scholarly journals Fully Pipelined Implementation of Tree-Search Algorithms for Vector Precoding

2013 ◽  
Vol 2013 ◽  
pp. 1-12 ◽  
Author(s):  
Maitane Barrenechea ◽  
Mikel Mendicute ◽  
Egoitz Arruti
Keyword(s):  
Data Processing ◽  
Hardware Implementation ◽  
Multiple Input Multiple Output ◽  
Search Algorithms ◽  
Search Problem ◽  
Tree Search ◽  
High Data ◽  
Field Programmable ◽  
Input Multiple Output ◽  
Downlink Channels

The nonlinear vector precoding (VP) technique has been proven to achieve close-to-capacity performance in multiuser multiple-input multiple-output (MIMO) downlink channels. The performance benefit with respect to its linear counterparts stems from the incorporation of a perturbation signal that reduces the power of the precoded signal. The computation of this perturbation element, which is known to belong in the class of NP-hard problems, is the main aspect that hinders the hardware implementation of VP systems. To this respect, several tree-search algorithms have been proposed for the closest-point lattice search problem in VP systems hitherto. Nevertheless, the optimality of these algorithms has been assessed mainly in terms of error-rate performance and computational complexity, leaving the hardware cost of their implementation an open issue. The parallel data-processing capabilities of field-programmable gate arrays (FPGA) and the loopless nature of the proposed tree-search algorithms have enabled an efficient hardware implementation of a VP system that provides a very high data-processing throughput.

scholarly journals Reduced Complexity Tree Search Algorithms for MIMO Decoding

2015 ◽  
Vol 10 (4) ◽  
pp. 230
Author(s):  
Gajanan R Patil ◽  
Vishwanath K Kokate
Keyword(s):  
Mimo Systems ◽  
Multiple Input Multiple Output ◽  
Search Algorithms ◽  
Error Rates ◽  
Sphere Decoding ◽  
Current Layer ◽  
Tree Search ◽  
Maximum Likelihood Decoding ◽  
Initial Radius ◽  
Input Multiple Output

Maximum Likelihood Decoding (MLD) is computationally complex technique for decoding received information in multiple input multiple output (MIMO) systems. Tree search algorithms such as sphere decoding (SD) and QR decomposition with M survivals (QRD-M) are used to reduce the complexity keeping the performance near ML. This paper presents two techniques for reducing the computational complexities of the tree search algorithms further. The first technique is based on selecting the initial radius for sphere decoding. The main contribution of this paper is that the greedy best first search is used to compute initial radius, instead of Babai estimate. The second contribution is, QRD-M algorithm is modified to prune the nodes in the current layer based on maximum metric of child nodes of smallest surviving node. The performance of the proposed techniques is tested for different MIMO systems in terms of bit error rates (BER) and average number of nodes visited. The proposed schemes have improved computational complexity with no degradation of performance.

scholarly journals MIMO Fading Emulator Development with FPGA and Its Application to Performance Evaluation of Mobile Radio Systems

2017 ◽  
Vol 2017 ◽  
pp. 1-15 ◽  
Author(s):  
Yoshio Karasawa ◽  
Katsuhiro Nakada ◽  
Guijiang Sun ◽  
Rikako Kotani
Keyword(s):  
Channel Model ◽  
Multiple Input Multiple Output ◽  
New Developments ◽  
Performance Limit ◽  
Stage Scheme ◽  
Mobile Radio Systems ◽  
Multiple Input ◽  
Field Programmable ◽  
Input Multiple Output ◽  
Radio Systems

We present four new developments for a multiple-input multiple-output (MIMO) over-the-air measurement system based on our previous studies. The first two developments relate to the channel model for multipath environment generation. One is a further simplification of the circuit configuration without performance degradation by reducing the number of delay generation units, which dominate the performance limit when implementing the circuit on a field-programmable gate array (FPGA). The other is to realize spatial correlation characteristics among the input ports on the transmission side, whereas the previously proposed channel model did not consider this correlation. The third development involves the details of implementing the MIMO fading emulator on an FPGA as a two-stage scheme. The fourth is the demonstration of application examples of the developed system.

Low-Complexity MIMO MMSE Receiver with Performance Enhancement via Coordinate Interleaving

2020 ◽  
Vol 29 (14) ◽  
pp. 2050231
Author(s):  
Serdar Özyurt ◽  
Mustafa Öztürk ◽  
Enver Çavuş
Keyword(s):  
Performance Enhancement ◽  
Minimum Mean Square Error ◽  
Multiple Input Multiple Output ◽  
Low Complexity ◽  
Complexity Reduction ◽  
Error Performance ◽  
Signal Space Diversity ◽  
Mmse Receiver ◽  
Field Programmable ◽  
Input Multiple Output

Multiple-input multiple-output (MIMO) Minimum mean-square error (MMSE) receivers are widely adopted in the latest communication standards and reducing the complexity of these receivers while preserving the error performance is highly desirable. In this work, we study the error performance and implementation complexity of MIMO MMSE receivers when combined with a coordinate interleaved signal space diversity (SSD) technique. Contrary to the well-known trade-off between the error performance and implementation complexity, the proposed system leads to a considerably simplified MIMO MMSE receiver with significant performance gains when compared to the original MIMO MMSE receiver. Unlike the standard MIMO MMSE receiver, the proposed coordinate interleaved technique induces a block diagonal transmit correlation matrix providing both performance enhancement and complexity reduction. The results show that the error performance can be improved more than 10[Formula: see text]dB with up to 71% computational complexity reduction. The complexity comparison between the original and proposed approaches is also verified by means of field-programmable gate array (FPGA) implementation.

scholarly journals 3D Multiple Input Multiple Output Large-Scale Antenna Systems

2020 ◽  
Vol 55 (6) ◽  
Author(s):  
Saif Saad Hameed ◽  
Fouad H. Awad ◽  
Adnan Yousif Dawod ◽  
Ayoob Abdulmunem Abdulhameed
Keyword(s):  
Large Scale ◽  
Random Noise ◽  
Multiple Input Multiple Output ◽  
Least Square ◽  
Noise Sources ◽  
Estimation Algorithms ◽  
High Data ◽  
Data Rates ◽  
Multiple Input ◽  
Input Multiple Output

The channel could be evaluated by utilizing several estimation algorithms. The various patterns of pilot arrangements for the channel appreciation are a huge problem in channel appreciation techniques since all the processes depends on it; this paper discusses improvements in channel selection. The Least Square and Least Square Mean methods are common, simple ways to begin to estimate a channel; however, they are less efficient than more complex approaches. Due to the boost in demand with high data rates in communications, developers continue to invent new methods and mechanisms to adjust the capacity and the accuracy of the communication network. One of the primary troubles in wireless communication is the communication channel, which is affected by nonlinear and random noise sources, which decrease the quality of the service on the network; in this case, the channel must be equalized to increase performance with minimal error. In this paper, a Massive Multiple Input Multiple Output was designed and simulated in order to estimate the channel and the performance of the network through using Least Square and Least Square Mean.

scholarly journals Low-Profile Two-Port MIMO Terminal Antenna for Low LTE Bands with Wideband Multimodal Excitation

2020 ◽  
Author(s):  
Hanieh Aliakbari ◽  
Buon Kiong Lau
Keyword(s):  
Electric Fields ◽  
Mobile Communications ◽  
Structural Changes ◽  
Multiple Input Multiple Output ◽  
Field Pattern ◽  
Characteristic Mode ◽  
High Data ◽  
Low Profile ◽  
Input Multiple Output ◽  
Terminal Antennas

<div>Multiple-input multiple-output (MIMO) is a key</div><div>enabler for high data rates in mobile communications. However, it is challenging to design MIMO terminal antennas for LTE bands below 1 GHz, due to the conventional chassis offering only one resonant characteristic mode (CM). Recently, it was shown that minor structural changes can yield up to two additional resonant modes for designing two-port MIMO antennas. Nonetheless, the resulting bandwidth for the second port is relatively small. To simultaneously meet bandwidth and other practical requirements (including low profile and no off-ground clearance), a step-by-step approach for structural changes and feed design is applied in this work to exemplify the use of physical insights from CM analysis to achieve a competitive wideband two-port solution. The main novelty is that an entirely new mode is identified and appropriately tuned by structural modification for creating an additional resonance below 1 GHz. Moreover, two simple probe-feed ports are designed to jointly excite different subsets of four modes over frequency. In addition, far-field pattern orthogonality is guaranteed by the different phase shifts of the characteristic electric fields at the port locations. Furthermore, bulkier self-resonant antenna elements are avoided. To show design flexibility, a three-port version is also demonstrated.</div>

Field Programmable Gate Array Based Testbed for Investigating Multiple Input Multiple Output Signal Transmission in Indoor Environments

2009 ◽  
pp. 474-499
Author(s):  
Konstanty Bialkowski ◽  
Adam Postula ◽  
Amin Abbosh ◽  
Marek Bialkowski
Keyword(s):  
Field Programmable Gate Array ◽  
Signal Transmission ◽  
Multiple Input Multiple Output ◽  
Indoor Environments ◽  
Front End ◽  
Rf Front End ◽  
Multiple Input ◽  
Field Programmable ◽  
Input Multiple Output ◽  
Gate Array

This chapter introduces the concept of Multiple Input Multiple Output (MIMO) wireless communication system and the necessity to use a testbed to evaluate its performance. A comprehensive review of different types of testbeds available in the literature is presented. Next, the design and development of a 2×2 MIMO testbed which uses in-house built antennas, commercially available RF chips for an RF front end and a Field Programmable Gate Array (FPGA) for based signal processing is described. The operation of the developed testbed is verified using a Channel Emulator. The testing is done for the case of a simple Alamouti QPSK based encoding and decoding scheme of baseband signals.

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