Abstract: The embodiments utilize OFDM symbols to communicate network IDs. The IDs are encoded into symbols utilizing the network IDs as seeds to scramble respective pilots that are then transmitted by utilizing the symbols. The pilots can be structured into a single OFDM symbol and/or multiple OFDM symbols. The single symbol structure for transmitting the network IDs is independent of the number of network ID bits and minimizes frequency offset and Doppler effects. The multiple symbol structure allows a much coarser timing accuracy to be employed at the expense of transmitting additional symbols. Several embodiments employ a search function to find possible network ID candidates from a transmitted symbol and a selection function to find an optimum candidate from a network ID candidate list.

Abstract: Systems and methods are provided for channel estimation and timing synchronization in a wireless network. In an embodiment, a method is provided for time synchronization at a wireless receiver. The method includes decoding at least one TDM pilot symbol located at a transition between wide and local waveforms and processing the TDM pilot symbol to perform time synchronization for a wireless receiver. Methods for channel estimation at a wireless receiver are also provided. This includes decoding at least one TDM pilot symbol and receiving the TDM pilot symbol from an OFDM broadcast to facilitate channel estimation for a wireless receiver.

Abstract: The embodiments utilize OFDM symbols to communicate network IDs. The IDs are encoded into symbols utilizing the network IDs as seeds to scramble respective pilots that are then transmitted by utilizing the symbols. The pilots can be structured into a single OFDM symbol and/or multiple OFDM symbols. The single symbol structure for transmitting the network IDs is independent of the number of network ID bits and minimizes frequency offset and Doppler effects. The multiple symbol structure allows a much coarser timing accuracy to be employed at the expense of transmitting additional symbols. Several embodiments employ a search function to find possible network ID candidates from a transmitted symbol and a selection function to find an optimum candidate from a network ID candidate list.

Abstract: Methods and apparatus for time tracking using assistance from TDM pilots in a communication network. In an aspect, a method is provided for time tracking in a device operating on a communication network, wherein the device performs a time tracking algorithm. The method includes determining a delay spread, and modifying at least one parameter used by the time tracking algorithm based on the delay spread. In another aspect, an apparatus is provided for time tracking in a device operating on a communication network, wherein the device performs a time tracking algorithm. The apparatus includes computation logic for determining a delay spread, and control logic for modifying at least one parameter used by the time tracking algorithm based on the delay spread.

Abstract: Systems and methods are provided for the transmission of waveforms. The method includes inserting at least one TDM pilot symbol located at a transition between wide area and local area waveforms to facilitate decoding of the transmission block.

Abstract: The embodiments provide mechanisms for synchronizing a receiver with OFDM pilots that are robust in the presence of channel fading conditions. In addition to using instantaneous channel estimate values to locate the first arriving path and last arriving path, the methods calculate time-domain averaged channel estimate values and use those averaged values to determine an average first arriving path and last arriving path. A combination of the instantaneous first arriving path and last arriving path and the average first arriving path and last arriving path may then be used to determine the delay spread and calculate a timing offset to be applied in timing synchronization. The various embodiments introduce improvements under channel fading conditions. Time-domain averaging may be embodied in a flexible DSP processor, or implemented in hardware and/or software. Using both instantaneous and time-averaged channel estimates greatly improves the robustness of time synchronization under channel fading conditions.

Abstract: The disclosure is directed to a receiver, and methods therefor, including an automatic gain control circuit with a first digital variable gain amplifier that outputs digital samples based on a modulated wireless signal, an interference canceller configured to filter the digital samples using a least mean squares algorithm to reduce narrowband interference, and a second DVGA configured to amplify the filtered digital samples.

Abstract: Systems and methods are provided for channel estimation and timing synchronization in a wireless network. In an embodiment, a method is provided for time synchronization at a wireless receiver. The method includes decoding at least one TDM pilot symbol located at a transition between wide and local waveforms and processing the TDM pilot symbol to perform time synchronization for a wireless receiver. Methods for channel estimation at a wireless receiver are also provided. This includes decoding at least one TDM pilot symbol and receiving the TDM pilot symbol from an OFDM broadcast to facilitate channel estimation for a wireless receiver.

Abstract: An improved receiver apparatus and acquisition algorithm using TDM pilots is disclosed. The timing acquisition method presented provides capabilities for adapting to changing channel conditions, in particular varying expected delay spreads. The information on an expected delay spread can be fed back to the initial acquisition algorithm based on previous successful attempts, and the delay spreads measured at that time, such as to set the length of the detection window used to in the TDM pilot processing. Based on the delay spread information, the algorithm for processing the specialized TDM pilot can adaptively modify the timing acquisition parameters for more robust performance under interference conditions. This may involve reducing the length of the detection window to just a little more than or equal to the maximum expected delay spread, which reduces sensitivity of the fine timing acquisition to signal noise.

Abstract: Systems and methods are provided for processing forward link only (FLO) signals. A device receives a FLO signal, processes a TDM pilot comprising a TDM Pilot 1, a TDM Pilot 2, a WIC, a LIC, a Transition Pilot Channel, and a Positioning Pilot, from the FLO signal, processes an overhead information symbol (OIS) comprising a wide-area OIS and a local-area OIS, from the FLO signal, processes an FDM pilot comprising a wide-area FDM pilot and a local-area FDM pilot, from the FLO signal; and processes data comprising wide-area data and local-area data, from the FLO signal.

Abstract: The disclosure is directed to a receiver. The receiver includes an interference canceller configured to filter digital samples produced from a modulated signal transmitted over a wireless channel, and a digital variable gain amplifier (DVGA) configured to amplify the filtered digital samples.

Abstract: Methods and systems are described for processing a signal in wireless communications. The signal may have synchronization information. A method of processing a signal having synchronization information may include receiving the signal, and determining a truncation region of the time domain estimated channel, the estimated channel having taps. The method further includes processing the channel taps within the truncation region.

Abstract: Methods and apparatus for setting timing of sampling of one or more symbols. The disclosed methods account for at least three types of effective interference (EI) and are used to set the timing of a sampling window for sampling received symbols. The methods includes setting timing based on determining an energy density function accounting for both static and dynamic EI, determining the minimum of a total energy profile and sliding the sampling window to ensure that the minimum point is at a predetermined point, and determining and using a composite energy profile accounting for short term and long term fading effects. The disclosed apparatus include a transceiver employing one or more of the disclosed methods for setting timing when receiving the symbols.

Abstract: An adaptive timing synchronization process dynamically adapts timing synchronization parameters for both wide and local area channels based on channel estimates. Timing synchronization parameters are dynamically adapted according to C/I estimates calculated from WID/LID energies. The timing synchronization algorithm 102 takes as the primary input, the current channel estimate 110 and produces an output comprising a correction to the current Fast Fourier Transform (FFT) sampling window position delta T (or offset) for locating the start of data within a current symbol 108. After dynamic parameter adjustment of noise filtering thresholds 104 and weak channel tap sensitivities 106 based on a calculated C/I from the channel estimate, a timing synchronization algorithm 102 locates the beginning of each continuous symbol by finding the boundary between the preamble, or cyclic prefix, and the useful data portions interlaced with pilots for channel information defining the start of a symbol 108.

Abstract: Methods and apparatus for setting timing of sampling of one or more symbols. The disclosed methods account for at least three types of effective interference (EI) and are used to set the timing of a sampling window for sampling received symbols. The methods includes setting timing based on determining an energy density function accounting for both static and dynamic EI, determining the minimum of a total energy profile and sliding the sampling window to ensure that the minimum point is at a predetermined point, and determining and using a composite energy profile accounting for short term and long term fading effects. The disclosed apparatus include a transceiver employing one or more of the disclosed methods for setting timing when receiving the symbols.

Abstract: In an OFDM system, a transmitter broadcasts a first TDM pilot on a first set of subbands followed by a second TDM pilot on a second set of subbands in each frame. The subbands in each set are selected from among N total subbands such that (1) an OFDM symbol for the first TDM pilot contains at least S1 identical pilot-1 sequences of length L1 and (2) an OFDM symbol for the second TDM pilot contains at least S2 identical pilot-2 sequences of length L2, where L2>L1, S1·L1=N, and S2·L2=N. The transmitter may also broadcast an FDM pilot. A receiver processes the first TDM pilot to obtain frame timing (e.g., by performing correlation between different pilot-1 sequences) and further processes the second TDM pilot to obtain symbol timing (e.g., by detecting for the start of a channel impulse response estimate derived from the second TDM pilot).

Abstract: Methods and apparatus for time tracking using assistance from TDM pilots in a communication network. In an aspect, a method is provided for time tracking in a device operating on a communication network, wherein the device performs a time tracking algorithm. The method includes determining a delay spread, and modifying at least one parameter used by the time tracking algorithm based on the delay spread. In another aspect, an apparatus is provided for time tracking in a device operating on a communication network, wherein the device performs a time tracking algorithm. The apparatus includes computation logic for determining a delay spread, and control logic for modifying at least one parameter used by the time tracking algorithm based on the delay spread.

Abstract: Methods and apparatus for timing synchronization based on transitional pilot symbols. In an aspect, a method is provided for time tracking synchronization in an OFDM system. The method includes receiving at least one TDM pilot symbol comprising a plurality of modulated sub-carriers that are configured to provide a channel estimate having a length that extends up to a duration of an FFT used for data transmission. The method also includes determining one or both of an instantaneous and averaged channel estimates from the plurality of modulated sub-carriers, and calculating a timing offset based on one or both of the channel estimates. An apparatus includes a receiver configured to receive the at least one TDM pilot symbol, a channel estimator configured to determine the instantaneous and averaged channel estimates, and a time synchronizer configured to calculate a timing offset based on the channel estimates.

Abstract: The disclosure is directed to a receiver. The receiver includes an interference canceller configured to filter digital samples produced from a modulated signal transmitted over a wireless channel, and a digital variable gain amplifier (DVGA) configured to amplify the filtered digital samples.

Abstract: A frequency tracking method and apparatus is provided. A receiver receives OFDM symbols and determines associated frequency offset. A frequency error estimator selects a cross correlation window for determining frequency offset based on timing offset. A symbol timing estimator is used to determine the timing offset.