3,151 research outputs found
A scheme for cancelling intercarrier interference using conjugate transmission in multicarrier communication systems
To mitigate intercarrier interference (ICI), a two-path algorithm is developed for multicarrier communication systems, including orthogonal frequency division multiplexing (OFDM) systems. The first path employs the regular OFDM algorithm. The second path uses the conjugate transmission of the first path. The combination of both paths forms a conjugate ICI cancellation scheme at the receiver. This conjugate cancellation (CC) scheme provides (1) a high signal to interference power ratio (SIR) in the presence of small frequency offsets (50 dB and 33 dB higher than that of the regular OFDM and linear self-cancellation algorithms [1], [2], respectively, at ΔfT = 0.1% of subcarrier frequency spacing); (2) better bit error rate (BER) performance in both additive white Gaussian noise (AWGN) and fading channels; (3) backward compatibility with the existing OFDM system; (4) no channel equalization is needed for reducing ICI, a simple low cost receiver without increasing system complexity. Although the two-path transmission reduces bandwidth efficiency, the disadvantage can be balanced by increasing signal alphabet sizes
Alamouti OFDM/OQAM systems with time reversal technique
Orthogonal Frequency Division Multiplexing with Offset Quadrature Amplitude
Modulation (OFDM/OQAM) is a multicarrier modulation scheme that can be
considered as an alternative to the conventional Orthogonal Frequency Division
Multiplexing (OFDM) with Cyclic Prefix (CP) for transmission over multipath
fading channels. In this paper, we investigate the combination of the OFDM/OQAM
with Alamouti system with Time Reversal (TR) technique. TR can be viewed as a
precoding scheme which can be combined with OFDM/OQAM and easily carried out in
a Multiple Input Single Output (MISO) context such as Alamouti system. We
present the simulation results of the performance of OFDM/OQAM system in SISO
case compared with the conventional CP-OFDM system and the performance of the
combination Alamouti OFDM/OQAM with TR compared to Alamouti CP-OFDM. The
performance is derived by computing the Bit Error Rate (BER) as a function of
the transmit signal-to-noise ratio (SNR)
- …