Abstract: A apparatus and method for improved performance in radio telecommunications systems, and in particular multi-carrier code division multiple access (MC-CDMA) networks that employ pulse-shaping filters on the transmit side of a radio link. In order to more accurately transmit a radio signal bearing a symbol sequence, the modulated and spread information stream is upsampled using a technique that involves inserting zeros in the frequency domain. A corresponding downsampling procedure on the receive side permits reconstruction of the transmitted symbols. A new channel estimation algorithm may also be used, and the improved channel estimation advantageously employed to obtain more faithful symbol detection.

Abstract: A generalized zigzag code is described where the code segments (each including one parity bit and information bits) of a block are not necessarily of uniform length. For coding rates in which the average code segment length is not an integer, all code segment lengths may be identical. The number of code segments depends on the coding rate and number of information bits in a block. At the encoder, parity bits are added to each string of information bits in a block to yield the code segments. For a punctured code, concatenated or not, the encoder may remove or not generate the punctured parity bits. At a decoder that operates at a rate different from the code rate of a received block, null parity bits are inserted. The received block has a number of code segments. The decoder increases the number of code segments by the addition of null parity bits, thereby reducing the coding rate to the rate of the decoder. Methods and apparatuses are detailed.

Abstract: A multi-level space time signal constellation that is optimized for use with a multi-carrier, multi-path communication scheme includes points on a first level separated from points on a mutually exclusive second level by a minimum distance that is based on a conditional probability distribution, preferably a Kullback-Leibler (KL) distance. Points within one level may be separated by a Euclidean distance, but spherical levels are rotated relative to one another to maximize a minimum inter-level KL distance. A receiver uses pilot symbols to estimate the channels and two-stage symbol detection, determining in one stage the constellation level and in another stage the point in the level. The receiver calculates a likelihood function based on a conditional distribution which does not reduce to the Euclidean-based nearest-neighbor detector. A single stored constellation may be scaled based on received signal to noise ratio.

Abstract: A method includes selecting one of a plurality of transmitter systems used to transmit data. Each transmitter system corresponds to one of a plurality of subbands. Each subband has a bandwidth and at least two of the subbands have different bandwidths. A physical layer technology is common to and used by each transmitter system to transmit on a respective subband. The selected transmitter system transmits the data. An apparatus includes a plurality of transmitter systems, each corresponding to one of a plurality of subbands. Each subband has a bandwidth and at least two of the subbands have different bandwidths. A physical layer technology is common to and used by each transmitter system to transmit on a respective subband. A controller is operable to select one of the transmitter systems to use to transmit data, and is operable to cause the selected transmitter system to transmit the data.

Abstract: An approach is provided for communicating in a multi-carrier system. A carrier selector selects one or more carriers among a plurality of carriers for transport of data over the multi-carrier system, wherein the data is transmitted using the selected carriers.

Abstract: A first data symbol that includes a kth data bit is received over a multicarrier system. A first channel quality parameter is estimated for the first data symbol. A second data symbol that includes a retransmitted kth data bit is received. A second channel quality parameter for the second data symbol is estimated. A probable value of the kth data bit is determined based on both the first channel quality parameter and the second channel quality parameter. In response to an ARQ for data symbols communicated over a multicarrier system, the following are performed: determining channel quality parameters, each of the channel quality parameters corresponding to at least one of the transmitted data symbols; selecting a subset of the channel quality parameters exhibiting a worst quality; constructing a block of data symbols corresponding to the subset; and communicating the block of data symbols over a plurality of subcarriers.

Abstract: A transmitter operates to increase a diversity order of a multi-carrier frequency division multiplex (MC-FDM) system. The transmitter has at least two transmit antennas and circuitry to provide at least two of the MC system frequency sub-carriers to different ones of the at least two transmit antennas.

Abstract: A generalized zigzag code is described where the code segments (each including one parity bit and information bits) of a block are not necessarily of uniform length. For coding rates in which the average code segment length is not an integer, all code segment lengths may be identical. The number of code segments depends on the coding rate and number of information bits in a block. At the encoder, parity bits are added to each string of information bits in a block to yield the code segments. For a punctured code, concatenated or not, the encoder may remove or not generate the punctured parity bits. At a decoder that operates at a rate different from the code rate of a received block, null parity bits are inserted. The received block has a number of code segments. The decoder increases the number of code segments by the addition of null parity bits, thereby reducing the coding rate to the rate of the decoder. Methods and apparatuses are detailed.

Abstract: A multi-level space time signal constellation that is optimized for use with a multi-carrier, multi-path communication scheme includes points on a first level separated from points on a mutually exclusive second level by a minimum distance that is based on a conditional probability distribution, preferably a Kullback-Leibler (KL) distance. Points within one level may be separated by a Euclidean distance, but spherical levels are rotated relative to one another to maximize a minimum inter-level KL distance. A receiver uses pilot symbols to estimate the channels and two-stage symbol detection, determining in one stage the constellation level and in another stage the point in the level. The receiver calculates a likelihood function based on a conditional distribution which does not reduce to the Euclidean-based nearest-neighbor detector. A single stored constellation may be scaled based on received signal to noise ratio.

Abstract: A apparatus and method for improved performance in radio telecommunications systems, and in particular multi-carrier code division multiple access (MC-CDMA) networks that employ pulse-shaping filters on the transmit side of a radio link. In order to more accurately transmit a radio signal bearing a symbol sequence, the modulated and spread information stream is upsampled using a technique that involves inserting zeros in the frequency domain. A corresponding downsampling procedure on the receive side permits reconstruction of the transmitted symbols. A new channel estimation algorithm may also be used, and the improved channel estimation advantageously employed to obtain more faithful symbol detection.

Abstract: A signal constellation for wireline or wireless multi-carrier communication systems, such as systems using OFDM or MC-CDMA, has points separated from one another by maximizing a distance between conditional probability distributions, such as a Kullbeck-Leibler (KL) distance. Preferably, the constellation points are arranged in concentric circles, with or without a point at the origin, wherein adjacent circles are rotated to maximize an angular distance between points on adjacent circles. Pilot symbols inserted in the transmitted signal are used by a receiver to estimate the channel of the multi-carrier system. Different constellations show optimum performance for different signal to noise ratios, and for different numbers of taps used to estimate the channel, especially in a fast fading environment where there may be fewer pilots per OFDM or MC-CDMA symbol than channel taps.

Abstract: A signal constellation for a multiple input/multiple output (MIMO) communication system when channel knowledge at the receiver is imperfect includes at least two (n−1)-dimensional sub-constellations of points that together form an n-dimensional constellation, the number n representing real dimensions and n=2M where M is the number of transmit antennas. The n-dimensional spherical constellation may define a single sphere or a plurality of concentric subset spheres, and points between subsets are separated by a Kullback-Leibler distance rather than a Euclidian distance. Each sphere has sub-constellations that preferably are arranged in symmetric pairs that define equal numbers of points that lie in parallel planes, to allow recursive construction that minimizes computational complexity. An appropriate constellation may be chosen by ceasing a search once the optimum minimum distance stops increasing as a number of the concentric levels increases.

Abstract: A system and method for the efficient transmission of information in a code division multiple access (CDMA) wireless telecommunication system. To increase the rate of reliable transmission, an orthogonal frequency-division multiplexing (OFDM) scheme is implemented in a direct-spread CDMA network, this combination sometimes being referred to as multi-carrier CDMA (MC-CDMA). Information (such as voice and data), interspersed with a known pilot signal, is encoded and spread across the frequency domain, rather than the time domain as in traditional CDMA; the allowable transmission bandwidth is divided into a number of carriers. To achieve even larger transmission rates, the guardband between carriers is eliminated. To prevent interference, the number of pilot transmissions is reduced and a corresponding number of frequency bins at the border of an OFDM block are loaded with zeros. The receiver simply ignores these subcarriers when reconstructing the transmitted signal.

Abstract: A hybrid receiver, and an associated method, for receiving a radio signal carrying transmitted data that is subject to distortion in the transmission channel. The receiver includes a plurality of stages that perform parallel interference cancellation (PIC) to establish successively more accurate estimates of the transmitted data, including a receiver first stage being either a RAKE receiver or a linear minimum mean-square error (LMMSE) receiver, a second stage including an LMMSE, and preferably a third stage also including an LMMSE. Each stage processes the estimates of the transmitted signal provided by the stage preceding it to mitigate or eliminate as much transmission-channel interference as possible and prove a refined estimate for processing by subsequent stages. Improved channel estimation may be achieved by processing the pilot signal in similar fashion as well.

Abstract: A receiver, a system, and an associated method, for receiving a radio signal carrying transmitted data that is subject to distortion in the transmission channel. The receiver includes a plurality of stages that perform parallel interference cancellation (PIC) with respect to a received space-time transmit diversity (STTD) signal to establish successively more accurate estimates of the transmitted data, including a receiver first stage being a RAKE-STTD receiver, a second stage including an minimum mean-square error (LMMSE) equalizer, and preferably a third stage also including an LMMSE. Each stage processes the estimates of the transmitted signal provided by the stage preceding it, as well as the received signal, to mitigate or eliminate as much transmission-channel interference as possible and prove a refined estimate for processing by subsequent stages. Improved channel estimation may be achieved by processing the pilot signal in similar fashion as well.

Abstract: A system and method for the efficient transmission of information in a code division multiple access (CDMA) wireless telecommunication system. The rate of reliable transmission is increased by implementing an orthogonal frequency-division multiplexing (OFDM) scheme in, for example, a direct-spread CDMA network, resulting in a multi-carrier CDMA (MC-CDMA) system. Information (such as voice and data), is encoded, divided, and spread across the frequency domain, rather than in the time domain as in traditional CDMA; the allowable transmission bandwidth is divided into a number of carriers. Using this scheme, a number of loading parameters such as code rate, data rate, and the number of streams into which the encoded data is divided may be varied to increase the performance of the system. Application of the variable loading parameter may be a function of channel quality, such as the presence of noise or the channel fading state.

Abstract: Apparatus, and an associated method, for a multiple-input, multiple-output communication system having M transmit antennas and N receive antennas. Apparatus is provided for the receiving station including processing elements permitting joint interference cancellation and prefiltering of data received at the receiving station. Additional joint encoding apparatus is provided for a sending station of the MIMO communication system together with corresponding decoding apparatus of the receiving station.

Abstract: A cellular communications system includes a plurality of mobile stations located within at least one cell; a base transceiver station (BTS) for servicing the cell; a base station controller (BSC) coupled to the BTS; and a Call Admission processor coupled to the BTS for receiving a call admission request from mobile stations located in the cell served by the BTS. The processor, which could be co-located with the BSC, grants cellular communications system resources to mobile stations based at least in part on a level of service required by the mobile stations and on a location of the mobile stations within the cell. For a mobile station having a high bandwidth requirement and that is determined to be located at the edge of the cell, the mobile station is preferentially granted system resources by being assigned a plurality of time slots per frame for forming one radio information block, and is operated with a non-convolutional modulation format and with turbo channel coding.

Abstract: A method and system of improving quality of service in a communication system is provided. The method includes the step of encoding a data set multiple times in a communication transmitter with the same or different error codes to form a plurality of encoded data sets. Each of the encoded data sets is then parallel or serial transmitted to a designated receiver. In addition, each of the encoded data sets may be adapted to an optimized burst structure for use in a TDMA system, CDMA system, or combination system thereof.

Abstract: A method and apparatus for decoding TCM signals including simplified polar computations and Viterbi decoding. The method includes converting the received signal from Cartesian to polar coordinates in order to provide a reduction in the number and complexity of the associated calculations. The branch metric computation for the Viterbi decoding algorithm is performed using polar samples of the demodulated signal.