7 research outputs found
Extensionless Adaptive Transmitter and Receiver Windowing of Beyond 5G Frames
Newer cellular communication generations are planned to allow asynchronous
transmission of multiple numerologies (waveforms with different parameters) in
adjacent bands, creating unavoidable adjacent channel interference. Most prior
work on windowing assume additional extensions reserved for windowing, which
does not comply with standards. Whether windowing should be applied at the
transmitter or the receiver was not questioned. In this work, we propose two
independent algorithms that are implemented at the transmitter and receiver,
respectively. These algorithms estimate the transmitter and receiver windowing
duration of each resource element (RE) with an aim to improve fair proportional
network throughput. While doing so, we solely utilize the available extension
that was defined in the standard and present standard-compliant algorithms that
also do not require any modifications on the counterparts or control signaling.
Furthermore, computationally efficient techniques to apply per-RE transmitter
and receiver windowing to signals synthesized and analyzed using conventional
cyclic prefix orthogonal frequency division multiplexing are derived and their
computational complexities are analyzed. The spectrotemporal relations between
optimum window durations at either side, as well as functions of the excess
signal to noise ratios, the subcarrier spacings and the throughput gains
provided over previous similar techniques are numerically verified.Comment: 15 pages, 2 algorithms, 3 tables, 11 figures (1 of which includes 3
subfigures) and 3 author biographies. Final version accepted for publication
in IEEE Transactions on Vehicular Technolog
Inter-Numerology Interference Analysis for 5G and Beyond
One of the defining characteristics of 5G is the flexibility it offers for
supporting different services and communication scenarios. For this purpose,
usage of multiple numerologies has been proposed by the 3rd Generation
Partnership Project (3GPP). The flexibility provided by multi-numerology system
comes at the cost of additional interference, known as inter-numerology
interference (INI). This paper comprehensively explains the primary cause of
INI, and then identifies and describes the factors affecting the amount of INI
experienced by each numerology in the system. These factors include subcarrier
spacing, number of used subcarriers, power offset, windowing operations and
guard bands
Interference analysis and power allocation in the presence of mixed numerologies
The flexibility in supporting heterogeneous services with vastly different technical requirements is one of the distinguishing characteristics of the fifth generation (5G) communication systems and beyond. One viable solution is to divide the system bandwidth into several bandwidth parts (BWPs), each having a distinct numerology optimized for a particular service. However, multiplexing of mixed numerologies over a unified physical infrastructure comes at the cost of induced interference. In this paper, we develop an analytical system model for inter-numerology interference (InterNI) analysis in orthogonal frequency-division multiplexing (OFDM) systems with and without filter processing in the presence of mixed numerologies. With the analytical model, the level of InterNI is quantified by the developed analytical metric, which is expressed as a function of several system parameters. This leads to an analysis and evaluation of these parameters for meeting a given distortion target. Moreover, a case study on power allocation utilizing the derived analysis is presented, where an optimization problem of maximizing the sum rate is formulated, and a solution is also provided. It is also demonstrated that a filtered-OFDM system better accommodates the coexistence of mixed numerologies. The proposed model provides an accurate analytical guidance for the multi-service design in 5G and beyond systems
Adaptive windowing of insufficient CP for joint minimization of ISI and ACI beyond 5G
Using minimum, even insufficient guards are proposed to achieve the spectral efficiency and latency requirements of cellular communication systems beyond 5G. This leads to interference in both time and frequency domains. In this paper, a partial-non-orthogonal multiple accessing scenario in which the desired user is experiencing both intersymbol interference (ISI) due to insufficient cyclic prefix (CP) and adjacent channel interference (ACI) caused by asynchronous transmitters using non-orthogonal numerologies in adjacent bands is investigated. ISI and ACI depend on the power offset between desired and interfering users, the instantaneous channel impulse responses of interfering users and transmitter and receiver window functions. Therefore, joint and adaptive utilization of CP requires real-time calculation of ISI and ACI. Analytical expressions for expected ISI and ACI at each subcarrier of the desired user are derived to minimize their combination. Accordingly, an adaptive algorithm consisting of windowing each subcarrier at the receiver with window length that minimizes the combined interference at that subcarrier by optimally exchanging ISI and ACI is proposed. Interference reduction performances of current, outdated and average optimal window length raised cosine receiver windows are assessed and compared to fixed and no receiver windowing. Windowing reduces interference even when CP is shorter than the channel if window length is determined using the proposed design guidelines.Institute of Electrical and Electronics Engineers Inc.IEEE Communications Societ