1,831 research outputs found
Frame Based Precoding in Satellite Communications: A Multicast Approach
In the present work, a multibeam satellite that employs aggressive frequency
reuse towards increasing the offered throughput is considered. Focusing on the
forward link, the goal is to employ multi-antenna signal processing techniques,
namely linear precoding, to manage the inter-beam interferences. In this
context, fundamental practical limitations, namely the rigid framing structure
of satellite communication standards and the on-board per-antenna power
constraints, are herein considered. Therefore, the concept of optimal frame
based precoding under per-antenna constraints, is discussed. This consists in
precoding the transmit signals without changing the underlying framing
structure of the communication standard. In the present work, the connection of
the frame based precoding problem with the generic signal processing problem of
conveying independent sets of common data to distinct groups of users is
established. This model is known as physical layer multicasting to multiple
co-channel groups. Building on recent results, the weighted fair per-antenna
power constrained multigroup multicast precoders are employed for frame based
precoding. The throughput performance of these solutions is compared to
multicast aware heuristic precoding methods over a realistic multibeam
satellite scenario. Consequently, the gains of the proposed approach are
quantified via extensive numerical results.Comment: Accepted for presentation at the IEEE ASMS 201
Rationale for and design of a generic tiled hierarchical phased array beamforming architecture
The purpose of the phased array beamforming project is to develop a generic flexible efficient phased array receiver platform, using a mixed signal hardware/software-codesign approach. The results will be applicable to any radio (RF) system, but we will focus on satellite receiver (DVB-S) and radar applications. We will present a preliminary mapping of beamforming processing on a tiled architecture and determine its scalability.\ud
\ud
The functionality, size and cost constraints imply an integrated mixed signal CMOS solution. For a generic flexible multi-standard solution, a software defined radio approach is taken. Because a scalable and dependable solution is needed, a tiled hierarchical architecture is proposed with reconfigurable hardware to regain flexibility. A mapping is provided of beamforming on the proposed architecture. The advantages and disadvantages of each solution are discussed with respect to applicability and scalability.\ud
\ud
Different beamforming processing solutions can be mapped on the same proposed tiled hierarchical architecture. This provides a flexible, scalable and reconfigurable solution for a wide application domain. Beamforming is a data-driven streaming process which lends itself well for a regular scalable architecture. Beamsteering on the other hand is much more control-oriented and future work will focus on how to support beamsteering on the proposed architecture as well
Directional Modulation via Symbol-Level Precoding: A Way to Enhance Security
Wireless communication provides a wide coverage at the cost of exposing
information to unintended users. As an information-theoretic paradigm, secrecy
rate derives bounds for secure transmission when the channel to the
eavesdropper is known. However, such bounds are shown to be restrictive in
practice and may require exploitation of specialized coding schemes. In this
paper, we employ the concept of directional modulation and follow a signal
processing approach to enhance the security of multi-user MIMO communication
systems when a multi-antenna eavesdropper is present. Enhancing the security is
accomplished by increasing the symbol error rate at the eavesdropper. Unlike
the information-theoretic secrecy rate paradigm, we assume that the legitimate
transmitter is not aware of its channel to the eavesdropper, which is a more
realistic assumption. We examine the applicability of MIMO receiving algorithms
at the eavesdropper. Using the channel knowledge and the intended symbols for
the users, we design security enhancing symbol-level precoders for different
transmitter and eavesdropper antenna configurations. We transform each design
problem to a linearly constrained quadratic program and propose two solutions,
namely the iterative algorithm and one based on non-negative least squares, at
each scenario for a computationally-efficient modulation. Simulation results
verify the analysis and show that the designed precoders outperform the
benchmark scheme in terms of both power efficiency and security enhancement.Comment: This manuscript is submitted to IEEE Journal of Selected Topics in
Signal Processin
- …