scholarly journals A Bit-Interleaved Sigma-Delta-Over-Fiber Fronthaul Network for Frequency-Synchronous Distributed Antenna Systems

2021 ◽  
Vol 11 (23) ◽  
pp. 11471
Author(s):  
Chia-Yi Wu ◽  
Haolin Li ◽  
Joris Van Kerrebrouck ◽  
Caro Meysmans ◽  
Piet Demeester ◽  
...  
Keyword(s):  
Spectral Efficiency ◽  
Performance Indicator ◽  
Multiple Input Multiple Output ◽  
Sigma Delta ◽  
Distributed Antenna Systems ◽  
Distributed Antenna ◽  
Multiple Input ◽  
Input Multiple Output ◽  
Time Interleaved ◽  
Antenna Systems

Cell-free massive multiple-input multiple-output (MIMO) has attracted wide attention as wireless spectral efficiency has become a 6G key performance indicator. The distributed scheme improves the spectral efficiency and user fairness, but the fronthaul network must evolve to enable it. This work demonstrates a fronthaul network for distributed antenna systems enabled by the bit-interleaved sigma-delta-over-fiber (BISDoF) concept: multiple sigma-delta modulated baseband signals are time-interleaved into one non-return-to-zero (NRZ) signal, which is converted to the optical domain by a commercial QSFP and transmitted over fiber. The BISDoF concept improves the optical bit-rate efficiency while keeping the remote unit complexity sufficiently low. The implementation successfully deals with an essential challenge—precise frequency synchronization of different remote units. Moreover, owing to the straightforward data paths, all transceivers inherently transmit or receive with fixed timing offsets which can be easily calibrated. The error vector magnitudes of both the downlink and uplink data paths are less than 2.8% (–31 dB) when transmitting 40.96 MHz-bandwidth OFDM signals (256-QAM) centered around 3.6 GHz. (Optical path: 100 m multi-mode fibers; wireless path: electrical back-to-back.) Without providing an extra reference clock, the two remote units were observed to have the same carrier frequency; the standard deviation of the relative jitter was 9.43 ps.

scholarly journals An Evaluation of Successive Pilot Decontamination in Massive MIMO

2018 ◽  
Vol 39 (2) ◽  
pp. 107
Author(s):  
Victor Croisfelt Rodrigues ◽  
Taufik Abrão
Keyword(s):  
Spectral Efficiency ◽  
Massive Mimo ◽  
Mimo Systems ◽  
Multiple Input Multiple Output ◽  
Pilot Training ◽  
Pilot Contamination ◽  
Fundamental Issue ◽  
Data Rates ◽  
Multiple Input ◽  
Input Multiple Output

The demand for higher data rates can be satisfied by the spectral efficiency (SE) improvement offered by Massive multiple-input multiple-output (M-MIMO) systems. However, the pilot contamination remains as a fundamental issue to obtain the paramount SE in such systems. This propitiated the research of several methods to mitigate pilot contamination. One of these procedures is based on the coordination of the cells, culminating in proposals with multiple pilot training phases. This paper aims to expand the results of the original paper, whereby the concepts of large pilot training phases were offered. The evaluation of such method was conducted through more comprehensible numerical results, in which a large number of antennas were assumed and more rigorous SE expressions were used. The channel estimation approaches relying on multiple pilot training phases were considered cumbersome for implementation and an uninteresting solution to overcome pilot contamination; contradicting the results presented in the genuine paper.

scholarly journals Spectral Efficiency Improvement Techniques In Massive Mimo For 5G Communications

2021 ◽  
Vol 12 (2) ◽  
pp. 1457-1465
Author(s):  
Naraiah R , Et. al.
Keyword(s):  
Spectral Efficiency ◽  
Mimo Systems ◽  
Multiple Input Multiple Output ◽  
Broad Band ◽  
Cell System ◽  
Base Station ◽  
Information Rate ◽  
Multiple Input ◽  
Input Multiple Output ◽  
Long Time

Wireless communications has gotten one of the quickest developing zones in our advanced life and makes colossal effect on practically every component of our day by day life. 5G should support a large number of new applications with a wide assortment of prerequisites, including higher pinnacle and client information rates, diminished dormancy, improved indoor inclusion, expanded number of gadgets, etc. The normal traffic development in at least a long time from now can be fulfilled by the consolidated utilization of more range, higher spectral efficiency, and densification of cells. The increment in spectral effectiveness will improve the throughput of the system which straightforwardly serves the Enhanced Mobile Broad band use instance of the 5G assistance. In massive Multiple-Input Multiple-Output (M-MIMO) systems few hundred quantities of antennas are conveyed at each base station (BS) to serve a moderately modest number of single-reception apparatus terminals with multiuser, giving higher information rate and lower idleness. Massive Multiple-Input Multiple-Output is the arising innovation in cell system for higher information rate correspondence. It utilizes enormous number of communicating reception apparatus at the base station which is made conceivable by the radio wire cluster which can be electronically steerable and adequately utilized for shaft framing. Spectral proficiency is the vital boundary to be improved in expanding throughput. The system execution under different commonsense limitations and conditions, for example, restricted soundness block length, number of base station (BS) antennas, and number of dynamic clients are assessed through simulation.  

scholarly journals Impact of Scheduling Algorithms for QoS Improvement in LTE Networks

2019 ◽  
Vol 8 (12) ◽  
pp. 5198-5202
Keyword(s):  
Spectral Efficiency ◽  
Multiple Input Multiple Output ◽  
Maximum Throughput ◽  
Lte Networks ◽  
Design Metrics ◽  
Capacity Enhancement ◽  
Multiple Input ◽  
Universal Mobile Telecommunications System ◽  
Input Multiple Output ◽  
4G Lte

Spectral efficiency and delay are important design metrics that should be taken into consideration while designing a LTE/LTE-A network. Various factors effect these metrics in various ways. In this paper we will be analyzing spectral efficiency vs number of users and delay vs number of users in a 4G LTE network. Additionally, we will be analyzing effect of different scheduling types on delay and throughput of the network. The scheduling types we compare are maximum throughput, proportional fair and round robin. We will conclude on a scheduling type that gives us the least delay and maximum throughput. In view of the Universal Mobile Telecommunications System (UMTS) Long Term Evolution (LTE) technology, this paper considers multiple input multiple output (MIMO) capacity enhancement.

scholarly journals Τεχνοοικονομική διαχείριση κινητών δικτύων πέμπτης γεννιάς (5G) και εξής

2021 ◽  
Author(s):  
Anastasia Κόλλια. Αναστασία
Keyword(s):  
Cloud Computing ◽  
Cognitive Radio ◽  
Massive Mimo ◽  
Multiple Input Multiple Output ◽  
Network Function Virtualization ◽  
Software Defined Networks ◽  
Network Function ◽  
Multiple Input ◽  
Input Multiple Output ◽  
Antenna Systems

Σήμερα, η χρήση κινητών δικτύων αποτελεί αναπόσπαστο κομμάτι της καθημερινότητας. Οι χρήστες χρησιμοποιούν το κινητό τόσο για κλήσεις και μηνύματα όσο και για κοινωνικά δίκτυα, βίντεο, ταινίες, εφαρμογές ασκήσεις και φυσικής κατάστασης, παιχνίδια, εφαρμογές γραφείου, ημερολόγια κλπ. Η χρηστικότητα των συσκευών όχι μόνο έχει αλλάξει άρδην τα τελευταία χρόνια, αλλά αναμένεται να μεταβληθεί ακόμα περισσότερο ιδίως όταν εφαρμογές Internet of Things (IoT) προστεθούν στην ήδη διευρυμένη χρήση των κινητών συσκευών. Ακόμα, εμφανίζεται η τάση προσθήκης στο δίκτυο άλλων απλών οικιακών συσκευών και άλλου επιπρόσθετου εξοπλισμού π.χ. ιατρικών μικροσυσκευών, συσκευών παρακολούθησης, καμερών ασφαλείας κλπ. Η διδακτορική αυτή διατριβή αποτελεί μία συνολική μελέτη και περιλαμβάνει ένα πλαίσιο σχετικά με την πέμπτη γενιά κινητής τηλεπικοινωνίας. Αναλύεται η κατάσταση των Τηλεπικοινωνιών στην Ελλάδα σε βάθος. Ακόμα, περιγράφονται οι σημαντικότερες έννοιες και τα πιο βασικά βήματα και οι σημαντικότερες εξελίξεις των υπαρχουσών γενεών κινητών δικτύων επικοινωνίας. Επιπρόσθετα, περιγράφεται το θεωρητικό πλαίσιο για τα κινητά δίκτυα επικοινωνίας, καθώς και διάφοροι όροι, που είναι απαραίτητοι για την κατανόηση της παρούσας διατριβής. Αναλύονται διεξοδικά οι σημαντικότερες τεχνολογίες, που αποτελούν δομικούς λίθους για την ανάπτυξη, αλλά και την εξέλιξη στη δόμηση και ύπαρξη της 5G γενιάς κινητής τηλεπικοινωνίας, όπως έχει ήδη περιγραφεί από πλήθος ερευνητικών δράσεων και περιλαμβάνουν τις τεχνολογίες: Υπέρπυκνες Αρχιτεκτονικές (Ultra-dense), Distributed Antenna Systems (DAS), Network Function Virtualization (NFV), Software Defined Networks (SDN), Massive Multiple Input Multiple Output (MIMO), Cognitive Radio (CR), Milimeter Wave (mmWave), Cloud Computing και IoT και σύγκριση με τις σημερινές τεχνολογίες. Παρατίθενται τεχνο-οικονομικά μοντέλα, με βάση τις πιο σημαντικές τεχνολογίες, που συντελούν στην ανάπτυξη και προώθηση της 5G. Τα μοντέλα αυτά αποτελούν σημαντικό όπλο, ώστε οι πάροχοι να επενδύσουν σε νέες τεχνολογίες, να έχουν κέρδη και να καινοτομούν. Για το σκοπό αυτό επεξηγούνται τα αρχιτεκτονικά μοντέλα, τα μαθηματικά μοντέλα, οι παράμετροι, που επιλέγονται αλλά και τα αντίστοιχα πειράματα, που διεξάγονται για τις τεχνολογίες Ultra-density, DAS, NFV, SDN, Massive MIMO, CR, mmWave. Συνοψίζονται τα κυριότερα συμπεράσματα βάση των επιμέρους μελετών, που πραγματοποιήθηκαν στα πλαίσια της παρούσας διατριβής και προτείνονται ιδέες για μελλοντική έρευνα στον τομέα. Στα πλαίσια αυτά φιλοδοξείται ότι η συγκεκριμένη εργασία θα αποτελέσει ένα βασικό εργαλείο πληροφόρησης και ενημέρωσης για την επιστημονική και τηλεπικοινωνιακή κοινότητα σε ό,τι αναφορά στην τεχνο-οικονομική ανάλυση των τεχνολογιών, που αποτελούν τους θεμέλιους λίθους για τα δίκτυα Πέμπτης γενιάς.

Adaptive MIMO Systems with High Spectral Efficiency

2009 ◽  
pp. 286-307 ◽  
Author(s):  
Zhendong Zhou ◽  
Branka Vucetic
Keyword(s):  
Spectral Efficiency ◽  
Adaptive System ◽  
Mimo Systems ◽  
Mimo System ◽  
Adaptive Modulation ◽  
Multiple Input Multiple Output ◽  
Adaptive Modulation And Coding ◽  
Multiple Input ◽  
High Spectral Efficiency ◽  
Input Multiple Output

This chapter introduces the adaptive modulation and coding (AMC) as a practical means of approaching the high spectral efficiency theoretically promised by multiple-input multiple-output (MIMO) systems. It investigates the AMC MIMO systems in a generic framework and gives a quantitative analysis of the multiplexing gain of these systems. The effects of imperfect channel state information (CSI) on the AMC MIMO systems are pointed out. In the context of imperfect CSI, a design of robust near-capacity AMC MIMO system is proposed and its good performance is verified by simulation results. The proposed adaptive system is compared with the non-adaptive MIMO system, which shows the adaptive system approaches the channel capacity closer.

Sign in / Sign up

Export Citation Format

Share Document