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The perturbation-based nonlinearity compensation (NLC) method is considered in conjunction with a forward error correction (FEC) code that is capable of detecting block errors. The FEC decoding is performed prior to the NLC, and NLC is then performed only for blocks, that could not be decoded correctly. The total NLC complexity is thus dramatically reduced to down to 1% in some cases w.r.t. the standard, hard decision-directed NLC performed prior to the FEC decoding. Negligible FEC decoding complexity increase is required for the subsequent decoding of the nonlinearity-compensated blocks. The proposed method achieves and sometimes outperforms the standard perturbation based NLC at a fraction of the overall complexity. Polar codes are used to exemplify the method.

We experimentally demonstrate a rate-adaptive concatenated forward error correction (FEC) scheme to minimize the information rate loss due to varying channel conditions. The concatenated coding scheme is based on inner soft-decision polar code and outer hard-decision staircase code. An experiment in a wavelength-division multiplexed (WDM) system with different SNR per WDM channel is performed by employing concatenated codes with various coded modulation schemes over a target distance of 140km which is relevant for extending the reach of data center interconnects. Experimental results show that the achieved data rate of the WDM system can be improved up to 37.6% with the proposed coding scheme w.r.t. the fixed code rate ZR FEC.

In this paper, we consider fast decoding of soft-decision (SD) Hamming codes as inner codes in concatenated forward error-correction (FEC) schemes for high-speed optical communication. The goal is single FPGA implementations at speeds of 400 Gb/s and beyond. A low complexity maximum a posteriori (MAP) probability decoding is applied to a (128,120) Hamming code. Chase decoding of a (128,119) Hamming code is also implemented. The VHDL designs for both decoding schemes are presented. The FEC performance and FPGA resource utilization are investigated and compared. Synthesis results indicate that, both the Chase and the MAP decoder leave sufficient resources available to also accommodate a powerful outer hard decision code, on a single FPGA. Furthermore, MAP decoding of (128,120) Hamming code features lower hardware complexity and provides a higher data throughput.

In this work, a multilevel coding (MLC) based coded modulation scheme with two degrees of freedom in rate flexibility is proposed and compared with a bit-interleaved coded modulation (BICM) scheme from a performance versus complexity perspective. The proposed MLC scheme is based on a rate flexible inner soft-decision polar code and utilizes an outer hard-decision staircase code structure as in the 400ZR concatenated forward error-correcting code. The performance of the MLC scheme is investigated for a range of inner code lengths, inner decoder list sizes, and signaling with 16 and 64 quadrature amplitude modulation, respectively. The MLC is designed such that a portion of the staircase encoded bits can bypass the inner code. The number of required inner soft-decision decoders can thus be reduced, thereby saving computational complexity. The proposed MLC scheme simultaneously offers up to a 53.7% reduction in the number of inner decoders and up to 0.55 dB of performance improvement when compared with the similar BICM approach.

A radio-over-fiber (RoF) distributed antenna system (DAS) architecture is proposed, where millimeter wave (mm-wave) signals are transmitted to four different radio access units (RAUs) arranged in a ring topology. The proposed architecture transmits duplex data of 128 Mb/s to each RAU in both downlink (DL) and uplink (UL) directions. The radio frequency (RF) signals are transmitted by polarization multiplexing a multi-wavelength source. Millimeter-wave signals at a frequency of 25 GHz are generated at each RAU using remote heterodyne detection. The proposed architecture provides increased coverage while maintaining good bit error rate (BER) results.

An ultra-wideband over fiber architecture is proposed where multiple coherent pulsed optical signals are used for transmitting high data rate signals to five different radio access units (RAUs). The RAUs are placed in a star topology to form a broadcast distributive antenna system architecture. The architecture transmits $$5 \times 1.25$$5?1.25 Gbps data from control unit to the RAUs using a wavelength division multiplexed signal. The multiple pulsed optical carriers forming the wavelength division multiplexed signal are generated using a single continuous wave optical source. The data modulated coherent optical pulsed signals are all-optically converted to electrical Gaussian mono-cycle pulses at the RAUs. The proposed architecture is cost-efficient and gives good bit-error rate results.

We propose a duplex dual-ring Radio Over Fiber (ROF) architecture considering the limitations imposed by the cost of the optical/electronic components and of deployed fiber. The proposed architecture uses two light sources and a low-frequency local oscillator (LO) at central unit (CU) for simultaneously transmitting and receiving 25 GHz RF signals to (from) eight simplified Radio Access Units (RAUs) arranged in dual-ring topology. A sophisticated combination of Polarization Multiplexing (PM), Optical Frequency Comb (OFC) generation, wavelength division multiplexing (WDM), wavelength reuse, remote heterodyne detection (RHD) and distributed antenna system (DAS) is conceived. It has been shown through simulations that the proposed architecture covers a large geographical area while maintaining the transmission integrity which is evaluated using bit-error rate (BER) matrics.

In this paper, we have proposed the idea of designing a pyramidal conformal array antenna and install it on a moving vehicle. Uniform circular planar array is used and it is replicated to design pyramidal shape conformal array antenna. Single panel circular planar array at 72 degree and at 42 degree is used to build the array geometry of pyramidal shape conformal array. By using circular arrays at 42 degree and at 72 degree the 3-D radiation pattern of pyramidal conformal array antenna has been shown. By using same pyramidal conformal array antenna with different phase slopes the idea of tracking target in the air and on ground is introduced. The applications of pyramidal conformal phased array radar system in defense and in automotive industry are presented in the end.

International audience; A decentralized link adaptation algorithm designed for multi-link MIMO interference systems to jointly optimize the power and the number of links is presented in this contribution. Game theory is adapted and used for both allocating resources and admitting users (i.e. with embedded congestion control). The MIMO interference system is mapped into a multi-player game. The solution of the proposed game is provided by a new gradient based decentralized link adaptation algorithm. The new algorithm allocates adaptively the power and the modulation scheme of the transmitter and maintains the optimum number of links using soft decision criteria based on the link metric. Each link decision depends on the type of traffic and the QoS requirements. An analytical framework is provided along with simulations and an analysis of the algorithm behavior under different system conditions. This type of algorithm is applicable to spectrum sharing and power management to reduce interference and energy consumption