11,933 research outputs found
Capacity bounds for MIMO microwave backhaul links affected by phase noise
We present bounds and a closed-form high-SNR expression for the capacity of
multiple-antenna systems affected by Wiener phase noise. Our results are
developed for the scenario where a single oscillator drives all the
radio-frequency circuitries at each transceiver (common oscillator setup), the
input signal is subject to a peak-power constraint, and the channel matrix is
deterministic. This scenario is relevant for line-of-sight multiple-antenna
microwave backhaul links with sufficiently small antenna spacing at the
transceivers. For the 2 by 2 multiple-antenna case, for a Wiener phase-noise
process with standard deviation equal to 6 degrees, and at the medium/high SNR
values at which microwave backhaul links operate, the upper bound reported in
the paper exhibits a 3 dB gap from a lower bound obtained using 64-QAM.
Furthermore, in this SNR regime the closed-form high-SNR expression is shown to
be accurate.Comment: 10 pages, 2 figures, to appear in IEEE Transactions on Communication
A Multistage Method for SCMA Codebook Design Based on MDS Codes
Sparse Code Multiple Access (SCMA) has been recently proposed for the future
generation of wireless communication standards. SCMA system design involves
specifying several parameters. In order to simplify the procedure, most works
consider a multistage design approach. Two main stages are usually emphasized
in these methods: sparse signatures design (equivalently, resource allocation)
and codebook design. In this paper, we present a novel SCMA codebook design
method. The proposed method considers SCMA codebooks structured with an
underlying vector space obtained from classical block codes. In particular,
when using maximum distance separable (MDS) codes, our proposed design provides
maximum signal-space diversity with a relatively small alphabet. The use of
small alphabets also helps to maintain desired properties in the codebooks,
such as low peak-to-average power ratio and low-complexity detection.Comment: Submitted to IEEE Wireless Communication Letter
Inter-plane satellite matching in dense LEO constellations
Dense constellations of Low Earth Orbit (LEO) small satellites are envisioned
to make extensive use of the inter-satellite link (ISL). Within the same
orbital plane, the inter-satellite distances are preserved and the links are
rather stable. In contrast, the relative motion between planes makes the
inter-plane ISL challenging. In a dense set-up, each spacecraft has several
satellites in its coverage volume, but the time duration of each of these links
is small and the maximum number of active connections is limited by the
hardware. We analyze the matching problem of connecting satellites using the
inter-plane ISL for unicast transmissions. We present and evaluate the
performance of two solutions to the matching problem with any number of orbital
planes and up to two transceivers: a heuristic solution with the aim of
minimizing the total cost; and a Markovian solution to maintain the on-going
connections as long as possible. The Markovian algorithm reduces the time
needed to solve the matching up to 1000x and 10x with respect to the optimal
solution and to the heuristic solution, respectively, without compromising the
total cost. Our model includes power adaptation and optimizes the network
energy consumption as the exemplary cost in the evaluations, but any other
QoS-oriented KPI can be used instead
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