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.
Location-based services rely on the accuracy of the user's position estimates. In WAW ("Where Are We?") location- based services, users want to be aware, not only, of their own position but also the position of the other elements on their group. If this information is available in real-time, this kind of service can be used to support coordinated positioning operations. This paper presents...
RSSI (received signal strength indicator)-based localization is advantageous in terms of transceiver hardware complexity, because almost all current wireless standards have the functionality in their protocols. In a localization area, a ??design?? problem to determine the placement of anchor nodes satisfying a required localization accuracy has never been addressed, although the accuracy of RSSI method...
This paper investigates the problem of optimal assignment of wireless interfaces for service delivery in the context of a heterogeneous wireless access system. We formulate service requests initiated by the applications running on the mobile device as a multiobjective optimization (MOO) problem: optimal mapping of application requirements to wireless interface while minimizing the monetary cost and...
The trend of merging telecommunication infrastructures with traditional IT infrastructures is becoming increasingly more common. The driver behind this development is partly the strong need for enhanced services from the telecom operator??s side aiming for value added services provision to the customer. The effect of this new trend is that existing value chains in the Telco infrastructure will disappear...
Innovative Ajax-like functionality in a mobile video delivery system is introduced, where light-weight, smooth, and quick-responsible accessibility to contents can be provided. This technology consists of viewers?? view context aware asynchronous pre-fetching and streaming scheme, and seamless media assembly and media synchronization scheme. This paper describes its innovative mechanisms and elemental...
Due to the recent popularization of digital broadcasting systems, selective contents, i.e., users watching their selected contents, have attracted attention. For example, in a quiz program, a user selects his or her answer and watches the video content for the answer. Although the server can deliver programs that meet users?? preferences, clients have to wait until their selected contents are delivered...
In this paper we present a method for the quasi-reliable transfer of Digital Cinema (DC) content over packet-lossy IP networks, such as wireless networks. By employing the MXF (Material eXchange Format) encapsulation, reliable transmission of MXF keys backup, and compressed frames Forward Error Correction (FEC), we show that visual artifacts due to packet losses are virtually cancelled, and decoder...
This paper describes and evaluates a novel resource management technique for minimizing the file transmission cost in a hybrid cellular-broadcasting system. While DVB-H technology is utilized for wide area broadcasting, the 3G-HSDPA system takes the role of providing not only feedback about reception conditions, but also on-demand repair information to the users that have missed part of the DVB-H...
The development of user interfaces for portable devices offers numerous challenges because of the heterogeneity of the environments in which mobile services are deployed. Thus, an adaptive middleware is needed to generate the user interfaces and adjust their parameters to the different usage scenarios. The middleware needs to enable the separation of the adaptation procedures from the core operations...
The present paper investigates call admission control (CAC) over multiservice wireless - broadband over power line (BPL) networks. The CAC problem is examined not only as a decision process but, also, as a channel reallocation and QoS renegotiation process. A fast and effective CAC algorithm for BPL networks is proposed providing high network utilization, low blocking rate (BR) and fairness between...
In a mobile communication system, it is important to assess the speech quality offered to the user. In GSM, if the AMR codec is employed, the vocoder bit-rate can be changed during a call according to the channel conditions. Speech quality evaluation can be difficult in this adaptive-rate scenario, and commonly used statistics, such as RXQUAL, are not sufficient for that purpose. This paper proposes...
When planning the structure of a backhaul mesh network for public access, it is common to introduce redundant nodes in the mesh network. These are called redundant, because they do not increase the network capacity under normal operation, due to the shortest-path metric of the routing protocol. Instead, their sole purpose is to increase the network reliability by providing failover links when a link...
Efficient management of mobile network resources is a critical task for successful operation. Giving higher priority and quality of service to applications with a high return on invest value, demands for intelligent distribution of bit rates and radio access. The research approach proposed here is based on the fact, that users cannot move freely, but are restricted to streets or rails in position,...
In this paper, we propose a fast prediction method adapted to multi-user turbo detection based on linear filtering and successive interference cancellation. Using Gaussian approximation, compression and quality tables, the method provides for each user its expected transmission quality at each iteration according to the linear filter of the multi-user detector (MMSE or Matched Filter) as well as its...
The on-line Bayesian Cramer-Rao (BCRB) lower bound for the dynamic estimation of a time-varying multi-path Rayleigh channel in 4-QAM OFDM system is considered. In case of negligible channel variation within one symbol and delay related information, true BCRB for data-aided (DA) context, and two closed-form expressions for non-data aided (NDA) context are derived.
We propose a new technique to estimate the signal-to-noise ratio (SNR) over flat fading time-varying single-input multiple-output (SIMO) channels, for quadrature amplitude modulation (QAM) signals in complex additive white Gaussian noise (AWGN). This technique relies on the use of periodically transmitted pilot symbols in the estimation process. It is a decision directed (DD) procedure since detected...
This paper proposes a two-step noise suppression method in the frequency and time domains for frequency domain channel estimation in single-carrier (SC)-FDMA radio access using a variable transmission bandwidth. In the proposed method, a weighted coherent averaging filter suppresses the noise component of the estimated channel gain in the frequency domain and then, after conversion of the channel...
This paper deals with transform domain channel estimation (TD-CE) in the MIMO-OFDM system when null carriers are placed at the edges of the spectrum in order to assure band isolation from interfering signals that occupy neighboring frequency bands. Indeed, the presence of these null carriers leads to a degradation of channel estimation because of a ??border effect?? phenomenon when using a discrete...
The Expectation-Maximization (EM) algorithm is studied to perform channel estimation in a low cost and high data rate impulse radio UWB receiver. The system under consideration uses a pulse position modulation with a simple analog energy detector. In order to overcome the problems inherent to high data rates, such as inter-symbol interferences, a probabilistic equalizer is used. The EM algorithm and...
Generative models hold the promise of reducing the computational load and cost caused by directly simulating a real system. They are vital to the design and performance evaluation of error control schemes and high layer wireless communication protocols. Therefore, designing an efficient and accurate generative model is highly desirable. Moreover, the errors encountered in digital wireless channels...
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.