The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
The LOS components of the base station (BS) can provide a high SNR to mobile stations (MSs), but they cannot achieve a high spatial multiplexing gain in the MIMO-OFDMA system. The spatial multiplexing gain is obtained by degrees of freedom between MIMO antenna arrays. MIMO channels should be uncorrelated to achieve the maximum degrees of freedom, and it depends on rich scattering environments which...
Block diagonalization is a linear precoding technique which eliminates the multi-user interference at the transmitter side by creating parallel orthogonal single user links. In this technique, the transmit diversity order is fixed for each user and only power can be controlled to satisfy SINR requirements. This restricts the degrees of freedom available for resource allocation and limits the energy...
The mobile WiMAX standard (802.16e) uses multiple-input multiple-output (MIMO) limited feedback linear precoding to exploit the channel state information at the transmitter. Although the performance of limited feedback linear precoding in relation to traditional open-loop MIMO-OFDM has been extensively studied in the literature, these studies commonly assume perfect channel estimation at the receiver...
This paper proposes a new way of measuring signal to interference and noise ratio (SINR) at a low level of power consumption for vertical handover. In order to select the most suitable radio access networks (RAN) in vertical handover, the SINR of the alternative RAN should be measured at a certain interval while communicating with the existing RAN. In our proposal, the SINR measurement interval for...
A novel cell architecture based on Distributed Antenna Arrays for next generation mobile WiMAX systems is proposed. By exploiting Spatial Multiplexing and beamforming techniques, our target is to maximize the throughput of a high speed user by keeping low the deployment costs. Radio over Fiber is one of the best solutions to feed from a central point distributed arrays and share wireless resources...
We propose a cross-layer strategy that jointly optimizes user scheduling and resource allocation for adaptive modulation and coding (AMC) based orthogonal frequency multiple access (OFDMA). The objective of this paper is to maximize the system throughput as a function of the bit error rate (BER) and the spectral efficiency based on selected modulation and coding schemes (MCSs). The proposed optimal...
Energy consumption of mobile access networks has recently received increased attention. Although cellular networks account for a rather small share of energy that is used by the ICT (Information and Communication Technology) sector, lowering their energy consumption appears important from an economical perspective. This paper recalls different means to enhance the capacity of evolved mobile networks...
This paper addresses the problem of transmitting data to multiple mobile stations using a decode-and-forward strategy. Precoding vectors are used in relays to cancel out multiple access interference at the mobile stations. Statistical distribution of signal to noise ratio (SNR) is approximated by an expectation maximization algorithm. Based on this distribution, system performance is evaluated for...
In this paper indoor wireless Infrared (IR) technology for healthcare monitoring is studied. Monitoring provides a continuous and reliable vital sign measurement to secure patient staying in the hospital. Considering that patient moving is inevitable, we focus on a mobile IR channel based on diffuse propagation. A model of mobile channel is developed through the study of statistical distributions...
In this paper the performance of multiple-input multiple-output (MIMO) system in the UTRAN Long Term Evolution (LTE) standard is evaluated by means of ergodic system capacity in low (3 km/h), medium (30 km/h) and high (120 km/h) mobility scenarios. The impact of adaptive modulation as well as Hybrid ARQ (HARQ) with Chase Combining to the distribution of effective SINR is established analytically and...
In this work, we analyze the performance of a multi-user sectored MIMO/OFDMA system under the limited feedback constraint. Dynamic radio resource management methods are used to a reuse-one sectorized cell in order to reduce the cross-sector interference. Simulation results show that the proposed strategy reduces the co-channel interference and maintain at the same time high spectral efficiency.
In wireless cellular networks, indoor coverage is a problem from the perspective of the service provider. A femto Access Point, also known as femto AP, is utilized to solve the problem. Generally, the femto AP is deployed in a home to support indoor users. Since there might be a small number of users in the home, it could be expected that the traffic load of the femto AP is lower than its wireless...
In mobile OFDM systems, such as underwater acoustic and digital video broadcasting (DVB) systems, time variation causes severe inter-carrier interference (ICI) which limits data detection performance. To address this problem, a signal processing strategy using several partial-interval FFTs instead of a conventional full-interval single FFT is proposed. Weighted combining of the partial FFT outputs...
In digital mobile communication systems, speech coding is very important to increase the bandwidth efficiency. Usually, speech coding algorithms determine speech parameters, which are highly sensitive to transmission errors. In this paper, we use the residual redundancy remaining after using the Enhanced Variable Rate Codec (EVRC) algorithm for error concealment. Average residual redundancies of the...
This paper presents a joint estimator for Doppler shift and SNR in wireless communications, which is derived from the relation of level crossing rate (LCR) and signal-to-noise ratio (SNR) in mobile propagations. Computer simulations clearly show a good performance for our joint estimator in a wide range of SNRs and velocities.
In a wireless network, multiuser diversity can be exploited by allowing the mobile user with the best channel to use the channel. However, the overhead incurred in polling channel state information (CSI) can overshadow the multiuser diversity gain. In our previous work, we proposed a Multiuser Diversity with Capture (MDC) scheme to reduce the overhead by taking advantage of the fact that only the...
This paper addresses the stability of a multi-antenna space division multiple access (SDMA) system that uses zero-forcing beamforming to support packet data services for a small number of mobiles. Define the stability region as the set of packet arrival rates for which finite queue lengths are feasible in the steady state. Consider perfect feedback of channel state information (CSI) and equal power...
Recently, passivity-based techniques to control the transmit power of mobile nodes have been proposed to ensure the finite gain stability of a class of cellular CDMA networks. These techniques implement the Zames-Falb multipliers at the mobile node and at the base stations. The finite gain stability of such a cellular network follows as a consequence of the fact that the Zames-Falb multipliers preserve...
In the present wireless scenario, transmit diversity has become one of the key contributing technologies. Analytical estimations of bit error rate (BER) can be obtained with space time transmit diversity (STTD). The desired user's BER performance improves as fading of interfering signal decreases. Nakagami-m fading is becoming more prevalent in performance analysis and other studies related to mobile...
With the development of wireless and mobile Internet technology, people in everyday life and business hope for access to the Internet even while they are in movement. IEEE 802.20 technology is mobile and can effectively address high-speed network access. In this paper the PHY layer model for simulating 802.20 in SIMULINK and subsystems in MATLAB S-function files are presented. To evaluate the performance...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.