Abstract: Techniques for performing system selection and acquisition are described. In one design, a terminal may obtain at least one system record for at least one system utilizing orthogonal frequency division multiplexing (OFDM) or single-carrier frequency division multiplexing (SC-FDM). Each system record may include system identification information for an associated system and an index for an associated acquisition record. The terminal may also obtain at least one acquisition record for the at least one system. Each acquisition record may include at least one value for at least one configurable system parameter, e.g., FFT size, cyclic prefix length, number of guard subcarriers, etc. The terminal may perform acquisition for the at least one system in accordance with the at least one system record and the at least one acquisition record. The system and acquisition records may be stored in a Preferred Roaming List (PRL) or a Most Recently Used (MRU) list.

Abstract: Systems and methods are provided for processing Time Domain Multiplexing Pilot symbols by employing complex accumulators to determine peak values which indicate the start of timing and frequency information. In an embodiment, a method is provided for timing acquisition in a wireless network. The method includes acquiring samples from an Orthogonal Frequency Division Multiplexing (OFDM) data packet over a predetermined period of time, where the samples include one or more TDM pilot symbols. The samples are then processed to determine a maximum value that indicates the TDM pilot symbol has been detected.

Abstract: In an embodiment, a first repeater configures a beacon signal that identifies the first repeater to one or more other repeaters. The first repeater transmits the configured beacon signal at a given transmission power level to the one or more other repeaters. The transmitted beacon signal is received at least by a second repeater. The second repeater reduces interference associated with other transmissions from the first repeater, such as retransmissions of donor signals, based on the received beacon signal.

Abstract: A wireless repeater having a receiving antenna for receiving an input signal and a transmitting antenna for transmitting an amplified signal includes first and second front-end circuits and a repeater baseband block coupled between the first and second front-end circuits. The repeater baseband block includes a channel estimation block, an echo canceller implementing time domain echo cancellation, a variable gain stage controlled by a gain control block implementing digital gain control, a first variable delay element introducing a first delay before or after the echo canceller, a second variable delay element introducing a second delay to the output signal. The delayed output signal is coupled to the channel estimation block as a reference signal for estimating the feedback channel, to the echo canceller as a reference signal for estimating the feedback signal, and to the gain control block for monitoring the stability of the repeater.

Abstract: A method for controlling gain in a wireless repeater includes providing one or more gain control metrics where the gain control metrics is indicative of a loop gain of the repeater; measuring the one or more gain control metrics; and adjusting a variable gain of the repeater using a gain adjustment step size being a function of at least the loop gain of the repeater as measured by the one or more gain control metrics. In another embodiment, the gain control algorithm block is configured to divide the loop gain of the repeater into multiple gain adjustment control zones. The gain adjustment control zones may include a first zone having a loop gain in a stable operating region and a second zone having a loop gain outside the stable operating region.

Abstract: Methods and apparatus for initial acquisition gain control in a communication system a method for use in a wireless communication system are disclosed. A disclosed methodology includes measuring the power of a signal received by a transceiver a number of times over a prescribed time period, the signal including a number of symbols. A gain of the transceiver is unidirectionally adjusted when a currently measured power is greater than a previously measured power during the prescribed time period until a maximal power level is measured. By adjusting the gain to accommodate a maximal power value, which is the same as the power level of an acquisition pilot symbol, overshoot and distortion by the transceiver are avoided during initial timing and frequency acquisition. Corresponding apparatus are also disclosed.

Abstract: Systems and methods are provided for processing Time Domain Multiplexing Pilot symbols by employing complex accumulators to determine peak values which indicate the start of timing and frequency information. In an embodiment, a method is provided for timing acquisition in a wireless network. The method includes acquiring samples from an Orthogonal Frequency Division Multiplexing (OFDM) data packet over a predetermined period of time, where the samples include one or more TDM pilot symbols. The samples are then processed to determine a maximum value that indicates the TDM pilot symbol has been detected.

Abstract: A system and method for frequency diversity uses interleaving. Subcarriers of an interlace are interleaved in a bit reversal fashion and the interlaces are interleaved in the bit reversal fashion.

Abstract: A method for positioning a collection window for a Fourier transform function is disclosed. A first orthogonal frequency division multiplexing (OFDM) symbol and a second OFDM symbol are received. The first OFDM symbol comprises a plurality of frequency division multiplexed (FDM) symbols. The first OFDM symbol is characterized by at least two of the following: a delay spread, a first arriving path (FAP), or a last arriving path (LAP). A channel location is estimated from a channel impulse response. A point relative to the channel location is selected. A beginning of the collection window is positioned for the second OFDM symbol at the selected point. Alternatively, a point is selected at a first location relative to the channel location using a first algorithm if a delay spread is less than a predetermined length. The selected point is chosen at a second location relative to the channel location using a second algorithm if the delay spread is greater than the predetermined length.

Abstract: A method for characterizing a communication channel is disclosed. A detection window is moved through a channel profile to accumulate tap energies in the channel profile within the detection window into an accumulated energy curve. A peak at a maximum in the accumulated energy curve is determined. A band relative to the accumulated energy curve is defined. A first arriving path (FAP) is determined using a trailing edge found near a second end of a zone in the accumulated energy curve. A leading edge is found near a first end of the zone of the accumulated energy curve. The last arriving path (LAP) is determined using the leading edge. The band defines a zone of the accumulated energy curve at or near the maximum that is within the band.

Abstract: A method for determining a communication channel location is disclosed. A first subset of a plurality of channel impulse responses is averaged over a first time period to produce a first filtered channel impulse response, and a second subset of the plurality of channel impulse responses is averaged over a second time period to produce a second filtered channel impulse response. The second time period is different from the first time period, and the second subset is different from the first subset. The communication channel location is determined using the first filtered channel impulse response and the second filtered channel impulse response.

Abstract: Apparatus and methods for use in a wireless communication system are disclosed for determining a timing position for channel activity in order to resolve timing ambiguity. A disclosed apparatus includes a processor that determines when channel activity occurs in at least one of an early or a late arrival position in a communication channel estimate and unwraps the channel activity in either the early arrival position or the late arrival position to a corresponding late or early arrival unwrapped channel activity position in the wireless channel estimate. The processor correlates symbol data in the communication signal corresponding to both the channel activity and the unwrapped channel activity to symbol data of the main channel activity. The processor determines whether a correct timing position of the channel activity is one of the early or late arrival positions based on the correlations, thus resolving timing ambiguity. Complementary methods are also disclosed.

Abstract: A wireless repeater includes a gain control metric computation block to compute a gain control metric for use in controlling the variable gain of the repeater. The gain control metric is computed by downsampling the gain control input signal to the gain control metric computation block and also downsampling the computed correlation and normalization terms. The gain control metric may be further enhanced by filtering the computed metric values using linear or non-linear filtering.

Abstract: The subject invention selects a starting sub-carrier frequency group for a pilot staggering sequence to facilitate in mitigating the possibility of pilot signal collisions. In one embodiment, a randomized starting sub-carrier frequency group of the pilot is utilized in a first orthogonal frequency division multiplexing (OFDM) symbol of a frame. In another embodiment, a starting pilot sub-carrier frequency group number is determined by utilizing a random number generator such as, for example, a Pseudo-Noise (PN) sequence generator, seeded by a network identification (ID) number. In this manner, the starting sub-carrier frequency group is specific to that particular network. The subject invention also provides a more scalable system through the trading of system bandwidth for coverage.

Abstract: The disclosure is directed to a mobile communication device that may receive wireless broadcast signals from a number of different base stations or transmitters. As the location of the device moves relative to the transmitters, one transmitter will likely be identified as the transmitter broadcast the strongest, or highest quality, signal. When that determination is made, the user of the mobile device is presented the opportunity to switch to receiving that transmitters signal. Based on the user's reply, the device may remain with the current transmitter, even though it does not have the strongest signal, or the device may be configured to acquire and start receiving the new transmitter's signal. The measuring of the quality of a transmitter's signal may be based on a composite score that combines a number of individual measurements made over a predetermined period of time.

Abstract: Apparatus and methods for use in a wireless communication system are disclosed for reducing channel estimation noise in a device such as a wireless transceiver. A disclosed apparatus includes a processor that determines a channel activity portion and a noise portion of a channel estimation. The processor also determines a threshold noise level based on channel estimate values in the noise portion of the channel estimation. The processor compares channel estimate energy values in the channel estimation to the threshold noise level and sets each of the channel estimate energy values being less than the threshold noise level to a predetermined value such as zero in order to reduce or eliminate the noise. Similar methods are also disclosed.

Abstract: Systems and methods are provided for the transmission of waveforms to aid channel estimation, timing synchronization, and AGC bootstrapping in a wireless network. 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: Methods and apparatus for including mode information in a wireless transmission frame, which is useful for system acquisition. In particular, a first information bit is provided in a preamble of a transmission frame, where the bit is configured to indicate that a wireless communication system is operating according to either a time division duplex (TDD) mode or a frequency division duplex (FDD) mode. The addition of a single bit minimally affects the resources of the preamble. Additionally, another bit resource already present in the preamble for normally communicating whether FDD transmissions are full duplex or half-duplex transmissions, may be further allocated to indicate partitioning information concerning TDD mode transmissions when the first bit indicates TDD mode, thus affording additional information communicated in the frame without increasing preamble resources.

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 including mode information in a wireless transmission frame, which is useful for system acquisition. In particular, a first information bit is provided in a preamble of a transmission frame, where the bit is configured to indicate that a wireless communication system is operating according to either a time division duplex (TDD) mode or a frequency division duplex (FDD) mode. The addition of a single bit minimally affects the resources of the preamble. Additionally, another bit resource already present in the preamble for normally communicating whether FDD transmissions are full duplex or half-duplex transmissions, may be further allocated to indicate partitioning information concerning TDD mode transmissions when the first bit indicates TDD mode, thus affording additional information communicated in the frame without increasing preamble resources.