712 research outputs found
Cooperative Energy Harvesting Networks with Spatially Random Users
This paper considers a cooperative network with multiple source-destination
pairs and one energy harvesting relay. The outage probability experienced by
users in this network is characterized by taking the spatial randomness of user
locations into consideration. In addition, the cooperation among users is
modeled as a canonical coalitional game and the grand coalition is shown to be
stable in the addressed scenario. Simulation results are provided to
demonstrate the accuracy of the developed analytical results
Energy Harvesting Cooperative Networks: Is the Max-Min Criterion Still Diversity-Optimal?
This paper considers a general energy harvesting cooperative network with M
source-destination (SD) pairs and one relay, where the relay schedules only m
user pairs for transmissions. For the special case of m = 1, the addressed
scheduling problem is equivalent to relay selection for the scenario with one
SD pair and M relays. In conventional cooperative networks, the max-min
selection criterion has been recognized as a diversity-optimal strategy for
relay selection and user scheduling. The main contribution of this paper is to
show that the use of the max-min criterion will result in loss of diversity
gains in energy harvesting cooperative networks. Particularly when only a
single user is scheduled, analytical results are developed to demonstrate that
the diversity gain achieved by the max-min criterion is only (M+1)/2, much less
than the maximal diversity gain M. The max-min criterion suffers this diversity
loss because it does not reflect the fact that the source-relay channels are
more important than the relay-destination channels in energy harvesting
networks. Motivated by this fact, a few user scheduling approaches tailored to
energy harvesting networks are developed and their performance is analyzed.
Simulation results are provided to demonstrate the accuracy of the developed
analytical results and facilitate the performance comparison.Comment: 30 pages, 7 figure
Dynamic Power Splitting Policies for AF Relay Networks with Wireless Energy Harvesting
Wireless energy harvesting (WEH) provides an exciting way to supply energy
for relay nodes to forward information for the source-destination pairs. In
this paper, we investigate the problem on how the relay node dynamically
adjusts the power splitting ratio of information transmission (IT) and energy
harvesting (EH) in order to achieve the optimal outage performance. According
to the knowledge of channel state information (CSI) at the relay, optimal
dynamic power splitting policy with full CSI and partial CSI are both provided.
Finally, through simulations, the proposed power splitting policies can improve
the outage performances and the policy with full CSI achieves the best
performance. It is also shown that the policy with partial CSI can approach the
policy with full CSI closely and incurs far less system overhead.Comment: accepted by IEEE ICC 2015 - Workshop on Green Communications and
Networks with Energy Harvesting, Smart Grids, and Renewable Energie
The Private Key Capacity of a Cooperative Pairwise-Independent Network
This paper studies the private key generation of a cooperative
pairwise-independent network (PIN) with M+2 terminals (Alice, Bob and M
relays), M >= 2. In this PIN, the correlated sources observed by every pair of
terminals are independent of those sources observed by any other pair of
terminal. All the terminals can communicate with each other over a public
channel which is also observed by Eve noiselessly. The objective is to generate
a private key between Alice and Bob under the help of the M relays; such a
private key needs to be protected not only from Eve but also from individual
relays simultaneously. The private key capacity of this PIN model is
established, whose lower bound is obtained by proposing a novel random binning
(RB) based key generation algorithm, and the upper bound is obtained based on
the construction of M enhanced source models. The two bounds are shown to be
exactly the same. Then, we consider a cooperative wireless network and use the
estimates of fading channels to generate private keys. It has been shown that
the proposed RB-based algorithm can achieve a multiplexing gain M-1, an
improvement in comparison with the existing XOR- based algorithm whose
achievable multiplexing gain is about [M]/2.Comment: 5 pages, 3 figures, IEEE ISIT 2015 (to appear
Resolution of Near-Field Beamforming and Its Impact on NOMA
The resolution of near-field beamforming is an important metric to measure
how effectively users with different locations can be located. This letter
identifies the condition under which the resolution of near-field beamforming
is not perfect. This imperfect resolution means that one user's near-field beam
can be still useful to other users, which motivates the application of
non-orthogonal multiple access (NOMA). Both the analytical and simulation
results are developed to demonstrate that those near-field beams preconfigured
for legacy users can indeed be used to effectively serve additional NOMA users,
which improves the overall connectivity and system throughput
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