Abstract: This paper presents the development of a single-ended 38.5 kS/s 10-bit programmable reference SAR ADC which is realized in MIMOS’s 0.35 µm CMOS process. The design uses a resistive DAC, a dynamic comparator with pre-amplifier and a SAR digital logic to create 10 effective bits ADC. A programmable reference circuitry allows the ADC to operate with different input range from 0.6 V to 2.1 V. The ADC consumed less than 7.5 mW power with a 3 V supply.
Abstract: Recently, increasing the quality of experience (QoE) is
an important issue. Since performance degradation at cell edge
extremely reduces the QoE, several techniques are defined at
LTE/LTE-A standard to remove inter-cell interference (ICI). However,
the conventional techniques have disadvantage because there is a
trade-off between resource allocation and reliable communication.
The proposed scheme reduces the ICI more efficiently by using
channel state information (CSI) smartly. It is shown that the proposed
scheme can reduce the ICI with fewer resources.
Abstract: The IEEE 802.22 working group aims to drive the
Digital Video Broadcasting-Terrestrial (DVB-T) bands for data
communication to the rural area without interfering the TV broadcast.
In this paper, we arrive at a closed-form expression for average
detection probability of Fusion center (FC) with multiple antenna
over the κ − μ fading channel model. We consider a centralized
cooperative multiple antenna network for reporting. The DVB-T
samples forwarded by the secondary user (SU) were combined using
Maximum ratio combiner at FC, an energy detection is performed
to make the decision. The fading effects of the channel degrades
the detection probability of the FC, a generalized independent and
identically distributed (IID) κ − μ and an additive white Gaussian
noise (AWGN) channel is considered for reporting and sensing
respectively. The proposed system performance is verified through
simulation results.
Abstract: This paper presents a 3D guidance scheme for
Unmanned Aerial Vehicles (UAVs). The proposed guidance scheme
is based on the sliding mode approach using nonlinear sliding
manifolds. Generalized 3D kinematic equations are considered
here during the design process to cater for the coupling between
longitudinal and lateral motions. Sliding mode based guidance
scheme is then derived for the multiple-input multiple-output
(MIMO) system using the proposed nonlinear manifolds. Instead of
traditional sliding surfaces, nonlinear sliding surfaces are proposed
here for performance and stability in all flight conditions. In the
reaching phase control inputs, the bang-bang terms with signum
functions are accompanied with proportional terms in order to reduce
the chattering amplitudes. The Proposed 3D guidance scheme is
implemented on a 6-degrees-of-freedom (6-dof) simulation of a UAV
and simulation results are presented here for different 3D trajectories
with and without disturbances.
Abstract: This paper proposes a cooperative Alamouti space time
transmission scheme with low relay complexity for the cooperative
communication systems. In the proposed scheme, the source node
combines the data symbols to construct the Alamouti-coded form at
the destination node, while the conventional scheme performs the
corresponding operations at the relay nodes. In simulation results,
it is shown that the proposed scheme achieves the second order
cooperative diversity while maintaining the same bit error rate (BER)
performance as that of the conventional scheme.
Abstract: This paper describes a node pair selection scheme
in relay-aided multiple source multiple destination communication
system based on stable marriage problem. A general case is assumed
in which all of source, relay and destination nodes are equipped
with multiantenna and carry out multistream transmission. Based
on several metrics introduced from inter-node channel condition,
the preference order is determined about all source-relay and
relay-destination relations, and then the node pairs are determined
using Gale-Shapley algorithm. The computer simulations show
that the effectiveness of node pair selection is larger in multihop
communication. Some additional aspects which are different from
relay-less case are also investigated.
Abstract: Cooperative communication systems are considered to be a promising technology to improve the system capacity, reliability and performances over fading wireless channels. Cooperative relaying system with a single antenna will be able to reach the advantages of multiple antenna communication systems. It is ideally suitable for the distributed communication systems; the relays can cooperate and form virtual MIMO systems. Thus the paper will aim to investigate the possible enhancement of cooperated system using decode and forward protocol. On the decode and forward an attempt to cancel or at least reduce the interference instead of increasing the SNR values is achieved. The latter can be achieved via the use group of relays depending on the channel status from source to relay and relay to destination respectively.
In the proposed system, the transmission time has been divided into two phases to be used by the decode and forward protocol. The first phase has been allocated for the source to transmit its data whereas the relays and destination nodes are in receiving mode. On the other hand, the second phase is allocated for the first and second groups of relay nodes to relay the data to the destination node. Simulations results have shown an improvement in performance is achieved compared to the conventional decode and forward in terms of BER and transmission rate.
Abstract: In this paper, we propose an efficient signal detector that switches M parameter of QRD-M detection scheme is proposed for MIMO-OFDM system. The proposed detection scheme calculates the threshold by 1-norm condition number and then switches M parameter of QRD-M detection scheme according to channel information. If channel condition is bad, the parameter M is set to high value to increase the accuracy of detection. If channel condition is good, the parameter M is set to low value to reduce complexity of detection. Therefore, the proposed detection scheme has better tradeoff between BER performance and complexity than the conventional detection scheme. The simulation result shows that the complexity of proposed detection scheme is lower than QRD-M detection scheme with similar BER performance.
Abstract: Recently, among the MIMO-OFDM detection techniques, a lot of papers suggested V-BLAST scheme which can achieve high data rate. Therefore, the signal detection of MIMO-OFDM system is important issue. In this paper, efficient iterative V-BLAST detection technique is proposed in wireless communication system. The proposed scheme adjusts the number of candidate symbol and iterative scheme based on channel state. According to the simulation result, the proposed scheme has better BER performance than conventional schemes and similar BER performance of the QRD-M with iterative scheme. Moreover complexity of proposed scheme has 50.6% less than complexity of QRD-M detection with iterative scheme. Therefore the proposed detection scheme can be efficiently used in wireless communication.
Abstract: Performance of Orthogonal Frequency Division Multiplexing (OFDM) system can be improved by adding channel coding (error correction code) to detect and correct errors that occur during data transmission. One can use the convolution code. This paper present performance of OFDM using Space Time Block Codes (STBC) diversity technique use QAM modulation with code rate ½. The evaluation is done by analyzing the value of Bit Error Rate (BER) vs. Energy per Bit to Noise Power Spectral Density Ratio (Eb/No). This scheme is conducted 256 subcarrier transmits Rayleigh multipath channel in OFDM system. To achieve a BER of 10-3 is required 10dB SNR in SISO-OFDM scheme. For 2x2 MIMO-OFDM scheme requires 10 dB to achieve a BER of 10-3. For 4x4 MIMO-OFDM scheme requires 5 dB while adding convolution in a 4x4 MIMO-OFDM can improve performance up to 0 dB to achieve the same BER. This proves the existence of saving power by 3 dB of 4x4 MIMO-OFDM system without coding, power saving 7dB of 2x2 MIMO-OFDM and significant power savings from SISO-OFDM system
Abstract: Wavelet analysis has some strong advantages over Fourier analysis, as it allows a time-frequency domain analysis, allowing optimal resolution and flexibility. As a result, they have been satisfactorily applied in almost all the fields of communication systems including OFDM which is a strong candidate for next generation of wireless technology. In this paper, the performances of wavelet based Multiuser Multiple Input and Multiple Output Orthogonal Frequency Division Multiplexing (MU-MIMO OFDM) systems are analyzed in terms of BER. It has been shown that the wavelet based systems outperform the classical FFT based systems. This analysis also unfolds an interesting result, where wavelet based OFDM system will have a constant error performance using Regularized Channel Inversion (RCI) beamforming for any number of users, and outperforms in all possible scenario in a multiuser environment. An extensive computer simulations show that a PAPR reduction of up to 6.8dB can be obtained with M=64.
Abstract: The traditional second order statistics approach of using only the hermitian covariance for non circular signals, does not take advantage of the information contained in the complementary covariance of these signals. Radar systems often use non circular signals such as Binary Phase Shift Keying (BPSK) signals. Their noncicular property can be exploited together with the dual centrosymmetry of the bistatic MIMO radar system to improve angle estimation performance. We construct an augmented matrix from the received data vectors using both the positive definite hermitian covariance matrix and the complementary covariance matrix. The Unitary ESPRIT technique is then applied to the signal subspace of the augmented covariance matrix for automatically paired Direction-of-arrival (DOA) and Direction-of-Departure (DOD) angle estimates. The number of targets that can be detected is twice that obtainable with the conventional ESPRIT approach. Simulation results show the effectiveness of this method in terms of increase in resolution and the number of targets that can be detected.
Abstract: This paper presents the design and characterization of analog readout interface circuits for ion sensitive field effect transistor (ISFET) and ion selective electrode (ISE) based sensor. These interface circuits are implemented using MIMOS’s 0.35um CMOS technology and experimentally characterized under 24-leads QFN package. The characterization evaluates the circuit’s functionality, output sensitivity and output linearity. Commercial sensors for both ISFET and ISE are employed together with glass reference electrode during testing. The test result shows that the designed interface circuits manage to readout signals produced by both sensors with measured sensitivity of ISFET and ISE sensor are 54mV/pH and 62mV/decade, respectively. The characterized output linearity for both circuits achieves above 0.999 rsquare. The readout also has demonstrated reliable operation by passing all qualifications in reliability test plan.
Abstract: This paper presents the development of a 38.5 kS/s 10-bit low power SAR ADC which is realized in MIMOS’s 0.35 µm CMOS process. The design uses a resistive DAC, a dynamic comparator with pre-amplifier and SAR digital logic to create 10 effective bits while consuming less than 7.8 mW with a 3.3 V power supply.
Abstract: Realistic systems generally are systems with various
inputs and outputs also known as Multiple Input Multiple Output
(MIMO). Such systems usually prove to be complex and difficult to
model and control purposes. Therefore, decomposition was used to
separate individual inputs and outputs. A PID is assigned to each
individual pair to regulate desired settling time. Suitable parameters
of PIDs obtained from Genetic Algorithm (GA), using Mean of
Squared Error (MSE) objective function.
Abstract: Multiple-input multiple-output (MIMO) systems are
widely in use to improve quality, reliability of wireless transmission
and increase the spectral efficiency. However in MIMO systems,
multiple copies of data are received after experiencing various
channel effects. The limitations on account of complexity due to
number of antennas in case of conventional decoding techniques have
been looked into. Accordingly we propose a modified sphere decoder
(MSD-1) algorithm with lower complexity and give rise to system
with high spectral efficiency. With the aim to increase signal
diversity we apply rotated quadrature amplitude modulation (QAM)
constellation in multi dimensional space. Finally, we propose a new
architecture involving space time trellis code (STTC) concatenated
with space time block code (STBC) using MSD-1 at the receiver for
improving system performance. The system gains have been verified
with channel state information (CSI) errors.
Abstract: In this paper, an adaptive polarized Multiple-Input
Multiple-Output (MIMO) Multicarrier Spread Spectrum Code Division Multiple Access (MC-SS-CDMA) system is designed for downlink mobile communications. The proposed system will be
examined in Frequency Division Duplex (FDD) mode for both macro urban and suburban environments. For the same transmission
bandwidth, a performance comparison between both nonoverlapped and orthogonal Frequency Division Multiplexing (FDM) schemes will be presented. Also, the proposed system will be compared with
both the closed loop vertical MIMO MC-SS-CDMA system and the
synchronous vertical STBC-MIMO MC-SS-CDMA system. As will
be shown, the proposed system introduces a significant performance
gain as well as reducing the spatial dimensions of the MIMO system
and simplifying the receiver implementation. The effect of the
polarization diversity characteristics on the BER performance will be
discussed. Also, the impact of excluding the cross-polarization MCSS-
CDMA blocks in the base station will be investigated. In addition,
the system performance will be evaluated under different Feedback
Information (FBI) rates for slowly-varying channels. Finally, a
performance comparison for vehicular and pedestrian environments
will be presented
Abstract: In this work, we study the problem of determining
the minimum scheduling length that can satisfy end-to-end (ETE)
traffic demand in scheduling-based multihop WSNs with cooperative
multiple-input multiple-output (MIMO) transmission scheme. Specifically,
we present a cross-layer formulation for the joint routing,
scheduling and stream control problem by incorporating various
power and rate adaptation schemes, and taking into account an
antenna beam pattern model and the signal-to-interference-and-noise
(SINR) constraint at the receiver. In the context, we also propose
column generation (CG) solutions to get rid of the complexity
requiring the enumeration of all possible sets of scheduling links.
Abstract: This paper features the modeling and design of a
Robust Decentralized Fast Output Sampling (RDFOS) Feedback
control technique for the active vibration control of a smart flexible
multimodel Euler-Bernoulli cantilever beams for a multivariable
(MIMO) case by retaining the first 6 vibratory modes. The beam
structure is modeled in state space form using the concept of
piezoelectric theory, the Euler-Bernoulli beam theory and the Finite
Element Method (FEM) technique by dividing the beam into 4 finite
elements and placing the piezoelectric sensor / actuator at two finite
element locations (positions 2 and 4) as collocated pairs, i.e., as
surface mounted sensor / actuator, thus giving rise to a multivariable
model of the smart structure plant with two inputs and two outputs.
Five such multivariable models are obtained by varying the
dimensions (aspect ratios) of the aluminium beam. Using model
order reduction technique, the reduced order model of the higher
order system is obtained based on dominant Eigen value retention
and the Davison technique. RDFOS feedback controllers are
designed for the above 5 multivariable-multimodel plant. The closed
loop responses with the RDFOS feedback gain and the magnitudes of
the control input are obtained and the performance of the proposed
multimodel smart structure system is evaluated for vibration control.
Abstract: It is well known that the channel capacity of Multiple-
Input-Multiple-Output (MIMO) system increases as the number of
antenna pairs between transmitter and receiver increases but it suffers
from multiple expensive RF chains. To reduce the cost of RF chains,
Antenna Selection (AS) method can offer a good tradeoff between
expense and performance. In a transmitting AS system, Channel
State Information (CSI) feedback is necessarily required to choose
the best subset of antennas in which the effects of delays and errors
occurred in feedback channels are the most dominant factors
degrading the performance of the AS method. This paper presents the
concept of AS method using CSI from channel reciprocity instead of
feedback method. Reciprocity technique can easily archive CSI by
utilizing a reverse channel where the forward and reverse channels
are symmetrically considered in time, frequency and location. In this
work, the capacity performance of MIMO system when using AS
method at transmitter with reciprocity channels is investigated by
own developing Testbed. The obtained results show that reciprocity
technique offers capacity close to a system with a perfect CSI and
gains a higher capacity than a system without AS method from 0.9 to
2.2 bps/Hz at SNR 10 dB.