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Recently, we proposed a joint iterative transmit/receive (Tx/Rx) minimum mean square error (MMSE) frequency-domain equalization (FDE) & inter-symbol interference (ISI) cancellation (ISIC) for single-carrier (SC) block transmissions. In this paper, we extend the previously proposed joint iterative Tx/Rx MMSE-FDE & ISIC to the SC hybrid automatic repeat request (HARQ) packet access to exploit...
In this paper, a single-carrier frequency domain adaptive antenna array (FDAAA) is proposed for the uplink transmission in cellular systems. The FDAAA algorithm will deal with co-channel interference and exploit the frequency selectivity of the channel fading jointly by using adaptive antenna array in the frequency domain. The receiver of the base station (BS) needs to adjust the AAA weight to optimize...
In this paper we consider SC-FDE schemes (Single-Carrier with Frequency-Domain Equalization) employing multi-resolution hierarchical constellations and we consider the design of turbo receivers, implemented in the frequency-domain, for systems where we have different error protections. We present a versatile method to design the receiver that is suitable to any constellation.
This paper presents a multiple-access MIMO wireless transceiver combining space- and frequency-domain spreadings with a frequency-domain block-coding strategy. Spreading across space (transmit antennas) and frequency (subcarriers) adds resilience against deep channel fades while providing space and frequency diversities, and block-coding enables multiple-access transmission. The merits of the proposed...
Conventionally, an interweave cognitive radio (CR) system can be developed based on the assumption of spectrum sharing between a wide-band CR system and some narrow-band primary systems. In this paper, we explode this assumption by constructing an interweave CR system using a hierarchical wide-band two-dimensional (2D) spread multi-carrier directed-sequenced code division multiple access (MC-DS-CDMA)...
In this paper, we propose two novel methods for downlink preamble detection and initial coarse time synchronization for mobile WiMAX systems and other OFDM Systems that adopt similar preamble structures. The two methods are based on frequency domain processing. The two methods are compared to the conventional time domain method for frame detection in WiMAX and to another frequency domain algorithm...
In this paper, both a time-domain and a frequency-domain 2 × 2 MIMO channel sounders are presented. The time-domain channel sounder is mainly based on the transmission of Code Division Multiplexed (CDM) signals, modulated by a carrier, which are received and acquired by an oscilloscope. The frequency-domain channel sounder is based on a multiport network analyzer which measures the S21 scattering...
In broadband wireless communication systems, single-carrier transmission with frequency domain equalization (SC-FDE) is regarded as an alternative modulation technique to the orthogonal frequency division multiplexing (OFDM). Compared with OFDM systems, SC-FDE has similar implementation complexity and performance. However, SC-FDE with linear equalizer will suffer from serious performance deterioration...
We propose a two-dimension adaptive spectral efficiency scheme for a new-designed single-carrier frequency division multiple access (SC-FDMA) system by flexible reference signal (RS) and data multiplexing for each user. Based on Doppler spread, each user first determines the number of SC-FDMA symbols that bear RS in a time slot, and each of such SC-FDMA symbols, based on bandwidth allocation, then...
For mitigating inter-symbol interference (ISI) and inter-carrier interference (ICI) caused by insufficient cyclic prefix (CP), per-tone equalizer (PTEQ) outperforms traditional time domain equalizer (TEQ) since each tone is equalized independently. However, PTEQ with equal number of taps (equal length) for all the tones can not achieve the optimal performance because channel conditions of different...
In the LTE-Advanced downlink, to satisfy high-level performance requirements, advanced multi-antenna transmission techniques such as higher-order single-user (SU)-MIMO, multi-user (MU)-MIMO, and coordinated multi-point transmission/reception (CoMP) are key. At the 3GPP RAN WG1 meeting, the demodulation reference signal (DM-RS) was defined to support channel estimation and data demodulation for up...
The peak-to-average power ratio (PAPR) of Nyquist filtered broadband single carrier (SC)-FDMA signals can be reduced by increasing the filter roll-off factor α. Furthermore, an additional frequency diversity gain can be obtained by making use of the excess bandwidth introduced by the transmit filtering. However, if the carrier-frequency separation is kept the same as in the case of α=0, the adjacent...
For the protection of incumbent users such as digital television (DTV), white space applications running on locally unused TV spectrum should be able to detect incumbent users at a low signal-to-noise ratio (SNR). Recent studies show that at a low SNR under high noise uncertainty, pilot detection performs better than other spectrum sensing methods such as energy detection and feature detection. The...
We discuss a novel pilot design for multi-user channel estimation in the OFDM uplink with localized block-type pilot placement. Due to this placement, multiple users' channels interfere with each other. By analyzing the properties of this multi-user interference, a criterium of choosing an appropriate DFT phase shift in frequency domain is derived. With this optimized shift, the multi-user interference...
This paper considers the design of linear frequency-domain receivers with oversampling for OQPSK (Offset Quaternary Phase Shift Keying) signals. Based on a receiver structure able to eliminate the residual interference between in-phase (I) and quadrature (Q) components at the sampling instants, a method that minimizes the overall residual ISI (Inter-Symbol Interference) plus IQI (I-Q interference)...
The frequency-domain filtered single-carrier (SC) signal transmission can achieve improved bit error rate (BER) performance due to additional frequency diversity gain while keeping a lower peak-to-average power ratio (PAPR) property than orthogonal frequency division multiplexing (OFDM). In this pa-per, we extend our recently proposed frequency-domain block signal detection (FDBD) with MLD employing...
Obtaining reliable channel state information (CSI) in future wireless standards is critical for the operation of downlink closed-loop techniques such as SU-MIMO, MU-MIMO, and coordinated multipoint (CoMP). However, this CSI is difficult to obtain especially when considering the potentially strong interference from neighboring sectors/base stations on the downlink reference symbols (RSs, aka pilot...
We propose a dual diagonal linear-minimum-mean-square-error (DD-LMMSE) channel estimation algorithm for orthogonal frequency division multiplexing (OFDM) systems involving joint channel estimation and signal detection. Computational complexity and mean-square-error (MSE) analysis are presented to evaluate the efficiency of the proposed algorithm. Compared with the optimal LMMSE method, the proposed...
The paper studies channel estimation methods with DRS in an OFDM system. As the DRS may only locate on part of the bandwidth, conventional methods, such as 2D Wiener filter and DFT based time domain estimation, cannot function well. A weighted averaging channel estimation method is proposed by which the channel responses estimated by LS estimation is averaged using Lagrange method. To verify the efficiency...
This paper presents a frequency-domain puncturing method for turbo codes. Conventional rate control for turbo codes is achieved by time-domain puncturing where some of the coded bits (parity bits) are punctured to increase the coding rate. The proposed puncturing method is done in the frequency domain. After applying the discrete Fourier transform (DFT) to the transmission coded symbols, some of the...
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