Bidirectional Wireless Telemetry for High Channel Count Optogenetic Microsystems

In the past few decades, there has been a significant progress in the development of wireless data transmission systems, from high data rate to ultra-low power applications, and from G-b per second to RFID systems. One specific area, in particular, is in wireless data transmission for implantable bio-medical applications. To understand how brain functions, neural scientists are in pursuit of high-channel count, high-density recordings for freely moving animals; yet wire tethering issue has put the mission on pause. Wireless data transmission can address this tethering problem, but there are still many challenges to be conquered. In this work, an ultra-low power ultra-wide band (UWB) transmitter with feedforward pulse generation scheme is proposed to resolve the long-existing problem in UWB transmitter. It provides a high-data rate capability to enable 1000 channels in broadband neural recording, assuming 10-bit resolution with a sampling rate of 20 kHz to accommodate both action potential (AP) and local field potential (LFP) recording, while remaining in ultra- low power consumption at 4.32 pJ/b. For the bi-directional communication between the wireless and recording/ stimulating module, a bit-wise time-division (B-TDD) duplex transceiver without cancellation scheme is presented. The receiver works at U-NII band (5.2GHz) and shares the same antenna with UWB transmitter. This significantly reduces the area consumption as well as power consumption for implantable systems. The system can support uplink at 200 Mbps for 1000 recording channels and downlink at 10 Mbps for 36 stimulation channels. With a 3.7 Volt 25mAh rechargeable battery, the system should be able to operate more than 1.5 hours straight for both recording and stimulation, assuming 1 LED channel with 100 µA, 10% duty-cycled stimulating current. The B-TDD transceiver is integrated with a dedicated recording/ stimulation optogenetic IC chip to demonstrate as a complete wireless system for implantable broadband optogenetic neural modulation and recording. The fully integrated system is less than 5 gram, which is suitable for rodent experiments.PHDElectrical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/155242/1/yujulin_1.pd

Optimized Full-Duplex Multi-Antenna Relay in Single-Input Single-Output Link

This thesis studies the performance evaluation and optimization of full-duplex multiple-input multiple-output (MIMO) relaying systems in single-input single-output (SISO) link, based on signal-to-interference-plus-noise ratio (SINR). Relays are transceivers which can improve the throughput of a system by coverage extension in a power-efficient manner, whereas full-duplex (FD) systems are point-to-point communication systems, in which transmission and reception occurs simultaneously on a single frequency band. Deploying relaying systems in the full-duplex mode, however, causes self-interference, because the signal transmitted from the transmitter side of the relay couples at its receiver side. This interference causes performance degradation in these systems. In this thesis, a one-way SISO communication link with a MIMO relay connecting the source and the destination nodes is studied. The relay is considered to be implementing either amplify-and-forward (AF) or decode-and-forward (DF) protocol. First, the end-to-end SINR of the system is derived. With the knowledge of SINR, numerical evaluation is made via computer simulations. The numerical results are reached by introducing different assumptions to the general system, as well as by keeping the system intact. Although the numerical solutions provide high performance, they require much time and computational power. Hence, this thesis offers some computationally efficient analytical solutions to the problem. For example, after setting the transmit filter of the relay, minimum mean square error (MMSE) method is applied on the first hop to optimize the system; or by assuming the relay self-interference channel is a rank-one matrix, a closed-form solution for the transmitter and receiver relay filters eliminating the self-interference is derived. Then, the performance of these methods are compared and discussed in different aspects; such as high SINR and computational requirement. The results indicate that each scheme has certain benefits over the others depending on the system design requirements

Full-duplex wireless communications: challenges, solutions and future research directions

The family of conventional half-duplex (HD) wireless systems relied on transmitting and receiving in different time-slots or frequency sub-bands. Hence the wireless research community aspires to conceive full-duplex (FD) operation for supporting concurrent transmission and reception in a single time/frequency channel, which would improve the attainable spectral efficiency by a factor of two. The main challenge encountered in implementing an FD wireless device is the large power difference between the self-interference (SI) imposed by the device’s own transmissions and the signal of interest received from a remote source. In this survey, we present a comprehensive list of the potential FD techniques and highlight their pros and cons. We classify the SI cancellation techniques into three categories, namely passive suppression, analog cancellation and digital cancellation, with the advantages and disadvantages of each technique compared. Specifically, we analyse the main impairments (e.g. phase noise, power amplifier nonlinearity as well as in-phase and quadrature-phase (I/Q) imbalance, etc.) that degrading the SI cancellation. We then discuss the FD based Media Access Control (MAC)-layer protocol design for the sake of addressing some of the critical issues, such as the problem of hidden terminals, the resultant end-to-end delay and the high packet loss ratio (PLR) due to network congestion. After elaborating on a variety of physical/MAC-layer techniques, we discuss potential solutions conceived for meeting the challenges imposed by the aforementioned techniques. Furthermore, we also discuss a range of critical issues related to the implementation, performance enhancement and optimization of FD systems, including important topics such as hybrid FD/HD scheme, optimal relay selection and optimal power allocation, etc. Finally, a variety of new directions and open problems associated with FD technology are pointed out. Our hope is that this treatise will stimulate future research efforts in the emerging field of FD communication

Συγκριτική παρουσίαση των τεχνολογιών 5G και WiFi 6.0

Τα τελευταία χρόνια, μεγάλη σημασία έχει δοθεί στην πέμπτη γενιά ασύρματης ευρυζωνικής συνδεσιμότητας γνωστής ως 5G, η οποία υπόσχεται μια σημαντική αναβάθμιση στη ποιότητα και στη χωρητικότητα των κινητών ευρυζωνικών υπηρεσιών αλλά και ένα γενικότερο τεχνολογικό άλμα με τη παροχή μιας πληθώρας νέων δυνατοτήτων. Παραδόξως, έχει δοθεί λιγότερη προσοχή στο Wi-Fi 6, το νέο πρότυπο 802.11ax της IEEE στην οικογένεια τεχνολογιών ασύρματου τοπικού δικτύου, με χαρακτηριστικά που στοχεύουν στα ιδιωτικά, ακραία δίκτυα, υποστηρίζοντας υψηλές ταχύτητες, χαμηλή καθυστέρηση και χαμηλή ενεργειακή κατανάλωση. Αυτή η εργασία εξετάζει την καταλληλότητα των κυψελωτών και των Wi-Fi δικτύων στην παροχή υψηλής ταχύτητας ασύρματης σύνδεσης στο διαδίκτυο. Και οι δύο τεχνολογίες φιλοδοξούν να προσφέρουν σημαντικά βελτιωμένη απόδοση, πολύ πιο γρήγορη ασύρματη ευρυζωνική σύνδεση και περαιτέρω υποστήριξη για το διαδίκτυο των πραγμάτων (IoT) και τις επικοινωνίες τύπου μηχανής, τοποθετώντας τις ως τεχνικά υποκατάστατες σε πολλά σενάρια χρήσης. Και οι δύο είναι πιθανό να διαδραματίσουν σημαντικό ρόλο στο μέλλον και ταυτόχρονα να αξιοποιηθούν ως ανταγωνιστικές και συμπληρωματικές τεχνολογίες. Το 5G αναμένεται να παραμείνει η προτιμώμενη τεχνολογία για την κάλυψη μιας ευρείας περιοχής, ενώ η τεχνολογία Wi-Fi θα παραμείνει κυρίαρχη για εσωτερική χρήση, χάρη στο πολύ χαμηλότερο κόστος ανάπτυξης. Ωστόσο, τα παραδοσιακά όρια που διέκριναν τις προηγούμενες γενιές κινητών και Wi-Fi δικτύων θολώνουν, με τη παρουσία πλέον αυτών των δυο τεχνολογιών να συμβάλει στην επίτευξη του στόχου της παροχής προσιτών, αξιόπιστων, και αδιάλειπτων ασύρματων ευρυζωνικών συνδέσεων υψηλής χωρητικότητας.In recent years, significant attention has been directed toward the fifth generation of wireless broadband connectivity known as ‘5G’, currently being deployed by Mobile Network Operators. 5G promises a significant upgrade in the quality and capacity of mobile broadband services but also a more general technological leap by providing a plethora of new capabilities Surprisingly, there has been considerably less attention paid to ‘Wi-Fi 6’, the new IEEE 802.1ax standard in the family of Wireless Local Area Network technologies with features targeting private, edge-networks, supporting high speeds, low latency and low energy consumption. This work revisits the suitability of cellular and Wi-Fi in delivering high-speed wireless Internet connectivity. Both technologies aspire to deliver significantly enhanced performance, enabling each to deliver much faster wireless broadband connectivity, and provide further support for the Internet of Things and Machine-toMachine communications, positioning the two technologies as technical substitutes in many usage scenarios. We conclude that both are likely to play important roles in the future, and simultaneously serve as competitors and complements. 5G is anticipated to remain the preferred technology for wide-area coverage, while Wi-Fi 6 will remain the preferred technology for indoor use, thanks to its much lower deployment costs. However, the traditional boundaries that differentiated earlier generations of cellular and Wi-Fi are blurring. The presence of both technologies should contribute to achieving the goal of providing affordable, reliable, and seamless high-bandwidth wireless broadband connections