DocumentCode :
1132664
Title :
Exploiting Multipath Diversity in Multiple Antenna OFDM Systems With Spatially Correlated Channels
Author :
Rangaraj, G.V. ; Jalihal, Devendra ; Giridhar, K.
Author_Institution :
Telecommun. & Comput. Networks, Indian Inst. of Technol., Madras, India
Volume :
54
Issue :
4
fYear :
2005
fDate :
7/1/2005 12:00:00 AM
Firstpage :
1372
Lastpage :
1378
Abstract :
Multiple antennas are useful in orthogonal frequency division multiplexing (OFDM) systems for providing transmit and receive diversity to overcome fading. Typically, these designs require considerable separation between the antennas. Spatial correlation is introduced when antennas are not well separated, and it often leads to performance degradation in a flat fading environment. However, in frequency selective fading channels with rich multipath diversity, OFDM receivers can overcome this performance degradation due to antenna correlation. This is due to transformation of a highly spatially correlated channel impulse response to a less spatially correlated channel frequency response inherently by an OFDM system in the presence of rich multipath diversity. We illustrate this for a simple receive diversity OFDM system and hence introduce the concept of space sampling at the receiver where antennas are placed relatively close to each other. The minimum separation required between the antennas under such circumstances is derived analytically, and it is shown that even with a separation of only 0.44\\lambda , the required spatial correlation in the channel frequency response becomes sufficiently low. Simulated performance results with such spacing for various multiple antenna OFDM systems corroborate the analytical results.
Keywords :
OFDM modulation; antenna arrays; correlation methods; discrete Fourier transforms; diversity reception; fading channels; multiuser channels; receiving antennas; sampling methods; transient response; transmitting antennas; DFT; OFDM receivers; OFDM systems; antenna correlation; channel frequency response; correlated channel impulse response; flat fading environment; frequency selective fading channels; multipath diversity; multiple antenna; orthogonal frequency division multiplexing; receive diversity; space sampling; spatial correlation; spatially correlated channels; transmit diversity; Analytical models; Degradation; Fading; Frequency diversity; Frequency response; OFDM; Performance analysis; Receiving antennas; Sampling methods; Transmitting antennas; Frequency selective fading; OFDM; multipath diversity; multiple antennas; space sampling; spatial correlation;
fLanguage :
English
Journal_Title :
Vehicular Technology, IEEE Transactions on
Publisher :
ieee
ISSN :
0018-9545
Type :
jour
DOI :
10.1109/TVT.2005.851350
Filename :
1492690
Link To Document :
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