602 research outputs found
Interference and Coverage Analysis in Coexisting RF and Dense TeraHertz Wireless Networks
This paper develops a stochastic geometry framework to characterize the
statistics of the downlink interference and coverage probability of a typical
user in a coexisting terahertz (THz) and radio frequency (RF) network. We first
characterize the exact Laplace Transform (LT) of the aggregate interference and
coverage probability of a user in a THz-only network. Then, for a coexisting
RF/THz network, we derive the coverage probability of a typical user
considering biased received signal power association (BRSP). The framework can
be customized to capture the performance of a typical user in various network
configurations such as THz-only, opportunistic RF/THz, and hybrid RF/THz. In
addition, asymptotic approximations are presented for scenarios where the
intensity of THz BSs becomes large or molecular absorption coefficient in THz
approaches to zero. Numerical results demonstrate the accuracy of the derived
expressions and extract insights related to the significance of the BRSP
association compared to the conventional reference signal received power (RSRP)
association in the coexisting network
ISAC-Enabled Beam Alignment for Terahertz Networks: Scheme Design and Coverage Analysis
As a key pillar technology for the future 6G networks, terahertz (THz)
communication can provide high-capacity transmissions, but suffers from severe
propagation loss and line-of-sight (LoS) blockage that limits the network
coverage. Narrow beams are required to compensate for the loss, but they in
turn bring in beam misalignment challenge that degrades the THz network
performance. The high sensing accuracy of THz signals enables integrated
sensing and communication (ISAC) technology to assist the LoS blockage and user
mobility-induced beam misalignment, enhancing THz network coverage. In line
with the 5G beam management, we propose a joint synchronization signal block
(SSB) and reference signal (RS)-based sensing (JSRS) scheme to predict the need
for beam switches, and thus prevent beam misalignment. We further design an
optimal sensing signal pattern that minimizes beam misalignment with fixed
sensing resources, which reveals design insights into the time-to-frequency
allocation. We derive expressions for the coverage probability and spatial
throughput, which provide instructions on the ISAC-THz network deployment and
further enable evaluations for the sensing benefit in THz networks. Numerical
results show that the JSRS scheme is effective and highly compatible with the
5G air interface. Averaged in tested urban use cases, JSRS achieves near-ideal
performance and reduces around 80% of beam misalignment, and enhances the
coverage probability by about 75%, compared to the network with 5G-required
positioning ability
On the Downlink Coverage Performance of RIS-Assisted THz Networks
This letter provides a stochastic geometry (SG)-based coverage probability
(CP) analysis of an indoor terahertz (THz) downlink assisted by a single
reconfigurable intelligent surface (RIS) panel. Specifically, multiple access
points (AP) deployed on the ceiling of a hall (each equipped with multiple
antennas) need to serve multiple user equipment (UE) nodes. Due to presence of
blockages, a typical UE may either get served via a direct link, the RIS, or
both links (the composite link). The locations of the APs and blockages are
modelled as a Poisson point process (PPP) and SG framework is utilized to
compute the CP, at a reference UE for all the three scenarios. Monte-Carlo
simulation results validate our theoretical analysis.Comment: Extended Arxiv version of submitted paper to IEEE Communications
Letter
Spatial-spectral Terahertz Networks
This paper focuses on the spatial-spectral terahertz (THz) networks, where
transmitters equipped with leaky-wave antennas send information to their
receivers at the THz frequency bands. As a directional and nearly planar
antenna, the leaky-wave antenna allows for information transmissions with
narrow beams and high antenna gains. The conventional large antenna arrays are
confronted with challenging issues such as scaling limits and path discovery in
the THz frequencies. Therefore, this work exploits the potential of leaky-wave
antennas in the dense THz networks, to establish low-complexity THz links. By
addressing the propagation angle-frequency coupling effects, the transmission
rate is analyzed. The results show that the leaky-wave antenna is efficient for
achieving the high-speed transmission rate. The co-channel interference
management is unnecessary when the THz transmitters with large subchannel
bandwidths are not extremely dense. A simple subchannel allocation solution is
proposed, which enhances the transmission rate compared with the same number of
subchannels with the equal allocation of the frequency band. After subchannel
allocation, a low-complexity power allocation method is proposed to improve the
energy efficiency.Comment: accepted by the IEEE Transactions on Wireless Communication
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