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To improve wireless system performance using co-channel signals and multiple receiver antennas, we develop a new adaptive block-length partitioned Viterbi algorithm (ABL-PVA) receiver for the MIMO frequency-selective fading channel. The classic PVA has a trellis detector for each transmit antenna and feeds back tentative decisions between these trellis detectors which can cause error propagation....
Achieving an increase in the spectral efficiency (SE) has always been a major driver in the design of communication systems. The use of MIMO techniques in mobile communications has achieved significant benefits in improving the system throughput. The basic underlying concept of MIMO is to exploit the signal and channel characteristics to eliminate interference between multiple transmissions. Departing...
For massive MIMO systems, linear signal detectors, such as zero forcing (ZF) signal detector, can achieve the near-optimal performance, but usually involve high complexity due to the required matrix inversion of large size. In this paper, we propose a signal detector based on symmetric successive over-relaxation (SSOR) method without matrix inversion, which can reduce the complexity by one order of...
Carrier aggregation (CA) is a technique introduced in LTE-Advanced to achieve a higher throughput by increasing bandwidth. In this work, the spectrally efficient frequency division multiplexing (SEFDM) bandwidth compression technique is utilized to enhance CA performance. This work reports experimental demonstration of SEFDM and shows that up to 7 component carriers (CCs) can be aggregated in a given...
This paper presents a digital low-IF Gaussian frequency-shift keying (GFSK) demodulator. The demodulator is based on a phase-shift quadrature discriminator. A preamble detector controls the sequencing of the blocks operation to minimize power consumption. An IF input signal of 1 MHz is used, the same of the data rate, hence, allowing a low-power receiver implementation. The implementation is fully...
During the past decade, various two-dimensional magnetic recording (TDMR) systems have been considered or developed in order to achieve surface recording density of a few terabits or more per square inch for future promising magnetic recording technologies [1]. In most cases, an effective two-dimensional (2D) signal processing is expected to introduce these TDMR systems because originally these future...
Bit-patterned media recording (BPMR), heat (or microwave) assisted magnetic recording (HAMR) and shingled writing (SW)/two-dimensional magnetic recording (TDMR) have been primed to further increase the areal density of magnetic recording beyond 1Tb/in2[1-3]. However, with the reduction of the track pitch, inter-track interference (ITI) becomes a major impairment for these magnetic recording systems...
With the demands of increasing area density for the hard disk drive system, an array reader magnetic recording (ARMR) system [1][2] has been proposed to use signal processing and detection/ decoding to improve area density in near future before heat-assistant magnetic recording (HAMR) and bit pattern media (BPM) technologies can be mature enough for large volume production. In ARMR systems, two or...
A robust digital modulation scheme, called differential on-on keying (DOOK), is presented in this paper which outperforms the conventional on-off keying (OOK). In this scheme, a sinusoidal signal is transmitted during the first half of the bit duration while a replica or an inverted version of the sinusoidal signal is transmitted during the second half for logic one or logic zero, respectively. Non-coherent...
The faster-than-Nyquist (FTN) signaling is a bandwidth-efficient technology which has drawn attention in the bandwidth-starved world. Since the symbols appear too early, inter-symbol interference (ISI) cannot be avoided in the receiver. Decision feedback equalization (DFE) cancellation is an efficient interference cancellation and signal detection schemes for FTN based communication system. However,...
A real demand for underwater acoustic (UWA) communications exists in oceanography, ocean exploration and undersea navigation. A new Doppler resilient digital communication, based on quadratic frequency modulations (QFM) is presented. The binary information is transmitted using two orthogonal QFM chirps. This signal modulation is suitable for low-data-rate communication such as telemetry. The first...
In this paper we propose a new detection scheme for space-time block coded (STBC) systems over a flat Rayleigh fading channel. The new detector is derived for receivers having unknown channel state information (CSI) and carrier frequency offset (CFO). The proposed detector is based on a maximal ratio combiner (MRC) which optimizes the output in terms of maximum signal-to-noise ratio (SNR) along with...
Coded OFDM systems are generally employed to overcome the symbol recovery problem in uncoded OFDM systems that is caused due to loss of diversity in uncoded OFDM systems. In this paper, we extend our recent research work on low complexity post-coded OFDM (PC-OFDM) systems. We consider new spreading codes and detection algorithms for PC-OFDM in this paper. PC-OFDM systems introduce frequency diversity...
In this paper we study the use of projection pursuit[12] and independent component analysis[2] in blind demodulation of CDMA signals in the presence of high multiple access interference. The blind single-user receiver is assumed to be unaware of the signals transmitted by co-channel users. Conventionally, linear MMSE receivers have been applied to solve the problem[10]. However, it is well known that...
The role of advanced front-ends including spatial diversity, has been considered as an independent part of peak-distortion equalizers, Wiener and Viterbi equalizers. This involves that the optimum processing to remove point or distributed sources, together with inner and outer intersymbol interference is analyzed independently at the beamformer and at the equalizer stages. Recently, based on extensions...
Neural Networks can be used to estimate the a posteriori probabilities of the transmitted symbols in digital communication systems. In this paper we apply this property to the on-line estimation of the bit error rate (BER) in the receiver, without using any reference signal. We discuss two different approaches to BER estimation: (1) computing the a posteriori symbol probabilities from estimates of...
Maximum a posteriori (MAP) sequence detection for channels with intersymbol interference (ISI) has previously required knowledge of the channel sampled impulse response (SIR). Generally the SIR coefficients are determined via least mean square (LMS) or recursive least squares (RLS) estimation algorithms. For many unguided media channels such as mobile radio and high frequency radio which exhibit a...
In this work we present a low-complexity detection scheme for spatial modulation (SM) systems in the large-scale multiple access channel (MAC). The proposed strategy is based on compressive sensing (CS) and it exploits the sparsity and structure of the transmitted SM signals in the MAC to enhance the detection performance. The analytical and simulation results presented in this paper show that the...
Frequency-shift keying (FSK) is an orthogonal modulation technique that is primarily used in relatively low-rate communication systems that operate in the power-limited regime. Optimal noncoherent detection of FSK takes the form of sequence detection and has exponential complexity in the sequence length when implemented through an exhaustive search among all possible sequences. In this work, for the...
A scalable Impulse Radio (IR) Ultrawideband (UWB) air interface is proposed for Low Data Rate (LDR) Wireless Personal Area Network (WPAN) applications. Reduced-complexity transmitter and receiver designs are also proposed. The performance of the proposed IR-UWB multiuser system is investigated in PAN propagation environments. Various different receiver detection techniques are compared and it is shown...
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