Adaptive time-frequency spreading of quasi-orthogonal block codes for MIMO-OFDM systems
Date
2006
Authors
Ong, Ju
Jayalath, Anagiyaddage Dhammik
Athaudage, Chandranath R
Journal Title
Journal ISSN
Volume Title
Publisher
Institute of Electrical and Electronics Engineers (IEEE Inc)
Abstract
This paper describes a novel low complexity time-frequency spreading of orthogonal block codes for MIMO-OFDM systems in highly time and frequency selective channels. The space-time codes (STC) and space-frequency codes (SFC) proposed in literature for MIMO-OFDM systems require a quasi-static channel, where the channel is assumed to be constant over a number of OFDM time symbols or OFDM subcarriers. In orthogonal block codes (OBC) this is equal to the number of transmit antennas Nt employed. For higher order space-diversity systems with Nt ≥ 4, it is likely that the assumption of constant channel within the OBC to be violated in fast fading channels resulting performance degradation. We propose an adaptive time-frequency spreading strategy that minimizes the decoding error rate in different types of fading channels. The adaptation technique incorporated is based on a fading interference matric, which is evaluated at the transmitter using channel fading statistics. Simulation results demonstrate the effectiveness of the proposed adaptive time-frequency spreading of OBCs.
Description
Keywords
Keywords: Communications systems; Frequency selective (FS) channels; international conferences; Low-complexity; MIMO-OFDM systems; Quasi Static; Singapore; Space frequency codes (SFC); Space-time codes (STCs); Sub-carriers; Time-frequency spreading; Transmit antenn
Citation
Collections
Source
Tenth IEEE International Conference on Communications Systems
Type
Conference paper