878 research outputs found
Power Allocation for Conventional and Buffer-Aided Link Adaptive Relaying Systems with Energy Harvesting Nodes
Energy harvesting (EH) nodes can play an important role in cooperative
communication systems which do not have a continuous power supply. In this
paper, we consider the optimization of conventional and buffer-aided link
adaptive EH relaying systems, where an EH source communicates with the
destination via an EH decode-and-forward relay. In conventional relaying,
source and relay transmit signals in consecutive time slots whereas in
buffer-aided link adaptive relaying, the state of the source-relay and
relay-destination channels determines whether the source or the relay is
selected for transmission. Our objective is to maximize the system throughput
over a finite number of transmission time slots for both relaying protocols. In
case of conventional relaying, we propose an offline and several online joint
source and relay transmit power allocation schemes. For offline power
allocation, we formulate an optimization problem which can be solved optimally.
For the online case, we propose a dynamic programming (DP) approach to compute
the optimal online transmit power. To alleviate the complexity inherent to DP,
we also propose several suboptimal online power allocation schemes. For
buffer-aided link adaptive relaying, we show that the joint offline
optimization of the source and relay transmit powers along with the link
selection results in a mixed integer non-linear program which we solve
optimally using the spatial branch-and-bound method. We also propose an
efficient online power allocation scheme and a naive online power allocation
scheme for buffer-aided link adaptive relaying. Our results show that link
adaptive relaying provides performance improvement over conventional relaying
at the expense of a higher computational complexity.Comment: Submitted to IEEE Transactions on Wireless Communication
Cross-Layer Optimization of Fast Video Delivery in Cache-Enabled Relaying Networks
This paper investigates the cross-layer optimization of fast video delivery
and caching for minimization of the overall video delivery time in a two-hop
relaying network. The half-duplex relay nodes are equipped with both a cache
and a buffer which facilitate joint scheduling of fetching and delivery to
exploit the channel diversity for improving the overall delivery performance.
The fast delivery control is formulated as a two-stage functional non-convex
optimization problem. By exploiting the underlying convex and quasi-convex
structures, the problem can be solved exactly and efficiently by the developed
algorithm. Simulation results show that significant caching and buffering gains
can be achieved with the proposed framework, which translates into a reduction
of the overall video delivery time. Besides, a trade-off between caching and
buffering gains is unveiled.Comment: 7 pages, 4 figures; accepted for presentation at IEEE Globecom, San
Diego, CA, Dec. 201
- …