2,332 research outputs found
Throughput Analysis for Wireless Networks with Full-Duplex Radios
This paper investigates the throughput for wireless network with full-duplex
radios using stochastic geometry. Full-duplex (FD) radios can exchange data
simultaneously with each other. On the other hand, the downside of FD
transmission is that it will inevitably cause extra interference to the network
compared to half-duplex (HD) transmission. In this paper, we focus on a
wireless network of nodes with both HD and FD capabilities and derive and
optimize the throughput in such a network. Our analytical result shows that if
the network is adapting an ALOHA protocol, the maximal throughput is always
achieved by scheduling all concurrently transmitting nodes to work in FD mode
instead of a mixed FD/HD mode or HD mode regardless of the network
configurations. Moreover, the throughput gain of using FD transmission over HD
transmission is analytically lower and upper bounded.Comment: 4 figure
Providing End-to-End Delay Guarantees for Multi-hop Wireless Sensor Networks over Unreliable Channels
Wireless sensor networks have been increasingly used for real-time
surveillance over large areas. In such applications, it is important to support
end-to-end delay constraints for packet deliveries even when the corresponding
flows require multi-hop transmissions. In addition to delay constraints, each
flow of real-time surveillance may require some guarantees on throughput of
packets that meet the delay constraints. Further, as wireless sensor networks
are usually deployed in challenging environments, it is important to
specifically consider the effects of unreliable wireless transmissions.
In this paper, we study the problem of providing end-to-end delay guarantees
for multi-hop wireless networks. We propose a model that jointly considers the
end-to-end delay constraints and throughput requirements of flows, the need for
multi-hop transmissions, and the unreliable nature of wireless transmissions.
We develop a framework for designing feasibility-optimal policies. We then
demonstrate the utility of this framework by considering two types of systems:
one where sensors are equipped with full-duplex radios, and the other where
sensors are equipped with half-duplex radios. When sensors are equipped with
full-duplex radios, we propose an online distributed scheduling policy and
proves the policy is feasibility-optimal. We also provide a heuristic for
systems where sensors are equipped with half-duplex radios. We show that this
heuristic is still feasibility-optimal for some topologies
Sliding Window Spectrum Sensing for Full-Duplex Cognitive Radios with Low Access-Latency
In a cognitive radio system the failure of secondary user (SU) transceivers
to promptly vacate the channel can introduce significant access-latency for
primary or high-priority users (PU). In conventional cognitive radio systems,
the backoff latency is exacerbated by frame structures that only allow sensing
at periodic intervals. Concurrent transmission and sensing using
self-interference suppression has been suggested to improve the performance of
cognitive radio systems, allowing decisions to be taken at multiple points
within the frame. In this paper, we extend this approach by proposing a
sliding-window full-duplex model allowing decisions to be taken on a
sample-by-sample basis. We also derive the access-latency for both the existing
and the proposed schemes. Our results show that the access-latency of the
sliding scheme is decreased by a factor of 2.6 compared to the existing slotted
full-duplex scheme and by a factor of approximately 16 compared to a
half-duplex cognitive radio system. Moreover, the proposed scheme is
significantly more resilient to the destructive effects of residual
self-interference compared to previous approaches.Comment: Published in IEEE VTC Spring 2016, Nanjing, Chin
Full-Duplex Cognitive Radio: A New Design Paradigm for Enhancing Spectrum Usage
With the rapid growth of demand for ever-increasing data rate, spectrum
resources have become more and more scarce. As a promising technique to
increase the efficiency of the spectrum utilization, cognitive radio (CR)
technique has the great potential to meet such a requirement by allowing
un-licensed users to coexist in licensed bands. In conventional CR systems, the
spectrum sensing is performed at the beginning of each time slot before the
data transmission. This unfortunately results in two major problems: 1)
transmission time reduction due to sensing, and 2) sensing accuracy impairment
due to data transmission. To tackle these problems, in this paper we present a
new design paradigm for future CR by exploring the full-duplex (FD) techniques
to achieve the simultaneous spectrum sensing and data transmission. With FD
radios equipped at the secondary users (SUs), SUs can simultaneously sense and
access the vacant spectrum, and thus, significantly improve sensing
performances and meanwhile increase data transmission efficiency. The aim of
this article is to transform the promising conceptual framework into the
practical wireless network design by addressing a diverse set of challenges
such as protocol design and theoretical analysis. Several application scenarios
with FD enabled CR are elaborated, and key open research directions and novel
algorithms in these systems are discussed
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