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۱The Effect of Channel State Information on the Capacity Bounds of MIMO Relay Channel
نویسنده(ها): ،
اطلاعات انتشار: بیستمین کنفرانس مهندسی برق ایران، سال
تعداد صفحات: ۴
In this paper, we compare the capacity bounds of fullduplex MIMO relay channel, by considering two cases for channel state information (CSI). In the first case, we assumethat the CSI is available at all nodes; in the second case, we consider that the CSI is only available at the receivers and thereis no information about the channel gains at the transmitters. Numerical results show that under certain constraint on the relay position with respect to the source and the destination, theavailability of CSI at the transmitters does not affect the capacity bounds. Thus, this simple result can be considered as apractical approach for constrained implementation of relaybased wireless networks<\div>

۲A Novel DS–CDMA Direction of Arrival Estimator for Frequency– Selective Fading Channel with Correlated Multipath by Using Beamforming Filter
اطلاعات انتشار: International Journal Information and Communication Technology Research، سوم،شماره۳، Jun ۲۰۱۱، سال
تعداد صفحات: ۱۴
In this paper, a new method for estimating the direction of arrival of Asynchronous DS–CDMA signals in multipath fading channel is proposed. In the proposed method, first, for removing the effects of undesired paths, we project the coherent signals of the undesired paths perpendicularly to the under process signal, next, the signal is passed through a filter bank.Byusing beam forming filters, the effectof other users on the desired users signal is decreased and hence, the search area is decreased almost to one tenth. In this algorithm, searching all angles is not required,to estimate the number of sources does not require any information criteria, andalso, the number of users can exceed the number of antenna arrays contrary to many of the conventional methods. Simulation results are illustrated to confirm the efficiency of the method.

۳Capacity Region of the Compound Multiple Access Channels with Common Message and in the Presence of Intersymbol Interference
اطلاعات انتشار: International Journal Information and Communication Technology Research، ششم،شماره۲، Spring ۲۰۱۴ ، سال
تعداد صفحات: ۱۰
The capacity region of a two–user linear Gaussian compound Multiple Access Channel with common message (CMACC) and intersymbol interference (ISI) under an input power constraint is derived. To obtain the capacity region we first convert the channel to its equivalent memoryless one by defining an n–block memoryless circular Gaussian CMACC model. We then make use of the discrete Fourier transform (DFT) to decompose the n–block circular Gaussian CMACC into a set of independent parallel channels whose individual capacities can be found easily. Finally we derive the capacity of this n–block memoryless circular Gaussian CMACC (n–CGCMACC) based on the DFT decomposition. Since our channel is a special case of a synchronous multi–terminal channel, the capacity region of the Gaussian CMACC with ISI is the same as the capacity region of the n–CGCMACC in the limit of infinite block length. We also investigate the capacity regions for some special cases of the Gaussian CMACC with ISI using the obtained capacity region, and finally, provide some numerical results to show the loss in the rate caused by ISI.

۴A New Upper Bound for Free Space Optical Channel Capacity Using a Simple Mathematical in Equality
نویسنده(ها): ،
اطلاعات انتشار: Journal of Information Systems and Telecommunication، اول،شماره۱، Jan – Mar ۲۰۱۳، سال
تعداد صفحات: ۸
In this paper, by using a simple mathematical inequality, we derive a$ new upper bound fkr the capacity of$ free space optical channel in coherent case. Then, by applying general fading distribution, we obtain an upper bound for mutual information in non–coherent case. Finally, we derive the corresponding optimal input distributions for both coherent and non–coherent cases, compare the results with previous works numerically and illustrate that our results subsume some of previous results in special cases.
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