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Multi-user multiple input and multiple output (MU-MIMO) is one of the key techniques in 3GPP Long-Term Evolution (LTE), which enhances the overall system capacity in the downlink. In order to reduce the effect of inter-user-interference in this system, it is necessary to utilize an efficient detection method at the user equipment (UE) that besides its feasibility at high data rate transmission systems...
This paper examines a type of linear beamforming for communications in interference networks. First, a receiver beamformer design is derived from a Maximum Likelihood (ML) framework with Automatic Gain Control (AGC) constraints. The studied beamformer keeps the complexity of the receiver low and it is able either to remove full coherent arrivals or to enhance them when required when different AGC...
The problem of MIMO communications with imperfect channel knowledge at the receiver is considered. Imperfect channel knowledge results from errors due to noise and errors due to time variations which cause the channel estimates to become outdated. A receiver structure named the Unified Generalized Likelihood Ratio Detector (UGLRD) is presented. The UGLRD is based on joint symbol-channel estimation,...
This paper presents a prototype of a high-throughput 4 × 4 64-QAM MIMO receiver consisting of a channel matrix QR decomposition, a soft-output K-Best MIMO detector and a Convolutional Turbo Code decoder. The proposed MIMO receiver provides low processing latency and a pipelined architecture scalable to a larger number of antennas and constellation order. Therefore, it is suitable for LTE-Advanced...
Lattice reduction is a promising technique to enhance the performance of sub-optimal MIMO detectors. This paper presents the Bounded Block Parallel Lattice Reduction (BBP-LR) algorithm, which is an implementation friendly low complexity algorithm specifically optimized for practical MIMO-OFDM systems. The optimisation of the BBP-LR algorithm is based on the following: 1) exploiting the frequency coherence...
In this paper, we have proposed the signal separation and equalization schemes for MFSK signals using FDE (Frequency Domain equalization) with CP (Cyclic Prefix) and the MLD (Maximum Likelihood Detection) with ZP (Zero Padding) on quasi-static MIMO frequency selective channels. Through computer simulations, we have verified that the MLD with ZP exhibits the better BER characteristics than the conventional...
A baseband multi-input, multi-output (MIMO) multi-carrier code division multiple access (MC-CDMA) downlink system meeting wideband CDMA (WCDMA) bandwidth requirements is simulated and its receiver part is implemented into a field programmable gate array (FPGA). The receiver was designed by integrating an existing single-input, single-output (SISO) fixed-point MC-CDMA receiver with an existing floating-point...
A Noisy Independent Component Analysis (ICA) based method for detection in the compound system MIMO-OFDM and in the context of CDMA is proposed. Noisy-ICA algorithm is used as a post processor attached to a subspace based CDMA receiver in the presence of Gaussian noise. The proposed architecture of the detector reduces the bias caused by the channel noise and further decreases the noise by dimensionality...
In this paper, the rate achievable in Multiple-Input-Multiple-Output (MIMO) systems with iterative receivers based on linear front-end (FE) processing is investigated. First, the communication with Gaussian input signal is assumed and the Extrinsic Information Transfer (EXIT) chart is applied to evaluate the achievable sum rate. Then, the method for deriving the EXIT chart for a more practical case...
This paper presents a new space-time two-stage receiver with the assistance of soft information for the Alamouti space-time block code (STBC) and spatially multiplexing (SM) combined systems. The first stage of the receiver consists of a set of soft generalized sidelobe canceller (GSC)-based detectors, each for every STBC group and is intended to yield a more precise initial estimate of the transmitted...
In this work we propose novel decision feedback (DF) detection algorithms with error propagation mitigation capabilities for multi-input multi-output (MIMO) spatial multiplexing systems based on multiple processing branches. The novel strategies for detection exploit different patterns, orderings and constraints for the design of the feedforward and feedback filters. We present constrained minimum...
We consider turbo-coded MIMO systems with Rayleigh fading, when channel state information is available at the receiver only. Using our recently proposed linearly complex MIMO signal detector, we derive two bit-error-rate bounds on performance for such systems by extending the union bound method from turbo codes on the AWGN channel to time-varying MIMO fading channels. These bounds allow a designer...
This document describes the design of received signal strength indicators (RSSI) for RF-MIMO systems. It covers considerations of system level aspects such as dynamic range and the suiting location of the RSSI and presents the implementation of a fully integrated RSSI circuit for 802.11a compliant diversity receivers. Drawing a total current of 6.1 mA from a 3.3 V supply, this circuit provides a dynamic...
We consider the problem of maximum likelihood (ML) signal detection in multiple-input multiple-output (MIMO) wireless communication systems. We propose a new preprocessing algorithm in the form of channel ordering for sphere decoders. Numerical results show that this new channel ordering leads to significantly lower complexity (in the form of the number of nodes visited by the search algorithm); for...
This paper introduces a new framework of the multiple-input multiple-output (MIMO) detection in iterative receivers. Unlike the conventional methods processing with symbol lattice, we consider the delta symbol lattice, i.e., the difference between two arbitrary points in the symbol lattice. The inherent flexible, symmetric, and sparse properties of the delta lattice enhance the detection in both complexity...
In classical non-iterative MIMO detection a soft-output MIMO detector computes likelihoods of the transmit bits being 1 or 0, given the received symbol vector. In iterative MIMO detection-decoding, detection performance is improved by exploiting apriori information about bit probabilities from the decoder. Transmit bits are viewed as random variables and the optimum detector performs Bayesian updating...
The Golden code has been proposed as an optimal space-time code for multiple-input multiple-output (MIMO) communication systems. This paper considers a ??blind?? MIMO system where the channel is assumed to be unknown. The Golden code is unidentifiable under this condition and can not be used directly. A block code modification is described which makes the Golden code usable in the context of blind...
In this paper we propose novel multistage receivers based on multiple parallel branches successive interference cancellation (MB-SIC) for the uplink of multiple-input multiple-output code-division multiple-access (MIMO-CDMA) systems. The proposed multistage receivers exploit a conventional ordered SIC for the first stage, followed by a grouping detection strategy and the novel MB-SIC scheme. The grouping...
In this paper we propose an adaptive successive interference cancellation (SIC) strategy for multiple-input multiple-output (MIMO) spatial multiplexing systems based on multiple interference cancellation branches. The proposed detection structure employs SICs on several parallel branches which are equipped with different ordering patterns so that each branch produces a vector of estimate symbols by...
In this work, we investigate a two-user multiple-antenna cooperative coding scheme for quasi-static fading channels based on the matrix-Alamouti method. At the destination, the two-users symbols are first decoupled, then fed to an iterative receiver that removes the remaining interference and decodes the information. Different interference cancellation scenarios are investigated. We propose a low-complexity...
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