Abstract: A portable wireless terminal generates and transmits a beacon signal. The beacon signal includes a sequence of beacon signal bursts, each beacon signal burst including one or more beacon symbols. A beacon symbol is transmitted using the air link resources of a beacon symbol transmission unit at a relatively high transmission power level with respect to user data symbols transmitted from the same wireless terminal, thus facilitating easy detection by other wireless terminals. The beacon symbols of the beacon signal occupy a small fraction of the total available air link resources. Beacon signals can, and sometimes do, convey wireless terminal identification information, via the location of the beacon symbols within the portion of the air link resource reserved for beacon symbol transmission units.

Abstract: Power control reports are communicated less frequently than the power control commands. The base station tracks the commands sent to the wireless terminal and estimates the wireless terminal's control channel transmit power. Received power control channel reports are utilized to compare the base station's estimated wireless terminal control channel transmit power to the actual wireless terminal control channel transmit power. An estimate of the error rate of transmitted power control signals is generated based using the tracked power command information and received power report information. Adjustments are performed in the power control command signaling to compensate for estimated error rates.

Abstract: Wireless terminal beacon signaling is used to achieve timing synchronization between two wireless terminals in a wireless communication system, e.g., in an ad hoc network lacking a centralized timing reference. An exemplary timing structure used by an individual wireless terminal includes a beacon transmission time interval, a beacon monitoring time interval and a silence time interval. A first wireless terminal monitoring for beacon signals from other wireless terminals, detects a beacon signal portion from a second wireless terminal and determines a timing adjustment as a function of the detected beacon signal portion. The first wireless terminal applies the determined timing adjustment, e.g., time shifting its timing structure, such that its beacon signal can be detected by the second wireless terminal.

Abstract: Techniques for efficiently sending reports in a wireless communication system are described. Reports may be sent repetitively in accordance with a reporting format. A terminal receives an assignment of a control channel used to send reports and determines a reporting format to use based on the assignment. The reporting format indicates a specific sequence of reports sent in specific locations of a control channel frame. The terminal generates a set of reports for each reporting interval and arranges the set of reports in accordance with the reporting format. The terminal repetitively sends a plurality of sets of reports in a plurality of reporting intervals. Reports may also be sent adaptively based on operating conditions. An appropriate reporting format may be selected based on the operating conditions of the terminal, which may be characterized by environment (e.g., mobility), capabilities, QoS, and/or other factors.

Abstract: Methods and apparatus for communicating transmission backlog information are described. Reporting control factors are utilized to expand reporting possibilities for a fixed bit size request report. At least one report control factor is determined as a function of channel quality information, power information, device capability information, and/or quality of service information. A transmission backlog report value is interpreted as a function of a reporting control factor. A wide range of quantization schemes for reporting transmission backlog information are facilitated corresponding to a small bit size report. A communications device can adaptively select a quantization request level closely matched to its current needs such as to provide an accurate representation of its current traffic channel resource needs.

Abstract: A wireless terminal determines the transmission power used for its dedicated control channel at a point in time, and generates a power report indicating a ratio of a maximum wireless terminal transmit power to the transmit power of the dedicated control channel at the point in time. The power report provides a measure of available transmit power for wireless terminal use for other purposes, e.g., uplink traffic channels, after taking into consideration the transmit power used for the dedicated control channel. The point in time has a known time offset from the start of a communications segment in which the power report is transmitted. This allows the base station receiving dedicated control channel uplink signals from the wireless terminal to measure the received signals, receive and process the communicated power report, and correlate information to be used for accurate wireless terminal closed loop power control.

Abstract: A wireless terminal receives a broadcast uplink interference report request conveying a requested report type and/or a locally unique base station identifier. The wireless terminal receives and measures broadcast reference signals, e.g., beacon and/or pilot signals, transmitted from a plurality of base station attachment points. Specific type interference reports relate a current serving connection base station attachment point to a selected base station attachment point corresponding to the received base station identifier. Generic type interference reports relate a current serving base station connection attachment point to other unspecified base station attachment points whose broadcast reference signals have been detected by the wireless terminal. Sub-types of generic reports include summation function and maximum function reports. Timing information is sometimes used to determine report sub-type and/or sector type of the selected attachment point.

Abstract: A wireless terminal receives and measures broadcast reference signals, e.g., beacon and/or pilot signals, transmitted from a plurality of base station attachment points. The wireless terminal monitors for and attempts to recover broadcast loading factor information corresponding to attachment points. The wireless terminal generates and transmits an interference report to a current attachment point, the report based on the results of a measured received reference signal from the current attachment point, a measured received reference signal from each of one or more different attachment points, and uplink loading factor information. In the absence of a successfully recovered broadcast uplink loading factor corresponding to an attachment point, the wireless terminal uses a default value for that loading factor.

Abstract: A multi-mode base station includes a transmit standby mode and an active mode. Transmit standby mode of base station operation is a low power/low interference level of operation as compared to active mode. In transmit standby mode at least some of the synchronization signaling such as pilot tone signaling is reduced in power level and/or rate with respect to the active mode. In transmit standby mode, the base station has no active state registered wireless terminals being serviced but may have some sleep state registered wireless terminals being serviced. Mode transitions from active to transmit standby may be in response to: a detected period of inactivity, scheduling information, base station mode change signals, and/or detected wireless terminal state transition. Mode transitions from transmit standby to active may be in response to: scheduling information, access signals, wake-up signals, hand-off signals, wireless terminal state change signals, and/or base station mode change signals.

Abstract: Wireless terminal for use with a multi-mode base station that supports a transmit standby mode and an active mode is described. Transmit standby mode of base station operation is a low power/low interference level of operation as compared to active mode. In transmit standby mode at least some of the synchronization signaling such as pilot tone signaling is reduced in power level and/or rate with respect to the active mode. In transmit standby mode, the base station has no active state registered wireless terminals being serviced but may have some sleep state registered wireless terminals being serviced. Mode transitions from active to transmit standby may be in response to: a detected period of inactivity, scheduling information, base station mode change signals, and/or detected wireless terminal state transition. Mode transitions from transmit standby to active may be in response to: scheduling information, access signals, wake-up signals from the wireless terminal, hand-off signals, etc.

Abstract: A method and apparatus for joint time and frequency synchronization for orthogonal frequency division multiplexing (OFDM) systems. A multitone pilot signal is sent in a designated OFDM symbol period. The receiver synchronizes to the pilot signal in a two-stage procedure. The first stage estimates the frequency offset coarsely with a frequency-domain correlation method and estimates the time offset with smoothed time-domain correlation. In a multipath channel, the smoothed time offset estimate is used to locate a cyclic prefix interval which captures the maximum total signal energy. The second stage improves the frequency estimate with a computationally efficient numerical optimization method.

Abstract: Transmit and/or receive diversity is achieved using multiple antennas. In some embodiments, a single transmitter chain within a wireless terminal is coupled over time to a plurality of transmit antennas. At any given time, a controllable switching module couples the single transmitter chain to one the plurality of transmit antennas. Over time, the switching module couples the output signals from the single transmitter chain to different transmit antennas. Switching decisions are based upon predetermined information, dwell information, and/or channel condition feedback information. Switching is performed on some dwell and/or channel estimation boundaries. In some OFDM embodiments, each of multiple transmitter chains is coupled respectively to a different transmit antenna. Information to be transmitted is mapped to a plurality of tones. Different subsets of tones are formed for and transmitted through different transmit chain/antenna sets simultaneously.

Abstract: Methods and apparatus for collecting, measuring, reporting and/or using information which can be used for interference control purposes. Wireless terminals measure signals transmitted from one or more base stations, e.g., base station sector transmitters. The measured signals may be, e.g., beacon signals and/or pilot signals. From the measured signals, the wireless terminal generates one or more gain ratios which provide information about the relative gain of the communications channels from different base station sectors to the wireless terminal. This information represents interference information since it provides information about the signal interference that will be caused by transmissions from other base station sectors relative to transmissions made by the base station sector to which the wireless terminal is attached.

Abstract: Transmit and/or receive diversity is achieved using multiple antennas. In some embodiments, a single transmitter chain within a wireless terminal is coupled over time to a plurality of transmit antennas. At any given time, a controllable switching module couples the single transmitter chain to one the plurality of transmit antennas. Over time, the switching module couples the output signals from the single transmitter chain to different transmit antennas. Switching decisions are based upon predetermined information, dwell information, and/or channel condition feedback information. Switching is performed on some dwell and/or channel estimation boundaries. In some OFDM embodiments, each of multiple transmitter chains is coupled respectively to a different transmit antenna. Information to be transmitted is mapped to a plurality of tones. Different subsets of tones are formed for and transmitted through different transmit chain/antenna sets simultaneously.

Abstract: Methods and apparatus for collecting, measuring, reporting and/or using information which can be used for interference control purposes. Wireless terminals measure signals transmitted from one or more base stations, e.g., base station sector transmitters. The measured signals may be, e.g., beacon signals and/or pilot signals. From the measured signals, the wireless terminal generates one or more gain ratios which provide information about the relative gain of the communications channels from different base station sectors to the wireless terminal. This information represents interference information since it provides information about the signal interference that will be caused by transmissions from other base station sectors relative to transmissions made by the base station sector to which the wireless terminal is attached.

Abstract: A method and apparatus for joint time and frequency synchronization for orthogonal frequency division multiplexing (OFDM) systems. A multitone pilot signal is sent in a designated OFDM symbol period. The receiver synchronizes to the pilot signal in a two-stage procedure. The first stage estimates the frequency offset coarsely with a frequency-domain correlation method and estimates the time offset with smoothed time-domain correlation. In a multipath channel, the smoothed time offset estimate is used to locate a cyclic prefix interval which captures the maximum total signal energy. The second stage improves the frequency estimate with a computationally efficient numerical optimization method.

Abstract: A synchronization of a pilot assisted channel estimation orthogonal frequency division multiplexing can be achieved by receiving a signal containing pilot symbols, providing an initial time and frequency synchronization to the signal, phase rotating the signal across time, transforming the signal with a fast Fourier transformation, phase rotating the signal across frequency, extracting the pilot symbols and generating a channel estimator. The phase rotating across time and the phase rotating across frequency are controlled by a phase rotation controller in accordance with the channel estimator. The initial time and frequency synchronization synchronizes the signal such that intercarrier interference effects and intersymbol interference effects are negligible. The signal may include plural carrier frequencies each having an arrival timing offset and a frequency offset. The signal may also include delay spread or Doppler spread.

Abstract: Methods and apparatus for efficient two-stage paging wireless communications systems are described. Wireless terminals are assigned to paging groups. A few first paging message information bits are modulated (using non-coherent modulation) into a first paging signal and communicated from a base station to wireless terminals. WTs wake-up, receive the first paging signal and quickly ascertain whether its paging group should expect a second paging signal, if so, the WT is operated to receive the second paging signal; otherwise, the WT goes back to sleep conserving power. The base station modulates (using coherent modulation) a number of second message information bits into a second paging signal and transmits the signal to WTs. From the information in first and second paging signals, a WT can determine that it is the paged WT and process the paging instructions. The intended paged WT can transmit an acknowledgement signal on a dedicated uplink resource.

Abstract: Improved timing synchronization and access control techniques for use in an orthogonal frequency division multiplexed (OFDM) wireless system or other type of wireless communication system. In accordance with the invention, an uplink synchronization and access control system is provided in which mobile stations transmit certain timing and access signals in dedicated intervals in an uplink stream. Access control is illustratively implemented as a two-stage process in which a given mobile first transmits a generic uplink access signal in one of the intervals. If this access is accepted, the base station transmits an access acknowledgment containing initial timing and power corrections, along with initial channel assignments on which the mobile can initiate a call set-up process. For re-synchronization, mobiles transmit timing synchronization signals in the dedicated timing and access intervals. The base station measures the arrival time of the signals, and sends back appropriate timing corrections.

Abstract: A base station having the strongest downlink signal is identified by utilizing a unique slope of a pilot tone hopping sequence being transmitted by a base station. Specifically, base station identification is realized by determining the slope of the strongest received pilot signal, i.e., the received pilot signal having the maximum energy. In an embodiment of the invention, the pilot tone hopping sequence is based on a Latin Squares sequence. With a Latin Squares based pilot tone hopping sequence, all a mobile user unit needs is to locate the frequency of the pilot tones at one time because the pilot tone locations at subsequent times can be determined from the slope of the Latin Squares pilot tone hopping sequence. The slope and initial frequency shift of the pilot tone hopping sequence with the strongest received power is determined by employing a unique maximum energy detector.