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\def\makelabel##1{\upshape ##1}}% } {\end{list}\end{raggedright}} \newenvironment{specHead}[2]% {\vspace{20pt}\hrule\vspace{10pt}% \phantomsection\label{#1}\markright{#2}% \pdfbookmark[2]{#2}{#1}% \hspace{-0.75in}{\bfseries\fontsize{16pt}{18pt}\selectfont#2}% }{} \def\TheFullDate{2013-01-15 (revised: 15 January 2013)} \def\TheID{\makeatother } \def\TheDate{2013-01-15} \title{Proportional air Multiusers Selective and Switched Channel Scheduling Schemes} \author{}\makeatletter \makeatletter \newcommand*{\cleartoleftpage}{% \clearpage \if@twoside \ifodd\c@page \hbox{}\newpage \if@twocolumn \hbox{}\newpage \fi \fi \fi } \makeatother \makeatletter \thispagestyle{empty} \markright{\@title}\markboth{\@title}{\@author} \renewcommand\small{\@setfontsize\small{9pt}{11pt}\abovedisplayskip 8.5\p@ plus3\p@ minus4\p@ \belowdisplayskip \abovedisplayskip \abovedisplayshortskip \z@ plus2\p@ \belowdisplayshortskip 4\p@ plus2\p@ minus2\p@ \def\@listi{\leftmargin\leftmargini \topsep 2\p@ plus1\p@ minus1\p@ \parsep 2\p@ plus\p@ minus\p@ \itemsep 1pt} } \makeatother \fvset{frame=single,numberblanklines=false,xleftmargin=5mm,xrightmargin=5mm} \fancyhf{} \setlength{\headheight}{14pt} \fancyhead[LE]{\bfseries\leftmark} \fancyhead[RO]{\bfseries\rightmark} \fancyfoot[RO]{} \fancyfoot[CO]{\thepage} \fancyfoot[LO]{\TheID} \fancyfoot[LE]{} \fancyfoot[CE]{\thepage} \fancyfoot[RE]{\TheID} \hypersetup{citebordercolor=0.75 0.75 0.75,linkbordercolor=0.75 0.75 0.75,urlbordercolor=0.75 0.75 0.75,bookmarksnumbered=true} \fancypagestyle{plain}{\fancyhead{}\renewcommand{\headrulewidth}{0pt}} \date{} \usepackage{authblk} \providecommand{\keywords}[1] { \footnotesize \textbf{\textit{Index terms---}} #1 } \usepackage{graphicx,xcolor} \definecolor{GJBlue}{HTML}{273B81} \definecolor{GJLightBlue}{HTML}{0A9DD9} \definecolor{GJMediumGrey}{HTML}{6D6E70} \definecolor{GJLightGrey}{HTML}{929497} \renewenvironment{abstract}{% \setlength{\parindent}{0pt}\raggedright \textcolor{GJMediumGrey}{\rule{\textwidth}{2pt}} \vskip16pt \textcolor{GJBlue}{\large\bfseries\abstractname\space} }{% \vskip8pt \textcolor{GJMediumGrey}{\rule{\textwidth}{2pt}} \vskip16pt } \usepackage[absolute,overlay]{textpos} \makeatother \usepackage{lineno} \linenumbers \begin{document} \author[1]{Rupinder Kaur} \author[2]{Muhammad Ejaz Aslam Lodhi} \affil[1]{ IGIT NEW DELHI, India.} \renewcommand\Authands{ and } \date{\small \em Received: 7 December 2012 Accepted: 31 December 2012 Published: 15 January 2013} \maketitle \begin{abstract} Presents increasing demand of rates in any digital communication system that excites the research idea of scheduling channel access methodology so as to results in maximizing the sum rate. The reduction in feedback messages for channel state information provides great savings in channel bandwidth for multiuser switched diversity scheduling systems. The present proposed work demonstrates that maximization of sum capacity can be achieved using optimization of per user threshold rate along with some prior estimation of channel state information.The results shown in higher achievable rate. Furthermore the proposed novel multiuser switched diversity MUSD system also achieves proportional fairness criteria along with decentralization of optimization threshold channel. \end{abstract} \keywords{multiuser diversity; per user threshold; proportional fairness scheduling.} \begin{textblock*}{18cm}(1cm,1cm) % {block width} (coords) \textcolor{GJBlue}{\LARGE Global Journals \LaTeX\ JournalKaleidoscope\texttrademark} \end{textblock*} \begin{textblock*}{18cm}(1.4cm,1.5cm) % {block width} (coords) \textcolor{GJBlue}{\footnotesize \\ Artificial Intelligence formulated this projection for compatibility purposes from the original article published at Global Journals. However, this technology is currently in beta. \emph{Therefore, kindly ignore odd layouts, missed formulae, text, tables, or figures.}} \end{textblock*} \let\tabcellsep& \section[{Introduction}]{Introduction}\par ne of the features of multiuser communication on fading channels is multiuser diversity \hyperref[b0]{[1]}. By exploiting the fading conditions independently, the multiuser diversity gain can be obtained and scheduling only the users with good channels \hyperref[b1]{[2]}. To maximize the capacity of information of the uplink in single-cell multiuser communications with frequency-flat fading at any given time, only one user is allowed to transmit with the best channel condition.\par Transmitting over the best channel maximizes the system sum-throughput, but results in "Unfair" allocation of the wireless resources among the users. Proportional fair scheduler (PF) which has been studied in this paper provides a good compromise between multiuser diversity gains and fairness \hyperref[b2]{[3]}. The main goal of this research work or project work is to develop a noble architecture or design of Multiuser switched diversity scheduling scheme that can accomplish the following objectives: a) Obtain the fairness in Scheduling scheme Design a system in which a single radio or air link resource can be used for Multi user communication scenario. In spite of conventional selection based scheduling here in this research work, a switching based scheduling scheme has to be obtained that may perform better than the existing systems. \section[{b) Comparison}]{b) Comparison}\par A comparison of MUSD schemes with fullfeedback multiuser selective diversity opportunistic scheduling schemes is needed to evaluate how much rate we lose due to the feedback savings.\par Multiuser switched diversity is to find user with good channel condition instead of best user among all suggested in \hyperref[b6]{[7]}.so channel condition if acceptable or not will be determined by considering predefined threshold .per user channel state threshold will be used in this paper \hyperref[b7]{[8]}. All the users are assigned with time slotted channel .each time slot channel will send one bit flag signal if its achievable rate is more than threshold \hyperref[b8]{[9]} .so feedback in MUSD will be reduced by assigning this threshold and assigning time slotted channel to users instead of per user feedback channel. This method also removes the congestion by using ordered scheduling. \section[{II.}]{II.} \section[{Review of Multiuser Selection Diversity}]{Review of Multiuser Selection Diversity}\par R Knopp and Humblet in \hyperref[b1]{[2]} explained the power control mechanism at transmitter in which capacity is increased by transmitting one user at one time over the entire bandwidth having Best channel quality. Received power is estimated at base section to control the transmit power to obtain high capacity. D. Tse in \hyperref[b9]{[10]} provide solution to multi path fading and losses by dynamically allocation to resources to users based on condition of channel quality of users. So when With existing full feedback multiuser diversity scheduling system In all wireless communication system, transmitter send pilot signal to all the receivers to measure the condition of channel mention in \hyperref[b3]{[4]}.in opportunistic system, mobile user continuously send the feedback information to base station which causes wastage of air link resources and mobile battery power.so there is need to reduce the feedback load by different methods \hyperref[b4]{[5]}and \hyperref[b5]{[6]}. Different methods that can be employed are lossy and lossless compression ,scalar quantization method, Schemes exploiting the fact that only the best user will be allowed to transmit (max-SNR scheduling), and consequently that feedback the reception at base station is week user as allocated with more power. T Ericksson and Tony Ottoson in \hyperref[b4]{[5]} states that sum capacity can be increased by feedback reduction methods. Feedback can be minimized without losing gain by different methods. First: Quantization, in which SNR is quantized before transmission. Second: Max SNR, in which users with only high SNR send feedback. Users with low SNR is unnecessary. Third: Data Compression, In this lossy and lossless compression techniques are used. Lossy compression techniques are transform coding and linear prediction coding etc. lossless compression techniques are arithmetic coding and 54Lempel ziv etc. M. S Alouni in \hyperref[b10]{[11]} explained that user transmit information only when its channel quality exceed threshold. if channel quality of number of users exceed threshold then random user is selected. But the problem occur when multiple users reply to same threshold then chances of collision occur. So Aim of this paper is to provide solution of various challenges occur in MUSD system. These challenges are; user with strong channel may not get access to the channel, so need is to obtain the fairness by scheduling the users with best channel conditions first rather than others; optimization at central scheduler is not easy because it needs knowledge of pdf of all the users \hyperref[b11]{[12]}; comparison of multiuser switched diversity with full feedback is required to calculate how much rate is lost. We propose proportional fairness scheme in multiuser switched diversity scheduling by using per-user threshold optimization with the principal function of maximizing the sum of the logarithms of the achievable rates. For each user, independent equations are used that provide solution to optimization. \section[{III.}]{III.} \section[{System Model}]{System Model}\par Consider if there is no delay in the decision of scheduling and block fading channel are used as medium between base station and users. Time slotted channel is used in orthogonal access scheme manner \hyperref[b12]{[13]}. Each user is allocated with slotted channel include guard band and data burst .guard band is used to send flag signal to base station if its channel quality is higher than feedback threshold. Scheduling is done on following conditions if its channel quality is better than threshold Value \hyperref[b13]{[14]}. Users prior to given one has achievable Rate less than threshold value. Consider if r i * is the threshold value of user i where achievable rate of user I is r i . User i is scheduled only if r i *j, i=j, i