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In order to effectively detect multiple signals in severe time-dispersive channels for single-carrier multiple-input and multiple-output systems (SC-MIMO), this letter proposes a novel space-time nonlinear receiver structure with hybrid time-frequency domain processing. The proposed receiver consists of an internal and an outer iteration (i.e., doubly iterative) parts together they can efficiently...
In cognitive radio contexts, it is an important work to design an optimal spectrum sensing framework. Most of the previous work just focused on either the optimal sensing time (quiet period) or the maximal throughput constrained by the probability of detection or some interference level. In this paper, we propose an optimal spectrum sensing framework in cognitive radio contexts which jointly optimizes...
N-continuous has been proved to be an effective and simple way in reducing the out-of-band power radiation of orthogonal frequency division multiplexing (OFDM) signals. However, it achieves sidelobes reduction at the cost of additional distortion to data signals and requires iterative processing to reverse the transmitter processing. In this paper, a novel iterative receiver is proposed to estimate...
Peak-to-average power ratio (PAR) reduction and sidelobes suppression are two challenges in orthogonal frequency division multiplexing (OFDM) systems. Many methods have been proposed to reduce either PAR or out-of-band power. However, few have been reported for joint reduction for both of them in the literature so far. In this paper, serial peak cancellation for PAR reduction is combined with the...
Single carrier frequency division multiple access (SC-FDMA), which combines single carrier modulation with frequency domain equalization, is a promising transmission technique in 3GPP LTE. In this paper, for SC-FDMA signals, the issue of multiuser interference (MUI) suppression is investigated in interleaved FDMA (IFDMA) system. Under this system, carrier frequency offset (CFO) underlines the orthogonality...
The performance of an iterative decoding and noncoherent demodulating algorithm to suppress the multi-tone jamming (MTJ) in FH-CPM systems is studied in this paper. To reduce the complexity of the demodulator, an iterative tree search (ITS) method, based on Laurent decomposition, is exploited. And to enhance the reliability of the system, an iterative multi-tone jamming state information (MTJSI) estimation...
In this paper, we present an improved iterative interchannel interference (ICI) cancellation and signal detection technique for orthogonal frequency division multiplexing (OFDM) system on fast time-varying fading channel with nonintegral-delay. As a consequence of the time-varying channel, the orthogonality of subcarriers is destroyed, resulting in interchannel interference (ICI), which increases...
The existed preamble structure for orthogonal frequency division multiplex/offset QAM (OFDM/OQAM) system requires two zero-value guard symbols to guarantee ISI and ICI avoidance (equivalent to 3/2 complex value symbols in OFDM with cyclic prefix system), which leads to OFDM/OQAM system with low spectrum efficiency. In this paper, we shorten the preamble with 1 zero-value guard symbol to improve the...
In this paper, we proposed a partial-band jamming suppression algorithm especially for a slow frequency hopping system. In this system, continuous phase modulation (CPM) is adopted, and the algorithm is based on the iterative noncoherent CPM detection and the jamming state information (JSI) estimation. The complexity of the system is reduced by iterative tree search scheme rather than the exhaustive...
In practical wireless multiple-input multiple-output (MIMO) communications system, the channel estimation must be imperfect. Unfortunately, the channel estimation errors have not been taken into account by existing soft-output MIMO minimum mean square error (MMSE) vertical Bell lab space time (VBLAST) detectors when calculating the log-likelihood ratio (LLR) of each coded bit, i.e., the soft information...
In orthogonal frequency division multiplexing (OFDM)-based cognitive radio (CR) systems, the sub-carriers, which span the spectrum used by licensed users (LUs), should be deactivated to avoid interference. The resulted OFDM system is called non-contiguous OFDM (NC-OFDM) system. For NC-OFDM systems, as no pilot symbols can be transmitted over these deactivated subcarriers, the conventional modified...
To overcome the PAPR problem of conventional orthogonal frequency-division multiplexing (OFDM) system, a significant amount of methods have been proposed. However, there are few literatures considering the PAPR reduction for uplink orthogonal frequency division multiple access (OFDMA) system. In this paper, we focus on the PAPR reduction for random interleaved uplink OFDMA system. Firstly, the conventional...
In practical wireless multiple-input multiple-output (MIMO) communication systems, the channel estimation must be imperfect. Unfortunately, the channel estimation errors have not been taken into account by existing soft-output MIMO minimum mean square error (MMSE) ordering successive interference cancellation (OSIC) detectors when calculating the log-likelihood ratio of each coded bit, i.e., the soft...
In this paper, we address the problem of channel estimation in time-variant multi-path environment in Orthogonal frequency division multiplexing systems(OFDM). Based on the assumption that the channel varies in a linear fashion during an OFDM block duration, a novel iterative channel estimation arithmetic with noise and interference suppression using pilot tones is investigated. Through iterative...
Multiple-input multiple-output (MIMO) bit-interleaved coded modulation (BICM) has been proposed to apply in fast-fading environment. In this paper, we investigated the link-level capacity (LLC) and bit-error-rate (BER) performance of MIMO BICM system with soft-output MMSE soft interference cancellation (SIC) detection. We compared two SIC schemes in this paper. The first one is ordering successive...
Direct sequence code-division multiple access (DS-CDMA) and multicarrier (MC-) CDMA are two important CDMA schemes for high rate wireless communication. A novel linear per user minimum mean square error (PU-MMSE) detection technique for DS-CDMA with frequency domain equalization (FDE) based on the MMSE criterion applied per user is presented. It is shown by computer simulation that PU-MMSE outperforms...
A novel linear per user minimum mean square error (PU-MMSE) detection technique for direct sequence code- division multiple access (DS-CDMA) with frequency domain equalization (FDE) based on the MMSE criterion applied per user is presented, which approximately restores the orthogonality among the spreading sequences and reduces the interference. It is shown by computer simulation that the DS-CDMA...
There are two schemes to perform interference cancellation in soft-out minimum mean square error (MMSE) ordering successive interference cancellation (OSIC) detector for channel coded multiple-input multiple-output (MIMO) system, i.e., soft interference cancellation (SIC) and maximal likelihood (ML) hard decision based interference cancellation (HDIC). In this paper, we investigated these two schemes...
A turbo-type scheme that uses parallel concatenation and turbo block decision feedback equalization (TBDFE) is proposed to suppress linear intersymbol interference. Two design methods are investigated based on the minimum mean square error (MMSE) criterion. In the first algorithm, the hard-decision data output from one detector are used as input of the feedback filter in the other detector. In the...
A reduced-complexity minimum mean square error (MMSE) soft interference cancellation (SIC) based multiple-input multiple-output (MIMO) turbo receiver is proposed. In this new proposal, the computational complexity intensive part of the MMSE SIC detector is ignored if the reliability of the a priori information is larger than a specific threshold. As the co-antenna interference (CAI) of MIMO system...
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