3,980 research outputs found
Cyclic prefix-based universal filtered multicarrier system and performance analysis
Recently proposed universal filtered multicarrier (UFMC) system is not an orthogonal system in multipath channel environments and might cause significant performance loss. In this paper, the authors propose a cyclic prefix (CP) based UFMC system and first analyze the conditions for interference-free one-tap equalization in the absence of transceiver imperfections. Then the corresponding signal model and output signal-to-noise ratio expression are derived. In the presence of carrier frequency offset, timing offset, and insufficient CP length, the authors establish an analytical system model as a summation of desired signal, intersymbol interference, intercarrier interference, and noise. New channel equalization algorithms are proposed based on the derived analytical signal model. Numerical results show that the derived model matches the simulation results precisely, and the proposed equalization algorithms improve the UFMC system performance in terms of bit error rate
Efficient Fast-Convolution-Based Waveform Processing for 5G Physical Layer
This paper investigates the application of fast-convolution (FC) filtering
schemes for flexible and effective waveform generation and processing in the
fifth generation (5G) systems. FC-based filtering is presented as a generic
multimode waveform processing engine while, following the progress of 5G new
radio standardization in the Third-Generation Partnership Project, the main
focus is on efficient generation and processing of subband-filtered cyclic
prefix orthogonal frequency-division multiplexing (CP-OFDM) signals. First, a
matrix model for analyzing FC filter processing responses is presented and used
for designing optimized multiplexing of filtered groups of CP-OFDM physical
resource blocks (PRBs) in a spectrally well-localized manner, i.e., with narrow
guardbands. Subband filtering is able to suppress interference leakage between
adjacent subbands, thus supporting independent waveform parametrization and
different numerologies for different groups of PRBs, as well as asynchronous
multiuser operation in uplink. These are central ingredients in the 5G waveform
developments, particularly at sub-6-GHz bands. The FC filter optimization
criterion is passband error vector magnitude minimization subject to a given
subband band-limitation constraint. Optimized designs with different guardband
widths, PRB group sizes, and essential design parameters are compared in terms
of interference levels and implementation complexity. Finally, extensive coded
5G radio link simulation results are presented to compare the proposed approach
with other subband-filtered CP-OFDM schemes and time-domain windowing methods,
considering cases with different numerologies or asynchronous transmissions in
adjacent subbands. Also the feasibility of using independent transmitter and
receiver processing for CP-OFDM spectrum control is demonstrated
Subband filtered multi-carrier systems for multi-service wireless communications
Flexibly supporting multiple services, each with different communication requirements and frame structure, has been identified as one of the most significant and promising characteristics of next generation and beyond wireless communication systems. However, integrating multiple frame structures with different subcarrier spacing in one radio carrier may result in significant inter-service-band-interference (ISBI). In this paper, a framework for multi-service (MS) systems is established based on a subband filtered multi-carrier system. The subband filtering implementations and both asynchronous and generalized synchronous (GS) MS subband filtered multi-carrier (SFMC) systems have been proposed. Based on the GS-MS-SFMC system, the system model with ISBI is derived and a number of properties on ISBI are given. In addition, low-complexity ISBI cancelation algorithms are proposed by precoding the information symbols at the transmitter. For asynchronous MS-SFMC system in the presence of transceiver imperfections, including carrier frequency offset, timing offset, and phase noise, a complete analytical system model is established in terms of desired signal, inter-symbol-interference, inter-carrier-interference, ISBI, and noise. Thereafter, new channel equalization algorithms are proposed by considering the errors and imperfections. Numerical analysis shows that the analytical results match the simulation results, and the proposed ISBI cancelation and equalization algorithms can significantly improve the system performance in comparison with the existing algorithms
MIMO-UFMC Transceiver Schemes for Millimeter Wave Wireless Communications
The UFMC modulation is among the most considered solutions for the
realization of beyond-OFDM air interfaces for future wireless networks. This
paper focuses on the design and analysis of an UFMC transceiver equipped with
multiple antennas and operating at millimeter wave carrier frequencies. The
paper provides the full mathematical model of a MIMO-UFMC transceiver, taking
into account the presence of hybrid analog/digital beamformers at both ends of
the communication links. Then, several detection structures are proposed, both
for the case of single-packet isolated transmission, and for the case of
multiple-packet continuous transmission. In the latter situation, the paper
also considers the case in which no guard time among adjacent packets is
inserted, trading off an increased level of interference with higher values of
spectral efficiency. At the analysis stage, the several considered detection
structures and transmission schemes are compared in terms of bit-error-rate,
root-mean-square-error, and system throughput. The numerical results show that
the proposed transceiver algorithms are effective and that the linear MMSE data
detector is capable of well managing the increased interference brought by the
removal of guard times among consecutive packets, thus yielding throughput
gains of about 10 - 13 . The effect of phase noise at the receiver is also
numerically assessed, and it is shown that the recursive implementation of the
linear MMSE exhibits some degree of robustness against this disturbance
Waveform Design for 5G and beyond Systems
5G traffic has very diverse requirements with respect to data rate, delay, and reliability. The concept of using multiple OFDM numerologies adopted in the 5G NR standard will likely meet these multiple requirements to some extent. However, the traffic is radically accruing different characteristics and requirements when compared with the initial stage of 5G, which focused mainly on high-speed multimedia data applications. For instance, applications such as vehicular communications and robotics control require a highly reliable and ultra-low delay. In addition, various emerging M2M applications have sparse traffic with a small amount of data to be delivered. The state-of-the-art OFDM technique has some limitations when addressing the aforementioned requirements at the same time. Meanwhile, numerous waveform alternatives, such as FBMC, GFDM, and UFMC, have been explored. They also have their own pros and cons due to their intrinsic waveform properties. Hence, it is the opportune moment to come up with modification/variations/combinations to the aforementioned techniques or a new waveform design for 5G systems and beyond. The aim of this Special Issue is to provide the latest research and advances in the field of waveform design for 5G systems and beyond
Filtered OFDM systems, algorithms and performance analysis for 5G and beyond
Filtered orthogonal frequency division multiplexing (F-OFDM) system is a promising waveform for 5G and beyond to enable multi-service system and spectrum efficient network slicing. However, the performance for F-OFDM systems has not been systematically analyzed in literature. In this paper, we first establish a mathematical model for F-OFDM system and derive the conditions to achieve the interference-free one-tap channel equalization. In the practical cases (e.g., insufficient guard interval, asynchronous transmission, etc.), the analytical expressions for inter-symbol-interference (ISI), inter-carrier-interference (ICI) and adjacent-carrier-interference (ACI) are derived, where the last term is considered as one of the key factors for asynchronous transmissions. Based on the framework, an optimal power compensation matrix is derived to make all of the subcarriers having the same ergodic performance. Another key contribution of the paper is that we propose a multi-rate F-OFDM system to enable low complexity low cost communication scenarios such as narrow band Internet of Things (IoT), at the cost of generating inter-subband-interference (ISubBI). Low computational complexity algorithms are proposed to cancel the ISubBI. The result shows that the derived analytical expressions match the simulation results, and the proposed ISubBI cancelation algorithms can significantly save the original F-OFDM complexity (up to 100 times) without significant performance los
Communications techniques and equipment: A compilation
This Compilation is devoted to equipment and techniques in the field of communications. It contains three sections. One section is on telemetry, including articles on radar and antennas. The second section describes techniques and equipment for coding and handling data. The third and final section includes descriptions of amplifiers, receivers, and other communications subsystems
Waveform Design for 5G and Beyond
5G is envisioned to improve major key performance indicators (KPIs), such as
peak data rate, spectral efficiency, power consumption, complexity, connection
density, latency, and mobility. This chapter aims to provide a complete picture
of the ongoing 5G waveform discussions and overviews the major candidates. It
provides a brief description of the waveform and reveals the 5G use cases and
waveform design requirements. The chapter presents the main features of cyclic
prefix-orthogonal frequency-division multiplexing (CP-OFDM) that is deployed in
4G LTE systems. CP-OFDM is the baseline of the 5G waveform discussions since
the performance of a new waveform is usually compared with it. The chapter
examines the essential characteristics of the major waveform candidates along
with the related advantages and disadvantages. It summarizes and compares the
key features of different waveforms.Comment: 22 pages, 21 figures, 2 tables; accepted version (The URL for the
final version:
https://onlinelibrary.wiley.com/doi/abs/10.1002/9781119333142.ch2
Software Defined Radio Implementation of Carrier and Timing Synchronization for Distributed Arrays
The communication range of wireless networks can be greatly improved by using
distributed beamforming from a set of independent radio nodes. One of the key
challenges in establishing a beamformed communication link from separate radios
is achieving carrier frequency and sample timing synchronization. This paper
describes an implementation that addresses both carrier frequency and sample
timing synchronization simultaneously using RF signaling between designated
master and slave nodes. By using a pilot signal transmitted by the master node,
each slave estimates and tracks the frequency and timing offset and digitally
compensates for them. A real-time implementation of the proposed system was
developed in GNU Radio and tested with Ettus USRP N210 software defined radios.
The measurements show that the distributed array can reach a residual frequency
error of 5 Hz and a residual timing offset of 1/16 the sample duration for 70
percent of the time. This performance enables distributed beamforming for range
extension applications.Comment: Submitted to 2019 IEEE Aerospace Conferenc
- …