Showing papers by "Amitava Ghosh published in 2008"

Method and apparatus for uplink power control in a communication system

Abstract: A communication system optimizes cell edge performance and spectral efficiency by a first step (404) of measuring, by the Node B, at least one system performance metric. A next step (406) includes sending, by the Node B, an indicator for the at least one system performance metric measurement. A next step (408) includes receiving the indicator for the at least one system performance metric measurement. A next step (410) includes determining an adaptive power control parameter based on the at least one system performance metric measured by the Node B and system performance metrics measured by at the least one other neighboring Node B. A next step (412) includes using the adaptive power control parameter to update an uplink transmit power level for at least one user equipment served by the Node B.

Method and apparatus for providing channel quality and precoding metric feedback in an orthogonal frequency division multiplexing communication system

Abstract: An Orthogonal Frequency Division Multiplexing communication system (100), wherein a frequency bandwidth is divided into one or more Resource Blocks Groups (RBGs) each having one or more Resource Blocks, provides for feedback of channel quality information and precoding metrics for a same at least one RBG of the one or more RBGs. More particularly, a user equipment (102) measures one or more channel quality parameters associated with at least one RBG of the one or more RBGs, determines channel quality information and a precoding metric for an RBG of the at least one RBG, and reports the channel quality information and a precoding metric determined for the RBG to a radio access network (110). In one embodiment of the invention, the RBG whose channel quality information and precoding metric are reported may be selected from the at least one RBG based on the measured channel quality parameters.

Method and apparatus for codebook based feedback in a closed loop wireless communication system

Abstract: A method and apparatus are provided for feedback for closed-loop transmitting with multiple transmit antenna elements and multiple receive antenna elements. A base station includes a codebook containing sets of weightings for the multiple transmit antenna elements, with each set of weightings identified by an index and the codebook known to the base station and a served mobile station (MS). The base station pre-codes pilot signals using a precoding matrix, preferably a unitary matrix, to produce pre-coded pilot signals, which precoding matrix may or may not be known to the MS and which precoding matrix may or may not be included in the codebook. The base station then transmits the pre-coded pilot signals to the MS via the multiple transmit antenna elements and, in response, receives an index to a set of weightings in the codebook for use in a subsequent transmission of a data stream.

Uplink control signaling in a communication system

Abstract: A system and method for uplink control signaling in a communication system includes a step of transmitting ( 200 ) the uplink control signaling in a frequency resource of the communication system reserved for random access. In particular, this step ( 200 ) can include allowing ( 202 ) the Physical Uplink Control Channel (PUCCH) to coexist with the Physical Random Access CHannel (PRACH) and transmitting ( 204 ) only channels which do not require Acknowledged/Negative Acknowledged (ACK/NACK) transmission.

Method and apparatus for allocating a physical random access channel in an othogonal frequency division multiplexing communication system

Abstract: A method and eNode B are disclosed that allocate a Physical random access channel (PRACH) in an Orthogonal Frequency Division Multiplexing communication system. In one embodiment, the eNode B maintains a predetermined location of a PRACH within a sub-frame, which predetermined location is adjacent to a Physical uplink control channel (PUCCH), allocates one or more sub-frames of a radio frame to a PRACH, and receives an access attempt over the PRACH based on the predetermined sub-frame location and the allocated one or more sub-frames. In another embodiment, the eNode B allocates one or more Physical Resource Blocks (PRBs) of one or more sub-frames of a PRACH hopping pattern period to a PRACH and informs a user equipment of the PRBs allocated for the PRACH by transmitting a first parameter informing of a slot configuration and a second parameter informing of a duration of a PRACH hopping period.

Uplink spatial division multiple access (sdma) user pairing and scheduling

Abstract: A method, system and communication network for transmitting information signals via uplink (UL) collaborative SDMA, in a wireless communication system. Base station receiver estimates a channel gain associated with the transmission path(s) of each user and keeps a matrix of normalized covariance, between users. Based on the estimated channel gain and the normalized covariance, ULS utility is able to compute channel capacity. Based on capacity estimates of (1) the multiplexed user signals and (2) the individual user signals, signals are either multiplexed for UL SDMA or are transmitted individually. An optimal selection of multiplexed signals may be based upon: (1) a cross user interface measurement; and (2) a selection mechanism based on eigen-decomposition techniques. The ULS utility enables a UL scheduler to pair information signals with clear spatial distinction and minimal correlation, based on capacity evaluations.

Feedforward of non-quantized precoding weights in a wireless communications system

Abstract: An apparatus and method to feedforward non-quantized precoding weights in an OFDM communication system includes a first step ( 300 ) of sending feedback information from a subscriber station (SS) to a base station (BS). A next step ( 302 ) includes deriving non-quantized weight information from the feedback information. A next step ( 304 ) includes transmitting symbols carrying the non-quantized weight information and non-precoded pilot symbols by the BS. A next step ( 305 ) includes receiving the information and symbols by the SS. A next step ( 306 ) includes estimating the non-quantized weights from the symbols carrying the non-quantized weight information and the non-precoded pilot symbols by the SS. A next step ( 308 ) includes decoding data from the BS by the SS using the estimated non-quantized weight information.

Method for blindly detecting a precoding matrix index

Abstract: A method for blindly detecting a precoding matrix index used to transmit a data or control signal is provided. The method includes receiving at a mobile station (102) a common reference signal and user specific data and control signal weighted by precoding matrix. An objective function is applied to the received reference signal and user specific data and control signal that minimizes the objective function for each of at least one rank used to transmit the received user specific data and control signal and each of known possible modulation constellations used to transmit the received data/control signal to determine the precoding matrix index (PMI).

Method and apparatus for choosing a modulation and coding rate in a multi-user, mimo communication system

Abstract: A method and apparatus for choosing a modulation and coding rate in a MU-MIMO communication system is provided herein. During operation, a node will determine the MCR to feed back to the base even though the mobile does not know which of the possible interferers (if any) will be using the same time/frequency resources as the mobile. This takes place via the mobile node calculating best antenna weights (codebook choice) for each group of subcarriers that can be potentially used by the mobile. Transmit weights v for each interferer are then determined and the weights are utilized to determine a best modulation and coding rate for the mobile.

Method and apparatus for implied resource assignment for uplink acknowledgment signalling

Abstract: A network node constructs ( 22 ) a downlink transmission using at least one group of resource elements. A remote unit receives ( 12 ) the downlink transmission and determines ( 13 ) a lowest index of the at least one group of resource elements. The remote unit then determines ( 14 ) an uplink resource, for use in uplink (UL) acknowledgment signaling, using the lowest index. The network node then receives ( 23, 24 ) the UL acknowledgment signaling that corresponds to the downlink transmission, the UL acknowledgment signaling having been transmitted using the uplink resource based on the lowest index. To determine the uplink resource, both the remote unit and the network node implicitly use the lowest index of the at least one group of resource elements that were used to construct the downlink transmission. Implicitly determining the uplink resource in this manner, serves to reduce overhead related to acknowledgment signaling.