Technology, Seoul, Rep. of Korea. I. IntroductionAs high-speed wireless data services, such as 3G/4G mobile communications, IEEE 802.11ac/ad wireless LAN, and wired Gigabit Ethernet, are becoming more widespread, multi-gigabit Ethernet networks are needed. Compared to wired multigigabit Ethernet networks, wireless multi-gigabit Ethernet networks have the advantage of an easy installation and low construction cost. bandwidth of 3 GHz. In our previous work, we presented a single carrier 16-QAM based E-band (71 GHz to 76 GHz and 81 GHz to 86 GHz) wireless point-to-point broadband communication system [7]. In the previous system, the FDD scheme was used because the spectrum is divided into a lower band (71 GHz to 76 GHz) and an upper band (81 GHz to 86 GHz). However, since a bandwidth of 3 GHz (92 GHz to 95 GHz) is allocated in the 90 GHz band, the proposed system herein utilizes a polarization-division duplex (PDD) architecture to achieve both full-duplex communication and a multi-Gbps data rate. By using a PDD scheme, the spectral efficiency of full-duplex communication can be increased by two times compared to that of the FDD-or TDD-schemebased existing millimeter wave wireless communication. In addition, an OFDM technique and equalizer are used to reduce the effects of inter-symbol interference caused by multipath propagation.II. System Architecture and Function Blocks Figure 1 and Table 1 produces 1 Gbps of binary data. Figure 2 shows a detailed block diagram of the RF/IF transceiver. In the IF transmitter, the digital-to-analog converted signal is low-pass filtered by a seventh-order Butterworth filter with a cutoff frequency of 288 MHz. A passive type I/Q mixer is used for the up conversion, with a conversion loss of 7 dB.Six IF channel sig...

16-QAM OFDM-Based K-Band LoS MIMO Communication System with Alignment Mismatch Compensation

“…We use a Xilinx Virtex‐7 XC7VX980T field‐programmable gate array (FPGA). The structure of the preamble is nearly identical to the one used in our previous study . However, because the FFT size is different from that in our previous study, the preamble code and the number of subcarriers for the preamble data are different.…”

“…If the receiver for the ideal LoS MIMO link is used and transmitter 2 (Tx2) does not transmit (x 2 (t) = 0), the receiver output is written as 3) Figure 3 shows the simulation and measurement results for the powers ofx 1 ðtÞ andx 2 ðtÞ, as well as the ratio between them. 4) In Fig. 3, the power ofx 2 ðtÞ is minimized when there is no amplitude difference (G 11 = G 21 ).…”

“…In particular, the first section in the preamble is used for the LoS MIMO alignment mismatch estimation and compensation, as well as for the signal detection and automatic gain control (AGC). Most of the modulation and demodulation techniques in our previous study are intended for use in a digital modem [4]. 7) For LoS MIMO communication, the cross-correlation of the first section of the preamble is used for LoS MIMO These are the modulation scheme, forward error correction (FEC) technique, signal detection, timing synchronization, carrier frequency offset compensation, and carrier phase recovery.…”

“…However, microwave backhaul links generally require line‐of‐sight (LoS) propagation. Various methods for improving spectral efficiency have been studied in previous works . Polarization division multiplexing (PDM), which employs independent datasets from two orthogonal polarizations (such as vertical and horizontal polarizations) at the same frequency to double the total data throughput, was used in .…”

“…Various methods for improving spectral efficiency have been studied in previous works . Polarization division multiplexing (PDM), which employs independent datasets from two orthogonal polarizations (such as vertical and horizontal polarizations) at the same frequency to double the total data throughput, was used in . Cross‐polarization isolation must be sufficiently large to improve the performance of PDM systems; this is accomplished by using two separate antennas , an orthomode transducer (OMT) device or a cross polarization interference cancellation (XPIC) algorithm .…”