PHY2: Emerging Transmission Techniques for Next Generation Wireless Communication Systems

Wednesday, 17 June 2020, 12:15-14:30 CEST, Recommended re-viewing,

Wednesday, 17 June 2020, 12:15-16:00 CEST, Non-Live interaction (Chat),  link sent only to Registered people


EXIT Chart Analysis of Cooperative Non-Orthogonal Multiple Access for Next Generation Wireless Communication Systems

Zeyad Elsaraf, Abbas Ahmed, Faheem A. Khan and Qasim Zeeshan Ahmed (University of Huddersfield, United Kingdom (Great Britain))
Non-orthogonal multiple Access (NOMA) has garnered considerable attention as a prime candidate for the next generation of wireless communication systems due to its improvement of spectral efficiency. The proposed model exploits one of NOMA’s key features, namely of users having to decode other users messages before decoding their own as part of successive interference cancellation (SIC). The purpose of the proposed model is to utilize such prior knowledge to allow
users to cooperate with other users through their relaying of information, thereby increasing the overall diversity gain and, by extension, each user’s data rate. The main focus of this paper is to asses the proposed model for a multi-user case. The performance comparison between the bit error rate (BER) versus
signal-to-noise ratio (SNR) is evaluated along with the data rate experienced at each user with independent Rayleigh fading. User fairness is also analysed through the implementation of extrinsic information transfer (EXIT) charts. Furthermore, expressions for the data rates at each user are derived independently and used to supplement the experimental data.


Feedback Enhancements for Semi-Persistent Downlink Transmissions in Ultra-Reliable Low-Latency Communication

Trung-Kien Le (EURECOM, France); Umer Salim (TCL, France); Florian Kaltenberger (Eurecom, France)
Ultra-reliable low-latency communication (URLLC) is one of the new service categories specified by The 3rd Generation Partnership Project (3GPP) that will be used for the applications with the strict reliability and latency requirements. To satisfy these requirements in Release 16, URLLC downlink (DL) transmission can be scheduled in the semi-persistent scheduling (SPS) resources to reduce control overhead and a retransmission if necessary is triggered by hybrid automatic repeat request (HARQ) feedback transmitted in uplink (UL) resources. However, in time division duplex (TDD) mode, HARQ feedback is dropped when there are no available UL resources for physical uplink control channel (PUCCH) in the indicated slot/sub-slot because that slot/sub-slot contains DL symbols in semi-static TDD configuration or flexible symbols updated to DL symbols in dynamic TDD configuration. Dropping the feedback results in a degradation of DL SPS quality of service (QoS) and may not be acceptable for URLLC based services and applications. This paper provides a scheme to guarantee the transmission of HARQ feedback and potential data retransmission when there is UL-DL slot/sub-slot conflict at the indicated feedback resource. The scheme comprises a dynamic indication of feedback resource without using an associated downlink control information (DCI). An acknowledgement (ACK)-only feedback protocol is proposed to best suit the scenario in question. The combination of dynamic indication of feedback resource and ACK-only feedback structure guarantees higher reliability and brings flexibility to the transmission of HARQ feedback as confirmed by the simulations.


RFF Based Parallel Detection for Massive MIMO

Varun Chhangani (Research Student, IIIT Hyderabad, India); Rangeet Mitra (ETS Montreal, Canada); Vimal Bhatia (Indian Institute of Technology Indore, India)
Multi user massive multiple input multiple output (MU-m-MIMO) has emerged as a viable technology for scaling up existing communication systems, and in serving increasing number of users for the next-generation communication systems. Several signal processing algorithms exist for mitigating the performance-limiting artefacts encountered in MU-m-MIMO systems (like inter-symbol interference, inter-channel interference, and device nonlinearities), among which, reproducing kernel Hilbert space (RKHS) based approaches have emerged to provide effective solutions. However, most of the existing RKHS based detectors for MU-m-MIMO are dictionary-based, which makes it difficult to gauge the memory requirements beforehand, and are prone to error in the presence of noisy observations. Hence, to reduce the computational complexity, a Random Fourier Features (RFF) based parallel detection algorithm is proposed for MU-m-MIMO, that uses decomposed blocks of high dimensional observations, and makes the proposed detector scalable for parallel computation using modern multi-core compute-units at the receivers (which is possible today due to advances in computing). Further, the RFF based explicit feature map to RKHS alleviates the requirement of a dictionary, and facilitates ease of practical implementation. Simulations are performed over realistic MU-m-MIMO systems, which indicates that the proposed approach delivers an acceptable uncoded BER performance, whilst maintaining a finite implementation budget, which makes the proposed approach attractive for implementation. Lastly, the the error-rate analysis of the proposed detector is performed, and validated through simulations.


Enhanced Bit-to-Symbol Mapping for M-ary θ-QAM

Seongjin Ahn, Hyeonho Seo and Dongweon Yoon (Hanyang University, Korea (South))
In conventional bit-to-symbol mapping for θ-QAM, the Hamming distance between the symbols with the minimum Euclidean distance is not minimized when θ < 60°, and this undesirably increases the bit error rate (BER). In this paper, we propose an enhanced bit-to-symbol mapping for M-ary θ-QAM, which minimizes the Hamming distance between the symbols with the minimum Euclidean distance even when θ < 60°. By adopting the conventional mapping when θ ≥ 60° and the proposed mapping when θ < 60°, we formulate the overall bit-to-symbol mapping for θ-QAM. To validate the proposed bit-to-symbol mapping, we compare the BERs of the proposed mapping and the conventional one through computer simulations.


Experimental Assessment of Modulation Formats for Beyond 5G mm-Wave ARoF Systems

Javier Perez Santacruz, Alvaro Morales, Simon Rommel and Ulf Johannsen (Eindhoven University of Technology, The Netherlands); Antonio Jurado Navas (University of Málaga, Spain); Idelfonso Tafur Monroy (Eindhoven University of Technology, The Netherlands)
Fifth-generation (5G) mobile network consists of a broad service variety of joined to fulfill different and exigent requirements. To reach this, analog radio over fiber (ARoF) fronthaul with millimeter-wave (mm-wave) cells is a firm candidate to be part of the 5G architecture. Nonetheless, combined mm-wave and ARoF systems presents big drawbacks such as high free-space path loss (FSPL), phase noise, chromatic dispersion, and other debasing effects. Therefore, the selection of the modulation format is crucial to reduce these effects. This work compares and analyzes different modulation formats in this type of system in order to choose the best waveform candidate for mm-wave 5G and beyond with ARoF fronthaul. An experimental comparison of OFDM, SC-FDM, UFMC, GFDM, and multi-CAP, shows that the standard OFDM may not be the best choice for mm-wave 5G.