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In this letter, we propose a low-complexity data-null subcarrier switching-based peak-to-average power ratio (PAPR) reduction scheme for the orthogonal frequency division multiplexing systems, which provides improved bit error rate. We perform the switching between the data and null subcarriers in such a way that distance between any two switched null subcarriers remains constant. This method can...
A recent transmission scheme called Packet-Appended Bit-Interleaved Coded Modulation with Iterative Decoding (PA-BICM-ID) consists in appending a conventional packet of Gray-labeled signals with some extra non-Gray-labeled signals in order to enable successful iterative decoding at the receiver side. In this paper, PA-BICM-ID is combined with Orthogonal Frequency Division Multiplexing (OFDM) with...
A continuous-switching type array antenna receiver has been proposed in order to reduce the deterioration due to fast-fading channel variations and improve communication performance. The receive antennas are placed in a linear array, and by sequentially switching the elements in the opposite direction to the direction of the train travel, it has been possible to fix the signal receiving point virtually...
A sequentially switched antenna array receiver (SSAAR) has been developed in order to lessen the fast-fading effects on super-express trains. The array elements are switched in reverse sequence to the direction of the train motion. To demonstrate the performance improvements, measurements were made using a scale model train with receiver moving at 3.6 km/h. A software simulation based on the Worldwide...
A clock-skew tolerant 8-bit 16x time-interleaved (TI) SAR ADC is presented that meets WiGig standard requirements with only background offset and gain calibrations. By using a “correct-by-construction”, timing-calibration-free global bottom-plate sampling scheme, the ADC achieves a sampling rate of 2.64GS/s while maintaining an ENOB of over 6 bits in the entire Nyquist band. The 40nm LP CMOS design...
The well-established low-cost broadband OFDM based wireless systems in license-exempt bands, including worldwide interoperability for microwave access (WiMAX) systems, have drawn considerable attention for radar related applications over the past decade. This paper explores an idea of utilizing Commercial Off-The-Shelf (COTS) WiMAX base stations (BSs) in unlicensed band for monostatic airborne synthetic...
This paper describes the evolution of powerline communications for the control of power distribution grids. First generation ripple control systems provide one-way communication, with which centralized load control and peak shaving have been performed for many years. The European standards body CENELEC restricted the use of frequencies between 3 kHz and 95 kHz for two-way communications for electricity...
Performances and capacity of MIMO-OFDM systems are enhanced with adaptive MIMO techniques such as Demmel condition number based switching algorithm. In this paper we show that the complexity of this algorithm can be reduced by using the 2-norm condition number of the channel matrix as the selection metric. Simulation results show that using this selection criterion, the switching algorithm offers...
Cognitive Radio (CR) technology is one of the promising technology to efficiently utilize the unused radio spectrum. Recently, the Federal Communications Commission (FCC) allowed TV white space (TVWS) to be used for data communications provided the licensed user operations should be protected. The FCC made the rules and regulation for using the TVWS. Till now there is no real deployment of any communication...
This paper proposes an advanced OFDM-MIMO reconfigurable architecture that uses an adaptive switching algorithm between diversity and spatial multiplexing. The transmitter blocs' specifications such as the MIMO technique and the modulation scheme are adjusted according to the channel state, which gives a practical cognitive radio strategy. The system cost- efficiency is performed by the application...
In this paper, we propose an adaptive transmission technique for MIMO-OFDM systems which selects one of space-time block coded OFDM (STBC-OFDM) and space-frequency block coded OFDM (SFBC-OFDM). STBC-OFDM and SFBC-OFDM undergo severe performance degradation in time-varying and frequency-selective channel, respectively. In the adaptive scheme, either STBC-OFDM or SFBC-OFDM is selected by using the proposed...
The parallel interaction medium access (PIMA) protocol is introduced to orchestrate channel access in a wireless ad hoc network when nodes are endowed with a single half- duplex radio, and can either transmit multiple packets to multiple destinations in parallel or receive multiple packets from multiple transmitters in parallel using OFDMA. Analytical and simulation results indicate that PIMA attains...
We propose QUEST (QUality ESTimation), a new method that accurately estimates IEEE 802.11 wireless link quality with no in-band signaling overhead. Existing link quality estimation methods either are based on hello exchanges by fixing or varying transmission rates or rely on the history (e.g., delivery ratio) of previously sent data packets in a per-rate/-neighbor manner. QUEST on the other hand,...
Some communication applications, like multimedia, deliver data of different importance classes allowing unequal error protection (UEP) levels. In this paper, a multiple-input multiple-output (MIMO) system using orthogonal frequency division multiplexing (OFDM) is considered with a new UEP bit-loading algorithm based on the non-UEP algorithm by Chow, Cioffi, and Bingham. In the proposed bit-loading...
Todaypsilas access network is migrating towards broadband IP, fixed/mobile convergence and service convergence. Thus, the next generation access network (NGAN) requires a converged optical/wireless access network infrastructure, other than the existing architecture that connect to the cellular, broadband wireless, and optical access networks separately, which complicate the network and increase the...
This paper addresses adaptive channel estimation for time-varying mobile wireless channels with nonstationary statistics. We presents a reduced complexity adaptive channel estimator based on a set membership filtering approach known as the Optimal Bounding Ellipsoid (OBE) algorithm. To exploit time and frequency domain correlation properties of the channel in an efficient low-complexity way, we allow...
Unequal error protection is the key to future transport of multimedia data. The paper presents an overview of some new approaches realizing UEP properties in physical transport, especially multicarrier modulation, or with LDPC and turbo codes. For multicarrier modulation, a UEP bit-loading method is described allowing for an arbitrary number of classes, arbitrary SNR margins between the classes and...
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