scholarly journals Joint parameter estimation of multiuser asynchronous DS CDMA signals in unknown fading channel in DS CDMA system with multiple antennas at the base-station and single antenna at the mobile

2003 ◽  
Vol 16 (3) ◽  
pp. 327-341
Author(s):  
Milojko Eric ◽  
Miroslav Dukic ◽  
Milorad Obradovic
Keyword(s):  
Parameter Estimation ◽  
Fading Channel ◽  
Antenna System ◽  
Base Station ◽  
Joint Estimation ◽  
Cdma System ◽  
Multiple Antenna ◽  
Single Antenna ◽  
Direction Of Departure ◽  
Mobile Receiver

We present MUSIC type algorithm for joint parameter estimation in asynchronous DS CDMA system with multiple antenna system at base station and single antenna system at the mobile users. The proposed algorithm is applied in downlink processing and it enables the joint estimation of time delay frequency shift as well as spatial parameters (direction of departure - DOD of transmitted signal) of asynchronous DS CDMA signals using single antenna system at the mobile. The proposed algorithm is well suited to unknown fading channel, frequency selective or dispersive, and it can be primarily used as a method of multipath channel identification. It seems to the authors that it can be used as a basis for the further improvement of process of detection at the mobile receiver. The proposed algorithm is near-far resistant, requires no preamble, and can be applied when the user sequences are not perfectly orthogonal.

Space-Time Modulated Codes for MIMO Channels with Memory

2009 ◽  
pp. 130-155
Author(s):  
Xiang-Gen Xia ◽  
Genyuan Wang ◽  
Pingyi Fan
Keyword(s):  
Antenna System ◽  
Space Time ◽  
Decision Feedback ◽  
Error Correction Codes ◽  
Multiple Antenna ◽  
Mimo Channels ◽  
Single Antenna ◽  
Multiple Transmit ◽  
Coded Systems ◽  
Antenna Systems

Modulated codes (MC) are error correction codes (ECC) defined on the complex field and therefore can be naturally combined with an intersymbol interference (ISI) channel. It has been previously proved that for any finite tap ISI channel there exist MC with coding gain comparing to the uncoded AWGN channel. In this chapter, we first consider space-time MC for memory channels, such as multiple transmit and receive antenna systems with ISI. Similar to MC for single antenna systems, the space-time MC can be also naturally combined with a multiple antenna system with ISI, which provides the convenience of the study. Some lower bounds on the capacities C and the information rates Ii.i.d of the MC coded systems are presented. We also introduce an MC coded zero-forcing decision feedback equalizer (ZF-DFE) where the channel is assumed known at both the transmitter and the receiver. The optimal MC design based on the ZF-DFE are presented.

scholarly journals PERFORMANCE ANALYSIS OF MIMO TECHNOLOGY USING VBLAST MAXIMUM A POSTERIORI (MAP)

2015 ◽  
pp. 285-288
Author(s):  
JOYA JUBAIR J ◽  
P J DEORE ◽  
B P PATIL
Keyword(s):  
Mimo System ◽  
Antenna System ◽  
Maximum A Posteriori ◽  
Multiple Antenna ◽  
A Posteriori ◽  
Detection Scheme ◽  
Single Antenna ◽  
Data Rates ◽  
Symbol Detection ◽  
Mimo Technology

Recent research shows that multiple antenna at both transmitter and receiver offers higher data rates compared to single antenna system. The information-theoretical capacity of MIMO grows linearly with the smaller of transmit and receive antenna in rich scattering environment with sufficient high SNR. In this paper, V-BLAST and maximum a-posteriori (MAP) is used improve the performance of the MIMO system. The original V-BLAST algorithm is a multi-layer symbol detection scheme, which detects symbols transmitted at different transmit antennas successively in a certain dataindependent order. The proposed V-BLAST-MAP algorithm differs from V-BLAST only in the ordering strategy of the symbols detected. The complexity of the V-BLAST-MAP is higher than that of V-BLAST. The performance improvement is also significant. In this paper, MATLAB Based simulation result are discussed .

Study of Power Control in CDMA System on the basis of optimization Technique

2017 ◽  
Vol 7 (8) ◽  
pp. 126
Author(s):  
. Geetanjli
Keyword(s):  
Power Control ◽  
Multiple Access ◽  
Optimization Technique ◽  
System Optimization ◽  
Base Station ◽  
Particle Swarm Algorithm ◽  
Cdma System ◽  
Frequency Division ◽  
Cdma Systems ◽  
Time Division

The power control in CDMA systems, grant numerous users to share resources of the system uniformly between each other, leading to expand capacity. With convenient power control, capacity of CDMA system is immense in contrast of frequency division multiple access (FDMA) and time division multiple access (TDMA). If power control is not achieved numerous problems such as the near-far effect will start to monopolize and consequently will reduce the capacity of the CDMA system. However, when the power control in CDMA systems is implemented, it allows numerous users to share resources of the system uniformly between themselves, leading to increased capacity For power control in CDMA system optimization algorithms i.e. genetic algorithm & particle swarm algorithm can be used which regulate a convenient power vector. These power vector or power levels are dogged at the base station and announce to mobile units to alter their transmitting power in accordance to these levels. The performances of the algorithms are inspected through both analysis and computer simulations, and compared with well-known algorithms from the literature.

scholarly journals Implementation of a Zero-Forcing Precoding Algorithm Combined with Adaptive Beamforming Based on WiMAX System

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Hyunwook Yang ◽  
Seungwon Choi
Keyword(s):  
Mimo System ◽  
Multiple Input Multiple Output ◽  
Experimental System ◽  
Multiple Access Interference ◽  
Adaptive Beamforming ◽  
Base Station ◽  
Zero Forcing ◽  
Single Antenna ◽  
Input Multiple Output ◽  
Wimax System

We propose a novel precoding algorithm that is a zero-forcing (ZF) method combined with adaptive beamforming in the Worldwide Interoperability for Microwave Access (WiMAX) system. In a Multiuser Multiple-Input Multiple-Output (MU-MIMO) system, ZF is used to eliminate the Multiple Access Interference (MAI) in order to allow several users to share a common resource. The adaptive beamforming algorithm is used to achieve the desired SNR gain. The experimental system consists of a WiMAX base station that has 2 MIMO elements, each of which is composed of three-array antennas and two mobile terminals, each of which has a single antenna. Through computer simulations, we verified that the proposed method outperforms the conventional ZF method by at least 2.4 dB when the BER is 0.1%, or 1.7 dB when the FER is 1%, in terms of the SNR. Through a hardware implementation of the proposed method, we verified the feasibility of the proposed method for realizing a practical WiMAX base station to utilize the channel resources as efficiently as possible.

MGF-Based Effective Capacity for Generalized Fading Channels

2014 ◽  
Vol 519-520 ◽  
pp. 929-933 ◽  
Author(s):  
Zhe Ji ◽  
You Zheng Wang ◽  
Jian Hua Lu
Keyword(s):  
Closed Form ◽  
Fading Channels ◽  
Mathematical Expression ◽  
Moment Generating Function ◽  
Effective Capacity ◽  
Multiple Antenna ◽  
Method Of Moment ◽  
Single Antenna ◽  
Generalized Fading Channels

In this paper, we study the effective capacity (EC) which was proposed to measure the quality of service (QoS) for fading channels. A unified expression for the effective capacity based on the method of moment generating function (MGF) is proposed. The unified expression applies to various fading channels and is derived for both single antenna and multiple antenna diversity system. The mathematical expression is illustrated with Nakagami-m fading channels and closed form expressions are derived in this case. The simulation results verify the consistence of the closed-form expressions with numerical evaluations.

scholarly journals Automotive antenna diversity system for satellite radio with high phase accuracy in low SNR-scenarios

2018 ◽  
Vol 10 (5-6) ◽  
pp. 578-586 ◽  
Author(s):  
Simon Senega ◽  
Ali Nassar ◽  
Stefan Lindenmeier
Keyword(s):  
Signal To Noise Ratio ◽  
A Priori ◽  
Multipath Fading ◽  
Correction Method ◽  
Antenna System ◽  
Antenna Diversity ◽  
Phase Detection ◽  
Low Snr ◽  
Single Antenna ◽  
Noise Correction

AbstractFor a fast scan-phase satellite radio antenna diversity system a noise correction method is presented for a significant improvement of audio availability at low signal-to-noise ratio (SNR) conditions. An error analysis of the level and phase detection within the diversity system in the presence of noise leads to a correction method based on a priori knowledge of the system's noise floor. This method is described and applied in a hardware example of a satellite digital audio radio services antenna diversity circuit for fast fading conditions. Test drives, which have been performed in real fading scenarios, are described and results are analyzed statistically. Simulations of the scan-phase antenna diversity system show higher signal amplitudes and availabilities. Measurement results of dislocated antennas as well as of a diversity antenna set on a single mounting position are presented. A comparison of a diversity system with noise correction, the same system without noise correction, and a single antenna system with each other is performed. Using this new method in fast multipath fading driving scenarios underneath dense foliage with a low SNR of the antenna signals, a reduction in audio mute time by one order of magnitude compared with single antenna systems is achieved with the diversity system.

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