Frequencies above 6 GHz are being considered by mobile communication industry for the deployment of future 5G networks. However in the higher carrier frequencies, especially the millimeter-wave frequencies (above 30 GHz), there can be severe degradations in the transmitted and received signals due to Phase Noise (PN) introduced by the local oscillators. In this paper, the effect of PN has been investigated for Orthogonal Frequency Division Multiplexing (OFDM), Offset QAM Filter-Bank Multi-Carrier (OQAM-FBMC) and QAM Filter-Bank Multi-Carrier (QAM-FBMC). The sources of degradation in these waveforms are quantified and closed-form expressions are derived for Signal-to-Interference Ratio (SIR). Evaluations are performed in terms of SIR and Symbol Error Rate (SER) for mm-wave frequencies using mmMAGIC PN model. The results reveal that OFDM outperforms OQAM-FBMC and QAM-FBMC and is a promising candidate for mm-wave communication.

5G is expected to operate in a wide frequency range to support new challenging use-cases. Multi- RATs (Radio Access Technologies): NR (New Radio) and evolved LTE (Long Term Evolution) will together constitute 5G. Utilizing NR at high frequencies will have a significant impact on radio propagation conditions with e.g. unfavorable higher path loss and increased outdoor-to-indoor penetration losses. In order to provide a reliable communication from the outset of 5G deployment and to minimize the standardization and implementation complexity, 5G UP (User Plane) instances of 5G AIs (Air Interface) related to evolved LTE and NR need to be aggregated on a certain layer of the protocol stack. This paper sheds light on how to integrate 5G AIs into a single 5G AI framework and explores which protocol stack layer could be used as aggregation layer. Inter-RAT hard handover is the state of the art technique to integrate multiple RATs in order to support mobility and reliability across different RATs. However, the hard handover incurs a transmission interruption which stands as an obstacle along the way of accomplishing 5G design. According to simulation results, a common PDCP (Packet Data Convergence Protocol) layer improves the hard handover functionality and stands out as a basis for tight interworking between evolved LTE and NR. By means of simulation, it is shown that the multi-RAT UP aggregation can achieve three times higher user throughput, when NR is using 28 GHz and LTE 2 GHz, compared to stand-alone NR.

Frequency bands above 6GHz are receiving great attention for 5G mobile radio communications due to the potential availability of enormous channel bandwidths. Various multi-carrier and single-carrier waveforms are being considered as potential candidates for 5G radio interface. When evaluating the waveform performance at high carrier frequency and large bandwidths, the inclusion of realistic hardware impairments is of great importance. In this paper, various 5G candidate waveforms (OFDM, DFTS-OFDM, W/P-OFDM, UF-OFDM, FBMC) are evaluated under hardware impairments (i.e., oscillator phase noise and non-linear amplifier) for above 6GHz mobile communications. It is observed that low out-of-band emission advantage of frequency localized waveforms (W/P-OFDM, UF-OFDM, FBMC) over OFDM and DFTS-OFDM may degrade or even vanish when hardware impairments are considered.

Observed Time Difference of Arrival (OTDOA) is a downlink positioning method in Long Term Evolution (LTE) networks, in which a User Equipment (UE) measures the time of arrival (TOA) of reference signals received from multiple base stations. The TOA measurements are reported to the network in terms of reference signal time difference (RSTD) measurements, which are used to determine the position of the UE. The accuracy of the estimated position relies on the accuracy of the measured and reported RSTDs (equivalently TOAs). A UE can determine TOA by measuring the time delay of the first channel tap in the estimated channel impulse response. This is usually a nontrivial task in indoor environments where the line-of-site (LOS) signal can be weak or even non-existent. This paper proposes an iterative method for the detection of the first channel tap in an estimated channel impulse response. The performance of the proposed method is evaluated using an ITU Macro 3D channel model. The proposed iterative method is shown to always outperform a commonly used fixed threshold/non-iterative method. Furthermore, the paper analyzes the impact of RSTD quantization resolution in scenarios where a good quality of TOA estimation is already available. By introducing higher resolutions, it has been shown that the current RSTD reporting in LTE specifications is limiting, and the positioning accuracy can be further improved by a finer RSTD reporting resolution.

5G radio access technology is envisioned to operate from sub-1 GHz to 100 GHz using a wide range of deployment options and to support diverse services. This paper proposes OFDM numerology and frame structure for 5G radio access. The numerology is proposed keeping in view realistic propagation channel measurements, mobility, effect of phase noise, and implementation complexity. The frame structure is proposed for both FDD and TDD. The proposed frame structure is flexible, scalable, and fulfills low latency requirements.

In this paper, we study the performances of cyclic prefix orthogonal frequency division multiplexing (CP-OFDM) and universal filtered orthogonal frequency division multiplexing (UF-OFDM) in the presence of phase noises. A phase noise mitigation scheme was proposed for CP-OFDM in a previous work. In this work, we extend the scheme to UF-OFDM. Phase noise estimation parameters are studied extensively in order to improve the performance of the scheme with a respect of the performance-complexity trade-off. The proposed scheme does not require detailed knowledge of statistics of the phase noise and can effectively compensate the phase noise within each multicarrier symbol with reasonable complexity.

This paper provides an overview and preliminary comparison of several multi-carrier and single-carrier waveforms that are potential candidates for future 5G mobile radio communications above 6 GHz. The waveforms are assessed primarily based on the established and known results as well as recent findings keeping in view the design requirements that are relevant to using frequencies above 6 GHz, especially the millimeter wave frequencies. The Key Performance Indicators and degrees of freedom in the design of different waveforms and their potential applications for mm-wave communications are discussed. Certain features that are particularly interesting for mm-wave communication and require further investigations are also highlighted. Furthermore, a common framework for synthesizing different waveform candidates has been developed. Finally, a preliminary qualitative comparison of different multi-carrier and single carrier waveforms has been derived.

City-wide control and coordination of traffic flow can improve efficiency, fuel consumption, and safety. We consider the problem of controlling traffic lights under fixed and adaptive routing of vehicles in urban road networks. Multicommodity back-pressure algorithms, originally developed for routing and scheduling in communication networks, are applied to road networks to control traffic lights and adaptively reroute vehicles. The performance of the algorithms is analyzed using a microscopic traffic simulator. The results demonstrate that the proposed multicommodity and adaptive routing algorithms provide significant improvement over a fixed schedule controller and a single-commodity back-pressure controller in terms of various performance metrics, including queue length, trips completed, travel times, and fair traffic distribution.

We consider the three-node Gaussian relay channel where the relay observes a noisy version of the interference present in the source--destination link. We investigate three fundamental relaying approaches: linear relaying, memoryless nonlinear relaying, and compress-and-forward (CF). For interference-limited cases, we illustrate that optimized memoryless nonlinear relaying almost achieves the capacity.

We study the problem of optimal design of relay mappings for the Gaussian relay channel in order to maximize the reliable transmission rate. We consider both Gaussian and modulation constrained signaling at the source. To optimize the relay mapping, we use an iterative integral equation as a necessary condition for optimality. The optimized relay mappings demonstrate significant rate improvement over conventional linear relaying (amplify-and-forward). The optimized mappings allow an efficient utilization of the side information received via the source-destination link at the destination. Hence, the proposed mappings can be considered as an analog, memoryless approach to implementing compress-and-forward relaying with Wyner-Ziv compression in the relay.