14 research outputs found
Irregular Turbo Codes in Block-Fading Channels
We study irregular binary turbo codes over non-ergodic block-fading channels.
We first propose an extension of channel multiplexers initially designed for
regular turbo codes. We then show that, using these multiplexers, irregular
turbo codes that exhibit a small decoding threshold over the ergodic
Gaussian-noise channel perform very close to the outage probability on
block-fading channels, from both density evolution and finite-length
perspectives.Comment: to be presented at the IEEE International Symposium on Information
Theory, 201
On the Diversity and Coded Modulation Design of Fluid Antenna Systems
Reconfigurability is a desired characteristic of future communication
networks. From a transceiver's standpoint, this can be materialized through the
implementation of fluid antennas (FAs). An FA consists of a dielectric holder,
in which a radiating liquid moves between pre-defined locations (called ports)
that serve as the transceiver's antennas. Due to the nature of liquids, FAs can
practically take any size and shape, making them both flexible and
reconfigurable. In this paper, we deal with the outage probability of FAs under
general fading channels, where a port is scheduled based on selection
combining. An analytical framework is provided for the performance with and
without estimation errors, as a result of post-scheduling delays. We show that
although FAs achieve maximum diversity, this cannot be realized in the presence
of delays. Hence, a linear prediction scheme is proposed that overcomes delays
and restores the lost diversity by predicting the next scheduled port.
Moreover, we design space-time coded modulations that exploit the FA's
sequential operation with space-time rotations and code diversity. The derived
expressions for the pairwise error probability and average word error rate give
an accurate estimate of the performance. We illustrate that the proposed design
attains maximum diversity, while keeping a low-complexity receiver, thereby
confirming the feasibility of FAs.Comment: IEEE Transactions on Wireless Communication
On the Diversity and Coded Modulation Design of Fluid Antenna Systems
Reconfigurability is a desired characteristic of future communication networks. From a transceiver’s standpoint, this can be materialized through the implementation of fluid antennas (FAs). An FA consists of a dielectric holder, in which a radiating liquid moves between pre-defined locations (called ports) that serve as the transceiver’s antennas. Due to the nature of liquids, FAs can practically take any size and shape, making them both flexible and reconfigurable. In this paper, we deal with the outage probability of FAs under general fading channels, where a port is scheduled based on selection combining. An analytical framework is provided for the performance with and without errors due to post-scheduling delays. We show that although FAs achieve maximum diversity, this cannot be realized in the presence of delays. Hence, a linear prediction scheme is proposed that overcomes delays and restores the lost diversity by predicting the next scheduled port. Moreover, we design space-time coded modulations that exploit the FA’s sequential operation with space-time rotations and code diversity. The derived expressions for the pairwise error probability and average word error rate give an accurate estimate of the performance. We illustrate that the proposed design attains maximum diversity, while keeping a low-complexity receiver, thereby confirming the feasibility of FAs
Spatial Modulation with Energy Detection: Diversity Analysis and Experimental Evaluation
In this paper, we present a non-coherent energy detection scheme for spatial
modulation (SM) systems. In particular, the use of SM is motivated by its
low-complexity implementation in comparison to multiple-input multiple-output
(MIMO) systems, achieved through the activation of a single antenna during
transmission. Moreover, energy detection-based communications restrict the
channel state information to the magnitude of the fading gains. This
consideration makes the design applicable for low-cost low-powered devices
since phase estimation and its associated circuitry are avoided. We derive an
energy detection metric for a multi-antenna receiver based on the
maximum-likelihood (ML) criterion. By considering a biased pulse amplitude
modulation, we develop an analytical framework for the SM symbol error rate at
high signal-to-noise ratios. Numerical results show that the diversity order is
proportional to half the number of receive antennas; this result stems from
having partial receiver channel knowledge. In addition, we compare the
performance of the proposed scheme with that of the coherent ML receiver and
show that the SM energy detector outperforms its coherent counterpart in
certain scenarios, particularly when utilizing non-negative constellations.
Ultimately, we implement an SM testbed using software-defined radio devices and
provide experimental error rate measurements that validate our theoretical
contribution.Comment: This work has been submitted to an IEEE journal for possible
publicatio