Diversity Gain Analysis of a Novel Dual-Frequency Multiple Access Relay Transmission Scheme

2007 ◽  
Author(s):  
Babak H. Khalaj ◽  
Javier del Ser ◽  
Pedro M. Crespo ◽  
Jesus Gutierrez-Gutierrez
Keyword(s):  
Multiple Access ◽  
Diversity Gain ◽  
Dual Frequency ◽  
Transmission Scheme

scholarly journals Non-Orthogonal Multiple Access in Multiuser MIMO Configurations via Code Reuse and Principal Component Analysis

Electronics ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 1330
Author(s):  
Panagiotis K. Gkonis ◽  
Panagiotis T. Trakadas ◽  
Lambros E. Sarakis
Keyword(s):  
Principal Component Analysis ◽  
Interference Cancellation ◽  
Correlation Matrix ◽  
Multiple Access ◽  
Multiple Input Multiple Output ◽  
Principal Component ◽  
Component Analysis ◽  
Inner Product ◽  
Transmission Scheme ◽  
Code Reuse

The goal of the study presented in this paper is to evaluate the performance of a proposed transmission scheme in multiuser multiple-input multiple-output (MIMO) configurations, via code reuse. Hence, non-orthogonal multiple access (NOMA) is performed. To this end, a correlation matrix of the received data is constructed at the transmitter, with feedback as only the primary eigenvector of the equivalent channel matrix, which is derived after principal component analysis (PCA) at the receiver. Afterwards, users experiencing improved channel quality (i.e., diagonal terms of the correlation matrix) along with reduced multiple access interference (i.e., the inner product of transmission vectors) are the potential candidates for their assigned code to be reused. As the results indicate, considering various MIMO configurations, the proposed approach can achieve almost 33% code assignment gain (CAG), when successive interference cancellation (SIC) is employed in mobile receivers. However, even in the absence of SIC, CAG is still maintained with a tolerable average bit error rate (BER) degradation.

scholarly journals Rate-Splitting Multiple Access in Cache-Aided Cloud-Radio Access Networks

2021 ◽  
Vol 2 ◽  
Author(s):  
Robert-Jeron Reifert ◽  
Alaa Alameer Ahmad ◽  
Yijie Mao ◽  
Aydin Sezgin ◽  
Bruno Clerckx
Keyword(s):  
Multiple Access ◽  
Access Networks ◽  
Mixed Integer ◽  
Transmission Scheme ◽  
Common Part ◽  
Multicast Transmission ◽  
Cloud Radio Access Networks ◽  
Radio Access Networks ◽  
Radio Access ◽  
Rate Splitting

Rate-splitting multiple access (RSMA) has been recognized as a promising physical layer strategy for 6G. Motivated by the ever-increasing popularity of cache-enabled content delivery in wireless communications, this paper proposes an innovative multigroup multicast transmission scheme based on RSMA for cache-aided cloud-radio access networks (C-RAN). Our proposed scheme not only exploits the properties of content-centric communications and local caching at the base stations (BSs) but also incorporates RSMA to better manage interference in multigroup multicast transmission with statistical channel state information (CSI) known at the central processor (CP) and the BSs. At the RSMA-enabled cloud CP, the message of each multicast group is split into a private and a common part with the former private part being decoded by all users in the respective group and the latter common part being decoded by multiple users from other multicast groups. Common message decoding is done for the purpose of mitigating the interference. In this work, we jointly optimize the clustering of BSs and the precoding with the aim of maximizing the minimum rate among all multicast groups to guarantee fairness serving all groups. The problem is a mixed-integer nonlinear stochastic program (MINLSP), which is solved by a practical algorithm we propose including a heuristic clustering algorithm for assigning a set of BSs to serve each user followed by an efficient iterative algorithm that combines the sample average approximation (SAA) and weighted minimum mean square error (WMMSE) to solve the stochastic non-convex subproblem of precoder design. Numerical results show the explicit max-min rate gain of our proposed transmission scheme compared to the state-of-the-art trivial interference processing methods. Therefore, we conclude that RSMA is a promising technique for cache-aided C-RAN.

scholarly journals Sensitivity Enhancement System for Pulse Compression Weather Radar

2014 ◽  
Vol 31 (12) ◽  
pp. 2732-2748 ◽  
Author(s):  
Cuong M. Nguyen ◽  
V. Chandrasekar
Keyword(s):  
Pulse Compression ◽  
Doppler Radar ◽  
Matched Filter ◽  
Simulated Data ◽  
Weather Radar ◽  
Sensitivity Enhancement ◽  
Dual Frequency ◽  
Transmission Scheme ◽  
Compression Technique ◽  
System Sensitivity

Abstract The use of low-power solid-state transmitters in weather radar to keep costs down requires a pulse compression technique that maintains an adequate minimum detectable signal. However, wideband pulse compression filters will partly reduce the system’s sensitivity performance. In this paper, a sensitivity enhancement system (SES) for pulse compression weather radar is developed to mitigate this issue. SES uses a dual-waveform transmission scheme and an adaptive pulse compression filter. The waveforms’ diversity can be done in the frequency domain or the time domain. The adaptive filter is designed based on the self-consistency between signal returns from the two waveforms. Analysis based on radar-simulated data and observations from NASA’s dual-frequency dual-polarized Doppler radar (D3R) shows that by using SES, the system sensitivity can be improved by 7–10 dB when compared to that of the conventional matched filter.

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