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.
For joint MIMO-OFDMA link adaptation and scheduling, channel quality feedback needs to be quantized, sparse and irregular. For flexible scheduling, prediction of the quantized channel at the base-station is needed. We propose measurement of 3D channel correlation parameters by the terminals and signalling back to the base station, which enables prediction of the quantized channel by multi-dimensional...
In this paper, we introduce several technologies to adapt orthogonal frequency division multiple access (OFDMA) scheme to satellite environments. Maximizing the commonalities with the terrestrial system is one of the most important factors for cost-effective service delivery, which will finally bring successful deployment of the system. For this purpose, we adopt an orthogonal frequency division multiplexing...
In order to reduce the pilot number and improve the spectral efficiency, recently emerged compressed sensing (CS) technique is applied for digital broadcast channel estimation. According to the six channel profiles of the ETSI digital radio mondiale (DRM) standard, the subspace pursuit (SP) algorithm is employed for the delay spread and attenuation estimation of each path in the case where the channel...
A novel de-centralized dynamic inter-cell interference coordination (ICIC) method, which can change cell-edge bands dynamically by using an X2 interface and can be applied to current downlink long-term evolution (LTE) systems, is proposed. This dynamic ICIC method can autonomously optimize fractional frequency reuse (FFR) parameters and thus increase throughput. In addition, it works well even in...
Low voltage power lines are attractive for communications in smart metering, but they are subject to many kinds of interferences. One important source of interference is the one which is synchronous with the power network frequency. This noise shares the mean periodicity with the mains, but it also usually has some sort of time drift or jitter that shifts the position and phase of the signal from...
In this paper, a jointed preamble/boundary detection and fractional carrier frequency offset (CFO) estimation design is presented which supports dual SC/HSI modes of IEEE 802.15.3c applications. Based on correlation based algorithms which utilizes the structure of preamble, an efficiency architecture is proposed which realizes synchronization detection with a sequential detection scheme and only single...
Wind blowing over the sea surface generates many dramatic effects. One of the most important effects is bubbles generated by breaking waves, which can have a major effect on high frequency acoustic propagation, sound speed profile and ambient noise due to the sound scattering and absorption properties of a thin layer of bubbles. In this paper, on one hand, we analyze several important properties of...
Wimax (Worldwide Interoperability for Microwave Access) is a promising technology which can offer high speed data, voice and video service to the customer end, which is presently, dominated by the cable and digital subscriber line (DSL) technologies. The performance assessment of Wimax systems is dealt with. The biggest advantage of Broadband wireless application (BWA) over its wired competitors is...
This paper presents a novel maximum likelihood (ML) time difference of arrival (TDoA) estimation algorithm for subsample delays. We introduce a new initial acquisition and cell search algorithm with implicit multiple access interference (MAI) cancelation. A joint carrier frequency offset (CFO) estimation and subsample delay estimation is used to compensate Doppler spreads and oscillator drifts. Analytical...
Orthogonal frequency division multiplexing (OFDM) is effective method for transmitting high speed data at frequency selective channel. But OFDM is sensitive to the carrier frequency offset (CFO) and sample timing offset (STO). As these effects, inter-carrier interference (ICI), inter-symbol interference (ISI) and common phase noise error (CPE) occur. And these effects cause degradation of performance...
For providing multimedia streaming services in a mobile WiMAX network, it is important to not only optimize the power consumption of mobile stations (MSs) but also satisfy the QoS requirements of the streams. This paper studies the problem of optimizing the power consumption of the mobile stations (MSs) in the cell of a base station (BS) where each MS has several uplink and downlink connections of...
In this paper, two estimators are proposed for calculating fine timing and channel impulse response (CIR) of a CD-OFDM based communication system. The proposed low complexity algorithms are designed to operate with asynchronous nodes having independent timing and carrier frequency offsets. These algorithms fully exploit the specially designed structure of time domain preamble used for cooperative...
In this paper, we propose a 2-dimensional (2D) delay-Doppler span estimation method based on the energy leakage suppression technique for OFDM pulse train radar systems. Unlike the existing methods which aim at resolving multiple target reflections, this estimator focuses on the span of the target on the 2D delay-Doppler plane, i.e., the nearest and furthest boundaries in delay, and the smallest and...
Current communication schemes rely on instantaneous adaptation, which increases the system complexity and is memoryless. We propose a scheme for adapting system parameters based on a priori knowledge of the channel statistics to reduce feedback requirements. As a vital parameter in OFDM system, cyclic prefix (CP) length depends mainly on two channel characteristics: the channel gains and the root...
Scheduling is a fundamental component in resource (bandwidth and power) management in NG wireless networks and plays the main role in providing QoS requirements such as delay, throughput and packet loss for different classes of service in 802.16d networks. In this paper we propose a novel scheduling algorithm Strict Priority Based Adaptive modulation and Coding (SP_AMC_Based) that can grantee QoS...
Multiuser diversity combined with Orthogonal Frequency Division Multiple Access (OFDMA) are a promising technique for achieving high downlink capacities in new generation of cellular and wireless network systems. The total capacity of OFDMA based-system is maximized when each subchannel is assigned to the mobile station with the best channel to noise ratio for that subchannel with power is uniformly...
A 2D Markov-Chain analysis is used to model channel occupancy within a high mobility picocell based network including handover and outage events. Single-cell performance is evaluated by the Grade of Service and by the call dropping probability. The relations between different picocellular network parameters are analyzed and guidelines for proper MAC protocol design are given.
In this paper we propose three different frequency resource management strategies that, working together with FFR and open-loop Fractional Power Control (PFC), succeed on mitigating both uplink inter-cell interference (ICI) and ICI fluctuations, that usually reduce the performance of SC-FDMA cell-based systems. Simulations are carried out with real-time traffic patterns at different loading scenarios,...
This paper presents simulation of WiMAX based system under jamming. The performance of the system was found out to greatly differ with the use of different jamming signals, allowing central areas to be identified, where system development should be focused on. In addition, from the basic theory point of view, rather surprising results were also found. This work should give a clear picture of how the...
Multiband Orthogonal Frequency Division Multiplexing (MB-OFDM) approach using UWB signals with short duration of pulses provide unique advantages in short-range high data rate wireless applications which include easy penetration through obstacles, high precision ranging and low processing power. A perfect reconstruction using discrete wavelet packet transmultiplexer in MB-OFDM transceiver counters...
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.