4,298 research outputs found
An Adaptive Fault-Tolerant Communication Scheme for Body Sensor Networks
A high degree of reliability for critical data transmission is required in
body sensor networks (BSNs). However, BSNs are usually vulnerable to channel
impairments due to body fading effect and RF interference, which may
potentially cause data transmission to be unreliable. In this paper, an
adaptive and flexible fault-tolerant communication scheme for BSNs, namely
AFTCS, is proposed. AFTCS adopts a channel bandwidth reservation strategy to
provide reliable data transmission when channel impairments occur. In order to
fulfill the reliability requirements of critical sensors, fault-tolerant
priority and queue are employed to adaptively adjust the channel bandwidth
allocation. Simulation results show that AFTCS can alleviate the effect of
channel impairments, while yielding lower packet loss rate and latency for
critical sensors at runtime.Comment: 10 figures, 19 page
Simultaneous Transmission and Reception: Algorithm, Design and System Level Performance
Full Duplex or Simultaneous transmission and reception (STR) in the same
frequency at the same time can potentially double the physical layer capacity.
However, high power transmit signal will appear at receive chain as echoes with
powers much higher than the desired received signal. Therefore, in order to
achieve the potential gain, it is imperative to cancel these echoes. As these
high power echoes can saturate low noise amplifier (LNA) and also digital
domain echo cancellation requires unrealistically high resolution
analog-to-digital converter (ADC), the echoes should be cancelled or suppressed
sufficiently before LNA. In this paper we present a closed-loop echo
cancellation technique which can be implemented purely in analogue domain. The
advantages of our method are multiple-fold: it is robust to phase noise, does
not require additional set of antennas, can be applied to wideband signals and
the performance is irrelevant to radio frequency (RF) impairments in transmit
chain. Next, we study a few protocols for STR systems in carrier sense multiple
access (CSMA) network and investigate MAC level throughput with realistic
assumptions in both single cell and multiple cells. We show that STR can reduce
hidden node problem in CSMA network and produce gains of up to 279% in maximum
throughput in such networks. Finally, we investigate the application of STR in
cellular systems and study two new unique interferences introduced to the
system due to STR, namely BS-BS interference and UE-UE interference. We show
that these two new interferences will hugely degrade system performance if not
treated appropriately. We propose novel methods to reduce both interferences
and investigate the performances in system level.Comment: 20 pages. This manuscript will appear in the IEEE Transactions on
Wireless Communication
Rateless codes-based secure communication employing transmit antenna selection and harvest-to-jam under joint effect of interference and hardware impairments
In this paper, we propose a rateless codes-based communication protocol to provide security for wireless systems. In the proposed protocol, a source uses the transmit antenna selection (TAS) technique to transmit Fountain-encoded packets to a destination in presence of an eavesdropper. Moreover, a cooperative jammer node harvests energy from radio frequency (RF) signals of the source and the interference sources to generate jamming noises on the eavesdropper. The data transmission terminates as soon as the destination can receive a sufficient number of the encoded packets for decoding the original data of the source. To obtain secure communication, the destination must receive sufficient encoded packets before the eavesdropper. The combination of the TAS and harvest-to-jam techniques obtains the security and efficient energy via reducing the number of the data transmission, increasing the quality of the data channel, decreasing the quality of the eavesdropping channel, and supporting the energy for the jammer. The main contribution of this paper is to derive exact closed-form expressions of outage probability (OP), probability of successful and secure communication (SS), intercept probability (IP) and average number of time slots used by the source over Rayleigh fading channel under the joint impact of co-channel interference and hardware impairments. Then, Monte Carlo simulations are presented to verify the theoretical results.Web of Science217art. no. 70
A Unifying Framework for Local Throughput in Wireless Networks
With the increased competition for the electromagnetic spectrum, it is
important to characterize the impact of interference in the performance of a
wireless network, which is traditionally measured by its throughput. This paper
presents a unifying framework for characterizing the local throughput in
wireless networks. We first analyze the throughput of a probe link from a
connectivity perspective, in which a packet is successfully received if it does
not collide with other packets from nodes within its reach (called the audible
interferers). We then characterize the throughput from a
signal-to-interference-plus-noise ratio (SINR) perspective, in which a packet
is successfully received if the SINR exceeds some threshold, considering the
interference from all emitting nodes in the network. Our main contribution is
to generalize and unify various results scattered throughout the literature. In
particular, the proposed framework encompasses arbitrary wireless propagation
effects (e.g, Nakagami-m fading, Rician fading, or log-normal shadowing), as
well as arbitrary traffic patterns (e.g., slotted-synchronous,
slotted-asynchronous, or exponential-interarrivals traffic), allowing us to
draw more general conclusions about network performance than previously
available in the literature.Comment: Submitted for journal publicatio
- …