Abstract
We propose combining channel estimation and optimal power allocation approaches for a multiple-antenna orthogonal frequency division multiplexing (OFDM) system in high-speed transmission applications. We develop a least-square channel estimation approach, derive the performance bound of the estimator, and investigate the optimal training sequences for initial channel acquisition. Based on the channel estimates, the optimal power allocation solution which maximizes the bandwidth efficiency is derived under power and quality of services (QoS) (symbol error rate) constraints. It is shown that combining channel tracking and adaptive power allocation can dramatically enhance the outage capacity of an OFDM multiple-antenna system when severe fading occurs.
Highlights
Orthogonal frequency division multiplexing (OFDM) technique has recently gained increasing interest as an effective alternative to conventional single tone modulation methods for high-rate communications systems [1, 2, 3]
The performance of the system is measured by bit error rate (BER) and the channel estimation mean square error (MSE), each averaged over 2500 OFDM blocks
It is observed that a significant increase in capacity can be obtained when the optimal power allocation is applied
Summary
Orthogonal frequency division multiplexing (OFDM) technique has recently gained increasing interest as an effective alternative to conventional single tone modulation methods for high-rate communications systems [1, 2, 3]. We first propose least-square (LS) channel estimation approach for OFDM multiple-antennas systems. Based on the channel estimates, the bandwidth efficiency is maximized by performing optimal power allocation over multiple antennas and subbands where some practical constraints such as specified quality of service (QoS) requirements in terms of symbol error probability and limited transmit power constraints are considered.
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