6,685 research outputs found
Maximising Average Energy Efficiency for Two-User AWGN Broadcast Channel
Energy consumption has become an increasingly important aspect of
wireless communications, from both an economical and environmental point of
view. New enhancements are being placed on mobile networks to reduce the power
consumption of both mobile terminals and base stations. This paper studies the
achievable rate region of AWGN broadcast channels under Time-division,
Frequency-division and Superposition coding, and locates the optimal energyefficient
rate-pair according to a comparison metric based on the average energy
efficiency of the system. In addition to the transmit power, circuit power and
signalling power are also incorporated in the energy efficiency function, with
simulation results verifying that the Superposition coding scheme achieves the
highest energy efficiency in an ideal, but non-realistic scenario, where the signalling
power is zero. With moderate signalling power, the Frequency-division scheme is
the most energy-efficient, with Superposition coding and Time-division becoming
second and third best. Conversely, when the signalling power is high, both Timedivision
and Frequency-division schemes outperform Superposition coding. On the
other hand, the Superposition coding scheme also incorporates rate-fairness into the
system, which allows both users to transmit whilst maximising the energy efficiency
Uplink CoMP under a Constrained Backhaul and Imperfect Channel Knowledge
Coordinated Multi-Point (CoMP) is known to be a key technology for next
generation mobile communications systems, as it allows to overcome the burden
of inter-cell interference. Especially in the uplink, it is likely that
interference exploitation schemes will be used in the near future, as they can
be used with legacy terminals and require no or little changes in
standardization. Major drawbacks, however, are the extent of additional
backhaul infrastructure needed, and the sensitivity to imperfect channel
knowledge. This paper jointly addresses both issues in a new framework
incorporating a multitude of proposed theoretical uplink CoMP concepts, which
are then put into perspective with practical CoMP algorithms. This
comprehensive analysis provides new insight into the potential usage of uplink
CoMP in next generation wireless communications systems.Comment: Submitted to IEEE Transactions on Wireless Communications in February
201
Outage analysis of superposition modulation aided network coded cooperation in the presence of network coding noise
We consider a network, where multiple sourcedestination pairs communicate with the aid of a half-duplex relay node (RN), which adopts decode-forward (DF) relaying and superposition-modulation (SPM) for combining the signals transmitted by the source nodes (SNs) and then forwards the composite signal to all the destination nodes (DNs). Each DN extracts the signals transmitted by its own SN from the composite signal by subtracting the signals overheard from the unwanted SNs. We derive tight lower-bounds for the outage probability for transmission over Rayleigh fading channels and invoke diversity combining at the DNs, which is validated by simulation for both the symmetric and the asymmetric network configurations. For the high signal-to-noise ratio regime, we derive both an upperbound as well as a lower-bound for the outage performance and analyse the achievable diversity gain. It is revealed that a diversity order of 2 is achieved, regardless of the number of SN-DN pairs in the network. We also highlight the fact that the outage performance is dominated by the quality of the worst overheated link, because it contributes most substantially to the network coding noise. Finally, we use the lower bound for designing a relay selection scheme for the proposed SPM based network coded cooperative communication (SPM-NC-CC) system.<br/
A Cooperative Network Coding Strategy for the Interference Relay Channel.
In this paper, we study an interference relay network with a satellite as relay. We propose a cooperative strategy based on physical layer network coding and superposition modulation decoding for uni-directional communications among users. The performance of our solution in terms of throughput is evaluated through capacity analysis and simulations that include practical constraints such as the lack of synchronization in time and frequency.We obtain a significant throughput gain compared to the classical time sharing case
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