5 research outputs found
Performance Analysis of Relay Selection Schemes in Multi-Hop Decode-and-Forward Networks
This paper analyses the data rate achieved by various relay selection schemes
in a single-user multi-hop relay network with decode-and-forward (DF) relaying.
While the single-user relay selection problem is well studied in the
literature, research on achievable rate maximization is limited to dual-hop
networks and multi-hop networks with a single relay per hop. We fill this
important gap by focusing on achievable rate maximization in multi-hop,
multi-relay networks. First, we consider optimal relay selection and obtain two
approximations to the achievable rate. Next, we consider three existing
sub-optimal relay selection strategies namely hop-by-hop, ad-hoc and
block-by-block relay selection and obtain exact expressions for the achievable
rate under each of these strategies. We also extend the sliding window based
relay selection to the DF relay network and derive an approximation to the
achievable rate. Further, we investigate the impact of window size in sliding
window based relay selection and show that a window size of three is sufficient
to achieve most of the possible performance gains. Finally, we extend this
analysis to a noise limited multi-user network where the number of available
relay nodes is large compared to the number of users and derive approximations
to the achievable sum-rate
Joint Relay Selection and Power Control that aims to Maximize Sum-Rate in Multi-Hop Networks
Focusing on the joint relay selection and power control problem with a view
to maximizing the sum-rate, we propose a novel sub-optimal algorithm that
iterates between relay selection and power control. The relay selection is
performed by maximizing the minimum signal-to-interference-plus-noise-ratio (as
opposed to maximizing the sum-rate) and the power control is performed using a
successive convex approximation. By comparing the proposed algorithm with
existing solutions via extensive simulations, we show that the proposed
algorithm results in significant sum-rate gains. Finally, we analyze the
two-user multi-hop network and show that optimum transmit power of at least for
two transmitting nodes can be found using binary power allocation.Comment: Extended Version, Submitted to IEEE Communications Letter
Integrated Sensing and Communications for IoT: Synergies with Key 6G Technology Enablers
The Internet of Things (IoT) and wireless generations have been evolving
simultaneously for the past few decades. Built upon wireless communication and
sensing technologies, IoT networks are usually evaluated based on metrics that
measure the device ability to sense information and effectively share it with
the network, which makes Integrated Sensing and Communication (ISAC) a pivotal
candidate for the sixth-generation (6G) IoT standards. This paper reveals
several innovative aspects of ISAC from an IoT perspective in 6G, empowering
various modern IoT use cases and key technology enablers. Moreover, we address
the challenges and future potential of ISAC-enabled IoT, including synergies
with Reconfigurable Intelligent Surfaces (RIS), Artificial Intelligence (AI),
and key updates of ISAC-IoT in 6G standardization. Furthermore, several
evolutionary concepts are introduced to open future research in 6G ISAC-IoT,
including the interplay with Non-Terrestrial Networks (NTN) and Orthogonal
Time-Frequency Space (OTFS) modulation.Comment: 7 pages, 6 figure
Towards Integrated Sensing and Communications for 6G: A Standardization Perspective
The radio communication division of the International Telecommunication Union
(ITU-R) has recently adopted Integrated Sensing and Communication (ISAC) among
the key usage scenarios for IMT-2030/6G. ISAC is envisioned to play a vital
role in the upcoming wireless generation standards. In this work, we bring
together several paramount and innovative aspects of ISAC technology from a
global 6G standardization perspective, including both industrial and academic
progress. Specifically, this article provides 6G requirements and ISAC-enabled
vision, including various aspects of 6G standardization, benefits of ISAC
co-existence, and integration challenges. Moreover, we present key enabling
technologies, including intelligent metasurface-aided ISAC, as well as
Orthogonal Time Frequency Space (OTFS) waveform design and interference
management for ISAC. Finally, future aspects are discussed to open various
research opportunities and challenges on the ISAC technology towards 6G
wireless communications.Comment: 7 pages, 5 figure
Optimal Routing for Multi-user Multi-hop Relay Networks via Dynamic Programming
In this paper, we study the relay selection problem in multi-user, multi-hop
relay networks with the objective of minimizing the maximum outage probability
across all users. When only one user is present, it is well known that the
optimal relay selection problem can be solved efficiently via dynamic
programming. This solution breaks down in the multi-user scenario due to
dependence between users. We resolve this challenge using a novel relay
aggregation approach. On the expanded trellis, dynamic programming can be used
to solve the optimal relay selection problem with computational complexity
linear in the number of hops. Numerical examples illustrate the efficient use
of this algorithm for relay networks.Comment: Extended Version, Accepted to IEEE Wireless Communications Letter