Multiple-input Multiple-output Wireless Link Research Articles

4096-QAM OFDM THz-Over-Fiber MIMO Transmission Using Delta-Sigma Modulation

A terahertz (THz)-over-fiber multiple-input multiple-output (MIMO) transmission of 4096-ary quadrature amplitude modulation (QAM) orthogonal frequency division multiplexing (OFDM) supported by 46-GBaud quadrature phase shift keying (QPSK) signal at 320 GHz is experimentally demonstrated in this letter. By employing the polarization division multiplexing (PDM) technique and 1-bit delta-sigma modulation (DSM) quantization, we successfully implement 4.6-GHz 4096-QAM OFDM signal transmission over 20 km of standard single-mode fiber (SSMF) and a 3-m MIMO wireless link, and satisfy the soft-decision forward error correction (SD-FEC) threshold of 1.0 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> with 15% overhead, which corresponds to a net rate of 84.4 Gbps for THz-over-fiber transmission. To the best of our knowledge, fusing OFDM and PDM, this is the highest rate achievable for DSM applications in THz communication. This experimental demonstration can provide a promising solution for high-order QAM signals in a fiber-wireless seamless network in future 6G networks.

Demonstration of Ultra-Capacity Wireless Signal Delivery at W-Band

High-speed long-haul wireless transmission links are required to meet the demand of mobile backhauling and emergency communications. We experimentally demonstrated ultra-high-speed 432-Gb/s polarization-division-multiplexing 16-ary quadrature amplitude modulation modulated W-band millimeter-wave (mm-wave) signal delivery over a 2-m horn antenna-based (HA-based) 4 × 4 multiple-input multiple-output (MIMO) wireless link, enabled by photonic mm-wave generation and optical/antenna polarization multiplexing. We further achieved the field trial demonstration of 80-Gb/s polarization-division-multiplexing quadrature phase shift keying modulated W-band mm-wave signal delivery over a 300-m Cassegrain antenna-based (CA-based) 4 × 4 MIMO wireless link, adopting photonic mm-wave generation, multi-band multiplexing, and optical/antenna polarization multiplexing. To the best of our knowledge, 80 Gb/s or 74.7 Gb/s after removing 7% forward-error-correction overhead is a record for W-band wireless signal delivery over a few hundred meters.

Fiber-wireless integration for 80 Gb/s dual-polarization-16 quadrature-amplitude-modulation signal transmission at Q-band

Abstract. We experimentally demonstrate a Q-band seamlessly integrated fiber-wireless system, where80 Gb∕s dual-polarization (DP) 16 quadrature-amplitude-modulation (DP-16QAM) is transmitted over 50-kmsingle-mode fiber-28 (SMF-28) wire link, 0.5-m 2×2 multiple-input multiple-output wireless link, and finally,another 50-km SMF-28 wire link. Conventional multimodulus-algorithm equalization is introduced at the receiverto realize polarization demultiplexing and to minimize crosstalk between the two polarizations. For the first time,we realize fiber-wireless integration signal transmission with high-order modulation (16QAM) and polarizationmultiplexing at Q-band. © 2014 Society of Photo-Optical Instrumentation Engineers (SPIE) [DOI: 10.1117/1.OE.53.10.106104] Keywords: optical communication; fiber-wireless integration; polarization multiplexing; 16 quadrature-amplitude-modulation.Paper 140783 received May 15, 2014; revised manuscript received Sep. 16, 2014; accepted for publication Sep. 17, 2014; publishedonline Oct. 9, 2014.

Optical-wireless-optical full link for polarization multiplexing quadrature amplitude/phase modulation signal transmission

We propose and experimentally demonstrate an optical wireless integration system at the Q-band, in which up to 40 Gb/s polarization multiplexing multilevel quadrature amplitude/phase modulation (PM-QAM) signal can be first transmitted over 20 km single-mode fiber-28 (SMF-28), then delivered over a 2 m 2 × 2 multiple-input multiple-output wireless link, and finally transmitted over another 20 km SMF-28. The PM-QAM modulated wireless millimeter-wave (mm-wave) signal at 40 GHz is generated based on the remote heterodyning technique, and demodulated by the radio-frequency transparent photonic technique based on homodyne coherent detection and baseband digital signal processing. The classic constant modulus algorithm equalization is used at the receiver to realize polarization demultiplexing of the PM-QAM signal. For the first time, to the best of our knowledge, we realize the conversion of the PM-QAM modulated wireless mm-wave signal to the optical signal as well as 20 km fiber transmission of the converted optical signal.

Multichannel 120-Gb/s Data Transmission Over 2$\,\times\,$2 MIMO Fiber-Wireless Link at W-Band

We experimentally demonstrated a seamlessly integrated fiber-wireless system that delivers multichannel 120-Gb/s data through 80-km fiber and 2-m 2×2 multiple-input multiple-output (MIMO) wireless link at 92-GHz W-band adopting polarization division multiplexing quadrature phase shift keying (PDM-QPSK) modulation. The three-channel 3×40-Gb/s optical PDM-QPSK signals with 12.5-GHz channel spacing are simultaneously upconverted to 92-GHz wireless carrier by optical polarization-diversity heterodyne beating and then transmitted and received by two pairs of transmitter and receiver antennas, which form a full 2×2 MIMO wireless link. At the wireless receiver, a two-stage analog and digital downconversion is performed. Polarization and wireless 2×2 MIMO demultiplexing are realized by constant modulus algorithm based on digital signal processing. The bit-error ratio performance for the 120-Gb/s PDM-QPSK signal is measured after 80-km single-mode fiber-28 and 2-m wireless transmission.

Investigation of interference in multiple-input multiple-output wireless transmission at W band for an optical wireless integration system

We experimentally investigate the interference in multiple-input multiple-output (MIMO) wireless transmission by adjusting the relative locations of horn antennas (HAs) in a 100 GHz optical wireless integration system, which can deliver a 50 Gb/s polarization-division-multiplexing quadrature-phase-shift-keying signal over 80 km single-mode fiber-28 and a 2×2 MIMO wireless link. For the parallel 2×2 MIMO wireless link, each receiver HA can only get wireless power from the corresponding transmitter HA, while for the crossover ones, the receiver HA can get wireless power from two transmitter HAs. At the wireless receiver, polarization demultiplexing is realized by the constant modulus algorithm (CMA) in the digital-signal-processing part. Compared to the parallel case, wireless interference causes about 2 dB optical signal-to-noise ratio penalty at a bit-error ratio (BER) of 3.8×10(-3) for the crossover cases if similar CMA taps are employed. The increase in CMA tap length can reduce wireless interference and improve BER performance. Furthermore, more CMA taps should be adopted to overcome the severe wireless interference when two pairs of transmitter and receiver HAs have different wireless distances.

Fiber-wireless transmission system of 108 Gb/sdata over 80 km fiber and 2×2multiple-input multiple-output wireless links at 100 GHz W-band frequency

We experimentally demonstrate a seamlessly integrated fiber-wireless system that delivers a 108 Gb/s signal through 80 km fiber and 1 m wireless transport over free space at 100 GHz adopting polarization-division-multiplexing quadrature-phase-shift-keying (PDM-QPSK) modulation and heterodyning coherent detection. The X- and Y-polarization components of the optical PDM-QPSK baseband signal are simultaneously upconverted to 100 GHz wireless carrier by optical polarization-diversity heterodyne beating, and then independently transmitted and received by two pairs of transmitter and receiver antennas, which form a 2×2 multiple-input multiple-output wireless link. At the wireless receiver, two-stage downconversion is performed firstly in the analog domain based on balanced mixer and sinusoidal radio frequency signal, and then in the digital domain based on digital signal processing (DSP). Polarization demultiplexing is realized by the constant modulus algorithm in the DSP part at the receiver. The bit-error ratio for the 108 Gb/s PDM-QPSK signal is less than the pre-forward-error-correction threshold of 3.8×10(-3) after both 1 m wireless delivery at 100 GHz and 80 km single-mode fiber-28 transmission. To our knowledge, this is the first demonstration to realize 100 Gb/s signal delivery through both fiber and wireless links at 100 GHz.

Experimental Demonstration of 48-Gb/s PDM-QPSK Radio-Over-Fiber System Over 40-GHz mm-Wave MIMO Wireless Transmission

In this letter, we demonstrate a 48-Gb/s polarization-division-multipexing (PDM) QPSK radio-over-fiber (RoF) system over 2 $\,\times\,$ 2 multiple-input–multiple-output (MIMO) wireless transmission. The PDM-QPSK signal is up-converted to a 40-GHz mm-wave and broadcasted through the 2 $\,\times\,$ 2 MIMO wireless system. The principle of the PDM-QPSK RoF system over 2 $\,\times\,$ 2 MIMO wireless transmission is presented. The conventional digital coherent demodulation algorithms for the compensation of chromatic dispersion, polarization demultiplexing and frequency offset, and phase recovery have been proved valid even if the 2 $\,\times\,$ 2 MIMO wireless transmission system is utilized. The BER performance after over 400-km fiber link and 100-cm wireless link clearly demonstrates the feasibility of this PDM-QPSK RoF system over 2 $\,\times\,$ 2 MIMO wireless link.

From theory to practice: an overview of MIMO space-time coded wireless systems

This paper presents an overview of progress in the area of multiple input multiple output (MIMO) space-time coded wireless systems. After some background on the research leading to the discovery of the enormous potential of MIMO wireless links, we highlight the different classes of techniques and algorithms proposed which attempt to realize the various benefits of MIMO including spatial multiplexing and space-time coding schemes. These algorithms are often derived and analyzed under ideal independent fading conditions. We present the state of the art in channel modeling and measurements, leading to a better understanding of actual MIMO gains. Finally, the paper addresses current questions regarding the integration of MIMO links in practical wireless systems and standards.