13,320 research outputs found
Joint Power Splitting and Secure Beamforming Design in the Wireless-powered Untrusted Relay Networks
In this work, we maximize the secrecy rate of the wireless-powered untrusted
relay network by jointly designing power splitting (PS) ratio and relay
beamforming with the proposed global optimal algorithm (GOA) and local optimal
algorithm (LOA). Different from the literature, artificial noise (AN) sent by
the destination not only degrades the channel condition of the eavesdropper to
improve the secrecy rate, but also becomes a new source of energy powering the
untrusted relay based on PS. Hence, it is of high economic benefits and
efficiency to take advantage of AN compared with the literature. Simulation
results show that LOA can achieve satisfactory secrecy rate performance
compared with that of GOA, but with less computation time.Comment: Submitted to GlobeCom201
Amplify-and-Forward in Wireless Relay Networks
A general class of wireless relay networks with a single source-destination
pair is considered. Intermediate nodes in the network employ an
amplify-and-forward scheme to relay their input signals. In this case the
overall input-output channel from the source via the relays to the destination
effectively behaves as an intersymbol interference channel with colored noise.
Unlike previous work we formulate the problem of the maximum achievable rate in
this setting as an optimization problem with no assumption on the network size,
topology, and received signal-to-noise ratio. Previous work considered only
scenarios wherein relays use all their power to amplify their received signals.
We demonstrate that this may not always maximize the maximal achievable rate in
amplify-and-forward relay networks. The proposed formulation allows us to not
only recover known results on the performance of the amplify-and-forward
schemes for some simple relay networks but also characterize the performance of
more complex amplify-and-forward relay networks which cannot be addressed in a
straightforward manner using existing approaches.
Using cut-set arguments, we derive simple upper bounds on the capacity of
general wireless relay networks. Through various examples, we show that a large
class of amplify-and-forward relay networks can achieve rates within a constant
factor of these upper bounds asymptotically in network parameters.Comment: Minor revision: fixed a typo in eqn. reference, changed the
formatting. 30 pages, 8 figure
Joint Computation and Communication Cooperation for Mobile Edge Computing
This paper proposes a novel joint computation and communication cooperation
approach in mobile edge computing (MEC) systems, which enables user cooperation
in both computation and communication for improving the MEC performance. In
particular, we consider a basic three-node MEC system that consists of a user
node, a helper node, and an access point (AP) node attached with an MEC server.
We focus on the user's latency-constrained computation over a finite block, and
develop a four-slot protocol for implementing the joint computation and
communication cooperation. Under this setup, we jointly optimize the
computation and communication resource allocation at both the user and the
helper, so as to minimize their total energy consumption subject to the user's
computation latency constraint. We provide the optimal solution to this
problem. Numerical results show that the proposed joint cooperation approach
significantly improves the computation capacity and the energy efficiency at
the user and helper nodes, as compared to other benchmark schemes without such
a joint design.Comment: 8 pages, 4 figure
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