7,764 research outputs found
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
Optimal Selection of Spectrum Sensing Duration for an Energy Harvesting Cognitive Radio
In this paper, we consider a time-slotted cognitive radio (CR) setting with
buffered and energy harvesting primary and CR users. At the beginning of each
time slot, the CR user probabilistically chooses the spectrum sensing duration
from a predefined set. If the primary user (PU) is sensed to be inactive, the
CR user accesses the channel immediately. The CR user optimizes the sensing
duration probabilities in order to maximize its mean data service rate with
constraints on the stability of the primary and cognitive queues. The
optimization problem is split into two subproblems. The first is a
linear-fractional program, and the other is a linear program. Both subproblems
can be solved efficiently.Comment: Accepted in GLOBECOM 201
Interference Mitigation for Cognitive Radio MIMO Systems Based on Practical Precoding
In this paper, we propose two subspace-projection-based precoding schemes,
namely, full-projection (FP)- and partial-projection (PP)-based precoding, for
a cognitive radio multiple-input multiple-output (CR-MIMO) network to mitigate
its interference to a primary time-division-duplexing (TDD) system. The
proposed precoding schemes are capable of estimating interference channels
between CR and primary networks, and incorporating the interference from the
primary to the CR system into CR precoding via a novel sensing approach. Then,
the CR performance and resulting interference of the proposed precoding schemes
are analyzed and evaluated. By fully projecting the CR transmission onto a null
space of the interference channels, the FP-based precoding scheme can
effectively avoid interfering the primary system with boosted CR throughput.
While, the PP-based scheme is able to further improve the CR throughput by
partially projecting its transmission onto the null space.Comment: 12 pages, 4 figures, submitted to the IEEE Trans. Wireless
Communications in April 201
Peak to average power ratio based spatial spectrum sensing for cognitive radio systems
The recent convergence of wireless standards for incorporation of spatial dimension in wireless systems has made spatial spectrum sensing based on Peak to Average Power Ratio (PAPR) of the received signal, a promising approach. This added dimension is principally exploited for stream multiplexing, user multiplexing and spatial diversity. Considering such a wireless environment for primary users, we propose an algorithm for spectrum sensing by secondary users which are also equipped with multiple antennas. The proposed spatial spectrum sensing algorithm is based on the PAPR of the spatially received signals. Simulation results show the improved performance once the information regarding spatial diversity of the primary users is incorporated in the proposed algorithm. Moreover, through simulations a better performance is achieved by using different diversity schemes and different parameters like sensing time and scanning interval
- …