Abstract: Techniques to efficiently schedule and serve stations in a wireless network are described. An access point may aggregate stations with flows carrying traffic having similar characteristics, e.g., VoIP flows. The access point may schedule these stations together in an overall service period. The access point may serve each station in a respective service period within the overall service period. The access point may send a multi poll frame at the start of the overall service period to indicate the start time and/or service period for each station. Each station may decide to power down until its start time. The service periods for the stations may overlap one another. The service period for each station may cover an initial transmission as well as additional transmission and/or retransmission. If additional transmission and/or retransmission are not needed for a given station, then the next station may be served right away.

Abstract: Transmission patterns for pilot symbols transmitted from a mobile station or base station are provided. The patterns may be selected according to a location of the mobile station with respect to one or more antennas are provided. In some aspects, the pattern may be selected based upon the distance between the mobile station and the one or more antennas. In other aspect, the pattern may be based upon whether the mobile station is in handoff.

Abstract: For certain embodiments of this application, a method and apparatus for generating pilots in a wireless multiple-input multiple output (MIMO) communication system is disclosed. The certain embodiments can include obtaining at least one pilot symbol for each antenna of a plurality of antennas, obtaining an orthogonal sequence for each antenna in the plurality of antennas, and covering the at least one pilot symbol for each antenna with the orthogonal sequence to obtain a sequence of covered pilot symbols for each antenna to obtain at least one covered pilot symbols for each of the plurality of antennas.

Abstract: Pilots are transmitted on demand on a reverse link and used for channel estimation and data transmission on a forward link. A base station selects at least one terminal for on-demand pilot transmission on the reverse link. Each selected terminal is a candidate for receiving data transmission on the forward link. The base station assigns each selected terminal with a time-frequency allocation, which may be for a wideband pilot, a narrowband pilot, or some other type of pilot. The base station receives and processes on-demand pilot transmission from each selected terminal and derives a channel estimate for the terminal based on the received pilot transmission. The base station may schedule terminals for data transmission on the forward link based on the channel estimates for all selected terminals. The base station may also process data (e.g., perform beamforming or eigensteering) for transmission to each scheduled terminal based on its channel estimate.

Abstract: Techniques for detecting and demodulating a signal/transmission are described. Signal detection is performed in multiple stages using different types of signal processing, e.g., using time-domain correlation for a first stage, frequency-domain processing for a second stage, and time-domain processing for a third stage. For the first stage, products of symbols are generated for at least two different delays, correlation between the products for each delay and known values is performed, and correlation results for all delays are combined and used to declare the presence of a signal. For demodulation, the timing of input samples is adjusted to obtain timing-adjusted samples. A frequency offset is estimated and removed from the timing-adjusted samples to obtain frequency-corrected samples, which are processed with a channel estimate to obtain detected symbols. The phases of the detected symbols are corrected to obtain phase corrected symbols, which are demodulated, deinterleaved, and decoded.

Abstract: Systems and methodologies are described that facilitate dynamically scheduling frequency sets for reuse by user devices to reduce inter-cell interference by evaluating an overall scheduling metric for each user device in a wireless communication region. The overall scheduling metric can be evaluated by determining a fairness metric for each user device in a wireless communication region, an overall channel peak desirability metric for each user device, and a channel delay desirability metric for each user device. The overall scheduling metric can be the product of the fairness metric and one or more of the overall channel peak desirability metric and the channel delay desirability metric. A user device with a highest overall scheduling metric score for a given round of dynamic scheduling can be awarded a frequency set.

Abstract: Methods and apparatus are presented for dynamically controlling the re-transmission scheme of acknowledgment signals. A source transmits a first data packet over a slot s1. If channel conditions are favorable, source transmits a second data packet over slot s2, which precedes the reception of any acknowledgment signals. A destination receives first data packet over slot d1 and second data packet over slot d2. Destination decodes first data packet during slots d2 and d3, and second data packet over slots d3 and d4. Destination transmits an acknowledgment signal (ACK1) associated with first data packet during slot d4. Rather then transmitting the second ACK1 associated with first data packet over slot d5, destination preempts this slot with an acknowledgment signal ACK2, which is associated with second data packet transmitted by source. Hence, destination is configured to overwrite the repetition of a previous acknowledgment in order to transmit a new acknowledgment.

Abstract: For certain embodiments of the present disclosure, a method and apparatus for generating pilots in a wireless multiple-input multiple output (MIMO) communication system is provided. The method comprises obtaining at least one pilot symbol for each antenna of a plurality of antennas, obtaining an orthogonal sequence for each antenna in the plurality of antennas, and covering the at least one pilot symbol for each antenna with the orthogonal sequence to obtain a sequence of covered pilot symbols for each antenna to obtain at least one covered pilot symbols for each of the plurality of antennas.

Abstract: Techniques to process data for transmission over multiple transmission channels. The available transmission channels are segregated into one or more groups, and the channels in each group are selected for use for data transmission. Data for each group is coded and modulated based on a particular coding and modulation scheme to provide modulation symbols, and the modulation symbols for each selected channel are weighted based on an assigned weight. The weighting “inverts” the selected channels such that they achieve similar received SNRs. With selective channel inversion, only “good” channels in each group having SNRs at or above a particular threshold are selected, “bad” channels are not used, and the total available transmit power for the group is distributed across the good channels in the group. Improved performance is achieved by using only good channels in each group and matching each selected channel's received SNR to the required SNR.

Abstract: Techniques to achieve better utilization of the available resources and robust performance for the downlink and uplink in a multiple-access MIMO system. Techniques are provided to adaptively process data prior to transmission, based on channel state information, to more closely match the data transmission to the capacity of the channel. Various receiver processing techniques are provided to process a data transmission received via multiple antennas at a receiver unit. Adaptive reuse schemes and power back-off are also provided to operate the cells in the system in a manner to further increase the spectral efficiency of the system (e.g., reduce interference, improve coverage, and attain high throughput). Techniques are provided to efficiently schedule data transmission on the downlink and uplink. The scheduling schemes may be designed to optimize transmissions (e.g., maximize throughput) for single or multiple terminals in a manner to meet various constraints and requirements.

Abstract: A mobile station accesses a base station by randomly selecting a first reverse link common control channel from a set of random access channels. The mobile station transmits a request portion of an access probe over the first reverse link common control channel. The request portion is subject to collision with other signals. The request portion comprises a hash identification which is derived from a uniquely identifying number using a hash function. The hash identification quasi-uniquely identifies the mobile station. The mobile station receives a channel assignment message from the base station designating the hash identification and a reserved access channel. The reserved access channel provides communication with a low probability of contention. The mobile station transmits a message portion of the access probe over the reserved access channel.

Abstract: Pilot and data transmission schemes for multi-antenna communication systems utilizing multi-carrier modulation are provided. Subband multiplexing is used to avoid interference resulting from transmitting multiple signals simultaneously from multiple antennas. M usable subbands are initially arranged to form multiple groups of subbands, with each group including a different subset of the usable subbands. Each of T transmit antennas is then assigned one or possibly more subband groups for pilot transmission and typically one subband group for data transmission. Pilot and data may then be transmitted from each antenna on the subbands assigned to that antenna for pilot and data transmission. For each transmit antenna, the transmit power for each assigned subband may be scaled higher such that all of the total transmit power available for the antenna is used for transmission. Pilot and/or data may be transmitted simultaneously from all T antennas on all usable subbands without causing mutual interference.

Abstract: Backward compatibility may require the use of fields or other indicators that are interpreted by new nodes or stations in a system in a manner different from the way legacy nodes interpret those same fields. In some circumstances, these indicators may be used to “spoof” legacy nodes to behave in certain ways, to allow a next generation protocol to be performed without interference from those legacy nodes. While this practice is may increase communication effectiveness, spoofing may lead to inefficient operation of legacy nodes. Legacy nodes may detect spoofing, including detecting field settings in a legacy portion of a transmitted message, or detecting phase shifts in a message. Once spoofing is detected, a variety of steps may be taken, including determining the duration of the next generation message, entering a low power state for the duration, communicating on alternate channels for the duration, modifying legacy backoff procedures, and others.

Abstract: Systems and methods for providing packet based handoff in wireless communication systems are provided.

Abstract: Techniques are provided to support successive interference cancellation (SIC) receiver processing with selection diversity whereby each of NT transmit antennas may be turned on or off. One symbol stream may be transmitted from each transmit antenna. A SIC receiver recovers the transmitted symbol streams in a specific order. Up to NT! orderings are evaluated. For each ordering, NT post-detection SNRs are obtained for NT transmit antennas and used to determine NT data rates, where the data rate is zero if the post-detection SNR is worse than a minimum required SNR. An overall data rate is computed for each ordering based on the NT data rates. The ordering with the highest overall data rate is selected for use. Up to NT symbol streams are processed at the data rates for the selected ordering and transmitted. The transmitted symbol streams are recovered in accordance with the selected ordering.

Abstract: Techniques for processing a data transmission at the transmitter and receiver. In an aspect, a time-domain implementation is provided which uses frequency-domain singular value decomposition and “water-pouring” results to derive time-domain pulse-shaping and beam-steering solutions at the transmitter and receiver. The singular value decomposition is performed at the transmitter to determine eigen-modes (i.e., spatial subchannels) of the MIMO channel and to derive a first set of steering vectors used to “precondition” modulation symbols. The singular value decomposition is also performed at the receiver to derive a second set of steering vectors used to precondition the received signals such that orthogonal symbol streams are recovered at the receiver, which can simplify the receiver processing. Water-pouring analysis is used to more optimally allocate the total available transmit power to the eigen-modes, which then determines the data rate and the coding and modulation scheme to be used for each eigen-mode.

Abstract: Techniques to determine a set of rates for a set of data streams to be transmitted in a multi-channel communication system. A group of transmission channels to be used for each data stream is initially identified. An equivalent system for each group is then defined to have an AWGN (or flat) channel and a spectral efficiency equal to the average spectral efficiency of the transmission channels in the group. A metric for each group is then derived based on the associated equivalent system, e.g., set to the SNR needed by the equivalent system to support the average spectral efficiency. A rate for each data stream is then determined based on the metric associated with the data stream. The rate is deemed to be supported by the communication system if the SNR required to support the data rate by the communication system is less than or equal to the metric.

Abstract: Techniques to process data for transmission over multiple transmission channels. The available transmission channels are segregated into one or more groups, and the channels in each group are selected for use for data transmission. Data for each group is coded and modulated based on a particular coding and modulation scheme to provide modulation symbols, and the modulation symbols for each selected channel are weighted based on an assigned weight. The weighting “inverts” the selected channels such that they achieve similar received SNRs. With selective channel inversion, only “good” channels in each group having SNRs at or above a particular threshold are selected, “bad” channels are not used, and the total available transmit power for the group is distributed across the good channels in the group. Improved performance is achieved by using only good channels in each group and matching each selected channel's received SNR to the required SNR.

Abstract: Techniques to partition and allocate the available system resources among cells in a communication system, and to allocate the resources in each cell to terminals for data transmission on the uplink. In one aspect, adaptive reuse schemes are provided wherein the available system resources may be dynamically and/or adaptively partitioned and allocated to the cells based on a number of factors such as the observed interference levels, loading conditions, system requirements, and so on. A reuse plan is initially defined and may be redefined to reflect changes in the system. In another aspect, the system resources may be partitioned such that each cell is allocated a set of channels having different performance levels. In yet another aspect, terminals in each cell are scheduled for data transmission (e.g., based on their priority or load requirements) and assigned channels based on their tolerance to interference and the channels' performance.

Abstract: Techniques to more efficiently transmit pilot and signaling on the uplink in an OFDM system. With subband multiplexing, M usable subbands in the system are partitioned into Q disjoint groups of subbands. Each subband group may be assigned to a different terminal for uplink pilot transmission. Multiple terminals may transmit simultaneously on their assigned subbands. The transmit power for the pilot may be scaled higher to attain the same total pilot energy even though S instead of M subbands are used for pilot transmission by each terminal. Pilot transmissions from the terminals are received, and a channel estimate is derived for each terminal based on the pilot received on the assigned subbands. The channel estimate comprises a response for additional subbands not included in the assigned group. Subband multiplexing may also be used for uplink signaling transmission.