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.
In this paper, the performance of a closed-loop transmit beamforming system employing the ";unconventional"; technique of analog channel state information (CSI) feedback is studied. The use of analog or unquantized symbols for CSI feedback leads to a low feedback rate of only one symbol per transmit antenna per frame, and does not result in an unrecoverable distortion as in the traditional...
In this paper, we propose a robust STBC transmission scheme to combat the timing synchronization errors over frequency-selective multiple-access channels. First, the equivalent channel model in the presence of timing synchronization errors is derived and we find that the synchronization errors result in an equivalent channel model with larger number of correlated channel taps. Based on this correlated...
Orthogonal frequency division multiplexing (OFDM) is the modulation scheme of choice for digital video broadcasting-handheld (DVB-H), which is required to operate under high mobility conditions resulting in significant Inter-carrier Interference (ICI). To mitigate ICI, several cancellation schemes have been proposed but they require reliable channel information at the receiver which is quite challenging...
Some communication applications, like multimedia, deliver data of different importance classes allowing unequal error protection (UEP) levels. In this paper, a multiple-input multiple-output (MIMO) system using orthogonal frequency division multiplexing (OFDM) is considered with a new UEP bit-loading algorithm based on the non-UEP algorithm by Chow, Cioffi, and Bingham. In the proposed bit-loading...
Three applications in wireless networks where model-free stochastic learning is applicable, are discussed. The learning based optimization problems are formulated and simulation results are presented. Some open issues are also discussed.
In this paper we derive optimal power allocation (PA) in space and time that minimizes BER for transmitter selection in multi-input-single-output (MISO) Rayliegh fading channels assuming perfect channel state information (CSI) is available at receiver and transmitter. This power allocation scheme achieves exponential diversity order with a single RF front end and requires feedback of the best channel...
This paper proposes a new space-frequency (SF) code construction scheme that can fully exploit both spatial and frequency diversities while providing great coding advantage and maintaining high bandwidth efficiency for MIMO-OFDM system operating in frequency-selective channels. The proposed SF code construction method is based on a class of trellis codes, where the trellis branches are labeled with...
Effects of improved channel estimation are studied for a proposed IEEE 802.11n OFDM MIMO system. Three channel estimation methods are considered: maximum likelihood (ML), time-domain truncation (TDT) and model-based (MB). TDT and MB are particularly useful when the channel delay spread is short. For an MMSE receiver, MB shows a 1-2.5 dB improvement over ML on the packet error rate performance for...
In this paper, we consider a new channel probing scheme for opportunistic scheduling in the uplink of orthogonal frequency division multiplexing (OFDM)-based wireless systems. To reduce signaling overhead for the probing, we consider a two-step channel probing process; called pre-probing and mainprobing. Good subchannels are first estimated through the pre-probing process using a probing signal transmitted...
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.