Abstract:
A method for performing channel estimation of an OFDM channel includes, in part, interpolating pilots for sub-channels positioned within a first range of an OFDM symbol, and estimating frequency response of sub-channels positioned within a second range of the OFDM symbol. The first range is defined by subchannels positioned substantially away from channel edges and the second range is defined by subchannels positioned substantially near channel edges. The method optionally includes transforming the pilots from frequency domain into the time-domain, time-domain windowing to obtain a channel impulse response having a multitude of discrete values, estimating the discrete values within the channel impulse response; and transforming the channel impulse response to the frequency domain.
Abstract:
An efficient channel estimation system and method provides good performance under high Doppler conditions and is suitable for OFDM systems such as DVB-T. A number of different pilot interpolations techniques enable the estimation of channel for the OFDM systems. For 2k and 4k modes, the channel is estimated using the preceding symbol, the present symbol, and two succeeding symbols. For an 8k mode, only one future symbol is used to estimate the channel.
Abstract:
An embodiment of the present invention is a technique to integrate data for a source synchronous protocol. A delay generator generates at least an integrating strobe from a data strobe synchronizing a data having a data window using the source synchronous protocol. A pulse generator generates a pulse from the at least integrating strobe. An integrating receiver integrates the data over an integration window defined by the pulse. The integration window is within the data window.
Abstract:
Embodiments include an on die termination circuit. The on die termination circuit may be programmable. The on die termination circuit may be programmed to compensate for environmental conditions and the physical characteristics of the device. The programmed on die termination circuit allows for faster transfer rates over communication lines by reducing the time needed to recover from signal reflection and similar issues.
Abstract:
A method and an apparatus are provided in an OFDM receiver for detecting and compensating for long echo. The method comprises a first pilot tone interpolation mechanism and a first window placement to filter a received OFDM symbol, a long echo channel detection coupled with a second pilot tone interpolation mechanism, a pre-echo and post-echo detection wherein the pre-echo condition is associated with a second new window placement, and both pre-echo and post-echo conditions place two time windows around a first peak channel response and a second peak channel response for channel estimation. The long echo is estimated by obtaining power spectra of a subset of subcarriers in one OFDM symbol, performing an inverse Fourier transform on the power spectra and determining the long echo by measuring the time between two peaks in the power profile.
Abstract:
Described is a system and method for applying transforms to multi-part files. A request is received to access a stream within a multi-part file. Upon receipt of the request, a list of transforms associated with the stream is identified. The list is also included within the multi-part file. The transforms specified in the list of transforms are performed on data before completing the request. If the request is a write, the transforms encode the data. If the request is a read, the transforms decode the data. The list of transforms is order dependent. The list of transforms includes a data structure having a first stream that includes a map that correlates the stream with a name for the list of transforms. A second stream that lists each of the transforms for the stream. A third stream for each of the transforms listed that identifies information associated with the transform.
Abstract:
A method and an apparatus are provided in an OFDM receiver for detecting and compensating for long echo. The method comprises a first pilot tone interpolation mechanism and a first window placement to filter a received OFDM symbol, a long echo channel detection coupled with a second pilot tone interpolation mechanism, a pre-echo and post-echo detection wherein the pre-echo condition is associated with a second new window placement, and both pre-echo and post-echo conditions place two time windows around a first peak channel response and a second peak channel response for channel estimation. The long echo is estimated by obtaining power spectra of a subset of subcarriers in one OFDM symbol, performing an inverse Fourier transform on the power spectra and determining the long echo by measuring the time between two peaks in the power profile.
Abstract:
A data transmission system is proposed, for example for video-on-demand, internet or multimedia applications, in which a number of subscribers in a building are connected to a central server through at least in part twisted pair cables within the building. Compensation for the channel distortion caused by the use of twisted pair cables is provided by the use of pre-emphasis filters in the outgoing data lines from the server. The required coefficients for the pre-emphasis filters are established by first characterizing the distortion properties of a channel by the use of a test signal.
Abstract:
A method for performing channel estimation of an OFDM channel includes, in part, interpolating pilots for sub-channels positioned within a first range of an OFDM symbol, and estimating frequency response of sub-channels positioned within a second range of the OFDM symbol. The first range is defined by subchannels positioned substantially away from channel edges and the second range is defined by subchannels positioned substantially near channel edges. The method optionally includes transforming the pilots from frequency domain into the time-domain, time-domain windowing to obtain a channel impulse response having a multitude of discrete values, estimating the discrete values within the channel impulse response; and transforming the channel impulse response to the frequency domain.
Abstract:
An embodiment of the present invention is a technique to calibrate an integrating receiver. A delay calibration circuit calibrates an adjusting code of a chain of delay elements and positioning of at least an integrating strobe used to define an integration window for the integrating receiver. An integrating receiver calibration pulse generator generates an IR calibration pulse from the at least integrating strobe. A calibration controller controls calibrating the adjusting code and the positioning of the at least integrating strobe.