Blind Fractionally Spaced Equalization and timing synchronization in wireless fading channels

Abstract

The development of low-complexity blind techniques for equalization and timing synchronization is of enormous importance in the design of wireless communication systems. In this paper, we propose a practical solution for blind equalization and timing recovery in fast-fading time and frequency selective wireless communication channels. We develop a general framework for Constant Modulus Algorithm (CMA) based joint Fractionally Spaced Equalization (FSE) and timing recovery. We use differential modulation to deal with any arbitrary carrier offset. We propose a data reuse strategy to achieve improved short burst wireless communication in CMA based equalization systems. Our results show that FSE outperforms T -Spaced Equalization (TSE) with approximately 2 times faster Mean Square Error (MSE) convergence and approximately 2 dB gain in Bit Error Rate (BER) performance in wireless fading channels. In addition, we demonstrate that the BER performance of the proposed FSE receiver meets the theoretical bounds with only a few dB loss in Stanford University Interim (SUI) channels, which are relevant to IEEE 802.16.3c standard for Wireless Metropolitan Area Networks.

A Joint Timing and Fractionally-Space Blind Equalization Algorithm

“…3 can be given. Compared with multi-channel model, it is more similar to the structure of SRE, while it also has an extraction module and could be realized easier.FSE-CMA is that FSE adopts the equalization algorithm (coefficient updating algorithm) of CMA, according to the FSE single-channel realization structure [4] [8] .…”

A Joint Timing and Fractionally-Space Blind Equalization Algorithm

“…Many authors have studied in depth on the structure of FSE; the multichannel and single channel system model of FSE has been studied in [1][2] [3]. Channel system model of FSE can use single symbol rate to express the full signal transmission process, every sample points of each symbol can be viewed as a sub-channel, and therefore FSE can be transformed as multi-channel system model [4] [5] .…”

“…2), which is based on FSE's multi-channel system model. Compared with multi-channel model, it is more similar to the structure of SRE, while it also has an extraction module and could be realized easier.FSE-CMA is that FSE adopts the equalization algorithm (coefficient updating algorithm) of CMA, according to the FSE single-channel realization structure [4] [8] .…”

Blind Fractionally Spaced Channel Equalization for Shallow Water PPM Digital Communications Links

“…In particular, a modified cost function of the CMA is introduced, which results in both faster convergence and computational complexity reduction with respect to the standard RLS-CMA. In addition to ISI cancellation, fractionally spaced equalization allows a more efficient symbol timing recovery, see [15,16] for more details. The work in [15] presented a method for symbol timing recovery by tracking the shift of the equalizer taps.…”

“…The work in [15] presented a method for symbol timing recovery by tracking the shift of the equalizer taps. With the scheme described in [16], synchronization is restored by estimating the time derivative of the equalizer output modulus and then adjusting the timing offset in feedback mode through interpolation. However, equalization performance strictly depends on the initial phase the received fractionally sampled signal is locked to; to this regard, a blind sampling phase estimation technique has been presented in [17].…”