132 research outputs found
Design and Analysis of Wideband In-Band-Full-Duplex FR2-IAB Networks
This paper develops a 3GPP-inspired design for the in-band-full-duplex (IBFD)
integrated access and backhaul (IAB) networks in the frequency range 2 (FR2)
band, which can enhance the spectral efficiency (SE) and coverage while
reducing the latency. However, the self-interference (SI), which is usually
more than 100 dB higher than the signal-of-interest, becomes the major
bottleneck in developing these IBFD networks. We design and analyze a
subarray-based hybrid beamforming IBFD-IAB system with the RF beamformers
obtained via RF codebooks given by a modified Linde-Buzo-Gray (LBG) algorithm.
The SI is canceled in three stages, where the first stage of antenna isolation
is assumed to be successfully deployed. The second stage consists of the
optical domain (OD)-based RF cancellation, where cancelers are connected with
the RF chain pairs. The third stage is comprised of the digital cancellation
via successive interference cancellation followed by minimum mean-squared error
baseband receiver. Multiuser interference in the access link is canceled by
zero-forcing at the IAB-node transmitter. Simulations show that under 400 MHz
bandwidth, our proposed OD-based RF cancellation can achieve around 25 dB of
cancellation with 100 taps. Moreover, the higher the hardware impairment and
channel estimation error, the worse digital cancellation ability we can obtain
A differential ML combiner for differential amplify-and-forward system in time-selective fading channels
We propose a new differential maximum-likelihood (DML) combiner for noncoherent detection of the differential amplify-and-forward (D-AF) relaying system in the time-selective channel. The weights are computed based on both the average channel quality and the correlation coefficient of the direct and relay channels. Moreover, we derive a closed-form approximate expression for the average bit error rate (BER), which is applicable to any single-relay D-AF system with fixed weights. Both theoretical and simulated results are presented to show that the time-selective nature of the underlying channels tends to reduce the diversity gains at the low-signal-to-noise-ratio (SNR) region, resulting in an asymptotic BER floor at the high-SNR region. Moreover, the proposed DML combiner is capable of providing significant BER improvements compared with the conventional differential detection (CDD) and selection-combining (SC) schemes
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