Low-Power VLSI Implementation of the Inner Receiver for OFDM-Based WLAN Systems

Synchronization Technique for OFDM-Based UWB System

“…In the design of frequency synchronizer, implementation of arctangent, sine and cosine functions is the most critical work since it decides the complexity of the synchronizer and the performance of the UWB receiver system. The traditional OFDM-based or CDMA-based systems usually employed classic coordinate rotation digital computer (CORDIC) algorithm for function evaluation (Tsai & Chiueh, 2007;Troya et al, 2008). Actually, there are other techniques for function evaluation, such as polynomial hyperfolding technique (PHT) (Caro et al, 2004), piecewise-polynomial approximation (PPA) technique (Caro & Steollo, 2005), hybrid CORDIC algorithm (Caro et al, 2009) and multipartite table method (MTM) (Caro et al, 2008).…”

VLSI Implementation of Auto-Correlation Architecture for Synchronization of MIMO-OFDM WLAN Systems

“…Although numerous synchronization algorithms for OFDM and MIMO-OFDM have been investigated, auto-correlation based synchronization is the most promising method, since it can be commonly used for frame detection, symbol timing synchronization and CFO estimation with moderate hardware complexity [1][2][3][4][5]. Therefore, a hardware efficient auto-correlation scheme needs to be developed for the CFO estimation of MIMO-OFDM systems.…”

“…In OFDM system, the auto-correlation is used to calculate the phase difference between two successive training symbols to estimate CFO value [1][2][3][4][5]. For MIMO system, these auto-correlation values can be simply combined using a maximal-ratio combining (MRC) which provides better performance because of improved receiver diversity [1].…”

“…N is an FFT size, ε is normalized CFO value. In [5], even though the delay registers for coarse CFO estimation (16 samples) and fine CFO estimation (64 samples) are shared for efficient design of a conventional SISO based WLAN, IEEE 802.11a, at least 64 delay registers are required for real and imaginary part, respectively. When the number of receiving antenna, N r , is 4, 256 delay registers are required for IEEE 802.11n legacy preamble, extension of 802.11a preamble, in order to perform the auto-correlation in (1).…”

“…Although, in [2], simple MIMO extension of single-input single-output (SISO) based OFDM synchronization for IEEE 802.11n is presented, it does not provide the significant improvement of the synchronization performance and the complex multipliers and delay registers for auto-correlation are increased by the number of receiving antennas. We have reviewed previous researches of synchronization-related hardware designs for SISO based OFDM [3][4][5]. For all the subsystems of the synchronizations, an efficient correlation scheme is commonly required.…”