643 research outputs found
Wideband Self-Adaptive RF Cancellation Circuit for Full-Duplex Radio: Operating Principle and Measurements
This paper presents a novel RF circuit architecture for self-interference
cancellation in inband full-duplex radio transceivers. The developed canceller
is able to provide wideband cancellation with waveform bandwidths in the order
of 100 MHz or beyond and contains also self-adaptive or self-healing features
enabling automatic tracking of time-varying self-interference channel
characteristics. In addition to architecture and operating principle
descriptions, we also provide actual RF measurements at 2.4 GHz ISM band
demonstrating the achievable cancellation levels with different bandwidths and
when operating in different antenna configurations and under low-cost highly
nonlinear power amplifier. In a very challenging example with a 100 MHz
waveform bandwidth, around 41 dB total cancellation is obtained while the
corresponding cancellation figure is close to 60 dB with the more conventional
20 MHz carrier bandwidth. Also, efficient tracking in time-varying reflection
scenarios is demonstrated.Comment: 7 pages, to be presented in 2015 IEEE 81st Vehicular Technology
Conferenc
Full-Duplex Systems Using Multi-Reconfigurable Antennas
Full-duplex systems are expected to achieve 100% rate improvement over
half-duplex systems if the self-interference signal can be significantly
mitigated. In this paper, we propose the first full-duplex system utilizing
Multi-Reconfigurable Antenna (MRA) with ?90% rate improvement compared to
half-duplex systems. MRA is a dynamically reconfigurable antenna structure,
that is capable of changing its properties according to certain input
configurations. A comprehensive experimental analysis is conducted to
characterize the system performance in typical indoor environments. The
experiments are performed using a fabricated MRA that has 4096 configurable
radiation patterns. The achieved MRA-based passive self-interference
suppression is investigated, with detailed analysis for the MRA training
overhead. In addition, a heuristic-based approach is proposed to reduce the MRA
training overhead. The results show that at 1% training overhead, a total of
95dB self-interference cancellation is achieved in typical indoor environments.
The 95dB self-interference cancellation is experimentally shown to be
sufficient for 90% full-duplex rate improvement compared to half-duplex
systems.Comment: Submitted to IEEE Transactions on Wireless Communication
Distributed Full-duplex via Wireless Side Channels: Bounds and Protocols
In this paper, we study a three-node full-duplex network, where a base
station is engaged in simultaneous up- and downlink communication in the same
frequency band with two half-duplex mobile nodes. To reduce the impact of
inter- node interference between the two mobile nodes on the system capacity,
we study how an orthogonal side-channel between the two mobile nodes can be
leveraged to achieve full-duplex-like multiplexing gains. We propose and
characterize the achievable rates of four distributed full-duplex schemes,
labeled bin-and- cancel, compress-and-cancel, estimate-and-cancel and decode-
and-cancel. Of the four, bin-and-cancel is shown to achieve within 1 bit/s/Hz
of the capacity region for all values of channel parameters. In contrast, the
other three schemes achieve the near-optimal performance only in certain
regimes of channel values. Asymptotic multiplexing gains of all proposed
schemes are derived to show that the side-channel is extremely effective in
regimes where inter-node interference has the highest impact.Comment: Published in IEEE Transactions on Wireless Communications, August
201
Survey of Spectrum Sharing for Inter-Technology Coexistence
Increasing capacity demands in emerging wireless technologies are expected to
be met by network densification and spectrum bands open to multiple
technologies. These will, in turn, increase the level of interference and also
result in more complex inter-technology interactions, which will need to be
managed through spectrum sharing mechanisms. Consequently, novel spectrum
sharing mechanisms should be designed to allow spectrum access for multiple
technologies, while efficiently utilizing the spectrum resources overall.
Importantly, it is not trivial to design such efficient mechanisms, not only
due to technical aspects, but also due to regulatory and business model
constraints. In this survey we address spectrum sharing mechanisms for wireless
inter-technology coexistence by means of a technology circle that incorporates
in a unified, system-level view the technical and non-technical aspects. We
thus systematically explore the spectrum sharing design space consisting of
parameters at different layers. Using this framework, we present a literature
review on inter-technology coexistence with a focus on wireless technologies
with equal spectrum access rights, i.e. (i) primary/primary, (ii)
secondary/secondary, and (iii) technologies operating in a spectrum commons.
Moreover, we reflect on our literature review to identify possible spectrum
sharing design solutions and performance evaluation approaches useful for
future coexistence cases. Finally, we discuss spectrum sharing design
challenges and suggest future research directions
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