8,114 research outputs found
User-Antenna Selection for Physical-Layer Network Coding based on Euclidean Distance
In this paper, we present the error performance analysis of a multiple-input
multiple-output (MIMO) physical-layer network coding (PNC) system with two
different user-antenna selection (AS) schemes in asymmetric channel conditions.
For the first antenna selection scheme (AS1), where the user-antenna is
selected in order to maximize the overall channel gain between the user and the
relay, we give an explicit analytical proof that for binary modulations, the
system achieves full diversity order of in the
multiple-access (MA) phase, where , and denote the number of
antennas at user , user and relay respectively. We present a
detailed investigation of the diversity order for the MIMO-PNC system with AS1
in the MA phase for any modulation order. A tight closed-form upper bound on
the average SER is also derived for the special case when , which is
valid for any modulation order. We show that in this case the system fails to
achieve transmit diversity in the MA phase, as the system diversity order drops
to irrespective of the number of transmit antennas at the user nodes.
Additionally, we propose a Euclidean distance (ED) based user-antenna selection
scheme (AS2) which outperforms the first scheme in terms of error performance.
Moreover, by deriving upper and lower bounds on the diversity order for the
MIMO-PNC system with AS2, we show that this system enjoys both transmit and
receive diversity, achieving full diversity order of in the MA phase for any modulation order. Monte Carlo simulations are
provided which confirm the correctness of the derived analytical results.Comment: IEEE Transactions on Communications. arXiv admin note: text overlap
with arXiv:1709.0445
Capacity of Coded Index Modulation
We consider the special case of index coding over the Gaussian broadcast
channel where each receiver has prior knowledge of a subset of messages at the
transmitter and demands all the messages from the source. We propose a
concatenated coding scheme for this problem, using an index code for the
Gaussian channel as an inner code/modulation to exploit side information at the
receivers, and an outer code to attain coding gain against the channel noise.
We derive the capacity region of this scheme by viewing the resulting channel
as a multiple-access channel with many receivers, and relate it to the 'side
information gain' -- which is a measure of the advantage of a code in utilizing
receiver side information -- of the inner index code/modulation. We demonstrate
the utility of the proposed architecture by simulating the performance of an
index code/modulation concatenated with an off-the-shelf convolutional code
through bit-interleaved coded-modulation.Comment: To appear in Proc. IEEE Int. Symp. Inf. Theory (ISIT) 2015, Hong
Kong, Jun. 2015. 5 pages, 4 figure
Application of Expurgated PPM to Indoor Visible Light Communications - Part II: Access Networks
Providing network access for multiple users in a visible light communication
(VLC) system that utilizes white light emitting diodes (LED) as sources
requires new networking techniques adapted to the lighting features. In this
paper we introduce two multiple access techniques using expurgated PPM (EPPM)
that can be implemented using LEDs and support lighting features such as
dimming. Multilevel symbols are used to provide M-ary signaling for multiple
users using multilevel EPPM (MEPPM). Using these multiple-access schemes we are
able to control the optical peak to average power ratio (PAPR) in the system,
and hereby control the dimming level. In the first technique, the M-ary data of
each user is first encoded using an optical orthogonal code (OOC) assigned to
the user, and the result is fed into a EPPM encoder to generate a multilevel
signal. The second multiple access method uses sub-sets of the EPPM
constellation to apply MEPPM to the data of each user. While the first approach
has a larger Hamming distance between the symbols of each user, the latter can
provide higher bit-rates for users in VLC systems using bandwidth-limited LEDs.Comment: Journal of Lightwave Technology. arXiv admin note: substantial text
overlap with arXiv:1308.074
High-Speed Visible Light Indoor Networks Based on Optical Orthogonal Codes and Combinatorial Designs
Interconnecting devices in an indoor environment using the illumination
system and white light emitting diodes (LED) requires adaptive networking
techniques that can provide network access for multiple users. Two techniques
based on multilevel signaling and optical orthogonal codes (OOC) are explored
in this paper in order to provide simultaneous multiple access in an indoor
multiuser network. Balanced incomplete block designs (BIBD) are used to
construct multilevel symbols for M-ary signaling. Using these multilevel
symbols we are able to control the optical peak to average power ratio (PAPR)
in the system, and hereby control the dimming level. In the first technique,
the M-ary data of each user is first encoded using the OOC codeword that is
assigned to that user, and then it is fed into a BIBD encoder to generate a
multilevel signal. The second multiple access method uses sub-sets of a BIBD
code to apply multilevel expurgated pulse-position modulation (MEPPM) to the
data of each user. While the first approach has a larger Hamming distance
between the symbols of each user, the latter can provide higher bit-rates for
users in VLC systems with bandwidth-limited LEDs
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