Advances in opportunistic radio technologies for TVWS

Abstract

Cognitive radio has been an active research area in wireless communications over the past 10 years. TV Digital Switch Over resulted in new regulatory regimes, which offer the first large-scale opportunity for cognitive radio and networks. This article considers the most recent regulatory rules for TV White Space opportunistic usage, and proposes technologies to operate in these bands. It addresses techniques to assess channel vacancy by the cognitive radio, focusing on the two incumbent systems of the TV bands, namely TV stations and wireless microphones. Spectrum-sensing performance is discussed under TV White Space regulation parameters. Then, modulation schemes for the opportunistic radio are discussed, showing the limitations of classical multi-carrier techniques and the advantages of filter bank modulations. In particular, the low adjacent band leakage of filter bank is addressed, and its benefit for spectrum pooling is stressed as a means to offer broadband access through channel aggregation.

Wideband frequency domain detection using Teager-Kaiser energy operator

“…The bandwidth of one subband should then be an integer multiple of the carrier spacing. Two key advantages can be identified for the transceiver architecture [8]. First, the input of the FFT can be fed with zeros at frequencies where incumbent users are present, while vacant subbands are used for transmission by the opportunistic radio.…”

“…It proposes to use a wideband FFT to access an important bandwidth and allocate frequency bins to CR users according to white spaces opportunities. The same FFT operation may also be used to perform the sensing step [8]. The outputs of the FFT are analyzed using specific frequency domain metrics.…”

Analysis of Candidate Waveforms for 5G Cellular Systems

“…Time and frequency domain Figure 1. Power spectral density of CP-OFDM centred on the active carrier [9].…”

Cyclic Prefix-Based Universal Filtered Multicarrier System and Performance Analysis

“…However, comparing with the FBMC system, the UFMC system inherits the advantageous properties of OFDM systems, e.g., ease in the implementation of multiantenna techniques and low complexity channel estimation and equalization algorithms. In addition, comparing with Filtered OFDM system that filters the whole bandwidth after OFDM modulation [8], the UFMC system provides flexibility to filter a subband with arbitrary bandwidth to enable the system adopted for specific users or service types by adjusting the subband and filter parameters only. For example, a UFMC system may serve two types of services (e.g., tactile and machine type communications [9]) in two subbands with different communications requirements and frame structure.…”