• Tuesday, 13 June, 11:30-13:00, Room Libray Auditotium
• Session Chair: Markku Juntti (University of Oulu, Finland)

11:30 Energy-efficient Joint Source and Relay Precoding Design for Cooperative MIMO-AF Systems

Fabien Héliot and Rahim Tafazolli (University of Surrey, United Kingdom (Great Britain))

This paper derives the optimal source and close-to-optimal relay precoding structure for minimizing the energy consumption of cooperative multiple-input-multiple-output (MIMO) amplify-and-forward (AF) systems, i.e. when relay and direct links are jointly considered. Even though the optimisation problem at hand is generally non-convex, we prove that the energy consumption optimisation function is unimodal when either the source or relay precoding matrix is known. Then, an iterative process is utilised to jointly optimise the source and relay precoding matrices. Simulation results confirm the benefit, in terms of energy consumption, of our novel approach for cooperative MIMO-AF systems in comparison with approaches optimising either the direct or relay link only, with a 20% improvement gain in favorable channel conditions.

11:48 Semi-blind MAP Channel Estimator for Pilot Decontamination

Guangyi Wang (University of Surrey & Institute for Communication Systems, United Kingdom (Great Britain)); Yi Ma, Na Yi and Rahim Tafazolli (University of Surrey, United Kingdom (Great Britain))

In this paper, a novel semi-blind channel estimator is introduced, with the ability of separating two or more independent wireless channels that are superimposed due to pilot contamination. Key novelties of this work include: a) exploiting the joint probability distribution of information and channel to facilitate the multi-channel separability of the maximum a posterior (MAP) channel estimator; b) exploiting the correlation between symbol detection results at a multi-antenna receiver to further improve the channel estimation accuracy. The mean-square error (MSE) of the proposed channel estimator is derived in a closed form, which exhibits the relationship between the pilot decontamination capacity and the modulation size as well as the data observation length. Moreover, simulation results demonstrate close MSE performances between the proposed estimator and the MAP estimator with orthogonal pilots.

12:06 Statistical Beam Codebook Design for mmWave Massive MIMO Systems

Majid Nasiri Khormuji (Huawei Technologies Sweden AB, Sweden); Renaud-Alexandre Pitaval (Huawei Technologies Sweden, Sweden)

We propose a novel method to construct beam codebooks, i.e. a set of beamforming weights, for beam sweeping and data transmission in mmWave massive MIMO channels. The proposed beam codebooks are designed according to the statistical distribution of the channel's angles of departure in order to efficiently sweep the angular space covered by the beams. We first present a general closed-form construction of beam codebooks for an arbitrary distribution of angles and then tailor the results to the Laplace distribution. The resulting beams are a priori better adapted to the channel statistics and thus enhance the spectral efficiency of the transmission as compared to conventional uniform beam designs.

12:24 Performance Analysis of FBMC and CP-OFDM in the Presence of Phase Noise

Kilian Roth (Technische Universität München, Germany); Leonardo Gomes Baltar (Intel Corporation, Germany); Michael Faerber (Intel Deutschland GmbH, Germany); Josef A. Nossek (TU Munich, Germany & Federal University of Ceara, Fortaleza, Brazil)

Multi-carrier (MC) modulation schemes like orthogonal frequency division multiplexing (OFDM) are highly sensitive to phase noise (PN). In the case of air interfaces operating in higher frequencies, e.g. the range between 6 and 100 GHz frequently called millimeter wave (mmWave), the PN generated by the local oscillators is even more accentuated. Alternative MC systems are being considered for future mmWave wireless communication. In this contribution, we analytically derive expressions for an upper bound for the interference power generated by the PN in OFDM, DFT-Spread-OFDM and Filter Bank Multi-carrier (FBMC). Then, we evaluate the performance degradation due to that imperfection in terms of coded and uncoded BER.

12:42 Coverage Analysis in the Uplink of mmWave Cellular Network

Oluwakayode Onireti (University of Glasgow, United Kingdom (Great Britain)); Ali Imran (University of Oklahoma, USA); Muhammad Ali Imran (University of Glasgow, United Kingdom (Great Britain))

In this paper, we present an analytical framework to evaluate the coverage in the uplink of millimeter wave (mmWave) cellular network. By using a distance dependent line-of-sight (LOS) probability function, the location of LOS and non-LOS user equipment (UE) are modeled as two independent non-homogeneous Poisson point processes, with each having different pathloss exponent. The analysis takes account of per UE fractional power control (FPC), which couples the transmission of UE due to location-dependent channel inversion. We consider the following scenarios in our analysis: 1) Pathloss based FPC (PL-FPC) which is performed using the measured pathloss and 2) Distance based FPC (D-FPC) which is performed using the measured distance. Results suggest that D-FPC outperforms the PL-FPC at high SINR. Also, the SINR coverage probability decreases as the cell density becomes greater than a threshold.