Photonic Radio Frequency Self-Interference Cancellation and Harmonic Down-Conversion for In-Band Full-Duplex Radio-Over-Fiber System

Abstract

We report a photonic radio frequency (RF) self-interference cancellation (SIC) and harmonic down-conversion (HDC) scheme based on a dual-parallel dual-drive Mach-Zehnder modulator (DDMZM). The proposed scheme can eliminate the chromaticdispersion induced power fading (CDIP) effect and thus is very suitable for in-band full-duplex (IBFD) radio-over-fiber (ROF) system. The self-interference RF signal is directly cancelled in optical domain, which overcomes the electronics bottleneck limitation of electrical SIC. Moreover, the HDC allows us to use a cost-effective low frequency local oscillation (LO) source to down-convert a high-frequency RF signal into an intermediate frequency (IF) band. In addition, the harmonic odd-order single-sideband (SSB) down-conversion is naturally free from the CDIP effect. The proposed photonic SIC+HDC system is theoretically analyzed and experimentally verified.

Optical Multipath RF Self-Interference Cancellation Based on Phase Modulation for Full-Duplex Communication

“…where i out −i,n (t i,n ) and i out −r,n (t r,n + τ n ) are output current from the PD of the n th interference signal and the n th reference signal processed by the optical processor and the TODLs, respectively, as expressed in (8) and (9). When the amplitude and time of each reference signal are properly controlled and the conditions in (10) and (11) are matched, the multipath interference can be cancelled and the SOI is recovered. The interference cancellation depth is one of the important parameters to characterize the performance of optical RF SIC system, which is affected by the time delay, amplitude and phase deviations between the reference path and the interference path.…”

“…In the actual application process, the conditions expressed as (10) and (11) for the multipath interference cancellation may not be achieved completely. For the n th pair of reference and interference signals, the amplitude, time delay and phase deviations between the two paths are indicated as α n , τ n , and ϕ n , respectively.…”

“…The key to achieving interference cancellation is to provide a reference signal that has the same magnitude and opposite phase of the interference signal with time matching. The cancellation can be achieved by using two Mach-Zehnder modulators (MZMs) biased at the opposite orthogonal bias points [7], [8] or dual-drive MZM [9], [10], dual-parallel MZM [11]- [13] operating at the proper bias points to obtain the out-of-phase relationship. However, DC bias control increases the complexity of the system and may affect the operation stability.…”

Photonics-assisted wideband RF self-interference cancellation with digital domain amplitude and delay pre-matching

“…The system is more compact and may have better stability using a single optical path. Besides the SIC function, the photonics-assisted SIC methods combining frequency downconversion [21], [24], [26], [27] and radio over fiber transmission [20], [22], [24], [26]- [28] are also extensively studied.…”

Stimulated Brillouin Scattering Based Image-Reject Microwave Signal Harmonic Down-Converter

“…Whereas, the used of optical filter may restrict the frequency range of the mixer. Frequency down conversion systems can also be achieved based on four-wave mixing (FWM) effect in a semiconductor optical amplifier (SOA) or high-order modulation of modulators, which can enable microwave downconversion in the electrical domain with a low-frequency electrical LO [7][8]. However, due to the existence of the image (IM) signal whose frequency is symmetrical to the RF signal with respect to the LO signal, the down-converted IF signals in above schemes not only contain the useful IF signal, but also have the undesired IM down-converted interference signal, which may lead to fuzzy frequency identification and even distortion of useful IF signal.…”