58 research outputs found
Adaptive Multi-objective Optimization for Energy Efficient Interference Coordination in Multi-Cell Networks
In this paper, we investigate the distributed power allocation for multi-cell
OFDMA networks taking both energy efficiency and inter-cell interference (ICI)
mitigation into account. A performance metric termed as throughput contribution
is exploited to measure how ICI is effectively coordinated. To achieve a
distributed power allocation scheme for each base station (BS), the throughput
contribution of each BS to the network is first given based on a pricing
mechanism. Different from existing works, a biobjective problem is formulated
based on multi-objective optimization theory, which aims at maximizing the
throughput contribution of the BS to the network and minimizing its total power
consumption at the same time. Using the method of Pascoletti and Serafini
scalarization, the relationship between the varying parameters and minimal
solutions is revealed. Furthermore, to exploit the relationship an algorithm is
proposed based on which all the solutions on the boundary of the efficient set
can be achieved by adaptively adjusting the involved parameters. With the
obtained solution set, the decision maker has more choices on power allocation
schemes in terms of both energy consumption and throughput. Finally, the
performance of the algorithm is assessed by the simulation results.Comment: 29 page
Optimal Distributed Scheduling in Wireless Networks under the SINR interference model
Radio resource sharing mechanisms are key to ensuring good performance in
wireless networks. In their seminal paper \cite{tassiulas1}, Tassiulas and
Ephremides introduced the Maximum Weighted Scheduling algorithm, and proved its
throughput-optimality. Since then, there have been extensive research efforts
to devise distributed implementations of this algorithm. Recently, distributed
adaptive CSMA scheduling schemes \cite{jiang08} have been proposed and shown to
be optimal, without the need of message passing among transmitters. However
their analysis relies on the assumption that interference can be accurately
modelled by a simple interference graph. In this paper, we consider the more
realistic and challenging SINR interference model. We present {\it the first
distributed scheduling algorithms that (i) are optimal under the SINR
interference model, and (ii) that do not require any message passing}. They are
based on a combination of a simple and efficient power allocation strategy
referred to as {\it Power Packing} and randomization techniques. We first
devise algorithms that are rate-optimal in the sense that they perform as well
as the best centralized scheduling schemes in scenarios where each transmitter
is aware of the rate at which it should send packets to the corresponding
receiver. We then extend these algorithms so that they reach
throughput-optimality
Using Dedicated and Opportunistic Networks in Synergy for a Cost-effective Distributed Stream Processing Platform
This paper presents a case for exploiting the synergy of dedicated and
opportunistic network resources in a distributed hosting platform for data
stream processing applications. Our previous studies have demonstrated the
benefits of combining dedicated reliable resources with opportunistic resources
in case of high-throughput computing applications, where timely allocation of
the processing units is the primary concern. Since distributed stream
processing applications demand large volume of data transmission between the
processing sites at a consistent rate, adequate control over the network
resources is important here to assure a steady flow of processing. In this
paper, we propose a system model for the hybrid hosting platform where stream
processing servers installed at distributed sites are interconnected with a
combination of dedicated links and public Internet. Decentralized algorithms
have been developed for allocation of the two classes of network resources
among the competing tasks with an objective towards higher task throughput and
better utilization of expensive dedicated resources. Results from extensive
simulation study show that with proper management, systems exploiting the
synergy of dedicated and opportunistic resources yield considerably higher task
throughput and thus, higher return on investment over the systems solely using
expensive dedicated resources.Comment: 9 page
Cooperative Precoding with Limited Feedback for MIMO Interference Channels
Multi-antenna precoding effectively mitigates the interference in wireless
networks. However, the resultant performance gains can be significantly
compromised in practice if the precoder design fails to account for the
inaccuracy in the channel state information (CSI) feedback. This paper
addresses this issue by considering finite-rate CSI feedback from receivers to
their interfering transmitters in the two-user multiple-input-multiple-output
(MIMO) interference channel, called cooperative feedback, and proposing a
systematic method for designing transceivers comprising linear precoders and
equalizers. Specifically, each precoder/equalizer is decomposed into inner and
outer components for nulling the cross-link interference and achieving array
gain, respectively. The inner precoders/equalizers are further optimized to
suppress the residual interference resulting from finite-rate cooperative
feedback. Further- more, the residual interference is regulated by additional
scalar cooperative feedback signals that are designed to control transmission
power using different criteria including fixed interference margin and maximum
sum throughput. Finally, the required number of cooperative precoder feedback
bits is derived for limiting the throughput loss due to precoder quantization.Comment: 23 pages; 5 figures; this work was presented in part at Asilomar 2011
and will appear in IEEE Trans. on Wireless Com
Multicell Coordinated Beamforming with Rate Outage Constraint--Part I: Complexity Analysis
This paper studies the coordinated beamforming (CoBF) design in the
multiple-input single-output interference channel, assuming only channel
distribution information given a priori at the transmitters. The CoBF design is
formulated as an optimization problem that maximizes a predefined system
utility, e.g., the weighted sum rate or the weighted max-min-fairness (MMF)
rate, subject to constraints on the individual probability of rate outage and
power budget. While the problem is non-convex and appears difficult to handle
due to the intricate outage probability constraints, so far it is still unknown
if this outage constrained problem is computationally tractable. To answer
this, we conduct computational complexity analysis of the outage constrained
CoBF problem. Specifically, we show that the outage constrained CoBF problem
with the weighted sum rate utility is intrinsically difficult, i.e., NP-hard.
Moreover, the outage constrained CoBF problem with the weighted MMF rate
utility is also NP-hard except the case when all the transmitters are equipped
with single antenna. The presented analysis results confirm that efficient
approximation methods are indispensable to the outage constrained CoBF problem.Comment: submitted to IEEE Transactions on Signal Processin
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