Enhanced OFDM for fragmented spectrum use in 5G systems

Abstract

Most of the recent and emerging wireless systems have selected orthogonal frequency division multiplexing (OFDM) scheme as the basis for the physical layer due to its flexibility and robustness. OFDM is commonly considered also as the first candidate technology for advanced cognitive radio, dynamic spectrum use and fragmented coexistence scenarios, including the 5G system development. Nevertheless, OFDM has the problem of high‐power spectral sidelobes around the active subcarriers, which limit its feasibility in fragmented spectrum use and asynchronous frequency division multiple access operation. Therefore, various sidelobe suppression techniques have been proposed in the literature to mitigate these effects. This paper investigates four different suppression techniques: time‐domain windowing, cancellation carrier method, subcarrier weighting and polynomial cancellation coding, as well as their combinations. These methods are elaborated for a practical heterogeneous fragmented spectrum use scenario based on 5‐MHz 3GPP Long‐Term Evolution (LTE), proposing various enhancements to achieve effective suppression in narrow gaps with affordable complexity. In addition to the spectral characteristics, also, the possible side effects are evaluated in details, considering peak‐to‐average power ratio characteristics, error rate performance, computational complexity and resources usage. Copyright © 2014 John Wiley & Sons, Ltd.

Effective schemes for OFDM sidelobe control in fragmented spectrum use

“…A short transition can be used in the inner subcarriers without compromising spectrum leakage characteristics. A well-designed edge windowing scheme provides suppression performance very close to conventional time domain windowing, which uses the same transition length in all subcarriers [3], [12]. The benefit of edge windowing is that longer cyclic prefix (CP) can be used in the inner subcarriers.…”

Studying Applicability Feasibility of OFDM in Upcoming 5G Network

“…Bogucka et al [7] have introduced a mechanism of aggregating spectrums of dynamic nature in 5G. Loulou and Renfors [8] have presented a study where a comparative analysis of existing suppression techniques and to overcome the spectral sidelobes of high power in OFDM. Lin et al [9] have used MachZehnder modulator for processing incoming signal into double sideband using experimental approach.…”

Performance Evaluation for Speed of Mobile Devices in UFMC Systems

“…드 로브를 갖고 있어 5G에서 요구되는 분산 스펙트럼 환 경에 부적합하다 [1] . 또한 주파수 옵셋에 의한 ICI(Inter Carrier Interference)에 취약 하다는 단점이 있는데 이것 은 기존의 4G LTE와 같은 엄격하게 동기를 맞추어 지는 시스템에는 적합하나 5G에서 요구되는 비동기적인 통신 방식에는 맞지 않는다 [2] .…”