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| Title |
Pub. Date |
Int. Class |
App. Num |
Applicant |
| 1. |
(WO 2009/142954) FEMTOCELL CHANNEL ASSIGNMENT AND POWER CONTROL FOR IMPROVED FEMTOCELL COVERAGE AND EFFICIENT CELL SEARCH
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26.11.2009
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H04W 36/00
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PCT/US2009/043573
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NTT DOCOMO INC.
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A method and a communication system for efficiently managing interference between femtocells and between each femtocell and a macrocell. The disclosed frequency assignment scheme for the femtocells minimizes interference between a femtocell and a macrocell and among different femtocells using a spectrum-sensing technique. The scheme selects a suitable channel from a set of candidate channels and ensures that the femtocell has an acceptable coverage area even when it is close to the macrocell base station. Additionally, the frequency assignment scheme favors a co-channel implementation to take advantage of the hand-off and cell search characteristics. In one embodiment, a joint power control and frequency band assignment technique partitions...
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| 2. |
(WO 2009/111392) OFDMA-BASED CO-CHANNEL FEMTOCELL
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11.09.2009
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H04W 72/00
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PCT/US2009/035716
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NTT DOCOMO, INC.
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A femtocell increases efficiency and coverage of a macrocellular network operating in a co-channel manner within the macrocell spectrum by selecting subcarriers for its mobile station using both the subcarrier allocation map received from the macrocell and a spectrum sensing operation. Interference is avoided by selecting only subcarriers not allocated by the macrocell and subcarriers allocated to users not nearby to the femtocell. Interference is eliminated from the received signals using co-channel interference avoidance techniques. Selection of subcarriers for femtocell use may take into consideration inter-carrier interference detected.
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| 3. |
(WO 2009/091420) METHOD AND SYSTEM OF TIME-OF- ARRIVAL ESTIMATION FOR ULTRA WIDEBAND MULTI-BAND ORTHOGONAL FREQUENCY DIVISION MULTIPLEXING SIGNALS
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23.07.2009
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H04L 27/28
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PCT/US2008/073133
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NTT DoCoMo INC.
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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.
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| 4. |
(WO 2009/058742) SYNCHRONIZED MULTI-LINK TRANSMISSION IN AN ARQ-ENABLED MULTI-HOP WIRELESS NETWORK
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07.05.2009
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H04L 1/18
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PCT/US2008/081369
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NTT DOCOMO, INC.
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A method and apparatus is disclosed herein for synchronized multi-link transmission in an ARQ-enabled multi-hop wireless network. In one embodiment, the method comprises performing pre-transmission of a packet to hops to enable a base station and the plurality of hops in the network to transmit the packet synchronously to one or more mobile stations in the wireless communication system; and performing one or more re-transmissions of the packet at a set of one or more hops forming a path in the network if time remaining before a synchronized transmission time for the path as a whole is greater than a threshold.
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| 5. |
(WO 2009/042472) A METHOD FOR ARQ-ENABLED PRE-TRANSMISSIONS IN MULTICAST AND BROADCAST SERVICES OF RELAY NETWORKS UTILIZING THE IDLE PERIODS
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02.04.2009
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H04L 1/18
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PCT/US2008/076693
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NTT DOCOMO, INC.
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A method and apparatus is disclosed herein for transmitting data in a network (e.g., a relay network). In one embodiment, the method comprises performing pre-transmission of a packet to hops to enable the base station and the plurality of hops to transmit the packet synchronously to one or more mobile stations in the wireless communication system; and performing one or more re-transmissions of the packet at a first set of one or more hops in the system during a delay due to pre-transmissions at a second set of one or more hops in the system.
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| 6. |
(WO 2009/035952) METHOD FOR AN IMPROVED LINEAR LEAST SQUARES ESTIMATION OF A MOBILE TERMINAL'S LOCATION UNDER LOS AND NLOS CONDITIONS AND USING MAP INFORMATION
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19.03.2009
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H04Q 7/22
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PCT/US2008/075634
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NTT DOCOMO INC.
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A linear least squares (LLS) estimator provides a low complexity estimation of the location of a mobile terminal (MT), using one of the fixed terminals (FTs) as a reference FT to derive a linear model. A method for selecting a reference FT is disclosed, which improves the location accuracy relative to an arbitrary approach to selecting the reference FT. In addition, a covariance-matrix based LLS estimator is proposed in line-of-sight (LOS) and non-LOS (NLOS) environments to further provide accuracy, taking advantage of the correlation of the observations. Different techniques for selecting the reference FT under non-LOS (NLOS) conditions are disclosed. A map-based two-stage LLS estimator assists in selecting the reference FT under NLOS cond...
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| 7. |
(WO 2009/006092) METHOD AND SYSTEM FOR A RELIABLE RELAY-ASSOCIATED AND OPPORTUNISTIC COOPERATIVE TRANSMISSION SCHEMES
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08.01.2009
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H04B 7/00
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PCT/US2008/067990
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NTT DOCOMO INC.
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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 serve the same target MS To ensure that reliable transmission exists between the BS and the RSs, the BS initially sends the information to all the RSs in the group The RSs then feedback their reliability values to the BS in a message If the reliability metric is greater than or equal to a threshold value, the RSs are considered reliable The reliable RSs transmit their information to the MS using a cooperative multicast transmission mode Meanwhile, the unreliable RSs within the relay group overhear the transmissions between the reliable RSs and the target MS The unreliable RSs that r...
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| 8. |
(WO 2008/124535) UPLINK MULTIPLE-INPUT-MULTIPLE-OUTPUT (MIMO) AND COOPERATIVE MIMO TRANSMISSIONS
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16.10.2008
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H04Q 7/20
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PCT/US2008/059307
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NTT DOCOMO INC.
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A method is provided for MIMO uplink communications between a base station and a wireless station with more than two antennae. The method includes: (a) negotiating between the base station and the wireless station uplink MIMO/cooperative MIMO capabilities, using a message exchange protocol in which a message exchanged comprises a field for specifying uplink MIMO/cooperative MIMO capabilities; (b) the base station receiving a request from the wireless station for data transmission; (c) the base station sending the wireless station an allocated resource and an uplink MIMO/cooperative MIMO method for uplink transmission; (e) the wireless station mapping data symbols to the allocated resource with proper pilot pattern; and (f) the base station ...
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| 9. |
(WO 2008/066815) A METHOD AND APPARATUS FOR RELIABLE MULTICASTING IN WIRELESS RELAY NETWORKS
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05.06.2008
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H04L 1/16
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PCT/US2007/024455
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NTT DOCOMO, INC.
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A method and apparatus is disclosed herein for performing multi casting. In one embodiment, the method comprises receiving routing, association, relaying, and/or topology information associated with a plurality of nodes in a multi-hop wireless network, the plurality of nodes communicably coupled in a tree or mesh arrangement via a plurality of broadcast channels; and determining a subset of the plurality of nodes over each broadcast channel on the multi-hop wireless network that is responsible for sending acknowledgment information, in response to receipt or lack of receipt of transmissions, back to senders of transmissions.
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| 10. |
(WO 2008/017034) WEIGHTED LEAST SQUARE LOCALIZATION METHOD EXPLOITING MULTIPATH CHANNEL STATISTICS FOR NON-LINE-OF-SIGHT MITIGATION
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07.02.2008
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H04Q 7/20
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PCT/US2007/075087
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NTT DOCOMO INC.
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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.
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| 11. |
(WO 2008/017033) LINE-OF-SIGHT (LOS) OR NON-LOS (NLOS) IDENTIFICATION METHOD USING MULTIPATH CHANNEL STATISTICS
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07.02.2008
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H04Q 7/20
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PCT/US2007/075084
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NTT DOCOMO INC.
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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 (210), the mean excess delay sprea (220), or the root mean square delay spread (230). 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 (260) is presented for the LOS and NLOS identification.
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| 12. |
(WO 2008/017032) ITERATIVE METHOD FOR JOINTLY ESTIMATING TIME-OF-ARRIVAL OF RECEIVED SIGNALS AND TERMINAL LOCATION
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07.02.2008
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H04Q 7/20
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PCT/US2007/075082
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NTT DOCOMO INC.
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A method for mitigating non-line-of-sight (NLOS) effects in a localization system uses both multipath channel characteristics and information from the mobile network. The method iteratively estimates the first arriving path of the received signals and the terminal location, with the estimate of the terminal location improving the estimate of the first arriving path, and vice versa. Initially, a peak selection method (100) determines a rough time-of-arrival (TOA) for a signal received (101) at each of a number of different fixed terminals (FTs). An estimate of the location of the mobile unit is then provided (e.g., based on a least-squares (LS) triangulation) (200). If the residual error is unsatisfactory, the TOAs are refined, using a searc...
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| 13. |
(WO 2007/018133) METHOD FOR SELECTING ENERGY THRESHOLD FOR RADIO SIGNAL
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15.02.2007
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G01S 7/285
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PCT/JP2006/315454
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MITSUBISHI ELECTRIC CORPORATION
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A method for estimation a time-of-arrival of a radio signal is provided. The signal is an ultra-wideband (UWB) signal. The method uses kurtosis of the received signal to estimate an energy threshold of the signal. The energy threshold can be used to determine a time-of-arrival of the signal.
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| 14. |
(WO 2007/011357) METHOD AND RECEIVER FOR IDENTIFYING A LEADING EDGE TIME PERIOD IN A RECEIVED RADIO SIGNAL
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25.01.2007
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H04L 7/00
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PCT/US2005/025476
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MITSUBISHI ELECTRIC RESEARCH LABORATORIES
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A method for identifying a leading edge time period of a received radio signal includes identifying a greatest energy time period in a sequence of time periods. The received radio signal has a greatest average energy in the greatest energy time period. The method also includes identifying a least energy time period in the sequence of time periods. The received radio signal has a least average energy in the least energy time period. Further, the method includes setting a threshold energy based on the greatest average energy and the least average energy, determining a number of window time periods based on a characteristic of a radio channel used by the received radio signal, and identifying as a leading edge time period an earliest time peri...
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| 15. |
(WO 2006/112831) METHOD AND SYSTEM FOR ESTIMATING TIME OF ARRIVAL OF SIGNALS USING MULTIPLE DIFFERENT TIME SCALES
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26.10.2006
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H04L 27/06
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PCT/US2005/013035
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MITSUBISHI ELECTRIC RESEARCH LABORATORIES
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A method and system (500) estimates a time of arrival of a signal received via a wireless communications channel. The energy in the received signal is conditioned at multiple different time scales to produce a conditioned signal (700). Then, a leading edge is detected in the conditioned signal (550). The leading edge corresponds to the time of arrival of the received signal (551).
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