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wireless-telecommunication-systems
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An optimal transmission policy for energy harvesting systems with continuous curves
, Article 12th International Symposium on Wireless Communication Systems, 25 August 2015 through 28 August 2015 ; Volume 2016-April , 2015 , Pages 411-415 ; 21540217 (ISSN) ; 9781467365406 (ISBN) ; Kaboli, R ; Mirmohseni, M ; Aref, M. R ; Sharif University of Technology
VDE Verlag GmbH
Abstract
Energy harvesting has been developed as an effective technology for communication systems in order to extend the lifetime of these systems. In this work, we consider a single-user energy harvesting wireless communication system, in which both of the arrival data and the harvested energy curves are modeled as continuous functions. Our goal is to find an offline algorithm, which maximizes the amount of data which is transmitted to the receiver node by a given deadline. If more than one scheme exist that transmit the maximum data, we choose the one with minimum utilized energy at the transmitter node
Distributed recovery units for demodulation in wireless sensor networks
, Article First IEEE International Conference on Distributed Computing in Sensor Systems, DCOSS 2005, Marina del Rey, CA, 30 June 2005 through 1 July 2005 ; Volume 3560 , 2005 , Pages 417-419 ; 03029743 (ISSN) ; Sedghi, V ; Sharif University of Technology
Springer Verlag
2005
Abstract
In this paper, the distributed recovery units for FM and PPM demodulation in wireless sensor networks is proposed and is showed that, the method introduces very little amount of distortion to recovered signal. With simulations, we have examined several different parameters. Besides, two different filtering schemes are simulated. Effect of iteration coefficient (X) on stability and convergence rate is investigated for different sampling and filtering methods. Next, we have studied the noise effect in demodulation with this method. Simulations results are included to verify convergence. © Springer-Verlag Berlin Heidelberg 2005
Cell selection for load balancing in heterogeneous networks
, Article Wireless Personal Communications ; Volume 101, Issue 1 , 2018 , Pages 305-323 ; 09296212 (ISSN) ; Kalbkhani, H ; Shayesteh, M. G ; Solouk, V ; Sharif University of Technology
Springer New York LLC
2018
Abstract
The vision of advanced long-term evolution (LTE-A) project is set to ultimate increase of network capacity in heterogeneous networks (HetNets). In HetNets with small cell configuration, a considerable majority of user devices is eventually connected to the macrocell base station (MBS), while small base stations (BSs), such as femtocell access points (FAPs), are still without any user. This results in unbalanced load and reduces the data rate of macrocell user equipment (MUE). In this paper, a method is proposed for load balancing among FAPs, while desired throughput is achieved. The proposed method uses the estimated received signal strength from different BSs and adjusted pilot signals....
Optimum low complexity filter bank for generalized orthogonal frequency division multiplexing
, Article Eurasip Journal on Wireless Communications and Networking ; Volume 2018, Issue 1 , 2018 ; 16871472 (ISSN) ; Khalaj, B. H ; Haghbin, A ; Sharif University of Technology
Springer International Publishing
2018
Abstract
Generalized frequency division multiplexing (GFDM) is one of the multicarrier modulation candidates proposed for the 5th generation of wireless networks. Among GFDM linear receivers, GFDM MMSE receiver achieves the best error performance for multipath fading channels at the cost of high numerical complexity. Hence, the combination of GFDM match filter (MF) receiver and double-side successive interference cancellation (DSIC) method is used instead. However, there is a significant gap between the error performance of GFDM MMSE and DSIC/MF receivers for the case of employing modern channel coding. Recently, we have proposed a new multicarrier scheme based on GFDM architecture called generalized...
Impact of jitter mechanisms on metric-based wireless routing protocols
, Article 2016 IEEE International Conference on Wireless Communications, Signal Processing and Networking, 23 March 2016 through 25 March 2016 ; 2016 , Pages 574-578 ; 9781467393379 (ISBN) ; Hemmatyar, A. M. A ; Cognizant; DRDO; et al.; IEEE; ISRO; SSN ; Sharif University of Technology
Presses Polytechniques Et Universitaires Romandes
Abstract
In many wireless communication protocols, small and random delay, called jitter, is imposed before packet transmission so as to reduce packet collisions. Jitter is recommended for many routing protocols such as AODV and LOADng. Jitter can be exploited to change the order of routes about which destination is informed and, as a result, make better routes, regarding their metric, more likely to choose by the destination. However, to the best of our knowledge, there is only one mechanism, called adaptive jitter mechanism, proposed for metric-based routing protocols. In this paper, we aim to show feasibility of using different random variables for jittering and define some shaping functions to...
Smart antennas for OFDM-WLANs based on a spatial-temporal multi-scenario channel model
, Article Iranian Journal of Electrical and Computer Engineering ; Volume 7, Issue 2 , 2008 , Pages 107-114 ; 16820053 (ISSN) ; Dadashzadeh, G ; Shishegar, A. A ; Hojjat, N ; Sharif University of Technology
Jahad Daneshgahi
2008
Abstract
combination of smart antenna techniques and OFDM could be considered as a promising solution for improving the performance and enhancing the data rates of next generation wireless communication systems operating in frequency selective fading environments. There are different design parameters which could affect the application of adaptive arrays in OFDM-based systems. Various beam-forming methods in frequency or time domain, different array architectures and various number of array elements are important factors which are able to change the performance and complexity of the system. These parameters may show different effects in different channel conditions. In this paper we implemented a new...
Diversity-multiplexing tradeoff in MIMO radars
, Article IET Radar, Sonar and Navigation ; Volume 11, Issue 4 , 2017 , Pages 691-700 ; 17518784 (ISSN) ; Radmard, M ; Chitgarha, M. M ; Farina, A ; Nayebi, M. M ; Bastani, M. H ; Sharif University of Technology
Institution of Engineering and Technology
2017
Abstract
Two gains play key roles in recently developed multiple-input-multiple-output (MIMO) wireless communication systems: 'spatial diversity' gain and 'spatial multiplexing' gain. The diversity gain (DG) refers to the capability to decrease the error rate of the MIMO channel, whereas the multiplexing gain (MG) implicitly refers to the amount of increase in the capacity of the MIMO channel. It has been shown that there is a fundamental tradeoff between these two types of gains, meaning interplay between increasing reliability (via an increase in the DG) and increasing data rate (via an increase in the MG). On the other hand, recently, MIMO radars have attracted much attention for their superior...
Design and Implementation of Time and Frequency Synchronization in LTE
, Article IEEE Transactions on Very Large Scale Integration (VLSI) Systems ; Volume 23, Issue 12 , January , 2015 , Pages 2970-2982 ; 10638210 (ISSN) ; Shabany, M ; Nezamalhosseini, A ; Gulak, G ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2015
Abstract
A novel architecture for efficient time and frequency synchronization, applied to the long-term evolution (LTE) standard, is proposed. For symbol timing, we propose applying a symbol-folding method on top of the sign-bit reduction technique, leading to a novel algorithm for the cyclic prefix-type recognition in LTE. Following the symbol timing, the fractional carrier frequency offset is estimated and compensated using an adaptive gain loop, which allows for a high-accuracy compensation in a short interval. In the frequency domain, for cell search, we propose a sign-bit reduction technique on top of the matched filter method for the primary synchronization signal detection. In addition, we...
On the BER of multiple-input multiple-output underwater wireless optical communication systems
, Article 2015 4th International Workshop on Optical Wireless Communications, IWOW 2015, 7 September 2015 through 10 September 2015 ; Sept , 2015 , Pages 26-30 ; 9781467377263 (ISBN) ; Salehi, J. A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2015
Abstract
In this paper we analyze and investigate the bit error rate (BER) performance of multiple-input multiple-output underwater wireless optical communication (MIMO-UWOC) systems. In addition to exact BER expressions, we also obtain an upper bound on the system BER. To effectively estimate the BER expressions, we use Gauss-Hermite quadrature formula as well as approximation to the sum of log-normal random variables. We confirm the accuracy of our analytical expressions by evaluating the BER through photon-counting approach. Our simulation results show that MIMO technique can mitigate the channel turbulence-induced fading and consequently, can partially extend the viable communication range,...
Adaptive power control algorithms in underwater wireless optical CDMA cellular networks
, Article 2015 4th International Workshop on Optical Wireless Communications, IWOW 2015, 7 September 2015 through 10 September 2015 ; September , 2015 , Pages 107-111 ; 9781467377263 (ISBN) ; Akhoundi, F ; Salehi, J. A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2015
Abstract
In this paper we introduce two adaptive power control algorithms for downlink of underwater wireless optical cellular networks. The first approach is based on the angle of user's position with respect to optical base transceiver station (OBTS) of the cell. The second scheme works according to the link distance between the user and the OBTS. Defining an optimization problem, we aim to guaranty the quality of service for each user while minimizing the transmitting power. In our methods, we utilize limited feedback channel state information (CSI) so that the algorithm could be implemented with low complexity. The simulation results for different water types demonstrate that our proposed...
A robust algorithm based on wavelet transform for recognition of binary digital modulations
, Article 2015 38th International Conference on Telecommunications and Signal Processing, TSP 2015, 9 July 2015 through 11 July 2015 ; July , 2015 , Pages 508-512 ; 9781479984985 (ISBN) ; Pezeshk, A. M ; Behnia, F ; Molnar K ; Herencsar N ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2015
Abstract
Automatic Modulation Recognition (AMR) of communication signals has been an important theme in wireless communication systems. Recently, digital modulation recognition has been considered remarkably, due to the vast application of this kind of AMR technique in spectrum sensing and cognitive radio. In this paper, we propose a wavelet-based algorithm for recognition of binary digital modulation schemes including BASK, BFSK and BPSK in presence of Additive White Gaussian Noise (AWGN). In this algorithm, Haar Wavelet Transform (HWT) of the received signal is compared to templates and the similarity of them are measured. Experimental results show a perfect classification of binary digital...
FiWi enhanced LTE-A HetNets with unreliable fiber backhaul sharing and WiFi offloading
, Article Proceedings - IEEE INFOCOM, 26 April 2015 through 1 May 2015 ; Volume 26 , 2015 , Pages 1275-1283 ; 0743166X (ISSN) ; 9781479983810 (ISBN) ; Levesque, M ; Maier, M ; Salehi, J. A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2015
Abstract
To cope with the unprecedented growth of mobile data traffic, we investigate the performance gains obtained from unifying coverage-centric 4G mobile networks and capacity-centric fiber-wireless (FiWi) broadband access networks based on data-centric Ethernet technologies with resulting fiber backhaul sharing and WiFi offloading capabilities. Despite recent progress on backhaul-aware 4G studies with capacity-limited backhaul links, the performance-limiting impact of backhaul latency and reliability has not been examined in sufficient detail previously. In this paper, we evaluate the maximum aggregate throughput, offloading efficiency, and in particular the delay performance of FiWi enhanced...
A novel area-efficient VLSI architecture for recursion computation in LTE turbo decoders
, Article IEEE Transactions on Circuits and Systems II: Express Briefs ; Volume 62, Issue 6 , 2015 , Pages 568-572 ; 15497747 (ISSN) ; Shabany, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2015
Abstract
Long-term evolution (LTE) is aimed to achieve the peak data rates in excess of 300 Mb/s for the next-generation wireless communication systems. Turbo codes, the specified channel-coding scheme in LTE, suffer from a low-decoding throughput due to its iterative decoding algorithm. One efficient approach to achieve a promising throughput is to use multiple maximum a posteriori (MAP) cores in parallel, resulting in a large area overhead. The two computationally challenging units in an MAP core are α and β recursion units. Although several methods have been proposed to shorten the critical path of these recursion units, their area-efficient architecture with minimum silicon area is still missing....
Design concepts and performance analysis of multicarrier CDMA for indoor visible light communications
, Article Journal of Optical Communications and Networking ; Volume 7, Issue 6 , 2015 , Pages 554-562 ; 19430620 (ISSN) ; Fallahpour, A ; Salehi, J. A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2015
Abstract
In this paper, we present a design methodology with implementational insight and evaluate the performance of a multicarrier code-division multiple access (MC-CDMA) system using intensity modulation/direct detection scheme suitable for an indoor visible light communication (VLC) environment. The proposed system is a CDMA system based on an orthogonal frequency division multiplexing (OFDM) platform. To overcome the light-dimming issue, we use a newly proposed methodology, namely, polarity reversed optical OFDM (PRO-OFDM). A unipolar signal is either added to the minimum current or subtracted from the maximum current in the LED linear current range to provide various amounts of dimming. The...
An efficient max-log MAP algorithm for VLSI implementation of turbo decoders
, Article Proceedings - IEEE International Symposium on Circuits and Systems, 24 May 2015 through 27 May 2015 ; Volume 2015-July , 2015 , Pages 1794-1797 ; 02714310 (ISSN) ; 9781479983919 (ISBN) ; Shabany, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2015
Abstract
Long term evolution (LTE)-advanced aims the peak data rates in excess of 3 Gbps for the next generation wireless communication systems. Turbo codes, the specified channel coding scheme in LTE, suffers from a low-decoding throughput due to its iterative decoding algorithm. One efficient approach to achieve a promising throughput is to use multiple Maximum a Posteriori (MAP) cores in parallel, resulting in a large area overhead, a big drawback. The scaled Max-log MAP algorithm is a common approach to implement the MAP algorithm due to its efficient architecture with its acceptable performance. Although many works have been reported to reduce the area of the MAP unit, an efficient VLSI...
Cognitive-engined spectrum-fragmented synchronous MC-CDMA based on generalized hadamard codes
, Article 2015 IEEE Wireless Communications and Networking Conference Workshops, WCNCW 2015, 9 March 2015 through 12 March 2015 ; March , 2015 , Pages 159-163 ; 9781479987603 (ISBN) ; Khojasteh, M. J ; Poursaeed, O ; Salehi, J. A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2015
Abstract
In Cognitive Radio (CR), in order to avoid interference in the Primary Users (PU), some subcarriers need to be deactivated. In systems based on Multicarrier Code Division Multiple Access (MC-CDMA), this causes losing orthogonality among different spreading codes, leading to poor Bit Error Rate (BER) performance. The performance of such system can be improved by using Generalized Hadamard Codes (GHC) instead of conventional Hadamard codes which avoids the loss of orthogonality. This is due to the fact that unlike conventional Hadamard codes, GHC are conjectured to exist for any arbitrary length. In this paper, we propose using a novel spreading code, namely, GHC for synchronous MC-CDMA in CR...
Energy harvesting systems with continuous energy and data arrivals: The optimal offline and heuristic online algorithms
, Article IEEE Journal on Selected Areas in Communications ; Volume 34, Issue 12 , 2016 , Pages 3739-3753 ; 07338716 (ISSN) ; Mirmohseni, M ; Aref, M. R ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2016
Abstract
Energy harvesting has been developed as an effective technology for communication systems in order to extend their lifetime. In this paper, we consider a single-user energy harvesting wireless communication system, in which arrival data and harvested energy curves are modeled as continuous functions. Our first goal is to find an offline algorithm, which maximizes the amount of data, which is transmitted to the receiver node by a given deadline. If more than one scheme exists that transmits the maximum data, we choose the one with minimum utilized energy at the transmitter node. We find this optimal algorithm, by showing its properties. Next, we propose an online algorithm for this system and...
Matching theory: Applications in wireless communications
, Article IEEE Signal Processing Magazine ; Volume 33, Issue 6 , 2016 , Pages 103-122 ; 10535888 (ISSN) ; Li, Y ; Song, L ; Han, Z ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2016
Abstract
Matching theory is a powerful tool to study the formation of dynamic and mutually beneficial relations among different types of rational and selfish agents. It has been widely used to develop high performance, low complexity, and decentralized protocols. In this article, a comprehensive survey of matching theory, its variants, and their significant properties appropriate for the demands of wireless communications and network engineers is provided. Recent research progress in applying matching theory to wireless communications to address major technical opportunities and challenges is presented. A novel classification of matching models from the practical perspective is provided, and the...
An online transmission policy for energy harvesting systems with data traffic arrival
, Article IWCIT 2016 - Iran Workshop on Communication and Information Theory, 3 May 2016 through 4 May 2016 ; 2016 ; 9781509019229 (ISBN) ; Mirmohseni, M ; Aref, M. R ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2016
Abstract
In communications, the nodes with the ability of harvesting energy potentially can prolong the overall network lifetime. In this paper, we consider a single-user energy harvesting wireless communication system, in which arrival data and harvested energy curves are modeled as continuous functions. Our goal is to find an online algorithm for the throughput maximization problem, which only needs the causal information of the arrival processes. We propose a heuristic online algorithm which is efficient for both discrete and continuous models, even when the distributions of harvested energy and arrival data are unknown
Toward 5G: Fiwi enhanced lte-a hetnets with reliable low-latency fiber backhaul sharing and wifi offloading
, Article IEEE/ACM Transactions on Networking ; Volume 25, Issue 2 , 2017 , Pages 690-707 ; 10636692 (ISSN) ; Levesque, M ; Maier, M ; Salehi, J. A ; Verikoukis, C ; Tipper, D ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2017
Abstract
To cope with the unprecedented growth of mobile data traffic, we investigate the performance gains obtained from unifying coverage-centric 4G mobile networks and capacity-centric fiber-wireless (FiWi) broadband access networks based on data-centric Ethernet technologies with resulting fiber backhaul sharing and WiFi offloading capabilities. Despite recent progress on backhaul-aware 4G studies with capacity-limited backhaul links, the performance-limiting impact of backhaul latency and reliability has not been examined in sufficient detail previously. In this paper, we evaluate the maximum aggregate throughput, offloading efficiency, and in particular, the delay performance of FiWi enhanced...