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We study the analog feedback of channel state infor- mation (CSI) in the massive multiple-input multiple-output or- thogonal frequency-division multiplexing (MIMO-OFDM) trans- mission. In a massive MIMO-OFDM system, the amount of CSI required by the transmitter increases linearly with the number of transmit antennas and subcarriers. To address this challenge, in this paper we propose a novel CSI feedback...
PMD incurs nonlinear noise in Stokes vector direct detection systems. We propose a novel algorithm to mitigate the PMD-induced nonlinear noise. DGD tolerance is improved from 4 to 10 ps for a 93-Gb/s signal.
In this paper we address the joint estimation of the channel impulse response in orthogonal frequency division multiplexing systems with phase distortion, namely phase noise and carrier frequency offset, phase noise bandwidth and the additive noise variance. The estimation algorithm is based on an implementation of the Extended Kalman Filter within the general framework of the Expectation-Maximization...
Orthogonal frequency division multiplexing (OFDM) is a leading technology in the field of broadband wireless communications. In OFDM systems, a high peak-to-average power ratio (PAPR) is a critical issue, which may cause a nonlinear distortion and reduce power efficiency. To reduce the PAPR, partial transmit sequences (PTS) technique can be applied to the transmit data. However, the phase factor sequence...
Multiuser MIMO (MU-MIMO) in general, and block diagonalization (BD) in particular, has become a crucial mechanism towards the achievement of a higher spectral efficiency in OFDMA-based wireless networks. The utilization of such techniques necessarily have implications in the resource allocation processes in charge of assigning subcarriers, powers and transmission modes among the different users. In...
This paper studies the impact of imperfect channel state information (CSI) due to limited feedback link on the performance of multi-user MIMO system using filter bank based multicarrier (FBMC) modulation. The system is composed of a transmitter performing Zero Forcing (ZF) precoding and single antenna receivers applying decoding techniques. Simulation-based results show that except when the number...
The problem of adaptively equalizing doubly dispersive MIMO channels for FBMC/OQAM systems is studied in this paper. The challenges in this type of multicarrier systems include their intrinsic self-interference and the need to cope with time- and frequency-selective subchannels in realistic propagation conditions. An efficient and numerically stable algorithm is adopted, relying on a decision feedback...
Spectral shaping is applied to Faster-Than-Nyquist (FTN) signaling to improve information rates. Under a transmit power constraint, the best shape is an inverse filter but for root raised cosine pulses this requires infinite power at the shaper input. Both input and output power constraints at the shaper are thus proposed as a solution to maximize the information rate while still guaranteeing practicality.
Nowadays, the OFDM support the growing request of higher data rate transportation in both wired and wireless communication. The SLM technique is recognized as one of the most capable methods which are applied in OFDM system in order to reduce the problem of high PAPR. However the major drawback of SLM is transmission of side information which has negative result on data rate and bandwidth efficiency...
Underwater acoustic (UWA) communication channel features relatively fast time variation. Spatial modulation (SM) combined with orthogonal frequency division multiplexing (OFDM) transmission can be applied to UWA communications. Channel estimation may induce a performance penalty for SM since only one transmit antenna is activated to carry pilots. Recently, a differential solution has been proposed...
The performance of orthogonal frequency division multiplexing interleave division multiple access (OFDM-IDMA) systems would be severely degraded by the inter-carrier interference (ICI) which is caused by multiple carrier frequency offsets (CFOs). Existing receivers with CFO mitigation capabilities either have extremely high complexities or suffer from performance loss compared with the conventional...
Cloud radio access network (C-RAN) is a next generation wireless access network architecture. In this architecture, common public radio interface (CPRI) links are widely used to transmit baseband signals. Currently, one of the great technical challenges for the C-RAN architecture is the soaring CPRI bandwidth required for data transmission between remote radio unit (RRU) and baseband unit (BBU). In...
Spectrally Efficient Frequency Division Multiplexing (SEFDM) is a non-orthogonal multicarrier communication technique that can pack more sub-carriers than Orthogonal Frequency Division Multiplexing (OFDM) in a given bandwidth. In this work, we propose a multi-band architecture named Block-Spectrally Efficient Frequency Division Multiplexing (B-SEFDM) for a large non-orthogonal system. Furthermore,...
Spectrally Efficient Frequency Division Multiplexing (SEFDM) is a non-orthogonal multi-carrier communication technique that can pack more sub-carriers than Orthogonal Frequency Division Multiplexing (OFDM) for a given bandwidth. In this paper, we propose a hybrid soft Iterative Detection (ID) together with Fixed Sphere Decoding (FSD) for QAM modulation schemes from 4QAM to 16QAM. In terms of 4QAM,...
Using selected mapping (SLM), chaotic-binary (CB) sequences have been successfully applied to reduce the peak-to-average power ratio (PAPR) of orthogonal frequency division multiplexing (OFDM) signals. However, high computational complexity associated with the construction of CB sequences make them unattractive in practical system. This paper presents an alternative source of SLM sequences, namely...
Recently, researches on wideband wireless communications have been investigated intensively. With the progress of wideband wireless communications, DOA estimation technique for wideband incident waves has been also required. The history of high-resolution wideband DOA estimation started several decades ago. However its standard technique is not developed yet. In this report, we have proposed a new...
Automatic modulation classification (AMC) has been a significant research topic in communication systems especially cognitive radio systems. The development of AMC algorithms is still at an immature stage for practical applications. In this paper, a supervised modulation classification scheme is proposed for automatic recognition of different types of communication signals. The supervised classification...
This paper presents a blind multi-user detection technique for multi-antenna quadrature amplitude modulation (QAM) receivers with Inphase/Quadrature phase (I/Q) imbalances. The estimation of multiple users in the presence of I/Q imbalances is performed by Blind Source Separation (BSS) methods. While the complex-valued signal model for multi-antenna QAM receivers does not lend itself to BSS due to...
Digital television terrestrial broadcasting (DTTB) industry has achieved rapid development in recent years. It is now facing new development opportunities for next-generation wireless broadcasting systems. As one of the DTTB standards, digital terrestrial multimedia/television broadcasting (DTMB) uses the time domain synchronous OFDM (TDS-OFDM) as its basic core technology. TDS-OFDM has higher spectral...
We consider a multiuser scenario with a center node for data fusion, where simultaneously transmitting is required in real time and with low probability of interception. We established a novel multiple access scheme, named matrix division multiple access (MDMA), based on OFDM technology. Precoded with different matrices, the signal from different end nodes can be distinguished due to the signal space...
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