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channel-conditions
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Resource provisioning of MVNOs in a virtualized wireless network: a procurement auction approach
, Article 2018 IEEE Globecom Workshops, GC Wkshps 2018, 9 December 2018 through 13 December 2018 ; 2019 ; 9781538649206 (ISBN) ; Ashtiani, F ; Mirmohseni, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
In wireless network virtualization, by separating services and infrastructure, and due to new network components, some new challenges appear. In this paper, we consider the competition among multiple mobile virtual network operators (MVNOs) for provisioning the required rates for users subscribed to a service provider (SP). To realize this competition, we consider an SP as a beneficiary decision maker component, who can choose which users to be serviced by each MVNO. Since the states between each user and different channels of each MVNO are distinct, MVNOs compete to serve the users with good channel conditions to minimize their costs. Using a multiple non-identical object procurement...
Blind interference alignment for the K-User SISO interference channel using reconfigurable antennas
, Article IEEE Communications Letters ; Volume 22, Issue 5 , 2018 , Pages 1046-1049 ; 10897798 (ISSN) ; Aref, M. R ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
In this letter, we explore blind interference alignment (BIA) for the K-user single-input and single-output interference channel. We show that if we implement the structure of reconfigurable antennas at the receivers, by increasing the number of reception modes, the chance of finding proper channel conditions to align most part of interference signals will increase. Throughout this letter, we use the antenna structure of media-based modulation as reconfigurable antenna structure of the receivers. In this method, the receivers try to find proper channel states to align interference signals in an opportunistic manner. The results of this letter show that our proposed method has higher capacity...
Achievable rate regions for relay channel with private messages with states known at the source
, Article ; Proceedings 2010 IEEE International Conference on Information Theory and Information Security, ICITIS 2010, 17 December 2010 through 19 December 2010 , 2010 , Pages 1080-1087 ; 9781424469406 (ISBN) ; Mirmohseni, M ; Aref, M. R ; Sharif University of Technology
Abstract
In this paper, we consider State-Dependent Relay Channel with Private Messages (SD-RCPM) as a generalization of the state-dependent relay channel, where the relay is both a source and a sink of data. We assume that the channel state is known only to the source and investigate two main cases: SD-RCPM with non-causal Channel State Information (CSI), and SD-RCPM with causal CSI. For non-causal case, we propose a coding scheme based on Gel'fand-Pinsker type coding at the source which is informed of CSI, and Decode-and-Forward (DF) scheme at the relay. Using Shannon's strategy and DF scheme, we also propose a coding strategy for the causal case. Based on these coding strategies, we derive new...
Analysis of a deterministic power level selection algorithm with small and large power steps for Aloha networks under saturation
, Article Wireless Networks ; Volume 15, Issue 3 , 2009 , Pages 407-418 ; 10220038 (ISSN) ; Khalaj, B. H ; Sharif University of Technology
2009
Abstract
Standard power control techniques are not deployable in Aloha networks due to lack of central controlling entity and/or inefficiency of such algorithms in large networks with bursty traffic. To handle this problem in practice, simple transmission power selection algorithms are used for ranging and/or combating harsh channel conditions. In such algorithms, the transmission power is steadily increased by an amount called power step, until the packet is successfully transmitted. Noting that ranging is the major concern of this approach, small power steps are ideal for its operation. However, as we will show in this paper, using small power steps with this algorithm causes a throughput collapse...
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...
Delay-aware scheduling in heterogeneous multiuser systems
, Article 2006 IEEE 7th Workshop on Signal Processing Advances in Wireless Communications, SPAWC, Cannes, 2 July 2006 through 5 July 2006 ; 2006 ; 078039710X (ISBN); 9780780397101 (ISBN) ; Hossein Khalaj, B ; Sharif University of Technology
2006
Abstract
Adaptive scheduling schemes which consider channel conditions are examples of cross-layer design in wireless networks. Research work which has been done on optimizing the performance of scheduling systems have shown that in each time slot it is better to transmit to the users with the best channel condition. In order to realize such schemes, most of earlier works have considered perfect feedback channels to send Channel State Information (CSI) to the scheduler. However, in practical systems there are some sources of imperfectness in feedback channels such as delay and quantization error. In this paper, we consider the effect of CSI delay on the performance of such systems. A new delay-aware...
An adaptive feedback bit allocation method for wireless systems with transmit diversity
, Article 2005 1st International Conference on Computers, Communications and Signal Processing with Special Track on Biomedical Engineering, CCSP 2005, Kuala Lumpur, 14 November 2005 through 16 November 2005 ; 2005 , Pages 181-184 ; 1424400112 (ISBN); 9781424400119 (ISBN) ; Shariatpanahi, P ; Hossein Khalaj, B ; Sharif University of Technology
2005
Abstract
Using multiple antenna transmitters and/or receivers is becoming a common method for improving spectral efficiency of wireless channels. The physical layer of the next generation of WLAN systems (802.11n) is based on a Multiple Input Multiple Output (MIMO) system which seems to be an efficient solution for defects which could occur in wireless channels. In this paper, we investigate an adaptive bit allocation method to feed the quantized channel state data back to the transmitting antennas, depending on the channel condition in a Multiple Input Single Output (MISO) scheme. We have proposed an adaptive bit allocation scheme with a significant performance improvement over the fixed bit...