370 research outputs found
Outage Probability for Multi-Cell Processing under Rayleigh Fading
Multi-cell processing, also called Coordinated Multiple Point (CoMP), is a
very promising distributed multi-antennas technique that uses neighbour cell's
antennas. This is expected to be part of next generation cellular networks
standards such as LTE-A. Small cell networks in dense urban environment are
mainly limited by interferences and CoMP can strongly take advantage of this
fact to improve cell-edge users' throughput. This paper provides an analytical
derivation of the capacity outage probability for CoMP experiencing fast
Rayleigh fading. Only the average received power (slow varying fading) has to
be known, and perfect Channel State Information (CSI) is not required. An
optimisation of the successfully received data-rate is then derived with
respect to the number of cooperating stations and the outage probability,
illustrated by numerical examples
Demo: Non-classic Interference Alignment for Downlink Cellular Networks
Our demo aims at proving the concept of a recent proposed interference
management scheme that reduces the inter-cell interference in downlink without
complex coordination, known as non-classic interference alignment (IA) scheme.
We assume a case where one main Base Station (BS) needs to serve three users
equipments (UE) while another BS is causing interference. The primary goal is
to construct the alignment scheme ; i.e. each UE estimates the main and
interfered channel coefficients, calculates the optimal interference free
directions dropped by the interfering BS and feeds them back to the main BS
which in turn applies a scheduling to select the best free inter-cell
interference directions. Once the scheme is build, we are able to measure the
total capacity of the downlink interference channel. We run the scheme in
CorteXlab ; a controlled hardware facility located in Lyon, France with
remotely programmable radios and multi-node processing capabilities, and we
illustrate the achievable capacity gain for different channel realizations.Comment: Joint NEWCOM/COST Workshop on Wireless Communications JNCW 2015, Oct
2015, Barcelone, Spain. 201
Energy-delay bounds analysis in wireless multi-hop networks with unreliable radio links
Energy efficiency and transmission delay are very important parameters for
wireless multi-hop networks. Previous works that study energy efficiency and
delay are based on the assumption of reliable links. However, the unreliability
of the channel is inevitable in wireless multi-hop networks. This paper
investigates the trade-off between the energy consumption and the end-to-end
delay of multi-hop communications in a wireless network using an unreliable
link model. It provides a closed form expression of the lower bound on the
energy-delay trade-off for different channel models (AWGN, Raleigh flat fading
and Nakagami block-fading) in a linear network. These analytical results are
also verified in 2-dimensional Poisson networks using simulations. The main
contribution of this work is the use of a probabilistic link model to define
the energy efficiency of the system and capture the energy-delay trade-offs.
Hence, it provides a more realistic lower bound on both the energy efficiency
and the energy-delay trade-off since it does not restrict the study to the set
of perfect links as proposed in earlier works
Multiband CSMA/CA with RTS-CTS strategy
We present in this paper a new medium access control (MAC) scheme devoted to
orthogonal frequency division multiple access (OFDMA) systems which aims at
reducing collision probabilities during the channel request period. The
proposed MAC relies on the classical carrier sense multiple access/collision
avoidance (CSMA/CA) protocol with RTS / CTS ("Request To Send" / "Clear To
Send") mechanism. The proposed method focus on the collision probability of RTS
messages exploiting a multi-channel configuration for these messages while
using the whole band for data transmissions. The protocol may be interpreted as
an asynchronous frequency multiplexing of RTS messages. This method achieves
strong performance gains in terms of throughput and latency especially in
crowded networks. Index Terms-Carrier sense multiple access/collision avoidance
(CSMA/CA), multiband, throughput, MAC protocol
Noisy Channel-Output Feedback Capacity of the Linear Deterministic Interference Channel
In this paper, the capacity region of the two-user linear deterministic (LD)
interference channel with noisy output feedback (IC-NOF) is fully
characterized. This result allows the identification of several asymmetric
scenarios in which imple- menting channel-output feedback in only one of the
transmitter- receiver pairs is as beneficial as implementing it in both links,
in terms of achievable individual rate and sum-rate improvements w.r.t. the
case without feedback. In other scenarios, the use of channel-output feedback
in any of the transmitter-receiver pairs benefits only one of the two pairs in
terms of achievable individual rate improvements or simply, it turns out to be
useless, i.e., the capacity regions with and without feedback turn out to be
identical even in the full absence of noise in the feedback links.Comment: 5 pages, 9 figures, see proofs in V. Quintero, S. M. Perlaza, and
J.-M. Gorce, "Noisy channel-output feedback capacity of the linear
deterministic interference channel," INRIA, Tech. Rep. 456, Jan. 2015. This
was submitted and accepted in IEEE ITW 201
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