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With the growing demand for higher data rate networks, OFDM has emerged as a key technology for 4G standards like 3GPP LTE, IEEE 802.16m WiMAX and IEEE 802.11n WLAN. With its robustness to frequency selective fading, high spectral efficiency and ease of implementation by means of Discrete Fourier Transform(DFT), OFDM is a cutting edge technology for Broadband mobile wireless. Along with its compatibility...
This paper discusses the application of a beam forming algorithm that slows temporal variations of measured MIMO channels. A measurement campaign is described which surveyed a section of Manhattan using a low base transmitter. The data were processed to obtain angular spectra. The spectra were then used to generate synthetic channels for algorithm evaluation. With 4 antennas the beam forming approach...
The reliability of mobile packet data transmission in multi-input multi-output (MIMO) communication systems is degraded by time-varying multi-path channel fading. This so-called Doppler-effect can be mitigated by using a shorter packet length and/or inserting more pilot training symbols and frequently tracking the channel at the receiver at the cost of additional rate overhead. A judicious choice...
The decision-directed space-alternating generalized expectation-maximization (SAGE) algorithm is introduced in [1] to estimate the channel and track the channel varying for OFDM systems with transmitter diversity. However, this method is based upon a discrete Fourier transform (DFT), which will cause power leakage and result in an error floor in a multipath channel with non-sample-spaced time delays...
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...
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). Under these conditions, the conventional one-tap per subcarrier channel estimation and equalization is suboptimal since it does not account for ICI...
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...
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