688 research outputs found
Near-Optimal Energy-Efficient Joint Resource Allocation for Multi-Hop MIMO-AF Systems
Energy efficiency (EE) is becoming an important performance indicator for ensuring both the economical and environmental sustainability of the next generation of communication networks. Equally, cooperative communication is an effective way of improving communication system performances. In this paper, we propose a near-optimal energy-efficient joint resource allocation algorithm for multi-hop multiple-input-multiple-output (MIMO) amplify-and-forward (AF) systems. We first show how to simplify the multivariate unconstrained EE-based problem, based on the fact that this problem has a unique optimal solution, and then solve it by means of a low-complexity algorithm. We compare our approach with classic optimization tools in terms of energy efficiency as well as complexity, and results indicate the near-optimality and low-complexity of our approach. As an application, we use our approach to compare the EE of multi-hop MIMO-AF with MIMO systems and our results show that the former outperforms the latter mainly when the direct link quality is poor
Jointly Optimal Channel and Power Assignment for Dual-Hop Multi-channel Multi-user Relaying
We consider the problem of jointly optimizing channel pairing, channel-user
assignment, and power allocation, to maximize the weighted sum-rate, in a
single-relay cooperative system with multiple channels and multiple users.
Common relaying strategies are considered, and transmission power constraints
are imposed on both individual transmitters and the aggregate over all
transmitters. The joint optimization problem naturally leads to a mixed-integer
program. Despite the general expectation that such problems are intractable, we
construct an efficient algorithm to find an optimal solution, which incurs
computational complexity that is polynomial in the number of channels and the
number of users. We further demonstrate through numerical experiments that the
jointly optimal solution can significantly improve system performance over its
suboptimal alternatives.Comment: This is the full version of a paper to appear in the IEEE Journal on
Selected Areas in Communications, Special Issue on Cooperative Networking -
Challenges and Applications (Part II), October 201
Joint Relay Selection and Power Allocation in Large-Scale MIMO Systems with Untrusted Relays and Passive Eavesdroppers
In this paper, a joint relay selection and power allocation (JRP) scheme is
proposed to enhance the physical layer security of a cooperative network, where
a multiple antennas source communicates with a single-antenna destination in
presence of untrusted relays and passive eavesdroppers (Eves). The objective is
to protect the data confidentially while concurrently relying on the untrusted
relays as potential Eves to improve both the security and reliability of the
network. To realize this objective, we consider cooperative jamming performed
by the destination while JRP scheme is implemented. With the aim of maximizing
the instantaneous secrecy rate, we derive a new closed-form solution for the
optimal power allocation and propose a simple relay selection criterion under
two scenarios of non-colluding Eves (NCE) and colluding Eves (CE). For the
proposed scheme, a new closed-form expression is derived for the ergodic
secrecy rate (ESR) and the secrecy outage probability as security metrics, and
a new closed-form expression is presented for the average symbol error rate
(SER) as a reliability measure over Rayleigh fading channels. We further
explicitly characterize the high signal-to-noise ratio slope and power offset
of the ESR to highlight the impacts of system parameters on the ESR. In
addition, we examine the diversity order of the proposed scheme to reveal the
achievable secrecy performance advantage. Finally, the secrecy and reliability
diversity-multiplexing tradeoff of the optimized network are provided.
Numerical results highlight that the ESR performance of the proposed JRP scheme
for NCE and CE cases is increased with respect to the number of untrustworthy
relays.Comment: 18 pages, 10 figures, IEEE Transactions on Information Forensics and
Security (In press
Wireless Information and Energy Transfer for Two-Hop Non-Regenerative MIMO-OFDM Relay Networks
This paper investigates the simultaneous wireless information and energy
transfer for the non-regenerative multipleinput multiple-output orthogonal
frequency-division multiplexing (MIMO-OFDM) relaying system. By considering two
practical receiver architectures, we present two protocols, time switchingbased
relaying (TSR) and power splitting-based relaying (PSR). To explore the system
performance limit, we formulate two optimization problems to maximize the
end-to-end achievable information rate with the full channel state information
(CSI) assumption. Since both problems are non-convex and have no known solution
method, we firstly derive some explicit results by theoretical analysis and
then design effective algorithms for them. Numerical results show that the
performances of both protocols are greatly affected by the relay position.
Specifically, PSR and TSR show very different behaviors to the variation of
relay position. The achievable information rate of PSR monotonically decreases
when the relay moves from the source towards the destination, but for TSR, the
performance is relatively worse when the relay is placed in the middle of the
source and the destination. This is the first time to observe such a
phenomenon. In addition, it is also shown that PSR always outperforms TSR in
such a MIMO-OFDM relaying system. Moreover, the effect of the number of
antennas and the number of subcarriers are also discussed.Comment: 16 pages, 12 figures, to appear in IEEE Selected Areas in
Communication
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