This letter proposes a method exploiting constructive interference (CI) to reduce the transmit signal’s peak-to-average power ratio (PAPR), while keeping total transmission as low possible. An optimization problem that jointly performs minimization and PAPR reduction is formulated, which however difficult solve directly due non-convex constraint. To obtain feasible solution in complexity, by us...

This paper analyzes the performance of linear and nonlinear multi-user detection (MUD) for an asynchronous OFDM-CDMA uplink transmission. Specifically, we regard linear MUD techniques such as the decorrelator and the MMSE approach as well as the nonlinear parallel interference cancellation (PIC) and their combination. It is pointed out that OFDM-CDMA systems offer a great advantage over single ...

This paper considers the uplink performance of a multi-user massive multiple-input multiple-output orthogonal frequency-division multiplexing (MIMO-OFDM) system with mobile users. Mobility brings two major problems to MIMO-OFDM system: inter carrier interference (ICI) and channel aging. In practice, it is common allot multiple contiguous subcarriers user as well schedule users on each subcarrie...

Orthogonal frequency division multiple-xing (OFDM) is an effective transmission method for cognitive radio system. This method provides high bandwidth and robustness against time dispersive channel. But OFDM inherits the high side lobe power and peak to average power ratio. High side lobe power of primary user (PU) distorts the signal of the secondary user (SU). In this paper we reduce the side...

Title of Dissertation: RESOURCE ALLOCATION ISSUES IN BROADBAND WIRELESS NETWORKS WITH OFDM SIGNALING Iordanis Koutsopoulos, Doctor of Philosophy, 2002 Dissertation directed by: Professor Leandros Tassiulas Department of Electrical and Computer Engineering Wireless broadband technologies are anticipated to flourish in the next few years, due to the increasing demand for wireless connectivity and...

System spectral efficiency and user fairness are crucial aspects for resource allocation in multi-user OFDM-based cellular networks. This work intends to investigate the influence of the performance of packet scheduling algorithms on the trade-off between these two objectives in scenarios with non real-time and real-time services. By means of system-level simulations, we were able to create a d...

In this paper, the relationship between time and frequency domain joint channel estimation (JCE) in multi-branch, i.e., multi-user and/or multiple antenna, systems is explained. It is proved that the design criterion of optimum pilots for frequency domain JCE can be deduced from the design criterion of optimum pilots for time domain JCE, and vice versa. This uncovers that the optimum pilots in ...

Abstract—In this contribution we propose new techniques for multi-user MISO broadcasting with Filter Bank based Multicarrier (FBMC) systems. FBMC is a prominent alternative to OFDM that can achieve higher bandwidth efficiency since no cyclic prefix is required. However, when extending FBMC to a multiantenna system, approaches that are used in OFDM can not be directly applied due to its special ...

The Orthogonal Frequency Division Multiplexing (OFDM) transmission technique can efficiently deal with multi-path propagation effects especially in broadband radio channels. It also has a high degree of system flexibility in multiple access schemes by combining the conventional TDMA, FDMA and CDMA approaches with the OFDM modulation procedure which is particularly important in the uplink of a m...

Cognitive radio (CR) is a promising concept for improving the utilization of scarce radio spectrum resources. Orthogonal frequency division multiplexing (OFDM) is regarded as a technology which is well-matched for CR systems. In this paper, it is shown that channel estimation errors can result in a severe performance degradation in a multi-user OFDM CR system. A simple back-off scheme is propos...