Pilot Symbol Assisted Adaptive Modulation for OFDM Systems with Imperfect Channel State Information

Author

Karami, Mahdi ; Olfat, Ali ; Beaulieu, Norman C.

Author_Institution

Dept. Electr. & Comp. Eng., Univ. of Alberta, Edmonton, AB, Canada

fYear

2010

fDate

6-10 Dec. 2010

Firstpage

1

Lastpage

6

Abstract

Adaptive modulation exhibits the advantage of great spectral efficiency for high data rate wireless transmission, where the transmission power and rate of subchannels in orthogonal frequency division multiplexing (OFDM) systems are matched to the channel state information (CSI). CSI can be acquired at the receiver by MMSE channel estimation based on pilot symbol assisted modulation (PSAM), which is a widely used technique, and fed back to the transmitter. While more accurate channel estimation will result in more reliable transmission, pilot symbols don´´t carry information and they impose an overhead on the system consuming power and bandwidth. An optimal adaptive PSAM scheme, that maximizes spectral efficiency by optimizing pilot power and spacing simultaneously is proposed. A rectangular pilot pattern is adopted to simplify the adaptive scheme.

Keywords

OFDM modulation; adaptive modulation; channel estimation; least mean squares methods; telecommunication network reliability; wireless channels; CSI; MMSE channel estimation; OFDM system; PSAM; high data rate wireless transmission; imperfect channel state information; orthogonal frequency division multiplexing system; pilot symbol assisted adaptive modulation; reliable transmission; spectral efficiency; Adaptive systems; Channel estimation; Modulation; OFDM; Receivers; Resource management; Transmitters;

fLanguage

English

Publisher

ieee

Conference_Titel

Global Telecommunications Conference (GLOBECOM 2010), 2010 IEEE

Conference_Location

Miami, FL

ISSN

1930-529X

Print_ISBN

978-1-4244-5636-9

Electronic_ISBN

1930-529X

Type

conf

DOI

10.1109/GLOCOM.2010.5683722

Filename

5683722