553,977 research outputs found
Fundamentals of Inter-cell Overhead Signaling in Heterogeneous Cellular Networks
Heterogeneous base stations (e.g. picocells, microcells, femtocells and
distributed antennas) will become increasingly essential for cellular network
capacity and coverage. Up until now, little basic research has been done on the
fundamentals of managing so much infrastructure -- much of it unplanned --
together with the carefully planned macro-cellular network. Inter-cell
coordination is in principle an effective way of ensuring different
infrastructure components behave in a way that increases, rather than
decreases, the key quality of service (QoS) metrics. The success of such
coordination depends heavily on how the overhead is shared, and the rate and
delay of the overhead sharing. We develop a novel framework to quantify
overhead signaling for inter-cell coordination, which is usually ignored in
traditional 1-tier networks, and assumes even more importance in multi-tier
heterogeneous cellular networks (HCNs). We derive the overhead quality contour
for general K-tier HCNs -- the achievable set of overhead packet rate, size,
delay and outage probability -- in closed-form expressions or computable
integrals under general assumptions on overhead arrivals and different overhead
signaling methods (backhaul and/or wireless). The overhead quality contour is
further simplified for two widely used models of overhead arrivals: Poisson and
deterministic arrival process. This framework can be used in the design and
evaluation of any inter-cell coordination scheme. It also provides design
insights on backhaul and wireless overhead channels to handle specific overhead
signaling requirements.Comment: 21 pages, 9 figure
SLAP lesion in overhead athletes
http://www.ester.ee/record=b490536
Reducing Packet Overhead in Mobile IPv6
Common Mobile IPv6 mechanisms, Bidirectional tunneling and Route
optimization, show inefficient packet overhead when both nodes are mobile.
Researchers have proposed methods to reduce packet overhead regarding to
maintain compatible with standard mechanisms. In this paper, three mechanisms
in Mobile IPv6 are discussed to show their efficiency and performance.
Following discussion, a new mechanism called Improved Tunneling-based Route
Optimization is proposed and due to performance analysis, it is shown that
proposed mechanism has less overhead comparing to common mechanisms. Analytical
results indicate that Improved Tunneling-based Route Optimization transmits
more payloads due to send packets with less overhead
Surface code implementation of block code state distillation
State distillation is the process of taking a number of imperfect copies of a
particular quantum state and producing fewer better copies. Until recently, the
lowest overhead method of distilling states |A>=(|0>+e^{i\pi/4}|1>)/\sqrt{2}
produced a single improved |A> state given 15 input copies. New block code
state distillation methods can produce k improved |A> states given 3k+8 input
copies, potentially significantly reducing the overhead associated with state
distillation. We construct an explicit surface code implementation of block
code state distillation and quantitatively compare the overhead of this
approach to the old. We find that, using the best available techniques, for
parameters of practical interest, block code state distillation does not always
lead to lower overhead, and, when it does, the overhead reduction is typically
less than a factor of three.Comment: 26 pages, 28 figure
Measurement of SIFT operating system overhead
The overhead of the software implemented fault tolerance (SIFT) operating system was measured. Several versions of the operating system evolved. Each version represents different strategies employed to improve the measured performance. Three of these versions are analyzed. The internal data structures of the operating systems are discussed. The overhead of the SIFT operating system was found to be of two types: vote overhead and executive task overhead. Both types of overhead were found to be significant in all versions of the system. Improvements substantially reduced this overhead; even with these improvements, the operating system consumed well over 50% of the available processing time
Optimum Pilot Overhead in Wireless Communication: A Unified Treatment of Continuous and Block-Fading Channels
The optimization of the pilot overhead in single-user wireless fading
channels is investigated, and the dependence of this overhead on various system
parameters of interest (e.g., fading rate, signal-to-noise ratio) is
quantified. The achievable pilot-based spectral efficiency is expanded with
respect to the fading rate about the no-fading point, which leads to an
accurate order expansion for the pilot overhead. This expansion identifies that
the pilot overhead, as well as the spectral efficiency penalty with respect to
a reference system with genie-aided CSI (channel state information) at the
receiver, depend on the square root of the normalized Doppler frequency.
Furthermore, it is shown that the widely-used block fading model is only a
special case of more accurate continuous fading models in terms of the
achievable pilot-based spectral efficiency, and that the overhead optimization
for multiantenna systems is effectively the same as for single-antenna systems
with the normalized Doppler frequency multiplied by the number of transmit
antennas.Comment: Submitted to IEEE Trans. Wireless Communication
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