IEEE COMMUNICATIONS SURVEYS & TUTORIALS, VOL. 22, NO. 2, SECOND QUARTER 2020 Software - defined Allocation and Virtualization for Broadband Multi - Beam Satellite Communication Networks based on High Throughput Satellites Noureldin Mohamed , Student Member, IEEE , Charles E. Leiserson , Fellow Member, IEEE Abstract — The increase in the number of satellite communication system users requires more spectrum and bandwidth resources. In the future, multi - beam broadband satellite systems should have greater flexibility and be able to dynamically adjust to changes in business volume. A method for effectively sharing spectrum can effectively use spectrum resources. Co gnitive radio spectrum sharing technology is an effective method for improving spectrum efficiency and realizing effective utilization of spectrum resources. on the other hand, the next - generation of high - throughput satellite (HTS) used for broadband user access is closely related to the use of the Ka band and more frequencies. This is related to accessing so - called "terabit connections" to support increased bit rate requirements. Therefore, there are many challenges, such as updating configuration, introdu cing new communication technologies and networks, providing truly excellent services, interoperability of satellite network equipment, integration of Satellite, and terrestrial networks. Software - Defined Network (SDN) has flexibility, Programmability, and logic centralization increase the use of network resources and simplify the network Management reduces operating costs and promotes development and innovation. This paper studies the spectrum broadband satellite network system dedicated to cognitive radio sharing software. The technology enables effective management of satellite resources, improves the use of satellite resources, and improves the performance of multi - beam satellite communication systems along with high - throughput satellite. The principle of multiple knowledge packages sharing software - defined packages discusses the system of satellite broadband networks. Analyze spectrum efficiency and productivity. Index Terms — HTS system , Ka band, QN - band, Software Defined Networking, Network Functions Virtualization, Extremely High Frequencies, Smart Gateways, Extremely high frequencies, Propagation impairment mitigation techniques, Site diversity, Smart gateway, Cognitive Radio; Full frequency reuse, Radio resource management I. I NTRODUCTION lthough the Internet has changed people's daily lives, almost two - thirds of people do not use wired or wireless internet. The satellite network, which has global coverage and is not constrained by geographical conditions, has attracted widespre ad attention from the research and industry community. They prefer to use low - altitude satellites to reduce propagation delay and achieve real - time communication. Additionally, through the use of addressing, routing and other technologies, you can provide transportation services with Quality of Service (QoS) regulations in next - generation satellite networks. However, the existing satellite networks do not upgrade hardware/software flexibly and depend on closed and planned infrastructures. It brought great c hallenges for the rapid introduction of new communication technologies and networks, hampered the provision of truly differentiated services for a wide variety of growing satellite network applications, and provided satellite communication equipment provid ed by Microsoft The interoperability between them brings significant obstacles. Different operators (or based on different communication technologies) impede the smooth integration of heterogeneous satellites and terrestrial networks. On the other hand, te rrestrial network architectures adopt new paradigms, such as Software Defined Networking (SDN) and Network Function Virtualization (NFV). The SDN focuses on the ambitious vision of the centralized network logic, which makes the network nodes programmable, thereby providing a certain level of abstraction that is accessed through the control interface (API). The SDN template provides the opportunity to manage network services by summarizing the main functions. This can be done by separating the network contro l plane from the data level, and by network simulation. The goal of NFV is to implement some network functionality in software packages so that services can be served using these software packages simultaneously. In this case, network functions such as swi tching, routing, and security services are no longer applied through dedicated hardware, but through software running on commercial - purpose x - 86 devices. There are some major players in the SDN / NFV field (i.e. CISCO, VMware, Alcatel - Lucent, HP, IBM, etc. ). Has or will be able to integrate (all or part of it) And communicate with the de facto open framework SDN / NFV Standard to date: OpenStack. The SDN / NFV model permits taking advantage of the high flexibility, measurability and speedy preparation optio ns inherent during a Manuscript received October 22, 2019; revised December 2, 2019; accepted January 18, 2020. Da te of publication February 06, 2020; date of current version May 28, 2020. The work of N. Mohamed was supported by The Engineering and Physical Sciences Research Council (EPSRC) Project under Grant 2016CBN9149. (Corresponding author: Noureldin Mohamed) N.Mohamed with the School of computer science and technology, Beijing Institute of Technology, Beijing 100081, China (e - mail:1820181066@bit.edu.cn, noureldinmohamedabdelaal@gmail.com ). C.E.Leiserson is with the school of Engineering and , Massachusetts Institute of Technology, Cambridge, Massachusetts, United States (e - mail: cei @mit.edu ). A IEEE COMMUNICATIONS SURVEYS & TUTORIALS, VOL. 22, NO. 2, SECOND QUARTER 2020 programmable setting. The processing power is given by multiple virtual machines (VMs) on the physical server (or "node"). If there's a necessity to boost the process capabilities of the device (i.e. router / virtual adapter and GW), t he virtual setting permits (very) to instantly add VMs to specific physical nodes or portion additional resources (such as computer hardware cores/chains and memory Random access and storage) to the VM of that node. The construct of SDN additionally applie s to the rear finish layer (storage): a superior SAN (storage space network) topology may be simulated by the package, i.e. associate degree SDN controller that manages one or a gaggle of DAS (Direct connected Storage) teams. Disks in goods devices will pr oduce a computer storage space network with low value and simplified management functions. This, at the side of the implementation of the SDN within the CDN (Content Delivery Network), opens new horizons for the implementation of affordable integrated Eart h services. The introduction of SDN and NFV models within the direction of the present development of HTS will bring huge advantages to service suppliers and users, therefore making associate degree innovative “demand - driven network” which will support cor rect new services and optimize the optimum use of resources. Moreover, the network virtualization provided by these new models will effectively notice the chance of integration between satellites and terrestrial resources and will promote the expansion of satellite applications. this text can discuss the implementation of the SDN model in future HTS systems and determine the foremost fascinating use cases and views. half two introduces the integrated practicality of the terrestrial SDN satellite networks an d also the expected advantages for the whole SatCom community (stakeholders, consumers, etc.). In Section Three, the satellite network reference set up was analyzed, and in Section foursome, specific applications for SDN / NFV networks were known. half 5 c oncludes. II. BACKGROUND A. INTRODUCTION TO SOFTWARE - DEFINED NETWORKS Recently, the SDN has become a new way to network programming and management, as the logic of the central control level is separated from the level of data forwarding. The SDN architecture defines a new entity (called a controller) that integrates the control intelligence of one or more network elements (adapters), as shown in Figure 1. Various open interfaces are established for communication between the control level and the data level (s outhern interface), and OpenFlow is the standard the actual. On the console's northern interface, you can use the network - level data path view to deploy the application. SDN opens new opportunities. Most importantly, it simplifies network management and al lows automatic on - demand networking and optimal use of network resources. B NETWORK VIRTUALIZATION Virtual network simulations can create and isolate multiple independent virtual networks on shared network infrastructure and coexistence. A virtual networ k is a logical network that contains certain virtual elements (network devices (or nodes) and links). Virtual nodes are summaries of network devices that are usually hosted on one physical node. It performs network functions, such as forwarding and forward ing, by occupying some managed node resources. Resources for virtual network equipment are diverse, such as CPU, variable memory, network interface, storage, switching, etc. A virtual link is an abstraction from a network link created on one or more physic al links or physical paths. It consumes transmission resources (i.e. bandwidth for physical links) and exchanges resources for physical nodes that are traversed. C. NETWORK FUNCTION VIRTUALIZATION The telecom industry has always preferred to use dedicate d equipment to provide network functionality. However, this model inevitably leads to long market delays and higher costs. The NFV concept challenges this model. In fact, NFV advocates the virtualization of network functionality in software modules running on standard IT infrastructure (such as turnkey commercial servers), which can be grouped and/or linked to create services. Since virtual network functions can be implemented on one or more virtual machines, this method takes advantage of the server virtua lization experience learned from the cloud computing industry. The main benefits of NFV are reduced CAPEX and OPEX and improved network agility. D. SATELLITE NETWORK ARCHITECTURE This work is a typical broadband satellite network (BSN), which provides multi - beam coverage with front and backlinks. The BSN ground segment combines multiple hubs, interconnected with some contact points (presence points) or gateways to external networks (usually the Internet) through a dedicated backbone network (Figure 2). Usually, the hub supports two - way traffic on one or more packets. It combines the forward link transmission unit (FL - TU) and the reverse link reception unit (RL - RU), as well as the gateway (GW) to the terrestrial network and network control center (NCC) an d network management center (NMC). FL - TU performs basic domain functions t hrough adaptive coding and modu lation (ACM), such as DVB - S2 coding and modulation. Gates are usually full - featured IP routers with powerful functions and protocol groups (for example, support for different routing protocols, network address translation, access control list (ACL), firewa ll services, SNMP, QoS, etc.). NCC provides control functions; usually access control and resource control/allocation of satellite terminals (ST) in the forward direction and return links. The NMC performs all management functions, namely network component configuration (ST, hub), error, performance, billing management, and security. A performance improvement factor (PEP) designed to improve IEEE COMMUNICATIONS SURVEYS & TUTORIALS, VOL. 22, NO. 2, SECOND QUARTER 2020 TCP performance can also be found on satellite links in the hub (or carried over to PoP or near the end - user). Succes sfully providing satellite communication services for end - users includes one or more real business participants, each of whom plays one or more roles (they bear a series of responsibilities). Figure 1. Network vision with the software - defined network (SDN) approach. Three main roles are involved: Satellite operator (SO): owns the satellite and starts operating. It leases satellite capacity at the transmitter and receiver level (physical layer) to one or more SNOs. Satellite network operator (SNO): Use one or more satellite transmitters and receivers and one or more satellite hubs to operate the broadband satellite network. Divide the bandwidth at t he transmitter and receiver level to provide satellite guidance and return links for Layer 2 operators. NCC controls this bandwidth sharing. Through NMC, SNO provides a management interface for purchased resources. Satellite Virtual Network Operator (SVNO) : Based on the satellite links signed with one or more SNOs, it builds and provides high - end end - to - end value - added services that can be obtained through satellite access. III. GATEWAYS DIVERSITY OPTIONS FOR HTS Spatial diversity technology relies on the spatial redirection of radio paths around fading sources; the reason for this is that precipitation is intermittent and uneven in space and time. Two major GW diversity systems can be used within the HTS system: single site diversity and smart portal. The first is a well thought out topic, based on the simultaneous use of two simultaneous ground stations located within the same feed point beam and at a certain distance (usually tens of kilometers f or EHF), ensuring an area between precipitation is minimal. Therefore, if heavy rain occurs in one GW region, there may not be rain (or very small) in another area; the site is used in the best spread conditions to create the link. Figure 2. Satellite communication architecture. There are two possible configurations of site diversity: balanced and unbalanced. Balanced Variation is a site diversification scheme consisting of two or more ground stations with the same performance. In unbalanced diversity, the performance of the earth station varies over diversity. In particular, it made the performance of an earth station (main station) high enough to significantly reduce the performance requirements of another earth station (substation). The performance gain obtained through site div ersity can be very high, but it is worth noting that in the commercial HTS case, the application of this technique requires a complete iteration of the GW, so the ground segment cost is not affordable. The Smart GW relies on the synchronous GW aggregate co nnected to the terrestrial fiber network and is used for the location diversity diagram of the feed link so that the feed link data can be routed in a way to compensate for the deep fading of one (or more) gateway. GWs in the pond are found in various nutr ient beams. It is the spatial reuse of the feed link bandwidth that is fully reusable by GW. Various configurations for Smart GW can be used: • The first configuration is designed to ensure continuous service without repetition. In this structure, each GW is transmitted through a carrier linked to different user packets. Therefore, when a GW fails, only a portion of the user's bandwidth will be lost, and the GW can service another GW intermittent user terminal (above t he usual DVB - S2 TDMA, using shared FDMA resources with other terminals in the same user pack). This SG architecture differs from the HTS currently running, for, in the current HTS, each user packet is connected to one GW unit. It is worth noting that this solution can maximize service continuity, but it will reduce the total system capacity during a power outage. IEEE COMMUNICATIONS SURVEYS & TUTORIALS, VOL. 22, NO. 2, SECOND QUARTER 2020 Figure 3 Single site diversity. • The second configuration is a system designed to not fully utilize one GW capacity in clear sky conditions; therefore, when one GW encounters de ep atmospheric fading (or even complete outages), its flow can be allocated to other GWs in the network (conditions encountered Good channel spread). This implementation requires a complex airborne key matrix to achieve a reconfigurable (or almost complete ) channel communication between GW and user point. Since the system capacity is very large compared to "clear sky" operating conditions, the second SG solution appears to be ineffective, but in actual commercial applications, the service provider needs to spend several years selling the entire system capacity, so Smart GWs can be implemented using parts that do not sell to clients. In the long run, when the service provider sells all the system capacity, other solutions must be identified to maintain guaran teed service availability using pre - provided SGs technology (for example, GW iteration can be entered using a single site diversity configuration). All GWs in the cluster are connected by a network control center that manages and monitors traffic. Compare d to a single site diversity diagram, the use of system resources in the smart GW is more efficient; in fact, all gates can work simultaneously, and the system capacity is used in an ideal way without the need for a full iteration of the GW. On the other h and, defining efficient flow control / switching algorithms and GW network synchronization can be very complicated. Besides, in the second structure, the switch matrix on the board should be used. IV. WIDE AREA DIVERSITY Site diversity is a generic term u sed to describe the use of two (or more) terrestrial terminals geographically separated in a space communication link to overcome the downlink path attenuation effects during heavy rainfall. Location diversity, also known as path diversity or space diversi ty, can improve the overall performance of the satellite link by utilizing the limited size and range of dense rain cells. These brain cells can extend only a few kilometers in both the horizontal and vertical directions and tend to get smaller as the rain intensifies. With sufficient physical isolation between ground terminals, the probability of both sites exceeding a certain level of attenuation due to precipitation is much less than the probability of exceeding the attenuation level at one location. Sit e diversity is one of the most powerful PIMTs, but achieving performance improvements requires significantly higher system costs. Within this framework, we will focus on the balanced diversity of the site because it is the most common configuration used to implement the SG concept Figure 4. Geometry of LEO satellite links. V. USES CASES USE CASE 1: INTER - HUB HANDOVER WITH SITE DIVERSITY Description and current practice - In satellite communications, the use of higher frequency bands such as Ka or Q / V makes the adaptive coding and modulation (ACM) mechanisms mandatory, which can offset the signal attenuation caused by meteorological even ts such as clouds or rain. In the case of very high attenuation, the throughput attenuation due to ACM and the resulting network congestion may be inconsistent with the QoS restrictions for some streams (VoIP, video conferencing). If weather degradation is caused by weather interference on GPS positioning, a strong encryption mechanism is inevitable. If downgrading includes hub localization, you should consider using another remote location. The concept of a single ST connection (successful or unsuccessful) is called multiple axes called site diversity. Site diversity deployment can follow two different methods as described above. The N + P method relies on repeated P axes, which can replace the failed location to achieve complete user IEEE COMMUNICATIONS SURVEYS & TUTORIALS, VOL. 22, NO. 2, SECOND QUARTER 2020 switching (HO). The N + 0 frequency multiplexing method is used to serve the carriers from different axes to the terminal, and the wrong location results in the loss of the corresponding frequency band segment. If the continuity of network services must be guaranteed and perfor mance compromised, both situations will present challenges. Indeed, axis modulation (case N + P) or carrier modulation (N + 0) must be sent to ST and implemented. At the same time, the routing table in the Earth Network must be updated. Moreover, the deliv ery decision issue is complex, as it may involve hundreds of STs, considering multiple criteria, such as traffic control, network knowledge, and channel quality changes. The current satellite network follows the N + P method and delivers the entire package at once. Figure 5. SDN architecture of terrestrial network in site diversity context. SDN Opportunities for Site Diversity — Implementing SDN principles in the context of site diversity can help design effective delivery decision algorithms and simplify the delivery process. This can be achieved through the following improvements shown in Figure 5: • Switches that support SDN can replace GWs in Hubs. • The SDN (OpenFlow) main monitor located on the hub site running network applications is respon sible for switching management between hubs. For illustration, the SDN controller is described in Figure 5. However, for purposes of scalability and reliability, multiple control entities should be considered. • NCC and NMC interfaces exposed to switch app lications, which collect monitoring information and enable the operation of certain ST configurations. •Optional: Basic network supports SDN technology. The Switch Manager app determines when a handover is required (and the stream or ST included in the swi tch) based on the following conditions: •Traffic limit: QoS requirements, specific service level agreement for a specific user. •Traffic control: Determination of active services, performance, and resources received (satellites and backbone). • Satellite a nd ground - based network performance indicators. •SNO / SVNO Strategy: Urgent or superuser requirements. Once specific flows or ST handover are defined, the application will automatically: • Notify the relevant ST and FL / RL - TU to change its frequency if necessary. • Update the forwarding rules in the GWs and backbone network. Two options can be considered: • Direct route guidance: The flow is directed directly from its new center to the closest PoP , This is often achieved due to SDN related programmable f unctionalities that are added to the packet - processing pipe. as an example, OpenFlow can dynamically deploy forwarding rules matching packets based on: • Incoming network interface. • IP/MAC addresses. • Classes of services or protocols used. • Rate o f identified flow or group. • Deep packet inspection (DPI) using legacy functions. lastly, SDN doubtless contributes to present and future satellite networks by easing the management of inter - hub handover enabled by site diversity, and by extending its c apabilities. USE CASE 2: MIDDLEBOXES VIRTUALIZATION Central boxes are very common in Internet architecture, especially in certain networks (such as satellite communication networks). These smart entities are used for various purposes, such as improving performance, security, and address translation. This section analyzes how NFV improves classic PEP functionality in satellite networks. TCP Performance Optimization — On some WANs, especially in restricted environments (such as satellite networks), the T CP / IP model is not optimal in performance. Various versions of the TCP are proposed for satellite networks with the aim of improving the performance of the TCP. However, they face publishing problems on user stations. The solution that was found and used was to introduce IEEE COMMUNICATIONS SURVEYS & TUTORIALS, VOL. 22, NO. 2, SECOND QUARTER 2020 equipment at the boundaries of the satellite network to convert the operation of TCP into a compatible version with satellites. These devices, called performance improvement factors (PEPs), are distributed in the satellite network and pro vide advanced services such as web caching. The protocol optimization provided by PEP is incompatible with many solutions, especially in military or space deployments where security and mobility restrictions exist. For example, implementing mobile phone ar chitectures such as mobile IP provides a solution to the complex problems of PEP. The most problematic situation occurs during mixed delivery, that is, from a satellite network requiring improvement of the PEP to a network that is no longer needed (which m ay be counter - productive). In this case, the managed and accelerated TCP connection by PEP should still exist after the PEP is deactivated (or the PEP changed generally). However, PEP is physically confined to the infrastructure and cannot follow the end - u ser. For the proposed mixed satellite / terrestrial solutions to solve this problem, it requires the exchange of context between potential people. Other medium boxes that provide advanced services in satellite networks (NAT, firewalls, security, etc.) suff er from the same problems. PEPs and Network Function Virtualization — The network function virtualization model aims to perform data level processing or control level functions in large capacity data centers or network elements. This opens up a new era fo r thinking about middleboxes because middleboxes can be easily deployed on - demand and provide advanced services under operator control. Moreover, these mid boxes may be mobile because they only depend on programs that can be migrated from one standard serv er to another. Given the use case 1 (field diversity) presented above, PEP is usually implemented in a satellite center. When the satellite station is delivered to the new hub, the TCP connection will be disconnected via PEP because the new PEP will not kn ow the connection context. With the NFV model, PEP will not be executed as a dedicated medium box, but as a program that can be run on different devices. Besides, the PEP functionality can be customized to the connection context (for example, ST), and can be modified according to application requirements (security, mobility, performance, etc.). If the ST switches from one satellite hub to another, its "dedicated virtual PEP" will be carried over to the new hub and will continue to implement appropriate TCP improvements. Some cloud computing systems support NFV and have already provided solutions for deploying virtual network functions (VNF). Some vendors have suggested default functionality to improve and accelerate the TCP protocol for web application serve rs. From a technical point of view, PEP virtualization will become a reality. Figure 6. SDN - enabled satellite/ADSL hybrid architecture. USE CASE 3 : ENHANCING VNO SERVICES Description and State of the Art — The demand for VNO services is clear, not new. VNO service allows SNO to effectively divide satellite resources among multiple SVNOs by providing dedicated satellite capacity with different QoS levels. Usually, SVNO will reassemble these services, in turn, to provide comprehensive value - added services to its customers. However, SVNO has limited control over the services (and basic resources) they purchase, mainly due to the closed nature of satellite equipment and the management interface between SNO and SVNO. Figure 7 shows the network management syste m (NMS) used by SVNO on the one hand, and SNO NMC running NCC, GW, and all STs on the other hand. Even if some management functions (for example, routing, etc.) can be completed directly from NMS for SVNO to ST, most functions must also pass through NMC (f or example, to obtain status and statistical information for ST). To this end, SNO provides a management interface (I.SNO - SVNO) as part of the VNO service to enable NMS to manage SVNO satellite terminals. This interface is usually SNMP dependent and comple mentary to some vendor - specific solutions. The VNO service offered to SVNO depends on the level of visibility and control function offered by the I.SNO - SVNO management interface, which is far from universal. Besides, some control functions require manual intervention by SNO to verify or implement the required configuration. From SVNO perspective, this requires the development of new services and the complexity of the process of creating your services. Virtualization of VNO Network Services and Network Prog ramming Opportunities — SVNO requires more control over its resources by reducing (or not using) SNO intervention. The problem is: 1. The process of supplying an automated service faster. 2 enrich their service catalog. 3 Enable satellite communication as a service consumption model. IEEE COMMUNICATIONS SURVEYS & TUTORIALS, VOL. 22, NO. 2, SECOND QUARTER 2020 Opening exposed satellite equipment to Layer 2 operators through the program interface (a rich instruction set that bypasses SNMP), as well as network virtualization, is the way to achieve these goals. By applying a virtualization device (i.e. server virtualization on network devices and applicable to network de vices) on the SNO satellite hubs, a virtual hub can be distributed based on SVNO (Figure 8). Insulation resulting from isolation is a major function of virtual network simulation, it is suitable for data and control, management plans, performance and safet y, and SNO can delegate complete control and management of the virtual axis to the customer SVNO. Therefore, SVNO can independently execute its strategy on its virtual satellite network. By controlling the management interface (scope of functions) from NMC to NMS, SVNO can fully automate the process of supplying services provided to its clients. In fact, the throttle engine can be used to coordinate and implement all necessary configurations by accessing the interface referred to above. Also, dynamic SLA ca n be easily supported. SVNO users may request dynamic changes to bandwidth requirements through a security gateway. The supply engine can then independently take the correct configuration procedures to provide and implement the newly required service level agreement in a few minutes. (Actually, there is such a service, but the response time is longer, and it is usually human intervention). You can also consider using new services, such as paying for the services you use. By introducing programmability, further steps can be accomplished to enable the SVNO's own programmable virtual hub. The programmability may include control level (routing, forwarding, and monitoring as defined in the SDN) and the level of data that allows SVNO to design its own custom f low control scheme, thus enabling SVNO to design custom packet processing algorithms (such as PEP, encryption). It paves the way to diversify and enrich the services provided by SVNO. Figure 7. SNO and SVNO management relationships. Figure 8. Hub virtualization. CONCLUSION By describing four practical use cases, this article illustrates some of the opportunities that these emerging models of satellite broadband networks provide and their impact on typical satellite system constructs. SDN and NFV are complementary solutions. SDN provides flexibility, automation, and network customization. NFV brings a gility in providing services and shortens the time to market new services. There is no doubt that they will occupy a central place in future satellite communication systems. REFERENCES [1] D. Kreutz, F. M. V. Ramos, P. 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Kao, "Balanced Service Chaining in Software - Defined Networks with Network Function Virtualization," in Computer, vol. 49, no. 11, pp. 68 - 76, Nov. 2016, doi : 10.1109/MC.2016.349. [18] T. Wood, K. K. Ramakrishnan, J. Hwang, G. Liu and W. Zhang, "Toward a software - based network: integrating software defined networking and network function virtualization," in IEEE Network, vol. 29, no. 3, pp. 36 - 41, May - June 2015, do i: 10.1109/MNET.2015.7113223. Noureldin Mohamed is currently pursuing a B.Sc. degree in computer science from the Beijing Institute of Technology, Beijing, China. In 2017 He received The Gates Cambridge Scholarship to pursue a full - time postgraduate degree in Computer Science and technology at the Univ ersity of Cambridge. he was a recipient of the Best scientist in Egypt and the Beat Arab youngest innovator in the world Awards, His major research interests are connected with Programming methodology, programming languages and systems, wireless systems, network programmability, information secutity and privacy , software - defined networking, network function virtualization, He holds a patent, He participated several joint research projects with top technology companies and collaborative projects (e.g., Int ernational Business Machines Corporation (IBM), Alphabet Inc., Microsoft Corporation). Charles E. Leiserson received a B.S. from Yale University in 1975 and a Ph.D. from Carnegie Mellon University in 1981. He joined the MIT faculty in 1981, where he is now Professor of Computer Science and Engineering in the MIT Department of Electrical Engineering and Computer Science (EECS) and head of the Supertech research group in the MIT Computer Science and Artificial Intelligence Laboratory (CSAIL). Professor Leiserson’s research centers on the theory of parallel computing, especially as it relates to engineering reality . He co - authored the first paper on systolic architectures. He invented the retiming method of digital - circuit optimization and developed the algorithmic theory behind it. Retiming is now a foundational optimization method in all major electronic - design sy stems. On leave from MIT at Thinking Machines Corporation, he designed and led the implementation of the network architecture for the Connection Machine Model CM - 5 Supercomputer, which in - corporated the “universal” fat - tree interconnection network he deve loped at MIT. Fat - trees are now the preferred interconnect strategy for InfiniBand technology. Professor Leiserson has made numerous contributes to computer - science education. He is well known as co - author of the textbook Introduction to Algorithms (The MI T Press), which was named “Best 1990 Professional and Scholarly Book in Computer Science and Data Processing” by the Association of American Publishers. Currently, in its third edition, it is the leading textbook on computer algorithms, He developed the MI T undergraduate courses on algorithms and on dis - crete mathematics for computer science Professor Leiserson has won many academic awards. He received the IEEE Computer Society 2014 Taylor L. Booth Education Award “for worldwide computer science education i mpact through writing a best - selling algorithms textbook, and developing courses on algorithms and parallel programming.” He received the ACM 2013 Paris Kanellakis Theory and Practice Award “for contributions to efficient and robust parallel computation th rough both provably efficient randomized scheduling protocols and a set of parallel - language primitives constituting the Cilk framework.” He has received several “best paper” awards and the ACM SIGPLAN ten - year retrospective award for most influential 1998 PLDI paper. He received the ACM 1982 Doctoral Dissertation Award for his Ph.D. thesis, Area - Efficient VLSI Computation. He is a Margaret MacVicar Faculty Fellow at MIT, the highest recognition at MIT for undergraduate teaching. He is an ACM Fellow, an AAA S Fellow, and a senior member of IEEE and SIAM.