234 research outputs found
Physical Layer Service Integration in 5G: Potentials and Challenges
High transmission rate and secure communication have been identified as the
key targets that need to be effectively addressed by fifth generation (5G)
wireless systems. In this context, the concept of physical-layer security
becomes attractive, as it can establish perfect security using only the
characteristics of wireless medium. Nonetheless, to further increase the
spectral efficiency, an emerging concept, termed physical-layer service
integration (PHY-SI), has been recognized as an effective means. Its basic idea
is to combine multiple coexisting services, i.e., multicast/broadcast service
and confidential service, into one integral service for one-time transmission
at the transmitter side. This article first provides a tutorial on typical
PHY-SI models. Furthermore, we propose some state-of-the-art solutions to
improve the overall performance of PHY-SI in certain important communication
scenarios. In particular, we highlight the extension of several concepts
borrowed from conventional single-service communications, such as artificial
noise (AN), eigenmode transmission etc., to the scenario of PHY-SI. These
techniques are shown to be effective in the design of reliable and robust
PHY-SI schemes. Finally, several potential research directions are identified
for future work.Comment: 12 pages, 7 figure
Secrecy Wireless Information and Power Transfer with MISO Beamforming
The dual use of radio signals for simultaneous wireless information and power
transfer (SWIPT) has recently drawn significant attention. To meet the
practical requirement that energy receivers (ERs) operate with significantly
higher received power as compared to information receivers (IRs), ERs need to
be deployed in more proximity to the transmitter than IRs. However, due to the
broadcast nature of wireless channels, one critical issue arises that the
messages sent to IRs can be eavesdropped by ERs, which possess better channels
from the transmitter. In this paper, we address this new secrecy communication
problem in a multiuser multiple-input single-output (MISO) SWIPT system where
one multi-antenna transmitter sends information and energy simultaneously to an
IR and multiple ERs, each with one single antenna. To optimally design transmit
beamforming vectors and their power allocation, two problems are investigated
with different aims: the first problem maximizes the secrecy rate for IR
subject to individual harvested energy constraints of ERs, while the second
problem maximizes the weighted sum-energy transferred to ERs subject to a
secrecy rate constraint for IR. We solve these two non-convex problems
optimally by reformulating each of them into a two-stage problem. First, by
fixing the signal-to-interference-plus-noise ratio (SINR) target for ERs (for
the first problem) or IR (for the second problem), we obtain the optimal
beamforming and power allocation solution by applying the technique of
semidefinite relaxation (SDR). Then, the original problems are solved by a
one-dimension search over the optimal SINR target for ERs or IR. Furthermore,
for each of the two studied problems, suboptimal solutions of lower complexity
are also proposed in which the information and energy beamforming vectors are
separately designed with their power allocation.Comment: accepted by IEEE Transactions on Signal Processing. Longer version of
arXiv:1306.096
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