7,042 research outputs found
Decoding Strategies at the Relay with Physical-Layer Network Coding
Cataloged from PDF version of article.A two-way relay channel is considered where two
users exchange information via a common relay in two transmission
phases using physical-layer network coding (PNC). We consider
an optimal decoding strategy at the relay to decode the network
coded sequence during the first transmission phase, which is
approximately implemented using a list decoding (LD) algorithm.
The algorithm jointly decodes the codewords transmitted by
the two users and sorts the L most likely pair of sequences
in the order of decreasing a-posteriori probabilities, based on
which, estimates of the most likely network coded sequences and
the decoding results are obtained. Using several examples, it is
observed that a lower complexity alternative, that jointly decodes
the two transmitted codewords, has a performance similar to the
LD based decoding and offers a near-optimal performance in
terms of the error rates corresponding to the XOR of the two
decoded sequences. To analyze the error rate at the relay, an
analytical approximation of the word-error rate using the joint
decoding (JD) scheme is evaluated over an AWGN channel using
an approach that remains valid for the general case of two users
adopting different codebooks and using different power levels.
We further extend our study to frequency selective channels
where two decoding approaches at the relay are investigated,
namely; a trellis based joint channel detector/physical-layer
network coded sequence decoder (JCD/PNCD) which is shown
to offer a near-optimal performance, and a reduced complexity
channel detection based on a linear receiver with minimum mean
squared error (MMSE) criterion which is particularly useful
where the number of channel taps is large
Random Linear Network Coding for 5G Mobile Video Delivery
An exponential increase in mobile video delivery will continue with the
demand for higher resolution, multi-view and large-scale multicast video
services. Novel fifth generation (5G) 3GPP New Radio (NR) standard will bring a
number of new opportunities for optimizing video delivery across both 5G core
and radio access networks. One of the promising approaches for video quality
adaptation, throughput enhancement and erasure protection is the use of
packet-level random linear network coding (RLNC). In this review paper, we
discuss the integration of RLNC into the 5G NR standard, building upon the
ideas and opportunities identified in 4G LTE. We explicitly identify and
discuss in detail novel 5G NR features that provide support for RLNC-based
video delivery in 5G, thus pointing out to the promising avenues for future
research.Comment: Invited paper for Special Issue "Network and Rateless Coding for
Video Streaming" - MDPI Informatio
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
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