Abstract: A non-cyclic evolving-type user resource structure applicable for use in the uplink and the downlink of an OFDMA system with large null guard tones (e.g., a 3GPP LTE system) is provided. In one example, the user resource structure combines the benefits of localized and distributed types of resource structures available in the current baseline 3GPP LTE (Release 8) specifications, and is especially suitable for operating in a fast time-varying channel. In another example, the non-cyclic evolving-type resource structure may be simplified to have no more than three stages: a band-type first stage, a partially evolved-type second stage and an interleaved-type third stage. Depending upon the target or average mobile speed and packet length, the resource structure may even have less than three stages.

Abstract: In a geolocation application, a method is provided to jointly estimate the time-of-arrival (TOA) and the amplitude of a received signal based on super-resolution technique. The super-resolution joint TOA-amplitude estimators are provided based on either the expectation-maximization (EM), parallel-interference-cancellation space-alternating generalized expectation maximization (PIC-SAGE) or serial-interference-cancellation SAGE (SIC-SAGE). The SIC-SAGE estimator minimizes the ranging estimation error especially under a non-line-of-sight (NLOS) condition. The SIC-SAGE estimator is a simplified version of the maximum likelihood estimator with more stable performance in a multipath rich environment, such as the ultra-wideband (UWB) based applications. These techniques provide the following benefits: 1) it is generic, so that signal processing can be deployed on both time-domain (e.g., UWB impulse-radio) and frequency-domain (e.g.

Abstract: An evolving-type resource structure supports high data rate services at high mobile speeds. The evolving-type resource structure is an efficient diversity-exploiting user resource structure for fast time-varying frequency-selective fading channel environments. In one example, an evolving-type resource structure takes advantages of both band-type and interleaved-type structures which exploit both multiuser diversity and frequency diversity in fast time-varying channels. The evolving-type resource structure is applicable to centralized, semi-distributed and distributed access schemes and may be used in both downlink (DL) and uplink (UL) transmissions in a cellular system.

Abstract: A mobile communication system uses a multiple-input-multiple-output (MIMO) technology with an orthogonal frequency division multiplexing access (OFDMA) scheme. At network entry, an initial ranging method selects from multiple ranging signal designs to accomplish the initial ranging process. Three classes of ranging signal designs may be selected for use in generating ranging codes. The information on the ranging signal design to be used, which is selected by the base station based on the cell size of the communication system (i.e., the radio coverage area of the base station), is broadcast from the BS. The ranging signal designs are directly applicable to single-antenna systems, and they are applied to MIMO systems by using appropriate mapping across transmit antennas based on the adopted MIMO ranging transmission scheme. Optimum eigenmode and suboptimum eigenmode transmission schemes provide the best performance at high computational complexity and high power consumption.

Abstract: A cooperative communication scheme is provided for a base station (BS) to communicate with a mobile station (MS) through a group of relay stations (RSs). The RSs, collectively referred to as a relay-associated group of RSs (R-group), serve the same target MS. The R-group may be formed during initial ranging or during periodical ranging of the MSs, according to the channel conditions between the MSs and the RSs. A reliable relay-associated transmission scheme provides fast recovery and reduces the burden on the BS. In one exemplary scheme, the BS transmits data to the R-group. To ensure that reliable transmission exists between the BS and the R-group, the BS initially sends the information to all the RSs in the R-group using multicast or unicast mode.

Abstract: A technique is provided to interleave data and control signals across a plurality of component carriers to achieve frequency diversity in conjunction with carrier aggregation.

Abstract: A time-of-arrival (TOA) estimation method for multi-band orthogonal frequency division multiplexing (MB-OFDM) signals uses a simple equally-spaced channel model to recover the impulse response of the wireless channel, and locates the delay of the first channel path by minimizing the energy leakage from the first channel path. The TOA is estimated based on the delay. Such a method does not require channel information for TOA estimation at the receiver and does not require modification of the receiver structure. The method also avoids a sub-optimal solution known to occur in maximum likelihood (ML) estimation.

Abstract: A base station (BS) communicates with a mobile station (MS) through relay stations (RSs). In one exemplary reliable relay-associated transmission scheme, the BS transmits data to the RSs using multicast or unicast. From the received packets, each RS calculates its reliability value according to a reliability function, which it informs the MS. The BS then generates a reliability metric to identify the RSs that are considered reliable. The reliable RSs transmit their information to the MS under a cooperative multicast transmission mode. Meanwhile, the unreliable RSs overhear the transmissions between the reliable RSs and the target MS. If the MS is unable to receive information from reliable RSs, the unreliable RSs can join the cooperative transmission to provide a higher cooperative diversity gain to the target MS.

Abstract: A cooperative communication scheme is provided for a base station (BS) to communicate with a mobile station (MS) through a group of relay stations (RSs). The RSs, collectively referred to as a relay-associated group of RSs (R-group), serve the same target MS. The R-group may be formed during initial ranging or during periodical ranging of the MSs, according to the channel conditions between the MSs and the RSs. A reliable relay-associated transmission scheme provides fast recovery and reduces the burden on the BS. In one exemplary scheme, the BS transmits data to the R-group. To ensure that reliable transmission exists between the BS and the R-group, the BS initially sends the information to all the RSs in the R-group using multicast or unicast mode.

Abstract: In a wireless communication system including a base station and multiple mobile stations, a method transmits an orthogonal frequency division multiple access (OFDMA) data frame to the mobile stations. The method includes the steps of (a) at the beginning of the data frame, collecting metrics representing channel conditions for each of the channels; (b) assigning each mobile station to one or more communication channels based on the metrics collected; (c) for each symbol in the frame, calculating an average bit-error-rate for each of a number of transmission modes, and assigning to that symbol the transmission mode corresponding to the lowest calculated average bit-error-rate for that symbol; and (d) transmitting the symbols in the frame according to their respective assigned transmission mode. In addition, a bit-loading optimization step may be carried out in conjunction with the method to determine a modulation order for each symbol to be transmitted.

Abstract: A method for detecting a subject's stress level associated with an activity includes (a) connecting the subject to a sensor that senses a value of a biometric; (b) during the activity, (i) repeatedly sensing the value of the biometric over each of a plurality of time windows; and (ii) computing, for each time window, a deviation in the sensed values of the biometric; and (c) detecting the stress level based on the computed deviations. In one implementation, the value of the biometric is a skin temperature measurement. The method may be implemented as an application in a wireless handheld device, such as a cellular telephone.

Abstract: A method determines an optimum bandwidth that minimizes ranging error in a geolocation application. The method ensures that an optimum bandwidth is selected under all channel conditions (i.e., both line-of-sight (LOS) and non-LOS (NLOS) conditions). Additionally, the method is generic and system-independent, such that it is applicable to both coherent receivers (e.g., match filter (MF) based receivers), non-coherent receivers (e.g., energy detector (ED) based receivers) and any types of time-of-arrival (TOA) estimators (e.g., whether peak-detection or threshold-based TOA estimator), regardless of the signal-to-noise ratios (SNRs) under consideration.

Abstract: A non-cyclic evolving-type user resource structure applicable for use in the uplink and the downlink of an OFDMA system with large null guard tones (e.g., a 3GPP LTE system) is provided. In one example, the user resource structure combines the benefits of localized and distributed types of resource structures available in the current baseline 3GPP LTE (Release 8) specifications, and is especially suitable for operating in a fast time-varying channel. In another example, the non-cyclic evolving-type resource structure may be simplified to have no more than three stages: a band-type first stage, a partially evolved-type second stage and an interleaved-type third stage. Depending upon the target or average mobile speed and packet length, the resource structure may even have less than three stages.

Abstract: A method and a receiver are provided for demodulating a received multi-carrier modulated signal. The demodulation procedure includes (a) multiplying the received multi-carrier modulated signal with its complex conjugate to obtain a squared signal; (b) multiplying the squared signal with a signal having a frequency 2 ? ? T to obtain a product signal, where T represents a duration of a symbol in the received multi-carrier modulated signal; and integrating the product signal over the duration T. The signal having a frequency 2 ? ? T may be a complex signal having the form exp ? ( j ? ? 2 ? ? T ? t ) ? ? or ? ? exp ? ( - j ? ? 2 ? ? T ? t ) , , or a cosinusoidal signal having the form cos ? ( j ? ? 2 ? ? T ? t ) , , according to whether the multi-carrier modulated signal is a complex signal or a real signal.

Abstract: An evolving-type resource structure supports high data rate services at high mobile speeds. The evolving-type resource structure is an efficient diversity-exploiting user resource structure for fast time-varying frequency-selective fading channel environments. In one example, an evolving-type resource structure takes advantages of both band-type and interleaved-type structures which exploit both multiuser diversity and frequency diversity in fast time-varying channels. The evolving-type resource structure is applicable to centralized, semi-distributed and distributed access schemes and may be used in both downlink (DL) and uplink (UL) transmissions in a cellular system.

Abstract: A method mitigates NLOS conditions based on weighted least squares (WLS) technique, in which the weights are derived from multipath components (MPCs) of the received signals. The weighting methodology can be used with both linear and non-linear least squares models, as well as different other NLOS mitigation schemes, such as residual based algorithms or maximum likelihood techniques.

Abstract: Non-line-of-sight (NLOS) identification and mitigation are carried out in a wireless positioning system based on channel statistics derived from multipath components of a received signal. The statistics may be based on the kurtosis, the mean excess delay spread, or the root mean square delay spread. The results are justified using IEEE 802.15.4a ultrawideband channel models. Amplitude and delay statistics based on the IEEE models are shown to be log-normal random variables. A joint likelihood ratio test is presented for the LOS and NLOS identification.

Abstract: A method that estimates jointly and iteratively the first arriving path of a received signal and a mobile terminal location uses a residual location error. The method may include setting a ranging threshold to reduce residual location error. The method iteratively estimates the first arriving path of the received signals and mobile terminal location, with the estimate of mobile terminal location improving the estimate of the first arriving path, and vice versa. Initially, a peak selection method determines a rough time-of-arrival (TOA) for a signal received at each of a number of different fixed terminals. An estimate of the location of the mobile unit is then provided (e.g., based on a least-squares (LS) triangulation). If the residual error is unsatisfactory, the TOAs are refined, using a search-back algorithm, which searches back from the strongest paths of the received signals. The new TOAs are used to refine the estimate of the location of the mobile terminal.

Abstract: A mobile communication system uses a multiple-input-multiple-output (MIMO) technology with an orthogonal frequency division multiplexing access (OFDMA) scheme. Multiuser diversity, multiantenna diversity, and power control since the first ranging attempt are exploited in the initial ranging process. At network entry, an initial ranging method selects from multiple ranging signal designs to accomplish the initial ranging process. In one embodiment, three classes of ranging signal designs may be selected for use in generating ranging codes. The information on the ranging signal design to be used, which is selected by the base station based on the cell size of the communication system (i.e., the radio coverage area of the base station), is broadcast from the BS. The ranging signal designs are directly applicable to single-antenna systems, and they are applied to MIMO systems by using appropriate mapping across transmit antennas based on the adopted MIMO ranging transmission scheme.

Abstract: A relaying selection and cooperative communications method provides a threshold selection criterion for forming a reliable group of relay stations (RSs) based on one or more design criteria. Possible design criteria include an outage probability constraint and a throughput constraint. The threshold value is selected according to, for example, transmission paths (e.g., line-of-sight, obstructed-light-of-sight, non-light-of-sight) or channel conditions (e.g., signal-to-noise-ratio) between the base station (BS) and the RSs (i.e., BS-RSs link) and between the RSs and the mobile station (MS) (i.e., RSs-MS link), respectively.