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We compare the 5G candidate waveforms UF-OFDM and CP-OFDM, as well as their single carrier DFT-spread variants, with respect to their sensitivity to impacts arising from RF processing in conjunction with respective signal conditioning algorithms, using both simulations and hardware measurements. Clipping algorithms are used for dealing with the high peak-to-average-power-ratio (PAPR), while taking...
Universal Filtered Orthogonal Frequency Division Multiplexing (UF-OFDM) is considered as a promising 5G waveform candidate. It requires a relatively simple transceiver structure, while achieving much better spectral properties compared to CP-OFDM. During the early deployment of 5G systems, many frequency bands will still be occupied by 4G systems, using the legacy CP-OFDM waveform. The main focus...
This paper provides indications and simulative performance evaluations of how a wireless system can profit from being able to support various subcarrier spacings concurrently. We show that with using this degree of freedom high Doppler, low latency and extended coverage scenarios are improved. In our investigations we consider different options for multi-carrier numerology, frame design and pilot...
Upcoming fifth generation (5G) cellular networks will demand more from the physical layer (PHY) than current- generation Orthogonal Frequency Division Multiplexing (OFDM) can deliver. The 5G waveform candidate Universal Filtered OFDM (UF-OFDM) is designed to provide the flexibility re- quired for future applications. However, the introduction of subband filters in UFMC can increase implementation...
Universal Filtered Multi-Carrier (UFMC, a.k.a. UF-OFDM) is a novel multi-carrier modulation technique, which aims at replacing OFDM for next generation wireless communication systems (5G). It is a generalization of OFDM and filter bank based multi-carrier (FBMC-FMT), which combines the advantages of OFDM and FBMC while avoiding its main drawbacks. UFMC is shown to be more robust in relaxed synchronization...
In this paper we assess the pains and potential gains a wireless communication system can leverage on, if we allow for multiplexing different subcarrier spacings within a single transmission time interval (TTI). CP-OFDM is nowadays most often the signal format of choice in wireless communication systems when serving multiple users. LTE/-A, WiFi and WiMAX have all adopted CP-OFDM due to its high degree...
In this paper, we investigate channel estimation for the massive Multiple-Input Multiple-Output (MIMO) systems, by deploying superimposed pilots. The pilots are the a priori known spreading sequences, repeated cyclically and superimposed to the signal layer. They reserve a marginal fraction of the total transmit energy. Thus, the initial channel estimates can be initially obtained by separating the...
Universal Filtered Multi-Carrier (UFMC) is a novel multi-carrier modulation technique which can be seen as a generalization of filtered OFDM and filter bank based multi-carrier (FBMC-FMT). Being a candidate waveform technology for 5G wireless systems, it combines the simplicity of OFDM with the advantages of FBMC. The FIR-filter, used in UFMC to filter a group of subcarriers, is a key design parameter...
UF-OFDM is a promising 5G waveform candidate, close to CP-OFDM, but with better spectral properties. Efficient receiver implementations exist, which are close to CP-OFDM in terms of complexity. The UF-OFDM multi-carrier modulator, on the other hand, still has no efficient solution in the literature up to now. This paper addresses this problem and presents a novel frequency domain generation method...
This paper reports intermediate transceiver and frame structure concepts and corresponding results from the European FP7 research project 5GNOW. The core is the unified frame structure concept which supports an integrated 5G air interface, capable of dealing both with broadband data services and small packet services within the same band. It is essential for this concept to introduce waveforms which...
In this paper, we investigate channel estimation for Interleave-Division Multiple Access (IDMA) in an asynchronous multiuser system, by deploying superimposed pilots. As the superimposed pilots are the a priori known spreading sequences, the initial channel estimates can be obtained by separating the users with respect to the corresponding code-division orthogonality. Within the inherent IDMA iterations,...
5G wireless systems may benefit by waveforms supporting relaxed synchronization, as this enables reduced energy consumption, better support of low-end devices and reduction of signaling overhead. In this paper we evaluate UFMC (Universal Filtered Multi-Carrier), also known as UF-OFDM (universal filtered OFDM) — the recently appeared waveform option for 5G — with respect to its performance in scenarios...
In this paper we review the waveform design of 4G (based on OFDM) and motivate the need for a redesign for 5G. Both the advent of the Internet of Things (IoT) and the move to user-centric processing are rendering OFDM unfeasible. With FBMC a potential contender has been promoted in recent years. Though FBMC is better suited than OFDM in theory, practical considerations pinpoint many issues of FBMC...
In this paper we investigate multiple access schemes and multi-carrier waveforms in the context of future 5th Generation (5G) wireless communication systems. We compare classical Frequency Division Multiple Access (FDMA) to Interleave-Division Multiple Access (IDMA) on top of two different multicarrier waveforms: Orthogonal Frequency Division Multiplexing (OFDM) and a new approach called Universal...
In this paper we compare three candidate multicarrier waveforms for the air interface of 5G: filtered CP-OFDM - the choice for 4G, FBMC - heavily discussed in recent years, and Universal Filtered Multi-Carrier (UFMC) - a new contender making its appearance recently. We judge their time-frequency efficiency when transmitting very small bursts (e.g. for machine to machine communications) and under very...
This article provides some fundamental indications about wireless communications beyond LTE/LTE-A (5G), representing the key findings of the European research project 5GNOW. We start with identifying the drivers for making the transition to 5G networks. Just to name one, the advent of the Internet of Things and its integration with conventional human-initiated transmissions creates a need for a fundamental...
Faster-than-Nyquist signaling originally proposed by J. E. Mazo promises higher spectral efficiencies by introducing controlled intersymbol interference at the transmitter at the cost of a higher receiver complexity. We propose a non-trellis based maximum likelihood (ML) receiver in conjunction with linear MMSE reception and interference cancellation for multi-carrier faster-than-Nyquist signaling...
In this paper, we propose a multi-carrier transmission scheme to overcome the problem of intercarrier interference (ICI) in orthogonal frequency division multiplexing (OFDM) systems. In the proposed scheme, called universal-filtered multi-carrier (UFMC), a filtering operation is applied to a group of consecutive subcarriers (e.g. a given allocation of a single user) in order to reduce out-of-band...
5GNOW is a European collaborative research project questioning the design targets of LTE and LTE-Advanced, in particular the obedience to strict synchronism and orthogonality. By introducing new waveforms, the project fosters a re-design of physical and partially MAC layer to support heterogeneous traffic (high rate, sporadic access, carrier aggregation). For system level performance evaluations of...
LTE and LTE-Advanced have been optimized to deliver high bandwidth pipes to wireless users. The transport mechanisms have been tailored to maximize single cell performance by enforcing strict synchronism and orthogonality within a single cell and within a single contiguous frequency band. Various emerging trends reveal major shortcomings of those design criteria: • The fraction of machine-type-communications...
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