Patent•
Wireless communication apparatus using fast fourier transforms to create, optimize and incorporate a beam space antenna array in an orthogonal frequency division multiplexing receiver
12 Nov 2008-
TL;DR: In this paper, the beam space antenna array is implemented with a Butler matrix array, and the antenna array may be a circular array, vertical array, or a combination of both circular and vertical arrays.
Abstract: A wireless communication apparatus which uses fast Fourier transforms (FFTs) in an orthogonal frequency division multiplexing (OFDM) receiver which incorporates a beam space antenna array. The beam space antenna array may be implemented with a Butler matrix array. The beam space antenna array may be a circular array, vertical array, or a combination of both circular and vertical arrays, for providing the desired angular antenna coverage. In one embodiment, the antenna array is optimized because the FFTs are linear invariant transform operators, whereby the order of operations in the OFDM receiver can be interchanged.
Citations
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Patent•
20 Jul 2007
TL;DR: In this article, the receiver evaluates a decoding metric using each possible value of the transmitted signal vector to produce a set of distances, and then combines distances from across the received signal vectors to produce the combined distance associated with each value.
Abstract: Systems and methods are provided for decoding signal vectors in multiple-input multiple-output (MIMO) systems, where the receiver has received one or more signal vectors from the same transmitted vector. For each received signal vector, the receiver evaluates a decoding metric using each possible value of the transmitted signal vector to produce a set of distances. The receiver then combines distances from across the received signal vectors to produce a combined distance associated with each possible value of the transmitted signal vector. Using the combined distances, the receiver may choose among the possible values of the transmit signal vector to determine the actual transmit signal vector.
41 citations
Patent•
12 Sep 2007
TL;DR: In this paper, a decoding scheme for decoding a signal vector in a transmission scheme that uses transmit diversity as well as HARQ, repetition coding, or any other protocol that allows a receiver to obtain multiple reception of common transmit information is described.
Abstract: Systems and methods are provided for decoding a signal vector in a transmission scheme that uses transmit diversity as well as HARQ, repetition coding, or any other protocol that allows a receiver to obtain multiple reception of common transmit information. Information obtained in more than one symbol period are treated as a single received vector, and each of the received signal vectors may be processed to reduce or remove phase rotations caused by the channel. The received signal vectors may be combined by addition and decoded using a maximum-likelihood decoder. In some embodiments, the transmitter and receiver are configured to communicate using the transmit diversity scheme and a spatial multiplexing scheme. The scheme may be chosen based on the quality of the channel through which communication takes place.
31 citations
Patent•
15 Jun 2015
TL;DR: In this article, a wireless network device includes an antenna array and a lobe interleaver, which divides and interleaves the radio signal of the antenna array with the same phase and the same power to generate a plurality of lobes with different squint angles.
Abstract: A wireless network device includes an antenna array and a lobe interleaver. The antenna array includes a plurality of antenna elements with different squint angles. The lobe interleaver is coupled to the antenna elements and has a plurality of output lobe ports. The lobe interleaver divides and interleaves the radio signal of the antenna array with the same phase and the same power to generate a plurality of lobes with different squint angles. The number of lobes is twice the number of antenna elements.
30 citations
Patent•
13 Nov 2009TL;DR: In this article, the spectral density estimates are then combined, and the signal features are sensed based on the combination of the spectral densities estimates, where each estimate is derived based on reception of the signal by a respective antenna in a system with multiple sensing antennas.
Abstract: Methods and apparatus for sensing features of a signal in a wireless communication system are disclosed The disclosed methods and apparatus sense signal features by determining a number of spectral density estimates, where each estimate is derived based on reception of the signal by a respective antenna in a system with multiple sensing antennas The spectral density estimates are then combined, and the signal features are sensed based on the combination of the spectral density estimates
29 citations
Patent•
15 Aug 2007TL;DR: In this paper, a concatenated signal vector with a previously processed signal vector is decoded using a maximum-likelihood (ML) decoder, where the ML decoder can use the channel response matrix associated with the current signal vector and a processed version of previous channel response matrices.
Abstract: Systems and methods are provided for decoding signal vectors in multiple-input multiple-output (MIMO) systems, where a receiver has received one or more signal vectors from the same transmitted vector. The receiver processes these received signal vectors one by one, and uses information from signal vectors that have already been processed to process the next signal vector. To process a current signal vector, the receiver concatenates the current signal vector with a previously processed signal vector. This concatenated signal vector is decoded using, for example, a maximum-likelihood (ML). To decode the concatenated signal vector, the ML decoder can use a concatenated channel matrix that includes a channel response matrix associated with the current signal vector and a processed version of previous channel response matrices.
26 citations
References
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TL;DR: This paper addresses digital communication in a Rayleigh fading environment when the channel characteristic is unknown at the transmitter but is known (tracked) at the receiver with the aim of leveraging the already highly developed 1-D codec technology.
Abstract: This paper addresses digital communication in a Rayleigh fading environment when the channel characteristic is unknown at the transmitter but is known (tracked) at the receiver. Inventing a codec architecture that can realize a significant portion of the great capacity promised by information theory is essential to a standout long-term position in highly competitive arenas like fixed and indoor wireless. Use (n T , n R ) to express the number of antenna elements at the transmitter and receiver. An (n, n) analysis shows that despite the n received waves interfering randomly, capacity grows linearly with n and is enormous. With n = 8 at 1% outage and 21-dB average SNR at each receiving element, 42 b/s/Hz is achieved. The capacity is more than 40 times that of a (1, 1) system at the same total radiated transmitter power and bandwidth. Moreover, in some applications, n could be much larger than 8. In striving for significant fractions of such huge capacities, the question arises: Can one construct an (n, n) system whose capacity scales linearly with n, using as building blocks n separately coded one-dimensional (1-D) subsystems of equal capacity? With the aim of leveraging the already highly developed 1-D codec technology, this paper reports just such an invention. In this new architecture, signals are layered in space and time as suggested by a tight capacity bound.
6,812 citations
29 Sep 1998
TL;DR: This paper describes a wireless communication architecture known as vertical BLAST (Bell Laboratories Layered Space-Time) or V-BLAST, which has been implemented in real-time in the laboratory and demonstrated spectral efficiencies of 20-40 bps/Hz in an indoor propagation environment at realistic SNRs and error rates.
Abstract: Information theory research has shown that the rich-scattering wireless channel is capable of enormous theoretical capacities if the multipath is properly exploited In this paper, we describe a wireless communication architecture known as vertical BLAST (Bell Laboratories Layered Space-Time) or V-BLAST, which has been implemented in real-time in the laboratory Using our laboratory prototype, we have demonstrated spectral efficiencies of 20-40 bps/Hz in an indoor propagation environment at realistic SNRs and error rates To the best of our knowledge, wireless spectral efficiencies of this magnitude are unprecedented and are furthermore unattainable using traditional techniques
3,925 citations
TL;DR: Using this joint space-time approach, spectral efficiencies ranging from 20-40 bit/s/Hz have been demonstrated in the laboratory under flat fading conditions at indoor fading rates.
Abstract: The signal detection algorithm of the vertical BLAST (Bell Laboratories Layered Space-Time) wireless communications architecture is briefly described. Using this joint space-time approach, spectral efficiencies ranging from 20-40 bit/s/Hz have been demonstrated in the laboratory under flat fading conditions at indoor fading rates. Early results are presented.
1,791 citations
TL;DR: Four suboptimum detection techniques based on zero forcing and minimum mean-square-error equalization with and without decision feedback (DF) are presented and compared and it is shown that the performance of the MMSE equalizers is better than that of the corresponding ZF equalizers.
Abstract: In code-division multiple-access (CDMA) systems transmitting over time-varying multipath channels, both intersymbol interference (ISI) and multiple-access interference (MAI) arise. The conventional suboptimum receiver consisting of a bank of matched filters is often inefficient because interference is treated as noise. The optimum multiuser detector is too complex to be implemented at present. Four suboptimum detection techniques based on zero forcing (ZF) and minimum mean-square-error (MMSE) equalization with and without decision feedback (DF) are presented and compared. They combat both ISI and MAI. The computational complexity of all four equalizers is essentially the same. All four equalizers are independent of the size of the data symbol alphabet. It is shown that the performance of the MMSE equalizers is better than that of the corresponding ZF equalizers. Furthermore, the performance of the equalizers with DF is better than that of the corresponding equalizers without DF. The impairing effect of error propagation on the equalizers with DF is reduced by channel sorting.
581 citations
Patent•
AT&T1
TL;DR: In this article, the authors proposed a high quality PCS communications method that combines a form of time division duplex (TDD), FDD, time division multiple access (TDMA), orthogonal frequency division multiplexing (OFDM), spatial diversity, and polarization diversity in various unique combinations.
Abstract: The high quality PCS communications are enabled in environments where adjacent PCS service bands operate with out-of-band harmonics that would otherwise interfere with the system's operation. The highly bandwidth-efficient communications method combines a form of time division duplex (TDD), frequency division duplex (FDD), time division multiple access (TDMA), orthogonal frequency division multiplexing (OFDM), spatial diversity, and polarization diversity in various unique combinations. The method provides excellent fade resistance. The method enables changing a user's available bandwidth on demand by assigning additional TDMA slots during the user's session.
482 citations