EE Seminar: Resource Allocation For LDPC-coded multi-carrier Downlink Channels
Speaker: Max Bluvshtein,
M.Sc. student under the supervision of Dr. Ofer Amrani
Wednesday, March 8th, 2017 at 15:00
Room 011, Kitot Bldg., Faculty of Engineering
Resource Allocation For LDPC-coded multi-carrier Downlink Channels
Abstract
Various techniques have been proposed to address the problem of resource allocation for multi-carrier communications, i.e. Orthogonal frequency-division multiplexing (OFDM) systems. They can be categorized by the type of criteria they aim at optimizing. These criteria, for the most part, arise either from information-theoretic measures such as channel capacity, or from measures that describe the error performance of a channel, which does not necessarily model the coding being employed.
In this work, we propose an optimization technique that is tailored for low density parity-check (LDPC) coded OFDM systems, by employing the so-called general stability condition introduced by Richardson et. al. ("Design of capacity-approaching irregular low-density parity-check codes"). The latter formulates a necessary condition for the Belief-Propagation (BP) decoder to perfectly decode a received vector with no errors.
We re-formulate the general condition so as to model practical multi-carrier/multi-user systems such as OFDMA and OFDRMA (OFDM with random multiple-access). By doing so, a general framework for resource allocation is laid down and employed herein to optimize the transmitted power based on the characteristics of LDPC-coded systems. Fortunately, a convex optimization problem is obtained, whose closed-form solution is elaborated upon in this work. The proposed optimization technique is utilized for performing power allocation in OFDMA and OFDMRA systems in a way that minimizes the transmitted power while guaranteeing reliable decoding.
To validate this technique, it is compared to information-theoretic methods that aim at optimizing the mutual-information between the transmitter and receiver. It is shown that both provide almost identical performance for all the scenarios addressed in this work.
